| 摘要 |
PURPOSE:To obtain a charged beam having a short pulse width easily by executing blanking of the charged beam using an aperture mask arranged in the position where a reduced image of the crossover from the beam emitter is formed and also using an electrostatic deflecting electrode arranged on the beam emitter side of the aperture mask. CONSTITUTION:The crossover beam emitted by an electron gun 1 is reduced in size by a lens 2 and formed into an image. An aperture mask 6 for blanking having an aperture smaller than the reduced image is arranged at the position Q where the reduced image is formed. A deflecting electrode 7 for blanking made of electrostatic deflector plates is set between a lens 2 and the aperture mask 6. When a voltage is not applied to the electrode 7, the crossover reduced image is formed on the aperture of the mask 6 (i.e. beam ON), whereas, when a positive or negative voltage is applied to the electrode 7, the reduced image is out of the aperture position (beam OFF). According to this construction, a pulse beam having small through rate wave form and a short width can be generated. |
