Re: I90, Brewster window cleaning.

Simon,

> How often do you all find you need to clean your Brewster windows on 
> Argon I90s? I just cleaned mine a month ago and already the current is 
> creeping up. It is really awkward on Vantages especially with DIVA 
> option, be glad when these things are a thing of the past.
>

I'm sure we'd go closer to 12 months than 1 month between Brewster 
window cleaning.  Are your Brewster window dust cover tubes closed?  
There is another effect that can come from aged dust covers: They 
contain an activated silver mesh whose function is to absorb the ozone 
generated (particularly in UV but also at 488).  If the covers have 
lost their reactivity, there can be a build up of ozone inside that 
space that results in loss of power and can also result in more rapidly 
dirtying Brewsters.  Check if that is the cause by watching the power 
as you slide them back.  If they are not working, you'll get more power 
with them slid back than if they are closed.  If that is the cause and 
you don't want to replace them, try running with the covers slightly 
ajar.

I certainly concur with you on wanting to get rid of the Ar dinosaurs; 
the main reason I need mine is that they also do UV.  Has anyone yet 
proved that the solid state, 10MHz, "pseudo-continuous" UV lasers are 
no more damaging to cells than genuine continuous-wave UV lasers (I'm 
worried about those high energy spikes)??

Frank.

     |	  |  << Frank Battye PhD
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