JPS62240534A - Manufacture of optical element - Google Patents

Abstract

PURPOSE:To form an elastic body with high accuracy by a method wherein the elastic body is molded by pouring elastic body material onto the molding surfaces of a mold and then the molded elastic body is released from the mold by pouring gas to the interface between the molding surface and the elastic body through passages provided on the mold or on the elastic body. CONSTITUTION:Raw material for an elastic body is poured through an inlet provided on a side force 4 in a gap portion, which is shaped by a columnar bottom force 2, to which fitting members 1 such as pins, wedges or the like are fitted so as to pass through from the molding surface of the force 2 to its bottom surface, a circular bottom plate 3 and the cylindrical side force 4, and then cured in order to form a columnar elastic body 5. Next, gas passages 1a are formed by drawing the fitting members 1 out of the bottom force 2. When gas such as air or the like is poured under pressure through gas inlets 6a of a jig 6, which is installed onto the bottom surface of the bottom force 2, the gas passes through the passages 1a and reaches the interface between the bottom force 2 and the elastic body 5 and quickly diffuses in the fine gap of the interface so as to lower the adhesion between the bottom force 2 and the elastic body 5 in order to accelerate the mold release. Because consequently the deformation of the elastic body at its mold release is suppressed, the elastic body 5 can be formed with high accuracy.

Description

[Detailed Description of the Invention] Toyotomi Tananej The present invention relates to a method of manufacturing a variable focus optical element using an elastic body. The present invention relates to a method of manufacturing the above-mentioned optical element forming a body.

Oka JLiL Violet This application describes an optical element that can have a variable focal length by changing its optical surface shape, and is used in optical equipment such as cameras and videos, as well as electro-optic equipment such as optical communications and laser discs. (Japanese Unexamined Patent Publication No. 111201/1983).

This variable focus optical element consists of an elastic body and a relatively hard aperture member that has an aperture and contacts the elastic body, and deforms the elastic body so that the elastic body is exposed from the aperture of the aperture member. By changing the shape of the optical surface (hereinafter referred to as the "aperture surface"), it is possible to obtain a large change in focal length with a relatively small change in external force.

In order to achieve good optical characteristics in such a variable focus optical element, it is necessary to form the elastic body constituting the optical surface with high precision to obtain an elastic body with excellent deformation characteristics.

To this end, it goes without saying that the accuracy during the above-mentioned elastic body molding (usually done using a mold) is important, but it is also important to improve the accuracy when forming the elastic body gI star shape after molding (i.e., the elastic body It is also extremely important to minimize deformation during mold release. This is because if the deformation of the elastic body is insufficiently suppressed when the elastic body is released from the mold, it is difficult to form the elastic body after molding with high precision (that is, within desired dimensional tolerances).

Conventionally, in the field of optical elements, there are 7 methods for releasing molded optical elements made of glass, resin, etc.
A method of driving a letter-shaped square into the contact surface between the optical element and the mold, cooling the contact member by blowing air onto the contact member between the optical element and the mold using an air gun, or using a water tank for heating and cooling. A method of applying temperature changes to the adhered body by means such as alternately immersing it in a water tank and forming it into a type Ia by utilizing the difference in expansion coefficient or contraction rate between the mold and the optical element, and applying ultrasonic vibration to the mold or the optical element. A method of applying and releasing the mold is known.

However, it is difficult to apply these conventional mold release methods to molding an elastic body used in a variable focus optical element.

That is, in the method of driving a 7-shaped wedge into the contact surface between the mold and the optical element, there is a problem in that the optical properties of the optical element are significantly impaired because scratches are likely to occur on the surface of the mold or the optical surface of the elastic body. There is.

In addition, the method of blowing air onto the mold and optical element in close contact with an air gun has poor cooling efficiency, which tends to result in incomplete mold release; In the method of heating and releasing from the mold, not only is it necessary to repeatedly perform heating or cooling operations to provide a temperature difference that allows for reliable mold release, but also the elastic material optics due to thermal expansion or thermal contraction during heating or cooling is required. Surface deformation is inevitable.

Furthermore, in the mold release method using ultrasonic vibrations, the ultrasonic vibrations are absorbed by the elastic bodies that make up the optical element, so not only is it difficult to produce a mold release effect, but also the absorption of the ultrasonic vibrations is difficult. This causes a problem in that the temperature of the elastic body increases and thermal deformation of one elastic body tends to occur.

