NUBM44 6W+ 450nm Laser Diode

[Deleted member 16589]

Now, my question. Through all this long thread has anyone documented the beam characteristics of this diode? In many of my videos, I take time to analyze and improve the beam dimensions as well as the divergence of these lasers. I am seeing and you can see as well, the output from this laser is not symmetric and has significantly higher divergence than the lower power blue diodes. Of course it is multimode, but even the main stripe is large in both the X and the Y and it cannot be brought to a tight focus. The asymmetry may represent facet damage or a problem with the can window, but the large stripe may be inherent to a larger junction dimension that can accommodate the higher current input. If true, that cannot be improved with optics.

I have a hard time finding divergence information myself. It seems most people (but not all) around here only want power and don't care about divergence.

I would rather have good divergence over power. I have an adjustable slit Im going to try some spatial filtering on one of my NDB7242E diodes. I get .36 mRad as they are.

 

[bandlasing]

There is clearly some inconsistency with the power values I am generating and the power others are seeing. The stock lens is clean (after mounting I inspected it under a video microscope). The can window appeared clean. I did not place this under the microscope or attempt to do anything to it after receiving it from DTR. So, I suppose this could be a source of loss. The "stock" lens that DTR supplies called the G-9 is familiar to me and I have used it with several other blue laser installations. Is there a suggestion that it has significant loss vs the G-2 lens? 50% loss from three Edmund optics Vis-0 coated lenses, one Vis-0 coated optical window and one MgFl lens (the -25mm cylinder) is unlikely, but I can certainly test the diode with only the collimator in place.

Now, my question. Through all this long thread has anyone documented the beam characteristics of this diode? In many of my videos, I take time to analyze and improve the beam dimensions as well as the divergence of these lasers. I am seeing and you can see as well, the output from this laser is not symmetric and has significantly higher divergence than the lower power blue diodes. Of course it is multimode, but even the main stripe is large in both the X and the Y and it cannot be brought to a tight focus. The asymmetry may represent facet damage or a problem with the can window, but the large stripe may be inherent to a larger junction dimension that can accommodate the higher current input. If true, that cannot be improved with optics.

I am definitely interested in seeing your power reading with only the single lens

 

[Jstr]

This could have happened at any time even in transit if something got in the wrong position and when fired after being received but if you powered the diode it would be impossible to miss with the lens in or out. It will not collomate into a nice beam but be scattered light in a halo. this is a risk anytime you have the lens out and these high power diodes will burn something on there in a fraction of a second.

Anyway send it over and lets see what we can do to resolve it without continuing to derail this thread.:beer:

That's interesting... The output was a perfect bar when collimated when I had it. No halo...

Sorry for derailing, this is my last post.

Thank you DTR.

 

[Alaskan]

It's still a bar, just that it has this optical disturbance in the middle of the bar now from a burned spot on the window. I saw it as soon as I powered it up the first time. I find the bar to be rather wide, even when collimated, it's still a wide bar which won't reduce to a spot. Needs corrective optics, lots of correction.

Edit: I looked at the window using a zoom-scope at high magnification and can see the window as a small crack in it near the center, it appears there was some contamination on the window which when the glass became hot, migrated, or rolled as a liquid over the center of the window to become boiling hot, hot enough to crack the window at that spot. There was a small amount of what appears to have been rosin coating the top of the can as well as a little of it on the window. This is my best idea of what happened, was the problem due to de-soldering contamination? I don't know, just surprised me there was what appeared to be vapor deposited rosin on both the can as well as portions of the window, but so little as to be difficult to see by eye. This lets JSTR off the hook, he likely had nothing to do with the failure.

 

[planters]

OK, I've done some additional testing and I am narrowing down the sources of the discrepancy, but it still remains. I went back to DTR's site and copied down the relative output in watts vs input current for two diodes I have used many times in the past; the P73 and the earlier generation, 9mm, 445nm diodes. The P73 is using Dave's 2mm aspheric lens and the 9mm is using the G-9 collimator. A table of the results would be burdensome to generate, but to summarize, my Ophir meter is 10% conservative relative to DTR's for the P73 at all posted current settings and 5% conservative for the 9mm tested all the way to 2.6A. I am not claiming my meter is more accurate ( or conceding that it is less so), but assuming the meters haven't changed then the NUBM44 diode I have is not performing as well as it should.

