From: pcdhSpamMeSenseless@electrooptical.net   
      
   On 04/04/2014 09:56 AM, haiticare2011@gmail.com wrote:   
   >   
   >>   
   >>   
   >> Optical Coherence Tomography?   
   >>   
   >   
   > I see that in the literature, and it uses the same hobgoblin as the FTIR -   
   the   
   > moving mirror in an interferometer.   
   >   
   >   
   > I wonder how difficult it is to cook up such a device within, say, 2 weeks.   
   > And I hear the "splush" of quick sand. But open to any opinions.   
   >   
   > I would try to cannabalize a micrometer caliber and drive it with a stepper   
   > motor. This contraption has to be pointed at something to get a signal. Same   
   > for FTIR reflectometry.   
   >   
   > I'd much rather push the complexity into the electronics-software domain   
   AMAP.   
   > In that line of wishful thinking, it would be dreamy to have a special filter   
   > in front of a cmos sensor. Presto! The output of the cmos sensor would be an   
   > interferogram of the FT, suitable for analysis.   
   >   
   > Several academic groups have made noises along these lines, one in Japan, but   
   > researchers continue to use the moving mirror.   
   >   
   > Any of you have any opinions on the difficulty of a portable, non-invasive   
   > device like this for FTNIR reflectometry? I immediately think of a DVD RW   
   > device. The FTNIR is much simpler, but the guts of the devices seem to bear   
   > some resemblances...   
   >   
   > In sum, 2 questions:   
   >   
   > 1. How daunting is it to whip up a FTNIR?   
      
   Hard.  The motion precision is the first issue, and keeping the detected   
   amplitude stable throughout the motion is the second.  Then there's   
   calibration.   
      
   Back in the '70s, iirc, people were doing things like dropping the   
   corner cube mirror in a vacuum column and taking the path difference to   
   be 1/2 g*t**2, but it turned out that surface stiction and ambient   
   vibration made the initial velocity and rotation rate too uncertain.   
      
   Cheers   
      
   Phil Hobbs   
      
      
   --   
   Dr Philip C D Hobbs   
   Principal Consultant   
   ElectroOptical Innovations LLC   
   Optics, Electro-optics, Photonics, Analog Electronics   
      
   160 North State Road #203   
   Briarcliff Manor NY 10510   
      
   hobbs at electrooptical dot net   
   http://electrooptical.net   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)