Abstract: In an optical pickup projecting a laser beam from a laser diode onto a disk through a half mirror, a collimator lens and an objective lens and receiving the laser beam reflected by the disk in a photodiode through the half mirror thereby reading information recorded in the disk, a portion of a metal board body having a pattern of a printed board corresponding to a connector pin fed with a high-frequency signal is notched to cause no electrostatic capacitance between the metal board body and the printed board thereby preventing a read signal from the photodiode from a jitter. Thus obtained is a high-performance and low-priced optical pickup causing no reading error.

Abstract: An optical pickup with two lasers for CD and DVD uses a grating to diffract one beam to the detector used by the other beam. This requires only one beam to be diffracted, allowing the diffraction pattern to be varied to compensate for different spacings between the lasers. A single, 4-quadrant detector is used to detect the returned beams from both lasers. The returned beam of the first laser passes through the grating element undiffracted, by passing through a portion without a grating pattern. The position of the detector is aligned with respect to this first beam. The grating diffracts the returned beam from the second laser to the same detector. The separation of the grating from the detector can be adjusted so that the returned beam from the second laser is also perfectly aligned with the detector.

Abstract: An optical pickup that is equipped with a photodetector unit, irradiates an optical disc with a laser beam, and receives returning light reflected by the optical disc, where the optical pickup is constructed to (1) divide the laser beam into a main beam, a preceding sub-beam, and a succeeding sub-beam, (2) direct the main beam, the preceding sub-beam, and the succeeding sub-beam toward the optical disc, and (3) divide returning lights of the main beam, the preceding sub-beam, and the succeeding sub-beam respectively into first-fourth main returning lights, first-fourth preceding returning lights, and first-fourth succeeding returning lights, and the photodetector unit includes: first-fourth main photodetectors that respectively receive the first-fourth main returning lights; first-fourth preceding photodetectors that respectively receive the first-fourth preceding returning lights; and first-fourth succeeding photodetectors that respectively receive the first-fourth succeeding returning lights.

Abstract: A volume radiation memory, nominally a 2.5 cm (1″) diameter 6 mm thick optical disk, is preferably written in parallel by two-photon absorption within, and read with massive parallelism by a single-beam-induced fluorescence of, spherical voxels of nominal diameter 2 microns spaced 2 microns center-to-center and arrayed 32×128 in planar segments that are tilted typically 40° to the planar surfaces of the disk, and that are typically located within a 5 mm thick central volume of the disk. Imaging of the voxels within the tilted planar segment for reading is through a two-lens doubly-telecentric afocal lens imaging system to a detector, normally an array of active pixel sensors or charge-coupled devices, located in the conjugate plane. Voxel illumination for reading may be orthogonal from the side of the disk, confocal-theta from a side of the disk, or co-linear through the doubly-telecentric afocal lens. Volumetric storage capacity is typically 5.89 gigabits (5.

Abstract: In an optical pickup device with a defocus adjustor used for adjusting a position of a photo-sensor against an optical system, the photo-sensor is mounted on a flexible printed circuit board, and the flexible printed circuit board is fixed on a plate spring. A first end of the plate spring with the flexible printed circuit board is fixed on a fixing face of a holder. Since the fixing face of the holder is inclined and the plate spring is formed flat with no bending portion, the plate spring is warped for generating a stress when the second end of the plate spring is fixed on the holder by an adjusting screw. The position of a photo-sensing face of the photo-sensor can be fine adjusted by tightening or loosening the adjusting screw.

Abstract: In an optical disc recording medium having formed thereon a first pit train and a second pit train, these pit trains are formed to be different in pit depth from each other and meet following two relations: 1 Y ≥   ⁢ 0.5 ⁢ M + 73.0411 - 1098.4938 ⁢   ⁢ ( X - 0.5 ⁢ K ) +   ⁢ 6584.719 ⁢   ⁢ ( X - 0.5 ⁢ K ) 2 - 19632.4312 ⁢   ⁢ ( X - 0.5 ⁢ K ) 3 +   ⁢ 29119.8871 ⁢ ( X - 0.5 ⁢ K ) 4 - 17190.8276 ⁢   ⁢ ( X - 0.5 ⁢ K ) 5 Y ≤   ⁢ 0.5 ⁢ M - 27.1270 + 307.9548 ⁢   ⁢ ( X - 0.5 ⁢ K ) -   ⁢ 1283.3732 ⁢   ⁢ ( X - 0.5 ⁢ K ) 2 + 2358.2052 ⁢   ⁢ ( X - 0.5 ⁢ K ) 3   ⁢ - 1620.1442 ⁢   ⁢ ( X - 0.

