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Thread: Phosphor conversion of photons in LEDs & photon recycling efficiency

  1. #1

    Default Phosphor conversion of photons in LEDs & photon recycling efficiency

    I know that phosphor in an LED converts some of the blue photons supplied to it into yellow photons to create white light.

    I'm wondering what happens when other colors of photons are supplied to the phosphor. What would happen if green photons enter the phosphor layer? Yellow photons?

    Thanks.

    Edit: Also interested in understanding photon recycling efficiency that increases LED luminance. How are the losses in a waiven collar accounted for when photons are sent back to the die for recycling? In the set up below (credit: SMA@ Taschenlampen Forums), the gain is 2.2x over the fraction of light defined by the flux ratio of solid angles for a 30 degree half angle beam opening--a 55% efficiency of a potential of 4x. The reflector is 99% efficient but it seems to pass quite a bit of light despite the rating.

    Last edited by Genzod; 03-02-2018 at 07:00 PM.

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    Default Re: Phosphor conversion of photons in LEDs

    Generally a phosphor provides photons at a wavelength (color) related to its molecular and crystalline structure, and not related to the wavelength of the incoming light. If the wavelength of the incoming light becomes too long, the phosphor won't emit any light.
    Jim

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    Default Re: Phosphor conversion of photons in LEDs

    There are differences between blue and violet pumped emitters, for example ...

    http://www.candlepowerforums.com/vb/...mid-power-leds
    ... is the archimedes peak

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    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by brickbat View Post
    Generally a phosphor provides photons at a wavelength (color) related to its molecular and crystalline structure, and not related to the wavelength of the incoming light. If the wavelength of the incoming light becomes too long, the phosphor won't emit any light.
    So if you have a typical blue emitter with yellow phosphor, the phosphor crystalline structure is designed to create yellow photons. But if the wavelength of the emitter increases, the generation of yellow photons will decrease until a point is reached where no more yellow photons will be generated, is that correct?

    If so, is that because the energy difference between the emitter source photons and the phosphor photons is approaching zero? Hence a hypothetical red or orange emitter can't give rise to yellow photons in that yellow phosphor?

  5. #5

    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by archimedes View Post
    There are differences between blue and violet pumped emitters, for example ...

    http://www.candlepowerforums.com/vb/...mid-power-leds
    Indeed. When Violet Beauregarde ate the yellow phosphor gum, the violet pumping was so markedly increased, she had to be rolled away and juiced.

    Last edited by Genzod; 02-25-2018 at 05:46 PM.

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    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by Genzod View Post
    So if you have a typical blue emitter with yellow phosphor, the phosphor crystalline structure is designed to create yellow photons. But if the wavelength of the emitter increases, the generation of yellow photons will decrease until a point is reached where no more yellow photons will be generated, is that correct?

    If so, is that because the energy difference between the emitter source photons and the phosphor photons is approaching zero? Hence a hypothetical red or orange emitter can't give rise to yellow photons in that yellow phosphor?
    Normal white LEDs use YAG:Ce phosphor. Here you can see the absorption spectrum of this type of phosphor. It should answer your question.
    This absorption and emission phenomenon is called Stokes Shift.

    Here you can find a nice article on the topic.

  7. #7

    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by Genzod View Post
    So if you have a typical blue emitter with yellow phosphor, the phosphor crystalline structure is designed to create yellow photons. But if the wavelength of the emitter increases, the generation of yellow photons will decrease until a point is reached where no more yellow photons will be generated, is that correct?

    If so, is that because the energy difference between the emitter source photons and the phosphor photons is approaching zero? Hence a hypothetical red or orange emitter can't give rise to yellow photons in that yellow phosphor?
    That is correct, and unfortunately at least at this point in time, only one photo out for each photon in, and as the emitted photons are less energetic, there is an efficiency loss equal to the ratios of the wavelengths.

  8. #8

    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by ssanasisredna View Post
    That is correct, and unfortunately at least at this point in time, only one photo out for each photon in, and as the emitted photons are less energetic, there is an efficiency loss equal to the ratios of the wavelengths.
    Quote Originally Posted by The Driver
    Normal white LEDs use YAG:Ce phosphor. Here you can see the absorption spectrum of this type of phosphor. It should answer your question.
    This absorption and emission phemnomenon is called Stokes Shift.

