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White Laser (NOT RGB)

H2Oxide

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There is nothing that makes the light that comes out of the headlights "laser light" unless part of the magenta laser (whatever that means) passes through the phosphor. As styropyro pointed out, fluorescence is the mechanism at work here. While lots of lasers operate on this mechanism, the fluorescence from the phosphor is spontaneous rather than stimulated.
 



Philosopher

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There was a thread in the forum some time back regarding automobile headlights which used a blue laser to blast a phosphor disk to make a blue tinted white light, I forget which vehicle it was used with, but it was a luxury car. There was some debate whether 405nm or 450nm was used, but I bought a yellow appearing phosphor disk on ebay and illuminated it with 450nm to find the white light it emitted was far brighter when using 450nm.

WOW. I think I am starting to get the full picture here..... and I think it has to do with light absorbance of the phosphor, which is why he used magenta - an opposite of green, and by darkening the phosphor to magenta - he made the phosphor become green light absorbent... he is saying that he is using Green laser, because it is the brightest and very cheap, humans are most sensitive to green, but if its the brightest from the scientific point of view - no idea, would need some sort of lumen measuring devise and test blue red and green of same wattage, for lumens, because if he is right, green and magenta could be the win over blue laser range :can:
 
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diachi

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WOW. I think I am starting to get the full picture here..... and I think it has to do with light absorbance of the phosphor, which is why he used magenta - an opposite of green, and by darkening the phosphor to magenta - he made the phosphor become green light absorbent... he is saying that he is using Green laser, because it is the brightest and very cheap, humans are most sensitive to green, but if its the brightest from the scientific point of view - no idea, would need some sort of lumen measuring devise and test blue red and green of same wattage, for lumens, because if he is right, green and magenta could be the win over blue laser range :can:


Green is brighter to the human eye than blue or red, but watt for watt blue is significantly cheaper.
 

steve001

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There was a thread in the forum some time back regarding automobile headlights which used a blue laser to blast a phosphor disk to make a blue tinted white light, I forget which vehicle it was used with, but it was a luxury car. There was some debate whether 405nm or 450nm was used, but I bought a yellow appearing phosphor disk on ebay and illuminated it with 450nm to find the white light it emitted was far brighter when using 450nm.
If I'm following what's said, 405nm light works too. I shown my 405nm laser onto the led phosphore facet and it created a bright white light. The led is the type used in flashlights.
 

Benm

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Bet on it being a 405-ish laser diode pumping some fluorescent material, the 'laser headlight' thing is mostly marketing.

You don't even -want- to have proper laser light for the application. Surely you could mix green with magenta, blue with orange, or RGB to get sort-of white light as a mix, but that would have significant downsides. For one, the color rendering would be horrible and in case of a blue-orange mix things like plants would hardly be visible.

Also, if it was coherent light you'd get speckle, which would be quite dizzying to look into while driving for a long time.
 

Radim

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diachi

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Afaik laser headlights are being developed by BMW and Audi. Also some cinema projectors use laser hitting rotating phosphore disk instead of bulb. Anyway as the light generated is not coherent it cannot be considered as laser light. It is interesting that even some white leds use UV light with phosphore to get white light.

Audi & BMW: https://www.osram.com/osram_com/new...aser-light-new-headlight-technology/index.jsp


Not just cinema projectors, home projectors use that method now - at least some of them anyway. That's where our blue diodes come from...

Unless the LED is RGB (i.e. individual emitters for each colour), it uses a phosphor with a blue emitter to make white.
 

Encap

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except there is no magenta phosphor----is just a mix of red and blue phosphors that emit red and blue lines that looks "pink" --the guy also talks about "green laser diodes" DPSS 532nm laser diodes from Thor Labs and as we know there are no 532nm laser diodes. The guy is mixing apples and oranges all over the place in the patent and clearly has no idea of what he is talking about. "white laser" the guy even says. What does the brightness of green to the human eye have to do with making a white headlight----green to the eye is green not anything else--what does he mean a mostly greenish white from a "magenta" phosphor that doesn't exist and emits a mix of red and blue lines??
To me the patent looks like mostly a pantload of you know what. Color is not a physical property; it is merely the brain’s interpretation of different wavelengths of light.

from the patent "According to one embodiment of the present invention, FIG. 3A shows one configuration of using green laser and magenta phosphor to produce diffused white light beams. The green laser beams 302 are produced by one or more laser diodes or green laser sources 304. In one embodiment, an array of green laser diodes 532 nm DPSS Laser Diodes from Thorlabs, Inc. located at 56 Sparta Ave, Newton, N.J. 07860, are used. The green laser beams 302 are coupled to a filter or a coating 306 made of phosphor in magenta. Magenta is a purplish red color and one of the three primary colors of the subtractive CMYK color model. As shown in FIG. 1, magenta is located midway between red and blue. Depending on implementation, there are some ways to obtain magenta phosphor. In one embodiment, the magenta phosphor is produced by mixing blue phosphor with reddish orange or red phosphor. By mixing the blue phosphor and the red phosphor in a predefined ratio (e.g., 20:80 or 50:50), the resulting phosphor emits a pink color in a CIE chromaticity diagram. The wavelength spectrum of the resulting phosphor actually shows two peaks of a blue and a red wavelength, but a user cannot differentiate the separate colors but rather sees only the mixed pink color." See the entire patent here: United States Patent: 9328887

Maybe the guy is just trying to Patent "me too" laser driven headlight system, that nobody wants because it is not economically viable, powered by 532nm green laser light instead of blue as BMW uses. You are not going to get much of a headlight out of a Thor Lab 10 or 40mW 532 dpss "diode". Tthe cost $175 each for the 40mW model not to mention the need for temperature controlled laser diode mounts as they only operate efficiently between 20 and 25 degrees C--see: https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=5597 Just what every auto maker needs headlight system with a duty cycle of maybe a few minutes that costs thousands dollars per headlight and is temperature sensitive and unstable.

BMW's headlight technology is powered by lasers, but the important thing to note is that when you look into them, you're not looking at an actual laser. What happens with each light is that three blue lasers positioned at the rear of the assembly fire onto a set of mirrors closer to the front. Those mirrors focus the laser energy into a lens filled with yellow phosphors. The yellow phosphors, when excited by the blue laser, emits an intense white light. That white light shines backward, onto a reflector. The reflector then bounces the more diffused white light forward, shining it out of the front of the headlight casing as a beam
 
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lazeristasUVISIR

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[subscribe]

Again this patent confirms that the truth should be not searched in patents.

As an idea for a white light source - yes, as a mixture of RGB.
 
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zenon

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Any affordable RGB laser pointers ?? 300-500 range ??
 

Snecho

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Any affordable RGB laser pointers ?? 300-500 range ??
This thread is 4 years old. Please do not ignorantly post your personal questions wherever you see fit.

Make your own thread.
 

18LJ

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While i will agree that shining a light thru a phosphor should disrupt the lightwave coherence, i have seen i think on surplus shed and also on ebay lenses and just plain yellow crystals that were advertised specifically as being used to change the color of a laser from red to green or vice versa. They were a bit too expensive to buy on a whim just to see if they really work but the concept is floating around out there. If i run across any examples ill try to remember to post here
 




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