| 摘要 |
PURPOSE:To provide a compact automatic focusing device corresponding to an optical device which is miniaturized. CONSTITUTION:An afocal optical system is constituted by inserting a concave lens 27 in the back part of a slave lens 21 so that the position of a surface 34 which is equivalent to the focusing surface 3 of a telescope 10 and the virtual focus of the lens 27 are aligned each other. When the lens 21 is placed at the equivalent surface 34 and such a position that the image of an object 22 is formed on the surface 34, light 36 emitted from the lens 27 becomes the parallel rays of light. Based on the parallelism thereof, the focusing position of the slave lens 21 is detected. |
