Long Wave Infrared Acousto-Optic Materials:Development of Novel Materials for the Fabrication of LWIR (8-12 micron)Acousto-optic Tunable Filters for I

In Phase I we developed novel anisotropic materials that can be used to fabricate acousto-optic tunable filter (AOTF)-based spectral imaging systems in the LWIR (8 to 12 micron) spectral region. This long wave infrared (LWIR) region technology is an essential part of achieving the goals set forth in the Army’s Third Generation Science and Technology Objective (STO). We investigated the mercurous halides (Hg2Cl2 and Hg2Br2) and tellurium (Te). Although all of these materials are suitable for LWIR AOTF operation, we will focus our Phase II work on Hg2Br2. The optical transparency range of Hg2Br2, 0.4 to 30 micron, extends even further than that of Hg2Cl2 (0.35 to 20 mm). Hg2Br2 is highly birefringent, has high refractive indices and an even lower acoustic attenuation compared to Hg2Cl2. A value of M2 for Hg2Br2 is about 3.7 times that of Hg2Cl2. Our objective of the Phase II project is to optimize the growth parameters of Hg2Br2, grow high quality crystals, and design fabricate an AOTF for operation in the 8 to 12 micron region. We will integrate the AOTF with high performance commercially available infrared imaging systems and demonstrate hyperspectral imaging in the 8 to 12 micron region with image processing capability. The high quality Hg2Br2 crystals along with the AOTF device will be delivered.