RL Associates Inc. has designed a novel 12-channel, multi-spectral beam splitter which covers the visible
region of the spectrum. Commonly-used beam splitting techniques include dichroic mirrors, spectral
bandpass filters, ruled diffraction gratings, and prisms, all of which are large and difficult to handle. The
RL Associates' beam splitter, developed for the US Navy's multi-spectral imaging programs, uses
multiplexed volume holographic gratings. A volume holographic optical splitter offers multi-channel
splitting in a single element which can be customized to accommodate a broad range of sensor array
geometries. The RL Associates beam splitter has an efficiency of 75% or greater, and an angular
acceptance of up to 25 degrees. These gratings are written in a thermally stable photosensitive glass.
Currently, a 12-channel beam splitter has been developed by multiplexing three volume holograms in a 2x2
array with each element being offset by approximately 35 nm. The output of each element is then directed
toward a separate imaging detector. Each detector is placed at a specific, unique position relative to the
other detectors. This ensures that no cross talk occurs between beam splitting elements. A prototype beam
splitter is currently under development. This beam splitter will extend into the short-wave infrared region
while still working in the visible region.