    Here you can find a nice article on the topic.
    Thanks everyone.

    Up until now, I wasn't sure where the extra energy was going from the shift. I thought perhaps part of the increased surface brightness of an LED undergoing the photon recycling that arises from a wavien collar was coming from the ratio of wavelengths. But now it would appear redirection of the formerly wasted wall light undergoes about a 15% loss from reflection and a tint shift toward yellow of any higher energy photons that make it back into the phosphor, representing a further energy loss due to conversion. The gain in surface brightness in LED due only*to the super-positioning of redirected photons that eventually escape through the collar's hole toward the lens.

    *Unless I'm overlooking something else, of course. Any comments regarding that?
    Last edited by Genzod; 02-26-2018 at 11:12 PM.

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    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by Genzod View Post
    ...I wasn't sure where the extra energy was going from the shift....
    High energy photon enters a phosphor, low energy photon exits. The energy difference shows up as heat in the phosphor, no?
    Jim

  10. #10

    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by brickbat View Post
    High energy photon enters a phosphor, low energy photon exits. The energy difference shows up as heat in the phosphor, no?
    Exactly. In my mind, I had imagined two boundaries describing the energy balance:

    1) For every 100 blue photons phosphor generates 120 yellow photons (assuming wavelength ratio 1:1.2)

    2) For every 100 blue photons phosphor generates 100 yellow photons and the extra energy from the wavelength ratio represents an efficiency loss, e.g. heat.

    (or something in between)

    Answer confirmed above by ssanasisredna as item 2.
    Last edited by Genzod; 02-26-2018 at 11:14 PM.

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    Flashaholic* The_Driver's Avatar
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    Default Re: Phosphor conversion of photons in LEDs

    The Wavien Collar redirects the light onto the phosphor. The blue part is "recycled". It can come back out at a different angle (converted light is scattered isotropically in phosphor) and is converted to yellow-green. 75% of the emitted light (of a domeless LED) is collected by the collar and the remaining 25% is amplified by a max of 120%. Thus the efficiency in terms of lumens is 55%.
    See here for more details (in German).

  12. #12

    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by The_Driver View Post
    The Wavien Collar redirects the light onto the phosphor. The blue part is "recycled". It can come back out at a different angle (converted light is scattered isotropically in phosphor) and is converted to yellow-green. 75% of the emitted light (of a domeless LED) is collected by the collar and the remaining 25% is amplified by a max of 120%. Thus the efficiency in terms of lumens is 55%.
    See here for more details (in German).
    That's a very decent article. Vielen Dank!

    I had likewise introduced the Lambert cosine through each dA area element in the hemisphere and integrated to get the same sin2
    θ result, so it was reassuring I was working with the correct formula.

    With 99% reflectivity, I would think the gain to have been close to 4X, not 2.2x, so I can see where you get the 55% efficiency. Is that inefficiency due the low critical angle of the phosphor and air, resulting in reflections that repeatedly bounce themselves off the phosphor and back to the reflector ad infinitum to eventual absorption?

    If so, would it help greatly to have a roughened phosphor to improve chances of reentering the phosphor so they can reemerge at a steeper angle and have a better chance of exiting the hole? I think that's the case with the newer XPG2 and XPG3 phosphors. I'm wondering if gain has been improved using a collar with those LEDs?

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    Flashaholic* The_Driver's Avatar
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    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by Genzod View Post
    With 99% reflectivity, I would think the gain to have been close to 4X, not 2.2x, so I can see where you get the 55% efficiency. Is that inefficiency due the low critical angle of the phosphor and air, resulting in reflections that repeatedly bounce themselves off the phosphor and back to the reflector ad infinitum to eventual absorption?
    I don't know the answer to that.
    Possible reasons:
    - Phosphor saturated by the heat of the die underneath and the additional heat from the light reflected by the collar
    - the die underneath the phosphor could be overheating from the reflected light causing it to emit less blue light which in turn reduced total amount of available light
    - reflection as you mentioned (what I know: at 90° angle the phosphor reflects ~3% at the phosphor-air-junction)

