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US-20260126633-A1 - IMAGING OPTICAL SYSTEM, PROJECTION TYPE DISPLAY DEVICE, AND IMAGING APPARATUS

US20260126633A1US 20260126633 A1US20260126633 A1US 20260126633A1US-20260126633-A1

Abstract

An imaging optical system including of a first optical system and a second optical system along an optical path in order from a magnification side to a reduction side, wherein: an intermediate image is formed at least twice between a magnification-side imaging plane and a reduction-side imaging plane, the first optical system includes at least two reflective surfaces having curvature, a surface of the first optical system on a most magnification side along the optical path is a first refractive surface that refracts rays reflected from the reflective surface of the first optical system, and a surface of the first optical system on a most reduction side along the optical path is a surface on the most reduction side along the optical path among surfaces through which rays pass plural times.

Inventors

  • Masaru Amano

Assignees

  • FUJIFILM CORPORATION

Dates

Publication Date
20260507
Application Date
20251231
Priority Date
20230714

Claims (20)

  1. 1 . An imaging optical system consisting of a first optical system and a second optical system along an optical path in order from a magnification side to a reduction side, wherein: an intermediate image is formed at least twice between a magnification-side imaging plane and a reduction-side imaging plane, the first optical system includes at least two reflective surfaces having curvature, a surface of the first optical system on a most magnification side along the optical path is a first refractive surface that refracts rays reflected from the reflective surface of the first optical system, the first refractive surface that transmits rays twice and reflects rays once, the first refractive surface is a surface on which a surface that transmits rays twice and a surface that reflects rays once are formed on the same surface, and a surface of the first optical system on a most reduction side along the optical path is a surface on the most reduction side along the optical path among surfaces through which rays pass a plurality of times.
  2. 2 . The imaging optical system according to claim 1 , wherein, on the first refractive surface, respective regions that transmit rays twice and a region that reflects rays once are regions different from each other.
  3. 3 . The imaging optical system according to claim 1 , wherein in a case where: a distance on an optical axis from the first refractive surface to a reflective surface of the first optical system on the most magnification side along the optical path is denoted by L 1 , and a distance on the optical axis from the reflective surface of the first optical system on the most magnification side along the optical path to a surface of the second optical system on the most reduction side along the optical path is denoted by L 2 , Conditional Expression (1) is satisfied, 0 .1 < ❘ "\[LeftBracketingBar]" L ⁢ 1 / L ⁢ 2 ❘ "\[RightBracketingBar]" < 0.8 . ( 1 )
  4. 4 . The imaging optical system according to claim 3 , wherein in a case where: a distance on the optical axis from the first refractive surface to a reflective surface of the first optical system on the most reduction side along the optical path is denoted by L 3 , and a distance on the optical axis from the reflective surface of the first optical system on the most reduction side along the optical path to a surface of the second optical system on the most reduction side along the optical path is denoted by L 4 , Conditional Expression (2) is satisfied, 0 .1 < ❘ "\[LeftBracketingBar]" L ⁢ 3 / L ⁢ 4 ❘ "\[RightBracketingBar]" < 0.8 . ( 2 )
  5. 5 . The imaging optical system according to claim 4 , wherein, inside the first optical system, rays are reflected three times from the reflective surface having curvature.
  6. 6 . The imaging optical system according to claim 5 , wherein the reflective surface of the first optical system on the most magnification side along the optical path and the reflective surface of the first optical system on the most reduction side along the optical path have a concave shape.
  7. 7 . The imaging optical system according to claim 1 , wherein the intermediate image is formed twice inside the first optical system.
  8. 8 . The imaging optical system according to claim 1 , wherein the first refractive surface has a free curved surface shape.
  9. 9 . The imaging optical system according to claim 1 , comprising a display element or an imaging element disposed on the reduction-side imaging plane, wherein: at least one of an optical axis of the first optical system or an optical axis of the second optical system is shifted in a direction orthogonal to the optical axis with respect to a center of the display element or the imaging element.
  10. 10 . The imaging optical system according to claim 9 , wherein: the optical axis of the first optical system is shifted in the direction orthogonal to the optical axis with respect to each of the optical axis of the second optical system and the center of the display element or the imaging element, and the optical axis of the second optical system is shifted in the direction orthogonal to the optical axis with respect to the center of the display element or the imaging element.
  11. 11 . The imaging optical system according to claim 1 , wherein the first refractive surface and one of the reflective surfaces are formed on the same optical member.
  12. 12 . The imaging optical system according to claim 1 , wherein the first optical system consists of one optical member.
  13. 13 . The imaging optical system according to claim 12 , wherein the optical member includes a surface facing the first refractive surface and that reflects rays twice.
  14. 14 . The imaging optical system according to claim 12 , wherein the reflective surface of the first optical system on the most magnification side along the optical path and the reflective surface of the first optical system on the most reduction side along the optical path are formed on the same surface.
  15. 15 . The imaging optical system according to claim 3 , wherein Conditional Expression (1-1) is satisfied, 0.2 < ❘ "\[LeftBracketingBar]" L ⁢ 1 / L ⁢ 2 ❘ "\[RightBracketingBar]" < 0.7 . ( 1 ⁢ ‐ ⁢ 1 )
  16. 16 . The imaging optical system according to claim 4 , wherein Conditional Expression (2-1) is satisfied, 0.2 < ❘ "\[LeftBracketingBar]" L ⁢ 3 / L ⁢ 4 ❘ "\[RightBracketingBar]" < 0.7 . ( 2 ⁢ ‐ ⁢ 1 )
  17. 17 . An imaging optical system, wherein: an intermediate image is formed at least twice between a magnification-side imaging plane and a reduction-side imaging plane, an optical member disposed on a most magnification side along an optical path includes: a PA surface that is a surface on the most magnification side along the optical path and that transmits rays twice and reflects rays once; and a PB surface that is a surface facing the PA surface and that reflects rays twice, and the PA surface is a surface on which a surface that transmits rays twice and a surface that reflects rays once are formed on the same surface.
  18. 18 . The imaging optical system according to claim 17 , wherein the intermediate image is formed twice inside the optical member.
  19. 19 . A projection type display device comprising the imaging optical system according to claim 1 .
  20. 20 . An imaging apparatus comprising the imaging optical system according to claim 1 .

