WO2023119767A1

WO2023119767A1 - Method for manufacturing optical element, and optical element

Info

Publication number: WO2023119767A1
Application number: PCT/JP2022/035324
Authority: WO
Inventors: 淳村田; 昌樹橋本; 陽平奥山
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2021-12-23
Filing date: 2022-09-22
Publication date: 2023-06-29

Abstract

Provided is a method for manufacturing an optical element. In this manufacturing method, a mirror surface conversion process for converting the entire surface of a columnar material to a mirror surface by heating is performed to form a mirror-surface-converted material from the columnar material, and the mirror-surface-converted material is subjected to mold press forming.

Description

Optical element manufacturing method and optical element

The present disclosure relates to an optical element manufacturing method and an optical element. More specifically, the present disclosure relates to a method of manufacturing an optical element that at least contributes to light transmission, and also relates to an optical element obtained by the manufacturing method.

Optical elements made of resin materials, glass materials, etc. have been used for various purposes. For example, optical elements are used as lenses, prisms, mirrors or optical fibers.

In recent years, optical elements have also been used in the optical sensing field, such as optical sensors for monitoring systems such as disaster prevention and/or crime prevention, or in-vehicle sensor modules for driving support systems.

JP 2013-14455 A WO2020/071071

The inventor of the present application realized that there were problems to be overcome in the production of conventional optical elements, and found the need to take countermeasures therefor. Specifically, it was found that there are the following problems.

Optical elements are manufactured through molding or by processing methods involving cutting, grinding and/or polishing. When an optical element is manufactured by grinding and/or polishing, the final shape of the optical element is obtained by shaving it from a raw material, resulting in a large amount of material loss (FIG. 13).

Mold press molding may be carried out as molding of optical elements. In such molding, since a pressing force is applied to the material using a mold, it is difficult to positively use a material made of a brittle material.

This disclosure has been made in view of such problems. That is, a main object of the present disclosure is to provide a method of manufacturing an optical element that is more suitable in terms of material loss reduction and molding.

The inventors of the present application have attempted to solve the above problems by dealing with them in a new direction, rather than dealing with them on the extension of the conventional technology. As a result, a method for manufacturing an optical element has been provided that achieves the above main object.

In the present disclosure, a method for manufacturing an optical element is provided, in which the entire surface of a columnar material is subjected to a mirror-finishing treatment for mirror-finishing by heating, a mirror-finished material is formed from the columnar material, and the mirror-finished material is subjected to mold press molding. be done.

The present disclosure also provides an optical element obtained by the above manufacturing method. The optical element of the present disclosure includes a light transmitting portion and a flange portion extending outwardly from the light transmitting portion. Different internal strain.

In the manufacturing method of the present disclosure, an optical element can be obtained more preferably in terms of material loss reduction and molding.

Regarding the reduction of material loss, the manufacturing method of the present disclosure can manufacture an optical element under conditions where the material loss of the raw material is reduced. Since the material used for mold press molding has a columnar shape, it is not necessary to obtain a shape relatively close to the shape of the optical element by grinding the material prior to the molding. For example, when manufacturing an optical element such as a lens, it is not necessary to obtain in advance a spherical or flattened lens-like shape by grinding or the like, and the material loss of the optical element can be further reduced.

In addition, in terms of molding, the manufacturing method of the present disclosure can mold optical elements without applying excessive pressing force to the material. For this reason, in the present disclosure, mirror surface treatment is performed by heating prior to mold press molding. Although the specular treatment itself can contribute to the transmittance of the optical element, in the present disclosure, the specular treatment is performed by heating the entire surface of the columnar material. This mirror-finishing treatment by heating the entire surface can bring the overall shape closer to the final shape of the optical element compared to the original columnar material, so it is possible to reduce the excessive pressing force applied to the material during mold press molding. It becomes possible. Therefore, even if the raw material is made of a brittle material, it can be used more positively for mold press molding.

Cross-sectional view schematically showing a lens as an optical element (Fig. 1(A): biconvex lens, Fig. 1(B): biconcave lens, Fig. 1(C): meniscus lens) Schematic cross-sectional view for explaining a part of the manufacturing method of the present disclosure Cross-sectional view schematically illustrating the configuration of a mold used in mold press molding Process cross-sectional views schematically illustrating mold press molding in the manufacturing method of the present disclosure Cross-sectional view schematically illustrating the configuration of a non-sleeve mold used in mold press molding Process cross-sectional view schematically illustrating mold press molding in the manufacturing method of the present disclosure (using a non-sleeve mold) Schematic cross-sectional view for explaining "aspect of mirror surface treatment using a mold" Schematic cross-sectional view for explaining "a mode of continuous processing using a mold" Cross-sectional view schematically showing a lens as an optical element (Fig. 9(A): biconvex lens, Fig. 9(B): biconcave lens, Fig. 9(C): meniscus lens) 3A and 3B are a perspective view and a plan view showing an exemplary embodiment of the optical element of the present disclosure; FIG. Schematic diagrams exemplarily showing characteristics of internal strain in a light transmitting portion of an optical element according to the present disclosure FIG. 2 is a cross-sectional view schematically illustrating the manner in which a meniscus lens is mold-pressed in accordance with the present disclosure; Schematic diagram for explaining an exemplary mode of manufacturing a lens by shaving from a raw material by grinding and polishing (prior art)

In the following, a method for manufacturing an optical element according to one embodiment and an optical element obtained by the manufacturing method will be described in more detail. However, more detailed description than necessary may be omitted. For example, detailed descriptions of well-known matters or redundant descriptions of substantially the same configurations may be omitted. This is to avoid unnecessary verbosity of the description and to facilitate understanding by those skilled in the art.

Applicants provide the accompanying drawings and the following descriptions for the full understanding of the present disclosure by those skilled in the art, and are not intended to limit the claimed subject matter. Various elements in the drawings are only schematically and exemplarily shown for understanding of the manufacturing method and the optical element of the present disclosure, and the external appearance, dimensional ratios, etc. may differ from the actual ones.

