Color Images with the MIT Holographic Video Display
Pierre St-Hilaire, Stephen A. Benton, Mark Lucente, Paul M. Hubel
Spatial Imaging Group
MIT Media Laboratory
Cambridge, MA
The MIT holographic video display can be converted to color by
illuminating the 3 acoustic channels of the acousto-optic modulator
AOM with laser light corresponding to the red, green, and blue parts
of the visible spectrum. The wavelengths selected are 633 nm (red),
532 nm (green), and 442 nm (blue). Since the AOM is operated in the
Bragg regime, each wavelength is diffracted over a different angular
range, resulting in a final image in which the three color primaries
do not overlap. This situation can be corrected by shifting the
diffracted spatial frequencies with a holographic optical element
(HOE). This HOE consisting of a single grating is placed right after
the AOM in the optical setup. Calculation of the required spatial
frequency for the HOE must take into account the optical activity of
the TeO2 crystal used in the AOM. The HOE introduces distortions in
the final image, but these are so small as to be visually negligible.
The final images are of a good quality and exhibit excellent color
registration. The horizontal view zone, however, diminishes for the
shorter wavelengths.
Published as:
P. St.-Hilaire, S.A. Benton, M. Lucente, and P.M. Hubel, Color images
with the MIT holographic video display," in: S.A. Benton, ed.,
SPIE Vol. 1667, Practical Holography VI (Feb., 1992), paper 1667-73,
pp. 73-84.
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