Abstract: Servo circuitry for correlating signals using a correlation data structure is disclosed. The servo circuitry is comprised of a setup system coupled to a correlation system that contains the correlation data structure. The setup system receives four signals and converts the signals to digital values. The correlation system takes the digital values and enters them into the correlation data structure. The correlation data structure yields a correlation value based on the digital values. The servo circuitry advantageously yields the correlation value that is a function of all four signals using the correlation data structure.

Abstract: An optical pickup device includes a semiconductor laser for emitting forward and backward laser light from front and back emergent end faces thereof, focusing device for focusing the forward laser light emergent from the front emergent end face of said semiconductor laser onto an optical recording medium, a light-receiving element for signal reproduction for detecting return light from the optical recording medium, and a light-guiding system for guiding the return light to said light-receiving element for signal reproduction, said optical pickup device being provided with a light source unit having an arrangement in which said semiconductor laser and said light-receiving element for signal reproduction being incorporated in a common package and shielding device, disposed inside said package of said light source unit, for preventing the light emitted from said semiconductor laser from being incident upon said light-receiving element for signal reproduction.

Abstract: A time-based optical servo system includes at least one optical indicator mark located on at least one servo track of a data storage medium. Alternatively, a pattern of optical indicators is repeatedly recorded in the at least one servo track. A servo read head assembly coupled to a transducing head assembly includes two elongate and non-parallel detection devices having a known relative geometry. The detection devices are adapted to detect the optical indicator marks and determine the time period required for each optical indicator mark to pass between the detection devices. This time period is used to calculate the location of the transducing head assembly relative to the storage medium in a translating direction and produce a position error signal (PES) based thereon.

Abstract: An optical pickup has a semiconductor laser having two laser sources of different wavelengths disposed in the same package, one diffraction grating and one optical detector. A plurality of light reception areas each having four divisional light reception planes of a -character shape are disposed at positions where light beams reflected from an optical disc are applied. A focus error signal is generated by an astigmatism method by using independently these light reception areas and a tracking error signal is generated by a differential phase detection method by using one or both the light reception areas.

Abstract: A compound optical unit includes a housing mounted to an optical pickup. A semiconductor laser, a light receiving member, and a composite optical member are integrally fixed to the housing. The semiconductor laser has a laser diode that emits a laser beam for a DVD. The composite optical member is provided with an incidence surface that admits light emitted from the semiconductor laser, an emission surface emits the light, a diffraction grating provided on the emission surface diffracts light reflected by an optical disk D, a reflecting surface that reflects light diffracted by the diffraction grating, and another emission surface that emits light reflected by the reflecting surface toward the light receiving member.

Abstract: An optical pickup is provided which is constructed from a single optical integrated device adapted to write data to, and/or read data from, more than one type of optical disc such as CD, DVD and the like. The optical integrated device includes means for selectively providing as output a result of the light detection by one of a plurality of light detecting elements. This selective output means makes it unnecessary to provide added terminals at the optical integrated device. There is also provided an optical disc drive using the optical pickup.

Abstract: An optical pickup has a semiconductor laser having two laser sources of different wavelengths disposed in the same package, one diffraction grating and one optical detector. A plurality of light reception areas each having four divisional light reception planes of a -character shape are disposed at positions where light beams reflected from an optical disc are applied. A focus error signal is generated by an astigmatism method by using independently these light reception areas and a tracking error signal is generated by a differential phase detection method by using one or both the light reception areas.

Abstract: In an optical scanning device for scanning an optical record carrier (20) and comprising a radiation source (2), a beam splitter (8) arranged to pass a first portion (b3) of the source beam (b1) to the record carrier and a second portion (b5) to an intensity sensor (10), and a signal detector (24) in the path of the beam reflected by the record carrier, false radiation (b6) reflected by the signal detector can be prevented from reaching the intensity sensor by tilting the signal detector. A polarization filter (40) may be arranged in front of the intensity sensor to prevent false radiation reflected by the radiation source and by the signal detector from reaching the intensity sensor.

Abstract: The medium of a disk for CD-R is a pigmentation material so readout by a 650-nm laser diode (LD) is not possible. Since CD-R is becoming popular in the marketplace, there are demands for a DVD readout device that is capable of reading CD-R format disks. An integrated semiconductor laser element is created by forming a two-wavelength LD monolithically on a GaAs substrate, and that laser element emits a laser beam that is reflected by a 45° mirror incorporated in a flat package.

