What is Conoscopy?
Conoscopy (from Ancient Greek κῶνος (konos) "cone, spinning top, pine cone" and σκοπέω (skopeo) "examine, inspect, look to or into, consider") is an optical technique to make observations of a transparent specimen in a cone of converging rays of light. The various directions of light propagation are observable simultaneously .
A conoscope is an apparatus to carry out conoscopic observations and measurements, often realized by a microscope with a Bertrand lens for observation of the direction's image. The earliest reference to the use of conoscopy (i.e., observation in convergent light with a polarization microscope with a Bertrand lens) for evaluation of the optical properties of liquid crystalline phases (i.e., orientation of the optical axes) is in 1911 when it was used by Mauging to investigate the alignment of nematic and chiral-nematic phases.