Refraction and Long-Range FLIR Images

  • A. J. Beaulieu


With the advent of focal plane arrays, ER sensors are increasingly being used for long-range applications with increased resolution to allow object identification. For sea applications the detection of near surface objects is often limited by the horizon and substantial image distortions due to atmospheric refraction are encountered. In some cases, targets can be detected well beyond the geometrical horizon limit while under different conditions, the horizon limit can be much smaller than the geometrical value and mirages can occur. For the prediction of the performance of the IR sensors, it is essential to take these effects into account. Ship-borne IR sensors to detect near sea-level targets, such as ships or low-altitude aircraft, are particularly sensitive to the refraction phenomena. This is why accurate models have been developed to cover the Marine Boundary Layer (MBL) which is the atmospheric layer immediately above the water surface. The predictions of these models are so significant that a sea-shore measurement program was undertaken to verify the validity of the models and to give a higher degree of confidence in its application to a variety of weather scenarios. The present report summarizes the model development, its experimental validation and the system implications of the effects of refraction.


Image Distortion Focal Plane Array Marine Boundary Layer Refraction Condition Horizon Limit 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Walmsley, J. L., “On theoretical wind speed and temperature profiles over the sea with applications to data from Sable Island, Nova Scotia”, Atmosphere-Ocean 26 (2), pp. 203–233. (1988)CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1995

Authors and Affiliations

  • A. J. Beaulieu
    • 1
  1. 1.BCI Co.Ste-FoyCanada

Personalised recommendations