Polarization microscopy: from ensemble structural imaging to single-molecule 3D orientation and localization microscopy

Optical contrasts in microscopy are sensitive to light polarization, whose interaction with molecular dipoles provides an important lever for probing molecular orientation. Polarization microscopy has evolved considerably during the last decade, integrating strategies ranging from traditional linear dichroism to single-molecule orientation and localization imaging. This review aims to provide a summary of concepts and techniques behind orientation and structural imaging at the molecular level, from ensemble microscopy in 2D to single-molecule super-resolution microscopy in 3D.