PSN-L Email List Message

Subject: Re: A Free Mass seismometer
From: "David H. Youden" dyouden@.........
Date: Tue, 08 Apr 2003 06:07:34 -0400

Hi Chris,

Sorry to be slow responding to you, but there is work to be done.

For information on high resolution stage interferometry go 

Select semiconductor, stage position, zmi systems, and read all about it. 
The stuff I usually use is the ZMI 2000 which costs about $9000 per axis. 
All that for one more fuzzy digit.

More later, gotta go.


At 12:38 PM 4/6/03 -0400, you wrote:
>In a message dated 06/04/03, dyouden@......... writes:
>Hi Dave,
>       Thanks for the reply.
>>I guess complexity depends upon personal viewpoint to some degree. What 
>>you have described seems complex to me. I have built systems similar to 
>>what you describe and the complexity springs from having to prevent rotation.
>       ? It is two flat sheets of glass with 4 pairs of small magnets and 
> two strips of metal mounted horizontally on top of the top sheet --- it's 
> not too complicated! I would expect it to be rather easier to prevent 
> rotation than to do the linear positioning.


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