In a message dated 23/10/2009, gmvoeth@........... writes:

Would it  be possible to somehow use an electron microscope to actually 
measure a  real
displacement of a pendulum or spring mass thingamajig  ??



Hi Goeff,
 
        I suppose that you could  build one inside a vacuum system, but why 
bother?
 
    LVDT sensors can be made to work down to 0.1 nano  metre. Differential 
capacitor types can give over 10x more resolution and you  are then close to 
atomic dimensions. The practical problem then becomes the  temperature 
stability of the sensor. 
    
    However, this is way below the amplitude of the  quiet earth graph - 
you can't see any signals below the natural seismic  noise level. Modern 
seismometers are usually enclosed in a sealed can to remove  atmospheric pressure 
noise. 
 
    Regards,
 
    Chris Chapman






In a message dated 23/10/2009, gmvoeth@........... writes:
Would it=20
  be possible to somehow use an electron microscope to actually measure a=
=20
  real
displacement of a pendulum or spring mass thingamajig=20
??


Hi Goeff,
 
        I suppose that you co=
uld=20
build one inside a vacuum system, but why bother?
 
    LVDT sensors can be made to work down to 0.1=
 nano=20
metre. Differential capacitor types can give over 10x more resolution and=
 you=20
are then close to atomic dimensions. The practical problem then becom=
es the=20
temperature stability of the sensor. 
    
    However, this is way below the amplitude of=
 the=20
quiet earth graph - you can't see any signals below the natural seism=
ic=20
noise level. Modern seismometers are usually enclosed in a sealed can to=
 remove=20
atmospheric pressure noise. 
 
    Regards,
 
    Chris Chapman