This paper describes the design and realization of a new type of heterodyne interferometer for simultaneously measuring displacement and angle using only one reference retroreflector. Theoretically, this interferometer has better angle accuracy compared with classical systems that employ two reference retroreflectors because it can avoid the relative displacement resulting from external factors. The optical and mechanical configurations of the proposed interferometer, which consists of a frequency-stabilized dual-frequency laser, a monolithic prism, and additional optical and electronic components, are designed and finely processed. The experimental results show that the angle accuracy of the interferometer is greater than ±0.15 arcsec in comparison with an autocollimator.
Traditional laser angular interferometers based on a Michelson Interferometer or its modifications have the same principle: changing the angle displacement to an optical path difference. However, measuring the angular error of stage travels is a dynamic process. The main trouble is lack of displacement information and need to be solved urgently. A obvious method is using two dual-frequency interferometers to get the displacement and angular. In this paper, a new kind of displacement and angle interferometer (DIAI) is introduced. In this DIAI, displacement and angular are measured simultaneously by special optical path. The DIAI consists of a stabilized orthogonal polarization dualfrequency laser, a monolithic prism and additional optical and electronic components. The dual-frequency laser is divided into reference light and measurement light by a beam-splitting prism. The measurement light spatially separated into horizontal polarized light and vertical polarized light by the polarization splitting prism. Changing by a fixed 45°- tilted reflector, the vertical polarized light is parallel to the horizontal polarized light. These parallel lights reflected by two corner cube retroreflectors at a moving target. Compared with the reference light, the displacement and angular are measured. Different from the traditional method, there is only one reference corner cube retroreflector in this system. Thus, the angular measurement accuracy is better. The accuracy of the DIAI is better than ±0.25 arcsec in comparison with an autocollimator.