JP2022056102A - Method for manufacturing optical member, and optical member - Google Patents

Abstract

To provide a method for manufacturing an optical member, capable of easily reducing manufacturing cost, and the optical member.SOLUTION: A method for manufacturing an optical member 141 comprising steps of: charging a glass powder including chalcogenide glass into a molding die 10; and hot-press molding and integrating the glass powder can manufacture the optical member 141 using the glass powder including chalcogenide glass. Therefore, it is not necessary to cut and polish the glass ingot of chalcogenide glass to manufacture a preform, and manufacturing cost can be reduced.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for manufacturing an optical member and an optical member.

Infrared cameras used in in-vehicle night vision and security systems are being developed. Infrared cameras are equipped with optical members such as filters and lenses that transmit infrared rays.

A crystalline material such as germanium (Ge) or silicon (Si) is often used for the optical member. However, Ge is an expensive material and is disadvantageous in reducing the cost of the optical member. In addition, Si has a low infrared transmittance, which is disadvantageous for improving the performance of an infrared camera.

Therefore, chalcogenide glass has been proposed as a material having excellent infrared transmittance and being relatively inexpensive (Patent Document 1).

Special Table 2015-521148 Gazette Japanese Unexamined Patent Publication No. 2012-201523

A method of manufacturing an optical member by heat-press molding of chalcogenide glass is known (Patent Document 2). However, the above method has a problem that it is necessary to cut and polish a glass ingot of chalcogenide glass to produce a preform, and the manufacturing cost tends to increase.

In view of the above problems, it is an object of the present invention to provide a method for manufacturing an optical member and an optical member whose manufacturing cost can be easily reduced.

The present invention is a method for manufacturing an optical member, which comprises a step of filling a glass powder containing chalcogenide glass into a molding die, and a step of heat-press molding the glass powder to integrate the glass powder.

In the method for manufacturing an optical member of the present invention, it is preferable that the average particle size of the glass powder is 300 μm or more.

In the method for producing an optical member of the present invention, the proportion of chalcogenide glass in the glass powder is preferably 90% or more in terms of mass%.

In the method for producing an optical member of the present invention, it is preferable that the chalcogenide glass contains 20% to 95% of S + Se + Te in mol%.

In the method for manufacturing an optical member of the present invention, it is preferable that the yield point T of the chalcogenide glass is 400 ° C. or lower.

In the method for producing an optical member of the present invention, it is preferable that the heat press molding is performed at a bending point T-40 ° C. or higher of the chalcogenide glass.

The method for manufacturing an optical member of the present invention preferably includes a step of forming a functional film on the surface of the optical member.

In the method for manufacturing an optical member of the present invention, it is preferable that the functional film is an antireflection film and / or a carbon-based protective film.

The optical member of the present invention is characterized by being an integrated product of glass powder containing chalcogenide glass.

In the optical member of the present invention, it is preferable that the ratio of the linear transmittance A and the diffusion transmittance B at a wavelength of 2.5 μm satisfies 1 <(B / A) ≦ 5.

According to the present invention, it is possible to provide a method for manufacturing an optical member and an optical member that can easily reduce the manufacturing cost.

(A) and (b) are schematic cross-sectional views for explaining a step of filling a glass powder containing chalcogenide glass into a mold in the method for manufacturing an optical member according to the first embodiment of the present invention. .. It is a schematic sectional drawing for demonstrating the heat press molding process in the manufacturing method of the optical member which concerns on 1st Embodiment of this invention. It is a schematic sectional drawing for demonstrating the heat press molding process in the manufacturing method of the optical member which concerns on 2nd Embodiment of this invention. It is a schematic sectional drawing for demonstrating the heat press molding process in the manufacturing method of the optical member which concerns on 3rd Embodiment of this invention. It is a partial cross-sectional image of the optical member of Example 1. It is a graph which shows the linear transmittance of the optical member of Example 1 and Reference Example 1. It is a graph which shows the diffusive transmittance and the linear transmittance of the optical member of Example 1. FIG.

Hereinafter, preferred embodiments will be described. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. Further, in the drawings, members having substantially the same function may be referred to by the same reference numeral.

