Figure 7: Microsphere imaging properties analyses.
From: Scanning superlens microscopy for non-invasive large field-of-view visible light nanoscale imaging
(a) Schematic showing the experimental set-up used to study the distance (Δz) between the microsphere apex and the samples (Blu-ray disc) on microsphere imaging properties. The inset shows the image stack recorded during scanning. The left schematics in b and c show two different illumination conditions: coaxial illumination; and partial and inclined illumination. The right images in b and c show the illumination conditions detected during the vertical scanning of an optical beam profiler around the objective focus, where θ is the incline angle of the incident light focused using a × 50 (numerical aperture=0.6) objective. (d,e) Cross-sections of the images recorded during PZT scanning, as shown in the inset of a, under different illumination conditions. (f–i,j–m) Super-resolution images corresponding to the specific positions marked in d and e, respectively. (n) Relationship between Δzmax and the microsphere diameter, where Δzmax is the maximum distance that allows for imaging, that is, the structure on sample cannot be observed through the microsphere superlenses as Δz exceeds Δzmax. The incline angle is set to ∼64° for partial and inclined illumination. (o) The influence of the inclined angle (θ) on Δzmax. The microsphere diameter is ∼60 μm in these measurements. Scale bars, 1 μm (f–m).
