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This paper gives the introduction about a new measuring device which is to measure th
e atmospheric coherence length by using the differential movement principle.The system can
observe the edge of the sun in the day time, and also observe planets at night. This system can
measure the atmospheric coherence length in both horizontal and slant directions. The
measurement in the day time requests the assistance of the attenuator and beacon beam of the
atmospheric coherence length in the direction of the slant path.The working principle is the laser
beam scattered by atmospheric turbulence through into the receiving optical system. Because the
receiving system which is consists of two completely symmetrical telephoto optical system.
Therefore，two optical channels in turbulence device are completely identical. After passing
through the optical channels, the beam focusing is finished. By adjusting the optical system
manually or automatically, two light point images can be formed on the photosensitive element of
the CCD. Atmospheric turbulence can cause phase fluctuation of wave front. After aggregation by
the receiving lens, The photosensitive element of CCD can collect the relative jitter of the two
imaging optical centroid positions we require, and researchers can obtain relative changes from
the two centroid positions by the calculations of computer software, as the result, the atmospheric
coherence length is obtained. By means of the simulation of the optical system and the imaging
quality optimization by Code V, researchers can rather achieve transfer function diagram, the
circle of confusion value in different views and energy distribution. From above, researchers can
examine whether the optical system is being qualified, or the method is leading to a better
observation effect. At end of this dissertation, the limitations of this system will be analyzed, and
the improvement methods and suggestions will be provided.
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