Compact Photo-Acoustic Chemical Sensor

摘要

The present security environment has created a need for robust, sensitive, portable gas-phase chemical sensors. The ready availability of high performance quantum cascade lasers, which can operate at ambient temperatures with only thermoelectric cooling, has made the possibility of such sensors quite realistic. A compact, sensitive, cost-effective photo-acoustic sensor capable of sub-part-per-million sensitivity is described. The sensor can be entirely self-contained in a small volume weighing only a few pounds. The quantum cascade laser is enclosed in a sealed package incorporating a collimating lens and thermoelectric cooler. The package sits on an external thermoelectric cooler. Both the laser and thermoelectric coolers are driven by a self-contained power supply and controller specifically designed for the purpose. The photo-acoustic gas cell contains input and output ports and anti-reflection coated optical windows. Details of the sensor's configuration and performance will be described as it relates to explosive detection using thermal fragmentation.