Mirrored-mirror mirror.
December 8, 2010 2:12 PM
I want to build a de-reversed mirror.
My brain swears that it remembers seeing plans to build a mirror that does not "reverse" the image the way a regular mirror does. It wasn't just two mirrors at a right angle or a concave mirror. It looked normal, and I'm pretty sure it was done with an enclosed optical apparatus of mirrors/lenses, not a camera.
It's sort of difficult to search for, but not luck with what I can think of. Reverse? Non-reverse? De-reverse?
Either actual plans or references to help with the principles needed to design such a thing would be awesome.
My brain swears that it remembers seeing plans to build a mirror that does not "reverse" the image the way a regular mirror does. It wasn't just two mirrors at a right angle or a concave mirror. It looked normal, and I'm pretty sure it was done with an enclosed optical apparatus of mirrors/lenses, not a camera.
It's sort of difficult to search for, but not luck with what I can think of. Reverse? Non-reverse? De-reverse?
Either actual plans or references to help with the principles needed to design such a thing would be awesome.
From the True Mirror link: And the image we see looking at us from the mirror is not the face we show to the world - left and right are reversed.
No. Mirrors do not reverse left and right. How could they do that without reversing top and bottom? Mirrors reverse front and back.
posted by weapons-grade pandemonium at 2:32 PM on December 8, 2010
No. Mirrors do not reverse left and right. How could they do that without reversing top and bottom? Mirrors reverse front and back.
posted by weapons-grade pandemonium at 2:32 PM on December 8, 2010
weapons-grade pandemonium, you're correct of course, but to most people, left-and-right is how they understand it.
The simple answer is: you need two mirrors held at a precise 90-degrees to each other (along a vertical join line). You could build such a frame out of rabbited wood frame stock; once the correct angle is achieved, lock it down with brads on a base, and seal with glue.
posted by IAmBroom at 2:37 PM on December 8, 2010
The simple answer is: you need two mirrors held at a precise 90-degrees to each other (along a vertical join line). You could build such a frame out of rabbited wood frame stock; once the correct angle is achieved, lock it down with brads on a base, and seal with glue.
posted by IAmBroom at 2:37 PM on December 8, 2010
Guys,
cmoj: It wasn't just two mirrors at a right angle.
posted by wayland at 2:52 PM on December 8, 2010
cmoj: It wasn't just two mirrors at a right angle.
posted by wayland at 2:52 PM on December 8, 2010
If you take two regular mirrors and put them at a right angle it will have a visible seam, which is probably what cmoj was referring to. But normal mirrors are silvered on the back side; if you use front-silvered mirrors as in Comrade_robot's second link then it does look seamless.
posted by Rhomboid at 3:26 PM on December 8, 2010
posted by Rhomboid at 3:26 PM on December 8, 2010
Well, to be clearer, it may have worked by putting two mirrors at right angles, but inside a box somehow and with a frontpiece that it projects on to or something to look like a normal mirror, but reversed on... whatever axis makes you feel comfortable.
posted by cmoj at 3:53 PM on December 8, 2010
posted by cmoj at 3:53 PM on December 8, 2010
Guys,
cmoj: It wasn't just two mirrors at a right angle.
wayland: Yes, it was. The only other way to do this is to use video camera equipment and a projection screen.
It could be done with a roof prism, turned so that the 90-deg angle is at the back - but then, the back sides are acting as two mirrors, so it's still the same idea (just much heavier).
posted by IAmBroom at 12:28 PM on December 9, 2010
cmoj: It wasn't just two mirrors at a right angle.
wayland: Yes, it was. The only other way to do this is to use video camera equipment and a projection screen.
It could be done with a roof prism, turned so that the 90-deg angle is at the back - but then, the back sides are acting as two mirrors, so it's still the same idea (just much heavier).
posted by IAmBroom at 12:28 PM on December 9, 2010
I just happened on a Physics Today article by Andrew Hicks which describes a method for shaping a mirror to produce an arbitrary transformation from the object to its image. The example in that article is a "saddle-shaped" mirror which, like two perpendicular mirrors, reverses front-back and left-right but not up-down. It looks like the magic mirror linked by lee is the same object.
There's some distortion in the image, which is apparently unavoidable. I guess if it's saddle-shaped, it's concave and reversing (like the inside of a spoon) in the horizontal direction, but convex and non-reversing (like the outside of a spoon) in the vertical direction. Matching those would be a neat problem.
posted by fantabulous timewaster at 9:54 AM on December 23, 2010
There's some distortion in the image, which is apparently unavoidable. I guess if it's saddle-shaped, it's concave and reversing (like the inside of a spoon) in the horizontal direction, but convex and non-reversing (like the outside of a spoon) in the vertical direction. Matching those would be a neat problem.
posted by fantabulous timewaster at 9:54 AM on December 23, 2010
« Older Movie scene where an incompetent dad burns the... | How to force page breaks when printing email? Newer »
This thread is closed to new comments.
posted by lee at 2:21 PM on December 8, 2010