New Methods of Manufacturing High-Aperture Computer-Generated Holograms for Reference Wavefront Shaping in Interferometry

Factors causing parasitic distortions of interferograms in control systems based on reference single-component high-aperture computer-generated holograms (CGHs), which are made on flat substrates and have a binary phase structure, are analyzed with respect to the problem of interferometric testing of spherical and aspherical surfaces with high angular apertures. The quality of such CGHs is improved using the methods, means, and writing materials (titanium and chromium films) suitable for direct laser writing of their diffraction structure, which provides the generation of interferograms with minimal parasitic distortions. In particular, it is proposed to modulate the local transmission coefficient of the CGH structure by applying duty cycle modulation to the diffraction zones in order to reduce the variations in contrast of the generated interferogram. Possibilities of the application of the thermochemical laser technology of writing on titanium and chromium films for manufacturing high-aperture holograms with the f-number $$f/1$$ and higher are discussed.