Devices and Techniques for Sensorless Adaptive Optics

Abstract

Additional information is available at the end of the chapter http://dx.doi.org/10.5772/53550 . IntroductionMinimizinμ the aberrations is the basic concern oλ all the optical system desiμners. For this purpose, a larμe amount oλ work has been carried out and plenty oλ literature can be λound on the subject. Until the last twenty years, the larμe majority oλ the optical desiμn was related to static optical systems, where several opto-mechanical parameters, such as reλractive index, shape, curvatures, etc. are slowly time dependent. In these systems, simple mechanisms can be adopted to chanμe the relative position oλ one or more optical elements λor example, the secondary mirror oλ many astronomical telescopes , or sliμhtly modiλy their shape and curvature as in some synchrotron beamlines, where some optical surλaces are mechanically bent to compensate deλocusinμ. In the last years, a new type oλ optical systems, that we may call dynamical, have heavily occupied the interest oλ optical desiμners, openinμ the possibility oλ workinμ also in situations where the system environment varies rather quickly with time, either in a controlled or not-controlled way. For this class oλ optical systems adaptive optics "O with a closed loop control system has to be implemented. The correction oλ dynamical systems was predicted by "abcock in the [ ] and, then, the λirst prototypes were realized in the early s with the purpose oλ satellite surveillance and launchinμ hiμh power laser beams trouμh the atmosphere [ ]. The most known scientiλic applications oλ closed loop correction by means oλ "O is the acquisition oλ astronomical imaμes in μround-based telescopes [ ] and in-vivo imaμinμ oλ cone photoreceptor mosaic by "O enhanced Fundus Cameras [ ]. In astronomy, to remove the so called seeinμ eλλect, the star liμht twinklinμ due to local dynamic variations oλ the atmospheric density in the air column above the telescope, it is necessary to have the real time knowledμe oλ the waveλront oλ the observed object. This can be realized, λor instance, by means oλ a Shack-Hartmann waveλront sensinμ device coupled to a dedicated λast alμorithm which returns the mathematical description oλ the waveλront aberration, typically throuμh a Zernike series decompo-

Adaptive-optics SLO imaging combined with widefield OCT and SLO enables precise 3D localization of fluorescent cells in the mouse retina

“…This is often used in aberration-dependent vision testing [24] or image quality-based aberration correction [25]. In our AO-SLO, similar to other AO-based imaging systems, this feature was used to actively shift the axial focus position of the imaging beam by adding a prescribed defocus term to the AO reference control, modifying the shape of the deformable mirror [26].…”

Advanced adaptive compensation system for free-space optical communications

“…Sensor-less systems perform the wave-front optimization with several iterations that require continuous sensing of the metric as feedback. Sensor-less systems can be classified into stochastic, and sequential imagebased methods [3]. The stochastic approach is generally based on blind algorithms that start the optimization with a random set of variables, applying an iterative approximation of the best solution.…”

“…Hence, the optimization of each mode can be done with three acquired images by interpolating the result of a quadratic function, which is the rms spot radius [3]. The following sections offer an overview of these techniques.…”

“…En la utilización o cita de partes x 2. 3 6.10 Camera input power distribution between the speckles for different turbulent regimes. The cumulative power of the speckles sum up 80% of the total input power.…”

“…132 6.12 (a) Continues BER curves are calculated with Eq. (2.99) and consider the measured power vectors for the scenarios D/r 0 = [3,5,10] assuming constant shot noise. The dashed curve represents the shot-noise limited ideal performance and the dotted curve the back-to-back reference curve of the receiver.…”