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

[blargg]

As I understand it, VGA, DVI, HDMI, DisplayPort, etc. all send the image in the usual scanline fashion, thus there is no need for any lag for any format. The display buffer size determines lag. If it only buffers one scanline at most, then added display lag is at most a fraction of a millisecond. Particular monitors might buffer the entire image for some input formats, and only a scanline for others, thus introducing say a higher lag for HDMI over VGA.

[Chief Blur Buster]

What about input lag?

There's no scanout lag. It's real-time beaming from signal, laser scan has same latency as CRT scan.

[alex47]

There's no scanout lag. It's real-time beaming from signal, laser scan has same latency as CRT scan.

• incredible colors
  no motion blur
  sharp image
  no latency or lag compared to LCD

why isn't this mass produced yet?

[Chief Blur Buster]

the other issue is that the prism needs to be very well aligned. if one face is off by 0.1 degree, the resulting image will have every 6th line be displaced by 2 pixels or so

Hmm, that's true -- not sure how precisely multisided (even 100-sided) spinning mirror prisms are. Many high end drills spin at 100,000 RPM, and creating an accurate 64-sided mirror prism might not be impossible. This creates 135KHz (80,000 / 60 x 64). Rotational accuracy can be made very accurate with a laser reference on one mirror automatically determining the angle for the next mirror. Repeat when manufacturing subsequent mirrors, and then at the very end, you've got 64 laser-reference precisely aligned & verified surfaces. The fact it's going to be used for laser scanning means it could be manufactured with laser angle verification, creating far better accuracies than 0.1 degrees. But that may not be the best way to scan a laser...

There are many ways to successfully scan a laser at tens of thousands of times per second. Piezoelectric-driven mirror (e.g. ultrasonic mirrored surface).

Or DMD system, with multiple rows of Texas Instruments DMD running in parallel -- the same micromirrors used in DLP projectors. If 135KHz DMD is not possible with one mirror, you could pull it off with a linear DMD with multiple parallel DMD modulators pre-positioning themselves for subsequent scanlines (one DMD per scanline), and simply have a slower vertical mirror modulator running at vertical refresh rate. With 1080 mirrors (remember, we have millions of mirrors on a DLP chip) in a 1-pixel wide row, combined with one slow vertical refresh rate modulating mirror modulating 120 times a second, one could theoretically pull off a 135KHz. Manufacturing imperfections for each mirror may be challenging (e.g. if each pixel tilts at different speeds), but there must be known ways and workarounds.

It appears the Microvision uses a scanning micromirror inspired by DMD technology.

Or simply chaining multiple modulators with a modulator. Four 10KHz modulators running in parallel (1/4 phase offset) combined with a 10KHz modulator to round-robin-cycle between the four 10KHz modulators.

The Microvision is already doing 31.5KHz out of the box, so that's already a fast mirror modulator in a sub-$300 device. I imagine it would be quite doable to do a 135KHz laser modulator, if we're already doing 31.5KHz cheaply.

There's papers on successful 31.5KHz scanning as early as 2002, at http://proceedings.spiedigitallibrary.o ... eid=875686 .... By using a scanning mirror fabricated with DLP-style technology.

Google "laser scanning micromirror"

[Chief Blur Buster]

There's no scanout lag. It's real-time beaming from signal, laser scan has same latency as CRT scan.

• incredible colors
  no motion blur
  sharp image
  no latency or lag compared to LCD

why isn't this mass produced yet?

It inherits some of the CRT disadvantages:
- CRT flicker
- CRT nonlinearity/nonuniformity/disortions/parallelogram/keystone/pincushoning/bowing
- CRT misconvergence (red/green/blue fringing)
- CRT soft focus situations (blurry beam/astigmatism/etc)
- Thicker boxes than LCD/DLP (although much thinner CRTs)

It can bring a bunch of other issues:
- Dark lighting needed, if you don't want to limit resolution (e.g. use white screen / white film)
- Using RPTV style screens limits resolution (e.g. black lines on screen, to make screen more usable in bright lighting)
- Liability issues. Lasers bright enough for a bright laser monitor, will produce dangerous brightness if the laser modulator stops working in mid-scan. (Needs good instant shutoff if laser beam stops moving)
- Laser speckle, if not using despeckling film

However, it does eliminate a lot of CRT limitations:
- Higher DPI is possible than CRT
- Color gamut is much bigger
- Not limited to CRT tube size
- No focussing for different throw distances needed (can be sharp focus at near/far throws)
- More bandwith is doable with laser than with CRT. Optic fibers modulate lasers very fast.
- Much smaller box sizes than a CRT tube or RPTV
- Far more lightweight than CRT
- Theoretically could be a 24" size 4-inch-thick transportable gaming monitor via a lens and some beampath folding.
- Lower persistence than CRT. Especially the Sony GDM-W900

We'd easily be able to blow away the Sony GDM-FW900 CRT in virtually all aspects.

In addition, today it is now easier to create a homebrew laser projector than a homebrew CRT (plus for electronics geeks). The components, including some of the laser scanning micromirrors, are off-the-shelf from various component suppliers.

[Black Octagon]

I'd by it if you made it, Chief:)

[flood]

- CRT nonlinearity/nonuniformity/disortions/parallelogram/keystone/pincushoning/bowing
- CRT misconvergence (red/green/blue fringing)
- CRT soft focus situations (blurry beam/astigmatism/etc).

these are far smaller isssues for lasers. bending light with mirrors is far easier to control than bending electron beams with coils.

the existence of dichroic mirrors should allow for the three beams to be perfectly aligned giving perfect convergence

[Amalion]

In order to advise anyone else considering it:

I picked up one of the Seeser projectors mentioned upthread, from ebay. The projector engine works, as does the bizarre Android OS installed on it, but it resolutely refused to display any VGA external source that I tried (sat on its "waiting for source" screen and ignored the signal), and I can't find any troubleshooting material online. So I'll be trying to get a refund, unless anyone has advice.

It also has a very loud and obnoxious fan. Does anyone know whether the Microvision unit of which it is a clone also had a fan?

[TimothyLottes]

848x480 (50 Lumen) 2 VGA imputs
The next prototype will be 2560x1440 HD 16:9 100 lumen 1 HDMI imput (Requires Warpalizer software) 4 way HDMI input/output converter will be built into the monitor.
I hope to build several different models at different AFFORDABLE price points and resolutions.
But the cost of these materials is high. Maybe I should Kickstarter this. lol

Awesome project! I'd also be interesting in getting some idea on pricing. I'm more interested in the lower resolution (1920x1080 or lower) and if possible, higher framerate options.

[rabidz7]

Could you do a 4:3 version of the next monitor?