An atomic force microscope (“AFM”) based interferometer, uses a light source, and a splitting optical interface, splitting the light beam into a signal light beam and a reference light beam. Both the signal and reference light beams are focused in the vicinity of an AFM cantilever. A beam displacer introduces a lateral displacement between the signal light beam and reference light beam, the lateral displacement being such that, in at least one plane between the beam displacer and the focusing lens structure, the center of the signal light beam is separated from the center of the reference light beam by more than half a sum of their beam diameters on that plane. A detector operates to determine differences in optical path length between the signal light beam and reference light beam to determine information about movement of the cantilever.

Atomic force microscopes (AFMs) employ a microscopic cantilever to convert nanoscale forces between a sharp tip on the cantilever and a sample under study into a measured displacement of the tip. While numerous technologies exist for sensing the deflection of +the cantilever, most AFMs have adopted technologies that reflect a focused light beam off the back of the cantilever as these techniques provide high sensitivity, low noise, and ease of use. These optical methods will broadly be divided into two categories in this document: interferometric detection methods and variants of the optical beam deflection (OBD) method.
Thanks to its design simplicity, high sensitivity and good noise performance, most commercial AFMs have adopted the OBD method. In this method, the reflected light beam is directed towards a split photodetector that allows the measurement of the angular deflection of the cantilever. Using a four-quadrant photodetector allows the measurement of angular deflection in two dimensions, referred to as normal and lateral deflection. The lateral deflection is particularly of interest to researchers studying tribology.
However, the angular deflection of the cantilever measured by the OBD method is an indirect measure of the tip displacement. Consequently, numerous calibration methods have been devised to infer the tip displacement from the photodetector signals. Despite careful calibration of the measured cantilever angular deflection into a tip displacement, it may be difficult to reduce the calibration error below 10%. Since there is a lack of an easily accessible standard for many cantilever measurement modes, errors are often not apparent to the user. In this case, large and systematic errors may be present in the signal, yet the user may mistakenly believe that the OBD angular deflection signal represents the true cantilever tip displacement.
Another limitation of the OBD method is that optimal signal-to-noise ratio (SNR) is achieved when the light spot size is matched to the cantilever size. This makes it difficult to achieve optimal SNR with one instrument on a variety of cantilevers. For a given spot size, larger cantilevers will have higher noise. Furthermore, some cantilevers have a triangular shape with a hollow base such that the light spot must be limited in size and therefore provide suboptimal SNR.
On the other hand, interferometry is an alternative optical method that directly measures the displacement of the cantilever end, which is directly related to the displacement of its tip. This enables researchers to measure the quantity of interest—tip displacement—without the need for additional calibration methodologies that are time consuming and may be highly inaccurate. Since the calibration is based on the wavelength of light, the calibration errors can be reduced to below a few percent. Furthermore, interferometry can achieve better noise performance than OBD method because the light spot size does not need to be matched to the size of the cantilever to optimize SNR. In other words, the displacement of cantilevers of various shapes and sizes can be measured with high SNR using a small focused light spot.
Whereas there is no shortage of academic papers about designs of interferometric AFMs and their advantages, commercial AFMs have not widely adopted such technologies in the mainstream due to their complexity. Fiber-based interferometers have also been widely adopted by academic researchers; however, such interferometers lack the ease of use expected from commercial AFMs because of the painstaking positioning of the fiber near the cantilever and limited optical access.
Typical interferometers that enable high quality optical access to the measured target object, as well as ease of use, introduce a signal laser beam through an objective lens; meanwhile, the reference light beam is reflected off a reference object, such as a mirror, at some distance from the target object. Typically, the reference light beam does not exit the optical system of the interferometer. Such interferometers can be used to measure vibrations of the target object, but suffer from very poor stability at low frequencies, as the path of the signal light beam and reference light beam are very different and therefore subject to different thermal drift and vibrations. These artifacts are indistinguishable from the displacement of the target object. To reduce this problem, a whole class of differential interferometers have adopted a design principle where the signal light beam and reference light beam both traverse the objective lens. The signal light beam is focused on the target object, and the reference light beam is focused on a reference object that is near the target object. The difference between the positions of the target object and the reference object becomes the measured interferometric signal. Maintaining the signal and reference light beams in proximity to each other rejects most of the undesirable drift and vibrations of the instrument through the common-mode rejection principle known to those skilled in the art. Since such differential interferometer designs for AFM, in the prior art, are reliant on birefringent prisms located near the cantilever, they greatly hinder the optical quality of imaging through the objective lens, and consequently they may have poor ease of use. Alternatively, other prior art designs place birefringent prisms at the back focal plane of an imaging lens, thereby also preventing high quality optical access to the target object. Therefore, there is a tradeoff between high-performance differential interferometry in the context of AFM versus ease of use and high-quality optical access to the cantilever.
A clear difference between AFMs based on the OBD method and interferometric methods is the requirements of the light source. Interferometers used for AFM make use of high-coherence laser sources, such as a Helium-Neon (HeNe) laser or a laser diode, as the light source—thereby ensuring a high contrast interferometric signal. Also, the narrow spectral bandwidth of such laser sources prevents any loss in signal contrast that may be caused by the dispersion of the optical glasses used in the optical design. On the other hand, because OBD AFMs do not rely on the coherence of the light source, they may also employ either high-coherence laser sources, or they may instead employ low-coherence sources such as superluminescent diodes (SLDs). The benefits of using low-coherence sources include better long-term stability of the measurement and reduction of measurement artifacts caused by the undesirable interference of back-reflections, for example. For these reasons, it is known to anyone skilled in the art that superluminescent diodes are preferred for certain experiments using OBD AFMs where back-reflections may cause artifacts, while high-coherence lasers are required for interferometric AFMs.
On the other hand, SLDs may have higher noise relative to lasers, especially at high frequencies (U.S. Pat. No. 8,370,960B2). For this reason, some manufacturers of OBD AFMs offer the option to select from a SLD light source or a laser diode light source. Depending on the experiment that the OBD AFM will be used for, it may be more beneficial to take advantage of the lower noise of a laser diode, or the reduction in back-reflection artifacts of a SLD.
Unlike AFMs based on the OBD method, interferometric AFMs have seen a wide variety of different implementations throughout the years. The simplest implementation of an interferometer is the Michelson interferometer, invented in the 1880's. It remains the basis behind much of today's interferometric technology.
FIG. 1 depicts a simple design of a Michelson interferometer in the context of AFM. A laser 010 is coupled into a polarization-maintaining optical fiber 020 that ends with an optical fiber connector 030. The laser light diverges out of the fiber end. The source light beam 040 is collimated from the diverging light by a collimating lens 050. The diameter 060 of the collimated source light beam 040 is determined by the focal length of the collimating lens, along with the divergence of the light beam exiting the optical fiber 030. A polarizer 070 is used to ensure that the polarization is highly linear and orientated preferentially relative to the remainder of the optical system at an optimal angle to maximize the measurement sensitivity. Such a polarizer may be an absorptive film polarizer, a wire grid polarizer, a polarizing cube beamsplitter (as drawn), or any such optical component with a function to transmit or reflect a single linear state of polarization.
Alternatively, the optical fiber can be omitted, and the collimated light beam emitted directly from a free-space laser source, such as a Helium Neon laser or laser diode, can be used in place of a fiber-coupled laser.
The collimated light beam is split up into two light beams by a half-silvered mirror 080 or any equivalent optical beamsplitter. The two light beams will be referred to herein as the signal light beam 090 and the reference light beam 100. Note that some people refer to the "signal" light beam as the "measurement" light beam.
The signal light beam 090 that is reflected off the half-silvered mirror 080 is focused through a microscope objective lens 110 onto a microscopic cantilever 120 (the target object) which is tethered to a cantilever support chip 130 for handling purposes. The diameter 062 of the signal light beam 090 is shown to decrease as the light reaches the cantilever. A cantilever support chip is the macroscopic object that AFM user touches, typically with tweezers, in order to introduce the cantilever into the AFM and secure it by holding the cantilever support chip down using some clamping mechanism. The cantilever support chip is typically on the order of a few millimeters in length and width, and usually less than a millimeter thick. The focused signal light beam 090 reflects off the cantilever and returns through the objective. The objective lens collimates the signal light beam 090 and that beam then returns to the half-silvered mirror 080.
The reference light beam 100 that is transmitted through the half-silvered mirror 080 reaches a reference mirror 140. The reference mirror 140 can be moved by a displacement mechanism 150 that is either manual or automated to some degree. The reference light beam that is reflected off the reference mirror returns to the half-silvered mirror 080. Tip and tilt adjustment mechanisms may be required for the reference mirror 140 in order to ensure that the returning reference light beam 100 spatially overlaps with the signal light beam 090, as described next.
Both returning light beams are recombined at the half-silvered mirror 080. A portion of each beam is recombined into the recombined light beam 200 and directed towards a light photodetector 160. The remaining fraction of the returning light beams returns along the light path of the source light beam 040 towards the light source, because the law of conservation of energy requires that the total amount of light remains unchanged. The amount of light reaching the light photodetector 160 is a sinusoidal function of the difference in the optical path length traversed by the signal light beam 090 and the optical path length traversed by the reference light beam 100, and the periodicity of that sinusoidal function is λ/2 as determined by the wavelength λ of the laser source. This is shown in FIG. 1b. Note that the optical path length of the signal light beam 090 includes the sum of the path lengths along the incoming part, before reflection from the cantilever, added to the sum of the path lengths along the returning part (after reflection from the cantilever). Similarly, the optical path length of the reference light beam 100 is the sum of the incoming and returning optical path lengths.
