The Australian Astronomical Observatory’s (AAO’s) AESOP project is part of the Multi-Object Spectrograph Telescope (4MOST) system for the VISTA telescope. It includes the 2436-fibre positioner, space frame and electronics enclosures. The AESOP concept and the role of the AAO in the 4MOST project have been described in previous SPIE proceedings. The project final assembly stage has recently been completed. In this paper, key results in accurate manufacturing and assembly of critical AESOP components are discussed. The major performance requirement for AESOP is that all 2436 science fibre cores and 12 guide fibre bundles are to be re-positioned to an accuracy of 10 micron within 1 minute. With a fast prime-focus focal-ratio, a close tolerance of +/-70 microns on the axial position of the fibre tips must be held so efficiency does not suffer from de-focus losses. Positioning accuracy is controlled with the metrology cameras installed on the telescope, which measures the positions of the fibre tips to an accuracy of a few micrometers and allows iterative positioning until all fibre tips are within tolerance on the ultimate position. Maintaining co-planarity of the fibre tips requires accurate control in the assembly of several components that contribute to such errors. Overall, the AESOP design fully complies with all its requirements and in most cases achieves its goals. A thorough consideration of all the relevant interfaces during the design and assembly phases, has resulted in comprehensive set of ICDs for the mechanical, electrical and software aspects of AESOP.
The Australian Astronomical Observatory’s (AAO’s) AESOP project is part of the Multi-Object Spectrograph Telescope (4MOST) system for the VISTA telescope. It includes the 2436-fibre positioner, space frame and electronics enclosures. The AESOP concept and the role of the AAO in the 4MOST project have been described in previous SPIE proceedings. The project final assembly stage has been completed. In this paper, engineering principles applied during assembly of critical components and testing of the instrument are discussed. The major performance requirement for AESOP is that all 2436 science fiber cores and 12 guide fiber bundles are to be re-positioned to an accuracy of 10 micron within 1 minute. With a fast prime-focus focal-ratio, a close tolerance on the axial position of the fiber tips must be held so efficiency does not suffer from de-focus losses. Positioning accuracy is controlled with the metrology cameras installed on the telescope, which measures the positions of the fiber tips to an accuracy of a few micrometers and allows iterative positioning until all fiber tips are within tolerance on the focal surface plane. Maintaining co-planarity of the fiber tips requires accurate control in the assembly of several components that contribute to such errors. AESOP requires a consistent production of high accuracy components and assemblies in a quantity of above 2500 items. To achieve this, we had to apply the highest engineering standards, including assembly procedures, metrology, and control systems. We designed many jigs and fixtures, which enabled us to produce high quality components and assemblies at reasonable cost. The results – working instrument was vastly achieved with the help of university students after providing a training in engineering practices.
In this paper we present recent progress on the Australian Astronomical Observatory’s AESOP2 fiber positioner for 4MOST (on VISTA). As an evolution of the Echidna “spine” technology used for FMOS (on Subaru), AESOP has challenging requirements to position 2,448 fibers in parallel, within 1 minute, to an accuracy of < 10 um RMS. AESOP successfully passed ESO’s official final design review and manufacturing has commenced. We present performance results from the first batch of newly-manufactured positioners and also report on how the AESOP project is tracking in terms of schedule, budget and risk.
The Australian Astronomical Observatory’s (AAO’s) AESOP project is part of the 4 metre Multi-Object Spectrograph Telescope (4MOST) system for the VISTA telescope. It includes the 2436-fiber positioner, space frame and electronics enclosures. The AESOP concept and the role of the AAO in the 4MOST project have been described in previous SPIE proceedings. Prototype tests, which were completed early in 2017 demonstrated that the instrument requirements are satisfied by the design. The project final design stage has recently been completed. In this paper, key features of the AESOP positioning system design, along with the techniques developed to overcome key mechanical, electronic, and software engineering challenges are described. The major performance requirement for AESOP is that all 2436 science fiber cores and 12 guide fiber bundles are to be re-positioned to an accuracy of 10 µm within 1 minute. With a fast prime-focus focal-ratio, a close tolerance on the axial position of the fiber tips must be held so efficiency does not suffer from de-focus losses. Positioning accuracy is controlled with the metrology cameras installed on the telescope, which measures the positions of the fiber tips to an accuracy of a few µm and allows iterative positioning until all fiber tips are within tolerance. Maintaining co-planarity of the fiber tips requires accurate control in the assembly of several components that contribute to such errors. Assembly jigs have been developed and proven adequate for this purpose. Attaining high reliability in an assembly with many small components of disparate materials bonded together, including piezo ceramics, carbon fiber reinforced plastic, hardened steel, and electrical circuit boards, has entailed careful selection and application of cements and tightly controlled soldering for electrical connections.
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