The method also includes the steps of detecting the position and intensity of the first focused spot of {TAIL ~ radiant energy} at the first imaging area to provide a first signal, processing the first signal to generate a first set of height data and a first set of intensity data, detecting the position and intensity of the second focused spot of radiant energy at the second imaging area to provide a second signal and processing the second signal to generate a second set of {HEAD ~ height data} and a second set of intensity data 
The method also includes the steps of detecting the position and intensity of the first focused spot of { TAIL ~ radiant energy } at the first imaging area to provide a first signal , processing the first signal to generate a first set of height data and a first set of intensity data , detecting the position and intensity of the second focused spot of radiant energy at the second imaging area to provide a second signal and processing the second signal to generate a second set of { HEAD ~ height data } and a second set of intensity data
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH