A CDBEAM 777 great project was stopped .. I need suggestions please!

[Minamoto Kobayashi]

About 5 months ago I have commissioned to my hero CDBEAM 777 a very special beautiful build, the "Blue Balista" laser.
It uses NUBM07E diode, a lot of customs components and the corrective optics.
This is the awesome 5.3W build with corrective optics:



.. and the marvellous collimated beam (together a similar 520nm build):



(full resolution here: https://www.flickr.com/photos/27318590@N08/26513672832/)

The beam was so well collimated to the infinity that also without a beam expander I can hit the clouds with small spot! :drool:

The problems.
---------------

The Linos Beam Expander and other expanders needs precise specs for the input beam.
For example, Hercules use DPSS tecnology, the beam is near tem00, it has a small diameter and it has low divergence, so absolutely no problems
to use it with any beam expander.
In the world of multimode diode the music is somewhat different: slow/fast axis, high divergence and high powered beam can create big issues.
The Blue Balista laser was perfectly collimated to the infinity, but the beam at the aperture was not suitable for the Linos beam expander.
In my precedent high powered 450nm build I was able to collimate the dead focus ad about 7 cm from the aperture because I had the G2 lens easily
accessible.
The correct regulation of the input beam is needed because the beam need to enter into the first small lens not focused to avoid to burn the lens coating.
The dead focus is so created inside the Linos BE, between the first and the second lens; in that way I will save the coating and obtain a
decent GAP between the min and the max focus regulation (I will have a dead focus at about 50 cm from the Linos BE aperture, and a focus to
the infinity when I rotate both the focus mechanisms at about 50% of the entire thread).
Also, in no condition the beam inside the Linos exceed the diameter of the lens, so I will not have any loss of power.

Unluckly the coating of my partucular brand new expensive Linos BE had a coating of 355nm. This coating was strong enough to bear a not-collimated
450nm beam from my precedent build, but its damage threshold was not enough high for my 465nm, 5.3W collimated beam build.
The beam was too strong and too much collimated, and the power dissipated by the not ideal coating exceeded the damage threshold of the coating
itself, so I have almost instantly destroyed the coating (a lot of smoke inside the Linos BE !!) :banghead::banghead:

The internal G2 lens cannot be rotated for two important facts:

1) It is difficult to remove the acrylic canopy without scratch it;
2) I will lose the perfect collimation and the beam quality.

So now I'm facing two big problems:

1) To found a company that can decoat and recoat my damaged lenses with the right coating;
2) To found a particular lens to put just inside the beam aperture, before the beam expander, to obtain a focus at about 7cm from the aperture.

Since the build has a deep hole inside the aluminum barrell, I can create a cylindrical lens holder with the outside diameter suitable for the hole,
and the inside diameter suitable for the lens.
So I can glue the lens inside the holder, and then I can move the custom lens holder along the entire barrell hole to change the focus point.
When I have found the correct focus point I can glue also the holder with a little drop of thermal compound to keep the holder in place forever.
At this point I ask to the expert guys of LPF what kind of lens I can use for my purpose. I already tried with a extra G2 lens, but it create a dead
focus at only 1 mm from the surface !!
I need a lens that create a focus at a certain distance. I can have much play with my custom lens holder in and out, so I can found easily the right
focus position.

 

[RedCowboy]

Found a company that can decoat and recoat my damaged lenses with the right coating.

^ That sounds good. ^

Did it work ok otherwise?

 

[Minamoto Kobayashi]

Sorry I have forgot the "to" LOL ... I'm searching for ... :crackup:
Now the lens are totally unusables. I must remove the destroyed coating ad recoat with the right coating (460-470 nm)

 

[Alaskan]

I tried to find a place to coat a lens for me and they wouldn't do a custom job for less than like 1800 dollars, if I remember correctly. I am interested in know who they are, if they can do that job far cheaper, but not in the hundreds of dollars.

 

[paul1598419]

That's a shame that you didn't get the correct AR coating to begin with. I fear this will cost you plenty. I feel for you.

 

[Minamoto Kobayashi]

Nice updates friends!

