Only a tenth the size of a bee's eye, as seen in the accompanying photo, the tiny dark lens in the center of the white disk is believed to be the world's smallest germanium‐immersed infrared detector. Developed by the Barnes Engineering Co., Stamford, Conn., these detectors are now being used in spacecraft instruments for analyzing radiation from the earth's horizon. When five of these units are mounted in a tightly spaced row one can examine the horizon in detail. Behind the 1‐mm diameter lens a tiny flake of thermistor material is embedded to convert incoming infrared energy into an electrical signal. Germanium was selected for the lens because it is an excellent transmitter of infrared energy and an efficient shield against interfering light.

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