Michael Lloyd-Hart

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We i n troduce adaptive optics as a technique to improve images taken by ground-based telescopes through a turbulent blurring atmosphere. Adaptive optics rapidly senses the wavefront distortion referenced to either a natural or laser guidestar, and then applies an equal but opposite proole to an adaptive mirror. In this paper, we summarize the application(More)
Adaptive optics with a sodium resonance laser guide star was used at the Multiple Mirror Telescope (MMT) in 1996 April to image the core of the globular cluster M13 (NGC 6205). A 23″ field was recorded in the K s-band with image resolution of 0″.51, when the uncorrected resolution was 0″.72. Global tilt, not sensed by the laser, was measured from the image(More)
We show in benchtop experiments that wave-front phase estimation by phase diversity can be significantly improved by simultaneous amplitude estimation. Processing speed, which will be important for real-time wave-front control applications, can be enhanced by use of small-format detectors with pixels that do not fully sample the diffraction limit. Using an(More)
We present a new way to sense atmospheric wave-front phase distortion. Short collimated pulses of laser light at ~350nm are projected from a small auxilliary telescope. Rayleigh scattering from each pulse is recorded over a wide range of height through the main telescope aperture in a continuous sequence of fast video frames by a detector conjugate to(More)
The adaptive secondary for the MMT is the first mirror of its kind. It was designed to allow the application of wavefront corrections (including tip-tilt) directly at the secondary mirror location. Among the advantages of such a choice for adaptive optics operation are higher throughput, lower emissivity, and simpler optical setup. Furthermore, this(More)
An adaptive optics system is being built for the 6.5 m MMT conversion telescope on Mt. Hopkins for diffraction-limited observations in the near infrared. At the heart of the system is a deformable secondary mirror which introduces corrections to the optical wavefront. By compensating these errors at the telescope's secondary, the system has been optimised(More)
The adaptive optics (AO) system for the 6.5 m MMT conversion telescope is the first to compensate the aberrated wavefront at the telescope's secondary mirror. This approach has unique advantages in terms of optical simplicity, high throughput and low emissivity. Its realization presents many technical challenges, which have now been overcome. The deformable(More)
We investigate the performance of a general multiconjugate adaptive optics (MCAO) system in which signals from multiple reference beacons are used to drive several deformable mirrors in the optical beam train. Taking an analytic approach that yields a detailed view of the effects of low-order aberration modes defined over the metapupil, we show that in the(More)
By taking advantage of the spatial and temporal correlation of the phase of the atmospherically-aberrated optical wavefront, we show in extensive computer simulations that the effect of the time delay in the servo loop of an adaptive optics system can be greatly reduced. Further work based on open-loop Shack-Hartmann sensor data from a 1.6-m telescope(More)