Suppression of the Zero-Order Diffraction Beam from Computer-Generated Holograms produced by a DLP® Spatial Light Modulator

We present a new optical technique to suppress the unwanted zero-order diffraction (ZOD) in holograms produced by the digital micromirror device (DMD). The proposed optical architecture consists of two light beams illuminating the DMD in an interferometer configuration. The two beams are incident from different angles, +24 degrees and -24 degrees, in order to utilize light diffracted from all the pixels to produce a binary Fresnel hologram. The relation between these two beams diffracting from the DMD was found to be complementary, and they both generated the same reconstructed image pattern. With pi phase difference between the two beams, the diffracted beams had their ZOD components out of phase while the reconstructed holograms were identical and in phase. Experiments were conducted to demonstrate ZOD suppression by destructive interference and simultaneous hologram enhancement by constructive interference. The method was shown to suppress the ZOD by a factor of 2.9 in a Fresnel hologram.