JP2012128151A - Optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical system which exhibits a variable apodization effect and has shape variable elements capable of satisfactorily correcting various aberrations.SOLUTION: The optical system comprises a plurality of optical materials and has shape variable elements AO1 and AO2 of which the shapes of interfaces are varied, and has two or more shape variable interfaces including shape variable interfaces A comprising two materials satisfying 0.2<|Δα|<1.5 where Δα(mm) is a difference between absorption coefficients of d lines and shape variable interfaces B comprising two materials not satisfying 0.2<|Δα|<1.5. When a refracting power variation on the i-th interface Aout of interfaces A is denoted as Δφand a refracting power variation on the i-th interface Bout of interfaces B is denoted as Δφ, the optical system satisfies Δφ×Δφ<0 where Δφis a sum total of refracting power variations of all interfaces A and Δφis a sum total of refracting power variations of all interfaces B.

Description

The present invention relates to an optical system, and more particularly to an imaging optical system that can control the amount of light flux that passes through an optical system by using a shape variable element in which the shape of an interface formed by two different media is variable. Is.

  In general, in an imaging optical system, the appearance of an out-of-focus image (blurred image) is regarded as important in addition to the imaging performance of a focused object. In particular, in a telephoto lens and a macro lens, an out-of-focus image may be photographed, and it is necessary to perform a design intended to see the out-of-focus image.

  As a technique for making an out-of-focus image look beautiful, an optical system including an apodization filter is disclosed in Patent Document 1. In Patent Document 1, the apodization filter is a filter configured such that the amount of transmitted light gradually decreases as the distance from the optical axis increases in the direction perpendicular to the optical axis. With this apodization filter, it is possible to add an intensity distribution in the imaging light beam, and to make the outline of the out-of-focus image look beautiful. In addition, if the apodization effect can be made variable, it is possible to freely control the appearance of an out-of-focus image, and as a result, the expressive power in photographing is increased, which is preferable.

  A technique for making the apodization effect variable is disclosed in Patent Document 2. In Patent Document 2, two types of liquids having different transmittances and not mixed with each other are arranged in a sealed space through a substantially spherical interface, and the liquid interface shape is changed by controlling the output of the applied voltage. An optical element having a variable apodization effect has been proposed.

Japanese Patent Laid-Open No. 11-231209 JP 2000-356792 A

  However, the apodization effect cannot be made variable by the conventional technique disclosed in Patent Document 1 described above.

  In Patent Document 2, the apodization effect is variable because two types of liquids that are not mixed with each other and have different transmittances are used. However, two types of liquids having the same refractive index are used.

  In the case where a variable apodization element is used in the optical system, it is preferable to form the interface with a liquid having the same refractive index, because aberration variation does not occur when the surface shape is changed. However, in reality, it is difficult to perfectly match the refractive indexes of the two types of liquids. Furthermore, even if the refractive index can be reduced at one wavelength, the chromatic dispersion (Abbe number) is also the same at the same time. It is even more difficult to adjust to the above. Further, when the interface of the variable apodization element is formed with two types of liquids having different refractive indices or Abbe numbers, aberration variation occurs when the apodization effect is changed, and imaging performance deteriorates.

  An object of the present invention is to provide an optical system capable of satisfactorily correcting various aberrations when using a variable shape element having a variable apodization function and changing the apodization effect, and an optical apparatus using the same. To do.

The first optical system of the present invention is an optical system comprising a plurality of optical materials and having a shape variable element that changes the surface shape of the interface, and the difference Δα (mm ⁻¹ ) in the absorption coefficient at the d-line is
0.2 <| Δα | <1.5
Including two or more shape-variable interfaces including a shape-variable interface A composed of two materials satisfying the above condition and a shape variable interface B formed from two materials not satisfying the conditional expression. , When the refractive power change amount at the i-th interface A _i is Δφ _Ai , and the refractive power change amount at the i-th interface B _i among the interfaces B is Δφ _Bi , the refractive power change amounts at all the interfaces A Is Δφ _A , and the total sum of the refractive power changes at all the interfaces B is Δφ _B.
Δφ _A × Δφ _B <0
It is characterized by satisfying.

ここで、Ｎ_Ａｉｆ、Ｎ_Ａｉｒはそれぞれ該界面Ａ_ｉを形成する物体側の材料と像側の材料のｄ線における屈折率であり、ｒ_Ａｉａ、ｒ_Ａｉｂはそれぞれ該界面Ａ_ｉの曲率が最も小さい時と大きい時の曲率半径であり、Ｎ_Ｂｉｆ、Ｎ_Ｂｉｒはそれぞれ該界面Ｂ_ｉを形成する物体側の材料と像側の材料のｄ線における屈折率であり、ｒ_Ｂｉａ、ｒ_Ｂｉｂはそれぞれ該界面Ｂ_ｉの曲率が最も小さい時と大きい時の曲率半径である。 However,

_{Here, N Ai f,} N Ai r is the refractive index at each d-line of the object side of the material and the image side of the material forming the interfacial _{A i, r Ai a, r} Ai b respectively interfacial _{A i} N _Bi f and N _Bi r are the refractive indices at the d-line of the object side material and the image side material forming the interface B _i , respectively. _{Bi a,} the radius of curvature of the large time and when r Bi _b is the smallest respective curvature of the interface B _i.

The second optical system of the present invention is composed of a plurality of optical materials and has an optical system having a shape variable element that changes the surface shape of the interface. In the optical system having the absorption coefficient difference Δα (mm ⁻¹ ) at the d-line,
0.2 <| Δα | <1.5
Including two or more shape-variable interfaces including a shape-variable interface A composed of two materials satisfying the above condition and a shape variable interface B formed from two materials not satisfying the conditional expression. When the shape of the i-th interface A _i changes, Δφc _{Ai is} the amount of chromatic aberration fluctuation, and the amount of chromatic aberration when the interface shape changes in the i-th interface B _i of the interfaces B is Δφc _Bi. When the total sum of the chromatic aberration variation amounts of all the interfaces _A is Δφc _A and the total sum of the chromatic aberration variation amounts of all the interfaces B is Δφc _B ,
Δφc _A × Δφc _B <0
It is characterized by satisfying.

