Study On Signal Processing System Of Nano-Measurement Laser Heterodyne Interference Based On Digital Signal Processor

With the development of the science technology, the requirement of measurement technology for Industrial processing is further improved. Various of laser measurement technology is widely used in high precision measurement. Laser heterodyne interferometry is universally accepted because of its extensiveness measurement range, high precision, huge application area and traceability. Every country all over the world invests large manpower to research for practical application. This thesis supported by national natural science funds(no.90923026). A signal processing system of the laser heterodyne interference based on the Digital signal processor (DSP) is designed. This system achieves high accuracy displacement measurement.This thesis describes the principle of the laser heterodyne interferometry. After researching and analyzing the signal processing methods of laser heterodyne interferometry, a new method based on Digital Signal processor is proposed. This new method can realize the high accuracy displacement measurement. The designing of the hardware and software which is constituted the signal processing system is completed and the system runs successfully. The designing of hardware mainly contains preprocess circuit and connection circuit with DSP. The designing of software includes the module of signal acquisition with DSP, signal processing module, and communicating with PC module. The display interface in PC is programmable with visual basic language.The phase difference measurement experiment,system stability experiment and displacement measurement are carried out in order to verify the feasibility of the designed method. The phase difference measurement experiment chooses 5 degree as a single step to increase with the range between 0 degree and 360 degree. The experimental result shows that standard deviation is 0.041°and the linearity coefficient is 0.99989. The displacement measurement experiment chooses 5nm,10nm,20nm,30nm,50nm as step length to operate. The experiment result shows that the range of the standard deviation is between 2nm~3nm and the linearity coefficient is above 0.999. All of the experiment result show that the designed signal processing system can realize the high precision displacement measurement and it has high reliability and practicability...