JPS5738406A - Method and device for detection of focal point - Google Patents

Method and device for detection of focal point

Info

Publication number
JPS5738406A
JPS5738406A JP11446680A JP11446680A JPS5738406A JP S5738406 A JPS5738406 A JP S5738406A JP 11446680 A JP11446680 A JP 11446680A JP 11446680 A JP11446680 A JP 11446680A JP S5738406 A JPS5738406 A JP S5738406A
Authority
JP
Japan
Prior art keywords
prism
focal point
incident
reflected light
reflected
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.)
Pending
Application number
JP11446680A
Other languages
Japanese (ja)
Inventor
Hisatsune Tsuda
Asao Hayashi
Kenichi Oikami
Masatoshi Ida
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.)
Olympus Corp
Original Assignee
Olympus Optical Co Ltd
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 Olympus Optical Co Ltd filed Critical Olympus Optical Co Ltd
Priority to JP11446680A priority Critical patent/JPS5738406A/en
Publication of JPS5738406A publication Critical patent/JPS5738406A/en
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/28—Systems for automatic generation of focusing signals
    • G02B7/30—Systems for automatic generation of focusing signals using parallactic triangle with a base line
    • G02B7/32—Systems for automatic generation of focusing signals using parallactic triangle with a base line using active means, e.g. light emitter
    • 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
    • G11B7/0908—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 for focusing only

Abstract

PURPOSE:To obtain an accurate focal point error signal, by making the reflected light of the beams condensed on a subject to be irradiated incident to an optical member having a reflective surface which is set almost at the critical angle to a beam in the reflected light flux and then detecting the change of light volume of the reflected light or the transmitted light. CONSTITUTION:The P polarized beams emitted from a laser beam source 21 are condensed on a disk 26 via a collimator lens 22, a polarizing prism 23, a 1/4 wavelength plate 24 and an objective lens 25 respectively. The reflected light goes backward and is reflected by the prism 23 to be made incident to a detecting prism 27. A part of the incident beam is reflected on a reflective surface 27a which is set almost at the critical angle to the incident beam to be made incident to a photodetector 28. At the same time, the residual beams transmit through the prism 27 and are made incident to a photodetector 30. The output of the detector 30 applies an information signal via an amplifier 31; while the output of the detector 28 is compared with the set value through a focal point error detecting circuit 31 to deliver an accurate focal point error signal.
JP11446680A 1980-08-19 1980-08-19 Method and device for detection of focal point Pending JPS5738406A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP11446680A JPS5738406A (en) 1980-08-19 1980-08-19 Method and device for detection of focal point

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP11446680A JPS5738406A (en) 1980-08-19 1980-08-19 Method and device for detection of focal point

Publications (1)

Publication Number Publication Date
JPS5738406A true JPS5738406A (en) 1982-03-03

Family

ID=14638433

Family Applications (1)

Application Number Title Priority Date Filing Date
JP11446680A Pending JPS5738406A (en) 1980-08-19 1980-08-19 Method and device for detection of focal point

Country Status (1)

Country Link
JP (1) JPS5738406A (en)

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