JP2001042212A - Bonded lens and optical system using the bonded lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate production and to obtain a high aspherical effect and high optical performance by making the bonded surface of an element made of material having a higher refractive index aspherical and making the bonded surface of an element made of material having a lower refractive index spherical. SOLUTION: Both lenses L1 and L2 having positive or negative refractive power are bonded by an adhesive CM. Signs of refractive power of the lenses L1 and L2 are different. The refractive index NH of the material. of the lens L1 is higher than the refractive index NL of the material of the lens L2. As for the bonded surface, the surface (concave surface) L1R of the lens L1 made of the material having the higher refractive index is made aspherical and the surface (convex surface) L2R of the lens L2 made of the material having the lower refractive index is made spherical. It is conceivable to set the surface L2R which is not aspherical to be plane. The lens L1 and the lens L2 are bonded so that the bonded surface may be marginal contact. Namely, the bonded surface of the lens made of the material having the lower refractive index is integrated with an adhesive by utilizing that difference of the refractive index from the adhesive is small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cemented lens and an optical system using the same, for example, a photographic optical system such as a video camera and a film camera, an optical system for measurement, an optical system for observation such as a finder, and a laser. The present invention is applicable to optical devices using various optical systems such as optical systems for office machines such as beam printers and copiers.

[0002]

2. Description of the Related Art Many optical systems conventionally used in optical instruments use an aspherical surface as a means for improving optical performance.

Further, as a means for correcting chromatic aberration in optical performance, there is often used a cemented lens in which a positive lens and a negative lens made of materials having different dispersions are cemented.

Further, an optical system in which an aspherical surface is introduced into a cemented surface of a cemented lens to improve optical performance is disclosed in, for example, Japanese Patent No. 2525.
No. 96799, Japanese Patent No. 2596827, Japanese Patent No. 264
No. 1515 and Japanese Patent Publication No. 4-5362,
Various proposals have been made in 282407 and the like.

[0005] However, there is no technical disclosure regarding the case where the cemented surface of the cemented lens is specifically made to be aspherical in the lens systems proposed in these. That is, in most of the conventional optical systems, only the description that "the bonding surface is an aspheric surface" is described, and even in the embodiment, only one bonding surface is recognized. Therefore, if interpreted literally, there are many cases in which the surface to be provided for bonding of the cemented lens is formed with exactly the same aspherical unevenness, and then the embodiment is not performed unless the surface is cemented.

However, in this case, two surfaces to be joined must be made aspherical. Further, if one of the surfaces has the same shape and the other is concave, the other needs to be formed with a high degree of accuracy and the accuracy is also high. It is not realistic in terms of cost.

For example, Japanese Patent No. 2596799 discloses an example in which an aspherical surface is positively introduced into a microscope objective lens, and Examples 1 and 3 propose that the joining surface is an aspherical surface. .

However, there is no disclosure of a specific technique other than the fact that the cemented surface is an aspherical surface, and the present invention relates to "including an objective lens with a cemented surface" and "introducing an aspherical surface into an objective lens".
Is only treated separately and is effective.

In Japanese Patent No. 2596827, in order to improve the optical performance of an objective lens for an endoscope, the objective lens is divided into two lenses in a front group, and an aspheric surface is introduced into each lens group. One having a cemented lens in the group is proposed.

In this case, however, the bonding surface is aspherical in the tenth embodiment of the numerical example. However, although the condition that a predetermined conditional expression (not described) is separately mentioned as a requirement, the bonding surface is positively determined. Does not claim to make the surface aspheric.

Further, Japanese Patent No. 2641515 proposes an achromatic objective lens such as a microscope.

At this time, when an objective lens is constituted only by a cemented lens, it is proposed that two of the three surfaces of the cemented lens be made aspherical to increase the degree of freedom of aberration correction.

Although numerical examples 1, 2 and 3 disclose that the joining surface is made aspherical, it is also not intended to make the joining surface aspherical positively. No disclosure was made.

