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About getting a gaussian beam...

ElektroFreak said:
^if that does a good enough job for your tastes, go for it.. The fiber gives exceedingly clean output, that and the other benefits are why I suggested it. All you would need to set things up is an adjustable driver for the diode, your aixiz module w/ lens, a jeweler's loupe, some epoxy and some creativity. The mechanics of getting truly clean output from a spatial filter aren't just as simple as a pinhole. The hole must be a specific size, and it is usually all but invisible. Working with fiber is working on a larger scale than a true spatial filter.
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Yeah I know. Higher spatial frequencies and unwanted noise tend to be farther radially on the transform plane and 86% of the power distribution of a gaussian geam is within 1/e of the beam radius or something like that.
 





I would build a small adjustable platform for the fiber so that it can be raised or lowered by a screw or screws, and similar for the aixiz module, only with horizontal adjustments instead of vertical. You epoxy the fiber to the platform and adjust either the fiber or diode adjustments until they're lined up. Perfection is not necessary for most hobbyist needs. Regardless of whether you use fiber or a spatial filter, a pointer will be nearly impossible. You'd basically be building a full-fledged laser head.
 
ElektroFreak said:
I would build a small adjustable platform for the fiber so that it can be raised or lowered by a screw or screws, and similar for the aixiz module, only with horizontal adjustments instead of vertical. You epoxy the fiber to the platform and adjust either the fiber or diode adjustments until they're lined up. Perfection is not necessary for most hobbyist needs. Regardless of whether you use fiber or a spatial filter, a pointer will be nearly impossible. You'd basically be building a full-fledged laser head.
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Yeah sorry I neglected to mention this is for a lab style laser not a pointer.
 
And here we are. The fruits of my masking tape, cardboard box, and aluminum foil spatial filter/collimater etc roflmao.

DSC_6392.jpg


And the spot (not collimated, not focused)
DSC_6395.jpg
It's elliptical because the beam doesn't pass through the centre of the lens, plus the beam isn't exactly perpendicular to the flat surface of the lens. Aside from that, it's relatively free from other artifacts, although at the focus point you can still faintly tell that you're focussing a portion of the semiconductor producing the laser (that is in fact what the 'side splash' comes from). Oh yeah using acrylic aixiz lens.
 
Limecat said:
Does anyone here actually have a spatial filter set up that provides them with a more or less clean gaussian beam? Seeing 'noisy' beams really irks me lol. I'd really like to have a set up that produces relatively clean gaussian beams so that it'd stay a circle even at distance.

Any tips?
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This company will have everything you need to accomplish this. From Ball lenses to Precision Pinholes and X Y mounts.
http://www.edmundoptics.com/

If you don't have this site bookmarked you should.
Sam's Laser FAQ - Preface, Introduction, What is a Laser?, Safety
 
steve001 said:
This company will have everything you need to accomplish this. From Ball lenses to Precision Pinholes and X Y mounts.
Optics, Imaging, and Photonics Technology - Edmund Optics

If you don't have this site bookmarked you should.
Sam's Laser FAQ - Preface, Introduction, What is a Laser?, Safety
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Yeah I have that site bookmarked. There is that option if I wanna go the professional and more expensive route... but I don't want to cross that bridge just yet hah. Thanks for the heads up though.
 
Are the spherical (ball) lenses made for fiber coupling?
I have a multimode 808 module which I would like to clean up.
Also, I once read that careful heating of the end of a fiber would make a ball effect.

HMike
 
I've never tried anything like this, but could it be possible to actually let the laser burn the pinhole itself (through some suitable material) after everything has been mounted?

That would eliminate the need for precision adjustments in position, and only leave the requirement for a mechanically stable mount.
 
Benm said:
I've never tried anything like this, but could it be possible to actually let the laser burn the pinhole itself (through some suitable material) after everything has been mounted?

That would eliminate the need for precision adjustments in position, and only leave the requirement for a mechanically stable mount.
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That'd work, if it was thin black plastic or a black sheet of paper. Good idea :)
But only works if the laser can be set to a setting strong enough to burn/melt. It wouldnt work for a low power laser though.
 
It's impossible to heep the heating as localized as it really should be. A true spatial filter will have a pinhole that is just a few microns or so across. Burning the pinhole with the laser will inevitably give a larger hole than necessary even at the focal point of the beam since a small amount of heat will spread to an area larger than the beam diamter through heat conduction in the material being burned. While you can get a slightly cleaner beam with a hand-made pinhole, it will be nowhere near the beam quality that a real spatial filter can provide.
 
That makes sense... even without the conducting and melting too much material away, the spill light would probably misshape the pinhole.

Still, i wonder if it could have any practical application in improving beam quality - not to perfection, but it might just shave some artifacts from the beam for very little investment.
 
Benm said:
That makes sense... even without the conducting and melting too much material away, the spill light would probably misshape the pinhole.

Still, i wonder if it could have any practical application in improving beam quality - not to perfection, but it might just shave some artifacts from the beam for very little investment.
Click to expand...

Doing things like slit experiments and fourier optics benefit from having the output be more or less clean i think. For burning, it won't matter since you just care about how well it burns :P
 
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