(First Embodiment)
1 (a) and 1 (b) are schematic cross-sectional views for explaining a step of filling a glass powder containing chalcogenide glass into a molding mold in the method for manufacturing an optical member according to the first embodiment of the present invention. Is. Further, FIG. 2 is a schematic cross-sectional view for explaining a heat press molding step in the method for manufacturing an optical member according to the first embodiment of the present invention. As shown in FIGS. 1 (a), 1 (b) and 2, in the present embodiment, the glass powder 4 is heat-press molded using the molding die 10 including the lower die 1, the upper die 2 and the body die 3. ..

First, as shown in FIG. 1 (a), the lower mold 1 and the body mold 3 are installed. The lower mold 1 has a first protrusion 11a in the center. The first protrusion 11a has a first molding surface 111. In the present embodiment, the first molding surface 111 is a horizontal plane. A body mold 3 is arranged on the lower mold 1. Specifically, the body mold 3 is arranged on the lower mold 1 by fitting the protruding portion 11a into the through hole 13a of the body mold 3. As a result, the molded portion 10a surrounded by the first molding surface 111 and the through hole 13a is formed. The molded portion 10a has an opening 10b that opens on the opposite side of the lower mold 1. The glass powder 4 is introduced from the opening 10b and filled in the molded portion 10a.

Next, as shown in FIG. 1 (b), the upper mold 2 is installed on the upper part of the glass powder 4. The upper mold 2 has a second protrusion 12a in the center. The second protrusion 12a has a second molding surface 121. In the present embodiment, the second molding surface 121 is a horizontal plane. The protruding portion 12a has a cross-sectional shape that can be fitted into the through hole 13a of the body mold 3, and if the protruding portion 12a is inserted into the through hole 13a of the body mold, the molded portion 10a becomes a closed space. be able to. Further, by raising and lowering the upper die 2, the protruding portion 12a can be raised and lowered in the through hole 13a.

Next, as shown in FIG. 2, the glass powder 4 is heat-press molded and integrated. More specifically, the second protruding portion 12a is introduced into the molding portion 10a, and the upper mold 2 is pressed downward. At this time, the glass powder 4 is integrated by pressing the glass powder 4 while heating it. As a result, the optical member 141 made of an integrated product of the glass powder 4 can be manufactured. The optical member 141 has a main surface to which the shapes of the first molding surface 111 and the second molding surface 121 are transferred. In the present embodiment, the optical member 141 is a plate-shaped optical member having two horizontal planes facing each other. Instead of pressing the upper mold 2 downward, the lower mold 1 may be pressed upward.

According to the manufacturing method of the present embodiment, the optical member 141 can be manufactured by using the glass powder 4 containing chalcogenide glass. Therefore, it is not necessary to cut and polish the glass ingot of chalcogenide glass to produce a preform, and the manufacturing cost can be reduced.

Further, according to the manufacturing method of the present embodiment, it is possible to manufacture an optical member having a complicated shape. For example, an optical member having a radius of curvature of 10 mm or less, 5 mm or less, particularly 3 mm or less can be suitably manufactured. Generally, in order to manufacture an optical member having a complicated shape by heat press molding, a preform having a near-shape of the product is likely to be required from the viewpoint of shape followability, and the manufacturing cost is likely to increase. On the other hand, the glass powder 4 is superior in shape followability as compared with the bulk preform. Therefore, even an optical member having a complicated shape can be easily manufactured.

Further, according to the manufacturing method of the present embodiment, it is possible to manufacture an optical member having a large diameter. For example, it is possible to manufacture an optical member having an effective diameter φ of 100 mm or more, 150 mm or more, particularly 200 mm or more. Generally, chalcogenide glass is produced by vacuum-sealing a raw material in a quartz test tube and melting it. Therefore, in order to obtain a large-diameter glass ingot, a custom-made quartz test tube is required, which tends to increase the manufacturing cost. Further, when melting is performed using a quartz test tube having a large diameter, the glass is liable to have veins or devitrification, which may make melting difficult. On the other hand, in the manufacturing method of the present embodiment, since it is sufficient to fill the molding die 10 having a desired effective diameter φ with a predetermined amount of glass powder 4, a large-diameter glass ingot and a large-diameter bulk preform are manufactured. There is no need. Therefore, even a large-diameter optical member can be easily manufactured. Large diameter optics are particularly suitable for, for example, aerospace applications.