In Japanese Patent Publication No. 4-5362, an objective lens for an optical disc requires a cemented lens in order to perform good aberration correction with respect to two wavelengths. In order to prevent this, the joining surface is made aspherical.

Therefore, this only mentions that the "joining surface" is an aspherical surface, and does not disclose any more specific technical details, and all six examples of the present invention relate to a cemented lens. Are all aspherical.

Japanese Patent Application Laid-Open No. 10-282407 proposes an achromatic condition unique to an aspheric surface by positively making an aspherical surface of a cemented surface. The surface to be provided must be formed with exactly the same aspherical irregularities, and then joined together. "

[0017]

It is useful to make the cemented surface aspherical as a method of increasing the degree of freedom in correcting aberrations of the cemented lens and obtaining a predetermined aspherical effect without requiring high processing accuracy. Technology.

However, it is very difficult to manufacture a cemented lens having an aspherical joint surface with high precision.

The present invention can be easily manufactured by appropriately setting the surface shape of the joining surface when the joining surface is made aspherical.
Moreover, it is an object of the present invention to provide a cemented lens capable of easily obtaining a high aspherical effect and high optical performance, and an optical system using the same.

[0020]

According to a first aspect of the present invention, there is provided a cemented lens in which two or more elements having different refractive indices of materials are cemented. It is characterized in that the joining surface of the element having the higher refractive index of the material is an aspherical surface, and the joining surface of the element having the lower refractive index is a spherical surface.

The cemented lens according to the second aspect of the present invention is a cemented lens in which two or more elements having different refractive indices of a material are joined to each other. The joint surface of the element having the lower refractive index is an aspheric surface, and the joint surface of the element having the lower refractive index is a flat surface.

According to a third aspect of the present invention, in the first or second aspect, the reference spherical surface radius of one of the joining surfaces of the two joining elements is RN, and the reference spherical surface radius of the other surface is RP. 0 ≦ | RN / RP | <1.0 (However, the reference spherical radius is the radius of a circle connecting a point intersecting the optical axis of the curved surface with the effective diameter of the curved surface or a point intersecting the outer peripheral portion.) Is satisfied.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the joining surface of the two joining elements is formed by joining a concave surface and a convex surface. RN, where RP is the reference spherical radius of the convex surface of the other element, 0 <| RN / RP | <1.0 (where the reference spherical radius is the effective diameter of the curved surface at the point of intersection with the optical axis of the curved surface, or the outer peripheral portion) And the radius of a circle connecting the points that intersect with.).

According to a fifth aspect of the present invention, in the invention of any one of the first to fourth aspects, when the difference between the Abbe numbers of the materials of the two joined elements is Δν, Δν> 10. It is characterized by.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, a refractive index (NH) of an element having a higher refractive index of a material among the two joined elements is higher. When the value is 1.6 or more, a non-dielectric film having a refractive index of N and satisfying a condition of 1.6 <N <NH is deposited on the element.

According to a seventh aspect of the present invention, in the first aspect of the present invention, the two joined elements are a positive lens and a negative lens.

The optical system according to the eighth aspect of the present invention is the optical system according to the first to seventh aspects.
Characterized in that it has the cemented lens of any one of the above.

According to a ninth aspect of the present invention, there is provided an optical apparatus including the optical system according to the eighth aspect.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of a principal part near a cemented surface of a cemented lens according to a first embodiment of the present invention. In FIG. 1, L1 is a lens having a positive or negative refractive power, L2 is a lens having a positive or negative refractive power, and both lenses are joined by an adhesive CM.

In this embodiment, the signs of the refractive power of the lens L1 and the lens L2 are different. The refractive index NH of the material of the lens L1 is higher than the refractive index NL of the material of the lens L2. The lens L1 having the higher refractive index of the material among the surfaces to be joined
(Concave surface) L1R is an aspheric surface, and the surface (convex surface) L2R of the lens L2 having the lower refractive index of the material is a spherical surface. Here, the non-aspheric surface L2R may be a flat surface.
The joining surfaces of the lenses L1 and L2 are in marginal contact.

