Diode help?

[ElektroFreak]

^Never a problem.

Chris is the guy who sold you those diodes..
I would ask him if he has any lenses that could help you collimate those diodes into something usable for shows. Multimode diodes can be pretty hairy when it comes to getting the right combination of optics. Ideally you'll need a beam that is no bigger than 6mm wide at the aperture, with a divergence of less than 2.0 mrad.

As I have never personally put together a multimode diode based laser (other than experimental DPSS stuff) I can't give you the math for this. I would highly recommend getting a set of optics from surplusshed.com or edmund scientific. If you were to find and purchase at least one set (various lenses compiled together into an experimenters set), you really shouldn't have too much trouble experimenting with configurations until you get one that works. Since you're working with visible light, it's even easier. You'll immediately be able to see the results of your work.

Edmund has a host of sets available, you just need some that contain convex and cylinder lenses. You might have to get two kits, but trust me you can never have too many lenses. The optics won't be coated which means there will be slight losses through each optic, so you'll want to use the combination that uses the least number of optical components.

Start by flipping through here and see what you find..

Here's your basic layout: diode => cylinder lens => convex lens


Here's what cylinder lenses look like (in case you don't already know):

[andy_con]

LOL oh right i see

cheers

[heruursciences]

I hope that setup was a VERY brief TEST of the unit, as the diode needs to have the whole case edge intimately contacted to a heat sink or it will die in short order,high power reds like this do not forgive you for overheating them for very long.


Here is how you can collimate this thing, or any other MM emitter-Yes even BARS TOO! Use one of 4 ways,

#1 Happy medium: The easiest by far is using a short fl aspheric lens such as the one from an axiz glass collimator plus a cylinder lens, focus the beam to the most well defined LINE output in distance, then use a short FL cylinder lens to finish the job, the result is a square dot with moderate diameter and very low divergence.

#2 BEST COLLIMATION: Expand the slow azis to match the fast axis and collimate with a moderately long ~2-5 inch 1/2 inch diameter aspheric lens, result is a VERY nicely collimated beam in near and far fields, but large beam diameter.

#3 Smallest beam dot: Use a ready made collimator assembly with a negative cylinder lens and SHORT FL aspheric lens, this gives the smallest beam diameter possible, but the largest divergence far field.

#4 Smallest FOOTPRINT- USE A FAC: Use some fiber optic material to correct the beam and make the output as square as possible, then correct with a short FL aspheric lens, beam result is similar to #1, but about half or less the length is possible!

Note; mounting a FAC is tricky, but can be done with dental resist, a hand held violet laser curing wand, cactus needles to apply the resist, a 3 axis mount with a disposable plate, Razor blades or the metal strips out of anti-theft tags work great since a small magnet can hold them to the fibers, and a dissecting microscope- assuming you have a way to power/view the laser at low duty cycles and a LOT of patience.

Hope this helps!

[andy_con]

I hope that setup was a VERY brief TEST of the unit, as the diode needs to have the whole case edge intimately contacted to a heat sink or it will die in short order,high power reds like this do not forgive you for overheating them for very long.


Here is how you can collimate this thing, or any other MM emitter-Yes even BARS TOO! Use one of 4 ways,

#1 Happy medium: The easiest by far is using a short fl aspheric lens such as the one from an axiz glass collimator plus a cylinder lens, focus the beam to the most well defined LINE output in distance, then use a short FL cylinder lens to finish the job, the result is a square dot with moderate diameter and very low divergence.

#2 BEST COLLIMATION: Expand the slow azis to match the fast axis and collimate with a moderately long ~2-5 inch 1/2 inch diameter aspheric lens, result is a VERY nicely collimated beam in near and far fields, but large beam diameter.

#3 Smallest beam dot: Use a ready made collimator assembly with a negative cylinder lens and SHORT FL aspheric lens, this gives the smallest beam diameter possible, but the largest divergence far field.

#4 Smallest FOOTPRINT- USE A FAC: Use some fiber optic material to correct the beam and make the output as square as possible, then correct with a short FL aspheric lens, beam result is similar to #1, but about half or less the length is possible!

Note; mounting a FAC is tricky, but can be done with dental resist, a hand held violet laser curing wand, cactus needles to apply the resist, a 3 axis mount with a disposable plate, Razor blades or the metal strips out of anti-theft tags work great since a small magnet can hold them to the fibers, and a dissecting microscope- assuming you have a way to power/view the laser at low duty cycles and a LOT of patience.

Hope this helps!

ok so if i wanted to go with the best option do you have any parts to do this?

[ElektroFreak]

I'd try for option No. 1 myself.. With the right lenses you should easily be able to get a small enough beam diameter that you don't lose half you power off the sides of the galvo mirrors..

[andy_con]

gee i had tough decisions!!!

[ElektroFreak]

A lot of people get spoiled working with singlemode diodes, but you can't get anywhere near this kind of power from singlemode.. It all seems complicated, and it is to a degree, but once you have that laser that you built sitting in front of you it's all worth it..

Also, I would go ahead and get a module like the ones smogthemog offered you. You can set one of those directly on that TEC and keep that diode nice and chilly.. Since you have two, you may as well just pick that whole assembly up. You can always use the blocks without the lenses.

[andy_con]

i have other plans regarding diode mounts and tec dont worry.

just need to get the correct lens.

i have e-mailed chris so am waiting for his reply

[ElektroFreak]

Good stuff.. hope it goes smoothly!

Post pics as you go..

[smogthemog]

I know Andy but the lenses should be available from Meredith and they should fit directly into these mounts.

There here if you want them anyway