Advive about knife edging after cylinder correction

[-bart-]

Only thing I could think of, is the accessibility of the dichro-mount adjustments.
Recollimating can be done before or after the right-angle mirror.

There are multimode-fibre-slip ring solutions
But I don't know how they handle power, and what polychromatic problems arise.

[danielbriggs]

Have you got adjustment on at least one of the sides of the periscope? Top might be easiest?

[kitatit]

Only thing I could think of, is the accessibility of the dichro-mount adjustments.
Recollimating can be done before or after the right-angle mirror.

There are multimode-fibre-slip ring solutions
But I don't know how they handle power, and what polychromatic problems arise.

You're a bad man Bart Yikes! I shudder to think of the price for those babies.

Yes it is a little tight around the dichro mounts. There is counter bored recesses in Dave's mounts so the socket head screws don't stick out much.

Baby steps, I've got to learn the fundamentals first. I'm going to try the knife edge first approach slicklasers suggested.

I might have some more question about re-collimating the the beam if it still need tweaking.

Thanks for your help Bart

[kitatit]

Have you got adjustment on at least one of the sides of the periscope? Top might be easiest?

Hi Dan

Not as yet. Those parts don't exist yet. I'm going to get them 3d printed. I'm trying to keep the costs down and also eliminate as much machining as possible. Most of the parts in this project are water jet cut.

I kind of have the gut feeling of this approach(Beam through the motor shaft) being unviable but hopefully it will work.

The motor is well made and has nice machined aluminium end bells with mounting holes. I'm hoping i can rely on the the rear end bell being square to the shaft centre. There wont be any mechanical load on the 3d printed parts so i'm going to go for a plastic that is more precise over more strength. Hopefully the laminated layers crate a nice 45deg surface to glue the bounce mirror on.

[planters]

I don't think the 5mm will be too daunting as long as the motor can be shifted a couple of mm up/down and right/left. It does not matter when you knife edge in terms of the beam size x beam diameter product, but it matters a lot that the telescopes are dedicated to each diode like you have them. This allows the highly diverging and usually slightly rotated relative to each other, beams, from the P73 collimators to be focused and corrected. I would spend a little more and PBS each diode pair instead of knife edging. This will allow you to produce the same divergence with a beam that is 1/2 as wide.

Oh, and use the smallest socket head screws that you feel confident tapping. Avoid button heads when this small as they strip when tightening. But if small, these screws will allow some shifting of Dave's mounts left to right as well as in and out.

[dnar]

Kit, you mad scientist you! All I can say is wow. That and I hope Cindy gets some of your attention too.

Looking forward to seeing this in action....

[kitatit]

Hi Kit,

Just a quick comment. I wouldn't waste your money on a hollow shaft motor and just build a pair of pillow blocks and machine something up and spin it via a little belt and motor. You have the skillz and the tools so make it how you need it.

chad

Hi Chad, sorry I missed your post before. Thanks for the props!
The manufacturer of the motor, spark eroded the hole in the shaft for us and while only buying 2 sample they were still very reasonably priced. They are 24v dc brushless and have integrated drivers. It runs at 3000rpm and is quiet as a mouse. I hadn't considered your approach. I'd be worried about vibration and noise if i used belts anywhere near that speed. Also While I can machine the parts, I have limited access to machines these days and I'm almost never home any way. After spending so much on machined parts on my projector I am going mostly with waterjet cut parts in this project to reduce machining operations. It has got me thinking though. I had a plan B that was a compromise I'd rather not make. Your idea is better. It's my new plan B if this doesn't work. I did some rudimentary tests and it's not looking too bad.

I don't think the 5mm will be too daunting as long as the motor can be shifted a couple of mm up/down and right/left. It does not matter when you knife edge in terms of the beam size x beam diameter product, but it matters a lot that the telescopes are dedicated to each diode like you have them. This allows the highly diverging and usually slightly rotated relative to each other, beams, from the P73 collimators to be focused and corrected. I would spend a little more and PBS each diode pair instead of knife edging. This will allow you to produce the same divergence with a beam that is 1/2 as wide.

Oh, and use the smallest socket head screws that you feel confident tapping. Avoid button heads when this small as they strip when tightening. But if small, these screws will allow some shifting of Dave's mounts left to right as well as in and out.

Hi Eric, Thanks for the clues. I have some cubes but I haven't used them yet. I did think of them but was thinking they might be a bit fiddly to use. I'm showing my inexperience here. It bugs me I am home so little to get hands on experimenting time. I really need to make it a priority. Nothing beats a real experience. Hmm I can't remember which cubes I have. i think they were broadband coated.

After slicklaser suggested knife edging the beams before the cylinders I drew up a layout like that
I thought it was nice being able to eliminate a pair of cylinders. I haven't got to try it yet. I only got up to setting up one diode with correction.
As my beam terminated at 2.8m from the aperture, and I wont need very accurate far field alignment, is it still worth it to use dedicated correction for each diode?

With the quick play I had with the Osram PLTB450 blues I think I won't even bother correcting them as they seem pretty good at 2.8m with one of DTRs 3 element lenses. I got 405g2 as well as 405g2 long focal length but didn't have time to try them.

Here are some pics of a single P73 going through the 5mm motor shaft. As you can see, it was a rough and ready test with the motor positioned with bluetack but it lost less power than I thought.

And thanks to my lovely assistant Cindee, here is a pic of the P73 beam after going through the motor shaft. Sorry the shot is over exposed, I was in a rush. She was smiling here but I could see the "Hurry the #@*% up and stop playing with your lasers, it's dinner time" caption above her head

Kit, you mad scientist you! All I can say is wow. That and I hope Cindy gets some of your attention too.

Looking forward to seeing this in action....

Hi Wayne, mmmMMMMWWWWOOOHHAA, it's almost alive!!
Yes Cindee gets plenty of attention, how could I not. Two of my loves in one room. If only she was more interested in my lasers. She was quiet good at driving Live Pro when we had a small back yard party for NYE though.

I've booked a couple of weeks off when I'm back in August would be good to catch up.

Cheers
Kit

[LaNeK779]

hey kit, are you sure the 2mm lens is facng the right way in the lens barrel?
that red line to the left of cindee on the white wall is troubling me a bit

(heh, that should keep him worried for about a month)


i'm looking forward to see what you are about to spin with that motor. you did have a machado grating didn't you?
but at 3000rpm the effect will be hmmm... interesting..

take care, keep us posted

[planters]

I wont need very accurate far field alignment, is it still worth it to use dedicated correction for each diode?

Yes. Because as you say it would allow you to eliminate a pair of cylinders that is why it is less frequently used, but it makes a big difference and is only worth doing with the very divergent P73 and G71 diodes. I suspect the red line mentioned by LaNek779 is from the wings of the P73 reflecting off the inside of the motor shaft. You won't want to add the complexity of a spatial filter before the shaft that will completely eliminate them, but you should see what a good anti reflection, black ink inside the shaft will do.

[dnar]

Kit, what? You had a laser NYE party and didnt invite me? WT?

A catch up is overdue, but please be aware I wont be in town in August... Yet to be announced, I have received a promotion. I am now also managing our export business, so August has me in Sydney for the Integrate show, then to Mumbai for new product signoff, followed by Dubai, Qatar, Oman, Paris, Germany, Norway, Amsterdam and London. All up a 4 week business trip. Maybe late Sept?