Research on exposure mosaic of large-aperture holographic lens

Compared with traditional refraction and reflection elements, diffractive imaging elements can be used as the primary mirror in large-aperture space telescope systems due to their low surface density and loose surface tolerances. At the same time, the expansion of the aperture of diffractive imaging elements has become an important development trend. In order to explore the manufacturing method of large-aperture diffractive imaging element. This paper proposes to use holographic lens as the diffractive mirror, and enlarge the aperture of holographic lens through exposure mosaic technology. By deflecting light path and rotating the substrate, the distribution position of the Gaussian beam center of the interference light field is changed, and the aperture of the holographic lens is increased through multiple exposures and developments. The effect of splicing errors on the imaging of the holographic lens is analyzed. In the scheme, the exposed and developed area is used as the alignment basis. The splicing error is judged according to the moirefringe formed by the light field and the developed area, the fringe acquisition and control system is used to collect the moire. The interferometer measured the phase error at the splicing area of the sample to be about 0.1 lambda, and the splicing error satisfies the imaging requirements of the holographic lens. The results show that the holographic splicing scheme is feasible and the splicing accuracy is high, which provides a solid theoretical foundation and technical support for multiple exposures to produce larger-diameter holographic lenses.