# White lasers



## Greco101 (Mar 13, 2011)

Why are they nearly impossible to make? Why can't a flashlight be focused like a laser? I've been on the market for an insanely tight, pocketable flashlight but can't seem to find one tight enough, or at least not have enough information on it to feel comfortable making an order. 
I work security at a nightclub and if I could pin point people with a light without blinding 100 other people around the spot/flood it'd make the job 10x easier. 
By tight I mean around the neighborhood of a 1' diameter at ~20-30' with very minimum flood. :shakehead


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## Isak Hawk (Mar 13, 2011)

I think a white laser would require many laser diodes and DPSS lasers in different colors. All the beams would then have to be collimated into one single beam. It can be done, but it's probably quite expensive and I doubt it would be pocketable...

Sounds like you need a flashlight with an aspheric lens of some kind. You could try asking in either the General or LED section, someone there might know of a light that would suit your needs.


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## Steve K (Mar 14, 2011)

Lasers can produce a very well focused beam because the light is all a single wavelength. IIRC, each wavelength of light will go through optics at a slightly different speed, causing them to focus at a different point. For that reason, white light, which contains all the visible wavelengths, cannot work in a laser that uses optics. You might be able to get acceptable results with a combination of separate red, green and blue lasers.

But... you'd have the same concerns about eye safety with a white laser that you have with a red laser. It's just a matter of the intensity of the light. Seems like you could get optics for a simple 5mw red laser to diverge the light a bit. i.e. spread the light out into a beam that has a larger cross section. Instead of producing a dot that's a couple of mm in diameter, it could produce a circle of light that's 30mm across. That would greatly reduce the intensity but still be visible without lighting up a couple of people. 

Seems like it would be possible to produce a flashlight with a white LED that can produce a very tight beam. Not as tight as a laser, but one that fits your description. It usually requires a somewhat large optic or reflector. The biggest obstacle is that there isn't much demand for a light like this, so it'll be hard to find a commercially built version.

If you want to tinker with this stuff, you can buy a wide variety of optics from places like Edmund Optics.


regards,

Steve K.


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## Greco101 (Mar 15, 2011)

Very interesting, I appreciate the informative responses guys.


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## CarpentryHero (Mar 29, 2011)

A flashlight with a good aspheric lens, may well do the trick. Ahorton sells surefire size lenses in the custom modified section. Itd be more like 4-5 inches at 30feet. Though with a larger light, you could focus more


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## bshanahan14rulz (Mar 29, 2011)

http://laserpointerforums.com/f64/fs-white-fusion-laser-mixing-kit-42013.html

Don't think they're sold anymore, but just to show that it was already done, produced in kit form too.


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## angelofwar (Mar 29, 2011)

The old Surefire KL3 bezels have pretty tight/focused beams with little to no spill. Also the Kroma.


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## Apollo Cree (Mar 30, 2011)

A "laser" is "coherent" light. Every photon is the same wavelength and in phase with all the other photons. This is necessarily a single color process. 

The way most laser devices work (LASER is "Light Amplification by Stimulated Emission of Radiation"), they tend to produce a small, tightly focused beam. Most white light sources emit light over a wide angle and you have to figure out how to focus the light from all these angles into a tight beam without losing too much light in the process. 

For a white "pseudo laser," you could try to combine multiple single color lasers to make a "pseudo white" light that looks like a white laser. That's what the laserpointerforums link above seems to be about. Very tricky, probably expensive. There would also be some problems with this in that the red, green, and blue parts of the beam would tend not to "stick together". Lasers tend to have "specular" light effects. When you shine it on something, instead of a smooth oval of light, it's little "speckles." A 3-color pseudo white laser would tend to have individual speckles of red, green, and blue. Also, it will be tough to get the red, blue, and green beams to stay together over a distance. 

You could also try and figure out how to focus a "normal" white light source into a narrow beam like a laser. For a number of reasons, this tends to be big, expensive, and inefficient. 

