Our true zero-order wave plates consist of a birefringent polymer film cemented between two high-precision N-BK7 optical windows, each with a high efficiency, broadband antireflection coating. This construction ensures excellent transmitted wavefront quality, while minimizing beam deviation and surface reflection losses. The assembly is mounted in a black anodized aluminum housing for protection and ease of mounting, with the wave plate fast axis marked for alignment reference.

A half-wave plate can rotate the plane of polarization from a polarized laser to any other desired plane. Suppose a plane-polarized wave is normally incident on a wave plate, and the plane of polarization is at an angle θ with respect to the fast axis. To see what happens, resolve the incident field into components polarized along the fast and slow axes, as shown. After passing through the plate, pick a point in the wave where the fast component passes through a maximum. Since the slow component is retarded by one half-wave, it will also be a maximum, but 180° out of phase, or pointing along the negative slow axis. If we follow the wave further, we see that the slow component remains exactly 180° out of phase with the original slow component, relative to the fast component. This describes a plane-polarized wave, but making an angle θ on the opposite side of the fast axis. Our original plane wave has been rotated through an angle 2θ.

The polymer material has very low birefringence that is nearly constant with wavelength. The retardance δ at a new wavelength λ that is different from the center wavelength λc is given by: δ = δc(λc/λ) where δc is the retardance at λc. The primary benefit is a moderate insensitivity to wavelength change, making them ideal for laser diode or tunable laser applications.

Polymer wave plates feature better angular acceptance than quartz wave plates. Polymer wave plates have excellent angular field of view. Retardation changes by less than 1% over a ±12° incidence angle.