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Anything above 100W 450nm?

RedCowboy

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Knife edging example.
The resulting beam/band is as wide as the number of beams.
The PBS combines 2 rows of 4 but the left band has to pass through that wave plate in the bottom center to be polarized opposite of the right band. I have never seen a PBS cube that could manage 100w.....better to just direct each array through a lens to your target.
7 arrays could be arranged 1 in the center surrounded by 6 more for 700w


1594495953145.png




You knife edge by the width of your beams so knife edging your 31/34 arrays won't really accomplish anything, a 4 array 2x2 would be the same as setting them into a bigger square.....might as well do that and lens each to your 2mm spot at your wheel or 1 array center surrounded by 6 for a total of 700w, each lensed and trained to your target or all focused with one big lens.....of course you could arrange your arrays 3x3 for 900w and lens each to your wheel....the problem is the 24 chips in the 31/34 arrays have aggressive divergence so you need to be close to your wheel to make a small spot focused through your lens, it becomes a question of physical size.......you could knife edge a bunch of c-lens corrected laser diodes building stacks of rows and then with a big lens focus them all to your wheel but that's a big undertaking.



You could try to fiber couple your arrays but you lose coherence length if that matters for pumping phosphor, from what I read it does otherwise just focus down the biggest blue industrial LED you can get.......I know they use them is some data projectors but hundreds of watts I have not seen, doesn't mean they don't exist I just haven't seen one .

The dicro glass plate set at a 90 degree angle lets the projector fire the blue laser bundle through it to hit the phosphor wheel then the light from the phosphor wheel can't get back through the dicro glass plate so it is reflected 90 degrees through a lens, this would make more room for you I think, you would need to abandon firing through your reflector and direct your phosphor wheel produced light to a reflector with lenses/mirrors so you have room to jam in half a dozen or more 31/14 arrays and focusing lenses near your wheel or angle your wheel and lens/reflect your product to the remote reflector........or possibly a bigger phosphor wheel.....but the spotlights I posted use LEP and 405nm lasers which are single mode, you can get a very good knife edged array of beams focused, but they are not as powerful.

 
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likevvii

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Maybe I used the term wrong. In my case, I can build the setup like a knife edge, but I won't be aiming the arrays to be parallel, but to a single spot.

Physically speaking, it is easier to stack more than 4 arrays if my setup is like a knife edge instead of the "pyramid mirror" I am using on my 3d model.

What I dont understand is when beams overlap. When I point all the beams to a spot; they eventually must overlap at the end. Does overlapping cause any issues?

Led wont really work for me because they don't have enough illuminance (brightness/area). I might get a lot of efficient brightness, but the cross sectional area of LEDs are too large and I won't get much range even if I have tens of thousands of lumens.

I still don't fully understand what coherence means, but I think as long as 450nm energy strikes the phosphor, it will produce light.

I could try coupling my own fiber? Sounds fun. Techincally speaking, it seems like the methods I am using to focus laser onto a wheel would be the same to focus into a fiber?
The problem is that the PCX lens and nichia array can only produce a 2x2mm spot. How would I get it smaller to be able to fit inside a fiber?
 

RedCowboy

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What I dont understand is when beams overlap. When I point all the beams to a spot; they eventually must overlap at the end. Does overlapping cause any issues?
No it won't matter at all, you get all the power, I have converged many beams and they add up at the point of impact, beams can cross in the air and there is no loss from crossing.

The projector I showed you knife edges 24 laser diodes ( 24 beams ) and focuses them through lenses onto the phosphor wheel, you can see the faint reflection of the 3 rows of 8 on the lens in the pic.



The reason you have to rotate one beam with a PBS cube is because it has to be opposite polarized otherwise the polarizing coating on the cube passes without combining.

If the chips in your 31/34 arrays produced beams with longer coherence length you could set several further back and focus them tighter at your wheel, you are limited by physical size based on how close you have to set your arrays with lenses to get a tight enough spot.

There's a specific angle needed to enter the fiber and I have not set up any fiber couplers, I have worked with modules that contain many small emitters all fiber coupled but they are set up to be coupled, these 31/34 arrays are meant to pump a phosphor wheel, they use 24 MM emitters with uneven divergence, it may need a special coupler that steps down or a gradient index lens, a really big fiber or may not be reasonably possible ........fiber coupling can be picky from what I understand, there's plenty of info to read about it, I want to learn myself.

