阅读说明：本技术 光学玻璃、使用其的光学元件、光学系统、接合透镜、照相机用更换镜头和光学装置 (Optical glass, optical element using same, optical system, cemented lens, interchangeable lens for camera, and optical device ) 是由 小出哲也 井口德晃 于 2018-05-11 设计创作，主要内容包括：一种光学玻璃,其中,以质量％计,SiO<Sub>2</Sub>成分为0％以上且小于5％、P<Sub>2</Sub>O<Sub>5</Sub>成分为10％以上40％以下、B<Sub>2</Sub>O<Sub>3</Sub>成分为4％以上30％以下、Na<Sub>2</Sub>O成分为0％以上11％以下、K<Sub>2</Sub>O成分为5％以上20％以下、TiO<Sub>2</Sub>成分为0％以上20％以下、ZrO<Sub>2</Sub>成分为0％以上2％以下、Nb<Sub>2</Sub>O<Sub>5</Sub>成分为20％以上70％以下,并且P<Sub>2</Sub>O<Sub>5</Sub>成分+B<Sub>2</Sub>O<Sub>3</Sub>成分大于25％且为41％以下、B<Sub>2</Sub>O<Sub>3</Sub>成分/P<Sub>2</Sub>O<Sub>5</Sub>成分为0.15以上且小于1.23、TiO<Sub>2</Sub>成分/P<Sub>2</Sub>O<Sub>5</Sub>成分为0以上且小于1.3、Nb<Sub>2</Sub>O<Sub>5</Sub>成分/P<Sub>2</Sub>O<Sub>5</Sub>成分为0.7以上2.8以下。(An optical glass wherein SiO is contained in an amount of mass% 2 Contains 0% or more and less than 5% of P 2 O 5 The components are more than 10% and less than 40%, B 2 O 3 The components are 4% to 30%, Na 2 O component of 0-11%, K 2 O content of 5-20%, TiO 2 ZrO content of 0-20% 2 The components are more than 0% and less than 2%, Nb 2 O 5 The components are 20% above 70%And P is 2 O 5 Component + B 2 O 3 Component (B) is more than 25% and 41% or less 2 O 3 component/P 2 O 5 Contains 0.15-1.23% of TiO 2 component/P 2 O 5 Has a component of 0 to less than 1.3 and Nb 2 O 5 component/P 2 O 5 The content of the component is 0.7-2.8.)

1. An optical glass in which, in mass%,

SiO₂the components are more than 0 percent and less than 5 percent,

P₂O₅The components are more than 10% and less than 40%,

B₂O₃The components are more than 4 percent and less than 30 percent,

Na₂O component of 0-11%,

K₂The O component is more than 5% and less than 20%,

TiO₂The components are more than 0% and less than 20%,

ZrO₂The components are more than 0% and less than 2%,

Nb₂O₅The component is 20-70%, and

P₂O₅component + B₂O₃The component (b) is more than 25% and less than 41%,

B₂O₃component/P₂O₅The component (A) is more than 0.15 and less than 1.23,

TiO₂component/P₂O₅The component (A) is more than 0 and less than 1.3,

Nb₂O₅component/P₂O₅The content of the component is 0.7-2.8.

2. The optics of claim 1Glass wherein (Na) is contained in mass%₂Component O + K₂O component)/(P₂O₅Component + B₂O₃Component (b) is 0.2 to 0.8 inclusive.

3. The optical glass according to claim 1 or 2, wherein (TiO) is contained in an amount of mass%₂Component + Nb₂O₅component)/(P₂O₅Component + B₂O₃Component (b) is 0.9 to 1.6 inclusive.

4. The optical glass according to any one of claims 1 to 3, wherein the BaO content is 0% to 20% by mass.

5. The optical glass according to any one of claims 1 to 4, wherein the ZnO content is 0% by mass or more and 20% by mass or less.

6. The optical glass according to any one of claims 1 to 5, wherein Al is contained in mass%₂O₃The content of the components is more than 0% and less than 10%.

7. The optical glass according to any one of claims 1 to 6, wherein Sb is present in mass%₂O₃The content of the components is more than 0% and less than 1%.

8. The optical glass according to any one of claims 1 to 7, which contains substantially no Ta.

9. The optical glass according to any one of claims 1 to 8, wherein the refractive index n to d-line_dIs in the range of 1.70 to 1.78.

