Title of Invention: Optical pickup apparatus, recording/reproducing apparatus provided with the optical pickup apparatus, optical element, and information recording/reproducing method Abstract: An optical pickup apparatus for reproducing information from an optical information recording medium or for recording information onto an optical information recording medium, is provided with a first light source for emitting first light flux having a first wavelength; a second light source for emitting second light flux having a second wavelength, the first wavelength being different from the second wavelength; a converging optical system having an optical axis and a diffractive portion, and a photo detector; wherein in case that the first light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the first light flux is greater than that of any other ordered diffracted ray of the first light flux, and in case that the second light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the second light flux is greater than that of any other ordered diffracted ray of the second light flux, where n stands for an integer other than zero. Detailed Description: Part general_description_paragraphs: This is a continuation of application Ser. No. 09/487,928, filed Jan. 20, 2000, which is incorporated herein by reference now U.S. Pat. No. 6,870,805. Part BACKGROUND OF THE INVENTION: The present invention relates to an optical pickup apparatus, a recording/reproducing apparatus with the optical pickup apparatus, an optical element, and an information recording/reproducing method. Recently, as the practical application of the short wavelength red laser, a DVD which is a high density optical information recording medium (called also optical disk) having almost the same dimension as a CD (compact disk) and the larger capacity, comes into the production. In a DVD recording/reproducing apparatus, the numerical aperture NA on the optical disk side of an objective lens when a semiconductor laser of 650 nm is used, is 0.6–0.65. The DVD has a track pitch of 0.74 μm, and the minimum pit length of 0.4 μm, and is in densification, in which dimensions are lower than a half as compared to the CD having the track pitch of 1.6 μm and the minimum pit length of 0.83 μm. Further, in the DVD, in ordered to suppress the coma which is generated when the optical disk is inclined to the optical axis, to be small, the transparent substrate thickness is 0.6 mm, which is the half of the transparent substrate thickness of the CD. Further, other than the above-described CD or DVD, various standard optical disks in which the light source wavelength or the transparent substrate thickness is different, for example, CD-R, RW (post script type compact disk), VD (video disk), MD (mini-disk), MO (photo-electro-magnetic disk), etc., come in the market and are spread. Further, the wavelength of the semiconductor laser is further shortened, and the short wavelength blue laser having the emission wavelength of about 400 nm is being into practical use. When the wavelength is shortened, even if the same numerical aperture as that of the DVD is used, the capacity of the optical information recording medium can be further increased. Further, in the same dimension as the CD which is the above-described conventional optical information recording medium, the development of a plurality of optical information recording media, such as the CD-R in which recording and reproducing can be carried out, or the DVD whose recording density is increased, in which the transparent substrate thickness of the recording surface, or the wavelength of the laser light for recording and reproducing is different, is advanced, therefore, it is required that the recording and reproducing by the same optical pickup can be conducted to these optical information recording medium. Accordingly, various optical pickups which have a plurality of laser light sources corresponding to the using wavelength, and by which the laser light is converged onto the recording surface by the same objective lens by the necessary numerical aperture, are proposed (for example, Japanese Tokkaihei No. 8-55363, Japanese Tokkaihei No. 10-92010, etc.). In the above description, in Japanese Tokkaihei No. 9-54973, an optical system using a hologram optical element in which 635 nm is used for the transmitted light (zero ordered diffracted ray)and 785 nm is used for—first ordered diffracted ray, and an optical system using a hologram optical system in which 635 nm is used for +first ordered diffracted ray and 785 nm is used for the transmitted light (zero ordered diffracted ray), are disclosed. Further, in Japanese Tokkaihei No. 10-283668, an optical system in which, the wavelength is 650 nm, a hologram ring lens is transmitted at 100%, and when 780 nm, the light is first ordered diffracted by the hologram ring lens, is disclosed. However, in these hologram element and hologram-shaped ring lens, when diffraction efficiency of zero ordered light is made to be 100% for the wavelength on one side, there surely is a limitation for diffraction efficiency of +first ordered diffracted ray or of—first ordered diffracted ray for the wavelength on the other side, and thereby, desirable high diffraction efficiency can not be obtained, a loss of a quantity of light is caused, and efficiency of using a quantity of light is worsened, which has been a problem. When a loss of a quantity of light is caused, a laser of higher power is required, especially in recording of information. Further, in the hologram element and the hologram-shaped ring lens, when diffraction efficiency of zero ordered light is made to be 100% for the wavelength on one side, and when diffraction efficiency of +first ordered diffracted ray or of—first ordered diffracted ray is made to be great by prohibiting zero ordered light from being transmitted as far as possible, for the wavelength on the other side, the hologram has been made to be as deep as 3.8–5.18 μm. Therefore, when a function of a hologram optical element or of a hologram-shaped ring lens is integrated in an objective lens in particular, it is very difficult to process a metal mold and to mold, which has been a problem. Further, the present inventors