| 摘要 |
PROBLEM TO BE SOLVED: To provide a determination method of an optimal filament current value without shortening a filament lifetime. SOLUTION: A plurality of binarized images which identify a pattern portion and a background portion with a plurality of concentration values as a threshold value are produced against an emission pattern image. Then, against a pattern portion of each of the obtained binarized images, diffusion of an intermediate point group in the same pixel direction and a similar straight line obtained from the intermediate point group is calculated and an average value of the diffusion in each of the binarized images is calculated to obtain an emission pattern evaluation value in the filament current value. The filament current value is increased within a predetermined variation width till the evaluated value becomes below the threshold value as compared with a predetermined threshold value and the filament current value is optimized. COPYRIGHT: (C)2008,JPO&INPIT
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