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

An imaging optical system that conjugates a reduction-side imaging plane and a magnification-side imaging plane each other,

• forms, in the imaging optical system, an intermediate image at a position conjugate to the magnification-side imaging plane, and
• consists of, in order from a magnification side to a reduction side along an optical path, a first optical system and a second optical system,
• wherein the first optical system and the second optical system are separated by a maximum air spacing among air spacings between lenses on an optical axis on the reduction side with respect to the intermediate image,
• the first optical system includes a lens surface having a concave shape adjacent to the intermediate image on the magnification side, and a lens surface having a concave shape adjacent to the intermediate image on the reduction side,
• a lens surface of the first optical system closest to the reduction side has a concave shape, and
• in a case where an air spacing on the optical axis between the first optical system and the second optical system is denoted by Dair,
• a distance on the optical axis from a lens surface of the first optical system closest to the magnification side to a lens surface of the second optical system closest to the reduction side is denoted by DAL,
• a distance on the optical axis from the lens surface of the first optical system closest to the magnification side to the lens surface of the first optical system closest to the reduction side is denoted by DG1,
• a distance on the optical axis from a lens surface of the second optical system closest to the magnification side to the lens surface of the second optical system closest to the reduction side is denoted by DG2, and
• in a case where the imaging optical system is a variable magnification optical system, Dair, DAL, DG1, and DG2 are values at a wide-angle end,
• Conditional Expressions (1) and (2) are satisfied, which are represented by
• 0.11
• <
• Dair
• /
• DAL
• <
• 0.25
• and
• (
• 1
• )
• 1
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• DG
• ⁢
• 1
• /
• DG
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• 2
• <
• 2.4
• .
• (
• 2
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