The main object of the present invention is to eliminate the drawbacks of the above-mentioned mold release method and to reliably release the elastic body after molding from the mold while suppressing the deterioration of molding accuracy during mold release. Accordingly, an object of the present invention is to provide a method for manufacturing a variable focus optical element that can form an I3+1 substance with high precision.

11 11 The optical element manufacturing method of the present invention was developed to achieve the above object, and comprises an elastic body and a relatively hard aperture member having an opening and in contact with the elastic body. Nari 1
When manufacturing an optical element that makes it possible to change the shape of the optical surface of the elastic body (opening surface) exposed from the opening by deforming the elastic body, an elastic material is injected onto the molding surface of the mold. and releasing the elastic body from the mold by injecting gas into the interface between the molding surface of the mold and the elastic body through a gas passage provided in at least one of the mold or the elastic body. It is characterized by consisting of a process.

In the manufacturing method of the present invention, the gas injected into the interface (close contact surface) between the elastic body and the mold after molding quickly diffuses into the fine gap between the elastic body and the mold, and the pressure of this gas Based on l
Since a uniform release promoting force acts along the surface of the 311 elastic body, the mold release is performed on the contact surface in such a manner that the elastic body floats from the mold.

Therefore, according to the manufacturing method of the present invention, the deformation of the elastic body during the molding process is suppressed to a minimum, so the elastic body can be molded with high precision. , an optical element with excellent optical properties can be obtained.

Hereinafter, the present invention will be explained in more detail with reference to the drawings as necessary. “%” indicates quantitative ratio in the following descriptions.
"Parts" and "parts" are based on weight unless otherwise specified.

LIJ., 1 FIGS. 1(a) to 1d) are schematic cross-sectional views in the thickness direction of an elastic layer for explaining a typical embodiment of the optical element manufacturing method of the present invention.

Referring to FIG. 1(a), a fitting member l having a pin or wedge shape is inserted through the mold from the molding surface (elastic body contact surface) to the bottom surface (the surface opposite to the molding surface). a cylindrical lower mold 2 made of a material such as metal or glass; a circular bottom plate 3 made of a transparent material such as glass; In the gap formed between the cylindrical side mold 4 that contacts the outer peripheral surface of the
After injecting a raw material for an elastic body made of silicone or the like through an injection port (not shown) provided in the side mold 4, the raw material for the elastic body is hardened with a hardening agent or the like to form a cylindrical shape centered on the optical axis. (casting method).

Then, as shown in FIG. 1(b), by pulling out the fitting member l from the lower die 2, the lower die 2! ! 2, from the bottom surface to the molding surface (i.e., the lower mold 2 and the molded elastic body 5
A gas passage la is formed that penetrates to the interface (with the interface).

Furthermore, as shown in FIG. 2181(c), the jig 6 is attached to the bottom surface of the lower mold 2 so that the gas inlet 6a provided inside the jig 6 communicates with the gas passage 1a, Gas such as air is injected while being pressurized through this gas inlet 6a.

This gas is supplied from the gas inlet 6a to the lower MX! 2, and reaches the interface between the lower mold 2 and the elastic body 5,
It quickly diffuses into minute gaps at the interface (adhesive surface) between the lower mold 2 and the elastic body 5, reduces the adhesive force between the lower mold 2 and the elastic body 5, and promotes their release.

In the embodiment shown in FIG. 1(C), the gas quickly diffuses into the fine gaps between the contact surfaces of the elastic body 5 and the side mold 4, so that the elastic body 5 is separated from the side mold 4. It also promotes mold.

The elastic body 5 formed with high precision by suppressing deformation during mold release in this way is formed into a cylindrical opening member 7 having a circular opening 7a and made of a relatively hard material such as metal or resin.
A variable focus optical element 8 is placed inside the optical element 8. In this optical element 8, the bottom plate 3 is provided so as to be movable in the direction along the optical axis with respect to the aperture member 7.

Although the outline of the optical element manufacturing method of the present invention is as described above, as a method for molding the elastic body 5, in addition to the casting method described above, molding methods known in the field of plastics such as injection method can also be used.

In the present invention, from the viewpoint of molding the elastic body with high precision,
It is preferable to use a plurality of molds (for example, an upper mold and a lower mold) (in the embodiment shown in FIG. 1, the circular bottom plate 3 also serves as the upper mold).

