The segmented mirror active optics technology is one of the key technologies for the extremely large telescope, while edge sensor is one of the essential core components of active optics for the co-phasing maintenance of all segmented mirrors. The main properties of these edge sensors are of high precision of nanometers, high linearity, and low sensitivity to temperature and humidity fluctuations as well as high reliability. This paper presents an eddy current edge sensor design developed cooperatively by Nanjing Institute of Astronomical Optics and Technology and University of Science and Technology of China. The stage work performance results of eddy current sensor prototype under representative operational conditions are also presented.
Extremely large telescopes with more and more large apertures are pursued, proposed and constructed by astronomers and technicians all over the world in the coming next years to satisfy the great demand of scientific progress. Segmented mirror active optics is the most important technology to co-phase the large primary for optically perfect segmentation. Based the experimental platform and test work in Nanjing Institute of Astronomical Optics and Technology in China, we introduce the latest co-phasing progress on fine segment support, edge sensor and close-loop co-phasing correction in China in this paper. Finally some conclusions are given based on the test results.
Edge sensor is one of the most important technologies for the extremely large segmented primary telescopes like Keck, Thirty Meter Telescope (TMT), European Extremely Large Telescope (E-ELT) and Chinese Future Giant Telescope (CFGT) for control of out-of-plane degrees of freedom. Different from the capacity edge sensor from Keck and TMT, one kind of an inductance edge sensor is proposed and applied with the similar principle and configuration, fine aligned and tested in this paper to try to realize the same co-focusing or co-phasing maintenance purpose and high accuracy of relative piston and tip/tilt degrees of freedom of the segments. The sensor is also considered and modified to much more sensitive to dihedral angle between the neighboring segments. Finally some preliminary conclusions are reached.
A telescope with a larger primary mirror can collect much more light and resolve objects much better than one with a
smaller mirror, and so the larger version is always pursued by astronomers and astronomical technicians. Instead of using
a monolithic primary mirror, more and more large telescopes, which are currently being planned or in construction, have
adopted a segmented primary mirror design. Therefore, how to sense and phase such a primary mirror is a key issue for
the future of extremely large optical/infrared telescopes. The Dispersed Fringe Sensor is a non-contact method using
broadband point light sources and it can estimate the piston by the two-directional spectrum formed by the transmissive
grating's dispersion and lenslet array. In this paper we introduce you the current research progress of the successful
design, construction and alignment of our dispersed Hartmann sensors together with its design principles and simulations
for indoor segmented mirror experiment system and outdoor segmented mirror experiment system. We also conduct
many successful real phasing tests and phasing corrections in the visible waveband using our existing indoor and outdoor
segmented mirror optics platform. Finally, some conclusions are reached based on the test and correction of experimental