JPS5738403A - Focal point detector - Google Patents

Focal point detector

Info

Publication number
JPS5738403A
JPS5738403A JP11445380A JP11445380A JPS5738403A JP S5738403 A JPS5738403 A JP S5738403A JP 11445380 A JP11445380 A JP 11445380A JP 11445380 A JP11445380 A JP 11445380A JP S5738403 A JPS5738403 A JP S5738403A
Authority
JP
Japan
Prior art keywords
block
photodetector
disk
inexpensive
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
JP11445380A
Other languages
Japanese (ja)
Other versions
JPS639306B2 (en
Inventor
Toru Musha
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 JP11445380A priority Critical patent/JPS5738403A/en
Publication of JPS5738403A publication Critical patent/JPS5738403A/en
Publication of JPS639306B2 publication Critical patent/JPS639306B2/ja
Granted 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
    • 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

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Head (AREA)
  • Automatic Focus Adjustment (AREA)
  • Optical Recording Or Reproduction (AREA)

Abstract

PURPOSE:To obtain an inexpensive focal point detector having high sensitivity and a facilitated production, by forming both a beam splitter that leads the reflected light of the beams focused on a subject to be irradiated to a photodetector and a detecting prism into a body. CONSTITUTION:The beams (linearly polarized within the paper surface) emitted from a laser beam source 1 are focused on a disk 6 including an information track via a collimator lens 2, a block 14, a beam splitting surface 3a, a block 13, a 1/4 wavelength plate 4 and an objective lens 5 respectively. The reflected light is made incident to the block 13 via the plate 4 and reflected on the surface 3a and a reflecting surface 15 to be received at a photodetector 12. The surface 15 is set equal to or little smaller than the critical angle to the incident light in a focusing state. Thus the volume of incident light varies to light receiving regions 12A and 12B if the disk 6 has a displacement toward the direction (a) or (b) and becomes out of focus. In such way, an inexpensive focus detector can be obtained with high sensitivity and a facilitated production.
JP11445380A 1980-08-19 1980-08-19 Focal point detector Granted JPS5738403A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP11445380A JPS5738403A (en) 1980-08-19 1980-08-19 Focal point detector

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP11445380A JPS5738403A (en) 1980-08-19 1980-08-19 Focal point detector

Publications (2)

Publication Number Publication Date
JPS5738403A true JPS5738403A (en) 1982-03-03
JPS639306B2 JPS639306B2 (en) 1988-02-26

Family

ID=14638104

Family Applications (1)

Application Number Title Priority Date Filing Date
JP11445380A Granted JPS5738403A (en) 1980-08-19 1980-08-19 Focal point detector

Country Status (1)

Country Link
JP (1) JPS5738403A (en)

Also Published As

Publication number Publication date
JPS639306B2 (en) 1988-02-26

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