I want to build an infinity box. A mirror, lights and a one way mirror facing the first. My husband said he’d build it, but wanted to know how to make the “tunnel” straight. I’ve never seen one that didn’t curve.
Why does the repeat reflections in face to face mirrors curve? Does the direction of the curve vary? If so, why?
I’m thinking that maybe they work best if the mirrors aren’t quite parallel, if they were perfectly parallel then wouldn’t you be blocking out the view of the multiple reflections?
I’m building an “infinity box” which is a regular mirror, some indirect lighting around the frame then a one way mirror facing the other mirror. Its just a fun thing to hang on the wall.
It still curves, even though they are lined up.
Ah, I’ve seen those. They curve because either the mirrors aren’t perfectly flat, or they’re not perfectly lined up. Small distortions or misalignments get translated into big arcs. I don’t know how good you can get it without a professional machine shop, but flattening and aligning the mirrors are your objectives. Probably lining them up is the more important of the two, and easier to do as well.
I’m sorry, I should point out that I don’t know anything about building anything, but I know enough optics to recognize what’s going on. I don’t have any sort of good tips on how to fix the problem.
You can do much the same thing by pointing your webcam at your monitor; the capture/processing delay makes for quite an interesting effect - it is extremely difficult (but not impossible) to get the frames to recede in a straight line.
With mirrors:
-They need to be exactly flat
-They need to be in parallel plane
-You need to view it from the central axis (not possible for regular mirrors unless you put your head in between them)
Any slight variation in the above will cause the effect to curve.
Thank you all. That was my gut feeling, but my husband was giving me a song and dance about the earth’s rotation and toilets flushing counter clockwise. I thought it might be “Honey, I just don’t feel like working today.”
Since he went to such lengths, I’ll let him off for today. I’ll tackle it next week end 
Normally when you run into parallel mirrors, also, like in elevators or hotel hallways or such, to not view the “tunnel” at an angle you’d have to have your head in the way of it in the first place.