For Buffo...

[JohnYayas]

For Brad:
Woke up from a dream where you and I were cleaning mud out of a water purifier system.

[Bradfo69]

Humm...... it's amazing what strange things our brains put together when sleeping. I rarely remember my dreams after I wake up but yeah, the once I remember are sometimes bizarre.

[buffo]

Trying to understand red section setup.

I need to get back to this project! Got side-tracked with a few important events recently (not the least of which was the 1000-year rainstorm that hit my area).

We all know reds MM fast axis needs to be expanded near 5mm in order to achieve 1mrad full angle.

Not sure where you got this information from.?. We have had several reds on display at SELEM over the past 3 years that have exhibited a divergence of 1 mrad or less with beam diameters far, far smaller than 5 mm. Both CDBEAM and PolishedBall have posted pictures of their own designs that accomplish this, and I've seen at least 4 different commercial projectors that achieve this level of performance as well. (The Lightspace Pluto II is perhaps the most ubiquitous example.)

I can't say which lenses this particular rig is using, as I did not build it. As I posted above, this is a commercial sample from Goldenstarlaser.com, and they did not share details about which lenses were used during it's construction.

That being said, I can take some beam measurements and report back here with my findings. (Indeed, that is on my list of things to do when I return to this project!) Hopefully we will be able to make some inferences based on those numbers. Several people have expressed interest in using these plates for projectors and/or beam rails, and sometime in the near future I expect there may be a group buy of sorts on these. (Current pricing is around $2200 each for them, which is very competitive.)

I can tell you that right now the divergence of the entire plate is considerably higher than 1 mrad. It's probably somewhere between 1.5 and 2 mrad, but I need to take more accurate measurements to be certain of that. Still, given the high power of the unit, that wide divergence is probably a good thing. It looks amazing at a distance of ~ 35 meters in my backyard, despite the higher divergence.

Adam

[polishedball]

What he is saying is that after correction the spot size will be 5X5mm in most cases per beam, know you knife them and have problems. See this auction for details on the beam size and how it works with the correction we know. Awesome details in the description.

http://www.ebay.com/itm/638nm-635nm-...IAAOSw9N1VuLrp

[jors]

Many thanks Adam

Not sure where you got this information from.?. We have had several reds on display at SELEM over the past 3 years that have exhibited a divergence of 1 mrad or less with beam diameters far, far smaller than 5 mm. Both CDBEAM and PolishedBall have posted pictures of their own designs that accomplish this, and I've seen at least 4 different commercial projectors that achieve this level of performance as well. (The Lightspace Pluto II is perhaps the most ubiquitous example.)

Adam

R you sure? with P73 or Oclaro 700mw? Can you share setup examples please?
Maybe I explained not very well....On P73, my measures below(sorry crappy table):

cyls.....collim.....1st cyl distance from diode...... NF.........FF (7 meters)........mrad
x4........g2.............. 80mm.......................... 5mm......12mm...................0,92
x6........g2...............30mm................... ........5mm......12mm...................0,92
x4.........f2...............35mm.................. .........5mm ......12mm.................0,92
x4........g2...............70mm................... ........8mm.......9,3mm.................0,20
etc

Sooo on ALL cases I need to expand fast axis near 5mm if want to achieve 1mrad with p73...then...if your red module is 2mrad or less...fast axis MUST be necessarily expanded 2-2,5mm/each diode.
Say for example, beam profile after cyls, and just before knife is:
5mmtall x2,5mm wide...so my question again is...how to Knife edge 4x 2,5mm wide beams inside 5mm??....beam array should be wider then 5mm and/or >2mrad

I think is not possible to knife edge 4 P73 which are cyl corrected for <2mrad 'inside' 5x5mm...maybe 5x8mm or more...ok, so module specs are wrong IMHO

[jors]

