Received the second component of my future project

Have you considered some transparent cooling, f.e. liquid loop? I would be scared of bubbles but if you can sort it out - maybe that wouldn’t be bad…

^ Yeah, i suggested that too, earlier.
Water.
Flowing on both sides of the Phosphor, sandwiched between thin glass or PMMA.
AR coated if that’s worth it.
The Phosphor will have a really hard time getting hot with direct water cooling.
Water is great stuff. It’s also as clear as water ! :stuck_out_tongue:

I don’t think it will be close to 2000lm, maybe 500 or a bit more, apparently about half of the laser light doesn’t enter the collimation lens.
Using some special combinations of lenses I could make 100% of it go to the 0.1mm spot on the phosphor but first I need to check that it won’t get damaged as it currently is.

Also, I already said this before, but water has a very low thermal conductivity.
Less than 1w/mk.
Just because it has a high heat capacity doesn’t mean it will cool the object well, because the area is so small that the heat transfer to the water will be miniscule.
You need a material will high thermal conductivity to move the heat away, then have high surface area to transfer that heat to the water or air efficiently.

This is why CPU heatsinks and waterblocks use copper to move the heat to large areas of fins, which THEN are cooled by water or air.
You can’t cool a computer by running water or air directly on the CPU.

You would get electrical issues when you do that… :stuck_out_tongue:
But i see your point.
But water is of course much better than air.
I don’t know. Maybe you’re right.
It’s a ‘gut feeling’ i guess, that convinces / persuades me to believe a thin wafer of Phosphor, basically sitting in rushing water has a really hard time to get hot.
But since you’re planning on hitting only a 0.01mm² spot, i’m not so sure…

Tell me if i’m boring you, but i had another thought:

Maybe place the Phosphor wafer in a ball bearing and spin it so that the laser point never hits a single spot for a long time.
You could add motion to the whole bearing so that it doesn’t only hit the same circle on the Phosphor.
Yeah, a lot of hassle, i guess…

Looking forward to this one! Fresh tech and new implementation, is always exciting.


I also need to correct The Driver, the BFF is definitely not 250Mcd. There is a reason I have said it start with a 1.

If you want you can calculate what equilibrium temperature the crystal would reach if it was in water.
I can tell you right now that 18mm^2 of area will reach a very high temperature before 3W of heat are carried away by the water…

Also rotating phosphor is what many projectors use:

Doing this with a single crystal phosphor would cost tens of thousands of dollars, assuming you can get a piece that large.

Thanks :stuck_out_tongue:
I’m still waiting for more updates on yours!

Suggestion, wear an eyepatch over your best eye whilst working on this. And please don’t shine it in my direction.

No worries, update is coming, just been busy with some other stuff.

You need to use two ar-coated (specifically for 450nm) cylinder optics together with a G7 focussing optic to get the best possible hotspot, highest efficiency and least amount of stray light. The cylinder lenses correct for the differently expanding axes of the rectangular laser beam. This can easily cost 100$, but it’s worth it.

The optical assembly and the cooling will probably give you the most grief.

Did you get a suitable, adjustable laser driver? I know a very compact one if you need it.

The engraving lasers they sell are doing .1mm^2 without any cylindrical optics, so I’m going to try that first.
There’s no point in spending $450 on an acylindrical lens if I’m already burning through the crystals without it.

The driver I bought can be regulated by 5v in addition to a current trim pot to adjust the maximum.

Also comes with a temp sensor for protection of the laser diode :slight_smile:


More expensive stuff.
Hopefully I don’t blind myself.

Lovely eyewear… :laughing: I hope it does the job it was created for. :sunglasses:

Be Safe! …but have fun. :+1:

It was like $50 and apparently much better quality than the cheap ones you can get form china, so it better be :stuck_out_tongue:

Be gracious and don’t be surprised if someone mistakens you for Elton John and asks for an autograph. :open_mouth:

hahaha

I’m already dazzled. :beer:

Nice. Looking forward to watching this build. No g-ball lens built into the can. 7 watt 450nm diode from a NUBM44/47 bank?

Thanks, yeah its a nubm44 :slight_smile:

I hope that mount has the right tolerances to press fit the diode, otherwise you get thermal issues

also a TEC cooling is needed to keep the diode cool if you want to drive it hard

I’ll heatsink the diode with thermal paste or liquid metal.
I’ll be making my own mount for the diode so I can probably do pressfit too.

With a large heatsink you can do 6-7W without a tec, see some of the videos on youtube.
A tec is more necessary for 8-10W which is pretty extreme.

I’m trying to keep the amount or parts minimized for highest reliability and lowest price, so that means no liquid cooling or fans or tecs.