Abstract: A crystal for flow cytometry with dual laser beams is disclosed. The crystal is a birefringent crystal comprising a material composition including a quartz mineral having a face side including a face angle of ninety degrees plus or minus one tenth of a degree; a wedge side that is substantially perpendicular to the face side, wherein the wedge side includes a wedge angle of two degrees plus or minus one tenth of a degree; and a major side that is substantially perpendicular to the face side and the wedge side. The major side includes a thickness of one and one-half millimeter plus or minus one tenth of a millimeter. A polarized light beam entering the birefringent crystal at an incident angle is separated into an ordinary light beam and an extraordinary light beam.

Abstract: A method for assembling a first lens and a second lens is provided. The method includes performing an optical center measurement for at least one of the first lens or the second lens, and performing an optical center adjustment when the optical center measurement does not satisfy a predetermined optical center condition. The method also includes performing a polarimetric measurement for at least one of the first lens or the second lens, and performing a polarimetric angle adjustment when the polarimetric measurement does not satisfy a predetermined polarimetric condition. The method further includes assembling the first lens and the second lens to form an optical assembly.

Abstract: The first, third, fourth, and seventh photosensors are disposed on one side with respect to the centerline, and the second, fifth, sixth, and eighth photosensors are disposed on another side with respect to the centerline. The first and seventh photosensors are positioned between the third and fourth photosensors in the direction parallel to the centerline. The second and eighth photosensors are positioned between the fifth and sixth photosensors in the direction parallel to the centerline. The first photosensor receives overlapped light of the 0th-order light with the +1st-order diffracted light, the second photosensor receives overlapped light of the 0th-order light with the ?1st-order diffracted light, each of the third to sixth photosensors receives the 0th-order light, and does not receive the +1st-order diffracted light and the ?1st-order diffracted light, and each of the seventh and eighth photosensors receives at least the 0th-order light.

Abstract: An optical component, a hologram, and a photodetector are configured in an optical head device of an optical disc device such that a +1-order beam or a ?1-order beam of diffracted light generated from light reflected from an information track in the intended information recording layer strikes the interior of the light-receiving surfaces of the tracking error detection light-receiving sections, a +1-order beam or a ?1-order beam of diffracted light generated from light reflected from an information track in an information recording layer one layer deeper than the intended information recording layer strikes outside the light-receiving sections, and a +1-order beam or a ?1-order beam of diffracted light that is generated from light reflected from an information track in an information recording layer one layer shallower than the intended information recording layer strikes outside the light-receiving sections.

Abstract: In one embodiment of the present invention, an optical pickup for writing and reading data on an optical storage medium comprises a diffractive element for diffracting a light beam to split it into multiple light beams. The diffracted light beams includes a zero-order diffracted light beam for writing data on a track of the land or the groove of the optical storage medium and non-zero-order diffracted light beams for reading the data from the track. The diffractive element has first and second diffraction gratings that have mutually different grating vector directions and pitches. The first diffraction grating forms light beam spots on the same track by the non-zero-order and zero-order diffracted light beams. The second diffraction grating forms a light beam spot to extend to both sides of said track, or forms a light beam spot on one side of said track, by the non-zero-order diffracted light beams.

Abstract: In a small-sized optical pickup device for enabling to obtain a stable servo-signal, as well as, a focus error signal and a tracking error signal, without receiving ill influences of stray lights from other layers, when recording/reproducing a multi-layer optical disc, a reflection light from the multi-layer optical disc is divided into plural numbers of regions by a diffraction grating. And, it is divided into at least four (4) regions, by a division line in the tangential direction of the optical disc and a division line in the radial direction thereof. Light receiving parts, for detecting either one of grating diffraction lights, i.e.

Abstract: An optical pickup and an information storage medium system using the same. The optical pickup includes a light source that emits light having a plurality of different wavelengths. The optical pickup includes a diffraction device having a plurality of diffraction patterns corresponding to the plurality of different wavelengths to divide the light incident from the light source unit into main light and sub light. The optical pickup further includes a photo-detector having a first main light reception unit that receives the main light and a first sub light reception unit that receives the sub light so as to detect an information signal and/or an error signal by receiving reflected light. The first sub light reception unit of the photo-detector is shaped so as to reduce reception of noise sub light due to diffraction based on an undesired diffraction pattern of sub light generated the diffraction device.