Thanks,
I know this setup.. this is 3 elements + 6X cyls.
As you can see, expansion is from 2mm uncorrected to 6,5mm corrected/each diode, sure achieving <1mad...maybe 0,8 which is really good, but the price to pay is 6,5mm wide and most scanners are 5mm beam entry, so loosing power here....this is the axis I'm referring to...so again:
-Near 5mm wide if you need 1mrad or slightly less
-Not possible to knife 4 diodes into 5mm wide....taking into account each diode is 6,5mm wide after expansion. Even not possible if 2mm wide after expansion for 2mrad like the goldenstar we are talking about! (2mm x 4 diodes=8mm)

What he is saying is that after correction the spot size will be 5X5mm in most cases per beam, know you knife them and have problems. See this auction for details on the beam size and how it works with the correction we know. Awesome details in the description.

http://www.ebay.com/itm/638nm-635nm-...IAAOSw9N1VuLrp

[buffo]

I haven't done the experiments to try re-creating the beams myself, but surely both you and John have seen commercial projectors with >1 watt of red with beams smaller than 5 mm and divergence of ~ 1 mrad.?. I mean, we had over a dozen of them at SELEM this year...

As for the E-bay auction, there's something fishy going on there. The fast axis correction should not affect the slow axis, yet it does in the pictures posted in the auction. (Look at the far-field picture: the fast axis is on the horizontal, so why does the vertical beam size grow so large in the second shot?) This makes no sense.

I can think of a few possible explanations for the differences between the numbers in your table and the stated results I've seen. It's possible the lens is mounted a lot closer to the emitter, reducing the beam diameter in the near field. It's possible they are using different/stronger primary lenses than you are (I know CDBEAM's rig used 2 mm diameter lenses that mounted right up against the emitter, for example). And it's possible they are using different cylindrical lenses for the fast axis correction.

I will definitely measure the beam diameter pre-and post correction. That should help us figure out what they are doing there at least.

Adam

[jors]

With single mode arrays for sure! With MM like P73, Yes, with Dave's f2 +4x cyls... you can achieve 1,2-1,3mrad @4mm or 0,92mrad @5mm and so on... so, as I said.. for 2 mrad you need to expand FA between 2-2,5mm
Sorry but for me Ebay auction is ok:

NF uncorrected 5,5(slow axis)x2mm(fast axis)....typical beam profile with long f collimator...maybe 8mm, 3-elements etc
NF corrected 5,5(slow axis)x6,5mm(fast axis)... so slow axis is unaffected and there's a FA expansion from 2 to 6,5mm...I think the FF vertical size 'seems' so large in the 2nd shot due camera settings, slightly opened iris, longer shot exposure etc, resulting in a brighter apparent spot. If you look carefully..the wall is brighter too

and yes,,, maybe there are setups with different collimators, cyls etc but optics laws always apply...no matter if you go with 3-elem, or g2, or Dave's F2, or x4, or 6x cyls etc....when manipulating optics with mitsu P73 to achieve 0,9-1,3mrad, you end with 5-4mm wide beam on FA. Lower f collimator, and you have to expand more etc (inversely proportional)

great if you can share some measurements!! so maybe I could sleep peacefully!
tnx again!

I haven't done the experiments to try re-creating the beams myself, but surely both you and John have seen commercial projectors with >1 watt of red with beams smaller than 5 mm and divergence of ~ 1 mrad.?. I mean, we had over a dozen of them at SELEM this year...

As for the E-bay auction, there's something fishy going on there. The fast axis correction should not affect the slow axis, yet it does in the pictures posted in the auction. (Look at the far-field picture: the fast axis is on the horizontal, so why does the vertical beam size grow so large in the second shot?) This makes no sense.

I can think of a few possible explanations for the differences between the numbers in your table and the stated results I've seen. It's possible the lens is mounted a lot closer to the emitter, reducing the beam diameter in the near field. It's possible they are using different/stronger primary lenses than you are (I know CDBEAM's rig used 2 mm diameter lenses that mounted right up against the emitter, for example). And it's possible they are using different cylindrical lenses for the fast axis correction.

I will definitely measure the beam diameter pre-and post correction. That should help us figure out what they are doing there at least.

Adam

[polishedball]

The eBay auction is also what I see in test. You need to stack the beams in most cases to get the best beam profile and size. My quad stacks 2, wave plate, and PBS to get just under 4w raw with some scanner spill.