OPTICON FP7 (2013-2016) WP5 - Freeform Active Mirror Experiment (FAME)

WP leader: Lars Venema (ASTRON)

Future extremely large ground based telescopes like the E-ELT require an increase in sampling density that drives the scale of the optics and their requirements. Instruments based on current designs tend to get bigger and more complex, leading to increasingly tight requirements on the overall performance . We aim to reduce the system size and thus the overall instrument weight, size and cost, while increasing performance in terms of spatial and spectral resolution. This can in part be realised by the introduction of Active Freeform Mirrors (AFMs). In the previous OPTICON FP7 contract we have developed optical design tools and evaluated possible manufacturing processes to produce AFMs. The team has also successfully designed an active and highly aspherical optical components (Freeform Mirror). At this stage, the technology appears to be very promising and justifies further development. Our objective now is to reduce the complexity of future instruments by combining two innovative technologies namely: freeform mirrors and active optics to produce AFMs. By making use of AFMs it may be possible to reduce the cost, size and mass of complex multi-object spectrographs (MOS) such as EAGLE or OPTIMOS. This would happen by reducing the number of mirrors in the optical train, while maintaining the instrument performance and stability by using an active structure. The successful freeform optical design funded by our previous FP7 contract will be further utilised and a complete prototype will be produced and fully tested. Comparing to existing active mirrors technologies, the primary goal of this development is to design components which are inherently stable over a wide range of environmental conditions. Under this work package various methodologies will be evaluated in terms of performance, cost effectiveness and ease of production.