previously proposed an objective lens (Japanese Tokuganhei No. 9-286954) which can structure a optical pickup which is composed of a plurality of divided surface which are divided into concentric circular-like ones, and in which each divided surface is aberration corrected to the diffraction limit to a plurality of light sources having different wavelength, and/or to the transparent substrate having the different thickness of the recording surface, and the structure is simplified. This objective lens has a function by which a necessary aperture can be automatically obtained corresponding to the using wavelength and/or the thickness of the transparent substrate. However, when a laser/detector integrated unit in which the laser light source and light detector are integrated, is used, there is a problem that a case occurs that the detection can not be correctly conducted due to a flare light entering into the light detector. This is conspicuous particularly in the laser/detector integrated unit of a type by which the light flux is deflected and introduced into the light detector by using the hologram. Further, when high speed recording is carried out in recordable disks in the DVD system (DVD-RAM, DVD-R, DVD-RW, DVD+R, etc.) or recordable disks in the CD system (CD-R, CD-RW, etc.), because a partial light beam becomes flare, the efficiency of use of the light amount is bad as compared to the optical system using the exclusive use lens, therefore, it is necessary to increase the power of laser light source. To both the DVD and CD whose using wavelength and transparent substrate thickness are different from each other, various interchangeable optical systems, in which one objective lens is used for recording and/or reproducing the information without generating large spherical aberration or chromatic aberration, are proposed. However, the optical systems which are in practical use, are structured such that the divergence degree of the divergent light flux from the light source is weakened by a coupling lens, or the divergent light flux is made to the parallel light flux or the weak convergent light flux, and the light flux is converged onto the information recording surface through the objective lens and the transparent substrate of the optical information recording medium, and accordingly, 2 lenses of the coupling lens and the objective lens are necessary. Accordingly, it is difficult that the size of the optical pickup apparatus is reduced to be small and thin, and there is a problem that the cost is increased. On the one hand, as described above, various optical disks except the CD and DVD are spread, and therefore, an optical system which is interchangeable to these optical disks, and whose structure is simple, and the optical pickup apparatus provided with the optical system are necessary. Part SUMMARY OF THE INVENTION: An object of the invention is to provide a pickup apparatus, a recording and reproducing apparatus, an optical element and a recording and reproducing method, wherein one pickup apparatus can conduct recording and/or reproducing of different types of optical information recording media employing rays of light with at least two different wavelengths. Further object is to make information recording and/or information reproducing to be conducted by one pickup apparatus, for each different optical information recording medium without generating serious spherical aberration and chromatic aberration even in the case of using rays of light having at least two different wavelengths and applying to different types of optical information recording media. In addition to that, another object is to provide an optical pickup apparatus having s simple structure. In particular, when using different types of optical information recording media each having a transparent substrate with a different thickness, the problem of spherical aberration becomes more serious. Further object is that one pickup apparatus can conduct recording and/or reproducing of information for different types of optical information recording media without generating serious spherical aberration and chromatic aberration, even in the aforesaid occasion. In addition, still further object is that detection of light by an photo detector can be conducted satisfactorily and sigmoid characteristics in detection are made to be satisfactory, without irradiation of flare light which affects the detection adversely on an photo detector, even in the case of a pickup apparatus employing an integrated unit composed of plural lasers and plural detectors. Furthermore, providing an optical pickup apparatus wherein a loss of a quantity of light is less and efficiency of using a quantity of light is excellent, a recording and reproducing apparatus, an optical element and a recording and reproducing method is also an object of the invention. The above object can be attained by the following structures and methods. (1) An optical pickup apparatus for reproducing information from an optical information recording medium or for recording information onto an optical information recording medium, comprises: a first light source for emitting first light flux having a first wavelength; a second light source for emitting second light flux having a second wavelength, the first wavelength being different from the second wavelength; a converging optical system having an optical axis and a diffractive portion, and a photo detector; wherein in case that the first light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the first light flux is greater than that of any other ordered diffracted ray of the first light flux, and in case that the second light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the second light flux is greater than that of any other ordered diffracted ray of the second light flux, where n stands for an integer other than zero. (2) An optical element for use in an optical pickup apparatus for reproducing information from an optical information recording medium or for recoding information onto an optical information recording medium, comprises: an optical axis, and a diffractive portion, wherein in case that the first light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the first light