The potential application of high-power UV lasers as an illumination source has stimulated the study and the development of new materials with high refractive index as constituents for optical devices. As a wide band gap and high refractive index material, Sc2O3 has been explored for UV optical coating applications. The physical and optical properties of Sc2O3 films are strongly dependent upon the deposition method, growth conditions and some postdeposition treatment. Plasma ion assisted deposition (PIAD) is a well-known advanced deposition technique to deposit dense dielectric films with superior optical properties such as smoothness, low scatter, and environmental stability. This research work is to apply PIAD process to obtain homogenous and UV transparent Sc2O3 layers to be paired with SiO2 to prepare UV 266nm antireflection coatings. Higher bandgap materials require higher photon energies when absorbed by a material and converted to electron excitation which promotes a valence electron to the conduction band. This would result in higher laser damage threshold. The coating performance and UV laser induced damage threshold of these AR coatings made with Sc2O3 layered with SiO2 are compared with the coatings made with HfO2-SiO2 paired AR coatings. The Sc2O3-SiO2 paired coatings demonstrate a comparable low reflectivity to AR coatings using HfO2 as high index materials. Furthermore, it shows a higher UV laser damage threshold than HfO2-SiO2 paired AR coatings. Sc2O3 demonstrates its potential application through this research work as optical interference coatings for high power UV laser devices.
Ever since the human genome was first sequenced, scientists have been inspired by possibilities of using genomic information for medical research. In recent year, new generation sequencing platform to deliver complete genome sequence data with higher throughputs are to be built to conduct genomic studies on a large scale. This requires the development of a wide field multi-channel fluorescence imager system. The complexity of this optical system for human genome sequencing application would also have specific optical coating challenges. For the objective lens system, it requires selection of multiple glass types with normal and anomalous dispersions in order to successfully correct chromatic aberrations to diffraction-limited level over a broad wavelength spectrum. The challenge is anti-reflection (AR) coatings need to be coated over these multi-glass types with various refractive index from 1.43 to 1.8 and operate through an extended range of broad spectrum range. In addition, auto-fluorescence of optical components and coatings applied to the lenses are considered an isotropic generation of the secondary stray light inside the system. This is undesirable and should be minimized. This research work presents the AR coating design strategy to accommodate the multiple glass types in the lens system over a broadband application range and the investigation results of achieving low auto-fluorescence through material selection and coating process control.