The Flat Crystal Shape Measurement System Based On Laser Plane Interferometer

In traditional optical cold processing field. Flat is a commonly used measuring instrument. So flatness is very important of its parameters. To be a measuring standard,its own flatness index need to be very precise. We always rely on visual measurement in our current metric field. Using aperture tolerances (N) and partial aperture tolerances (△1N.△2N) to characterize the flatness. But the efficiency and accuracy of this way can not meet the demand of economic and social development speed.The project is based on the transformation of laser interferometer named PG15-J4.It is a combination of CCD image sensor technology and computer image processing technology. It has improved not only the degree of the automation but also the accuracy of the result.This paper introduced the related theoretical knowledge of flat and the optical interference theory firstly, then elaborate several commonly testing methods. Finally we determine the equal thickness interference method is the best. Next we complete the re-equip of PG15-J4including light source and CCD.Then we did the image processing of the collected interferogram. Including the gray scale change, image filtering, binarization and the crucial stripe thinning processing. Finally obtained single pixel stripes. According to the GB2831-81we calculate the flatness index. The result comply with the JJG28-2000.Thus we achieve the goal that improve the testing efficiency and accuracy of measurement.