WO2019142397A1

WO2019142397A1 - Optical glass, optical element equipped with optical glass, and optical device

Info

Publication number: WO2019142397A1
Application number: PCT/JP2018/034202
Authority: WO
Inventors: 幸平吉本; 山本　博史
Original assignee: 株式会社ニコン
Priority date: 2018-01-18
Filing date: 2018-09-14
Publication date: 2019-07-25
Also published as: JP7024802B2; JPWO2019142397A1

Abstract

An optical glass containing Al³⁺ and P⁵⁺ in amounts of 30 to 40% and 1 to 15%, respectively, when expressed in cation mol%, also containing O^2- and F^- in amounts of 5 to 16% and 84 to 95%, respectively, when expressed in anion mol%, and also having a ratio (O/P) of the number of oxygen atoms to the number of phosphorus atoms of less than 3.4.

Description

Optical glass, optical element using optical glass, optical device

The present invention relates to an optical glass, an optical element using the optical glass, and an optical apparatus. The present invention claims priority to Japanese Patent Application No. 2018-006394 filed on Jan. 18, 2018, and the contents described in that application for designated countries permitted to be incorporated by reference to the literature Incorporated herein by reference.

Fluorite having low refractive index and low dispersion is used as a lens material of an optical system in an optical device. Fluorite is manufactured, for example, by the descent method (Bridgeman method) as shown in Patent Document 1.

JP 2005-330156 A

The first embodiment of the present invention is 30-40% of Al ³⁺ and 1-15% of P ^{5+ in terms} of mole percent of cation, and 5-16 of O ²⁻ in terms of mole percent of anion. %, F 2 ⁻ is 84 to 95%, and the ratio of the number of oxygen atoms to the number of phosphorus atoms (O / P) is less than 3.4.

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

A third aspect of the present invention is an optical device comprising the optical element of the second aspect.

It is a perspective view of an imaging device concerning this embodiment. It is a block diagram which shows the example of a structure of the multiphoton microscope which concerns on this embodiment. It is the figure which plotted the (lambda) ₈₀ value with respect to O / P of each Example and each comparative example.

Hereinafter, an embodiment of the present invention (hereinafter, referred to as "the present embodiment") will be described. The following present embodiment is an example for describing the present invention, and is not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of the gist of the present invention.

In the present specification, unless otherwise specified, the content of each component is shown in terms of mol% of cation and in mol% of anion. The term “mol% of cation” and “mol% of anion” as used herein mean that the total amount of the cation component and the total amount of the anion component contained in the glass are 100 mol%. It is assumed that complex salts such as carbonates, hydroxides, nitrates and hydrous salts used as raw materials of glass constituents are all decomposed at the time of melting to change into oxides and / or fluorides. In addition, the gas component produced by decomposition | disassembly of complex salt is not considered as a glass structural component.

The optical glass according to the present embodiment has 30 to 40% of Al ^{3+ and} 1 to 15% of P ^{5+ in terms} of mole percent of cation, and 5 to 16 of O ²⁻ in terms of mole percent of anion. %, F 2 ⁻ is 84 to 95%, and the ratio of the number of oxygen atoms to the number of phosphorus atoms (O / P) is less than 3.4. According to this embodiment, the fluorophosphate-based optical glass can have an optical constant of low refractive index and low dispersion, and can be excellent in ultraviolet and visible light transmittance.

For example, although fluorite is manufactured by the Bridgman method, it has a problem that it is unsuitable for mass production because the amount that can be manufactured at one time is limited and it takes time. In addition, since fluorite has cleavage properties, there is also a problem that mechanical strength is poor and processing is difficult. With regard to these points, the optical glass according to the present embodiment can solve the above-mentioned problems of fluorite while having the low refractive index and low dispersion equivalent to fluorite.

