Chemical vapor detection using a passive infrared bioinspired sensor

Standoff detection of chemicals remains a crucial need for a variety of applications of importance for defense, homeland security, environmental, and industrial applications. The goal of standoff chemical sensing is to enable the identification and classification of an unknown hazardous or toxic chemical, without any operator or instrument having to come in direct contact with the chemical itself. Currently, standoff detection of chemical vapors is carried out using optical sensing techniques. Passive infrared (IR) sensors have identified chemical vapor clouds at ranges exceeding one kilometer by detecting, spectrally resolving, and analyzing scene radiance. Currently available passive IR sensors have substantial size, weight, power, and cost (SWaP-C) limitations, which reduce the number of sensors capable of being deployed in a given area, or precludes their use altogether in certain circumstances. To address these limitations, we are developing a unique passive low SWaP-C IR sensor capable of detecting chemical vapors when viewed against a cold-sky or terrestrial background. This sensor, inspired by human color vision, will use only the response through three broadband infrared optical filters to discriminate between target chemicals and background interferents. The key technology of the PBS is a commercially available pyroelectric quadrant chip sensor which contains four channels with unique bandpass IR filters installed. We demonstrate results collected using a variable temperature blackbody in the laboratory, which represents passive IR sensing against various background conditions. These results demonstrate the first step in the development of a passive bioinspired IR sensor which will use only low-cost commercially available components, and be capable of rapidly providing actionable detection of chemical vapor clouds.