In order to improve calculating efficiency of sub-pixel location of diffraction spot generated by two-dimension phase plate by correlation function fitting extreme method

three effect factors: template size

fitting window size and correlation function are analyzed in detail. Analyzing results show that the three effect factors all make bigger effect on calculation efficiency and the template and fitting window sizes make the biggest effect on locating precision during integer pixel searching. The optimal design of searching template and fitting window sizes are completed during sub-pixel location experiment of diffraction spot generated by two-dimension phase plate: the optimized template and fitting window sizes are 51×51pixel and 3×3pixel respectively. Comparing with the template of 131×131pixel which just includes the whole diffraction spot

the calculating time of whole locating process is shorted for 40%

so the calculation efficiency is improved without degrading location precision.