JP7418096B2 - Optical elements, optical instruments and imaging devices - Google Patents

Description

The present invention relates to an optical element including a plurality of optical elements, an optical device having the same, and an imaging device.

Optical elements consisting of a plurality of optical elements are used as lenses in optical systems such as digital cameras and video cameras, and are required to be small and have high optical performance. In such optical elements, by using a combination of different materials, performance that cannot be achieved with a single material can be obtained. For example, as an optical element that reduces chromatic aberration, Patent Document 1 proposes an optical element that includes a plurality of optical elements such as resin and glass.

Optical elements that combine optical elements made of different materials have the problem of being easily deformed and prone to cracks and fissures due to low adhesion between the materials and differences in properties due to temperature changes. In order to solve this problem, Patent Document 2 proposes an optical element that suppresses the generation of stress due to expansion and contraction deformation due to temperature and humidity.

JP2011-102906A Japanese Patent Application Publication No. 2010-266496

However, in the case of optical elements using optical elements with greatly different linear expansion coefficients, even if the linear expansion coefficients of the optical elements to be sandwiched are made the same as specified in Patent Document 2, deformation of the optical element or the gap between the optical elements may occur. Peeling easily occurs at the interface.

In order to solve this problem of peeling at the interface, it is known that, for example, after molding a thermosetting or photocuring resin material into an optical element, it is attached to another optical element with an adhesive layer formed with an adhesive to suppress deformation. It is being An adhesive layer whose elastic modulus becomes significantly lower when heated to high temperatures can effectively prevent peeling at the interface between two different optical elements. However, in an optical element using such an adhesive layer, when the temperature is raised to high temperature and then returned to the original temperature, the change in surface shape becomes large and the optical performance may deteriorate.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical element that exhibits little change in surface shape before and after heating while preventing peeling of optical elements made of different materials.

The optical element of the present invention is an optical element having a first optical element and a third optical element made of glass or plastic, and a second optical element made of optical resin, wherein the first optical element and the opposing surface of the second optical element and/or the opposing surface of the second optical element and the third optical element are joined with an adhesive resin layer, and the first optical element is The third optical element has a convex shape on the surface facing the second optical element, and the third optical element has a concave shape on the surface facing the second optical element, and the indentation modulus of the adhesive resin layer at 20° C. When Ead1 is the indentation modulus at 60°C and Ead2 is the indentation modulus at 60°C, the following formula (1) is satisfied: 0.2≦Ead2/Ead1≦0.5 (1)
When the coefficients of linear expansion from 20°C to 60°C of the first optical element and the third optical element are α1 and α3, respectively, the following formula (2) is satisfied: 0.25≦α1/α3<1.0 (2)
It is characterized by

According to the present invention, it is possible to provide an optical element in which peeling of different optical elements is prevented and the surface shape changes less when the temperature is returned to room temperature after being heated to a high temperature.

FIG. 2 is a cross-sectional view of the optical element of this embodiment. It is a figure showing the manufacturing method of the optical element of this embodiment. 3 is a cross-sectional view of an optical element of Example 2. FIG. FIG. 3 is a cross-sectional view of an optical element of Example 3. FIG. 6 is a cross-sectional view of an optical element of Example 6. FIG. 1 is a diagram showing an imaging device according to the present embodiment.

Embodiments of the present invention will be described below.

(optical element)
As shown in FIG. 1, an optical element according to an embodiment of the present invention is composed of at least three optical elements. The optical element 10 includes at least a first optical element 11, a second optical element 12, and a third optical element 13. The facing surfaces of the first optical element 11 and the second optical element 12 and/or the facing surfaces of the second optical element 12 and the third optical element 13 are bonded with an adhesive layer 14 formed from an adhesive. has been done. An example will be described below in which the second optical element 12 and the third optical element 13 are bonded with an adhesive layer 14.

The first optical element 11 has a convex surface facing the second optical element 12. For example, glass or plastic can be used as the first optical element 11. It is preferable to use glass for the first optical element 11 from the viewpoint of small volume change due to temperature change. The linear expansion coefficient of the first optical element is preferably 30×10 ⁻⁷ /°C or more and 81×10 ⁻⁷ /°C or less.

