We report on progress at the University of Hawaii on the integration and testing setups for the adaptive secondary mirror (ASM) for the University of Hawaii 2.2-meter telescope on Maunakea, Hawaii. We report on the development of the handling fixtures and alignment tools we will use along with progress on the optical metrology tools we will use for the lab and on-sky testing of the system.
A consortium of industrial and academic partners, coordinated by TNO, is working on the realization of a 620mm adaptive secondary mirror (ASM) for the University of Hawaii’s 2.2-meter telescope [1][2][3]. The ASM consists of a 620mm-diameter slumped convex aspherical mirror shell, manipulated by 210 variable-reluctance actuators mounted on a light-weighted support frame. The mirror shell is manufactured to the required accuracy at low cost through slumping. The actuators are driven by dedicated PWM current drivers and commanded through a real-time FPGA-based interface. After successful performance testing of several laboratory prototypes[4], this project will provide the definitive on-sky demonstration of this new technology. We report on the manufacturing and testing of the major subsystems, and on the integration status of the ASM as a whole.
An adaptive secondary mirror (ASM) is currently being developed for the UH2.2 telescope, consisting of a slumped 620mm convex aspherical facesheet, manipulated by 210 variable-reluctance actuators and supported on a silicon aluminium alloy support structure. The total power dissipation of the actuators is expected to be under 3 Watts. The ASM will weigh around 55kg, which is about 15kg lighter than the original passive secondary mirror (M2). We present the design, breadboarding activities and manufacturing status of this adaptive mirror. The project is on track for delivery of the ASM in Hawaii in the middle of 2021.
In April 2018, VDL signed the contract to deliver more than 900 Primary Mirror Support frames for the 39-meter diameter ELT to ESO. Obviously, the M1 structure is a rather complex module. Because of the extreme output specifications (25 nanometer surface form accuracy of 133 slightly different mirror shapes and positions), as well as the required serviceability and reliability over decades of planned operation, the module truly is an engineering masterpiece. This appears to be the first time in large infrastructure-based astronomy history that a supply chain is set up to manage an order of this magnitude of highly complex M1 support structures. VDL together with its development partners TNO and NOVA has taken up this challenge.
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