A barbecue has a pair of storable shelves mounted on opposite portions of the barbecue housing adjacent the upper open end of the housing. The shelves are rotatable about generally vertical pivot axes so that each can be swung between a first position for use outside the housing and a second position for storage inside the housing. The shelves are positioned, one over the other, for storage inside the housing when each is in the second position. Swinging movement of each of the shelves between the first and second position is provided by a downwardly extending shaft at an end of a bracket on which the shelf is mounted, which shaft is rotatably received within a mating vertical aperture in a mounting assembly mounted at the inside surface of the barbecue housing. Recesses in the shelf brackets permit the brackets to be positioned over and to nest on the rim of the housing when in the first position outside of the housing.

1. Area of the Art
The present invention relates to cooking appliances such as barbecues, and more particularly to barbecues having one or more shelves associated therewith.
2. Description of the Prior Art
It is known in the art to provide a cooking appliance such as a barbecue having one or more shelves associated therewith. The shelves may be movably attached to the barbecue so that they can be moved into a position of use such as outside of the barbecue for storage of food and implements thereon, and also movable into a position for storage of the shelves such as at the inside of the barbecue. Published U.S. Application No. 2003/0192526 of DeMars shows various embodiments of a barbecue in which opposite shelves are folded over for storage inside the barbecue and are unfolded to the outside of the barbecue for use. Published U.S. Application No. 2003/0111070 of DeMars and U.S. Pat. No. 6,606,987 of DeMars have similar disclosures. Published U.S. Application No. 2003/0111070 of DeMars also shows a barbecue with hinging shelves.
Still further examples of barbecues with hinging shelves are provided by published U.S. Application No. 2003/0079737 of Wu and U.S. Pat. No. 6,513,515 of Wu.
Published U.S. Application No. 2002/0050274 of Hamilton et al. describes a portable stove having opposite hinging shelves that cover the top of the stove when pivoted to an inner position. U.S. Pat. No. 5,016,607 of Doolittle describes opposite shelves which remain outside of a barbecue and which are hinged and can be raised and lowered. The hinges have latching mechanisms to latch the shelves in a raised position. U.S. Pat. No. 4,166,413 of Meszaros also describes a barbecue having shelves which are raised and lowered. U.S. Pat. No. 2,541,528 of McAvoy describes an arrangement of opposite hinging shelves similar to that in published U.S. application Ser. No. 0050274 of Hamilton.
The various examples of the prior art discussed above describe barbecues having shelves which are hinged or otherwise pivotable about horizontal axes so that they fold to the inside of the barbecue for storage and to the outside of the barbecue for use. However, it may be desirable to provide other configurations and arrangements in which shelves are movable between a position on the inside of the barbecue for storage and a position on the outside of the barbecue for use.


A true/complement integrated circuit device is disclosed for reducing an amount of simultaneous switching on a bus between a current state and a next state. The device includes a current state register connected to the bus for outputting the current state onto the bus during a first clock cycle. A next state register is provided for containing the next state, wherein the next state is a pending state of the bus intended for a next clock cycle. A comparison circuit compares a current state value in the current state register with a next state value in the next state register on a bit-by-bit basis to determine if the current state value and the next state value are of a same polarity or of an opposite polarity. A circuit is provided for determining a ratio of switching signals from an output of the bit-by-bit comparisons by the comparison circuit. The ratio determining circuit further generates a true/complement (T/C) signal having a first state if it is determined that more than a prescribed percentage of bits are in transition, the T/C signal having a second state otherwise. Lastly, a circuit is provided for complementing the bits of the next state register in response to the T/C signal being in the first state, and not complementing the bits of the next state register in response to the T/C signal being in the second state, prior to being transferred into the current state register and output onto the bus during the next clock cycle.

1. Field of the Invention
This invention relates generally to integrated circuits and, more particularly, to a method and apparatus for controlling simultaneous switching noise in an output bus configuration of very large scale integrated (VLSI) circuits.
2. Discussion of the Related Art
The fabrication of high performance VLSI devices permits the use of many functions on a single integrated circuit chip. The functional blocks on a single chip must be connected with a variety of other chips in order to receive data and communicate results within a computer system or other similar system. Communication between chips or functional blocks is faster when the data is transmitted in parallel over a large number of interconnections or bus. The electrical behavior of interconnections between functional blocks on a single chip is different than the behavior of interconnection between chips. The electrical resistance, capacitance, and inductance associated with packaging and interconnecting multiple chips affects the switching transitions of the signals sent between the chips. Therefore, the output drivers are used to compensate for these effects.
Output drivers generally drive a much larger capacitive load than an on-chip functional block would drive. To handle these large loads and meet required cycle times, output drivers have to drive high currents and have large di/dt's (corresponding to fast switching transition times). When a large number of these output drivers switch at the same time, the current demanded by the drivers can exceed the amount of current an integrated circuit package can supply to the on-chip power buses. When this happens, noise is generated on the chip and the buses "bounce" away from a card supply. The amount of noise depends on the speed of the drivers, the number of drivers switching, the design of the on-chip power buses and the electrical characteristics of the package. It is possible that the on-chip bus may be a volt or more away from the value of the same supply on the card. This much noise on a power supply can cause problems with signals being received on the same chip and can cause outputs that are not supposed to be switching to temporarily change states. Thus there exists a concern with simultaneous switching output drivers.
The stronger output signal coupled with a large number of output signals switching in parallel produces a noise problem on a single chip. Part of the noise problem is a result of a change in the current required by the input/output devices when many input/output devices are switched at once. The effects of the changes in current, also called current spikes, on the input/output devices vary depending on the placement of the drivers with respect to the power supply pins on the chip and the design of the power supply bussing. This is because current spikes must pass through the power supply bussing and its parasitic impedance. The placement of a switching input/output device with respect to the power supply pins changes the impedance which the current spikes encounter. Therefore, the voltage dropped across the impedance varies and this produces different effects on the input/output devices and other circuits near the input/output devices. In particular, when a current spike (i.e., noise) becomes large enough over a small enough impedance, an input/output device may (depending upon its position within a chip) switch its logical state unintentionally.
In an effort to reduce overall chip power consumption, the power supply bussing on a chip has the lowest impedance that is practical. A low impedance aggravates the noise problem because the current spike is not damped as it travels through the bussing so that it effects more circuits. Both a larger current spike and smaller impedances are likely when several input/output devices operate in parallel. Therefore, enhancing the signal speed and number of parallel input/output devices makes the chip communication more unreliable because the signals sent may not be correct due to the current noise (also referred to as Delta I noise) in the power supply.
Another part of the Delta I noise is that the current spike is an AC signal capacitively coupled to adjacent input/output devices through the parasitic capacitances between the input/output devices. The placement of the input/output devices determines the impedance through which the current spike passes. This impedance and size of the current spike determine the strength of the voltage signal capacitively coupled to the adjacent devices. If enough voltage is coupled to an adjacent input/output device through several input/output devices switching to one state simultaneously, and therefore having a cumulative effect, then the adjacent input/output device will switch logical state unintentionally. Again, switching logic signals are made more unreliable because of the Delta I noise.
As buses increase in size and transfer rates, the condition of simultaneous switching noise increases. The effect of this noise is a capping of a frequency and/or the increase in cost for packaging. At the same time, increasing complexity of processor architecture has resulted in the external bus to be the bottleneck. Some means of increasing the bus speed without increasing the simultaneous switching noise is needed.
Prior known solutions to this problem of simultaneous switching noise include the reducing of the speed of the transitions between the logic states of the input/output devices, however, the performance of the chip is undesirably limited by the Delta I noise. Another known technique is to filter out the current spikes. While filtering out the current spikes may be effective, the same may be prohibitively expensive because of packaging costs. Still another solution to the Delta I noise problem is to modify the parasitic elements on the power supply bussing for the chip itself. Typically, the later is done by using several input/output pins on the chip (rather than a single pin) for power supply connections. However, the number of input/output pins on a VLSI chip is generally limited. Therefore, the functionality of the chip is limited because the number of pins useful for logic signals is limited due to allocating extra pins for the power supply.