I then tested the NUBM44 with only the G-9 collimator and the maximum output is 5.6W at4.4A. Increasing the current further causes the power to decrease. I also measured the beam dimensions of the two blue diodes and this is eye opening. At 50cm from the front of the collimator lens, the "3W", 9mm beam is 3mm high and 2mm wide. The beam from the NUBM44 at the same distance from its collimator is 3mm high and 7mm wide. In the far field and at the same 14M distance the 3W is 9mm high and 58mm wide while the NUBM44 is 12 mm high and 180mm wide!

These beam dimensions suggest that much more aggressive beam expansion will be necessary for the NUBM44 to produce a similar far field spot size, but the near field beam is already fatter and so this will constrain the potential expansion more for the diode that needs it more. This is not good.

I'm looking forward to some posts that analyze the beam quality of this diode rather than focusing only on the RAW output. Hopefully, there will be some better methods to limit divergence than I have tried.

 

[Atomicrox]

I am seeing and you can see as well, the output from this laser is not symmetric and has significantly higher divergence than the lower power blue diodes.

Compared to the NDB7A75 or to the older/lower power NDB7875?

Fantastic video, BTW!

 

[bandlasing]

OK, I've done some additional testing and I am narrowing down the sources of the discrepancy, but it still remains. I went back to DTR's site and copied down the relative output in watts vs input current for two diodes I have used many times in the past; the P73 and the earlier generation, 9mm, 445nm diodes. The P73 is using Dave's 2mm aspheric lens and the 9mm is using the G-9 collimator. A table of the results would be burdensome to generate, but to summarize, my Ophir meter is 10% conservative relative to DTR's for the P73 at all posted current settings and 5% conservative for the 9mm tested all the way to 2.6A. I am not claiming my meter is more accurate ( or conceding that it is less so), but assuming the meters haven't changed then the NUBM44 diode I have is not performing as well as it should.

I then tested the NUBM44 with only the G-9 collimator and the maximum output is 5.6W at4.4A. Increasing the current further causes the power to decrease. I also measured the beam dimensions of the two blue diodes and this is eye opening. At 50cm from the front of the collimator lens, the "3W", 9mm beam is 3mm high and 2mm wide. The beam from the NUBM44 at the same distance from its collimator is 3mm high and 7mm wide. In the far field and at the same 14M distance the 3W is 9mm high and 58mm wide while the NUBM44 is 12 mm high and 180mm wide!

These beam dimensions suggest that much more aggressive beam expansion will be necessary for the NUBM44 to produce a similar far field spot size, but the near field beam is already fatter and so this will constrain the potential expansion more for the diode that needs it more. This is not good.

I'm looking forward to some posts that analyze the beam quality of this diode rather than focusing only on the RAW output. Hopefully, there will be some better methods to limit divergence than I have tried.

Strange with the readings you are getting sounds like it's a NDB7A75 diode not this new one. Maybe that first batch DTR extracted were the new diodes and the ones after that projector was the normal 7A75 DIODES

 

[TaterMay]

OK, I've done some additional testing and I am narrowing down the sources of the discrepancy, but it still remains. I went back to DTR's site and copied down the relative output in watts vs input current for two diodes I have used many times in the past; the P73 and the earlier generation, 9mm, 445nm diodes. The P73 is using Dave's 2mm aspheric lens and the 9mm is using the G-9 collimator. A table of the results would be burdensome to generate, but to summarize, my Ophir meter is 10% conservative relative to DTR's for the P73 at all posted current settings and 5% conservative for the 9mm tested all the way to 2.6A. I am not claiming my meter is more accurate ( or conceding that it is less so), but assuming the meters haven't changed then the NUBM44 diode I have is not performing as well as it should.

