A high-precision roll angle measurement method

A novel high-precision measurement method for measuring roll is presented. The pentagonal prism and corner-cube prism are used as splitting element and sensitive element, respectively. A pair of parallel collimated beams generated by a pair of splitting pentagonal prisms is incident upon the target moving along linear guide. Two beams returning from two corner-cube prisms on the target reach two four-quadrant photoelectric detectors (QD1 and QD2), respectively. So the roll can be measured by differential measurement based on QD1 and QD2. Further, the measurement resolution can be doubled and resistance to common mode interference can be enhanced, by adopting common-path structure based on the polarization splitting prisms. Feasibility of the method is verified by theoretical analysis and experiments. When the system parameters apply to the values supposed, for the roll, the angular resolution can reach to 0.1″, and measuring accuracy is about 1″.