    Quote Originally Posted by Genzod View Post
    If so, would it help greatly to have a roughened phosphor to improve chances of reentering the phosphor so they can reemerge at a steeper angle and have a better chance of exiting the hole? I think that's the case with the newer XPG2 and XPG3 phosphors. I'm wondering if gain has been improved using a collar with those LEDs?
    sma tested the collars with a de-domed XP-G2 (this LED had the highest known luminance of all LEDs in the beginning of 2015). The phosphor of the XP-G2 is pretty rough. The newer XP-G3 on the other hand has a much lower luminance because the effective die size is much larger. Its die is basically 3D, it also emits light to the sides. Generally it can be said that the XP-G3 is a fundamentally different LED compared to the XP-G2.

  14. #14

    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by The_Driver View Post
    I don't know the answer to that.
    Possible reasons:
    - Phosphor saturated by the heat of the die underneath and the additional heat from the light reflected by the collar
    - the die underneath the phosphor could be overheating from the reflected light causing it to emit less blue light which in turn reduced total amount of available light
    - reflection as you mentioned (what I know: at 90° angle the phosphor reflects ~3% at the phosphor-air-junction)...
    Okay, great to understand other avenues of potential losses. At least heat can be managed.

    I'm a little confused about your last mention. The critical angle (from the vertical) for air and phosphor is about 34 degrees, right? So wouldn't very shallow angles of approach (coming from 90 degrees from vertical) mostly bounce right off the phosphor, like that reflected at the base of the reflector (90 degrees)? It seems like you're saying 97% of photons approaching LED from the bottom of the reflector is absorbed (3% reflected). I'm thinking 3% absorption and 97% reflection at that horizontal vector. Maybe our angle conventions are opposite, or I'm just not familiar enough with the physics here.

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    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by Genzod View Post
    Okay, great to understand other avenues of potential losses. At least heat can be managed.

    I'm a little confused about your last mention. The critical angle (from the vertical) for air and phosphor is about 34 degrees, right? So wouldn't very shallow angles of approach (coming from 90 degrees from vertical) mostly bounce right off the phosphor, like that reflected at the base of the reflector (90 degrees)? It seems like you're saying 97% of photons approaching LED from the bottom of the reflector is absorbed (3% reflected). I'm thinking 3% absorption and 97% reflection at that horizontal vector. Maybe our angle conventions are opposite, or I'm just not familiar enough with the physics here.
    I meant that when you shine blue light from straight-on (vertical) toward a flat piece of phosphor, 3% of the light is reflected back at the phosphor-air junction. Very shallow angles probably increase this percentage for a flat piece of phosphor.

    Here's a picture of a nicely de-domed Cree LED. Around it you can see the reflective LED package. The exposed phosphor-silicon-mix reflects much less light than the package, it has a much rougher surface. All flashlights with Wavien collar that achieved very high luminance values used de-domed XP-G2 LEDs or now Osram Black Flat LEDs (no dome from the factory, but much smoother surface compared to de-domed Cree LEDs).

    Here you can find some more detailed findings regarding the optical properties of the phosphor-silicone-mix used in LEDs.

  16. #16

    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by The_Driver View Post
    I meant that when you shine blue light from straight-on (vertical) toward a flat piece of phosphor, 3% of the light is reflected back at the phosphor-air junction. Very shallow angles probably increase this percentage for a flat piece of phosphor.
    Okay, haha! Our angle conventions were different and opposite. You were describing a downward perpendicular approach, hence 90 degrees from base, and I was thinking 90 degrees measured from the vertical axis--photons moving horizontally.

    Here's a picture of a nicely de-domed Cree LED. Around it you can see the reflective LED package. The exposed phosphor-silicon-mix reflects much less light than the package, it has a much rougher surface. All flashlights with Wavien collar that achieved very high luminance values used de-domed XP-G2 LEDs or now Osram Black Flat LEDs (no dome from the factory, but much smoother surface compared to de-domed Cree LEDs).

    Here you can find some more detailed findings regarding the optical properties of the phosphor-silicone-mix used in LEDs.
    I'll definitely read that publication, thanks!

  17. #17

    Default Re: Phosphor conversion of photons in LEDs

    I was looking over this reference TheDriver supplied. In the post, SMA is describing his experiment where he determines the luminance gain arising from a large wavien collar centered on a dedomed XP-G2. I'll describe what I think is going on here with this configuration, and I hope someone of experience would jump in to guide and correct my thinking.