To optimize sensitivity, the displacement mechanism 150 attached to the reference mirror 140 is adjusted so that half the light returns to the source, and half the light reaches the light photodetector 160. This condition, herein referred to as a "centered interferometer", can be achieved by displacing the reference mirror 140 by at most λ/4. This mechanism is necessary because, when either all or none of the light reaches the light photodetector 160, the sensitivity goes to zero, such that no signal can then be detected. Also, the position of maximum sensitivity for the interferometer coincides with the position of maximum linearity, where the sinusoidal response function is locally linear. That is, the signal response to a change in cantilever displacement will be most linear if the interferometer is centered by appropriate positioning of the displacement mechanism 150.
More generally, the prior art teaches the advantages of having a means for tuning or modulating a phase difference between the signal light beam 090 and the reference light beam 100. While the displacement mechanism 150 is one way of achieving this, in other cases a liquid crystal device is used to tune or modulate a phase difference between two light beams. Note that to operate an interferometer in the "centered interferometer" condition, the means for tuning the phase difference must be maintained in the correct state. If the tuning means is an electrically activated mechanism such as a piezoelectric element or liquid crystal device, it must remain continuously activated or energized throughout the interferometric measurement. This may introduce noise and/or drift into the measurement.
By translating the displacement mechanism 150 through roughly one wavelength cycle, the sensitivity of the interferometer may be calibrated if the wavelength of the laser source is known. At that point, any change in power at the light photodetector 160 can be calibrated into an accurate displacement measurement of the cantilever tip, in units of meters.
The simple Michelson interferometer design depicted in FIG. 1 has a major drawback: half the light returns into the laser source which can cause lasing instabilities. Such instabilities result in optical power fluctuations that erroneously may resemble a cantilever displacement as measured by the light photodetector 160. A change in power is indistinguishable for a cantilever displacement for this design. To reduce lasing instabilities, a Faraday isolator 170 may be installed along the optical fiber as shown in FIG. 2. Alternatively, for a free-space laser, a free-space isolator may be used with similar benefits.
This interferometer arrangement does not allow for a viewing system with access to the cantilever. The alternative arrangement shown in FIG. 3 uses a beamsplitter 180 that is added between the clean-up polarizer 070 and the half-silvered mirror 080 of the design of FIG. 2. This creates visual access for a camera system 190 that can be used to create an image of the cantilever and focused laser spot seen through the microscope objective 110. The camera system 190 typically includes an image sensor, lenses to focus parallel light to the image sensor, a white light illumination system, and a beamsplitter to introduce the illumination light. These elements may be disposed in various ways, modified, or omitted, depending on the characteristics of the microscope objective 110 and the intended applications of the AFM. While allowing access for the camera system 190, the half-silvered mirror 080 also returns both the signal light beam 090 and reference light beam 100 towards the beamsplitter 180, which then reflects a portion of the light towards the light photodetector 160. Note that, in this case, the recombined light beam 200 that will be measured is returned along the source light beam 040 before being redirected to the light photodetector 160. As before, the optical power at the light photodetector 160 is a measure of the cantilever displacement and varies sinusoidally with respect to cantilever displacement. In a different arrangement, the positions of the light photodetector 160 and camera system 190 may be interchanged with similar functionality and performance.
The design of this interferometer has a dynamic range that is limited by the wavelength of light λ. The full range of motion of the cantilever displacement is λ/4. At either extreme of this range, the sensitivity goes to zero, and therefore the interferometer cannot measure cantilever displacement at these positions. In practice, the usable range of the interferometer is much smaller than λ/4, especially if high accuracy and low noise is desired and non-linearities are to be avoided.
The limited dynamic range of the interferometer can be overcome by quadrature detection, such as used in U.S. Pat. No. 6,020,963. Instead of monitoring the optical power in the path of the recombined light beam 200, the polarization state of the recombined light beam 200 is used to measure the optical path difference between the path of the signal light beam 090 and the path of reference light beam 100. Measuring the polarization state is more involved than simply measuring an optical power using a photodetector. This measurement scheme is employed by the design of FIG. 4.
Rather than splitting the source light beam 040 into two paths using a half-silvered mirror 080, the signal light beam 090 and reference light beam 100 in a quadrature interferometer are generated by splitting the source light beam 040 into two orthogonal polarization states using a polarizing beamsplitter 210. When both signal light beam 090 and reference light beam 100 are recombined into the recombined light beam 200, the optical power does not change as a function of cantilever displacement as it does in a Michelson interferometer. Rather, the polarization state changes between linear, elliptical and circular as a function of cantilever displacement. The degree of ellipticity of the light beam polarization state (of which linear and circular polarization are limiting cases) is directly related to the cantilever displacement. A portion of the recombined light beam 200 that is reflected by the polarizing beamsplitter 210 can be analyzed to determine the degree of ellipticity of its polarization by using a quadrature phase analyzer 220.
One possible configuration of a quadrature phase analyzer is shown in FIG. 4b. It involves splitting the light beam into two arms using a non-polarizing beamsplitter 230. Along one arm, referred to as the "in-phase" arm, the two polarization states are mixed using a half-wave retardation plate 240 with its birefringence extraordinary axis rotated to 22.5° with respect to the polarization axis of the signal light beam 090 or the polarization axis of the reference light beam 100. Next, a polarizing beamsplitter 250 is used to direct half of each of the signal light beam 090 and reference light beam 100 towards two photodetectors 260 and 262, such as in U.S. Pat. No. 6,020,963. Along the other arm, referred to as the "quadrature" arm, the two polarization states are mixed using a quarter-wave retardation plate 270 with its birefringence extraordinary axis rotated to 45° with respect to the polarization axis of the signal light beam 090 and polarization axis of the reference light beam 100. In this arm, a polarizing beamsplitter 280 is also used to direct half of each of the signal light beam 090 and reference light beam 100 towards two photodetectors 264 and 266.
The difference in optical power between the photodetector 260 and the photodetector 262 from the in-phase arm is calculated, and this difference is divided by the sum of both photodetector optical powers; this normalized difference becomes the in-phase signal I. Analogously, the quadrature signal Q is measured as well using both photodetectors 264 and 266 in the quadrature arm. Plotting Q versus I results in a Lissajous plot, as shown in FIG. 4c. In an ideal interferometer, the response is a unit circle 284. In that case, any optical path configuration between signal light beam 090 and reference light beam 100 at any instant in time results in a point on the unit circle, referred to as the phase state point 290. A vector 286 can be defined between the origin point of the Lissajous plot and the phase state point 290. The angle φ between this vector and the x-axis of the Lissajous plot can be calculated using the two-argument arctangent function, namely
          φ    =         atan          2                (             Q       ,       I            )               ,      where               atan        2             (           Q      ,      I          )          ≡            arctan          (           Q      I          )        +         m          π          and both the integer m and the branch of the arctangent function are chosen to give a result that is continuous over an interval of width 2π such as φ∈(−π, π]. This two-argument form of the arctangent function, a tan 2, is known to those skilled in computer programming; it appears in the FORTRAN language, the Perl language, and standard math libraries for Java, C, .NET, and Python.
As the cantilever is displaced by λ/2, the phase state point 290, as measured by the quadrature phase analyzer 220, goes around the Lissajous by one full circle. The angle φ is a direct measurement of the phase difference between the signal light beam and the reference light beam, and can be used to infer the cantilever displacement d by
   d  =              λ           4            π            n                 φ      =            λ           4            π            n                 atan        2                   (             Q       ,       I            )          .          where n is the index of refraction of the medium surrounding the cantilever. In other words, the change in optical path length of the signal arm caused by a displacement of the cantilever results in a phase difference between the signal light beam and the reference light beam that is measured as a change in angle on the Lissajous plot. To avoid discontinuities in the displacement signal d, the output of the function a tan 2 should be unwrapped using methods known to those skilled in the art. This unwrapping is particularly important if the displacement signal will vary over a range greater than λ/2.
Due to imperfections of the optical components and the optical system assembly, the response to cantilever displacements measured by the quadrature phase analyzer 220 is generally an ellipse 282 on the Lissajous plot rather than an ideal unit circle 284. Simply assuming an ideal response results in cyclical error of the reconstructed displacement signal. To prevent cyclical error and ensure high accuracy measurement of the cantilever displacement, the measured response on the ellipse 282 can be corrected to infer the corresponding ideal-unit-circle 284 response of the system by the following calibration procedure. The model used for correcting deviations from ideal circular Lissajous is an elliptical Lissajous model, such as presented in Bellon et al., Opt. Commun. 207, 49-56 (2002). Measuring the five parameters that define the size, location, and angle of the ellipse involves modulating the optical path difference between the signal and reference arms (by displacing the cantilever deliberately, for example) and recording a Lissajous shape. Then, an elliptical function is fit using non-linear least-squares method to determine the most accurate parameters that describe the Lissajous shape. Subsequently, these recorded five parameters are used to interpret the photodetector responses as an accurate cantilever displacement. It may be necessary to perform this calibration procedure before every experiment since aligning the AFM may change one or more of these five parameters.
Generating this cantilever displacement signal from both the I and Q signals requires a non-linear calculation that can be performed using digital electronics, such as a field-programmable gate array (FPGA). The calculation must be performed at a frequency much higher than the cantilever displacement that is being measured in order to reconstruct an accurate cantilever displacement signal.
