Video and displays
ALR screen
An ambient light rejecting screen that reflects projector light toward the seats while absorbing or redirecting light arriving from other angles.
An ALR screen uses an optical structure, either multilayer coatings or a lenticular sawtooth surface, to treat light differently by its angle of arrival. Light from the projector is reflected to the audience; light from windows, lamps, or the ceiling is absorbed or bounced away.
In a room that cannot be made dark, an ALR screen is the difference between a grey, low-contrast picture and one with usable black levels. It matters most for daytime viewing and for UST projectors.
A good ALR surface rejects 60 to 90 percent of off-axis light. The geometry is specific: a screen made for a ceiling-mounted projector generally will not work with a UST unit, and many ALR screens have a narrower half-gain viewing cone than matte white.
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