Method of and apparatus for controlling deflection of optical beams
AssigneeDainippon Screen Mfg. Co., Ltd.
InventorsAkira Kuwabara, Eiichi Tamaki, Yasufumi Koyama
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Abstract
An AOD driver (27) generates a driving signal of an AOD (11), whose frequency varies in response to a sweep signal and whose amplitude varies in accordance with an amplitude control signal. In an initial stage, a constant signal level is stored in a memory (29) and is supplied to the AOD driver. A laser beam is deflected by the AOD and the light intensity thereof is detected by a photo-sensor (14). A signal representing the light intensity is given to a CPU (33) and a corrected amplitude control signal is generated, which is stored in the memory in place of the original amplitude control signal to control the AOD driver.
Claims20
A method of controlling an optical beam deflected by an acousto-optic deflector, said method comprising the steps of:
- (a) generating a periodic sweep signal whose level varies with time;
- (b) generating an amplitude control signal synchronized with said sweep signal;
- (c) generating a drive signal whose frequency and amplitude vary in response to said sweep signal and said amplitude control signal, respectively;
- (d) providing said drive signal to said acousto-optic deflector to thereby drive said acousto-optic deflector to thereby drive said acousto-optic deflector and obtain a deflected optical beam;
- (e) detecting light intensity of said deflected optical beam with a photo-sensor in synchronism with said sweep signal, to thereby obtain light intensity data representing dependence of said light intensity on said frequency;
- (f) correcting said amplitude control signal as a function of a reference light intensity value to obtain a corrected amplitude control signal, said reference light intensity value retrieved within said light intensity data;
- (g) generating said drive signal again while substituting said corrected amplitude control signal for said amplitude control signal;
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- (h) providing said drive signal generated in the step (g) to said acousto-optic deflector to thereby obtain said deflected optical beam with intensity corrected.
An apparatus for controlling an optical beam deflected by an acousto-optic deflector, comprising:
- (a) memory means holding predetermined amplitude control data;
- (b) means for generating a periodic sweep signal whose level varies with time;
- (c) means for generating an address signal representative of respective addresses of said memory means in synchronism with said periodic sweep signal;
- (d) means for reading said amplitude control data from said memory means to generate an amplitude control signal synchronized with said sweep signal;
- (e) driver means for receiving said sweep signal and said amplitude control signal and for generating a drive signal whose frequency and amplitude vary in response to said sweep signal and said amplitude control signal, respectively, wherein said drive signal is supplied to said acousto-optic deflector to drive said acousto-optic deflector and obtain a deflected optical beam;
- (f) photo-sensor means operable to detect light intensity of said deflected optical beam and to generate an intensity signal representing said light intensity;
- (g) means for receiving said intensity signal and said address signal to obtain light intensity data representing relationship between said light intensity and said respective addresses;
- (h) means for generating a corrected amplitude control signal as a function of a reference light intensity value and storing said corrected amplitude control signal in said addresses of said memory means in place of said predetermined amplitude control data said reference light intensity value being retrieved within said light intensity;
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- (i) means for reading said corrected amplitude control signal from said memory means to deliver said corrected amplitude control signal to said driver means, in place of said amplitude control signal, thereby obtaining said deflected optical beam with intensity corrected.
Dependencies are inferred from the claim text.