Fabry-Perot displacement interferometer for the measuring range up to 100 mm

Current commercial laser interferometers have demonstrated outstanding measuring performances for high precision measurements, but they are very sensitive to environmental or mechanical effects. Owing to the fact that the most laser interferometers are based on the structure of Michelson interferometer, the above-mentioned influences from measuring arms will undisputedly lead to significant errors. To realize the high precision measurement, the environmental conditions must be strictly demanded. As a result of that limit, it's inconvenient for industrial applications. In comparison with such non-common optical path structure, conventional Fabry-Perot interferometer with common optical path can effectively reduce the measuring errors resulting from environmental disturbances. To minimize the environmental and mechanical effects, a new interferometric displacement system with the structure of common optical path is proposed. By the optical interference principle and the corner cube reflector, the novel system with the common optical path can be designed. Hence, the novel interferometer can hold the advantage of large measurement range, and the signal pattern is nearly the same with that of Michelson interferometer. Because of the folded optical cavity, the resolution of the multi-interference interferometer with corner-cube can be enhanced to λ/16. Through this development, a high accurate interferometric displacement measurement system can be available under ordinary environmental conditions without the compensation requirement of the tilt angles and its prominent measurement characterizations have been proven. It will be demonstrated that measurement range is larger than 100 mm and the standard deviation of the comparison experiment is about 0.211 μm (within half wavelength) in the whole measuring range.