means for producing an electrical signal in {HEAD ~ the photodetector} having {TAIL ~ a frequency component} proportional to the blood cell velocity in response to autodyne beating of Doppler shifted and non Doppler shifted radiation signals 
having
means for producing an electrical signal in { HEAD ~ the photodetector } having { TAIL ~ a frequency component } proportional to the blood cell velocity in response to autodyne beating of Doppler shifted and non Doppler shifted radiation signals
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH