Remote Sensing by Active and Passive Optical Techniques
Document ID: 131
Philbrick, C. Russell
O'Brien, Michael D.
Lysak, Jr., Daniel B.
Stevens, Timothy D.
Balsiger, Franz
The Pennsylvania State University, Communications and Space Sciences Laboratory, University Park, PA, U.S.A.
Presented: AGARD SPP Symposium on "Remote Sensing: A Valuable Source of Information" AGARD-CP-582
Toulouse, France, 22-25 April, 1996.
Summary
Active optical remote sensing techniques based on lidar have been mostly limited to ground based and aircraft applications because of rather restrictive l/R2 dependence of signal, low power efficiency ( ~1 % ) of flash lamp pumped lasers and large physical size required by the power system. The advances in diode pumped lasers and other electro-optical instruments make it possible to consider new possibilities. Opportunities for future aircraft, RPV and satellite platform measurements over large spatial scales have prompted us to evaluate current capabilities for ground-based lidar measurements with a view toward future compact lidars. We have examined the Raman and DIAL lidar techniques to determine their capability for various remote sensing applications. The Raman techniques, even with inherent sensitivity disadvantages of small scattering cross-sections, have proven to be highly successful for ground-based remote sensing because they easily provide quantitative results, and these techniques will still be valuable from aircraft altitudes. Examples of ground-based lidar measurements of structure properties and minor species profiles have been used to provide confidence in the model calculations of expected performance from flight platforms. Use of acousto-optical tunable filters (AOTF) with lidar techniques provide special capabilities for measurement of Raman and fluorescent lidar returns. Applications of SPR-DIAL techniques for high altitude platforms would be useful for detection of chemical pollution in the atmosphere and waterways. Capabilities of current ground-based lidar systems for profiling meteorological properties, such as: density, temperature, water vapor, refractivity, chemical species, aerosol extinction and particle characteristics, provide the base from which we may consider future applications. Our recent reports have described the capability of lidars to measure species and temperature profiles, this paper focuses on the ability of lidar to measure and quantify aerosol properties.