Charlie:

At least one less thing to worry about: If you've ever seen an actual DMD device you will quickly see that the thing is REALLY sealed up at the fab. While you may be corect that clean room issues could be responsible for crud in the chip, that seems unlikely to pass their QA. As to your concern about putting a protective something-or-other over the chip, or for having the OEM do it, that isn't needed. it is possible that dust could lnad on the front surface of the device, but that could easily be cleaned or blown away as needed.

In so far as the color wheels themsleves, there are a variety of options available to those few companies that actually design and build their own optical engines. Right now you can chose from a variety of options, including four, six or nine segment wheels. (Depends on how many repeats you want and if you want a "white" segment or just RGB.) The new SCR color wheels have been demosntrated but are still a bit off in terms of being used in commerical or consumer products.

But what do I know, I'm only a dog!

ARF ARF, says Iggy