Research On Grating Moire Fringe Interferometry And Its Application

At the present time, grating linear movement sensor based on grating Moiréfringe interferometry technology has developed rapidly. Grating movement measurement system has reached the nanometer level resolution, measuring accuracy than 0.1um.It is widely used, almost penetrated into the social sciences in various fields, such as the machine tool industry, test measurement, aerospace navigation, national defense, education and scientific research in all industry sectors.This paper first described in detail the formation mechanism of Moiréfringe,when the measurement grating for coarse grating, the moire fringe formation mechanism of the shadow of the principle of using sunscreen to explain, when the measurement grating for fine grating, then explained by diffraction interference principle. And then systematically introduced the principle of design of grating linear movement sensor based on Grating Moiréfringe technology, grating linear movement sensor is composed of grating reading-head and moire fringe signal processing electronics components. Grating reading-head include Grating pair, the lighting system composed of light source, collimation mirror, the essential diaphragm, received slot and adjusted organization, etc. Finally, a new kind of application based on the Moiréfringe interferometry technology is proposed, which apply the grating linear movement sensor to the digital reading microscope. The digital reading microscope includes optical system, control and display system, CCD camera and display four parts, among them, it is the key module that is designed to control with the display system, which is based on FPGA technology and mainly concludes four fold-frequency subdivision and direction-judgment module , reversible counter module,displaying control module and displaying interface module.After a lot of theoretical research and practical testing, we have already applied grating Moiréfringe technology to the digital reading microscope successfully, which has made the accurate measurement of linear displacement of the testee become true, and the measured resolution has reached 0.5um, the measurement accuracy has reached±1um. CCD camera instead of eyepiece can avoid the inconvenience of traditional visual observation.