We employ a novel framework for information-optimal
microscopy
to design a family of point spread functions (PSFs), the Tetrapod
PSFs, which enable high-precision localization of nanoscale emitters
in three dimensions over customizable axial (<i>z</i>) ranges
of up to 20 μm with a high numerical aperture objective lens.
To illustrate, we perform flow profiling in a microfluidic channel
and show scan-free tracking of single quantum-dot-labeled phospholipid
molecules on the surface of living, thick mammalian cells