Download or read book Design of the Tip tilt Mirror for the Adaptive Optics System of Amateur Telescopes and Optimum Placement of Actuators written by Parthapratim Chakraborty and published by . This book was released on 1998 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design and Implementation of the Tip Tilt Compensation System for Raven a Multi Object Adaptive Optics System written by Reston Nash and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Multi-Object Adaptive Optics promises to be a useful tool for the upcoming class of Extremely Large Telescopes. Like current adaptive optics systems, MOAO systems compensate optical aberrations caused by atmospheric turbulence, but with the added benefit of being able to compensate multiple portions of a telescope's field at the same time. To ensure the success of the eventual MOAO systems built for the ELTs, several demonstrator instruments have been designed and tested on current telescopes. Raven is one of these demonstrators, designed by the University of Victoria Adaptive Optics Lab for the Subaru 8.2 meter telescope to feed the InfraRed Camera and Spectrograph. Raven corrects the light of two science targets using wavefront information from three natural guide stars, and a single laser guide star. The topic of this thesis is the design and implementation of Raven's tip/tilt compensation system, used to stabilize the output image positions on IRCS's 0.140" slit. Tip/tilt correction of the science targets is done using a combination of motorized pick-off arms, piezoelectric tip/tilt platforms, and deformable mirrors. Through digital filtering and calibration, it is shown that these actuators are able to collectively keep the output science images stationary during simulated laboratory observations. A performance reduction due to residual tip/tilt errors is expected to be less than 5%. Raven goes on-sky in mid-2014, and it will be the first MOAO instrument to attempt scientific observations.
Download or read book The Design of an Adaptive Tip tilt Mirror for Adaptive Optics written by Christopher C. Wilcox and published by . This book was released on 2005 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamic Reconstruction and Multivariable Control for Force Actuated Thin Facesheet Adaptive Optics written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-11-18 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Multiple Mirror Telescope (MMT) under development at the University of Arizona takes a new approach in adaptive optics placing a large (0.65 m) force-actuated, thin facesheet deformable mirror at the secondary of an astronomical telescope, thus reducing the effects of emissivity which are important in IR astronomy. However, The large size of the mirror and low stiffness actuators used drive the natural frequencies of the mirror down into the bandwidth of the atmospheric distortion. Conventional adaptive optics takes a quasi-static approach to controlling the, deformable mirror. However, flexibility within the control bandwidth calls for a new approach to adaptive optics. Dynamic influence functions are used to characterize the influence of each actuator on the surface of the deformable mirror. A linearized model of atmospheric distortion is combined with dynamic influence functions to produce a dynamic reconstructor. This dynamic reconstructor is recognized as an optimal control problem. Solving the optimal control problem for a system with hundreds of actuators and sensors is formidable. Exploiting the circularly symmetric geometry of the mirror, and a suitable model of atmospheric distortion, the control problem is divided into a number of smaller decoupled control problems using circulant matrix theory. A hierarchic control scheme which seeks to emulate the quasi-static control approach that is generally used in adaptive optics is compared to the proposed dynamic reconstruction technique. Although dynamic reconstruction requires somewhat more computational power to implement, it achieves better performance with less power usage, and is less sensitive than the hierarchic technique. Grocott, Simon C. O. and Miller, David W. Langley Research Center; Marshall Space Flight Center ADAPTIVE OPTICS; DEFORMABLE MIRRORS; TELESCOPES; DYNAMIC CONTROL; OPTIMAL CONTROL; ACTUATORS; ATMOSPHERIC MODELS; BANDWIDTH; DISTORTION; EMISSIVITY; FLEXIBILITY; INFRARED ASTRONOMY; MATRI...
Download or read book Modeling and Control of Magnetic Fluid Deformable Mirrors for Adaptive Optics Systems written by Zhizheng Wu and published by Springer Science & Business Media. This book was released on 2012-10-21 with total page 323 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modeling and Control of Magnetic Fluid Deformable Mirrors for Adaptive Optics Systems presents a novel design of wavefront correctors based on magnetic fluid deformable mirrors (MFDM) as well as corresponding control algorithms. The presented wavefront correctors are characterized by their linear, dynamic response. Various mirror surface shape control algorithms are presented along with experimental evaluations of the performance of the resulting adaptive optics systems. Adaptive optics (AO) systems are used in various fields of application to enhance the performance of optical systems, such as imaging, laser, free space optical communication systems, etc. This book is intended for undergraduate and graduate students, professors, engineers, scientists and researchers working on the design of adaptive optics systems and their various emerging fields of application. Zhizheng Wu is an associate professor at Shanghai University, China. Azhar Iqbal is a research associate at the University of Toronto, Canada. Foued Ben Amara is an assistant professor at the University of Toronto, Canada.
