LEP Modding Discussion

Hi guys, not sure if thread like this has been created before but I think we may start our journey on flashlight modding with LEP. :sunglasses:

Done some quick searching on Google, and found that this SoraaLaser is a company that creates white light laser SMD components. Based on the specifications as mentioned in this article, their emitter produces 500 lumens of output and able to produce about 2 degree of beam angle with 1” of optics. It seems like the Weltool W3 and the Acebeam W10 are both using this emitter but please correct me if I’m wrong, anyway I’m not sure there are how many LEP diode major players out there at the moment.

It has a 7070 footprint, which is something similar to the XHP70.2 emitter. We need a DTP MCPCB board and a driver to run this device and the lambertian emission angle is 120 degree, so does it mean that it can work with reflector as well? I am thinking if we can run it in our Convoy C8 one day :laughing:

Any idea where to purchase this LEP, how much does it cost and has anyone has any experience playing around with it?

Acebeam is not using it, they are using a different module.
The more important specification of such an emitter is not stated - the luminance. But 500lms is probably similar to lights like the Acebeam W10 if you factor in the high losses of using a single aspheric lens without pre-collimator. It might actually be a bit dimmer.

Check out this thread (it’s in German, just use Google translate). I posted a lot of fundamental information regarding LEP.

Ok thanks for the correction and also the informative thread. :slight_smile:

I have some noobie questions if you don’t mind:

  1. What is the typical lighting angle from these LEP? 120 degree?
  2. Do they work with reflector instead of lens system?
  3. Is it possible to find a way to develop a driver to run one of these LEP in our flashlight?
  4. Where can I purchase LEP currently?
  5. If we’re talking about 10x more of luminance than our currently available LEDs, does it mean that the luminance is near to those short-arc xenon bulb already?

Thank you!

1. Theory says that the angle is rather wide because the converted light is isotropically scattered (in all directions).
2.Theory says they will work with a reflector for the same reason. You still need to block the direct laser light passing straight through the phosphor though. Where are gonna put the stopper that actually absorbs the laser radiation?
3. These drivers already exist. You can find them on Laserpointer Forums.com They are very small, but usually don’t have any modes.
4. There is no well known shop yet. Maybe one of those new Chinese LEP companies that have started popping up will sell you something. Be prepared to spend a lot!
5. Yes, 10-times the luminance of the best led (10x 250cd/mm^2) is definitely in the territory of the Xenon short-arc bulbs. Both can go higher though (Xenon short-arc up to 5000cd/mm^2, but only in multi killowatt bulbs). Commercially available LEP goes up to 3500cd/mm^2 (Osram Phaser). With a properly cooled phosphor Crystal and a large laser bank much higher numbers should be possible though.

  1. 120 degrees is down to 50%. The total angle is 180 degrees with a cosinusoidal distribution just like a flat LED like the black flat.

2) yes, just like a a regular LED.

3) you just need a constant voltage driver instead of constant current. The voltage will depend on what laser you use and how much power you want it to run at.

4) You can’t, you need to make it yourself using a blue laser and a phosphor.

5) My theoretical calculations show it can be more than any short arc bulb that exists, but it will be a few months before I can do any real world testing.

But at what point will the phosphor get too hot?

And when you shine the laser through the phosphor, how can you cool it?

Wouldn’t it be better to stick the phosphor on a alu coated reflector?

Thinking about a tiny indentation in an aluminium plate, alu coated like a regular reflector.
Put a tiny phosphor in the indentation and direct the blue laser at straight angle to the phosphor.
So that the blue laser light (after passing through the phosphor) reflects on the indentation surface, so that it wil be scattered and becomes a part of the output light spectrum, like with ordinary blue pump LEDs.
No need to dump the laser light, phosphor cooled by the aluminium plate.
…but then the laser will be in front of the phosphor…
Hmmm…
Could work well in the Synios beam though.

So anyway, in this case, the blue laser light will pass through the phosphor twice.
Once directly and twice when it reflects off the indentation surface.
You’ll then nees less phosphor than usual or get warmer tint than usual with regular LEDs.

It would be awesome if someone at BLF did the testing and figured out where to obtain LEP parts and how to build LEP flashlights. I’d love to have a small zoomie powered by a LEP.

1) I have not found any research on this so far. I don’t think anybody has done a test of that yet. What I have found is that on a single crystal phosphor you can go to 350C before any significant performance drop, and one place tested up to 14W of laser on a 5mm piece.
I don’t have any info on how to relate W/mm^2 to temperature so we can’t really know the max. laser power we can use.

