The Nanometer Displacement Measurement System Based On Optical Multiplication Path

Nano displacement measurement is the technology with high accuracy and high resolution. Typically, the higher the resolution and accuracy of the instrument, the more it costs and its structure is more complex. In this situation, a new measurement system is studied in this paper. Combined the Laser interferometry with the structure of optical multiplication frequency, the system can highly improve the resolution and accuracy at the source. More importantly, this system can easily be implemented and its cost is low. In this paper, three tasks are completed.(1) The theory of Interferometry is studied and based on this theory, the stuctue of optical multiplication frequency is used in the system and the complete optical measurement structure is designed, including the adjustable structure. The structure costs low and can be easily realized. At the same time, the character of the signal from this optical structure is analized, including its contrast, amplitude and frequency.(2) By using the combination of FPGA and PCI9054 chip, the signal acquisition circuit is designed with PCI interface. The circuit can adjust the signal and co nvert the analog signal into digital signal so that it can be analized by a computer. By using the PCI interface, the sampling rate can be highly improved and the speed of the whole system is accelerated.(3) Experimental platform is developed to evaluate the performance of the whole system. And the result is compared with the data from Dual- frequency laser measuring instrument. At last, the error of the whole system is analized in order to reduce the measurement error and get the condition of its use.