Because the element of the far field diagnosis system which is used to detecte facula is ccd , when it works , much types of noise will affect it , and threshold value will affect the efficient signal . in this paper , hartmann - shack wavefront sensor which can detect the phase of beam is studied , what is detected by hartmann - shack wavefront sensor can be transform into far field , and we compare this result with that detected by the far field diagnosis system , and we can know which system is more accurate 事实上， hartmann - shack波前传感器的ccd在探测光斑阵列时，也同样受ccd噪声因素的影响，并且还有波前本身的复原误差，但是hartamnn - shack波前传感器的ccd噪声影响的是波前复原精度，虽然这也将导致事后处理远场光斑的误差，但这种误差与远场测量系统的误差相比孰大孰小是本文研究的主要内容。
