Higher resolution link, just keep clicking the magnifier in the bottom right.
http://s1003.photobucket.com/user/AlbinoWarLord/media/HolographicSight.jpg.html?sort=3&o=5
In the beginning section we use a bump offset to do the holographic effect. In the middle section we draw the rings with math because I didn’t feel like opening photoshop. Then we do it three times and add them, multiplying by desired color and brightness. Apply to a flat plane that takes nearly the entire UV space and is centered on the 0.5, 0.5 coordinate. You could easily replace the middle section with a reticule texture if desired.
*There are some parameters in the image all named with 2 at the end. This is because I copy pasted in Photoshop. They should be in groups with 1, 2, and 3, so you can make the rings different sizes if you want. The Height parameters at the left should all be different values, -1, -2, and -3 were what I used, but this depends on how far apart you want the rings to look.
