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US 10,379,272 B2Granted
Optical system and image pickup apparatus including the same
AssigneeCanon Kabushiki Kaisha
InventorHiroto Yasui
Life of this patent
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Abstract
Provided is an optical system including a front unit, an aperture stop and a rear unit which are arranged in order from an object side to an image side. The front unit includes a diffractive optical element, at least one first refractive optical element having a power in the same sign as a sign of a power at a diffractive surface of the diffractive optical element, and at least one second refractive optical element having a power in a different sign from the sign of the power at the diffractive surface. A partial dispersion ratio between a d-line and a C-line and a partial dispersion ratio between a g-line and the d-line of the at least one first refractive optical element and the at least one second refractive optical element are appropriately set.
Claims13
An optical system, comprising a front unit, an aperture stop, and a rear unit, which are arranged in order from an object side to an image side,
- the front unit comprising a diffractive optical element, at least one first refractive optical element having a power in the same sign as a sign of a power of a diffractive surface of the diffractive optical element, and at least one second refractive optical element having a power in a different sign from the sign of the power of the diffractive surface,
- wherein the following conditional expression is satisfied:
- 0.001
- <
- ∑
- i
- =
- 1
- M
-
-
-
- δ
-
-
- θ
- dC
- -
- fsi
-
- /
- M
- <
- 0.010
- where δθdC-fsi is defined as θdC-fsi−(−0.1968×θgd-fsi+0.548), and θdC-fsi and θgd-fsi represent a partial dispersion ratio between a d-line and a C-line and a partial dispersion ratio between a g-line and the d-line, respectively, of a material of an i-th (i is an integer of 1 or more and M or less, and M is an integer of 1 or more) first refractive optical element counted from the object side among the at least one first refractive optical element,
- wherein the following conditional expression is satisfied:
- 0.0001
- <
- ∑
- j
- =
- 1
- N
-
-
-
- δ
-
-
- θ
- dC
- -
- fdj
-
- /
- N
- <
- 0.0010
- where δθdC-fdj is defined as θdC-fdj−(−0.1968×θgd-fdj+0.548), and θdC-fdj and θgd-fdj represent a partial dispersion ratio between the d-line and the C-line and a partial dispersion ratio between the g-line and the d-line, respectively, of a material of a j-th (j is an integer of 1 or more and N or less, and N is an integer of 1 or more) second refractive optical element counted from the object side among the at least one second refractive optical element, and
- wherein the following conditional expression is satisfied:
- 0.001
- <
- ∑
- j
- =
- 1
- N
-
-
- Δθ
- gd
- -
- fdj
-
- /
- N
- <
- 0.010
- where Δθgd-fdj is defined as θgd-fdj−(−1.687×10−7×vdfdj3+5.702×10−5×vdfdj2−6.603×10−3×vdfdj+1.462), and vdfdj represents an Abbe number of the material of the j-th (j is an integer of 1 or more and N or less, and N is an integer of 1 or more) refractive optical element counted from the object side among the at least one second refractive optical element.
66 more elements
An image pickup apparatus, comprising:
- an optical system;
- and
- an image pickup element, which is configured to receive light of an image formed by the optical system,
- wherein the optical system comprises a front unit, an aperture stop, and a rear unit, which are arranged in order from an object side to an image side,
- wherein the front unit comprises a diffractive optical element, at least one first refractive optical element having a power in the same sign as a sign of a power of a diffractive surface of the diffractive optical element, and at least one second refractive optical element having a power in a different sign from the sign of the power of the diffractive surface,
- wherein the following conditional expression is satisfied:
- 0.001
- <
- ∑
- i
- =
- 1
- M
-
-
-
- δ
-
-
- θ
- dC
- -
- fsi
-
- /
- M
- <
- 0.010
- where ΔθdC-fsi is defined as θdC-fsi−(−0.1968×θgd-fsi+0.548), and θdC-fsi and θgd-fsi represent a partial dispersion ratio between a d-line and a C-line and a partial dispersion ratio between a g-line and the d-line, respectively, of a material of an i-th (i is an integer of 1 or more and M or less, and M is an integer of 1 or more) first refractive optical element counted from the object side among the at least one first refractive optical element,
- wherein the following conditional expression is satisfied:
- 0.0001
- <
- ∑
- j
- =
- 1
- N
-
-
-
- δ
-
-
- θ
- dC
- -
- fdj
-
- /
- N
- <
- 0.0010
- where ΔθdC-fdj is defined as θdC-fdj−(−0.1968×θgd-fdj+0.548), and θdC-fdj and θgd-fdj represent a partial dispersion ratio between the d-line and the C-line and a partial dispersion ratio between the g-line and the d-line, respectively, of a material of a j-th (j is an integer of 1 or more and N or less, and N is an integer of 1 or more) second refractive optical element counted from the object side among the at least one second refractive optical element, and
- wherein the following conditional expression is satisfied:
- 0.001
- <
- ∑
- j
- =
- 1
- N
-
-
- Δθ
- gd
- -
- fdj
-
- /
- N
- <
- 0.010
- where Δθgd-fdj is defined as θgd-fdj−(−1.687×10−7×vdfdj3+5.702×10−5×vdfdj2−6.603×10−3×vdfdj+1.462), and vdfdj represents an Abbe number of the material of the j-th (j is an integer of 1 or more and N or less, and N is an integer of 1 or more) refractive optical element counted from the object side among the at least one second refractive optical element.
70 more elements
Dependencies are inferred from the claim text.