Modeling and digital calibration for the mirror normal pointing error of the 2D scanning reflector

Abstract

The 2D scanning reflector (2DSR) has been widely used in various important opto-mechanical systems. The pointing error of the mirror normal of the 2DSR will greatly affect the optical axis pointing accuracy. In this work, a digital calibration method for the pointing error of the mirror normal of the 2DSR is researched and verified. At first, the error calibration method is proposed based on the datum, which consists of a high-precision two-axis turntable and the photoelectric autocollimator. All the error sources, including the assembly errors and the datum errors in the calibration are analyzed comprehensively. Then the pointing models of the mirror normal are derived from the 2DSR path and the datum path by using the quaternion mathematical method. Additionally, the pointing models are linearized by the Taylor series first-order approximation of the error parameter trigonometric function items. The solution model of the error parameters is further established by using the least square fitting method. In addition, the procedure of the datum establishment is introduced in detail to strictly control the datum error to be small enough, and the calibration experiment is carried out subsequently. At last, the errors of the 2DSR are calibrated and discussed. The results show that the pointing error of the mirror normal of the 2DSR decreases from 365.68 to 6.46 arc seconds after the error compensation. The consistency of the error parameters of the 2DSR calibrated by digital calibration and physical calibration verifies the effectiveness of the digital calibration method proposed in this paper.