WO1987002499A1 - Appareil d'enregistrement et de lecture de reperes de donnees optiques sur un support optique - Google Patents

Appareil d'enregistrement et de lecture de reperes de donnees optiques sur un support optique Download PDF

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Publication number
WO1987002499A1
WO1987002499A1 PCT/US1986/002129 US8602129W WO8702499A1 WO 1987002499 A1 WO1987002499 A1 WO 1987002499A1 US 8602129 W US8602129 W US 8602129W WO 8702499 A1 WO8702499 A1 WO 8702499A1
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WIPO (PCT)
Prior art keywords
medium
light beam
scanning
recited
transfer device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1986/002129
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English (en)
Inventor
Dennis H. Rose
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
OPTICON TECHNOLOGY Inc
Original Assignee
OPTICON TECHNOLOGY Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by OPTICON TECHNOLOGY Inc filed Critical OPTICON TECHNOLOGY Inc
Publication of WO1987002499A1 publication Critical patent/WO1987002499A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/085—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam into, or out of, its operative position or across tracks, otherwise than during the transducing operation, e.g. for adjustment or preliminary positioning or track change or selection
    • G11B7/08547—Arrangements for positioning the light beam only without moving the head, e.g. using static electro-optical elements
    • G11B7/08564—Arrangements for positioning the light beam only without moving the head, e.g. using static electro-optical elements using galvanomirrors
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/002—Recording, reproducing or erasing systems characterised by the shape or form of the carrier
    • G11B7/003—Recording, reproducing or erasing systems characterised by the shape or form of the carrier with webs, filaments or wires, e.g. belts, spooled tapes or films of quasi-infinite extent
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector

Definitions

  • This invention relates to apparatus for reading and writing digital data from and onto an optical data storage medium, and more specifically, to such apparatus operable with optical storage film.
  • the invention includes a telecentric arrangement for the optical components utilized therein in order to eliminate movement of a reflected optical beam and thus to permit two dimensional scanning and increased efficiency of operation of the device.
  • Prior art devices for reading and recording optical data are well known. In such devices it is known to utilize relative movement between an optical beam and a recording medium in order to read optically encoded data written on a data track.
  • the prior art systems are further typically constrained to read the one dimensionally recorded data sequentially, in a serial fashion as recorded on a spiral track along the record medium. Accordingly there is a need in optical information transfer technology for a multidimensional information storage and readout capability.
  • Yet another object of the invention is the provision of a multidimensional scan for data recorded on an optical storage medium, and particularly provision of a two dimensional scan for such data. It is an additional object of the invention to provide an optical scanning arrangement in which a beam of light scans data in a direction perpendicular to the direction of relative movement between a record medium and the light source. It is a further object of the invention to provide apparatus for scanning an optical data storage medium in two dimensions and for providing a stationary tracking control system therefor.
  • Still another object of the invention is the provision of apparatus for scanning an optical data storage medium in two dimensions and of a stationary focusing control therefor.
  • an improved optical information device having a light source for producing a light beam and an optical arrangement for irradiating a- surface- of an optical data storage medium by the light, beam.
  • the improved structure includes a scanning device for: caursing the light beam to scan the surface ' of the medium, as well as a device for fixing the reflected beam to impinge on stationary optics used therewith.
  • the beam fixing device includes a telecentric arrangement between an objective lens of the system, the medium, and the scanning device for the beam which includes a reflector therefor.
  • the reflector may comprise a galvanometer causing displacement of the beam for scanning tracks perpendicularly to the direction of relative movement between the medium and the light source, the reflector being placed at a back focal point of the objective, thus providing two dimensional scanning ' of the stored optical data while maintaining the reflected beam substantially fixed.
  • the storage medium is a flexible film.
  • Rollers and vacuum devices are used to provide appropriate curvature to the film to conform the same to curvature of field introduced by the objective and by other- lenses in t .e optical system, thus compensating for the curvature of field.
  • a number of linearly disposed photo detecting elements in a linear array, to permit simultaneous reading of a number of data bits recorded along a single track perpendicularly to the direction of relative movement between the film and the beam.
  • the linear array is placed to permit simultaneous reading of corresponding data bits on a plurality of tracks recorded on the medium.
