Comparison between a model-based and a conventional pyramid sensor reconstructor

Abstract

A model of a non-modulated pyramid wavefront sensor (P-WFS) based on Fourier optics has been presented. Linearizations of the model represented as Jacobian matrices are used to improve the P-WFS phase estimates. It has been shown in simulations that a linear approximation of the P-WFS is sufficient in closed-loop adaptive optics. Also a method to compute model-based synthetic P-WFS command matrices is shown, and its performance is compared to the conventional calibration. It was observed that in poor visibility the new calibration is better than the conventional.

Virtual pyramid wavefront sensor for phase unwrapping

“…Let us imagine that the wrapped phase, φ w (x, y) (experimentally obtained in a PS-PDI when aberrations were induced with a deformable mirror) defined in the interval [-π π] within a circular pupil, P(x, y) be located at the back focal plane of a lens with a focal length of 1 m (physically not present) that focusses light onto a pyramidal prism (physically not present) with its phase, T(X, Y) [16,18] as illustrated in Fig. 1.…”

Extreme adaptive optics simulations for EPICS

“…The pyramid sensors, classical PWFS and RS, have shown to have excellent sensitivity, but low dynamical range [3]. The classical PWFS has less optical components compared to RS, but it suffers from diffraction effects deteriorating its performance [4]. The third sensor, MODS, has been introduced to increase the dynamical range of pyramid sensors while maintaining many beneficial properties of PWFS.…”

Analysis on measured signal retrieval approaches in non-modulation pyramid wavefront sensor

“…As a result, RMS and PV of this phase screen equal respectively to 1.14λ and 5.6λ. The closed-loop correction operates by using the linear reconstruction theory 11 and using the last three approaches to obtain the measurement signals. A liquid-crystal spatial light modulator (LCSLM) is acted as a wavefront corrector.…”

“…There are four choice of the normalization factor: (1) The product of average intensity and a factor at the input pupil 9,10 . (2) The average of total energy at the CCD detector 11,12 . (3) The averaging total energy in the effective image of pupil plane detected by the CCD 8 .…”