Frequency Agile LIDAR Receiver for Chem-Bio Sensing

Physical Sciences Inc. proposes to develop an ultra low noise receiver module for direct detection LWIR LIDAR systems. The proposed receiver concept is compatible with emerging LWIR source technologies, e.g., optical parametric amplifier-based sources, as well as existing frequency-agile CO2 laser technology. The optical system will incorporate a rapidly-tunable Fabry-Perot interferometer (etalon) to reduce the baseline flux on the detector and thereby reduce the background-limited photon statistical (BLIP) noise associated with backscatter measurements. The tunable etalon’s transmission will track the emission wavelength of the LIDAR transmitter. Development of a low-noise amplifier matched to the receiver detector is required in order to realize the BLIP noise reduction resulting from the etalon. Model calculations indicate that the NEP of the proposed receiver will be 4x less than what can be achieved using a conventional optical design and a commercially-available detector and amplifier. Model calculations further indicate that this reduction in system NEP can extend maximum standoff range by up to a factor of 2 or improve detection limits for chemical vapors or aerosol particles by up to a factor of 4.