"Upward" and "downward" used directly or indirectly in this specification correspond to the upward and downward directions in the drawings, respectively. In a preferred embodiment, the downward vertical direction (that is, the direction in which gravity acts) corresponds to the "downward direction", and the opposite direction corresponds to the "upward direction".

In this specification, the "cross-sectional view" is based on a virtual cross section obtained by cutting along the thickness direction of the optical element. In other words, a sketch of a cross section cut along the thickness of the optical element corresponds to the "cross-sectional view". Typically, the "thickness direction of the optical element" can correspond to the direction of light transmission in the optical element. Further, the term “planar view” used in this specification is based on a sketch of the object viewed from above or below along the thickness direction.

Various numerical values and ranges referred to herein are also intended to include the lower or upper numerical value itself, unless specific terms such as "less than" or "greater than/greater than" are provided. . That is, taking a numerical range of 1 to 10 as an example, it can be interpreted as including the lower limit of "1" and the upper limit of "10".

[Manufacturing method of the present disclosure]
The present disclosure relates to methods of manufacturing optical elements. In particular, the present disclosure manufactures optical elements from blanks by mold pressing. Mold press molding is a method of pressing and molding a material using a mold, and the present disclosure is characterized by items related to the molding method.

Specifically, the entire surface of the columnar material is subjected to mirror-finishing treatment by heating to form a mirror-finished material from the columnar material, and the material obtained by the mirror-finishing treatment by heating, that is, the mirror-finished material is obtained. It is subjected to mold press molding.

In this specification, the term "optical element" broadly means a member for transmitting light. Thus, the optical elements may be lenses, prisms or mirrors, for example. Furthermore, the optical element may be a window item or the like related to light transmission. In a narrow sense, an "optical element" means a member for converging or diverging light, such as a lens (see FIG. 1). When the optical element 10 is a lens, the "light transmitting portion" of the optical element 10 corresponds to the lens portion (at least the "R surface" portion including the optically effective surface).

In the production method of the present disclosure, the material used for mold press molding is a mirror-finished material obtained from the columnar material by heating the entire surface of the columnar material. That is, the material used for mold press molding is a material whose entire surface has been mirror-finished by heating.

FIG. 2 schematically shows an exemplary aspect of the mirror surface treatment in the present disclosure. As shown in FIG. 2, the material to be subjected to mold press molding is a columnar material 20 whose entire surface is heated to obtain a mirror-finished material 25 . Next, the mirror-finished material 25 is subjected to mold press molding using a suitable mold.

The columnar material 20 is, as its name suggests, a material having a columnar shape as a whole. That is, the material to be mirror-finished by heating has a three-dimensional shape in which the cross-sectional shape in a predetermined direction (for example, the cross-sectional shape cut along the direction perpendicular to the thickness direction of the optical element) is substantially constant. It may be a material having an original shape. Such a columnar material 20 may have an overall shape such as a triangular column, a square column, a hexagonal column, or a cylinder, for example.

The columnar material 20 is preferably a single item. Such materials can be obtained from ingots. When the columnar material is obtained from an ingot, the material loss is small. In other words, the material 20 used in the manufacturing method of the present disclosure does not require grinding or the like to obtain a shape relatively close to the final optical element shape, and material loss is small. For example, in mold press molding, it is not necessary to grind a spherical or flattened lens-like material in advance, and material loss is reduced accordingly.

The columnar material may have a polygonal columnar shape or a cylindrical columnar shape. In other words, the material to be subjected to the mirror-finishing by heating may be a prismatic material or a cylindrical material. Prismatic material has a relatively simple shape and can be easily obtained from an ingot. Also, with the prismatic material, it is difficult to form a closed space between the mold surface and the material during molding. Therefore, compared with a material having a large R surface, a prismatic material is less likely to cause so-called "air retention" during molding. The prismatic material may have, for example, a rectangular shape or a substantially rectangular shape in plan view. As used herein, quadrilateral means shapes such as squares and rectangles. On the other hand, the cylindrical material may have a circular or substantially circular shape in plan view.

The columnar material may contain, for example, a glass material. That is, a mirror-finished material may be obtained from a material comprising a glass material, and the mirror-finished material may be subjected to mold press molding. A glass material generally has a large coefficient of linear expansion, and in mold press molding, the amount of expansion during heating and the amount of shrinkage during cooling become large, making molding difficult. In the manufacturing method of the present disclosure, as will be described later, application of excessive pressing force to the material due to the "mirror surface treatment by heating" is further avoided, and materials containing glass materials can be more positively employed.

In the manufacturing method of the present disclosure, the heating performed as mirror surface treatment is performed by heating the entire columnar material from the outside. That is, instead of local heating in which only a partial surface area of the columnar material is heated, the entire surface area of the columnar material is heated. Preferably, the columnar material is mirror-finished by heating the entire surface of the columnar material. Due to the overall plastic deformation of the columnar material, the heating of such a mirror surface treatment can bring the overall shape of the material closer to the shape of the optical element compared to the original columnar material, and the material during mold press molding. can be reduced. Therefore, even if the raw material is made of a brittle material, it can be used more positively for mold press molding.

　The heating performed as a mirror surface treatment may be performed from the entire periphery of the columnar material. That is, the columnar material may be heated from all of the upward, downward, and lateral directions of the columnar material. In other words, the mirror surface heat treatment may be performed so that all the top, bottom and side surfaces of the columnar material are heated. As a result, the surface of the columnar material is not locally heated but wholly heated, and the entire material to be press-molded can more easily approximate the shape of the optical element. The "lateral direction" here corresponds to a direction perpendicular to the material axis along the upward direction and the opposite downward direction of the columnar material.