Abstract: Disclosed are a module to detect a tracking error signal that is easy to be assembled and robust against variation in a track angle, a diffraction grating, an optical pickup, and an optical disc apparatus that enable the module to be realized, wherein a diffraction grating divided into at least three areas, first, second, and third areas, is used; the second area is an area that do not diffract light; and focusing positions of light diffracted by the first and third areas sandwiching the second area therebetween on an optical disc are arranged with a spacing of (2n?1)×t/2 in an optical disc radial direction, respectively, where n is a nonnegative integer and t is a spacing of guide grooves of the optical disc.

Abstract: For obtaining stable servo-signals without receiving ill influences of stray lights from other layers, on both a focus error signal and a tracking error signal, when recording/reproducing a multi-layer optical disc having small gap between layers thereof, a light beam is divided with using a first and a second diffraction gratings. The first diffraction grating is a polarization diffraction grating, and is mounted on an actuator. The second diffraction grating is disposed on a fixed portion. The first diffraction grating has a first region having a center of a light beam and other(s), and among signal lights reflecting from the disc, the light beam entering into the first region is diffracted, and the light beam entering into the second region transmits therethrough. The second diffraction grating transmits the light beam diffracting on the first region of the polarization diffraction grating therethrough, while diffracting the light beam diffracting on the second region.

Abstract: An optical pickup device includes a polarization diffraction grating to diverge an optical beam reflected from an optical disc and an optical detector to receive the optical beam diverged by the polarization diffraction grating, a polarization of 0 order diffracted light diffracted through the polarization diffraction grating is substantially perpendicular to that of a +1 order diffracted light diffracted therethrough, and a polarization filter having a plurality of domains is mounted between the polarization diffraction grating and the optical detector.

Abstract: There is provided a diffraction grating including a convex portion and a concave portion which are used for lights having different wavelengths ?1, ?2 and ?3 and are alternately disposed on at least one surface of a substrate with a predetermined pitch. An average refractive index of the convex portion is smaller than an average refractive index of the concave portion. A phase difference in the lights having the wavelength ?1 which transmit the convex portion and the concave portion and a phase difference in the lights having the wavelength ?2 which transmit the convex portion and the concave portion are both substantially the integral multiple of 2?, and a phase difference in the lights having the wavelength ?3 which transmit the convex portion and the concave portion is substantially the non-integral multiple of 2?.

Abstract: An optical pickup having a one-plane, two-wavelength diffraction grating and a two-wavelength laser generator is provided in which crosstalk noise caused by leakage of a track error signal into a focus error signal is reduced to improve focus control performance. A main beam and sub-beams generated by the one-plane, two-wavelength diffraction grating and reflected from the surface of an optical disc are incident on corresponding light receiving elements among which the one to receive the main beam and those to receive the sub-beams are relatively shifted in a linear-speed direction of the optical disc. The distance of the shifting is determined based on the characteristic, relative to the relative positions of the light receiving elements, of the leakage of the tracking error signal into the focus error signal detected based on the main beam and sub-beams.

Abstract: There is provided a diffraction grating including a convex portion and a concave portion which are used for lights having different wavelengths ?1, ?2 and ?3 and are alternately disposed on at least one surface of a substrate with a predetermined pitch. An average refractive index of the convex portion is smaller than an average refractive index of the concave portion. A phase difference in the lights having the wavelength ?1 which transmit the convex portion and the concave portion and a phase difference in the lights having the wavelength ?2 which transmit the convex portion and the concave portion are both substantially the integral multiple of 2?, and a phase difference in the lights having the wavelength ?3 which transmit the convex portion and the concave portion is substantially the non-integral multiple of 2?.

Abstract: An optical head device includes a diffraction grating which diffracts a part of the light beam which is selectively emitted from a semiconductor laser having two luminous points and is divided along a tangential direction of the track of the optical disk, a relationship of arrangement of the second and third regions corresponds to a relationship of the optical axes of the first and second light beams on the diffraction grating, the second region is located at a position crossing an optical axis of the first light beam, a phase difference between phases of the first and third regions is 180°, a phase difference between phases of the third and fourth regions is 180°, and the third region has a width which is not larger than amount of a position deviation of ±first-order diffracted light of the second light beam from zeroth-order diffracted light.

