Means for near real time C-W laser source characterization

A system for locating the source of radiation incident on said system, comprising:

• optical means for presenting two images of the field-of-view of said system:
• detecting means optically cooperating with said optical means for providing an electrical output indicative of each image;
• two optical modulation filters having finite lengths and attenuation factors, each filter movable across one of said images for occupying a portion of the optical path between the image and said detection means and wherein the attenuation factor of the filter moving across one of said images is invariant in a direction perpendicular to its movement, and the attenuation factor of the filter moving across the other image varies linearly in a direction perpendicular to its movement;
• circuit means electrically connected to said detection means for comparing the amplitudes of the outputs said detecting means associated with each of said images with one another;
• and
• means for sensing the position of at least one of said plurality of optical filters and providing an electrical analog of said position at the time of the comparison performed by said circuit means, whereby said position corresponds to the point of origin of said radiation within said field-of-view in at least one dimension.