True/complement output bus for reduced simulataneous switching noise

International Business Machines Corporation


A deep learning based compression (DLBC) system trains multiple models that, when deployed, generates a compressed binary encoding of an input image that achieves a reconstruction quality and a target compression ratio. The applied models effectively identifies structures of an input image, quantizes the input image to a target bit precision, and compresses the binary code of the input image via adaptive arithmetic coding to a target codelength. During training, the DLBC system reconstructs the input image from the compressed binary encoding and determines the loss in quality from the encoding process. Thus, the models can be continually trained to, when applied to an input image, minimize the loss in reconstruction quality that arises due to the encoding process while also achieving the target compression ratio.

This invention generally relates to digital image processing, and more specifically to the efficient encoding of digital media content such as images and videos using machine learning techniques.
Streaming of digital media makes a large portion of Internet traffic with projections to reach an even higher portion by 2020. Existing approaches to digital media content compression such as image compression, however, have not been able to adapt to the growing demand and the changing landscape of applications. Compression of digital media content, in general, is to identify and reduce irrelevance and redundancy of the digital media content for compact storage and efficient transmission over a network. If the structure in an input (e.g., image or video) can be discovered, then the input can be represented more succinctly. Hence, many compression approaches transform the input in its original type of representation to a different type of representation, e.g., the discrete cosine transform (DCT), where the spatial redundancy of the input can be more conveniently exploited by a coding scheme to attain a more compact representation. However, in existing image compression approaches deployed in practice, the mechanisms for structure exploitation are hard-coded: for instance, JPEG employs 8×8 DCT transforms, followed by run-length encoding; JPEG 2000 applies wavelets followed by arithmetic coding, where the wavelet kernels used in the transform are hard-coded, and fixed irrespective of the scale and channel of input data.
Deep learning has revolutionized many tasks of analysis such as machine translation, speech recognition, face recognition, and image classification. However, deep learning has not been successfully employed for compression of digital media data. For example, existing deep learning based approaches have not been able to produce results surpassing performance of hard-coded approaches. Furthermore, existing deep learning based approaches are not computationally feasible for deployment in practice.

Deep learning based on image encoding and decoding


A transceiver switching apparatus and method for maintenance and repair of a troubled transceiver in a cellular base station in a CDMA mobile telecommunication system. The apparatus has a switching module having a plurality of switches in combination, capable of simultaneous control of the switches with a single control signal. The switching apparatus includes a plurality of transceivers each being capable of generating an alarm signal upon occurrence of an abnormal state therein, and an alarm release signal upon removal of the abnormal state, each of the transceivers outputting an intermediate transmitting frequency converted from an intermediate receiving frequency signal on basis of a tuning frequency, at least one spare transceiver adapted for performing the same function as the transceivers, a receiving switching circuit having pairs of inputs and outputs for delivering the intermediate receiving frequency selectively to the plurality of transceivers and/or the spare transceiver, and a transmitting switching circuit having pairs of inputs and outputs for receiving the intermediate transmitting frequency selectively from the plurality of transceivers and/or the spare transceiver.

1. Field of the Invention
The present invention relates to a Code Division Multiple Access (hereinafter, referred to as CDMA) mobile telecommunication system and, in particular, to a switching apparatus and method for switching over to a spare transceiver for maintenance and repair of a troubled transceiver when the transceiver, preferably, but not exclusively, for use in a CDMA cellular base station, gets into trouble.
2. Description of the Related Art
Generally, a CDMA mobile telecommunication system is provided with a low power radio transmitter and receiver (transceiver) and a control unit in a central area of each service area, i.e., a cell, in which a cellular base station serves as a relay to communicate by radio with a selected mobile telephone terminal equipment. A receiving frequency applied from each mobile terminal equipment is converted and amplified into a much lower radio frequency, which is often referred to as an "intermediate frequency". The cellular base station converts the receiving frequency to the intermediate frequency, which is subsequently converted to a transmit intermediate frequency on basis of a tuning frequency of each transceiver.
A cellular base station of CDMA mobile telecommunication system has a multiplicity of transceivers adapted to convert an intermediate frequency to and from the respective different radio frequencies corresponding to each mobile terminal equipment, in which system the number of those transceiver depends upon the number of radio channels. When the system needs to perform maintenance and repair of a transceiver due to any one of the transceivers operating in a CDMA cellular base station getting into trouble or malfunctioning, one of a plurality of switches, each switch corresponding to a respective transceiver, i.e., the switch coupled to the troubled transceiver, is turned off to switch over to a predetermined spare transceiver that continues the conversion of the intermediate frequency instead of the troubled transceiver.
Thus, a problem of space occurs because of such a large number of switches in use which require a lot of control cables connected with those switches, and which inevitably leads to complicated construction of the transceiver system and higher cost.

Switching apparatus and method for transceiver of cellular base station in code division multiple access mobile telecommunication system


This specification relates to a colorless composite material capable of retaining transparency within a wide temperature range by impregnating glass composition (glass fibers) with inorganic-organic hybrid resin. A colorless composite material according to exemplary embodiments includes glass fibers, and inorganic-organic hybrid resin consisting of inorganic bonds and organic bonds, wherein the inorganic bonds are Si—O—Si bonds or Si—O-M bonds and M denotes a metallic element.

In general, glass or plastic is used as a transparent material. However, the glass is fragile and the plastic is weak to a strong impact or force. This is leading to development of colorless composite materials. The related art colorless composite material is manufactured by impregnating glass fibers with typical transparent resin. However, the glass fiber and the typical transparent resin exhibit a great difference in, a refractive index variation according to the change of temperature. This may cause an optical transmittance variation according to the change of temperature.

