Cold Mirrors for Projection Heat Control

Light sources used in motion-picture projection radiate heat in the form of infrared radiation as well as visible light. While the infrared radiation increases problems of overheating and film distortion it does not contribute to the screen image; therefore, maximum reduction of infrared radiation with minimum visible light loss is essential with the use of the high energy output of present-day projection light sources. A front-surface-coated projection lamp mirror is described which reflects to the film a high percentage of visible light, but which transmits through the mirror most of the infrared. Comparisons are made between front-surface-coated mirrors, rear-surface-coated mirrors and absorption-type heat filters.

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Published
1958-03
Content type
Original Research
DOI
10.5594/J11180