  • Yet another embodiment of the invention provides a two dimensional array of photo detectors for sim ltaneously reading data recorded along corresponding portions of a plurality of tracks along the record medium.
  • the improved apparatus is stabilized by a system utilizing a light beam reflected by the record medium to a substan ially fixed location relative to the stationary optics.
  • the fixed reflected beam permits the utilization of simplified, stationary, detectors for autof ocuss i ng and tracking control devices even with multidimensional beam scanning and movement of the incident beam.
  • a split photodetector arrangement is used for tracking control of the beam.
  • An autofocus control is used in which the light beam reflected from the record medium is passed through a beam splitter and focussed by a pair of lenses. The two resultant light beams are passed through apertures to a pair of photodetecting elements.
  • One aperture is preferably located in front of the focal point of the lens and the other aperture is located behind the focal point of the lens.
  • An acousto-optical scanner may be used to control tracking of the medium by the incident beam.
  • a motorized drive may be activated to displace a lens for proper positioning of the incident beam.
  • FIG. 1 illustrates a preferred embodiment of the invention
  • FIG. 2 illustrates in block diagram form the control circuitry for the preferred embodiment of Figure 1;
  • FIG. 3 shows an alternate embodiment of the invention
  • Figure 4 shows a tracking control system for the embodiment of Figure 3.
  • Figure 5 shows a focus control system for the alternate embodiment of Figure 3.
  • FIG. 1 there is shown a preferred embodiment of the invention for writing and reading information onto and from an optical data medium, preferably a flexible optical tape.
  • a laser diode 7 provides a light beam.
  • the output beam which may diverge, is collected and collimated by a collimating lens 8, which provides the laser beam to an anamorphic prism 9.
  • the output beam from lens 8 has an elliptical gaussian cross section, which is changed to a round elliptical cross section by the prism 9.
  • the beam provided by prism set 9 on the one hand is used both for tracking and focus control and, on the other hand, is used for writing of data on the optical tape.
  • the laser beam is also used for reading data.
  • the collimated beam is provided to a polarizing beam splitter 10 and an associated quarter wave plate 11.
  • Polarizing beam splitter 10 passes beams polarized in the P_ direction and reflects beams polarized in the S_ direction.
  • the invention may also be practiced by utilizing a beam splitter which passes the S polarized portion of the beam and reflects the P_ polarized portion, when all other polarization sensitive components are similarly modified.
  • Quarter wave plate 11 converts the linearly polarized beam into a righthand circularly polarized beam, which is provided to a focussing lens 12 for focussing onto an acousto-optical deflector 13.
  • Beam deflector 13 is preferably capable of scanning at least small angles at frequencies of up to 20 Khz, and is used to provide the desired tracking correction for the invention.
  • the circularly polarized beam expands and is passed through a dichroic beam splitter 14 and is collimated by a lens 15 which, together with focussing lens 12, functions as a telescope to expand the beam to a diameter of approximately 30 mm, which permits focussing of the beam to a 2 m spot on the optical tape.
  • the beam as expanded by lens 15, is incident on a scanning galvanometer 16 for scanning the optical tape either to read or to write data thereon.
  • the scan frequency of galvo 16 is 275 Hz.
  • the galvo 16 is telecentrically located with respect to an objective lens 17. That is, the galvanometer is located at the back focal length of objective lens 17 in order to provide telecentric scanning of the data on the optical film being scanned.
  • the fulcrum of rotation of the scanning beam lies at the objective back focal length so that the beam is perpendicular to the tape at all times.
  • this arrangement causes the beam to be retroref lected to the objective, along the original axis, and without displacement of the reflected beam as a function of scan angle.
  • the scanned light beam upon reflection by the optical tape and further reflection by galvanometer 16, the scanned light beam is congruent with the incident imaging beam output by acousto optical deflector 13 and lens 12.
  • the reflected beam is substantially stationary at lens 12, and is provided to tracking control and focus control optics thereat.
  • the scanned beam, reflected by galvanometer 16, is focussed on the optical medium, flexible tape 18 through an optical window 19, which may be provided in a tape cartridge.
