Re: Argon ion laser - age/noise and effect on images..?

Posted by Jacqueline Ross on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Argon-ion-laser-age-noise-and-effect-on-images-tp7586010p7586016.html

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Thanks Steve,

 

I can reduce it by going slower and using more averaging. However, the PMT gain that I’m using is usually only 600V and to get a reasonable image, I’m having to slow right down and use averaging Line 8 on a system when I normally would get a good image with faster speed and Line 4 with similar labelling. It’s a bit puzzling but I’ve got a few tests to do now to see if I can get a better idea of what’s happening.

Cheers,

 

Jacqui

 

 

From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Stephen Cody
Sent: Friday, 18 November 2016 2:47 p.m.
To: [hidden email]
Subject: Re: Argon ion laser - age/noise and effect on images..?

 

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Hi Jacqui,

 

I would expect you'd see black horizontal lines if the laser was failing. If you are seeing a grainy image (I'm presuming a noisy image); increasing laser power though AOTF and decreasing PMT gain (HV) should make it go away.

 

Cheers Steve

 

Stephen H. Cody

On 18 Nov. 2016, at 8:26 am, [hidden email] wrote:

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Hi Jacqui,

Could your laser have just gone out of alignment? This happens quite regularly on our old SP2.

cheers,

Rosemary

 

Dr Rosemary White

CSIRO Black Mountain

GPO Box 1700

Canberra, ACT 2601

Australia

 

T 61 2 6246 5475

E [hidden email]

 

From: Confocal Microscopy List <[hidden email]> on behalf of Jacqui Ross <[hidden email]>
Reply-To: Confocal Microscopy List <[hidden email]>
Date: Friday, 18 November 2016 11:19 am
To: "[hidden email]" <[hidden email]>
Subject: Argon ion laser - age/noise and effect on images..?

 

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Hi everyone,

 

I’m hoping that someone can help me to confirm whether an effect I am seeing with one of our confocal  microscopes is likely to be due to the ageing of an argon ion multiline laser.

 

The laser is about 8 years old and the power level has dropped to about 1/3 of the original output but we are still able to excite the fluorophores very well at AOTF controlled percentages <5%.

 

What I’m noticing is that when I use the argon ion laser, e.g. 488nm line, the images look much more granular than when using other lasers when similar voltages are being used at the PMT. I’ve checked the other detectors and it doesn’t seem to be related to the PMTs.

 

Much slower speeds and more averaging do improve the images but I’m puzzled by this as the issue is there even when the Master gain/voltage is at a level which I wouldn’t normally need to go slower/average as much.

 

Can anyone tell me whether the age of the laser can cause issues like this? I’m wondering if we should just replace it. We only normally replace lasers when they expire.

 

Or if there are some tests that I can do to further define the issue?

 

The last measurements were as below for 8A with two different beam splitters;

 

488nm              0.51mW (NT 80/20)                    2.31mW (MBS488)        

Thanks in advance for any ideas.

 

Cheers,

 

Jacqui

Jacqueline Ross

Biomedical Imaging Microscopist
Biomedical Imaging Research Unit (BIRU)
School of Medical Sciences 
Faculty of Medical & Health Sciences
The University of Auckland
Private Bag 92019
Auckland 1142, NEW ZEALAND

Telephone: Ext 87438; DDI:  [phone]

Website:    http://www.auckland.ac.nz/biru