Novel Optical Design of Folded Fabry-perot Displacement Measurement Interferometer

Due to its high resolution and the large measuring range, laser interferometer has been applied widely to the precision industrial measurement and calibration. Fabry-Perot interferometry was often used for the microdisplacement, because of its common optical path structure being insensitive to the environmental disturbances. In the past researches, some kinds of modified Fabry-Perot interferometers with corner-cube reflector have been proposed to enhance the measuring range. With such new optical structure, the Fabry-Perot interferometer can be used in the purpose of hundred milometer displacement measurement. This will be beneficial to realize the high precision displacement in the large measuring range and under the ordinary measuring environment. In this investigation, a novel folded Fabry-Perot interferometer has been proposed. With the optical design, the optical resolution is about 158.2 nm and the measurement range of the Fabry-Perot interferometer can be enhanced up to 200 mm without any tilt angle compensation system.