Microvision laser projector

[sbk]

This new technology seems very promising, despite I see at least two downsides which would temper a lasershow use : first the 510nm wavelength is half as bright as 532nm (and that's not a very true green), and secondly the power we could reach with these don't seem as powerful as the recent blue diodes... Maybe we would be stuck to combine a lot of diodes to obtain bigger power, like we do for the red ones... But wait and see

BTW, how's performing your Lasever 1W 532nm Pascal?? Je pense qu'il a encore une longue vie devant lui avant d'être remplacé par une diode verte native

[Stoney3K]

I get a small issue with the showwx+, I just noticed that the green output is slightly noisy, from unpacking, I can see slight horizontal lines on all white background, on Windows/VGA.

I get small power variations on the green laser, like a "superimposed white noise" of low/medium frequency.

The green is a DPSS, which has been shown to have the tendency to mode-hop when modulating. Since you're modulating it with a high-frequency signal like video, it's not unthinkable that the doubling crystal will just barf at it and modulate terribly bad.

Just to prevent any terminology disputes: The diode is a direct-pumped doubled laser. The lasing *still* happens inside the doubling crystal, so technically it's a DPSS. Furthermore, it's well-known that the temperature variation of the doubling crystal will cause lasers to vary in power and hop modes.

I wonder how these Osram green diodes will end up.

[-bart-]

I doubt the dpss is modulated with video-data.
I am sure that the micromirror device does this.

[shrad]

like early television, you raster-scan X and Y on the mirror with a dual ramp, synchronized with the framerate you need at the resolution you need

then all you have to do is modulate the colours separately with the video signal and nothing more

the colours are "separated" as they are multiplexed in time along the raster scan, like one line green, one line red, one line blue, next line, ...

it's the reason the resolution is so small on those... be it black and white and you double the resolution

it's also the reason you can adjust the image position for each colour, it just slightly modifies the X/Y ramps during the colour scan time

[-bart-]

I stand corrected, it's actually one scanning mirror.

In theory it could be adapted to have an ilda port

[Serveurperso]

I'm pretty sure, the MEMS have only one working frequency (because is a self-resonant, and same frequency for all supported video mode), all lasers work together to make the white, and the green is not a DPSS but a very fast direct SHG switched to make all video line.
Video is interlaced as CRT because is known on the web (high speed camera filming found on youtube) and iphone display is fluid as NTSC on CRT.

Regards

[Stoney3K]

I'm pretty sure, the MEMS have only one working frequency (because is a self-resonant, and same frequency for all supported video mode), all lasers work together to make the white, and the green is not a DPSS but a very fast direct SHG switched to make all video line.
Video is interlaced as CRT because is known on the web (high speed camera filming found on youtube) and iphone display is fluid as NTSC on CRT.

Regards

It's still a frequency doubled laser. These are known to cause trouble with bad modulation characteristics if the temperature is not kept stable enough.

The fact that there's no YAG producing 1064 pumped from 808nm doesn't mean the problem goes away. We've had lots of trouble keeping a KTP crystal stable when it comes to temperature, and I suspect that may be causing the problem on this Microvision as well.

[Serveurperso]

I forgot to say that almost unvisible after a few minutes of operation!