Investigation on displacement measurements in the large measuring range by utilizing multibeam interference

The laser interferometer has been implemented for the precision displacement measurement and calibration, due to its high resolution of the nanometer order and the large measuring range. Multibeam interferometry is often used for the micro-displacement, because of its common optical path structure being resistive to the environmental disturbances. The conventional multibeam interferometers like Fabry-Perot interferometers are composed by two approximately parallel planar mirrors. With this optical structure, the measuring range will be constrained in micrometers. In this investigation, a modified multibeam interferometer with corner-cube prism has been proposed to resolve the problem. With the new arrangement of the optical path, the displacement measurement will be insensitive to the tilt angle and the optical resolution will be better than that of the conventional multibeam interferometer with two planar mirrors. This will be beneficial to realize the high precision displacement in the large measuring range and under the uncomplicated measuring condition. The experimental results show that the standard deviation is about 0.255 μm in measuring range of 160 mm, if the tilt angle is less than ±9." That also proves that the proposed interferometer is feasible for precision displacement measurement in the large range.