Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers



NUBM44 6W+ 450nm Laser Diode

Alaskan

Well-known member
LPF Site Supporter
Joined
Jan 29, 2014
Messages
12,160
Points
113
Well, this is the second one o these diodes with the same problem, the one I bought from another member and now yours. Why? Is this power level so high that if you don't get the beam focused right, i.e. the lens too far away from the diode light reflecting off the holder damages the window? This is a wild guess or stab at what is going on, if this is the problem maybe focus to infinity at low power, or maybe this isn't the issue? We haven't had high power diodes like this before, there might be something going on like this that lower power diodes aren't susceptible to. At first I questioned whether there was a vapor deposit of rosin on the lens from the extraction process, but if DTR is checking all of his to assure the windows are clean, that can't be it.
 



RedCowboy

Well-known member
Joined
Jul 10, 2015
Messages
9,011
Points
113
I should point out that no, that is not one of these blocks. That video is 4 years old...
Yes I know that was an old A 24 diode block, sorry I am along time reader but first time poster. I didn't mean for it to seem non relevant to this thread so I deleted it. However what I was thinking of is the concept of taking the 7 diode block and whatever stock optics it uses to run it all through the spinning phosphor wheel. From there possibly use a part I've seen at coherent that is basically a mirror polished aluminum tube. Then a pair of corrective optics and/or a beam expander. However all my beam combining success has been with single mode beams, except for knife edging. With these multi modes I can extend the range via beam expanders but it's still a bar shape or a hot spot with wings that works but is not elegant. These new diodes could benefit from a wider housing and a wider 3 element set with an adjusted spacing for the far field point of focus but not the lightshow solid beam people. I am enjoying reading what you experts are doing with cylindrical optics and I am a big fan of doing what works, but later on when we get down to a single high output floodlight style output RGB diode in each unit like the ball lens 9mm's we may need wider optics to start with? My bet is the diodes are going to be wider like T-03's or arrays possibly like the plpm4-450. Anyway I am here to learn, thanks.
 
Last edited:

RedCowboy

Well-known member
Joined
Jul 10, 2015
Messages
9,011
Points
113
Well, this is the second one o these diodes with the same problem, the one I bought from another member and now yours. Why? Is this power level so high that if you don't get the beam focused right, i.e. the lens too far away from the diode light reflecting off the holder damages the window? This is a wild guess or stab at what is going on, if this is the problem maybe focus to infinity at low power, or maybe this isn't the issue? We haven't had high power diodes like this before, there might be something going on like this that lower power diodes aren't susceptible to. At first I questioned whether there was a vapor deposit of rosin on the lens from the extraction process, but if DTR is checking all of his to assure the windows are clean, that can't be it.
It could be too much power for the case window combined with reflection from the shape of adjustable optic? But you would think the maker would have tested the heck out of these before release. I am curious what the stock optics look like. I could have touched the backside of the 3 element and gotten finger oil vaporized onto the window because it popped dead center. I probably just overheated it because the beam looked solid, sorry I didn't take any beamshots :( Clean and cool will be my rule for these bad boys.:)
 

Alaskan

Well-known member
LPF Site Supporter
Joined
Jan 29, 2014
Messages
12,160
Points
113
My thought the damage could occur through the G2 lens being backed out too far and reflections from the beam hitting the lens holder barrel probably isn't it, after sleeping on the idea I'm doubtful now. However if you did have residue from your finger on the lens, that could do it.
 

planters

New member
Joined
Jun 24, 2010
Messages
286
Points
0
CD,
The near field that will matter is the dimension at a practical distance from the diode for say a scanner, but to determine the divergence of the final beam, it is the dimension after beam expansion at say the exit face of the second cylinder or a few cm past that where combining optics or scanner mirrors will be located.

I suspect that I have some power loss from my diode because the most divergent light does not strike the entrance aperture of my power meter. That is why the assumption that your power loss may be similar to your measurements with the other diode might not apply here.

I will test the next diode as soon as I get it, but what I think is going on here is that the fundamental technology of this GaN diode is no different than the last generation of 9mm diodes. The ball lens that was included with the other high power diode makes me think that the projector manufacturers do not care about beam quality/divergence. They wanted to reduce diode count and all the associated manufacturing costs and driving complexity and so Nichia responded by generating diodes with more fine wires for current delivery and a wider facet that maintained similar fluence on the face and similar charge density within the chip. What we loose in exchange for the greater power/chip with a plano/plano cavity is that the gain becomes much less restrained to a linear, coherent, point-like source. It will be impossible, after the fact, to produce the same beam characteristics and far field brightness with this diode as with the previous, lower power diodes.

