how ro pump a 473nm crystal assembly?

[Draco]

I have had this LBO device for a while and i am hoping i can find some help here, I am having some difficulty finding out what type of pump diode i need for it, i get some saying it's pumped with 808nm like a green dpss but others tell me the pump diode is 1064? I am at a loss on this one here are pictures of it
DSC01719.JPG
and the inside
DSC01722.JPG
DSC01727.JPG

I have tryed pumping it with 808 but i doubt i had enough power or a correctly shaped beam, i cant find info on this thing so i dont even know what end to pump it from. I am also getting another 473nm with an unknown problem, i want to get this set working as i love this color.

Thanks

[JRGixxerfreaK1]

I have had this LBO device for a while and i am hoping i can find some help here, I am having some difficulty finding out what type of pump diode i need for it, i get some saying it's pumped with 808nm like a green dpss but others tell me the pump diode is 1064? I am at a loss on this one here are pictures of it
DSC01719.JPG
and the inside
DSC01722.JPG
DSC01727.JPG

I have tryed pumping it with 808 but i doubt i had enough power or a correctly shaped beam, i cant find info on this thing so i dont even know what end to pump it from. I am also getting another 473nm with an unknown problem, i want to get this set working as i love this color.

Thanks

I do miss that 473nm blue,

from what I know they are pumped with 808nm, but dont know what 1064nm has to do with it?
Anyways 808nm is your pump source most likely , its being converted to 946nm then finally doubled to 473nm by LBO or BBO
so if your not seing any output even with lots of tries do a little wiggle of the pump diode to get it aligned you should be able to see brief flash of blue,
If not you have following possible scenarios:

1. LBO or BBO I believe was Hygroscopic, has a problem with moisture , that could be your first problem since it is exposed to the house air , but now a days I believe they use a more efficient ones like BiBO, those not really suffering the problem

2. im not sure but I think maybe you need to shift you 808nm pump wavelength using tec, either heating or cooling,

3. Temps on the crystal , need to find a optimum temp with the tec, although I believe it should lase even at room temp, thou not efficient

4. 473nm blue dpss being very inefficient only at 3-5 % of blue output you get, I think you need to give your pump a little kick


Ohh and please be very careful with 808nm pump diode, invisible danger! wear a proper protective ir suited goggles or shield yourself away from it like I did using the crude way of cmos camera hooked up to your tv screen :P

[catalanjo]

@ Philip-"808nm ......its being converted to 946nm" .....I think it is this stretching stage that our reptile friend is having trouble with!

Both colours are invisible which doesn't help much,so all the alignment process is a PITA until you get the first glimpse of final blue output.

After that it gets much easier to optimise !
Like many others here, I have always mucked about with pre-aligned setups but I can imagine the hassles involved pretty easily when starting from scratch !

Cheers

[JRGixxerfreaK1]

@ Philip-"808nm ......its being converted to 946nm" .....I think it is this stretching stage that our reptile friend is having trouble with!

Both colours are invisible which doesn't help much,so all the alignment process is a PITA until you get the first glimpse of final blue output.

After that it gets much easier to optimise !
Like many others here, I have always mucked about with pre-aligned setups but I can imagine the hassles involved pretty easily when starting from scratch !

Cheers

yes both wavelength is invisible :P

im no expert at all, im assuming you could use a IR detection card and have the ir lase at low power not to burn the card

Im sure planters or others could chime in

[planters]

I am pretty sure that except for the coatings and doping concentration that you have a Nd. YAG crystal that has gain at 1064nm as well as weaker gain at 946nm. If so, then the pump wavelength should be 808nm. Is the crystal assembly monolithic or can you separate the doubler? Use an IR capable CCD camera (a security cam) or a filter-less webcam and you can image both wavelengths. How many watts of 808nm are you using? This wavelength is visible, but at dangerously low visibility (1/64,000 vs 555nm) and several watts looks like a few hundred micro watts. Focus a few watts of 808 into the crystal and look for the emission. I am assuming the YAG is monolithic with its mirrors. If not, then while pumping with the diode, adjust the cavity optics until you get some emission. With this short a cavity and the gain at 946 still decent (the 1064nm gain will have been inhibited by factory coatings) I am sure that even hand adjustments will generate an IR flash. Unless the diode is way off, several watts near 808nm is likely to pump the cavity enough to get a flash. From there it is just a matter of optimizing IR output with diode temperature and mirror adjustment.

Placing and adjusting the doubler within a live 946nm beam should generate a blue flash if it ever will.

[mixedgas]

Please wear safety glasses! An Eye is a terrible thing to waste. 808 is very nasty in this regard. 808 diodes usually emit a little incoherent red, which lulls people into feelings of security.

Steve

[Draco]

I have not tried taking the device apart any farther then just for the pictures and reassembled it so none of the factory alignment "should" have changed, it's always been in a bubble package. Now I am sure i dont have enough pumping power, when i tried i was using about 100mw of 808nm. and part of the prism from a green dpss for the beam correction, i have a more powerful 808nm on order and i will need to make a mount for it.
I do have a web cam with the ir filter removed and good quality safety glasses for the IR lines, i have 4 pairs scattered around so one is always at arms reach, i had gotten them when i bought my first high power laser, now i wish that one was 808nm, it was a bar type diode laser but is not close to 808nm.

I am assuming i will need to try pumping from each end to see if it worked or not? I forgot what end was the input
Thank you very much for the info, now i just need to try it at a higher power level, i have a 1 watt on hand now that some times mode hops but a 2 watt replacement on the way

[Draco]

is 2 watts enough power? if so i will need to pause and let my budget catch up a bit

[buffo]

2 watts should be enough to get it to lase, but remember that DPSS blue designs are notoriously inefficient when compared to DPSS green. For one, the gain on the 946 nm line is a lot lower than the gain at 1064 nm. But more importantly, the doubling crystal is *very* inefficient at converting the 946 to 473.

A good rule of thumb for a 473 nm blue is 3 to 5% overall efficiency. So in your example your 2 watt pump diode should yield a maximum of 100 mw of blue if everything is properly aligned.

You didn't mention how much power the laser was originally rated for... If it was a 100 mw unit, you're probably fine. If it was a 10 mw unit, you're over-driving it, and if it was a 500 mw unit you might not see much output at all.

Adam

[Draco]

Thank you for the info.

i bought the crystal from a surplus vender and the rated power is unknown, the crystal is fairly large, that's kinda why i ball parked a 2 watts