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 Foundry Microfabrication of Deformable Mirrors for Adaptive Optics written by William D. Cowan and published by . This book was released on 1998-04-01 with total page 285 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microelectromechanical Systems (MEMS) is a rapidly emerging field of research in which batch fabrication processes are used to construct miniature devices. MEMS devices are particularly well suited to optical applications. Foundry microfabrication offers a substantial cost advantage for prototype system development. In this research, foundry MEMS processes are used to fabricate low-cost deformable mirror systems (MEM-DMs) for adaptive optics. The challenges and design trades associated with fabrication of continuous and segmented deformable mirrors in foundry processes are examined in detail. Micromirror surface figure is shown to be critically important. Beam steering and optical aberration correction experiments conclusively demonstrate the potential of low-cost MEM-DMs. The prototype MEM-DM systems are approximately 1/ 500th the cost of conventionally manufactured deformable mirrors. An innovative direct digital control scheme further reduces adaptive optic system cost by eliminating the digital to analog converter typically required for each controlled element. In addition to the MEM-DMs, other MEMS devices are shown. The thermally actuated piston micromirrors offer greater deflections for operation at longer optical wavelengths. Other MEMS devices examined include a series of tilting mirrors, pressure gauges, test structures, electrostatic scratch drive actuated rotors, and a new type of electrostatic cantilever motor with lateral motion output.
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 2012-10-22 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 MEMS Deformable Mirrors for Adaptive Optics written by Raji Krishnamoorthy Mali and published by . This book was released on 1999 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Demonstrating Optical Aberration Correction with a Mems Micro Mirror Device written by Shaun Roger Hick and published by . This book was released on 1996-12-01 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research conducted the first demonstrated use of a micro- electro-mechanical structure (MEMS) mirror array to correct a static optical aberration. A well developed technique in adaptive optics imaging systems uses a deformable mirror to reflect the incident wave front to the imaging stage of the system. By matching the surface of the deformable mirror to the shape of the wave front phase distortion, the reflected wave front will be less aberrated before it is imaged. Typical adaptive optics systems use piezo-electric actuated deformable mirrors. This research used an electrostatically actuated, segmented mirror array, constructed by standard MEMS fabrication techniques, to investigate its performance as a deformable mirror. The relatively cheap cost of MEMS fabrication promises new adaptive optics applications if a suitable design can be found. In the demonstration, the point spread function (PSF) of the corrected and uncorrected aberrated image were compared. A 43 percent improvement in the peak intensity of the PSF was noted in the corrected image.
Download or read book Design Fabrication and Characterization of MEMS Deformable Mirrors for Ocular Adaptive Optics written by Hyunkyu Park and published by . This book was released on 2009 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Micro machined Membrane Deformable Mirrors for Cryogenic Adaptive Optics written by Harold Michael Dyson and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Micro deformable Mirrors written by and published by . This book was released on 1999 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modelling MEMS Deformable Mirrors for Astronomical Adaptive Optics written by Célia Blain and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As of July 2012, 777 exoplanets have been discovered utilizing mainly indirect detection techniques. The direct imaging of exoplanets is the next goal for astronomers, because it will reveal the diversity of planets and planetary systems, and will give access to the exoplanet's chemical composition via spectroscopy. With this spectroscopic knowledge, astronomers will be able to know, if a planet is terrestrial and, possibly, even find evidence of life. With so much potential, this branch of astronomy has also captivated the general public attention. The direct imaging of exoplanets remains a challenging task, due to (i) the extremely high contrast between the parent star and the orbiting exoplanet and (ii) their small angular separation. For ground-based observatories, this task is made even more difficult, due to the presence of atmospheric turbulence. High Contrast Imaging (HCI) instruments have been designed to meet this challenge. HCI instruments are usually composed of a coronagraph coupled with the full on-axis corrective capability of an Extreme Adaptive Optics (ExAO) system. An efficient coronagraph separates the faint planet's light from the much brighter starlight, but the dynamic boiling speckles, created by the stellar image, make exoplanet detection impossible without the help of a wavefront correction device. The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system is a high performance HCI instrument developed at Subaru Telescope. The wavefront control system of SCExAO consists of three wavefront sensors (WFS) coupled with a 1024-actuator Micro-Electro-Mechanical-System (MEMS) deformable mirror (DM). MEMS DMs offer a large actuator density, allowing high count DMs to be deployed in small size beams. Therefore, MEMS DMs are an attractive technology for Adaptive Optics (AO) systems and are particularly well suited for HCI instruments employing ExAO technologies. SCExAO uses coherent light modulation in the focal plane introduced by the DM, for both wavefront sensing and correction. In this scheme, the DM is used to introduce known aberrations (speckles in the focal plane), which interfere with existing speckles. By monitoring the interference between the pre-existing speckles and the speckles added deliberately by the DM, it is possible to reconstruct the complex amplitude (amplitude and phase) of the focal plane speckles. Thus, the DM is used for wavefront sensing, in a scheme akin to phase diversity. For SCExAO and other HCI systems using phase diversity, the wavefront compensation is a mix of closed-loop and open-loop control of the DM. The successful implementation of MEMS DMs open-loop control relies on a thorough modelling of the DM response to the control system commands. The work presented in this thesis, motivated by the need to provide accurate DM control for the wavefront control system of SCExAO, was centred around the development of MEMS DM models. This dissertation reports the characterization of MEMS DMs and the development of two efficient modelling approaches. The open-loop performance of both approaches has been investigated. The model providing the best result has been implemented within the SCExAO wavefront control software. Within SCExAO, the model was used to command the DM to create focal plane speckles. The work is now focused on using the model within a full speckle nulling process and on increasing the execution speed to make the model suitable for on-sky operation.
