for crappy mice, glass that has a readable surface behind it isn't an issue (usually 1/8th inch or so). But for higher end mice, especially gaming oriented, they have a limited reach, the smaller the better, so your mouse won't track when you pick the mouse up. I have built a mouse pad or two out of some acrylic and some uv reactive paint, it's kind of difficult to get infrared mice to read on this kind of surface because the IR signal is diffused rather than reflected. laser mice *shouldn't* have as much of an issue provided that the glass isn't too thick and does indeed have something of color or opaqueness behind it. Having said all that, the title of this article clearly makes me want to read about "darkfield" tech or whatever but no mention of it is included. disappointing to say the least. Maybe i will mod my mouse with a red laser so i can use glass/acrylic.