Does anyone know if all of these LEP flashlights are using the same wavelength laser to excite the phosphor? What do they use? I know a blue wavelength, but blue laser diodes can be purchased fairly inexpensively from 405 to 460 nm.
They will likely all be close to 460nm because that's where the Ce:YAG Phosphor has the highest absorption rate and also where the most powerful laser diodes can be had.
Update:
The NUBM44 450 nm laser diode is the most powerful blue right now I am aware of producing about 8 watts output, there are 465 nm diodes such as the NUBM07E which can produce about 3 watts at 465 nm or so, but not eight watts at that long of a blue wavelength.
Last night I pointed a 410 nm violet-blue 1.5 watt laser pointer at the phosphor of a SBT90.2 LED and the light output from its surface was brilliant white, I tried 450 nm and the output was a dull yellow. Although not sure what phosphor they are using for that diode.
450nm is almost the same as 465nm. In this case only the output of the laser diode really matters. So yes, the NUBM44 is probably the most powerful.
How bright is your 450nm laser? It's very unlikely that the phosphor of the SBT90.2 LEDs does not have it's maximum absorption at 450-465nm.
I have tried this myself with an Osram Black flat here (in German) and a 3W ~445nm diode. The Osram LED became brighter when lit up by the laser even when it was running at full power and the laser was not even perfectly focussed on the LED (no cylindrical correction optics, only a standard "G2" focussing lens).
My available test wavelengths:
I have several blue laser pointers, I'm afraid to use the eight watt one on my flashlight, may damage it. The powers available to me are 200 mw, 1 watt, 3 watts and 8 watts from 405 to 488 nm (450 nm @8W). I tried the 200 mw 450 nm laser and the 1.5 watt 410 nm pointer produced the best result. As a note to your concern about unequal drive powers into the phosphor, I defocused the 410 quite a bit to roughly approximate the power density of the 200 mw pointer and I could clearly see 450 nm was far less effective at producing much output, only seeing some yellow.
Splitting nm hairs:
When I say the wavelengths are far different I'm coming from a visual standpoint. For myself, even 5 nm makes a big difference in how the tint of a beam appears to me. Because our eyes are less and less sensitive to the shorter blue wavelengths, I prefer the longer wavelength blue lasers, so the difference between 450 nm and 460 nm is very substantial to me, but of course the sensitivity of our retina to wavelength isn't what we are discussing.
Back to what I'm looking for:
I'm really curious what wavelength most LEP flashlights are using to excite the phosphor, I have a W3 Pro and a spectrometer good to .2 nm accuracy, time to set it up and try to find the answer for that flashlight. So far, searching Google, I haven't found much information regarding the excitation wavelengths used in LEP's, so far only the mention of blue wavelength which is fairly wide in terms of the blue visual spectrum, in nanometers. However, there are only a few common wavelength of blue laser diodes, such as 445, 450, 460, 465 nm (plus or minus a nm or so), the shorter wavelengths being able to produce substantially greater amounts of coherent light output.
Where to get LEP optimized phosphor for blue pump wavelengths?
Anyone have a recommendation of where I can purchase the phosphor, or the phosphor targets being used in LEP flashlights? Seems they are secret sauce in this industry now, not much can be found, I'm unable to find samples available for the ones used in these flashlights.
I was able to find some phosphor coated disks (with the outer edge in a ring coated, not the centers) used with laser projectors which respond brilliantly to 410 nm. Perhaps I will use those for my home brew LEP flashlight I want to build. I'd like to build one which can produce several times the lumen output of the LEP's available to me in the market right now.
You can get them here for example. They also offer complete modules like this one. Last year they also offered modules without the pre-collimator lens for use in reflectors. I have one of those. You can find a test of this module here (in German), done by someone I know. Here is a BLF-thread on these modules. Here you can buy a similar module, but with pre-collimator.
The_Driver: Great, I owe you for this help, was able to open and go to each link fine, translating the German to English using an online tool. I ordered some transmissive white phosphor plates through Alibaba a few minutes ago.
I've received a response from one vendor, and found more information from another the blue pump wavelengths vary some, these two show 440 to 455 nm. While both in the blue spectrum, these wavelengths are far different from the 410 nm violet-blue laser diode pump which works so well with some phosphor wheels I have from laser projectors, the 450 nm wavelength not working well at all on them.