10. The optical glass as claimed in any of claims 1 to 9, wherein Abbe's number v_dIs in the range of 20 to 30.

11. The E.E. 1E10, wherein the refractive index n to d-line_dAnd Abbe number v_dSatisfy v_d+40×n_d-96.4 is in the relationship of 0 or less.

12. The optical glass according to any one of claims 1 to 11, wherein the specific gravity S is_g2.9 to 3.6.

13. The optical glass according to any one of claims 1 to 12, wherein a partial dispersion ratio (Pg, F) is 0.6 or more.

14. The optical glass as claimed in any one of claims 1 to 13, wherein the internal transmittance at an optical path length of 10mm is up to a wavelength (λ) of 80%₈₀) Is 450nm or less.

15. An optical element comprising the optical glass according to any one of claims 1 to 14.

16. An optical system comprising the optical element of claim 15.

17. A replacement lens for a camera, comprising the optical system according to claim 16.

18. An optical device provided with the optical system according to claim 16.

19. A cemented lens having a 1 st lens element and a 2 nd lens element,

at least 1 of the 1 st lens element and the 2 nd lens element is the optical glass according to any one of claims 1 to 14.

20. An optical system comprising the cemented lens of claim 19.

21. A replacement lens for a camera, comprising the optical system according to claim 20.

22. An optical device comprising the optical system of claim 20.

Technical Field

The invention relates to an optical glass, an optical element, an optical system, a junction lens, a replacement lens for a camera, and an optical device. The present invention claims priority from japanese patent application No. 2017-116580 filed on 14/6/2017, and for a given country approved for content introduction by way of reference, the content described in that application is incorporated by reference into the present application.

Background

In recent years, imaging apparatuses and the like provided with image sensors having a high number of pixels have been developed, and optical glasses having high dispersion and low specific gravity have been required as optical glasses used for these apparatuses.

Disclosure of Invention

A first aspect of the present invention relates to an optical glass in which SiO is present in mass%₂Contains 0% or more and less than 5% of P₂O₅The components are more than 10% and less than 40%, B₂O₃The components are 4% to 30%, Na₂O component of 0-11%、K₂O content of 5-20%, TiO₂ZrO content of 0-20%₂The components are more than 0% and less than 2%, Nb₂O₅The component is 20-70%, and P₂O₅Component + B₂O₃Component (B) is more than 25% and 41% or less₂O₃component/P₂O₅Contains 0.15-1.23% of TiO₂component/P₂O₅Has a component of 0 to less than 1.3 and Nb₂O₅component/P₂O₅The content of the component is 0.7-2.8.

A second aspect of the present invention relates to an optical element using the optical glass of the first aspect.

A third aspect of the present invention relates to an optical system including the optical element of the second aspect.

A fourth aspect of the present invention relates to an interchangeable lens for a camera including the optical system of the third aspect.

A fifth aspect of the present invention relates to an optical device including the optical system of the third aspect.

A sixth aspect of the present invention relates to a cemented lens including a 1 st lens element and a 2 nd lens element, wherein at least 1 of the 1 st lens element and the 2 nd lens element is the optical glass of the first aspect.

A seventh aspect of the present invention relates to an optical system including the cemented lens of the sixth aspect.

An eighth aspect of the present invention is a replacement lens for a camera including the optical system of the seventh aspect.

A ninth aspect of the present invention relates to an optical apparatus including the optical system of the seventh aspect.

Drawings

Fig. 1 is a perspective view showing an example of an imaging device that is an optical device according to the present embodiment.

Fig. 2 is a schematic diagram showing another example of an imaging apparatus using the optical apparatus of the present embodiment.

Fig. 3 is a block diagram showing an example of the configuration of the multiphoton microscope of the present embodiment.

Fig. 4 is a schematic diagram showing an example of the cemented lens of the present embodiment.

Detailed Description

Embodiments of the present invention (hereinafter referred to as "the present embodiment") are explained below. The following embodiments are illustrative of the present invention, and are not intended to limit the present invention to the following. The present invention can be suitably modified and implemented within the scope of the gist thereof.

In the present specification, unless otherwise specified, the contents of the respective components are all mass% (mass percentage) based on the total weight of the glass in terms of oxides. The oxide-converted composition referred to herein means the following composition: the oxides, complex salts, and the like used as the raw materials of the glass constituent components of the present embodiment are all decomposed to oxides during melting, and the respective components contained in the glass are represented by assuming that the total mass of the oxides is 100 mass%.

