PURPOSE: To demonstrate birefringence in a calcite crystal.

DESCRIPTION: Light from a bright point source passes through an object (a letter F in a baffle), a calcite crystal, and a lens, which focusses the F onto a distant screen. The calcite crystal can be rotated in its baffle to show separation of the two polarization components. The rotatable polaroid is inserted into the beam between the calcite crystal and the lens to demonstrate that the two component images are orthogonally polarized. The sequence of photographs below shows the two polarized images and both combined with the polaroid at an angle between the ordinary and the extraordinary ray planes.

SUGGESTIONS:

REFERENCES: (PIRA 6H35.15) See Demonstration I7-04: CRYSTAL MODELS - CALCITE for description of calcite crystal formation.

EQUIPMENT: Bright point source with condenser lens and iris, Letter F in baffle, calcite crystal in rotating mount, rotating polaroid, 20cm convex lens.

SETUP TIME: 5 min.