  The fast-growing field of soft matter research requires increasingly
sophisticated tools for experimental studies. One of the oldest and most widely
used tools to study soft matter systems is optical microscopy. Recent advances
in optical microscopy techniques have resulted in a vast body of new
experimental results and discoveries. New imaging modalities, such as nonlinear
optical microscopy techniques that were developed to achieve higher resolution,
enable soft matter research at length scales ranging from the molecular to the
macroscopic.
  The aim of this chapter is to introduce a variety of optical microscopy
techniques available to soft matter researchers, starting from basic principles
and finishing with a discussion of the most advanced microscopy systems. We
describe traditional imaging techniques, such as bright field and polarizing
microscopy, along with state-of-the-art three-dimensional (3D) imaging
techniques, such as fluorescence confocal and nonlinear optical microscopies.
Different approaches are discussed along with their applications in the study
of soft matter systems by providing typical examples.