(Cation component)
Al ³⁺ has the effect of improving the devitrification resistance of the optical glass. When the content is small, the optical glass is easily devitrified, but even if it is introduced in excess, the optical glass is easily devitrified. From this point of view, the content of Al ³⁺ is 30 to 40%, preferably 32 to 38%, and more preferably 34 to 37%.

P ⁵⁺ has the effect of improving the devitrification resistance of the optical glass. When the content is small, the optical glass is easily devitrified, but when it is introduced excessively, the dispersion becomes too large. From this viewpoint, the content of P ⁵⁺ is 1 to 15%, preferably 3 to 12%, and more preferably 5 to 10%.

In the present embodiment, for example, components such as Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ca ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Zn ²⁺ , Y ³⁺ , La ³⁺ , Gd ³⁺ , and Zr ⁴⁺ are appropriately contained. Can.

Li ⁺ has the effect of enhancing the meltability of optical glass, but if it is introduced in excess, in addition to the resistance to devitrification being lowered, the viscosity of the glass at the time of molding is lowered and the glass tends to be difficult to mold. is there. From such a viewpoint, the content of Li ⁺ is preferably 0 to 3%, more preferably 0 to 2%, and still more preferably 0 to 1%.

Na ⁺ has the effect of improving the meltability of optical glass, but when it is introduced in excess, it has the tendency that the viscosity of the glass at the time of molding is lowered and the glass forming becomes difficult, in addition to the devitrification resistance being lowered. is there. From such a viewpoint, the content of Na ⁺ is preferably 0 to 3%, more preferably 0 to 2%, and still more preferably 0 to 1%.

K ⁺ has the effect of enhancing the meltability of optical glass, but if it is introduced in excess, in addition to the resistance to devitrification being lowered, the viscosity of the glass at the time of molding is lowered and the glass tends to be difficult to mold. is there. From this point of view, the content of K ⁺ is preferably 0 to 2%, more preferably 0 to 1.5%, and still more preferably 0 to 1%.

Mg ²⁺ has the effect of improving the devitrification resistance of the optical glass. If the content is too small, the effect of improving the devitrification resistance can not be obtained sufficiently. In addition, when incorporated in excess, the refractive index tends to decrease, and the devitrification resistance tends to decrease. From this point of view, the content of Mg ²⁺ is preferably 5 to 10%, more preferably 6 to 9%, and still more preferably 7 to 8%.

Ca ²⁺ has an effect of improving the devitrification resistance of the optical glass. If the content is too small, the effect of improving the devitrification resistance can not be obtained sufficiently. In addition, when incorporated in excess, the refractive index tends to decrease, and the devitrification resistance tends to decrease. From this point of view, the content of Ca ²⁺ is preferably 20 to 30%, more preferably 22 to 28%, and still more preferably 23 to 25%.

Sr ²⁺ has the effect of increasing the refractive index of the optical glass and improving the devitrification resistance. If the content is too small, the effect of increasing the refractive index and the effect of improving the devitrification resistance can not be sufficiently obtained. Moreover, when it introduce | transduces excessively, a dispersibility will become large too much, and it exists in the tendency for devitrification resistance to fall on the contrary. From this point of view, the content of Sr ²⁺ is preferably 10 to 20%, more preferably 12 to 18%, and still more preferably 14 to 17%.

Ba ²⁺ has the effect of increasing the refractive index of the optical glass and improving the devitrification resistance. If the content is too small, the effect of increasing the refractive index and the effect of improving the devitrification resistance can not be sufficiently obtained. Moreover, when it introduce | transduces excessively, a dispersibility will become large too much, and it exists in the tendency for devitrification resistance to fall on the contrary. From this point of view, the content of Ba ²⁺ is preferably 3 to 10%, more preferably 4 to 9%, and still more preferably 5 to 8%.

Zn ²⁺ has the effect of improving the devitrification resistance of the optical glass. However, when it is introduced in excess, the dispersibility tends to be too large. From this point of view, the content of Zn ²⁺ is preferably 0 to 3%, more preferably 0 to 2%, and still more preferably 0 to 1%.