The second optical element may have a maximum thickness t2c in the direction of the optical axis L of 0.3 mm or more and 10 mm or less. The maximum thickness t2c is preferably 0.3 mm or more and 2.0 mm or less. The optical axis L passes through the center of the optical element 10 when the optical element 10 is viewed from the light incident direction. Therefore, the maximum thickness t2c can be expressed as the thickness in the normal direction starting from the center of the first optical element 11 or the third optical element 13. As the second optical element 12, for example, an organic material such as resin can be used. The resin used for the second optical element 12 has, for example, a d-line refractive index nd of 1.60 or more and 1.67 or less, an Abbe number νd of 16.7 or more and 21.5 or less, and a partial dispersion ratio θgF of 0. A value of 70 or more and 0.76 or less can be used. By using such a material with a high θgF, it is possible to design an optical system that efficiently reduces chromatic aberration of short wavelength light in visible light.

As the resin used for such a second optical element 12, for example, a resin obtained by polymerizing or copolymerizing a compound represented by the following general formula (1) having an acryloyl group or a methacryloyl group can be used.

[In formula (1), X and Y are each a substituent selected from the substituents shown below.

（＊は、Ｒ_１又はＲ_２との結合手を表す。）
Ｒ_１及びＲ_２は、それぞれ水素原子、炭素数１乃至２のアルキル基及び（メタ）アクリロイル基から選択されるいずれかの置換基である。Ｚ_１及びＺ_２は、それぞれ水素原子、ハロゲン原子、炭素数１乃至２のアルコキシ基、炭素数１乃至２のアルキルチオ基、無置換の炭素数１乃至２のアルキル基及び下記式（３）に示す置換基から選択されるいずれかの置換基である。

(* represents the bond with R ₁ or R _2. )
R ₁ and R ₂ are each a substituent selected from a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, and a (meth)acryloyl group. Z ₁ and Z ₂ are each a hydrogen atom, a halogen atom, an alkoxy group having 1 to 2 carbon atoms, an alkylthio group having 1 to 2 carbon atoms, an unsubstituted alkyl group having 1 to 2 carbon atoms, and the following formula (3). Any substituent selected from the substituents shown.

（式（３）において、＊＊は、結合手を表し、ｍは０又は１であり、ｎは２乃至４のいずれかの整数であり、Ｒは水素又はメチル基である。）
ａ及びｂは、それぞれ０乃至２のいずれかの整数である。ａが２のとき２つのＺ_１は、同じであってもよいし異なっていてもよい。ｂが２のとき２つのＺ_２は、同じであってもよいし異なっていてもよい。〕

(In formula (3), ** represents a bond, m is 0 or 1, n is an integer of 2 to 4, and R is hydrogen or a methyl group.)
a and b are each an integer from 0 to 2. When a is 2, the two Z ₁ 's may be the same or different. When b is 2, the two Z ₂ 's may be the same or different. ]

The third optical element 13 has a concave shape on its surface facing the second optical element. As the third optical element 13, for example, glass or plastic can be used. It is preferable to use glass as the third optical element 13 from the viewpoint of small volume change due to temperature change. The linear expansion coefficient of the third optical element 13 is preferably 66×10 ⁻⁷ /°C or more and 136×10 ⁻⁷ /°C or less.

The adhesive forming the adhesive layer 14 may be, for example, an acrylic photocurable resin, an epoxy cured resin, or the like. Among these, it is preferable to use acrylic photocurable resins because they have excellent moldability. The adhesive layer 14 satisfies the following formula (1), where the elastic modulus at 20° C. is Ead1 and the elastic modulus at 60° C. is Ead2.
0.2≦Ead2/Ead1≦0.5 (1)

If 0.2>Ead2/Ead1, the elastic modulus of the adhesive layer 14 becomes too low at high temperatures, and peeling occurs at the optical element interface. Furthermore, if Ead2/Ead1>0.5, the adhesive layer will not be elastically deformed easily when the temperature is high, and peeling will occur at the interface of the optical element.

The adhesive layer 14 that satisfies formula (1) of this embodiment has a lower elastic modulus at 60° C. than that at 20° C., and is easily deformed at high temperatures. Therefore, in the optical element 10 in which a plurality of optical elements having large differences in linear expansion coefficients are bonded together, peeling of the optical elements that occurs when the temperature is raised can be suppressed. Further, the thickness of the adhesive layer 14 is not particularly limited, but is, for example, 10 μm or more and 30 μm or less.

