Electro-optic polymer liquid crystal thin films for hyperspectral imaging

The authors present a study focused on the feasibility of using holographic polymer dispersed liquid crystal wavelength filters for hyperspectral imaging (HSI). For this study, stacks of these filters were fabricated in the visible wavelength range of 600 to 800 nm. These filters were demonstrated to have a number of properties useful for HSI applications, including uniform reflection efficiency of 80% across a 35 mm optical aperture, polarization insensitivity for normal incidence, spectral resolution of 10 nm, and fast switching times on the order of microseconds. In addition, the ability to modulate each filter in the stack at a different frequency allows for spectral multiplexing, thus enabling synchronous detection and demodulation of the image data. Although the filters in their current state show promise for HSI applications, techniques to further improve performance in terms of viewing angle range and transmission throughput are presented. Finally, a system level integration of such a stack into the prototype drive and detection unit is discussed.