<title>WILDCAT chemical sensor development</title>

Abstract

The WILDCAT sensor was developed to provide chemical detection and identification at large standoff ranges on the order of 20 km for concentration-path length product measurements and 5 km for range-resolved measurements. The transmitter is a wavelength agile CO₂ laser with output energy of 1 J/pulse at a repetition rate of 100 Hz. The laser wavelength can be shifted by a two-stage second harmonic generator and optical parametric oscillator to prove chemical absorption features outside the normal laser emission bands. The receiver is composed of a 60 cm dia. Cassegrain telescope and two-element HgCdTe detector that are integrated into a gimbal system for full hemispherical scanning. The laser/optical table and gimbal/telescope subsystems are connected by a rigid truss and all components are integrated into a transportable field test station. The data acquisition system is composed of 12 bit, 125 MHz analog-digital converters and a digital signal processor. Algorithms allow for real-time data processing and display of chemical concentration maps. All key transmitter and receiver components are capable of further development for compact, standalone sensors that can operate from fixed sites or mobile platforms, including aircraft, ships, and ground vehicles.