ここで、ｒ_Ａｉａ、ｒ_Ａｉｂはそれぞれ該界面Ａ_ｉの曲率が最も小さい時と大きい時の曲率半径であり、ν_Ａｉｆ、ν_Ａｉｒはそれぞれ該界面Ａ_ｉの物体側の材料と像側の材料のアッベ数であり、、ｒ_Ｂｉａ、ｒ_Ｂｉｂはそれぞれ該界面Ｂ_ｉの曲率が最も小さい時と大きい時の曲率半径であり、ν_Ｂｉｆ、ν_Ｂｉｒはそれぞれ該界面Ｂ_ｉの物体側の材料と像側の材料のアッベ数である。 However,

_{Here, r Ai a,} r Ai b is the radius of curvature of the time respectively as large as when the curvature of the interface _{A i} is the smallest, ν _Ai f, ν _Ai r is the object side of the material of each the interface _{A i ,,} r Bi a is the Abbe number of the image side of the _{material, r Bi} b is the radius of curvature of the time respectively as large as when the curvature of the interface _{B i} is smallest, ν _Bi f, ν _Bi r each the interface the Abbe number of the object side of the material and the image-side material B _i.

According to the present invention, it is possible to provide an optical system that can change the shape of the interface to make the apodization effect variable, and can sufficiently correct (reduce) various aberrations even when the shape is variable. Can do.

The figure explaining the structural example of the shape variable element of an electric drive system. The figure explaining the structural example of the shape variable element of an elastic film drive system. The schematic diagram which shows the interface change of a shape variable element. The schematic diagram which shows the change of the transmittance | permeability distribution in a light beam. 1 is a cross-sectional view of an optical system using a shape variable element that is Embodiment 1 of the present invention. FIG. 6 is an aberration diagram of Example 1. Sectional drawing of the optical system using the shape variable element which is Example 2 of this invention. FIG. 6 is an aberration diagram of Example 2. Sectional drawing of the optical system using the shape variable element which is Example 2 of this invention. FIG. 6 is an aberration diagram of Example 3. Sectional drawing of the optical system using the shape variable element which is Example 4 of this invention. FIG. 6 is an aberration diagram of Example 4. Sectional drawing of the optical system using the shape variable element which is Example 5 of this invention. FIG. 6 is an aberration diagram of Example 5. Sectional drawing of the optical system using the shape variable element which is Example 6 of this invention. FIG. 10 is an aberration diagram of Example 6.

  Embodiments of the present invention will be described below with reference to the drawings.

First, items common to embodiments of the present invention to be described later will be described. The shape variable element of the embodiment changes the surface shape of the interface to change the apodization effect and the refractive power or the amount of chromatic aberration. And the material which comprises this shape variable element satisfies the conditions mentioned later.
The optical system of the embodiment has an optimum configuration for optical devices such as a digital still camera, a silver salt film camera, and a video camera.

  The shape variable element of the embodiment is composed of a plurality of optical materials, and the refractive power is changed by changing the surface shape of the interface, and acts as a convex lens or a concave lens. The shape variable element can be realized by an electric drive type element. The electric drive system shown in FIG. 1 is made of two or more liquid materials that do not mix with each other, and changes the interface shape by applying a voltage. For example, as an electrolytic solution, water, a liquid such as ethanol or ethylene glycol (Nd: about 1.33 to 1.5) is mixed at an arbitrary volume ratio, and a material having an optical characteristic to some extent is obtained. can get. Similarly, as a non-electrolytic solution, a liquid having a certain degree of optical characteristics is obtained by mixing a liquid such as silicon oil (Nd: about 1.37 to 1.6) at an arbitrary volume ratio. be able to.

  Further, it is possible to obtain the effect of variable shape by providing a driving means such as an actuator using an elastic film at the interface shown in FIG. 2 and applying mechanical control. According to this, even if it is the liquid mixed with each other, it is realizable and there exists an advantage that the selectivity of material is high.

  Next, consider a case where a material having low transmittance is used for one liquid of the variable shape element as shown in FIGS.

  FIG. 3 shows a schematic diagram of a variable shape element using a liquid with low transmittance. An interface is provided between the electrolytic solution 31 and the non-electrolytic solution 32, and a material with low transmittance is used for the electrolytic solution 31. Further, the shape of the interface changes from FIG. 3A to FIG. 3B depending on the applied voltage.

FIG. 4 schematically shows the transmittance value with respect to the incident light beam position. At this time, in order to create a liquid with low transmittance, for example, in the case of an electrolytic solution, it can be obtained by adding a material such as carbon black or titanium oxide. In order to create a liquid with low transmittance in the non-electrolyte liquid, it can be obtained, for example, by mixing a dye that dissolves in fats and oils. The dye is preferably a chelate azo pigment or a nitroso pigment.
In general, since the pigment often has a color, an achromatic pigment can be obtained by mixing them at a predetermined ratio.

In the case of the element having the configuration shown in FIG. 3, the liquid portion formed by the electrolytic solution 31 has a configuration in which the optical path length increases as the height from the optical axis indicated by the alternate long and short dash line increases. The transmittance of light passing through the position is reduced. For this reason, as shown in FIG. 3A, the contour of the out-of-focus image appears to blur more greatly as the curvature of the interface is tighter.
Conversely, as shown in FIG. 3B, when the curvature of the interface is reduced, the transmittance distribution in the incident light beam becomes uniform, and the outline of the out-of-focus image becomes clear.
As described above, it has been described that the state of an out-of-focus image can be changed by changing the interface shape by using a material having low transmittance as one material of the shape variable element.