In the mirror-finishing treatment, it is preferable to soften the entire surface of the columnar material by heating to mirror-finish the columnar material. This is because the overall shape of the material can more easily approximate the shape of the optical element, and the effects of the present disclosure can be more easily realized. The heating time for such mirror finishing may be relatively short. In other words, the softening does not have to reach the central portion of the columnar material, and at least the surface portion may be softened, so the heating time may be short. Specifically, in the case of a columnar material containing chalcogenide glass (for example, IRG203 manufactured by Xinhuaguang), the heating time for the mirror surface treatment is 800 seconds or less, 700 seconds or less, or 650 seconds or less at a temperature higher than the glass transition temperature (Tg). It may be within seconds. For example, the columnar material may be subjected to heat for specular treatment for 400 seconds to 800 seconds, 500 seconds to 700 seconds, or 550 seconds to 650 seconds.

In the production method of the present disclosure, the specular material obtained by heat-treating the entire surface of the columnar material preferably has a smooth surface or a glossy surface. That is, the specular material can preferably have a smooth or glossy surface as its specular surface. In particular, because of the heat treatment of the entire surface (rather than localized heating, such as the edge of the material), the entire surface of the mirrored material (i.e., the surface is ) can be smooth or glossy.

The mirror surface material has a low surface roughness due to its mirror surface. By way of example, the surface roughness of the mirror-finishing material may be reduced to Ra 50 nm or less, preferably Ra 35 nm or less, and more preferably Ra 20 nm or less by the mirror-finishing treatment. In other words, the “mirror surface” of “mirror treatment” and/or “mirror material” in the present disclosure is substantially a mirror surface with a surface roughness of Ra 50 nm or less, preferably Ra 35 nm or less, more preferably Ra 20 nm or less. pointing to The lower limit of the surface roughness Ra is not particularly limited, and may be Ra0 nm (not including 0), for example. In the present disclosure, "Ra" is the so-called arithmetic average roughness, which is a value measured using a scanning white light interferometer (Zygo NewView) for at least one surface forming the outer surface of the mirrored material. be. As the value of the surface roughness Ra, the average value of the measured values at 10 arbitrary points on the surface of the mirror-finished material (for example, 10 arbitrary points including at least the surface constituting the mirror-finished material) may be adopted. .

In the mirror surface treatment by heating, the columnar material may be heated to a temperature higher than its glass transition temperature Tg. That is, the entire surface of the columnar material may be heated under heating conditions higher than the material of the columnar material or the glass transition temperature Tg of the material. For example, as the specular treatment, the columnar material is softened by heating under heating conditions 50 to 200° C. higher than the glass transition temperature Tg of the columnar material, more preferably 100 to 190° C. higher. Such heating conditions tend to soften the entire surface of the columnar material more effectively, and the effects of the present disclosure are more likely to be manifested. For example, if the heating temperature is lower than the lower limit of the above temperature range, it is difficult to obtain a sufficient mirror surface, and defects in the mirror surface of the material are likely to occur. Phenomena such as material cracking are more likely to occur. Here, the "glass transition temperature Tg" in the present disclosure is a value obtained from a thermal expansion curve showing the relationship between temperature and sample elongation. For example, the glass transition temperature Tg of chalcogenide (for example, Xinhuaguang IRG203) is about 266°C, and the glass transition temperature Tg of chalcohalide is about 375°C. Therefore, when a pillar-shaped material comprising chalcogenide is used, the entire surface of the pillar-shaped material may be heated under heating conditions of, for example, about 316°C to about 466°C, preferably about 366°C to about 456°C. When a columnar material comprising a chalcohalide is used, the entire surface of the columnar material may be heated, for example, under heating conditions of about 425°C to about 575°C, preferably about 475°C to about 565°C.

Although the term "temperature condition" in the present disclosure refers to the temperature of the columnar material or its ambient atmosphere, for simplicity or convenience, the set temperature ( For example, the set temperature set in the heating means and/or the mold).

In the manufacturing method of the present disclosure, the mirror-finished material obtained by heat-treating the entire surface is subjected to mold press molding. In other words, in the manufacturing method of the present disclosure, prior to mold press molding, the entire surface of the columnar material is subjected to mirror-finishing treatment for mirror-finishing by heating. In mold press molding, an optical element is molded from a mirror-finished material through pressure deformation. In other words, the light transmitting portion and the flange portion of the optical element can be integrally molded from a single mirror-finished material by mold press molding.

Fig. 3 shows a mold used for mold press molding. As illustrated, the mold 50 used in the manufacturing method of the present disclosure is composed of, for example, at least a pair of upper mold 51 and lower mold 52, which are main parts of the mold. The upper mold 51 and the lower mold 52 are drivable so as to approach or separate from each other, and form a mold cavity 56 therebetween. At least the light-transmitting portion of the optical element is formed by pressing and deforming the mirror-finishing material between the pair of upper mold 51 and lower mold 52 . When the optical element is a lens, the mirror surface material is deformed by the pressing force received from the upper mold 51 and the lower mold 52, and the shape of the lens portion, which is the "essential" of the optical element, is obtained. The mold 50 may additionally comprise a mold sleeve 53, as shown in FIG. The mold sleeve 53 has a "cylindrical shape" as its name suggests, and is provided on the outer peripheral surface of the main part of the mold. The mold sleeve 53 is a mold member that, together with the upper mold side 51 and the lower mold 52, contributes to forming the mold cavity, and preferably acts to bound the outer edges of the mold cavity.

As can be seen from this description, the "mold main part" as used herein means the main mold member that contributes to the formation of most of the mold cavity. On the other hand, the term "mold sleeve" as used herein refers to a mold member that plays a secondary function and is provided on the outer peripheral surface of the main part of the mold so as to constitute at least a part of the body of the mold. means. When the mold cavity is formed by the space surrounded by the upper mold, the lower mold, and the mold sleeve in the mold main part, the mold sleeve is a cylindrical shape that bounds the outer edge of the mold cavity. It is a mold member.

