Ordinary ray passes undisplaced. Extraordinary ray is laterally displaced by an amount dependant on the length of the crystal. Therefore the extraordinary ray transcribes a cylinder when the polarizer is rotated. Both beams have high polarization purity.
Beam displacer polarizers separate an incoming beam into two orthogonally polarized, parallel output beams. The ordinary ray is transmitted undeviated, the extraordinary ray is laterally displaced. This is similar to the output of a Rochon polarizer except that the Rochon separates by angular deviation.
The lateral separation of the beams depends on the wavelength and the length of the crystal. The ratio of separation to length is approximately 1:10 in calcite, so fairly long crystals are required. This limits the beam diameter when total separation is required.
Since the beam displacer polarizer is manufactured from a single crystal, the power handling capability is high.
|Beam separation / length ratio||~1:10|
|Highest angular beam deviation tolerance||30 arcsec|
|Surface quality||40-20 S/D (DIN: 5/2 x 0.16)|