    It's hard to say exactly whether the XP-G2 SMA@Taschenlampen Forums pulled out of his scrap box was bare phosphor, had a sealant over the bare phosphor or if the dedome was a slice job with some silicone remaining over the bare LED. If someone here knows SMA, that information would be helpful in my understanding of photon recycling. This fact is critical to understanding the behavior of reflected photons returning to the emitter surface.

    Assuming the XP-G2 has a seal and the sealing material has a refractive index of 1.5 like silicone, the critical angle between air and silicone would be about 42 degrees. (measured from the vertical axis ) If the seal is perfectly smooth (assume for the moment), I would expect all photons approaching the phosphor at 42 degrees or more would simply bounce off the barrier and head to the opposite side of the collar for another 99% reflection and 1% absorption. It would take a number of reflections back and forth like a PONG game to be completely absorbed by the mirror.

    Photons approaching at less than 42 degrees from vertical axis (regardless of wavelength) would enter the seal, then the phosphor, and some with enough energy (shorter wavelength) would be converted to lower energy photons. Those surviving, converted and unconverted photons would take another stab at a favorable exit angle that allows escaping the dome or get stuck in a reflective loop until completely absorbed by the mirror.

    In essence, only the region of the mirror from 30-42 degrees supports increasing the luminance of the LED. The region from 42-90 degrees would eventually be absorbed by the mirror.

    Of course this is not a perfect world with perfect surfaces, so I would expect the line to be less tightly defined (blurred/transitioned). Roughness of the LED surface would change angles of incidence to favor more re-absorption and emission, so I would anticipate the useful area of the mirror might extend beyond 42 degrees a bit.

    If I use the following formula:

    GAIN = K* sin2γ / sin2θ

    (Ratio of flux through solid angles times a correction factor: constant * [critical angle of the die's top layer / half angle of the collar port].)

    Where γ=42 degrees (gamma) is the critical angle of the first layer of the LED and θ=30 degrees (theta) is the half-angle of the collar's port (both measured from the vertical axis), and GAIN is about 2.20 in the posted experiment from Taschenlampen Forums, K becomes 1.23. If I set K to 1 and predict the angle that divides the useful from non-useful regions of the mirror, I get 48 degrees, which is close to the critical angle, deviated only by 6 degrees. I would therefore suspect surface roughness is responsible for the 6 degree offset in prediction of that line.

    If the phosphor were bare, I would expect the critical angle to be around 34 degrees from vertical. The phosphor surface would probably be rougher than a sealed surface so I would expect the line to be lower than 40 degrees but probably not beyond 48 degrees.

    This is all just conjecture from a photon noob, and I'm not trying to assert that that is what is actually going on here. But at the moment, it is what I'm thinking is happening as I'm trying to understand this physics.

    Anyone here with some expertise that can give some knowledgeable insight, guidance or correction? Thanks.


    EDIT:
    Conceptual error: I re-examined my calculations for photons approaching the die at shallow angles.

    Snells law can't describe an angle of approach that prevents photons from entering a slower medium (air to phosphor) like it can in reverse (phosphor to air) to describe TIR.

    If photons in air coming from 70 degrees (from vertical axis) impact the phosphor surface, refraction into the die takes place 31 degrees from the vertical axis. Even 90 degrees has a refractive angle of 34 degrees from normal, as weird as that seems to my intuition (due to particle wave duality). So refraction is always taking place from all angles of approach coming from the collar to the die.
    Last edited by Genzod; 03-02-2018 at 06:43 PM.

  18. #18

    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by Genzod View Post
    I'm wondering what happens when other colors of photons are supplied to the phosphor. What would happen if green photons enter the phosphor layer? Yellow photons?
    Above about 500nm (green-cyan) YAG phosphor has a very low level of absorption.

    Not directly relevant to your question but a while back I was doing some research into blue-green (cyan) phosphors, and with the types of phosphors used in LEDs (including the advanced new ones that have just been developed) it generally takes an excitation source at least 40 nanometers less than the peak emission you hope to get from the phosphor. Try to excite the phosphor with a wavelength that's just barely less than the normal peak wavelength emission of the phosphor and it will end up shifting the wavelength distribution towards longer wavelengths, so that there will still be that characteristic gap in the spectrum. Although the minimum of the gap might be as high as 45 percent of the peak phosphor value.

