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23 October 2001 Three-dimensional profilometry using hybrid grating projection
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This paper describes a grating projection method for the measurement of surface profiles of objects. In this kind of profilometry, a grating with binary transmittance distribution has been utilized usually. And in these cases such a problem is known as an error is caused due to the non-sinusoidal transmittance distribution of the grating. And another difficulty is also indicated that shifting of the grating is given by mechanical movement of the grating. Here we propose to use a hybrid grating is given by mechanical movement of the grating. Here we propose to us a hybrid grating which consists of a conventional binary grating and a liquid crystal binary grating. Then moire pattern is produced by superposing these two binary gratings. When two binary gratings are overlapped with an appropriate gap, the resultant more pattern becomes closely sinusoidal in intensity distribution. The, in the optical arrangement for profile measurement using this hybrid grating, when the LC gratin pattern is moved, the projected pattern is shifted arbitrarily in phase. Surface profiles of some samples are measured to show validity of the more pattern projection and utility of the prototype system.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Toru Yoshizawa, Hiroshi Takahashi, Masayuki Yamamoto, Yukitoshi Otani, and Hiroo Fujita "Three-dimensional profilometry using hybrid grating projection", Proc. SPIE 4398, Optical Measurement Systems for Industrial Inspection II: Application in Industrial Design, (23 October 2001);

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