Y ^{3 +} has the effect of improving the devitrification resistance of the optical glass, maintaining the low dispersion of the optical glass and increasing the refractive index, and maintaining the meltability of the raw material to suppress the rise in liquidus temperature. However, when it is introduced in excess, the meltability of the glass raw material is deteriorated, and the liquidus temperature tends to rise to lower the devitrification resistance of the glass. From this point of view, the content of Y ³⁺ is preferably 0 to 5%, more preferably 0 to 3%, still more preferably 0 to 2%, and still more preferably 0 to 1%. .

La ³⁺ has an effect of maintaining the low dispersion of the optical glass while increasing the refractive index, maintaining the meltability of the raw material, suppressing the rise of the liquidus temperature, and improving the devitrification resistance of the optical glass. However, when it is introduced in excess, the meltability of the glass raw material is deteriorated, and the liquidus temperature tends to rise to lower the devitrification resistance of the glass. From this point of view, the content of La ³⁺ is preferably 0 to 5%, more preferably 0 to 3%, still more preferably 0 to 2%, and still more preferably 0 to 1%. .

Gd ³⁺ has the effect of enhancing the refractive index while maintaining the low dispersion of the optical glass, maintaining the meltability of the raw material, suppressing the rise of the liquidus temperature, and improving the devitrification resistance of the optical glass. However, when it is introduced in excess, the meltability of the glass raw material is deteriorated, and the liquidus temperature tends to rise to lower the devitrification resistance of the glass. From this point of view, the content of Gd ³⁺ is preferably 0 to 5%, more preferably 0 to 3%, still more preferably 0 to 2%, still more preferably 0 to 1%. .

Zr ^{4 +} has an effect of enhancing the refractive index of the optical glass, suppressing the dispersion, and improving the devitrification resistance. However, when incorporated in excess, the dispersibility becomes too large, and the devitrification resistance also tends to decrease. From this point of view, the content of Zr ⁴⁺ is preferably 0 to 1%.

As preferable combinations of the contents of the above-mentioned components, 5 to 10% of Mg ²⁺ , 20 to 30% of Ca ²⁺ , 10 to 20% of Sr ²⁺ , and 3 to 10% of Ba ²⁺ . In addition, Li ⁺ is 0 to 3%, Na ⁺ is 0 to 3%, K ⁺ is 0 to 2%, and Zn ²⁺ is 0 to 3%. Further, Y ³⁺ is 0 to 5%, La ³⁺ is 0 to 5%, Gd ³⁺ is 0 to 5%, and Zr ⁴⁺ is 0 to 1%.

(Anion component)
The anion components O ²⁻ and F ² ⁻ contribute to the refractive index, dispersibility, stability, etc. of the optical glass. From the viewpoint of the dispersion of the optical glass and the refractive index, O ²⁻ is 5 to 16%, preferably 7 to 14%, more preferably 9 to 12% in terms of mol% of anions. From the viewpoint of dispersion of the optical glass and the refractive index, F ^{− in} terms of mol% of the anion is 84 to 95%, preferably 86 to 93%, more preferably 88 to 91%.

If the ratio of the number of oxygen atoms to the number of phosphorus atoms (O / P) is less than 3.4, good ultraviolet transmittance can be maintained, but if it is 3.4 or more, the internal transmittance is 80% The wavelength (λ ₈₀ ) shifts to the long wavelength side, and the light transmittance in the ultraviolet region is degraded. From this point of view, O / P is less than 3.4, preferably 3.2 or less, and more preferably 3.0 or less. The ratio (O / P) of the number of oxygen atoms to the number of phosphorus atoms has the same meaning as the ratio of oxygen (O) to phosphorus (P) in atomic% (at.%).

Not only the said component but another component can also be added in the range from which the effect of the optical glass which concerns on this embodiment is acquired.

