In this project, by means of two mirrors (which can be tilted about two perpendicular axis) we deflect the laser beam so as to scan a rectangular screen and modulate the laser source to obtain a colored image on the screen. We don’t make use of sophisticated devices such as MEMS micromirror and acousto-optical-modulators.

Advantages of our technique are:
- Total cost will not exceed 10 USD in mass production. (Mechanical part costs only few dollars)
- Low power consumption (Approx. 4 W.)
- Pictures can be performed on any screen
- No lenses are needed for focusing
- Scan head can be made as small as a cigarette box.

Max. speed of the fast axis mirror is 25 KHz. That corresponds to 50000 back and fro lines per second.
In order to make use of the conventional video signal, the resonant frequency of the present scanner is tuned to 15625Hz.
Therefore number scanned lines in each frame is 625. Refresh rate is 25 frames (50 fields) per second.
Vibrations of both axis are resonant, therefore sinusoidal.
Slow axis is driven by piezo.
Fast axis is elecromagnetically driven.
Laser modulation is analog.


15625 Kpps (15.625 Mpps) Color Projector/ TV:
http://www.youtube.com/watch?v=NTpwygS8baY

3D Visual Effect by Kuntman's Scanner:
http://www.youtube.com/watch?v=yRNsjvzmKRI

Videos:
http://www.youtube.com/watch?v=DmCzjv7Q20s
http://www.youtube.com/watch?v=HleDvzLk7SI



*********

kay... and how you do it?

really, i did have this idea some months ago too. my plan was to rip off the electronics from an old tv, the part beeing used to convert composite or component input signals into a picture. and then fire it with... yes, a MEMS. dont know anything else beeing capable to scan fast enough for at least PAL...

/ps: your cam has a really weird codec! even VLC refused to play it at the first try... worked after the 3rd

how are these 'vibrating mirrors' driven??

Are they just galvo's??


I guess I'll believe it when I see more of it... It's just hard for me to wrap my head around. *The scanning part doesn't make sense to me.

Also, as far as colors, you said the lasers were modulated by the video signal. Is this pulse width modulation (for color shades, say dark red and bright red) or is it just blanking (obviously not blanking because I see different shades of red) or is it like fading analog modulation?


Also, your resolution is only going to be as good as the beam size of your laser, unless I'm really missing something.

Slow axis is resonant piezo driven
Fast axis is resonant electromagnetic driven
Laser modulation is analog.

How does that go together

Am i getting this wrong or something. 100mW red, 100mW blue , 100mW green for 10 USD

How does that go together *

Am i getting this wrong or something. 100mW red, 100mW blue * , 100mW green for 10 USD * [/quote]
A little common sense goes a long way... :

I'm pretty sure he is only taking about the scanning device... 8-)


Jerry

Scanning part costs only few dollars.
I assume that the total cost will be considerably reduced in case of mass production.

I don't get it either *:-? Is it like Raster scanning, or is it scanning pictures that are TINY and then using a lens to blow them up ? I really doubt you could raster scan an image that size with HOME MADE Galvos, they would be far too slow.

Please explain this in a more simple fashion, with diagrams if possible.

-Adam


EDIT: the only way I can think of doing it is taking out the RGB cube from an LCD projector, and instead of using whitelight, splitting it up, and firing that through the LCDs on the RGB cube, you could use lasers. But if you used LCDs you wouldn't get all the lines going down the image due to the camera.

It would also be VERY difficult to get text as small as in one of your videos using lasers with "Galvos"

-Adam

so i did a bit research on your nice project. apparently you are searching for an investor for bringing your technology to the market. i dunno if you can find them here, this is rather a hobbyst board. but you could boost us to a new level of scanner diy building if you would share some details with us

ps: photonlexicon.com is a bit more dedicated to scanners etc...

hmm... Still doesn't make a whole lot of sense to me. If these motors are fast enough to scan tv that well (I assume it's 'rastering' the image) then I would think that laser projectors would be using this same technology but they dont. Galvo's are still the scanning method of choice. I would think if these are that much faster that they would be more widely used.

Also, how did you get such detail in the image? Do you have to adjust the laser's focus such that it is a pinpoint on the wall? with even a 2mm or 3mm beam, which is still pretty darn good, the image would look much worse because the laser spot just isn't small enough to do fine resolution.

This is why the 'laser tv' that is part of Pangolin's software has such low resolution, because anything higher just wouldn't work.

