The Next Dimension: Digital Holography for 3D Interferometric Scattering

We provide detailed experimental guidelines for implementing digital holography in the context of high-sensitivity interferometric scattering (iSCAT)-based nanosizing applications. Our approach relies on interferometry via the highly versatile off-axis implementation of digital holography, which offers key advantages over more traditional strategies. After a brief theoretical discussion of off-axis holography and its differences and similarities with iSCAT, typical experimental implementations and digital data-processing steps are presented. Key experimental parameters and strategies to achieve optimal performance are also highlighted. Following these experimental aspects, we focus on digital postprocessing routines that enable digital refocusing and 3D particle tracking as well as pupil function aberration correction. We then conclude with a few examples highlighting the broad applicability of digital holography for nanosizing and particle characterization applications, as well as an outlook for future applications.