The manufacturing method of the optical glass which concerns on this embodiment is not specifically limited, A well-known method is employable. Moreover, manufacturing conditions can select suitable conditions suitably. For example, raw materials such as oxides and fluorides are prepared to have a target composition, preferably melted at 850 to 1150 ° C., more preferably 950 to 1050 ° C., homogenized by stirring, and defoamed. After that, it is possible to employ a manufacturing method or the like which is flow-molded in a mold. The optical glass thus obtained can be processed into a desired shape by performing reheat press or the like as necessary, and can be polished or the like to form a desired optical element.

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

The optical glass according to the present embodiment has low refractive index and low dispersion (Abbe number (数_d ) is large). The Abbe number (ν _d ) of the optical glass according to the present embodiment is preferably 92 to 97, more preferably 93 to 97, and still more preferably 94 to 97. In addition, the refractive index (n _d ) of the optical glass according to the present embodiment is preferably 1.41 to 1.45, more preferably 1.42 to 1.45, and still more preferably 1.43 to It is 1.45. The preferred combination as the physical properties of the optical glass according to this embodiment, refractive index _{(n d)} is in the range of 1.41 to 1.45, and the range Abbe number ([nu _d) of 92-97 It is in.

From the viewpoint of the ultraviolet and visible light transmittances of the optical system, the wavelength (λ ₈₀ ) at which the internal transmittance in an optical path length of 10 mm is 80% in the optical glass according to the present embodiment is preferably 340 nm or less, more preferably Is 338 nm or less, more preferably 336 nm or less.

In the optical glass according to this embodiment, the wavelength (λ ₅ ) at which the internal transmittance in an optical path length of 10 mm is 5% is preferably 300 nm or less, more preferably 298 nm or less, still more preferably 296 nm or less It is.

From the viewpoint described above, the optical glass according to the present embodiment can be suitably used, for example, as an optical element included in an optical device. The optical device is particularly suitable as an imaging device and a multiphoton microscope, among others.

<Imaging device>
FIG. 1 shows an imaging device 1 (optical apparatus) including a lens 103 (optical element) having an optical glass according to the present embodiment as a base material. The imaging apparatus 1 is a so-called digital single-lens reflex camera, and a lens barrel 102 is detachably attached to a lens mount (not shown) of a camera body 101. Then, light passing through the lens 103 of the lens barrel 102 forms an image on a sensor chip (solid-state imaging device) 104 of the multi-chip module 106 disposed on the back side of the camera body 101. The sensor chip 104 is a bare chip such as a so-called CMOS image sensor, and the multi-chip module 106 is, for example, a COG (Chip On Glass) type module in which the sensor chip 104 is bare chip mounted on a glass substrate 105.

Higher resolution, lighter weight, and smaller size are required for an optical system used for such a digital camera or the like. In order to realize these, it is effective to use high refractive index optical glass in the optical system. From this point of view, the optical glass according to the present embodiment is suitable as a member of such an optical device. In addition, as an optical apparatus applicable in this embodiment, not only the imaging device mentioned above but a projector etc. are mentioned, for example. The optical element is not limited to the lens, and may be, for example, a prism.

<Multiphoton microscope>
FIG. 2 is a block diagram showing an example of the configuration of the multiphoton microscope 2 according to the present embodiment. The multiphoton microscope 2 includes an objective lens 206, a condenser lens 208, and an imaging lens 210 as optical elements. The optical system of the multiphoton microscope 2 will be mainly described below.

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

The pulse splitting device 202 splits the ultrashort pulse light, raises the repetition frequency of the ultrashort pulse light, and emits it.

The beam adjustment unit 203 has a function of adjusting the beam diameter of the ultrashort pulse light incident from the pulse splitting device 202 according to the pupil diameter of the objective lens 206, the wavelength and ultrashort of the multiphoton excitation light emitted from the sample S Function to adjust the focusing and divergence angle of ultrashort pulse light to correct the on-axis chromatic aberration (focus difference) with the wavelength of the pulse light, the pulse width of the ultrashort pulse light while passing through the optical system It has a pre-chirp function (group velocity dispersion compensation function) or the like that gives inverse group velocity dispersion to ultrashort pulse light in order to correct spreading due to velocity dispersion.