flux is greater than that of any other ordered diffracted ray of the first light flux, and in case that the second light flux whose wavelength is different from that of the first light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the second light flux is greater than that of any other ordered diffracted ray of the second light flux, wherein a difference in wavelength between the first light flux and the second light flux is 80 nm to 400 nm and n stands for an integer other than zero. (3) An apparatus for reproducing information from an optical information recording medium or for recording information onto the optical information recording medium comprises; an optical pickup apparatus, comprising a first light source for emitting first light flux having a first wavelength; a second light source for emitting second light flux having a second wavelength, the first wavelength being different from the second wavelength; a converging optical system having an optical axis, a diffractive portion, and a photo detector, wherein in case that the first light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the first light flux is greater than that of any other ordered diffracted ray of the first light flux, and in case that the second light flux passes through the diffractive portion to generate at least one diffracted ray, an amount of n-th ordered diffracted ray of the second light flux is greater than that of any other ordered diffracted ray of the second light flux, where n stands for an integer other than zero. (4) A method of reproducing information from or recording information on at least two kinds of optical information recording media by an optical pickup apparatus comprising a first light source, a second light source, a photo detector and a converging optical system having an optical axis and a diffractive portion, the method comprises steps of; emitting first light flux from the first light source or second light flux from the second light flux, wherein a wavelength of the second light flux is different from a wavelength of the first light flux; letting the first light or the second light flux pass through the diffractive portion to generate at least one diffracted ray of the first light flux or a least one diffracted ray of the second light flux, wherein when an amount of n-th ordered diffracted ray among the at least one diffracted ray of the first light flux is greater than an amount of any other ordered diffracted ray of the first light flux, an amount of n-th ordered diffracted ray among the at least one diffracted ray of the second light flux is greater than an amount of any other ordered diffracted ray of the second light flux, converging, by the converging optical system, the n-th ordered diffracted ray of the first light flux onto a first information recording plane of a first optical information recording medium or the n-th ordered diffracted ray of the second light flux onto a second information recording plane of a second optical information recording medium in order for the optical pickup apparatus to record the information onto or reproduce the information from the first information recording plane or the second information recording plane, detecting, by a photo detector, a first reflected light flux of the converged n-th ordered diffracted light from the first information recording plane or a second reflected light flux of the converged n-th ordered diffracted light from the second information recording plane; where n stands for an integer other than zero. Part DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT: An optical pickup apparatus for reproducing information from an optical information recording medium or for recording information onto an optical information recording medium has therein a first light source for emitting first light flux having a first wavelength, a second light source for emitting second light flux having a second wavelength, the first wavelength being different from the second wavelength, a converging optical system having an optical axis, a diffractive portion, and a photo detector. Further, the diffractive portion generates more n-th ordered diffracted ray than other ordered diffracted ray in the first light flux which has passed the diffractive portion, and generates more n-th ordered diffracted ray than other ordered diffracted ray also in the second light flux which has passed the diffractive portion. n stands for an integer other than zero. The optical element of the invention is one having a diffraction portion which makes the aforesaid embodiment possible. An apparatus for reproducing information from an optical information recording medium or for recording information onto the optical information recording medium has the optical pickup apparatus stated above. (11-1) Incidentally, “an amount of n-th ordered diffracted ray being greater than that of any other ordered diffracted ray 11” means that the diffraction efficiency for the n-th ordered diffracted ray is higher than that for the other ordered diffracted ray other than the n-th ordered diffracted ray. Further, n in n-th ordered includes also a sign, and when +first ordered diffracted ray is generated more than other ordered diffracted ray in the first light flux which has passed the diffractive portion, it is intended that +first ordered diffracted ray is generated more than other ordered diffracted ray even in the second light flux which has passed the diffractive portion, and it does not include that—first ordered diffracted ray is generated more than other ordered diffracted ray in the second light flux which has passed the diffractive portion. (11-2) The optical pickup apparatus of the invention is one wherein one pickup apparatus can conduct recording and/or reproducing optical information recording media in different types employing at least two wavelengths each being different from others. Namely, the optical pickup apparatus of the invention is one used for recording/reproducing of different information recording media such as a first optical information recording medium and a second optical information recording medium. A first light source of the optical pickup apparatus emits first light flux for reproducing information