Pulse driven NUBM44 ?

[RedCowboy]

I have seen videos of people etching metal with these advertised 15W DIY laser heads, I had seen some that are junk but others appear to work.

My question is has anyone pulse driven the NUBM44 ?

Has anyone used these Chinese drivers?

It says it takes standard TTL at <9Khz, so if I gave one an 8Khz signal at 100% PW the driver should limit the actual pulse duty cycle the diode gets to make a 15w pulse. ( Would have to..duhh ) That is my 100% PW TTL signal would tell the driver to drive the diode so it makes 15W pulses at 50% duty cycle or less per pulse.....or does the driver replicate my modulated PW exactly?

Has anyone used one?

Has anyone tested the output ? Is it making 15w pulses ?

Has anyone seen just the driver for sale?

Has anyone seen what diode is in the module ? I think I saw one that had an open diode in it, anyone have one with a 9mm can/window diode inside ?

https://www.ebay.com/itm/15W-Pulse-...262740287690?_trksid=p2349526.m4383.l4275.c10

 

[paul1598419]

Maybe I don't understand what you are asking, but a 100% duty cycle at 8 KHz, or any frequency, would be basically on all the time. It wouldn't be pulsed at all. Even if you pulsed a direct diode with shorter pulses, one can't get double the output of the maximum power in CW mode. Those have got to be Chinese mWs. I doubt they have even bothered to test the power output.

 

[RedCowboy]

Gee whiz Paul, I know that, I'm saying the driver may not mirror the PWM signal like an amp, it may use it as a measure to pulse the diode at twice it's normal albeit over spec output for half duration pulses or less.

I was thinking out loud for a second there, what I am saying is I could give this Chinese driver 100% PW at 8Khz and it would give the diode it's max allowable pulse at the voltage and current for the duty cycle or actual PW the diode puts out, I can't imagine the CNC software knows every diodes limit so the CNC software and circuit would modulate between 0 - 100% PW and the driver would interpret and reproduce 0 to 100% based on 100% being actually 35% or what ever that diode would take as the laser head and driver are sold as 1 part and the CNC software and controller could be giving TTL to any laser head.....unless this software and controller are made to work with only this laser head, but I see the laser head and it's driver being sold separately for DIY applications, really I suppose I have to buy one and scope it to see.

Also I expect this is the Chinese rating of 15W max and not accurate, but if we could pulse drive the NUBM44 to make a 50% duty cycle or PW at 15w then the laser would look brighter.

----edit----

For instance, if the cnc controller ( the users laptop ) and software were drawing a solid line it would be moving X axis and giving the laser 100% but the driver on the laser head that's pulse driving a NUBM44 at 15w would not give it 100% duty cycle per pulse, just 100% of what it is able to take at 15w output, otherwise it would pop. I theorizing that the driver sees a 100% PW and gives the diode a 50% duration pulse at 15w.

If the laser head is a universal item then it's driver would have to interpret 0-100% PW as 0 - 100% of what it can output and that being a 50% duty cycle pulse at 15w for the NUBM44 diode est.

What I am looking to do is repurpose the pulse driver, not pulse drive the diode myself because I don't know how long of a pulse it can take at 15W output and if the driver on this head drives it and they survive then I only need to power the driver and PWM the TTL as it's a universal control logic, unless the software knows what diode it is and the driver mirrors the PWM exactly....this is what I don't know...but as the head and driver should be a universal part for any DIY setup then the TTL PWM should be at the spec <9Khz and 0 - 100% of a 5v control signal with 0-0.8 being OFF and 3.5-5.0 being ON, and the laser head and it's driver run the diode based on it's set up.

 

[paul1598419]

The problem with that is that power is the energy in J that can be had in one second. In other words, 1 watt = 1J/s. Your diode may be able to give you 1J of energy in a second's time, but the amount it can give in 0.5 seconds will be much less than 0.6J, so it can't provide the energy necessary to have the power equation give you the 15 watts.

