Abstract This invention relates to a device for converting infrared radiation into visible light in order to make infrared images visible for viewing, detecting, and/or recording. In the converter, a single crystal of zinc sulfide is irradiated by a source of ultraviolet light thereby trapping charge carriers in the crystal at impurity or defect sites in the crystal lattice. The crystal is then exposed to a desired scene of infrared radiation that frees the charge carriers and, through quantum transitions, emits photons thereby producing a visible image of the desired scene. A cryogenic device and optical system are employed to reduce ambient infrared radiation and to increase the converter''s sensitivity to radiation of 15 microns and longer.
The infrared converter according to claim 1 wherein said crystal means has two faces; said ultraviolet means on one face thereof, and; said infrared energy is focused on the other face of said crystal means thereby producing a visible image on said single crystal means on said one face thereof.
Claim 2
Dependent Claim
16 words
The infrared converter according to claim 1 wherein said single crystal is composed of zinc sulfide.
Claim 3
Dependent Claim
17 words
The infrared converter according to claim 1 wherein said single crystal is composed of self-activated zinc sulfide.
Claim 4
Dependent Claim
16 words
The infrared converter accoRding to claim 1 wherein said single crystal is composed of zinc selenide.
Claim 5
Dependent Claim
33 words
The infrared converter according to claim 1 wherein said ultraviolet means is comprised of an ultraviolet source and a mirror that is so pivoted as to allow selective irradiation of said crystal means.