The optical glass of the present embodiment is the following optical glass: in mass%, SiO₂Contains 0% or more and less than 5% of P₂O₅The components are more than 10% and less than 40%, B₂O₃The components are 4% to 30%, Na₂O component of 0-11%, K₂O content of 5-20%, TiO₂ZrO content of 0-20%₂The components are more than 0% and less than 2%, Nb₂O₅The component is 20-70%, and P₂O₅Component + B₂O₃Component (B) is more than 25% and 41% or less₂O₃component/P₂O₅Contains 0.15-1.23% of TiO₂component/P₂O₅Has a component of 0 to less than 1.3 and Nb₂O₅component/P₂O₅The content of the component is 0.7-2.8.

Conventionally, in order to achieve high dispersion, improvement of TiO has been attempted₂、Nb₂O₅And the likeMethod of content of ingredients. However, when the content of these components is increased, the transmittance tends to decrease or the specific gravity tends to increase. In this respect, since the optical glass of the present embodiment can reduce the specific gravity while achieving high dispersion, the weight of the lens can be reduced.

SiO₂Is a component for improving chemical durability and reducing resistance to devitrification. SiO 2₂If the content of (b) is too large, the devitrification resistance tends to be lowered. From such aspect, SiO₂The content of (b) is 0% or more and less than 5%, preferably 0% or more and 4% or less, and more preferably 0% or more and 3% or less. By making SiO₂The content of (b) is in this range, and resistance to devitrification can be improved to improve chemical durability.

P₂O₅Is a component for forming a glass skeleton, improving resistance to devitrification, lowering the refractive index, and reducing chemical durability. P₂O₅If the content of (b) is too small, devitrification tends to occur easily. In addition, P₂O₅When the content of (b) is too large, the refractive index and chemical durability tend to be lowered. From this point on, P₂O₅The content of (b) is 10% to 40%, preferably 20% to 30%, more preferably 20% to 25%. By making P₂O₅The content of (b) is in this range, and thus the resistance to devitrification is improved, the chemical durability is improved, and the refractive index can be increased.

B₂O₃Is a component for forming a glass skeleton, improving resistance to devitrification, lowering the refractive index, and reducing chemical durability. B is₂O₃When the content of (b) is too small, the meltability is deteriorated and devitrification tends to occur easily. In addition, B₂O₃When the content of (b) is too large, the refractive index and chemical durability tend to be lowered. From such aspect, B₂O₃The content of (b) is 4% to 30%, preferably 10% to 20%, more preferably 10% to 18%. By making B₂O₃The content of (b) is in this range, and thus the resistance to devitrification is improved, the chemical durability is improved, and the refractive index can be increased.

Na₂O is a component for improving the melting property and lowering the refractive index. Na (Na)₂When the content of O is too large, the refractive index tends to decrease. From this point of view, Na₂The content of O is 0% to 11%, preferably 1% to 8%, more preferably 1% to 5%. By reacting Na₂The content of O in this range can prevent a decrease in refractive index.

K₂O is a component for improving the melting property, lowering the refractive index, and chemical durability. K₂The content of O is 5% to 20%, preferably 7% to 20%, and more preferably 10% to 20%. By making K₂The content of O in this range enables high chemical durability to be achieved without lowering the refractive index.

TiO₂Is a component for increasing the refractive index and decreasing the transmittance. If TiO₂When the content (b) is large, the transmittance tends to be poor. From such aspect, TiO₂The content of (b) is 0% to 20%, preferably 0% to 15%, more preferably 1% to 10%. By making TiO₂The content of (b) is in this range, and high transmittance can be achieved without lowering the refractive index.

ZrO₂Is a component for increasing the refractive index and reducing resistance to devitrification. If ZrO of₂When the content (c) is large, the glass tends to be easily devitrified. From this aspect, ZrO₂The content of (b) is 0% to 2%, preferably 0% to 1.5%, more preferably 0% to 1%.

Nb₂O₅Is a component for increasing the refractive index and dispersion and decreasing the transmittance. If Nb₂O₅When the content (b) is small, the refractive index tends to decrease. In addition, if Nb₂O₅When the content (b) is large, the transmittance tends to be poor. From such aspect, Nb₂O₅The content of (b) is 20% to 70%, preferably 30% to 60%, more preferably 30% to 55%. By making Nb₂O₅The content of (b) is in this range, and high transmittance can be achieved without lowering the refractive index and dispersion.

