>    
   > Wiki says that the volume fraction is about 45%, and an erythrocyte is    
   >    
   > about 6 or 8 microns across, so the mean free path is something like   
   >    
   >    
   >    
   > MFP ~ 6 um/(0.45)**1/ ~ 7 um,   
   >    
   >    
   >    
   > which is somewhat unrealistically generous since it ignores the volume    
   >    
   > taken up by the blood cells themselves.   
   >    
   >    
   >    
   > So your 1 mm of blood will scatter the light not once but over 100    
   >    
   > times.  In other words, it's completely diffuse.   
      
   Phil, Thanks for your analysis of scattering. I wanted to return to this issue   
   of diffuse transmission to see what you think of the following analysis on a   
   photon per photon basis, involving superposition. We are looking for a number   
   about the presence    
   of absorbing particles, about 1% v/V, and the rbc's or their lysed ghosts, are   
   50%.   
      
   In one thought-picture is the light being elastically scattered through the    
   1 mm cuvette. Most is scattered out of the optical path that reaches the PD,   
   but some manages to get through, call it X number of photons.   
      
   In another picture, we have just a few absorbing particles present in a 1 mm   
   path along with above scenario. At 1% v/V, a photon NOT getting scattered will   
   encounter about 1 of these inelastic absorbers. And IF a photon gets through   
   the scattering media    
   to reach the PD, it also has had a chance of sncountering an absorber, call it   
   P.    
      
   So, the signal seen is X-P, where P has the signal information.    
      
   What do you think of this analysis?    
      
   TIA,   
   JB   
      
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