Artificial illumination for radiometry in shortrange ground applications

In this report we study the use of artificial illumination in short-range radiometry ground applications. It includes a short introduction to radiometry and simple approximate calculations to illustrate natural scene contrasts in- and outdoors. We study the power requirement when illuminating a rough surface and when illuminating a plane surface or a corner reflector. We point out the potential benefits of multistatic arrangements and the use of an extended surface illuminating the target scene. These benefits regard the reduction of "speckle", the possibility to detect plane surfaces and the possibility to perceive the form of the target. We conclude that the power requirement regarding artificial illumination in the cases studied to be below 10 mW. We also conclude that the speckle phenomenon is an important problem when using artificial illumination and that the reduction of speckle calls for several sources illuminating the target scene from several directions and in addition also the use of a broad bandwidth will contribute.