Zero Order Half-Waveplates

Zero Order Quarter-Waveplates

Multiple Order Half-Waveplates

Multiple Order Quarter-Waveplates

Multiple Order retardation plates:
The refractive index of crystalline quartz depends on the orientation of the plane of polarization of light with respect to the axis of the crystal. The direction for which the refractive index is the largest (the speed of light is the smallest) is called the slow axis. The perpendicular direction with the smallest index of refraction – the fast axis of the crystal. The slow axis of a MO plate is marked with a side flat. Due to this polarization dependence of the phase velocity a plate made of crystalline quartz with an appropriate thickness may rotate the plane of polarization (λ/2 plate) or convert a linear polarized light into circular polarized and vice versa. Lens-Optics offers multiple order dichroic plates for two wavelengths with λ/2 (180 deg.) or λ/4 (90 deg.) λ/300 retardation in the region from 250 to 2000 nm.

Zero Order retardation plates:
A zero order retardation plate is a combination of two multiple order plates having retardations that differ by exactly λ/4 or λ/2. By aligning the fast axis of one plate with the slow axis of the other only the difference of the two retardations will affect the polarization of the transmitted light. Zero order retardation plates are much less sensitive to wavelength and to temperature changes (~ 0.0001 λ/°C). For example a 780 nm plate may be reasonably used in a spectral region from 765 to 795 nm.