Computer Holographic Measurement of Machine Parts by Laser Interferometry

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(1) To measure a deviation of objective surface of machine parts, a new interferometer by using the CCD image sensor instead of hologram in the previous proto-type interferometer was developed. The Introduction of the CCD image sensor gives stable measurement.(2) The brightness data of each interference fringe pattern to reference and objective surfaces is converted to discontinuous phase difference. Also a proposal in this report, that is, the computer holographic technique, was applied to the data processing. The technique enable phase to concatenate efficiently.(3) The interference fringe pattern on the CCD image sensor involves a thick density of fringes, and it also contains a considerable amount of noise. The problem to be solved such as pattern connected between neighboring fringes is remained, even if it is relieved by the technique mentioned above. For this problem, some methods by reducing the fringes by inserting concave lens in the path of the reference beam, by applying target surface form and by the heterodyne method using two beam sources with different wave lengths were introduced in the experiment. These methods were successful for data processing from the brightness data to the form deviation.(4) It is not distinct how many interference fringe patterns should be taken by phase shifting method to calculate phase difference from brightness data of interference fringe pattern. From a series of experiment using some plane test pieces, it is cleared that 6-8 sheets of the pattern are sufficient. This result increases considerably efficiency of data processing.