| 摘要 |
PURPOSE:To obtain a laser beam whose intensity distributions both in the direction of an electric field and in the direction perpendicular thereto are shaped both in a trapezoid, by dividing at least either of paired main discharge electrodes into two or more in the longitudinal direction thereof. CONSTITUTION:Main discharge electrodes 3 one of which is divided into two in the longitudinal direction are kept at an equal potential and conduct discharge independently with an opposite electrode 2 respectively, and thereby the direction of an electric field in the section of a laser beam presents the shape of a trapezoid. On the other side, the light intensity distribution of the section of the laser beam in the direction of the electrode width perpendicular to the direction of the electric field is a superposition of light intensity distributions having shapes approximate to the shapes of two normal distributions which have peak values at positions corresponding to the central portions 13a and 13b of a discharging surface, and the light intensity distribution as a whole in the direction of the electrode width perpendicular to the direction of the electric field takes the shape of a trapezoid. Thus, the light intensity distributions of a laser beam both in the direction of the electric field and in the direction of the electrode width perpendicular thereto are shaped in a trapezoid. |
