LI Yu-xia,WANG Shuai,WANG Jian-li,et al.Dual-motor de-rotator system of prime focus alt-azimuth telescope with large field of view[J].Optics and Precision Engineering,2021,29(04):749-762.
LI Yu-xia,WANG Shuai,WANG Jian-li,et al.Dual-motor de-rotator system of prime focus alt-azimuth telescope with large field of view[J].Optics and Precision Engineering,2021,29(04):749-762. DOI: 10.37188/OPE.20212904.0749.
Dual-motor de-rotator system of prime focus alt-azimuth telescope with large field of view
Owing to the Earth's rotation, image rotation always appears on the primary focus detector during the long exposure of Alt-Az telescopes with large aperture and wide field of view. This implies that except for the central point, other stars rotate around the center of the field of view; thus the target cannot be accurately identified and observed. To eliminate the image rotation, the de-rotator tracking error of a telescope with a large aperture and wide field of view should be less than 5″. The position and velocity of the image rotation of the primary-focus detector were analyzed and verified based on the star rotation principle. Subsequently, a dual-motor driving de-rotator system was designed, where the clearance of the mechanism was removed by the recombination current command. The experimental results indicate that the image rotation characteristics are consistent with the expression of image rotation, and the measurement error is less than 2%. The dual-motor diving de-rotator system can improve the stability and accuracy of the tracking system; thus the tracking accuracy of the de-rotator mechanism can be less than 1″ both at a low velocity of 15 (″)/s and at a high velocity of 170 (″)/s. In addition, the tracking error remains less than 1 arcsec when the de-rotator operated at a variable and high velocity of 7.86°sin(2π×0.5
t
).
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