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oai:docta.ucm.es:20.500.14352/350412023-08-25T12:45:29Zcom_20.500.14352_14col_20.500.14352_15

00925njm 22002777a 4500 dc Torcal Milla, Francisco José author Sánchez Brea, Luis Miguel author Bernabeu Martínez, Eusebio author 2015 We analyze the field produced by a cylindrical convex diffraction grating at the Fresnel regime for several kinds of light sources, including a monochromatic quasipunctual source, finite size, and polychromatic sources. These results can help one understand the functioning of rotary optical encoder technology. A decrease in the self-image contrast is produced for finite nonpunctual sources. In addition, the polychromaticity of the source affects the smoothness of the self-images, making them quasicontinuous from a certain distance from the grating forward. Finally, we experimentally validate the obtained analytical predictions. 2040-8978 10.1088/2040-8978/17/3/035601 https://hdl.handle.net/20.500.14352/35041 http://dx.doi.org/10.1088/2040-8978/17/3/035601 http://iopscience.iop.org/ Near field diffraction of cylindrical convex gratings