An ultra-sensitive angle sensor employing single-cell photodiodes, which allows tighter focusing leading to a higher angular resolution better than 0.001 arc-second, has been designed based on laser autocollimation. Aiming to investigate the influences of spherical aberrations in the optical system on the sensor sensitivity, an optical model has been established based on wave optics. Computer simulation has been carried out by using the model, and its feasibility has been verified in experiments. In addition, a prototype optical angle sensor has been designed in a compact size of 100 mm × 150 mm, and its measurement resolution has been verified in experiments.
This paper proposes a method of improving the sensitivity of the angle sensor for angular motion errors of precision linear stages. The sensitivity of the angle sensor based on laser autocollimation depends on the diameter of the incident beam on the objective lens. The relationship between the sensitivity of the sensor and the beam diameter is investigated by expanding the diameter and using a single-cell photodiode as the position-sensing detector corresponding to a small light spot. From the experimental result, the sensitivity is improved by expanding the diameter and the sensor can detect angular motion of about 0.001ʺ.
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