Homemade Scanning Laser Color Projector/TV

[chipdouglas]

Blanking is basically turning the laser off so there isn't connecting lines. Go check out the laser shows section. There are some great tutorials and explanations.

 

[zmr]

Thanks. But, suppose SLTVM uses negative sync., than there will be no connecting lines??? :yabbem::yabbem:

 

[Bionic-Badger]

Thanks. But, suppose SLTVM uses negative sync., than there will be no connecting lines??? :yabbem::yabbem:

You don't need "connecting lines" between pixels of a "raster" laser display because the pixels are already adjacent. Blanking is used to keep the laser off for intermediate positions that shouldn't be drawn. If he's using a "real" TV-based output, he'll blank it when one horizontal line is drawn and the X position needs to return back to the left side of the image, just like a CRT.

 

[zmr]

That's exactly what I mean:

We don't need "connecting lines" between pixels of a raster.
But, we should keep the laser off during the back traces.
Now suppose that SLTVM uses negative sync.-TV based-video signal as an input to the laser driver, which consists of a single NPN transistor.
Then, laser will be automatically off during the back traces.

So, SLTVM blanks what?

 

[Bionic-Badger]

That's exactly what I mean:

We don't need "connecting lines" between pixels of a raster.
But, we should keep the laser off during the back traces.
Now suppose that SLTVM uses negative sync.-TV based-video signal as an input to the laser driver, which consists of a single NPN transistor.
Then, laser will be automatically off during the back traces.

So, SLTVM blanks what?

It probably just zeroes the output signal to the laser for the duration of the blanking, in the same manner that it is done in CRTs.

 

[sltvm2007]

Thanks for the discussion.
I accept that this point needs some explanation.
Since our fast mirror vibrates sinusoidally, laser traces a sinusoid.
That's why we should delete all odd(even) numbered lines and all odd(even) numbered fields.
This kind of blanking is somewhat different from the case in CRTs.

 

[clurado]

sltvm2007: Can you show us some higher quality with better view of your fast mirror construction ?!

i am interested to use polygonal mirrors , do you have some suggestions !?

is there any solution for fast scanning ?!

 

[sltvm2007]

Reply to clurado:

OK. I will try to take a closer picture.

I think that polygonal mirrors are good only for slow axis.
This point have been discussed in this thread.

As far as I know, Kuntman's fast mirror is the simplest solution for fast scanning.
Maybe you mean something else by "solution"!?

 

[clurado]

So how did you synchronize fast axis & slow axis with input composite signal ?! i think this is very important because non of galvanometer or the fast mirror are linear ? so how did you manage them ?!

 

[sltvm2007]

In this scanner we use a resonant fast mirror.
It is not linear, but it is finely tuned to the frequency of the input horizontal sync. pulses.

We also use a resonant galvo for vertical scanning, for simplicity.
If you like, you may use some nonresonant scanning method for slow axis.
At low frequencies synchronisation is not much a problem. It can be achieved by means of a feed-back control.

You will find below a closer view of the fast mirror of Kuntman's scanner.

 

[sltvm2007]

new! Block diagram: No blanking!

 

[sltvm2007]

New! Biaxial Mirror for Kuntman's Scanner

 

[KreAture]

I love this!
Finally someone with guts and skills

Just wanted to chime in and ask if this might be worth CNC'ing some tiny parts for.
I've been playing with biaxial mirrors and have a setup that may work. It needs some parts cnc'd though and now that my cnc is actually working I can finally do it.

Basically the mirror is fixed on a fiberglass caddy that pivots in both axis with a magnet underneeth. A set of SMD inductors are driven to pan/tilt the mirror. The whole thing is about 8mm accross with a 3-4mm mirror surface and a total weight of less than a gram.

 

[sltvm2007]

I love this!
Finally someone with guts and skills

Just wanted to chime in and ask if this might be worth CNC'ing some tiny parts for.

Sorry, I dont understand what you are asking me.
Will you please express it in a simple wording.
I also dont know what "guts and skills" mean. Is it an idiom?
Thanks.

 

[KreAture]

I think this is a advanced project and I am happy that someone wants to try it.

I have been thinking of doing this myself and so far I have only been playing with the x/y mirror.
http://kreature.org/projects/xy_laser/xy_galvo_1.png
Doing this in two dimensions works on my small tests but the mirror needs to be scaled down for speed. CNC cutting the tiny parts may work.

 

[sltvm2007]

Yes, the mirror should be scaled precisely and laser CNC cutting is very important.
While I was working for the university I made use of this technique.
But it is not critical; simple filing is enough for many purposes.