Publications by authors named "Fengyou Li"

We proposed a valid method with a novel computer-generated hologram (CGH) to test large-aperture convex aspheric. The CGH consisted of two zones with different amounts of power: the central zone has a larger amount of power than the marginal zone. Compared with other CGHs used for convex aspheric testing [SPIE.

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The formation of multiplexed phase-only holograms with more weighted phase functions creates spurious cross terms and nonlinear scaling. We extend previously reported work [Appl. Opt.

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A valid optical system with a computer-generated hologram fabricated on a concave lens surface, for measuring large-aperture convex surface, is demonstrated experimentally. The CGH employed in this system has been constructed using a new technology that combines laser direct writing and lithography. This technology allows precise alignment, superior linear profile and high resolution of the gratings that compose the CGH.

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We fabricated a large curved computer-generated hologram pattern on the concave substrate with diameter of 110mm and radius of curvature of 504mm. The line width of the hologram varied form 39um to 810um. We adopt the single pass and the screw-lines to fabricate this curved hologram precisely and efficiently.

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We demonstrate experimentally the technique of fabricating large diffractive optical elements (DOEs) in thick film on a concave lens surface (mirrors) with precise alignment by using the strategy of double exposure. We adopt the method of double exposure to overcome the difficulty of processing thick photoresist on a large curved substrate. A uniform thick film with arbitrary thickness on a concave lens can be obtained with this technique.

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We present what we believe to be a new method for correcting the joint error of a laser writer without reduction of throughput. By digitization, we optimize the intensity data of the incident beam at the vicinity of the start point and the end point. The joint error will not be sensitive to lengthening of the start or end point by optimization.

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We demonstrate experimentally the lithography technique to fabricate a large computer-generated diffractive optical element (DOE) pattern on a concave lens surface with precise alignment by using a laser direct writer. We obtained photoresist film with uniform thickness on the large concave substrate by selecting proper spin-coating parameters, which mainly involve spin rate, spin acceleration, and viscosity of the photoresist. We obtained a square line profile on the concave lens surface.

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