 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 ( z ) ranges 
 of up to 20 m 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 . 
Supplementary Material