Influence of Dome effect on system performance of four-aperture coherent length monitors

System performances of two four-aperture coherent length monitors, whose optical source is tungsten-halogen lamp at horizontal direction, were explored by synchro contrast experiments. Experimental results show that, dimensions and temporal varying tendencies of atmospheric coherent length, measured by these two systems, are almost the same, and the correlation coefficients are all larger than 0.94. Influence of Dome effect on system performances was also researched. The main influence of this effect was embodied by the decreased of atmospheric coherent length, and the influence intensity was determined by the distance of the shifting system along the optical path. When the distance was smaller than 15 cm, there was no remarkable Dome effect. As the distance increased from 15 cm to 55 cm, the intensity of Dome effect also increased, and reached its maximum at 55 cm. There was no obvious change when the distance became larger. Dome effect had no obvious influence on the overall tendency of temporal variation of atmospheric coherent length. Correlation coefficients of all experimental results are larger than 0.9.