The materials of the lower mold 1, the upper mold 2 and the body mold 3 are not particularly limited, but for example, carbon, tungsten carbide, silicon carbide, glassy carbon, silicon nitride or titanium carbide are preferably used. Thereby, the heat resistance of the lower mold 1, the upper mold 2 and the body mold 3 can be enhanced. In addition, the releasability is less likely to decrease even at high temperatures. Boron nitride, titanium carbide, diamond-like carbon (DLC) or the like may be coated on the surfaces of the lower mold 1, the upper mold 2 and the body mold 3 in order to improve the mold releasability.

Heat press molding is performed at T-40 ° C or higher, T-30 ° C or higher, T-20 ° C or higher, T-10 ° C or higher, T ° C or higher, and T + 5 ° C or higher when the yield point of chalcogenide glass is T ° C. It is preferable to do it. If the temperature of the heat press molding is too low, the integration of the optical member 141 becomes insufficient, and pores tend to remain inside. Such pores scatter incident light and tend to reduce the infrared transmittance of the optical member 141. On the other hand, if the temperature of the heat press molding is too high, the glass powder 4 is liquefied and becomes molten glass, and a minute gap of the molding mold 10 (for example, a gap between the lower mold 1 and the body mold 3 or a gap between the upper mold 2 and the body mold 3) is formed. Since it enters the gap), the releasability tends to decrease. Further, the molten glass is more easily oxidized than the glass powder 4, and oxidation impurities are more likely to be generated. Such oxidizing impurities tend to reduce the infrared transmittance of the optical member 141. Therefore, the temperature of the heat press molding is preferably T + 50 ° C. or lower, T + 40 ° C. or lower, and T + 30 ° C. or lower, for example.

The load at the time of heat press molding is preferably, for example, 5 MPa to 60 MPa, 10 MPa to 40 MPa, and particularly preferably 20 MPa to 30 MPa. If the load is too small, the optical member 141 is insufficiently sintered, and vacancies tend to remain inside. If the load is too large, the molding die 10 is likely to be damaged.

The heat press molding is preferably performed in the atmosphere. As a result, the manufacturing cost can be further reduced. From the viewpoint of suppressing the oxidation of the glass powder 4, for example, heat press molding may be performed in an inert atmosphere such as nitrogen, argon or helium.

The press time for heat press molding is preferably, for example, 30 seconds to 1000 seconds, 60 seconds to 600 seconds, and particularly preferably 100 seconds to 300 seconds. If the press time of the heat press molding is too short, the integration of the optical member 141 becomes insufficient, and pores tend to remain inside. If the press time of the heat press molding is too long, the glass powder 4 is devitrified and the infrared transmittance tends to decrease.

A step of forming a functional film on the surface of the optical member 141 may be provided after the glass powder 4 is heat-press molded to produce the optical member 141. In this way, the optical member 141 having a functional film on the surface can be manufactured. By having the functional film, the optical characteristics and weather resistance of the optical member 141 can be improved. In this step, well-known film forming methods such as a PVD (Physical Vapor Deposition) method such as a sputtering method and a vacuum deposition method, a CVD (Chemical Vapor Deposition) method, and a coating method such as spraying and spin coating can be used. ..

The functional film is preferably an antireflection film and / or a carbon-based protective film. As the antireflection film, it is preferable that the low refractive index layer and the high refractive index layer are alternately laminated with a total of two or more layers, two to 34 layers, particularly four to twelve layers. If the number of layers is too small, it becomes difficult to obtain the desired optical characteristics. If the number of layers is too large, the manufacturing cost tends to increase. The combination of the low refractive index layer and the high refractive index layer is not limited, and the refractive index of the high refractive index layer may be relatively larger than the refractive index of the low refractive index layer. When both the antireflection film and the carbon-based protective film are provided, either of them may be the outermost surface, but for example, it is preferable that the carbon-based protective film is the outermost surface. By doing so, the optical member 141 is less likely to be damaged.