I suspect they (Nichia) may be considering replacing the single facet on the diode to multiple facets as they hope to further increase power. This will create a completely uncorrectable, nightmare of a beam. This would effectively discourage harvesting as well. If they did pursue the ever expanding junction route then they may have to move to a larger than 9mm diode support to deal with the thermal load.
 

planters

New member
Joined
Jun 24, 2010
Messages
286
Points
0
Thanks for the link! This might work. Maybe you saw my video describing wavelength division multiplexing?
https://www.youtube.com/watch?v=UE-73EWUapw

I did this with prisms and red P73 diodes. I was unaware that this technology might be available as a stand alone solution.

It was obvious when I demonstrated the NUBM44 diode that you can wavelength tune with current. The reds can be tuned with current as well as temperature.

I will contact this company and find out if they can offer a red or blue, reflective device that is affordable.

This will not solve the particular problems with this diode, but opens the possibility for increasing the brightness of any diode. The limit of this method is the ratio of the bandwidth of each input laser and the spectral spread of the array. You cannot treat two neighboring diodes differently if their wavelengths overlap.
 

RedCowboy

Well-known member
Joined
Jul 10, 2015
Messages
9,011
Points
113
Oh yes, I'm subscribed to your channel, you do very nice work.
 

Alaskan

Well-known member
LPF Site Supporter
Joined
Jan 29, 2014
Messages
12,160
Points
113
I'd like to see how far a 520nm laser diode can be tuned with either voltage or temperature, would be great to get one up closer to 532nm. Anyone have the beam diameter of the NUBM44 at 25mm away from the diode face?
 
Last edited:

crazyspaz

New member
Joined
Jul 4, 2012
Messages
2,862
Points
0
CD,
The near field that will matter is the dimension at a practical distance from the diode for say a scanner, but to determine the divergence of the final beam, it is the dimension after beam expansion at say the exit face of the second cylinder or a few cm past that where combining optics or scanner mirrors will be located.

I suspect that I have some power loss from my diode because the most divergent light does not strike the entrance aperture of my power meter. That is why the assumption that your power loss may be similar to your measurements with the other diode might not apply here.

I will test the next diode as soon as I get it, but what I think is going on here is that the fundamental technology of this GaN diode is no different than the last generation of 9mm diodes. The ball lens that was included with the other high power diode makes me think that the projector manufacturers do not care about beam quality/divergence. They wanted to reduce diode count and all the associated manufacturing costs and driving complexity and so Nichia responded by generating diodes with more fine wires for current delivery and a wider facet that maintained similar fluence on the face and similar charge density within the chip. What we loose in exchange for the greater power/chip with a plano/plano cavity is that the gain becomes much less restrained to a linear, coherent, point-like source. It will be impossible, after the fact, to produce the same beam characteristics and far field brightness with this diode as with the previous, lower power diodes.

I suspect they (Nichia) may be considering replacing the single facet on the diode to multiple facets as they hope to further increase power. This will create a completely uncorrectable, nightmare of a beam. This would effectively discourage harvesting as well. If they did pursue the ever expanding junction route then they may have to move to a larger than 9mm diode support to deal with the thermal load.
Exactly right. Who cares about beam specs, if you want beam specs they have low power 440 diodes that do around .4mRad or something close...projectors are about light, you don't need a fine needle beam to make a perfect video projection. Which is why these diodes are so ridiculously powerful and have such absurdly bad beams specs. Save on space, save on money, save on power...a stepping stone to a more perfect solution, from a business standpoint. As RedCowboy said a few posts up, it would make sense that at some point in the future, a new projector will be torn down to find one very large (TO3 sorta thing) "diode" that spits out ridiculous powers in the form of what is barely laser output anymore (more of an LED/flashlight) into a single focusing lens, and boom. Minimum heat, minimum cost, minimum space, maximum efficiency.


Oh yes I'm subscribed to your channel, you do very nice work.
Seconded :D
 

TaterMay

New member
Joined
May 16, 2015
Messages
350
Points
0
It is very hard to clean optics, I mean really clean them. A good rule it to never let them get dirty! If you have to, canned air is a pretty good, non-contact method, but make sure you short the leads as high velocity air (with debris) can generate a significant voltage. Use a loupe to inspect the optic and I have found a common wooden tooth pic can move or stick to a particle that I am afraid to wipe across an optical surface. A dedicated spray bottle with super pure, spectroscopic grade or at least reagent grade acetone or methanol can blast dirt off complex surfaces, avoiding the need to wipe. Methanol is safer and less aggressive toward potting compounds and adhesives.

