Focusing Multi-diode Laser systems?

[gottaluvlasers]

Hey PLers-

I am definitely not an optics expert, so i ask you brilliant geniuses this-

I have a customer who is looking at a KVANT module for a non-light show use. They need the beam to be focused down to a 20 um point size. They are interested in the 660 wavelength, but seem to be open to also 532nm (in my head, it may be easier to focus 532 as it is a polarized beam and much better quality from source). It needs to be in the ~1.5W range. Is this possible? Are the multiple diode laser modules capable of this type of focusing?

thanks for any help or advice.

-Marc

[absolom7691]

I am certainly no expert, but I would think DPSS is a no brainer. Great beam characteristics. As far as mulli-diode setup.... I would think Planters would know this one.

[dsli_jon]

Yo Dukie..

They need the beam to be focused down to a 20 um point size. They are interested in the 660..

No-need to push them to dpss - easy to achieve a very-nice round beam (to focus-down cleanly..) with a 'FAC' (fast-axis corrector..) lens.. There are several-providers out there of such 'plug-n-play' modules.. For that power-level, there are off the shelf fiber-coupled modules, that can then, be focused-down...

..But, I'd say, before making any hard-recommendations, a) you need to find out more about their 'application' / goals - is this telecom / data? are they trying to cram this into fiber, at-all or, some kind of 'writer' / scriber? And, Modulated or CW? etc, etc, b) Talk to 'P'fessor Roberts' - he's already got a bunch of data on various diodes 'best-case scenario' with getting µm spot-sizes.. he's just about 'all the encyclopedia you'll ever-need'..

Dang, used a smiley..
j

[mixedgas]

You can get a 1 watt 660 diode launched into a fiber from several vendors. The fiber is actually "welded" to the metal diode case with a ceramic bond or a compression weld. This is possibly far easier then trying to "correct" a Kvant module. Price will be in the 500-900$ range per diode, depending on the vendor, although I've been offered "extra stock" for as low as 350$ once.

20 uM with a green just requires a good microscope objective as the focal element. These are in the 200$ range.

I'm hard to get ahold of these days, my new job requires the "impossible" to happen in the lab. We all know of the saying that "The impossible just takes a little longer" so give me a day or two to find the diode data. So I'm doing 10-12 hour days plus a 45 minute commute each way. . This means I'm sluggish and slow.

Steve

[mixedgas]

PM sent....

Steve

[planters]

I agree with Jon. There are a lot of ways toward this end and the costs will vary significantly. More application info will make this much easier. Is he looking at Kavant because he comes from a light show background?
That's a large wavelength range and a pretty small spot, but is it the energy density at aprox. 500KW/cm2 or a clean 20um spot that's required?
The depth of focus is important. Even a pretty shitty diode can achieve a small spot with an extremely short FL lens like a microscope objective, but the depth of focus will be very short.
I agree a fiber coupled diode would work, but the fiber generally does not improve the M2 quality of the diode without a corresponding power loss. So I think a well corrected diode with a short focus lens might be cheaper if a little less convenient.

[andythemechanic]

No Problem to fokus many diode lasers to the same spot. Just have them pointed to the same direction before the focussing lens, that all what is needed. In the focal plane of the focussing lens all beams that point to the same direction before will join into one nice spot.
To achieve a tight focus you usually will need some kind of camera system to look at the focal spot and do the alignment.

Andreas

[Stoney3K]

I agree with Jon. There are a lot of ways toward this end and the costs will vary significantly. More application info will make this much easier. Is he looking at Kavant because he comes from a light show background?
That's a large wavelength range and a pretty small spot, but is it the energy density at aprox. 500KW/cm2 or a clean 20um spot that's required?
The depth of focus is important. Even a pretty shitty diode can achieve a small spot with an extremely short FL lens like a microscope objective, but the depth of focus will be very short.

Adding to that: The depth of focus is quite important if you want to use this unit as a laser cutter. Obviously, less focal depth means less penetration through your material, and, therefore, less thick material that you would be able to cut.

[andyf97]

I am not sure that is so easy, is he ever going to get a beam < 20um from a source that has a larger emitter than 20um.