The present invention pertains to radiant energy systems and more particularly to systems exhibiting the retroreflection principle wherein the system comprises a focusing means and a surface exhibiting some degree of reflectivity positioned near the focal plane of the device, and wherein incident radiation falling within the field-of-view of said system is reflected back in a direction which is parallel to the incident radiation. The present invention has great applicability in military optical system applications for detecting the presence of an enemy employing surveillance equipment and for neutralizing this surveillance capability.