I'm designing a stereoscopic system to capture 2 images at the same time one for the right eye and one for the left eye.

To take a photo through a reflecting system, which one is the best choice of reflector to include in designing that system : Mirror or Totally reflecting prism?

Which one best preserves the quantity of light reflected so that I can have a bright, clear image similar to a photo taken with camera normally.


3 Answers 3


Based on an update in the comments it looks like you're trying to build some kind of stereoscopic mount or device to capture two images in one exposure.

A prism offers better light transmission. Mirrors are significantly lighter. Mirrors offer some ability to modify their geometry. Mirrors are significantly cheaper to produce.

Which is right for you depends on the circumstances you wish to satisfy.

All the prior art I found (albeit in a very very brief search) in the 3d photography field were mirror based devices such as the Kúla Deeper. I have to assume that the significant weight and cost differences won out over the better optics.

  • There is an alternative called first surface mirror. No glass transitions but more sensitive to damage.
    – Wirewrap
    Jun 1, 2015 at 7:34
  • Thanks for that info, would I be safe to assume that producing such a mirror would be costly and that any product would probably need additional protective measures (like a clear glass cover) that would negate the benefit of that sort of material? Jun 4, 2015 at 9:50
  • 1
    The silver layer is on the front side of the glass sheet instead of the back. No need to protect it when in place, you only need to protect it when you assemble your system, like avoiding fingerprints. Can be ordered from companies like Edmund Scientific.
    – Wirewrap
    Jun 4, 2015 at 16:45

Prisms have fewer air-to-glass transitions than a series of mirrors, and therefore better image quality. This is why SLRs and DSLRs with pentaprism viewfinders are usually preferred over pentamirror finders — although the latter are lighter and cheaper, both of which can also be significant advantages.


First thing to do is to walk up to a mirror and look at your reflection. What do you see? Do you see one nice crisp image? No you dont. You see 2 images. So basically you need to find a surface silvered mirror like the one in a SLR camera or use a prism and deal with refraction . Unless you know optics the former will be easier but alignment is critical.

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