from a first optical information recording medium or for recording information onto the first optical information recording medium, while, a second light source of the optical pickup apparatus emits second light flux for reproducing information from a second optical information recording medium or for recording information onto the second optical information recording medium. Usually, an optical information recording medium has a transparent substrate on an information recording plane. (11-3) When putting the function of the invention in another way, the converging optical system is capable of converging “n-th ordered diffracted ray of the first light flux”, which is generated at the diffractive portion by the first light flux being reached the diffractive portion, on a first information recording plane of the first optical information recording medium through a first transparent substrate, to reproduce information recorded in the first optical information recording medium or to record information onto the first optical information recording medium, and the converging optical system is capable of converging “n-th ordered diffracted ray in the second light flux”, which is generated at the diffractive portion by the second light flux being reached the diffractive portion, on a second information recording plane of the second optical information recording medium through a second transparent substrate, to reproduce information recorded in the second optical information recording medium or to record information onto the second optical information recording medium, and the photo detector is capable of receiving light flux reflected from the first information recording plane or the second information recording plane. (11-4) There will be shown as follows the embodiment which is more preferable, wherein the converging optical system is capable of converging n-th ordered diffracted ray in the first light flux on a first information recording plane of the first optical information recording medium under the state that wave-front aberration is not larger than 0.07 λrms within the prescribed numerical aperture of the first optical information recording medium in the first light flux on the image side of the objective lens (in other words, under the state wherein the light flux within the prescribed numerical aperture takes diffraction limit capacity or less in the best image point (best focus)), and the converging optical system is capable of converging n-th ordered diffracted ray in the second light flux on a second information recording plane of the second optical information recording medium under the state that wave-front aberration is not larger than 0.07 λrms within the prescribed numerical aperture of the second optical information recording medium in the second light flux on the image side of the objective lens (in other words, under the state wherein the light flux within the prescribed numerical aperture takes diffraction limit capacity or less in the best image point (best focus)). Further, it is preferable that n-th ordered diffracted ray is converged under the state that wave-front aberration is not larger than 0.07 λrms within the prescribed numerical aperture on the image side of the objective lens on each information recording plane, even in the case of wavelength shift of about ±10 nm or less caused by temperature fluctuation and electric current fluctuation, in the first light source or in the second light source. In particular, it is especially preferable that n-th ordered diffracted ray is converged under the state of 0.07 λrms or less within the prescribed numerical aperture on the image side of the objective lens, even when the first light flux or the second light flux is one having a wavelength of 600 nm or less (for example, 350 nm–480 nm) and wavelength shifting of about ±10 nm or less is generated. (11-5) Incidentally, when n-th ordered diffracted ray is +first ordered diffracted ray or—first ordered diffracted ray, a loss of a quantity of light is less than that in an occasion where a diffracted ray of higher ordered than ±first ordered is used, which is preferable. Further, when a diffraction efficiency of n-th ordered diffracted ray of the first light flux in the diffractive portion is represented by A % and a diffraction efficiency of diffracted ray of other certain-th ordered (preferably, the number of ordered with the greatest diffraction efficiency among number of ordered other than n) is represented by B %, it is preferable to satisfy A−B≧10, while, when a diffraction efficiency of n-th ordered diffracted ray of the second light flux in the diffractive portion is represented by A′ % and a diffraction efficiency of diffracted ray of other certain-th ordered is represented by B′ %, it is preferable to satisfy A′−B′≧10. The condition of A−B≧30 and A′−B′≧30 is more preferable, that of A−B≧50 and A′−B′≧50 is still more preferable, and that of A−B≧70 and A′−B′≧70 is further more preferable. (11-6) When both of the first light flux and second light flux are used for recording of information on optical information recording medium, it is preferable that diffraction efficiency of n-th ordered diffracted ray in the diffractive portion is made to be maximum at the wavelength between the wavelength of the first light flux and the wavelength of the second light flux. (11-7) When either of the first light flux and second light flux alone is used for recording of information on optical information recording medium and the other light flux is used for reproduction only, it is preferable that diffraction efficiency of n-th ordered diffracted ray in the diffractive portion is made to be minimum at the wavelength between the wavelength of the first light flux and the wavelength of the second light flux. The more preferable is that the diffraction efficiency of the n-th ordered diffracted ray in the diffractive portion is made to be maximum at one of the wavelength of the first light flux and the wavelength of the second light flux in using for recording of information. (11-8) As an optical element on which the diffractive portion is provided, a lens having a refraction surface and a flat type element both provided on the converging optical