a bit technical question regarding retro reflective screens

[taxay]

I was wondering how much Gain you would get if the video projection beam was coming out towards a retro reflective screen nearly exactly from your eye position.In my own home theatre the projector is on a tripod rather than mounted on a wall and the screen is a 120'' retroreflective one. I've always noticed when I crouch to grab something from the floor (the beer), the image gets so bright when my eye is amost in the same angle of incidence as the projection lens that the light dazzles me.

But the question of just how much Gain you get at that angle come to my head when I saw this:https://www.youtube.com/watch?v=XPOgLt_73cY

To summarize the video it's a head-worn, very compact dual projector which directs the projection beam with special optics (a polarizer and QWP) to the screen and back to your eyes. So I'd guess you could expect very bright images even if the source LED wasn't very bright in this. Is 5.0 gain a reasonable estimate?

 

 

[Joe Fernand]

A screen does not generate light so you can never have more light reflecting off of the screen than the Source can Output - the 'gain' figure is relative to how much light you get back from a known surface.

https://www.projectorcentral.com/projector_screens_gain.htm

 

https://www.projectorcentral.com/projector_screens_brightness.htm

 

 

Joe

[Jivemaster]

Retro reflective screens have a very hot hotspot with a lot of fall off all round. If you position the screen to see the hotspot then probably only on position will see it all the others will miss it and miss most of the video.

[bigclive]

Retro reflective screens have a very hot hotspot with a lot of fall off all round. If you position the screen to see the hotspot then probably only on position will see it all the others will miss it and miss most of the video.

 

In this application that's probably a desirable effect, since each player is getting their own stereo image.