In an ordinary optical system, the outline of an out-of-focus image is often relatively clear. In order to make a difference in the appearance of an out-of-focus image with respect to a normal optical system, the curvature of the interface as shown in FIG. However, if the refractive index and Abbe number of the two materials forming the interface are different, a very large aberration occurs due to the strong curvature, and correction with other lenses becomes difficult. In addition, when the interface shape is changed, aberration fluctuations further occur and correction becomes more difficult.
In the case of the variable shape element using the liquid material as described above, the optical characteristics of the two materials forming the interface can be adjusted to some extent by mixing several kinds of materials, but other specific gravity and environmental resistance are also available. Considering that the physical properties related to etc. are set to desired values, it is difficult to make them completely coincide.

なる式を満たすものとする。 Therefore, in the optical system of the present invention, first, there is a shape variable element that changes the surface shape of at least one interface, and the difference Δα in the absorption coefficient at the d-line of the materials MAf and MAr that form the shape variable interface A. (Mm ⁻¹ ) is configured to satisfy the following condition.
0.2 <| Δα | <1.5 (1)
Here, the absorption coefficient α means that when light is incident on a material having a thickness d (mm), the amount of incident light is I ₀ , and the amount of emitted light is I.

The following expression is satisfied.

By using a material that satisfies the above equation (1), the interface shape of the interface A can be changed to make the apodization effect variable. If the lower limit condition of the expression (1) is not satisfied, it is not preferable because the curvature of the interface must be considerably tight in order to obtain a sufficient apodization effect, and the generation of aberrations at the interface becomes large. If the upper limit condition of the expression (1) is not satisfied, the average transmittance in the light beam is lowered, and the sensitivity of the transmittance due to the manufacturing error and the interface shape change error is increased, and a desired transmittance distribution is obtained. Since it becomes difficult, it is not preferable.
The expression (1) is more preferably within the following range.
0.25 <| Δα | <1.0 (1a)

The optical system of the present invention has one or more shape-variable interfaces B that do not satisfy the condition of the expression (1), in addition to the shape-variable interface A for making the apodization effect variable. Furthermore, the sum [Delta] [phi _A refractive power variation in shape variable interface A to the apodization effect _variable, the sum [Delta] [phi _B refracting power variation at the interface B satisfies the following conditional expression.
Δφ _A × Δφ _B <0 (2)

と表せる。なお、界面Ａ_ｉにおける屈折力変化量をΔφ_Ａｉ、及び、界面Ｂ_ｉにおける屈折力変化量をΔφ_Ｂｉは、以下のように表せる。 Incidentally, the interface i (i = A, B) power variation [Delta] [phi _i in each _N i f the refractive index from the object side at the d-line of the material forming the interface _{i, N} i r, curvature change of the interface i When the amount is ΔR, it is expressed by the following equation.
Δφ _i = (N _i r−N _i f) × ΔR (b)
However, ΔR = 1 / r _i a-1 / r _i b (c)
here,
r _i a is a radius of curvature when the curvature of the interface i takes the smallest value,
r _i b is a radius of curvature when the curvature of the interface i takes the largest value. Specifically, for Δφ _A and Δφ _{B in} equation (2), the amount of change in refractive power at the i-th shape variable interface A _i in the shape-variable interface A is Δφ _Ai , and the shape is variable. When the refractive power change amount at the i-th shape-variable interface B _i among the various interfaces B is Δφ _Bi ,

It can be expressed. Incidentally, the interface _{A i} in power change amount [Delta] [phi _Ai, and the [Delta] [phi _Bi refractive power variation at the interface _{B i,} can be expressed as follows.

ここで、
Ｎ_Ａｉｆ：形状可変な界面Ａ_ｉを形成する物体側の材料のｄ線における屈折率、
Ｎ_Ａｉｒ：形状可変な界面Ａ_ｉを形成する像側の材料のｄ線における屈折率、
ｒ_Ａｉａ：形状可変な界面Ａ_ｉの曲率が最も小さい時の曲率半径、
ｒ_Ａｉｂ：形状可変な界面Ａ_ｉの曲率が最も大きい時の曲率半径、
Ｎ_Ｂｉｆ：形状可変な界面Ｂ_ｉを形成する物体側の材料のｄ線における屈折率、
Ｎ_Ｂｉｒ：形状可変な界面Ｂ_ｉを形成する像側の材料のｄ線における屈折率、
ｒ_Ｂｉａ：形状可変な界面Ｂ_ｉの曲率が最も小さい時の曲率半径、
ｒ_Ｂｉｂ：形状可変な界面Ｂ_ｉの曲率が最も大きい時の曲率半径、
である。

here,
N _Aif : the refractive index at the d-line of the material on the object side that forms the deformable interface A _i ,
N _Air : the refractive index at the d-line of the image-side material that forms the shape-variable interface A _i ,
r _Ai a: the radius of curvature when the curvature of the shape-variable interface A _i is the smallest,
r _Ai b: radius of curvature when the curvature of the variable shape interface A _i is the largest,
N _Bif : the refractive index at the d-line of the material on the object side that forms the shape variable interface B _i ,
N _Bi r: the refractive index at the d-line of the image-side material forming the deformable interface B _i ,
r _Bi a: radius of curvature when the curvature of the shape variable interface B _i is the smallest,
r _Bi b: radius of curvature when the curvature of the shape variable interface B _i is the largest,
It is.

Equation (2) means that the refractive power fluctuation that occurs when the shape of the interface A changes is canceled by another shape-variable interface B.
When the apodization effect is changed by changing the shape variable interface, if the power of the entire optical system changes, the focal length changes and the object image magnification changes, which is not preferable.