First of all, at about 7 miles from my home I have found a glass company that owns a very expensive programmable coating machine.
The problem is the decoating procedure.
Usually there are two methods ... the best results are achieved with the use of fluoridre compound, but it can be applied only to the quartz lenses.
The other method, solphoric acid at 120 °C, works well with fused silica lenses, but the results could be poor. In fact, the silica lenses can lose part of its properties, and part of the coating could remain over the lenses.
The consequential issues are mainly two: an halo around the dot and a significant loss of power (20-25% against the 2% of a quality lens!)
The ideal scenario will be to have the original lenses uncoated, but for the Linos BE it is really impossible!
However, I will try, stay tuned!

About the beam focus, I talked with a very kind gentleman from Edmund optics that have suggested me this kind of lens:

6.0mm Dia. x 72.0mm FL, VIS 0°, Inked, Plano-Convex Lens

To work properly, Linos BE needs an input beam with some precise specs.
I learned from my previous experiences that the Linos work very well with thin DPSS tem00 beams, but for the multimode diodes the music is totally different: I need to collimate a dead focus inside the BE, between the second and the third lens.
I measured with digital caliper the correct focus distance, and it is about 70mm from the G2 lens (or from the convex surface of the above mentioned lens).
In that way I do not risk to damage the coating (a too much focused beam against a coated lens can heavily damage the coating itself because the power will exceed the coating threshold damage).
And as a nice side effect, I will obtain a nice GAP in the LINOS BE focusing regulations.
In fact a wrong convergent or divergent beam can create either a too short focus or a too long focus.
In my sleepless nights, on top of the chimney of my building, I really tried everything :evil:
The ideal setting will be achieved when the minimum focus is reached at about 50 cm from the Linos BE aperture (both the focusing regulations at the minimum, aka completely screwed), while the focus to the infinity will be reached with both the focusing mechanisms at 50% of the entire course.
So the CDBeam777/Minamoto Kobayashi project continues, and will be really a laser with "attributes" ... stay tuned !! :wave: :wave:

 

[VirtueViolater]

Nice updates friends!

First of all, at about 7 miles from my home I have found a glass company that owns a very expensive programmable coating machine.
The problem is the decoating procedure.
Usually there are two methods ... the best results are achieved with the use of fluoridre compound, but it can be applied only to the quartz lenses.
The other method, solphoric acid at 120 °C, works well with fused silica lenses, but the results could be poor. In fact, the silica lenses can lose part of its properties, and part of the coating could remain over the lenses.
The consequential issues are mainly two: an halo around the dot and a significant loss of power (20-25% against the 2% of a quality lens!)
The ideal scenario will be to have the original lenses uncoated, but for the Linos BE it is really impossible!
However, I will try, stay tuned!

About the beam focus, I talked with a very kind gentleman from Edmund optics that have suggested me this kind of lens:

6.0mm Dia. x 72.0mm FL, VIS 0°, Inked, Plano-Convex Lens

To work properly, Linos BE needs an input beam with some precise specs.
I learned from my previous experiences that the Linos work very well with thin DPSS tem00 beams, but for the multimode diodes the music is totally different: I need to collimate a dead focus inside the BE, between the second and the third lens.
I measured with digital caliper the correct focus distance, and it is about 70mm from the G2 lens (or from the convex surface of the above mentioned lens).
In that way I do not risk to damage the coating (a too much focused beam against a coated lens can heavily damage the coating itself because the power will exceed the coating threshold damage).
And as a nice side effect, I will obtain a nice GAP in the LINOS BE focusing regulations.
In fact a wrong convergent or divergent beam can create either a too short focus or a too long focus.
In my sleepless nights, on top of the chimney of my building, I really tried everything :evil:
The ideal setting will be achieved when the minimum focus is reached at about 50 cm from the Linos BE aperture (both the focusing regulations at the minimum, aka completely screwed), while the focus to the infinity will be reached with both the focusing mechanisms at 50% of the entire course.
So the CDBeam777/Minamoto Kobayashi project continues, and will be really a laser with "attributes" ... stay tuned !! :wave: :wave:

Good luck, man, your obsessed, I LOVE IT
Great to see such enthusiasm