The primary advantage of the quadrature analyzer scheme is that the signal dynamic range can now exceed λ/4, while maintaining the low-noise performance irrespective of cantilever displacement—within some limit set by the optical system. Furthermore, the signal linearity does not depend on the starting condition of the interferometer, and the linearity is not limited to a displacement <<λ/4. In other words, the interferometer does not need to be "centered" as described earlier because any starting point in the optical path difference between paths of the signal light beam 090 and reference light beam 100 is equivalent and allows for high-linearity and low-noise measurements.
Many configurations of the quadrature phase analyzer 220 have been proposed. Some place the quarter-wave plate before the first beamsplitter (TaeBong Eom et al., Meas. Sci. Technol. 12, 1734 (2001)). Some omit the half-wave retardation plate by rotating the quadrature phase analyzer 220 mechanically by 45° around the optical axis of the light beam (Bellon et al., Opt. Commun. 207, 49-56 (2002)). Other use birefringent crystals instead of polarizing cube beamsplitters (Paolino et al., Rev. Sci. Instrum. 84, 095001 (2013)). Other designs only use a total of two photodetectors, one in each arm, to perform the polarization measurement (Weber et al., Rev. Sci. Instrum. 90, 083503 (2019)). More involved designs (US 2006/0087658A1) generate four phase-shifted signals (0°, 90°, 180°, 270°) that all pass through polarizers prior to reaching respective photodetectors with the goal of reducing common-mode errors at the expense of light lost at the polarizers. Each configuration has some trade-off between performance and manufacturing simplicity.
One disadvantage of the design in FIG. 4 is that it is not differential. Therefore, any mechanical motion, such as vibration or thermally-induced drift, in either arm (signal light beam 090 or reference light beam 100) can be erroneously perceived as a cantilever displacement. In addition, the longer the path lengths of the signal light beam 090 and reference light beam 100, the more prone the system becomes to these sources of error.
In prior art, several differential-interferometer configurations have been proposed to reduce the optical path difference between the paths of both polarization states by using birefringent materials close to the cantilever (Schonenberger et al., Rev. Sci. Instrum. 60, 3131 (1989)). This is shown in FIG. 5, where a calcite window 300 is placed close to the cantilever to split the source light beam 040 into two parallel beams with orthogonal polarization states. A disadvantage of this design is the presence of a fragile crystal, easily damaged by liquids, near the cantilever. Also, the camera view of the cantilever and sample has double vision due to the birefringence of calcite, since information from light with different polarizations is offset differently at the camera. Because the source light beam 040 is split into signal light beam 090 and reference light beam 100 near the cantilever, the polarizing beamsplitter 210 used in previous implementations is here replaced by a dichroic mirror 310. The benefits are that all the light coming from the laser is reflected towards the cantilever in the incoming path (prior to reflection from the cantilever) and also fully reflected on the returning path (after reflection from the cantilever), while allowing some light of different wavelengths to reach the camera system 190 for viewing. The diameter 064 of the reference light beam 100 converges in a manner similar to the diameter 062 of the signal light beam 090 because both light beams are focused through the same lens.
The signal light beam 090 travels toward the AFM cantilever, reflects from the cantilever, and then travels away from the cantilever along substantially the same signal light beam path. Where necessary to distinguish them, we refer to the signal light beam before reflection from the cantilever as the "incoming" signal light beam and the signal light beam after reflection from the cantilever as the "returning" light beam. Due to their spatial overlap they are not distinguishable in the figures, and are both designated 090 in the figures. Similarly, the reference light beam 100 is referred to as "incoming" before it reflects and "returning" after it reflects from the cantilever.
FIG. 6 shows a configuration where a split-angle birefringent prism 320 can be used to split both polarization states into two beams that can be focused at two different locations on the cantilever (den Boef et al., Rev. Sci. Instrum. 62, 88 (1991)). In this configuration, it is preferable to use a birefringent prism, such as used in U.S. Pat. No. 5,315,373 that creates two light beams with different angles, such as a Wollaston, Rochon, or Senarmont prism. For reasons explained below, in this design the microscope objective 110 shown in previous figures is replaced by an imaging lens 340. The geometry of the split-angle birefringent prism 320 can be tuned to create angular separation of both light beams that is specifically chosen for the imaging lens 340 in order to achieve a desired separation of the light beams at the cantilever. In order to ensure that both beams have the same incidence angle on the cantilever, the split-angle birefringent prism 320 must be located at the back focal plane 330 of the imaging lens 340.
Note that a microscope objective 110 cannot be used in this arrangement because the back focal plane 330 of the microscope objective 110 is physically located inside the microscope objective 110 and it would not be possible to place the birefringent prism 320 at the back focal plane 330. As such, the imaging lens 340 that must be employed instead is a lower quality lens, such as an achromatic doublet, singlet lens, or other simple imaging lens. Not only does the imaging lens 340 provide a lower quality image of the cantilever and its surrounding, but the split-angle birefringent prism 320 creates two images at the camera system 190 because it splits orthogonal polarizations into separate paths that have different angles.
In this scenario, the signal light beam 090 and the reference light beam 100 follow very similar paths alongside each other. The split-angle birefringent prism 320 geometry and optical properties are optimized in the design stage to create a prescribed separation distance between the signal light beam 090 and reference light beam 100 at the cantilever. In this design the ideal separation distance is slightly smaller than the length of the cantilever that is being measured. The signal light beam 090 is at the cantilever end (target object), while the reference light beam 100 is at the cantilever base (reference object). This allows measuring the displacement difference between these two locations, which changes as the cantilever deflects under sample forces.
It is clear from FIG. 6 that this design cannot readily accommodate cantilevers of various sizes. However, commercial cantilevers are available from roughly 10 μm to 500 μm in length, and in a variety of shapes. One solution is to adopt a beam separation that is larger than the cantilever length such that one beam is focused on the cantilever and the other is focused on the cantilever support chip (Paolino et al., Rev. Sci. Instrum. 84, 095001 (2013)). In the case of a 500 μm long cantilever, this would imply a separation greater than 500 μm, with the reference light beam 100 focused onto the cantilever support chip 130, which is the reference object in this context. However, the thickness of the cantilever support chip can be larger than the depth of field of the laser focused through the imaging lens 340, which leads to a reduced contrast or even total lack of signal. Therefore, it is beneficial to introduce a difference in the axial focus position of the two beams such that each beam can be focused on the surface that it reflects from. As proposed by Cunningham et al. in 1994 (Cunningham at al., Meas. Sci. Technol. 5(11), 1350 (1994)), a defocusing glass window 350 is added to the signal light beam, as shown in FIG. 7, so as to focus the signal light beam 090 onto the cantilever 120 and, simultaneously, the reference light beam 100 onto the cantilever support chip 130. In this arrangement, the deflection of both small and large cantilevers can be measured with the same optical system. Furthermore, the deflection of the cantilever 120 is measured with respect to the stationary cantilever support chip 130, and therefore the measurement does not depend on the separation distance between the signal light beam 090 and reference light beam 100.
Alternatively, Goto et al. have used a birefringent defocusing lens to slightly defocus one of the polarizations in the source light beam 040 in order to change the relative focus of the signal light beam 090 and reference light beam 100 at the cantilever (Goto et al., Rev. Sci. Instrum. 66, 3182 (1995)). A birefringent lens is necessary because both signal light beam 090 and reference light beam 100 are both spatially substantially overlapping, such that standard optics cannot be used on one of those light beams without affecting the other.
Note that the diameter 060 of the source light beam 040 in combination with the focal length of the microscope objective 110 or imaging lens 340 determines the divergence of the focused light beam at the cantilever, the light spot diameter, and the depth of field of the focused light beam. For straight cantilevers that are not curved due to residual or thermally-induced internal stress, a wide range of diameters of the source light beam 040 would result in high contrast signals. That is because the light beams will overlap substantially after reflection off the cantilever 120 and chip 130 and recombination into the recombined light beam 200. Conversely, for curved cantilevers as illustrated in FIG. 7b, the reflected signal light beam 090 will return along a path slightly different from the incoming signal light beam 090 path. Consequently, the signal light beam 090 and reference light beam 100 will only partially overlap when recombined into the recombined light beam 200. This leads to a reduced interferometric contrast, lower signal, and higher measurement noise. However, increasing the diameter of the source light beam 040 ensures more overlap between reference light beam 100 and signal light beam 090 in the recombined light beam 200 leading to a higher signal, and consequently lower noise. In conclusion, choosing a larger diameter of the source light beam 040 makes the system more tolerant to undesirable cantilever curvature.
On the other hand, increasing the diameter of the source light beam 040 results in a decreased depth of field, which makes the system less tolerant to cantilever support chip thickness variability. Errors in in chip thickness, as illustrated in FIG. 7b, may arise due to differences in substrates and micromachining processes used to fabricate the cantilever. The consequence of chip thickness errors is that the returning signal light beam 090 and reference light beam 100 will be defocused with respect to each other when they are recombined into the recombined light beam 200. This leads to a reduced interferometric contrast, lower signal, and higher measurement noise. However, for a given error in cantilever support chip thickness with respect to the design thickness, a smaller beam diameter will lead to a smaller loss of contrast, higher signal, and lower measurement noise. In conclusion, there is a trade-off when choosing the source light beam 040 diameter: a smaller diameter 060 of the source light beam 040 results in more tolerance to chip thickness error but less tolerance to cantilever curvature, and vice versa.
Similarly, a larger beam diameter 060 of the source light beam 040 leads to less tolerance for chip tilt errors. Chip tilt errors, as illustrated in FIG. 7b, can arise due to machining tolerances of the chip holder, for example. Any error in the chip tilt causes a relative defocus between the signal light beam 090 and reference light beam 100 since the two beams are separated by some distance. For any given amount of chip tilt error, the relative defocus between the returning light beams will be larger for larger light beam diameters. In other words, a smaller beam diameter 060 of the source light beam 040 results in more tolerance to chip tilt errors, and vice versa. An appropriate beam diameter 060 of the source light beam 040 must be chosen to compromise between cantilever curvature, errors in chip thickness, and chip tilt. In the prior art, the ability to make these design choices was limited, and therefore it was difficult to customize the characteristics of the interferometer to the desired applications of atomic force microscopy.

