Preparation of CVD ZnS polycrystalline material for infrared optics

Chemical vapor deposited zinc sulfide (CVD ZnS) is a long-wave infrared material with excellent optical and mechanical properties. CVD ZnS windows and domes with bulk size up to 250mm×15mm were prepared by chemical vapor deposition and hot isolated pressing. Technical issues for preparation of CVD ZnS, including chemical reaction, hot isolated pressing, control of flow pattern and equipment, are discussed. Optical and mechanical properties of CVD ZnS were measured and analyzed. The full-band transmittance of the samples is close to the theoretical value of ZnS, the inhomogeneity of refractive index at 0.6328 μm is less than 2×10-5, the bulk absorption at 1.06μm is 2×10-3cm-1 and bending strength is 104MPa. The result indicates that the quality of CVD ZnS is similar to that of American products.