In this module there are 3 rows of emitters and all 3 rows end up coupled to a fiber at the output, the mirrors are each one step higher so you get 3 layers of rows ( knife edged ) at the coupler, the deal on the left is a fiber coupler, the fiber is missing.

 
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gazer101

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Knife edging example.
The resulting beam/band is as wide as the number of beams.
The PBS combines 2 rows of 4 but the left band has to pass through that wave plate in the bottom center to be polarized opposite of the right band. I have never seen a PBS cube that could manage 100w.....better to just direct each array through a lens to your target.
7 arrays could be arranged 1 in the center surrounded by 6 more for 700w


View attachment 69312




You knife edge by the width of your beams so knife edging your 31/34 arrays won't really accomplish anything, a 4 array 2x2 would be the same as setting them into a bigger square.....might as well do that and lens each to your 2mm spot at your wheel or 1 array center surrounded by 6 for a total of 700w, each lensed and trained to your target or all focused with one big lens.....of course you could arrange your arrays 3x3 for 900w and lens each to your wheel....the problem is the 24 chips in the 31/34 arrays have aggressive divergence so you need to be close to your wheel to make a small spot focused through your lens, it becomes a question of physical size.......you could knife edge a bunch of c-lens corrected laser diodes building stacks of rows and then with a big lens focus them all to your wheel but that's a big undertaking.



You could try to fiber couple your arrays but you lose coherence length if that matters for pumping phosphor, from what I read it does otherwise just focus down the biggest blue industrial LED you can get.......I know they use them is some data projectors but hundreds of watts I have not seen, doesn't mean they don't exist I just haven't seen one .

The dicro glass plate set at a 90 degree angle lets the projector fire the blue laser bundle through it to hit the phosphor wheel then the light from the phosphor wheel can't get back through the dicro glass plate so it is reflected 90 degrees through a lens, this would make more room for you I think, you would need to abandon firing through your reflector and direct your phosphor wheel produced light to a reflector with lenses/mirrors so you have room to jam in half a dozen or more 31/14 arrays and focusing lenses near your wheel or angle your wheel and lens/reflect your product to the remote reflector........or possibly a bigger phosphor wheel.....but the spotlights I posted use LEP and 405nm lasers which are single mode, you can get a very good knife edged array of beams focused, but they are not as powerful.

Would it be possible to use an insane fresnel lens to focus a laser array down to a point and then have a concave lens focus it back out?

And if so, is there such a material that could withstand the needed 1W+ of laser light that would be striking its surface?

Thanks!
 

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RedCowboy

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A Fresnel lens won't do any magic tricks here, they have their uses but you can focus tighter with glass, the guys you see making solar ovens use a fresnel because it's an easy way to get a big lens to collect a lot of sunlight.

I have worked with positive-negative lens combos before but the issue here is the aggressive and uneven divergence of 24 emitters, it's not a single point source.

Here's an array of beams I was working with recently, I use a pos-neg lens combo and your bundle size and the resulting divergence depends on your focal lengths, you can't make any lens do anything, they have to work together and both change the focus of your beams.

If you focus a 31/34 array with a lens onto a flat surface you will see 24 points, now we want to squeeze those points down into as small a space as possible, but it's still 24 points......if you have one of those multi LED flashlights you can hold a lens in front of it and see the emitters where you focus it onto a wall or the ceiling.


 
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likevvii

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A way to get smaller spot size is use a shorter focal length convex lens.

Do you think a cylindrical mirror or lens can squeeze things down even more?

I'm thinking if there are any 2mm fiber optic I can buy.

My goal is to have 1mm spot, but 2mm is a good balance too.
 

RedCowboy

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A way to get smaller spot size is use a shorter focal length convex lens.

Do you think a cylindrical mirror or lens can squeeze things down even more?

I'm thinking if there are any 2mm fiber optic I can buy.

My goal is to have 1mm spot, but 2mm is a good balance too.
#1 This is why I said you will need to be close to your wheel.

