Electronic devices for seeing in very dim light have become commonplace, but all of them are blind in total darkness. Last week Baird Associates. Inc. of Cambridge, Mass, showed a recently declassified "camera" that needs no light at all, only infra-red (heat) radiation from faintly warm objects.
Baird's Evaporograph (Eva for short) is based on a prewar German idea which until recently was not followed up diligently. It has a concave mirror which concentrates heat rays as the mirror of an astronomical telescope concentrates light.
Just before they come to a focus, the rays...
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