I agree that temperature is not likely my problem, but testing another diode in two different hosts should clear that up

CD,
Where are you measuring your near field, relative to the diode face? What does the correction do to the power?
With these very divergent diodes like the P73, you can adjust the magnification ratio of your cylinder pair simply by varying the distance from the diode. As you increase this distance the first cylinder is struck by the same ray angle, but further from its axis and so becomes more powerful. Consequently the second, positive cylinder has to be spaced further from the first lens, increasing the magnification.
You are the man. You probably just saved an NDB7875 of mine. Unfortunately, I didn't see whatever particles were on another, higher power NDB7875, so it has a circle burned in the center very badly. But still, toothpicks work very well. Just stocked up on them. I also learned through this that a highly likely source of a dirty window is a less-than-perfect job machining a heatsink. It had quite a few bits of metal and dirt in the threaded area where the lens screws in, even though I tried to clean it well before the build. I'll definitely be more vigilant in cleaning it next time. Have you guys tested the diodes that you and DTR swapped yet?
 

hakzaw1

Well-known member
Joined
Apr 2, 2009
Messages
10,091
Points
113
IMHO nobody makes diodes 'meant' for us-
or portable lasers-(or even laserprojectors)... of the entire market we make up prolly 2%.
 

planters

New member
Joined
Jun 24, 2010
Messages
286
Points
0
The 520nm diode is based on a strained lattice in the junction, but uses GaN like the 445 diodes. These, 445nm diodes tune very little with temperature at something like 0.05nm/C. But, as we saw they tune significantly with current.

A little trick with removing machining debris. After all the normal, common sense, Scotch-Brite pads, scrubbing and brushing with solvent and soap, is to run a clean screw or threaded component with pipe thread tape wrapped around it into all the tapped holes a few times. Any, even microscopic particles that can come off, will.

I am waiting for DTR's diode, but I did a fairly good inspection of the first diode when it arrived and the host was very clean.

IMHO nobody makes diodes 'meant' for us-
or portable lasers-(or even laserprojectors)... of the entire market we make up prolly 2%.
I heard somewhere that the original Ca***s were shipped back to firms in CN just to harvest the early 445nm diodes. Actually, the redirection of technology is a lot of the excitement with many of these laser projects. It's like tearing apart a lawn mower and using the engine to build a go kart. It's unregulated, thank goodness. You can build a 10W hand held if you want to, but no major manufacturer would ever market such a thing unless it was to supply it to the military for $50,000 each.

Although of less interest to the pure laser pointer crowd, the steadily increasing power of these 445nm diodes opens up the possibility of using them as pump sources. Just like the 808nm diodes with lousy beams from bars can pump NdYAG and other crystals, 445 can pump dyes and short wavelength crystals. The coumarin dyes have some amazing colors and you can also pump Pr3+ crystals which lase in the red,orange and multiple lines in the blue simultaneously. Building these lasers is not as simple as plunging in a diode into a driver, but it isn't experimental. It has been done before.
 

RedCowboy

Well-known member
Joined
Jul 10, 2015
Messages
9,011
Points
113
I guess I'm not tracking, why would something made in China be shipped back to harvest the diodes? Just so China laser hobbyist shops could sell them in pointers?
Sorry if I'm getting off topic here but I don't know if N company would outsource to China, Japan and China have some deep old wounds. Yes I know a lot of finished units are assembled there. But Osram has a factory in China that they have invested hundreds of millions of euros in and the South China University of Technology has produced all kinds of advances in the semiconductor industry, recently they got 122% increase in efficiency moving GaN from silicon to copper, but they are doing a lot more than that. Hell Chinese city busses have been powered by ultra capacitors for something like 10 years now. But I digress, I think N company is fighting to stay ahead but I bet the next big wow is going to come from Osram. I know I will buy a whole projector to get a plpm4-450 in hand.:drool:
 
Last edited:

VisibleGreen

Banned
Joined
May 1, 2011
Messages
1,062
Points
0
Maybe these diodes require an absolutely clean lens. Maybe typical residue on, well, anything will burn and damage the window? As if you have to treat it like opening up a harddrive. No dust whatsoever anywhere.
 

Jstr

New member
Joined
Feb 10, 2014
Messages
347
Points
0
I think N company is fighting to stay ahead but I bet the next big wow is going to come from Osram. I know I will buy a whole projector to get a plpm4-450 in hand.:drool:
I don't mean to derail the thread, but I have to say the plpm4-450 package looks awesome.They claim they have doubled the power of each individual emitter, which makes me hope the whole package is capable of being pushed to 70~80W. Another interesting thing is that the optical temperature for power is listed as 65°C. Although I would say it'd be difficult to use in a handheld. ;)

If you have plans to get one, be sure to post your findings!

I'm also quite interested in the beam correction on the NUB diodes, so thank you cdbeam and planters!
 
Last edited:




Top