Polymer-dispersed liquid crystals (PDLCs) have been developed for modulation of infrared radiation in the 2-5 and 8-14 micrometers wavelength regions. The electro-optic performance of an IR PDLC shutter depends on film thickness, liquid crystal droplet size, and the transparency of the substrates and the PDLC components. The effect of each of these factors on IR electro-optic performance of PDLC films was investigated using double modulation experiments and infrared spectroscopy. The authors have also compared the sensitivity of a pyroelectric vidicon infrared camera using PDLC shutter and a mechanical shutter.