Dr Rakich began his career in optics as an amateur telescope maker. In New Zealand there are no tertiary institutions offering degrees specializing in geometrical optics. Dr. Rakich had the good fortune to meet Norman Rumsey, a retired senior Scientist from a New Zealand Government Laboratory. Norman was looking for an “apprentice” to pass on something of his life-long knowledge of optics to, and Dr. Rakich, then 19 years old, was a willing study. With this grounding in optics, culminating in a Doctorate through the University of Canterbury, Dr. Rakich has had an interesting and varied career, travelling to most corners of the world working on telescopes, instrumentation and other optical devices and systems. Dr Rakich has had lead technical roles in Kiwistar Optics, EOS Space Systems, Large Binocular Telescope Observatory, European Southern Observatory and the Giant Magellan Telescope Observatory. In 2019 Dr Rakich returned to his home in New Zealand and began working as a consultant for his own company, Mersenne Optical Consulting. It is notable that among regular clients of Mersenne Optical Consulting are all of the companies and organizations mentioned above. Dr. Rakich has been first author on numerous scientific publications. Novel telescope alignment techniques and understanding of underlying fundamentals of optical design and geometrical aberration theory have resulted from this work. The so called “Paul-Rumsey” telescope, a flat-field three-mirror anastigmat with the same performance as the Paul-Baker telescope but with only one aspheric mirror is one example of innovation. Dr. Rakich is the technical leader of a multi-institutional effort to incorporate new technologies of multiple-fibre ADM interferometers into the alignment of the world’s largest telescopes. Through his consulting company, Dr. Rakich continues to provide technical leadership and support in the areas of optical design and analysis, precision alignment, optical fabrication and metrology.
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MORFEO, formerly known with the acronym MAORY, is the Multi-Conjugated Adaptive Optics (MCAO) module for the European Extremely Large Telescope (ELT). MORFEO is designed to feed the Near Infrared (NIR) camera MICADO with both MCAO and Single-Conjugated AO (SCAO) operation modes. The optical configuration provides a one to one imaging of the telescope focal surface on two ports (one feeding MICADO and the other dedicated to a future instrument) and it is equipped with two post-focal deformable mirrors together with the Laser Guide Star (LGS) and Natural Guide Star (NGS) channels for wavefront sensing and tomographic reconstruction.
In this paper, we present the status of the optical configuration at the completion of the Preliminary Design Review (PDR). We will focus our attention on the tolerance analysis of the elements, consisting in both manufacturing and alignment, to provide the expected performances of the instrument after initial integration. We will also present the outcomes of the stability analysis of the instrument, consisting in rigid-body motions and thermoelastic deformations of the structure and optomechanics, used to define the procedures and benchmark to maintain the instrument performances during operation. Details on the integrated modelling, specifically developed for this purpose, will be provided.
Since 2016 GMT have been developing a telescope metrology system, that is intended to close the gap between openloop modelling and AGWS operations. A prototyping campaign was initiated soon after receipt of laser metrology hardware in 2017. This campaign is being conducted in collaboration with the Large Binocular Telescope Observatory (LBTO), and hardware was first deployed on the LBT in August 2017. Since that time the system had been run and developed over some hundreds of hours on-sky. It has been shown to be capable of reliably measuring the relative positions of the main optics over ~ 10 m to a repeatability of ~ 1-2 microns RMS. This paper will describe the prototyping campaign to date, the basic design of the system, lessons learned and results achieved. It will conclude with a discussion of future prototyping efforts.
The project is developing a Telescope Metrology System (TMS) which incorporates a large number of absolute distance measuring interferometers. The system will align optical components of the telescope to the instrument interface to (well) within the capture range of the active optics wavefront sensing systems. The advantages offered by this technological approach to a TMS, over a network of laser trackers, are discussed. Initial investigations of the Etalon Absolute Multiline Technology™ by Etalon Ag4 show that a metrology network based on this product is capable of meeting requirements. A conceptual design of the system is presented and expected performance is discussed.
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