Furthermore, when the change amount of the focal length when changing the shape-variable interface when photographing the same distance object is Δf and the focal length of the optical system is f, the following conditional expression is satisfied, so that the object image magnification is It is more preferable because the apodization effect can be changed without greatly changing.
−0.05 <Δf / f <0.05 (3)
However, the focal length f is a value at the time of focusing on an object at infinity, and when the focal length changes due to a change in the shape of the interface, it indicates the value of the focal length when the curvature of the interface takes the largest value.
Further, the refractive index at the d-line of the object-side material M _i f and the image-side material M _i r forming the variable-shape interface i is N _i f and N _i r, respectively, and the interface i is When the amount of change in Petzval sum when the shape changes is ΔP _i , the following conditional expression is satisfied.
| ΣΔP _i × f | <0.1 (4)
However, ΔP _i = (1 / N _i r−1 / N _i f) × ΔR (d)

If the upper limit condition of the expression (4) is not satisfied, the field curvature change that occurs when the interface shape is changed becomes large, and it becomes difficult to correct various aberrations. More preferably, the following range is used.
| ΣΔP _i × f | <0.08 (4a)
Further, when the refractive index at the d-line of the material forming the interface A having a variable shape is N _A f and N _A r, the following conditions are satisfied.
_{0.0005 <| N A f-N} A r | <0.2 ··· (5)
If the condition of the upper limit of the expression (5) is not satisfied, the aberration generated when the shape of the interface A is deformed increases, and the correction cannot be completely performed at another interface having a variable shape. Further, if the lower limit condition is not satisfied, the degree of freedom of material selection is lost, and the difficulty of material production increases.
The formula (5) is preferably set within the following range.
_{0.001 <| N A f-N} A r | <0.1 ··· (5a)

In addition, when the two materials forming the shape-variable interface A have substantially the same refractive index at the d-line, at least one shape-variable interface B that satisfies the following expression (6) is satisfied. With the above-described configuration, it is possible to have a configuration in which chromatic aberration fluctuations that occur when the shape of the interface changes are suppressed.
Δφc _A × Δφc _B <0 (6)

で与えられる。また、形状可変な界面Ａと形状可変な界面Ｂのいずれか又は双方が複数含まれている場合は、界面Ａｉの形状が変化したときの色収差変動量をΔφｃＡｉ、界面Ｂiの界面形状が変化したときの色収差変動量をΔφｃＢｉとしたとき、全ての該界面Ａiの色収差変動量の総和ΔφｃＡ、全ての界面Ｂｉの色収差変動量の総和ΔφｃＢは、

で与えられる。ただし、
ｒ_Ａｉａ：形状可変な界面Ａ_ｉの曲率が最も小さい時の曲率半径、
ｒ_Ａｉｂ：形状可変な界面Ａ_ｉの曲率が最も大きい時の曲率半径、
ν_Ａｉｆ：形状可変な界面Ａ_ｉの物体側の材料のアッベ数、
ν_Ａｉｒ：形状可変な界面Ａ_ｉの像側の材料のアッベ数、
ｒ_Ｂｉａ：形状可変な界面Ｂ_ｉの曲率が最も小さい時の曲率半径、
ｒ_Ｂｉｂ：形状可変な界面Ｂ_ｉの曲率が最も大きい時の曲率半径、
ν_Ｂｉｆ：形状可変な界面Ｂ_ｉの物体側の材料のアッベ数、
ν_Ｂｉｒ：形状可変な界面Ｂ_ｉの像側の材料のアッベ数、
である。 Here, Δφc _A and Δφc _B are chromatic aberration fluctuation amounts of the shape-variable interface A and the shape-variable interface B, respectively.

Given in. In addition, when one or both of the shape-variable interface A and the shape-variable interface B are included, the amount of chromatic aberration variation when the shape of the interface Ai changes is ΔφcAi, and the interface shape of the interface Bi changes. When the amount of chromatic aberration fluctuation at that time is ΔφcBi, the total amount ΔφcA of the chromatic aberration variation amount of all the interfaces Ai and the total amount ΔφcB of the chromatic aberration variation amounts of all the interfaces Bi are

Given in. However,
r _Ai a: the radius of curvature when the curvature of the shape-variable interface A _i is the smallest,
r _Ai b: radius of curvature when the curvature of the variable shape interface A _i is the largest,
[nu _Ai f: Abbe number of the object side of the material of the deformable interface _{A i,}
[nu _Ai r: Abbe number of the image side of the material of the deformable interface _{A i,}
r _Bi a: radius of curvature when the curvature of the shape variable interface B _i is the smallest,
r _Bi b: radius of curvature when the curvature of the shape variable interface B _i is the largest,
ν _Bif : Abbe number of material on the object side of the shape variable interface B _i ,
ν _Bi r: Abbe number of the material on the image side of the shape variable interface B _i ,
It is.

At this time, when the refractive index relating to the light beam having the wavelength λ is nλ, the g-line (435.8 nm), the F-line (486.1 nm), the d-line (587.6 nm), and the C-line ( The refractive index for 656.3 nm is expressed as ng, nF, nd, nC, respectively. The Abbe numbers νd for the d-line are respectively expressed as follows.
νd = (nd−1) / (nF−nC)

Furthermore, when the sum of all of the interface i deformable chromatic aberration variation at the interface i Derutafaishi _i and DerutafaiC, and total DerutafaiC satisfies the condition below, it is possible to obtain an optical system which suppresses a more chromatic variations.
−0.05 <ΔφC × f <0.05 (7)

である。ここで、
ν_ｉｆ：形状可変な界面ｉを形成する物体側の材料のｄ線におけるアッベ数、
ν_ｉｒ：形状可変な界面ｉを形成する像側の材料のｄ線におけるアッベ数、
ｒ_ｉａ：界面ｉの曲率が最も小さい時の曲率半径、
ｒ_ｉｂ：界面ｉの曲率が最も大きい時の曲率半径、
である。 However,

It is. here,
ν _i f: Abbe number in d-line of the material on the object side that forms the variable-shape interface i,
ν _i r: Abbe number at the d-line of the image-side material forming the variable-shape interface i,
r _i a: radius of curvature when the curvature of the interface i is the smallest,
r _i b: radius of curvature when the curvature of the interface i is the largest,
It is.

At this time, the deformable interface A to form, respectively [nu _{A f} the Abbe number of the material, when formed into a [nu _{A r,} that the following conditions are satisfied, the configuration also chromatic aberration fluctuation is small in the case of changing the interface shape can do.
0.1 <| ν _A f−ν _A r | <30 (8)
Further, the shape-variable interface A having a variable apodization effect is preferably in the vicinity of the stop.