The optical element 10 using an adhesive layer that is easily deformed by heat at high temperatures that satisfies formula (1) is said to change the shape of the adhesive layer and deteriorate its optical performance when the temperature is returned to the original temperature after being raised to a high temperature. The inventor discovered a problem. This is because when the adhesive layer is heated to a high temperature and then returned to its original temperature, the adhesive layer deforms so that the curvature becomes smaller (the radius of curvature becomes larger) with respect to its original shape.

The optical element 10 of this embodiment satisfies the following formula (2) when the linear expansion coefficients of the first optical element 11 and the third optical element 13 from 20° C. to 60° C. are α1 and α3, respectively.
0.25≦α1/α3<1.0 (2)

In the optical element 10 of this embodiment, when formula (2) is satisfied, the third optical element 13 acts to increase the curvature of the adhesive layer 14. It is believed that it is possible to suppress the change in the shape of the adhesive layer 14 and prevent the optical performance from deteriorating.

When the optical element 10 satisfies 0.25>α1/α3, the linear expansion coefficients of the first optical element 11 and the third optical element 13 are significantly different, so that the shape change when the adhesive layer 14 is heated to a high temperature is Even if the temperature is returned to the original temperature, the shape change remains and the optical performance deteriorates. In the case of α1/α3≧1.0, when the adhesive layer 14 is heated to a high temperature and then returned to its original temperature, the restoring force that restores the shape change of the adhesive layer 14 is small. When returned, the surface shape changes greatly.

The linear expansion coefficients of the first optical element 11, the second optical element 12, and the third optical element 13 from 20°C to 60°C are α1, α2, and α3, respectively. The optical element 10 of this embodiment can suppress peeling at the optical element interface when the following formula (3) and the following formula (4) are satisfied.
9.0≦α2/α1≦24.5 (3)
5.0≦α2/α3≦11.0 (4)

Further, when the maximum thickness in the optical axis L direction of the second optical element 12 is t2c, and the outer diameter thickness is t2e, if the following formula (5) is satisfied, based on the shape change of the adhesive layer 14, This is preferable because it increases the restoring force.
0.005≦t2e/t2c<0.95 (5)

Moreover, it is more preferable that t2e/t2c satisfy the following formula (6).
0.005≦t2e/t2c≦0.05 (6)

(optical equipment)
FIG. 6 shows the configuration of a single-lens reflex digital camera, which is an example of a preferred embodiment of the imaging device of the present invention. In FIG. 6, a camera body 602 and a lens barrel 601, which is an optical device, are combined, but the lens barrel 601 is a so-called interchangeable lens that can be attached to and detached from the camera body 602.

Light from an object is photographed by passing through an optical system including a plurality of lenses 603, 605, etc. arranged on the optical axis of the photographing optical system within the housing of the lens barrel 601. The optical element of the present invention can be used for lenses 603 and 605, for example.

Here, the lens 605 is supported by an inner tube 604 and movably supported relative to the outer tube of the lens barrel 601 for focusing and zooming.

During the observation period before photographing, light from the subject is reflected by the main mirror 607 in the housing 621 of the camera body, passes through the prism 611, and then the photographed image is projected to the photographer through the finder lens 612. The main mirror 607 is, for example, a half mirror, and the light transmitted through the main mirror is reflected by a submirror 608 in the direction of an AF (autofocus) unit 613, and this reflected light is used, for example, for distance measurement. Further, the main mirror 607 is mounted and supported by a main mirror holder 640 by adhesive or the like. During photographing, the main mirror 607 and the sub-mirror 608 are moved out of the optical path through a drive mechanism (not shown), the shutter 609 is opened, and the photographing light image incident from the lens barrel 601 is received (imaged) on the image sensor 610. . Further, the diaphragm 606 is configured so that brightness and depth of focus during photographing can be changed by changing the aperture area.

(Manufacturing method of optical element)
A method for manufacturing an optical element according to this embodiment will be described with reference to the drawings.