Further, in order to improve the mold releasability of the lower mold 2, the contact surface of the elastic body 5 of the lower mold 2 may be subjected to a mold release treatment such as Teflon coating, if necessary.

Next, the configuration of each part shown in the drawings will be explained.

The lower mold 2 is made of metal (for example, brass), glass, etc.
It is a cylindrical member having a molding surface of a desired shape (the contact surface of the elastic body 5), but below this 71! ! 2 is provided with a gas passage 1a that is formed to be able to fit with the fitting member 1 and that passes through the molding surface and the bottom surface (the surface opposite to the molding surface) of the lower mold 2.

Although it is possible to provide this gas passage 1a so as to penetrate the central part (near the optical axis) of the lower mold 2, the influence on the optical characteristics of the elastic body 5 should be minimized as much as possible.
Alternatively, from the point of view of easily applying mold release promoting force by gas injection to the close contact surface between the elastic body 5 and the side mold 4, it is preferable to penetrate the part near the outer periphery (outer edge part) of the cylindrical lower mold 2. It is preferable to form it so that.

It is preferable to provide a plurality of gas passages 1a from the viewpoint of uniformly applying the releasing force caused by gas injection to the elastic body 5. Also, the gas passages 1a are preferably provided in a plurality of shapes, for example, in a cylindrical shape centered on the optical axis. It may be formed as an opening.

Although the shape of the gas passage 1a is not particularly limited,
It is preferable that the shape is wedge-shaped so that the cross-sectional area becomes relatively small on the molding surface side of the lower mold 2.

The fitting member 1 that fits into the gas passage 1a is made of a material such as metal, ceramics, or plastic, but is preferably made of the same material as the lower mold 2.

In the present invention, as the gas supplied to the interface between the elastic body 5 and the lower mold 2 through the gas passage 1a, any substance that is in a gaseous state at the temperature at which the mold release operation is performed (usually room temperature) may be used without particular restriction. However, at this temperature, the elastic body 5. It is preferable to use a gas (eg, air, nitrogen, etc.) that does not readily chemically react with the lower mold 2 and the like.

Such gas is forcibly injected from the bottom side of the lower mold 2 in the gas passage 1a while being pressurized. It is preferable that

Due to this pressurized injection of gas, the surface shape of the elastic body 5 is temporarily slightly deformed, but as the gas diffuses to the interface between the elastic body 5 and the lower mold 2, the elastic body 5 is quickly removed from the lower mold 2. Since the mold is released quickly, it is easy to control this temporary deformation to a small amount within the elastic deformation, and the temporary deformation of the elastic body 5 can be quickly restored. Therefore, the deterioration in molding precision of the elastic body 5 after release due to the pressurized injection of gas as described above does not substantially pose a problem.

The side mold 4, which together with the lower mold 2 described above constitutes a mold for molding the elastic body 5, is a cylindrical member made of the same material as the lower mold 2. ,
It is sufficient if it is provided on at least one side of the side molds 4.

As the material constituting the elastic body 5, any natural or synthetic polymer substance that exhibits elastomer properties at the operating temperature of the optical element 8 can be used without particular limitation.
For example, it is also possible to use a liquid elastic body obtained by dissolving hydrocarbons in aluminum soap (such as aluminum laurate).

The material constituting the elastic body 5 is 350 nm-t'8
Those having a spectral transmittance of 0% or more and 92% or more in the 500 to 700 nm region, and an elastic modulus of 5XIO2 dyne/cm2 or more and 1X10@dyne/am2 or less are preferably used. When using multiple materials with different elastic moduli selected from this range (for example, see Figure 2 (a) described below).
), two elastic bodies R51 and 52
And the product W! 1 elastic body 54)) The ratio (E 1 / E 2 ) of the elastic modulus (E, ) of the elastic body 51 and the elastic modulus (E2) of the 1 elastic body 52 is (although it varies depending on the thickness of each layer). ) is preferably selected in the range of 2 to 10,000.

Such an elastic body is used when the optical element obtained by the present invention is used as a lens.

It is preferable to use a material with high transparency (at least for light of the wavelength used).

In the present invention, for example, the following elastic materials are used.

(a) Diene rubbers For example, diene polymers such as butadiene and isoprene, diene-vinyl copolymers such as nitrile rubber and acrylic rubber.

