Mid-infrared autocollimation for linear motion error measurement

• Main Authors: Hiraku Matsukuma, Kaede Matayoshi, Masashi Nagaoka, Yuki Shimizu, Wei Gao
• Format: Article
• Language: English
• Published: Elsevier 2021-12-01
• Series: Measurement: Sensors
• Subjects: Mid-infrared laser; Autocollimation; Motion error; Rough surface
• Online Access: http://www.sciencedirect.com/science/article/pii/S2665917421002282

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.