NUBM44 blue- New Video

[rMuD]

Are you both using Thermopile sensors? in DTR's video I heard it was exceeding his sensors capability and it does not look like it is a heat sink. Per planters video which the wavelength shifts at least 8mm up. A thermopile counts Joules, and Photo Detector counts photons. The lower the wavelength higher the energy. 444nm = 4.4740e-19 J/photon 452 = 4.3948e-19 J/photon.

If the increase in power is shifting the wavelength even though the power is decreasing it is increasing the ocular brightness to the human eye. In the end.. Watts is what we measure a laser projector in, in reality we are looking for a mix of ocular brightness and color gamut.

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.

[planters]

I am currently using a thermal sensor. I do have photo sensors as well and they are so much faster, but cannot tolerate these high powers. Soon, I will measure a diode which DTR has measured as well and this will help to compare the effects of the lenses and the meters.

As does the laser diode I'm asking about.

No sir, it does not. The diode you are asking about is the theme of this thread and the subject of your post. I did not miss that detail. The video you post shows a kludgy, open laser cutter. with a bowed workpiece taped to the top of a cardboard box. This suggests that you don't require a very sophisticated solution. The low cost G-9 lens I suggested will produce a very tiny spot 10-20 cm from the diode.

You are correct that the blue diodes at 405 or 445nm will interact with many materials that are not as absorbent at longer or even IR wavelengths. In any case, I think that this diode will not be as useful as it might seem because the spot size will be substantially larger than lower power 445nm diodes. The cut speed might be similar, but the line width will be finer with the lower power diodes.

[kingjamez]

No sir, it does not. The diode you are asking about is the theme of this thread and the subject of your post. I did not miss that detail.

The video you post shows a kludgy, open laser cutter. with a bowed workpiece taped to the top of a cardboard box. This suggests that you don't require a very sophisticated solution. The low cost G-9 lens I suggested will produce a very tiny spot 10-20 cm from the diode.

See we are finally in agreement! The cardboard box WAS a much better way to try to make me look bad! Well done.


Please disregard my question. I'll just experiment until I figure out the best answer on my own. That certainly seems like a better option at this point.

Jordan's package with the diode arrives tomorrow and should be tuned for a "tame" 4A of input current. I'll see how it does in comparison to my other 445's and 405's.


-Jim

[planters]

See we are finally in agreement! The cardboard box WAS a much better way to try to make me look bad! Well done.

I'm not so sure, the tape is pretty bad and the bow in the workpiece is significant, but you may be right.

I'll just experiment until I figure out the best answer on my own. That certainly seems like a better option at this point.

Agreed, and good luck.

[DTR]

Another test posted over on LPF.

Re tested mine tonight. I finally got the chance to move my diode from the copper 12mm module and into one of DTR's XYZ heatsinks. The diode seems to sit steady right above 7 watts for the 3 tests I did. All the tests we're about 45 seconds.

Did a quick video of last test.

[planters]

I got back from a trip this afternoon and DTRs diode had arrived. He also sent his mount and heat sink. These are nice quality and were easy to work with. The lens he sent, I am guessing is a G2 in a 9x 0.5 barrel. I added a small amount of PTFE tape to stabilize the focus and set it up. The bad news is the video I did was with a bad diode. The good news is the diode he sent performs as I had hoped and like most of the other testers have measured. At 600mA, I was already getting 600mW. By 1,100mA, I saw 1,500mW. At 2,000mA, the diode was producing 3,200mW. The maximum power was 7,100mW at 5,100mA. After this, the power began to drop with additional current.

The beam was better as well. With a 5x cylinder pair the beam at 30cm from the collimator was 7mm high and 3mm wide and at 14M the beam was 16mm high and 6mm wide.

As I posted above, my power meter is very similar to DTR's or around 5% conservative. In addition, I examined the lens he sent and it was pretty clean but, not perfect. It was in about the same condition as the G-9 that I installed for the first test.

The high power is a great finding, but the better beam is more important to me. Three of these could be knife edged to produce a 7x9mm beam with 20W of power and a PBS would allow you to produce the same beam with 40 watts!

Nice.

[catalanjo]

.............7x9mm beam ............................................with 40 watts! Nice.

I wont wun ov dem fings !
Cheers

[planters]

Of course you do.

Without cryo cooling and with DTR's mount or a modification to allow a multi diode clamp, the lay out is very simple. It might be neat to water cool each block, but that is not necessary. Six, Lasertack prisms on six LSP flex-mounts send each triple beam to the PBS. On the way, one triple beam passes through a wave plate. The mounts would be offset depending on the location so that each beam travels as close as possible to the same distance prior to merging in the PBS. These highly divergent beams are very sensitive to the distance from the collimator to the beam expander. Finally, a (-)25mm cylinder and a (+)125mm cylinder should give the beam I describe. For such an impressive laser a final stage through a PCX/PCX telescope would allow the 7mm x 9mm beam size to be adjusted up or down and a spatial filter between these lenses could clean up the wings.

[catalanjo]

Got most of the stuff ... but Dave ain;t got no waveplates left ........

Got first bigblu diode now despite USPS still telling me that it was out on the town in Frankfurt !
I will also need load more diodes ....... and definitely water cooled
Cheers
PS. That's a very concise recipe you just came up with there ! ...... Ole!

[DTR]

Got first bigblu diode now despite USPS still telling me that it's out on the town in Frankfurt

Just peaked at it as I was curious and it dose say delivered on the 14th in Spain.

"July 14, 2015 , 10:51 am Delivered SPAIN"

Although tracking does not always show when they are delivered.