Transparent composite material and a production method therefor


In one embodiment, an infusion set and sensor assembly delivered within a subject is disclosed. The assembly includes a cannula that is terminated at a cannula opening. The assembly further includes a sharp that is at least partially within the hollow of the cannula. A sensor having a proximal end and a distal end is also included in the assembly. The proximal end of the sensor is held in a fixed location while the distal end is retained with a portion of the cannula. The sensor further includes sensor slack, wherein transitioning the sharp from a first position to a second position simultaneously inserts the cannula and sensor to a desired insertion depth within a subject via a single point of insertion.

Diabetes is a growing healthcare crisis, affecting nearly 30 million people in the United States. Approximately 10 percent of those affected require intensive glucose and insulin management. In hospital patients, hypoglycemia in both diabetic and non-diabetic patients is associated with increased cost and short- and long-term mortality.
To prevent complications, diabetes requires ongoing management. Continuous glucose monitoring (CGM) has been shown in studies to be the most effective way to improve glucose control, whether used with insulin injections or a continuous insulin pump. CGM systems typically rely on sensors that are implanted under the skin for time periods varying between days and weeks. CGM has been optionally incorporated with infusion pump therapy. Used together CGM and an infusion pump enables an artificial pancreas system which have demonstrated improved both short and long term patient outcomes.
However, improvements in care and outcome would ideally not come at the expense of user comfort and convenience. Having to perform an insertion of the CGM sensors and an infusion set can be viewed as a hindrance or encumbrance that dissuade users from adopting an artificial pancreas system. Thus, it could be viewed as advantageous to minimize the number of insertions to enable an artificial pancreas system.
Accordingly, it would be highly advantageous to enable the insertion of a combined infusion set and sensor via a single insertion point. The claimed invention seeks to address many issues associated with single point insertion of a combined infusion set and sensor.


A sound determination unit previously divides sound into a low sound range for first sound, a middle sound range for second sound, and a high sound range for third sound by its frequency band. When sound information detected by the microphone is inputted to the sound determination unit, the sound determination unit determines whether the frequency band of that sound information is in the predetermined low sound range or not. When it is in the low sound range, a signal to operate a first vibrator is generated from a first controller. When it is in the middle sound range, a signal to operate a second vibrator is generated from a second controller. When it is in the high sound range, a signal to operate a third vibrator is generated from a third controller.

1. Field of the Invention
The present invention relates to a tool for stimulating a certain part of a human body and more particularly, it relates to a portable rhythm sensible tool through which a user can feel music information and sense its rhythm.
2. Description of the Background Art
Conventionally, a tool to stimulate a certain part of a human body is disclosed in Japanese Unexamined Patent Publication No. 2003-265569 (JP2003-265569), for example. As shown in FIG. 1, a massaging tool 1 disclosed in the JP2003-265569 comprises a vibrator 2 and a sensor 3 which responds to an incoming call of a cellular phone, and the vibrator 2 and the sensor 3 are connected through a connection cable 4.
According to the massaging tool 1, an incoming electric wave of the cellular phone is sensed by the sensor to change over ON/OFF of the vibrator 2.
According to the massaging tool 1 disclosed in the above document, an operation mode of the vibrator 2 can be changed regardless of intention of a user. However, since there are only two modes, that is, a vibrated mode and a non-vibrated mode as its operation mode, the operation mode is poor in variety.


The present inventors extensively studied and found that an antibody binding to PepT has cytotoxic activity and inhibits cell growth. These results suggest that an antibody binding to PepT, particularly an antibody having a cytotoxic activity, can be used as a cell growth inhibitor, for example, in treating and preventing cancer.

Mammalian animals need to take in external sources of nutrition and many transport proteins are known to exist in their cells. Many peptide transporters (peptide transport proteins; PepTs) that carry out peptide transport have been found to date (for example, J. Biol. Chem., 270(12):6456-6463, (1995); Biochim. Biophys. Acta., 1235:461-466, (1995); Mol. Microbiol., Vol. 16, p 825, (1995); Unexamined Published Japanese Patent Application No. (JP-A) Hei 6-261761; JP-A Hei 11-172; and U.S. Pat. No. 5,849,525). PepT can be classified into proteins that import peptides into cells and proteins that export peptides from cells. They can also be classified according to the different energy sources used during transport. Proton-driven PepTs, which carry out transport by utilizing protein gradient, belong to the PTR family (Mol. Microbiol., Vol. 16, p 825, (1995)). PepTs that carry out transport using ATP in the body belong to the ABC family (Annu. Rev. Cell. Biol., Vol. 8, p 67, (1992)).
There are reports that PepTs are involved in the transport of not only small-molecule peptides such as dipeptides and tripeptides, but also of pharmaceutical agents such as β-lactam antibiotics and ACE inhibitors (Ganapathy, Leibach., Curr. Biol. 3, 695-701, (1991); Nakashima et al., Biochem. Pharm. 33, 3345-3352, (1984); Friedman, Amidon., Pharm. Res., 6, 1043-1047, (1989); Okano et al., J. Biol. Chem., 261, 14130-14134, (1986); Muranushi et al., Pharm. Res., 6, 308-312, (1989); Friedman, Amidon., J. Control. Rel., 13, 141-146, (1990)).
PepT1 and PepT2 are proton-driven PepTs that contribute to the absorption of proteins and the maintenance of peptidic nitrogen sources by uptaking small-molecule peptides into cells. PepT1 and PepT2 are 12-transmembrane proteins, comprising 708 and 729 amino acids, respectively (J. Biol. Chem., 270(12):6456-6463, (1995); Biochim. Biophys. Acta., 1235:461-466, (1995); and Terada and Inui, Tanpakusitsu Kakusan Kouso., Vol. 46, No. 5, (2001)).
There are reports that PepT1 and PepT2 also transport pharmaceuticals such as β-lactam antibiotics and bestatin (Saito, H. et al., J. Pharmacol. Exp. Ther., 275, 1631-1637, (1995); Saito, H. et al., Biochim. Biophys. Acta., 1280, 173-177, (1996); and Terada, T. et al., J. Pharmacol. Exp. Ther., 281, 1415-1421 (1997)).
PepT1 is mainly expressed in the small intestine and its expression has been confirmed in the kidney and pancreas. Expression of PepT2 has been confirmed in the kidney, brain, lung, and spleen. PepT1 and PepT2 have been reported to be localized in the brush border membrane of intestinal and renal epithelial cells (Ogihara, H. et al., Biochem. Biophys. Res. Commun. 220, 848-852, (1996); Takahashi, K. et al., J. Pharmacol. Exp. Ther., 286, 1037-1042 (1998); Hong, S. et al., Am. J. Physiol. Renal. Physiol., 276, F658-F665 (1999); and Terada and Inui, Tanpakusitsu Kakusan Kouso., Vol. 46, No. 5, (2001)).
Furthermore, overexpression of PepT1 in the cell membrane of human pancreatic duct carcinoma cell lines (Cancer Res., 58, 519-525, (1998)) and the expression of PepT2 mRNA in human pancreatic duct carcinoma cell lines (Millennium World Congress of Pharmaceutical Sciences, (2000)) have been reported. However, the involvement of PepT1 and PepT2 in cancer cell growth was unclear and no discussion had been made as to whether PepT1 and PepT2 when used as target antigens against antibodies will affect cancer cell proliferation.

