In a previously reported holographic code for the synthesis of arbitrary complex fields with phase-only modulators, the amplitude is encoded by scaling the phase modulation. For the appropriate performance of this code, it is necessary to employ an ideal phase modulator, which can not be easily obtained with a standard liquid-crystal device. We generalize and improve the above holographic code in such a way that the desired complex function can be obtained by using the restricted phase-mostly modulation provided by a twisted-nematic liquid-crystal display, in a simple setup employing two polarizers and a He-Ne laser. A commercial liquid-crystal device employed in this setup only provides a phase modulation in a range smaller than 1.5π radians, coupled with an amplitude modulation with a significant variance. In spite of these restrictions, the quality of complex signals encoded with the modified holographic code is only affected by a marginal efficiency reduction. We present numerical simulations and experimental results regarding our proposal.

Date Published: 10 September 2005
PDF: 8 pages
Proc. SPIE 5908, Optical Information Systems III, 59080I (10 September 2005); doi: 10.1117/12.617993

Published in SPIE Proceedings Vol. 5908:
Optical Information Systems III
Bahram Javidi; Demetri Psaltis, Editor(s)