LAUSR

Optical diffraction limits resolution in visible spectrum to 200 nm in the lateral dimension (x-y) and 500 nm in axial dimension (z). Recent advances in engineering properties of fluorescent proteins and dyes have enabled nanometer scale visualization by localizing sparse ensembles of photoswitchable/photoactivatable molecules through many frames. A final image is formed by combining locations of all the molecules to form a “super-resolution image”. The family of techniques is known as single-molecule localization microscopy (SMLM)[1]. Although SMLM enables high precision imaging of 10-20 nm in the lateral dimension, it lacks axial (z) resolution, especially near focus. One method to extract axial information uses an astigmatic lens to distort the point spread function, thereby enabling extraction of a limited amount of 3D information. Unfortunately, this approach has a limited depth capability of only about 500-700 nm.