Download or read book The Shock and Vibration Digest written by and published by . This book was released on 2000 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Technique for Designing Active Control Systems for Astronomical telescope Mirrors written by W. E. Howell and published by . This book was released on 1973 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book LQG LTR Tilt and Tip Control for the Starfire Optical Range 3 5 meter Telescope s Adaptive Optics System written by Neil D. Paris and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Smart Structures and Materials 1993 written by Mark A. Ealey and published by . This book was released on 1993 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Active and Adaptive Optical Components and Systems written by and published by . This book was released on 1993 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Issues in the Design and Optimization of Adaptive Optics and Laser Guide Stars for the Keck Telescopes written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We discuss issues in optimizing the design of adaptive optics and laser guide star systems for the Keck Telescope. The initial tip-tilt system will use Keck's chopping secondary mirror. We describe design constraints, choice of detector, and expected performance of this tip-tilt system as well as its sky coverage. The adaptive optics system is being optimized for wavelengths of I-2.2[mu]m. We are studying adaptive optics concepts which use a wavefront sensor with varying numbers of subapertures, so as to respond to changing turbulence conditions. The goal is to be able to ''gang together'' groups of deformable mirror subapertures under software control, when conditions call for larger subapertures. We present performance predictions as a function of sky coverage and the number of deformable mirror degrees of freedom. We analyze the predicted brightness several candidate laser guide star systems, as a function of laser power and pulse format. These predictions are used to examine the resulting Strehl as a function of observing wavelength and laser type. We discuss laser waste heat and thermal management issues, and conclude with an overview of instruments under design to take advantage of the Keck adaptive optics system.
Download or read book Efficient Drive Electronics for Deformable Mirrors of Telescope Adaptive Optics Systems written by Joel Niebergal and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis deals with the design and experimental validation of Deformable Mirror Electronics (DME) for Extremely Large Telescope (ELT) Adaptive Optics (AO) applications. Modern ground based telescopes achieve their best possible imaging resolution through the application of AO. However, due to the fundamental diffraction of optical elements, the next generation of ELTs will employ primary mirrors of an increasingly large diameter as the final means of improving imaging resolution further. The corresponding increase in diameter and actuator count of the Deformable Mirrors (DMs) in these systems has led to the rapid development of high order DM technology. A significant challenge to operating these multi-thousand channel DMs is related to the DM Electronics (DME), which are required to be highly efficient so-as to operate within practical budgetary constraints. This thesis develops a DME reference design based on the requirements for the Thirty Meter Telescope's next generation AO system, the Narrow Field Infrared Adaptive Optics System (NFIRAOS), which operates two DMs with a total of 7673 piezoelectric actuators. The basis of the DME is the DM actuator driver, which has been developed to be suitable for very high order reproduction by optimization of its size, power, cost and reliability. A complication is that the piezoelectric actuators in NFIRAOS DMs require high voltage drive signals of ?400 V to obtain the rated stroke and must be current limited to avoid damage. Candidate amplifiers are evaluated in simulation and hardware based on a combination of performance, physical and functional criteria; with the most suitable circuit chosen for a multi-channel prototype implementation and testing with a DM breadboard prototype. The development and optimization of an amplifier capable of meeting NFIRAOS performance criteria and budgetary constraints is demonstrated.
