Goldenstar collimator lenses?

[VMH2]

Hi.
Can someone explain to me how the collimator lenses on Goldenstar's website work?
I've got my head around what they do but how?
The website says '3 element collimator lens for green and blue laser diodes' So what about the red? do they fit direct to the diodes or need to be spaced in front and if so are they placed before or after the dichro's? Are they a set of there different values or do they combine for adjustment as nec?
Doing a Google search hasn't helped much.
Thanks.

[jors]

link plz! 15 characters

[VMH2]

http://goldenstarlaser.com/index.php...product_id=459
Bit more than 15 characters.
I have actually now found a site specialising in Collimators, with all the info on choosing the right one, but no prices.
They also do adjustable ones and ones that correct elliptical beams to negate the need for anamorphic prisms, i believe.
Thing is, as it will be my first build and on a very tight budget i want to keep is as cheap and simple as possible while still getting an acceptable beam.

[jors]

In order to help..can you share some details of your project? number/kind of laser diodes, desired power/beam specs you want to achieve...n so on

[VMH2]

I cant give specifics at the moment as i'm still learning.
Maybe I should have started this thread different as I have plenty of other issues to clarify also but the idea is to build an RGB around 3w with under 1 Mrad divergance, preferably 8 Mrad and 3mm beam, if poss.
I'm thinking diodes simply as they seem the easyest to position and the mounts are all identical so no issues with getting the heights right.
Two diodes at 90 degrees from the main beam to minimise the amount of dicro's and DT40 wide scanners.
I'm just going on what is available from Goldenstar at the moment to keep things simple but can look at other options when I have a better idea of the plan.
As I say, I should probably start another thread to discuss the whole project but was just initialy confused by the lack of info on the collimators from Goldenstar.

[jors]

Well, all the info you need is here in PL, so take your time in reading large amounts of threads.
Also keep in mind that a laser which is >5mw can easily damage your retina. So those 800mW and up class IV lasers are very dangerous, so protection glasses is a must when manipulating beams.
Also keep safe from specular reflections in your room before firing any laser. Even looking at dot is potentially dangerous so again keep all above in mind to avoid blind your eyes.
That said, just a few concepts as a starting point:

-Such "3-elements lens" is a common collimator at about 8mm Focal length. The other one very 'common' is called 'G2' collimator, which is about 4.02 focal length.
-I advice you taking a look here https://sites.google.com/site/dtrlpf/ to purchase diode and optic elements, this is a reliable source, but ok, GS or Techhood on ebay are other possible sources.
-With 3-ele collimator you will get less divergence but a fatter beam, with G2 lens you will get more divergence but a thinner beam. So A more expanded (becomes fatter) beam is less divergent.
Important rule, is, if you want to achieve less divergence you must expand your beam and viceversa, so you will get a fatter beam but spot on far-field is smaller at a given distance, because of less divergence.
-First, I advice you in purchasing one diode and a 3-ele collimator. For blue, for example, you need a 3-elem anti-reflection coated for blue..so there are AR coated 3-elem collis indeed for each wavelenght.
-GREEN-BLUE: With NDG700, NDG7475, NDB7875 (look at DTR shop) you will get at about 1,8mrad just with 3-elem colli. Just purchase one of these diodes and look by yourself if this divergence is Ok for your needs.
-RED: With Mits 500mW / Oclaro 700mw and 3-elem you will get near 4mrad divergence. As you can see reds are almost double divergent than green/blue. So reds needs 'extra' optical correction (after collimator) to match green/blue divergence.
-You want to mach all wavelenghts divergence in order to get similar far-field spot size, for a better RGB colour overlap, which traduces also in a rich rendering color palette.
-So my advice is to test 1st one green for example with 3-elem. If you want less than 1,8mrad (smaller far field spot), you must correct Green/blue with a prism pair:
https://www.photonlexicon.com/forums...me-with-prisms
As you can see above link, You can correct blue/green with a single prism pair. This way you expand the beams, so again, you get fatter beam, but smaller divergence (smaller far-field spot), which is desirable.
For the RED, even you go to 1,8mrad or 1mrad route (or in between of course) you need a pair of cylindrical lenses to get above divergence. Prism pair simply don't work well for multimode reds. You can find more info here on PL.
You can purchase such cyl lenses here: http://lasershowparts.com/store/... and read this thread about correcting multimode reds.
https://www.photonlexicon.com/forums...l+lenses+mitsu
So, remember the rule, to get 1mrad from red, because it is almost double divergent diode than G/B, you must expand more the red...exactly at near 5mm fat beam to get 1mrad. Just keep in mind if your scanner can handle such beam.
Result is, if you want match R/G/B in divergence, red always is fatter in near field than G/B, because it needs more beam expansion...however far field spots are similar in size..which is desirable for a better color rendering.

diode host: If you buy diode on DTR inside those 12mm copper modules, you need something like this:
http://shop.z-bolt.com/Heat-Sink-for...ules_p_13.html
This heatsink 'clamps' the 12mm cylinder and have a little fan on the top (not showed in pictures, so ask them..just in case). I've tested them, yes a bit 'bulky', but they will keep your diode safe just cooled at ambient temp.
You don't need a big alum baseplate with such heatsinks.
Other smaller diode host are something like this:
http://lasershowparts.com/store/inde...&productId=303
Here you can fit diode directly inside this host. However, because small size and no fan, you need to attach those hosts into 'bigger' alum baseplate+heatsink (maybe with fans below etc). If host becomes very warm at touch...you simple need a more efficient cooling.
Hope this helps a bit
Cheers

[clickamouse]

Excellent summation!
This needs to be in the PL Wiki when it is reborn.

Thanks...Mike

[JRGixxerfreaK1]

Nice one! sums it all up lol

[catalanjo]

Nice one Jordi !
Cheers

[VMH2]

Thanks Jors.
I have to say i didn't expect anyone to put quite that much effort into a reply.
It sounds like all the manufacturers i have been looking at claiming <1 Mrad and 3 or 4mm beam with practically zero correction have an 'interesting' way of measuring them.
As i have been basing my expectations on their specs im sure 1.8 Mrad would be fine if that is more realistic, so i should be able to get away with blue and green with just the collimators and cylindrical lenses for the red. The optics kit at Lasershow parts looks good.
What i am hoping to achieve is something i can use for abstracts with scrim hung in front of the stage but beam shows also, so a bit of a compromise. Normally not more than about 30 meters dance floor though. Although it would be nice to have the power for bigger if needed.
As it gets VERY dusty here i was thinking i would be better to use diodes with separate drivers so i can mount them with a heat sink and fans on the underside of the mounting plate and seal off the optics etc on top?