Review of “Adaptive Optics for Biological Imaging” edited by Joel A. Kubby

Book review Background Optical imaging systems, such as microscopes or telescopes, aim to provide as crisp and detailed a view as possible. Unfortunately, most devices do not achieve their full optical power due to aberrations that are introduced by the imaging system itself (e.g., the chromatic aberration introduced by a simple lens), in the object to be imaged (e.g., extensive scattering within individual cells), or in the intervening medium (e.g., atmospheric turbulence when imaging astronomical objects). As a result of these aberrations, the incoming wavefronts are distorted, resulting in blurred images. In the case of microscopy, aberrations result in reduced resolution both laterally and axially. In some cases, the aberrations are modest and simple to correct for with static optical elements. However, in most cases, the aberrations are strong, complex in nature, and/or highly dynamical and the loss in image quality incurred can be both dramatic and variable. Aberrations are so common that they have indeed limited the effective resolving power of microscopes and telescopes for centuries. A variety of remedial methods have been proposed against aberrations but none is as versatile and powerful as adaptive optics (AO) systems. These systems aim at actively controlling and correcting for aberrations, enabling normal imaging systems to reach their nominal power. The key element of an AO system is a “deformable mirror” that can be controlled to compensate the aberrations induced on the incoming wavefronts. The challenges of building an AO system are extremely serious. While the concept was introduced in the astronomical context over 60 years ago, the first on-sky partial experiments awaited the late 1970s and the first full operating system the late 1980s. Nowadays, AO is a mainstream part of modern astronomy: all existing and planned state-of-the-art telescopes have such a device and low-cost versions are being commercialized for small telescopes.