Imaging optical system, projection-type display apparatus, and imaging apparatus

An imaging optical system capable of projecting an image, displayed on an image display device disposed on a reduced-side conjugate plane, as a magnified image on a magnified-side conjugate plane, the system comprising, in order from a magnified side:

• a first optical system which is constituted by a plurality of lenses;
• and
• a second optical system which is constituted by a plurality of lenses, wherein
• the second optical system forms the image displayed on the image display device as an intermediate image,
• the first optical system forms the intermediate image on the magnified-side conjugate plane,
• a height of a principal ray of light having a maximum angle of view becomes maximum on a lens surface of the whole system on the most magnified side, among heights of principal rays of light having a maximum angle of view on respective lens surfaces, and
• the following Conditional Expressions (1) and (4) are satisfied,
• 0.03<H×|f|/(L×I)<0.09 (1)
• 0.8<H×f2/(fo×I2)<1.3 (4)
• where H is a height of the principal ray of light having a maximum angle of view on a plane orthogonal to an optical axis through a point of intersection between the lens surface on the most magnified side and the optical axis,
• f is a focal length of the whole system,
• L is a distance on the optical axis between the lens surface on the most magnified side and a lens surface on a most reduced side,
• I is a maximum image height on a reduced side, and
• fo is a focal length of the first optical system.