The focus of a two-photon microscope is often degraded by inhomogeneities in the
refractive index within biological specimens. In this book it is shown for various
specimens, even for living zebrafish, that the resolution and the fluorescence signal of a
two-photon microscope can be substantially improved by using adaptive optics, i.e.
wavefront correction based on coherence-gated wavefront sensing (CGWS). The advantage
of using CGWS relies on the fact that the wavefront distortions are sensed by backscattered
instead of fluorescent light. Thus, neither photodamage nor photobleaching occurs and
wavefront distortions can be sensed in less than 1 microsecond with an accuracy of lambda/50, even in strongly scattering samples.
Furthermore, CGWS is thoroughly investigated for all relevant parameters affecting the
measurement process, such as coherence length, polarization of the light, density of
scatterers, and coherence-gate position.
The book is mainly addressed to experts in the field of optical physics and light microscopy.