Mr. Ockert J. Strydom Profile

Ockert J. Strydom

at South African Astronomical Observatory

SPIE Involvement:

Author

Publications (19)

Proceedings Article | 13 December 2020 Poster + Presentation + Paper

A dual-beam spectrograph design for transient follow-up with SALT

Janus Brink, Ockert Strydom, Melanie Saayman, John Menzies

Proceedings Volume 11447, 1144768 (2020) https://doi.org/10.1117/12.2560996

KEYWORDS: Spectrographs, Received signal strength, Astronomy, Spectroscopy, Large Synoptic Survey Telescope, Optical instrument design, Large telescopes, Beam splitters, Spectral resolution, Cameras

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Proceedings Article | 10 July 2018 Paper

A high-efficiency low-resolution spectrograph design for SALT

Janus Brink, Ockert Strydom, Magaretha Pretorius, Petri S. Vaisanen

Proceedings Volume 10706, 107066H (2018) https://doi.org/10.1117/12.2313130

KEYWORDS: Sensors, Telescopes, Spectrographs, Spherical lenses, Mirrors, Spectroscopy, Astronomy, Observatories, Optical design, Large telescopes

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Proceedings Article | 10 July 2018 Paper

Performance of the updated Southern African Large Telescope prime-focus guidance system

Janus Brink, Ockert Strydom, Stephen Hulme, Anthony Koeslag, Deneys Maartens, Keith R. Browne, Eben Wiid

Proceedings Volume 10706, 1070668 (2018) https://doi.org/10.1117/12.2313120

KEYWORDS: Telescopes, Sensors, Imaging systems, Control systems, Stars, Received signal strength, Prisms, Beam splitters, Motion controllers

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Proceedings Article | 6 July 2018 Paper

Image processing for a pyramid wavefront sensor equipped guide probe on SALT

Anthony Koeslag, Janus Brink, Deneys Maartens, Stephen Hulme, Ockert Strydom

Proceedings Volume 10707, 107072M (2018) https://doi.org/10.1117/12.2313142

KEYWORDS: Stars, Image processing, Telescopes, Received signal strength, Cameras, Wavefront sensors, Prisms, Mirrors, Observatories, Waveguides

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A new guide probe, using a Pyramid WaveFront Sensor (PWFS), has been built for the guider port of the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope (SALT). The PWFS splits the light from a guide star into a double image of the star at the guider image plane. These two images move with respect to each other with changes in focus. Analysis of the movements in such two-star images allows for simultaneous tracking and focus adjustments while guiding. This paper describes the image processing software developed for the new guidance system. The PWFS is a custom made prism with a 9 degree prism apex angle. Incident light is split as it passes through the prism resulting in two images identical in shape, size and orientation resolving at the guider image plane. A point source, like a star, thus appears as a double image of the star at the image plane. These two images are affected identically with seeing fluctuations allowing one or both images to be used to calculate guidance offsets independently of the focus measurement. The separation of the two images correlates to the focus divergence from the ideal which is used to correct the telescope focus. The prism can be moved off to one side, such that the incident light is not split. In this configuration the guide probe provides guidance offsets without the focus adjustments for maximum sensitivity with dim guide. The software was developed using existing guider images to ensure that the algorithm could handle the image artefacts that are commonly encountered. To reduce processing time and the effects of anomalies the surrounding image is masked out leaving only the star. A centroiding algorithm is then applied to the star to estimate its location in the image. For PWFS double-star images, Zemax was used to model the effect of shifting focus on the light passing through the prism. From this a simulated data set was produced and the software expanded to detect the two stars and measure the separation. The software is capable of measuring star translational movements and double star separation reliability and accurately.

Proceedings Article | 18 August 2016 Paper

SALT tracker upgrade utilizing aerospace processes and procedures

Keith Browne, Raoul van den Berg, Chris Coetzee, Ockert Strydom, Janus Brink, Eben Wiid, Wouter Lochner, Grant Nelson, Paul Rabe, Martin Wilkinson, Vic Moore, Adelaide Malan, Jonathan Love, Anthony Koeslag

Proceedings Volume 9911, 99111J (2016) https://doi.org/10.1117/12.2231559

KEYWORDS: Aerospace engineering, Telescopes, Safety, Mechanical engineering, Manufacturing, Computer aided design, Design for manufacturability, Inspection, Actuators, Finite element methods

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Proceedings Article | 8 August 2016 Paper

SALT: Active control of the primary mirror with inductive edge sensors

Hitesh Gajjar, John Menzies, Chris Coetzee, Ockert Strydom, Jonathan Love, Keith Browne, Deon Bester, David Buckley

