Campbell Scientific PWS100 Present Weather Sensor - Manual (Page 88)

Section 8. Functional Description
FIGURE 8-1. Laser unit
Rod lens Cylindrical lens
Doublet lens Grating Laser
FIGURE 8-2. Laser unit showing light sheet production (not to scale)
The sensor units as shown in Figure 8-3, comprise a lens, a filter tuned to the
wavelength of the laser output and a photodiode placed at the back focal length
of the lens with suitable amplification electronics. This photodiode then
accepts light from the detection volume over a finite range of angles as shown
in Figure 8-4.
8-2