A5030196301- Adaptive optics and wavefront sensing
- Optical Systems and Laser Technology
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Advanced optical system design
- American Constitutional Law and Politics
- American History and Culture
- Optical Wireless Communication Technologies
- Astronomical Observations and Instrumentation
- Software Engineering Research
- Formal Methods in Verification
- Canadian Identity and History
- Semiconductor Lasers and Optical Devices
- Race, History, and American Society
- Advanced Software Engineering Methodologies
- Optical Network Technologies
- Real-Time Systems Scheduling
- Software Reliability and Analysis Research
- Parallel Computing and Optimization Techniques
- Atomic and Subatomic Physics Research
- Seismic Imaging and Inversion Techniques
- Logic, programming, and type systems
- Optical measurement and interference techniques
- Service-Oriented Architecture and Web Services
- Embedded Systems Design Techniques
Durham University
2009-2020
Duke University
2010
Naval War College
1961
University of Virginia
1956
Adaptive optics provides real time correction of wavefront disturbances on ground based telescopes.Optimizing control and performance is a key issue for ever more demanding instruments larger telescopes affected not only by atmospheric turbulence, but also vibrations, windshake tracking errors.Linear Quadratic Gaussian achieves optimal when provided with temporal model the disturbance.We present in this paper first on-sky results Kalman filter LQG vibration mitigation CANARY instrument at...
Context. A new challenging adaptive optics (AO) system, called multi-object (MOAO), has been successfully demonstrated on-sky for the first time at 4.2 m William Herschel Telescope, Canary Islands, Spain, end of September 2010.
The Southern African Large Telescope (SALT) High Resolution Spectrograph (HRS) is a fibre-fed R4 échelle spectrograph employing white pupil design with red and blue channels for wavelength coverage from 370–890nm. instrument has four modes, each object sky fibres: Low (R~15000), Medium (R~40000) (R~65000), as well Stability mode enhanced radial velocity precision at R~65000. contains fibre double-scrambler offers optional simultaneous Th-Ar arc injection, or the inclusion of an iodine cell...
The Durham adaptive optics (AO) real-time controller was initially a proof of concept design for generic AO control system. It has since been developed into modern and powerful central-processing-unit-based system, capable using hardware acceleration (including field programmable gate arrays graphical processing units), based primarily around commercial off-the-shelf hardware. is enough to be used as the all currently planned 8 m class telescope systems. Here we give details this concepts...
SALT HRS is a fibre-fed, high dispersion échelle spectrograph currently being constructed for the Southern African Large Telescope (SALT). In this paper we highlight performance of key optical components, describe integration tasks that have taken place and present some first light results from laboratory. The instrument construction well advanced report on attainment required mechanical thermal stability provide measurement input optics (including fibre feed). initial alignment both optics,...
EAGLE is a multi-object 3D spectroscopy instrument currently under design for the 42-metre European Extremely Large Telescope (E-ELT). Precise requirements are still being developed, but it clear that will require (~100 x 100 actuator) adaptive optics correction of ~20 - 60 spectroscopic subfields distributed across ~5 arcminute diameter field view. It very likely LGS be required to provide wavefront sensing with necessary sky coverage. Two alternative implementations considered, one which...
Recent advances in adaptive optics (AO) have led to the implementation of wide field-of-view AO systems. A number wide-field systems are also planned for forthcoming Extremely Large Telescopes. Such multiple wavefront sensors different types, and usually deformable mirrors (DMs). Here, we report on our experience integrating cameras DMs with real-time control two These CANARY, which has been operating on-sky since 2010, DRAGON, is a laboratory demonstrator instrument. We detail issues...
The first on-sky results obtained by CANARY, the multi-object adaptive optics (MOAO) demonstrator, are analysed. data were recorded at William Herschel Telescope, end of September 2010. We describe command and calibrations algorithms used during run present observing conditions. processed MOAO-loop engaged or disengaged slopes buffers, comprising synchronised measurements four natural guide stars (NGS) wavefront sensors running in parallel, near infrared (IR) images. method we use to...
HARMONI is the adaptive optics assisted, near-infrared and visible light integral field spectrograph for Extremely Large Telescope (ELT). A first instrument, it provides work-horse spectroscopic capability ELT. As project approaches its Final Design Review milestone, design of instrument being finalized, plans assembly, integration testing are detailed. We present an overview instrument's capabilities from a user perspective, provide summary design, including operations calibrations, brief...
CANARY is an on-sky Laser Guide Star (LGS) tomographic AO demonstrator in operation at the 4.2m William Herschel Telescope (WHT) La Palma. From early demonstration of open-loop tomography on a single deformable mirror using natural guide stars 2010, has been progressively upgraded each year to reach its final goal July 2015. It now two-stage system that mimics future E-ELT: GLAO-driven woofer based 4 laser delivers ground-layer compensated field figure sensor locked tweeter DM, achieves...
