High Speed and Low-Noise Open-Path Gas Detection System

Emissions and leaks of toxic and hazardous chemicals have serious consequences to the general public and the environment. In particular, development of sensors that can continuously monitor trace chemicals associated with the handling and processing of nuclear materials will lead to timely detection of accidental leaks or prohibited clandestine activities. By extending the remote sensing range, measurements can be made at a safe distance and a large area can be effectively surveyed with one sensor. We propose a multispecies gas sensor that can operate in long-range open path configuration based on Pendar’s proprietary quantum cascade laser (QCL) array technology. The sensor is capable of broadband high-resolution spectral measurements in the mid-infrared, which allows sensitive and selective detection of a multitude of chemical species. The system performs spectral measurements at a speed of a few microseconds to milliseconds, which allows timely interception of moving plumes or rapidly evolving emission sources. During Phase I, we confirmed the feasibility of a QCL array-based open-path spectrometer for kilometer- range sensing. The Phase I breadboard prototype demonstrated sensing in the spectral region of 930 cm- 1-1500 cm-1 with a frequency resolution of <0.05 cm-1. Outdoor remote sensing was performed using a retroreflector with over 250-meter optical pathlength. Phase II work will focus on improving sensor stability, extending the sensing range to 1 km pathlength, and delivering a compact and fully packaged prototype that is field deployable. With Pendar’s expertise in portable sensing system development, continuing funding (sequential Phase II or Phase III) will lead to further ruggedization and improvement of the mechanical and opto-mechanical design, miniaturization of electronics, and ultimately system production and commercialization. We believe the proposed system is a versatile instrument that can be applied to applications ranging from monitoring emissions in oil refineries and processing plants to trace explosive detection.