If and when I get the transmissive plates I just ordered I will try both 410 and 450 nm and report back how well they work with them, I expect the 410 nm won't work well as the plates I ordered are designed for closer to 450 nm.
Why are laser diodes used to pump these phosphor plates? Simply because they can be focused into a much tighter beam spot upon the target and not because coherent light itself is needed beyond that characteristic?
Chris
I have the new Ant-man titanium coming with the new driver going to make a vid on it see if it’s Actually 300 lm with more range
Blue Laser diodes reach a much higher luminous intensity than blue LEDs. As long as the Phosphor doesn't overheat this is also the case after the conversion to white light inside the Phosphor. The luminous intensity can be much higher.
The "tighter beam" is just a byproduct of physics. The emission surface of a laser diode is much smaller than a typical blue (white) led.
I think everybody here would enjoy you letting us take part in your progress with whatever you are building. Pictures etc. are always welcome. A new thread would be good idea if you plan on doing that.
I understand the physics of a laser diode, for the most part, although for me there is always something more to learn as I am just a hobbyist with them. When you say luminous intensity in my view this is simply due to the size of the focused spot they can produce being much smaller than an LED can possibly focus down to, so in that respect, if I understood you, I believe we are on the same page.
I'm guessing it's the amount of power density we can achieve with a finely focused laser diode output compared to an LED is what makes the difference and why laser diodes are used. Perhaps the narrow line width of the laser diode could help too? There are so many things I need to understand about how this phosphor behaves for maximum efficiency or output.
Am I correct that the beam from the laser diode is focused to a very fine point, or is the beam focused to a larger spot than they can really produce in order not to burn the phosphor target? I've been trying to find the answer to that question too. The drawings I've seen of LEP's appear to show the laser diode beam focused down to a tight spot in some illustrations.
I always have lots of laser projects being worked at the same time, at least for gathering parts and then later assembling. Seems I can't just start and finish one project at a time, this slows my progress on any one thing. My current laser projects are a 2 watt 577 nm OPSL laser and an eight X 525 nm green 1 watt NDG7475 laser diode pointer, all outputs being run in a tight circle with a long focal length collimator for each beam to reduce the divergence. Those eight diodes can be pushed harder to 1.25 watts or more output each to allow over 10 watts total of 525 nm green.
Thought this was interesting.
laser module $24.62 | 4.75W white laser/4.75W blue laser diode converted to white laser module
Tried the link, but doesn't work.
Thanks! I see, but the price displayed for me is over 100 USD for the LEP module, maybe you meant the laser module alone? The price displayed for that here is close to 90 USD. Still not too bad a price for use to build a multi-output flashlight using several of them.
Better to use 1 and a big lens or 2
For these LEP flashlights, do you know what the relative relationship of the divergence is when using a lens focal length which is double? For a regular laser beam colimated to infinity, doubling the diameter of the beam reduces the divergence by half, is this the same for the incoherent light from a LEP too?
Hi bros, do you reckon 1k lumens LEP single head is possible? Don’t have to be ultra high cd. Just 1-2 mil cd range is fine.
The Nextorch T20L is 900+ lumens.
And welcome back, haven't seen you for a long time :)
Thanks man, will check it out.
The Nextorch T20L looks interesting, but 20 watts of laser source ought to produce far more lumen than that, maybe their claim of 20 watts is wall plug efficiency, so to speak. Lots of Chinese are selling "20 watt" lasers on ebay but they are not telling you the output power, but instead a rough number for the input power which to me is a very dishonest misrepresentation, because we don't look for the wall plug power when shopping for lasers, only the output. The NUBM44 laser diode is a 6 watt rated output diode which can be pushed to about 7 to 8 watts output, that is likely what they are using in it, or a newer version of that diode at 8 watts.
Edit: Although I am new to researching LEP flashlights, from what I gather so far, if using a reflector/mirror target with the laser diode the output in lumens is close to 125 lm per watt of laser diode pumping, if the phosphor is the through type, where it is back pumped from the laser, the output is about 20 percent less per watt of laser power. In either case, a 20 watt pump laser should be able to produce more than 2000 lumen, if the phosphor could take it. I am not sure if using the word pump is appropriate for this application or not, maybe someone can help me with that as well as my estimate of lumen per watt of laser power..