Three-degrees-of-freedom measurement system for measuring straightness errors and their position based on the Faraday effect

Abstract

A three-degree-of-freedom measurement system based on the Faraday effect is proposed for simultaneouslymeasuring two-dimensional straightness errors and their position. Thanks to the Faraday effect of faraday rotator,the direction of linearly polarized beam can be changed by 90° when the linearly polarized beam passes throughthe same Faraday rotator back and forth twice. A novel optical configuration is designed, which can integrate theinterferometry and position sensitive detection technology ingeniously and put their advantages together. Themeasurement principle is described in detail. The influence of angle error of the semi-transparent mirror onstraightness measurement is discussed. To verify the feasibility of the proposed system, the experimental setup formeasuring three degrees of freedom was constructed and a series of experiments were carried out.