Oxford Instruments Asylum Research, Inc.


A positive radiation-sensitive mixture is disclosed containing a compound which forms an acid under the influence of actinic radiation, and an acid-cleavable compound, wherein the acid-cleavable compound is monomeric and contains an acetal group whose aldehyde or ketone component has a developer solubility of about 0.1 to 100 g/l and a boiling point above about 150.degree. C. The mixture does not exhibit different development properties, even at different "holding times", and therefore exhibits a wide processing latitude and makes possible a high structural resolution.

The present invention relates to a positive radiation-sensitive mixture containing a compound which forms an acid under the action of actinic radiation, and an acid-cleavable compound.
Positive radiation-sensitive mixtures in which an acid is formed through the action of actinic radiation on a photoinitiator and the acid then, in a secondary reaction, renders the irradiated regions of an acid-cleavable material soluble in an appropriate developer have been known for some time.
Of the acid-cleavable materials employed hitherto in this area, the following have proven successful:
(a) those containing at least one orthocarboxylic ester and/or carboxamide aceta group, it being possible for the compounds to have a polymeric character and for the groups mentioned to occur as linking elements in the main chain or as lateral substituents, PA1 (b) oligomeric or polymeric compounds containing recurring acetal and/or ketal groups in the main chain, PA1 (c) compounds containing at least one enol ether or N-acyliminocarbonate group, PA1 (d) compounds containing silyl ether groups, PA1 (e) compounds containing siylenol ether groups, and PA1 (f) cyclic acetals or ketals of .beta.-keto esters or amides. PA1 R denotes carboxyl, OR' or SR', PA1 R.sub.1 and R.sub.2 are identical or different and denote hydrogen, chorine, bromine, alkyl, which is optionally substituted by aryl, alkoxy, aryloxy, hydroxyl groups or by fluorine atoms; or alkyl, which is optionally substituted by alkoxy, aryloxy, hydroxyl groups or by halogen atoms, PA1 R' denotes hydrogen, alkyl which is optionally substituted by aryl, alkoxy, aryloxy or hydroxyl groups or by fluorine atoms; aryl which is optionally substituted by alkoxy, aryloxy or hydroxyl groups or by halogen atoms; acyl, alkylsulfonyl, arylsulfonyl, alkoxycarbcnyl, triorganosilyl, triorganostannyl or denotes an alkylene, arylene, bisacyl, sulfonyl, alkylenedlsulfonyl, arylene disulfonyl, diorganosilyl or diorganostannyl group whose second valency is bonded to the 0 atom of a further unit of the formula I, it being possible for the alkylene and arylene groups to be substituted in corresponding manner to the alkyl and aryl radicals, and PA1 n denotes 0 to 3, PA1 where PA1 R.sub.3 denotes alkyl, in particular, (C.sub.1 -C.sub.3) alkyl, or aryl, in particular, phenyl
As components of radiation-sensitive mixtures, acid-cleavable compounds of type (a) are described in detail in EP-A-0,022,571 and DE-A-2,610,842; mixtures which contain compounds of type (b) are described in DE-C-2,306,248 and DE-C-2,718,254; compounds of type (c) are mentioned in EP-A-0,006,626 and 0,006,627; compounds belonging to type d) are presented in DE-A-3,544,165 and DE-A-3,601,264; compounds of type (e) can be found in U.S. application Ser. No. 07/243,819 Now U.S. Pat. No. 4,916,046 (corresponding to German Patent Application P 3,730,783.5), filed simultaneously, now U.S. Pat. No. 4,916,046, issued Apr. 10, 1990: compounds of type (f) are mentioned in EP-A-0,202,196.
In DE-A-2,610,842, compounds containing ortho -ester or -amide acetal groups in a radiation-sensitive copying material are described which are used in the production both of printing plates and microelectronic circuits. Investigations have shown that the resolution which is necessary in the submicron region can only be achieved to a limited extent or not at all, using the acid-cleavable compounds outlined therein, which liberate formates of low water solubility on exposure.
The radiation-sensitive copying materials described in DE-A-2,718,254 are also used for lithographic printing plates and for positive resists. They contain, as the acid-cleavable component, an oligomeric compound containing recurring acetal or ketal units, whose alcohol component must be at least dihydric. In addition to the large range, due to the production process, within which the molecular weight or degrees of polymerization of such polyacetals vary, the danger of introduction of contaminants into the radiation-sensitive mixture is particularly critical in the case of these acid-cleavable compounds since distillative purification is no longer possible. Due to the choice of the aldehyde or ketone components, some of the acetals and ketals described result in mixtures which are difficult to develop or allow only a small process window between irradiation and development, generally between 0.1 and 5 hours. Depending on this "holding time", considerable development rate differences occur in some cases and can extend so far that development is no longer possible at all.
Use of a recording material containing an acid-cleavable material of this type results in an unacceptable variation of the process parameters. In addition, the structural resolution is in most cases in need of improvement; this applies in particular when the acetal is too soluble in the developer, for example, in the case of acetals containing 4-hydroxybenzaldehyde as the aldehyde component.
In addition, it has recently been proposed, in contrast to the prior art, to employ cyclic acetals or ketals of .beta.-keto esters or amides as an acid-cleavable material which is stated to be also suitable for use in photoresists (EP-A-0,202,196). A disadvantage of these photoresists is their low radiation sensitivity.

Positive radiation-sensitive mixture containing monomeric acid-cleavable compound and radiation-sensitive recording material produced therefrom


An apparatus for generating and collecting particulate matter derived from combusting a carbon-containing fuel in oxidizing gas includes a fuel burner housed in a container. The container has a gas inlet, a gas outlet; the gas outlet connects with a conduit for transporting the gas to atmosphere which is associated with means for forcing gas to flow from the gas inlet via the container and the conduit to atmosphere. Located within the conduit is a station for collecting particulate matter from gas flowing through the conduit. The gas flow-forcing means is controlled in response to a detected gas flow rate at the gas inlet to ensure the rate of gas flow at the gas inlet is maintained at a desired rate, thereby to promote particulate matter formation. A method for collecting particulate matter derived from combusting carbon-containing fuel employs the apparatus.

The automotive industry is required to limit certain emissions generated by engines when in use due to the adverse affect such emissions can have on human health and the environment. Such emissions include hydrocarbons, nitrogen oxides, sulphur oxides, carbon monoxide and particulate matter (PM).
One example of an exhaust treatment system component that helps enable the automotive industry to meet emission standards is the Johnson Matthey CRT® system. This technology (disclosed in EP 0 341 832) makes use of a process for combusting diesel particulate deposited on a filter in nitrogen dioxide at up to 400° C., which nitrogen dioxide is obtained by oxidising nitrogen monoxide in the exhaust gas over a suitable catalyst disposed upstream of the filter. The nitrogen monoxide oxidation catalyst can comprise a platinum group metal such as platinum, palladium, ruthenium, rhodium or combinations thereof. The filter can be coated with material that facilitates higher temperature combustion such as a base metal catalyst, e.g. vanadium oxide, La/Cs/V2O5 or a precious metal catalyst.
However, in an effort to continually reduce the adverse effect of engine emissions governments are adopting increasingly strict emission standards, e.g. according to European Union emission standards a diesel powered passenger car produced in 1993 was allowed to produce up to 0.140 g/km of PM (the so-called Euro I Tier Emission Standard), whereas in 2005 the regulated amount was no more than 0.025 g/km of PM (Euro IV Tier) and it is anticipated Euro V Tier could be 0.005 g/km. Therefore an exhaust treatment system that was able to meet the emission standards set for vehicles five years ago is not necessarily capable of meeting the emission standards set to be introduced in the near future. Hence new exhaust treatment systems constantly need to be developed to enable the automotive industry to meet the progressively stricter emission standards. However, as with the development of any new system (or component of a system) such a system needs to be tested in the laboratory before it is put to use in practice. Many tests might be carried out on an exhaust treatment system comprising a catalyst and/or a filter before the system is put into practice, such tests including durability testing, catalyst ageing, filter retention tests, pressure drop loading tests, ageing cycles with regeneration tests, NOx-trap regeneration, soot mass limit tests, poison testing (including sulphation ageing, and testing to see how the catalyst and/or filter reacts to exposure to a range of chemicals such as phosphates, halides, alkaline earth and rare earth compounds), ash loading studies, white smoke tests and the testing of a system when the engine is fuelled with a variety of alternative fuels. Those organisations carrying out such tests include: exhaust system manufacturers (including filter manufacturers, coating companies and canning companies), vehicle manufacturers, consultancies, research institutions and academic laboratories.
Prior art methods of laboratory testing a new exhaust system tend to rely on the use of a bench-mounted vehicular internal combustion engine for prolonged periods of time, which is exceedingly costly. Nonetheless, since it is important that the testing of such a system should mimic the conditions under which the system would be used in practice, and that the PM contacting the system mimic the PM produced by an engine, no reliable alternative was previously available.
DE 37 10 749 C1 discloses an apparatus for simulating deposits of foreign substances contained in gaseous media on functional parts in flow systems, such as the deposit of soot in the air intake systems of engines. EP 1 616 914 A1 discloses an apparatus for producing carbon black with defined properties and for testing filters by passing a gas stream containing carbon black through a filter.

