| 摘要 |
PURPOSE:To measure true thermal expansion vibration of a specimen without being influenced by a disturbance by converting a beat signal into a binary signal and generating a delay signal which delays by predetermined time from the binary signal. CONSTITUTION:A measurement light beam (beam 1) having oscillation frequency F1 is applied to a specimen surface position where thermal expansion vibration occurs due to application of excitation light, the reflected light and reference light (beam 2) having oscillation frequency F2 are interfered with each other. After an electric signal E wherein the interference light is photoelectrically converted 11 is obtained, a beam wave signal E1 of the signal E {beat frequency: Fb (Fb = F1 - F2)} is taken out. Then the beam wave signal E1 is binarized 13 to be converted into a binary signal E2, and a delay signal E3 delayed by time tau from the binary signal E2 in a delay circuit 14 is generated. Then a signal component V0 related to frequency F is extracted 16 from a multiplication signal Vm obtained by multiplying the binary signal E2 by the delay signal E3 to estimate a specimen by amplitude and a phase of the signal component V0. Thus true thermal expansion vibration of the specimen can be measured without being influenced by a disturbance. |
