OPRA Setup. The laser emitting at 488nm passes a clean-up (lens L1 and L2 with appending focal length f1=50mm; f2=100mm) and is directed to a dichromatic beam splitter (BS1, detection wavelength bigger than 505nm). The scan unit in detail is shown in the inset. Here two y-scanning-mirrors (SMY) are used to project the spot to the rotation axes of the x-scanning-mirror (SMX, 15 kHz). After the scanning unit the beam passes a second beam expander and is directed to the objective. The returning fluorescent light is descanned and separated from the excitation light using the dichromatic beam splitter (BS1). After descanning the fluorescent beam is expanded by a factor of two (f4=200mm; f5=400mm). The adjustable detection pinhole between the lenses L4 and L5 can be used to achieve confocal sectioning (not in measurements). After the expansion the beam is rescanned using the same scanning system and projected via the lens L6 (f6=200mm) to the camera. To compare the images with a widefield setup an excitation light source, the optional (opt.) lenses L7, and a dichromatic beam splitter (BS2) were added in this configuration, while the scanner does not move and the detection pinhole is removed.