Coherent light generators – Particular beam control device – Having particular beam control circuit component
Patent
1984-01-30
1986-03-18
Davie, James W.
Coherent light generators
Particular beam control device
Having particular beam control circuit component
372 38, H01S 313
Patent
active
045773203
ABSTRACT:
A light power controlling apparatus contains a semiconductor laser and a photosensor for receiving part of light emitted from the semiconductor laser to produce a corresponding electrical signal. The semiconductor laser is connected to first and second current circuits. The first current circuit averages a voltage signal based on the electrical signal of the photosensor by a first low-pass filter, thereby to have a detected voltage. The detected voltage is compared with a desired voltage by an error amplifier. The error amplifier produces a signal representing a difference between the detected voltage and the desired voltage. The difference signal is integrated by an integrator. According to the integrated signal, the first current circuit supplies a forward current to the semiconductor laser. The second current circuit is set at a peak power value in a modulating mode according to a voltage signal of a peak power setting member. The second current circuit supplies to the semiconductor laser a forward current according to a modulating signal, with superposing on the forward current of the first current circuit. The modulating signal is averaged by a second low pass filter. A voltage representing the product of the averaged value and the peak power value is added to the desired value. The sum voltage is then supplied to the error amplifier where it is compared with the detected voltage.
REFERENCES:
patent: 3898583 (1975-08-01), Shuey
patent: 4292606 (1981-09-01), Trimmel
patent: 4450564 (1984-05-01), Meuleman et al.
patent: 4516242 (1985-05-01), Yokota
Chen, "Simultaneous Feedback Control of Bias and Modulation Currents for Injection Lasers", Electronics Letters, Jan. 3, 1980, vol. 16, No. 1.
Sakamoto Masaharu
Yoshikawa Shoji
Davie James W.
Olympus Optical Co,. Ltd.
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