  • the multidimensional scanning of the optical medium may thus be accomplished efficiently, utilizing essentially stationary tracking, focussing, and detecting optics.
  • the use of a flexible medium, and the curvature provided thereto provides compensation for 5 curvature of field introduced by the scanning optics.
  • the use of a flexible medium, and the curvature provided thereto provides compensation for curvature of field introduced by the scanning optics.
  • the scanning apparatus of the ⁇ invention is telecentrically arranged. Such telecentricity assures that the central focussed ray will be perpendicular to the optical tape at all positions of the scan, so that the beam is reflected back directly through the path through which it came. 5
  • the reflected beam is thus stationary after leaving galvo 16, permitting the tracking and focus servo- optics, which utilize the reflected beam, to remain stationary.
  • the optical tape medium which is used in the n present invention may preferably form data mark pits in response to the concentrated focussed laser beam.
  • the tape may be of a write-once only type of medium.
  • the output power of laser 7 is preferably controlled to assure that no inadvertent writing takes place during a reading operation or as a result of tracking or focussing control. Accordingly, laser power is preferably reduced during a reading operation.
  • the optical tape medium used in the present invention carries data arranged thereon as 5 frames formed of groups of tracks perpendicular to the direction of tape motion.
  • a reading operation an image of a portion of the tape, including a portion of aaframe or a plurality of frames, is imaged by a video camera 1.
  • a scanning beam similar to l ⁇ 'the beam focussed on the tape for tracking and focussing control purposed as hereinabove described, may be imaged on the tape as a reading beam.
  • the reading beam may scan the tape perpendicularly to the direction of motion thereof to scan the various tracks 15. in each data frame, in accordance with the embodiment of Figure 3.
  • control of the scanning beam is required in order to provide proper tracking and focussing.
  • control of the scanning beam is necessary in order to assure that the data is properly read.
  • the objective lens 17 is preferably provided with. a relatively large depth of focus, so that even if the optical tape to objective lens distance were to vary the spot size would remain fairly constant.
  • the present invention includes autofocus control optics and circuitry, so that the spot size is maintained constant' and in sharp focus on the tape 18.
  • the tape cartridge or other tape conveying mechanism used in conjunction with the invention includes tape curving means for providing curvature to the optical tape in conformity with the curvature of field introduced by objective lens 17, thus further assuring constancy of focus and accuracy of the optical system.
  • the tape may be shaped by rollers, by a capstan, or by vacuum hold-down devices in order to minimize the va ' riations in the focussed spot on the medium surface.
  • the tape may be differently mounted, without using a cartridge.
  • the reflected beam passing in a path congruent with the incident beam after reflection by scanning galvanometer 16, traverses lens 15 and is reflected by beam splitter 14 to the optical detecting system, which may consist of a single photodetec tor diode, a linear array of photodetectors which may be self scanned, a rectangular array, or a video imaging camera as shown in Figure 1.
  • the optical detecting system may consist of a single photodetec tor diode, a linear array of photodetectors which may be self scanned, a rectangular array, or a video imaging camera as shown in Figure 1.
  • the beam output by laser 7 may itself be used for reading the data, as well as to provide tracking and/or focus control, as described below. Additionally, it may be the same laser beam which is used to read the data and to provid optical control for a linear or rectangular array ⁇ f photodiodes.
  • the galvo mirror may be designed to be at least partially transmissive, so that the image of the data tracks may be projected therethrough onto a linear CCD photodetector array as illustrated in Figure 3, for example. Such an array provides a parallel readout of the data tracks on the tape.
  • the invention may be practiced by r e t r o r ef 1 ec t i on of the scanning beam to the photodetectors of the tracking or focus control optics to read the recorded data.
  • imaging may be efficiently obtained by utilization of a separate light source, such as shown at 29 in Figure 1.
  • the imaging light, incident on optical tape 18, is reflected thereby and focussed on scanning galvanometer 16.
  • the telecentric arrangement again permits the reflected viewing beam to be substantially stationary once reflected by galvanometer
  • the information bearing beam reflected by dichroic beam splitter 14 is essentially stationary and is provided to the imaging video apparatus.
