Mr. Michael Thomakos Profile

Michael Thomakos

at Australian Astronomical Optics Macquarie Univ

SPIE Involvement:

Author

Publications (3)

Proceedings Article | 29 August 2022 Poster + Paper

Vacuum adhesion of Starbug fibre optic positioning robots in high-altitude ground-based astronomy instrumentation

Ellie O'Brien, Jon Lawrence, Celestina Lacombe, Michael Thomakos, Michael Goodwin, James Gilbert, Slavko Mali, Rolf Muller, Nirmala Kunwar, Jahanzeb Zahoor, Lew Waller, Tony Farrell

Proceedings Volume 12182, 1218237 (2022) https://doi.org/10.1117/12.2629158

KEYWORDS: Telescopes, Green fluorescent protein, Observatories, Robots, Fiber optics, Ferroelectric materials, Astronomy, Stellar astronomy, Liquid crystal on silicon, Glasses

Read Abstract +

Starbugs are self-motile fibre optic positioning robots developed by AAO-MQ. MANIFEST (MANy Instrument FibrE SysTem) is a facility class Instrument which will operate up to 900 Starbugs on the Giant Magellan Telescope (GMT). The FOBOS (Fibre-Optic Broadband Optical Spectrograph) Fibre Positioner is a facility class Instrument which will operate up to 1800 Starbugs on the Keck Telescope. Starbugs deliver an optical payload to the location of an astronomical object on the telescope focal plane. The Starbugs are made from a pair of concentric Piezoceramic Tubes (PZT), and a high-voltage waveform is applied to the PZT to create an actuation. Staging of the waveform creates successive microsteps, on the order of 3-20 μm each, at a driven frequency of 100Hz. The Starbugs are adhered to the Glass Field Plate (GFP) using an ancillary vacuum system, which must provide sufficient adhesion force to maintain the Starbug GFP position in the high-altitude environmental conditions at Mauna Kea (MKO) and Las Campanas Observatory (LCO) sites. The minimum vacuum adhesion requirements to achieve Starbug GFP position were used to specify the vacuum pump flow rate and operational head pressure. The vacuum adhesion requirements were experimentally obtained using the Starbug Test Stand, located in Sydney, Australia. The Starbugs Test Stand vacuum adhesion requirements were parametised for dry air mass flow rate and head pressure, and then corrected for the 95th percentile environmental conditions at MKO and LCO. The vacuum system numerical model was verified by the TAIPAN instrument. When corrected for ambient atmospheric conditions at the UK Schmidt Telescope (Siding Spring Observatory, Australia), the numerical model could predict the steady state vacuum pump speed with 1.29% variation from the measured vacuum pump speed recorded by the TAIPAN Instrument control software. This capability of the numerical model will be used for real-time condition monitoring of the Starbugs Instruments.

Proceedings Article | 29 August 2022 Poster + Paper

Development of the FOBOS focal plane positioner

David Adams, Jon Lawrence, Helen McGregor, Ellie O'Brien, Celestina Lacombe, Nuria Lorente, Michael Goodwin, Rebecca Brown, Michael Thomakos, Tayyaba Zafar, Nick MacDonald, Kyle Westfall, Kevin Bundy, Renate Kupke, Marc Kassis, Claire Poppett

Proceedings Volume 12184, 121846K (2022) https://doi.org/10.1117/12.2627289

KEYWORDS: Galactic astronomy, Spectrographs, Robots, Spectroscopy, Optical fibers, Glasses, Astronomical imaging, Telescopes

Read Abstract +

Proceedings Article | 26 August 2022 Poster + Paper

A Starbug's life: a material trade study using fatigue life criteria for high-altitude robotic fibre positioning instruments

Ellie O'Brien, Jon Lawrence, Celestina Lacombe, Michael Thomakos, Michael Goodwin, James Gilbert, Slavko Mali, Rolf Muller, Nirmala Kunwar, Jahanzeb Zahoor, Lew Waller, Tony Farrell

Proceedings Volume 12182, 1218236 (2022) https://doi.org/10.1117/12.2629152

KEYWORDS: Ferroelectric materials, Green fluorescent protein, Electrodes, Telescopes, Mechanics, Safety, Roads, Observatories, Robots, Robotics

Read Abstract +

Starbugs are self-motile fibre optic positioning robots developed by AAO-MQ. The MANIFEST (MANy Instrument FibrE SysTem) is a facility class Instrument which will operate up to 900 Starbugs on the Giant Magellan Telescope (GMT). The FOBOS (Fibre-Optic Broadband Optical Spectrograph) Fibre Positioner is a facility class Instrument which will operate up to 1800 Starbugs on the Keck Telescope. The Starbugs deliver an optical payload to the location of an astronomical object on the telescope focal plane. The Starbugs are made from a pair of concentric Piezoceramic Tubes (PZT), and a high-voltage waveform is applied to the PZT to create an actuation. Staging of the waveform creates successive microsteps, on the order of 3-20 μm each, at a driven frequency of 100Hz. The Starbugs are adhered to the Glass Field Plate (GFP) using an ancillary vacuum system. The Starbugs have an airtight vacuum sealing component between the PZT and the GFP, called Slippers, which serve as a traction surface against the polished GFP. The Slippers set the science fibre focus offset, which has functional requirements that trace to Observatory level requirements. The Slipper components are subject to non-zero centred fully reversed fatigue loading due to the combined load case of the vacuum induced compression and the shear load of the PZT actuation as the Starbug completes the step. The contact interface between the Slipper and the GFP is subject to surface fatigue and functions as a sacrificial wear surface to ensure the longevity of both the PZT and the optical payload. The fatigue life behaviour of the Slipper, with particular interest on this interface, was defined using industry standard methods and informed the trade study to select the appropriate material for the Slippers to survive a nominal period on-sky (fatigue life). The trade study terms were vacuum sealing ability as a function of mechanical hardness versus fatigue life (108 cycles). Several suitable materials were identified and will be physically prototyped, with results reported in this manuscript.

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