system are given, though there is no limitation in particular. When a lens having a refraction surface as an optical element on which a diffractive portion is provided, there are given an objective lens, a collimator lens and a coupling lens as a concrete example of the optical element. On the refraction surfaces on each of these lenses, a diffractive portion can be provided. A flat-shaped or lens-shaped optical element which is intended only to be provided with a diffractive portion may also be added to a converging optical system. Incidentally, when providing a diffraction portion on a refraction surface of an objective lens, it is preferable that an outside diameter of the objective lens (outside diameter including a flange if the flange is provided) is larger than an aperture diameter by 0.4 mm–2 mm. (11-9) The diffractive portion may be provided either on an optical surface of the optical element on the light source side, or on the image side (optical information recording medium side), or on both sides. Further, the diffractive portion may be provided either on the convex surface or on the concave surface. (11-10) When a diffractive portion is provided on an objective lens, it is more preferable because the number of parts is reduced and errors in assembly of an optical pickup apparatus in manufacturing can be reduced. In that case, it is preferable that the objective lens is of a single-element type, but it may also be of a two-element type. A plastic lens is preferable, but a glass lens is also acceptable. It is also possible to provide on the surface of a glass lens a resin layer on which a diffractive portion is formed. It is preferable that the objective lens on which the diffractive portion is provided has on its outer circumference a flange section having a surface extending in the direction perpendicular to an optical axis. This makes it easy to mount on the pickup apparatus accurately, and makes it possible to obtain stable performance even when ambient temperature fluctuates. It is further preferable that the refraction surface of the objective lens is an aspheric surface and a diffractive portion is provided on the aspheric surface. The diffractive portion may naturally be provided either on one side of the objective lens or on both sides thereof. (11-11) Further, it is preferable that an optical element on which a diffractive portion is provided is made of a material with Abbe's number νd of not less than 50 and not more than 100. It may either be made of plastic or be made of glass. Incidentally, in the case of a plastic lens, it is preferable that a refractive index of its material is in a range of 1.4–1.75, and the range of 1.48–1.6 is more preferable and that of 1.5–1.56 is further preferable. When the diffractive portion is provided on a lens (preferably on a plastic lens), it is preferable that the following conditional expression is satisfied, for obtaining an optical pickup apparatus and an optical element which are stable against temperature fluctuation. −0.0002/° C.<Δn/ΔT<−0.00005° C. wherein, ΔT: Temperature fluctuation Δn: Amount of change of refractive index of the lens It is further preferable to satisfy the following conditional expression. 0.05 nm/° C.<Δλ1/ΔT<0.5 nm/° C. wherein, Δλ1 (nm): Amount of change of wavelength of first light source for temperature fluctuation ΔT (11-12) The diffractive portion is preferably a phase type one from the viewpoint of efficiency of using light, though it may also be an amplitude type one. It is preferable that the diffractive pattern of the diffractive portion is shaped to be symmetry rotatable in relation to the optical axis. It is preferable that the diffractive portion has plural annular bands when viewed in the direction of the optical axis, and these plural annular bands are formed mostly on the concentric circle whose center is on the optical axis or in the vicinity of the optical axis. A circle is preferable, but it may also be an ellipse. A blaze type ring-zonal diffraction surface having steps is especially preferable. It may further be a ring-zonal diffraction surface which is formed stepwise. It may further be a ring-zonal diffraction surface which is formed stepwise as annular bands which shift discretely in the direction where lens thickness is greater as its position becomes more distant from the optical axis. Incidentally, it is preferable that the diffractive portion is ring-zonal, but it may also be a 1-dimensional diffraction grating. (11-13) When the diffraction portion represents concentric circles in a ring-zonal form, a pitch of diffraction annular bands is defined by the use of a phase difference function or an optical path difference function. In this case, it is preferable that a coefficient other than zero is owned by at least one term other than a squared term in a phase difference function expressed by a power series which shows positions of plural annular bands. Due to this structure, it is possible to correct spherical aberration of chromatic aberration caused by rays of light each having a different wavelength. (11-14) When a coefficient other than zero is owned by a squared term in a phase difference function expressed by a power series which shows positions of plural annular bands of the diffractive portion, paraxial chromatic aberration can be corrected, which is preferable. However, when it is important not to make a pitch of diffraction annular bands to be too small, it is also possible to make the phase difference function expressed by a power series which shows positions of plural annular bands of the diffractive portion to include no squared term. (11-15) Incidentally, it is preferable that the number of steps of diffraction annular bands of the diffractive portion is in a range from 2 to 45. The more preferable is not more than 40. Still further preferable is not more than 15. Incidentally, counting of the number of steps is achieved by counting the number of stepped sections of annular bands. Further, it is preferable that a depth of the stepped section of diffraction annular bands of the diffraction portion in the direction of the optical axis is not more than 2 μm. Due to this structure, an optical element can be manufactured easily, and