Method for optical alignment based on principle of maximum entropy of four-quadrant detector sequence

Four-quadrant detectors is widely used in the align process in the space lase communications. However, its adverse effects, such as deformation and spot broken, caused by the atmospheric turbulence, appear while the laser beam go through the atmosphere, which severely limits the alignment accuracy of the four-quadrant devices. Since four-quadrant detectors provide less message then the CCD, it's difficult to suppress the influence generated from the atmosphere. In this paper, a optical axis alignment method was proposed based on the four-quadrant detector. The value of the output miss distance of the four-quadrant detector for a certain time was calculated, the original formula was weighted by using the entropy that computing the entropy from the distribution probability of each quadrants. By taking advantage of the high frame rate of the quadrant detector, insufficient information was made up for to suppress the effect of the atmospheric turbulence, an experimental platform was set up, and a certain effect was achieved.