title: Optical transmittance measurement system for coated elements with low transmittance.
abstract: The low-transmittance elements required for a high power laser facility have stringent specifications about transmittance. To validate optic performance against specifications, a metrology system for transmittance is proposed. The system is composed of a laser source, an integrating sphere, a power meter, and four uncoated wedged glasses. A relative measurement method is adopted, which is that the surface reflectivity of uncoated glass is used as the reference to compare with the sample's transmittance. The systematic feature is that uncoated wedged glasses are applied to split and reflect beams, which not only avoid coating errors, but also make the two beam powers attenuate properly. Measurement results for a sample's transmittance are presented. Experiment and analysis show that the relative standard uncertainty (σ(T)/T) of measurement is 0.424%. This system is available for large-aperture elements.
authors.affiliation: The Advanced Optical Instrument Research Department, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an, China.
authors.forename: Hongyun
authors.initials: H
authors.lastname: Wang
authors.forename: Zhengshang
authors.initials: Z
authors.lastname: Da
authors.forename: Lili
authors.initials: L
authors.lastname: Liu
authors.forename: Juanning
authors.initials: J
authors.lastname: Zhao