Standoff handheld real-time early warning detector (SHREWD)

A lightweight, compact sensor breadboard demonstrator is being developed that will be capable of detecting chemical agents in the 8 - 12 micrometers band by DIAL for ranges on the order of 4 km. Engineering analysis shows that the overall sensor size and weight would be approximately 1 cu. ft. and 35 lbs., respectively. The sensor is composed of a 12.5 cm diameter, off-axis paraboloid receive telescope and a 300 Hz repetition rate solid-state laser transmitter. The transmitter is based on a diode-pumped, 1.06 micrometers laser with an output energy of 20 mJ and two cascaded OPO stages that shift the laser wavelength to the far IR bands. The first stage OPO is configured in an arrangement that shifts the laser output to beyond 2 micrometers . The second stage OPO completes the shift to the 8 - 12 micrometers band, giving an overall 1.06 (mu) $m yields 8 - 12 micrometers conversion efficiency of 2% and a sensor output power of 0.1 W.