Abstract: An optical pickup device having a lead frame package and a detecting unit is provided. The lead frame package includes a sub-mount, a light source mounted on the sub-mount and emitting a beam, a reflecting element disposed to direct the beam toward an optical medium, a transmission-type diffraction gating element dividing the beam into three beams, and a hologram optical element diffracting the beams reflected from the optical medium, the lead frame package having an opening defined by the hologram optical element, the bottom of the lead frame package, and side walls of the lead frame package. The detecting unit having a substrate and a photo diode mounted on the substrate is disposed within the opening of the lead frame package. After the detecting unit is adjusted with respect to the lead frame package to a position to accurately receive the reflected beams from the hologram optical element, the detecting unit is fixed to the lead frame package.

Abstract: Surface-enhanced Raman optical data storage (SERODS) systems having increased reading and writing speeds, that is, increased data transfer rates, are disclosed. In the various SERODS read and write systems, the surface-enhanced Raman scattering (SERS) data is written and read using a two-dimensional process called parallel signal transfer (PST). The various embodiments utilize laser light beam excitation of the SERODS medium, optical filtering, beam imaging, and two-dimensional light detection. Two- and three-dimensional SERODS media are utilized. The SERODS write systems employ either a different laser or a different level of laser power.

Abstract: An optical pick-up capable of reproducing information excellently on both CD and DVD, which are significantly different in terms of three kinds of factors, a base material thickness, a wavelength of a light source, and NA, and detecting TE signals by three kinds of methods, that is, the phase difference method, the PP method, and the 3-beam method, which are necessary to record and reproduce information. The optical pick-up is formed by integrating laser light sources having two kinds of wavelengths (&lgr;1, &lgr;2) for detecting TE signals; photodetectors, and hologram for generating the diffracted light for detecting signals.

Abstract: An optical disc is manufactured under a uniform condition by forming grooves and lands on the entire surface of the disc. The optical disc is configured to obtain a reliable reproduction signal, and the grooves and lands are formed on a lead-in area, a user data area and a lead-out area of the optical disc. Since the same manufacturing condition can be adopted in mastering discs, the yield can be enhanced and the manufacturing cost can be reduced.

Abstract: An optical head is composed of a light source means (1) for generating a luminous flux (A), a polarization beam splitter (2), an object lens (11) opposed to an appropriate recording medium (12), and a power monitoring means (6) for monitoring the power of the luminous flux (A) output from the light source means (1). The power monitoring means (6) is adapted to utilize a luminous flux (B) other than a luminous flux (C) of the luminous flux (A) (the whole amount of light) in order to monitor the power of the luminous flux (A) output from the light source means (1). The luminous flux (C) is substantially used for reproducing predetermined information from the recording medium (12) or recording the predetermined information onto the recording medium (12).

Abstract: An optical pickup device includes a semiconductor laser for emitting forward and backward laser light from front and back emergent end faces thereof, focusing device for focusing the forward laser light emergent from the front emergent end face of said semiconductor laser onto an optical recording medium, a light-receiving element for signal reproduction for detecting return light from the optical recording medium, and a light-guiding system for guiding the return light to said light-receiving element for signal reproduction, said optical pickup device being provided with a light source unit having an arrangement in which said semiconductor laser and said light-receiving element for signal reproduction being incorporated in a common package and shielding device, disposed inside said package of said light source unit, for preventing the light emitted from said semiconductor laser from being incident upon said light-receiving element for signal reproduction.

Abstract: An optical pickup apparatus which supports two wavelengths and is amenable to a reduction in size without employing a combining prism. The optical pickup apparatus employs a semiconductor laser device implemented in the form of a one-chip laser diode having two light sources for emitting a first laser beam and a second laser beam at a wavelength different from that of the first laser beam. A photodetector unit has a first detector section for receiving the first laser beam and a second detector section for receiving the second laser beam, and is set at positions at which the first and second laser beams follow return light paths of different lengths from an optical disc to the first and second detector sections.

Abstract: There is disclosed a substrate unit comprising a light emitting element attachment surface for attaching a light emitting element which emits laser light substantially in parallel to the attachment surface, a light reflecting surface for changing the direction of the light axis of the laser light emitted from the light emitting element by a predetermined angle by reflection, and a light detecting element attachment surface, formed on the same two-dimensional plane as a plane of the light emitting element attachment surface, for attaching a light detecting element which receives light incident from the outside.