Cell growth inhibitor containing anti-PepT antibody


A system and method of wavefront sensing with a Shack-Hartmann wavefront sensor precisely locates focal spots on a detector array, and determines the location of the lenslet array with respect to the detector array.

1. Technical Field
This invention pertains to the field of wavefront sensing methods and devices, and more particularly, to a method and system for more precisely determining the location of a focal spot in a wavefront sensor, for more precisely determining the location of vertices or boundaries of lenslets in a lenslet array with respect to pixels of a wavefront sensor, for using this information to reconstruct an arbitrary wavefront with the wavefront sensor, and for more efficiently performing the calculations to perform the reconstruction.
2. Description
A light wavefront may be defined as the virtual surface delimited by all possible rays having an equal optical path length from a spatially coherent source. For example, the wavefront of light emanating from a point light source is a sphere (or a partial sphere where light from the point light source is limited to emission along a small range of angles). Meanwhile, the wavefront created by a collimating lens mounted at a location one focal length away from a point source is a plane. A wavefront may be planar, spherical, or have some arbitrary shape dictated by other elements of an optical system through which the light is transmitted or reflected.
A number of different wavefront sensors and associated methods are known. Among these are the Shack-Hartmann wavefront sensor, which will now be described in greater detail.
FIG. 1 shows a basic configuration of a Shack-Hartmann wavefront sensor 180. The Shack-Hartmann wavefront sensor 180 comprises a micro-optic lenslet array 182 that breaks an incoming beam into multiple focal spots 188 falling on an optical detector 184. Typically, the optical detector 184 comprises a pixel array, for example, a charge-coupled device (CCD) camera. The lenslets of the lenslet array 182 dissect an incoming wavefront and creates a pattern of focal spots on a charge-couple device (CCD) array. The lenslet array typically contains hundreds or thousands of lenslets, each on the size scale of a hundred microns. Most Shack-Hartmann sensors are assembled such that the CCD array is in the focal plane of the lenslet array.
A Shack-Hartmann wavefront sensor uses the fact that light travels in a straight line, to measure the wavefront of light. By sensing the positions of the focal spots 188, the propagation vector of the sampled light can be calculated for each lenslet of the lenslet array 182. The wavefront can be reconstructed from these vectors.
To better understand one or more aspects of this invention, it is worthwhile to discuss the operation of a Shack-Hartmann wavefront sensor in more detail.
In typical operation, a reference beam (e.g., a plane wave) is first imaged onto the array and the location of the focal spots is recorded. Then, the wavefront of interest is imaged onto the array, and a second set of focal spot locations is recorded. FIGS. 2A–F illustrate this process.
Usually, some optical system delivers a wavefront onto the lenslet array which samples the wavefront over the tiny regions of each lenslet. The lenslets should be much smaller than the wavefront variation, that is, the wave-front should be isoplanatic over the sampled region. When the CCD array is in the focal plane of the lenslet array, each lenslet will create a focal spot on the CCD array. The location of these focal spots is the critical measurement, for this reveals the average of the wavefront slopes across each region. That is, the shift in the focal spot is proportional to the average of the slopes of the wavefront over the region sampled by the lenslet. Software may compute the shift in each focal spot.
If the wavefront is not isoplanatic, the quality of the focal spot erodes rapidly and it becomes more difficult to determine the peak location.
However, where the isoplanatic condition is satisfied and where the focal spot shift is consistent with the small angle approximation of Fresnel, then the focal spot shift is exactly proportional to the average of the wavefront slope over the lenslet.
The incident wavefront is then reconstructed from the measurements of the average of the slopes for the hundreds or thousands of lenslets in the array.
It was stated above that the shift in the focal spot is proportional to the average of the slopes of the wavefront over the region sampled by the lenslet. This will now be shown as follows:
We begin by examining the types of wavefronts incident upon a lenslet and calculating their spatial irradiance distribution in the focal plane. We then resolve what this distribution tells us about the average value of the slopes of the sampled wavefront.
As noted above, most Shack-Hartmann sensors are assembled such that the CCD array is in the focal plane of the lenslet array. Therefore the appropriate complex amplitude distribution, Ff(u, v), of the field in the focal plane is given by the Fraunhofer diffraction pattern:
                                          F            f                                          (                          u              ,              v                        )                          =                                            exp                                            (                                  ⅈ                                                                                k                                          2                                            f                                                                                (                                                                  u                        2                                            +                                              v                        2                                                              )                                                  )                                                    ⅈ                                                                                λ                                                                                f                                                      ∫                                          ∫                                  -                  ∞                                ∞                                                                                F                    l                                                                          (                                          x                      ,                      y                                        )                                                                                exp                                                        (                                                                  -                        ⅈ                                                                                2                                                    π                                                                          λ                                                                                f                                                                                (                                                  xu                          +                          yv                                                )                                                              )                                                                                P                                                        (                                          x                      ,                      y                                        )                                                                                ⅆ                  x                                                                  ⅆ                  y                                                                                1        )            where the pupil function, P(x,y), describes the lens aperture. The function is 1 inside the lens aperture and 0 outside of the aperture. In the example that follows we will build the pupil function using the rectangle function, which is defined as:
                              π                                (            x            )                          =                  {                                                    0                                                                                for                                                                                                      x                                                                              >                                      1                    2                                                                                1                  2                                                                                for                                                                                                      x                                                                              =                                      1                    2                                                                                1                                                                                for                                                                                                      x                                                                              >                                      1                    2                                                                                2        )
the field Fl(u, v)incident upon the lenslet is related to the wavefront ψ(x, y) incident upon the lenslet through:F1(x,y)=exp(−iΨ(kx,ky))  3)
where k is the wavenumber, 2π/λ. The spatial irradiance distribution in the focal plane is related to the field amplitude by:I(x,y)=F(x,y)F*(x,y)  4)
The first step was to model the portion of the wavefront sampled by the lenslet. We begin with planar wavefronts and advance to wavefronts with more structure. Consider the first six simple cases in a Taylor series:Ψ00(x,y)=1Ψ10(x,y)=xΨ01(x,y)=yΨ20(x,y)=x2Ψ11(x,y)=xyΨ02(x,y)=y2
These six wavefronts were then analyzed using equation (2). Before presenting the results for the corresponding intensity distributions, a few functions must be defined. First is the sampling function:
                              sin                                                              cx                =                              sin                                                                          x                    x                                    (        5        )
then the error function:
                              erf                                (            x            )                          =                              2                          π                                                                    ∫              0              x                                                                  ⅇ                                  -                                      t                    2                                                                                ⅆ                t                                                                        (        6        )
and the imaginary error function:erfi(x)=−ierf(ix)  (7)
and finally the exponential integral function:
                              ei                                (            x            )                          =                  -                                    ∫                              -                z                            ∞                                                                                ⅇ                                      -                                          t                      2                                                                      t                                                          ⅆ                t                                                                        (        8        )
The intensity distributions can now be written in terms of these general functions. The first is the well-known result:
                                          I            10                                          (                          x              ,              y                        )                          =                                            (                                                d                  2                                                  f                                                                                λ                                            )                        2                                                                        sin                                                                                c              2                                                  (                                                                    π                                                                                d                                                        f                                                                                λ                                                                  x                            )                                                                                sin                                                                                c              2                                                  (                                                                    π                                                                                d                                                        f                                                                                λ                                                                  y                            )                                                          (        9        )
The next two results are also for planar wavefronts with tilt. They are:
                                          I            10                                          (                          x              ,              y                        )                          =                                            (                                                d                  2                                                  f                                                                                λ                                            )                        2                                                                        sin                                                                                c              2                                                  (                                                                    π                                                                                d                                                        f                                                                                λ                                                                                (                                      x                    -                    f                                    )                                            )                                                                                sin                                                                                c              2                                                  (                                                                    π                                                                                d                                                        f                                                                                λ                                                                  y                            )                                                          (        10        )                        and                                                                            I            10                                          (                          x              ,              y                        )                          =                                            (                                                d                  2                                                  f                                                                                λ                                            )                        2                                                                        sin                                                                                c              2                                                  (                                                                    π                                                                                d                                                        f                                                                                λ                                                                  x                            )                                                                                sin                                                                                c              2                                                  (                                                                    π                                                                                d                                                        f                                                                                λ                                                                                (                                      y                    -                    f                                    )                                            )                                                          (        11        )
We expect the symmetry under interchange of x and y in equations (10) and (11) since space is isotropic and the lenslet has a discrete symmetry under rotations by integer multiples of 90°.
For the case of nonplanar wavefronts the results quickly become more complicated. To present these results, first define the intermediate variables:
                                                        α              =                                                                    2                                                                                π                                                                                df                                    +                                      λ                                                                                y                                                                    2                                    f                                                                                λ                                                                          and                                              β              =                                                                    2                                                                                π                                                                                df                                    -                                      λ                                                                                y                                                                    2                                    f                                                                                λ                                                                                (        12        )
The intensity distribution can now be written as:
                                          I            20                                          (                          x              ,              y                        )                          =                              -                          1              π                                                                    (                              d                f                            )                        2                                          (                                          erfi                                                  (                  za                  )                                            +                              erfi                                                  (                                      z                                                                                β                                    )                                                      )                                          (                                          erfi                                                  (                  iza                  )                                            +                              erfi                                                  (                                      i                                                                                z                                                                                β                                    )                                                      )                                                                        sin                                                                                c              2                                                  (                                                                    π                                                                                d                                                        f                                                                                λ                                                                  x                            )                                                          (        13        )
For both I20(x,y) and I02(x,y) we see the symmetry in the solutions under interchange of x and y. The intermediate variables now become:
                                                        α              =                                                                    2                                                                                π                                                                                df                                    +                                      λ                                                                                x                                                                    2                                    f                                                                                λ                                                                          and                                              β              =                                                                    2                                                                                π                                                                                df                                    -                                      λ                                                                                x                                                                    2                                    f                                                                                λ                                                                                (        14        )            and the irradiance distribution in the focal plane is:
                                          I            02                                          (                          x              ,              y                        )                          =                              -                          1              π                                                                    (                              d                f                            )                        2                                          (                                          erfi                                                  (                  za                  )                                            +                              erfi                                                  (                                      z                                                                                β                                    )                                                      )                                          (                                          erfi                                                  (                  iza                  )                                            +                              erfi                                                  (                                      i                                                                                z                                                                                β                                    )                                                      )                                                                        sin                                                                                c              2                                                  (                                                                    π                                                                                d                                                        f                                                                                λ                                                                  y                            )                                                          (        15        )
Finally we consider the case where the input wavefront exhibits some torsion. First define the intermediate variables:
                                                                        α                1                            =                                                                    2                                                                                π                                                                                df                                    +                                      λ                                                                                x                                                                    2                                    f                                                                                λ                                                                          and                                                              α                2                            =                                                                    2                                        π                                                                                df                                    -                                      λ                                                                                x                                                                    2                                    f                                                                                λ                                                                                (        16        )
                                                                        β                1                            =                                                                    2                                                                                π                                                                                df                                    +                                      λ                                                                                y                                                                    2                                                                                f                                                                                λ                                                                          and                                                              β                21                            =                                                                    2                                                                                π                                                                                df                                    -                                      λ                                                                                y                                                                    2                                    f                                                                                λ                                                                                (        17        )
Then the irradiance distribution can be written as:
                                          I            11                                          (                          x              ,              y                        )                          =                                            (                              λ                                  4                                                                                π                    2                                                              )                        2                                          (                                          ei                                                  (                                                            ia                      1                                                                                β                      2                                                        )                                            -                              ei                                                  (                                                            ia                      1                                                                                β                      2                                                        )                                            -                              ei                                                  (                                                            -                                              ia                        2                                                                                β                      1                                                        )                                            +                              ei                                                  (                                                            -                                              ia                        2                                                                                β                      2                                                        )                                                      )                    ×                      (                                          ei                                                  (                                                            -                                              ia                        1                                                                                β                      12                                                        )                                            -                              ei                                                  (                                                            ia                      1                                                                                β                      2                                                        )                                            -                              ei                                                  (                                                            ia                      2                                                                                β                      1                                                        )                                            +                              ei                                                  (                                                            -                                              ia                        2                                                                                β                      2                                                        )                                                      )                                              (        18        )
Clearly the solutions in equations (9)–(11) are even functions and they are separable. That is, the irradiance distributions for these three functions can be written X(x)Y(y). The next three functions are not separable as the function arguments mix the variables x and y. However, a careful analysis of the constituent functions in equations (6)–(8) reveals that the combinations in equations (13), (15) and (18) are even functions also.
Now we address the issue of how the amplitude of these input wavefronts affects the focal spot position. Consider that the wavefront has an amplitude κ. The incident wavefronts become:Ψ00(x,y)=κΨ10(x,y)=κxΨ01(x,y)=κyΨ20(x,y)=κx2Ψ11(x,y)=κxyΨ02(x,y)=κy2
These new wavefronts were again propagated through the lenslet using equation (1). As one might expect, there was no change in I00(x,y). The irradiance distributions for the odd parity terms become:
                                          I            10                                          (                          x              ,              y                        )                          =                                            (                                                f                                                                                λ                                d                            )                        2                                                                        sin                                                                                c              2                                                  (                                                                    π                                                                                d                                                        f                                                                                λ                                                                                (                                      x                    -                                          κ                                                                                f                                                        )                                            )                                                                                sin                                                                                c              2                                                  (                                                                    π                                                                                d                                                        f                                                                                λ                                                                  y                            )                                                          (        19        )                        and                                                                            I            01                                          (                          x              ,              y                        )                          =                                            (                                                f                                                                                λ                                d                            )                        2                                                                        sin                                                                                c              2                                                  (                                                                    π                                                                                d                                                        f                                                                                λ                                                                  x                            )                                                                                sin                                                                                c              2                                                  (                                                                    π                                                                                d                                                        f                                                                                λ                                                                                (                                      y                    -                                          κ                                                                                f                                                        )                                            )                                                          (        20        )