  • the tracking optics receive the reflected laser beam and are responsive thereto. Tracking control is necessary to provide proper alignment between the imaging laser beam and the tape in a writing operation. Similarly, in a reading operation, where a single photodiode or a linear array of photodiodes is utilized, it is necessary to provide proper tracking between the reading laser beam and the data on the tape. Accordingly, the tape preferably includes preformed grooves, or other indicia, for detection by the tracking optics. Of course, where a self-scanned array is used, it may be possible to bypass a need for a tracking control. Nonetheless, for proper imaging of a complete frame or of a predetermined portion of a frame in a reading operation, or for proper location of a data track to be written, the embodiment of Figure 1 includes the tracking control optics.
  • the beam splitter 10 reflects the returning S- polarized beam to the tracking and focussing control optics.
  • a narrow band filter is provided at the reflecting output of polarizing beam splitter 10 / in order to block any stray light or unrelated reflection from the beam provided to the control optics.
  • an essentially pure data beam is provided to beam splitters 20 and 23 for the tracking and focussing optics, respectively.
  • Beam splitter 20 utilizes a portion of the reflected beam to control tracking by reflecting that portion to a focussing lens 21, which in turn focusses the portion of the beam on a split photodiode detector
  • the present invention permits 5., the use. of. stationary tracking and focussing optics notwithstanding the necessity for scanning the laser beam. pexpe_ndicularly to to the direction of motion of thestape
  • pregrooved data tracks are imaged on the split photodetector 22 which straddles the image thereof.
  • the servo mechanism outputs a control signal 46 to an acousto-optical 5 deflector driving mechanism 48 , as shown in Figure 2, thus causing a deflection of the scanning laser beam by the AO deflector 13 in order to provide proper positioning . of the beam for properly tracking the pregrooved data tracks on the optical tape 18.
  • Another portion of the reflected beam, passed by beam splitter 20, is provided to beam splitter 23 in the focus control optics.
  • Beam splitter 23 provides the other portion of the reflected beam to a pair of lenses 24 and 36.
  • the two lenses focus the respective components of the beam provided thereto at corresponding focal points.
  • a pair of apertures 25 and 27 are provided, one aperture (25, for example) located between one lens (e.g., 24) and the focal point thereof, the other aperture (e.g., 27) being located outside the focal point, that is, further removed from the lens than its focal point.
  • the light focussed by lenses 24 and 36, after passage through apertures 25 and 27, is detected by photodetectors 26 and 28, respectively.
  • the position of the focus created by the two lenses will similarly change, so that the two apertures block differing amounts of light.
  • the two apertures clearly block different amounts of light in a push-pull fashion. More particularly, as the focus moves away from the two lenses, more light J ' will be blocked by aperture 25 and less light will be blocked by aperture 27, and vice versa. Thus, as the focus moves toward lenses 24 and 36, less light will be blocked by aperture 25 and more light will be blocked by aperture 27 so that more light will impinge on photodetector 26 while less light will impinge on photodetector 28.
  • the difference voltage between outputs C and D of photodetectors 26 and 28 is proportional to the focussing error.
  • the outputs of photodetectors 26 and 28 are amplified by amplifiers 52 and 54, respectively, and are used to drive a focussing servo 56 as shown in Figure 2.
  • a focus motor 58 may be mounted either on the objective lens 17 or on the focussing lens 12, for example.
  • a separate focus control may not be necessary.
  • the light emitted by laser diode 7, upon reflection by the optical tape 18, is returned to the tracking and focus control optics to provide proper tracking of the preformed data tracks on the tape and to provide proper focussing of the scanning spot thereon.
  • the reflected illumination is provided through objective 17 to the galvo 16 for reflection through collimating lens 15 and for further reflection by the dichroic beam splitter 14, which reflects white light and passes 830 nm laser beams.
  • Video camera 1 thus receives and scans the detected image through a sequence of lenses 2, 4, 15 and 17 which magnify the reflected image by a factor of as much as 1000 times. Where necessary, the path of the reflected beam may be extended by use of further reflecting optics symbolized by a mirror identified by reference numeral 3 in Figure 1.
  • a pair of filters 5 and 6 may be provided to minimize laser power reflected to the video camera. More particularly, filters 5 and 6 may be a laser block and a neutral density filter, respectively.
