Study Of Roll Measurement Method Based On The Pentagonal Prism

A laser measurement system with multi-degree-of-freedom (MDOF) is the focus of the precision manufacturing industry, where the roll angle error measurement remains a challenge and has not yet been solved properly. Existing methods are of low accuracy, or with complex structure, which cannot be integrated within the MDOF measurement.This thesis focused on the development of optical high-precision roll angle measurement which was applied in a MDOF measurement system. The pentagonal prisms were used to get parallel dual-beam and the retroreflector as the roll angle sensor. The high-precision roll angle measurement was obtained by the indirect straightness error measurement. The system applied the thermally-diffused expanded core (TEC) single-mode fiber-coupled laser module to reduce the laser beam drift and increase the collimation, which ensured the stability and precision of the measurement system. At the same time, the measurement resolution improved by increasing the distance of the pentagonal prisms. The system provides a simple, compact and real-time method for roll angle measurement, which is easy to incorporate within the MDOF measurement.This thesis includes the optical structure design, the software optimization, setting up the system and the achievement of a five-degree-of-freedom measurement system. The parallelism error of two measurement beams was analyzed and its feasibility was verified through a lot of experiments which obtained repeatable, stable and comparable results. The experimental results show that the roll angle error measurement resolution is better than0.15arcsec.