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Physics/First surface mirrors.


QUESTION: Why are first surface mirrors so expensive? As I understand it, it would cost $15 either for a full length bathroom regular mirror with frame or a 1" by 1" piece of first surface mirror. Why is that? I'd like to buy those mirrors to design a adapter with my 3D printer to split all images taken with my camera into split screen stereoscopic images. I don't require anything too high ended. Just without the glare and light reduction of glass.

ANSWER: You can find them larger than that for not much more money (see the result of my quick google search below).  To create a second-surface mirror, one merely needs to polish glass to be smooth and then coat the smooth (back) surface with a silvering agent (silver or aluminum).  The thickness of the silvering doesn't have to be very precise.  To get a first-surface mirror, one must vacuum-deposit a precise and even coating of aluminum (or sometimes gold, depending on the application) to the front of the smooth glass surface.  This is generally a much more expensive process, and the tolerances for this type of vacuum deposition are pretty tight, as I understand it.  Having vacuum deposited thin metal surfaces on carbon foils by hand, I can tell you that it's a finicky process.

Anyhow, maybe this is more in your range:

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QUESTION: Is a second surface mirror that you're refering to the same as a house mirror? Like a bathroom one? If so it might be cheapest to go to a local glass cutter that deals in common mirrors and I can request thinner glass. I am only at the experimental stage and want to cut costs as much as possible. A brand name of the product I want to replicate cost $180ish and I'd like to create the same for a fraction if possible. I want to determine the correct angles for stereoscopics to work and figure how I'll edit images in post.

A second surface mirror is indeed the same as a house mirror.  You can get that (an "ordinary" mirror) made out of plastic, easy and cheap to cut.  That fact would somewhat minimize your ghosting problem that will always be present with a normal mirror.


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Dr. Stephen O. Nelson


I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.


I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

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