(b) Ethylene copolymer selected from α-olefins, dienes, polar monosubstituted vinyl compounds (acrylic acids, methacrylic acids, styrene, vinyl chloride, vinyl ethers, etc.), di-substituted vinyl compounds (maleic acids), etc. A copolymer of 1, 11 or several kinds of compounds obtained by the above-mentioned methods and ethylene (these ethylene-based copolymers have the crystallinity of ethylene significantly reduced or eliminated).

(c) Olefin rubber such as polyisobutyne, atactic polypropylene, polyvinyl chloride (mixed with a relatively large amount of plasticizer), a copolymer consisting of two or more heptamers of acrylic acid or acrylic ester; A copolymer consisting of two or more acrylic acid derivatives (containing water or a high boiling point solvent).

(iv) Other rubbers, such as silicone polymers (dimethyl silicone polymer, diphenyl dimethyl silicone polymer, etc.), phosphazene polymers.

The elastic materials listed above are crosslinked as necessary; for example, by controlling the degree of crosslinking, the elastic modulus E can be changed. This crosslinking may be carried out using, for example, a crosslinking agent made of sulfur, peroxide, or the like.

In the present invention, various elastomers such as those described above are used as the material constituting the elastic body 5. Silicone rubber, ethylene-propylene-genter polymer and the like are particularly preferably used from the viewpoint of easy formation of the body.

Referring to FIG. 1(d), the opening member 7 that accommodates the elastic body 5 described above is a plate made of a relatively hard material such as metal, glass, or resin, preferably having a thickness of about 0.1 to 10 a+m. It is formed into a cylindrical shape having a circular opening 7&.

This opening member 7 is preferably made of an opaque material.

The circular bottom plate 3 that holds the body 5 together with the opening member 7 described above is made of a transparent and relatively hard material such as glass or resin, and preferably has a thickness of about 0.1 to 5 mm. .

The optical element 8 includes the elastic body 5 as described above and the aperture member 7.
and a bottom plate 3, and the entire optical element 8 is shown in FIG.
Although it is formed in a cylindrical shape as shown in d), in the present invention, for example, an optical element may be constructed using an elastic body formed in a rectangular parallelepiped shape and a rectangular parallelepiped opening member having a rectangular opening. good.

The rectangular aperture surface of such an optical element can be used as a cylindrical lens, a toric lens, or the like.

It is also possible to use the opening surface 5a of the elastic body 5 as a reflective surface by depositing metal on the opening surface 5a. In such embodiments, l51Il
The material constituting the elastic body does not need to be transparent, and a filler such as metal powder may be dispersed in the elastic body.

Next, a method of using the optical element 8 obtained by the manufacturing method of the present invention will be explained with reference to FIGS. 1(d) and 1(e).

Figure 1(d) shows its initial state! As shown in FIG. 1(e), pressure is applied to the bottom plate 3 from below in the drawing to deform the elastic body 5 under pressure. Then, in response to the magnitude of this pressure, the opening surface 5a of the elastic body 5 closes the opening 7a of the opening member 7.
The convex lens shape of the opening surface 5a can be reversibly changed by controlling the magnitude of the pressure applied to the 6 elastic bodies 5 protruding from the 6 elastic bodies 5 in a convex lens shape.
A desired focal length can be obtained using this optical element 8.

On the other hand, when negative pressure is applied to the elastic body 5, contrary to the above, the opening surface 5a of the elastic body 5 gives a reversibly changeable concave lens shape (not shown).

As described above, how the opening surface 5a of the elastic body 2 changes when the elastic body 5 is deformed can be analyzed using, for example, a structural analysis program based on the finite element method.

In the above, the embodiment of forming the optical element 8 (FIG. 1(d)) having the elastic body 5 made of a single layer by the manufacturing method of the present invention has been described. An optical element 8a having a laminated elastic body 54 as shown in Figure (a) may be formed.

The laminated elastic body 54 includes a first elastic layer 51 having a relatively large elastic modulus and a second elastic layer 5 having a relatively small elastic modulus from the opening surface 51a side along the optical axis direction.
For example, as shown in FIG. 2(b), the first elastic layer 51 is formed using an upper mold 21, a lower mold 22, and a side mold 23. , after separating the upper mold 21 from the first elastic layer 51 as shown in FIG. 2(c),
As shown in FIG. 2(d), the bottom plate 3 and the first elastic layer 5
1 and the side mold 23 by forming the second elastic layer 52.

