Why only a true RGB Laser Projector is the Best

[w.mayer]

In this thread I would like to post about reasons why a true RGB laser projector can project such an incredible good picture, probably the best in the world.

For many people it is still a question why a true RGB laser projector shows a better picture compared to the same projector which is driven by a xenon lamp or even an UHP lamp. A good example is a Barco cinema projector, which you can convert from xenon to laser.

Today, I would like to start with one of the major reasons and I am planning to add more reasons later on.

“THE WAVE LENGTH OF EACH OF THE 3 LASER BEAMS”

When you have a regular lamp based projector, at first the white light from the lamp will have to split via a prism into their RGB light parts.
These R G B parts of the lightlooks like a reversed bell, when you measure it from the projector and these parts are about 30-50 nm wide, see the pictures down below.

For example, green goes from about 550nm to 600 nm, so it is about 50 nm wide.
A true laser ( not laser phosphor!) has only around 1 or 2nm wave length wide bell at the laser and this light beam will go much easier to every glass that was in the light engine of the projector and the lens and was also more easy to be reflected from all surfaces.

Count how many glasses the light after it was created from the 3 R G B DMDs hit and need to pass till it hit the screen!!!
You will be shocked/surprised how many surfaces and glass parts are needed so that the light finally hits the screen.
My guess is, at the light engine at least 15 glasses and surfaces and at the lens, easily 13 lenses and 26 surfaces the lights must be passing thru.
So we are talking at more than 25 glass lenses and more than 50 surfaces in total!!!

And this is the main difference as a tight laser beam with this super slim beam can pass much better without bugs and decreases to any glass parts or reflected surfaces.

Laser phosphor projectors are a compromise as only the blue is real laser with a very slim wavelength laser (see picture Sony Vw 760), yet the red and green still have a rather wide 50nm beam.

The picture with the true laser is not a real measurement, I just created it to explain what I described above, but in reality they could be looking a bit wider, see also the Blue part from the Sony VW760 picture.

When taking a closer look at the pictures, BTW thanks to Raphael Vogt www.av-consultant.de  and Ekki Schmitt from http://cine4home.de , you will see that an UHP lamp based projector has lesser red light and especially in the dark-red a big minus.
Yet this is still better than most laser phosphor projectors that have even a bit lesser good red light than a UHD lamp based projectors.
Xenon based projector have almost all 3 colors at similar levels and dark red is very strong.

Only a true RGB laser Pr. can show full 100% of Rec. 2020 vision color today.
When I show visitors the Rec. 2020 red the Barco Thor can do when I playback the hidden test pictures from Sony UHD Disc most are shocked as they never see such a deep saturated red before.
Trade of is that I have to switch 3 laser from 6 laser of as only in this mode the pr. show full Rec. 2020 vision color but you reduce the lumen by 50% when doing it.
At all 6 lasers the Barco have you have full 100% DCI color.

Summary is the tight light beam is responsible for a huge quality improvement when the light source is a true direct RGB laser.

[w.mayer]

I got some more details I like to share.

In the Barco Thor the two Red Laser had about 2nm the two Green Laser are about 6nm and two Blue Laser in-between so around 4nm.
May someday I can post a picture of what the Barco Thor outputs with a real measurement.

Barco was forced to use a slightly wider laser because when they put 6 laser with for sample only 1 nm "speckle" will be "a lot more".

With lamp and even laser phosphor, light travels in all directions and from all angles. This indeed makes it difficult to capture, but also makes sure that the ‘field of depth’ is less, and the contrast is lower.
With RGB lasers, they are much more directional, so the imaging is more high quality (less scatter, less strange angles), and there is better field of depth, a better definition of a pixel, and higher contrast.

[w.mayer]

One more reason why a RGB laser pr. is the best is the prism in the light engine.
Barco RGB laser projector use a much better (and of course much more expensive) prism than
in all lamp based projectors.
This prism was built from a very special glass material has less thermal expansion, makes a higher contrast, and also a better pixel definition (less flare, sharper pixels).
This together with the much better optics produce an image that is much sharper and with higher contrast.
One result is the insane high ansi cr. in the near 1000:1 range!
Not only for normally ansi cr. test pictures like the big chessboard
also the micro cr. is far better.
I mean when small bright areas are near small dark areas this RGB laser show a much better picture compare to every other lamp based technology include laser phosphor.

[w.mayer]

Thanks to Raphael Vogt www.av-consultant.de I can post here a light spectrum measurement from him from the new JVC 4K projector the NX9.
This projector and the other 2 are delayed and today no one knows when JVC will bring it finally to the marked.

One picture show the spectrum without the DCI Filter one with the Filter inside.

As you can see the filter shrink the wide of each primary color and therefore you lost lumen but get better wider color.

[MrPixels]

JVC sent a memo today the new models are going into production. Seams what ever issue they were having has been solved.

[w.mayer]

Yes can confirm this.
My dealer in Germany told me yesterday the same.
He guess end of januar we likely will get first shipment.

[w.mayer]

So back to RGB Laser.

An advantage from laser based pr. compare to Xenon lamp or UHD lamp based pr. are that the light source show not any flicker.

Often Xenon lamp pr. show with a new lamp a bit flicker as the arc of the bulb need first to burn in a bit.
So often you can see with a new lamp the first 100 to 150 hours flicker.
Later it will be better but you still can see it when you watch close.
It is also depends on every individual as some people are sensitive about flicker some not.

All laser phosphor pr. I have seen so far not show any flicker as well.

Also color drift is an advantage from real RGB laser.

UHD lamp based pr. have a color drift as a UHP lamp contains a huge mix of different elements.
During the last years UHP lamp manufactures improve the color drift a lot compare to the past but still a
UHP lamp have some color drift.

