NEOS PCAOM 6 ch Help

[Tesa]

Hello all

thanks for all the good reading in here. I'm sorry my bad English but I hope you
understand anyway.

I have a 10w whitelite laser with 2 spectraphysic tubes, 1 argon 1 krypton. I also have a NEOS PCAOM 6 ch system.
I have installed Neos and driver, but the light output is very low and the waste beam is over 80%

I've mounted a polarizing cube

(http://www.thorlabs.de/thorProduct.cfm?partNumber=GTH5)

so my problem should not be polarizing.

I do not know much about gas lasers and PCAOM's so I hope someone can help.
if anyone has the manual for the driver it would help much.



can anyone help me how to set the driver? I have searched everywhere but could find nothing.

[stanwax]

Does your PCAOM cell (the part the beam goes through) have a bragg mount?
that will allow you to adjust the angle so its at it s most effecient angle for its function.
Set the channels on the driver to match the wavelengths you have then start with one channel - a strong one such as 488nm or 514nm and put 5v to the driver input. Then adjust the angle of the cell until that line is brightest. Now try feeding 5v to the other channels and they should all work.
Rob

[Tesa]

yes I have adjusted so it is the strongest wave is used.

how do I know what wavelength the driver set to? everything I have on the driver is 2 screws per channel indicated by numbers and letters and a level adjust, but I do not know what they are

[dsli_jon]

Hi Tesa -

have a 10w whitelite laser with 2 spectraphysic tubes, 1 argon 1 krypton.

Are these SP 164s or 168s? Just-curious, Lemme know..

I've mounted a polarizing cube...so my problem should not be polarizing.

All due-respect, I think that may-be exactly your problem...if the cube is oriented so that it is rotating your typically (in SP 164s/168s) vertically-polarized beams into H-pol, then you are shooting the combined-beams into a vertically-mounted PCAOM, that would about do it (...murder your output like this...) -

Try 'rotating' your polarizer 90˚, still-parallel relative to the beam-input (ie; rotate it 90˚ on it's 'side') and PCAOM and see if that changes your output-level...
Alternatively, you could also try mounting your PCAOM at a 90˚ to the beam-input... you could also use a '1/4-wave plate', but I am guessing you probably don't have one of those 'lying-around'...

And - yes - as-was correctly pointed-out, you also need to have the PCAOM in a proper mount for adjusting the 'bragg-angle' - Also, you need to ensure that the combined-beams are, indeed, going thru the 'sweet-spot' of your x-tal, called the "clear-aperture"...

Here's a great article by Bob Ash, of 'New Method Lasers' fame...



The more 'classic' (and easier to manage) way to combine an Ar/Kr pair is with dichroics / adjustable mounts... I have a set, laying around, in mounts I could sell, (as I am sure do-others ) but here is a 'pic' of the 'typical' method to do this:



...this way, you have easily-tweekable adjustments for 'convergence' of the B/G and R beams, and this will not change your native tube-polarization (as-shown)...

I do not know much about gas lasers and PCAOM's so I hope someone can help. if anyone has the manual for the driver it would help much. -
can anyone help me how to set the driver?

I can hook you up with the driver-setting manual, but I doubt it is that - most-likely, it-is your combo-scheme / polarization.

Also, more-likely than a 'totally-fried' driver (though that is possible, if you put full-strength signals to the driver, then unhook the RF-cable, that can do it in..), it *could* be your RF-cable - it needs to be RG-58 and have no defects that could cause 'shorting' of the + / – or any 'back-reflection' of the RF... I have seen them inexplicably 'go-bad', many-times over the years...

If re-doing your combining-scheme / rotating the pol, does not work, that would be the next thing I'd ferret out - change the cable to a new RG-58, and make sure any 'elbows' / adaptors are also not 'bad'....

Lemme know...
cheers..
j

[Tesa]

Hi Dsli Jon

it is two Stabilite 2011 tubes.
I am sure that my beam is V pol, cause when I rotate the polarizer 90˚ my output disappears completely.

I've tried with a new RG-58 cable, but it made no difference.

I take some pictures tomorrow, maybe it can help

if you know where I can find the manual. it would be a great help

[300EVIL]

if you know where I can find the manual. it would be a great help

PM me your email address and I'll send you the selector switch assignments with wavelength/frequency chart. You may need access frequency counter to re-tune the driver if it's off.

[mixedgas]

There are two types of PCAOM crystals by NEOS. The older one, the connector should be in the plane of the brewster window. The newer one should be across the plane of the brewster window. The "sweet spot" where everything works inside the crystal is about 2 mm tall by 2 mm wide, if you are not in the "sweet spot" and the polarization does not match, you get garbage out. You have to "search" the crystal up and down and left and right as well as rotate it. Usually I rotate the BNC connector about 10 degrees away from the laser about the pivot point. You align on the 488 line for beast power and cleanest diffraction order, then you start on the colors. Its tough, the first time, to find the right spot. The newer ones tend to have the connector on top of the housing.

Steve

48062s are the older crystal.

[Tesa]

Hello I took some pictures and hope you see what I'm doing wrong.

the left dot on the first photo is the first order beam, the right is the 0 order.

i pic. 3 the right is the fisrt order

[dsli_jon]

Hi Tesa -

Hello I took some pictures and hope you see what I'm doing wrong.

Of course, hard to call anything 100% from pix, but a question: in this pic - http://www.photonlexicon.com/forums/...7&d=1300963501 ...if looks like your tube might-be rotated in the magnet / jacket, or, even whole assy. in the mount? Granted, you might very-well have a V-pol beam, but it is possible to have the tube rotated, in-place, and that would also whack the heck-out of your efficiency (if the pol. was-actually 10 or 20˚-off from true V...) Yes, would-be 'atypical', but that's what we're looking for, here, yes?

Also, what is going-on with that 'periscope' assy. with the MM-1s, there? Is that your beam-combining cube? I honestly think that could be most of your problem, right there... I respecfully-suggest you scrap that method of combining / rotating polarization, and use the more 'classic' combining-scheme, with the PCAOM being mounted vertically... ie:



...since, unless you have an RF watt-meter and an O-scope, you are also really kind-of 'shooting in the dark', too, with troubleshooting down the x-tal / driver path, further... one way to quickly test is to swap with a known-good x-tal / driver - If you don't have another, know anyone that does? Friend? Nearby laser-sho co? Just some thoughts...

But I'd bet it's your cube / combo-scheme, there...Or your tube is rotated, in its 'crib'... let us know..
ciao
j

[mixedgas]

Ah, the picture tells me everything!

That is a I90MRA and I90MK dual medical sled. The red tube is rotated 90' on those, and is nearly impossible to rotate back because of the special "in series with the tube" magnet on the krypton and the way the MK gas ballast sticks out. DO NOT try to bend the gas ballast piping, it will kill the tube. You need a half waveplate or a special combination of mirrors to rotate the red polarization to match the pcaom.

Steve