#2 Not with 24 multi mode emitters, each emitter would need beam shaping which you could do by removing the factory gang lens but it would be very involved, there's a thread on it but it's unfinished ATM.

#3 I don't know if there's 2mm single clad, I have stripped, cleaved and polished the end of fiber and there's a bit to learn, the end of the fiber is an optical instrument itself and the beam angle has to fall within a range when entering the fiber and a lot of fiber is coated for IR you would need fiber coated for vis. or 445-455nm

#4 You have seen Drakes/Styros video haven't you, he used a F-theta lens and Drakes convergence/cluster point was maybe 2.5 mm ( est. ) central hot spot and 5mm counting all the visible spot.



Screenshot_2020-07-12 (4) 2020 World's most powerful CW handheld laser - YouTube.pngScreenshot_2020-07-12 (4) 2020 World's most powerful CW handheld laser - YouTube(1).png
 
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gazer101

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A Fresnel lens won't do any magic tricks here, they have their uses but you can focus tighter with glass, the guys you see making solar ovens use a fresnel because it's an easy way to get a big lens to collect a lot of sunlight.

I have worked with positive-negative lens combos before but the issue here is the aggressive and uneven divergence of 24 emitters, it's not a single point source.

Here's an array of beams I was working with recently, I use a pos-neg lens combo and your bundle size and the resulting divergence depends on your focal lengths, you can't make any lens do anything, they have to work together and both change the focus of your beams.

If you focus a 31/34 array with a lens onto a flat surface you will see 24 points, now we want to squeeze those points down into as small a space as possible, but it's still 24 points......if you have one of those multi LED flashlights you can hold a lens in front of it and see the emitters where you focus it onto a wall or the ceiling.


Right but at least the beams would be tighter together right? Even with the bad divergence, you'd still be able to see a tight-ish spot 10ft away (with each of the beams having expanded a bit due to divergence)?

Focusing them tighter together wouldn't result in the array becoming a glorified flashlight I don't think (would still have the throw of a laser) 🤔
 

RedCowboy

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I have only had those taken from rear projection TV's which are useless for lasers, actually just tested one again and NOPE.....maybe if one was specifically made and coated for a specific laser use, but I have not seen anything but poor results with these and what I read suggests they would not be as good as normal glass/fused silica optics, but I would love to be surprised.

 

likevvii

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I looked around on what types of lens we can use, and it all seems pointless if you are just trying to focus one wavelength. A simple convex lens, aspherical if possible will do the job with lowest cost, most options, and availability.

I talked to some fiber coupled companies and the cost is above 10000USD at 100W. They are also HUGE. I wonder how much the 2000W will cost. Just imagine waving that fiber around in the air at full power LOL

__
For the use in projectors where the beam travels below 300mm distance, we can assume all the diodes are very parallel to each other. When focused, all 8 (nubm05), 20 (nubm31t) diodes will mostly overlap each other when focused with a lens.
I believe they were specifically designed to result in a 2x2mm spot for the balance of intensity, efficiency, and thermal limits.
If I modify the the multi lens to increase the height, I should be able to farther reduce the spot size.

Based on the testing with phosphor wheels, they get extremely hot. The wheel itself, but most importantly the strike zone on the surface phosphor which can be 2x to 3x above the wheel itself. If the spot size was smaller than 2mm, it would easily go past the critical temperature of the phosphor and damage it.

Phosphors used on LEDs and economy projectors are silicone based which have a surface limit of 200C.
Cinema and industrial phosphors are either single crystal or ceramic which have a surface limit of 400C.
Both phosphors are still usually bound with silicone so they have a overall limit of 185C.
20200612-221545.jpg20200612-221616.jpg20200613-033303.jpg
This is barely 60W output and the wheel was already climbing fast above 125C. But this is without any active cooling. My thermal camera has a very slow shutter/capturing speed so it will not be able to really read the temperature exactly where the laser hits, but that spot should be near the 300~400C zone.