I'm not saying this correctly as it is late and my mind is winding down. I hope that you can get the gist of what I'm trying to say, though.

 

[RedCowboy]

I understand that, 15w pulses of 50% duty cycle would be 7.5w of total output as read on a LPM is what you mean in essence, right?

I need to see a schematic for that Chinese pulse driver or get access to an entire working CNC unit with it so I can see how the driver is being modulated from the laptop, there's no way you or anyone could answer my question without knowing how it ( that specific driver ) is designed, most people who have one won't even know.

But even if I pulse drove a 44 diode with my own hand build driver, the laser would look brighter but the total power in heat energy it put out would not be any greater, although the higher energy albeit shorter pulses of energy would have a higher peak.

What I could do is buy the head with driver and make a simple PWM circuit running at 8K and slowly turn up the PW while reading the lasers total energy on a LPM, then I will know if I need to limit my PWM circuit to est. 50% or if I can give it 100% and the driver will in turn make the laser put out the claimed 8W actual total output they claim, with that 8W being made up of est. 50% duty cycle 15W pulses. :beer:


p.s. I suspect 15W and 8W are inflated anyway, still if we could make our 44 diodes look half again as bright....

-------edit--------

Paul, if we use TTL to modulate our standard driver such as in the pic, then 100% PW will be full power, but as the driver I am looking at for the cnc head is making 15w pulses, it's full power may be 50% pulses, so wouldn't a TTL signal of 100% PW tell the driver to drive the diode at 15W but 50% PW ? Unless the software in the users PC knows not to give more than a certain % of PW.

This is what I don't know, and because these laser heads with drivers could be used with any DIY CNC I would expect the driver would accept a TTL signal of 0 - 100% PW and in turn drive the diode as it was designed, not as 1 to 1 per the control PW, but I don't know, I suppose I would have to test 1 and see, but if they are crap then hopefully someone will say so. Maybe they just have a lens that will let 7w of 450nm etch metal ?

----EDIT----

Looking at this further, I believe it will run without any TTL input at all, I'm pretty sure giving it 100% PW would not hurt it, I would order one but if it had a de-canned mubm08 diode I would be quite disappointed.

Anyone know what's in these ?

https://www.ebay.com/itm/15W-Laser-...321747&hash=item56a6c7fba9:g:DswAAOSws6ZaMNPe

 

[lasersbee]

If I understand your concerns correctly....

1) the Laser's Driver will know to output 100% of the
available Laser Power when the TTL input signal is at
100% PWM. It is not the CNC software that controls
the actual output of the Laser it is the Driver.

a) If the same CNC software asks for 50% power and
sends out a 50% PWM TTL signal at 9Khz... A 1 Watt
TTL controlled Laser will output 500mW and a 10 Watt
TTL controlled Laser will output 5 Watts.

2) The stated frequency of 9Khz is the spec timing of
each PWM pulse required to read the pulses properly
by the Driver and control the Laser Power.

3) The TTL PWM pulse's width is the only thing controlling
the Power of the TTL Modulated Laser... not the frequency
of the pulses.

4) If you apply a steady 5VDC to the TTL input you will
get 100% Laser Power output.

You probably know all that but I thought I'd put it out
there anyway...:beer:


Jerry

 

[RedCowboy]

Correct, just giving the TTL a steady 5 volts is the same as giving it a 100% PW modulated signal at 9Khz which in this case is a driver designed to in turn pulse drive a laser diode at twice it's normal albeit over spec output ( 15w output ) in pulses of 50% or less duration, the frequency the driver pulses the diode may not even be 9Khz

This is what I was thinking to start, it's not as if the driver was running the diode CW to start with, and as I looked at it more it appears the thing is meant for multi use applications and doesn't even need to be modulated in order to be " ON " , I was originally thinking it was purpose built to be modulated only but after looking at these further it appears not to be the case.

I was hoping to repurpose the driver in a build using a NUBM44 and I remember but cant find where someone had one of these modules opened up and the factory supplied diode had no can on it, but I could be mistaken, I expect but don't know for a fact that they are using a currently in circulation ( N ) brand diode.

