Mr. Marvin F. Campbell Profile

Marvin F. Campbell

Retired / Consultant at MF Campbell Consulting

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Author

Publications (5)

Proceedings Article | 27 July 2016 Paper

Pre-construction progress of giant steerable science mirror for TMT

Fei Yang, Hongchao Zhao, Qichang An, Peng Guo, Haibo Jiang, Linchu Han, Virginia Ford, Glen Cole, Byron Smith, Marvin Campbell

Proceedings Volume 9906, 99064M (2016) https://doi.org/10.1117/12.2232068

KEYWORDS: Thirty Meter Telescope, Mirrors, Prototyping, Telescopes, Polishing, Optical fabrication, Interfaces, Calibration, Motion measurement, Surface finishing

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The Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) team is developing the Giant Steerable Science Mirror (GSSM) for Thirty Meter Telescope (TMT) which will enter the preliminary design phase in 2016. The GSSM is the tertiary mirror of TMT and consists of the world’s largest flat telescope mirror (approximately 3.4m X 2.4 m X 100mm thick) having an elliptical perimeter positioned with an extremely smooth tracking and pointing mechanism in a gravity-varying environment. In order to prepare for developing this unique mirror system, CIOMP has been developing a 1/4 scale, functionally accurate version of the GSSM prototype during the pre-construction phase of GSSM. The prototype will incorporate the same optomechanical system and servo control system as the GSSM. The size of the prototype mirror is 898.5mm×634mm×12.5mm with an elliptical perimeter. The mirror will be supported axially by an 18 point whiffletree and laterally with a 12 point whiffletree. The main objective of the preconstruction phase includes requirement validation and risk reduction for GSSM and to increase confidence that the challenge of developing the GSSM can be met. The precision mechanism system and the optical mirror polishing and testing have made good progress. CIOMP has completed polishing the mirror, the prototype mechanism is nearly assembled, some testing has been performed, and additional testing is being planned and prepared. A dummy mirror is being integrated into the cell assembly prototype to verify the design, analysis and interface and will be used when testing the prototype positioner tilt and rotation motions. The prototype positioner tilt and rotator structures have been assembled and tested to measure each subsystem’s jitter and dynamic motion. The mirror prototype has been polished and tested to verify the polishing specification requirement and the mirror manufacturing process. The complete assembly, integration and verification of the prototype will be soon finished. Final testing will verify the prototype requirements including mounted mirror surface figure accuracy in 5 different orientations; rotation and tilt motion calibration and pointing precision; motion jitter; and internally generated vibrations. CIOMP has scheduled to complete the prototype by the end of July 2016. CIOMP will get the sufficient test results during the pre-construction phase to prepare to enter the preliminary design for GSSM.

Proceedings Article | 22 July 2014 Paper

Wheel drives for large telescopes: save the cost and keep the performance over hydrostatic bearings

Marvin Campbell

Proceedings Volume 9145, 91452H (2014) https://doi.org/10.1117/12.2056624

KEYWORDS: Servomechanisms, Telescopes, Control systems, Optical instrument design, Antennas, Radar, Computer programming, Teeth, Radio telescopes, Electroluminescence

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The use of steel wheels on steel tracks has been around since steel was invented, and before that it was iron wheels on iron tracks. Not to be made obsolete by the passage of time, this approach for moving large objects is still valid, even optimal, but the detailed techniques for achieving high performance and long life have been much improved. The use of wheel-and-track designs has been very popular in radio astronomy for the largest of the large radio telescopes (RT), including such notables as the 305m Arecibo RT, the 100m telescopes at Effelsberg, Germany (at 3600 tonnes) and the Robert C. Byrd, Greenbank Telescope (GBT, 7600 tonnes) at Greenbank, West Virginia. Of course, the 76m Lovell Telescope at Jodrell Bank is the grandfather of all large aperture radio telescopes that use wheel drives. Smaller sizes include NRAO’s Very Long Baseline Array (VLBA) telescopes at 25m and others. Wheel drives have also been used on large radars of significance such as the 410 tonne Ground Based Radar-Prototype (GBR-P) and the 150 foot (45.7m) Altair Radar, and the 2130 tonne Sea Based X-Band Radar (SBX). There are also many examples of wheel driven communications antennas of 18 meters and larger. All of these instruments have one thing in common: they all use steel wheels that run in a circle on one or more flat, level, steel tracks.

This paper covers issues related to designing for wheel driven systems. The intent is for managing motion to sub arc-second levels, and for this purpose it is primary for the designer to manage measurement and alignment errors, and to establish repeatability through dimensional control, structural and drive stiffness management, adjustability and error management. In a practical sense, there are very few, if any, fabricators that can machine structural and drive components to sufficiently small decimal places to matter. In fact, coming within 2-3 orders of magnitude of the precision needed is about the best that can be expected. Further, it is incumbent on the design team to develop the servo control system features, correction algorithms and structural features in concert with each other. Telescope designers are generally adept at many of these practices, so the scope of this paper is not that, but is limited to those items that pertain to a precision wheel driven system.

Proceedings Article | 29 September 2004 Paper

Critical wind effects on parabolic reflectors

Marvin Campbell

Proceedings Volume 5495, (2004) https://doi.org/10.1117/12.552352

KEYWORDS: Reflectors, Antennas, Control systems, Aerodynamics, Servomechanisms, Radio telescopes, Optical instrument design, Wind energy, Lead, Picture Archiving and Communication System

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Proceedings Article | 4 February 2003 Paper

SOAR 4.2-m telescope: evolution of drive and pointing performance from early predictions to final testing

Marvin Campbell, Edward Reese

Proceedings Volume 4837, (2003) https://doi.org/10.1117/12.456985

KEYWORDS: Telescopes, Computer programming, Electroluminescence, Control systems design, Control systems, Optical instrument design, Statistical analysis, Servomechanisms, Motion models, Safety

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Proceedings Article | 2 August 2000 Paper

Structural optimization and modeling of large dynamic structures for controls simulation

Tim Campbell, Adel Elsaie

Proceedings Volume 4004, (2000) https://doi.org/10.1117/12.393938

KEYWORDS: Control systems, Antennas, Structural design, Optimization (mathematics), Astronomy, Systems modeling, Complex systems, Structural dynamics, Device simulation, Astronomical imaging

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