Abstract: A new laser measurement system has been developed for identifying geometrical error of a machine tool. Five moving error components in a motional direction can be measured by using this system simultaneously, such as yawing, Pitching rolling, and two straightness errors.The system integrates a linear displacement measuring system using the unique property of retro-reflector and an angular displacement measuring system using the principle of auto-collimator. The basic system consists of twoparts: a refevence part mounted on a reference base; a measuring part fixed on the moving table to be measured.The measuring portion contains a flat mirror to detect the yaw and pitch angular errors, and two separate retroreflectors to measure the linedr errors.The rolling error component is calculated by the distance between the two retroreflectors and their two vertical linear error components. The reference portion contains a He-Ne Laser tube, a beam expander, a beam splitter, two polorized beam splitters, a combined auto-collimator , a half wave plate and a quarter wave plate, four two-dimensional position sensing devices, and three reflection mirrors.The accuracy of the system is within 1.5μm and 0.5" for linear and angular displacement respectively.

Key words: machine tools, laser measurement system, moving error, control equipment