____
Here is something interesting:
Untitled-2.jpg
For the longest time I have been thinking about this image.
I have recently come across some special optics that finally gives me the understanding I need.


array optic 2.jpg
array optic 1.jpg
How some projectors "combine" does not necessarily overlap them but effectively use the spacing between the diodes to pair the beams. A nubm05 block has a large physical gap between each diode so we can use simple solutions whereas the nubm31t array will need an optic with specially coated areas to selectively pass and reflect the beam to merge them.

This is basically knife edging them into a grid.
 

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RedCowboy

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Yes I have seen those plates stacking 2 GBall banks ( like in your pic ) in a large projector but as aggressive as the fast axis divergence of each emitter in your 31/34 is and how close they are together you will likely only have room to merge 2 arrays.

I wonder if you could focus a ring of as many 31/34 arrays as you need into a light pipe to act as a big fiber optic and bring it near your phosphor wheel at an angle, you won't have very good coherence length so you will need to place it's output close to your phosphor wheel, likely at an angle so you don't block your product from reaching your reflector.


 
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gazer101

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I looked around on what types of lens we can use, and it all seems pointless if you are just trying to focus one wavelength. A simple convex lens, aspherical if possible will do the job with lowest cost, most options, and availability.

I talked to some fiber coupled companies and the cost is above 10000USD at 100W. They are also HUGE. I wonder how much the 2000W will cost. Just imagine waving that fiber around in the air at full power LOL

__
For the use in projectors where the beam travels below 300mm distance, we can assume all the diodes are very parallel to each other. When focused, all 8 (nubm05), 20 (nubm31t) diodes will mostly overlap each other when focused with a lens.
I believe they were specifically designed to result in a 2x2mm spot for the balance of intensity, efficiency, and thermal limits.
If I modify the the multi lens to increase the height, I should be able to farther reduce the spot size.

Based on the testing with phosphor wheels, they get extremely hot. The wheel itself, but most importantly the strike zone on the surface phosphor which can be 2x to 3x above the wheel itself. If the spot size was smaller than 2mm, it would easily go past the critical temperature of the phosphor and damage it.

Phosphors used on LEDs and economy projectors are silicone based which have a surface limit of 200C.
Cinema and industrial phosphors are either single crystal or ceramic which have a surface limit of 400C.
Both phosphors are still usually bound with silicone so they have a overall limit of 185C.
View attachment 69340View attachment 69335View attachment 69336
This is barely 60W output and the wheel was already climbing fast above 125C. But this is without any active cooling. My thermal camera has a very slow shutter/capturing speed so it will not be able to really read the temperature exactly where the laser hits, but that spot should be near the 300~400C zone.

____
Here is something interesting:
View attachment 69339
For the longest time I have been thinking about this image.
I have recently come across some special optics that finally gives me the understanding I need.


View attachment 69338
View attachment 69337
How some projectors "combine" does not necessarily overlap them but effectively use the spacing between the diodes to pair the beams. A nubm05 block has a large physical gap between each diode so we can use simple solutions whereas the nubm31t array will need an optic with specially coated areas to selectively pass and reflect the beam to merge them.

This is basically knife edging them into a grid.
Yeah regular lenses are quite bulky. The reason I was thinking to use a fresnel lens was due to its portability
 

RedCowboy

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Yeah regular lenses are quite bulky. The reason I was thinking to use a fresnel lens was due to its portability
I have never seen a Fresnel lens used to focus a laser or an array of laser beams, have you gazer101 ?
They are crude light gathering lenses and in lighthouses used for directing incoherent light, would be a step back in this application I think.
 
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RedCowboy

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Maybe remove the gang lens and use rows of FAC lens or lengths of fiber like the Chinese are doing with de-canned and re-capped GBalls then a single coli lens.......a length of fiber could span a row of emitters unless the alignment is canted which I think it might slightly be, but maybe for your purpose not too much ???
 

gazer101

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Maybe remove the gang lens and use rows of FAC lens or lengths of fiber like the Chinese are doing with de-canned and re-capped GBalls then a single coli lens.......a length of fiber could span a row of emitters unless the alignment is canted which I think it might slightly be, but maybe for your purpose not too much ???
Technology's not quite there yet to make it worthwhile to combine hundreds of tiny emitters with insane optics... might as well just get a CO2 tube with a huge electric hookup and call it a day

Idk how you'd make that into 445nm tho
 




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