DTR's Laser Shop: Diodes-Drivers-Lenses-LEDs & More

[logsquared]

Solarfire described a complicated custom collimnator he built some time ago using two orthogonal cylinder lenses to fine tune the divergence of a 445 diode. This was a first stage collimnator used instead of the typical single small lens such as the O-like. If your looking for awesome with these large asymmetric emitters your best bet will be to deal with each axis independently and as close to the source as possible.

This is the way to go for sure. Only drawbacks are, hard to machine mounts, and finding a cylindrical lens with a high NA and short focal length for the fast axis.

[steve-o]

I like the whole black-hole thing Dnar. If we can capture anti-matter and put it in a magnetic field of, say, 10 ^12 Guass, I think we could sustain a photon-electron bond of 10^-12 ms which should be sufficient to capture a semi- permeation of the chromea bond of light-to-matter permeability theroem which should in theory sustain at least 12 ms of coherent negative light anti-photons. Whattcha' think?

-edit - oops dnar didn't see your post . soory to interrupt the flow ... .

[dnar]

I like the whole black-hole thing Dnar. If we can capture anti-matter and put it in a magnetic field of, say, 10 ^12 Guass, I think we could sustain a photon-electron bond of 10^-12 ms which should be sufficient to capture a semi- permeation of the chromea bond of light-to-matter permeability theroem which should in theory sustain at least 12 ms of coherent negative light anti-photons. Whattcha' think?

That's basically what I am thinking. All we need to work out is how to mount the "hole" thing on a 2x2" peltier.

[CDBEAM]

Mr. Planters.....is this the concept you had in mind ???? Although the use of Lava's Cylinderical Lenses is an interesting thought ??

I realize that most ideas will be shot down.....and that is almost to be expected.....and really to be welcomed...for if the idea has actually been tried....and found NOT to work....shoot away....and save all from going down a blind alley !!! wasting time and money....BUT....it is possible.....even if unlikely... that
the synergy of ALL contributions may lead to a solution. I am sure that many, many minds.....optically trained engineers... have worked on this problem. BUT...many here have a passion unmatched elsewhere !!....hence the term..." Photonintoxicated"...or Photoxicated ( ?? )

CDBEAM

[absolom7691]

I can get my hands on some 3mm fiber. Is it not possible to focus the beam down and at the focal point, inject the light into the fiber, at the other end, collimate the output from the fiber? Please correct me if I am wrong, but would this not give you a near TEM00 beam??

Posted this again over in CDBEAM's Mitsu 638 thread http://www.photonlexicon.com/forums/...044#post208044

[planters]

No. Without significant loss the fiber does not improve the beam. It can't alter the mode of a beam already generated. Even though what happens in a fiber is too small to see there is no magic occurring within the fiber. To help visualize this draw this out at a highly enlarged scale and trace a few rays from a diverging diode through a positive lens and into a fiber. The zig-zag rays will reflect due to total internal reflection as they pass through the fiber and as they exit a second collimnating lens will return the beam back to it's original diverging profile. The small entrance aperture of a fiber is used to act as a spatial filter to remove splash and non-uniformity.
The most direct and proven methods for improving divergence will increase the near field beam size and because this is almost always a lot smaller than the far field, more effort should be spent on enlarging the effective aperture of the scanning system while maintaining it's performance ie bigger and better amps,motors and mirrors. Go B. Benner

[-bart-]

Well, if there would be a tapered fibre that would be 1µx100µ on one side, and a diameter of 12µ on the other...
And if there would be an elegant yet efficient way to couple the 1µx100µ end onto the laser facet...
I 'm sure something useful would come out of the 12µ end.

[planters]

Sorry no. A tapered fiber no matter how gradual will cause each internal reflection to accumulate 2x the taper angle. This happens EACH time the ray strikes the side of the fiber. Only those few rays that are traveling nearly parallel to the fiber axis AFTER launch through the positive lens will pass out of the other end of the fiber. The rest will accumulate sufficient additional angle of incidence with the fiber walls that they will exceed the maximum AOI for total internal reflectance and will be lost to the cladding. The loss will not be 100%, but so nearly so that this will not work.

[Bradfo69]

hence the term..." Photonintoxicated"...or Photoxicated ( ?? )
CDBEAM

Love this. "Photoxicated" get's my vote.

[dnar]

Sorry no. A tapered fiber no matter how gradual will cause each internal reflection to accumulate 2x the taper angle. This happens EACH time the ray strikes the side of the fiber. Only those few rays that are traveling nearly parallel to the fiber axis AFTER launch through the positive lens will pass out of the other end of the fiber. The rest will accumulate sufficient additional angle of incidence with the fiber walls that they will exceed the maximum AOI for total internal reflectance and will be lost to the cladding. The loss will not be 100%, but so nearly so that this will not work.

So this would be much like what occurs inside the laser cavity, only the spatially coherent beams exit the cavity?