# Viewing computer screen through 3D glasses, why the asymmetry?

I have 3D glasses made up of plastic.

First case: When I hold front side of the 3D glasses (by this I mean that side on which light falls) in front of a computer screen, light coming from screen is not blocked, at any angle of rotation. But I see somewhat (slightly) bluish screen when 3D glasses are held horizontally; and yellowish (slightly) screen when glasses are held vertically.

Second case: Now I flip the side of the glasses i.e. "back" side of glasses is in front of screen and "front" side is closer to eyes. In this second case, when glasses are held horizontally, the light is blocked. When glasses are held vertically, light is not blocked; I can see the screen. For intermediate angle, intensity of light varies from minimum to maximum.

Questions:

1. Why I get slightly colored screens in the first case and why light is not blocked ?

2. Why light is blocked in the second case ?

I know (after reading somewhere) that glasses consists of a pair of circular polarizer and linear polarizer. Circular polarizer in my first case will be near to computer screen and linear polarizer will be near to eyes; and in second case vice versa.

• You probably need to mention which 3D glasses in this case, since there are many types... I assumed polarized 3D system? May 7, 2015 at 9:28
• Perhaps you don't want me to refer you to this wikipedia article (why?), but it's really well explained there: en.wikipedia.org/wiki/… May 7, 2015 at 9:44
• @AndrewT. Yes. polarized 3D system.
– atom
May 7, 2015 at 10:05
• @JanDvorak: I had read that article before I posted this question. I did not find answers to my 3 queries above, in that article.
– atom
May 7, 2015 at 10:07
• Rather than stating "don't send me to Wiki" it would be better to say "I have read x, and it leaves me wondering about Y". It "shows research effort" which is one of the criteria for getting upvotes (and often, better effort in answers) May 7, 2015 at 11:57