Enhanced Capability Point Combined Bio and Chem Sensor

Many chemical agents have unique absorption spectra in the 9-to-11μm wavelength range, and sufficient absorption cross sections for detection at trace concentration levels. In this proposal, a short standoff range LWIR DISC LIDAR will be developed, providing comprehensive chemical and biological standoff detection, as well as MWIR detection of industrial chemicals. The LIDAR is based on a 1 mm diameter electron-initiated avalanche photodiode (eAPD) with an approximate 5 MHz bandwidth. The advantage of an eAPD over a conventional photodiode is that a narrowband filter can be used to reduce background to the level of the amplifier. The HgCdTe eAPD, with its noiseless gain, provides the opportunity to operate at high frequencies and over a wide spectral range, with greater sensitivity than a system based on a photodiode alone. HgCdTe APDs operate at low voltage, and have shown to have excellent uniformity and good yields. Exponential-gain values well in excess of 1,000 have been obtained in HgCdTe APDs with essentially zero avalanche-induced noise. In Phase I, we will design an HgCdTe APD based DISC LIDAR system, demonstrate infrared HgCdTe APD performance, and demonstrate the technologies necessary for a Phase II system development and demonstration program.