title: Large-angle scattered light measurements for quantum-noise filter cavity design studies.
abstract: Optical loss from scattered light could limit the performance of quantum-noise filter cavities being considered for an upgrade to the Advanced Laser Interferometer Gravitational Wave Observatory (LIGO) gravitational-wave detectors. This paper describes imaging scatterometer measurements of the large-angle scattered light from two high-quality sample optics, a high reflector and a beamsplitter. These optics are each superpolished fused silica substrates with silica:tantala dielectric coatings. They represent the current state-of-the art optical technology for use in filter cavities. We present angle-resolved scatter values and integrate these to estimate the total scatter over the measured angles. We find that the total integrated light scattered into larger angles can be as small as 4 ppm.
authors.affiliation: Department of Physics, California State University Fullerton, Fullerton, California 92831, USA. fabianmagana@csu.fullerton.edu
authors.forename: Fabian
authors.initials: F
authors.lastname: Magaña-Sandoval
authors.forename: Rana X
authors.initials: RX
authors.lastname: Adhikari
authors.forename: Valera
authors.initials: V
authors.lastname: Frolov
authors.forename: Jan
authors.initials: J
authors.lastname: Harms
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Lee
authors.forename: Shannon
authors.initials: S
authors.lastname: Sankar
authors.forename: Peter R
authors.initials: PR
authors.lastname: Saulson
authors.forename: Joshua R
authors.initials: JR
authors.lastname: Smith