| 摘要 |
PURPOSE:To make intensity distribution uniform by providing incident beam dividing means, means for so processing the divided first beam that an optical image is reverse at right and left sides and upper and lower sides, and means for superposing part of an output beam on a second beam. CONSTITUTION:A beam splitter 11 is disposed obliquely at 45 degrees with respect to an optical axis on the optical path 12 of an excimer laser. When a laser beam 16 is incident, part 17 is reflected perpendicularly, the remaining beam 18 is passed as it is to be incident into a right angle prism 13, reflected at an input side and deflected at 180 degrees. An emitting beam 18a from the right angle prism 13 is next incident to a roof prism 15 so that the image is reversed to be deflected at 90 degrees at upper and lower sides and at right and left sides, and an emitting beam 18b is incident in a direction perpendicular to the laser beam 16 from the rear face with respect to the beam splitter 11. Part 18c is reflected, and superposed on the reflected beam 17 reflected by the beam splitter 11. |