For example, the mold cavity has a circular or substantially circular shape in plan view. That is, the inner peripheral surface of the mold sleeve bounding the outer edge of the mold cavity may have a circular or substantially circular shape in plan view. Specifically, for example, the outer peripheral surface of the main part of the mold has a form of a cylindrical outer surface, and a cylindrical mold sleeve may be provided for it, and the mold has a circular or substantially circular shape in plan view. A cavity is provided.

Mold press molding using such a mold may be performed under temperature conditions specific to mirror-finished materials. For example, mold press molding may be performed under temperature conditions lower than the heating temperature of the mirror surface treatment. This is because the pressure deformation of the specular surface material becomes more preferable, and it becomes easier to obtain an optical element in which the light transmission portion and the flange portion are more preferably integrally molded. For example, mold press molding may be performed under temperature conditions that are preferably 20° C. to 130° C. lower than the heating temperature conditions for the mirror-finishing treatment, for example, under temperature conditions that are 40° C. to 90° C. lower than the heating temperature conditions for the mirror-finishing treatment. . From another point of view, the heating conditions for mirror finishing are preferably 20° C. to 130° C. higher than the heating conditions during mold press molding, for example, 40° C. to 90° C. higher than the heating conditions during mold press molding. may be performed. Heating for such a mirror surface treatment tends to favorably soften the surface of the columnar material as a whole, and the effects of the present disclosure are more likely to be manifested.

In terms of the relationship with the glass transition temperature of the columnar material, mold press molding may be performed at a temperature higher than the glass transition temperature of the columnar material. For example, the mold press molding may be performed under temperature conditions preferably 40° C. to 150° C. higher than the glass transition temperature of the columnar material, for example, 60° C. to 100° C. higher than the glass transition temperature of the columnar material. This is because the specular-finishing material obtained by the specular-finishing treatment based on heating can be more suitably plastically deformed.

In the manufacturing method of the present disclosure, mold press molding may be performed under an inert atmosphere. For example, a nitrogen atmosphere may be used as the atmosphere condition for mold press molding. In other words, the mold press molding of the mirror-finished material may be performed in an atmosphere in which nitrogen gas accounts for the majority. For example, it may be a nitrogen atmosphere with an oxygen concentration of 10 ppm or less.

Next, mold press molding will be described chronologically with reference to FIG. In the mold press molding shown in FIG. 4, the end face of the flange portion of the optical element molded in the mold cavity formed between the upper mold and the lower mold is subjected to mold transfer.

First, as shown in FIG. 4(A), a state in which the specular material 25 is put into the mold 50 is obtained. That is, as shown in the figure, a state is obtained in which the mirror-finished material 25 is placed in a mold cavity 56 surrounded by, for example, an upper mold 51, a lower mold 52, and a mold sleeve 53. FIG.

The mirror surface material 25 may be a single material. Such a mirror-finished material 25 has, as its outer surface, a mechanical tool such as grinding or polishing and/or a liquid treatment (especially a treatment that brings a chemical liquid into contact with the material to obtain a mirror surface, such as a pH adjustment such as an acid range). It preferably has a mirror surface obtained without any chemical treatment using a chemical polishing liquid. In connection with such a mirrored surface, the overall shape of the mirrored blank 25 may have a shape that more closely approximates the final shape of the optical element compared to the original columnar blank. That is, in the present disclosure, the entire surface is mirror-finished by heating, and therefore the mirror-finishing treatment in the present disclosure is preferably a non-mechanical or non-chemical treatment.

The mirror-finished material 25 put into the mold 50 is deformed by being pressed by the heated mold 50 during mold press molding. That is, the specular surface material 25 is heated by the heat of the mold 50, and deformed by the pressing force received from the mold 50 as shown in FIGS. 4(B) and 4(C) into a desired shape. . More specifically, the single mirror-finishing material 25 is plastically deformed by the pressing force received from the mold 50 , and the inner surface shape of the mold 50 (especially the upper mold 51 and the lower mold 52 ) changes to the mirror-finishing material 25 . A light transmitting portion and a flange portion are integrally obtained from the material 25 by transferring. In addition, when the columnar material corresponds to a prismatic material and the biconvex lens is formed from the mirror-finished material obtained by heating the entire surface thereof, the mirror-finished material 25 in the mold has an inconvenient "air" on its upper or lower surface. It is likely to have the advantage of being less likely to cause accumulations.

The mirror-finished material 25, which is plastically deformed during mold pressing, is deformed so as to expand outward, and then comes into contact with the mold sleeve 53 (see FIG. 4(D)). That is, the material 25 comes into contact with the inner peripheral surface 58 of the mold sleeve 53 having a circular shape or a substantially circular shape in plan view. In mold press molding, mold transfer is performed on the entire circumference of the end surface of the mirror-finished material. In mold transfer of the entire periphery of the end surface, the flange shape of the optical element, that is, the peripheral edge contour of the optical element can be easily arranged in a desired shape.

During mold pressing, the deformation of the mirror surface material is caused by the pressing force received from the mold. In the manufacturing method of the present disclosure, the pressing force that can be applied to the material can be a pressure that is not undesirably excessive. Due to the "heating of the entire surface" described above, the mirrored material preferably has an overall shape (especially the shape formed by the entire surface or the entire outer surface) that is closer to the final optical element compared to the original columnar material. This is because it has a shape. Therefore, even if the raw material is made of a brittle material, it can be used more positively for mold press molding. For example, glass materials such as chalcogenide materials and/or chalcohalide materials have been thought to be generally unsuitable for mold press molding because they are brittle under pressure, although they are excellent lens materials in terms of optical properties. Even such a glass material can be used in the manufacturing method of the present disclosure. In addition, the fact that the load applied to the mirror surface material during mold press molding is not excessive is that the material is ground prior to mold press molding to a shape relatively close to the shape of the optical element (for example, a lens approximate shape). This means that the material does not need to be prepared in advance. In other words, the material loss of the raw material is reduced as a result, and from such a point of view as well, it is easy to employ a glass material such as a chalcogenide material and/or a chalcohalide material in the present disclosure.

