摘要 |
According to the present inventions, a phase control device for laser light pulse includes a laser, a reference comparator, a measurement comparator, a phase difference detector and a loop filter. The laser outputs a laser light pulse. The reference comparator compares a voltage of a reference electric signal having a predetermined frequency and a predetermined voltage with each other, thereby outputting a result thereof. The measurement comparator compares a voltage based on a light intensity of the laser light pulse and a voltage of a measurement electric signal having the predetermined frequency, with a voltage of a phase control signal, thereby outputting a result thereof. The phase difference detector detects a phase difference between the output from the reference comparator and the output from the measurement comparator. The loop filter removes a high frequency component of an output from the phase difference detector. Further, the voltage of the phase control signal is different from the predetermined voltage. Furthermore, the laser changes the phase of the laser light pulse according to the output from the loop filter.
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