For the higher order cases, there is a slight rewrite. For example for I20(x), the intermediate variables become:
                                                        α              =                                                                    2                                                                                π                                                                                d                                                                                κ                                                                                f                                    +                                      λ                                                                                y                                                                    2                                    f                                                                                λ                                                                          and                                              β              =                                                                    2                                        π                                                                                d                                                                                κ                                                                                f                                    -                                      λ                                                                                y                                                                    2                                    f                                                                                λ                                                                                (        21        )            and the irradiance distribution in equation (13) is then multiplied by κ−1/2. For the torsion case ψ11(x, y) the intermediate variables are:
                                                                        α                1                            =                                                                    2                                                                                π                                                                                d                                                                                κ                                                                                f                                    +                                      λ                                                                                x                                                                    2                                    f                                                                                λ                                                                          and                                                              α                2                            =                                                                    2                                        π                                                                                d                                                                                κ                                                                                f                                    -                                      λ                                                                                x                                                                    2                                    f                                                                                λ                                                                                (        22        )                                                                                β                1                            =                                                                    2                                                                                π                                                                                d                                                                                κ                                                                                f                                    +                                      λ                                                                                y                                                                    2                                    f                                                                                λ                                                                          and                                                              β                2                            =                                                                    2                                        π                                                                                d                                                                                κ                                                                                f                                    -                                      λ                                                                                y                                                                    2                                    f                                                                                λ                                                                                (        23        )            and the irradiance distribution in equation 18 is then multiplied by κ−2.
However, the only peaks that shift position are I10(x,y) and I01(x,y). And both of these shifts are exactly in the focal plane. The question now becomes how does this compare to the average value of the wavefront slopes?
The average value of the wavefront slope is given by:
                              m          x                =                                            ∫                                                -                  d                                /                2                                            d                /                2                                                                                ∫                                                      -                    d                                    /                  2                                                  d                  /                  2                                                                                ∂                    x                                                                          ψ                                                              (                                              x                        ,                        y                                            )                                                                                ⅆ                  x                                                                                ⅆ                  y                                                                          d            2                                              (        24        )            and similarly for my. The six input wavefronts and their average slopes m=(mx, my) are:ψ00(x,y)=κ mT=(0,0)ψ10(x,y)=κx mT=(0,0)ψ01(x,y)=κy mT=(κ,0)ψ20(x,y)=κx2 mT=(0,κ)ψ11(x,y)=κxy mT=(0,0)ψ02(x,y)=κy2 mT=(0,0)
So for these six cases, which are the most physically relevant, the average of the wavefront slope exactly describes the shift of the peak in the focal plane accounting for the distance offset of the focal length. Because of this exact relationship, it is convenient for us to define the focal spot location as being the location of the peak intensity of the focal spot.
For the purposes of this discussion, we define "isoplanatic" as the condition where the wavefront is well approximated over an area the size of the lenslet, by a plane wave.
This analysis buttresses the lore of Shack-Hartmann wavefront sensing. The shift in the focal spot position is directly proportional to the average of the wavefront slope across the lenslet. In the small angle limit inherent in the Fresnel approximation, this is an exact result for the isoplanatic cases and also true for the higher terms examined, although focal spot location is ambiguous in these cases as well as for additional higher order terms. An important issue that has not been discussed is how combinations of these terms behave. This is an important issue that is quite relevant physically.
FIGS. 3A–F and 4A–F show some exemplary incident wavefronts and output irradiance distributions in the focal plane. The lenslet is a square of size d=280μ and has a focal length f=28 mm; the wavelength λ=325 nm.
FIGS. 3A–C show the functional form of some exemplary incident wavefronts which all have a generally planar structure. FIGS. 3D–F graphically shows the corresponding wavefronts incident upon the lenslet. Note that in these examples over 95% of the light is confined to an area the size of a lenslet. The x and y axes are in microns. The vertical scale in the first column is also in microns. The vertical axis on the second column represents intensity and is in arbitrary units.
FIGS. 4A–C show a series of increasingly more complicated incident wavefronts. Clearly the focal spots are degrading rapidly where the incident wavefront has a non-planar structure. Notice the concept of a peak is ambiguous here and a center of mass computation of focal spot location could be highly problematic. Also, only a small portion of the light falls within the lenslet area. The x and y axes are in microns. The vertical scale in the first column is also in microns. The vertical axis on the second column represents intensity and is in arbitrary units.
FIGS. 3A–F and 4A–F validate the well known rule of thumb: the wavefront sensor works best in the isoplanatic limit. In other words, the lenslet size should be much smaller than the variations one is attempting to measure. Of course practical wavefront sensor design includes many other considerations too and one cannot shrink the lenslet size arbitrarily. But the message is that in the isoplanatic limit we expect to find well-defined focal spots that the center of mass can handle with higher precision.
So, to recap, a Shack-Hartmann wavefront sensor is a powerful tool for optical analysis, however the precision of the wavefront data that it produces may be less than is desired at times, and the speed and ease by which an incident wavefront may be reconstructed are also sometimes less than desirable.
First, it is difficult to precisely locate the focal spots produced by the lenslet array. Although the center of mass may be computed as an approximation of the focal spot location, more precision is desired. The basic problem with center of mass algorithms lies with deciding which pixels to include in the calculation. All cameras have a background level of electronic noise. The center of mass algorithm is especially sensitive to noise away from the brightest pixel because of weighting of the calculation by distance. To exclude this effect, a threshold is usually applied that excludes all pixels below some absolute brightness level. This threshold may be further refined after this preliminary step according to how bright the light is under a lenslet. To see the effect of this threshold, a calculation can be done using the center of mass. The sinc-squared intensity pattern can be overlaid with a discrete section of CCD pixels. The continuous intensity pattern is broken into discrete pixelated values as counts. Then the center of mass algorithm can be applied to the pixelated values. Then a calculation can be done where the sinc-squared pattern is translated into small steps across the fixed CCD. This corresponds to the situation where tilt is added in small steps to the beam as it hits the lenslet. The center of mass location can be plotted against the known tilt added to the beam. When this process is done, it will be seen that the center of mass will follow a straight line up to the point where a new pixel starts to receive enough light to be counted (or another pixel got too little light.). At that point, there will be an abrupt jump in the line. The appearance will be a line with lots of little kinks in it. On the average, the input translation versus center of mass calculation will produce a line with a slope of one. So it is evident that if there are kinks in the line, the slopes of all the little straight sections of lines must be something different than the ideal slope of one. The kinks and the non-unity piecewise slopes indicates that center of mass calculations have a fundamental flaw that makes them unsuitable for being the basis of wavefront measurements if extremely high accuracies are desired.
Secondly, in general, a lenslet boundary will not line up neatly with a pixel boundary. Instead the boundary line will likely cross through pixels. For precise wavefront measurements, it is important to precisely determine the location of the vertices or boundaries of lenslets in a lenslet array with respect to pixels (e.g., CCD array) of a corresponding wavefront sensor. This knowledge is needed in order to assign locations of the boundaries of the lenslets to locations on the CCD.
Third, it is difficult to take a series of hundreds or thousands of measurements of the average of the slopes and reconstitute the incident wavefront. This process of taking the measurements and reconstituting the wavefront incident upon the lenslet array is called reconstruction and can be quite computationally intensive and time-consuming.
Accordingly, it would be desirable to provide a system and method of more accurately locating the focal spots in a wavefront sensor. It would also be desirable to provide a system and method for to precisely determine the location of the vertices or boundaries of lenslets in a lenslet array with respect to pixels (e.g., CCD array) of a corresponding wavefront sensor. Furthermore, it would be desirable to provide a system and method for reconstructing a wavefront from measurement data provided by a pixel array in a wavefront sensor. Even furthermore, it would be desirable to provide a system and method for efficiently computing polynomials for defining a wavefront detected by a wavefront sensor. And, it would be desirable to provide such a system and method which overcomes one or more disadvantages of the prior art.
The present invention comprises a system and method for sensing a wavefront.
In one aspect of the invention, a method of determining a location of a focal spot on a detector array improves upon a "pure" center of mass calculation. When a near plane wave illuminates a square lens, the focal spot has a sinc-squared shape. This knowledge can be exploited to generate a number of improvements to calculating the focal spot peak location.
Several techniques show improvement over pure center of mass methods for locating a focal spot. One technique uses the knowledge that the sinc-squared function has minimum in it before the side lobes appear. The focal spot location algorithm can be written so these minima are located, and then the pixels that are identified as being proper to include in the center of mass calculation will be those that lie within the minima. Another technique is that the shape of the sinc-square function can be fit to values that show up in each pixel. This can be done with least squares method or by "sliding" methods. Then the equation for the sinc-squared gives the location of the peak. Still another refinement is to use a different weighting than a linear weight from center in the calculation of center of mass. The effect is to reduce weight given to dimmer pixels. In particular, this weight can be matched to provide piecewise linear slopes of one, although this reduces the dynamic range of the sensor unless another method is found to eliminate the kinks.
In another aspect of the invention, a method of determining a location and size of a lenslet with respect to a detector array exploits a-priori knowledge of the spacing of the lenslets in a lenslet array. Such a-priori knowledge can be produced by direct measurement of the lenslet arrays by microphotography, by knowledge of the photolithography process, or by other means. In a particularly advantageous manufacturing process, the spacing between lenslet is extremely regular. Accordingly, when one compares algorithms that calculate focal spot locations, the better algorithm is the one that comes up with a the locations in the most regular grid. This can be done on a theoretical basis using the sinc-squared patterns as inputs, or on experimental data using a plane wave to illuminate the lenslet array. Further refinements can be obtained by adding tilt to the plane wave and doing least squares fit to determine spacings.
In a similar way, non-uniform grids can be defined if it is desired to manufacture lenslet arrays with non-uniform spacings.
In yet another aspect of the invention, a method of reconstructing a wavefront from a plurality of focal spots produced on a detector array, includes.
In still another aspect of the invention, a method of determining a set of polynomials defining a wavefront from a plurality of focal spots produced on a detector array, includes.


