Step 35: Lighting: the Solution, I Said It Already
So perhaps surprisingly, the most sensible choice was halogen lighting.
On my first scanner, I bought new halogens and found that their lack of flicker, super-high output and reasonable price was perfect for this application. The bumpy hexagonal lens system they put on outdoor bulbs diffuses the light very nicely. And then, just in time for building the second scanner, I found a source of recycled halogen bulbs -- the Habitat for Humanity ReStore. At our ReStore, they have salvaged bulbs for 1.50 each, a tenth of the new price. FINALLY, the white balance of your camera can (and should) be set to Tungsten, which perfectly corrects for the warm color cast of these lights. In other words, your cameras come preset to use these things. It saves you time and effort and a whole step of color-correcting later.