Laser projectors general? [zero lag & zero blur!!!]

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Light23
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Re: Laser projectors general?

Post by Light23 » 09 Dec 2014, 03:11

In all of this talk about how great direct laser scanning is with motion blur, color gamut and contrast I would also like to discuss the shortcomings about the showwx LBS (Laser Beam Scanning) method and how to resolve any issues so you can get the most out of gaming on this device.

(1.)Text
Image
Text is by far more readable than with other display technologies. BUT...
As you can see in the image above there are blue and red fringe lines on either side of every letter or font.
The problem is that the red, green, and blue lasers are not perfectly aligned with respect to each other which means that the image for red, green, and blue are all scaled independently of each other. This in turn causes a color “aliasing” when looking at text close up.

I found out a way to negate this effect completely tonight.

The laser setup is RGB like most monitors BUT there are some monitors that are setup for BGR.
You will need to do a alteration of the subpixel layout from RGB to BGR on the OS you are using.

I know several of you have already bought a showwx+ so hook it up right now and examine this image closely to understand what I mean...
Image

Notice how the example subpixel BGR looks the best on the showwx+?
Thats because its reversing the RGB alignment and 'correcting' the font into solid black by reversing the RGB order.
(Even messing with the lasers individual laser alignment never got rid of the color fringing in font before now.)

You can change the sub pixel layout in Windows by using ClearType. Firefox allows you to force webpages to use the fonts you specify by unchecking "Allow pages to choose their own fonts instead of my selection above" in the advanced fonts settings. I use this to force Windows ClearType fonts in Firefox.

Run the ClearType optimizer thingy in windows 8. It’s supports BGR.

(2.)
Laser speckle
Image
The laser radiation speckle can be...distracting.
With its grainy appearance and shifting pattern when you move like 1cm, it can be a problem.
The speckle issue is caused by the very narrow bandwidth of the lasers used. They have a lot of coherence with no mode hopping, which is great for holography but awful for display tech.
(Beam scanning lasers requires “single mode” lasers that don’t “hop” because the hopping turns into intensity/color variations in the beam scanning process thus making a noisy image.)
(I created a special screen for back projected displays that eliminates speckle by %100 by decreasing the longitudinal coherence lengths of the emitted light, the speckle generating mutual interference of wavefronts is also reduced completely.)
Image
If there is enough interest I can put the screens on Ebay and sell them that way for those of you that may want one.
Just let me know.


(3.)
It's 16 Bit color depth
The number of bits used to represent RGB values has nothing to do with colour space (except that using only 8 bits in colour spaces wider than Adobe RGB is a bit of a nonsense, as the steps between adjacent values are too wide).
16 bit vs 24 bit is never about extending the gamut, but always about increasing the number of possible pixel values within any given gamut. It depends very much on the image whether you’d see any benefit.
The only thing a higher bit path to the display would bring to the party is less banding and a lower dE between two similar colors previewed. Bit depth and gamut are separate entities (although the wider the gamut, the more reasons why you’d want a wider path).

(4.)
'Scan' lines.
The showwx does 480 progressive, but, it is shifting the scan lines VERY quickly to fill in the gaps. when displaying video, the scan lines moving around can be visible and distracting. This might work great at a higher refresh rate, but at it's native 59.9hz it doesn't cut it.
Use PowerStrip to up the Hz of the ShowWX+ to 72hz to reduce this visual artifact to an unnoticeable level.

flood
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Re: Laser projectors general?

Post by flood » 09 Dec 2014, 20:21

Light23 wrote: Laser speckle
Image
The laser radiation speckle can be...distracting.
With its grainy appearance and shifting pattern when you move like 1cm, it can be a problem.
The speckle issue is caused by the very narrow bandwidth of the lasers used. They have a lot of coherence with no mode hopping, which is great for holography but awful for display tech.
(Beam scanning lasers requires “single mode” lasers that don’t “hop” because the hopping turns into intensity/color variations in the beam scanning process thus making a noisy image.)
(I created a special screen for back projected displays that eliminates speckle by %100 by decreasing the longitudinal coherence lengths of the emitted light, the speckle generating mutual interference of wavefronts is also reduced completely.)
Image
If there is enough interest I can put the screens on Ebay and sell them that way for those of you that may want one.
Just let me know.
you mean like subsurface scattering?
that's pretty clever

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Light23
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Re: Laser projectors general?

Post by Light23 » 09 Dec 2014, 20:59

flood wrote: that's pretty clever
Thanks Flood!
Image

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Chief Blur Buster
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Re: Laser projectors general?

Post by Chief Blur Buster » 12 Dec 2014, 19:00

Light23 wrote:
flood wrote: that's pretty clever
Thanks Flood!
Very clever, too!
Eliminating laser speckle via subsurface scattering.

I am interested in testing out one of these laser projectors. Laser projectors have darn near zero persistence, like a short-persistence CRT. Laser projectors are completely blur-free (but very, very flickery at 60Hz). The thing that stops me buying one is their low resolution and low lumens, but I'm pretty interested in laser projector developments. I'll need to tweet about this technology in the near future, even if it's niche market.