This invention modifies the microstructure of semiconductor nanocrystallite embedded glass by following a prescribed process schedule, so that it can be a solid state laser active medium. The crystalline phase of the glass consists of uniformly dispersed nanometer size single crystals which belong to one of the following semiconductor compounds: ZnS.sub.x Se.sub.1-x, CdS.sub.x Se.sub.1-x, ZnS.sub.x Te.sub.1-x, ZnSe.sub.x Te.sub.1-x, CuCl.sub.x Br.sub.1-x, InP, Al.sub.x Ga.sub.1-x As, GaInAsP, AlGaAsSb, InAsSbP, and AlGaInP, where x=0 to 1.. Some of the semiconductor nanocrystallite embedded glass has a tunable range which overlaps that of the visible dye lasers, therefore it can be used as a replacement for the existing liquid dyes as the active media utilized in the tunable dye laser systems.

The present invention pertains to how to produce and to use semiconductor nanocrystallite embedded glass as a tunable laser active medium. Most tunable lasers use liquid solutions of organic dyes as active lasing media. Since the wavelength, bandwidth, or pulse length of the tunable dye laser can be varied within a range using different dyes in combination with proper optical resonantor designs, the dye laser has been a major workhorse in the advancement of laser spectroscopy. However, the dye molecules react photochemically upon irradiation causing material degradation problems. The design which uses a stable region of a thin dye solution film through a jet nozzle as the active lasing host has lessened the photochemical degradation problem. However, the stability of the jet is still of concern, because it can not be ensured. In addition, the maintenance of the liquid dye circulation system and occasional change of dye solutions demands skilled technical support. Therefore, the search for solid state variants to replace the liquid tunable dye lasers is attractive. Organic dye impregnated polymer or glass as replacement for the dye solution has been considered but so far no product has been developed. The problems are mostly in the area of light induced dye chemical changes at the dye solution/host interface upon irradiation. Recently, Ti-Saphire has been introduced as a tunable solid state laser host. It is tunable in dye laser wavelengths. But the price of Ti-Saphire is high and its tunable range is narrow. It is still far from being able to replace the dye laser.
The semiconductor nanocrystallite embedded glass can be categorized as one of the glass/crystallites composites because it contains more than one phase. The semiconductor crystallite embedded glass is photorefractive due to its high .sub..chi..sup.(3) values. The potential application in holographic data storage, and phase conjugation using this glass has been considered. Some of the semiconductor crystallite embedded glass has been used as a sharp cut-off filter in the optical industry for years. The photoluminescence properties of the sharp cut-off filters has been studied and published before. But no attention has been paid to their potential as tunable laser host materials. This invention modifies the microstructure of the semiconductor nanocrystallite embedded glass so that it can be a practical alternative for replacing the liquid dye in tunable lasers.
The semiconductor nanocrystallite embedded glass contains two distinctly different phases. The glassy phase is composed largely of silicate tetrahedra networks which serve as structural support and transparent window for the semiconductor crystalline phase. The crystalline phase is composed of numerous semiconductor single crystals which are referred to as nanocrystallites here. It is the nanocrystallite which serves as the laser active media. The lasing property of the nanocrystallite is dictated by its composition and its microstructure. The composition determines its peak wavelength of flourescence, and the microstructure determines its fluorescence bandwidth. The microstructure of semiconductor nanocrystallite can be characterized by the size distribution, number density, and the spatial distribution within the glass matrices. Due to the isotropic nature of the glass structure, the orientation of the nanocrystallite is random. Usually, compound semiconductor crystals belong to wursite or zincblend structure and are likely to have direct band gaps. Compound semiconductor single crystals have definite band gap energy depending on the relative chemical composition of the compounds and their orientations. If one assumes that each crystallite resembles a spherical particle, the relative composition, x, varies along its axis. The value of x is the smallest at the core and it increases along the axis. The range of variation is small but is critical for the emission efficiency.
Each of the compound semiconductors possesses a characteristic band gap energy. The magnitude of the band gap energy correlates to a specific wavelength edge below which the irradiation will be absorbed. For instance, zinc sulfide selenide (ZnS.sub.x Se.sub.1-x) absorbs any irradiation wavelength shorter than 450 nm. The shifting of the edge can be obtained by varying the value of x. Optically pumped single crystal platlets used as a laser host have been reported at cryogenic temperatures. The high refractive index of the bulk and high absorption coefficient at fluorescent wavelength hinders the further development of the optically pumped single crystal compound semiconductor.
The semiconductor nanocrystallite embedded glass possess a strong absorption of photons with energy greater than the band gap energy of the nanocrystallite. In contrast to the compound semiconductor single crystal, it has a smaller refractive index and a very low absorption in flourescence wavelength. These factors facilitate conditions favorable for laser application. Dispersed nanocrystallite with each single crystal sizes smaller than 20 nm will prevent concentrated absorption and subsequential heating. Consequently, the penetration depth in the glass ceramics increases and so does the pumping efficiency. The absorbed energy generates electron-hole pairs within the semiconductor nanocrystallite. The generated electrons and holes migrate according to the local electrical field, since there is no net external electrical field imposed on the material, the generated electrons and holes migrate in pairs and are subject to random fluctuation of the local environment. Consequently, the electron and hole pairs recombine and annihilate each other at a characteristic rate called the spontaneous recombination rate. At the same time, photons are emited with a wavelength range corresponding to the energy differences between the recombining pairs of electrons and holes. The emitted photons stimulate further electron hole pair recombinations and facilitate the neccessary coherence for lasing. The emission wavelength is usually longer than that of absorption. This prevents resonant absorption at band gap energy and avoids bleaching of the material. The emission spectrum can be characterized using two parameters: first, full width at half maximum (FWHM), and second, the peak wavelength. For instance, ZnS.sub.x Se.sub.1-x (x=0.09) nanocrystallite embedded glass has photoluminescence spectrum of FWHM=50 nm, and peak at 520 nm. The inhomogeneous broadening of the spectrum is due to the random orientation of the crystallites. This is the major factor which contributes to the wavelength tunability of the lasers.
The size distribution, the spatial distribution, and the number density of the semiconductor nanocrystallite within the glass matrices, and the relative constituents composition (i.e., spatial distribution of x) within each semiconductor nanocrystallite are major attributes for tunable laser application using semiconductor nanocrystallite embedded glass as hosts. This invention provides process information for producing optimized semiconductor nanocrystallite embedded glass. In addition, it also provides the preferred geometrical design of the semiconductor nanocrystallite embedded glass for replacing organic dye solution in a tunable dye laser.