Now if someone was able to figure out how to make a light emitter that produced a beam like a laser, but with all frequencies of light instead of just one frequency, that would be really neat. I don't think it's likely, though.


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## Ragnarok (May 5, 2011)

White lasers are not only possible, they've been around and available for purchase for quite some time (that is, if you have some serious cash!), They are not as yet handheld items, but I don't see why the technology could not be used so. They are a type of _fiber_ laser known by the name _supercontinuum_ lasers, and here's how they work:

http://www.nktphotonics.com/side5412-cid-7858.html
http://www.sumita-opt.co.jp/en/news.htm (look further down the page)

Note that each wavelength will have its own individual power and divergence, so that at long ranges the spot will no longer be white, but a radial distribution of colors.

http://laserpointerforums.com/f40/white-diode-pumped-fiber-laser-25590.html

You might try placing an _aperture_ out front of your light to cut the scatter/spread.

fyi, R.


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## Got Lumens? (May 6, 2011)

Yup, Worked for Beltel for 15 years, they do exist.
Interesting tidbit. The newest fiberoptic multiplexers now use 16 different spectrums of fiber lasers running over a single fiber. They can now send data that is 32x times more than the most power single spectrum fiber carrier multiplexors. Huge amounts of data, like 32 OC192's on one fiber! The equivelent of 5376 T1s or 247726.08 MPS!



Ragnarok said:


> White lasers are not only possible, they've been around and available for purchase for quite some time (that is, if you have some serious cash!), They are not as yet handheld items, but I don't see why the technology could not be used so. They are a type of _fiber_ laser known by the name _supercontinuum_ lasers, and here's how they work:
> 
> http://www.nktphotonics.com/side5412-cid-7858.html
> http://www.sumita-opt.co.jp/en/news.htm (look further down the page)
> ...


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## Bigmac_79 (Jul 28, 2011)

I've got an Inova X1 (LED, not laser) that is super tight b/c it has an aspheric lens. I haven't measured it, but I bet it wouldn't be much more than 1' diameter at 30 feet. Mine's green, but I bet I'm pretty sure they come in white. For shining at a person's head, I would rather use an LED with an aspheric lens than a laser

EDIT: My X1 has no flood, it's just an even circle.


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## susanawalkly (Jul 31, 2011)

It is the first I heard of white lasers. I only know those of common available red, green, blue lasers. I am very interested in your imagination. 
Is it in same light color of a common used flashlight?


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## bshanahan14rulz (Aug 1, 2011)

I believe there are eximer lasers and plasma lasers that can generate "white" light. They aren't full spectrum, but it's enough to make white. They're kinda complicated, though, and I don't think you'll get one in a handheld.


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## 1215 (Aug 2, 2011)

Pretty much tell you now that unless you are totally dedicated this won't happen. You'd need a housing big enough for at least 2 diodes, blue/yellow which will give you a white. Probably cheaper to go blue/green/red though as yellow is prohibitively expensive for anything but pro/lab use. Then use dichoric mirrors to combine into a white beam. And get proper laser goggles with the right OD factor to save your eyes while you try align it. Lasers are like playing with fire if you don't have appropriate techniques and protection!!!


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## Tsportmat (Aug 3, 2011)

bshanahan14rulz said:


> I believe there are eximer lasers and plasma lasers that can generate "white" light. They aren't full spectrum, but it's enough to make white. They're kinda complicated, though, and I don't think you'll get one in a handheld.


 
I don't know very much about plasma lasers, but I don't think you'll get a white excimer laser; generally they're UV, so invisible, unless they fluoresce a material (like paper).

As has been said, a laser must have just one wavelength, so unless you mix about 3 different lasers together, you won't get white.


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## carrot (Aug 3, 2011)

CarpentryHero said:


> A flashlight with a good aspheric lens, may well do the trick. Ahorton sells surefire size lenses in the custom modified section. Itd be more like 4-5 inches at 30feet. Though with a larger light, you could focus more


 
This will probably solve your needs. A good example of an aspheric flashlight is the DEFT, made by one of our own here.


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