Dale A. Richter

Advanced Airborne UV DIAL System for Stratospheric and Tropospheric Ozone and Aerosol Measurements

An advanced UV DIAL system for airborne measurements of ozone and aerosol distributions across the troposphere and lower stratosphere was developed at the NASA Langley Research Center during 1995. This paper describes the system and its improved performance including examples from the recent TOTE/VOTE field campaign.

Design validation of an eye-safe scanning aerosol lidar with the Center for Lidar and Atmospheric Sciences Students (CLASS) at Hampton University

ITTs Advanced Engineering and Sciences Division and the Hampton University Center for Lidar and Atmospheric Sciences Students (CLASS) team have worked closely to design, fabricate and test an eye-safe, scanning aerosol-lidar system that can be safely deployed and used by students form a variety of disciplines. CLASS is a 5-year undergraduate- research training program funded by NASA to provide hands-on atmospheric-science and lidar-technology education. The system is based on a 1.5 micron, 125 mJ, 20 Hz eye-safe optical parametric oscillator (OPO) and will be used by the HU researchers and students to evaluate the biological impact of aerosols, clouds, and pollution a variety of systems issues. The system design tasks we addressed include the development of software to calculate eye-safety levels and to model lidar performance, implementation of eye-safety features in the lidar transmitter, optimization of the receiver using optical ray tracing software, evaluation of detectors and amplifiers in the near RI, test of OPO and receiver technology, development of hardware and software for laser and scanner control and video display of the scan region.

Laser interrogation of surface agents (LISA) for chemical agent reconnaissance

Laser Interrogation of Surface Agents (LISA) is a new technique which exploits Raman scattering to provide standoff detection and identification of surface-deposited chemical agents. ITT Industries, Advanced Engineering and Sciences Division is developing the LISA technology under a cost-sharing arrangement with the US Army Soldier and Biological Chemical Command for incorporation on the Armys future reconnaissance vehicles. A field-engineered prototype LISA-Recon system is being designed to demonstrate on-the- move measurements of chemical contaminants. In this article, we will describe the LISA technique, data form proof-of- concept measurements, the LISA-Recon design, and some of the future realizations envisioned for military sensing applications.

A compact ozone DIAL system

An eye-safe, ground-based differential absorption lidar for ozone measurements is currently being tested. Its novel features include an all-solid state OPO transmitter, a dual channel grating-based receiver and a fast membrane mirror light shutter.

Compact ground-based UV DIAL system for measurements of tropospheric ozone

The development of a portable, eye-safe, ground-based ozone lidar instrument specialized for ozone differential absorption lidar (DIAL) measurements in the troposphere is presented. This compact prototype instrument is intended to operate at remote field sites and to serve as the basic unit for future monitoring projects requiring multi-instrument networks. In order for the lidar technology to be widely deployed in networks, it must be fairly easy to use and maintain as well as being cost-competitive with a ground station launching ozone sondes several times a week. The chosen laser transmitter for the system is an all-solid state tunable frequency-doubled OPO which produces 25 mJ uv pulses. Progress with alternative solid-state uv laser sources based upon an IR-pumped OPO and based upon stimulated Raman scattering in barium nitrate will be discussed. The receiver incorporates highly efficient dielectric coatings, a parabolic primary and a narrow- bandpass grating-based filter. Dual analog and photon-counting detector channels are incorporated to extend the measurement range. All data acquisition and control hardware is incorporated in an industrial PC-based system. A flexible, user-friendly graphical user interface is written in LabVIEW for data acquisition and online processing and display.

Performance characterization and ground testing of an airborne CO2 differential absorption lidar system (phase II)

The Phillips Laboratory Remote Optical Sensors (ROS) program is developing the Laser Airborne Remote Sensing (LARS) system for chemical detection using the differential absorption lidar (DIAL) technique. The system is based upon a high-power CO2 laser which can use either the standard 12C16O2 or the 13C16O2 carbon dioxide isotopes as the lasing medium, and has output energies in excess of 4 J on the stronger laser transitions. The laser, transmitter optics, receiver telescope and optics, and monitoring equipment are mounted on a flight-qualified optical breadboard designed to mount in the Argus C-135E optical testbed aircraft operated by Phillips Laboratory. The LARS system is being prepared for initial flight experiments at Kirtland AFB, NM, in August 1997, and for chemical detection flight experiments at the Idaho National Engineering Laboratory (INEL) in September 1997. This paper briefly describes the system characterization, and presents some results from the pre- flight ground testing.

Measurements of tropospheric ozone with a compact UV DIAL system

Current results from laboratory testing of an eye-safe, ground-based ozone lidar instrument specialized for ozone differential absorption lidar measurements in the troposphere are presented. This compact prototype instrument is intended to be a prototype for operation at remote field sites and to serve as the basic unit for future monitoring projects requiring multi-instrument networks. In order for the lidar to be widely deployed, it must be fairly easy to use and maintain as well as being cost-competitive with a ground station launching ozone sondes several times a week. To achieve these goals, the system incorporates (1) an all- solid state compact OPO transmitter, (2) a highly efficient, narrow bandpass grating-based receiver, (3) dual analog and photon-counting detector channels, and (4) a PC-based data acquisition system.

Development and testing of a long-range airborne CO2 DIAL chemical detection system

The Air Force Research Laboratory has developed and tested an airborne CO2 differential absorption lidar system for the remote detection of chemicals. The Laser Airborne Remote Sensing DIAL system uses topographic backscatter to provide a long-range measurement of the column-content absorption of chemical plumes in the path of the laser beam. A high-power CO2 laser, capable of operation on multiple isotopes, and a Mersenne telescope constitute the major transceiver components. In addition to the laser, telescope, and transceiver optics, several onboard diagnostic instruments were mounted on the flight bench to monitor and optimize the system performance during airborne operation. The flight bench, electronics racks, and data acquisition and experiment control stations were designed to be integrated onto the AFRL C-135E research aircraft, and to utilize the existing pointing and tracking system on the aircraft.

Optical design of Hampton University Lidar Systems

The Zemax® optical design program is being used to develop the Hampton University ozone and aerosol lidar systems. A macro developed for use within the Zemax® program enables the design to be optimized.

The Hampton University Center for Lidar and Atmospheric Sciences Students

A portable, eyesafe, 125 mJ, 20Hz, 1.5 micron scanning aerosol lidar is currently being tested by students and faculty in the Center for Lidar and Atmospheric Sciences in conjunction with ITT and NASA.