What is the benefit of polymer retarders?

Traditionally, the birefringent materials of choice for retarders have been naturally-occurring crystalline materials such as calcite, mica and quartz. Some applications now require performance versatility beyond what these crystals can offer. Using birefringent polymers for polarization control offers a unique combination of high performance and cost-effectiveness.

Precision polymer retarders feature carefully aligned birefringent polymer sheets laminated between two precision BK7 windows. Polymer materials offer a lower birefringence than quartz and can therefore be made into true zero-order retarders of reasonable thickness. They also offer excellent angular field-of-view since they are true zero-order retarders.

Polymer retarders are much less sensitive to incidence angle than quartz retarders. The curve below compares the change in retardance as a function of incidence angle for polymer and quartz retarders. A polymer retarder changes by less than 1% over a ±10° incidence angle.

The temperature sensitivity of laminated polymer retarders is about 0.04% per °C, allowing operation over moderate temperature ranges without significantly degrading retardance accuracy.