| 摘要 |
PROBLEM TO BE SOLVED: To provide an imaging optical system that can prevent a ghost at a low cost and is suitable to a video camera or a digital camera using an imaging device with comparatively high surface reflection such as a CCD. SOLUTION: This imaging optical system is used to focus a flux of light at a focus position P on the imaging surface 1 of an imaging device through lens L1 to L3 , and a parallel light flux C in which a central light flux is almost parallel to a light axis is provided between the lenses L2 and L3 . The parallel light flux C is provided with a half prism 2 having planes 3 and 4 whose object- side and a first imaging surface side surfaces are nearly orthogonal to the light axes respectively. Both planes 3 and 4 of the half prism 2 are joined with ghost prevention members 5 and 6 respectively. The ghost prevention members 5 and 6 are made of glass optically equivalent to those of both planes, and a surface opposite to the joint surface is a lens surface with a large curvature radius.
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