First, as shown in FIG. 2A, uncured ultraviolet curable resin 12a is filled between the glass that is the first optical element 11 and the mold 15.

Next, as shown in FIG. 2(b), the uncured ultraviolet curable resin 12a is irradiated with ultraviolet rays from the first optical element 11 side, and a second optical An ultraviolet curing resin as element 12 is provided.

As shown in FIG. 2(c), an adhesive 14a containing an ultraviolet curable resin is applied to the side of the second optical element 12 that is not in contact with the first optical element 11 using a dispenser (not shown) or the like. work.

As shown in FIG. 2(d), the ultraviolet curing resin of the second optical element 12 and the glass of the concave third optical element 13 are bonded with an adhesive 14a. Then, the adhesive 14a is irradiated with ultraviolet rays from the third optical element 13 side to form the adhesive layer 14, thereby obtaining the optical element 10.

In the method for manufacturing an optical element, the order of molding and joining the optical elements may be changed, and the second optical element 12 is molded on the concave third optical element 13, and then the first optical element It may also be created by joining the elements 11.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the Examples described below unless it exceeds the gist thereof.

In Examples and Comparative Examples, measurements and evaluations were made using the following methods.

(thermal durability)
In evaluating the thermal durability of the optical element, first, the temperature of the optical element was raised from 20°C to 60°C over 40 minutes, held at 60°C for 10 minutes, and then cooled at room temperature of 20°C. Next, one hour after the start of cooling, it was confirmed that the temperature of the optical element was 25° C. or lower. Then, the surface shapes of the first optical element 11 and the third optical element 13 were measured using a laser interferometer GPI (manufactured by ZYGO), and the changes in the surface shapes were converted into Newton's rings and determined. When the design value of the surface shape of the optical element is a spherical surface R, a change in the direction in which R becomes smaller is considered as a positive value, and a case in which R changes in the direction in which it becomes larger is considered as a negative value. Thermal durability was evaluated based on the following criteria.

A: The change in the Newton rings of the first optical element 11 and the third optical element 13 is within ±3 lines, and the total Newton ring change of the first optical element 11 and the third optical element 13 is within ±3 lines. is within 4 and has high thermal durability.

B: The change in the Newton rings of the first optical element 11 or the third optical element 13 exceeds ±3, or the change in the Newton rings of the first optical element 11 and the third optical element 13 in total exceeds 4, and there is room for improvement in thermal durability.

(Modulus of elasticity)
The elastic modulus of the ultraviolet curing resin, adhesive layer, etc. was measured using a measurement sample prepared by cutting an optical element. Specifically, the elastic modulus was measured using Nanoindenter G200 (manufactured by Keysight Technologies). In order to measure the temperature dependence of the elastic modulus, the elastic modulus was measured at every 10° C. using a heating stage set to raise the temperature from 20° C. to 60° C. by 2° C. per minute.

(linear expansion coefficient)
The linear expansion coefficients of the ultraviolet curable resin, adhesive layer, etc. were measured using a measurement sample prepared by cutting the optical element using a thermomechanical analyzer using the TMA method. Specifically, the expansion and contraction of the measurement sample was measured when the temperature was changed while a constant load was applied. The temperature was raised from 20°C to 80°C over 10 minutes, held at 80°C for 10 minutes, and then lowered from 80°C to 20°C over 10 minutes. Normally, the first measurement value tends to reflect large errors, so after measuring 3 cycles of increasing and decreasing the temperature, calculate the average value from the data of 2 times excluding the first time, and calculate the coefficient of linear expansion. did.

(Peeling)
After creating the optical element, a peeling test was conducted by heating it in an oven at a high temperature. Specifically, the created optical element was placed in an oven, heated from 20°C to 60°C over 4 hours, held at 60°C for 1 hour, and then lowered from 60°C to 20°C over 4 hours. did. Peeling was confirmed by microscopic observation of the samples 1 hour after the temperature was lowered to confirm the presence or absence of peeling. As a result of microscopic observation, those in which no peeling was observed were rated A. An optical element with a rating of A means that it was an optical element with high durability. Further, as a result of microscopic observation, one or more peelings were observed as B. An optical element rated B means that there is room for improvement in durability.

(Example 1)
In Example 1, an optical element having the shape shown in FIG. 1 was manufactured.

