On Saturday, April 5, 2014 8:12:13 AM UTC-4, sgpopt...@gmail.com wrote:   
   > It is not reflectometry.. Actually, it is an AM modulated signal that I am   
   seeking. Revealing the details of the app would be difficult, as my employer   
   would not like that.    
   >    
   >    
   >    
   > But in a nut shell, I have a very weak laser source, this source emits a   
   1MHz signal with low duty cycle and looks at the reflection of this signal.   
   The object in 400mm distance makes a motion and by analysing the reflection,   
   the system interprets the    
   motion and takes several decisions. Now the job is 10x the distance without   
   increasing the laser source.    
   >    
   hmmm - If you want *definitive* advice, I would advise you to get more   
   specific    
   about the optics w/o telling the app.    
   But from what you say, literally, you could try back-end signal enhancement    
   methods, like lock-in and signal averaging.   
   A $5 microprocessor can do these.   
      
   j.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)