A compact Ultraviolet Biological Trigger Lidar (UBTL) instrument for detection and discrimination of bio-warfare-agent (BWA) simulant aerosol clouds was developed by us [Prasad, et al, 2004] using a 5mW, 375nm semiconductor UV optical source (SUVOS) laser diode. It underwent successful field tests at Dugway Proving Ground and demonstrated measurement ranges of over 300m for elastic scattering and >100m for fluorescence. The UBTL was modified during mid-2004 to enhance its detection and discrimination performance with increased range of operation and sensitivity. The major optical modifications were: 1. increase in telescope collection aperture to 200 mm diameter: 2. addition of 266nm and 977nm laser transmitters: 3. addition of three detection channels for 266nm and 977nm elastic backscatter and fluorescence centered at 330nm. Also the commercial electronics of the original UBTL were replaced with a multi-channel field programmable gate array (FPGA) chip for laser diode modulation and data acquisition that allowed simultaneous and continuous operation of the UBTL sensor on all of its transmitter and receiver wavelengths. A notebook computer was added for data display and storage. Field tests were performed during July 2004 at the Edgewood Chemical and Biological Center in Maryland to establish the enhanced performance of UBTL subsystems. Results of these tests are presented and discussed.
A compact ultraviolet lidar stand-off sensor was recently developed and field-tested for detection of bio warfare (BW) agent stimulant aerosols and interferents. It employed a low-power (~5mW), continuous-wave, 375nm semiconductor ultraviolet optical source (SUVOS) laser diode that was modulated at high-speed with a pseudo-random (PR) code to provide range-resolved lidar detection of both aerosol elastic scattering and fluorescence. The sensor incorporated a 150mm diameter receiver telescope and 3 photon-counting detection channels centered at 375nm, 440nm, and 550nm. Aerosol elastic and fluorescence lidar profiles were obtained by correlating the signal photon-counts with the PR code. Tests of the lidar were performed first with simulants released in the Large Aerosol Chamber at Edgewood Chemical and Biological Center, MD at a lidar range of only 7.5m. The second phase of testing was done at Dugway Proving Ground, UT. Here the lidar was continuously scanned (± 13°) in a horizontal plane to detect downwind simulant and interferent aerosol disseminations at ranges of several hundred meters. Preliminary analyses of these tests show that the lidar detected fluorescence from the BW simulants at ranges up to 100m, and elastic scattering from aerosols up to 350m.
A suite consisting of an infrared sensor, optical sensors and a video camera are prepared for launch by a group of students at University of Virginia (UVA) and James Madison University (JMU). The sensors are a first step in the development of a Gas Filter Correlation Radiometer (GFCR) that will detect stratospheric methane (CH4) when flown on sub-orbital sounding rockets and/or from the hypersonic X-34 reusable launch vehicle. The current payload has a threefold purpose: (a) to provide space heritage to a thermoelectrically cooled mercury cadmium telluride sensor, (b) to demonstrate methods for correlating the IR reading of the sensor with ground topography, and (c) to flight test all the payload components that will become part of the sub- orbital methane GFCR sensor. Once completed the system will serve as host to other undergraduate research design projects that require space environment, microgravity, or remote sensing capabilities. The payload components have been received and tested, and the supporting structure has been designed and built. Data from previous rocket flights was used to analyze the environmental strains placed on the experiment and components. Payload components are being integrated and tested as a system to ensure functionality in the flight environment. This includes thermal testing for individual components, vibration testing from individual components and overall payload, and load testing of the external structure. Launch is scheduled for Spring 2001.
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