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US 11,029,586 B2Granted
Optical system and image projection apparatus
AssigneeCanon Kabushiki Kaisha
InventorMakoto Takahashi
Life of this patent
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Abstract
An optical system includes, in order from a reduction conjugate side to an enlargement conjugate side, a refractive optical unit having a positive refractive power, and a mirror optical unit that includes a mirror element having a positive refractive power and a mirror element having a negative refractive power and reforms an intermediate image formed by the refractive optical unit. A predetermined condition is satisfied.
Claims23
An optical system comprising;
- in order from a reduction conjugate side to an enlargement conjugate side, a refractive optical unit having a positive refractive power, and
- a mirror optical unit that includes a mirror element having a positive refractive power and a mirror element having a negative refractive power,
- wherein the mirror optical unit forms an image of an intermediate image formed by the refractive optical unit, and
- wherein the following conditional expressions are satisfied:
- 0.6≤φ0/φM1≤0.95,
- 0.23≤L2/L1≤0.4, and
- 0.09≤|φ0/φfa|≤0.2,
- where φ0 is the refractive power of the refractive optical unit, φM1 is a refractive power of the mirror element having the strongest positive refractive power in the mirror optical unit, L1 is a distance on an optical axis from a surface in the refractive optical unit closest to the enlargement conjugate side to a reflective surface of the mirror element having the strongest positive refractive power in the mirror optical unit, L2 is a distance on the optical axis from an intermediate image point of an on-axis light flux to the reflective surface of the mirror element having the strongest positive refractive power in the mirror optical unit, and φfa is a refractive power of an overall optical system.
5 more elements
An image projection apparatus comprising;
- an optical system;
- an image display element;
- and
- a light guide optical system configured to guide light from the image display element to the optical system,
- wherein the optical system includes, in order from a reduction conjugate side to an enlargement conjugate side, a refractive optical unit having a positive refractive power, and a mirror optical unit that includes a mirror element having a positive refractive power and a mirror element having a negative refractive power,
- wherein the mirror optical unit forms an image of intermediate image formed by the refractive optical unit, and
- wherein the following conditional expressions are satisfied:
- 0.6≤φ0/φM1≤0.95,
- 0.23≤L2/L1≤0.4, and
- 0.09≤|φ0/φfa|≤0.2,
- where φ0 is the refractive power of the refractive optical unit, φM1 is a refractive power of the mirror element having the strongest positive refractive power in the mirror optical unit, L1 is a distance on an optical axis from a surface in the refractive optical unit closest to the enlargement conjugate side to a reflective surface of the mirror element having the strongest positive refractive power in the mirror optical unit, L2 is a distance on the optical axis from an intermediate image point of an on-axis light flux to the reflective surface of the mirror element having the strongest positive refractive power in the mirror optical unit, and φfa is a refractive power of an overall optical system.
8 more elements
Dependencies are inferred from the claim text.