First Scanner (RGY)

[Steve Milani]

I chosen to place an additional plate, adjustable in height by filleted bars, under each component.
This is the easier solution.

All the best

Steve

[Mille]

Ok a little update on my scanner with some picture too





This is the scanning working in progress
I've setted only the optical elements.
The other stuff is only positioned without screws and nothing.



And this is the control "temple"

I have a question: i noticed that green laser seems to be underpowered when is set to idle for some time.
If i use frames with only red (or just a little green) for a while, right after that the yellow frames is more toward orange, and become a bright yellow only after some seconds (maybe a minute).
Is this common?

[Steve Milani]

Nice!
You're on the right way!
It seems a very clean setup also.
Remember.. hurry is the worst enemy.

Good job Mate!

[Dr Laser]

I was always wondered why there is a need to invent a new circular wheel.
There is a perfect and simple lasersetup. And remember :every beam bending will cost you power.


Plus those adjusting platforms will not be steady enough and will not allow proper cooling!

[Mille]

I was always wondered why there is a need to invent a new circular wheel.
There is a perfect and simple lasersetup. And remember :every beam bending will cost you power.


Plus those adjusting platforms will not be steady enough and will not allow proper cooling!

Cool... all that info would have been usefull some week ago when i asked some tips in building the scanner

Btw i took some pictures of the ilda test pattern.





How do you think is the galvos tuning?
I'm oriented to do beam shows more than graphics...
Theres some geometrical correction (the sides are little bent)

[Steve Milani]

Uhm...
I see...
This is a job for Adam (Buffo)...
I think nobody can help you better then him

[buffo]

I have a question: i noticed that green laser seems to be underpowered when is set to idle for some time. If i use frames with only red (or just a little green) for a while, right after that the yellow frames is more toward orange, and become a bright yellow only after some seconds (maybe a minute). Is this common?

Yes, unfortunately it is common. It's most likely caused by "jellybeaning" of your green laser. DPSS lasers (especially ones with inexpensive drivers) sometimes exhibit power fluctuations when they are modulated rapidly. The problem is related to poor feedback on the tec controller and a failure to keep some "idle" current flowing through the diode (below lasing threshold) when the laser should be off. The solution is to replace the driver module. (This sometimes means buying a whole new laser.)

There is a partial solution you can try, however. Bill Benner published a schematic for a "color smoothing and delay circuit" that you could install on your red laser. This will delay the modulation of your red so that it more closely matches the rise time on your green. That, coupled with a better green driver, should eliminate your problem entirely.

I was always wondered why there is a need to invent a new circular wheel.

Because of a hundred other variables that apply to a hobbyist-built projector that don't apply to one made in a factory. Such as, not wanting to have to machine custom shims for each laser to get the beam heights right, and not wanting to deal with the hassle of flaoting tables, so deciding to add an extra bounce to each beam path and doing the alignment with mirror mounts instead. Or having the perfect case (for free) to use for your projector, but it's too narrow to fit the lasers in the classic side-by-side arrangement shown in your picture, thus requiring some other layout.

And remember: every beam bending will cost you power.

In that case, why do you have the green laser bouncing off a mirror in your picture? You could mount it sideways (parallel with the main beam path) and omit one bounce! (Just like my original RGB layout.)

Eh - rules need to be broken once in a while, either to make the design easier to build, or to make it fit, or for any of a number of other reasons. And really, if you have good mirrors, you'll only lose around 1% per bounce on a first-surface mirror. That's an insignificant amount of power. Adding a couple extra bounces (to make alignment a snap) is a good trade-off, assuming you have the space in your projector.

Plus those adjusting platforms will not be steady enough and will not allow proper cooling!

I disagree completely. My new projector has platforms of roughly the same thickness and they are *rock* solid. Even after the projector bounced around in the back of my jeep for over 9 hours, the alignment never moved. (And I've recently checked my alignment over a 400+ foot throw, so I mean it when I say it's spot-on.) The key is having the floating tables mounted to a baseplate that won't flex. The lasers themselves can be mounted on thinner plates because the weight of a single laser is not enough to bend them.

Likewise, cooling is not affected by the amount of thermal mass, but rather the surface area. He'll be just fine without any forced air movement on that layout up to at least a half watt of total output, based on my personal experience. I've built two other projectors that had similar layouts with no problems (and no forced air cooling either). More power than that and he might need to add a fan to blow under the floating tables, but he'll still be just fine.

Finally, back to Millie's scanner tuning. I need to know what angle you're projecting at, and at what speed. Looks like you're either scanning too fast or too wide. Otherwise tuning looks reasonably good. Before you tweak anything though, we need to be sure you're in the ballpark for your scanners.

Adam

[stanwax]

Plus those adjusting platforms will not be steady enough and will not allow proper cooling!

I addition the laserwave module with the internal fan can be operated all day long without a heatsink as all the cooling is self contained

Rob

[Mille]

Finally, back to Millie's scanner tuning. I need to know what angle you're projecting at, and at what speed. Looks like you're either scanning too fast or too wide. Otherwise tuning looks reasonably good. Before you tweak anything though, we need to be sure you're in the ballpark for your scanners.

Adam

The scanning speed is 20k... if i reduce it some the circle in test pattern is kinda matching the square.
I don't really know about the scan angle: do i have to misure the distance from wall and the side of the image?

[buffo]

The scanning speed is 20k... if i reduce it some the circle in test pattern is kinda matching the square.

Yeah, that's to be expected. Ok - so you've got ScanPro20's and your running them at 20K. Good. Now we need to look at the scan angle.

I don't really know about the scan angle: do i have to misure the distance from wall and the side of the image?

Yeah, you do. Here's a link to a chart that will help you calculate your scan angle. Basically you measure the distance from the scanners to the wall that you're projecting on, and then measure the width of the pattern.

Here's a quick way to check: Divide the distance by the width, and multiply by 100. If you get a number larger than 14, you are scanning too wide.

The ILDA test pattern is designed to be scanned at 8 degrees. Some scanners can manage a few more, say 10, or even 11 degrees, but if you scan it too wide, the center circle will not touch the square and you'll see other artifacts start to crop up.

Set your scan angle to 8 degrees and take a picture of the ILDA test pattern. Then take a picture of the LaserMedia test pattern. Finally, reduce your scan angle to 5 degrees and take another picture of the ILDA test pattern. That will tell me a lot.

Adam