AOA Xinetics (AOX) has been at the forefront of Deformable Mirror (DM) technology development for over two
decades. In this paper the current state of that technology is reviewed and the particular strengths and weaknesses of the
various DM architectures are presented. Emphasis is placed on the requirements for DMs applied to the correction of
high-energy and high average power lasers. Mirror designs optimized for the correction of typical thermal lensing effects
in diode pumped solid-state lasers will be detailed and their capabilities summarized. Passive thermal management
techniques that allow long laser run times to be supported will also be discussed.
The design of the Southern African Large Telescope (SALT), which is based closely on the Hobby-Eberly Telescope (HET) at the University of Texas but includes advances incorporating lessons learned from HET, is briefly reviewed. The flowdown of requirements from the optical error budget to the primary mirror control subsystems is presented. The techniques and algorithms used by the Center of Curvature Alignment Sensor (CCAS) to measure segment tilt and piston and estimate the global radius of curvature of the primary are discussed in detail. The steps in the process that allows CCAS to capture and identify segments misaligned by more than 70 arcsec and bring them into alignment with residual errors less than 50milli-arcsec is fully described. Next, the hardware and software designs of CCAS are presented, as well as the results of laboratory performance testing. CCAS has been installed and integrated with the primary mirror control system. Performance results of the integrated system over a range of environmental conditions will be shown. Finally, the overall results of this project are summarized and suggestions for future improvements presented.
Atmospheric turbulence over long horizontal paths perturbs phase in the pupil of an optical communications receiver, and also can cause severe intensity scintillations. We describe a real time wavefront compensation system using PC technology to perform all wavefront control tasks. This system uses a modal correction scheme, and we report the first measurements of residual wavefront taken approximately 1 meter above ground level at 1 km range. The effects of turbulence, scintillations and control bandwidth on the correction are all examined.
Atmospheric turbulence over long horizontal paths perturbs phase and also can cause severe intensity scintillation in the pupil
of an optical communications receiver. This limits the bit error rate over which intensity based modulation schemes can
operate. To quantifi the extent ofthe problem, we built a high speed and high resolution wavefront sensor capable of
measuring both the amplitude and phase over a horizontal turbulent path. We present resulting measurements of the
probability distributions ofboth amplitude and phase as well as Zernike polynomial decomposition ofthe temporal power
spectra of phase fluctuations. These results are compared to existing turbulence models, and are used to determine
requirements for a wavefront correction scheme using adaptive optics.
As part of the HST repair mission it is necessary to verify the performance of the correction optics before their installation in the telescope. To accomplish this precision testing a Hartmann style wavefront sensor and pupil parameter measurement tool has been designed and built. This instrument, termed the Aberrated Beam Analyzer (ABA), will be used to measure the wavefront of both aberrated HST simulators and the unaberrated output of the correction optics. In addition, the ABA measures the location, size, and obscuration ratio of the exit pupil of the system under test. Parameters such as the chief ray angle, PSF, MTF, encircled energy, and Strehl ratio are calculated from the measured data. Operation of the ABA is fully automated and is controlled via a high level scripting language. All data is permanently archived on optical disks for later analysis. The design and theory of operation of the ABA will be discussed. Particular emphasis will be given to the error budget and the measurement performance of the ABA. Some preliminary data will be presented.
An extensive research program has been conducted to characterize the performance of image-tube components under conditions typical of adaptive optics systems, as well as to develop novel image-tube components and assembly techniques. A comparison is presented of standard image-tube capabilities which identifies the tube components which fall short of requirements. Attention is given to the fiber-optic faceplate, phosphor formulation, gate-electrode pulsers, power supplies, and intensifier packaging that have been developed.