Yeah probably about that much.
A research paper got 4k lumens with 14W of lasers.
The highest power single blue laser is about 7W though, so about 2k lumens, not sure how much will be wasted out the back, maybe 50% or maybe less.
Possible, but I need to have cooling on that side so I canât fit a second collar.
My imagination runs wild, but i have no data / specsâŚ
Is the phosphor water resistant?
Thinking glass - water - Phosphor - water - glass sandwich, water pumped through the sandwich.
Because obviously the Phosphor will get crazy hot when you point a metal cutting laser at itâŚ
Iâve been thinking about the âreflecting LEPâ too, with an extremely tiny parabola behind the Phosphor, a tiny dent in a aluminium (coated) heat sink.
The dent has to be filled with a piece of Phosphor.
I think it will produce horrible tint shift artefacts thoughâŚ
Other than that, itâs so small, how are you gonna shape a 1 - 2 mm diameter parabola in a piece of metal, and coat it with PVD ?
Let alone put the right shape of Phosphor in thereâŚ
Yeah itâs water resistant, itâs just a crystal.
Water would change the refractive index and would probably make focusing stuff problematic.
Also even though it has very high heat capacity the conductivity is not that high so the small area of the crystal wouldnât dissipate much heat.
There have been experiments using liquid which has phosphor particles in it within a cooling loop so itâs cycling the phosphor through a radiator for cooling.
Maybe iâm under- or overestimating something, but 0.25mm of anything sandwiched between running water will have a very hard time getting hot.
All will go dramatically wrong though, when the water reaches 100°C somehowâŚ
Canât imagine that happening with proper water flow though, but i could be wrong.
But water is an awesome cooling medium. Very high thermal capacity.
Oh, and itâs as clear as water, of course.
Interesting idea.
Youâll need more Phosphor thoughâŚ
But i guess powdered Phosphors, as used in LED dies are not that expensive.
One more question.
What diameter laser beam do you plan on hitting the Phosphor?
1.5 mm ? Less?
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 wouldnât be badâŚ
^ Yeah, i suggested that too, earlier.
Water.
Flowing on both sides of the Phosphor, sandwiched between thin glass or PMMA.
AR coated if thatâs worth it.
The Phosphor will have a really hard time getting hot with direct water cooling.
Water is great stuff. Itâs also as clear as water !
I donât think it will be close to 2000lm, maybe 500 or a bit more, apparently about half of the laser light doesnât 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 wonât 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 doesnât 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 canât cool a computer by running water or air directly on the CPU.
You would get electrical issues when you do thatâŚ
But i see your point.
But water is of course much better than air.
I donât know. Maybe youâre right.
Itâs a âgut feelingâ 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 youâre planning on hitting only a 0.01mm² spot, iâm not so sureâŚ
Tell me if iâm 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 doesnât only hit the same circle on the Phosphor.
Yeah, a lot of hassle, i guessâŚ
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 waterâŚ
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
Iâm still waiting for more updates on yours!