When the interface A is moved away from the stop position, the positions where the on-axis light beam and the off-axis light beam enter the interface A are different. For this reason, the apodization effect varies depending on the angle of view of the out-of-focus image.
Specifically, when the distance between the shape-variable interface A and the aperture position at the time of focusing on an infinite object is LA and the optical total length is L, the following conditional expression is satisfied. An apodization effect can be obtained.
0.01 <LA / L <0.15 (9)
However, when the value of the equation (9) changes due to the change in the interface shape, LA and L indicate values when the absolute value of the curvature of the interface A is the largest.

In the above formula (6), it has been described that it is desirable that the signs of the chromatic aberration fluctuation amounts at the interfaces A and B are opposite. This is considered by applying to axial chromatic aberration and lateral chromatic aberration.
Regarding axial chromatic aberration, since the amount of aberration is proportional to the square of the axial light height, the sign of the amount of chromatic aberration variation when the interface shape changes is reversed, as shown in equation (6), regardless of the front and rear of the aperture. Otherwise, axial chromatic aberration cannot be corrected.
However, with respect to lateral chromatic aberration, since the amount of aberration is proportional to the off-axis light flux height, if there is a variable shape interface before and after the stop, each amount of aberration cannot be canceled. It will increase.

Therefore, by arranging at least one of the shape-variable interfaces different from the shape-variable interface A on the same side as the interface A with respect to the stop, both axial chromatic aberration and lateral chromatic aberration are corrected well. be able to.
Further, when changing the interface shape of the shape-variable interface A, by simultaneously moving at least one group interval, the degree of freedom of aberration correction increases, and it becomes easy to correct various aberrations satisfactorily. .

Hereinafter, specific examples of the optical system using the shape variable element described above will be described.
The optical system of each embodiment is a photographic lens system used in an imaging apparatus such as a video camera, a digital still camera, or a silver salt film camera. In the lens cross-sectional view, the left side is the object side (front), and the right side is the image side (rear).
The lens group is a portion divided by the lens interval in the optical axis direction that changes by zooming or focusing. In addition, for optical image stabilization, a block that operates in a direction perpendicular to the optical axis may be used as a lens group.
In the lens cross-sectional view, i indicates the order of the lenses from the object side, and Li is the i-th lens group. SP is an aperture stop. IP is an image plane, and a photosensitive surface corresponding to an imaging surface of a solid-state imaging device and a film surface of a silver salt film camera in the imaging apparatus is disposed.

AOj (j = 1, 2, 3,...) Represents a shape variable element. The optical system of each embodiment includes at least one shape variable element.
In the aberration diagrams, d, g, C, and F indicate aberrations related to the d-line, g-line, C-line, and F-line, respectively. ΔM and ΔS are a meridional image plane and a sagittal image plane, respectively. Lateral chromatic aberration is represented by the g-line. ω is a half angle of view, and Fno is an F number.

FIGS. 5A and 5B are optical systems of Example 1 (Numerical Example 1), and the lens cross section in the state where the curvature of the interface A is the largest and the smallest when the object at infinity is in focus. FIG.
In order from the object side to the image side, a first lens unit L1 having a positive refractive power, an aperture stop SP, and a second lens unit L2 having a positive refractive power are provided, and the shape variable element AO1 and the shape variable element AO2 are opened. This is an optical system with a focal length of 135 mmF2.83 arranged on the image side of the stop SP.
The optical system moves the entire lens (L1, L2) to the object side during focusing, and at the same time moves the second lens unit L2, so that close-up photography from an infinite object to an imaging magnification of -0.25 times is performed. Is possible.

The variable shape element AO1 close to the aperture stop SP has a lens portion L1f made of a non-electrolyte material on the object side and a low transmittance (absorption coefficient α = 0.4), and a lens made of an electrolyte on the image side. A portion L1r is included, and the interface shape can be changed electrically.
In addition, the shape variable element AO2 has a lens portion L2f made of a non-electrolyte on the object side and a lens portion L2r made of an electrolyte on the image side, and is configured to be able to electrically change the interface shape. The liquid that forms the lens portions L2f and L2r is substantially transparent in the visible range.
In the variable shape element AO1, the lens portion L1f made of a material having low transmittance has a negative power.

In FIG. 5A, the curvature of the shape variable element AO1 is the largest. At this time, the light beam passing through the lens portion L1f has a configuration in which the transmittance decreases as the height of the light beam from the optical axis increases, and the outline of the out-of-focus image can be blurred. FIG. 5B shows a state where the curvature of the shape variable element AO1 is the smallest. At this time, the light beam passing through the lens portion L1f has a uniform transmittance distribution in the light beam, and the outline of the out-of-focus image can be clearly seen as compared with the state of FIG.
Further, by changing the curvature of the variable shape element AO1 and simultaneously changing the curvature of the variable shape element AO2, the aberration variation occurring in the variable shape element AO1 is corrected, and the optical system as a whole is corrected for various aberrations. ing.

  FIGS. 6A and 6B are aberration diagrams of the state in which the curvature of the interface A is the largest and the state in the smallest state at the time of focusing on an object at infinity of the optical system of Example 1, respectively. ) Is an aberration diagram in a state where the curvature of the interface A is the largest at an imaging magnification of −0.25. 6A, 6B, and 6C show that the optical system as a whole is an optical system in which various aberrations are corrected.

FIGS. 7A and 7B are optical systems of Example 2 (Numerical Example 2), and the lens cross section in the state where the curvature of the interface A is the largest and the smallest when the object at infinity is in focus. FIG.
In order from the object side to the image side, a first lens unit L1 having a positive refractive power, an aperture stop SP, and a second lens unit L2 having a positive refractive power are provided, and the shape variable element AO1 and the shape variable element AO2 are opened. This is an optical system with a focal length of 135 mmF2.83 arranged on the image side of the stop SP.
The optical system moves the entire lens (L1, L2) to the object side during focusing, and at the same time moves the second lens unit L2, so that close-up photography from an infinite object to an imaging magnification of -0.25 times is performed. Is possible.

