This little device has more apps and uses then Carter had liver pills! For instance it has the abilities of a Flashlight, Scanner, Repair tool, Medi-gel Dispenser, Program and Hacking hub, Video camera, Video, Audio and holographic communication, Downloadable video games (heh), Omni-gel converter, and a real time object manufacturer. Now on to the science!
So let us begin with the holographic nature. On your armor or wrist type device, there is a projector. This projects a hard-light in the shape of a gauntlet covering your hand and forearm. The hard-light projector works in a similar manner such as the energy sword hilt in my last post. Holdings not energy but instead gamma rays in a static state. Difference being this is hard LIGHT making it much more stable and well, hard. To be more specific according to the mass effect wiki "Diamond-hard".
Now for the theories. I theorize that because the omni-tool is in fact all light it gets hot much like your light bulbs. Like a laser pointer it would require a heat chip to keep it from baking your arm like a potato.
Now for this hard light to be usable as a keyboard it would have to sense how far away your other hand is to present the graphic of the keys and the rings moving. With that being said there must be a small transmitter in the finger tips of the glove opposite of the omni tool.
Next we have its overly long lasting battery power. What i hypothesize is that on the same forearm as the omni-tool there is a atmospheric energy harvester. Basically a device that attracts static electricity in the air and utilizes it to power energy storage units again on that forearm.
Finally to wrap us up. From what i can see the omni tool isn't so much about the orange light that is around the arm, as it is a computer embedded in the forearm armor of the soldiers that use it. Essentially a projector computer on steroids utilizing tiny micro chips so as not to make the gauntlet too heavy. When you see people using omni-tools without a wrist gauntlet... well that just doesn't make any sense what so ever. At least none that i can see.With all due respect
The Game General