Absolute Calibration of Smooth Surface and Cylindrical Surface Measurement

Digital interferometer is widely used for evaluating optical surfaces due to its outstanding sub -nanometer accuracy and precision. In this paper, we will summarize its advantages and then describe its applications in industry, especially in both absolute flat and cylindrical surface and measurements. Transmission flat has normally 1/20 wavelength PV. However, when a flat surface under test is better or much better than the transmission flat, we need the absolute flat measurement. We developed a method to be easily able to achieve the accuracy of 1/100 wavelength PV. Two different measurement methods are proposed for the surface shape measurement of the inner surface and the outer surface of the cylinder, and the circular data is converted into rectangular data. For off-axis aspheric surfaces, we also propose a new measurement method. We have dedicated our efforts to do so. The theoretical analysis and experimental validation are presented in the paper.