Design, fabrication and evaluation of anti-reflection films coated on LYSO scintillators

Surface treatment method affects optical properties of scintillator which is a critical component of PET detector module. We designed and fabricated the high transmittance antireflection (AR) films for Lutetium-yttrium oxy-orthosilicate (LYSO) crystals with different combinations of the exact composition, thickness, and number of layers. It is feasible to adjust the reflectivity of the coating to produce crystal arrays with desired optical properties.The simulation results indicated that coating films constructed with MgF 2 , TiO 2 , HfO 2 significantly increase the transmittance of coupling surfaces. Based on the method of multilayer dielectric film stacking, we optimized an AR film with 11 layers, which matches the emission spectrum of LYSO scintillator. According to the design and simulation results, the samples show desirable optical performance. We have investigated the feasibility of applying AR coatings directly to the crystal strip to increasing its light output across the entire emission spectrum (360 nm to 620 nm).We concluded that AR coatings designed in this study can be applied to scintillators to improve the performance of PET detector, which is mostly characterized by increasement of light yield of LYSO crystal and improvements of energy and timing performance.