  19. #19

    Default Re: Phosphor conversion of photons in LEDs

    As to losses: Light converted by phosphor and emitted at wrong angle will not be reflected back and therefore will be lost.

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    Flashaholic* The_Driver's Avatar
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    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by Genzod View Post
    I was looking over this reference TheDriver supplied. It's hard to say exactly whether the XP-G2 SMA@Taschenlampen Forums pulled out of his scrap box was bare phosphor, had a sealant over the bare phosphor or if the dedome was a slice job with some silicone remaining over the bare LED. If someone here knows SMA, that information would be helpful in my understanding of photon recycling.

    In the post, SMA is describing his experiment where he determines the luminance gain arising from a large wavien collar centered on a dedomed XP-G2. I'll describe what I think is going on here with this configuration, and I hope someone of experience would jump in to guide and correct my thinking.
    I know him personally. He used a cool-white XP-G2 and de-domed it using the classic way (imersion in nitro paint thinner or similar). This removes the silicone lens on top of the LED, but does not (to my knowledge) alter the silicon-phosphor-mix underneath. But you can ask him yourself, he is also a member here on the forum.

  21. #21

    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by The_Driver View Post
    I know him personally. He used a cool-white XP-G2 and de-domed it using the classic way (imersion in nitro paint thinner or similar). This removes the silicone lens on top of the LED, but does not (to my knowledge) alter the silicon-phosphor-mix underneath. But you can ask him yourself, he is also a member here on the forum.
    Thanks, Driver. I got a reply from him today. He used a chemical dedome with no sealer. That means the index of refraction is 1.0 and 1.8 and the critical angle is 34 degrees. Since the difference between the virtual critical angle of 48 (that yields 55% efficiency in lumen gain) and the actual critical angle is 14 degrees, I think it implies the exposed phosphor is rough, changing incident angles of photon impacts and facilitating better absorption to capture more of the reflected light.
    Last edited by Genzod; 03-01-2018 at 07:23 PM.

  22. #22

    Default Re: Phosphor conversion of photons in LEDs

    Conceptual error: I re-examined my calculations for photons approaching the die at shallow angles.

    Snells law can't describe an angle of approach that prevents photons from entering a slower medium (air to phosphor) like it can in reverse (phosphor to air) to describe TIR.

    If photons in air coming from 70 degrees (from vertical axis) impact the phosphor surface, refraction into the die takes place 31 degrees from the vertical axis. Even 90 degrees (horizontal to die surface) has a refractive angle of 34 degrees from normal, as weird as that seems to my intuition. So there is always some refraction taking place from all angles of approach coming from the collar to the die.

    What I need to understand now is: to what extent photons are also reflecting off the phosphor at shallow angles of approach. I've seen a % reflection vs. angle of incidence profile for air to glass. Does anyone know where i might find such a profile for air to bare YAG phosphor?
    Last edited by Genzod; 03-02-2018 at 05:19 AM.

  23. #23

    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by The_Driver View Post

    - reflection as you mentioned (what I know: at 90° angle the phosphor reflects ~3% at the phosphor-air-junction)
    Now that I have a better grip on reflection/refraction with Snell's law (considering photons as a particle only without equal attention to its dual wave nature had thrown me for a conceptual loop), I reconsidered what you said here and it makes a lot more sense now, and is very helpful.

    I found this equation for normal reflectance from this source:



    I don't know if this form of equation can be applied generally to the indices of different mediums. Pressing carelessly ahead, using 1.8 for phosphor and 1 for air and substituting, I get 8% reflection for head on air to phosphor. Do you have a reference for the 3% you mentioned?

    For glass, head on, reflection is about 4% with 96% transmittance. When the incident angle approaches about 60 degrees, the efficiency improves (I think close to 0% reflection), then starts dropping again toward 4% reflection as angle continues to become more shallow (as when the aspheric lens is twisted closer to the LED for flood). Here is the profile of reflectance vs. incident angle for glass with more detail beyond 70 degrees in the original plot of this I saw elsewhere. There might be some analogy here with air and phosphor. If I could just find a similar plotted profile for the optical efficiency of phosphor.