I then tested the NUBM44 with only the G-9 collimator and the maximum output is 5.6W at4.4A. Increasing the current further causes the power to decrease. I also measured the beam dimensions of the two blue diodes and this is eye opening. At 50cm from the front of the collimator lens, the "3W", 9mm beam is 3mm high and 2mm wide. The beam from the NUBM44 at the same distance from its collimator is 3mm high and 7mm wide. In the far field and at the same 14M distance the 3W is 9mm high and 58mm wide while the NUBM44 is 12 mm high and 180mm wide!

These beam dimensions suggest that much more aggressive beam expansion will be necessary for the NUBM44 to produce a similar far field spot size, but the near field beam is already fatter and so this will constrain the potential expansion more for the diode that needs it more. This is not good.

I'm looking forward to some posts that analyze the beam quality of this diode rather than focusing only on the RAW output. Hopefully, there will be some better methods to limit divergence than I have tried.

It does, indeed, sound as though your diode is likely underperforming if it is dropping power after 4.4A. The others that have been tested thus far have continued to climb in power up to about 5.5A, right?

 

[Moe Ron]

Strange with the readings you are getting sounds like it's a NDB7A75 diode not this new one. Maybe that first batch DTR extracted were the new diodes and the ones after that projector was the normal 7A75 DIODES

Greetings,

The new diode is about 1/3 longer than the NDB7A75 in output using the G lens. Running side by side is a very noticeable difference between the 2. Would suspect maybe the emitter is just a little bigger, and why we have a higher output in this new one. I have no way of checking myself, but am sure someone here can look,and maybe even get some data on it.


cheers,
Moe

 

[Cel]

It seems most people (but not all) around here only want power and don't care about divergence.

I would rather have good divergence over power.

Me too! :beer:

I'd sacrifice power for better beam and dot anytime. Power has become dirt cheap.

 

[VisibleGreen]

I suggest that someone make another thread about the beam characteristics, power and other tests for this diode with only data and/or close discussion of that data.

 

[CDBEAM777]

I suggest that someone make another thread about the beam characteristics, power and other tests for this diode with only data and/or close discussion of that data.

Yea...When I get my hands on one....The first test will be to examine the divergence-Aspect ratio !!

Perhaps the raw output is actually more divergent than the P73/HL63193 Red diode. ???? Dunno ????

We do have some optics to consider for beam correction. I assure you....none will deliver a perfect Gaussian profile (Round)..... !!!

For my personal taste's ...a reasonable beam geometry ....at say 10 meters is a reasonable and achievable goal....:eg::eg::eg: We will see !!!

 

[planters]

I was comparing the divergence to the first 9mm "3W" diode.

It is definitely dropping after 4.4A and the 1:1 relationship begins to level off after 4.0A.

I would not create a separate thread for some of the beam characteristics. The power is just another characteristic and the power may in fact come to depend on how the beam needs to be manipulated.

I strongly suspect that this diode will require substantial correction and expansion and if the junction is much larger in order to accommodate the high current/fluence then it will be impossible to correct for that.

 

[Drivinfast247]

This is AMAZING!!!!

 

[CDBEAM777]

:crackup::crackup:

This is AMAZING!!!!

Yes....it is amazing....that we freely share our knowledge and information....with no monetary entanglement.....whatsoever !!!

Experimenters and "Makers" from all around the planet can and do jump in....and ...bit by bit....we learn, we document and we share and pool our knowledge....er....ah..." Cue the epic music soundtrack " now !!!!

I have no doubt...the boyz at dArpa look in....from to time to time...maybe get a laugh or two !!!...maybe are amazed at our....er....ah....dedication.....and progress....on a budget that likely amounts to a month supply of TP for their main Laser Lab:crackup::crackup::crackup:

That is what is truly amazing !!!!!...and a huge thanx to those that make this Forum possible !!

 

[NightExplorer96]

6W's of blue?!?! It's incredibly how fast technology moves these days

-Alex