Also with 100mW of red green and blue, your colors are going to be wacky... You need like 100mW green 200mW blue and at least 400mW 660nm red to make a halfway decent white balance. Either that or you will have to turn the green and blue dowm considerably...

Galvos are designed to scan paths like i understand, making lines, curves, circles etc. They change their speed and angle dynamically and guide the laser beam point-to-point. His solution uses mirrors with fixed scanning speed; the laser dot starts in the upper left corner of the screen and then goes from left to right, one line down, and repeats. so it should look jsut like a plain light square. Making a visible picture of it is now up to the modulation, having to vary the lasers intensity exactly in sync with the postions of the mirrors.

Just like the cathode ray in an old CRT

Thank you very much for your kind interest.
I am not able to upload pictures into this forum.
You may see some photos in the public profile of sltvm2007 in the forum: photonlexicon.

you can use abload.de to embed pictures here... or get 6 more posts

Prior art for this type of thing used rotating mirrors, which worked well for linear (saw-tooth-wave) raster scanning.

Using resonance is a nice idea to keep the costs down and potentially improve reliability by eliminating rotating parts, but the problem is that it doesn't match standard saw-tooth-wave raster formats (eg: NTSC, PAL) without using a scan converter.

Without a scan converter, you can only display a small part of the standard raster image without considerable distortion.

This is the way how i will try it...

Galvos are designed to scan paths like i understand, making lines, curves, circles etc. They change their speed and angle dynamically and guide the laser beam point-to-point. His solution uses mirrors with fixed scanning speed; the laser dot starts in the upper left corner of the screen and then goes from left to right, one line down, and repeats. so it should look jsut like a plain light square. Making a visible picture of it is now up to the modulation, having to vary the lasers intensity exactly in sync with the postions of the mirrors.

Just like the cathode ray in an old CRT [/quote]


But that's just raster scanning, and you can't get high resolution with raster scanning, since the laser beam is 1-3mW wide usually, that's the size of your smallest pixel.

-Adam

When you think about it, any tweeter or other small speaker is capable of 15Khz very easily. As long as it's a concisely defined and repetitive path, it can be engineered without much of a problem. The part I don't understand is the modulation.

625 is on one axis, and assuming 16x9 ratio, 350 on the other. With a framerate of 25fps, your modulation speed would therefore have to be 5.5Mhz. That's 200-600 times faster than lasers I'm aware of.

No problem

LDs are fast enough.

Diodes maybe... but DPSS too?

No problem

LDs are fast enough.[/quote]


And you have Green LDs ? :

Also, the drivers can't go this fast too easily.

I'd really like to see a diode running at 5+MHz. Sure the diode can do it, but probably not the driving electronics.

I mean, 5+MHz AND it's modulating power... I dont know about that.

Even upon special request most laser manufacturers can only do up to 30kHz modulation... I've seen as high as 50kHz.

If it were using PWM modulation it would make a whole lot more sense to have such a super fast modulation rate, because that's how it works. But analog at a few mHz just doesn't sound right to me.

With respect to DVDs, 10.5Mbps is 1X and we've seen 22X. That's 231 million pulses per second (231MHz TTL). So why are no lasers (outside of optical drives) capable of more than 50KHz?

The lasers themselves are quite capable of modulation up into the MHz range, it's the drive circuitry that comes with them that is not. You could use a DPSS laser for high-speed data transmission if you wanted to, but the usual DPSS wavelengths are not the best suited for fiber transmission. Laser diodes are by far the most efficient, low-cost solution for high-speed modulation in fibers and consequently are the most common lasers to see being modulated at MHz speeds. Any diode is capable of very high-speed modulation, as well as any DPSS laser head, so long as the modulation circuitry can provide pulses at these speeds.

Isn't it so that DPSS has some sort of delays in the cristal which implay that it cant react that fast?

Not that I know of. Light typically propagates faster in solids than liquids or gasses, so the transmission through the crystal will still be plenty quick. When you consider the math, it would take one hell of a propagation delay in the crystal to cause issues modulating in the MHz range. I'm not sure just what the limits are, and there are limits, but DPSS lasers can definitely be modulated very fast. Stability in DPSS lasers during modulation is another matter, however. This makes them unsuitable for high speed modulation more than any propagation delay problems.

FrothyChimp is the man when it comes to this stuff, so I'm sure he could set the record straight.