Download or read book Evaluation of Control Laws and Actuator Locations for Control Systems Applicable to Deformable Astronomical Telescope Mirrors written by Aaron J. Ostroff and published by . This book was released on 1973 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: Some of the major difficulties associated with large orbiting astronomical telescopes are the cost of manufacturing the primary mirror to precise tolerances and the maintaining of diffraction-limited tolerances while in orbit. One successfully demonstrated approach for minimizing these problem areas is the technique of actively deforming the primary mirror by applying discrete forces to the rear of the mirror. A modal control technique, as applied to active optics, has previously been developed and analyzed. The modal control technique represents the plant to be controlled in terms of its eigenvalues and eigenfunctions which are estimated via numerical approximation techniques. The report includes an extension of previous work using the modal control technique and also describes an optimal feedback controller. The equations for both control laws are developed in state-space differential form and include such considerations as stability, controllability, and observability. These equations are general and allow the incorporation of various mode-analyzer designs; two design approaches are presented. The report also includes a technique for placing actuator and sensor locations at points on the mirror based upon the flexibility matrix of the uncontrolled or unobserved modes of the structure. The locations selected by this technique are used in the computer runs which are described. The results are based upon three different initial error distributions, two mode-analyzer designs, and both the modal and optimal control laws.
Download or read book Selected Papers on Prisms and Mirrors design and Fabrication written by R. Hradaynath and published by . This book was released on 1993 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: SPIE Milestones are collections of seminal papers from the world literature covering important discoveries and developments in optics and photonics.
Download or read book Tip tilt Compensation written by and published by . This book was released on 1992 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: The angular resolution of long-exposure images from ground-based telescopes equipped with laser guide star adaptive optics systems is fundamentally limited by the the accuracy with which the tip-tilt aberrations introduced by the atmosphere can be corrected. Assuming that a natural star is used as the tilt reference, the residual error due to tilt anisoplanatism can significantly degrade the long-exposure resolution even if the tilt reference star is separated from the object being imaged by a small angle. Given the observed distribution of stars in the sky, the need to find a tilt reference star quite close to the object restricts the fraction of the sky over which long-exposure images with diffraction limited resolution can be obtained. In this paper, the authors present a comprehensive performance analysis of tip-tilt compensation systems that use a natural star as a tilt reference, taking into account properties of the atmosphere and of the Galactic stellar populations, and optimizing over the system operating parameters to determine the fundamental limits to the long-exposure resolution. Their results show that for a ten meter telescope on Mauna Kea, if the image of the tilt reference star is uncorrected, about half the sky can be imaged in the V band with long-exposure resolution less than 60 milli-arc-seconds (mas), while if the image of the tilt reference star is fully corrected, about half the sky can be imaged in the V band with long-exposure resolution less than 16 mas. Furthermore, V band images long-exposure resolution of less than 16 mas may be obtained with a ten meter telescope on Mauna Kea for unresolved objects brighter than magnitude 22 that are fully corrected by a laser guide star adaptive optics system. This level of resolution represents about 70% of the diffraction limit of a ten meter telescope in the V band and is more than a factor of 45 better than the median seeing in the V band on Mauna Kea.
Download or read book Micro deformable Mirrors for Adaptive Optics Applications written by Emily Jo Carr and published by . This book was released on 2006 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Wavefront Control for Space Telescope Applications Using Adaptive Optics written by and published by . This book was released on 2007 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: Future long dwell high resolution imagery satellites and space telescopes will require very large flexible primary mirrors. These large mirrors face many challenges including optical surface imperfections, structural vibrations, and jitter. A flexible mirror can overcome some of these challenges by applying adaptive optics techniques to correct mirror deformations and aberrations to produce image quality data. This paper examines and develops control techniques to control a deformable mirror subjected to a disturbance. The experimental portion of the work uses discrete time proportional integral control with second order filters to control disturbances in a deformable mirror and correct aberrations in an adaptive optics system using laser light. Using an adaptive optics testbed containing two deformable mirrors, two fast steering mirrors, two wave front sensors, a position sensor, and a combination of lenses the system corrects a simulated dynamic disturbance induced in the deformable mirror. Experiments using the described testbed successfully demonstrate wavefront control methods, including a combined iterative feedback and gradient control technique. This control technique results in a three fold improvement in RMS wavefront error over the individual controllers correcting from a biased mirror position. Second order discrete time notch filters are also used to remove induced low frequency actuator and sensor noise at 0.8 Hz, 2 Hz and 5 Hz. Additionally a 2 Hz structural disturbance is simulated on a Micromachined Membrane Deformable Mirror and removed using discrete time notch filters combined with a modal iterative closed loop feedback controller, showing a 36 fold improvement in RMS wavefront error over the iterative closed loop feedback alone.