The variable shape element AO1 close to the aperture stop SP has a lens portion L1f made of a material (absorption coefficient α = 0.51) made of an electrolyte on the object side and a non-electrolyte on the image side. A portion L1r is included, and the interface shape can be changed electrically.
Further, the shape variable element AO2 has a lens portion L2f made of an electrolyte on the object side and a lens portion L2r made of a non-electrolyte on the image side, and is configured to be able to electrically change the interface shape. The liquid that forms the lens portions L2f and L2r is substantially transparent in the visible range.

Further, the variable shape elements AO1 and AO2 are configured such that the refractive index at the d-line is substantially the same and only the Abbe number is different.
The variable shape element AO1 gives negative power to the lens portion L1f made of a material with low transmittance, and the apodization effect of the out-of-focus image can be changed by changing the curvature of the interface shape as in the first embodiment. It can be configured.
Further, by changing the curvature of the variable shape element AO1 and simultaneously changing the curvature of the variable shape element AO2, the chromatic aberration variation caused by the variable shape element AO1 is corrected, and the optical system as a whole is corrected for various aberrations. ing.

  FIGS. 8A and 8B are aberration diagrams of the state in which the curvature of the interface A is the largest and the state in the smallest state at the time of focusing on an object at infinity of the optical system of Example 2, respectively. ) Is an aberration diagram in a state where the curvature of the interface A is the largest at an imaging magnification of −0.25. 8A, 8B, and 8C that the optical system as a whole is an optical system in which various aberrations are corrected.

FIGS. 9A and 9B show the optical system of Example 3 (Numerical Example 3), in which the curvature of the interface A is the largest and the smallest when the object at infinity is in focus. It is lens sectional drawing.
In order from the object side to the image side, a first lens unit L1 having a positive refractive power, an aperture stop SP, and a second lens unit L2 having a positive refractive power are provided, and the shape variable element AO1 and the shape variable element AO2 are opened. This is an optical system with a focal length of 135 mmF2.83 arranged on the image side of the stop SP.
The optical system moves the entire lens (L1, L2) to the object side during focusing, and at the same time moves the second lens unit L2, so that close-up photography from an infinite object to an imaging magnification of -0.25 times is performed. Is possible.

The variable shape element AO1 close to the aperture stop SP has a lens portion L1f made of a non-electrolyte material (absorption coefficient α = 0.67) on the object side and a lens made of an electrolyte on the image side. A portion L1r is included, and the interface shape can be changed electrically.
In addition, the shape variable element AO2 has a lens portion L2f made of a non-electrolyte on the object side and a lens portion L2r made of an electrolyte on the image side, and is configured to be able to electrically change the interface shape. The liquid that forms the lens portions L2f and L2r is substantially transparent in the visible range.
The variable shape element AO1 gives negative power to the lens portion L1f made of a material with low transmittance, and the apodization effect of the out-of-focus image can be changed by changing the curvature of the interface shape as in the first embodiment. It can be configured.

Further, by changing the curvature of the variable shape element AO1 and simultaneously changing the curvature of the variable shape element AO2, the aberration variation occurring in the variable shape element AO1 is corrected, and the optical system as a whole is corrected for various aberrations. ing.
FIGS. 10A and 10B are aberration diagrams of the state in which the curvature of the interface A is the largest and the state in the smallest state at the time of focusing on an object at infinity of the optical system of Example 3, respectively. ) Is an aberration diagram in a state where the curvature of the interface A is the largest at an imaging magnification of −0.25. 10A, 10B, and 10C that the optical system as a whole is an optical system in which various aberrations are corrected.

FIGS. 11A and 11B show the optical system of Example 4 (Numerical Example 4), which has a state in which the curvature of the interface A is the largest and a state in which it is the smallest when an object at infinity is in focus. It is lens sectional drawing.
In order from the object side to the image side, a first lens unit L1 having a positive refractive power, an aperture stop SP, and a second lens unit L2 having a positive refractive power are provided, and the shape variable element AO1 and the shape variable element AO2 are opened. This is an optical system with a focal length of 135 mmF2.83 arranged on the image side of the stop SP.
The optical system moves the entire lens (L1, L2) to the object side during focusing, and at the same time moves the second lens unit L2, so that close-up photography from an infinite object to an imaging magnification of -0.25 times is performed. Is possible.

The variable shape element AO1 close to the aperture stop SP has a lens portion L1f made of a material (absorption coefficient α = 0.49) made of an electrolyte on the object side and a non-electrolyte on the image side. A portion L1r is included, and the interface shape can be changed electrically.
Further, the shape variable element AO2 has a lens portion L2f made of an electrolyte on the object side and a lens portion L2r made of a non-electrolyte on the image side, and is configured to be able to electrically change the interface shape. The liquid that forms the lens portions L2f and L2r is substantially transparent in the visible range.
The variable shape element AO1 gives negative power to the lens portion L1f made of a material with low transmittance, and the apodization effect of the out-of-focus image can be changed by changing the curvature of the interface shape as in the first embodiment. It can be configured.

Further, by changing the curvature of the variable shape element AO1 and simultaneously changing the curvature of the variable shape element AO2, the aberration variation occurring in the variable shape element AO1 is corrected, and the optical system as a whole is corrected for various aberrations. ing.
Further, in the fourth embodiment, the curvature of the shape variable element AO2 can be changed even during close-up object shooting. As a result, an aberration variation due to a change in object distance can be further suppressed, and an optical system in which aberrations from an object at infinity to a close object are well corrected is obtained.

  FIGS. 12A and 12B are aberration diagrams of the state in which the curvature of the interface A is the largest and the state in the smallest state at the time of focusing on an object at infinity of the optical system of Example 4, respectively. ) Is an aberration diagram in a state where the curvature of the interface A is the largest at an imaging magnification of −0.25. 12A, 12B, and 12C show that the optical system as a whole is an optical system in which various aberrations are corrected.

