Optical sensor for detecting indicatrices

摘要

The sensor contains a special lens for deflecting a beam emitted from a point on the axis of symmetry in a spatial angle of about 2 pi into an axially parallel beam. The lens consists of smooth surfaces using both refraction and reflection for beam deflection and has different focal lengths for different emission angular regions. The lens is used in combination with a suitable input coupling lens for simultaneous top illumination of a specimen and to make a reflection indicatrix measurable. The aperture errors for both detection regions are reduced, e.g. by using a parabolic reflective surface (PA) and making the corresp. input surface (KZ) concentric with the emission point.