A mirror-polished material comprising a glass material (e.g., a chalcogenide material and/or a chalcohalide material) reduces the pressing force of the mold press by, for example, at least 5% compared to a material obtained by mechanical mirror-finishing. be able to. In one aspect, the mold press pressure applied to the heat-treated mirror-polished material is reduced by 5% to 50%, or 10% to 40%, as compared to the mechanically mirror-polished material. can be

The mirror-finished material 25 that has been desirably transferred to the mold is released from the mold at the final stage of mold pressing. That is, the mirror-finished material that has been plastically deformed by the mold press is finally removed from the mold after unloading and cooling, and is provided as the desired optical element 10 (see FIG. 4(E)).

The manufacturing method of the present disclosure can be embodied in various modes.

(Aspect of non-edge)
In such a mode, mold press molding is performed without using a mold sleeve. That is, in mold press molding, the end face of the flange portion of the optical element molded in the mold cavity formed between the upper mold and the lower mold is not subjected to mold transfer. As the mold, for example, a non-sleeve mold 50 as shown in FIG. 5 may be used. As shown, the non-sleeve mold 50 is primarily composed of an upper mold 51 and a lower mold 52 and does not include a sleeve member (such as mold sleeve 53 shown in FIG. 3).

In this aspect, when the mirror-finished material is put between the upper mold and the lower mold, the outer peripheral portion of the material that is not in contact with the upper and lower molds is not subjected to mold transfer. For example, as shown in the schematic process diagram of FIG. 6, mold press molding is performed without transferring to a mold sleeve. This means that although mold press molding is performed in the same manner as in the embodiment described with reference to FIG.

Specifically, the mirror-finished material 25 (see FIG. 6A) put into the mold 50 is heated by the heat of the mold 50 and deformed by the pressing force received from the mold 50 (see FIG. 6 ( B) and FIG. 6(C)). In particular, the mirror-finished material 25, which receives pressure from the upper mold 51 and the lower mold 52 of the mold 50, is plastically deformed so as to expand outward. In other words, the material obtained by the mirror-finishing treatment for mirror-finishing the entire surface by heating is plastically deformed due to the pressing force received from the mold 50 . The mirror-finished material 25 (FIG. 6(D)), which has been transferred to the desired mold through such plastic deformation, is released from the mold at the final stage of mold press molding and taken out as an optical element 10 (FIG. 6(E) )reference). In such a mode, the mirror-finished material 25, which is plastically deformed during mold press molding, is not pressed against the mold sleeve 53 (see FIG. 4(D)), and therefore the entire circumference of the end surface of the mirror-finished material is not transferred to the mold. Therefore, the outermost end surface (particularly, the end surface of the flange portion) of the obtained optical element 10 can have, for example, a rounded shape (see FIG. 6(E)).

In the manufacturing method of the present disclosure, the mirror-finished material that is mold press-molded has a shape that is closer to the final optical element than the original columnar material due to the mirror-finishing treatment. In other words, the mirrored material has a mirror surface on its entire surface, but the overall shape is relatively close to the final optical element (that is, the final shape of the optical element compared to the original columnar material). "Relative approximation shape to the optical element"). Therefore, the plastic deformation of the mirror-finished material that deforms toward the outer peripheral portion that is not in contact with the upper and lower dies during mold press molding is easily performed uniformly, and the desired lens shape can be obtained by mold press molding without using a mold sleeve. It can be pressurized and deformed.

Also, when a mold sleeve is not used, the close contact between the mold sleeve and the lens edge surface is essentially avoided during molding. In other words, if there is a close contact between the mold sleeve and the lens edge surface, cracks may occur due to the difference in contraction due to the difference in linear expansion coefficient during the cooling process after molding. If no sleeve is used, it is reduced.

(Aspect of mirror surface treatment using a mold)
In such an embodiment, the entire surface of the columnar material is heated and mirror-finished by using a mold used for mold press molding. That is, a mirror-finished material is obtained with a mold for mold press molding. For example, a mold cavity of a mold used for mold press molding may be used to perform mirror surface treatment. More specifically, the mold cavity of the lower mold used for mold press molding may be used to perform the mirror surface treatment. For example, as shown in FIG. 7, the heat of the lower mold 52 may be used to mirror-finish the columnar material 20 . This means that the columnar material may be mirror-polished by the forming means prior to mold press forming.

In this embodiment, the columnar material 20 is mirror-finished by heating the columnar material 20 while it is placed in the lower mold 52 (see FIG. 7). For example, a columnar material is put into a lower mold whose temperature has been raised to the heating temperature condition of the specular treatment or is in the process of raising the temperature to the heating temperature, and the heat from the lower mold is used to form a columnar shape. Material may be heated. Alternatively, after the columnar material is put into the lower mold, the temperature of the lower mold may be raised to the heating temperature condition, and the heat from the lower mold may be used to heat the columnar material. When the mold cavity of the lower mold is used for the mirror surface treatment in this manner, a portion of the columnar material and the lower mold may be in contact with each other. In this regard, the lower mold may contact only a portion of the bottom surface (or the bottom surface or bottom side portion) of the columnar blank. For example, only the perimeter or rim of the bottom surface of the columnar blank may come into contact with the lower mold. The columnar material is supported by the lower mold at the contact portion thereof, and is heated by the lower mold used for the support. If the bottom surface of the columnar material is in full contact with the bottom surface of the columnar material, the heating condition of the bottom surface of the columnar material may become too strong. It becomes easier to heat the entire surface evenly. The lower mold may, for example, form the convex or concave shape of the optical surface of the optical element. That is, the cavity-forming surface of the lower mold may have a shape complementary to the convex or concave shape of such optical surface. In another way, the cavity forming surface of the lower mold may be curved, for example. When the lower mold is used for the mirror surface treatment, the lower mold may be used in combination with the upper mold. A mold may be used. In such a case, a heating means (preferably an upper heating means provided on the upper side) may be used in combination with the lower mold (or a mold sleeve provided with the lower mold) as shown.