CANARY is an on-sky Laser Guide Star (LGS) tomographic AO demonstrator that has been in operation at the 4.2m William Herschel Telescope (WHT) La Palma since 2010. In 2013, was upgraded from its initial configuration used three off-axis Natural Stars (NGS) through inclusion of four Rayleigh LGS and associated wavefront sensing system. Here we present system analysis results obtained WHT between May September 2014. Finally final 'Phase C' aims to recreate emulate expected both AOF VLT E-ELT.
The main goal of Green Flash is to design and build a prototype for Real-Time Controller (RTC) targeting the European Extremely Large Telescope (E-ELT) Adaptive Optics (AO) instrumentation. E-ELT 39m diameter telescope see first light in early 2020s. To this critical component operations, astronomical community facing technical challenges, emerging from combination high data transfer bandwidth, low latency throughput requirements, similar identified barriers on road Exascale. With Flash, we...
We address two problems concerned with the maintenance of safety-critical software. Firstly, we analyse new issues required for reverse engineering real-time existing code to extract high level designs. Secondly, present a possible design abstraction mechanism that can be used use formal transformations both in systems involving temporal constraints, and definition abstract representation. framework results initial experiments. The contributions are: (1) requirements analyses systems, (2)...
Full LQG adaptive optics (AO) control is validated for the first time on sky classical AO and multi-object with 3 natural guide stars (GSs) a Rayleigh laser GS, including vibration mitigation, Canary demonstrator (William Herschel Telescope, Spain).
Tools to record the knowledge gained by maintainers engaged in understanding an existing program are described. These tools based on a model of comprehension process and reverse engineering as whole. They form part integrated toolset around central repository. Using these new documentation for software system may be built up incrementally successive who work system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
EAGLE is a multi-object 3D spectroscopy instrument currently under design for the 42-metre European Extremely Large Telescope (E-ELT). will use open-loop Multi-Object Adaptive Optics (MOAO) to provide partial AO correction across wide (5-10 arcmin) field of view. The novelty this scheme such that on-sky demonstration required prior final construction an E-ELT instrument. CANARY project implement single channel MOAO system on 4.2m William Herschel Telescope. undergoing phased development plan...
The CANARY on-sky MOAO demonstrator is being integrated in the laboratory and a status update about its various components presented here. We also discuss alignment calibration procedures used to improve system performance overall stability. will be commissioned at William Herschel Telescope end of September 2010.
MOSAIC is a mixed-mode multiple object spectrograph planned for the ELT that uses tiled focal plane to support variety of observing modes. The AO system 4 LGS WFS and up NGS positioned anywhere within full 10 arcminute field view control either M4/5 alone GLAO operation feeding 200 targets in plane, or conjunction with open-loop DMs MOAO correction. In this paper we present overall design performance systems.
DRAGON is a real-time, tomographic Adaptive Optics test bench currently under development at Durham University. Optical and mechanical design work for now complete, the system close to becoming fully operational. emulates current 4.2 m 8 telescopes, can also be used investigate ELT scale issues. The full features 4 Laser Guide Star (LGS) Wavefront Sensors (WFS), 3 Natural (NGS) WFSs one Truth Sensor, all of which are 31 × sub-aperture Shack-Hartmann WFS. Two Deformable Mirrors (DMs), Boston...
The Green Flash initiative responds to a critical challenge in the astronomical community. Scaling up real-time control solutions of AO instruments operation specifications modules at core next generation extremely large telescopes is not viable option. main goal this project design and build prototype for an RTC targeting E-ELT first-light instrumentation. We have proposed innovative technical based on emerging technologies High Performance Computing, assessed enabling through prototyping...
Abstract Reverse‐engineering of interrupt‐driven, real‐time programs with timing constraints is a particularly challenging research area, because the functional behaviour program, and non‐functional requirements, are implicit can be very difficult to discover. However, in this paper we present significant advance which achieved by modelling interrupts wide spectrum language, WSL. A small example program modelled way, formal transformations used derive various ‘inverse‐engineer’ specification...
Paper reprinted from ICSM '96. We describe a formal approach to reverse engineering programs with concurrent constructs. This has been topic which not previously addressed, yet is required for safety critical systems and many others. To achieve this we have used transformation based successful in coping sequential systems. accommodate concurrency extend the core kernel language (WSL) introduce then prove new transformations. preliminary results. The novel aspects of work are application...
DRAGON is be a new and in many ways unique visible light adaptive optics test bench. Initially, it will existing concepts for CANARY, the laser guide star tomographic demonstrator on WHT, then later used to explore other future telescopes. Natural Laser Guide Stars (NGS LGS) are emulated, where LGSs exhibit effects of passing up through turbulence spot elongation. AO correction performed by one high low order deformable mirror, allowing woofer-tweeter control, multiple wave front sensors...
We present in this paper the very first on-sky results of full Multi-Object Adaptive Optics (MOAO) LQG control (i.e. all modes, with coupling, controlled an regulator), obtained Spring 2013 on CANARY demonstrator at William Herschel Telescope (La Palma, Spain). The MOAO pathfinder features two AO configurations that have both been tested: single-conjugated and multi-object NGS NGS+LGS, together vibration mitigation tip tilt modes. successful are presented shortly analyzed terms performance tuning.