This is topic RealD's new extra light system.. in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=009803

---

Posted by James B Gardiner (Member # 5151) on 03-15-2009, 03:31 AM:
 
Does anyone have the details on this new RealD system that is suppose to archive much better light levels?
How does it work etc?
 

---

Posted by Julio Roberto (Member # 4976) on 03-15-2009, 03:58 AM:
 
I haven't seen it nor have I found more information about it, so I can only speculate.

They probably replaced the traditional circular polarizer (linear+wave plate) which often only gets efficiencies of about 47% max. theoretical with a different multi-wave guide one (probably multi chiral sandwiches) which has theoretical efficiencies of up to 94% at the beginning of their Zscreen sandwich.

There. Instant light doubling

They are much more expensive but very reasonable, as few things are cheaper than a traditional polarizer filters

[ 03-15-2009, 05:24 AM: Message edited by: Julio Roberto ]
 

---

Posted by James B Gardiner (Member # 5151) on 03-15-2009, 08:19 AM:
 
Julio,
I need more then that. How about some links to this tech.
Discussing how it works etc?

I have not heard of this polarizing tech you mention. I expect there would be some type of information online.. especially the circular stuff. Found a lot on that.

I heard there was a new type of BOX with maybe two outputs.
And that some how it re-uses the light..
Sounded very iffy to me.
 

---

Posted by Julio Roberto (Member # 4976) on 03-15-2009, 08:49 AM:
 
http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?tp=&arnumber=4382351&isnumber=4382237

That would be a good paper on the technology I was talking about.

I doubt RealD used a light recovery box, but if they did, that would be the "easy" way out.

It's easy to separate light "50/50" based on its polarization with, i.e., a wire grid polarizer, by reflecting the half that is in one direction and allowing the other half to pass through.

Then you can rotate the half you reflected with a wave plate and make it go through the optical path again. That way you get "100%" of the light polarized in one state going through the path you wanted.

Sort of.

Here is a link to RealD patent abstract for such an implementation:

http://www.faqs.org/patents/app/20080225236

quote:

---

A polarization conversion system (PCS) is located in the output light path of a projector. The PCS may include a polarizing beam splitter, a polarization rotating element, a reflecting element, and a polarization switch. Typically, a projector outputs randomly-polarized light. This light is input to the PCS, in which the PCS separates p-polarized light and s-polarized light at the polarizing beam splitter. P-polarized light is directed toward the polarization switch on a first path. The s-polarized light is passed on a second path through the polarization rotating element (e.g., a half-wave plate), thereby transforming it to p-polarized light. A reflecting element directs the transformed polarized light (now p-polarized) along the second path toward the polarization switch. The first and second light paths are ultimately directed toward a projection screen to collectively form a brighter screen image in cinematic applications utilizing polarized light for three-dimensional viewing.

---