The cemented lens of the present invention is used alone or as a part of a lens system such as a photographing lens, a measuring lens, and a condenser lens. It is also used for a part of an optical system constituting an optical device.

FIG. 2 is a sectional view of a principal part near a cemented surface of a cemented lens according to a second embodiment of the present invention. In FIG. 2, L1 is a lens having a positive or negative refractive power, L2 is a lens having a positive or negative refractive power, and both lenses are joined by an adhesive CM.

In this embodiment, the sign of the refractive power of the lens L1 is different from that of the lens L2. The refractive index NH of the material of the lens L2 is higher than the refractive index NL of the material of the lens L1. The lens L2 having the higher refractive index of the material among the surfaces to be joined.
(Convex surface) L2R is an aspheric surface, and the surface (concave surface) L1R of the lens L1 having the lower refractive index of the material is a spherical surface. Here, the non-aspheric surface L1R may be a flat surface.
The joining surfaces of the lenses L1 and L2 are in marginal contact.

The cemented lens of this embodiment is a cemented lens composed of a lens, a parallel plane plate, and two or more elements (optical elements) such as a cylindrical lens and an anamorphic lens, for example, a cemented lens composed of a positive lens and a negative lens. The joining surface of the element having the higher refractive index of the material is made aspherical, and the other is made spherical (or flat).

That is, strictly speaking, the joining surface is in a state in which a thin layer of the adhesive CM is filled between the two surfaces.

In order for the cemented lens to achieve one of its purposes, achromatism, sufficiently effectively, the elements to be cemented must have an appropriate refractive index difference.

This embodiment focuses on the difference in the refractive index between the adhesive and the element to be joined, and makes the surface having the higher refractive index among the elements to be joined an aspheric surface, thereby exhibiting the aspheric effect. The other is made easy by making it remain spherical or flat.

That is, the bonding surface of the material having the lower refractive index is integrated with the adhesive by utilizing the fact that the difference in the refractive index from the adhesive is small, and the bonding surface of the material having the higher refractive index is bonded. The effect is utilized by using only the difference in refractive index from the agent as the amount of aspherical surface.

In general, as compared with an aspherical surface having an interface with air or vacuum, the aspherical refractive power which is related to the amount of change of the aspherical surface is attenuated. However, according to this embodiment, the sensitivity of the aspherical surface to the surface accuracy is also attenuated. Therefore, the processing accuracy can be kept low. Attenuation of the aspherical refractive power, which affects the amount of aspherical change, can be compensated for by increasing the amount of aspherical surface, but the sensitivity to the surface accuracy of the aspherical surface remains low and processing becomes easier. .

In the cemented lens of the present invention, it is more preferable to satisfy at least one of the following conditions.

(A-1) In the cemented lens, when the reference spherical surface radius of the concave surface among the cemented surfaces of the elements is RN and the reference spherical surface radius of the convex surface is RP, 0 ≦ | RN / RP | <1.0 Satisfies ‥‥‥ (1). (However, the reference spherical radius is the radius of a circle connecting a point intersecting the optical axis of the curved surface with the effective diameter of the curved surface or a point intersecting the outer peripheral portion.) This condition is shown in FIG. 1 (Example 1 of the present invention). As shown in FIG. 1, when the joining surface is considered as being divided into a concave surface and a convex surface of the element, it is important that they come into contact at the outer peripheral portion (hereinafter referred to as marginal contacts).

Therefore, when the concave surface L1R side is an aspheric surface,
When comparing the radius of curvature RN of the concave-side reference spherical surface with the radius of curvature RP of the convex-side spherical surface (broadly defined as a reference spherical surface),
The condition for the marginal contact is that the radius of curvature RP on the convex side needs to be smaller.

In the first embodiment shown in FIG. 1, since the concave surface L1R side is aspherical and is in marginal contact, the reference spherical surface is defined as a surface including the optical axis La and the marginal contact point (line).

