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.

Quarter-wave waveplates are used to turn plane-polarized light into circularly polarized light and vice versa. To do this, we must orient the wave plate so that equal amounts of fast and slow waves are excited – for example, by orienting an incident plane-polarized wave at 45° to the fast (or slow) axis. On the other side of the waveplate, we again examine the wave at a point where the fast-polarized component is at maximum. At this point, the slow-polarized component will be passing through zero, since it has been retarded by a quarter-wave or 90° in phase. If we move an eighth wavelength farther, we will note that the two are the same magnitude, but the fast component is decreasing and the slow component is increasing. Moving another eighth wave, we find the slow component is at maximum and the fast component is zero. If we trace the tip of the total electric vector, we find it traces out a helix, with a period of just one wavelength. This describes circularly polarized light.

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.