1 like this! When forming the LN elastic body 54,
The aspect of the invention in which gas is injected into the interface between the upper mold 21 and the first elastic layer 51 will be described in some detail below.

That is, as shown in FIG. 3(a), the cylindrical upper y! held by the upper die fixing holder 21a! 1i, 21 and
A cylindrical lower mold 2 held by a lower mold fixing holder 22a
A cylindrical side mold 23 is arranged so as to face the cylindrical lower mold fixing holder 22a with a fixed interval, and is in contact with the outer peripheral surface of the cylindrical lower mold fixing holder 22a.
A cylindrical jig z for injecting the elastic raw material is mounted on the upper side of the drawing (the surface opposite to the surface facing the upper die 21 of the holder 21a).
A cylindrical side mold 25 is arranged so as to contact the outer circumferential surface of the mold 4. The upper mold 21 and the upper mold holder 21a are connected from the bottom surface of the upper mold holder 21a (the surface opposite to the surface facing the upper mold 21 of the holder) to the molding surface of the upper mold 21 (the surface facing the elastic body).
A gas passage 11a is formed that reaches the gas passage 1.
A pin or wedge-shaped fitting member 11 is fitted into 1a.

Through the raw material injection port 24a formed in the raw material injection jig 24 so as to communicate with the gap between the upper mold fixing holder 21a and the side mold 23 and the gap between the upper fi 21 and the lower mold 22,
After a raw material (such as silicone) for the first elastic layer 51 is injected into the gap between the upper mold 21 and the lower mold 22, the elastic raw material is hardened using a hardening agent or the like to form the first elastic layer 51.

Next, as shown in FIG. 3(b), the jig 24, the side mold 2
5, the upper mold holder 2 is removed by pulling out the fitting member 11 from the upper mold 21 and the upper mold holder 21a.
1a to the molding surface of the upper mold 21 (i.e., the upper mold 21
and the first elastic layer 51).
form.

Furthermore, as shown in FIG. 3(c), the jig 6 is attached to the bottom surface of the upper mold holder 21a so that the gas injection port 6a formed inside the gas injection jig 6 communicates with the gas passage 11a. When the gas, such as air, is pressurized and injected through the gas inlet 6a, the action of this gas causes (Fig. 1 (c)
)), the #-shape at the interface between the upper mold 21 and the first elastic layer 51 is promoted.

After forming the first elastic layer 51 with high accuracy in this manner, the lower mold z2 having the 1911 elastic layer formed on the molding surface is used to form the first elastic layer 51 in FIGS. 1(a) to 1. (d)
By a method similar to that shown in .

A second elastic body layer 52 is laminated on the first elastic body R51 to form a laminated elastic body 54, and this laminated elastic body 54 is attached to the opening member 7.
The optical element 8a shown in FIG. 2(a) may be obtained by housing the optical element 8a in FIG.

In this optical element 8a, by balancing the deformation of the first elastic layer 51 and the second elastic layer 52 constituting the laminated elastic body 54, it is possible to obtain preferable deformation characteristics of the laminated elastic body 54 as a whole. , for example, the aperture surface 51
It becomes possible to deform a while keeping it in a desirable shape such as a spherical surface. Note that the mode of deformation of the opening surface 51a of the laminated elastic body 54 may be controlled by giving an appropriate distribution to the thickness of the first elastic body layer 510 in the optical axis direction.

The shape change of the laminated elastic body 54 can be easily analyzed using a structural analysis program based on the finite element method, as in the case of the single-layer elastic body 5 described above.

In addition, when forming the laminated elastic body 54 used for this optical element 8a, the second elastic body layer 52 (the surface of this elastic body layer 52 is often more adhesive than the surface of the first elastic body layer 51). In consideration of the mold releasability from the side mold 23, the elastic layer is formed in such a manner that only the first elastic layer 51 comes into contact with the side mold 23, as shown in FIG. 4 (gas passages are not shown). A body layer 51 may also be formed.

The embodiments of the present invention for forming the optical elements 8 to 8a as shown in FIG. 1(d) and FIG. 2(a) have been described above, but according to the manufacturing method of the present invention,
Optical elements (8b to 8g) having other configurations as shown in FIGS. 5 to 10, which are schematic cross-sectional views in the thickness direction of the elastic layer, can also be suitably manufactured.