As shown in FIG. 2, when the refractive index of the material of the element having a convex surface is high as shown in FIG. 2, since the convex surface L2R is made aspheric, the spherical surface on the concave L1R side and the convex surface are formed. Comparing the radii of curvature of the reference spheres indicates that the radius of curvature RP of the reference sphere on the convex side also needs to be large.

In FIG. 2, the convex side is an aspherical surface. In this case, the reference spherical surface may be defined by a marginal contact point (line) or by an outer peripheral portion.

When the conditional expression (1) exceeds the upper limit, it means that the joint is not marginally contacted.

When | RN / RP |> 1.0, the center contact (hereinafter referred to as “medium hit”) occurs, which is not preferable because the center of the lens and the like are damaged during the joining process.
When /RP|=1.0, the contact is full (full contact), which is not a problem in theory. However, even if it is a full contact by design, there is still a danger that the contact will be near due to tolerances during surface processing. Not preferred.

| RN / RP | = 0 indicates that the non-aspheric surface is a plane (RP = ∞).

(A-2) The difference between the Abbe numbers at the d-line of the material of both elements (positive lens and negative lens) of the cemented lens is Δ
When νd, Δνd> 10 ＞ (2) is satisfied.

If conditional expression (2) is satisfied, it becomes easy to perform more effective achromatism on the joint surface.

(A-3) When the refractive index NH of the material of the element (lens) of the cemented lens having the higher refractive index is 1.6 or more, a non-dielectric film is deposited on the surface of the element. Is good. When the refractive index of the non-dielectric film at this time is N, it is preferable to satisfy 1.6 <N <NH ‥‥‥ (3).

When the refractive index difference between the two elements in the cemented lens becomes too large, the influence of the reflection on the cemented surface on the loss of the light amount and the ghost cannot be ignored.
The adhesive used for ordinary bonding has a refractive index of 1.52 to 1.
Since it is about 56, which is close to the refractive index of the lower material of the cemented lens, the reflection on that surface is negligibly small.

Therefore, it is sufficient to consider the surface reflection at the joint surface having the higher refractive index. For this purpose, when the refractive index (NH) of the material of the element having the higher refractive index is 1.6 or more, a non-dielectric film satisfying the conditional expression (3) is deposited on the element. This is preferable because the reflectance at the bonding surface can be kept low (N is the refractive index of the non-dielectric film).

FIG. 3 is an explanatory diagram of the technical contents of the conditional expression (3). In FIG. 3, the same elements as those shown in FIG. 1 are denoted by the same reference numerals. FIG. 3 illustrates a joining state when the concave surface is made aspherical. In this case, the element L1 having the higher refractive index is on the concave surface side. Therefore, N
When H> 1.6, a non-dielectric film (NH>N> 1.6) having a refractive index N is disposed on the concave surface side.

This non-dielectric film may be any film as long as the refractive index satisfies conditional expression (3). However, when compatibility with the adhesive CM and durability are taken into consideration, Al (aluminum)
It is highly preferred to include an oxide of Further, the non-dielectric film of the present embodiment may be formed by vapor deposition, ion sputtering, or the like, or may be formed by spin coating or the like.

Further, in this case, if the material of the element L2 having a lower refractive index has a refractive index of 1.6 or less, the antireflection by the non-dielectric film is very effective, but the refractive index is lower. A value of 1.6 or more does not impair the purpose.

Next, a specific configuration of an optical system using the cemented lens of the present invention will be described. 4 and 6 are lens cross-sectional views of Numerical Examples 1 and 2 of an optical system using the cemented lens of the present invention. FIG. 5 is an aberration diagram of Numerical Embodiment 1 of the present invention,
FIGS. 7, 8, and 9 are aberration diagrams at the wide-angle end, at the middle, and at the telephoto end according to Numerical Embodiment 2 of the present invention.

