Development of a deep-hole measuring system by using autocollimation principle optical analysis and its verification experiment

The measuring system for evaluating the accuracy of a deep hole is developed by using the autocollimation principle. The system consists of a measuring unit and an optical system for light reception. The measuring unit comprises one laser diode, two mirrors, two quarter-wave plates, one polarizing beam splitter, and a feeler. It detects the displacement of a feeler on the basis of the autocollimation principle. The optical system for light reception, which receives the laser beam irradiated from the measuring unit, comprises a plano-convex lens and a CCD camera and receives the laser beam irradiated from the measuring unit. In this study, the evaluation function of various errors of the optical system is derived using ray tracing and their effect on the measuring accuracy is examined. The results show that the measurement error of the deep-hole measuring system due to the misalignment of the optical parts is about ±1 μm and that the detection error of the mirror angle due to the lens aberration used in the optical system for light reception can be reduced to less than 0.003° , which corresponds to the displacement of 0.87 μm of the feeler.