Simple broadband implementation of a phase contrast wavefront sensor for adaptive optics.

The most critical element of an adaptive optics system is its wavefront sensor, which must measure the closed-loop difference between the corrected wavefront and an ideal template at high speed, in real time, over a dense sampling of the pupil. Most high-order systems have used Shack-Hartmann wavefront sensors, but a novel approach based on Zernike's phase contrast principle appears promising. In this paper we discuss a simple way to achromatize such a phase contrast wavefront sensor, using the pi/2 phase difference between reflected and transmitted rays in a thin, symmetric beam splitter. We further model the response at a range of wavelengths to show that the required transverse dimension of the focalplane phase-shifting spot, nominally lambda/D, may not be very sensitive to wavelength, and so in practice additional optics to introduce wavelengthdependent transverse magnification achromatizing this spot diameter may not be required. A very simple broadband implementation of the phase contrast wavefront sensor results.

[1]  Emil Wolf,et al.  Principles of Optics: Contents , 1999 .

[2]  James D. Phillips,et al.  Beamsplitters for astronomical optical interferometry , 1995, Defense, Security, and Sensing.

[3]  R. Dekany The Palomar Adaptive Optics System , 1996 .

[4]  J. Hardy,et al.  Adaptive Optics for Astronomical Telescopes , 1998 .

[5]  Michael K. Giles,et al.  Focal plane masks in adaptive optics systems , 1999, Optics & Photonics.

[6]  Eric E. Bloemhof,et al.  Palomar adaptive optics project: status and performance , 2000, Astronomical Telescopes and Instrumentation.

[7]  E. W. Justh,et al.  Adaptive optics with advanced phase-contrast techniques. I. High-resolution wave-front sensing. , 2001, Journal of the Optical Society of America. A, Optics, image science, and vision.

[8]  E. W. Justh,et al.  Adaptive optics with advanced phase-contrast techniques. II. High-resolution wave-front control. , 2001, Journal of the Optical Society of America. A, Optics, image science, and vision.

[9]  Eric E. Bloemhof,et al.  Design considerations for a novel phase-contrast adaptive-optic wavefront sensor , 2002, SPIE Optics + Photonics.

[10]  Michael K. Giles,et al.  Closed-loop phase-contrast adaptive optics system using liquid crystal phase modulators: experimental results , 2002, Optics + Photonics.

[11]  J. K. Wallace,et al.  Phase-contrast wavefront sensing for adaptive optics , 2004, SPIE Optics + Photonics.