When the mirror surface treatment is performed by heating using the mold cavity, the mirror surface material can be subjected to mold press molding more smoothly or efficiently. That is, since the mold is commonly used for the mirror-finishing treatment and the mold press molding, the transition from the mirror-finishing treatment to the mold press molding is relatively smooth.

There are no particular restrictions on the method of heating the mold. For example, the mold may be heated using a heating coil built into the mold and/or a heat medium flowing through a heat medium conduit of the mold. The mold may be heated using heating means provided separately from the mold. For example, as shown in FIG. 7, a heating means 60 provided outside the lower mold 52 may be used to heat the lower mold 52 to mirror-finish the columnar material. Furthermore, a heating means 65 may be used instead of the upper mold at the position where the upper mold is arranged when the mold is used (see FIG. 7), thereby heating the columnar material and subjecting it to a mirror finish. may be performed.

(Aspect of continuous treatment using mold)
In such a mode, the mirror-finishing treatment of the columnar material and the cooling of the resulting mirror-finishing material are performed continuously using a mold. For example, as shown in FIG. 8, by using a mold 50 (e.g., especially a lower mold) for mold press molding, the entire surface of the columnar material is heated and mirror-finished to obtain a mirror-finished material. , the same mold 50 (e.g., the lower mold in particular) may be used to cool the mirror-finished material. That is, the means for mold pressing, the means for obtaining the mirror-finished material, and the means for cooling it may be substantially the same. A mold used for mold press molding obtains a mirror-finished material, and the mold can be used to mold-press the mirror-finished material, so that smoother production of optical elements can be achieved. In such a continuous process, for example, the time required for mold press molding may be shorter than the time required for mirror polishing. When the metal mold is used to cool the mirror-finished material, the lower mold may be used in combination with the upper mold. However, as shown in FIG. A lower mold may be used. In such a case, a cooling means (preferably an upper cooling means provided on the upper side) may be used in combination with the lower mold (or a mold sleeve provided with the lower mold) as shown.

(Condition of lens product)
In such an embodiment, a lens is manufactured as the optical element 10 . That is, manufacturing lenses for converging or diverging light. The type of lens is not particularly limited, and may be a convex lens or a concave lens. The convex lens may be a biconvex lens (FIG. 1(A)), a plano-convex lens, or the like, and the concave lens may be a biconcave lens (FIG. 1(B)), a plano-concave lens, or the like. Furthermore, the lens may be a meniscus lens as shown in FIG. 1(C). It should be noted that the optical element obtained according to the above-described "non-edge aspect" may have a unique shape because the entire circumference of the end face of the mirror-finished material is not molded and transferred. Specifically, the outermost edge surface of the optical element 10 may have a rounded shape as a whole. For example, in the case of the lens shown in FIG. 9, in a cross-sectional view of a biconvex lens (FIG. 9A), a biconcave lens (FIG. 9B), a meniscus lens (FIG. 9C), etc., the outermost edge surface The profile may be curved as a whole.

As described above, in the manufacturing method of the present disclosure, since the mirror-finished material obtained by heating the entire surface is subjected to mold press molding, it is difficult to apply an excessive pressing force to the material during mold press molding, and even brittle materials can be used. Can be actively recruited. Therefore, in the production method of the present disclosure, glass materials can be used more positively. In particular, a chalcogenide material and/or a chalcohalide material can be used more positively due to the mirror-finishing treatment that mirror-finishes the entire surface by heating. Since chalcogenide materials have suitable transmission properties for the infrared region, and chalcogenide materials can have suitable transmission properties for the visible light region as well as the infrared region, the manufacturing method of the present disclosure is , as an optical element, a lens for at least the infrared region can be suitably manufactured.

[Optical element of the present disclosure]
The optical element of the present disclosure is obtained by the manufacturing method described above, and corresponds to an optical element obtained from a raw material through the mold press molding described above. In other words, the optical element of the present disclosure is an optical element obtained by mold-press molding a columnar material whose entire surface has been mirror-finished by heating.

The optical element of the present disclosure preferably comprises a light transmitting portion and a flange portion extending outwardly therefrom. When the optical element is a lens, the optical element of the present disclosure has a light transmission portion corresponding to the lens portion and a flange portion extending outwardly therefrom. The flange portion corresponds to the outermost edge portion of the optical element that does not contribute to light transmission when the optical element is in use, and is a portion of the optical element that can have, for example, a substantially constant thickness.

FIG. 10 shows a schematic diagram when the optical element 10 is a lens. Although only one example of the optical element, FIG. 10 shows a perspective view and a plan view of the appearance of a biconvex lens as the optical element 10 .

In the optical element 10 according to the present disclosure, the light-transmitting portion 11 has a peripheral region (for example, a “region including the outermost peripheral portion” in the light-transmitting portion) and an inner region inside the peripheral region. is different. That is, as shown in the schematic diagram of FIG. 11, the amount of internal strain may be different between the inner region 11A corresponding to the substantial light transmitting portion of the light transmitting portion 11 and the surrounding region 11B. Note that the inner region and the surrounding region may correspond to regions that are adjacent to each other and integrally contact each other in a plan view. The lower diagram of FIG. 11 illustrates the relative magnitude relationship of internal strain. In the lower diagram of FIG. 11, relatively dark colored portions indicate relatively large internal strain, and relatively light colored portions indicate relatively small or no internal strain. The internal strain feature of FIG. 11 is preferably related to the manufacturing method described above. In particular, internal strains associated with mold pressing, which is performed with little material loss, may be introduced into the optical element. The internal strain shown in FIG. 11 is obtained by mold press molding the material without obtaining an approximate lens shape by grinding or the like prior to mold press molding (preferably, mold press molding the material whose entire surface has been heat-treated as a mirror surface treatment. It can be said that this is an example of the internal strain that is characteristic of the optical element obtained by