Proceedings Volume 9906, 990639 (2016) https://doi.org/10.1117/12.2234264

KEYWORDS: Sensors, Telescopes, Mirrors, Environmental sensing, Humidity, Simulation of CCA and DLA aggregates, Temperature metrology, Control systems, Transmitters, Actuators

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Proceedings Article | 22 July 2016 Paper

A new modular guidance system for the Southern African Large Telescope

Janus Brink, Stephen Hulme, Anthony Koeslag, Deneys Maartens, Martin Wilkinson, Keith Browne, Eben Wiid, Raoul van den Berg, Wouter Lochner, Ockert Strydom

Proceedings Volume 9912, 99125F (2016) https://doi.org/10.1117/12.2231407

KEYWORDS: Optical design, Control systems, Optical design, Control systems design, Received signal strength, Telescopes, Computer programming, Sensors, Prisms, Imaging systems, Cameras

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Proceedings Article | 22 July 2016 Paper

Transmission and opto-mechanical performance of the liquid lens coupling in the Robert Stobie Spectrograph on SALT

Ockert Strydom, Wouter Lochner, Janus Brink, Darragh O'Donoghue, Éric Depagne, Martin Wilkinson, Jonathan Love, Lisa Crause, Kenneth Nordsieck, J. Alan Schier

Proceedings Volume 9912, 99123D (2016) https://doi.org/10.1117/12.2232243

KEYWORDS: Liquid lenses, Absorption, Liquids, Spectrographs, Received signal strength, Collimators, Reflectivity, Ultraviolet radiation, Ocean optics, Optical testing

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Proceedings Article | 22 July 2016 Paper

Results from bonding of the SALT primary mirror edge sensors

Ockert Strydom, Hitesh Gajjar, Jonathan Love

Proceedings Volume 9912, 991244 (2016) https://doi.org/10.1117/12.2233101

KEYWORDS: Sensors, Mirrors, Mirrors, Humidity, Connectors, Tolerancing, Adhesives, Telescopes, Image segmentation, Environmental sensing, Nanotechnology

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Proceedings Article | 15 July 2016 Paper

Worth its SALT: four years of full science operations with the Southern African Large Telescope

Janus Brink, Thea Koen, Paul Kotze, Alexei Kniazev, Éric Depagne, Brent Miszalski, Encarni Romero Colmenero, Theodore Williams, Veronica Van Wyk, Petri Väisänen, Chris Coetzee, David Buckley, Steve Crawford, Anja Schroeder, Ockert Strydom, Fred Marang

Proceedings Volume 9910, 99100T (2016) https://doi.org/10.1117/12.2232873

KEYWORDS: Observatories, Large telescopes, Telescopes, Gemini Observatory, Mirrors, Coating, Adaptive optics, Gemini Planet Imager, Turbulence, Structural engineering

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Proceedings Article | 11 July 2016 Paper

Monitoring the performance of the Southern African Large Telescope

Deneys Maartens, Keith Browne, Ockert Strydom, David De Bruyn, Christian Hettlage, Chris Coetzee, Petri Väisänen, Encarni Romero Colmenero, Steven Crawford, Paul Kotze, Paul Rabe, Stephen Hulme, Janus Brink

Proceedings Volume 9910, 99102M (2016) https://doi.org/10.1117/12.2230484

KEYWORDS: Telescopes, Large telescopes, Astronomical telescopes, Efficient operations, Automatic tracking

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Proceedings Article | 7 August 2014 Paper

Commissioning the SALT fiber instrument feed

Eben Wiid, Janus Brink, Ockert Strydom, Darragh O'Donoghue

Proceedings Volume 9151, 915121 (2014) https://doi.org/10.1117/12.2055943

KEYWORDS: Computer programming, Telescopes, Cameras, Stars, Human-machine interfaces, Target acquisition, Motion models, Imaging systems, Motion controllers, Control systems

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Proceedings Article | 24 July 2014 Paper

Performance of the Southern African Large Telescope (SALT) High Resolution Spectrograph (HRS)

Lisa Crause, Ray Sharples, David Bramall, Jürgen Schmoll, Paul Clark, Eddy Younger, Luke Tyas, Éric Depagne, Janus Brink, Ockert Strydom, Steven Crawford, Sean Ryan, Martin Wilkinson, David Buckley

Proceedings Volume 9147, 91476T (2014) https://doi.org/10.1117/12.2055635

KEYWORDS: Spectrographs, Stars, Spectral resolution, Mirrors, Calibration, Telescopes, Iodine cells, Large telescopes, Lawrencium, Cameras

