Holographic radar: A strategy for uneven surfaces

Holographic radar gives a useful image of sub-surface objects under favorable conditions. However when the surface has undulations of many millimeters, or is broken by stones, or elevated areas of harder material, then images are obtained which may well be a partial representation to the surface height, but may obscure the buried objects under investigation. If these are, for example, anti-personnel mines or Improvised Explosive Devices, the consequences could be serious. A simple possible solution is explored here: that is to cover the rough surface with a smoothed layer of appropriate sand. A simulated mine was buried at 40 mm depth in rough sand containing many hard sandstones, several breaking the surface by a centimeter or so. The image was full of detail correlating with the surface structure and largely obscuring the mine. A layer of sand from the same source was then covered over the rough surface and approximately smoothed by a straight edge. The simulated mine became clear.