On Compensation of Errors in the Moire Method by Use of Diffraction Beams

抄録

The moire method by use of diffraction beams is effective for the measurement of strain components. However, errors are caused by nonuniformity in thickness of film used as specimen gratings, unevenness of surface of mirrors, aberration in lenses, etc. in this paper three methods are proposed, by which these errors are compensated. First, "the looped path method" is discribed. In this method two beams which are to produce an interference pattern pass the same looped path, but in opposite directions to each other, thus the above mentioned errors are compensated. Secondly, an optical system proposed by Sciammarella(1967) is applied to the shifting method, and it is found that those errors can be largely reduced by adjusting an optical apparatus precisely. Thirdly, the double exposure method is described, in which the errors are compensated and sensitivity of measurement is doubled.