A receiver including an analyzer and a detector coupled to the output of
the analyzer. The analyzer selects a polarized component of a return beam
for input to the detector. The analyzer may be linear, circular or
elliptical. Coupled with a laser adapted to output a polarized beam, the
receiver provides an active optical target detector. An arrangement may
be included for compensating for rotation and ellipticity in the returned
beam. In one embodiment, the arrangement for compensating for rotation of
the orientation of linear polarization in the returned beam includes a
Faraday rotator positioned between the transmitter and the analyzer. An
arrangement is disclosed for varying the rotation in the returned beam
using a Faraday rotator until a maximum transmittance is achieved. In an
alternative embodiment, the arrangement for compensating for ellipticity
in the returned beam includes an electro-optical modulator positioned
between the transmitter and the analyzer. In another alternative
embodiment, two electro-optical modulators are included to compensate for
any change in the polarization state in the returned beam.