The thickness of the low refractive index layer and the high refractive index layer per layer is preferably 0.01 to 10 μm, 0.02 to 5 μm, and particularly preferably 0.03 to 2 μm. If the thickness is too small, it will be difficult to obtain the desired optical characteristics. If the thickness is too large, the stress applied to the interface between the functional film and the optical member 141 becomes large, and the adhesion of the functional film and the mechanical strength of the optical member 141 tend to decrease.

Examples of the low-refractive index layer and the high-refractive index layer include metal oxides (Y ₂ O ₃ , Al ₂ O ₃ , SiO, SiO ₂ , MgO, TIO, TIO ₂ , Ti ₂ O ₃ , CeO ₂ , Bi ₂ O ₃ ). , HfO ₂ ), hydride carbon, diamond-like carbon (DLC), Ge, Si, ZnS, ZnSe, As ₂ S ₃ , As ₂ Se ₃ , PbF ₂ , telluride, fluoride (YF ₃ ), etc. Can be done.

As the carbon-based protective film, it is preferable to use diamond-like carbon (DLC).

The glass powder 4 contains chalcogenide glass. Chalcogenide glass contains at least one selected from chalcogen elements (S, Se, Te) as an essential component. For example, it is preferable to contain S + Se + Te 20% to 95%, 30% to 90%, 40% to 85%, and particularly 50% to 80% in mol%. In this specification, "○ + ○ + ..." Means the total amount of the contents of each corresponding component.

By containing Te among the chalcogen elements, it becomes easier to transmit infrared rays having a longer wavelength (for example, infrared rays having a wavelength of 20 μm or more). The content of Te is preferably 20% or more, 40% or more, 50% or more, and particularly preferably 60% or more in mol%. On the other hand, if the content of Te is too large, the weather resistance is lowered, and the glass powder 4 is likely to be deteriorated by water or oxygen in the atmosphere. As a result, the infrared transmittance of the optical member 141 tends to decrease. Therefore, the content of Te is preferably mol%, which is 95% or less, 90% or less, 85% or less, and particularly preferably 80% or less.

In addition to the above components, for example, the following components may be contained.

Ge is a component that expands the vitrification range and enhances the thermal stability of glass without lowering the infrared transmittance. The content of Ge is preferably 0% to 40%, 1% to 35%, 5% to 30%, 7% to 25%, and particularly preferably 10% to 20% in mol%. If the content of Ge is too high, the raw material cost tends to increase.

Ga is a component that expands the vitrification range and enhances the thermal stability of glass without lowering the infrared transmittance. The Ga content is preferably 0% to 30%, 1% to 30%, 3% to 25%, and particularly preferably 4% to 20% in mol%. If the Ga content is too high, the raw material cost tends to increase.

F, Cl, Br, and I are components that enhance the thermal stability of glass. On the other hand, if the content is too large, the weather resistance of the glass powder 4 is lowered, and the glass powder 4 is easily deteriorated by water or oxygen in the atmosphere. As a result, the infrared transmittance of the optical member 141 tends to decrease. Therefore, the content of F + Cl + Br + I is preferably 0 to 40%, 0 to 30%, 0 to 20%, 0 to 10%, and particularly preferably 0 to 5%. The content of each component of F, Cl, Br, and I is preferably 0 to 40%, 0 to 30%, 0 to 25%, and particularly preferably 0 to 20%, respectively.

The yield point T of the chalcogenide glass is preferably 400 ° C. or lower, 350 ° C. or lower, 300 ° C. or lower, and particularly preferably 250 ° C. or lower. If the yield point T is too high, the heating temperature during heat press molding becomes high, and the molding mold 10 is liable to be damaged. The lower limit of the yield point T is not particularly limited, but is, for example, 100 ° C. or higher.

The coefficient of thermal expansion of chalcogenide glass is 250 × ^10-7 / ° C or less, 220 × ^10-7 / ° C or less, 200 × ^10-7 / ° C or less, especially 180 × ^10-7 / ° C in the range of 30 to 150 ° C. The following is preferable. If the coefficient of thermal expansion is too large, cracks are likely to occur during heat press molding, and the manufacturing cost of the optical member 141 is likely to increase. The lower limit of the coefficient of thermal expansion is not particularly limited, but is, for example, 50 × 10 ^-7 / ° C. or higher.

