JPS5977643A - Optical type pickup device - Google Patents

Optical type pickup device

Info

Publication number
JPS5977643A
JPS5977643A JP57188569A JP18856982A JPS5977643A JP S5977643 A JPS5977643 A JP S5977643A JP 57188569 A JP57188569 A JP 57188569A JP 18856982 A JP18856982 A JP 18856982A JP S5977643 A JPS5977643 A JP S5977643A
Authority
JP
Japan
Prior art keywords
light
laser
lambda
splitter
polarized
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
JP57188569A
Other languages
Japanese (ja)
Inventor
Saburo Takamiya
Toshio Sogo
Kuniyoshi Tamatoshi
Koji Yamashita
Original Assignee
Mitsubishi Electric Corp
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 Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Priority to JP57188569A priority Critical patent/JPS5977643A/en
Publication of JPS5977643A publication Critical patent/JPS5977643A/en
Pending legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00Recording 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
    • G11B7/12Heads, e.g. forming of the optical beam spot or modulation of the optical beam

Abstract

PURPOSE:To utilize a longitudinal single mode laser as a light source for optical disc reading of which noise is reduced by maintaining returning light to a semiconductor laser at 3% or more by the means for shifting the quantity of phase shifting of a 1/4 wavelength plate by lambda/4 and for reducing the light extinction ratio or the like. CONSTITUTION:The light from a semiconductor laser 1 is condensed on the surface of a disc 6 through a polarized beam splitter 3, a lambda/4 plate and a condenser lens 5 and the reflected light from the surface of the disc 6 is reflected by the polarized beam splitter 3 and made incident to a photodetector 8, which reads out the variation of reflected light power by the existence of a pit 11. Since the wavelength of the lambda/4 plate 4 is shifted within the range of >=+ or -2%- <=20% from 1/4 wavelength and the polarized beam splitter 3 with the bad quality of <=95%->=50% light extinction ratio is used to increase the returning light, the laser to be used originally as a longitudinal single mode laser can be acted as a stable longitudinal multi-mode laser with low noise.
JP57188569A 1982-10-25 1982-10-25 Optical type pickup device Pending JPS5977643A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP57188569A JPS5977643A (en) 1982-10-25 1982-10-25 Optical type pickup device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP57188569A JPS5977643A (en) 1982-10-25 1982-10-25 Optical type pickup device

Publications (1)

Publication Number Publication Date
JPS5977643A true JPS5977643A (en) 1984-05-04

Family

ID=16225978

Family Applications (1)

Application Number Title Priority Date Filing Date
JP57188569A Pending JPS5977643A (en) 1982-10-25 1982-10-25 Optical type pickup device

Country Status (1)

Country Link
JP (1) JPS5977643A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6293627A (en) * 1985-10-19 1987-04-30 Sanyo Electric Co Ltd Method for measuring return beam noise of semiconductor laser
JPH0210530A (en) * 1988-06-28 1990-01-16 Matsushita Electric Ind Co Ltd Optical head

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6293627A (en) * 1985-10-19 1987-04-30 Sanyo Electric Co Ltd Method for measuring return beam noise of semiconductor laser
JPH0210530A (en) * 1988-06-28 1990-01-16 Matsushita Electric Ind Co Ltd Optical head

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