Full-color multiplexed reflection hologram of diffusing objects recorded by using simultaneous exposure with different times in photopolymer Bayfol® HX

Abstract

An optimized wavelength multiplexing procedure for color reflection holograms of diffusing objects recorded in Bayfol® HX photopolymer is proposed. It is based on simultaneous initial illumination of all the wavelengths and sequential shuttering down of the laser beams involved. Three lasers of 442 nm, 532 nm and 633 nm were selected, as a tradeoff solution between setup complexity and color reproduction accuracy. The obtained results prove that the presented method improves the simultaneous and sequential exposure methods by increasing the mean efficiency and reducing the standard deviation (increasing uniformity) of the involved wavelengths. For a Spectralon® diffusing object, the assessed method reports a mean efficiency of 25.0% with a standard deviation of 2.9%, while simultaneous and sequential iterative exposures result in mean efficiencies of 12.1% and 20.6% with standard deviations of 3.4% and 5.4%, respectively.

The authors would like to thank Covestro Deutschland AG for supplying the recording photopolymer material. This research has been supported by the “Diputación General de Aragón-Fondo Social Europeo” (TOL research group, E44_17R), the “Generalitat de Catalunya” (2017FI_B2_00127 and 2017 SGR 1276) and the "Ministerio de Ciencia e Innovación" (PID2019-108598GB-I00). Daniel Chemisana thanks ICREA for the ICREA Academia award.