You searched for: “snooperscope
snooperscope
1. A device that converts infrared radiation into a visual image and is used for seeing in the dark.
2. An infrared image converter, and a battery-operated high-voltage direct-current source constructed in portable form to permit a foot soldier or other user to see objects in total darkness.

Infrared radiation is sent out by the infrared source is reflected back to the snooperscope and converted into a visible image on the fluorescent screen of the image tube.