The fluorescent tubes are best. Easy to find a 13w holder and a tube, that you can plug in and get really good results. If you go to rummage sales, you'll find them, but Lowe's has the fixtures and Ace hardware has the bulbs.

Then the portable fluorescent, battery operated that you can get at coin shows.

LEDs, and others do not work as well. I found the regular, incandescent light bulbs to be the worst of all of them. They get hot too!

With that, I haven't figured out how to scan a UV chip yet, I take photos. Greg uses a little digital microscope 10 power that he shines with a UV light. I always wanted to convert an old scanner, but never had the time or energy. Different digital cameras have different results. Some look blue, some purple, but none that I've seen yet, show a nice marking, without a color cast. Using a combination of UV and subdued natural lighting, lets you see the chip and the markings. (Winter project?)

Last of all. UV marking do fade and wash off chips. They may have been worn or washed off you chip.