Waveplate

Waveplates and retardation plates are optical elements with two principal axes, one slow and one fast, that resolve an incident polarized beam into two mutually perpendicular polarized beams. Their operation is based on birefringent linear effect, which is the difference in the refractive indices for the beams with parallel and normal polarization towards the optical axis of the crystalline quartz materia being within the waveplate plane. The emerging beam recombines to form a particular single polarized beam.

The Most common types of waveplates are quarter-wave plates(λ/4 plates) and half-wave plates(λ/2 plates), where the difference of phase delays between the two linear polarization directions is π/2 or π, respectively, corresponding to propagation phase shifts over a distance ofλ/4 orλ, respectively.

Some important cases are：

When a light beam is linearly polarized, and the polarization direction is along one of the axes of the waveplates, the polarization stays unchanged.

When the incident polarization does not coincide with one of the axes, and the plate is a half-wave plates, then the polarization stays linear,but the polarization direction is rotated. For example, for an angle of 45°against the axes, the polarization direction is rotated by 90°.

When the incident polarization is at an angle of 45°against the axes, a quarter-wave plate generates a state of circular polarization. (Other input polarizations lead to elliptical polarization states.) Conversely, circularly polarized light is converted into linearly polarized light.

Specifications: