| 摘要 |
PROBLEM TO BE SOLVED: To provide a vibration measuring apparatus capable of measuring a high frequency minute vibration. SOLUTION: An object 10 to be measured vibrating with a frequencyωis irradiated with light whose intensity is modulated with a frequencyωm from a laser diode 14. The light reflected by the object 10 to be measured is detected by a division photo-diode 16 divided into two regions. A component of beat of a frequency (ω-ωm) is contained in the difference of intensities of the reflected lights received by the two regions. The frequencyωis calculated by calculating the frequency of the beat using a frequency detector circuit 17. Whenωexceeded 1MHz, it was conventionally difficult to measure with high accuracy on performance of a detector. However, since (ω-ωm) can be set to 1 MHz or less by appropriately settingωm in the present invention, it is possible to measure with high accuracy even ifωexceeds 1 MHz. COPYRIGHT: (C)2006,JPO&NCIPI
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