In a message dated 2007/06/29, gmvoeth@........... writes:

> There is one called (not sure of spelling) michaelson Interferometer
> that uses a laser interference pattern to count the patterns
> and use this to tell the deflection of whatever.

Hi Geoff,

       The problem with these is that the wavelength of light is about 1/2 
micron, which is LARGE in seismic terms. You can measure to small fractions of a 
wavelenght but it is both difficult and expensive. A couple of Si photocells 
and a filament lamp will give you much better seismic performance.

       MIs have 'been around' for about 100 years. 

> Have you ever seen anything relating to bouyancy or levitation ?

       I can't think of anything.

> I have the awareness that it might be possible with the aid
> of a PID loop (Proportional/Integral/Derivative) feedback
> like the cruise control in a car used in conjunction with
> a hall effect sensor to fix a mass at a stable point and measure
> the energy used to keep it at the refrence point.
> PID is commonly used in industrial control to fix settings
> like temperature and flow rates.
> Any Ideas Here ?
> 
    Sounds like a standard wide band seismic sensor to me. They use 3 
component feedback.

    What were those other sensors you were talking about?  

    Regards,

    Chris Chapman
   
In a me=
ssage dated 2007/06/29, gmvoeth@........... writes:



There is one called (not sure o=
f spelling) michaelson Interferometer

that uses a laser interference pattern to count the patterns

and use this to tell the deflection of whatever.




Hi Geoff,



       The problem with these is that the wave=
length of light is about 1/2 micron, which is LARGE in seismic terms. You ca=
n measure to small fractions of a wavelenght but it is both difficult and ex=
pensive. A couple of Si photocells and a filament lamp will give you much be=
tter seismic performance.



       MIs have 'been around' for about 100 ye=
ars. 



Have you ever seen anything rel=
ating to bouyancy or levitation ?




       I can't think of anything.



I have the awareness that it mi=
ght be possible with the aid

of a PID loop (Proportional/Integral/Derivative) feedback

like the cruise control in a car used in conjunction with

a hall effect sensor to fix a mass at a stable point and measure

the energy used to keep it at the refrence point.

PID is commonly used in industrial control to fix settings

like temperature and flow rates.

Any Ideas Here ?



    Sounds like a standard wide band seismic sensor to me. Th=
ey use 3 component feedback.



    What were those other sensors you were talking about?&nbs=
p; 



    Regards,



    Chris Chapman