The DigiLens™ ASIL device is a laminate of multiple holographic elements encapsulated in a hermetically sealed opto-electronics package. The device is customized both in size and optical function for every customer and so is unique in its application-specific role.
Each Holographic Optical Element (HOE), or layer, is based on the revolutionary properties of a new class of Electrically Switchable Polymer Dispersed Liquid Crystal material. The HOE is basically a Brag hologram, where during recording, the PDLC undergoes a phase separation, creating regions densely populated by liquid crystal micro-droplets, interspersed by regions of clear photopolymer.
When an electric field is applied to the hologram via a pair of ITO electrodes, the natural orientation of the LC droplets is changed, causing the refractive index modulation of the fringes to reduce and the hologram diffraction efficiency to drop to very low levels, effectively erasing the hologram. The resulting phase volume hologram exhibits very high diffraction efficiencies and fast switching times.
Color imaging, for example, is achieved by designing the ASIL as a stack of red, green and blue sensitive lens layers, which are switched in sequence with the red, green and blue illumination sources. This essentially creates three separate monochromatic optical channels, simplifying the problem of color correction.