Preparation And Optical Properties Of Transparent Polycrystalline Zns Bulk Materials

The transmittance of chemical vapor deposition (CVD) ZnS can be effectively improved through the processing of hot isostatic pressing (HIP) in inert gas, especially in the waveband of visible light and near infrared. In general, the size of the particles of the polycrystalline ZnS bulk material can be increased after the processing of HIP. This change can definitely affect the optical properties and mechanical properties of the material. In this paper, a two-step method is applied to improve preparation of transparent polycrystalline ZnS bulk materials. The first step is the growth of polycrystalline ZnS through dynamic CVD. Then the grown polycrystalline ZnS bulk materials is annealed in inert gas at 800 similar to 900 degrees C for 10 similar to 50 h. Experimental results show that the optical properties and mechanical properties of the materials is significantly improved. The average transmission rate of the materials is over 74% in the wavebands 8 similar to 12 mu m and is over 70% in the mid-infrared 3 similar to 5 mu m. The absorption peak of the materials at 6 mu m attributed to Zn-H complex and S vacancy is obviously decreased. Furthermore, results of imaging experiments show that lenses made of the annealed transparent polycrystalline ZnS bulk materials has excellent performance in optical properties and modulation transfer function (MTF).