| 摘要 |
PROBLEM TO BE SOLVED: To obtain a small-sized optical image-forming system forming the image of an object positioned on an image plane and constituted of small number of parts easily aligned with each other by specifying an angle between the 1st and the 2nd surfaces of the 1st prism of the optical image-forming system. SOLUTION: The optical image-forming system includes a 1st prism 102, a 2nd prism 104, a focusing reflection element 106, and a focusing transmission element 108. The 1st prism 102 includes a 1st, a 2nd and a 3rd surfaces 132, 134 and 136. The 3rd surface 136 faces the image plane. The angle between the 1st and the 2nd surfaces 132 and 134 isα. The angleαis within a range where light outgoing from an exit pupil passes through the element 108 and the 2nd and the 1st prisms 104 and 102, is perfected by the element 106, returned to the 1st prism 102, reflected by the 2nd surface 134, perfectly internally reflected by the 1st surface 132, and passes through the 3rd surface 136 to reach the image plane.
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