From: pcdhSpamMeSenseless@electrooptical.net   
      
   On 1/29/2014 9:59 PM, haiticare2011@gmail.com wrote:   
   > Phil, The ouija puck flies in another direction... Just out of   
   > curiosity, do you machine and build your prototypes? I have a machine   
   > shop with a cnc swiss lathe and a small lathe plus mini-mill. I have   
   > been machining various cavities to measure Hb in a thin arteriole   
   > model - One approach is to shoot the light directly through   
   > transverse. Another is the reflective cavity approach as discussed by   
   > M. Johnson. Still a third is a narrow cavity which 'supports' an   
   > evanescent wave.   
   >   
   > Speaking of reflective, I saw BaSo4 paint at Edmunds. They use a   
   > minimum of binder, and I think that's the secret - the Fresnel   
   > formula is the square of refractive index index, so just an   
   > light-incoherent binder will reduce reflection considerably, even   
   > with no interference.   
   >   
   > ButI don't want to pay XXX $ per ounce, so am thinking of "depleting"   
   > TiO2 paint of its binder.   
   >   
   > JB   
   >   
      
   What I tell clients is that it's cheaper if they do the mechanical   
   design work.  (It is.)   
      
   Being a physicist, I tend to make integrating spheres myself, using   
   cheap'n'cheerful Chinese ping-pong balls with several layers of spray   
   paint on the outside.  My favourite recipe is 5 or so coats of Krylon   
   1502 white, followed by 3 coats of Krylon 1602 ultraflat black.  That   
   works pretty well for lots of jobs, e.g. measuring LED output.   
      
   Doing it right is a bit more difficult, of course.  There's a Labsphere   
   app note that talks about the math of integrating spheres, which is   
   actually surprisingly subtle for such a simple device.   
   ( http://labsphere.com/technical/technical-guides.aspx )   
      
   To do it right, you need at least a millimetre of MgO or BaSO4 paint, in   
   probably six coats, with (as you say) a minimal amount of just the right   
   binder.   
      
   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)