FIGS. 13A and 13B show the optical system of Example 5 (Numerical Example 5) shown in FIG. 13, in which the curvature of the interface A is the largest and the smallest when the object at infinity is in focus. It is lens sectional drawing.
In order from the object side to the image side, the lens unit includes a first lens unit L1 having positive refractive power, an aperture stop SP, and a second lens unit L2 having positive refractive power, and includes a shape variable element AO1, a shape variable element AO2, and a shape. This is an optical system having a focal length of 135 mmF2.83, in which the variable element AO3 is disposed on the image side of the aperture stop SP.
The optical system moves the entire lens (L1, L2) to the object side during focusing, and at the same time moves the second lens unit L2, so that close-up photography from an infinite object to an imaging magnification of -0.25 times is performed. Is possible.

Further, the variable shape element AO1 close to the aperture stop SP has a lens portion L1f made of a material (absorption coefficient α = 0.37) made of a non-electrolyte on the object side and a lens made of an electrolyte on the image side. A portion L1r is included, and the interface shape can be changed electrically.
In addition, the shape variable element AO2 has a lens portion L2f made of a non-electrolyte on the object side and a lens portion L2r made of an electrolyte on the image side, and is configured to be able to electrically change the interface shape. The liquid that forms the lens portions L2f and L2r is substantially transparent in the visible range.
The variable shape element AO3 includes a lens portion L3f made of an electrolyte on the object side and a lens portion L3r made of a non-electrolyte on the image side, and is configured to be able to electrically change the interface shape. The liquid that forms the lens portions L3f and L3r is substantially transparent in the visible range.

The variable shape element AO1 gives negative power to the lens portion L1f made of a material with low transmittance, and the apodization effect of the out-of-focus image can be changed by changing the curvature of the interface shape as in the first embodiment. It can be configured.
Further, by changing the curvature of the shape variable element AO1 and simultaneously changing the curvature of the shape variable element AO2 and the curvature of the shape variable element AO3, the aberration variation generated in the shape variable element AO1 is corrected, and various aberrations of the entire optical system are achieved. Is a corrected optical system.

  FIGS. 14A and 14B are aberration diagrams of the state in which the curvature of the interface A is the largest and the state in the smallest state at the time of focusing on an object at infinity of the optical system of Example 5, respectively. ) Is an aberration diagram in a state where the curvature of the interface A is the largest at an imaging magnification of −0.25. 14A, 14B, and 14C that the optical system as a whole is an optical system in which various aberrations are corrected.

FIGS. 15A and 15B show the optical system of Example 6 (Numerical Example 6), and the lens cross section in the state where the curvature of the interface A is the largest and the smallest when the object at infinity is in focus. FIG.
In order from the object side to the image side, the lens unit includes a first lens unit L1 having positive refractive power (including an aperture stop SP) and a second lens unit L2 having positive refractive power, and includes a shape variable element AO1 and a shape variable element AO2. Is an optical system having a focal length of 180 mmF3.5, arranged on the image side of the aperture stop SP.
During focusing, the entire lens (L1, L2) is moved toward the object side and at the same time, the second lens unit L2 is moved to increase the object distance imaging magnification from -infinity to -0.11 times. Close-up photography is possible.

The variable shape element AO1 close to the aperture stop SP has a lens portion L1f made of a non-electrolyte on the object side and made of a material having a low transmittance (absorption coefficient α = 0.50), and a lens made of an electrolyte on the image side. A portion L1r is included, and the interface shape can be changed electrically.
In addition, the shape variable element AO2 has a lens portion L2f made of a non-electrolyte on the object side and a lens portion L2r made of an electrolyte on the image side, and is configured to be able to electrically change the interface shape. The liquid that forms the lens portions L2f and L2r is substantially transparent in the visible range.
The variable shape element AO1 gives negative power to the lens portion L1f made of a material with low transmittance, and the apodization effect of the out-of-focus image can be changed by changing the curvature of the interface shape as in the first embodiment. It can be configured.
Further, by changing the curvature of the variable shape element AO1 and simultaneously changing the curvature of the variable shape element AO2, the aberration variation occurring in the variable shape element AO1 is corrected, and the optical system as a whole is corrected for various aberrations. ing.

  FIGS. 16A and 16B are aberration diagrams of the state in which the curvature of the interface A is the largest and the state in the smallest state at the time of focusing on an object at infinity of the optical system of Example 6, respectively. ) Is an aberration diagram in a state where the curvature of the interface A is the largest when the closest object is in focus. 16A, 16B, and 16C show that the optical system as a whole is an optical system in which various aberrations are corrected.

  Hereinafter, specific numerical data of each example (numerical example) is shown. In each embodiment, i represents the surface number counted from the object side. Ri is the radius of curvature of the i-th optical surface (i-th surface), and Di is the axial distance between the i-th surface and the (i + 1) -th surface. The unit of distance is expressed as millimeters.

Ndi and νdi represent the refractive index and Abbe number of the material of the i-th optical member with respect to the d-line, respectively.
In addition, “E ± XX” in each numerical value means “× 10 ^{± XX} ”.
Fno is an effective F number, ω is a half angle of view, and the unit is degrees.
Table 7 shows the relationship between the conditional expressions (1) to (9) and numerical examples.
As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

In Examples 1 to 4 and 6 described above, the difference Δα (mm ⁻¹ ) in the absorption coefficient at the d line is
0.2 <| Δα | <1.5 (1)
The optical system having one surface each having the shape variable interface A made of two materials satisfying the above and the shape variable interface B not satisfying the expression (1) has been described. In the fifth embodiment described above, an optical system having one shape-variable interface A that satisfies the equation (1) and two shapes-variable interfaces B that do not satisfy the equation (1) has been described as an example. However, the present invention is not limited to this configuration. The effect of the present invention can be obtained even when there is a plurality of either or both of the shape-variable interface A that satisfies the equation (1) and the shape-variable interface B that does not satisfy the equation (1). In that case, for the power variation Derutafaiei by the sum of the power variation Derutafaiei _i for the individual interfacial A _i, for power variation DerutafaiB the sum of power variation DerutafaiB _i for the individual interfacial B _i On the other hand, the formula (2) may be applied. Also, the chromatic aberration variation DerutafaicA by the sum of the chromatic aberration variation DerutafaicA _i for the individual interfacial _{A i,} the chromatic aberration variation DerutafaicB with respect to the sum of the chromatic variation DerutafaicB _i for the individual interfacial _{B i,} equation (6) Should be applied.