Particulate matter generator and collector


A coated article includes a glass substrate that supports a coating such as a low-E (low emissivity) coating. In certain example embodiments, the glass substrate is formed of a soda-lime-silica based glass composition manufactured using a float process. In certain example embodiments, lithium oxide (e.g., LiO2) and/or potassium oxide (K2O) is used in the soda-lime-silica based glass substrate in order to reduce sodium migration and/or improve surface stability. Such coated articles are useful, for example and without limitation, in architectural, vehicular and/or residential glass window applications.

Coated articles including low-E coatings supported by glass substrates are known in the art. For example, see U.S. Pat. Nos. 6,723,211, 6,686,050, 6,749,941, 6,916,408, and 6,887,575, the disclosures of which are all hereby incorporated herein by reference. Each of these patents discloses a low-E coating supported by a glass substrate. The glass substrate is often a soda-lime-silica type of glass substrate including at least SiO2, CaO and Na2O.
Such coated articles often need to be heat treated. Examples of heat treatment (HT) include thermal tempering, heat bending (e.g., in vehicle windshield applications) and heat strengthening. For instance, in certain applications tempering is required by code (e.g., e.g., for building windows over doorways, for windows identified as breakable windows for firemen, and other applications). Heat treatment (e.g., tempering, heat bending, etc.) typically involves heating the glass substrate with a coating thereon in a furnace at a temperature of at least about 580 degrees C., more preferably at least about 600 degrees C., and often at least about 620 or 640 degrees C. (e.g., for at least about 2 minutes, more preferably for at least about 5 minutes). Thus, it will be appreciated that such heat treatments typically involve very high temperatures.
Unfortunately, due to the high temperatures involved, heat treatment such as tempering and/or heat bending can cause damage to low-E coatings supported by the glass substrate. For example, the high temperatures used in such heat treatments often cause sodium (Na) to migrate from the glass into the coating. If sodium reaches the coating (e.g., the IR reflecting layer(s) that is typically formed of or based on Ag), the coating may be damaged. For example, sodium migration from the glass substrate into the coating can cause the coated article to have undesirable haze, undesirable color, and/or reduced visible transmission following heat treatment.
Thus, it will be appreciated that there exists a need in the art to provide a coated article which is resistant to sodium migration during optional heat treatment.

Coated article including soda-lime-silica glass substrate with lithium and/or potassium to reduce sodium migration and/or improve surface stability and method of making same


The present disclosure is related to a method for scattering correction of an image. The method may include obtaining an image of a subject and a reference image of air. The method may also include identifying an OOI from the image, the OOI including one or more pixels. For each pixel of the one or more pixels of the OOI, the method may also include determining an equivalent thickness of the OOI corresponding to the each pixel based on a pixel value of the each pixel and the reference image, and determining a scatter correction coefficient of the each pixel based at least in part on the equivalent thickness of the OOI corresponding to the each pixel. The method may further include correcting the pixel value of the each pixel using the corresponding scatter correction coefficient for each pixel of the one or more pixels of the OOI.

High-energy rays (e.g., X-rays, γ-rays) are widely used in medical imaging. For example, X-rays are used in, for example, computed tomography (CT) devices or digital radiography (DR) devices to generate an image of a subject. During a scan performed by an imaging device, X-rays irradiated on the subject can pass through the subject and are detected by one or more detectors. However, some X-rays may scatter when passing through the subject, which may cause scatter noise in the image generated based on the scan. Conventionally, a grid may be assembled on the imaging device to limit the scattered X-rays from reaching the detector(s) during the scan. However, only a portion of the scattered X-rays may be limited by the grid. In addition, primary X-rays may also be limited by the grid, which may reduce the imaging quality. To improve the imaging quality, the radiation dose of the scan may need to be increased and the subject may suffer from unnecessary radiations. Thus, it is desirable to provide mechanisms for correcting an image to reduce or eliminate scatter noise in the image to improve the imaging quality and avoid unnecessary radiations on the scanned subject.

Systems and methods for scatter correction of image

SHANGHAI UNITED IMAGING HEALTHCARE CO., LTD.


Information sources are selected in accordance with a subject matter of interest to a user, where the subject matter of interest is identifiable by a plurality of sets of subject-related data, and each set has an indication of at least one context in which the set is of interest to the user. The state of the user is tracked, one or more contexts are identified from the tracked state, at least some sets of subject-related data are selected in accordance with a predetermined relationship between at least some of the identified contexts and said indication of context, a list of information sources is generated based on the selected sets of subject-related data, and the list is transmitted to a terminal associated with the user so as to allow the user to select an information source of interest and thereby to access information from the source.

1. Technical Field
The present invention relates to a system for providing information to a user, particularly providing information relevant to a context of the user.
2. Related Art
In the current information rich climate, a considerable amount of attention is being paid to develop improved methods of information retrieval. In particular, the field of agent technology is heavily involved in developing agents for searching, summarisation, filtering and presentation of information e.g. Davies, Weeks & Revett, 1997 ("Information Agents for the WWW" in Software agents and soft computing, Eds H. Nwana, N. Azarmi, Berlin Springer-Verlag). Most, if not all, of these rely on the agent having some knowledge of the user. The inclusion of user information is rapidly becoming a key area, not only for agent technology, but also for the Internet in general, as demonstrated by the recently proposed Open Profiling Standard Dunn, Gwertzman, Layman & Partovi 1997 ("Privacy and profiling on the web" Technical note, WWW consortium Jun. 2, 1997). User information is undoubtedly playing an ever-increasing role as digital libraries, electronic commerce, and personalised applications become more widespread.
Filtering agents (such as email prioritising agents) were typically the first generation of agents to be concerned with managing volumes of information. Maes 1994 describes the various motivations, methods and applications of such agents for reducing information overload (Maes (1994) "Agents that reduce workload and information overload" Communications of the ACM, July). Indeed, this is perhaps the single most important reason that agents have succeeded within the Internet environment: there are simply too many resources available for any one person to consult exhaustively, and indeed if one were fortunate enough to have browsed all these pages, one would probably find that only a small percentage were actually of any interest or relevance. Search agents (such as Amalthaea) are becoming increasingly prominent as a means to reduce this workload, with most including some method of allowing the user to inform the agent of their interests and preferences. Further developments within agent technology have begun to consider previous interactions with a user as well as learning their interests.
Many recent agents include some form of user profiling, such as                Yenta (Foner & Crabtree, 1997 ("Multi-agent matchmaking" in Software agents and soft computing, Eds H. Nwana, N. Azarmi, Berlin Springer-Verlag)),        Syskill & Webert (Pazzani and Billsus, 1997 "Learning and revising user profiles: the identification of interesting web sites", Machine learning 27 (3)),        Personal WebWatcher (Mladenic, 1996 "Personal webwatcher: design and implementation", Technical report Ijs-DP-7472, School of computer science, Carnegie-Mellon University, Pittsburgh USA, October.),        Letizia (Lieberman. 1995 "Letizia: An agent that assists web browsing", Proceedings, 14th Joint International Conference on artificial intelligence (IJDAI-95), Montreal, Canada),        NewsSIEVE (Haneke, 1997 "Learning based filtering of text information using simple interest profiles", In P. Kandzia & M. Klusch, Co-operative information agents. Berlin: Springer-Verlag"), and        INSOP (Kindo et al 1997 "Adaptive personal information filtering system that organizes personal profiles automatically", Proceedings 15th International Joint Conference on Artificial Intelligence (IJCAI-97) pp. 716-721 Nagoya, Japan).The agent of Syskill & Webert learns a user's profile and uses this to guide its suggestions for interesting web pages. The user rates the relevance of the suggestions to the user's interest and the agent employs a naive Bayesian classifier to revise the user profile accordingly. Amalthaea (Moukas, 1997 "User modelling in a multiagent evolving system" Proceedings, workshop on Machine learning for user modelling, 6th International Conference on User modelling, Chia Laguna, Sardinia) employs a weighted keyword representation for a user's profile, which is then consulted in order to query Internet search engines in order to retrieve pages of interest to a user. Amalthaea's user profile comprises a number of information filtering agents (IFAs), each one specialised for a particular topic. These IFAs can be constructed in a number of ways (e.g. through analysis of a user's hotlist of favourite web pages; through observation of the user's interaction with their browser (using page access history logs) etc.) Furthermore the IFAs can evolve over time, so that they can adapt more closely to the user as the user interacts with Amalthaea over time.
Many web sites collect information about a user in order to a) keep track of demographic information, b) provide personalised services and information from the site. This technique is becoming more important for sites to be able to maintain a loyal customer base. Indeed Firefly, Autonomy and OpenSesame! have all recently announced products which will enable such adaption.
It is therefore clear that having a profile of a user is crucial in order to provide services and information of interest to the user. Although the systems described above use a variety of techniques and information sources, not many systems attempt to arrange the keywords, or identifiers in the profile, as a function of the context of a user. The context of a user at a moment in time largely determines the type and content of information that is of interest to the user at that moment in time (e.g. if a user is working then the user is likely to want to know about work related interests) and developments in this area could assist in reducing the volume of information that is presented to a user.
The Applicant's patent EP807291 (U.S. Pat. Nos. 5,931,907 and 6,289,337) teaches a software-based system known as the "JASPER" agent, which stores meta-information, such as URL of the document and keywords indicative of the content of the document, relating to documents of interest to a user. JASPER also stores user profiles comprising keywords that indicate the interests of users in particular types of information, and performs collaborative filtering between users to identify users that may have overlapping interests (arranging users into groups). JASPER compares the meta-information between groups of users, and, if one user in group A has identified a document as being relevant to him, JASPER passes the meta-information relating to the identified document to other users in group A (e.g. via email). The user profile can be arranged to store keywords in categories, as a function of context (e.g. types of work, leisure), and JASPER can change the content of those categories in accordance with detected changes in information type viewed by the user (e.g. performing a comparison between keywords stored in respect of one context and comparing that to the keywords in documents being viewed). JASPER is thus concerned with identifying a set of keywords that characterise context, for the purposes of information delivery and identification between groups of users.
Schmidt A et al, in "There is more to context than location" Computers and Graphics, Pergamon Press Ltd. Oxford, GB, vol. 23, No. 6, December 1999 (1999-12), pages 893-901, XP004187838 ISSN: 0097-8493, describes identifying extrinsic conditions associated with a user, Schmidt describes using inputs from different types of sensors to improve context identification, and uses the context information to improve selection of display characteristics and dialogue status (such as interruptability) for mobile users reliant on receiving data via mobile devices.

