In case anyone wanted to have a peek inside a Spyder3 for comparison, I had one sitting around that I stopped using a long time ago. So I had no intention of reassembling the thing, which basically doesn't agree with any of my other sensors (used with any software).
From the front there is a 2mm honeycomb, cyan glass filter with unknown function, plastic diffuser, fresnel lens, and finally no less than seven plastic transmissive (not dichroic) filters for seven diodes (or whatever they are...). The whole path is very shallow, about 15 mm or so.
It should be noted that I have another Eizo-branded Spyder3, once bought bundled with a Flexscan unit, that seems at a whole other precision level. I've tested this against the i1D3 in both ColorNavigator and Spectraview II, and they basically give identical results. So it seems, just as the case with LCD panels, that Eizo hand picks their components.