Transport of intensity equation: a tutorial

Phase retrieval has recently been experimentally demonstrated, using the irradiance transport equation. We show that this equation provides a unified description for incoherent wavefront sensing methods, bringing new insights and opening new prospects in this area.

Wavefront sensing and the irradiance transport equation

A new method has been developed for testing the optical quality of ground-based telescopes Aberrations are estimated from wideband long-exposure defocused stellar images recorded with current astronomical CCD cameras An iterative algorithm is used that simulates closed-loop wave-front compensation in adaptive optics Compared with the conventional Hartmann test, the new method is easier to implement, has similar accuracy, and provides a higher spatial resolution on the reconstructed wave front It has been applied to several astronomical telescopes and has been found to be a powerful diagnostic tool for improving image quality

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Wave-front reconstruction from defocused images and the testing of ground-based optical telescopes

Interferogram Analysis For Optical Testing, Second Edition

Spatially Resolved Images of Titan by Means of Adaptive Optics

A new wavefront sensing method based on local wavefront curvature measurements rather than tilt measurements is investigated. Performances are compared to that of a Shack-Hartmann sensor. Examples of experimentally reconstructed wavefronts are presented and several applications are discussed.

Curvature Sensing: A New Wavefront Sensing Method

Results recently obtained for the use of the curvature-sensing method as a substitute for slope sensing in optical wavefront reconstruction, using long-exposure CCD images of the beam cross-section on either side of the telescope focal plane. A program based on the solution to the Poisson equation is then applied in order to reconstruct the wavefront. Relative to the existing Hartmann sensing methods, curvature-sensing yields sensitivity comparable to that of the Shack-Hartmann test. Additional optics and reference plane-based calibration are obviated. Tests of the new method on an 88-inch Ritchey-Chretien telescope have yielded a map of residual wavefront errors as a solution of the Poisson equation.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Testing of telescope optics: a new approach

In this paper we describe the active optics system of the WIYN 3.5 meter telescope put into operation in the spring of 1995 on Kitt Peak, Arizona. The active optics system provides real time collimation of the telescope and optical figure control of the primary mirror. The individual subsystems are first described. These include the wavefront curvature sensing technique, the support and articulation of the secondary mirror, the control of the primary mirror figure and rigid body motion, and the mechanics and electronics used for controlling and monitoring the optics. Algorithms for the complete loop are then discussed. This involves mapping coma terms used to actively correct the collimation, while residual phase errors are corrected by active control of the forces supporting the primary mirror. In the next section we compare two operational modes: open loop using mapped collimation and optical figure corrections, and closed loop using feedback from the wavefront sensor directly. Finally, preliminary stellar images obtained with the actively controlled telescope are presented.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

WIYN telescope active optics system

The concept of curvature sensing and compensation in adaptive optics is investigated by means of a computer simulation. Satisfactory correction is observed when the signal from a 13 element sensor is directly applied to a simulated membrane mirror.

Nicolas A. Roddier

Papers

Curvature Sensing: A New Wavefront Sensing Method

Testing of telescope optics: a new approach

WIYN telescope active optics system

Curvature sensing and compensation: a computer simulation.