| 摘要 |
PROBLEM TO BE SOLVED: To easily measure the thickness of a measuring object with high accuracy, without being affected by vibration of the object and vibration of a transmission medium of measurement light from a light source to an interferometer. SOLUTION: A split light of main light P0 emitted from a single-wavelength laser light source 2 is guided toward two measurement optical units Z through optical fibers a10 and b10, and the like. The measurement optical units Z face measurement parts 1a and 1b, facing each other, on the respective back-and-front surfaces of the object 1, respectively, and integrally hold an optical apparatus. In the measurement optical unit Z, each split light of the main light P0 is further split into two light beams by a beam splitter 13, and two measurement light beams P1 and P2 that differ in frequency are generated from the resulting split beams by sound optical elements 15 and 16, respectively. Photodetectors 28 and 38 detect the measurement beat signals obtained by a heterodyne interferometer 20, by using the measurement light P1 as object light and the measurement light P2 as the reference light; and reference beat signals, based on the two measurement light beams P1 and P2. The phase difference of both the beat signals is detected as the phase information for the thickness calculation of the object 1. COPYRIGHT: (C)2010,JPO&INPIT |