2) Mount the phosphor plate on a metal piece with a hole in the middle. The phosphor will conduct heat to the parts touching the metal. If you use a powder phosphor instead of a single crystal the heat conductivity is much worse and that’s why you can’t use very powerful lasers with it.

3) There are two methods of doing laser phosphor, one is through-style and the other is reflective style.
According to a company I’ve talked to, the through style (laser on one side, output on the other) is the best way to get the highest intensity.
The other way will have a reflective metal directly behind the phosphor so that the light comes out the same size that the laser goes in.
I agree this is likely better for cooling but you still have laser light that goes through the phosphor and bounces back out so you need to make sure it doesn’t get reflected back into the laser diode or it can cause damage.
The phosphor does not absorb all of the laser light.

4) Passing the laser through twice will likely increase the efficiency, but I’m not sure how it would affect the intensity.
I haven’t found any data on the polar distribution of emission on a laser-phosphor system.

3) Yeah, that’s why i propose an indentation or cavity, so that the laser light won’t simply bounce back to the laser, but scatters and becomes part of the spectrum, like in ordinary LEDs.
The cavity will probably have to be a tiny parabolic mirror for the best results, but how on earth are you gonna accomplish that…
Maybe settle for a spherical cavity then… That should still be somewhat DIY-able…

Will the phosphor alone not diffuse the laser light already?
Not enough apparently…

Interesting stuff. :+1:

That may just be going on with the current LEP flashlights, that scattered blue is then simply part of the white spectrum of the flashlight. (not sure if that is what happens, you could check with a simple polarising filter if the tint changes when rotating the filter)

Some of the laser radiation goes through without being scattered, see my thread. There is a presentation linked there which contains a picture showing this.

I read the first post of your thread (in german, could not find Google translate to work) and it is a nice overview of the subject, thanks!

The benefit of having it in reflective configuration is to have metal right behind the point where the laser hits the phosphor, for better cooling and to also redirect the light back forward.
It should not be a parabola or cavity, it needs to be flat, so that the light is emitted normally in a hemisphere, because in recoil the collection mirror is to the sides of the light source, not in front.

Most of the laser light is converted to white by the phosphor, and some is simply scattered and adds to the blue spectrum, but there is still a significant amount that goes straight through.
This small amount is still dangerous.
Imagine a mirror that reflects 90% of light, 10% will still go through, and if the laser is 6W then that’s 600mW getting through and that will instantly blind anybody within a few tens of meters.

“This small amount is still dangerous.
Imagine a mirror that reflects 90% of light, 10% will still go through, and if the laser is 6W then that’s 600mW getting through and that will instantly blind anybody within a few tens of meters.”

If I understand correctly what you’re saying, we will now have essentially powerful blinding lasers hidden in innocuous looking flashlights. If the flashlight isn’t modded correctly and safely with an LEP I may as an innocent bystander get permanently blinded by someone not knowing WTF they’re doing.

Sounds great can’t wait. :disguised_face:

Well, there is one exception to that, and I happen to have it here. A 500W lamp that has a peak value of 5400 cd/mm^2 Average luminance is of course a bit lower.

Yes, that’s why all LEP flashlights you see have a laser sink or 45 degree mirror in the center of the lens.
That’s where the laser is pointing at, and the sink/mirror blocks it from coming out of the flashlight.
It certainly is very dangerous, more than even the UV from short arc bulbs.

High power lasers are already easy to buy by just anyone though, so it’s not like the risk is increased much, there are already plenty of idiots waving blinding lasers around :confused:

Your searchlights are an inspiration, have you used that bulb in one of your projects or is it for an upcoming project? :slight_smile:

And I know what you are using it for ;).

Is there a datasheet? I have never seen such a high value for such A “small” bulb.

I am not sure but this LEP is in SMD package at 7070 size, looks like it is available in a form that similar to our LED no?
And for this LEP the laser diode seems to be shining on the phosphor at an inclined angle and then reflected to the front, not really “through” the phosphor right?

This isn’t what these laser flashlights are using though.
It’s just a proprietary design from SLD laser.
Another way of doing things.

It likely gets far lower performance though, since everything needs to be compacted so much.
The laser isn’t very large, the laser doesn’t have good cooling, the phosphor doesn’t have good cooling, etc.

I think you misunderstand me.
I can’t make a drawing now since i’m on my phone abroad this week.
But when you hit a flat surface with a parallel laser beam, it will obviously reflect straight back to the laser, which we do not want.
However, when it hits a tiny parabolic cavity, you have the reverse of a recoil light, although you do have a focal point there.
But the laser light will spread from there, along with the light from the phosphor.