I also wonder what these are really putting out and if it's worth the trouble, maybe someone has one and has checked it on a LPM.

If it was putting out a 15w pulse of 50% duration at unknown frequency then it should read aprox. 7.5 watts on a LPM, is that not correct ?

 

[paul1598419]

Yes, if the diode you are using is capable of that power. I now see you are only interested in what the driver can do. I don't know this driver, so I can't speak to its ability to supply a diode with enough current to output 15 watts. Since that is also a function of the diode's maximum power, I don't know that this question can be answered in that form.

 

[diachi]

You can't have a "PW modulated signal at 9kHz" with a 100% duty cycle. If the duty cycle is 100% then there's no modulation, it's a constant voltage...

 

[RedCowboy]

Yes that's true. :beer:

 

[lasersbee]

I also wonder what these are really putting out and if it's worth the trouble, maybe someone has one and has checked it on a LPM.

If it was putting out a 15w pulse of 50% duration at unknown frequency then it should read aprox. 7.5 watts on a LPM, is that not correct ?

I bought a 3.5W 445nm Module and driver
similar to the 15W Laser and Driver you
show and it only put out ~2.5W.

I'd be surprised that for $127 USD that it put
out anywhere near 15 Watts..

Basically yes... if the TTL pulse width is set
to 50% then the Laser would put out 1/2 of
what it put out at 100% pulse width.

I don't know the actual specs of that Driver
but if the Specs say 9Khz PWM frequency then
I would get as close as possible to that for the
first runs. You can play with that frequency
once you know the driver is working correctly
to see if it still works properly.


Jerry

 

[Encap]

p.s. I suspect 15W and 8W are inflated anyway, still if we could make our 44 diodes look half again as bright....

Pulsing a direct diode can only result in a lower average output number than peak output.
The diode peak power is it's peak power output---average optical output power is the product of the repetition rate, the pulse width, and the peak pulse power.

Not sure what peak output is for nubm44 nor what max electrical power it can handle is without destroying it.
I don't think there is any official spec sheet for it. I guess someone needs to experiment a bit to determine peak output.
DTR gives as much info as is available for the lastest versions NUBM44-81/NUBM47-A1 which have a 10% higher output than prior versions see: https://sites.google.com/site/dtrlpf/home/diodes/6w-nubm44-445nm-laser-diode

" Laser Peak Power and Average Power: What’s the Difference?
By OphirBlog / Laser Power & Energy Meters, Laser Power & Energy Sensors / Jan 8,2014

When I think of a laser, I think power.

At the end of the day, a laser is just another way to transfer energy from one place to another. (In fact, there are those that think it might be the next big thing in long-distance energy transportation, as used by Lockheed Martin to power a UAV for over 48 hours.)

Since power is a measure of how much energy is transferred in a unit of time, this is the prevalent parameter when it comes to lasers. However, if the laser is pulsed, things start getting complicated. Where before, there was just power and maybe power density, now we start to see many more specifications. There’s pulse energy, width, and repetition rate, as well as two kinds of power: peak and average. Pay attention, because here’s where it gets confusing. The same laser can have an average power of 10 mW, but a peak power of 10 kW!
Divide the energy per pulse by the pulse width (in time) and you will get the peak power. This is the power of the laser during the pulse, and it would be your only power spec if instead of pulsing the laser you never turned it off (as in a CW laser). But since the laser is off some of the time (usually much more time than it’s on) the average power will be lower. A simple way to think of the average power is just the peak power times the duty factor. In other words, you’re averaging the power over the course of one on/off cycle of the laser.

So, if for example, your laser is 10 kW, and it pulses for 1 ns at 1 kHz (in other words, its duty cycle is 1/1,000,000 or 0.0001%). Since the laser is off a million times as much as it’s on, the effective average power is one millionth of the peak power, or 10 mW."
From: Laser Peak Power and Average Power: What?s the Difference?

