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 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 Optical MEMS Nanophotonics and Their Applications written by Guangya Zhou and published by CRC Press. This book was released on 2017-12-14 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers device design fundamentals and system applications in optical MEMS and nanophotonics. Expert authors showcase examples of how fusion of nanoelectromechanical (NEMS) with nanophotonic elements is creating powerful new photonic devices and systems including MEMS micromirrors, MEMS tunable filters, MEMS-based adjustable lenses and apertures, NEMS-driven variable silicon nanowire waveguide couplers, and NEMS tunable photonic crystal nanocavities. The book also addresses system applications in laser scanning displays, endoscopic systems, space telescopes, optical telecommunication systems, and biomedical implantable systems. Presents efforts to scale down mechanical and photonic elements into the nano regime for enhanced performance, faster operational speed, greater bandwidth, and higher level of integration. Showcases the integration of MEMS and optical/photonic devices into real commercial products. Addresses applications in optical telecommunication, sensing, imaging, and biomedical systems. Prof. Vincent C. Lee is Associate Professor in the Department of Electrical and Computer Engineering, National University of Singapore. Prof. Guangya Zhou is Associate Professor in the Department of Mechanical Engineering at National University of Singapore.
Download or read book MEMS Adaptive Optics written by Scot S. Olivier and published by SPIE-International Society for Optical Engineering. This book was released on 2007 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of SPIE present the original research papers presented at SPIE conferences and other high-quality conferences in the broad-ranging fields of optics and photonics. These books provide prompt access to the latest innovations in research and technology in their respective fields. Proceedings of SPIE are among the most cited references in patent literature.
Download or read book IR Space Telescopes and Instruments written by John C. Mather and published by . This book was released on 2003 with total page 660 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 Advances in Nanotechnology Research and Application 2012 Edition written by and published by ScholarlyEditions. This book was released on 2012-12-26 with total page 14170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Nanotechnology Research and Application / 2012 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Nanotechnology. The editors have built Advances in Nanotechnology Research and Application / 2012 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Nanotechnology in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Advances in Nanotechnology Research and Application / 2012 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Download or read book Optical Modeling and Validation for the Deformable Mirror Demonstration Mission written by Rachel E. Morgan (S.M.) and published by . This book was released on 2020 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microelectromechanical Systems (MEMS) Deformable Mirrors (DMs) are a promising technology to enable the wavefront control required for high contrast imaging and characterization of exoplanets with coronagraph instruments. MEMS DMs are a key technology option for future exoplanet imaging space telescopes because they can provide precise wavefront control with low size, weight, and power required. The Deformable Mirror Demonstration Mission (DeMi) CubeSat mission will demonstrate MEMS DMs in the space environment for the first time. The DeMi payload will characterize the on-orbit performance of a 140 actuator MEMS DM with 5.5 [mu]m maximum stroke, with a goal of measuring individual actuator wavefront displacement contributions to a precision of 12 nm. The payload will be able to measure low order aberrations to [lambda]/10 accuracy and [lambda]/50 precision, and will correct static and dynamic wavefront phase errors to less than 100 nm RMS. The DeMi payload contains both a Shack Hartmann wavefront sensor and an image plane wavefront sensor to monitor the DM behavior on orbit. In this thesis, an optical diffraction model is developed to simulate the signals on both the Shack Hartmann wavefront sensor and the image plane wavefront sensor. The flight payload alignment and integration process is described, and the optical model is validated with relevant data from the flight payload. The DeMi satellite is expected to launch in February 2020.
Download or read book High Actuator Count MEMS Deformable Mirrors for Space Telescopes written by and published by . This book was released on 2010 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Micro Electro Mechanical Systems (MEMS) deformable mirrors are capable of correcting aberrations in space-based optical imaging systems. The small size, weight, and power requirements are ideal for space based adaptive optics. However, the yield, number of actuators, and surface accuracies can be improved. Yield is the proportion of the mirror segments that work. A low-power driver is also needed. The impact of microscopic manufacturing defects and substrate bowing were investigated. To reduce power consumption in the drive electronics, a multiplexed driver was investigated. A prototype of the multiplexed driver was constructed and will be used for future tests on a deformable mirror.
Download or read book Optical Infrared and Millimeter Space Telescopes written by and published by . This book was released on 2004 with total page 728 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book MEMS Mirrors written by Huikai Xie and published by MDPI. This book was released on 2018-05-04 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "MEMS Mirrors" that was published in Micromachines
Download or read book Optical Manufacturing and Testing written by and published by . This book was released on 1999 with total page 662 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Journal of Micro nanolithography MEMS and MOEMS written by and published by . This book was released on 2008 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 The Academic Job Search Handbook written by Julia Miller Vick and published by University of Pennsylvania Press. This book was released on 2016-03-17 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: For more than twenty years, job seekers have relied on The Academic Job Search Handbook for help in their search for faculty positions. The new fifth edition provides updated advice and addresses current topics in today's competitive market.
Download or read book Space Telescopes and Instrumentation 2012 written by Mark C. Clampin and published by . This book was released on 2012 with total page 1856 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of SPIE present the original research papers presented at SPIE conferences and other high-quality conferences in the broad-ranging fields of optics and photonics. These books provide prompt access to the latest innovations in research and technology in their respective fields. Proceedings of SPIE are among the most cited references in patent literature.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1020 pages. Available in PDF, EPUB and Kindle. Book excerpt:
