Bread boards and Alignment

[laserLips]

Can I buy different lasers form different suppliers and assume they are all the same height so when It comes to putting them on a breadboard , the lasers will all be at he same height? What kind of standards (apart from ILDA) do lasers follow?

Graham

[stanwax]

quite simply no. its up to you to equalise the beam heights either by position of the laser or by changing the height with optics - or a combination of the two.

Rob

[laserLips]

Stan when you say change the height with optics, you mean put some thing under he laser to make it higher....sorry...Newbie...
Can I just get somthing else straight aswell....
Are bread boards, optics and beam table all different things...
Graham

[stanwax]

firstly its Rob not Stan.

Beam table and breadboard can be the same thing but dont have to be....! Breadboard suggests, but not implies that its a drilled metal plate of some size with threaded holes for attaching devices such as lasers, kinematic mirror mounts, beam steering mirrors etc. So you can make a beamtable from a breadboard but you dont have to. My beam tables are cut and drilled to the sizes that I want and do not have the matrix of holes that you would think of automatically if the term breadboard were used.
Optics can be anything from PBS cubes (polarising beam splitter), to dichros for mixing colours through lenses and steering mirrors.
If you have a mirror that is not parallel to the vertical then a beam hitting it parallel to the horizontal will be reflected upwards or downwards depending on its inclination - only prob with this is you loose the parallel to the horizontal attitude - but that can be dealt with. To raise or lower a beam in this way only a small angle of deviation is needed - remember physics at school - the angle of reflection is equal to the angle of incidence. So if the beam hits a mirror at 85 degrees to the mirror surface then it will reflect at the same 85 degrees. The total separation between the beams in terms of angle will be 10 degrees.

Rob

[laserLips]

Sorry for getting your name wrong Rob.. and thanks for that description.
So when it comes to bread baords, are there any rules of thumb for the width and hieght of the matrix?

What about screw size?

Thanks,
Graham

[stanwax]

if you buy a standard breadboard it tends to be 1 inch pitch - i think with some standard thread - im sure someone will jump in and say what thread as I dont know. However it really does not matter if you are just knocking up a beamtable for a projector. Unless you are likely to change the configuration frequently then you might as well just get a suitably sized lump of ally and drill holes where you need them - tapping where needed. See image - this is the 'beamtable' in my little RGB. its nothing more than drilled ally plate. If you do decide to move stuff around - as I did recently when I converted from RGY to RGB then just drill some more holes

Rob

PS you are not the first to call me stan - and Im sure you wont be the last

[buffo]

There are two easy ways to adjust the height of the beam. The first is to mount each laser on it's own table. That is, mount the laser to a piece of 1/4 (or thicker) plate that is at least an inch larger (in length and width) than the base of the laser. Then drill holes in the corners of this plate and suspend it above your main beam table using threaded rods. You'll need an adjustment nut on the bottom and another one on the top of the "floating" table. This will allow you to adjust the height of the beam as well as the angle. (Not all lasers emit a beam that is parallel to the baseplate.)

In theory you only need to "float" two lasers, since you want to match the height of the two lower beams to the beam height of the laser that has the highest beam. However, in practice you end up having to float all three lasers because the added height from the threaded rod and the nuts, not to mention the thickness of the table itself, is almost always too high for the third laser, so you need to raise it as well.

The other way is to bounce the beam off two mirrors to raise the beam. (The first reflection sends the beam up or down, while the second reflection brings the beam back parallel with the optical table.) Note that you can use the reflective face of a dichro as the second mirror, so you only need to add one bounce mirror in the path, not two. Also, when using mirrors to adjust the beam height, you really only need to adjust two of the beams. The third beam (usually green - the one that passes through both dichros) becomes your base that you align the other two beams to.

Using floating tables makes construction more difficult, and it's not as easy to adjust, but you have less optical losses (fewer reflections). It's also cheaper, since you don't have to purchase two more adjustable mounts for the extra bounce mirrors.

Using mirrors makes final alignment easier, and it also works better with larger, higher power lasers because the lasers are mounted directly to the large optical table. This dissapates the heat better than a floating table does. (This isn't an issue with smaller lasers.)

Finally, there is one other way to do it, but it's a lot more involved. If you have access to a milling machine, you can fabricate custom shims for your lasers to bring them all to the same level and make all the beams parallel. But it's not easy, and it's not adjustable, so you have to get it exactly right the first time. (Or start over with a new shim.)

Adam

Edit: Took too long for the reply - totally missed Rob's replies. Oops!

[Laser Ben]

Almost all breadboards are spaced equally. Metric ones are M5 tapped holes on 25mm centers, and imperial ones are 1/4-20 on 1" centers. You will usually use a imperial one in the USA and a metric one else ware in the world.

Breadboards are quite expensive for a proper one. Your Best be will be to get a 1/2" aluminum plate and figure out where you need holes. The way I'm going to try to do it, is mill down a 1" plate so the beams are all at the same height and they go perfectly into the Galvos.

[mliptack]

The way I'm going to try to do it, is mill down a 1" plate so the beams are all at the same height and they go perfectly into the Galvos.

Hmmm sounds really impressive... I cant wait to see that work of art! Hopefully you wont change your mind on the layout too late...

Rob I was wondering if there was a reason for you to have your blue laser first in line shotting through all the dichrohics. How much loss with it do you have?

[laserLips]

Thanks for all the great replies everyone. Shame there arent more standards.

Wow look at this... http://tidyurl.net/v6Dye

and this ... http://tidyurl.net/v0Nzm
also this palce...http://www.kineticsystems.com/page137.html

Has anyone used these, mega bucks though.

Having said that I just saw this...
http://tidyurl.net/d3Ipl
Thast more like it but still pricey...
Where can one get 1/2" aluminum plate? Had a look on the net but only came across theose really expensive ones..