A model of measurement error caused by non-uniform spot on four-quadrant detector

Aiming at the influence of the energy distribution of incident light on the traditional location algorithm of four-quadrant detector (4-QD), the generation rule of measurement error is analyzed. A model to express the energy distribution of the light spot of 4-QD is established by using characteristic parameters, and the measurement error model related to the characteristic parameters is derived. In the actual system, for different spot locations, we can use this model to fit the energy distribution, and get the spot characteristic parameters of the system, and then use it to calculate the measurement error caused by the traditional algorithm in 4-QD system. In the experiment, the energy distribution image of the incident beam is obtained by the beam quality analyzer, and the actual moving distance of the spot is compared with the calculation result of the traditional measurement algorithm. From the experimental results, it can be proved that the measurement error model of the four-quadrant detector, which is described in this paper, is consistent with the experimental results. It can further modify the calculation results of the 4-QD system in practical applications, to improve the measurement accuracy.