Fig. 4From: Improvement of the detection efficiency calibration and homogeneity measurement of Si-SPAD detectorsScanning results for different z -positions using the PDM (Micro Photon Devices) detector. a, b Scan in front of and behind the front focal plane of the objective, i.e. predominantly Gaussian profiles with their fitting curves and c scan at the focal plane of the objective and therefore nearly rectangular profileBack to article page