FIG. 5(a) shows an optical system in which a single-layer elastic body 5 with a flat aperture surface 5a is held between a circular aperture plate 71 and a circular bottom plate 3, and these are accommodated in a cylindrical side wall 9. Element 8
FIG. 5(b) shows a state in which the aperture plate 71 is moved along the optical axis direction in a direction to press the elastic body 5, and the aperture surface 5a of the elastic body 5 is made to protrude in the shape of a convex lens. .

FIG. 6 shows an optical element 8c using a laminated i-shaped body 54 with a flat opening surface 51a in place of the single-layer elastic body 5 of FIG. 5(a), and FIG. An optical element 8d is shown in which a one-circle spacer plate 71 is used in place of the cylindrical opening member 7 of FIG.

FIG. 8 shows the first elastic layer 51 (elastic modulus El) and the second elastic layer 52 (elastic modulus E2) from the top of the drawing along the optical axis.
) and a third elastic layer 53 (modulus of elasticity E3) of 81 layers, and a plurality of aperture plates (71
In the optical element 8e of FIG.
However, El and E3 may not be equal, and at least one of the aperture plates 71 and 72 is provided movably along the side wall 9.

FIG. 9 shows an optical element 8f in which an aperture plate 71 is provided on the surface of the second elastic body 52 inside the laminated elastic body 54 (the aperture plate 71 is bonded to the first and second elastic body layers). , FIG. 10 shows a structure in which a cylindrical side wall 9 made of a piezoelectric element is provided on the outer periphery of a cylindrical laminated elastic body 55, and the inner diameter of the side wall 9 is changed by controlling the voltage applied to this side wall 9. 8g of optical elements in which the laminated elastic body 55 is deformed by
shows.

In the above, y! An embodiment in which a gas passage is provided in the mold in order to inject gas into the interface between the mold and the elastic body has been described.1 In the present invention, the connection between the mold and the elastic body is made through the gas passage provided on the side of the elastic body to be molded. Gas may be injected into the interface, and gas passages may be provided in both the mold and the elastic body.

When providing a gas passage in the elastic body, for example, the elastic body raw material is injected into the gap where the elastic body is to be formed, with a fitting member such as a bottle or a rod inserted.

After the elastic body is hardened, the fitting member is pulled out from the elastic body to form a gas passage.

When forming a gas passage on the elastic body side in this way, it is preferable to provide the gas passage so as to penetrate through a portion of the elastic body through which light rays do not pass (for example, the outer edge of a cylindrical elastic body).

As described above, the present invention provides an optical element that molds an elastic body using a mold and then releases the elastic body from the mold by injecting gas into the interface between the mold and the elastic body. A manufacturing method is provided.

According to the manufacturing method of the present invention, since the mechanical and thermal deformation of the elastic body is suppressed when the elastic body is released from the mold, the elastic body can be formed with high precision. , an optical element with excellent optical precision can be obtained.

[Brief explanation of drawings]

1 to 10 are schematic cross-sectional views of the elastic layer as viewed in the thickness direction, and FIGS. 1(a) to 1e),
Figure 2 (a) to d), Figure 3 (a) to C)
, and FIG. 4 are diagrams for explaining the optical element manufacturing method of the present invention, and FIGS. 5 to 10 are diagrams showing other embodiments of the optical element obtained by the manufacturing method of the present invention. l...Fitting member 1a...Gas passage 2...Lower die 3...Bottom plate 4...Side die 5...Elastic body 51...First elastic layer 52...No. 2 Elastic layer 6...Jig 6a...Gas inlet a...Aperture member 71.72...Aperture plate 8...Optical element 9...Side wall ΩJ: Fig. 1(a) , (b) , (C) Figure 1 (a) (b) Figure 1 (c) (d) (e) Figure 2 (b) (ci) Figure 3 (b) (c) Figure S h (b)

Claims (1)

[Claims] Consisting of an elastic body and a relatively hard opening member having an opening and in contact with the elastic body, the shape of the optical surface of the elastic body exposed from the opening is changed by deforming the elastic body. When manufacturing an optical element that makes it possible to A method for manufacturing an optical element, comprising the steps of: injecting gas into the interface between the elastic body and the elastic body, and releasing the elastic body from the mold.