Parameters of Random Atmosphere and its Measurement

The reason of image quality degradation of astronomical image through the random atmosphere is discussed. The seeing parameter r₀ and the other optical parameters describing the image quality degradation are studied and the methods used to measure these paremeters are introduced. A new instrument(Solar Lamb Different Image Motion Mo nitor)that can measure day-time seeing and night-time seeing was built in Yunnan Observatory. It is the first time that the differential image motion method can be used to measure the day-time seeing. The day-time seeing data obtained with SLDIMM at Yunnan Observatory is also given in the thesis. At last, the near-field approximation is quantitatively analysized. As a result, a new wide region inside which the near-field appro ximation applies is given.