Abstract: The focus light spot of the returned light is divided in halves so as the returned light from the points on the line perpendicular to the recording track at the center of the reading focus light spot is divided in halves;

Abstract: An optical head includes a (1) light radiating unit in which the relative positions of first and second light sources are set so that a straight line interconnecting a spot position of the laser light illuminated on an optical disc and a spot position of the second laser light similarly illuminated on the optical disc will be 45±15° with respect to a recording track on the optical disc and (2) a light receiving element having plural light receiving sections arranged substantially parallel to a splitting line substantially parallel to the straight line which interconnects the spot position of the laser light illuminated on an optical disc and the spot position of the second laser light similarly illuminated on the optical disc and which is projected on the optical disc.

Abstract: A method of controlling a balance of a photodetector capable of increasing light reception efficiency thereof in a compatible optical pickup and an apparatus thereof. The method includes installing first and second light sources in a single module; directing light supplied from the first or second light source and transmitted through a holographic optical element, an optical path changing unit, and an objective lens onto a disk corresponding to each light source, transmitting the light reflected from the disk through the objective lens, and the optical path changing unit to a photodetector, moving the photodetector so that the center of a first one of first and second spots received by the photodetector is concentric with the center of the photodetector; and moving the holographic optical element so that the center of the second received spot from the second light source is concentric with the center of the photodetector.

Abstract: An optical pickup device includes a semiconductor laser for emitting forward and backward laser light from front and back emergent end faces thereof, focusing device for focusing the forward laser light emergent from the front emergent end face of said semiconductor laser onto an optical recording medium, a light-receiving element for signal reproduction for detecting return light from the optical recording medium, and a light-guiding system for guiding the return light to said light-receiving element for signal reproduction, said optical pickup device being provided with a light source unit having an arrangement in which said semiconductor laser and said light-receiving element for signal reproduction being incorporated in a common package and shielding device, disposed inside said package of said light source unit, for preventing the light emitted from said semiconductor laser from being incident upon said light-receiving element for signal reproduction.

Abstract: Apparatus for simultaneously recording and reading information on a medium moveable in forward and reverse directions includes a first record laser and means for establishing a first beam path for recording information on the moveable medium and a second read laser and at least a first and second read-out detector respectively associated with the forward and reversed directions of the recording medium and means for establishing two beam paths which direct the laser light to positions forward and rearward from where the first laser beam illuminates the medium and such read laser beams are reflected respectively to the first and second detectors. The apparatus further includes means to select either the first or the second read-out detectors and to process information read by such selected detector so that as the medium is moving in the forward direction, the data are read from the first detector and when the medium is moving in the reverse direction. the data are read from the second detector.

Abstract: The present invention relates to a device for reading from or writing to optical recording media, which device has a scanning beam generation means, a focusing means and a photodetector comprising at least two detector zones and serving to receive zeroth- and first-order diffraction beams from the recording medium.

Abstract: A transmission diffraction grating body including a base material being substantially transparent with respect to wavelength &lgr;1 and having a refractive index n0; another base material being substantially transparent with respect to wavelength &lgr;1 and having a refractive index n1, which is formed on the base material having a refractive index n0; and a relief diffraction grating formed on the base material having a refractive index n1; wherein the refractive indexes n1 and n0 satisfy the relationship: n1>n0. Thus, the base material having a refractive index n1 can be formed of a high refractive index material, and when the depth of grating of the diffraction grating is set so that the diffraction grating diffracts the light with wavelength &lgr;1 and does not diffract the light with wavelength &lgr;2, the depth of grating of the diffraction grating can be made to be shallow, thus preventing the loss of the amount of the light with wavelength &lgr;1.

Abstract: An optical apparatus can eliminate offset resulting from assembling errors and also can correct offset even in the photodetector of any optical system. An optical disk apparatus for reading information from tracks traces the track with the condensed spot of light beam depending on the tracking error signal obtained from the optical system for tracking error detection. The tracking error detecting optical system includes an optical apparatus having a photodetector for outputting, as the tracking error signal, a differential value of outputs of a plurality of light receiving sections for receiving the light beam condensed by the condenser lens. Also, an optical element is provided for relatively increasing and/or decreasing the amount of receiving light of a light receiving section depending on displacement of the optical axis of the light beam, in order to balance the light received by the light receiving sections and compensate for affect.