Abstract: An optical pickup device has a semiconductor laser emitting light which is in turn branched via a diffraction grating into at least three beams of light including a main beam and two sub beams which are in turn condensed via an objective lens on an optical disk at a guide groove and reflected by the optical disk to provide three reflections of light which are in turn received by detectors, each divided into two regions, respectively, to generate a tracking error signal. The diffraction grating is divided into three regions including a first region, a second region and a third region located intermediate therebetween, each having a periodical structure out of phase, the periodical structure having grating grooves in a direction determined depending on the phase of the second region to incline relative to a direction perpendicular to the guide groove of the optical disk.

Abstract: An optical controller includes a light source for emitting light, an object lens for condensing light emitted from the light source, a light detection unit for receiving light reflected on an optical information recording medium and outputting a signal corresponding to the amount of the light, and a laser control unit for controlling the amount of the light emitted from the light source to the information recording surface on which information is to be recorded or reproduced, based on the recording state of an information recording surface disposed closer to the object lens than an information recording surface on which the information is to be recorded or reproduced.

Abstract: An optical pickup apparatus and an optical recording/reproducing system including the same, the optical pickup apparatus includes at least two optical systems for different types of optical recording media, one of objective lenses of the optical systems being offset from a central line of the optical recording medium, wherein the optical system including the offset objective lens having a diffraction grating diffracting light emitted from a light source to form a main beam and sub-beams, wherein the diffraction grating includes first and second diffraction regions having different grating patterns arranged alternately thereon, and a center of each sub-beam is arranged at a boundary of the first and second diffraction regions of the diffraction grating, and a center of the diffraction grating and an optical axis of the light source are adjusted to be coincided with each other, preventing generation of an alternating current in a Push-Pull signal of the sub-beams.

Abstract: The present invention can simplify the configuration of a polarization adjustment plate. According to the present invention, the crystal axis of the polarization adjustment wavelength plate 32 is so arranged as to be turned up from the X-Y plane being an orthogonal plane with respect to the optical axis 40a, and the wavelength dependence which the crystal material is originally provided with is largely expressed, and further the thickness “ta” with respect to the optical axis 40a is set up such that the phase difference ? to be brought about at the beam center becomes low from 360°+180°=540° being a desired design value to irradiate the optical beam as the P-polarization by a predetermined difference value or 60°.

Abstract: An objective optical system is formed of a diffractive optical element with a diffractive surface formed on a virtual plane and an objective lens for focusing three light beams of three different wavelengths at three different numerical apertures onto desired positions of three different recording media with substrates that include different thicknesses, such as an AOD, a DVD, and a CD, that introduce different amounts of spherical aberration in the focused beams. The objective optical system provides compensating spherical aberrations to the three light beams, two of which are incident on the objective optical system as collimated beams and one of which is incident as a diverging beam. The objective optical system focuses second-order diffracted light of one wavelength and first-order diffracted light of the other two wavelengths. An optical pickup device includes the objective optical system, the recording media, and a light source that provides the three light beams.

Abstract: An objective lens consists of two lens elements of different materials that are cemented. The lens surfaces that are cemented includes a phase function so that the cemented surface forms a optical diffractive surface that enables the objective lens to focus incident light of three different wavelengths with different numerical apertures onto different optical recording media. Three conditions are satisfied so as to achieve optimum imaging. The optical diffractive surface is shaped so that the order of the diffracted light of the shortest wavelength ?1 having the largest diffracted intensity is zero and different from the order of the diffracted light of the second wavelength ?2 having the largest diffracted intensity, and the order of the diffracted light of the first wavelength ?1 having the largest diffracted intensity is also different from the order of the diffracted light of the third wavelength ?3 having the largest diffracted intensity.

Abstract: Part of reflected light from an optical disc enters a diffraction element (10). The ±first-order diffracted light and zero-order diffracted light from the diffraction device (10) travel via a cylindrical lens (11) and a spot lens (12) and enter a photodetector (13). If an objective lens shifts, a beam on the diffraction element (10) also shifts. Therefore, the intensity distribution of a spot of the zero-order diffracted light falling on light-receiving areas (A, B, C, D) of a four-part light-receiving element (13a) becomes bright as a whole, while the intensity distributions of spots of the ±first-order diffracted light falling on light-receiving areas (E, F) of light-receiving elements (13b, 13c) become dark as a whole. Thus, an optical pickup tracking error detecting method and an optical pickup device enabling good tracking control are provided.

