选址与日冕观测组知识库

The optical resolution of ground-based telescopes is severely affected by the atmospheric turbulence at the location of the telescope. Thus, an instrument is introduced in this paper to measure local atmospheric turbulence. The instrument is mainly used to measure the turbulence inside and outside the telescope dome and in clean rooms. After the laser passes through a certain distance, the telescope system is employed to image the parallel laser beam. Then, the fluctuation of the receiving spot on the CCD is measured. Finally, the local atmospheric turbulence is reflected. In the laboratory, the median and mean values of atmospheric coherence length were 152.83cm and 154.53cm, 60.55cm and 58.82cm, and 4.90cm and 5.49cm under closed environment, open door, and open electric heater, respectively. Besides, the two conditions of the close dome and the open dome are compared to demonstrate that turbulence is more variable than expected. The median and mean values of the measured atmospheric coherence length under the close dome in the daytime of July 10 and in the night of July 10, 11, and 12 were 25.1cm and 27.1cm, 26.72cm and 27.03cm, 36.2cm and 34.61cm, and 32.49cm and 32.55cm, respectively. When the dome was fully opened in the daytime on July 11 and 12, the median value of atmospheric coherence length was 7.7cm and 5.03cm, respectively, with the mean value of 9.3cm and 7.67cm. Thus, the existence of the verified dome atmospheric coherence length should not be ignored.