Abstract Details
| Name: Varun Kumar Affiliation: Indian Institute of Astrophysics Conference ID: ASI2016_489 Title : An Inductive Edge Sensor for Segmented Mirror Telescope Authors and Co-Authors : Padmakar Singh Parihar Abstract Type : Poster Abstract Category : Instrumentation and Techniques Abstract : Edge sensor is a vital component of any segmented mirror telescope (SMT) and their performances highly depend on the performance of edge sensor. In order to achieve very high spatial resolution and sensitivity, all mirror segments of SMT’s must be precisely positioned with respect to each other to form a single primary mirror. Capacitance based displacement sensors are widely used for this purpose, but they have inherent sensitivity towards humidity and dust, which makes them unsuitable for telescopes installed at low altitude and humid regions. Whereas, inductance based sensors produce promising results in such situations. These inductance based sensors works on the principle of mutual inductance variation between two planar inductors. There are number of requirements for the sensor, such as very high sensitivity, temporal stability, immunity toward environmental changes, low noise as well as ability to probe more than one dimension. We have used COMSOL multi-physics for design and analysis of planar coils, required for inductive sensor. Effect of shape of the coil, trace geometry and density, number of coils in transmitter and receivers, current in the transmitters etc. are the design parameters deciding the sensitivity, range and sensing dimensions. The goal is to design and develop an inductive edge sensor which should have high sensitivity to piston, gap and tilt as well as having large sensing range with few nanometer precision. After optimizing the design, these coils are fabricated on flexible polyimide substrate by making use of classical PCB manufacturing technology. Flexible coils bonded on low thermal expansion glass blocks ensure very high thermal stability, which is one of the critical requirements for any edge sensor. In addition to the sensor, FPGA based sensing electronics has also been designed and developed. In this paper we report results related to sensor design and analysis, describe the sensor manufacturing process and related electronics. Finally we explain sensor calibration procedures and report preliminary results related to the performance. |