A Study On The Coloration Effects Of The Three Optical Thin Films Under Proton And Electron Irradiation

Three typical enhancing transparence films of MgF₂, ZrO₂, and Al2O3 were tested under the irradiation of the 60keV electrons and protons, which were plated on quartz substrate by means of physical vacuum deposition, to investigate the degradation in transparence with variation of irradiation influence using charged particles radiation equipment. Based on the theory about color centers produced by irradiation in optical materials, the amount of absorption bands and corresponding color centers, of which are formed inside each film under irradiation of electrons and protons, were determined through analyzing absorption spectra and photoluminescence spectra. The evolvement of typical absorption bands with irradiation influence was analyzed employing a mathematical fitting method.The irradiation of electrons and protons showed a coloration effect on the tested materials and changed the spectral property, which had no influence on the crystal structure.After the proton irradiation, the following results were obtained. There are four optical absorption bands forming in MgF₂ film near 260nm, 320nm, 370nm, 400nm, and 470nm, corresponding to the F center and three deferent F₂ centers, respectively. Five absorption bands are generated in ZrO₂ film near 210nm, 260nm, 290nm, 370nm, and 510nm, contributing to the E' center, the H₂ center, the intrinsic defect center, the F center and the F⁺ center, respectively. Five absorption bands are produced in Al2O3 film near 197nm, 250nm, 280nm, 350nm, and 450nm, assigning to the F center, the F⁺ center, the F₂ center, the F³⁺ center, and the F²⁺ center, respectively. Six absorption bands are produced in anti-reflection film system of lens near 370nm, 400nm, 450nm, 490nm 580nm and 750nm, responding to the F₂ center of MgF₂, the vacancy center of Al2O3, the F²⁺ center of Al2O3, the F⁺ center of ZrO₂, the F²⁺ center of Al2O3 and the absorption band of Al2O3The analyzed results from the electron irradiation test were described as followed. There are five absorption bands forming in MgF₂ film near 230nm, 260nm, 290nm, 450nm, and 490nm. Among those, the bands near 260nm and 490nm may respond to the F center and the HD center, while the other three bands are contributing to three types of F₂ centers. Four absorption bands are generated in ZrO₂ film near 210nm, 240nm, 280nm, and 340nm, assigning to the E' center, the H2 center, the F₂ center, the intrinsic defect center, and the F center, respectively. Three absorption bands are produced in Al₂O₃ film near 195nm, 230nm, and 390nm, responding to the F center, the F+ center, and the vacancy center, respectively. Four absorption bands are produced in anti-reflection film system of lens near 370nm, 400nm, 440nm and 490nm, responding to the F₂ center of MgF₂, the vacancy center of Al₂O₃, the F²⁺ center of Al₂O₃, and the F+ center of ZrO₂, respectively.The formation and accumulation of each color center depend on not only materials and the type of charged particles but also the energy of irradiation. The results showed that the concentration of color center is increased with increasing irradiation influence, while there are transitions among some associated centers during irradiation.