n-th ordered diffracted ray can easily be made to be +first ordered diffracted ray or—first ordered diffracted ray. Further, when providing a diffraction portion on the surface of an optical element on the light source side, it is preferable that a depth of a stepped section becomes greater as the stepped section becomes more distant from an optical axis. (11-16) With regard to the effect of the diffractive portion to deflect the light flux, in the present specification, the case that the light flux is deflected toward the optical axis is called as the positive effect, on the other hand, the case that the light flux is deflected so as to be shifted away from the optical axis is called as the negative effect. With regard to the pitch on the ring-zonal diffraction surface, there may also be provided a pitch wherein a pitch is provided to be inversely proportional to a height from an optical axis. It is also possible to provide a pitch having aspheric characteristics wherein the way of providing a pitch is not inversely proportional to a height from an optical axis. In particular, when providing a pitch having aspheric characteristics, namely, when a pitch is not provided to be inversely proportional to a height from an optical axis, it is preferable that there is no point of inflection in the function of optical path difference, though there may also be the point of inflection. Further, the diffraction effect added in the diffractive portion may either be positive on the entire surface of the diffractive portion, or be negative on the entire surface of the diffractive portion. It is also possible to arrange so that a plus or minus sign of the diffraction effect added in the diffractive portion is switched at least one time in the direction to become more distant from the optical axis in the direction perpendicular to the optical axis. For example, there is given a type wherein a sign is changed from minus to plus in the direction to become more distant from the optical axis in the direction perpendicular to the optical axis, as shown in FIG. 47(c). In other words, it can be said that plural annular bands of the diffractive portion are blazed, and on the diffractive annular band closer to the optical axis, its stepped section is positioned to be away from the optical axis, and on the diffractive annular band farther from the optical axis, its stepped section is positioned to be closer to the optical axis. There can also be given a type wherein a sign is changed from plus to minus in the direction to become more distant from the optical axis in the direction perpendicular to the optical axis, as shown in FIG. 47(d). In other words again, it can be said that plural annular bands of the diffractive portion are blazed, and on the aforesaid diffractive annular band closer to the optical axis, its stepped section is positioned to be closer to the optical axis, and on the diffractive annular band farther from the optical axis, its stepped section is positioned to be farther from the optical axis. Incidentally, the pitch (zone distance) of diffraction annular bands means distance p in FIG. 134 between a step of a annular band and a step of its adjacent annular band in the direction perpendicular to the optical axis, while, a depth of the step means length d in FIG. 134 of the step in the optical direction. (11-17) Incidentally, when the pitch is smaller, converging effect and diverging effect on that portion become stronger, and when pitch is greater, converging effect and diverging effect on that portion become weaker Further, the diffractive portion may also be provided on the entire portion of the surface through which a light flux passes, in an optical element having a diffractive portion. In other words, it can be said that it is also possible to arrange so that the all light flux within the maximum numerical aperture at an image side of an objective lens may pass through the diffractive portion. A diffractive portion may also be provided simply on the entire portion on one optical surface of an optical element, or not less than 70% (not less than 80% is preferable and not less than 90% is more preferable) of one optical surface of the optical element may be made to be a diffractive portion. (11-18) Further, the diffractive portion may also be provided on only a part of the surface of an optical element through which a light flux passes, to make another area to be a refraction surface or a transmission surface, in an optical element. When a diffractive portion is provided only on a part of the surface through which a light flux passes, the diffractive portion may be provided only on a portion in the vicinity of an optical axis including the optical axis, or the diffractive portion may be provided to be in a ring shape, without being provided to be in the vicinity of the optical axis. For example, a diffractive portion may be provided on 10% or more and less than 90% of one surface in optical surfaces of an optical element. Or, 10% or more and less than 50% of one surface may be made to be a diffractive portion. (11-19) Incidentally, when providing a diffractive portion only on a part of the surface of an optical element through which a light flux passes, NA1>NAH1, NAH1≧NA2, NA2≧NAL1≧0 is preferable in the case of NA1>NA2. In the case of NA2>NA1, NA2>NAH2, NAH2≧NA1, NA1≧NAL2≧0 is preferable. Incidentally, each of NA1 and NA2 is a prescribed numerical aperture of an objective lens on the image side, when using the first light flux and the second light flux respectively. Each of NAH1 and NAH2 is a numerical aperture of the objective lens on the image side for each of the first light flux and the second light flux passing through the outermost side of the diffractive portion. Each of NAL1 and NAL2 is a numerical aperture of the objective lens on the image side for each of the first light flux and the second light flux passing through the innermost side of the diffractive portion. (11-20) When the diffractive portion is provided only on a part of the surface of an optical element through which a light flux passes, it is preferable that the light flux which has passed the diffraction portion at NA1 or less in the first light flux and light which has passed