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3 February, 2020
Progress on the New WHT Prime Focus Rotator and Corrector Systems for WEAVE
During the stand-down last November, the new rotator system was successfully integrated within the WEAVE Prime Focus Assembly, and then mounted on the WHT top-end where an exhaustive campaign of tests took place over several weeks. The main objective was to mechanically align the rotator with the optical axis of the WHT primary mirror. This ensures that the sky map is always centred on the telescope axis, in order to optimise the image quality and throughput of light for the stars in the instrument focal plane. This alignment was performed using a laser-tracker metrology system, with targets placed all around the telescope. Finally, the high-level control system of the new rotator was successfully integrated within the WHT main Telescope Control System.
WEAVE Prime Focus Assembly being lifted to the top-end. Large format: PNG.
Members of the ING Board and staff in front of the Prime Focus assembly. Large format: PNG.
In December 2019, an extensive inspection of the WEAVE Prime Focus Corrector Lens L1 (polished by KiwiStar, New Zealand) began at SENER's premises in Barcelona. The lens (photograph below) was mounted in a customised holder, developed by SENER Aeroespacial, allowing it to be rotated.
L1 lens being inspected at SENER in Barcelona. Acknowledgement: FEDER. Credit: SENER Aeroespacial. Large format: PNG.
The team responsible for the lens inspection at SENER, including ING's optical engineer Emilie Lhomé. Acknowledgement: FEDER. Credit: SENER Aeroespacial. Large format: PNG.
The lens has a diameter of 1.1 meter and is made of fused silica. It is the entrance lens for the WEAVE Prime Focus Corrector System, composed of 6 large lenses, that will be assembled and delivered to ING in the coming months.
Optical layout of WEAVE's Prime Focus Corrector (PFC) System. The purpose of the WEAVE PFC is to correct for the optical aberrations in the two-degree field-of-view. It includes an Atmospheric Dispersion Corrector (ADC), comprising two pairs of counter-rotating air-separated doublets, to compensate for atmospheric dispersion as the elevation of the telescope changes. Large format: PNG.
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