The photon counting detectors can be used in Missile countermeasure with significantly improved sensitivity and reliability. A spectrometer based on these detectors can be used for making spectroscopic studies of molecules in the range of 1-11 microns. It can be also used to detect trace amounts of the molecular species for the applications in chemical sensing and detections of biological and chemical agents. It can be used as a tool for biomedical diagnostics for important applications such as glucose detection. The new LIDAR system to be developed by PI by combining the photon counting detectors and a laser has important applications in archaeology, meteorology and atmospheric environment, wind power, geology, physics and astronomy, biology and conservation, military and law enforcement, vehicles, imaging, and 3-D mapping. Since it can reach single photon sensitivity around 1550 nm, it is not only eye-safe but also important for military applications in night vision goggles. The photon counting detectors implemented by PI during Phase 2 will meet the requirement of NASA as being defined by the NASA SBIR solicitation of TOPIC: S1 Sensors, Detectors, and Instruments. Specifically, these detectors will be used to achieve single photon sensitivity in the wavelength ranges of near-IR (1-1.8 microns ) and mid-IR (3-4 microns ). In comparison, InGaAs/InP avalanche photodiodes are incapable of reaching single photon sensitivity within the two spectral ranges. 3-D imaging systems by combining the photon counting detectors and a laser can be used to realize coherent imaging LIDAR for the ASCENDS, DESDynI, LISA, Doppler Wind Lidar, and LIST mission programs. Such 3-D imaging can be achieved by both a staring single-element photon counting detector and an array of these detectors. The energy sources of nine infrared luminous galaxies can be diagnosed by a ground-based 3-4 ¬µm spectrometer to be developed by PI based on the photon-counting detectors.