Moving disks made of semiconductor nanocrystallite embedded glass


In a method for capturing three-dimensional data of an area of space, a plurality of measuring beams (Ls) are sent out to a plurality of measuring points. A detector (50) receives a plurality of reflected beams (Lr) which are reflected by the measuring points (34a). A plurality of distances to the measuring points (34a, 34b) are determined as a function of the reflected beams (Lr). According to one aspect of the invention, at least one object (30) which comprises a hidden channel (66) having a visible entry opening (72) is located in the area of space. A rod-shaped element (32) is inserted into the channel (66) in such a manner that a free end proximal portion (70) protrudes from the entry opening (72). A first distance to a first measuring point (34a) and a second distance to a second measuring point (34b) are determined. An orientation (74) of the hidden channel (66) is determined as a function of the first and the second distances.

The present invention relates to a method for capturing three-dimensional data of an area of space, comprising the steps of:                providing a laser scanner having a transmitter and a receiver,        sending out a plurality of measuring beams by means of the transmitter to a plurality of measuring points in the area of space,        receiving a plurality of reflected beams which are reflected by the measuring points, and        determining a plurality of distances to the plurality of measuring points as a function of the reflected beams.
The invention also relates to an apparatus for capturing three dimensional data of an area of space, comprising a laser scanner having a transmitter and a receiver, the transmitter being configured for sending out a plurality of measuring beams to a plurality of measuring points in the area of space, the receiver being configured for receiving a plurality of reflected beams which are reflected by the measuring points and for determining a plurality of distances to the plurality of measuring points as a function of the reflected beams.
Such a method and such an apparatus are known, for example, from DE 103 61 870 B4.
This document discloses a laser scanner comprising a measuring head which holds a rotor rotatably supported. The rotor is rotated about a horizontal axis whilst sending out a plurality of laser beams. Due to the rotation of the rotor, the laser beams are sent out into a plurality of directions in space which cover an elevation angle of 270° or more. In addition, the measuring head is rotated about a vertical axis so that the laser beams sent out almost completely scan the surrounding area of space. In the measuring head, a receiver is arranged which receives the reflected beams reflected from object points in the area of space and which determines the distances to the object points by means of a difference in delay time between the beams sent out and the received beams. In addition, the receiver generates for each measuring point a gray scale value which depends on the intensity of the reflected measuring beam. Altogether, this known laser scanner can be used for recording a three-dimensional image of an area of space, the plurality of gray scale values producing an all-rotund image which is comparable to a black/white recording of the area of space. In addition, a distance information item is provided for each measuring point so that the area of space can be examined more accurately, surveyed and/or documented later by means of the recorded data. A typical application for such a laser scanner is the surveying of factory halls in which, for example, a new production line is to be planned and set up. In another known application, such a laser scanner is moved through a tunnel tube (if necessary without rotation about the vertical axis) in order to check, e.g., the state of the tunnel and determine the clear width at every point in the tunnel.
In principle, such a laser scanner is suitable for capturing three-dimensional data of any area of space which is bounded by objects such as walls or natural obstacles. The relatively fast and extensive data acquisition including an "optical image" of the area of space in an all-round view also allows such a laser scanner to be advantageous for forensic applications, i.e. the coverage and documentation of crime scenes. However, forensic coverage of a crime scene requires further information which cannot be supplied by laser scanners hitherto known. This includes primarily information about the location and the course of bullet channels produced when a projectile penetrates into a wall or into another obstacle.
For the forensic coverage of bullet channels, rods marked with colours colors are used today which rods are inserted into a bullet channel in such a manner that a proximal end proximal-portion of the rods protrudes protrude from the entry opening of the bullet channel. These rods can be used for identifying the orientation of the bullet channel. Suitable rods are offered, for example, by the Lightning Powder Company, Inc., 13386 International Parkway, Jacksonville, Fla. 32218, USA.
Against this background, it is an object of the present invention to improve a method and an apparatus of the type initially mentioned in order to open up new applications. In particular, it is an object of the invention to facilitate the forensic data capture of an area of space.

Method and an apparatus for capturing three-dimensional data of an area of space