  • FIG 2 there is shown a functional system block diagram for the preferred embodiment. Various elements of the system have previously been described. The remaining elements of the embodiment of Figure 2 include a monitor 60 for the data scanned by video camera 1. The detected data may be provided by the video camera to any utilization equipment, of which monitor 60 is only an illustration. Thus, for the embodiment of Figure 1 the data on tape 18 is detected by video camera 1 and may be decoded by computing or other devices receiving the detecjted data therefrom.
  • the preferred embodiment further provides for writing of optical data on the optical tape 18.
  • Data to be written on the tape is provided from a data buffer 62 to a driver 64 for the laser diode 7.
  • the data may be provided to the buffer 62 by a computer 66.
  • data may be keyboard entered to computer 66, or may be received from other devices.
  • the data is then provided to buffer 62 for controlling driver 64.
  • a fast pulse generator 68 may be used to trigger the laser diode driver 64.
  • a synchronization circuit 70 is included for synchronizing the data to be written onto the tape with the scanning galvo 16 as well as with a tape drive 72.
  • tape 18 may be provided in a cartridge so that tape drive 72 may include a cartridge drive.
  • Synchronizing circuit 70 thus provides synchronizing signals to a galvo driver 74, to a tape drive 72, and to the data buffer 62.
  • phase lock loops are utilized in the synchronizing circuits to attain the desired synchronization.
  • tracking servo 44 activates the acousto-optical deflector driving mechanism 48 in order properly to control the tracking acousto-optical deflector 13.
  • the writing beam is properly positioned on the optical tape 18 to record the data in accordance with a predetermined position of the preformed data tracks.
  • synchronizing marks may be provided on the optical tape.
  • the synchronizing marks such as sprocket holes or the like, may be detected by a different tracking optics system for controlling the tracking servo 44.
  • One difference between the embodiments of Figures 1 and 3 relates to the method for detecting and imaging the data, written on tape 18.
  • the light beam generated by laser 7 is used both for reading, writing and optics control of the system.
  • scanning galvo 16 is made partially transmissive so that the beam reflected by tape 18 is partially transmitted through galvo 16 to a photodetecting arrangement 80.
  • the photodetecting arrangement 80 may comprise a single photodiode, a linear CCD array, or a rectangular array.
  • the image of the data tracks may be projected through a further lens 82 onto the photodetecting structure. As previously mentioned herein, however, the reflected da .
  • the photodetecting arrangement shown at 80 is preferably a linear photodetecting array capable of providing simultaneous readout of multiple data channels, thus increasing the rate of data readout from the optical tape. Accordingly, the embodiment of Figure 3 is capable of writing one data mark at a time, while capable of reading a plurality of data marks simultaneously. In order to read simultaneously the plural data channels, however, a separate, non-scanned, illuminating source (not shown) may be provided. In either case, whether a single or plural photodetectors are utilized, the reflected beam provided by galvo 16 is stationary, and does not have lateral or angular shifts.
  • a further difference between the embodiments of Figures 1 and 3 relates to the tracking control mechanism.
  • the present embodiment incorporates a linear motor 84 built into lens 17, the linear motor responding to the outputs of split photodetector 22 and the tracking servo 44 to cause the lens to oscillate as necessary to maintain proper tracking.
  • the scanning beam is controlled by galvo 16 to scan in a right-left orientation in the plane of the drawing figure.
  • the linear motor 84 causes oscillation of lens 17 perpendicularly to the plane of the drawing, so that the scanning beam is controlled in movement perpendicular to the plane of the drawing, in order to track a pregrooved data track such as illustrated at 85, for example.
  • Figure 3 illustrates a single lens 86 in the focussing control optics.
  • the embodiment of Figure 3 first provides the beam to lens 86 for subsequent beam splitting by the beam splitter 23.
  • the beam is focussed by lens 86 and the portion of the beam reflected by beam splitter 23 passes through aperture 25, within the focus, while the portion transmitted by beam splitter 23 passes through aperture 27, located outside the focus of lens 86.
