Measuring large numerical apertures by imaging the angular distribution of radiation of fluorescing molecules.
Exact knowledge of the numerical aperture is crucial in many applications using high-aperture objectives such as confocal microscopy, optical trapping, or advanced sub-wavelength imaging methods. We propose and apply a precise and straightforward method for measuring this fundamental parameter of microscope objectives with numerical apertures above unity. Our method exploits the peculiarities of the fluorescence emission of molecules at a glass/air interface.
Dai
Luru
L
Gregor
Ingo
I
von der Hocht
Iris
I
Ruckstuhl
Thomas
T
Enderlein
Jörg
J