P₂O₅And B₂O₃The sum of the contents of (P)₂O₅+B₂O₃) More than 25% and 41% or less, preferably 30% to 41% or less. By making P₂O₅+B₂O₃Within this range, the refractive index can be increased.

B₂O₃Relative to P₂O₅The ratio of the contents of (A), (B)₂O₃/P₂O₅) Is 0.15 or more and less than 1.23, preferably 0.2 or more and 1 or less, and more preferably 0.45 or more and 1 or less. By making B₂O₃/P₂O₅Within this range, the refractive index can be increased.

TiO₂Relative to P₂O₅Content ratio of (TiO)₂/P₂O₅) Is 0 or more and less than 1.3, preferably 0 or more and 1 or less, more preferably 0% or more and 0.5 or less. By making TiO₂/P₂O₅Within this range, the refractive index and the transmittance can be improved.

Nb₂O₅Relative to P₂O₅Content ratio of (Nb)₂O₅/P₂O₅) Is 0.7 to 2.8, preferably 0.7 to 2.5, and more preferably 0.7 to 2.4. By making Nb₂O₅/P₂O₅Within this range, the refractive index and the transmittance can be improved.

The optical glass of the present embodiment may further contain Li₂O、MgO、CaO、SrO、BaO、ZnO、Al₂O₃、Y₂O₃、La₂O₃、Gd₂O₃、Sb₂O₃、WO₃And Ta₂O₅One or more of the group of ingredients as optional ingredients.

From the aspect of meltability, Li₂The content of O is preferably 0% to 10%, more preferably 0% to 5%, and further preferably 0% to 2%.

From the viewpoint of high dispersion, the content of MgO is preferably 0% to 20%, more preferably 0% to 15%, and still more preferably 0% to 10%.

From the viewpoint of high dispersion, the content of CaO is preferably 0% to 20%, more preferably 0% to 15%, and further preferably 0% to 10%.

The SrO content is preferably 0% to 20%, more preferably 0% to 15%, and further preferably 0% to 10% in view of high dispersion.

From the viewpoint of high dispersion, the content of BaO is preferably 0% to 20%, more preferably 0% to 10%, and further preferably 0% to 5%.

From the viewpoint of high dispersion, the content of ZnO is preferably 0% to 20%, more preferably 0% to 10%, and still more preferably 0% to 5%.

From the aspect of meltability, Al₂O₃The content of (b) is preferably 0% to 10%, more preferably 0% to 7%, and further preferably 0% to 2%.

From the aspect of meltability, Y₂O₃The content of (b) is preferably 0% to 10%, more preferably 0% to 7%, and further preferably 0% to 5%.

From the aspect of meltability, La₂O₃The content of (b) is preferably 0% to 10%, more preferably 0% to 7%, and further preferably 0% to 5%. Further, from the viewpoint of cost, it is more preferable that La is not substantially contained₂O₃。

Gd₂O₃Since it is an expensive raw material, the content thereof is preferably 0% to 10%, more preferably 0% to 7%, and still more preferably 0% to 5%.

Sb is Sb in view of defoaming property at the time of melting glass₂O₃The content of (b) is preferably 0% to 1%.

From the aspect of transmittance, WO₃The content of (b) is preferably 0% to 10%, more preferably 0% to 7%, and further preferably 0% to 2%.

Ta₂O₅Since it is an expensive raw material, the content thereof is preferably 0% to 5%, and more preferably substantially not contained. From this point of view, it is preferable that Ta is not substantially contained in the present embodiment.

As a preferred combination of their contents, Li₂O component of 0-10%, MgO component of 0-20%, CaO component of 0-20%, SrO component of 0-20%, BaO component of 0-20%, ZnO component of 0-20%, and Al₂O₃Contains more than 0% and less than 10% of Y₂O₃The components are more than 0% and less than 10%, La₂O₃Contains more than 0% and less than 10% of Gd₂O₃The component is 0-10%, Sb₂O₃The components are 0% to 1%, and WO₃The components are 0-10% and Ta₂O₅The content of the components is more than 0% and less than 5%.

In the optical glass of the present embodiment, P is preferred₂O₅、B₂O₃、Na₂O、K₂O、TiO₂、Nb₂O₅The following relationship is satisfied.

