A computational tool for evaluating THz imaging performance in brownout or whiteout conditions at land sites throughout the world

Steven T. Fiorino; Richard J. Bartell; Matthew J. Krizo; Seth L. Marek; Matthew J. Bohn; Robb M. Randall; Salvatore J. Cusumano

doi:10.1117/12.818922

6 May 2009 A computational tool for evaluating THz imaging performance in brownout or whiteout conditions at land sites throughout the world

Steven T. Fiorino, Richard J. Bartell, Matthew J. Krizo, Seth L. Marek, Matthew J. Bohn, Robb M. Randall, Salvatore J. Cusumano

Author Affiliations +

Proceedings Volume 7324, Atmospheric Propagation VI; 732410 (2009) https://doi.org/10.1117/12.818922
Event: SPIE Defense, Security, and Sensing, 2009, Orlando, Florida, United States

Abstract

This study quantifies terahertz (THz) or sub-millimeter imaging performance during simulated rotary-wing brownout or whiteout environments based on geographic location and recent/current atmospheric weather conditions. The atmospheric conditions are defined through the Air Force Institute of Technology Center for Directed Energy (AFIT/CDE) Laser Environmental Effects Definition and Reference or LEEDR model. This model enables the creation of vertical profiles of temperature, pressure, water vapor content, optical turbulence, and atmospheric particulates and hydrometeors as they relate to line-by-line layer extinction coefficient magnitude at wavelengths from the UV to the RF. Optical properties and realistic particle size distributions for the brownout and whiteout particulates have been developed for and incorporated into LEEDR for this study. The expected imaging performance is assessed primarily at a wavelength of 454 μm (0.66 THz) in brownout conditions at selected geographically diverse land sites throughout the world. Seasonal and boundary layer variations (summer and winter) and time of day variations for a range of relative humidity percentile conditions are considered to determine optimum employment techniques to exploit or defeat the environmental conditions. Each atmospheric particulate/hydrometeor is evaluated based on its wavelength-dependent forward and off-axis scattering characteristics and absorption effects on the imaging environment. In addition to realistic vertical profiles of molecular and aerosol absorption and scattering, correlated optical turbulence profiles in probabilistic (percentile) format are used. Most evaluated scenarios are brownout environments over ranges up to 50 meters. At submillimeter wavelengths and the short ranges studied, preliminary results indicate the main source of image degradation in brownout conditions is water vapor content, even with visibility less than 10 m and strong optical turbulence.

Citation Download Citation

Steven T. Fiorino, Richard J. Bartell, Matthew J. Krizo, Seth L. Marek, Matthew J. Bohn, Robb M. Randall, and Salvatore J. Cusumano "A computational tool for evaluating THz imaging performance in brownout or whiteout conditions at land sites throughout the world", Proc. SPIE 7324, Atmospheric Propagation VI, 732410 (6 May 2009); https://doi.org/10.1117/12.818922

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available