Monitoring of volatile organic components associated with waste disposal activities and gas pipeline leaks with a man-portable mid-infrared DIAL

LaSen, Inc. is continuing development of compact and rugged lidar systems for ground-based and airborne detection of volatile organic components (VOC) in the mid-infrared spectral region. The first-generation ground-based sensor (Lidar I) measures 0.19 m3 and weighs 55 kg. Throughout 2001, Lidar I is undergoing a series of field tests in south-central New Mexico, USA. The tests completed to date include measuring methane level at rural dumpsites and monitoring emissions from contaminated soil at a diesel fuel spill site. To support the lidar programs, LaSen developed a compact tunable mid-infrared laser source based on an intracavity optical parametric oscillator. The laser source delivers up to 1.3 mJ of mid-infrared energy per pulse and is angular tuned in the 3—5-µm band through a servo-controlled loop. A piezo-driven tuner for fast switching between “on ” and “off ” lines is available as an option. Lidar I performance characteristics relevant to detection of various VOC are discussed. The second-generation sensor (Lidar II) is undergoing development and is scheduled for tests in the fourth quarter of 2001. Lidar II is a re-packaged version of Lidar I, with a significant decrease in both weight and size. Although not specifically designed for an airborne platform, Lidar II will be capable of demonstration flights on board a helicopter operating in a look-down topographic mode