  In the first to sixth embodiments, an example in which one shape variable element has one shape variable interface is described, but the present invention is not limited to this. Even when one shape variable element has two or more shape-variable interfaces, whether each shape-variable interface is an interface A that satisfies the expression (1) or an interface B that is not seen. By judging and applying the present invention, the effects of the present invention can be enjoyed.

  In addition, by configuring an imaging apparatus including the lens apparatus including the optical system of the first to sixth embodiments and a camera apparatus that includes the imaging element and captures a subject image formed on the imaging element by the lens apparatus. It is possible to realize an image pickup apparatus in which various aberrations are favorably corrected while realizing the apodization effect of the present invention.

AO1 variable shape element AO2 variable variable element

Claims (13)

An optical system comprising a shape variable element made of a plurality of optical materials and changing the surface shape of the interface,
The difference Δα (mm ⁻¹ ) in the absorption coefficient at the d line is
0.2 <| Δα | <1.5
Two or more shape-variable interfaces, including a shape-variable interface A formed from two materials satisfying the above and a shape-variable interface B formed from two materials not satisfying the above conditional expression,
When the refractive power change amount at the i-th interface A _i of the interface A is Δφ _Ai and the refractive power change amount at the i-th interface B _i of the interface B is Δφ _Bi , all the interfaces A The total Δφ _A of the refractive power change amount at λ and the total Δφ B of the refractive power change amount at all the interfaces _B are
Δφ _A × Δφ _B <0,
An optical system characterized by satisfying
However,

_{Here, N Ai f,} N Ai r is the refractive index at each d-line of the object side of the material and the image side of the material forming the interfacial _{A i, r Ai a, r} Ai b respectively interfacial _{A i} N _Bi f and N _Bi r are the refractive indices at the d-line of the object side material and the image side material forming the interface B _i , respectively. _{Bi a,} the radius of curvature of the large time and when r Bi _b is the smallest respective curvature of the interface B _i. Forming the variable shape interface i, of the object-side material and the image side of the material, the refractive index of each N _{i f,} N i _r at the d-line, and when the interface i is shape change 2. The optical system according to claim 1, wherein the following conditional expression is satisfied, where ΔP _i is a change amount of the Petzval sum.
| ΣΔP _i × f | <0.1
However,

Here, f is the focal length of the optical system when the object at infinity is in focus and the curvature of the interface i is the largest, r _i a is the radius of curvature when the curvature of the interface i is the smallest, and r _i b is the interface This is the radius of curvature when i has the largest curvature. When the refractive index at the d-line of the material forming the variable interface A is N _A f and N _A r respectively,
_{0.0005 <| N A f-N} A r | <0.2
The optical system according to claim 1, wherein: In an optical system comprising a plurality of optical materials and having a variable shape element that changes the surface shape of the interface,
The difference Δα (mm ⁻¹ ) in the absorption coefficient at the d line is
0.2 <| Δα | <1.5
Two or more shape-variable surfaces including a shape-variable interface A formed from two materials that satisfy the above condition and a shape-variable interface B formed from two materials that do not satisfy the above conditional expression,
Among the interface A, i th interfacial A _i Δφc _Ai chromatic aberration variation amount when the shape is changed _in, among the interface B, the chromatic aberration fluctuation amount when the interface shape changes in i-th surface B _i Is Δφc _Bi , the total Δφc _A of all the chromatic aberration variations of the interface _A and the total Δφc B of all the chromatic aberration variations of the interface _B are:
Δφc _A × Δφc _B <0
An optical system characterized by satisfying
However,

_{Here, r Ai a,} r Ai b is the radius of curvature of the time when and large respectively curvature of the interface _{A i} is the smallest, ν _Ai f, the object side and the image side of the [nu _Ai r each the interface _{A i} materials are the Abbe _{number, r Bi a,} r Bi b is the radius of curvature of the time when and large respectively curvature of the interface _{B i} is smallest, ν _Bi f, ν _Bi r is the interfacial _{B i} respectively It is the Abbe number of the material on the object side and the image side. When the distance between the shape-variable interface A and the stop when focusing on an infinite object is LA and the optical total length is L,
0.01 <LA / L <0.15
The optical system according to claim 1, wherein: Chromatic aberration variation Derutafaishi _i when changing the shape of the deformable interface i, the sum of all the interfacial i DerutafaiC, the focal length f at the time of infinite object if, to satisfy the following condition The optical system according to claim 1, wherein:
−0.05 <ΔφC × f <0.05
However,

Here, the Abbe numbers in the d-line of the object side material and the image side material forming the shape-variable interface i are v _i f and v _i r, respectively, and the curvature when the curvature of the interface i is the smallest. The radius is r _i a, and the radius of curvature when the curvature of the interface i is the largest is r _i b. When the Abbe numbers in the d-line of the object-side and image-side materials that form the shape-variable interface A are ν _A f and ν _A r, respectively.
0.1 <| ν _A f−ν _A r | <30
The optical system according to claim 1, wherein:   The shape changeable interface A and one or more shape changeable interfaces different from the interface A are arranged on the same side with respect to the stop. The optical system according to item.   The optical system according to any one of claims 1 to 8, wherein the optical system changes two or more shape-variable interfaces at the same time when photographing an object at the same distance. In the optical system, when the amount of change in the focal length when the shape-variable interface is changed at the same distance object shooting is Δf, and the focal length of the optical system is f,
−0.05 <Δf / f <0.05
The optical system according to claim 1, wherein:   11. The optical system according to claim 1, wherein when the interface shape of the shape-variable interface A is changed, the interval between the one or more lens groups is changed.   The optical system according to claim 1, wherein the shape-variable interface is made of a plurality of liquid materials that are not mixed with each other.   An imaging apparatus comprising: a lens apparatus including the optical system according to any one of claims 1 to 12; and a camera apparatus that includes an imaging element and images a subject image formed on the imaging element by the lens apparatus. .

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