    To throw another wrench into my noobular mindset, I'm wondering if bare air to phosphor reflections of light rays returning from the reflector are Lambertian (2nd type) and possibly dominated by yellow green wavelengths?

    Last edited by Genzod; 03-02-2018 at 08:53 PM.

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    Flashaholic* The_Driver's Avatar
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    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by Genzod View Post
    I don't know if this form of equation can be applied generally to the indices of different mediums. Pressing carelessly ahead, using 1.8 for phosphor and 1 for air and substituting, I get 8% reflection for head on air to phosphor. Do you have a reference for the 3% you mentioned?
    Yes, here. It's basically just the fresnel equations.

    You need to take into acount that no LED hast just phosphor. It's always a phosphor silicone mix which mostly contains silicone. Thus you need to use the refractive index of silicone for 450nm: ~1.41
    If you want to be really precise you need to take into account the temperature related shift of the refractive index of silicone and also the temperature related shift of the dominant wavelength of the blue led die.

  25. #25

    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by The_Driver View Post
    Yes, here. It's basically just the fresnel equations.

    You need to take into account that no LED has just phosphor. It's always a phosphor silicone mix which mostly contains silicone. Thus you need to use the refractive index of silicone for 450nm: 1,41
    Okay, I just used the refraction index of 1.8 for a phosphor type LED from Dr. Jones CPF/BLF. I see using 1.41 for silicone you get about 3%.

    I also see in the article reference you provided that the reflection for a phosphor LED type surface is specular not Lambertian. Thank you.
    Last edited by Genzod; 03-02-2018 at 09:05 PM.

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    Default Re: Phosphor conversion of photons in LEDs

    I researched this stuff during the past year for my laser phosphor project. I summarized my findings including the sources here (all in German).

  27. #27

    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by The_Driver View Post
    I researched this stuff during the past year for my laser phosphor project. I summarized my findings including the sources here (all in German).
    What an amazing study! Ausgezeichnet! I had read an article from Dec 2017 where a university was studying laser based LEDs. They said the anticipated results would improve efficacy by 10x over the typical YAG phosphor LED. I was contemplating getting a blue laser and targeting a cooled LED to see how it might improve upon the wavien collar, and you saved me a little work! I was discussing this with Degarb. I think if they are able to provide LEDs with 10x luminance over what we have now in the XPG2, the wavien collar will die an untimely death. Even if laser LEDs cost 10x that of a $3 XPG2, that's still 3-4x less than a wavien collar that only gets you 2.2x.

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    Flashaholic* The_Driver's Avatar
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    Default Re: Phosphor conversion of photons in LEDs

    The LED with the highest luminance (Osram Black Flat HWQP) currently does up to 260cd/mm^2. Osram already offers a laser phosphor module with 3700cd/mm^2. That is in the realm of the best short-arc bulbs (up to 6000cd/mm^2). This module is much bigger though than a XP-G2 based flashlight.

    At the present time laser phosphor modules are much more expensive compared to LEDs. If you want 1000 lumens (to get a somewhat large hotspot) you will need to pay at least 100-150$. You need the expensive diode, the phosphor target and a special laser driver (more precisely regulated). You also need to think about safety if you are using separate components.

    A nice alternative might be the Soraa SLD. It's a smd module with laser and phosphor that doesn't emit any laser radiation.

    The Wavien collar is already "dead". The company is gone. Another company owns the patent, but is not selling it separately and not fully using its potential in the one light they offer.

  29. #29

    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by The_Driver View Post
    The LED with the highest luminance (Osram Black Flat HWQP) currently does up to 260cd/mm^2. Osram already offers a laser phosphor module with 3700cd/mm^2. That is in the realm of the best short-arc bulbs (up to 6000cd/mm^2). This module is much bigger though than a XP-G2 based flashlight.
    The Wavien collar takes up a bit of space itself, and then you have to create more available length in the light cavity to meet a 60 degree beam that ordinarily would be 90-120 degrees. With the wavien collar in the way, the ability to zoom to flood is lost to a great degree. I haven't seen any laser modules as of yet, but I would imagine that the option of constructing the laser to come from under the phosphor would leave the space in front free of obstruction.

