Research Oninstrumentation Of Digital Moiré Phase-shifting Interferometer

Because aspheric optical element is widely used, the aspheric surface testing technology and testing instrument is particularly important. Now aspheric surface testing instrument based on interferometry technology is the main development direction. Digital moiré phase-shifting interferometry based on partial compensation method has advantages of high precision, good generality, high speed and easy calibration, which is promising in the filed of large diameter and deep asphericity. However, the corresponding interferometer is deficient in market. In this thesis, we proposed to study the instrumentation of digital moiré phase-shifting interferometer based on partial compensation method.Based on the principle of digital moiré phase-shifting interferometer and aspheric surface testing target, this thesis completes the general design of the interferometer system, including a real non-null test interferometer optical system, an image transmission system, a moiré image real-time synthesis and display system, and analyzes the function and the design difficulty of each subsystem. The thesis then researches and designs each subsystem.The real non-null test interferometer system optical system combines the advantages of Twyman-Green interferometer and Fizeau interferometer, including a collimating and beam expanding system and a telescope system. The thesis designs these two systems and further analyzes the tolerance in Zemax to meet the design requirement and finally realizes the optical system.For the image transmission system, the thesis first selects the hardware according to the transmit requirement and makes a general design. In the image transmission system, the thesis mainly researches the data transmission between FPGA and DSP with EMIF interface and EDMA mode. In order to realize image data tramission between FPGA and DSP, the thesis designs the software modules in the DSP and FPGA.In the moiré image real-time synthesis and display system, the thesis researches the implement of digital moiré technique on DSP. Moiré synthesis image is correspongding to the aspheric surface figure error which is used to align the real non-null test interferometer system. The thesis also analyzes how to adjust the real non-null test interferometer system.The thesis lays a foundation for the instrumentation of digital moiré phase-shifting interferometer.