British Telecommunications public limited company


A high quality liquid crystal display device has an alignment film with a photoconductive characteristic. Since a region having gate lines situated therebelow does not undergo irradiation of a backlight, no photoconductive effect can be obtained. A photoresist is disposed below the alignment film situated over the gate lines in order to transfer the charges in the region to an opening portion of the alignment film in an early stage. Since the photoresist has a thickness of about 1.5 μm, which is 20 times or more the 70 nm thickness of the alignment film, the resistance in the lateral direction is low in a portion where the photoresist is present. Accordingly, since the charges on the alignment film present over the gate line transfer to the opening portion of the alignment film and are eliminated in an early stage, the residual image is eliminated in the early stage.

1. Field of the Invention
The present invention relates to a liquid crystal display device, and particularly relates to a liquid crystal display device having a liquid crystal display panel of which alignment film is provided with alignment controllability by irradiation of light.
2. Description of the Related Art
Liquid crystal display devices include a TFT substrate having pixel electrodes, thin film transistors (TFT), etc. formed in a matrix; a counter substrate disposed in facing relation to the TFT substrate and having color filters, etc. formed at positions corresponding to the pixel electrodes of the TFT substrate; and liquid crystals put between the TFT substrate and the counter substrate. Images are formed by controlling the light transmittance of liquid crystal molecules of each pixel.
Since the liquid crystal display devices are flat and light in weight, their application use has been extended in various fields, for example, from large-sized display devices such as television sets to mobile phones and DEC (Digital. Still Cameras). The liquid crystal display devices involve a problem about a viewing angle characteristic. The viewing angle characteristic is a phenomenon that luminance or chromaticity changes when the screen is viewed obliquely compared with when it is viewed from the front. An IPS (In Plane Switching) system in which liquid crystal molecules are operated by horizontal electric fields has excellent viewing angle characteristics.
A method of applying an alignment treatment, that is, providing an alignment controllability to an alignment film used in the liquid crystal display device includes a rubbing treatment in the prior art. In the alignment treatment by rubbing, alignment is performed by rubbing an alignment film with a cloth. The alignment treatment also includes optical alignment method of providing the alignment controllability to an alignment film in a contactless manner. The optical alignment is applicable to the IPS system since a pre-tilt angle is not required.
JP-A-2004-206091 discloses a photolytic optical alignment treatment by irradiation of light typically represented by UV-light. JP-A-2004-206091 describes that the photolytic optical alignment can provide the following effect of:    (1) mitigating alignment disturbance due to the complicate stepped structure in a Pixel portion, and    (2) overcoming damage to thin film transistors caused by static electricity in the alignment treatment by rubbing and display failure caused by disturbance of alignment due to the disorder at the tip of the rubbing cloth or dusts, thereby overcoming complexity in the process caused by frequent replacement of the rubbing Cloth required for obtaining uniform alignment Controllability.
JP-A-2010-72011 discloses a configuration in which the upper layer of the alignment film is formed of a film having a large molecular weight and capable of efficient optical alignment while the lower layer of the alignment film is formed of a photoconductive film having a small molecular weight thereby decreasing a residual image.

Liquid crystal display device comprising an alignment film subjected to an optical alignment treatment and having a photoconductive characteristic


An audio enhancement system and method for use receives a group of multi-channel audio signals and provides a simulated surround sound environment through playback of only two output signals. The multi-channel audio signals comprise a pair of front signals intended for playback from a forward sound stage and a pair of rear signals intended for playback from a rear sound stage. The front and rear signals are modified in pairs by separating an ambient component of each pair of signals from a direct component and processing at least some of the components with a head-related transfer function. Processing of the individual audio signal components is determined by an intended playback position of the corresponding original audio signals. The individual audio signal components are then selectively combined with the original audio signals to form two enhanced output signals for generating a surround sound experience upon playback.

1. Field of the Invention
This invention relates generally to audio enhancement systems and methods for improving the realism and dramatic effects obtainable from two channel sound reproduction. More particularly, this invention relates to apparatus and methods for enhancing multiple audio signals and mixing these audio signals into a two channel format for reproduction in a conventional playback system.
2. Description of the Related Art
Audio recording and playback systems can be characterized by the number of individual channel or tracks used to input and/or play back a group of sounds. In a basic stereo recording system, two channels each connected to a microphone may be used to record sounds detected from the distinct microphone locations. Upon playback, the sounds recording by the two channels are typically reproduced through a pair of loudspeakers, with one loudspeaker reproducing an individual channel. Providing two separate audio channels for recording permits individual processing of these channels to achieve an intended effect upon playback. Similarly, providing more discrete audio channels allows more freedom in isolating certain sounds to enable the separate processing of these sounds.
Professional audio studios use multiple channel recordings systems which can isolate and process numerous individual sounds. However, since many conventional audio reproduction devices are delivered in traditional stereo, use of a multi-channel system to record sounds requires that the sounds be "mixed" down to only two individual signals. In the professional audio recording world, studios employ such mixing methods since individual instruments and vocals of a given audio work may be initially recorded on separate tracks, but must be replayed in a stereo format found in conventional stereo systems. Professional systems may use 48 or more separate audio channels which are processed individually before receded onto two stereo tracks.
In multi-channel playback systems, i.e., deed herein as systems having more than two individual audio channels, each sound recorded from an individual channel may be separately processed and played through a corresponding speaker or speakers. Thus, sounds which are recorded from, or intended to be placed at, multiple locations about a listener, can be realistically reproduced through a dedicated speaker placed at the appropriate location. Such systems have found particular use in theaters and other audio-visual environments where a captive and fixed audience experiences both an audio and visual presentation. These systems, which include Dolby Laboratories' "Dolby Digital" system; the Digital Theater System (DTS); and Sony's Dynamic Digital Sound (SDDS), are all designed to initially record and then reproduce multi-channel sounds to provide a surround listening experience.
In the personal computer and home theater arena, recorded media is being standardized so that multiple channels, in addition to the two conventional stereo channels, are stored on such recorded media. One such standard is Dolby's AC-3 multi-channel encoding standard which provides six separate audio signals. In the Dolby AC-3 system, two audio channels are intended for playback on forward left and right speakers, two channels are reproduced on rear left and right speakers, one channel is used for a forward center dialogue speaker, and one channel is used for low-frequency and effects signals. Audio playback systems which can accommodate the reproduction of all these six channels do not require that the signals be mixed into a two channel format. However, many playback systems, including today's typical personal computer and tomorrow's personal computer/television, may have only two channel playback capability (excluding center and subwoofer channels). Accordingly, the information present in additional audio signals, apart from that of the conventional stereo signals, like those found in an AC-3 recording, must either be electronically discarded or mixed into a two channel format.
There are various techniques and methods for mixing multi-channel signals into a two channel format. A simple mixing method may be to simply combine all of the signals into a two-channel format while adjusting only the relative gains of the mixed signals. Other techniques may apply frequency shaping, amplitude adjustments, time delays or phase shifts, or some combination of all of these, to an individual audio signal during the final mixing process. The particular true or techniques used may depend on the format and content of the individual audio signals as well as the intended use of the final two channel mix.
For example, U.S. Pat. No. 4,393,270 issued to van den Berg discloses a method of processing electrical signals by modulating each individual signal corresponding to a pre-selected direction of perception which may compensate for placement of a loudspeaker. A separate multi-channel processing system is disclosed in U.S. Pat. No. 5,438,623 issued to Begault. In Begault, individual audio signals are divided into two signals which are each delayed and filtered according to a head related transfer function (HRTF) for the left and right ears. The resultant signals are then combined to generate left and right output signals intended for playback through a set of headphones.
The techniques found in the prior art, including those found in the professional recording arena, do not provide an effective method for mixing multi-channel signals into a two channel format to achieve a realistic audio reproduction through a limited number of discrete channels. As a result, much of the ambiance information which provides an immersive sense of sound perception may be lost or masked in the final mixed recording. Despite numerous previous methods of processing multi-channel audio signals to achieve a realistic experience through conventional two channel playback, there is much room for improvement to achieve the goal of a realistic listening experience.
Accordingly, it is an object of the present invention to provide an improved method of mixing multi-channel audio signals which can be used in all aspects of recording and playback to provide an improved and realistic listening experience. It is an object of the present invention to provide an improved system and method for mastering professional audio recordings intended for playback on a conventional stereo system. It is also an object of the present invention to provide a system and method to process multi-channel audio signals extracted from an audio-visual recording to provide an immersive listening experience when reproduced through a limited number of audio channels.
For example, personal computers and video players are emerging with the capability to record and reproduce digital video disks (DVD) having six or more discrete audio channels. However, since many such computers and video players do not have more than two audio playback channels (and possibly one sub-woofer channel), they cannot use the full amount of discrete audio channels as intended in a surround environment. Thus, there is a need in the art for a computer and other video delivery system which can effectively use all of the audio information available in such systems and provide a two channel listening experience which rivals multi-channel playback systems. The present invention fulfills this need.