The average particle diameter D ₅₀ of the glass powder 4 is preferably 300 μm or more, 400 μm or more, and particularly preferably 450 μm or more. If the average particle size D ₅₀ is too small, the specific surface area of the glass powder 4 increases, and it is easily deteriorated by water or oxygen in the atmosphere. As a result, the infrared transmittance of the optical member 141 tends to decrease. On the other hand, if the average particle diameter D ₅₀ is too large, the sintering of the optical member 141 becomes insufficient, and pores tend to remain inside. Therefore, the average particle diameter D ₅₀ is preferably 2 mm or less, 1 mm or less, and 900 μm or less. The "average particle diameter D ₅₀ " is a value measured on a volume basis and refers to a value measured by a laser diffraction method.

The ratio of chalcogenide glass to the glass powder 4 is preferably 90% or more, 95% or more, 99% or more, and particularly 99.9% or more in mass%. By doing so, it becomes easy to obtain the desired infrared transmittance. The upper limit is not particularly limited, but may be, for example, 100% or 99.99% or less.

The optical member 141 may contain an inorganic powder other than the glass powder 4. For example, a metal powder such as Ge or Te or a non-oxide ceramic powder may be contained. However, if the content is too large, the infrared transparency tends to decrease. Therefore, the content of the inorganic powder is preferably 10% or less, 5% or less, particularly 3% or less in mass% in the optical member 141. It is preferable that the oxide powder is not substantially contained because it may promote the oxidation of the glass powder 4. In the present invention, "substantially free" means that the optical member 141 is intentionally not contained, and does not mean that unavoidable impurities are completely eliminated. Objectively, it means less than 0.1% by mass.

The ratio of the glass powder 4 to the optical member 141 is preferably 80% or more, 90% or more, 95% or more, and particularly 99% or more in mass%. The upper limit is not particularly limited, but may be, for example, 100%, 99.99% or less, or 99.9% or less.

The optical member 141 preferably has a linear transmittance of 20% or more, 30% or more, and particularly preferably 35% or more at a wavelength of 10 μm. By satisfying the above values, it can be used as an optical member suitable for an infrared device. The upper limit is not particularly limited, but may be, for example, 90% or less, 80% or less, 70% or less, and 65% or less. The above-mentioned linear transmittance means a value measured using a sample having a thickness of 2 mm.

The optical member 141 is an integrated product of glass powder 4 containing chalcogenide glass. In other words, the optical member 141 is made of a sintered body of glass powder 4 containing chalcogenide glass. Therefore, it has characteristic light transmission characteristics due to light scattering at the interface between powders. For example, in the optical member 141, the ratio of the linear transmittance A and the diffusion transmittance B at a wavelength of 2.5 μm is 1 <(B / A) ≦ 5, 1.05 ≦ (B / A) ≦ 4, and further 1. .1 ≦ (B / A) ≦ 3 is satisfied. As described above, the optical member 141 tends to have a diffusion transmittance B larger than a linear transmittance A. On the other hand, if the diffusion transmittance B is too larger than the linear transmittance A, the light scattering becomes too large and it becomes difficult to use it as an infrared device. Therefore, when the B / A satisfies the above upper limit value, the optical member 141 can be suitably used for an infrared device. The linear transmittance A and the diffusion transmittance B described above mean values measured using a sample having a thickness of 1 mm.

The optical member 141 is suitable as an optical member such as an aspherical lens, a spherical lens, a filter, and a window material. Further, the optical member 141 can also be used as a preform for manufacturing another optical member. The surface of the optical member 141 may be optically polished and used, or the above-mentioned functional film may be provided and used.

(Second embodiment)
FIG. 3 is a schematic cross-sectional view for explaining a heat press molding process in the method for manufacturing an optical member according to a second embodiment of the present invention. As shown in FIG. 3, in the molding die 20, the second molding surface 122 has a recess. As a result, the optical member 142 having a convex portion can be formed. For example, the plano-convex optical member 142 can be formed. Other points are the same as those of the first embodiment.