Abstract: An optical head includes a light radiating unit in which the relative positions of first and second light sources is set so that a straight line interconnecting a spot position of the laser light illuminated on an optical disc and a spot position of the second laser light similarly illuminated on the optical disc will be substantially perpendicular to a recording track on the optical disc, and a light receiving element having plural light receiving portions which are obtained on splitting by a splitting line substantially parallel to the straight line interconnecting the spot position of the laser light illuminated on an optical disc and the spot position of the second laser light similarly illuminated on the optical disc and which is projected on the optical disc.

Abstract: In a method, a light emitting portion of a light spot forming device is formed. The light emitting portion has a minute opening, and a light collecting portion for collecting the light coming from a light source for light spot formation to the minute opening. A light emitting portion base film and a resist film are successively formed on the light collecting portion. A light intercepting mask and a light amount detecting device are arranged. The position of the light intercepting mask is adjusted such that the light from the light source is collected by the light collecting portion onto the base film, and is received by the light amount detecting device, and the amount of light detected by the device takes on the maximum value. The resist film is exposed with the light from a light source for exposure through the through-hole in the mask to form a through-hole for etching.

Abstract: The present invention provides for a optical head device having a beam-guiding optical device to bring beams of different wavelengths which are emitted by separate light sources together onto the same optical axis or to guide the beams onto a common photo receiving device. The beam-guiding optical device includes an incident plane and an exit plane and the incident plane and the exit plane are back to back. One of the incident plane and the exit plane has a stair-like surface wherein a step height between neighboring treads in the stair-like surface is set to cause a phase difference of n wavelength to one of the beams passing through the neighboring treads and n is equal to 1, 2, 3 . . . .

Abstract: Light from a light source is applied to a diffraction grating via a collimator lens. The light diffracted by the diffraction grating is applied to a polarization beam splitter. The light polarized by the polarization beam splitter at a given polarizing plane is transmitted and is applied to a recording surface of an optical disc via a ¼-wave plate and an objective lens. The light reflected from the recording surface of the optical disc is applied to the polarization beam splitter via the objective lens and the ¼-wave plate and is reflected by the polarization beam splitter toward a focusing lens. The light incident to the focusing lens is thereby condensed and is applied to a holographic element which diffracts the light and disposes the focal points of the ±1 diffraction orders to be offset from each other along the optical axis of the zeroth diffraction order with the focal point of the zeroth diffraction order being between the focal points of the ±1 diffraction orders.

Abstract: An optical head apparatus capable of stably obtaining a detection signal of spherical aberration even with a high density optical disk. A spherical aberration error signal is obtained by: dividing the returning light from the optical disk into a transmitted light and a diffracted light; reproducing information with the transmitted light having a larger amount of light while dividing the diffracted light having a small amount of light into two regions, i.e., region near the optical axis and a region distant from the optical axis; determining amounts of focus deviation in respective regions as focus error signals; and taking the difference signal therebetween. Thus, it is possible to detect the amount of spherical aberration with the SN ratio of the information reproducing signal kept at high level.

Abstract: In an optical pickup used in a DVD player, a photo detector has a predetermined photo sensing area pattern for detecting a returning laser beam from an optical disc. The returning laser beam is originated from a first laser beam or a second laser beam. The first and the second laser beams are alternatively emitted from a two wavelength laser having first and second right sources. Either the first laser beam or the second laser beam travels to the optical disc through a grating, a polarizing beam splitter, a collimating lens, a rising mirror, and an object lens and is reflected by the optical disc. The reflected laser beam reflected from the optical disc travels to the photo detector as the returning laser beam through the object lens, the rising lens, the collimating lens, and the polarizing lens. The predetermined photo sensing area pattern enables the photo detector to detect the returning laser beam regardless of the origin of the returning laser beam.

Abstract: The present invention relates to a device for reading from and/or writing to optical recording media having a scanning unit, which is equipped with at least two detector units each having a plurality of detector elements, and also an evaluation unit, each of the detector elements being connected to the evaluation unit by means of a line.

Abstract: There is disclosed a compact optical information storage apparatus in which noise attributed to wobbling or the like is reduced and high-density recording is possible. An optical device 410 comprises a reflective surface 64 including a main portion for reflecting a signal light reflected by a separation surface 61 in a predetermined direction, and a mask portion 411 having an optical property different from the optical property of the main portion.

