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Largest Wattage in Handheld Portable Laser?

Arshus

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Lol. Don't put down my primitive amusement forms! I love 'burning crap', I could have been one of those pyro guys on film sets. Like that guy on Tropic Thunder.
 

qumefox

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To each their own. heh. It just holds little amusement for me. I'm happier with a fog machine and a bunch of front surface mirrors.
 

ped

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You could combine two with a PBS in a large flashlight host.. I don't see anyone doing more than that though, since it would involve a LOT more complexity.
Yeah for sure, but it is do'able.

:takeit:
 

DrSid

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You two both need to do a bit more reading about how monochromatic light interacts with itself. Neither method is valid due to destructive interference. Also, dichro's only work to combine DIFFERENT wavelengths.

There are really only two ways to combine the same wavelength together, and one of them isn't really combining them..

The first method is to use a polarized beam splitter to combine two 90 degree polarization offset beams into a single one.. This can only be done with two beams.. and once. If the resulting beam is run through another PBS, it will get split back into the two different beams again.

The second method is knife edging, which isn't really combining beams at all. It's just arranging the beams so they're parallel and aligned really close to each other without overlapping. If they overlap then you deal with power loss due to destructive interference.

The two methods can be combined though, You can have two knife edged banks, with one polarized at 90 degrees to the other, then run the output of each bank through a PBS.. but this arrangement with neither be remotely small in any way, or be robust enough to be swung or banged around and have any hope of all the optics and mirrors staying in alignment.

We'll probably see two diodes combined with a PBS in a handheld in the near future.. but I think anything beyond that is very unlikely.
We discussed this in the thread where some guy used whole 24 diode array from the original projector focused into one point. Since the diodes are each at bit different wavelength, which is not very stable anyway, the power combines real nice.
In other words .. those diodes are coherent by them selves, but not against each other.
Also if you focus the beams from different directions, even if you had co-coherent sources, you would only get small areas with cancellation .. and some other small dots with double power, in avg it will go to simple sum of powers again.
 
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DrSid

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You two both need to do a bit more reading about how monochromatic light interacts with itself. Neither method is valid due to destructive interference. Also, dichro's only work to combine DIFFERENT wavelengths.

There are really only two ways to combine the same wavelength together, and one of them isn't really combining them..

The first method is to use a polarized beam splitter to combine two 90 degree polarization offset beams into a single one.. This can only be done with two beams.. and once. If the resulting beam is run through another PBS, it will get split back into the two different beams again.

The second method is knife edging, which isn't really combining beams at all. It's just arranging the beams so they're parallel and aligned really close to each other without overlapping. If they overlap then you deal with power loss due to destructive interference.

The two methods can be combined though, You can have two knife edged banks, with one polarized at 90 degrees to the other, then run the output of each bank through a PBS.. but this arrangement with neither be remotely small in any way, or be robust enough to be swung or banged around and have any hope of all the optics and mirrors staying in alignment.

We'll probably see two diodes combined with a PBS in a handheld in the near future.. but I think anything beyond that is very unlikely.
We discussed this in the thread where some guy used whole 24 diode array from the original projector focused into one point. Since the diodes are each at bit different wavelength, which is not very stable anyway, the power combines real nice.
In other words .. those diodes are coherent by them selves, but not against each other.
IMHO in these systems cubes and knives are used to make one collimated beam (thick one in case of knives). Which is impossible otherwise.
Or do you have any example where destructive interference did occur with diode lasers ? I haven't found one.
 

qumefox

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We discussed this in the thread where some guy used whole 24 diode array from the original projector focused into one point. Since the diodes are each at bit different wavelength, which is not very stable anyway, the power combines real nice.
In other words .. those diodes are coherent by them selves, but not against each other.
IMHO in these systems cubes and knives are used to make one collimated beam (thick one in case of knives). Which is impossible otherwise.
Or do you have any example where destructive interference did occur with diode lasers ? I haven't found one.
And was the output of this actually measured on an LPM? I doubt it was or else it would have probably been quite evident that the focused output wasn't anywhere close the power of each individual diode combined. Assuming each of the 24 diodes was putting out 1W.. it wouldn't surprise me if losses weren't 50% or more.. Now you tell me. How are you going to tell the difference between 12W and 24W just by burning stuff with no other reference?

The reason you've never seen proof of it either way here, is mostly because the people who can afford the tools to prove this to people here, have very little interest in 'burning'. And I say 'here' because elsewhere like PL where most people have an educational background involving optics and light interactions.. it doesn't have to be proven because it's already a known fact.
 

DrSid

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I just don't see how it would be physically possible .. do you have any reference ? If the diodes were same wavelength, same phase, same direction, same position in space .. yep, then you have problem. But none of this is relevant in this case.
It's true however the output was not measured (AFAIK). Also few people have such LPM ..

I found the thread, the discussion stars at this my post. There is not much info in it as I see it now though:

http://laserpointerforums.com/f65/i-have-done-i-have-power-52490-3.html#post770868
 
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qumefox

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I just tried this with two 405nm pens. They measured 54mW and 64mW individually. When both were pointed at the same spot on the LPM, the highest reading I could get was 86mW, which comes out as a 27% loss considering they should total 118mW combined.
 

Leodahsan

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I just tried this with two 405nm pens. They measured 54mW and 64mW individually. When both were pointed at the same spot on the LPM, the highest reading I could get was 86mW, which comes out as a 27% loss considering they should total 118mW combined.
(ugly drawing detected)

Maybe the photons collided with each other, because the light sources weren't parallel, like
||

but they were like
.\. / (ignore the dots)
. \/ << collision :p
 

qumefox

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(ugly drawing detected)

Maybe the photons collided with each other, because the light sources weren't parallel, like
||

but they were like
.\. / (ignore the dots)
. \/ << collision :p
Well that's what i'm talking about and the point i'm trying to get across. Just pointing a bunch of same wavelength lasers at the same spot doesn't result in a power level that is the sum of the power of all the lasers. You lose power due to destructive interference.
 

DrSid

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Can someone try it with more lasers (3,4) ? I wonder what the numbers would be.
Still the info I found on the interned is quite clear .. such sources should not interfere. It is the photon interfering with itself what causes the interference patterns. And even if you send photons one by one the interference pattern will statistically occur (which is one of the parts of slit experiment). Putting two lasers together just should mean more individual photons.
 

qumefox

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You can't combine same wavelengths with a dichro... They don't work that way. dichros will either pass or reflect a wavelength depending on the coatings. They can't do both. The closest transition gap i've seen on a dichro is about 15nm, which is a dichro for combining 635nm with 650nm.
 
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qumefox

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Still. For the purposes of this forum.. it's still not really possible to combine two 445's, or any other similar wavelength diodes with a dichro..
 




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