Amelioration of accuracy of displacement measurement in strong feedback regime based on region decision: Enlargement of measurement range of self-mixing displacement sensor

Abstract

Increasing the measurable distance and the displacement measurement limit of a self-mixing displacement sensor poses one of the most important problems to improve the sensor’s performance. In order to solve the problem, there has to be found the estimation method of the optical feedback factor for a strong feedback regime. The hardship of the estimation in this regime is brought about by a strong speckle noise and the restriction of normalization methods presented hitherto. In the paper we have found an approach to improving the accuracy of the self-mixing sensor, which can work even for long range and large displacement, by deciding the region of the optical feedback factor based on the ratio of fringe height and using it and fringe counting method.