Between the optical glass of the first optical element 11 (elastic modulus 118 GPa at 20°C, linear expansion coefficient 62×10 ^-7 /°C from 20°C to 60°C) and the mold 15, an uncured acrylic UV-curable resin is 12a was applied. Ultraviolet rays were irradiated from the first optical element 11 side using a high-pressure mercury lamp (EXECURE 250, manufactured by HOYA CANDEO OPTRONICS Co., Ltd.) to cure the acrylic UV-curable resin. The ultraviolet irradiation conditions were 25 mW/cm ² and 200 seconds. In this way, the acrylic UV curing resin of the second optical element 12 (modulus of elasticity at 20°C 2.6 GPa, coefficient of linear expansion 728×10 ^-7 /°C) is placed on the glass of the first optical element 11. has been established. The thickness of the second optical element 12 in the optical axis direction was 1 mm, and the thickness of the outer periphery was 0.05 mm.

Thereafter, the adhesive 14a was applied to the surface of the second optical element 12 that was not in contact with the first optical element 11, and the second optical element 12 and the third optical element 13 were joined. The adhesive 14a was made of an acrylic UV curing resin, and the ultraviolet irradiation conditions were 10 mW/cm ² and 100 seconds. The adhesive layer 14 cured in this manner has an elastic modulus of 0.65 GPa at 20°C, and a modulus of elasticity of 0.23 GPa at 60°C, and the elastic modulus at 20°C is the same as the elastic modulus at 60°C. The ratio was 0.35. Further, the thickness of the adhesive layer 14 was 20 μm. For the third optical element 13, optical glass (modulus of elasticity at 20° C. is 90 GPa, coefficient of linear expansion from 20° C. to 60° C. is 66×10 ⁻⁷ /° C.) was used.

The configuration and evaluation results of the optical element of Example 1 are summarized in Table 1.

(Comparative example 1)
In Comparative Example 1, an optical element was manufactured in the same manner as in Example 1, except that the first optical element 11 and the third optical element 13 were replaced with those shown in Table 1. Specifically, both the first optical element 11 and the third optical element 13 are made of optical glass having an elastic modulus of 118 GPa at 20° C. and a linear expansion coefficient of 69×10 ⁻⁷ /° C. from 20° C. to 60° C. Using.

The configuration and evaluation results of the optical element of Comparative Example 1 are summarized in Table 1.

(Example 2)
In Example 2, an optical element having the shape shown in FIG. 3 was manufactured.

In Example 2, the first optical element 21 was made of optical glass having an elastic modulus of 82 GPa at 20°C and a coefficient of linear expansion from 20°C to 60°C of 30×10 ⁻⁷ /°C. The second optical element 22 was made of an acrylic UV-curable resin having an elastic modulus of 2.6 GPa at 20° C. and a linear expansion coefficient of 728×10 ⁻⁷ /° C. from 20° C. to 60° C. The second optical element 22 was molded on the first optical element 21, and its maximum thickness in the optical axis direction was 1 mm, and the outer circumferential thickness was 0.03 mm.

For the third optical element 23, optical glass having an elastic modulus of 76 GPa and a linear expansion coefficient of 117×10 ⁻⁷ /° C. was used. An optical element was manufactured in the same manner as in Example 1 except for these changes.

The configuration and evaluation results of the optical element of Example 2 are summarized in Table 1.

(Comparative example 2)
In Comparative Example 2, an optical element having the shape shown in FIG. 3 was manufactured.

The first optical element 21 was made of optical glass having an elastic modulus of 82 GPa at 20° C. and a linear expansion coefficient of 30×10 ⁻⁷ /° C. from 20° C. to 60° C. For the second optical element 22, an acrylic UV-curable resin having an elastic modulus of 2.6 GPa at 20° C. and a linear expansion coefficient of 728×10 ⁻⁷ /° C. from 20° C. to 60° C. was used. The second optical element 22 was molded on the first optical element 21, and its maximum thickness in the optical axis direction was 1 mm, and the outer circumferential thickness was 0.03 mm. The third optical element 23 was made of optical glass having an elastic modulus of 70 GPa at 20° C. and a linear expansion coefficient of 145×10 ⁻⁷ /° C. from 20° C. to 60° C. An optical element was manufactured in the same manner as in Example 1 except for these changes.

