Is there a special term for silvered mirrors being used for optics?
August 20, 2013 10:45 AM   Subscribe

Do specialized mirrors for optics projects have a different name for a "glassless" mirror, or a specially silvered mirror which has a glass quality to minimize any internal reflections?

I am using an ordinary wall mirror to bounce the beam from a video projector at a forty five degree angle so the projection goes up onto the ceiling, but internal reflections between the silvered surface of the mirror and the glass creates "ghost images" about two millimeters apart.

Do specialized mirrors for optics projects have a different name for a "glassless" mirror, or a specially silvered mirror which has a glass quality to minimize any internal reflections?
posted by shipbreaker to Technology (5 answers total) 1 user marked this as a favorite
 
First-surface mirrors
posted by MrMoonPie at 10:47 AM on August 20, 2013 [4 favorites]


I've also heard the term "Front surface mirror" for those.
posted by rmd1023 at 10:54 AM on August 20, 2013


You can tell if a mirror is a front/first surface mirror by placing an object (a finger works well for this) on the top surface. A front/first surface mirror will show a reflection that touches the object. A back surface mirror will have a gap between the object and the mirror surface, this gap size depends on the thickness of the glass.

Snopes website covers this topic a little more in depth.
posted by JujuB at 11:08 AM on August 20, 2013


I had never heard that term, even working in optics labs for close to 20 years. We just call them "mirrors", maybe specifying whether they have silver, aluminum, gold, or dielectric reflecting surfaces. I'm not sure exactly what size you're looking for, or what your budget is, but here are a couple options from two of the largest vendors of research-grade optics: Newport and Thorlabs.
posted by partylarry at 11:12 AM on August 20, 2013


For telescopes, we just call them "mirrors".

You should see the giant mirror at Palomar when it is out for refinishing - that telescope is the last of its kind.
posted by RedOrGreen at 2:04 PM on August 20, 2013


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