Due to this extremely interesting niche, I've also added a link to this topic in the engineer-league "Area51". Worth further engineering for bigger, better laser displays, even for gaming -- possibly as a desktop rear projection box with a despeckling screen -- with some modifications to allow shallow depth projection, it would only need to be 3-4 inches thick for a 24" laser 1080p -- zero lag & zero blur! A manufacturer such as ASUS or BENQ could probably bring a laser gaming monitor to market before OLEDs are available!
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blargg
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Re: Laser projectors general?

Post by blargg » 12 Dec 2014, 21:59

Laser technology also seems such that it's quite approachable by the hobbyist. You need some laser diodes, a brightness modulator circuit (high bandwidth so perhaps tricky), an X/Y mirror (also pretty high speed), and an FPGA and CPU combination for the controlling software. It's nothing like trying to manufacture your own LCD panel, and you don't have to deal with lots of signal protocols, just the one from the source signal.

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sharknice
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Re: Laser projectors general?

Post by sharknice » 13 Dec 2014, 00:37

blargg wrote:Laser technology also seems such that it's quite approachable by the hobbyist. You need some laser diodes, a brightness modulator circuit (high bandwidth so perhaps tricky), an X/Y mirror (also pretty high speed), and an FPGA and CPU combination for the controlling software. It's nothing like trying to manufacture your own LCD panel, and you don't have to deal with lots of signal protocols, just the one from the source signal.
That doesn't sound like it would be very expensive either. It would be pretty awesome to be able to build your own laser projector.

Amalion
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Re: Laser projectors general?

Post by Amalion » 14 Dec 2014, 07:43

Light23 wrote: If there is enough interest I can put the screens on Ebay and sell them that way for those of you that may want one.
Just let me know.
Interested. How much would they be? Would you ship to the UK?

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Light23
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Re: Laser projectors general?

Post by Light23 » 20 Dec 2014, 03:49

Give me a week or so to get back with you on a price Amilion. ;)

My prototype screen is comprised of several elements of optically bonded films and glass. I WAS using Pilkington Optiwhite glass, rated at 0.91 for a 6mm thickness pane. (2 panes of Optiwhite results in 17% laser light loss)

My new prototype screen uses Amiran® anti-reflective 'Water white' glass.

"Water White" low iron glass gives color purity, with no green color cast like regular glass and has much less loss and reflectance than normal glass.
Which is great for the laser projector as I don't want any loss of light.
(I prefer the Amiran® because two panes results in only 4% loss instead of 17%.)

In between the two planes of Amiran® glass is a special homemade holographic optically vacuum bonded film along with another types of special film to create a dark screen for viewing in ambient lighting conditions and to de-speckle the laser light and create an ultra wide viewing angle screen.
On top of all this my monitor screen also contains an optical interference anti-reflective glass, dip-coated on one or both sides, with a residual reflection of approximately 1%.

Some pieces of my screen I outsource from other suppliers and some I make my own (Like the clear special holographic film) using my custom holography setup. All optically bonded to the glass with a brand-new vacuum bonding process that is the substitution of the current world wide used “wet bonding” technology. The VacuBond direct dry optical bonding, does not cause optical defects as scratches or moiré during the production process, which makes its use in my laser display screen perfect.

When I finish this last prototype I plan to house the screen projector/projectors and mirror set up in a this housing and size for optimal brightness.
Image
Image
The laser projectors face the back of the monitor, reflect off a 25.4mm Dia. (350nm - 1100nm), Precision Broadband Laser Mirror and shines back onto the screen. (This signal is mirrored in the Windows OS so that its orientation will appear to be correct to compensate for the mirror.)

I can sell the monitor housing including 6 RGB lasers, laser mirror & screen or just the the screen itself.
The monitor version will be 50 Lumens instead of the 15lumens of version 1. :D

So the details so far are:

Light23 Laser Monitor (v.2)
50 Lumens
75Hz
VGA connection
Anti reflective
High contrast
UltraWide viewing angle
Over 200% NTSC color gamut
100% No blur
No pixels , No burn in
Six lasers total in monitor version
Two blue lasers @ (450nm & 442nm) respectively
Two red lasers @ (638nm & 642nm) respectively
Two green lasers @ (530nm & 532nm) respectively
Widest color gamut monitor in the world due to 6 different wavelengths of lasers used

Image
Image

Will post updates soon...

flood
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Re: Laser projectors general?

Post by flood » 20 Dec 2014, 07:24

that's quite an elaborate stack...
you should note that since lasers are monochromatic, it is not as important to have broadband materials, if the final white balance can be tuned somehow

but how does it appear under ambient lighting?

also why 6 lasers?
Chief Blur Buster wrote:Laser projectors have darn near zero persistence
if the laser projector works by scanning a mirror, the effective persistence is basically the inverse of the pixel clock. i.e. <0.1us

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Re: Laser projectors general?

Post by Chief Blur Buster » 20 Dec 2014, 15:04

flood wrote:if the laser projector works by scanning a mirror, the effective persistence is basically the inverse of the pixel clock. i.e. <0.1us
Yep. It's a scanning mirror in the Microvision laser projector.

Assuming the beam spot size is no bigger than the diameter of pixels.
(In CRTs, beam spot can be bigger than a pixel, making things look fuzzy)

But that's a math rounding error far to the right of the decimal point. :D
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