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US 6,606,200 B1Granted
Zoom lens device and optical apparatus provided with the same
AssigneeCanon Kabushiki Kaisha
InventorsHiroki Nakayama, Hiroyuki Hamano, Hiroki Yoshida
Life of this patent
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Abstract
A zoom lens device including a diffraction optical element constructed in a new way. In a basic form of the invention, the zoom lens device includes in order of lens units from a long conjugate side, at least a first lens unit including the diffraction optical element, a second lens unit which is moved during zooming in order to change the size of an image, and a third lens unit. In this zoom lens device, during zooming at least one of the lens units from the third lens unit onwards is moved in order to correct a change in an image plane which occurs as the magnification changes.
Claims104
A zoom lens device comprising in order of lens units from a long conjugate side, at least:
- a first lens unit having a positive refractive power and including a diffraction optical element;
- a second lens unit having a negative refractive power, said second lens unit being moved during zooming in order to change the size of an image;
- a stationary third lens unit having a positive refractive power;
- and
- a fourth lens unit, wherein during zooming said fourth lens unit is moved to correct changes in an image plane occurring as the magnification changes,
- wherein the condition:
- Ψ1·C1<0
- is satisfied, when Ψ1 is the refractive power due to the curvature of a surface corresponding to a diffraction optical surface of said diffraction optical element, and when the phase at said diffraction optical element is:
- φ ( h ) = 2 π λ ( C1 · h 2 + C2 · h 4 + C3 · h 6 + ⋯ + Ci · h 2 i )
- where λ is the wavelength of an incident light beam, Ci is a coefficient representing the phase, and h is the height measured from an optical axis.
7 more elements
A zoom lens device comprising in order of lens units from a long conjugate side, at least:
- a first lens unit having a positive refractive power and including a diffraction optical element;
- a second lens unit having a negative refractive power, said second lens unit being moved during zooming in order to change the size of an image;
- and
- a third lens unit having a positive refractive power,
- wherein during zooming (i) said third lens unit or (ii) in the case where there is one or more lens unit on the short conjugate side of said third lens unit, at least one lens unit of said third lens unit and said one or more lens unit, is moved to correct changes in an image plane occurring as the magnification changes, and
- wherein said diffraction element comprises a first annular diffraction grating, and a second annular diffraction grating formed on said first annular diffraction grating, with said first annular diffraction grating and said second annular diffraction grating being made of different materials.
3 more elements
A zoom lens device comprising in order of lens units from a long conjugate side, at least:
- a first lens unit;
- a second lens unit which is moved during zooming in order to change the size of an image, said second lens unit including a diffraction optical element;
- a third lens unit which is stationary during zooming;
- and
- a fourth lens unit,
- wherein during zooming (i) said fourth lens unit or (ii) in the case where there is one or more lens unit on the short conjugate side of said fourth lens unit, at least one lens unit of said fourth lens unit and said one or more lens unit, is moved in order to correct a change in an image plane which occurs as the magnification changes, and
- wherein the condition:
- Ψ2·C1<0
- is satisfied, when Ψ2 is the refractive power due to the curvature of a surface corresponding to a diffraction optical surface of said diffraction optical element, and when the phase at said diffraction optical element is:
- φ ( h ) = 2 π λ ( C1 · h 2 + C2 · h 4 + C3 · h 6 + ⋯ + Ci · h 2 i )
- where λ is the wavelength of an incident light beam, Ci is a coefficient representing the phase, and h is the height measured from an optical axis.
8 more elements
A zoom lens device comprising in order of lens units from a long conjugate side, at least:
- a first lens unit;
- a second lens unit which is moved during zooming in order to change the size of an image;
- a third lens unit which is stationary during zooming and which includes a diffraction optical element;
- and
- a fourth lens unit;
- wherein during zooming (i) said fourth lens unit or (ii) in the case where there is one or more lens unit on the short conjugate side of said fourth lens unit, at least one lens unit of said fourth lens unit and said one or more lens unit, is moved to correct a change in an image plane which occurs as the magnification changes.
3 more elements
A zoom lens device comprising in order of lens units from a long conjugate side, at least:
- a first lens unit;
- a second lens unit which is moved during zooming in order to change the size of an image;
- a third lens unit which is stationary during zooming;
- and
- a fourth lens unit including a diffraction optical element;
- wherein during zooming (i) said fourth lens unit or (ii) in the case where there is one or more lens unit on the short conjugate side of said fourth lens unit, at least one lens unit of said fourth lens unit and said one or more lens unit, is moved to correct changes in an image plane occurring as the magnification changes.
3 more elements
An optical apparatus, comprising:
- a zoom lens device;
- and
- means for holding said zoom lens device,
- wherein said zoom lens device comprises in order of lens units from a long conjugate side, at least:
- (a) a first lens unit having a positive refractive power and including a diffraction optical element;
- (b) a second lens unit having a negative refractive power, said second lens unit being moved during zooming in order to change the size of an image;
- (c) a stationary third lens unit having a positive refractive power;
- and
- (d) a fourth lens unit, wherein during zooming said fourth lens unit is moved to correct changes in an image plane occurring as the magnification changes,
- wherein the condition:
- Ψ1·C1<0
- is satisfied, when Ψ1 is the refractive power due to the curvature of a surface corresponding to a diffraction optical surface of said diffraction optical element, and when the phase at said diffraction optical element is:
- φ ( h ) = 2 π λ ( C1 · h 2 + C2 · h 4 + C3 · h 6 + ⋯ + Ci · h 2 i )
- where λ is the wavelength of an incident light beam, Ci is a coefficient representing the phase, and h is the height measured from an optical axis.
