| In recent years, Surface measurement is developing towards large range and high resolution. With the development of technology, it is urgently necessary to develop large range surface measurement instrument, combining laser and grating interference with traditional stylus measurement technology is a promising measurement method, which is full use of stability and reliability of stylus measurement technology, high resolution and large range of interference. Processing the optical output signal has become a significant way to improve resolution. To improve the accuracy of measuring signal and the frequency response, a better data processing system are need, and only in this way can the data be accurately obtained and correctly handled. Based on the requirements, it has developed a spherical grating sensor signal processing system. The specific research contents are as the follows:In a new optical structure, the spherical grating was used as a sensing element. Using laser's secondary diffraction on spherical grating as coherent light formed interference fringe. Using the Doppler Effect we can conclude that there is a definite function relationship between micro-displacement and movement of Grating interference fringe.The circuit requires collecting Grating interference fringe. The hardware circuit divided into analog part and digital part. The analog part will mainly take the photodiode as the core, receiving the grating fringe signal and getting sinusoidal signals through I/V conversion, differential amplification and filtering. AD converter chip TLC5510 sampled analog signals in high speed, and process the signal using the programmable logic device EP1C6T144C8 (FPGA). On the platform of Quartusâ…¡, we can use Verilog HDL to design each module, and then connect together in the top modules, and finally realize the temporal logic control.Experiment proved that the signal processing system satisfy the requirement of spherical grating interference fringe processing. |
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