I've experimented using simple color LCDs as an image source, backlighting it with a spread beam. I've used 635 nm and 650 nm lasers. I don't have hard numbers but I estimate that only 1/1000 of the light passes through. A huge amount is reflected off the acrylic backplate, another significant amount lost to the polarizer, and then the RGB pixel filters take care of the rest.
Does anyone have good experience to share using LCDs? What's the most light-efficient method you have used? And what's the most effective approach for hobbyists -- not necessarily most light-efficient but within the costs and capabilities of motivated hobbyists?
Joe
LCD Transmittivity
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BobH
LCD Transmittivity
Perhaps the polarization of the laser beam does not match a polarizer on the input face of the LCD. Or, perhaps the LCD must be on to get anything through it. In other words, the "off" state is black, and the "on" state pixel is what gets through.