Talk:Two-way mirror

From Wikipedia, the free encyclopedia

	It is requested that a photograph or photographs be included in this article to improve its quality.
	The Free Image Search Tool (FIST) may be able to locate suitable images on Flickr and other web sites.

Introduction -we hope this page doesn't violate any state secrets, but anyone who has watched detective shows or has tried on mirrored sunglasses knows something about all this. And any renter who wants to check out a suspiciously placed bathroom mirror should learn how to put their wife at ease that the landlord is not videotaping them in the shower for a future internet posting. Its quite common to see mirrored windows separating shopping areas from the manager' office. And mirrored ceiling tiles often hide attic video cameras. U.S. Post offices even have soundproof passages in the ceiling called Look Out Galleries, that have little mirrored bay windows to prevent theft or diversion of the mails by employees. Feel free to shorten or correct spelling.

The reference to disneyland may be out of date, as it was 1971 when i noticed this. Transparent ghosts were well lit reflections of ghost manakins located below the viewer but reflected against a glass wall to appear as semi transparent apparitions flying in a room next to the viewer. All the more impressive because they appeared in three dimensions. A similar effect was had by reflections in framed mirrors as the cars rotated and climbed out of the ride, and appeared in the mirror to be riding in the car with you. WonderWheeler 07:41, 26 February 2007 (UTC)

The effect referred to by WonderWheeler is called Pepper's ghost. — Paul G 17:13, 15 June 2007 (UTC)

Thanks for the addition of Peppers's ghost. I was unaware of the term, was only observing the effect. There is also a discussion at mirror under "one-way mirror". Will try to add a link there to this page, and thereby Pepper's ghost. WonderWheeler 01:05, 26 August 2007 (UTC)

[edit] urinal

i once used a urinal at a restaurant (the type where it is a long a wall) and instead of a metal wall they had a two-way mirror, that you could see all the patrons of the resteraunt through. i don't understand how this type of glass could be fooled so easily (i dont think it was especially dark in the bathroom) as anyone wearing sunglasses or something could see you! there must be other types of mirrors. does anyone know? —The preceding unsigned comment was added by 202.156.66.110 (talk)

In case it's any comfort, I'm pretty sure sunglasses won't help you see through a two-way mirror from the bright side. The sunglasses will cut down the intensity of the reflected light from the bright room, but they'll dim the transmitted light from the darker room by the same factor. So the reflection will still overwhelm the transmitted image and you won't be able to see it. I admit I'm not completely sure that the mirror doesn't partially polarize the reflected image -- if it does then polarized sunglasses might have some effect. --Trovatore 01:54, 3 October 2007 (UTC)

[edit] this page is terrible

This page needs drastic revision. It is written like a how-to guide. It does not meet wikipedia's quality standards. Someone needs to completely rewrite it. --Rebent 17:20, 14 October 2007 (UTC)

It doesn't even say when two-way mirrors were invented. PolarisSLBM (talk) 01:27, 27 December 2007 (UTC)

[edit] Physics

As I understand it, a true passive one-way optical device is not possible—you can use a video camera and a screen, but you can't make optics that only let light through in one direction. Please correct me if I am wrong, but I think this is related to reciprocity. If this is in fact the case, the article should make it clear that so-called one-way mirrors are really a combination of coated glass with particular lighting. In the usual case, you use a semi-silvered mirror, so say 10% of the light passes through and 90% is reflected. If you put that between a dark room and a light room, where the dark room is 5% as bright as the light room, then on the light side, you will see 0.9 * 1 L + 0.1 * 0.05 D = 0.9 L + 0.005 D where L and D are the images of the light and dark rooms respectively if they were lit the same. On the dark side, you would see 0.05 * 0.9 D + 0.1 * 1 L = 0.045 D + .1 L which, adjusting for exposure is the same as L + .45D. So effectively, that's one-way glass, even though it really behaves symmetrically. —Ben FrantzDale (talk) 21:25, 26 May 2008 (UTC)