| Autor: |
Roman I. Kuts, Anatoly I. Malyshev, Ruslan K. Nasyrov, Dmitry A. Belousov, Victor P. Korolkov, Alaxander R. Sametov, S. L. Mikerin |
| Rok vydání: |
2019 |
| Předmět: |
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| Zdroj: |
Holography, Diffractive Optics, and Applications IX. |
| DOI: |
10.1117/12.2537269 |
| Popis: |
Computer-generated holograms are widely used in interferometry for aspherical mirror testing. However, CGH has relatively low numerical aperture, which is limited both by the spatial resolution of the manufacturing process and by the need to do the design in a frame of the rigorous diffraction theory. As a result, the typical minimum period for phase CGH is limited to about 2 μm, if a wavefront error does not exceed λ/20. It limits now f/number at value of f/1.5 for 633 nm wavelength. In this paper we discuss the technology of direct laser writing on metal films of the titanium group and chromium. It allows one to fabricate microstructures with a period of up to 1 μm at 0.7 μm spot size. Thermochemical effects of laser radiation on the films of various metals have been studied for a long time. The spatial resolution of thermochemical writing on metal films can be significantly improved by through oxidation, which dramatically increases negative feedback at light absorption. The study of laser writing on Zr and Ti films demonstrated their future promise for the technology of creating computer-generated holograms. However, the technology of laser through-oxidation is limited by relatively low scanning speeds of up to 500 mm/s. It limits CGH size when using circular scanning of the laser beam. Reactive ion etching of Ti films through the laser-induced oxide mask can be used to fabricate binary phase structures. The technology is studied for producing diffractive transmission spheres (TS) with an aperture of up to f/0.75. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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