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"Optical remote sensing in a turbulent atmosphere," colloquium April 15, 2011

Dan Slater, Nearfield Systems

Finding, identifying and characterizing distant terrestrial objects with ground based electro-optical sensors presents several difficult technical challenges. The entire optical path is fully immersed in a dense and turbulent atmosphere which results in a significant loss of scene contrast and resolution. Although there are strong similarities to the problems of ground based high resolution astronomical and space object imaging, there are also significant differences. The first part of the presentation discusses the problem of high resolution terrestrial imaging through a turbulent scattering atmosphere. Several ground based optical instruments specifically designed for long range remote sensing will be described including MIST (Miniature Integrated Speckle imaging Telescope) and TFIC (Terrestrial Fusion Imaging Camera). MIST supports a variety of imaging and non imaging experiments. TFIC is a portable high resolution camera that also includes wideband radiometric capabilities. The TFIC image processing workflow, using a combination of luminance processing, speckle imaging and image fusion is described. Representative high resolution urban and marine environment imagery with horizontal path distances up to 128 km (80 miles) is shown.

The second part of the presentation discusses long range electro-optical sensing using non cooperative specular sensing probes. Solar illuminated glinting objects can serve as in situ sensor probes that are observable from very long distances. Retro reflective objects produce glints when illuminated by coaxial illumination sources such as lasers. These glints are modulated by illumination source variances, the local probe environment, the intervening propagation paths and the remote sensing receiver. The modulating signals can be recovered by using detectors with temporal, spatial, wavelength, directivity or polarization sensitivity. Spatial glint correlation and glint beam forming using clustered and moving specular probes can provide additional information.

Keywords: high resolution imaging, remote sensing, atmospheric turbulence, glints, retroreflectors

About the speaker:

Dan Slater is vice president, co founder and head of research and development for Nearfield Systems Inc. (NSI). Previously he was a long term consultant to TRW (now Northrop Grumman), Paramount Pictures and others. He has consulted on a variety of projects including spacecraft antenna measurements, launch vehicle avionics, flight simulation, imaging radar design, photo instrumentation and motion picture special effects. He has designed numerous aerospace, underwater and motion picture optical systems and lenses. He has received two Academy Awards for motion picture camera technology developments and holds 14 US patents. He is the author of the technical book "Nearfield Antenna Measurements" (Artech House 1991) and numerous technical papers. He is a senior member of the American Institute of Aeronautics and Astronautics, the Institute of Electrical and Electronics Engineers (IEEE) and the Antenna Measurement Techniques Association (AMTA)