I am a very happy Nexus 7 user, but as I was struggling to run a QR code through Google goggles, I began to understand how useful a camera on the back would be. So I'm thinking about a project of reflecting the front-facing camera around the edge of the tablet to turn it into a rear-facing camera.
This is easily done with a couple of mirrors; also by using two mirrors the image is reversed twice, turning it forward again (with a complication, see below). But mirrors are tricky to line up & inherently fragile. The same thing can be done with a prism. In fact two commercially made prisms do exactly that, the Porro prism (Porro prism - Wikipedia, the free encyclopedia) and the pentaprism (Pentaprism - Wikipedia, the free encyclopedia).
So I think this would be a fun project and I wonder whether anyone else agrees. I've found a source for both kinds of prisms at Surplus Shed, and have an idea of which would serve (13MM PENTA PRISM - Surplus Shed and SMALL PORRO ABBE PRISMS - Surplus Shed), but I need a way to hold them onto the tablet. Anyone have access to a 3D printer?
Penta or Porro. A Porro prism would need to be situated so that one half of the hypotenuse of the prism covered the camera lens and the other half peeked over the edge of the tablet. It would face backward. Because of the design of these prisms the image would not be reversed, as I mentioned, but it would be rotated 180 degrees. So everything would be upside down on the screen. I suspect most folks would find this annoying. The possible advantage of a penta prism is that instead of redirecting the camera 180 degrees, to point out the back of the tablet, it would redirect the camera to point 90 degrees, that is, out the top (or sides or bottom when rotated). Penta prisms are more expensive. Porro prisms could redirect most phone cameras to make them front-facing.
Lunch hour is over, but I'd be interested to hear responses etc from you all. Please forgive me if I don't reply until after work.
This is easily done with a couple of mirrors; also by using two mirrors the image is reversed twice, turning it forward again (with a complication, see below). But mirrors are tricky to line up & inherently fragile. The same thing can be done with a prism. In fact two commercially made prisms do exactly that, the Porro prism (Porro prism - Wikipedia, the free encyclopedia) and the pentaprism (Pentaprism - Wikipedia, the free encyclopedia).
So I think this would be a fun project and I wonder whether anyone else agrees. I've found a source for both kinds of prisms at Surplus Shed, and have an idea of which would serve (13MM PENTA PRISM - Surplus Shed and SMALL PORRO ABBE PRISMS - Surplus Shed), but I need a way to hold them onto the tablet. Anyone have access to a 3D printer?
Penta or Porro. A Porro prism would need to be situated so that one half of the hypotenuse of the prism covered the camera lens and the other half peeked over the edge of the tablet. It would face backward. Because of the design of these prisms the image would not be reversed, as I mentioned, but it would be rotated 180 degrees. So everything would be upside down on the screen. I suspect most folks would find this annoying. The possible advantage of a penta prism is that instead of redirecting the camera 180 degrees, to point out the back of the tablet, it would redirect the camera to point 90 degrees, that is, out the top (or sides or bottom when rotated). Penta prisms are more expensive. Porro prisms could redirect most phone cameras to make them front-facing.
Lunch hour is over, but I'd be interested to hear responses etc from you all. Please forgive me if I don't reply until after work.
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