Multi-channel audio enhancement system for use in recording and playback and methods for providing same


A method for automated error detection and verification of software comprises providing a model of the software, the model including one or more model inputs and one or more model outputs, and a plurality of blocks embedded within the model each with an associated block type, the block types each having a plurality of associated block-level requirements. The method further comprises topologically propagating from the model inputs, a range of signal values or variable values, and error bounds, across computational semantics of all the blocks to the model outputs. Each behavior pivot value for a given block is identified and examined to determine if modifying or extending the propagated range by the error bound will or may cause a signal value to fall on either side of the behavioral pivot value. All occurrences of the signal value that will or may fall on either side of the behavioral pivot value are reported.

Flight-critical software is part of an aircraft system that includes sensors and actuators, and integrates physical processes with computation. This software controls and interacts with many different, mixed-criticality subsystems, such as the engine, guidance and navigation, fuel management, flight control, communication, collision detection and resolution, climate control, and entertainment.
The algorithms underlying the software are based on mathematical principles such as algebra, analysis, geometry, and trigonometry. The calculations often involve nonlinear arithmetic that is not adequately supported by formal tools due to the complexity of the necessary calculations. Typically, models based on continuous mathematics are implemented using discrete software systems. In such models, numeric values are approximated by floating-point representations that introduce errors. Floating-point computations can likewise introduce errors. In addition, the software itself is executed on a distributed platform that introduces numerical and timing errors due to jitter, sensor precision, and external mechanical or functional errors.
These errors can accumulate and may qualitatively change the behavior of the system. Any time the system must make a decision (e.g., an if-then-else or loop construct) that compares two values, either or both of those values may be offset by error to some degree. This can cause a system to perform different behaviorally than if the values were precisely represented. The value around which execution changes is called a "behavioral pivot value." Decisions that depend on behavioral pivot values can affect the timing behavior and physical performance of the system controlled by the software. However, current tools either do not take these errors into account or are not scalable enough to support industrial-sized problems.

Method for automated error detection and verification of software


Some embodiments relate to an integrated chip that includes a first source/drain region and a second source/drain region disposed in a substrate. A plane that is substantially perpendicular to an upper surface of the substrate traverses the first source/drain region and the second source/drain region. Agate electrode extends over a channel region in the substrate between the first source/drain region and the second source/drain region. The gate electrode is separated from the channel region by way of a charge trapping dielectric structure. The charge trapping dielectric structure includes a tunnel dielectric layer, a charge trapping dielectric layer over the tunnel dielectric layer, and a blocking dielectric layer over the charge trapping dielectric layer. The channel region has a channel width measured perpendicularly to the plane, and the tunnel dielectric layer has different thicknesses at different respective points along the channel width.

Embedded memory is electronic memory that is integrated with logic devices on a common integrated circuit (IC) die or chip. Embedded memory is able to support operation of the logic devices and is often used with very-large-scale integration (VLSI) IC dies or chips. The integration advantageously improves performance by eliminating interconnect structures between chips and advantageously reduces manufacturing costs by sharing process steps between the embedded memory and the logic devices.

This patent is subject to a terminal disclaimer.

Embedded flash memory cell including a tunnel dielectric layer having different thicknesses over a memory region

Taiwan Semiconductor Manufacturing Company, Ltd.


A storage system includes a redundant array of independent disks (RAID), a file subsystem, and a multiple device control unit. The RAID includes a plurality of disks and a bitmap. The file subsystem is used for executing a write command and a trim command. The multiple device control unit does not execute a first synchronization operation on the plurality of disks during the RAID is built, does not execute a second synchronization operation on expansion capacity of the plurality of disks during the RAID is expanded, executes a third synchronization operation on at least one added disk according to the blocks of the plurality of disks occupied by the data during the RAID is reshaped, and/or executes a corresponding operation on at least one added disk according to the blocks of the plurality of disks occupied by the data during the RAID is recovered.

1. Field of the Invention
The present invention is related to a storage system and an operation method of a storage system, and particularly to a storage system and an operation method of a storage system that have advantages of fast establishment, recovery, reshaping, and/or resizing.
2. Description of the Prior Art
A high level storage device is usually capable of providing a very large capacity file system and redundant array of independent disks (RAID) for a user. However, when the very large capacity file system is built in a large capacity RAID, data of the user stored in the large capacity RAID may suffer some risk in some conditions.
RAID level greater than 1 can still provide normal write and read capability when one disk of the RAID fails ("degraded"), but RAID-6 can allow at most two disks to fail. When a RAID (such as the RAID-1, the RAID-5, or the RAID-6) has a failed disk, the user can substitute the failed disk with a normal disk. Meanwhile, a program of an operation system (such as Linux) will perform a recovery process (called recovery) on the normal disk. Then, the program can store data (the same as data stored in other healthy disks) in the normal disk according to a store rule of the RAID. While the program performs the recovery process on the normal disk, the RAID is unsafe because the RAID (except for the RAID-6) can not allow another disk to fail. However, the RAID spends more time on the recovery process the greater the capacity of the RAID, which means that the RAID is unsafe for a longer time. Thus, when a file system is in a degraded RAID, risk of loss of user data of the file system is increased because the RAID may crash at any time.

Storage system and operation method of a storage system


A delivery nozzle is connected to the outlet end of a fuel supply hose and includes an outlet pipe. A valve is operatively associated with the discharge end of the outlet pipe for opening and closing the latter and an operator is provided for closing the valve responsive to the operator being subject to sub-atmospheric pressure. Further, sub-atmospheric pressure generating structure is operatively associated with the valve operator and generates sub-atmospheric pressure responsive to fuel flow through the outlet pipe and the discharge end of the pipe being submerged within rising fuel in a tank or a tank fill neck into which fuel is being discharged from the outlet pipe.

1. Field of the Invention
This invention relates to a delivery nozzle connected to the end of a fuel supply hose, said nozzle comprising an outlet pipe, a valve, means for operating said valve and means responsive to subatmospheric pressure for automatically closing said valve.
2. Description of Related Art
In a similar, generally known nozzle, the valve is disposed in a handle, and the means for manually operating the valve are disposed under the handle. Furthermore, an open connecting line extends through the outlet pipe, namely, from the free end of the outlet pipe to a point in the vicinity of the valve, with the result that when the relevant end of the connecting line is closed as a result of the level of the liquid in the tank being filled, a subatmospheric pressure arises at the other end disposed in the vicinity of the valve, as a result of which the valve is closed.
Such a known device has various disadvantages, the first of which is that there is always after-drip as a result of the fact that the valve is spaced from the outlet pipe end. A further disadvantage is that the valve is operated by hand, and so can easily be opened before the outlet pipe end is within the tank to be filled. A third drawback is that the valve construction is such that in the vicinity of the valve the fluid being supplied is greatly whirled in the nozzle, resulting in a certain degree of foaming which is apt to cause premature closure of the means responsive to subatmospheric pressure for closing the valve.

Automatic shut-off liquid delivery nozzle


This disclosure is directed to the design of a dilatation catheter having two or more associated fluidcarrying tubes, the operative or distal end of one of which supplies fluid to inflate an expansible balloon and the operable or distal end of the other of which supplies an injectable dye or contrast enhancing fluid adjacent the proximal end of the balloon.

