Research director, Laboratory of glasses and ceramics, Institute of Chemistry, University of Rennes I/CNRS, France

Biography: Xiang-Hua Zhang is Research director of the CNRS (French National center for scientific research). He got his bachelor in Zhejiang University, China in 1983 and PhD degree in University of Rennes I, France in 1988. He worked in the laboratory of glasses and ceramics, a joint laboratory CNRS-University of Rennes I until 1996 when he left to find the Umicore IR glass company, the world leader for molded chalcogenide glass optics. He came back to the laboratory in 2002 and became the director of this laboratory in 2012. He is mainly specialized in chalcogenide glasses and ceramics for thermal imaging. He is co-inventor of 17 patents and author or co-author of more than 310 peer-reviewed publications.

Speech Title: Infrared optical materials for thermal imaging

Abstract: Thermal imaging is more and more widely used for commercial and defence applications because it provides additional information to visible images. Thermal imaging is generally realised in the infrared region between 8-12 µm, corresponding to an atmospheric window and also to the maximum thermal emission of objects at room temperature. There are however very few materials transparent in this spectral region. Germanium, a rare and expensive element, has very interesting optical properties with very high refractive index and very low chromatic dispersion. Another frequently used material is the polycrystalline ZnSe produced with the Chemical Vapour Deposition technique. These expensive materials associated with complex fabrication method for optics are often inappropriate for commercial applications such as applications for mobile phone and for car driving assistance. For extending the application domain of thermal imaging, the main challenge is to lower the cost of the infrared detectors and of infrared optics.

Chalcogenide glasses are glasses based on sulphur, selenium and tellurium. They have been intensively studied mainly due to its large optical transmission window from the visible to far infrared region including the 8-12 µm region. They can be easily moulded into complex optical elements.

In this talk, different infrared transmitting materials and optics will be presented and compared.

Keywords: Thermal imaging, chalcogenide glasses, infrared optics