  We propose a straightforward sample-based technique to calibrate the axial
detection in 3D single molecule localization microscopy (SMLM). Using
microspheres coated with fluorescent molecules, the calibration curves of
PSF-shaping- or intensity-based measurements can be obtained for any required
depth range from a few hundreds of nanometers to several tens of microns. This
experimental method takes into account the effect of the spherical aberration
without requiring computational correction.
