| 摘要 |
<P>PROBLEM TO BE SOLVED: To enhance the measurement accuracy of the vibrational frequency of an object. Ž<P>SOLUTION: A vibrational frequency measuring apparatus includes: a semiconductor laser 1 which radiates a laser beam to an object 10 of a measuring target; a photodiode 2 converting optical output of the semiconductor laser 1 to electric signals; a laser driver 4 for driving the semiconductor laser 1; a current-voltage conversion and amplification section 5 for converting the output current of the photodiode 2 into a voltage, for amplification; a filtering section 6 filtering carrier wave from the voltage output of the current-voltage conversion amplification section 5; a signal extraction section 7 for counting the number of mode hop pulses or self-combined signals contained in the voltage output of the filtering section 6; and a frequency measuring section 8 for determining vibrational frequency of the object 10, based on counted result of the signal extraction section 7. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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