The most popular retarders are quarter and half wave. When linearly polarized light is input at 45° to the axis of a quarter waveplate, the output is circularly polarized; similarly, input circularly polarized light is transformed into linearly polarized light. One use of a quarter waveplate is in conjunction with a linear polarizer to create an optical isolator (a one-way valve for light). A half waveplate rotates linearly polarized light to any desired orientation.

Multiple and Zero Order Waveplates

With an appropriate choice of thickness, any degree of retardance may be achieved at any wavelength for which quartz is transparent. However, the minimum thickness necessary to achieve a mechanically strong part corresponds to several full waves of retardance. The multiple order waveplate is designed to give a retardance of several full waves, plus the desired fraction (e.g. 10¼). This results in a single, physically robust component with the desired performance. However, even small changes in wavelength or temperature will result in significant changes in the desired fractional retardance.

A zero order waveplate is constructed of two multiple order waveplates (optically contacted, bonded or airspaced) with their axes crossed. Thus, the effect of the first plate is canceled by the second, except for the residual difference between them. For example, crossing a 10¼ wave retarder with a 10 wave retarder results in a unit with an overall retardance of one quarter wave. Any temperature or wavelength induced changes in retardance are also nearly canceled out due to this construction. A zero order waveplate thus provides better thermal and spectral stability than a multiple order waveplate, while offering similar mechanical strength characteristics.

Custom Capabilities

VLOC carries over 100,000 uncoated waveplates in inventory and has developed computer-aided selection software to allow us to quickly match customer requests for both multiple and zero order retarders. This allows quick response for prototype orders. Typical retardance tolerance is between λ/200 to λ/600. Custom orders can be manufactured to any specific retardance in a variety of sizes and shapes. Please contact our sales engineers to discuss your special quartz polarization component requirements.