Homemade Scanning Laser Color Projector/TV

diachi said:

It's not the coatings that's the problem, the problem is the driver. The driver creates a wave in the crystal which changes the crystals properties at certain wavelengths, if the driver is at an incorrect frequency then it can't modulate at that wavelength.

-Adam

Click to expand...

Wow! you learn something new every day. I always just assumed that the coatings were responsible (and I still do think they matter a little in terms of losses) but given how AOMs work that makes perfect sense...

So this means you cant just use any AOM and maybe even not a for-multiline one, cause the freuquencies must fit your lasers exactly?

we should get back to the cheaper lcd blanking idea

As far as I know you could use the same types of AOMs that are used in high-end RGB systems. I'm not sure that an LCD would be able to keep up, although it might. Typically, 1-2ms response time is EXTREMELY good for an LCD, so there's no way that 1MHz would be possible. At most, 1-2kHz. AOMs of this type are very expensive currently, but if they were integreated into laser TVs then the price would come down due to higher demand and the lower costs associated with mass production.

So you say whe must design a working prototype first and throw it on the market before everyone will be able to build it diy with our help? paradox but logical.

Apropos DLP - will it create speckle/interferency when firing a expanded laser beam on it?

The concept of a truly useful DIY laser TV is uncharted waters for the most part. The closest that has been done with good color distribution and decent picture quality is RGB raster imaging using a relatively normal RGB scanner setup, but the resoloution is nowhere near what most people would consider "television". This entire thread so far has been just speculation about the types of technologies and techniques to use in such a project. If you want tp build a DIY laser TV, then judging the practicality of such a project is up to you. What I can tell you is that short of some real ingenuity, the costs outweighs the outcome in most cases. The real ingenuity would come from the mind of whoever decided to undertake the project. If you were to invent some new methods of doing things, the project could suddenly become a much more realistic goal..

Regarding DLPs introducing speckle noise, personally I have no idea. Someone here may know more, but I doubt that many people on this forum have used lasers and DLPs together in their hobbyist projects..

Homemade Scanning Laser Color Projector/TV---Green Laser Modulation

As can be seen from the videos of sltvm2007 in Youtube, high speed modulation of a green laser is possible without an acousto-optical-modulator. However, modulation of a DPSS green laser is not easy because of the very narrow dynamic range of the crystal. Besides some modifications on the optics, LD current should carefully be adjusted in order to protect the DPSS laser.

However, before experimenting on the modulation of LDs, a hobbyist should have a high speed scanner. A relatively slow scanner with a 5-10 Hz slow axis mirror and few kHz fast axis mirror would be good for beginning.

Good luck!

You are speaking of "modifications on the optics" of the green LD ... what did you to yours?

Very cool

Very cool!

THEORY of OSCILLATIONS


Before beginning to make a scanner we need a little physics.

According to the theory of small oscillations

6.28f= sqroot(k/I)


"f" is the freq of oscillations
"k" is the force constant of the restoring force
"I" is the moment of inertia of the system


Therefore for greater "f" we need greater "k" and smaller "I".

"I" depends on the shape of the mirror and also how it is pivoted.

_______________________________________________________
SLTVM: Simple Solutions for High Speed Scanners

"NO MEMS, NO AOM"


VIDEO:
[highlight]youtube.com/watch?v=NTpwygS8baY[/highlight]


PHOTOS:
[highlight]photonlexicon.com/forums/album.php?albumid=104[/highlight]

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^well, duh! But seriously, while I have a great deal of respect for true DIYers, wouldn't it be simpler to use commercial galvos?

As far as I know, commercial galvos are suitable only for the slow axis (vertical scan).
You need a very fast scanning mirror for the horizontal sweep.
In our project, frequency of the horizontal mirror is 15625 Hz; so tuned to scan the video signal coming from a DVD player.

______________________________________________________
SLTVM: Simple Solutions for High Speed Scanners

"NO MEMS, NO AOM"


VIDEO:
[highlight]youtube.com/watch?v=NTpwygS8baY[/highlight]


PHOTOS:
[highlight]photonlexicon.com/forums/album.php?albumid=104[/highlight]

* * * ** * *


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How can we calculate the moment of inertia of a circular mirror?


Moment of inertia of a circular mirror with respect to an axis passing through its center is given by the formula:


I=mrxr/4


"I" is the moment of inertia of the system
"m"is the mass
"r"is the radius

This means, for smaller "I", "m" and "r" should be made smaller.

_______________________________________________________
SLTVM: Simple Solutions for High Speed Scanners

"NO MEMS, NO AOM"


VIDEO:

http://www.youtube.com/watch?v=NTpwygS8baY


PHOTOS:

http://www.photonlexicon.com/forums/album.php?albumid=104

**********

What are the dimensions of your mirrors?

radius of the slow mirror is 6mm,
radius of the fast mirror is 1.5mm
___________________________________________
SLTVM: Simple Solutions for High Speed Scanners

"NO MEMS, NO AOM"


VIDEO:

http://www.youtube.com/watch?v=NTpwygS8baY


PHOTOS:

http://www.photonlexicon.com/forums/album.php?albumid=104

**********

Thanks,

What are the mirrors made of?

Hard disc material is good for mirrors.

___________________________________________
SLTVM: Simple Solutions for High Speed Scanners

"NO MEMS, NO AOM"


VIDEO:

http://www.youtube.com/watch?v=NTpwygS8baY


PHOTOS:

http://www.photonlexicon.com/forums/album.php?albumid=104

**********