Coherent light generators – Particular beam control device – Having particular beam control circuit component
Reexamination Certificate
2006-08-31
2009-11-17
Rodriguez, Armando (Department: 2828)
Coherent light generators
Particular beam control device
Having particular beam control circuit component
C372S038010
Reexamination Certificate
active
07620083
ABSTRACT:
A semiconductor laser drive system and a semiconductor laser driving method where both internal noise and optical feedback noise can be simultaneously reduced are provided at low cost and low power consumption. The semiconductor laser drive system in an optical pickup configured such that a turn light9efrom an irradiated object of a laser beam9emitted from a semiconductor laser2enters into the semiconductor laser2is composed of a drive circuit3for driving the semiconductor laser2; an optical detector6for detecting light intensity of a laser beam9bwhere the laser beam9emitted from the semiconductor laser2is ramified to convert the light intensity into an electric signal; and a feedback circuit that is composed of an amplifier circuit7and a filter circuit arranged between the drive circuit3and the light detector6, and that applies electric negative feedback to the drive circuit3for reducing optical feedback noise if the frequency of the electric signal is within a frequency banc to be utilized as a signal, and that applies electric positive feedback to the drive circuit3for reducing internal noise if the frequency of the electric signal is outside the frequency band to be utilized as a signal.
REFERENCES:
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patent: A 2000-77774 (2000-03-01), None
A. Ariomoto,et al; “Optimum conditions for the high frequency noise reduction method in optical videodisc players,”Applied Optics., vol. 25, No. 9; pp. 1398-1403; May 1986.
M. Yamada; “Theoretical analysis of noise-reduction effect in semiconductor lasers with help of self-sustained pulsation phenomena,”J. Appl. Phys; vol. 79, No. 1; pp. 61-71, Jan. 1996.
M. Yamada et al; “Characteristics of Mode-Hopping Noise and Its Suppression with the Help of Electric Negative Feedback in Semiconductor Lasers;”IEEE Journal of Quantum Electronics, QE-23, No. 8, pp. 1297-1302, Aug. 1987.
National University Corporation Kanazawa University
Oliff & Berridg,e PLC
Rodriguez Armando
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