Numerical model of microsphere-assisted CSI and methodology to study the resolution enhancement. (IMAGE)
Caption
a) Schematic representation of a high NA microsphere-assisted coherence scanning interferometer. b) Intensities of exemplary FEM simulations of the interaction between vertical incident light and the surface combined with a microcylinder for different material and wavelength setups. The different setups are used to study influences of various physical effects occurring in the interaction on CSI measurement results. c) Simulated CSI (NA=0.9) results (called interferograms) obtained from a dielectric plane mirror, a phase grating with period length 300 nm and the same grating shifted laterally by the half of the period length. As shown in the magnified area, the grating profile can be obtained in the focal plane of the sphere. d) Simulated interferogram from a grating with 300 nm period length obtained by CSI with NA=0.52. Note that according to the Abbe resolution limit in air, this grating should not be resolved. The middle figure shows grating profiles reconstructed by envelope (env) and phase (ph) evaluation for the grating and its inverse (laterally shifted by half period length). As shown, the grating is obviously resolved due to the assistance of the microcylinder. The right figure displays the difference of the grating profile and the inverse one. The standard deviation of this difference can be considered as a quantity for the resolution and is zero if the grating is not resolved.
Credit
by Tobias Pahl, Lucie Hüser, Sebastian Hagemeier and Peter Lehmann
Usage Restrictions
Credit must be given to the creator.
License
CC BY