A Three-Axis Angle Sensor with a Linear Encoder Scale Reflector

This paper presents a design study of an optical three-axis angle sensor for measurement of angular error motions of long-stroke precision linear stages. The three-axis angle sensor, which is based on a laser autocollimation method, can detect angular motions about the XYZ-axes simultaneously by using zeroth-and first-order diffraction beams from a diffraction grating mounted on a measuring target as a reflector. In this paper, an optical sensor head is designed in such a way that the three-axis angle sensor shares a diffraction grating with an optical sensor head of a linear encoder, which is already installed in a stage system. The optical sensor head of the three-axis angle sensor is designed in a size of smaller than 50 mm × 30 mm × 30 mm so that the sensor head can be compatible with the linear encoder. Details of the optical configuration designed for the sensor head, and some results of experiments are reported.