Many adaptive optics systems rely on a wavefront sensor (WFS) to sense the aberrations in an incoming wavefront. The required corrections are determined and applied by the wavefront corrector - often a deformable mirror (DM). We wish to develop a wavefront sensor-less correcting system, as derived from the original adaptive optics system of Muller and Buffington[1]. In this experiment we apply commands to a corrective element with adjustable segments in an attempt to maximise a metric which correlates to image quality. We employ search algorithms to find the optimal combination of
actuator voltages on a DM to maximise a certain sharpness metric. The "sharpness" is based on intensity measurements taken with a CCD camera. It has shown [2] that sharpness maximisation, using the Simplex algorithm[3], can minimise the aberrations and restore the Airy rings of an imaged point source. The results are repeatable and so-called "blind" correction of the aberrations is achieved. This paper demonstrates that the technique can be applied to extended objects which have been aberated using a Hamamatsu SLM to induce aberrations. The correction achieved using various search algorithms
are evaluated and presented.
The original proposal of wavefront-sensorless aberration correction was suggested by Muller and Buffington[1]. In this technique we attempt to correct for wavefront aberrations without the use of conventional wavefront sensing. We apply commands to a corrective element with adjustable segments in an attempt to maximise a metric which correlates to image quality. We employ search algorithms to find the optimal combination of actuator voltages on a DM to maximise a certain sharpness metric. The "sharpness" is based on intensity measurements taken with a CCD camera. It has been shown that sharpness maximisation, using the simplex algorithm, can minimise the aberrations and restore the Airy rings of an imaged point source. This paper demonstrates that the technique can be applied to extended objects which have been aberrated using a Hamamatsu SLM to induce aberrations. The correction achieved using various search algorithms are evaluated and presented.
A key component of any adaptive optics system (AO) for the correction of wavefront aberrations, is the wavefront sensor(WFS). Many systems operate in a mode where a WFS measures the aberrations present in the incoming beam. The required corrections are determined and applied by the wavefront corrector - often a deformable mirror (DM). We wish to develop a wavefront sensor-less correcting system, as derived from the original adaptive optics system of Muller and Buffington. In this experiment we employ a method in which a correcting element with adjustable segments is driven to maximise some function of the image. We employ search algorithms to find the optimal combination of actuator voltages to maximise a certain sharpness metric. The “sharpness” is based on intensity measurements taken with a CCD camera. Results have been achieved using a Nelder-Mead variation of the Simplex algorithm. Preliminary results show that the Simplex algorithm can minimise the aberrations and restore the Airy rings of the imaged point source. Good correction is achieved within 50-100 iterations of the Simplex algorithm. The results are repeatable and so-called “blind” correction of the aberrations is achieved. The correction achieved using various sharpness algorithms laid out by Muller and Buffington are evaluated and presented.
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