USER'S GUIDE  ____________________________________________________________________ 
106  __________________________________________________________________ M211187EN-C 
 
  0009-006 
Figure 38  FSR102 Receiver Block Diagram 
An ambient light level as high as 30 kcd/m
2
 neither influences the 
detection of the photodiode, nor saturates the preamplifier. The DC level 
is monitored for detecting eventual saturation caused by the ambient 
light. 
Two infrared LEDs are provided for the backscatter and contamination 
measurement. The light level is sampled and converted using the same 
method of detection described with the scattering signal measurement. 
The window contamination measurement principle is based on the 
change of the total reflection of the light beam on the window surface. 
The principle is shown in Figure 37 on page 105.