Specialized Optical Properties - Microscope objectives often have design parameters that optimize performance under certain conditions. For example, there are special objectives designed for polarized illumination signified by the abbreviations P, Po, POL, or SF (strain-free and/or having all barrel engravings painted red), phase contrast (PH, and/or green barrel engravings), differential interference contrast (DIC), and many other abbreviations for additional applications. A list of several abbreviations, often manufacturer specific, is presented in Table 1. The apochromat objective illustrated in Figure 1 is optimized for DIC photomicrography and this is indicated on the barrel. The capital H beside the DIC marking indicates that the objective must be used with a specific DIC Wollaston prism optimized for high-magnification applications.