  Among the approaches in three-dimensional (3D) single molecule localization
microscopy, there are several point spread function (PSF) engineering
approaches, in which depth information of molecules is encoded in 2D images.
Usually,the molecules are excited sparsely in each raw image. The consequence
is that the temporal resolution has to be sacrificed. In order to improve
temporal resolution and ensure localization accuracy, we propose a method,
SH-CS, based on light needle excitation, detection system with single
helix-point spread function (SH-PSF), and compressed sensing (CS). Although the
SH-CS method still has a limitation about the molecule density, it is suited
for relatively dense molecules. For each light needle scanning position, an SH
image of excited molecules is processed with CS algorithm to decode their axial
information. Simulations demonstrated, for random distributed 1 ~ 15 molecules
in depth range of 4 {\mu}m, the axial localization accuracy is 12.1 nm ~ 73.5
nm. The feasibility of this method is validated by experimental data.
