It™s often necessary to alter or manipulate the source™s polarization. For example, a reflective phase retarder converts linear to circular polarization and improves the laser cutting quality. (For reflective phase retarders, please see Phase Retarders.) However, most polarization altering devices -- the reflective phase retarder and waveplates -- are very wavelength sensitive and offer only narrowband, or single wavelength operation.
The Fresnel prisms and rhombs described on this page utilize the principle that when light undergoes total internal reflection, there is a relative phase change between the s and p polarization components. This effect is only weakly dependent on wavelength (Figure 1). Thus, these components are ideal for those working at either multiple distinct wavelengths or with broadband sources in the 8 to 12 µm region.
By manipulating the rhomb™s geometry, devices which produce quarter-wave, half-wave, or virtually any required retardation can be constructed. Please contact a II-VI sales representative with your design requirements.