Abstract: An optical head is provided, which suppresses the offset in the tracking error signal.

Abstract: An optical pickup head device includes a diffraction grating for generating zero-order diffracted light and at least first-order diffracted light and provides a tracking error signal with a DPP method. The diffraction grating includes grating patterns with a nonuniform period or phase. The size of the first-order diffracted light converged on an optical recording medium is larger in the direction parallel to a tangent to the track than in the direction perpendicular to the tangent. P1/P0>PW2/PW1 is established, where PW1 represents the power that is required to record information on the optical recording medium, PW2 represents the maximum power that allows information recorded on the optical recording medium to be reproduced without being erased, P0 represents the light amount of the zero-order diffracted light converged on the optical recording medium, and P1 represents the light amount of the at least first-order diffracted light converged on the optical recording medium.

Abstract: A polarizing optical element changes its optical reflectance and/or transmittance according to a polarization state of incoming light. The optical element includes: a first grating layer including multiple striped portions that extend in a predetermined direction; and a second grating layer including multiple striped portions that extend in that predetermined direction. Average grating pitches of the first and second grating layers are both defined to be shorter than the wavelength of the incoming light. The first grating layer is made of a first material that exhibits a light reflecting property to the incoming light. The second grating layer is made of a second material that reduces the reflection of the incoming light from the first grating layer.

Abstract: A magneto-optical disk drive that prevents the track shift signal from overlapping the MO signal, even when the optical head projects a divergent spherical wave onto the beam splitter. This objective is realized by a magneto-optical disk drive that uses an optical head which emits a divergent spherical wave onto a beam splitter surface of a beam splitter. Since the tracking error signal, which is overlapped by the MO signal of the MO detection unit, is synchronous with the tracking signal, a correction circuit is used to overlap the MO signal with the tracking error signal and to eliminate errors caused when the track shift signal overlaps the MO signal.

Abstract: A focus error detecting apparatus and a focus error detecting method of an optical pickup in which the system is not easily influenced by track transversal noises and an optical disc thickness error and which can be used together with a 3-beam system or a DPD system. The return light from an optical disc is divided to a first optical path and a second optical path by a hologram device, a predetermined astigmatism is applied to the light on each divided optical path, the light is received and detected by a first detector and a second detector, and a focusing error signal is obtained by predetermined arithmetic operations.

Abstract: An optical element that receives a first incident light and a second incident light through a main surface and allowing the first and second incident lights to be transmitted therethrough, the first and second incident lights being linearly polarized lights having substantially orthogonal polarizing directions and having different wavelengths &lgr;1 and &lgr;2 respectively, the optical element receiving a first reflected light and a second reflected light generated when the first and second incident lights are reflected from a reflector through the other face, and allowing the first and second reflected lights to be transmitted therethrough again, the optical element has a polarizing hologram that allows the first incident light, the second incident light, and the second reflected light to be transmitted therethrough upon receiving these lights and that diffracts the first reflected light upon receiving this light; and at least one wavelength plate that varies at least one of polarizing states of all of the f

Abstract: An optical information storage unit for reproducing information recorded on lands and grooves of a magneto-optical recording medium by means of a reflected light obtained from a luminous flux which has been emitted from a light source, irradiated onto the recording medium and reflected from the recording medium. The optical information storage unit includes a first wave plate on which the reflected light from the magneto-optical recording medium is incident; a diffraction grating on which the light having been transmitted through the first wave plate is incident; a second wave plate on which the light having been transmitted through the diffraction grating is incident; and a polarization detecting unit on which the light having been transmitted through the second wave plate is incident.

Abstract: An optical pickup head device includes a diffraction grating for generating zero-order diffracted light and at least first-order diffracted light and provides a tracking error signal with a DPP method. The diffraction grating includes grating patterns with a nonuniform period or phase. The size of the first-order diffracted light converged on an optical recording medium is larger in the direction parallel to a tangent to the track than in the direction perpendicular to the tangent. P1/P0>PW2/PW1 is established, where PW1 represents the power that is required to record information on the optical recording medium, PW2 represents the maximum power that allows information recorded on the optical recording medium to be reproduced without being erased, P0 represents the light amount of the zero-order diffracted light converged on the optical recording medium, and P1 represents the light amount of the at least first-order diffracted light converged on the optical recording medium.