11 more elements
An optical apparatus comprising in order of lens units from a long conjugate side, at least:
- a first lens unit having a positive refractive power and including a diffraction optical element;
- a second lens unit having a negative refractive power, said second lens unit being moved during zooming in order to change the size of an image;
- and
- a third lens unit having a positive refractive power,
- wherein during zooming (i) said third lens unit or (ii) in the case where there is one or more lens unit on the short conjugate side of said third lens unit, at least one lens unit of said third lens unit and said one or more lens unit, is moved to correct changes in an image plane occurring as the magnification changes, and
- wherein said diffraction element comprises a first annular diffraction grating, and a second annular diffraction grating formed on said first annular diffraction grating, with said first annular diffraction grating and said second annular diffraction grating being made of different materials.
3 more elements
An optical apparatus, comprising:
- a zoom lens device;
- and
- means for holding said zoom lens device;
- wherein said zoom lens device comprises in order of lens units from a long conjugate side, at least:
- (a) a first lens unit;
- (b) a second lens unit which is moved during zooming in order to change the size of an image, said second lens unit including a diffraction optical element;
- (c) a third lens unit which is stationary during zooming;
- and
- (d) a fourth lens unit;
- wherein during zooming (i) said fourth lens unit or (ii) in the case where there is one or more lens unit on the short conjugate side of said fourth lens unit, at least one lens unit of said fourth lens unit and said one or more lens unit, is moved in order to correct a change in an image plane which occurs as the magnification changes, and
- wherein the condition
- Ψ2·C1<0
- is satisfied, when Ψ2 is the refractive power due to the curvature of a surface corresponding to a diffraction optical surface of said diffraction optical element, and when the phase at said diffraction optical element is:
- φ ( h ) = 2 π λ ( C1 · h 2 + C2 · h 4 + C3 · h 6 + ⋯ + Ci · h 2 i )
- where λ is the wavelength of an incident light beam, Ci is a coefficient representing the phase, and h is the height measured from an optical axis.
12 more elements
An optical apparatus, comprising:
- a zoom lens device;
- and
- means for holding said zoom lens device;
- wherein said zoom lens device comprises, in order of lens units from a long conjugate side, at least:
- (a) a first lens unit;
- (b) a second lens unit which is moved during zooming in order to change the size of an image;
- (c) a third lens unit which is stationary during zooming and which includes a diffraction optical element;
- and
- (d) a fourth lens unit;
- wherein during zooming (i) said fourth lens unit or (ii) in the case where there is one or more lens unit on the short conjugate side of said fourth lens unit, at least one lens unit of said fourth lens unit and said one or more lens unit, onwards is moved to correct a change in an image plane which occurs as the magnification changes.
7 more elements
An optical apparatus, comprising:
- a zoom lens device;
- and
- means for holding said zoom lens device;
- wherein said zoom lens device comprises, in order of lens units from a long conjugate side, at least:
- (a) a first lens unit;
- (b) a second lens unit which is moved during zooming in order to change the size of an image;
- (c) a third lens unit which is stationary during zooming;
- and
- (d) a fourth lens unit including a diffraction optical element;
- wherein during zooming (i) said fourth lens unit or (ii) in the case where there is one or more lens unit on the short conjugate side of said fourth lens unit, at least one lens unit of said fourth lens unit and said one or more lens unit, is moved to correct changes in an image plane occurring as the magnification changes.
7 more elements
A zoom lens device comprising in order from the object side to the image side:
- a first lens unit having a positive refractive power, wherein said first lens unit includes from the object side to the image side a meniscus negative first lens having a convex surface facing the object side, a positive second lens, and a positive third lens;
- a second lens unit having a negative refractive power, said second lens unit being moved during zooming in order to change the size of an image;
- a third lens unit having a positive refractive power;
- a fourth lens unit having a negative refractive power, wherein said fourth lens unit is moved during zooming;
- and
- a fifth lens unit having a positive refractive power,
- wherein said first lens unit further includes a diffractive optical element.
4 more elements
A zoom lens system comprising, in order from an object side to an image side,
- a first lens unit of positive optical power;
- a second lens unit of negative optical power which moves along an optical axis for zooming;
- a third lens unit of positive optical power;
- and
- a fourth lens unit which moves along an optical axis for zooming,
- wherein at least one of said first, second, third and fourth lens unit includes a diffraction optical element, and
- wherein the product of the refractive power due to the curvature of a surface corresponding to a diffraction optical surface of said diffraction optical element and the optical power due to the diffractive action of said diffraction optical surface is a positive value.
4 more elements
A camera, comprising:
- a zoom lens system for forming an image;
- and
- an image pick-up element for receiving said image;
- wherein said zoom lens system comprises in order from an object side to an image side,
- (a) a first lens unit of positive optical power;
- (b) a second lens unit of negative optical power which moves along an optical axis for zooming;
- (c) a third lens unit of positive optical power;
- and
- (d) a fourth lens unit which moves along an optical axis for zooming,
- wherein at least one of said first, second, third and fourth lens units includes a diffraction optical element, and
- wherein the product of the refractive power due to the curvature of a surface corresponding to a diffraction optical surface of said diffraction optical element and the optical power due to the diffractive action of said diffraction optical surface is a positive value.
8 more elements
A zoom lens system comprising, in order from the object side to the image side:
- a first lens unit having a positive refractive power;
- a second lens unit having a negative refractive power;
- a third lens unit having a positive refractive power;
- and
- a fourth lens unit having a positive or negative refractive power,
- wherein during zooming, said second lens unit and said fourth lens unit move and said third lens unit is stationary, and
- wherein a diffraction optical surface is included in said third lens unit or a diffraction optical surface is included in said fourth lens unit.
4 more elements
Dependencies are inferred from the claim text.