Fig. 3: Scanning confocal microscopy with a 2nd-order lens.
a Sketch for optical setup of SCM in a transmission mode. PMT: photomultiplier tube. b–e Double slits (b) and their images by using coherent bright-field microscope (c), traditional objective-based SCM (d) and our high-order-lens-based SCM (e). The double slits have the center-to-center distances of 180 nm (I), 190 nm (II), 200 nm (III), 210 nm (IV), 220 nm (V) and 230 nm (VI). f Line-scanning intensity profiles of images with different microscopies. g Measured valley-peak ratios for SCM images based on traditional objective (black dots) and our high-order lens (red asterisks). The valley-peak ratio γ is defined by using γ = Ix=0/I|x|=D/2, where Ix=0 and I|x|=D/2 denote the intensity values at the x = 0 (the symmetric axis of double slit) and |x | =D/2 (the center of each slit), respectively. The error bars are generated because the different I+|x| and I-|x| are achieved in experiment, as observed in (f). h–k Complex nano-object bird (h) and its images by using coherent bright-field microscope (i), traditional objective-based SCM (j) and our high-order lens-based SCM (k). The zoomed-in images at the wing region (labeled in the red boxes) are shown in the lower panels.