The configuration and evaluation results of the optical element of Comparative Example 2 are summarized in Table 1.

(Example 3)
In Example 3, an optical element having the shape shown in FIG. 4 was manufactured.

In Example 3, the first optical element 31 was made of optical glass having an elastic modulus of 80 GPa at 20° C. and a linear expansion coefficient of 72×10 ⁻⁷ /° C. from 20° C. to 60° C. The second optical element 32 was made of an acrylic UV-curable resin having an elastic modulus of 2.6 GPa at 20°C and a linear expansion coefficient of 728×10 ⁻⁷ /°C from 20°C to 60°C. The second optical element 32 was molded on the first optical element 31, and its maximum thickness in the optical axis direction was 1 mm, and the outer circumferential thickness was 0.01 mm.

The third optical element 33 was made of optical glass having an elastic modulus of 76 GPa at 20°C and a coefficient of linear expansion from 20°C to 60°C of 117×10 ⁻⁷ /°C. The elastic modulus of the adhesive layer 34 at 20° C. is 1.87 GPa, the elastic modulus at 60° C. is 0.63 GPa, and the ratio of the elastic modulus at 20° C. to the elastic modulus at 60° C. is 0.34. there were. Further, the thickness of the adhesive layer 34 was 20 μm. An optical element was manufactured in the same manner as in Example 1 except for these materials and configurations.

The configuration and evaluation results of the optical element of Example 3 are summarized in Table 1.

(Example 4)
In Example 4, an optical element having the shape shown in FIG. 1 was manufactured. In Example 4, the first optical element 11 was made of optical glass having an elastic modulus of 78 GPa at 20°C and a linear expansion coefficient of 81×10 ^-7 /°C from 20°C to 60°C. The second optical element 12 was made of an acrylic UV curable resin having an elastic modulus of 2.6 GPa at 20°C and a linear expansion coefficient of 728×10 ⁻⁷ /°C from 20°C to 60°C. The second optical element 12 was molded on the first optical element 11, and its maximum thickness in the optical axis direction was 1 mm, and the outer circumferential thickness was 0.05 mm. The third optical element 13 was made of optical glass having an elastic modulus of 70 GPa at 20° C. and a linear expansion coefficient of 136×10 ⁻⁷ /° C. from 20° C. to 60° C. The elastic modulus of the adhesive layer 14 at 20° C. was 0.31 GPa, the elastic modulus at 60° C. was 0.15 GPa, and the ratio of the elastic modulus at 20° C. to the elastic modulus at 60° C. was 0.48. . Further, the thickness of the adhesive layer 14 was 20 μm. An optical element was manufactured in the same manner as in Example 1 except for these materials and configurations.

The configuration and evaluation results of the optical element of Example 4 are summarized in Table 1.

(Example 5)
In Example 5, an optical element having the shape shown in FIG. 1 was manufactured. In Example 5, the first optical element 11 was made of optical glass having an elastic modulus of 80 GPa at 20° C. and a linear expansion coefficient of 72×10 ⁻⁷ /° C. from 20° C. to 60° C. The second optical element 12 was made of an acrylic UV-curable resin having an elastic modulus of 2.6 GPa at 20°C and a linear expansion coefficient of 728×10 ⁻⁷ /°C from 20°C to 60°C. The second optical element 12 was molded on the optical element 11, and its maximum thickness in the optical axis direction was 1 mm, and the outer circumferential thickness was 0.05 mm.

The third optical element 13 was made of optical glass having an elastic modulus of 76 GPa at 20°C and a linear expansion coefficient of 117×10 ^-7 /°C from 20°C to 60°C. The elastic modulus of the adhesive layer 14 at 20° C. is 0.62 GPa, the elastic modulus at 60° C. is 0.13 GPa, and the ratio of the elastic modulus at 20° C. to the elastic modulus at 60° C. is 0.21. Ta. Further, the thickness of the adhesive layer 14 was 20 μm. An optical element was manufactured in the same manner as in Example 1 except for these materials and configurations.

The configuration and evaluation results of the optical element of Example 5 are summarized in Table 1.

