# is it practical to de-focus a laser to make it a throwy flashlight?



## waddup (Sep 21, 2010)

do white lasers even exist?


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## black_ice_pc (Sep 21, 2010)

A "white" laser can be created by mixing red, green and blue together, like a TV. However, due to the power levels of current lasers, I really doubt there would be any practical point in making a laser-flashlight.


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## csshih (Sep 21, 2010)

black_ice_pc said:


> A "white" laser can be created by mixing red, green and blue together, like a TV. However, due to the power levels of current lasers, I really doubt there would be any practical point in making a laser-flashlight.



since lasers usually peak sharply at a particular wavelength, won't said white light have very poor CRI?


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## PCC (Sep 21, 2010)

I've tried shining a laser pointer through different lenses to see if I can scatter the beam but they don't seem to have much affect. Lasers are, basically, extremely tight throwers so why would you want to make them less throwy?


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## bshanahan14rulz (Sep 21, 2010)

One might need to cover a wider area. Sure, wouldn't be much of a laser, but it would still be more collimated than a flashlight....


cssih, laser diodes are generally only one wavelength. Gas lasers that output white are combining several spectral lines in the output to make white.

You can buy white laser kits on LPF. Thought I saw them on here too...
Kinda pricy, and not flashlight-shaped... but you could use that to make a white laser thrower. All you'd need is one more lens on the output.


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## fyrstormer (Sep 22, 2010)

Even de-collimated, the coherent light would be far more damaging to the eyes than regular light. Still a bad idea.


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## bshanahan14rulz (Sep 23, 2010)

Coherent light is "far more damaging"? Perhaps mathematically it is slightly more damaging, since you would be imaging more or less a point source if you used diodes, but as to coherent light being way more dangerous than non-coherent light? I don't understand the reasoning. Isn't coherence just the property of waves that have same frequency, amplitude, and direction? I mean, constructive interference would increase amplitude of some waves, but it would decrease it of others, it would kind of balance out, right?


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## jirik_cz (Sep 23, 2010)

there is already a manufacturer which sells defocused green lasers as hunting flashlights.


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## MikeAusC (Sep 24, 2010)

Torches using 5 watt LEDs are quite cheap.

Lasers putting out 50mW (one hundredth of the power) of the power are quite expensive.

Why would a Laser-based torch be better ?


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## Midnight Oil (Sep 24, 2010)

Check out the ND3 laser designator @ lasergenetics.com. Definitely not cheap.

Snap, someone beat me to it.


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## wyager (Sep 24, 2010)

Yes. Lasers are much more efficient than LEDs. I was thinking with the whole runtime craze of late, it would actually be very efficient to use an unfocused red 650nm (or even better, 635nm) diode. You get more watts output per watt input (A lot more) at the expense of CRI. However, since the only practical purpose I can think of is low power lighting, that wouldn't matter much. It wouldn't be all that expensive either.


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## andyw513 (Sep 28, 2010)

I dunno if practical would be the exact word for it, but fun comes to mind quickly. I placed a convex/concave lens (It's curved) over the tip of my Optotronics 532nm and it cast a blinding beam for a couple hundred feet. 

What I mean by blinding is that it wasn't exactly hurting my eyes until I tried to distinguish the shapes of trees and stumps I was illuminating. The light cast was simply too dense to distinguish anything in distinction. 

Given that 532nm is pretty intense anyway, it could mean that laser is meant to be a laser, or that the wavelength used was not the appropriate choice for what I was experimenting with. Perhaps the idea of "tri-coloring" a laser-torch might work, but only with varying output powers of each wavelength used? Any other thoughts to this?


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## bshanahan14rulz (Sep 28, 2010)

MikeAusC said:


> Torches using 5 watt LEDs are quite cheap.
> 
> Lasers putting out 50mW (one hundredth of the power) of the power are quite expensive.
> 
> Why would a Laser-based torch be better ?



Lasers "out-throw" LEDs.


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## Netscott (Sep 30, 2010)

Actually if laser diodes are not collimated or lightly collimated they typically put out quite a wide beam. 
They could make for effective flashlights in select wavelengths: 405 nm, 445 nm, 532 nm, 650 nm, 670 nm, etc.

-Scott


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## wyager (Sep 30, 2010)

Netscott said:


> Actually if laser diodes are not collimated or lightly collimated they typically put out quite a wide beam.
> They could make for effective flashlights in select wavelengths: 405 nm, 445 nm, 532 nm, 650 nm, 670 nm, etc.
> 
> -Scott



No such thing as a 532nm diode 
Pumped 532nm lasers will always be more focused that a diode.
It's also worth noting that 510-520nm diodes are currently in development. I imagine Nichia has passed the 1 Watt mark by now, they were at 50mW a while ago IIRC.


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