In a message dated 24/04/2010, gmvoeth@........... writes:

I have  this laser pointer and was just wondering how it might be used with 
mirrors to  detect ground motions ?
Hi Geoff,
 
    It is NO USE. These small lasers are VERY noisy and  the intensity 
drifts a lot with temperature.

How  about two silvered surfaced mirrors that bounce the light
between them at a  slight angle sort of like you see yourself
a zillion times in a mirror at  the barber shop ??
a teeter totter mirror bouncing off a light beam  ?

What kind of sensor for a red LED laser pointer ?
    Any ideas ?
 
    A couple of large area silicon photocells and  a small filament bulb 
work very well. In some measurements I found that I could  resolve motions 
down to less than 15 nano metres.
 
    Regards,
 
    Chris Chapman







In a message dated 24/04/2010, gmvoeth@........... writes:
I have=20
  this laser pointer and was just wondering how it might be used with mirr=
ors to=20
  detect ground motions ?
Hi Geoff,
 
    It is NO USE. These small lasers are VERY noi=
sy and=20
the intensity drifts a lot with temperature.
How=20
  about two silvered surfaced mirrors that bounce the light
between the=
m at a=20
  slight angle sort of like you see yourself
a zillion times in a mirro=
r at=20
  the barber shop ??
a teeter totter mirror bouncing off a light beam=
=20
  ?

What kind of sensor for a red LED laser pointer ?
    Any ideas ?
 
    A couple of large area silicon pho=
tocells and=20
a small filament bulb work very well. In some measurements I found that I=
 could=20
resolve motions down to less than 15 nano metres.

 
    Regards,
 
    Chris Chapman