Optical properties of Teflon® AF amorphous fluoropolymers

The optical properties of three grades of Teflon (R) AF-1300, AF1601, and AF2400-were investigated using a J.A. Woollam VUV-VASE spectroscopic ellipsometry system. The refractive indices for each grade were obtained from multiple measurements with different film thicknesses on Si substrates. The absorbances of Teflon (R) AF films were determined by measuring the transmission intensity of Teflon (R) AF films on CaF2 substrates. In addition to the refractive index and absorbance per cm (base 10), the extinction coefficient (k), and absorption coefficient (alpha) per cm (base e), Urbach parameters of absorption edge position and edge width, and two-pole Sellmeier parameters were determined for the three grades of Teflon (R) AF. We found that the optical properties of the three grades of Teflon (R) AF varied systematically with the AF TFE/PDD composition. The indices of refraction, extinction coefficient (k), absorption coefficient (alpha), and absorbance (A) increased, as did the TFE content, while the PDD content decreased. In addition, the Urbach edge position moved to a longer wavelength, and the Urbach edge width became wider. c 2008 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.2965541]