The repetition frequency of the ultrashort pulse light emitted from the pulse laser device 201 is increased by the pulse division device 202, and the above-described adjustment is performed by the beam adjustment unit 203. Then, the ultrashort pulse light emitted from the beam adjustment unit 203 is reflected in the direction of the dichroic mirror 205 by the dichroic mirror 204, passes through the dichroic mirror 205, is condensed by the objective lens 206, and is irradiated onto the sample S. . At this time, the ultrashort pulse light may be scanned on the observation surface of the sample S by using a scanning means (not shown).

For example, when fluorescently observing the sample S, the fluorescent dye to which the sample S is stained is multiphoton-excited in the region to be irradiated with the ultrashort pulse light of the sample S and the vicinity thereof. Fluorescence (hereinafter referred to as "observation light") having a wavelength shorter than that of pulsed light is emitted.

The 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 transmitted through the dichroic mirror 205 according to the wavelength.

The observation light reflected by the dichroic mirror 205 is incident on the fluorescence detection unit 207. The fluorescence detection unit 207 includes, for example, a barrier filter, a PMT (photo multiplier tube), and the like, receives the observation light reflected by the dichroic mirror 205, and outputs an electric signal according to the light amount. . Further, the fluorescence detection unit 207 detects the observation light across 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 transmitted through the dichroic mirror 205 is descanned by the scanning means (not shown), transmitted through the dichroic mirror 204, condensed by the condensing lens 208, and substantially conjugate with the focal position of the objective lens 206. The light passes through the provided pinhole 209, passes through the imaging lens 210, and enters the fluorescence detection unit 211.

The fluorescence detection unit 211 includes, for example, a barrier filter, a PMT, and the like, receives the observation light focused on the light receiving surface of the fluorescence detection unit 211 by the imaging lens 210, and outputs an electrical signal according to the light amount. Further, the fluorescence detection unit 211 detects observation light across 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.

Note that the fluorescence detection unit 211 may detect all the observation light emitted from the sample S in the direction of the objective lens 206 by removing the dichroic mirror 205 from the light path.

The observation light emitted from the sample S in the opposite direction to the objective lens 206 is reflected by the dichroic mirror 212 and enters the fluorescence detection unit 213. The fluorescence detection unit 213 includes, for example, a barrier filter, a PMT, and the like, receives the observation light reflected by the dichroic mirror 212, and outputs an electrical signal according to the light amount. Further, the fluorescence detection unit 213 detects observation light across 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.

For example, the electrical signals output from the

fluorescence detection units

207, 211, and 213 are input to a computer (not shown), and the computer generates an observation image based on the input electrical signals, and generates an observation. An image can be displayed and data of an observation image can be stored.

Examples of the present invention and comparative examples will be described. Each table shows the composition of the optical glass according to the example and the comparative example, the refractive index (n _d ), the Abbe number (v _d ), the wavelength (λ ₈₀ ) at which the internal transmittance at an optical path length of 10 mm is 80%, It is shown together with the measurement result of the wavelength (λ ₅ ) at which the internal transmittance in an optical path length of 10 mm is 5%. The present invention is not limited to these examples.

<Preparation of optical glass>
The optical glass which concerns on each Example and a comparative example was produced in the following procedures. First, optical glass raw materials such as oxides, phosphates and fluorides were weighed so as to have an optical glass weight of 100 g so as to obtain the chemical compositions (weight%) described in the respective tables. Next, the weighed raw materials were mixed, charged into a platinum crucible, melted at a temperature of 950 ° C. for about 1 hour, and stirred and homogenized. Thereafter, the temperature was lowered and then cast into a mold or the like, and each sample was obtained by slow cooling.