the refraction surface at NA1 or less other than the diffractive portion are converged at mostly the same position, in the case of NA1>NA2. In the case of NA2>NA1, it is preferable that the light flux which has passed the diffraction portion at NA2 or less in the second light flux and light which has passed the refraction surface at NA2 or less other than the diffractive portion are converged at mostly the same position. An embodiment wherein the diffractive portion has the first diffraction pattern and the second diffraction pattern, and the second diffraction pattern is farther than the first diffraction pattern in terms of a distance from the optical axis. It is possible to combine a diffractive portion and a refraction surface having no diffractive portion on the same plane. (11-21) When two types of diffraction patterns are used, it is also possible to arrange so that n-th ordered diffracted ray is generated more than other ordered diffracted ray in the first light flux which has passed the first diffraction pattern of the diffractive portion and is capable to be converged on a first information recording plane, and n-th ordered diffracted ray is generated more than other ordered diffracted ray also in the second light flux which has passed the first diffraction pattern of the diffractive portion and is capable to be converged on a second information recording plane, and n-th ordered diffracted ray is generated more than other ordered diffracted ray in the first light flux which has passed the second diffraction pattern of the diffractive portion and is capable to be converged on a first information recording plane, while, 0-th ordered light representing transmitted light is generated more than other ordered diffracted ray in the second light flux which has passed the second diffraction pattern of the diffractive portion. The n-th ordered in this case is preferably first ordered. (11-22) Further, in another embodiment, n-th ordered diffracted ray is generated more than other ordered diffracted ray in the first light flux which has passed the first diffraction pattern of the diffractive portion and is capable to be converged on a first information recording plane, and n-th ordered diffracted ray is generated more than other ordered diffracted ray also in the second light flux which has passed the first diffraction pattern of the diffractive portion and is capable to be converged on a second information recording plane, and 0-th ordered diffracted ray is generated more than other ordered diffracted ray in the first light flux which has passed the second diffraction pattern of the diffractive portion and is capable to be converged on a first information recording plane, while, diffracted ray not of n-th ordered but of negative ordered is generated more than other ordered diffracted ray in the second light flux which has passed the second diffraction pattern of the diffractive portion. The n-th ordered in this case is preferably +first ordered, and negative ordered is preferably—first ordered. (11-23) In the case of an optical pickup apparatus or an optical element used in plural optical information recording media each having a different thickness of a transparent substrate, it is especially preferable that a pitch of annular bands of the diffraction portion satisfies the following conditional expression. 0.4<=|(Ph/Pf)−2|<=25 The more preferable is 0.8≦|(Ph/Pf)−2|≦6, and further preferable is 1.2≦|(Ph/Pf)−2|≦2 (11-24) A pitch of annular bands of the diffractive portion corresponding to the maximum numerical aperture of the objective lens on the image side is represented by Pf, and a pitch of annular bands of the diffractive portion corresponding to ½ of the maximum numerical aperture is represented by Ph. Incidentally, with regard to the maximum numerical aperture, the greatest one among prescribed numerical apertures of some types of optical information recording media subjected to information reading/recording in an optical pickup apparatus is regarded as the maximum numerical aperture. Incidentally, the prescribed numerical aperture means a numerical aperture which makes reading/recording of information on optical information recording medium by a light flux which has a prescribed wavelength possible in its optical pickup apparatus, but it may also be a numerical aperture stipulated by the standard of a certain optical information recording medium. Further, “a pitch of annular bands of the diffractive portion corresponding to the maximum numerical aperture of the objective lens on the image side” means a pitch of annular bands located at the outermost portion of the light flux passing through the diffraction portion in the case of the maximum numerical aperture. “A pitch of annular bands of the diffractive portion corresponding to ½ of the maximum numerical aperture” means a pitch of annular bands located at the outermost portion of the light flux passing through the diffraction portion in the case of the numerical aperture which is a half of the maximum numerical aperture. (11-25) Incidentally, there will be accepted an optical pickup apparatus wherein up to the prescribed numerical aperture is made to be no-aberration for one light flux among two light fluxes respectively from two light sources, and for the portion outside the prescribed numerical aperture, aberration is made to be flare. (11026) In other words, it can be said as follows. The first light flux which is within a prescribed numerical aperture, of a first optical information recording medium, of the objective lens on the image side in the case of using a first light flux is converged on a first information recording plane of the first optical information recording medium under the state of 0.07 λrms or less, and the first light flux passing through the outside of the prescribed numerical aperture of the objective lens on the image side in the case of using a first light flux is made to be greater than 0.07 λrms on a first information recording plane, and the second light flux passing through the prescribed numerical aperture of the objective lens on the image side in the case of using a first light flux as well as the second light flux passing through the outside of the aforesaid