Automatic control method of spherical wave exposure interference field based on the Moiré alignment principle.

Aberration-corrected gratings are widely applied in spectral analysis owing to their dispersion and convergence properties. However, the phase distribution error of the exposure interference field reduces the accuracy of the groove density distribution, making it difficult to satisfy the needs of high-precision spectral instruments. Therefore, this paper establishes an error model for the phase distribution of the spherical wave exposure interference field, describing the relationship between the phase distribution error and the recording parameter error. This model is used to propose a method of automatically controlling a spherical wave exposure interference field based on Moiré alignment principle. This method automatically measures the phase of the interference field by extracting the phase from the Moiré fringes generated by the superposition of the interference field and the reference grating, and then inversely calculates the recording parameters. The measurement results are then fed back to the automatic calibration mechanism for compensation, thereby achieving automatic control of the exposure interference field. Applying this method to calibrate the exposure interference field reduces the average relative error of the groove density of the produced plane aberration-corrected grating by two orders of magnitude compared with that of the traditional control method. This method significantly enhances the control accuracy for the spherical wave exposure interference field, improving the distribution accuracy of the groove density of the aberration-corrected grating, thereby supporting spectral analysis.