| 摘要 |
PURPOSE:To reduce the size of an optical system by providing a convex cylindrical lens, which collimates a light beam into nearly circular parallel light by focusing it, between a fully reflecting mirror and objective lens. CONSTITUTION:Between fully reflecting mirror 15 changing a light beam in direction and objective lens 16, concave cylindrical lens 14 is arranged which while a light beam is parallel in either direction of mutually orthogonal directions perpendicular to the optical axis of the light beam, focues a light beam spread in the other direction to obtain nearly circular parallel light beams in both directions. The function of reducing the light beam to an extremely small spot is the same. The leading- in range of focusing control can be expanded by reducing the distance between convex cylindrical lens 14 and objective lens 16. Therefore, the size of the optical system can be reduced in this constitution. |
