Three dimensional profilometry using moire pattern projeciton

摘要

This paper describes a grating projection method using phase shifting technique for the measurement of surface profiles of three dimensional objects. In this kind of profilometry a grating with binary intensity distribution has been utilized in most of cases. And in these cases such problems are known as an error is caused due to the non-sinusoidal intensity distribution of the grating and another difficulty is also indicated that the period of the grating is required to be adjusted in accordance with the size and profile of the specimen. Here we propose to use a moire pattern which is produced by superposing two binary gratings. When two gratings are overlapped with an appropriate gap, the resultant moire pattern becomes closely sinusoidal in intensity distribution. Then, in the optical arrangment for profile measurement using a grating projection method, if one grating is rotated, the period of the pattern is varied arbitrarily. And iof one or two of the gratings are moved in one direction, the formed moire pattern cna be moved in one way to give necessary shifting of the phase. Surface profiles of some samples are measured to show validity of the moire pattern projection and utility of the prototype system.