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SPIE Journal Paper | 11 February 2013

Resolving the Southern African Large Telescope’s image quality problems

Darragh O'Donoghue, Lisa Crause, James O'Connor, Francois Strumpfer, Ockert Strydom, Craig Sass, Janus Brink, Charl du Plessis, Eben Wiid, Jonathan Love

OE, Vol. 52, Issue 08, 081604, (February 2013) https://doi.org/10.1117/12.10.1117/1.OE.52.8.081604

KEYWORDS: Mirrors, Telescopes, Monochromatic aberrations, Computer generated holography, Interfaces, Large telescopes, Image quality, Stars, Cameras, Optical testing

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Proceedings Article | 17 September 2012 Paper

A happy conclusion to the SALT image quality saga

Chris Coetzee, Lisa Crause, Charl du Plessis, Janus Brink, Eben Wiid, Jonathan Love, Martin Wilkinson, James O'Connor, Ockert Strydom, Darragh O'Donoghue, Craig Sass, Francois Strumpfer

Proceedings Volume 8444, 84444I (2012) https://doi.org/10.1117/12.924997

KEYWORDS: Mirrors, Telescopes, Stars, Computer generated holography, Image quality, Interfaces, Optical testing, Autocollimators, Aluminum, Monochromatic aberrations

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Proceedings Article | 20 July 2010 Paper

Cleaning the Southern African Large Telescope's M5 mirror

James O'Connor, Ockert Strydom, Lisa Crause, Francois Strümpfer, Darragh O'Donoghue, David A. Buckley, Peter Gillingham, Hitesh Gajjar, Jonathan Love

Proceedings Volume 7739, 77393Z (2010) https://doi.org/10.1117/12.856795

KEYWORDS: Mirrors, Laser sintering, Telescopes, Reflectivity, Sodium, Optical coatings, Monochromatic aberrations, Inspection, Polymer thin films, Polymers

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Proceedings Article | 19 July 2010 Paper

Saving SALT: repairs to the spherical aberration corrector of the Southern African Large Telescope (SALT)

James O'Connor, Janus Brink, Lisa Crause, Francois Strumpfer, Darragh O'Donoghue, Ockert Strydom, Eben Wiid, Eli Atad-Ettedgui, Craig Sass

Proceedings Volume 7739, 77390Q (2010) https://doi.org/10.1117/12.856239

KEYWORDS: Telescopes, Mirrors, Computer generated holography, Monochromatic aberrations, Interfaces, Image quality, Optical alignment, Optical testing, Large telescopes, Cameras

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Proceedings Article | 23 July 2008 Paper

The image quality of the Southern African Large Telescope (SALT)

Craig Sass, Fred Marang, Charl du Plessis, Yas Hashimoto, Janus Brink, Encarni Romero-Colmenero, Alexei Kniazev, Martin Still, Willie Koorts, James O'Connor, Johann Du Toit, Darragh O'Donoghue, Luis Balona, Hitesh Gajjar, Sandisa Siyengo, John Booth, Anthony Koeslag, Arkadiusz Swat, J. Christopher Clemens, Martyn Wells, Lucian Botha, Steven Crawford, Lisa Crause, Eli Atad-Ettedgui, Bruce Bigelow, Ockert Strydom, Geoffrey Evans, Hannah Worters, Lawrence Ramsey, Alrin Christians, David Buckley, Ramotholo Sefako, Johann Scholtz, Nicola Loaring, Douglas Metcalfe, Phil Charles, Herman Kriel, Brennan Meyer, Petri Vaisanen, Malcolm Hendricks, Jonathan Love

Proceedings Volume 7018, 701813 (2008) https://doi.org/10.1117/12.788841

KEYWORDS: Mirrors, Telescopes, Monochromatic aberrations, Image quality, Cameras, Simulation of CCA and DLA aggregates, Image segmentation, Wavefront sensors, Wavefronts, Interfaces

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Proceedings Article | 23 July 2008 Paper

Automated CO2 cleaning system for the SALT primary mirror

Hitesh Gajjar, Ockert Strydom, Charl du Plessis, Herman Kriel

Proceedings Volume 7018, 70181P (2008) https://doi.org/10.1117/12.787781

KEYWORDS: Carbon dioxide, Mirrors, Control systems, Safety, Liquids, Telescopes, Switches, Interfaces, Human-machine interfaces, Computing systems

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Showing 5 of 19 publications

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