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Programmable CGH on photochromic material using DMD generated masks
Author(s): Romain Alata; Frédéric Zamkotsian; Patrick Lanzoni; Giorgio Pariani; Andrea Bianco; Chiara Bertarelli
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Paper Abstract

Computer Generated Holograms (CGHs) are used for wavefront shaping and complex optics testing, including aspherical and free-form optics. Today, CGHs are recorded directly with a laser or intermediate masks, allowing only the realization of binary CGHs; they are efficient but can reconstruct only pixilated images. We propose a Digital Micromirror Device (DMD) as a reconfigurable mask, to record rewritable binary and grayscale CGHs on a photochromic plate. The DMD is composed of 2048x1080 individually controllable micro-mirrors, with a pitch of 13.68 μm. This is a real-time reconfigurable mask, perfect for recording CGHs. The photochromic plate is opaque at rest and becomes transparent when it is illuminated with visible light of suitable wavelength. We have successfully recorded the very first amplitude grayscale CGH, in equally spaced levels, so called stepped CGH. We recorded up to 1000x1000 pixels CGHs with a contrast greater than 50, using Fresnel as well as Fourier coding scheme. Fresnel’s CGH are obtained by calculating the inverse Fresnel transform of the original image at a given focus, ranging from 50cm to 2m. The reconstruction of the recorded images with a 632.8nm He-Ne laser beam leads to images with a high fidelity in shape, intensity, size and location. These results reveal the high potential of this method for generating programmable/rewritable grayscale CGHs, which combine DMDs and photochromic substrates.

Paper Details

Date Published: 22 February 2018
PDF: 14 pages
Proc. SPIE 10546, Emerging Digital Micromirror Device Based Systems and Applications X, 1054606 (22 February 2018); doi: 10.1117/12.2292075
Show Author Affiliations
Romain Alata, Lab. d'Astrophysique de Marseille, CNRS (France)
Aix Marseille Univ. (France)
Frédéric Zamkotsian, Lab. d'Astrophysique de Marseille, CNRS (France)
Aix Marseille Univ. (France)
Patrick Lanzoni, Lab. d'Astrophysique de Marseille, CNRS (France)
Aix Marseille Univ. (France)
Giorgio Pariani, INAF - Osservatorio Astronomico di Brera (Italy)
Andrea Bianco, INAF - Osservatorio Astronomico di Brera (Italy)
Chiara Bertarelli, Politecnico di Milano (Italy)


Published in SPIE Proceedings Vol. 10546:
Emerging Digital Micromirror Device Based Systems and Applications X
Michael R. Douglass; Benjamin L. Lee, Editor(s)

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