The Collaborative International Dictionary of English v.0.48:

Polariscope \Po*lar"i*scope\, n. [Polar + -scope.] (Opt.)
   An instrument consisting essentially of a polarizer and an
   analyzer, used for polarizing light, and analyzing its
   properties.
   [1913 Webster]

WordNet (r) 3.0 (2006):

polariscope
    n 1: an optical device used to measure the rotation of the plane
         of vibration of polarized light [syn: polarimeter,
         polariscope]