Characterizing high-quality microscope objectives: a new approach

We present a novel technique for testing of the high quality microscope objective lenses. The characterization of the lens is achieved by using a point light source approximated by a 40 nm colloidal gold bead scatterer and simultaneously measuring the field distribution in the pupil plane (pupil function) and light intensity in the image plane (point spread function). Aberrations introduced by the lens are then expanded into Zernike polynomials. The proposed technique is particularly suited for measuring apodization and vignetting effects and allows for easy measurements of the off-axis aberrations.