numerical aperture are converged on a second information recording plane under the state of 0.07 λrms or less. In this case, NA1 is smaller than NA2, and a light flux between NA1 and NA2 is made to be flare when recording and reproducing the first optical information recording medium. (11-27) Or, the second light flux which is within a prescribed numerical aperture, of a second optical information recording medium, of the objective lens on the image side in the case of using a second light flux is converged on a second information recording plane of the second optical information recording medium under the state of 0.07 λrms or less, and the second light flux passing through the outside of a prescribed numerical aperture of the objective lens on the image side in the case of using a second light flux is made to be greater than 0.07 λrms on a second information recording plane, and the first light flux passing through the prescribed numerical aperture of the objective lens on the image side in the case of using a second light flux as well as the first light flux passing through the outside of the aforesaid numerical aperture are converged on a first information recording plane under the state of 0.07 λrms or less. In this case, NA1 is greater than NA2, and a light flux between NA2 and NA1 is made to be flare, when recording and reproducing the second optical information recording medium. These embodiments can be established voluntarily by the design of a diffraction portion. For example, it is possible either to provide a diffractive portion on the entire surface of an optical element and thereby to generate flare at the prescribed numerical aperture or more by designing the diffractive portion, or to provide a diffractive portion on a part of the surface of an optical element and to make the other part to be a refraction surface so that flare may be generated by the refraction surface and the diffractive portion. (11-28) In the embodiment to generate flare stated above, it is preferable that an aperture regulating means to block or diffract the first light flux outside a prescribed numerical aperture of the objective lens on the image side in the case of using the first light flux and to transmit the second light flux and an aperture regulating means to block or diffract the second light flux outside a prescribed numerical aperture of the objective lens on the image side in the case of using the second light flux and to transmit the first light flux are not provided. Namely, it is preferable to provide an ordinary aperture only without providing a dichroic filter or a hologram filter. If the diffractive portion is only designed to satisfy the aforesaid function, it is enough to provide only an ordinary aperture, which is preferable because a mechanism is simple. (11-29) However, it is also possible to use a filter such as a hologram filter to generate flare. Incidentally, when providing a filter such as a hologram filter, a separated filter may be provided in the optical converging system, or a filter may be provided on the objective lens. It is possible either to provide flare to be under for the position to make the minimum spot when the light flux located where the prescribed numerical aperture is more smaller are converged, or to provide flare to be over. The preferable is to provide to be over. When generating flare as stated above, it is possible to generate flare continuously on the spherical aberration diagram or to generate flare discontinuously. Further, an another embodiment, there is given an embodiment of an optical pickup apparatus wherein no flare is generated. The following one is given. (11-30) In other words, it is possible to express as follows. The first light flux which is within a prescribed numerical aperture, of a first optical information recoding medium, of the objective lens on the image side in the case of using the first light flux is converged on a first information recording plane of a first optical information recording medium under,the state of 0.07 λrms or less, and the first light flux which has passed the outside of a prescribed numerical aperture of the objective lens on the image side in the case of using the first light flux is converged on the first information recording plane under the state of 0.07 λrms or less, or it is blocked and does not reach the first information recording plane. The second light flux which has passed the inside of a prescribed numerical aperture of the objective lens on the image side in the case of using the first light flux, and the second light flux which has passed the outside of a prescribed numerical aperture are converged on a second information recording plane of a second optical information recording medium under the state of 0.07 λrms or less. In this case, N1 is smaller than NA2, and a light flux between NA1 and NA2 is also converged or blocked, when conducting recording or reproducing for the first optical information recording medium. (11-31) Or, the second light flux which is within a prescribed numerical aperture, of a second optical information recoding medium, of the objective lens on the image side in the case of using the second light flux is converged on a second information recording plane of a second optical information recording medium under the state of 0.07 λrms or less, and the second light flux which has passed the outside of a prescribed numerical aperture of the objective lens on the image side in the case of using the second light flux is converged on the second information recording plane under the state of 0.07 λrms or less, or it is blocked and does not reach the second information recording plane. The first light flux which has passed the inside of a prescribed numerical aperture of the objective
{'bibliographic_information': "{'country': 'US', 'doc-number': '10612019', 'kind': 'B2', 'date': '20030703', 'extension': '649', 'disclaimer_text': 'This patent is subject to a terminal disclaimer.', 'invention_title': 'Optical pickup apparatus, recording/reproducing apparatus provided with the optical pickup apparatus, optical element, and information recording/reproducing method'}", 'source_file': './grant/2007/ipg070206.xml', 'source_data': 'USPTO-Grant'}