| 摘要 |
PURPOSE:To widen a photographable distance range, and to execute distance measurement with good focusing performance by providing a focus correcting prism having two total reflecting surfaces for extending a base line length by square times of angular magnification of a photographing afocal converter, in front of a photodetecting lens. CONSTITUTION:A focus correction prism 7 is installed to the side of an object to be photographed 3 of a photodetecting lens 4 in a distance measuring optical system, and this focus correcting prism 7 has two total reflecting surfaces 8, 9 parallel to each other, and an incident surface 10 and an emitting surface 11 are parallel to each other, too. Also, the total reflecting surface 8 of the left side and the emitting surface 11 cross each other at an angle of 45 deg., and the total reflecting surface 9 of the right side and the incident surface 10 also cross each other at an angle of 45 deg.. The focus correcting prism 7 is installed in front of the side of the object to be photographed of the photodetecting lens 4, therefore, an optical axis 12 moves to the right side, namely, in the direction opposite to an optical axis 13, and the result is reduced substantially to the same as a fact that the base line length L is extended. Also, when the total reflecting surface 9 is positioned at the side of the optical axis 13 by rotating the focus correcting prism 7 while centering the optical axis 12, the base line length L is shortened, on the contrary. |