Na₂O and K₂Sum of contents of O (Na)₂O+K₂O) relative to P₂O₅And B₂O₃The sum of the contents of (P)₂O₅+B₂O₃) Ratio of (1 to ((Na))₂O+K₂O)/(P₂O₅+B₂O₃) ) is preferably 0.2 to 0.8, more preferably 0.3 to 0.6. By reacting (Na)₂O+K₂O)/(P₂O₅+B₂O₃) Within this range, the dispersion can be improved.

TiO₂And Nb₂O₅Sum of contents of (TiO)₂+Nb₂O₅) Relative to P₂O₅And B₂O₃The sum of the contents of (P)₂O₅+B₂O₃) Ratio of ((TiO)₂+Nb₂O₅)/(P₂O₅+B₂O₃) ) is preferably 0.9 to 1.6, more preferably 1 to 1.5. By reacting (TiO)₂+Nb₂O₅)/(P₂O₅+B₂O₃) Within this range, the dispersion can be improved.

As a preferable combination of the above conditions, (Na)₂O+K₂O)/(P₂O₅+B₂O₃) 0.2 to 0.8 inclusive, (TiO)₂+Nb₂O₅)/(P₂O₅+B₂O₃) Is 0.9 to 1.6 inclusive.

In addition to these, components such as a known clarifying agent, a coloring agent, a defoaming agent, and a fluorine compound may be added to the above glass composition in an appropriate amount as necessary for the purpose of clarification, coloring, decoloring, fine adjustment of an optical constant value, and the like. The optical glass of the present embodiment is not limited to the above components, and other components may be added within a range in which the effects of the optical glass of the present embodiment are obtained.

The method for producing the optical glass of the present embodiment is not particularly limited, and a known method can be used. In addition, the production conditions may be appropriately selected. For example, the following production methods can be employed: raw materials such as oxides, carbonates, nitrates, sulfates and the like are blended so as to have a desired composition, melted at preferably 1100 to 1400 ℃, more preferably 1200 to 1300 ℃, stirred to be homogenized, defoamed, and then injected into a mold to be molded. The optical glass thus obtained can be processed into a desired shape by reheating pressing or the like as necessary, and subjected to polishing or the like, thereby producing a desired optical element.

The raw material is preferably a high-purity product with a small content of impurities. The high purity product means that the content of the component is 99.85% by mass or more. By using a high-purity product, the amount of impurities is reduced, and as a result, the internal transmittance of the optical glass tends to be improved.

Next, the physical property values of the optical glass of the present embodiment will be described.

The optical glass of the present embodiment preferably has a high refractive index (n)_d) Large). However, in general, the refractive index (n)_d) The higher the specific gravity tends to be increased. From such a practical situation, the refractive index (n) of the optical glass of the present embodiment to d-line_d) Preferably 1.70 to 1.78, and more preferably 1.72 to 1.77.

Abbe number (. nu.) of the optical glass of the present embodiment_d) Preferably 20 to 30, and more preferably 22 to 27. The refractive index (n) of the optical glass of the present embodiment_d) And Abbe number (v)_d) For the refractive index (n) of d-line_d) 1.70 to 1.78 and an Abbe number (. nu.) of_d) Is 20 to 30. The optical glass of the present embodiment having such properties can be combined with other optical glasses, for example, to design an optical system in which chromatic aberration and other aberrations are well corrected.

From the viewpoint of correcting chromatic aberration, the refractive index (n) of the optical glass of the present embodiment with respect to d-line_d) And Abbe number (v)_d) Preferably satisfies ν_d+40×n_d-96.4 is in the relationship of 0 or less.

The optical glass of the present embodiment preferably has a low specific gravity in terms of the light weight of the lens. However, in general, the larger the specific gravity, the more the refractive index tends to decrease. From such a practical situation, the preferred specific gravity (S) of the optical glass of the present embodiment_g) The lower limit is 2.9, and the upper limit is 3.6, and the range is 2.9 to 3.6.

The optical glass of the present embodiment preferably has a large partial dispersion ratio (Pg, F) in terms of aberration correction of the lens. From such a practical situation, the optical glass of the present embodiment preferably has a partial dispersion ratio (Pg, F) of 0.6 or more.

In the optical glass of the present embodiment, the internal transmittance at an optical path length of 10mm is a wavelength (λ) at which 80% of the internal transmittance is obtained in terms of the visible light transmittance of the optical system₈₀) Preferably 450nm or less, more preferably 43 nm or less0nm or less.