  • the outputs of amplifiers 41 and 42 for the output signals of photodetector 22 are subtracted from one another in a difference amplifier 90 to provide a tracking error signal proportional to the tracking offset.
  • driver amplifiers 92 and 94 are provided to driver amplifiers 92 and 94 for respectively driving the linear motor 84 for the objective lens 17 and the rotating motor 88 for the photodetector array 80.
  • the scanning optics for the scanning beam are maintained on track, and the array is maintained in alignment with the data tracks.
  • the control system utilized in focussing servo 56 is illustrated in greater detail. More particularly, as shown therein the output signals of amplifiers 52 and 54 are provided to a difference amplifier 96 for generating a focussing error output signal.
  • the focussing error output signal is provided to a focussing motor 97 associated with the collimating lens 8, or to a focussing motor 98 associated with the objective lens 17.
  • a focussing motor 97 associated with the collimating lens 8 or to a focussing motor 98 associated with the objective lens 17.
  • the linear motor 84 associated with lens 17 provides movement perpendicular to the plane of the drawing in Figure 3 while the focussing motor associated with the same lens assembly provides vertical movement in the drawing Figure 3.
  • a system for writing data on and reading data from an optical medium and preferably from a flexible optical medium such as optical tape (which may be photographic film, for example), the tape advantageously being curved to compensate for curvature of field by the optical system.
  • a telecentric system is used for control of the scanning beam to permit multidimensional displacement thereof along the tape without causing a corresponding displacement of the reflected beam.
  • accurate tracking control and focussing control is provided utilizing optical systems which are not required to move with the reflected beam.
  • the data may be read rfrom the tape by a video camera or by a photodetector arrangement comprising a single detector, or a l i near or a rec tangu lar a rray of de tectors.
  • the tape may be scanned perpendicularly to the direction of tape motion or parallel thereto and plural data may be read simultaneously or consecutively.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Recording Or Reproduction (AREA)
  • Optical Head (AREA)

Abstract

Le système de lecture et d'écriture de données ci-décrit pour une bande optique (18) corrige la courbure de distorsion du champ et permet un balayage multidimensionnel à bande (18) à l'aide d'une source à faisceau lumineux (7). Un agencement optique télécentral du galvanomètre de lecture de données (16) et de la lentille (17) permet d'obtenir comme résultat un faisceau réfléchi stationnaire, ce qui permet d'utiliser un système de commande de poursuite optique fixe (20-22) et un système de commande de focalisation automatique (23-28 et 36).
PCT/US1986/002129 1985-10-10 1986-10-09 Appareil d'enregistrement et de lecture de reperes de donnees optiques sur un support optique Ceased WO1987002499A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US78478185A 1985-10-10 1985-10-10
US784,781 1985-10-10

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WO1987002499A1 true WO1987002499A1 (fr) 1987-04-23

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US3530258A (en) * 1968-06-28 1970-09-22 Mca Technology Inc Video signal transducer having servo controlled flexible fiber optic track centering
US4198657A (en) * 1975-07-07 1980-04-15 Pioneer Electronic Corporation Optical disk reader with means for correcting errors due to eccentricity and time axis variations
US4199783A (en) * 1977-04-29 1980-04-22 Thomson-Csf Optical system for recording and reading an information on a tape
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US4528654A (en) * 1979-10-01 1985-07-09 Bogey B.V. Dustproof case for an optical information tape including a clamping lens
US4410969A (en) * 1979-12-19 1983-10-18 Hitachi, Ltd. Optical information playback apparatus
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US4422168A (en) * 1980-08-19 1983-12-20 Olympus Optical Co. Ltd. Method and apparatus for detecting a focussing condition of an objective lens
US4453239A (en) * 1980-08-19 1984-06-05 Olympus Optical Company, Ltd. Method and apparatus for controlling the focusing and tracking of a light beam using a main and secondary light beam in association with multiple detectors
US4567585A (en) * 1983-10-31 1986-01-28 Daniel Gelbart Optical tape recorder using linear scanning

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0424250A3 (en) * 1989-10-16 1992-01-15 Sony Corporation Servo control circuit for image rotator
US5155720A (en) * 1989-10-16 1992-10-13 Sony Corporation Servo control circuit for image rotator

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