Xenon lamp pr. are have “almost” not any color drift.
I am not sure about laser phosphor at this time. I guess that they have a slight color drift over the livetime as phosphor gets weaker over time.

A true RGB direct laser show no color drift over the lifetime at least not any that counts.

[MrPixels]

Laser is also Safer than Xenon.

Drop a Laser module and nothing happens.

[donaldk]

Wolfgang could you explain why a seperate RGB lightsource projector still needs a prism, that in regular 3 DMD/LCD/LCoS projectors is used to sperate the Red, Green and Blue light from the White light?

Some of the LG single DMD, 3 LED projectors have a simply elegant block with an U shaped placement of the three LEDs around the DMD. No prism, just the light to the dmd.

Very nice summary Wolfgang, of the issues that make the Barco L HC/Thor, and the Christie alternatives, RGB LASER DLP projectors, king of the hill.

Just to clarify the 'LASERS' are actually arrays of LASER Diodes, that is also how projector manufacturers can adjust the bandwidth of R, G, and B colors, to avoid/reduce speckle and metameric failure.

As for dropping laser units, probably something does happen when that happens, they may get damaged, but they are not highly pressurised, scattering glass everywhere at high speeds.

As the LASER Diodes age there will be a difference in output, and even colorshift, as diodes age unevenly. The rate of decay, though, is soooooo much lower than 900-1500 specified hour lifetime Xenon bulbs. Sophisticated projectors like the Barco's may have electronic management to counter this issue, just like they have constant light-output control, and calibration options to manage even distribution of the laserlight when light is traded for on-off contrast. Perhaps you can expand on this?

The narrow spectrum per color, should help in combatting the chromatic abberation through the optical system. The refractive index is frequency=color dependent. Narrow spectrum light optical abberations might be more easy to combat throught compensation in the video. As far as I now no projector manufacturer has implemented something like this. It has been implemented on the other end of the chain, light to electrical signal, i.e. high-end camera's.

The issue with 6 seperate primaries not being Rec. 2020 compliant is that in the standard it specifies three exact primaries. That was what we learned a few years ago when the first RGB (near) Rec. 2020 projectors were demonstrated.

Even when the three primaries would lay outside rec. 2020 triangle such a projetcor would not be compliant. Theoretically one could construct a projector with 6 primaries that shows light upto the edges of the rec. 2020 color triangle, but in practical applications Rec. 2020 is still a nice to have, to an absolute requirement, so there is no need for such complicated projects.

[w.mayer]

I am 99% sure that you are right a 6 P or a 3P laser pr. do not need a color separation optical prima as the separation is already made buy the laser itself.
So likely a mistake from me.

But there was such a prima also in a laser 3 or 6p pr. inside that works “the opposite way”.
When you need to overlay the 3 RGB DMDs to one picture such a prima is need in both a xenon lamp based and RGB laser based pr.

Dropping a laser is may nothing that counts in the real world but there are so many other very small issues that add all together made a true RGB laser pr. the best money can buy.

There is as I had post long time ago already just one feature where it is possible to improve the visual picture quality in a big step and this is improving the black like Christie do it with their upcoming insane expensive and likely difficult to operate and adjust infinity cr. projectors.
Let’s see if and when they finally comes to the market but this technology can be a game changer.

[donaldk]

Wolfgang you said you were to informed by christie on the new projector, including pricerange a few weeks ago, so did they tell you so you are now saying 'insanely expensive' because your contacts provided guide pricing, or is it because they don't dare tell you, so it must be way more than the Thor?

[w.mayer]

Yes forget to do the post this time of the year I am very busy.
Please see the last post from me:
http://dci-forum.com/d-cinema-hi-end-cinema-home/11/new-christie-large-venue/2952/52

[w.mayer]

Yesterday Raphael Vogt very well known as one of the best in Germany that can calibrate displays and projectors comes to visit me as he was near Munich.
He had also his own measuring laboratory and is also known from his web site  https://www.lowbeats.de/

He measure the Barco Thor because of I like to know how the peaks from each 2 laser per color looks and how big is his color range if it really as Barco say can do full 100% BT2020.

He made 2 measurements one show the Spectrum of BT 709 and the DCI P3 color where the Pr. operate with 2 laser per red, green and blue and the other with only 1 laser per red green blue show the BT2020 Spectrum .

The picture was displayed with the internal uncorrected 12 bit test pattern from the Barco Thor displayed to my new Dreamscreen V6 XXL screen.

As the new V6 screen was visually very close in color to the old Harkness Matt Preview I so far not let Barco do the color calibration again for this new screen.
I may will do it may not as there will be for sure not a big difference visible.

Mr. Vogt also measure the color triangle to see how wide the color can go in the BT2020 color.
In this mode the Barco Thor switch 3 from the 6 laser of mean that only one laser is working in red green and blue.
Therefore the lumen will be drop to about half.

I will post later the picture but I can tell you that he measure just a bit bigger than BT2020!

But as I had post please now compare the 2 Barco measurements to a typically UHD or Xenon Lamp Projector and you will be understand better why a true laser is the best.

[donaldk]

So Barco can do wider than Rec 2020 gamut, as the switched off Blue and Red lie further out. Barco marketeer order a slight software modification to turn of the other R and B instead, and be first to show 1xx% rec. 2020.

[w.mayer]

Here the BT2020 color measurement.

As you can see the Barco Thor can do bigger than BT2020!

Green is hit almost 100% Red and Blue are bigger than BT2020!

I think this is the only Pr. so far on the market that can do bigger than BT2020.
And this is not senseless it is good as it gives room for further calibrations that cost something in color and you still can do 100% BT 2020 with the color calibration made.
THIS IS WOW!