Abstract: An optical head for an optical disc drive is provided with a first laser diode that emits a shorter wavelength laser beam, a second laser diode that emits a longer wavelength laser beam, and an objective lens for converging the beams emitted by the laser diodes on the data recording surface of the optical disc. Each of first and second surfaces of the objective lens is rotationally symmetrical, and a rotational axis of the first surface and a rotational axis of the second surface are arranged to be deviated from each other.

Abstract: In a photodetector, the minimum size of the photodetection area for detecting a focus error signal from a light beam on the inner radius side of a hologram is made smaller than the minimum diameter of diffracted light beam spots (30, 31) for recording and reproduction, and when a CD is reproduced, a light beam close to the optical axis is made to significantly contribute to the focus error signal and the minimum size of the photodetection area for detecting the focus error signal from a light beam from the peripheral side of the hologram is made larger than the minimum diameter of diffracted light beam spots (130, 131) for recording and reproduction, whereby the focus error signal is made equal to the normal focus error signal when a DVD is reproduced, so that the focus offset variation caused when the base material thickness varies can be reduced.

Abstract: In an optical pickup apparatus, a light source, a photo device and optical elements, constructing an optical system for converging a light emitted by the light source on an optical recording medium and guiding a returning light reflected by the optical recording medium to the photo device, are mounted on a frame which is composed of a wiring board having wiring patterns, including circuits of electric supply to the light source and the photo device.

Abstract: An optical pickup apparatus includes a light source having a plurality of integrated light emitting portions for emitting laser beams of different wavelengths, the light source being adapted to selectively emit one of the laser beams of different wavelengths; a photodetector for detecting the laser beam; and an optical system for directing the laser beam emitted from the light source to the disc, and for directing the laser beam reflected by the disc to the photodetector. The light source is positioned such that a straight line connecting respective light emitting points of the plurality of light emitting portions is coincident with a tangential line of a track on a disc to be reproduced.

Abstract: In optical heads with multiple semiconductor laser chips with different wavelengths, coma aberrations generated by laser beams projected at an angle relative to the entry axis of a focus lens is reduced.

Abstract: An optical disk device has

Abstract: A laser diode chip for an optical pickup apparatus, in which a plurality of laminated light emitting portions which emit laser beams having different wavelengths are formed on a substrate, and light emitting points of the plurality of light emitting portions are placed at positions separated by different lengths from each other in the laminate direction from the same plane of the substrate.

Abstract: Disclosed is a head of an optical data recording and/or reproducing device. The head is provided with a laser source, an objective optical system, a deflector for deflecting the laser beam emitted by the laser source towards the objective optical system. A relay optical system provided between the deflector and the objective optical system. Further, a detector is provided between the deflector and the relay optical system. The detector has a first and a second light receiving portions and an opening. The two light receiving portions are arranged in a first direction in which the laser beam is deflected by the deflector. A part of the laser beam incident on the detector is received by the first and second light receiving portions, the other passes through the opening. An amount of rotation of the deflector is detected in accordance with amounts of light received by the two light receiving portions.

Abstract: An apparatus and method for reproducing information stored in a fluorescent multilayer information carrier. The apparatus utilizes auto-focusing and auto-framing techniques when reading the information to enable parallel reading from uniformly moving carrier. To avoid discontinuity in motion, an actuator with an objective lens performs periodic motion following a specific moving information page and, after the end of reading of this page, returns back to follow the next page.

Abstract: An optical recording medium of the present invention is arranged such that respective information recorded on lands and grooves are reproducible by either of a light beam of a first wavelength &lgr;1 and a light beam of a second wavelength &lgr;2 which is shorter than the first wavelength &lgr;1. The groove depth d of the optical recording medium is such that tracking error signals of not less than a predetermined level can be ensured for respective wavelengths &lgr;1 and &lgr;2 without generating distortion in waveform, irrespectively of differences in receiving light sensitivity of a photodetector provided in an optical pickup devices for use in recording and reproducing information on and from such optical recording medium.

Abstract: A minute optical head is provided so that a light source and one or more photo detector elements are integrated on the same substrate by a simple manufacturing process and may be applied to an apparatus for recording and reproducing recordable optical information. An apparatus for recording and reproducing optical information is arranged to have a minute optical head. A light waveguide layer composed of column semiconductor crystal is formed on a monocrystalline transparent substrate and an active layer is formed on the side of the light waveguide layer. The light beam source is a semiconductor having a vertical resonator formed of a high-reflection film before and after an emitting surface of the active layer so that a light beam is vertically radiated to the substrate. The photo detector element is integrated on the closer portion of the substrate to the light beam source of the semiconductor laser.