<Measurement of optical glass>
1. Refractive index (n _d ) and Abbe number ( _{d d} )
The refractive index of each sample _{(n d)} and Abbe number ([nu _d), the refractive index meter (manufactured by Shimadzu Corporation; "KPR-2000") was measured and calculated using. n _d represents the refractive index of optical glass to light of 587.562 nm. _{d d} was obtained from the following equation (1). n _C and n _F indicate the refractive index of the optical glass with respect to light of wavelengths 656.273 nm and 486.133 nm, respectively. The value of the refractive index was up to the fifth decimal place.
_{d d} = (n _d -1) / (n _F -n _C ) (1)

2. Wavelength internal transmittance is wavelength at which 80% (lambda ₈₀₎ and _5% (λ 5)
Optically polished optical glass samples having a thickness of 12 mm and a thickness of 2 mm were prepared, and the internal transmittance in the wavelength range of 200 to 700 nm when light was incident parallel to the thickness direction was measured. Then, the wavelength at which internal transmittance in an optical path length of 10mm is 80% and lambda _80, the wavelength at which internal transmittance of 5% was lambda _5.

Each table shows the result of each example and comparative example, and the figure which plotted the (lambda) ₈₀ value with respect to O / P in FIG. 3 is shown. In addition, about the numerical value of the composition in a table | surface, unless otherwise indicated, it is shown by mol% of a cation about a cation component, and mol% of an anion about an anion component. Further, “Devitrification” in the Table indicates that devitrification occurs when the optical glass is manufactured, and measurement (that is, use as an optical glass) is impossible.

It was confirmed that each of the examples had a low refractive index and a low dispersion, and the transmittance was good.

DESCRIPTION OF SYMBOLS 1 ... Imaging device, 101 ... Camera body, 102 ... Lens-barrel, 103 ... Lens, 104 ... Sensor chip, 105 ... Glass substrate, 106 ... Multichip module, 2 multiphoton microscope 201 pulsed laser device 202 pulse dividing device 203

beam adjusting unit

204, 205, 212 dichroic mirror 206

objective lens

207, 211, 213 ... fluorescence detection unit, 208 ... condensing lens, 209 ... pinhole, 210 ... imaging lens, S ... sample

Claims

In terms of mol% of cation,
30-40% of Al 3+ ,
P 5+ is 1 to 15%, and
In mole% of anion,
O 2− is 5 to 16%,
F - is 84 to 95%, and
Optical glass, characterized in that the ratio of the number of oxygen atoms to the number of phosphorus atoms (O / P) is less than 3.4.
In terms of mol% of cation,
5 to 10% of Mg 2+ ,
20-30% of Ca 2+ ,
10 to 20% of Sr 2+ ,
The optical glass according to claim 1, wherein Ba 2+ is 3 to 10%.
In terms of mol% of cation,
0 to 3% of Li + ,
Na + is 0 to 3%,
K + 0 to 2%,
The optical glass according to claim 1 or 2, wherein Zn 2+ is 0 to 3%.
In terms of mol% of cation,
Y 3+ is 0-5%,
La 3+ is 0-5%,
Gd 3+ is 0-5%,
The optical glass according to any one of claims 1 to 3, wherein Zr 4+ is 0 to 1%.
The optical glass according to any one of claims 1 to 4, characterized in that the refractive index (n d ) is in the range of 1.41 to 1.45.
The optical glass according to any one of claims 1 to 5, wherein the Abbe number (ν d ) is in the range of 92 to 97.
The optical glass according to any one of claims 1 to 6, wherein a wavelength (λ 80 ) at which the internal transmittance at an optical path length of 10 mm is 80% is 340 nm or less.
The optical glass according to any one of claims 1 to 7, wherein a wavelength (λ 5 ) at which the internal transmittance in an optical path length of 10 mm is 5% is 300 nm or less.
An optical element using the optical glass according to any one of claims 1 to 8.
An optical apparatus comprising the optical element according to claim 9.