I. Field of the Invention
This invention is directed generally to intravascular catheters, and more particularly to the design of a dilatation catheter having a pair of associated fluidcarrying tubes, the operative or distal end of one of which supplies fluid to inflate an expansible balloon and the operable or distal end of the other of which supplies an injectable dye or contrast enhancing fluid adjacent the proximal end of the balloon.
II. Description of the Related Art
Dilatation catheters of the general class of the present invention are well known and generally described in references such as the American Journal of Cardiology, Volume 49, Apr. 1, 1982, pages 1216-1222. They are basically employed to enlarge constrictions in larger vessels or arteries, or even other internal cavities by employing a precisely placed inflatable balloon device to compress plaque or other obstructing material against the arterial wall or the outer surface of the cavity of interest thereby reopening a larger channel for blood flow or the like. This method of treatment of stenotic lesions in the vascular system is known as transluminal balloon angioplasty. The procedure involves the use of an elongated, flexible, plastic catheter having an inflatable expander member or balloon proximate its distal tip. The catheter describes a tubular lumen suitable to conduct an amount of fluid introduced from without the body to and from the balloon to accomplish inflation and deflation of the balloon as required. One such device is illustrated and described in U.S. Pat. No. 4 762 129. The system is introduced at an appropriate site in the vascular system, commonly in the femoral artery, and routed through the system using a guide wire to the site of the lesion of interest to be treated. Once the deflated balloon is positioned in the desired relationship to the lesion, the appropriate fluid is introduced into the proximal end of the catheter and flows to inflate the balloon which, in turn, compresses the stenotic lesion against the wall of the blood vessel.
In order for the balloon to be precisely positioned with respect to the stenosis to be compressed and the result easily evaluated, a contrast medium or dye is utilized to enhance the contrast at the site so that the scene can be viewed with greater resolution by the operator of the device. Normally, this involves injecting an amount of contrast fluid or dye material into the femoral artery and waiting until the diluted dye makes its way through the vascular system to the site of the stenotic lesion. There is a significant time delay between the time of injection and the corresponding effect on the image viewed on the fluoroscope. Because of the dilution effect, it also requires the injection of an additional amount of fluid consistent with the need to circulate the fluid through the vascular system to the site. Adjustments in concentration also require time and may lack the desired accuracy or control. It would represent a great improvement in the art if the appropriate contrast fluid or dye could be introduced near the distal end of the catheter proximate to the balloon member and the stenotic lesion. This would save a great deal of the time spent waiting for the fluid to circulate, reduce the amount of contrast fluid required and increase the control over the predictable result of dye addition.

Dilatation balloon catheter with infusion lumen


An apparatus and method for dispensing a single paper towel from a continuous paper towel roll includes a housing having a housing back and a front cover connectable thereto for opening and closing the housing. A dispensing opening is positioned along a periphery of the housing, the dispensing opening defined at least partly by the housing back and at least partly by the front cover; a paper retainer member associated with the front cover and positioned to guide through the dispensing opening a tail of a paper towel roll positioned in the housing; and a piston assembly comprising a biasing member and a piston responsive thereto, the piston assembly connected to the housing so that the piston contacts the tail of a paper towel roll extending through the dispensing opening. The dispenser is magnetically attachable to a ferrous metal surface.

Dispensers for roll paper towels have been well known for some time. Such dispensers are commonly placed in lavatories, near sinks, and in public restrooms to enable users to dry their hands after washing. Typically, a paper towel dispenser is mounted on a wall adjacent a sink or other handwashing station. The dispensers are usually hand operated by the user, and dispense a length of paper towel according to pulling action by the user. Some dispensers are provided with an actuating mechanism for dispensing the paper towels, and also intended to help prevent unchecked dispensing of the paper towels, which causes waste of paper.
The prior art includes various attempts to design paper towel dispensers having mechanisms for preventing excess dispensing of paper towels. A typical approach to this problem is some type of metering mechanism requiring a user to push an activating button or lever, or wait a predetermined time before another paper towel can be pulled from the dispenser. For example, U.S. Pat. No. 4,664,304 issued to Wendt et al. describes a metering mechanism having a button which must be depressed by the user for each predetermined amount of paper towel to be dispensed. As shown in the figures, such an actuating button is typically interconnected with a drive mechanism or other moving parts which function in the act of dispensing. At times, gears and other moving parts connected to the button will break or disengage therefrom, rendering the button useless.
Because of the materials used in a work area or for ease of cleaning, locations where paper towel dispensers are commonly found are designed with ferrous metal surfaces that make attachment by conventional fasteners difficult. In particular, for example, wall partitions dividing stalls in a restroom facility are likely to be manufactured of metal, usually a ferrous metal. The skilled will recognize that the term "ferrous" as described in standard English dictionaries means "containing iron." A ferrous metal, for example, will display magnetic attraction, so that a magnet will attach to the metal. Accordingly, an embodiment of this invention is contemplated that would allow conventional fasteners to be replaced by one or more magnets for attaching the dispenser to ferrous metal walls or surfaces. This feature would eliminate the need to drill one or more holes into the metal surface in order to attach the dispenser, thus preventing the potential for corrosion between the fastener and the metal wall and greatly facilitating the installation process.
In view of the foregoing, there continues to be a need for a roll paper towel dispenser structured to provide a user with a single paper towel at a time, and not requiring any affirmative action by the user, other than pulling out the paper towel. Additionally, a roll paper towel dispenser having a metering mechanism not easily accessible to a user would be more tamper resistant and would help prevent intentional damage to the dispenser. Further, a dispensing control mechanism that is relatively simple, inexpensively fabricated, and easily maintained would be advantageous.


A fluorescent element includes a fluorescent light layer that converts a light flux from an LD light source into light having a different wavelength, a scattering layer, and a reflective element. The fluorescent light layer is provided between the scattering layer and the reflective element.

Field of the Invention
The present invention relates to an optical element, a light source device using the optical element, and a projection display apparatus.
Description of the Related Art
In recent years, a projector including a light source device including a solid light source, such as a laser diode (hereinafter referred to as LD) light source and an LED light source, and a fluorescent element that converts a portion of excitation light emitted from the solid light source into fluorescent light having a wavelength different from the wavelength of the excitation light has been developed.
Such a light source device is disclosed in JP 2012-189938 A.
JP 2012-189938 A discloses a light source device including a light source unit that includes a plurality of blue LDs, a light source unit including a plurality of red LDs, and a fluorescent element having a fluorescent light layer that is provided on a transmissive substrate and emits green-color light by excitation by blue-color light. With a portion of the light from the blue LD working as excitation light and the rest of the portion of the light passing through the fluorescent element as unconverted light, the fluorescent element emits blue-color light, green-color light, and red-color light.
As in the light source device disclosed in JP 2012-189938 A, in which the fluorescent element having a fluorescent light layer that emits fluorescent light by excitation by blue-color light, the light amount of blue-color light tends to be smaller than the light amount of green-color light and red-color light, because the blue-color light is used as excitation light. Therefore, the color balance of a projected image might be degraded.

Optical element, light source device using the same, and projection display apparatus


The present invention relates to a tool as well as a blank for manufacturing of the tool. The tool is made of solid cemented carbide and includes a shank for mounting in a rotatable spindle and chip flutes. Lines of intersection between the chip flutes and clearance surfaces form cutting edges at a cutting end of the tool. The flush channels extend through the entire tool in order to transfer flushing medium to the cutting end of the tool. The flush channels have varying pitch.

The present application is a continuation of International Application No. PCT/SE04/00857, filed Jun. 2, 2004, which claims priority of SE 0301617-7, filed Jun. 4, 2003, and SE 0301828-0, filed Jun. 19, 2003, all three of which are incorporated by reference.
The present invention relates to a rotatable tool and a blank.
It is previously known through for example WO 98/28455 to press material powder, such as tungsten carbide (WC) together with cobalt (Co), between a punch and a die, and subsequently to sinter the material such that the binder metal is melted and binds the carbides to form tool material for chip removing machining. The known technique brings about a plurality of drawbacks. The powder give off dust and the formed green body (pressed but not sintered material) will not endure handling to any degree. Furthermore the chip flutes must be ground and the method requires time and energy. The problems have partly been solved by injection moulding of cemented carbide mixed in a carrier such as indicated in SE-B-9501687-9. The method of injection moulding brings a high degree of freedom concerning geometry but brings costly investments in moulds.
It is previously known through for example U.S. Pat. No. 4,779,440 and WO/0074870 to form a blank for a helix drill. The extruded blank has chip flutes with uniform pitch along the circumference of the blank.
It is desirable to provide a rotatable tool and a blank having varying pitch of the flush channels.
It is desirable to provide a tool having flush channels of varying pitch.
It is desirable to provide a tool having good durability.
According to an aspect of the invention, a rotatable tool is provided, the tool being made of cemented carbide and comprising a shank for mounting in a rotatable spindle, at least one chip flute, a cutting edge formed at a line of intersection between the at least one chip flute and clearance surfaces at a cutting end of the tool, and at least one flush channel extending through the tool to transfer flushing medium to the cutting end of the tool, wherein the flush channel has a varying pitch.
According to another aspect of the invention, a blank for a tool for chip removing machining is provided, the blank being made of solid cemented carbide and comprising at least one space for forming at least one flush channel in the tool, the space extending through the entire blank, wherein the space has a varying pitch.