The optical system shown in FIG. 4 shows a case where the present invention is applied to a so-called Gaussian lens, and the optical system shown in FIG. 6 shows a case where the present invention is applied to a five-group type zoom lens.

FIGS. 6A, 6B, and 6C show zoom positions at the wide-angle end, the middle position, and the telephoto end, and arrows show the movement trajectories of the respective lens groups accompanying zooming from the wide-angle end to the telephoto end. Is shown.
In the figure, SP denotes an aperture, and IP denotes an image plane.

In the lens sectional view and numerical examples, Li,
Ri, Di, Ni, and νi are, in order from the object side, the radius of curvature of the i-th lens surface, lens thickness, adhesive, or air space;
Refers to the refractive index and Abbe number.

In Numerical Embodiment 2, R29 to R32 denote a low-pass filter such as quartz or a prism for three-color separation. However, the stop SP is counted as one surface.
The aspherical shape has an X axis in the optical axis direction and an H axis in a direction perpendicular to the optical axis.
Axis and the traveling direction of light are positive, R is the paraxial radius of curvature, B,
When C, D, E, and F are each aspheric coefficients,

[0062]

(Equation 1)

This is represented by the following equation.

Numerical Example 1 f = 100 Fno = 1: 4.0 2ω = 43.8 ° R 1 = 62.28 D 1 = 8.11 N 1 = 1.71805 ν 1 = 53.8 R 2 = 234.88 D 2 = 0.68 R 3 = 34.30 D 3 = 6.67 N 2 = 1.75034 ν 2 = 44.8 R 4 = 56.09 D 4 = 1.80 R 5 = 63.23 D 5 = 3.09 N 3 = 1.70780 ν 3 = 30.1 R 6 = 24.16 D 6 = 12.90 R 7 = Aperture D 7 = 18.61 R 8 = -29.67 D 8 = 3.09 N 4 = 1.77252 ν 4 = 27.7 R 9 = -112.70 D 9 = 0.051 N 5 = 1.56000 ν 6 = 55.0 R10 = -112.70 D 9 = 10.36 N 6 = 1.81059 ν 6 = 46.6 R11 = -36.96 D10 = 0.41 R12 = 1342.79 D11 = 7.29 N 7 = 1.81059 ν 7 = 46.6 R13 = -96.45 D12 = 64.132 Aspheric coefficient R10 k = 7.41218e-01 B = 0.00 C = -2.11074e-11 D = 3.04682 e-12 E = -1.14390e-14 In Numerical Example 1 of FIG. 4, the surface R9 and the surface R10 form a joint surface, and the element R5 of the material L5 having a higher refractive index is aspheric. The reference spherical radii of the surface R9 and the surface R10 are as follows: R9 (RP): -112.70 R10 (RN): -109.797 (at φ40.0 mm), and have a marginal contact of φ40.0 mm. (RN / RP = 0.974) Therefore, the adhesive has a center thickness of 0.051 mm.
In Numerical Example 1, it is effective to prevent reflection if a non-dielectric film (not shown) of about N = 1.65 is deposited on the surface R10, which is the element L5 having the higher refractive index, by vapor deposition or the like.