 

[RedCowboy]

Yes, but like an impact hammer when you concentrate your energy into a short pulse it's better able to overcome some obstacles.

Also due to persistence of vision a pulsed laser with a peak of 15w will look brighter than an 8 watt laser running CW even though the total energy ( joules ) is less when measured over time.

For instance a NUBM44 will run at 4.7v drawing 4.5a and put out 7.5w of energy CW, but if given 7v would draw 7a and dim down, but if given 7v and 7a for a short pulse 8000 times a second with that pulse being on for 30% and off for 70% of it's duration then the total energy would be less but the peak energy would be higher during that pulse and the laser would look brighter even though it was putting out less joules of energy.
**In theory, I have not run one at that current for that pulse duration.

 

[Encap]

Yes, but like an impact hammer when you concentrate your energy into a short pulse it's better able to overcome some obstacles.

Also due to persistence of vision a pulsed laser with a peak of 15w will look brighter than an 8 watt laser running CW even though the total energy ( joules ) is less when measured over time.

For instance a NUBM44 will run at 4.7v drawing 4.5a and put out 7.5w of energy CW, but if given 7v would draw 7a and dim down, but if given 7v and 7a for a short pulse 8000 times a second with that pulse being on for 30% and off for 70% of it's duration then the total energy would be less but the peak energy would be higher during that pulse and the laser would look brighter even though it was putting out less joules of energy.
**In theory, I have not run one at that current for that pulse duration.

With a DPSS laser and other types that are no direct diode, you can do pulsed pump output at higher than would normal be used for CW and push some pulsed higher output within limits as long as you do not damage the crystals.

Direct diodes are different ---no photon pump just electricity---peak output is peak meaning you can't get a higher power out of it under any circumstance.

I understand what you are saying but for a direct diode the peak output is peak output regardless of duration or rate it can not output any higher mWs. Maybe get a fresh one and test highest possible output without burning the diode out--determine the actual peak output.

Not sure how it would relate to brightness -- 4X output results in double the brightness as a rule of thumb but there is a maximum the eye can handle/see/detect--beyond that you don't see any increase in brightness and get into eye damage territory. Could you look at the dot of a 32W 445nm laser and see double the brightness of an 8W laser dot---assuming you could still see at all---who knows ???

If you knew you the peak output value was higher than safe CW output you could make a hand held that runs at 8W CW and have a momentary "Turbo" side button that could pulse it at bit higher for a short time perhaps but I don't see any real point in doing that other than novelty value burning things while wearing goggles that prevent you from seeing the increase in brightness ---then again there are many better and more powerful and better ways to burn things.

Who would want to expose their eyes to those powers anyway or want to make hand held lasers more dangerous that they are already?-why for what purpose? What are the NOHDs for pulsed of whatever peak and so on.

Bottom line is someone needs to experiment a bit and determine the peak output possible from NUBM44-81/NUBM47-A1 to see if it is any higher than 8W and if so how much higher.

Maybe get one of those low cost Chinese "15W" jobs and see what it really does?

In any case good luck with whatever which way you decide to do/try.

 

[Hemlock_Mike]

For some cutting operations, a pulsed system is used
to allow ablated material to clear the beam path using
the gas nozzle around the objective lens.
HM

 

[RedCowboy]

That's interesting Encap, but one thing I think of are the 660/650nm reds that claim a 100mw CW and 240mw pulsed and up, typically the pulsed peak is always higher sometimes twice as much and they are direct P/N junction diodes.

I can see where there would be a limit as to how many electrons can flow to holes at once based on the amount of substrate and the surface area because of the heat from the voltage drop, if you actively cooled the diode it could be driven harder.

Anyway by pulsing you give cooling time in between, it would figure that although there is a limit, that pulse driving the diode could produce higher peak energies by driving it harder than it could normally stand but for short duration pulses, however the total energy ( joules ) would not be any greater.

p.s. I included the images for readers to see, I'm sure you already know all about how they work.