Fig. 1. (a) Angular distribution of emission into glass for isotropically oriented molecules in glass at an air/glass interface when excited by light circularly polarized within the plane of the interface. Emission maximum occurs at the angle of total internal reflection (TIR), indicated by light-red lines. (b) Intensity distribution of fluorescence within the back focal plane of an objective as a function of the distance ρ from the optical axis divided by the focal distance f of the objective. The vertical light-red lines show the position of TIR.

Fig. 2. Principal scheme of the experimental set-up used for imaging the intensity distribution of fluorescence in the back focal plane of the objective. The imaging lens images the back focal plane of the objective onto the CCD camera. In the realized experimental set-up, this imaging was achieved by using the microscope’s tube lens (not shown) plus and additional lens.

Fig. 3. (a) Measured intensity distribution in the back focal plane for the Olympus UApo/340 40× objective with nominal NA of 1.15. The barely visible black circle at the edge of the illuminated area is the determined out NA-determined cut-off of fluorescence collection, the cyan circle marks the position of the fluorescence discontinuity at the TIR-angle. (b) Same as Fig. 3(a), but for the Olympus PlanApo 60× objective with nominal NA of 1.4.