Thinking about how your phone’s touchscreen operates, you might assume that the so-called optical pads that have been making appearances on recent BlackBerrys ( among other devices ) operate in a similar fashion — but you’d be wrong. RIM’s official BlackBerry blog is chiming in today to drop some knowledge on us dullards, and it turns out that “optical” isn’t just a cute nickname — the pads do actually operate in much the same way as modern desktop mice, using a low-res infrared camera to capture movement across the surface and translate it into movement. In practical terms, what this means is that you don’t need a conductive surface to operate the pad — you can use pretty much anything that the sensor can see, so a gloved hand (for instance) is theoretically good to go. That being said, don’t expect to be snapping photos with your “camera” any time soon — we’re literally talking about a handful of grayscale pixels here, which should make it only marginally better than the Droid’s cam.

The image associated with this post is best viewed using a browser. The leaked-to-all-hell BlackBerry Onyx may have undergone one last change before heading to manufacture: judging by this shot nabbed by BlackBerry Underground , it’ll have a Curve 8520-esque optical trackpad —not a trackball. This feature has been a persistent rumor since the original Onyx shots hit the web , though the fact that it contradicted the actual photos of the device didn’t bode well for its credibility. In the context of early reactions to the Onyx leak, this apparent late change makes a lot of sense: the handset was characterized as a best-of-all-worlds device, keeping all the best features of non-touch BlackBerrys without sacrificing compactness. Grabbing the optical trackpad from the 8520, then, is an obvious move. [ BlackBerry Underground via BGR ]