Sony Laser Projection...... Update - Page 3

Originally Posted by space2001 

I started the thread to talk about Sony Laser projectors in General. I can't talk to much about it but they did have a showing of SOMETHING SOMEWHERE with a Black curtain.

http://thejournal.com/articles/2013/01/29/mitsubishi-launches-lamp-free-hybrid-laser-projector.aspx

I bet the Mitsubishi will be cheaper.

Originally Posted by coolscan 

That is kind of the big question.
In general it is no difference. A RGB laser will give better and wider colorspace than a lamp. With laser light engine you also save on the optics because you can use a lens with a smaller aperture/F-stop because of the difference in Etendue. Lenses with smaller aperture is much cheaper to make. Think f/4-f/6 for laser and f/1.8 for lamp is typical.
This also gives a deep DOF so there will be less need for focusing the lens.

Originally Posted by tvted 

The larger glass will be more effective for transmission. There is a 3 to 4 stop difference with the the numbers you quoted from the 1.8. This amounts to a difference of 1/8th to 1/16th the amount of lumens at the lens vs. the 1.8 so you compromise your output.

I assume by DOF you mean depth of focus? Depth of field would be of no value on a a single-plane source like a image chip.

td

2.2 Étendue
The étendue of a light source is determined by the product of the emitting surface and the solid angle of the light
emission. For a short arc lamp the étendue is defined by the arc length. More powerful lamps have longer arcs, and thus a
larger étendue.

Lasers, on the other hand, have very small étendue, which is determined by the diameter of the beam waist
and the divergence angle of the beam and both of them are very small for most lasers.

The étendue of a projector is determined by the f-number of the light incident on the light valve and the size of the light valve.
The performance of today’s lamp-based high-end projectors is limited by the law of étendue: in a perfect optical system
étendue is conserved, but it can never be reduced without light losses and only the part of the light from the lamp that fits
inside the étendue of the light valve can be used. In order to collect more light from the light source (this can be one or
more lamps), the f-number of the system can be decreased. This increases the étendue acceptance of the system and the
system becomes brighter.

For a projector using a lamp one always has a trade-off between brightness versus contrast ratio, efficiency and depth of
focus. Figure 3 shows the typical behavior of brightness and contrast as a function of the f-number for a projector with a
lamp.
There is not such a trade-off for projectors based on lasers, or it comes only into play for very high brightness
levels.
As the étendue of a laser is very small compared to the étendue of today’s projectors, one can easily combine
several laser sources, without any light losses and still keep the f-number high.

High-brightness demonstration

The optics were slowed from f/2.4 to f/6.0, while the conventional prism combiner was replaced with dichroic plates to improve contrast and further reduce costs. Speckle reduction was accomplished throughout the machine using multiple techniques strategically placed to keep the optical efficiency high while reducing optomechanical complexity.

Originally Posted by tvted 

The larger glass will be more effective for transmission.

Originally Posted by noah katz 

Are you sure about that?

That would seem to mean that transmission is nonlinear, i.e decdreases varies with brightness (lumens per lens area)

Originally Posted by coolscan 

To give a general answer to the questions asked here after my last post.

After the Osiris project was culminated in 2010, there has been very little public information about laser projectors. Seems like all R&D have disappeared into the various companies that guard their development against the competition, or only published papers behind Pay-Walls.
Because of this, it is impossible to conclude anything about what sort of gains Laser projectors will have compared to bulb projectors, except what we already know.
I will as always both depend on difference between what imaginer systems that is use (Lcos/DLP) and what type of lasers (Solid State Lasers/Semiconductor Diode lasers).

There are not even any real confirmations of what is holding them back. Is it unsolved Speckle problems, Laser costs or a combination of both?

AVS had several very good articles and videos on the technical presentation of the Kodak DLP laser projectors back in 2010, but most of the links are dead.
For those that haven't seen the videos and want to know more about Laser projectors. This videos gives a good insight in the principle and problems with using Laser for projector light engines.
Here is the link; http://www.youtube.com/user/avscience?feature=watch Scroll down; There are ten videos in the complete presentation.

Out of the little that have been released of information since 2010, there seems to still be some problems to solve with laser projectors, maybe particularly with smaller HT units that will use semiconductor diode lasers.

Wish there where more openness about the latest developments and problems connected to laser driven HT projectors.

Originally Posted by noah katz 

coolscan, thanks for the links and excerpts.

Is there then a bottom-line improvement in CR we can expect with a laser pj?

Originally Posted by mark haflich 

Question, while it would be nice to eliminate the need and expense of changing bulbs, do we need laser projectors and should we lament not getting them.

Originally Posted by coolscan 


The Kodak DLP laser prototype at an exhibition at the Kodak theater on Gain-1 white screen measured on/off 10.000:1. But they had a earlier version at 20K:1, and expected a commercial version would reach that measure.

Originally Posted by space2001 

Don't forget with Laser driven source you can adjust the brightness on the fly. In a darker scene of the movie, the light output can be lowered, just like the auto iris.