New Projector Taking Shape...

[Jem]

Hi All

Well, it's been a steep, but very interesting, learning curve making the move from using lasers to make holograms to using lasers to make a projector. But thanks to all you folks on this forum who have given help and advice my projector is finally taking shape.

I realise that some of my early questions may have appeared rather silly to those more experienced than I, but all were relevant to me at the time and all have helped me reach this stage.

O.K., so, i'm a long way from getting it finished and it's not very tidy as yet, but hey, it works

I shall now take it all to bits again, bolt everything down firmly and tidy up all the wiring. In other words, build it properly!

What do you folks do to get all the beam heights to match correctly? Do you use aluminium shims pasted together with heat transfer paste? Or is there some other magical way of doing it?

Anyway here's a few pictures I took along the way, please forgive me if they are out of order, i've not quite got the hang of posting pictures as yet.

Since I took the photo's i've attached the Galvos (DT40Pro's - Thanks Jian for help and advice!) and powered it all up.

Cheers

Jem

P.S. Any comments, suggestions either good or bad are most welcome

[steve-o]

Nice work Jem!
I see a dual-Marconi-Maxyzmodule setup

[carmangary]

I'm pretty much in the same boat but a little behind. I am going to go buy an aluminum base plate as soon as I have time to go to the metal shop. How thick is yours? I am thinking of going with 1/4". What do you think?

I plan on milling aluminum blocks to get my laser heights even but shims would be my 2nd choice. I hadn't planned on using any paste between the pieces but I guess some heatsink grease couldn't hurt.

[cruch]

I hadn't planned on using any paste between the pieces but I guess some heatsink grease couldn't hurt.

Guess the ARCTIC SILVER 5 is a good compound to use?
I got some of them. I will use it at my next project

BTW: ebay sells them cheap

[Jem]

Thanks for the comments guys

Correct Stevo! One of Marconi's nice twin reds - 472Mw - Lovely!

The Blue is a 200Mw Lasever unit (Thanks David Wu)

The Green is the one I purchased from the 'Doctor', it's a 256Mw LambdaPro. I've ordered a 200Mw Lasever 532nm to replace this as the beam diameter on the LambdaPro is a bit wide and I figured that matching beam diameters would be better. I may sell the LambdaPro if anyone's interested - or - I may just build another (green only) projector

The Dichroics and mounts are from Edmund Optics just up the road from me in York (UK).

Scanners are DT40Pro's from Jian (Thanks Jian you're a great guy and your help and advice is truly appreciated).

The aluminium baseplate is from Metal Supermarket in the UK (£54 ). It's 12mm thick, so hopefully will act as a nice heatsink (but heavy!)

I've just been playing again (couldn't resist another play before I strip it down). I'm using Mamba Black and the Medialas USB DAC, i've played some of their shows that come with the software and all i've got to say is.... A W S O M E ! ! ! ! !

Can't wait until I get it all fixed together properly.

I'm going on the Laser Visuals Safety Course on Monday 16th and i'm hoping to find out more about safety blanking shutters. If anyone can give me some advice as to what you are using and where you got it i'd really appreciate it.

On the bench to the right is one of my pairs of safety goggles. I've got 2 pairs, one for the red and one pair that covers the blue/green wavelengths. Both are OD3 which seem just about right so that you can still see some of the 'dot'.

Cheers

Jem

[DZ]

If anyone can give me some advice as to what you are using and where you got it i'd really appreciate it.

GM-20's make for nice shutters in projectors as they are very quiet when compaired to a rotary solenoid. They float around on ebay from time to time for around $50 or less.

Very nice looking projector Jem, good job! You may want to turn your scan amps around that way they can be adjusted from the outside easier, just a thought.

David

[Jem]

You may want to turn your scan amps around that way they can be adjusted from the outside easier, just a thought.

David

Adjust scanamps?????? - Not Bl**dy likely, I think i'll leave well alone unless something goes wrong

Good idea about turning them around though, looks like i'll have to drill some more holes.

Where (apart from Ebay) can I get the GM20's? I expect I would also require some sort of control board, are these also readily available?

Jem

[sbk]

What do you folks do to get all the beam heights to match correctly? Do you use aluminium shims pasted together with heat transfer paste? Or is there some other magical way of doing it?

You have different solutions.

- You can use two mirrors on adjustable mounts per laser, it's a bit expensive but the most practical and versatile (the first to adjust height, the second to get the beam parallel again).
- You can get a machined base plate with the right height to get the height of your beam matching the others beams at the dichro. Then the dicro on its adjustable mount can align the beam parallel to the incident beam.
- You can hold your laser on a mount with which you can lift your laser and tilt.
- You can try with aluminium sheets to adjust the last 1/10mm of height...

[Zoof]

This is what I'm doing to get the beam hights right.
I'm deliberately having the beams not parallel to the ground plate in various ways. This way you can move various components back and forward and they will pick up the beam at a different height. With the properties of my lasers it all works out very well (can be different for others) , all I need is a 3mm alu sheet under my galvo mount, green and blue are directly mounted on the baseplate. This ensures good heat conduction as opposed to using shims which ruins good heat transfer to baseplate and extra heatsinking is needed. The red is on an adjustable mount I made myself, less heat transfer but it is TEC+fan cooled so it will be OK.
Will have some pics and designs in my gallery if and when I can find the time again to work on it !!!!!!

edit: the angle to the baseplate is small but just enough to get the beams right using standard thickness alu not requiring machining. The beam travels 30 cm horizontally and 2 mm vertically.

[The_Doctor]

I'm deliberately having the beams not parallel to the ground plate in various ways. This way you can move various components back and forward and they will pick up the beam at a different height.

Nice. That's exactly what I'll be doing. I worked that out as part of my 60° beam path scanner idea. It's not just beam height that has to be matched, but laser module pointing accuracy, which is rarely good enough. By angling each beam so it crosses a main axis exactly at some arbitrary point, all it needs is a single reflection at that point to steer the beam exactly where it must go.

Jem, I like it. It's not compact. But it is neat, and I agree, a 12mm base plate is a minimum I'd choose too, on that scale. Like the choice of scan mirror thickness to size, there is a kind of proportion to these things... Seeing what you paid for that baseplate, I don't feel so bad. Not that I thought RS were ripping me off, it was a fine bit of metal, and still is.