Characterization of 3D spatial resolution by imaging 300-nm polystyrene beads with RI of 1.5956 immersed in oil with RI of 1.5536. The mean permittivity images of beads show dense center and differential permittivity images resolve edges of the beads. The mean permittivity of the center bead is selected for Gaussian fits in x and z directions. The Gaussian fits are deconvolved with the physical size of the bead to measure the FWHM of the PSF in x and z .
