Micro-Stress Support-Enhanced Two-Plate Shearing Absolute Testing for Φ800 mm Interferometers

Large-aperture optical elements are increasingly in demand for applications in astronomy, high-power lasers, and aerospace technology, but their manufacturing and testing processes pose significant challenges. In this paper, we propose an ultra-large-aperture digital laser plane interferometric testing technique that combines the two-plate shearing absolute mutual testing method with micro-stress support technology. This method enables high-precision testing of Φ800 mm planar elements and offers advantages such as fast testing speed, high resolution, and precise alignment. Simulation results and comparisons with measurements from a ZYGO interferometer validate the effectiveness of the proposed method. Experimental testing of an Φ800 mm planar element yielded a PV value of 0.0923λ and an RMS value of 0.0114λ at a wavelength of 632.8 nm. The quantitative results are incorporated into the abstract and conclusions, highlighting the method's minimal error and high accuracy. This technique provides a novel approach for high-precision testing of large-aperture optical elements.