title: Scanning metallic nanosphere microscopy for vectorial profiling of optical focal spots.
abstract: Recent years have witnessed fast progress in the development of spatially variant states of polarization under high numerical aperture focusing, and intensive exploration of their applications. We report a vectorial, broadband, high contrast and subwavelength resolution method for focal spot profiling. In this experiment, a 100 nm diameter gold nanosphere on a silica aerogel substrate is raster scanned across the focal spots, and the orthogonal polarization components can be obtained simultaneously by measuring the scattering far field in a confocal manner. The metallic-nanosphere-on-aerogel structure ensures negligible distortion to the focal spots, low crosstalk between orthogonal polarization components (1/39 in experiment), and a low level background noise (1/80 of peak intensity in experiment), while high contrast imaging is not limited by the resonance bandwidth.
authors.forename: Hui
authors.initials: H
authors.lastname: Yi
authors.forename: Jing
authors.initials: J
authors.lastname: Long
authors.forename: Hongquan
authors.initials: H
authors.lastname: Li
authors.forename: Xiaolong
authors.initials: X
authors.lastname: He
authors.forename: Tian
authors.initials: T
authors.lastname: Yang