    I'm glad to hear Osram is offering an LD module! Could you link me to a sales page for the one you mentioned? EDIT: Okay, called Phaser 3000 and Phaser 500. Got it.

    EDIT: With 3700 cd/mm^2 @40 watts, I get about 2730 cd/mm^2 @18.63w for a maxed out Flat Black for the comparison. If the 260 luminance figure you provided is anywhere close to 795 lm @ 4.6A and 4.05V, then that's roughly 10x more intensity for the same power supplied.

    Size and weight for the product is 90mmx220mmx175mm and 3.9kg, not exactly EDC yet.

    At the present time laser phosphor modules are much more expensive compared to LEDs. If you want 1000 lumens (to get a somewhat large hotspot) you will need to pay at least 100-150$. You need the expensive diode, the phosphor Target and a special laser driver (more precisely regulated). You also need to think about safety if you are using separate components.
    So it is nearly breaking even with the old price of the collar, and it is certainly cheaper than having one made for you by a machine shop or a molding and coating manufacturer. At least now you can buy a module, which is something you can't do with the present Waiven patent owners.

    The Wavien collar is already "dead". The company is gone. Another company own the patent, but not selling it separately and not fully using its potential in the one light they offer.
    As long as the patent is still out there and has legal bite, the collar technology has value and the idea is still alive even though the manufacturing company is dead. I meant that the legal threat of the patent will become irrelevant when the technology loses its relevance in lieu of the laser module revolution. I would expect prices for laser modules to eventually come down just like anything else. I remember when it cost several thousands of dollars for a 40" 1080p LED TV. We waited for the technology to become cheap and bought ours for $500.
    Last edited by Genzod; 03-03-2018 at 06:13 PM.

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    Default Re: Phosphor conversion of photons in LEDs

    Quote Originally Posted by Genzod View Post
    The Wavien collar takes up a bit of space itself, and then you have to create more available length in the light cavity to meet a 60 degree beam that ordinarily would be 90-120 degrees. With the wavien collar in the way, the ability to zoom to flood is lost to a great degree. I haven't seen any laser modules as of yet, but I would imagine that the option of constructing the laser to come from under the phosphor would leave the space in front free of obstruction.
    Quote Originally Posted by Genzod View Post

    I'm glad to hear Osram is offering an LD module! Could you link me to a sales page for the one you mentioned? EDIT: Okay, called Phaser 3000 and Phaser 500. Got it.

    EDIT: With 3700 cd/mm^2 @40 watts, I get about 2730 cd/mm^2 @18.63w for a maxed out Flat Black for the comparison. If the 260 luminance figure you provided is anywhere close to 795 lm @ 4.6A and 4.05V, then that's roughly 10x more intensity for the same power supplied.

    Size and weight for the product is 90mmx220mmx175mm and 3.9kg, not exactly EDC yet.



    So it is nearly breaking even with the old price of the collar, and it is certainly cheaper than having one made for you by a machine shop or a molding and coating manufacturer. At least now you can buy a module, which is something you can't do with the present Waiven patent owners.



    As long as the patent is still out there and has legal bite, the collar technology has value and the idea is still alive even though the manufacturing company is dead. I meant that the legal threat of the patent will become irrelevant when the technology loses its relevance in lieu of the laser module revolution. I would expect prices for laser modules to eventually come down just like anything else. I remember when it cost several thousands of dollars for a 40" 1080p LED TV. We waited for the technology to become cheap and bought ours for $500.
    Yes, the collar is not really a very practical thing. It was also overly expensive considering what it does. They could have made it out of aluminium and offered it for a quarter of the price.

    The lasers are already cheap if you are ok with a using multiple diodes in a single light (a laser bank where all the beams are combined using optics). Only the very powerful multi-watt diodes from Osram and Nichia are actually expensive.

    The Osram Black Flat's luminance has been measured by multiple people and several record braking throwers have been built with it. The highest value ever measured (that I have seen) is 260cd/mm^2 at maximum output (4.5-5A). In the light linked in my sig we got up to around 240-250cd/mm^2.

    EDIT: your PM box is full!

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