New 250mW from Laserworld components

[greenalien]

I've just completed my latest laser project. All the major parts - scanners, diode and DAC/Software were bought via Ebay auction from Laserworld.
The idea was to build the entire system inside a 2-U flightcase, bought from CPC. After 10 years of lugging an Argon rig with a massive power supply around, portability was a key issue!

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Here's all the bits assembled onto a 1-U half width rack shelf - I used this because I already had it available. It needed beefing up with a length of 1/2 x 1/2 ally angle to stop it flexing too much.

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ILDA 30k test pattern - close up of centre section. Galvo tuning has to be done with the mechanics outside the case! This is as good as I could get it after an hour or so's adjustments.

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...and the full ILDA test image. Galvos are rated up to 45K but I'm running them at 30K, should do for most things I want.

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Rear of case, showing ILDA connector and key switch. Pic is a bit dark but 2 filtered fans are also fitted. Electronics run pretty cool, so these aren't really needed, but keeping the interior at a slight positive pressure with filtered air should stop smoke fluid residue from getting in. Mounting clamp is removable, fits to a captive nut welded onto a flat bar bolted under top of case.

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And finally, front view. Aperture is covered by 82mm 'coated digital protection filter' got from Ebay.

[allthatwhichis]

Nice!



I like that case. How hard was it to convert? Do you think there'd be enough room to go multi color? I bet a mazuxmodule'd fit, but I'm not sure about a blue from the pics.

buffo should be posting a scanner tuning tutorial here soon that could get that pattern looking nice and tight. Nice work though.

[mliptack]

I agree, that looks great!

Just one word of advice, I see your label on the back says 250mW as the maximum output, but if your laser is rated at 250mW then it most likely is a bit over that. You should probably put 300 or 350mW on there just to be safe.

my 2 cents
-Max

[greenalien]

I like that case. How hard was it to convert?

Case was obtained from :
http://cpc.farnell.com/jsp/Audio,+Vi...questid=468970

(note that this is a special price until 28 December, or until stocks run out. Usual price is £39.95 plus VAT.

No conversion to the case apart from fitting the captive nut for the hanging coupler. Front and rear panels cut from 3mm alloy plate bought from a scrap yard (used to be a signboard). Fitting screws supplied with the case. 82mm 'digital protection AR filter' obtained from :
http://stores.ebay.co.uk/DIGITAL-iSH...Q3amesstQQtZkm

The parts are all fitted onto a rack tray that only half-fills the case, so there is lots of room inside; could be the basis for a full colour system if the laser modules and power supplies aren't too big.

The only issue with getting the 'works' in and out of the case is that the connector for the 'Y' galvo needs to be rotated down to give enough clearance. This means removing the front filter to give access to the clamp screw. The filter is just a press fit at present, however, I have a cheap 82mm uv filter from which I intend to remove the glass; I can then epoxy the outer ring in the aperture and screw the AR filter into that.

I'm very pleased with the portability of the package, there's enough room in the case ends to stow the clamp and cables, and once the ends are clipped on, everything is nicely protected - and I can carry the laser in one hand and my laptop in the other!

I'm generally happy with the precision of the image but would like to get the circles in the test pattern completely circular rather than oval.

I am now seriously considering getting a 1W module with analogue blanking to replace the current module, which is good but only has TTL blanking. I'd rather be able to adjust the power more precisely.

[buffo]

I'm working on a scanner-tuning tutorial based on the mini-class that Bill Benner put on for us at FLEM 1.5. Unfortunately, the video for that class didn't turn out very well at all. But I hope to have at least some still pictures and a nice write-up that one could follow.

Don't know when it will be done though... Time, always time! But when it's done I'll post details here. It might be enough to help you tweak your scanners in a little tighter.

Still, your projector looks great! I'm a little curious about the enclosure you used - did it not come with front and back plates, or did you replace them with your own material because you wanted something thicker?

Based on the case dimentions listed on the website you linked to (19 inches wide by 14 inches deep) there would be plenty of room in there for a full RGB table... The only real sticking point is the narrow height. It looks to be only about, what, 6 inches tall? (I couldn't find the height listed on the website.) That might make things a little cramped, but it's still doable. (My RGB optical table is only 9 inches by 14 inches...)

