A novel method to improve detecting sensitivity of quadrant detector

This paper presents a set of formulae for estimating the light spot position projected on a quadrant detector (QD). A novel method of annular segmentation calculus (ASC) is designed to analyze the detecting light spot of QD. The influences of the spot movement mode, spot energy distribution, and dead area to the dynamic range and the detection sensitivity are analyzed. It is shown in simulations that our new formulae have achieved a much better results to increase measurement accuracy. It is also shown that on the condition of the same spot size, the detection sensitivity of Gaussian distribution is prior to uniform distribution. The detection sensitivity of diagonal mode is better than cross mode. The detection sensitivity increases with increase in the size ratio of dead area to spot. The simulating and experimental results show that the measuring range of QD is 400 μm, and the resolution is 50 μm. The study presented here will be beneficial in developing the nanomechanical displacement detection techniques.