ELECTRON GUN WITH AUTOMATIC ASTIGMATISM ELIMINATION, AND AUTOMATIC ASTIGMATISM ELIMINATION METHOD OF AN ELECTRON GUN

The present invention discloses an automatic anastigmatic electron gun and an automatic anastigmatic method for an electron gun, which use a split Rogowski coil as the detecting element to realize non-contact detection of electron beam spot morphology in combination with the pulse electron beam technology. The split Rogowski coil uses differential-mode signals as the output and the minimum value of detection signals as the correction target of the anastigmatic device, which simplifies the processing method of detection signals, eliminates the influence of common-mode interference signals, and improves detection sensitivity and precision. The "optimum" exciting current of the anastigmatic device is searched by axes to realize quick search. The weighted values of the amplitude and the average value of the detection signals can reflect the difference of electron beam spot morphology more fully. With the integrated data of the weighted values as the judgment basis, two rounds of search and confirmation of the "optimum" value further improve the reliability and reduce the randomness.