Measuring the complex forward-scattering amplitude of single particles by self-reference interferometry: CAS-v1 protocol

Abstract

Theoretical and experimental bases are given for measuring the complex forward-scattering amplitude of single particles through self-reference interferometry. Our analyses reveal the nondimensional parameters that primarily control the accuracy and resolution of the complex amplitude data. We propose a measurement protocol, Complex Amplitude Sensing version 1 (CAS-v1), for effectively utilizing self-reference interferometry as a universal tool for inline measurements of the complex forward-scattering amplitude of single sub- and super-micron particles suspended in a fluid flow. The CAS-v1 protocol will facilitate applications of self-reference interferometry to real-time particle measurements in the industrial, biomedical, and environmental sciences.