(Example 6)
In Example 6, an optical element having the shape shown in FIG. 5 was manufactured. The first optical element 41 was made of optical glass having an elastic modulus of 118 GPa at 20°C and a linear expansion coefficient of 62×10 ⁻⁷ /°C from 20°C to 60°C. The second optical element 42 was made of an acrylic UV-curable resin having an elastic modulus of 2.6 GPa at 20°C and a linear expansion coefficient of 728×10 ⁻⁷ /°C from 20°C to 60°C. The second optical element 42 was molded on the first optical element 41, and its maximum thickness in the optical axis direction was 2 mm, and the outer circumferential thickness was 0.01 mm. The third optical element 43 was made of optical glass having an elastic modulus of 76 GPa at 20° C. and a linear expansion coefficient of 117×10 ⁻⁷ /° C. from 20° C. to 60° C. An optical element was manufactured in the same manner as in Example 1 except for these materials and configurations.

The configuration and evaluation results of the optical element of Example 6 are summarized in Table 1.

(Peeling at the optical element interface)
In the optical element of Example 1, adhesive layers having different elastic moduli as shown in Table 2 were used to observe the occurrence of peeling between the optical elements.

Table 2 shows the elastic modulus and evaluation results of the adhesive layers of Reference Examples 1 to 6 in which adhesive layers having different elastic moduli were used.

10, 20, 30, 40 Optical equipment 11, 21, 31, 41 First optical element 12, 22, 32, 42 Second optical element 13, 23, 33, 43 Third optical element 14, 24, 34 , 44 Adhesive layer

Claims (11)

An optical element comprising a first optical element and a third optical element made of glass or plastic, and a second optical element made of optical resin,
The opposing surfaces of the first optical element and the second optical element and/or the opposing surfaces of the second optical element and the third optical element are joined with an adhesive resin layer,
The first optical element has a convex shape on a surface facing the second optical element,
The third optical element has a concave shape on a surface facing the second optical element,
When the indentation modulus of the adhesive resin layer at 20°C is Ead1 and the indentation modulus at 60°C is Ead2, the following formula (1) is satisfied: 0.2≦Ead2/Ead1≦0.5 (1)
An optical element that satisfies the following formula (2), where linear expansion coefficients from 20° C. to 60° C. of the first optical element and the third optical element are α1 and α3, respectively.
0.25≦α1/α3<1.0 (2) 2. The optical element according to claim 1, wherein the second optical element is an optical resin layer having a maximum thickness in the optical axis direction of 0.3 mm or more and 10 mm or less. The optical element according to claim 2, wherein the maximum thickness of the second optical element in the optical axis direction is 2.0 mm or less. The optical element according to any one of claims 1 to 3, which satisfies the following formula (3) and the following formula (4) when the linear expansion coefficient from 20 °C to 60 °C of the second optical element is α2. .
9.0≦α2/α1≦24.5 (3)
5.0≦α2/α3≦11.0 (4) The optical element according to any one of claims 1 to 4, which satisfies the following formula (5), where the maximum thickness in the optical axis direction of the second optical element is t2c, and the outer diameter thickness is t2e. .
0.005≦t2e/t2c<0.95 (5) The optical element according to claim 5, wherein the t2e/t2c satisfies the following formula (6).
0.005≦t2e/t2c≦0.05 (6) The linear expansion coefficient of the first optical element is in the range of 30×10 ⁻⁷ /°C or more and 81×10 ⁻⁷ /°C or less,
The optical element according to any one of claims 1 to 6, wherein the third optical element has a linear expansion coefficient in a range of 66×10 ⁻⁷ /°C or more and 136×10 ⁻⁷ /°C or less. The optical element according to any one of claims 1 to 7, wherein the adhesive resin layer has an indentation modulus of elasticity at 20°C in a range of 0.31 GPa or more and 1.87 GPa or less. An optical device comprising a housing and an optical system including a plurality of lenses within the housing,
An optical device characterized in that at least one of the lenses is an optical element according to any one of claims 1 to 8. An imaging device comprising a housing, an optical system including a plurality of lenses within the housing, and an imaging element that receives light passing through the optical system,
An imaging device characterized in that at least one of the lenses is an optical element according to any one of claims 1 to 8. The imaging device according to claim 10, wherein the imaging device is a camera.

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