Subarcsec High-Precision 3-D Spatial State Measurement System for an Optical Platform Based on Wavefront Phase Modulation

As the demand for stability in ultrahigh precision optoelectronic system alignments continues to increase, synchronous 3-D spatial state measurements are necessary to ensure the accuracy and reliability of detection data. In this context, a 3-D interferometry system based on computer-generated hologram (CGH) wavefront modulation was proposed, in which an aspheric mirror was used as a reference mirror (RM) to reflect in real time the wavefront changes caused by platform instability. The relative position calibration of optoelectronic elements and wavefront modulation are realized based on CGH. By employing a dual-constraint ray tracing method and a spatial state sensitivity matrix, a model was established to realize a mapping relationship between the RM 3-D spatial instability state parameters and the fit Zernike polynomial coefficients of the wavefront difference grid matrix. The experimental validation of the proposed 3-D spatial state measurement system was conducted. Measurement results were obtained from wrapped phase data processed using spatial phase unwrapping (SPU) by applying Zernike polynomial fitting and the mapping relationship. The results demonstrated the system’s capability to achieve real-time synchronous measurement of tilt and displacement in three dimensions with a high level of accuracy, exhibiting a maximum deviation error of less than $0.2"$ for tilt and $4~\mu $ m for displacement, respectively. The system demonstrated excellent stability throughout the experiments. The relative standard uncertainties for tilt and displacement measurements are 1.74% and 2.98%, respectively.