Abstract
To expand field of view (FOV) of telescope, the method of special scanning often is used, but, for some telescopes with special structure in optics and machine, the conventional scanning methods are unsuitable. This paper proposes a novel scanning method based on autoguiding system so as to expand the FOV of fiber array solar optical telescope (FASOT) in possession of the special structure in optics and machine. Meanwhile, corresponding experiments are conducted in the FASOT prototype, FASOT-1B, in order to demonstrate that, for both FASOT and FASOT-1B, the proposed scanning method is feasible. First of all, on the basis of the software and hardware characteristics of FASOT and FASOT-1B, the three key technologies related to the proposed scanning method are described: quickly locating and pointing the first scanning step, the closed-loop controlling of multistep scanning, and the disturbance suppression of every scanning step based on Kalman filter. Afterwards, experiments are conducted and corresponding results show that the proposed scanning method is robust for the random disturbances forced on every scanning step and able to meet the scanning requirement of both FASOT and FASOT-1B .
Highlights
Fiber array solar optical telescope (FASOT) is a pioneer of Chinese giant solar telescope (CGST) [1], and it is a telescope which will be capable of conducting real-time, high-efficiency, high-precision spectropolarimetry of multiple magnetosensitive lines over a two-dimensional field of view, i.e., giving real-time 3D stokes measurements of multiple lines
Because the performance of the mount of FASOT is superior to the one of FASOT-1B, if the scanning specifications can be met by FASOT-1B, they can be did by FASOT
On the basis of the special structure of FASOT in optics and machine, this paper proposes a novel scanning method based on autoguiding system so as to expand the field of view of observation of FASOT
Summary
Fiber array solar optical telescope (FASOT) is a pioneer of Chinese giant solar telescope (CGST) [1], and it is a telescope which will be capable of conducting real-time, high-efficiency, high-precision spectropolarimetry of multiple magnetosensitive lines over a two-dimensional field of view, i.e., giving real-time 3D stokes measurements of multiple lines. The light from solar is collected by the guiding optics of main telescope labeled as 1 in Figure 1 and inputted to a field stop located at the Cassegrain focus plane of main telescope that splits the FOV into two parts. A novel polarization demodulation technique named reduced optical switching demodulation [4] is adopted by FASOT to improve the polarimetric sensitivity and reduce the integration time. These technologies mentioned above will make FASOT obtain a polarimetric noise level on the order of 8.0 × 10−4Ic. 2.
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