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JPS5461503A - Detection of focal point - Google Patents

Detection of focal point

Info

Publication number
JPS5461503A
JPS5461503A JP12729777A JP12729777A JPS5461503A JP S5461503 A JPS5461503 A JP S5461503A JP 12729777 A JP12729777 A JP 12729777A JP 12729777 A JP12729777 A JP 12729777A JP S5461503 A JPS5461503 A JP S5461503A
Authority
JP
Japan
Prior art keywords
optical image
light flux
detecting
detection
focal point
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.)
Granted
Application number
JP12729777A
Other languages
Japanese (ja)
Other versions
JPS6019049B2 (en
Inventor
Kenichi Oikami
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 JP12729777A priority Critical patent/JPS6019049B2/en
Publication of JPS5461503A publication Critical patent/JPS5461503A/en
Publication of JPS6019049B2 publication Critical patent/JPS6019049B2/en
Expired legal-status Critical Current

Links

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
    • G11B7/09—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

Landscapes

  • Optical Recording Or Reproduction (AREA)
  • Automatic Focus Adjustment (AREA)

Abstract

PURPOSE:To prevent the signal reading performance from being dedteriorated, even if the signal reading light flux is used as a focus adjusting light flux, by irradiating an objecft to be focused with a light flux so that the convergence may be effected, while imparting astigmatism to the reflected light flux, when it is intended to accomplish the detection of the focal point with the use of the reflected light flux. CONSTITUTION:The detection of a focal is accomplished by detecting the size of an optical image at a detecting plane. There ae arranged at this detecting plane a light receiving element which has two concentric areas 30 and 31. When a disc surface 32 is positioned at a focal point, the optical image of the detecting plane is that shown in brokenline a. Then, as the disc surface 32 leaves an optical system 33, the optical image at the detecting plane becomes that shown in broken line b. On the contary, when the disc surface 32 approaches the optical system 33, the optical image becomes that shown in broken line c. As a result, it is possible to know the size of the optical image by detecting the difference between the guantity of light incident upon the area 31 and that incident upon the area 30.
JP12729777A 1977-10-25 1977-10-25 Focus detection method Expired JPS6019049B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP12729777A JPS6019049B2 (en) 1977-10-25 1977-10-25 Focus detection method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP12729777A JPS6019049B2 (en) 1977-10-25 1977-10-25 Focus detection method

Related Child Applications (1)

Application Number Title Priority Date Filing Date
JP7550486A Division JPS61239435A (en) 1986-04-03 1986-04-03 Focus detecting method

Publications (2)

Publication Number Publication Date
JPS5461503A true JPS5461503A (en) 1979-05-17
JPS6019049B2 JPS6019049B2 (en) 1985-05-14

Family

ID=14956469

Family Applications (1)

Application Number Title Priority Date Filing Date
JP12729777A Expired JPS6019049B2 (en) 1977-10-25 1977-10-25 Focus detection method

Country Status (1)

Country Link
JP (1) JPS6019049B2 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59152534A (en) * 1983-02-18 1984-08-31 Mitsubishi Electric Corp Focus detector
JPS61500337A (en) * 1983-11-04 1986-02-27 マツクス−プランク−ゲゼルシヤフト、ツ−ル、フエルデルング、デル、ヴイツセンシヤフテン、アインゲトラ−ゲナ−、フエライン Method and apparatus for detecting focusing state of imaging optical device
JPS6192445A (en) * 1985-10-04 1986-05-10 Matsushita Electric Ind Co Ltd Photodetector for optical disc device

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59152534A (en) * 1983-02-18 1984-08-31 Mitsubishi Electric Corp Focus detector
JPS61500337A (en) * 1983-11-04 1986-02-27 マツクス−プランク−ゲゼルシヤフト、ツ−ル、フエルデルング、デル、ヴイツセンシヤフテン、アインゲトラ−ゲナ−、フエライン Method and apparatus for detecting focusing state of imaging optical device
JPS6192445A (en) * 1985-10-04 1986-05-10 Matsushita Electric Ind Co Ltd Photodetector for optical disc device

Also Published As

Publication number Publication date
JPS6019049B2 (en) 1985-05-14

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