(Third embodiment)
FIG. 4 is a schematic cross-sectional view for explaining a heat press molding step in the method for manufacturing an optical member according to a third embodiment of the present invention. As shown in FIG. 4, in the molding die 30, the first molding surface 113 and the second molding surface 123 are formed of curved surfaces. More specifically, the first molding surface 113 has a convex portion made of a curved surface, and the second molding surface 123 has a concave portion made of a curved surface. Thereby, the optical member 143 having a curved surface can be formed. For example, a meniscus-shaped optical member 143 can be formed. Other points are the same as those of the first embodiment.

Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples.

The optical member of Example 1 was manufactured as follows. First, a glass ingot of chalcogenide glass was prepared. The glass composition was 15% Ge, 5% Ga, 75% Te, and 5% Ag in mol%. The glass ingot obtained by using an agate mortar was crushed and classified to obtain a glass powder having an average particle diameter of 650 μm. Next, the obtained glass powder was filled in a molding die and pressed at a load of 25 MPa and a heating temperature of 190 ° C. for 200 seconds to prepare a disk-shaped optical member made of a sintered body of the glass powder. The obtained optical member was processed to have a predetermined thickness, and the infrared transmittance was measured. Further, a glass ingot having the same composition as that of Example 1 was also processed to have a predetermined thickness to prepare an optical member, which was used as Reference Example 1. The results are shown in FIGS. 5 to 7.

FIG. 5 is a partial cross-sectional image of the optical member of the first embodiment. As shown in FIG. 5, no grain boundaries or bubbles of 1 μm or more were confirmed in the optical member of Example 1.

FIG. 6 is an image showing the linear transmittance (measured value at a thickness of 2 mm) of Example 1 and Reference Example 1. As shown in FIG. 6, the optical member of Example 1 did not show an absorption peak in the infrared region, like the optical member of Reference Example 1 produced by processing an ingot (that is, in a bulk shape). In addition, infrared rays of 20 μm or more were transmitted.

FIG. 7 is an image showing the diffusion transmittance and the linear transmittance (both measured values at a thickness of 1 mm) of Example 1. As shown in FIG. 7, in the optical member of Example 1, the ratio of the linear transmittance A and the diffusion transmittance B at a wavelength of 2.5 μm was 1.1.

According to the method for manufacturing an optical member of the present invention, it is possible to manufacture an optical member that can be suitably used for an infrared device such as an infrared sensor or an infrared camera.

1 Lower mold 2 Upper mold 3 Body mold 4 Glass powder 10, 20, 30 Molding mold 10a Molding part 10b Opening part 11a First protruding part 12a Second protruding part 13a Through hole 141, 142, 143 Optical members 111, 112 , 113 First molding surface 121, 122, 123 Second molding surface

Claims (10)

It is a manufacturing method of optical members.
The process of filling a mold with glass powder containing chalcogenide glass,
A method for manufacturing an optical member, comprising a step of heat-press molding the glass powder to integrate the glass powder. The method for manufacturing an optical member according to claim 1, wherein the average particle size of the glass powder is 300 μm or more. The method for producing an optical member according to claim 1 or 2, wherein the ratio of chalcogenide glass to the glass powder is 90% or more in mass%. The method for producing an optical member according to any one of claims 1 to 3, wherein the chalcogenide glass contains 20% to 95% of S + Se + Te in mol%. The method for manufacturing an optical member according to any one of claims 1 to 4, wherein the yield point T of the chalcogenide glass is 400 ° C. or lower. The method for manufacturing an optical member according to any one of claims 1 to 5, wherein the heat press molding is performed at a yield point T-40 ° C. or higher of the chalcogenide glass. The method for manufacturing an optical member according to any one of claims 1 to 6, further comprising a step of forming a functional film on the surface of the optical member. The method for manufacturing an optical member according to claim 7, wherein the functional film is an antireflection film and / or a carbon-based protective film. An optical member made of an integrated product of glass powder containing chalcogenide glass. The optical member according to claim 9, wherein the ratio of the linear transmittance A and the diffuse transmittance B at a wavelength of 2.5 μm satisfies 1 <(B / A) ≦ 5.

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