Corkscrew point spread function for far-field three-dimensional nanoscale localization of pointlike objects

We describe the corkscrew point spread function (PSF), which can localize objects in three dimensions throughout a 3:2 μm depth of field with nanometer precision. The corkscrew PSF rotates as a function of the axial (z) position of an emitter. Fisher information calculations show that the corkscrew PSF can achieve nanometer localization precision with limited numbers of photons. We demonstrate three-dimensional super-resolution microscopy with the corkscrew PSF by imaging beads on the surface of a triangular polydimethylsiloxane (PDMS) grating. With 99,000 photons detected, the corkscrew PSF achieves a localization precision of 2:7 nm in x, 2:1 nm in y, and 5:7 nm in z.