The optical glass of the present embodiment can reduce Ta, which is an expensive raw material₂O₅And the like, and further, the component may not be contained, and therefore, the composition is excellent in terms of raw material cost.

From the above-described points, the optical glass of the present embodiment can be suitably used as, for example, an optical element provided in an optical device. Particularly suitable as an optical device, in particular as an imaging device or a multiphoton microscope.

< imaging apparatus >

Fig. 1 is a perspective view of an example of an imaging device that is an optical device. The imaging device 1 is a so-called digital single-lens reflex camera (lens-interchangeable camera), and the photographing lens 103 (optical system) includes an optical element having the optical glass of the present embodiment as a base material. The lens barrel 102 is detachably mounted to a lens mount (not shown) of the camera body 101. The light having passed through the lens 103 of the lens barrel 102 is focused on a sensor chip (solid-state image pickup device) 104 of a multi-chip module 106 disposed on the back surface side of the camera body 101. The sensor Chip 104 is a bare Chip such as a so-called CMOS image sensor, and the multichip module 106 is a COG (Chip On Glass) type module in which the sensor Chip 104 is mounted On the Glass substrate 105 as a bare Chip, for example.

Fig. 2 is a schematic diagram of another example in the case where the optical device is an imaging device. Fig. 2(a) shows a front view of the imaging device CAM, and fig. 2(b) shows a rear view of the imaging device CAM. The imaging device CAM is a so-called digital still camera (lens non-interchangeable camera), and the photographing lens WL (optical system) includes an optical element having the optical glass of the present embodiment as a base material.

In the imaging device CAM, when a power button (not shown) is pressed, a shutter (not shown) of the photographing lens WL is opened, and light from an object (object) is condensed by the photographing lens WL and forms an image on an imaging element disposed on an image plane. The subject image formed on the image pickup device is displayed on a liquid crystal display M disposed behind the image pickup device CAM. The photographer determines the composition of the subject image while viewing the liquid crystal display M, then presses the release button B1, captures the subject image with the image pickup device, and records and saves the subject image in a memory (not shown).

The imaging device CAM is provided with an auxiliary light emitting section EF that emits auxiliary light when the object is dark, a function button B2 for setting various conditions of the imaging device CAM, and the like.

Optical systems used in such digital cameras and the like are required to have higher resolution, lighter weight, and smaller size. In order to achieve these functions, it is effective to use a glass having a high refractive index in the optical system. Especially for high refractive index and lower specific gravity (S)_g) Glass having high press moldability is in high demand. From this viewpoint, the optical glass of the present embodiment is suitable as a component of the optical device. The optical device applicable to the present embodiment is not limited to the above-described imaging device, and may be, for example, a projector. The optical element is not limited to the lens, and examples thereof include a prism.

< multiphoton microscope >

Fig. 3 is a block diagram showing an example of the configuration of the multiphoton microscope 2. The multiphoton microscope 2 includes an objective lens 206, a condensing lens 208, and an imaging lens 210. At least one of the objective lens 206, the condenser lens 208, and the imaging lens 210 includes an optical element made of the optical glass of the present embodiment. The following description will be made centering on the optical system of the multiphoton microscope 2.

The pulse laser apparatus 201 emits, for example, ultrashort pulse light having a near-infrared wavelength (about 1000nm) and a pulse width of femtosecond unit (for example, 100 femtoseconds). The ultrashort pulse light immediately after being emitted from the pulse laser device 201 generally forms linearly polarized light polarized in a predetermined direction.

The pulse dividing device 202 divides the ultrashort pulse light, increases the number of repetition frequencies of the ultrashort pulse light, and emits the pulse light.

The light beam adjustment unit 203 has the following functions: a function of adjusting the beam diameter of the ultrashort pulsed light incident from the pulse dividing device 202 according to the pupil diameter of the objective lens 206; a function of adjusting the convergence and divergence angles of the ultrashort pulse light in order to correct axial chromatic aberration (focus difference) between the wavelength of the multiphoton excitation light emitted from the sample S and the wavelength of the ultrashort pulse light; in order to correct the case where the pulse width of the ultrashort pulse light is widened by the group velocity dispersion during the passage through the optical system, a pre-chirp function (group velocity dispersion compensation function) or the like is provided to the ultrashort pulse light with the opposite group velocity dispersion.

