| 摘要 |
PURPOSE:To measure variation in the film thickness of a thin film formed on a rotating disk at the same position momentarily by providing a rotary image still device equipped with a rotary right-angle prism which rotates synchronously a half as fast as the rotating speed of the rotating thin film in the incidence optical path of laser light. CONSTITUTION:The rotary image still device 6 equipped with the rotary right-angled prism 8 which rotates synchronously a half as fast as the rotating speed of the rotating thin film is provided in the incidence optical path of the laser light, and a beam splitter which separates the incidence optical path and a reflection optical path is provided in the optical path of the reflected light of the laser light. Then the prism 8 which rotates synchronously a half as fast as the rotating speed of, for example, a rotary sample base 2 for rotating the thin film by detecting the rotating speed is used to project the laser light on the film thickness measurement point of the thin film sample 1 while following up the rotary movement of the measurement point. then reflected light beams from the top and reverse surface of the thin film interferes each other to become interference light, which travels through an optical path different from the optical path of incidence and is photodetected by a photodetector 15, so that variation in the interference light intensity is detected.
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