574nm 36 mW Yellow Laser

[Nexgen]

Unit came from OPT lasers. Shipping took 2 days.

Added a small heatsink, but that’s not enough, still hot.
Current draw and power (IR Diode)
39mW@1.5A
49mW@1.7A
65mW@2A
70mW@2.3A

Diode has rollback at 3.3A (yellow gets dimmer)

IC has label “OPT 2.0A PSU”

 

[Encap]

Unit came from OPT lasers. Shipping took 2 days.

Added a small heatsink, but that’s not enough, still hot.
Current draw and power (IR Diode)
39mW@1.5A
49mW@1.7A
65mW@2A
70mW@2.3A

Diode has rollback at 3.3A (yellow gets dimmer)

IC has label “OPT 2.0A PSU”

Great photos--product is looking a little bit improved.

 

[paul1598419]

I believe that heat sink on the bottom of the driver has an output transistor attached to it. If you are going to over drive this, I would look into adding a fan to carry all that heat away as quickly as possible. It seems to work well on the lower power drivers. I have had a chance to experiment with two of those drivers so far. And I have a spare too. Just in case.

 

[Deleted member 16589]

Unit came from OPT lasers. Shipping took 2 days.

Added a small heatsink, but that’s not enough, still hot.
Current draw and power (IR Diode)
39mW@1.5A
49mW@1.7A
65mW@2A
70mW@2.3A

Diode has rollback at 3.3A (yellow gets dimmer)

IC has label “OPT 2.0A PSU”

at 2 Amps whats the voltage on the diode?

 

[paul1598419]

Looks like he was driving it with that PS. If so, the Vf is 1.59 volts at 2 amps. Sounds about right as I had mine up to 1.61 volts at around that same current or a little above.

 

[Nexgen]

Yes, Paul is right. What’s power of yours at 2A? If it can reach that of course.
At 70mW beam is amazing on this.

I’ve checked operating current on that diode is 2.5A so it should be safe up to this range.

It’s not rolling back at 3.7A that’s strange. Just ran it 2 seconds at that current.

 

[Deleted member 16589]

Looks like he was driving it with that PS. If so, the Vf is 1.59 volts at 2 amps. Sounds about right as I had mine up to 1.61 volts at around that same current or a little above.

Thanks I did not catch that.

Yes, Paul is right. What’s power of yours at 2A? If it can reach that of course.
At 70mW beam is amazing on this.

I’ve checked operating current on that diode is 2.5A so it should be safe up to this range.

Wow I expected the voltage to me way higher considering how hot these drivers get.

When did you order yours? I ordered last month and like others are still waiting.

 

[Nexgen]

I ordered mine week ago. Just wrote to OPT asking what they have. They offered me 50mw units 60$ each. But there were only 2 in stock. So I got them.

 

[paul1598419]

Good for you, Nexgen. I am really very happy with mine. Since I did the mods I've already posted about it can run indefinitely without a problem. I know I'm getting at least 50 mW, but until I get an LPM out and measure it I won't know exactly what the power output is on mine. I've had other projects taking up my bench, so it could still be a few days before I get it setup and measured.

 

[Nexgen]

Just woke up and measured my laser again, results are pretty interesting on cold starts. At 2.5A it peaks 88mw, which is highest current for that diode. I’ll be receiving second unit and measuring it. But what for a module, it’s 20mm as in previous units.

BTW, thanks for 3M rep :yh:

 

[Alaskan]

Great, nice amount of power and like that new heat sinked driver. I'm hoping to receive my Blitz Buck driver soon to one of these in a host.

 

[DTR]

All this interest in yellow lasers led me to this while looking for info how these two wavelengths are created.

Optics Communications
Volume 387, 15 March 2017, Pages 357-360

End pumped yellow laser performance of Dy3+:ZnWO4
ZhongchaoXiaFengpoYan

https://doi.org/10.1016/j.optcom.2016.12.008

Highlights
A square filter is used for TEM00 selection, which is from the Fine Processing.<br>

A novel continuous-wave blue LD pumped Dy:ZnWO4yellow laser at 575 nm is reported.
The laser output is up to 110 mW and the slope efficiency is 13%.

Abstract
We report an end pumped single transverse-mode (TEM00) yellow laser based on Dy3+:ZnWO4 crystal. The pump light is InGaN blue laser diode at 450 nm with the maximum power of 1.5 W. A 3 cm length Dy3+:ZnWO4 crystal served as the gain medium. By way of the square filter, we discuss the TEM00 properties. In continuous-wave operation and single transverse-mode, a maximum output power of 0.110 W and a slope efficiency of 13.0% are achieved at an emission wavelength of 575 nm.
Dy3+:ZnWO4
Yellow laser

https://www.sciencedirect.com/science/article/abs/pii/S0030401816310719

Yep these are coming. This post is kind of buried now back in the middle of this thread.

https://laserpointerforums.com/f40/574nm-36-mw-yellow-laser-102893-22.html#post1535339

 

[kecked]

The reason that driver is running so hot is the wasted power. If the current is 2A and Vf is 1.59V the diode is dissipating 3.18W BUT.....The driver is running on 12V so the voltage drop on the drive transistor/FET is 12V-1.59V=10.41V So it's wasting 21W of heat continuously. That's a LOT of wasted heat. What is needed is to reengineer the driver to run on say 5V Now you only have to deal with 7W of heat. That is 1/3 less heat just by dropping the voltage on the drive.

I replaced the driver and am running it off 5V. The heat is still non trivial but no worse than running any other diode at 2A. Difference is the other didoes give watts of output.

A second idea is to add a 2-4W Ohm resistor in line with the diode now you have a second place to dump the heat 1.59VF + (2A/10.41V=0.19Ohm) + 2A*3Ohm=6V(12W)

So now the FET has 12v-1.59V-6V=4.41V across it which is 9W Diode 3W FET 9W Resistor 12W(resistor plus fet) which is still wasted but at least you can shift the heat to other places with still enough voltage to forward bias the fet. That 12W 3Ohm could and should be a set of 5W units in parallel. You might be able to go to 4Ohms but the voltasge for the FET is getting skinny.

So that's my idea for a simple non invasive hack. Since the driver is constant current the divide the voltage and conquer should work. Try it and let me know what you get. easier enough with zero risk. Someone should measure the actual voltage on the fet as they might be dumping the heat in an other place.

There is a reason the driver stops working at 9V so that needs to be account for in my calculation. I am skepitcal of my analysis for this reason.

PS, the heat from that driver heats the electrolytic very strongly. It's a matter of time till it fails taking the diode with it.

 

[Alaskan]

I've never felt an electrolytic so hot on any circuit board before, those are my same thoughts, it will have a much shorter life due to that.

 

[paul1598419]

Since no one is using AC to drive these, that electrolytic should be able to be removed. I was concerned about that cap when I first got my unit. I actually ruined a driver trying to remove the heat sink I had on the IC too close to the electrolytic. But, it still gets far too hot for what it is.

I don't see these giving off 21 watts of waste heat. The driver doesn't pull that much power in total, so it can't give off that much waste heat.

 

[Skittles]

I believe that heat sink on the bottom of the driver has an output transistor attached to it. If you are going to over drive this, I would look into adding a fan to carry all that heat away as quickly as possible. It seems to work well on the lower power drivers. I have had a chance to experiment with two of those drivers so far. And I have a spare too. Just in case.

How would you attached a fan to it, do you have pics?