| 摘要 |
A measurement instrument of optical characteristics (1) has a light source section (10), a first optical coupler (21), a second optical coupler (22), a lens (31), a lens (32), a phase modulator section (40), a drive section (41), an optical path length difference adjustment section (50), a control section (51), a light receiver section (60), a synchronization detector section (70), and a measurement section (80). The phase modulator section (40) performs phase modulation of light at frequency f. The synchronization detector section (70) outputs a first signal of a value corresponding to a magnitude of the frequency f components contained in an electrical signal output from the light receiver section (60) as well as outputs a second signal of a value corresponding to a magnitude of the frequency 2f components contained in the electrical signal. The control section (51) controls a difference in the optical path lengths that is adjusted by the optical path length difference adjustment section (50) to be a specified value in accordance with the first signal and the second signal being output from the synchronization detector section (70). |
