Development of a new measurement, system for straightness error by a heterodyne interferometer with a grating

A new straightness error measurement optical system has been developed. This system consists of three components: (i) A He-Ne Zeeman laser, (ii) A grating secured onto a slide table and (iii) A heterodyne interferometer where a beat signal, which includes a phase shift deltaphi depending on an in-plane displacement deltax of the grating, is generated. Straightness error can be measured, because deltaphi is proportional to deltax. In this study, using this system, straightness error of a slide table is measured experimentally. Straightness error measured by this system is good agreement with one measured by a commercial laser interferometer system. The effectiveness of this system is confirmed by this result.