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation of International Application No. PCT/JP2024/025318, filed on Jul. 12, 2024, which claims priority from Japanese Patent Application No. 2023-116335, filed on Jul. 14, 2023. The entire disclosure of each of the above applications is incorporated herein by reference. BACKGROUND Technical Field The present disclosed technology relates to an imaging optical system, a projection type display device, and an imaging apparatus. Related Art In the related art, as an imaging optical system that can be used in a projection type display device, an imaging apparatus, and the like, an imaging optical system disclosed in JP2008-250296A, JP2017-040849A, and JP2020-024359A is known. In recent years, there is a demand for an imaging optical system that is configured to be small with a small number of optical elements and that has a wide angle of view and favorable optical performance. SUMMARY The present disclosure has been made in view of the above circumstances, and provides an imaging optical system that is configured to be small with a small number of optical elements and that has a wide angle of view and favorable optical performance, and a projection type display device and an imaging apparatus comprising the imaging optical system. A first aspect of the present disclosure relates to an imaging optical system consisting of a first optical system and a second optical system along an optical path in order from a magnification side to a reduction side, in which an intermediate image is formed at least twice between a magnification-side imaging plane and a reduction-side imaging plane, the first optical system includes at least two reflective surfaces having curvature, a surface of the first optical system on a most magnification side along the optical path is a first refractive surface that refracts rays reflected from the reflective surface of the first optical system, and a surface of the first optical system on a most reduction side along the optical path is a surface on the most reduction side along the optical path among surfaces through which rays pass a plurality of times. In the first aspect, in a case where a distance on an optical axis from the first refractive surface to a reflective surface of the first optical system on the most magnification side along the optical path is denoted by L1, and a distance on the optical axis from the reflective surface of the first optical system on the most magnification side along the optical path to a surface of the second optical system on the most reduction side along the optical path is denoted by L2, Conditional Expression (1) is satisfied, 0.1<❘"\[LeftBracketingBar]"L⁢1/L⁢2❘"\[RightBracketingBar]"<0.8.(1) It is more preferable that Conditional Expression (1-1) is satisfied, 0.2<❘"\[LeftBracketingBar]"L⁢1/L⁢2❘"\[RightBracketingBar]"<0.7.(1⁢‐⁢1) In the first aspect, in a case where a distance on the optical axis from the first refractive surface to a reflective surface of the first optical system on the most reduction side along the optical path is denoted by L3, and a distance on the optical axis from the reflective surface of the first optical system on the most reduction side along the optical path to a surface of the second optical system on the most reduction side along the optical path is denoted by L4, Conditional Expression (2) is satisfied, 0.1<❘"\[LeftBracketingBar]"L⁢3/L⁢4❘"\[RightBracketingBar]"<0.8.(2) It is more preferable that Conditional Expression (2-1) is satisfied, 0.2<❘"\[LeftBracketingBar]"L⁢3/L⁢4❘"\[RightBracketingBar]"<0.7.(2⁢‐⁢1) In the first aspect, it is preferable that, inside the first optical system, rays are reflected three times from the reflective surface having curvature. In the first aspect, it is preferable that the reflective surface of the first optical system on the most magnification side along the optical path and the reflective surface of the first optical system on the most reduction side along the optical path have a concave shape. In the first aspect, it is preferable that the intermediate image is formed twice inside the first optical system. In the first aspect, it is preferable that the first refractive surface has a free curved surface shape. In the first aspect, it is preferable that the imaging optical system includes a display element or an imaging element disposed on the reduction-side imaging plane, in which at least one of an optical axis of the first optical system or an optical axis of the second optical system is shifted in a direction orthogonal to the optical axis with respect to a center of the display element or the imaging element. In the first aspect, it is preferable that the optical axis of the first optical system is shifted in the direction orthogonal to the optical axis with respect to each of the optical axis of the second optical system and the center of the display element or the imaging element, and the optical axis of the second