Abstract
The design of an ultraprecision displacement sensor with subnanometer resolution is proposed for the use of ultraprecision technologies. The principle of the sensor is based on the high-sensitive detection of power change at a specific point in the light reflected from the object surface which is subject to a small displacement. The sensor consists of the single light source, the reflective object and reference surfaces, the optical fiber bundles for transmission of the illuminating and the reflected light and the photodiodes setup. In operation, the object and the reference surfaces are illuminated by the light transmitted through the optical fiber bundles from the single light source. Then, the reflected light from both surfaces are transmitted through the other optical fiber bundles to two separated but equivalent photodiodes respectively. By using the differential amplifier, the diodes enable to give a high-sensitive displacement signal which is included in the total signal of the reflected light. The sensor proposed here has some distinctive features such as the non-contact measurement, the high resolution of 0.5nm, the wide working range of about 30μm within the 5% linearity and the sufficient stability of 1nm in 20 seconds for specific research purposes.