Download or read book Design Fabrication and Characterization of High stroke High aspect Ratio Micro Electro Mechanical Systems Deformable Mirrors for Adaptive Optics written by Bautista Fernández Rocha and published by . This book was released on 2011 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Adaptive Optics Using MEMS Deformable Mirrors written by Dhiraj Hiro Malkani and published by . This book was released on 2000 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Fabrication Processes for MEMS Deformable Mirrors in the Next Generation Telescope Instruments written by Alioune Diouf and published by . This book was released on 2010 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This dissertation advances three critical technology areas at the frontier of research for micro electro-mechanical systems (MEMS) deformable minors (DMs) needed for next generation telescopes (NGTs). High actuator-count MEMS deformable minors are needed for future ground-based large astronomical telescopes. Scaling up the current MEMS DMs to unprecedented numbers of independent actuators--up to 10,000 on a single DM--will require new electrical connection architecture for the actuators in order to replace the wire-bonded scheme that has been used to date. A through-wafer via interconnection fabrication process for MEMS DMs is developed to offer a path to transform the frontier of high actuator count MEMS micromirrors. In a class of NGTs instrument known as the Multi-Object Adaptive Optics (MOAO), the correction made by the DM of the wavefront phase error over the entire telescope field view is not accessible to the sensing unit. To achieve compensation, precise, single step "open-loop" commands must be developed for the DM. Due to the nonlinear relationship between applied voltage and actuation displacement at each actuator, and the mechanical coupling among actuators through the mirror membrane, such open-loop control is a formidable task. A combination of mirror surface modeling and sparse actuator empirical calibration is used to demonstrate open-loop control of MEMS deformable minors to the accuracy of closed-loop control over the entire available DM stroke. Shapes at the limit of achievable minor spatial frequencies with up to 2.5um amplitudes have been achieved within 20nm RMS error accuracy of closed-loop control. The calibration of a single actuator to be used for predicting shapes results in an additional 14nm RMS surface error compared to parallel calibration of all actuators in the deformable minor. The ubiquitous reflective coatings for MEMS deformable minors are gold and aluminum. Emerging adaptive optics application require broadband optical coatings usable from the near visible to near infrared, i.e. silver. Many of the reflective coatings of interest have high stress resulting in added curvature on deformable mirror. A thick epitaxial polysilicon MEMS mirror that can tolerate thicker reflective coatings with higher stresses has been fabricated. A thin film deposition process to counteract the stress in the reflective coating was also developed. The deformable mirror has low stress (-10 nm flatness), high reflectivity (>95%), 1024 actuated segments, that is usable over a wavelength range from visible to IR with a protective layer for the silver coating and stress-reducing layer between the silver and mirror layer to obtain the desired flatness.
Download or read book Adaptive Optics with a Micromachined Membrane Deformable Mirror for High Resolution Retinal Imaging written by Lijun Zhu and published by . This book was released on 1999 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Extreme Adaptive Optics Testbed written by J. W. Evans and published by . This book was released on 2005 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: ''Extreme'' adaptive optics systems are optimized for ultra-high-contrast applications, such as ground-based extrasolar planet detection. The Extreme Adaptive Optics Testbed at UC Santa Cruz is being used to investigate and develop technologies for high-contrast imaging, especially wavefront control. We use a simple optical design to minimize wavefront error and maximize the experimentally achievable contrast. A phase shifting diffraction interferometer (PSDI) measures wavefront errors with sub-nm precision and accuracy for metrology and wavefront control. Previously, we have demonstrated RMS wavefront errors of 1.5 nm and a contrast of10{sup 7} over a substantial region using a shaped pupil without a deformable mirror. Current work includes the installation and characterization of a 1024-actuator Micro-Electro-Mechanical-Systems (MEMS) deformable mirror, manufactured by Boston Micro-Machines for active wavefront control. Using the PSDI as the wavefront sensor we have flattened the deformable mirror to 1 nm within the controllable spatial frequencies and measured a contrast in the far field of10{sup 6}. Consistent flattening required testing and characterization of the individual actuator response, including the effects of dead and low-response actuators. Stability and repeatability of the MEMS devices was also tested. Ultimately this testbed will be used to test all aspects of the system architecture for an extrasolar planet-finding AO system.
Download or read book Adaptive Optics in Astronomy written by François Roddier and published by Cambridge University Press. This book was released on 1999-06-17 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adaptive optics is set to revolutionise the future of astronomy; this is the first book on the subject and is set to become the standard reference.
Download or read book Dynamic Characterization Modeling and Control of a Deformable Mirror for Adaptive Optics Ophthalmic Applications written by Erika Odlund and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
