On a machine tool, geometric deviations (positional and angular deviation) occur according to the movement of table, column, and so on. On the other hand, a laser measurement system has become popular, since it performs highly accurate measurement of the each geometric deviation except for roll deviation. In this paper, we focus on the improvement of measurement sensitivity of roll. The system consists of a bi-prism, a double-path optical heterodyne laser interferometer and a V-shaped reflector which composed of two plane mirrors. For improvement of measurement sensitivity, reflexive reflecting prisms are attached on the rear-side of the interferometer to make number of laser paths increase comparing with the conventional system. From the experimental results, it is confirmed that measurement sensitivity is increased in proportion to the number of laser paths.
