need advice about pump shaping versus FAC lens

[shrad]

hi all

I'm currently working on crystalaser 10~25mW model

these have a pump shaping set of optics comprising the standard two-wedges and two-lenses

is this a flaw in the design, I don't know, but it seems they have approx. 20% of the pump beam hitting the mount up and down of the first lens of the set (pump beam is therefore cropped to approx. 60~70%)

is this a common issue?

would a FAC corrected diode interfere with the beam shaping optics? (I bet so)

if you could discuss this, that would be nice... have you any idea of what could resolve this? I have a piece of optical fiber to try optimizing with a custom FAC lens, but I'd love some advice before I try this solution

[ElektroFreak]

I always post this link when people ask about pump correction.. may or may not apply to your specific question.. very good little read, though.

http://laser.physics.sunysb.edu/~xue...breport/p2.htm

More specifically regarding your question, if that system was designed without FAC then yes, adding FAC will throw things off.

It's odd that the system was designed with such losses, has it ever been repaired or worked on before?

[shrad]

no, this is a scientific laser head with its original design

I tried replacing the diode with another one, but it dropped out of alignment or the diode has been zapped and is out of its spectra (still varies in power like any good diode)

hope its not a 830nm diode instead of the 808nm one, as I bought 7 of them claimed as 1.6W spectra physics

they are NIB, so even if they are 830nm, they'd still be resellable (plus they have a FAC lens, not attached, also in the gel-pak)

thanks for the link, I'll have a look, but sadly I have no time in the next few days to look at those lasers, maybe in several weeks, past october ^^

[GooeyGus]

Do you have a tiny crystal set (from a pointer or similar) that you could hold in front of the pump to see if you get green light, thus verifying that they are 808nm?

If not, send me a pm. I've got a bunch and I'd be willing to send one to you so you can make sure your diodes are the right wavelength.

[shrad]

yes indeed, but unfortunately I'm into moving to a new house, and each time I want to have my laser fix, it involves opening X boxes, each opened one being to find that the thing I was looking for is in fact in another box

next time I'll try with a small hybrid, but I think the diode got somewhat zapped like another one I had zapped last month... got that one to work under the spectrometer at work and it appeared the spectrum was a hill between 900nm and 1200nm

these diodes have a tiny FAC lens so when I have a helping hand and a magnifier, I'll be able to try it out.. I think the vertical axis is left untouched by the wedges so it will not interfere with the FAC lens

in that field, I'd take caution in the future when I happen to buy a FACed diode on ebay, as there is a possibility the seller would have glued it himself off axis

anyway, I think I have now two diodes to experiment with a grating to tune the laser output and make an external cavity diode