In this embodiment, the refractive index N and the Abbe number ν are λ
= Constant at 0.525 μm. Numerical Example 2 f = 6.09 ~ 100 Fno = 1.64 ~ 2.24 2ω = 52.4 ° ~ 3.4 ° R 1 = 101.272 D 1 = 2.145 N 1 = 1.84666 ν 1 = 23.8 R 2 = 47.552 D 2 = 0.0023 N 2 = 1.56000 ν 2 = 55.0 R 3 = 47.563 D 3 = 8.565 N 3 = 1.60311 ν 3 = 60.7 R 4 = -567.090 D 4 = 0.220 R 5 = 41.667 D 5 = 4.832 N 4 = 1.77250 ν 4 = 49.6 R 6 = 100.614 D 6 = Variable R 7 = 59.489 D 7 = 0.988 N 5 = 1.69680 ν 5 = 55.5 R 8 = 9.246 D 8 = 4.893 R 9 = -27.107 D 9 = 0.988 N 6 = 1.69680 ν 6 = 55.5 R10 = 43.307 D10 = 1.318 R11 = 21.415 D11 = 2.301 N 7 = 1.84666 ν 7 = 23.8 R12 = 55.722 D12 = Variable R13 = -21.109 D13 = 0.769 N 8 = 1.77250 ν 8 = 49.6 R14 = 36.596 D14 = 2.196 N 9 = 1.84666 ν 9 = 23.8 R15 = -450.217 D15 = variable R16 = -2887.585 D16 = 4.392 N10 = 1.58313 ν10 = 59.4 R17 = -16.967 D17 = 1.647 R18 = Aperture D18 = 2.196 R19 = 35.046 D19 = 4.392 N11 = 1.60311 ν11 = 60.7 R20 = -27.518 D20 = 0.988 N12 = 1.83481 ν12 = 42.7 R21 = 134.301 D21 = Variable R22 = 119.682 D22 = 3.843 N13 = 1.58313 ν13 = 59.4 R23 = -31.305 D23 = 0.165 R24 = 1099.776 D24 = 1.098 N14 = 1.80518 ν14 = 25.4 R25 = 22.341 D25 = 3.843 N15 = 1.48749 ν15 = 7 0.2 R26 = -155.425 D26 = 0.165 R27 = 32.691 D27 = 2.745 N16 = 1.58144 ν16 = 40.8 R28 = -165.337 D28 = Variable R29 = ∞ D29 = 1.515 N17 = 1.55000 ν17 = 60.0 R30 = ∞ D30 = 22.0 N18 = 1.58913 ν18 = 61.2 R31 = ∞ D31 = 2.6 N19 = 1.52000 ν19 = 64.0 R32 = ∞ ＼ Focal length 6.1 25.4 100.0 Variable spacing＼ D 6 1.263 31.285 44.151 D12 46.084 12.314 2.821 D15 2.016 5.764 2.390 D21 18.101 18.329 21.550 D28 9.081 8.853 5.632 Aspheric coefficient R 2 k = 7.89557e-02 B = -1.17576e-07 C = 3.16696e-10 D = -6.00136e-13 E = 0.0 R16 k = 9.14906e + 04 B = -3.02233e-05 C = 2.43513e-08 D = -1.80364e-12 E = 0.0 In the numerical example 2 of FIG. 6, a cemented lens is applied to the first group of the zoom lens. The zoom lens includes a first lens unit LL1 and a fourth lens unit LL4 fixed during zooming, a second lens unit LL2 having a zooming action, and a third lens unit LL for correcting an image plane variation due to zooming.
3, the fifth lens group LL5. The zoom lens has an Fno / 1.6 and a zoom ratio of about 16 times.

In the second embodiment, in order to correct higher-order chromatic aberration at the Tele end, the joining surface of the surfaces R2 and R3 is
An aspherical surface is introduced into a surface R2 of a material having a high refractive index, and the surface R3 is joined as a spherical surface.

The reference spherical radii of the surfaces R2 and R3 are as follows: R2 (RP): 47.548 (at φ46.0 mm) R3 (RN): 47.563, and a marginal contact is made at φ46.0 mm. (RN / RP = 0.9997) Therefore, the center thickness of the adhesive is 0.0023 mm. Also in Numerical Example 2, a non-dielectric film of about N = 1.65 on the surface R2 which is the element having the higher refractive index (not shown)
It is effective to prevent reflection by attaching it by vapor deposition or the like.

In this embodiment, the refractive index N and the Abbe number ν are d
It is a constant in the line.

It should be noted that the cemented lens of the present invention is not limited to Numerical Embodiments 1 and 2, but can be similarly applied to any optical system such as a photographing lens, a zoom lens, and a finder system.

