Chapter 11 Active and adaptive optics in confocal microscopy

Abstract

Publisher Summary This chapter discusses active and adaptive optics in confocal microscopy. It also explores the way radial polarization can be used both to enhance the axial component of the electric field in the focal plane and to generate a very finely focused spot of light. In both active and adaptive optics, it is important to be able to control the optical field incident on a high numerical aperture objective lens. An adaptive optical system permits both specimen–and system–induced aberrations to be measured and corrected. The key elements in an adaptive optics system are the wavefront sensor, which measures the (unwanted) aberration in an optical beam together with a wavefront correction element, which is able to introduce the appropriate amount of pre-aberration so as to cancel out the unwanted and restore diffraction-limited performance. Various methods are available (such as the use of deformable mirrors) to implement the wavefront generation element. A very general approach, based on the use of computer-generated holograms, leads to a very versatile system, which is able to generate beams of arbitrary phase, amplitude, and polarization.