In the present disclosure, the "surrounding area" may correspond to an area including the outermost peripheral portion of the light transmitting portion 11 in plan view. Although it is only an example, for example, if the diameter of the circular shape of the light transmitting portion 11 in plan view is D (see FIG. 11), the light transmitting region outside the concentric circular region having a diameter of at least 0.5D is referred to as the "surrounding region." can be regarded as

The planar shape of the inner region may be a shape in which each side of a polygon such as a square curves toward the center and/or the periphery. For example, the planar shape of the inner region is a shape in which each side of a polygon such as a square (for example, a quadrangle) is curved relatively inward so that each side has an extreme value in the middle region or central portion. you can For example, when the light transmitting portion of an optical element is virtually divided into an inner area in which each side of a square is curved toward the center and an outer peripheral area, the amount of internal strain between them is may be different. For example, in the exemplary embodiment shown in FIG. 11, the lighter colored portion may correspond to the inner region and the darker colored portion may correspond to the peripheral region.

In a preferred embodiment, the outer shape of the inner region (that is, the shape of the inner region in plan view) may be considered to correspond to the outer shape of the columnar material before mold press forming that forms the optical element. Then, the distortion-free region of the square or other polygonal columnar material may be processed by mold press molding into a shape in which each side of the square or other polygon is curved toward the center or the periphery. In such a case, in the light-transmitting portion, the internal strain may be different between a region corresponding to the outer shape of the columnar material (hereinafter also referred to as a “material-corresponding region”) and other regions. That is, as shown in FIG. 11 (particularly, an exemplary planar view in the case where the optical element shown below is a lens), in the light transmitting portion 11, the lens of the area corresponding to the dimension of the region corresponding to the material The amount of internal distortion is different between the surface and the lens surface of the other area.

In the present disclosure, the internal strain in the light transmitting portion can be grasped, for example, by measuring retardation (phase difference). A commercially available measuring instrument may be used to measure the retardation (phase difference). For example, a model PA-300-MT-NIR850 manufactured by Photonic Lattice Co., Ltd. may be used to measure retardation (phase difference). With such a retardation measuring instrument, it is possible to grasp the internal strain of the light transmitting portion (that is, the distribution of internal strain as shown in the lower diagram of FIG. 11).

When the mirror-finished columnar material has a prismatic shape, the region corresponding to the material of the light transmitting portion in plan view can be a quadrangle such as a square. In such a case, for example, the amount of internal strain may be different between the area corresponding to the dimension of the square material corresponding region in plan view and the area corresponding to the other light transmitting portion (that is, the surrounding region). Although this is only an example, the internal strain in the square region area corresponding to the dimensions of the prismatic shape is about 8 to 12 nm, while the internal strain in the other region area (that is, the surrounding region area) is the maximum. It may be about 30 nm.

Thus, in the optical element of the present disclosure, the amount of internal strain may be different between the inner region of the light transmitting portion and the peripheral region of the light transmitting portion, but the strain of the inner region including the central portion of the light transmitting portion is small. or substantially none. Because of such distortion properties, the optical element of the present disclosure as a whole can have desired optical properties. For example, optical properties substantially comparable to those of optical elements manufactured through mechanical processing such as cutting, grinding and/or polishing (see FIG. 13) (e.g., optical elements manufactured through such mechanical processing) Optical elements of the present disclosure may have optical transmission properties that are substantially similar to optical elements of the present disclosure.

In a preferred aspect, the optical element has a stress distribution according to the plan view shape of the columnar material. That is, when the optical element is made of a glass material, the molded optical element may have a stress distribution according to the shape of the glass material due to the above-described manufacturing method. Further, in the optical element of the present disclosure, if it is desired to change the average value of the internal strain within the optical effective diameter, it can be handled by changing the dimensions of the columnar material. That is, when changing the average value of the internal strain within the optical effective diameter, it is possible to arbitrarily change the dimensions of the columnar material to be mirror-finished. In addition, the material is not limited to a prismatic shape (that is, the planar shape of the area corresponding to the material of the light transmitting portion is not limited to a quadrangle such as a square). It may be a shaped material. That is, the planar shape of the region corresponding to the material of the light transmitting portion may be triangular, hexagonal, or circular. In such a case, a stress distribution corresponding to the triangular prism, hexagonal prism, or cylinder of such material can be obtained in the light transmitting portion of the optical element.

The optical element 10 of the present disclosure is preferably obtained by mold press molding from a single material 20, and thus has a unique configuration. Specifically, in the optical element 10 of the present disclosure, the light transmission portion 11 and the flange portion 12 are preferably made of the same material and integrated with each other. In the embodiment shown in FIG. 10, the light transmitting portion 11 corresponding to the lens portion and the flange portion 12 outside thereof are made of the same material and are integrated with each other. Integrating with the same material in this manner increases the homogeneity and further improves the structural strength of the optical element 10 compared to the case where the light transmitting portion 11 and the flange portion 12 are integrated with different materials. can be.

The optical element 10 of the present disclosure is obtained under the condition that the load applied to the specular material during mold press molding is not excessive. Therefore, the optical element 10 can be suitably obtained through mold press molding from a chalcogenide material and/or a chalcogenide material or the like. In other words, the optical element 10 of one preferred embodiment comprises a chalcogenide material and/or a chalcohalide material. It can also be said that the optical element 10 can comprise a so-called chalcogenide and/or chalcohalide glass. Most succinctly, it can be said that the optical element 10 preferably consists of a chalcogenide glass or a chalcohalide glass.

