Optimizing performance parameters for switchable polymer dispersed liquid crystal optical elements
View Patent ↗Described herein are the materials, mechanisms and procedures for optimizing various performance parameters of HPDLC optical devices in order to meet differing performance requirements. These optimization tailoring techniques include control and independent optimization of switchable HPDLC optical devices to meet the demanding requirements of anticipated applications for, inter alia, the telecommunications and display industries. These techniques include optimization of diffraction efficiency, i.e., index modulation, polarization dependence control, haze, cosmetic quality, control of response and relaxation time, voltage driving for on and off switching, and material uniformity. This control and independent optimization tailors properties of switchable HPDLC optical devices according to the specific requirements of the application of the switchable HPDLC optical device. The invention disclosed herein retains the desirable attributes of the multi-functional acrylate system for forming HPDLC optical devices, but adds new materials to the acrylate system and/or new process control to the recording to optimize performance parameters as may be needed for specific applications. This results in high optical quality switchable holograms with good diffraction efficiency and low, stable switching voltage.
1. A system for controlling the index modulation of a switchable polymer dispersed liquid crystal optical element comprising:
a first substrate and a second substrate with a pre-polymer liquid crystal material therebetween; and
a first electrode pattern on the first substrate and a second electrode pattern on the second substrates, the first electrode pattern and second electrode pattern adapted to apply a switching voltage to the switchable polymer dispersed liquid crystal optical element, wherein at least one of the first and second electrode patterns consists of interdigitated electrodes having a voltage approximately equal to the switching voltage applied to only every other interdigated electrode.
2. The system according to claim 1 , wherein both of the first and second electrode patterns consist of interdigitated electrodes; and further wherein, the interdigitated electrodes of the first electrode pattern are staggered with respect to the interdigitated electrodes of the second electrode pattern.
3. The system according to claim 1 , wherein at least one of the first and second electrode patterns is a solid planar pattern.
4. The system according to claim 1 , wherein each of the interdigitated electrodes has a height (h) and each of the interdigitated electrodes are separated by a separation (b), wherein each of (h) and (b) are approximately equal to the width of the polymer dispersed liquid crystal optical material.
5. The system according to claim 1 , wherein the first electrode pattern is transparent.