Compensation for spatial phase aberration by use of genetic algorithm in heterodyne detection

The method of compensation for spatial phase aberration based on an array detector and sequence shifting has a great advantage. But in the method, the calculations of the shifting steps depend on the known optical field distributions, so the method is limited when the accurate distributions cannot be obtained. To overcome this problem, we propose to use genetic algorithm (GA) to search appropriate shifting steps, which can be performed automatically in a microcontroller unit (MCU). Because there is no need of obtaining the field distributions, the system can be simplifies by omitting the two on-off controllers in the optical path. Meanwhile, the detection of a weak optical signal becomes feasible in the new method. Numerical calculations confirm that genetic algorithm can effectively determine the shifting steps and the signal-to-noise ratio (SNR) of the array detector can be increased by more than one hundred times compared with the single detector.