Title:
SEMICONDUCTOR LASER OPTICAL DEVICE
Document Type and Number:
Japanese Patent JPS63208704
Kind Code:
A
Abstract:
PURPOSE:To accurately measure the tilt angle and intensity ratio of the substrate of an optical disk by inputted a high-frequency signal to the driving stage for a semiconductor laser so as to eliminate interference fringes formed by the interference between reflected light beams from the top and reverses surfaces of a parallel plane plate. CONSTITUTION:A driving circuit 13 sends a DC or pulse signal and the semiconductor laser 1 oscillates. At this time, a high-frequency oscillator 14 superposes an AC signal of hundreds of MHz - about 1 GHz upon a signal from the driving circuit 13. Consequently, the oscillation longitudinal mode spectrum of the semiconductor laser 1 which oscillates in single mode is made multiple by the high-frequency superposition. The visibility of interference fringes of the multiple semiconductor laser decreases abruptly with an optical path difference. Consequently, the interference fringes generated between the reflected light beams from the top and reverse surfaces of the optical disk 5 disappear and no interference fringes appear on a monitor 12.
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Inventors:
TATENO KIMIO
OTAKE MASATOSHI
MIYAMURA YOSHINORI
ITO SHO
OTAKE MASATOSHI
MIYAMURA YOSHINORI
ITO SHO
Application Number:
JP4022787A
Publication Date:
August 30, 1988
Filing Date:
February 25, 1987
Export Citation:
Assignee:
HITACHI LTD
International Classes:
G01B11/24; (IPC1-7): G01B11/24
Attorney, Agent or Firm:
Katsuo Ogawa