The term "chalcogenide material" as used herein broadly refers to at least one chalcogen element selected from the group consisting of S (sulfur), Se (selenium) and Te (tellurium) in group VIb of the periodic table. is one of the main components. For example, the chalcogenide material contains Ge (germanium), As (arsenic), Sb (antimony), P (phosphorus), Ga (gallium), In (indium), and Si (silicon). The term "chalcogenide material" as used herein means a halogen element (at least one selected from the group consisting of fluorine, chlorine, bromine and iodine) or a compound thereof introduced into such a chalcogenide material. means a material having a composition such that it consists of Such chalcogenide and/or chalcohide materials and the like may have suitable transmission properties for the infrared region or for both the infrared and visible regions. Therefore, the optical element 10 of the present disclosure can be suitably used as a lens for transmitting at least light rays in the infrared region.

Although the embodiments have been described above, they are merely examples of typical examples. Therefore, those skilled in the art will easily understand that the manufacturing method and optical element of the present disclosure are not limited to this, and that various embodiments are conceivable.

For example, in the above description, a preferred mode of manufacturing the optical element was described with reference to the drawings, but that is for convenience of description only. The manufacturing method of the present disclosure may have its overall process in view of actual manufacturing. For example, the manufacturing methods of the present disclosure may be based on continuous processing. Alternatively, the manufacturing method of the present disclosure may be based on batch processing.

In addition, in the above description with reference to FIG. 7, a mode in which the columnar material is heated by the heat from the lower mold to perform the mirror-finishing treatment has been described, but the present disclosure is not limited to this. For example, an upper mold of the mold may additionally or alternatively be used to heat the columnar material for mirror surface treatment. In such a case, the columnar material may be mirror-finished by heating the upper mold using a heating coil built into the upper mold and/or a heat medium flowing through the heat medium pipe of the upper mold. . Also, a heating means provided separately from the upper mold may be used. For example, the upper mold may be heated using a heating means arranged outside the upper mold to perform the mirror surface treatment.

Furthermore, in the above description, the embodiment of mold-pressing a biconcave lens or a biconvex lens as a lens has been mainly described, but the present disclosure is not limited to this. For example, as shown in FIG. 12, the present disclosure can be applied in the same way even when the optical element 10, which is a meniscus lens, is mold-press molded.

The optical element according to the present disclosure can be used as various lenses. In particular, the optical element according to the present disclosure may comprise a chalcogenide material and/or a chalcohalide material, etc. in certain preferred embodiments, so an infrared lens (a lens intended at least for far-infrared rays, by way of example only) ), a visible light lens, or a broadband transmission lens that transmits light in both the infrared region and the visible light region.

REFERENCE SIGNS LIST 10 optical element 11 light transmitting portion 11A inner region of light transmitting portion 11B peripheral region of light transmitting portion 12 flange portion 20 columnar material 25 mirror surface material 50 mold 51 upper mold 52 lower mold 53 mold sleeve 56 mold cavity 58 Inner peripheral surface of mold sleeve 60 Heating means 65 Heating means

Claims

A manufacturing method for manufacturing an optical element,
A method of manufacturing an optical element, comprising the steps of subjecting the entire surface of a columnar material to mirror-finishing by heating to form a mirror-finished material from the columnar material, and subjecting the mirror-finished material to mold press molding.
2. The method of manufacturing an optical element according to claim 1, wherein the specular surface treatment includes heating and softening the columnar material under a heating condition 50° C. to 200° C. higher than the glass transition temperature of the columnar material.
3. The method of manufacturing an optical element according to claim 1, wherein the heating is performed by heating the columnar material from all of the upward direction, the downward direction, and the lateral direction of the columnar material.
The method for manufacturing an optical element according to any one of claims 1 to 3, wherein the mold press molding is performed at a temperature 20°C to 130°C lower than that of the mirror surface treatment.
The method for manufacturing an optical element according to any one of claims 1 to 4, wherein the mold press molding is performed at a temperature condition that is 40°C to 150°C higher than the glass transition temperature of the columnar material.
6. The method for manufacturing an optical element according to claim 1, wherein the specular surface treatment is performed using a mold cavity of a lower mold used for the mold press molding.
7. The method of manufacturing an optical element according to claim 6, wherein the lower mold contacts only a portion of the bottom surface of the columnar material.
8. The method of manufacturing an optical element according to claim 6, wherein the lower mold forms a convex or concave shape of the optical surface of the optical element.
The method for manufacturing an optical element according to any one of claims 1 to 8, wherein the surface roughness Ra of the mirror-finishing material is set to 50 nm or less by the mirror-finishing treatment.
10. The method for manufacturing an optical element according to claim 1, wherein said columnar material has a polygonal columnar shape or a cylindrical columnar shape.
The method for manufacturing an optical element according to any one of claims 1 to 10, wherein the columnar material contains a chalcogenide material and/or a chalcohalide material.
12. The mold press molding according to any one of claims 1 to 11, wherein the end surface of the flange portion of the optical element molded in a mold cavity formed between an upper mold and a lower mold is subjected to mold transfer. 3. A method for manufacturing the optical element according to .
12. The method according to any one of claims 1 to 11, wherein in the mold press molding, the end surface of the flange portion of the optical element molded in a mold cavity formed between an upper mold and a lower mold is not subjected to mold transfer. A method for manufacturing an optical element according to any one of the above.
an optical element,
comprising a light transmissive portion and a flange portion extending outwardly from the light transmissive portion;
In the optical element, in the light transmitting portion, internal strain is different between a peripheral region and an inner region inside the peripheral region.
15. The optical element according to claim 14, wherein the planar view shape of the inner region is a shape in which each side of the polygon curves toward the center or the periphery.
15. The optical element according to claim 14, wherein the outer shape of said inner region corresponds to the outer shape of a columnar material before mold press forming forming said optical element.
The optical element according to any of claims 14-16, wherein the optical element comprises a chalcogenide material and/or a chalcohalide material.