'optical cube' definitions:

Definition of 'optical cube'

From: GCIDE
  • Biprism \Bi"prism\, n. [Pref. bi- + prism.]
  • 1. A prism whose refracting angle is very nearly 180 degrees. [Webster 1913 Suppl.]
  • 2. A combination of two short rectangular glass prisms cemented together at their diagonal faces so as to form a cube; -- called also optical cube. It is used in one form of photometer. [Webster 1913 Suppl.]