| 摘要 |
PURPOSE:To simplify the constitution of an optical system including a beam shaping prism. CONSTITUTION:This beam shaping prism 4 has an incidence face 41 and a reflecting face 42 facing each other at a prescribed vertical angle, and refractive indexes of these constituting materials and the vertical angle are combined to shape the section of exit light 22, which is made incident from the incidence face 41 and is reflected by the reflecting face 42 and is emitted from the incidence face 41 again, to an approximate circle. The reflecting face 42 of the beam shaping prism 4 is made of a laminated body of, for example, optical thin films and is so arranged that an optical axis 21 before reflection and an optical axis 23 after reflection in the beam shaping prism 4 do not coincide with each other. |