The number of repetition frequencies of ultrashort pulsed light emitted from the pulse laser apparatus 201 is increased by the pulse dividing apparatus 202, and the beam adjusting unit 203 performs the adjustment. The ultrashort pulse light emitted from the light beam adjustment unit 203 is reflected by the dichroic mirror 204 in the direction of the dichroic mirror 205, passes through the dichroic mirror 205, is converged by the objective lens 206, and is irradiated onto the sample S. At this time, the ultrashort pulse light can be scanned on the observation surface of the sample S by using a scanning device (not shown).

For example, in the case of fluorescence observation of the sample S, a fluorescent dye that dyes the sample S is subjected to multiphoton excitation in a region where the sample S is irradiated with the ultrashort pulse light and the vicinity thereof, and emits fluorescence (hereinafter referred to as "observation light") having a wavelength shorter than that of the ultrashort pulse light having an infrared wavelength.

Observation light emitted from the sample S in the direction of the objective lens 206 is collimated by the objective lens 206, and is reflected by the dichroic mirror 205 or passes through the dichroic mirror 205 according to the wavelength thereof.

The observation light reflected by the dichroic mirror 205 enters the fluorescence detection unit 207. The fluorescence detection unit 207 is composed of, for example, a blocking filter, a PMT (photomultiplier tube), or the like, receives the observation light reflected by the dichroic mirror 205, and outputs an electric signal according to the amount of the observation light. The fluorescence detector 207 detects the observation light on the observation surface of the sample S in accordance with the scanning of the ultrashort pulse light on the observation surface of the sample S.

On the other hand, the observation light having passed through the dichroic mirror 205 is subjected to descan (descan) by a scanning device (not shown), passes through the dichroic mirror 204, is condensed by the condensing lens 208, passes through a pinhole 209 provided at a position substantially conjugate to the focal position of the objective lens 206, passes through the imaging lens 210, and enters the fluorescence detection unit 211.

The fluorescence detection section 211 is configured by, for example, a blocking filter, a PMT, or the like, receives observation light imaged on the light receiving surface of the fluorescence detection section 211 by the imaging lens 210, and outputs an electric signal according to the light amount thereof. The fluorescence detector 211 detects the observation light on the observation surface of the sample S in accordance with the scanning of the ultrashort pulsed light on the observation surface of the sample S.

Note that, by removing the dichroic mirror 205 from the optical path, all observation light emitted from the sample S in the direction toward the objective lens 206 may be detected by the fluorescence detection unit 211.

Further, the observation light emitted from the sample S in the direction opposite to the objective lens 206 is reflected by the dichroic mirror 212 and enters the fluorescence detection unit 213. The fluorescence detection unit 113 is configured by, for example, a blocking filter or a PMT, and receives the observation light reflected by the dichroic mirror 212 and outputs an electric signal according to the amount of the observation light. The fluorescence detector 213 detects the observation light on the observation surface of the sample S in accordance with the scanning of the ultrashort pulsed light on the observation surface of the sample S.

The electric signals output from the fluorescence detection units 207, 211, and 213 are input to, for example, a computer (not shown) that generates an observation image based on the input electric signals, displays the generated observation image, or stores data of the observation image.

< cemented lens >

Fig. 4 is a schematic diagram showing an example of the cemented lens of the present embodiment. The cemented lens 3 is a compound lens having a 1 st lens element 301 and a 2 nd lens element 302. The optical glass of the present embodiment is used for at least one of the 1 st lens element and the 2 nd lens element. The 1 st lens element and the 2 nd lens element are joined by a joining member 303. As the joining member 303, a known adhesive or the like can be used. In addition, the lens constituting the cemented lens is sometimes referred to as a "lens element" as described above, from the viewpoint of clarifying that the lens is an element of the cemented lens.

The cemented lens according to the present embodiment is useful for chromatic aberration correction, and can be suitably used for the above-described optical element, optical system, optical apparatus, and the like. Further, an optical system including a cemented lens is particularly suitable for use in an interchangeable lens for a camera, an optical device, and the like. In the above embodiment, the cemented lens using 2 lens elements has been described, but the present invention is not limited to this, and a cemented lens using 3 or more lens elements may be used. When a cemented lens using 3 or more lens elements is produced, at least 1 of the 3 or more lens elements may be formed using the optical glass of the present embodiment.