The limitation of classical AO and the basic principle of MCAO are briefly introduced. A dual-conjugate AO (tow-DM
MCAO) can offer a possibility of widening FOV characterized by the isoplanatic angle, Considering the application of
lidar, the isoplanatic angle's expressions of MCAO for uplink and downlink are deduced in this paper. And through
simulation, the conjugate height, the isoplanatic angle, the isoplanatic angle gain and the coherence length for
dual-conjugate system are thoughtfully discussed. The results show the conjugate heights play a great role in widening
the isoplanatic angle, and the isoplanatic angle retains maximum when the conjugate heights is at optimal altitudes. For
the ground lidar, the positions of optimal conjugate heights simulated are about 1 and 12 km, and the optimal detecting
height is 17 km. For the air-borne lidar, the isoplanatic angle gain is minimum at the height of 13 km, and fails to reach
an optimal detecting state, and the selection of the optimal conjugate height is relative with not only the coherence length
but also the height of air-borne system.
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