Adam

[greenalien]

The case didn't include front/back plates, (but it does have front and back 'lids', which have neat butterfly catches to fix them on with; unfortunately not in the pics) but not difficult to make my own. I learned something new in the process - provided you use them in a drill press and go gently, with a little lubrication, you can persuade hole saws that were intended to cut wood to go through Aluminium alloy!
Regarding scanner setup, I'm attaching a copy of the instructions for my scanner set which has some basic tuning suggestions included - I'd be interested to see what the experienced group members have to say about them!
LW-45K-en_neu.pdf

[buffo]

Those instructions are really basic, and don't tell you what to look for when you're tweaking things. LaserFX.com has a good article that goes into more detail about how to tune your scanners. That site also has a decent explanation of what different parts of the ILDA test pattern actually test for.

Adam

[greenalien]

Adam - thanks for that info, much better than the supplied brochure. I hope to find time next week to see if I can get the tuning a bit tighter - the main thing I'd like to do is get the centre circle of the pattern completely circular, rather than oval!

[buffo]

You should be able to get there... You're very close already.

Couple things: When you increase the servo gain, the circle will get larger. Adding damping will make it smaller.

When you increase the servo gain, you'll see "overshoots" on the corners of the square that surrounds the circle. Watch those corners carefully. You want dots at the corners. If you see lines extending past the corner, add low-frequency damping to bring the line back to the dot.

Once you get the gain up high enough, you'll find that after you add enough low frequency damping to bring the overshoot line back to the dot on the corner, you'll then have some "undershoot", where it looks like the line is re-tracing back behind the corner a little bit. Add a little high-frequency damping to bring that under-shoot back to the dot on the corner.

If you have the lasermedia test pattern (looks like a diamond inside of a square with the 4 corners of the diamond touching the middles of the sies of the square), you can use that to verify that each scanner is running at the same speed. Look at the diagonal lines on the top left and bottom right of the diamond. If you see one solid line, you're golden. If you see two lines, then you need to tweak the gain on one of the scanners until the lines overlap perfectly again. (Yeah, then you'll want to go back to the ILDA test pattern and tweak the damping a bit... You may have to go back and fourth a few times to get it perfect.)

I noticed that you're using the version "B" of the test pattern to tune with. While that will work, I had better luck using the original pattern. (The one that doesn't have the huge square outside of the rest of the pattern.)

You have to remember though that when tuning with the original pattern you can't have your image size set at 100%. Depending on the scanners you have you'll want to be down around 15 to 30 % of full size. (Which should correspond to a scan angle of around 8 to 15 degrees.)

When I use the ILDA pattern, I first reduce the image size to near zero. (Your laser show software should have a control for this.) Then I slowly increase the image size setting until the circle in the middle of the pattern stops getting larger. I back off about 1-2 %, and that's where I tune at. (Remember that the scanners are ballistic when drawing that inner circle, so they should be moving as fast as they can. When you reach the point where the circle stops getting bigger, you've reached the limit of your scanner amps.)

Based on the picture you posted, I'd start with your X galvo first. Add some servo gain and see if you can get that circle looking better... Then play with the damping controls as explained above.

Adam

[greenalien]

A little more info on the aperture , that I finished off last night.

I bought 2 different 82mm lens filters from Ebay. The first one was a cheap Hoya UV filter - 99p plus £4.99 P&P from :

http://stores.ebay.co.uk/DIGITAL-ACCESSORIES-CENTRE

Note that this filter has both external and internal screw threads.

The second one was an AntiReflective coated 'Digital Protection' filter
Kenko 82mm PRO 1 Digital MC PROTECTOR Filter F71

bought for £11.99 plus £5 p&p from

http://stores.ebay.co.uk/DIGITAL-iSHOP

Having cut the aperture in the front plate to be a close fit on the outside thread of the first filter, (hole saw, then careful filing!) I then dismantled the filter (using a pair of dividers to unscrew the thin locking ring that secured the UV lens), discarded the glass filter and locking ring, and epoxied the threaded ring into the front plate.
(the glass on this cheap filter has no AR coating, so reflects too much light to be used as a laser aperture cover).
Once the epoxy had set, I was able to screw the Kenko AR filter into the fixed ring. This means that I can easily remove the AR filter for access to the galvos without removing the front plate, and the whole thing looks very neat. With the laser running, the amount of back reflection is minimal so the AR coating does its job well.