Optical properties visible light transmittance

A similar two-step process, i.e., HP followed by HIP, has been used to prepare optically transparent poly crystalline spinel ceramics [193, 195]. The elfect of HP temperature on optical properties of the final ceramics HIP sintered at 1900 °C for 1 h under a pressure of 189 MPa was studied. Three HP temperatures, 1400, 1450, and 1500 °C in vacuum of 10 Pa for 1 h at 50 MPa, were examined. The sample HP pre-sintered at 1400 °C had the maximum transmittance of over 60 and 70 % in the UV-visible and near-IR wavelength regions, respectively. The light transmittance was well correlated with the microcracked grain boundary surface area per unit volume of the samples. 

PVDF films up to 100-125 pm are transparent to translucent when the molten polymer is quenched in water to minimize crystallization. The transmittance spectra of PVDF in the ultraviolet, visible, and near-infrared light regions are shown in Fig. 13.102. Infrared absorbance of PVDF is given in Fig. 13.103. Optical properties of homopolymer PVDF films and sheets produced by different fabrication techniques are summarized in Table 13.41. 

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