| Summary: | It is known that linear motion errors for linear guides can be measured by the autocollimation method. In this case, it is necessary to install a mirror on the measurement target. On the other hand, if a light with a wavelength sufficiently longer than that of the surface roughness of the measurement target is used, the need for a mirror is eliminated. We have proposed an autocollimation method using a mid-infrared laser. In the original prototype of mid-infrared autocollimator, the angle of laser irradiation is 45° to the measurement target. However, this method does not allow us to obtain a long measurement range. Therefore, we construct a system in which the laser irradiation angle is set to 0° by controlling the polarization of light. By using this method, autocollimation is applied to a sample with a root mean square roughness Rq of 0.2 μm, and an angular resolution of 1.1 arc-second is obtained.
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