Received the second component of my future project

Sounds like a fun project!

I know you are all about the luminance, but I wonder how much output you can get. Say you get a 10W output blue laser. Max theoretical efficacy for excited phosphor is 300 lumens/W. Say you get half that to account for phosphor inefficiency and light emitted backwards. Then that is 1500 lumens. Is that on the right track?

You could put a hemispherical reflecting collar on the bottom too to recycle the light going down.

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 can’t fit a second collar.

Wish i had the funds for such things…

Planning to make it a ‘shine through’ set up?

Does that phosphor emit only yellow or is it a wider band?

Are you gonna get pieces of diamond to $andwich the phosphor?

Yeah it will be through.
It emits a spectrum of light like a regular phosphor would:

I bought the yellow.

No I can’t afford diamond plates for cooling :smiley:

Interesting. :+1:

My imagination runs wild, but i have no data / specs…

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 it… :wink:

I’ve been thinking about the ‘reflecting LEP’ 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 though…
Other than that, it’s 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 there…

How thick is the Phosphor you bought?

Yeah it’s water resistant, it’s 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 wouldn’t dissipate much heat.

There have been experiments using liquid which has phosphor particles in it within a cooling loop so it’s cycling the phosphor through a radiator for cooling.

The phosphor plates are 0.25mm thick.

So is salt. :slight_smile:

You’ll get it focussed, i’m sure. :slight_smile:

Maybe i’m 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 somehow…
Can’t 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 it’s as clear as water, of course. :stuck_out_tongue:

Interesting idea.
You’ll need more Phosphor though…
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?

It will be concentrated, not sure how small I can go before burning the crystal but I’m gonna try .1mm square.

.1 mm² ?? :open_mouth:

0.1 x 0.1 mm
:slight_smile: :slight_smile: :slight_smile:

Wouldn't that be 0.01 mm²?

yeah, a square with side length .1mm.

0.01 mm² ??

Well, you can burn quite a few 0.1 mm² holes in a 9 mm² Phosphor…

Haha true :stuck_out_tongue:

Hmm…2000 lm from 0.01 mm²?
That’s over 60 000 cd/mm², nearly 160 times brighter than the current LEPs used in flashlights.

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.
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…