[0070]

According to the present invention, as described above, by appropriately setting the surface shape of the joining surface when the joining surface is made aspherical, it is easy to manufacture and a high aspherical effect can be obtained. In addition, it is possible to achieve a cemented lens and an optical system using the same, which easily provide high optical performance.

In addition, according to the present invention, when a cemented lens having an aspherical cemented surface is formed as described above, it is possible to achieve a cemented lens having an aspherical amount managed to the same degree as high-precision processing. Optical system with high-level aberration correction and camera system (optical equipment) using them
Can be achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a first embodiment of a cemented lens according to the present invention;

FIG. 2 is a sectional view of a principal part of a cemented lens according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a principal part of a third embodiment of the cemented lens according to the present invention;

FIG. 4 is a lens cross-sectional view of Numerical Example 1 of an optical system using a cemented lens of the present invention.

FIG. 5 is an aberration diagram of a numerical example 1 of the optical system using the cemented lens of the present invention.

FIG. 6 is a lens sectional view of a numerical example 2 of an optical system using the cemented lens of the present invention.

FIG. 7 is an aberration diagram at a wide angle end of Numerical Example 2 of the optical system using the cemented lens of the present invention.

FIG. 8 is an intermediate aberration diagram of Numerical Example 2 of the optical system using the cemented lens of the present invention.

FIG. 9 is an aberration diagram at a telephoto end of Numerical Example 2 of the optical system using the cemented lens of the present invention;

[Explanation of symbols]

 Li i-th lens LLi i-th lens group d d-line gg-line c c-line ff line ΔM Meridional image plane ΔS Sagittal image plane

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2H087 KA02 KA03 KA08 KA12 KA14 KA19 LA06 PA05 PA11 PA16 PA18 PB07 PB15 PB16 QA02 QA07 QA12 QA17 QA21 QA25 QA26 QA34 QA41 QA46 RA05 RA12 RA13 SA32 SA43 SA47SA47 SA72 SA75 SB04 SB05 SB14 SB23 SB34 SB45

Claims (9)

[Claims] 1. A cemented lens in which two or more elements having different refractive indices of a material are joined to each other, a joining surface of an element having a higher refractive index of a material among the two joined elements is non-contact. A cemented lens having a spherical surface and a cemented surface of an element having a lower refractive index is a spherical surface. 2. In a cemented lens in which two or more elements having different refractive indices of a material are joined to each other, a joining surface of an element having a higher refractive index of a material among the two joined elements is non-contact. A cemented lens having a spherical surface and a cemented surface of an element having a lower refractive index is a flat surface. 3. When the reference spherical surface radius of one of the connecting surfaces of the two joined elements is RN, and the reference spherical surface radius of the other surface is RP, 0 ≦ | RN / RP | <1. 3. The method according to claim 1, wherein the reference spherical radius satisfies 0 (however, the radius of the reference spherical surface is an effective diameter of the curved surface or a radius of a circle connecting the point of intersection with the outer peripheral portion). Cemented lens. 4. The joint surface of the two elements joined together is a joint of a concave surface and a convex surface, one of which has a reference spherical surface radius of the concave surface of the element, and the other has a reference spherical surface radius of the convex surface of the other element. 0 <| RN / RP | <1.0 (where the reference spherical radius is the effective diameter of the curved surface or the radius of the circle connecting the point intersecting the outer peripheral portion) 2. The cemented lens according to claim 1, wherein: 5. The cemented lens according to claim 1, wherein Δν> 10, where Δν is a difference between Abbe numbers of the materials of the two elements joined together. 6. The refractive index (N) of the element having the higher refractive index of the material among the two joined elements.
When H) is 1.6 or more, a non-dielectric film having a refractive index of N and satisfying a condition of 1.6 <N <NH is deposited on the element. The cemented lens according to any one of the above items. 7. The cemented lens according to claim 1, wherein the two cemented elements are a positive lens and a negative lens. 8. An optical system comprising the cemented lens according to claim 1. Description: 9. An optical apparatus comprising the optical system according to claim 8.