Development of a precise displacement sensor based on geometric optical amplification principle

In order to realize precise displacement measurement with low cost, a precise displacement sensor composed of right-angle reflectors is proposed in this paper. The sensor was designed as a reading head composed of a laser source and a position sensitive detector. The geometric optical amplification principle is proposed in this paper, when the relative displacement of the laser relative to the right angle mirror occurs, the relative displacement of the outgoing laser reflected by the right angle mirror will be multiplied. The displacement sensor with even magnification effect can be constructed only by the optical characteristics of right-angle mirror. The displacement measurement principle based on geometric optical amplification proposed in this paper, and the sensor prototype with double amplification is constructed, and relevant experiments are carried out. The experimental results showed that the sensor could achieve twofold amplification, the displacement measurement accuracy was ±500 nm, and measurement resolution was better than 100 nm. High-precision displacement measurement and a wide range can be achieved by using multiple reading heads. The measurement system does not require high precision of optical devices, so it is especially suitable for constructing a displacement measurement system with small range and high precision, through the multiple amplification structure, more than 10 times geometric optical amplification can be realized.