Subject: Re: aperture align problems
From: John Cumings <>
Date: Sat, 03 Apr 2004 11:23:04 -0800

Kai Mei,

I'm not sure, but I think this may also be caused by not doing a proper
gun align first.  Remember that the scan speed during gun alignment can
affect the adjustment.  For proper gun alignment, you should operate at
scan speed 9 when in emission mode.  

I presume you knew this, but it is good that we have this email list just
so we can double-check each other.



     John Cumings 
     Postdoctoral Scholar
     Physics Department
     Stanford University                        

     office (650) 725-1025
     lab (650) 725-2047
     fax (650) 724-3681

     Geballe Laboratory for Advanced Materials
     239 McCullough Building
     476 Lomita Mall
     Stanford, CA 94305-4045
In message <>you write:
>Kai Mei,
>     First of all the focus wobble doesn't work.  You can test this by
>changing the focus manually back and forth. You'll find that the image is
>still moving around even when it doesn't when you turn on focus wobble.
>The best way to align the aperture is to 'focus wobble' manually. This
>fact is noted in the GG lab version of the raith instructions which is on
>the swiki.
>     Having said that, the 120 micron aperture has had the same problem
>since two bakeouts ago. As far as I know, the machine will just have to be
>opened up again and things realigned.
>     HOpe this helps.
>On Thu, 1 Apr 2004, Kai-Mei Camilla Fu wrote:
>> Date: Thu,  1 Apr 2004 17:51:21 -0800
>> From: Kai-Mei Camilla Fu <>
>> To:
>> Subject: aperture align problems
>> I am using the 7.5 micron aperture and can't seem to align it using 
>> aperture align.  The focus wobble improves as I move the aperture to x = 
>> 100% but I can't move it furthur.  Does anyone know what to do in this case?
>> Thanks,
>> Kai-Mei