JP3239598B2 - Method for manufacturing diffractive optical element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a diffractive optical element in which a layer of an active energy ray-curable resin is closely formed by molding a base material such as glass using a molding die.

[0002]

2. Description of the Related Art In recent years, a technique has been developed in which an active energy ray-curable resin is molded in close contact with a molding surface of a base material such as glass using a molding die having a predetermined surface shape. It is used as a method for producing composite molded articles such as lattices. This manufacturing method is described in, for example, JP-A-3-79314 and JP-A-3-19710.
No. 6, JP-A-4-144718 and the like.

FIGS. 10 (a) to 10 (d) are views showing a conventional method for manufacturing a diffraction grating. First, as shown in FIG. An active energy ray-curable resin 23 typified by a cured resin is dropped, and then another base material 21 made of a glass plate or the like is brought into contact with the droplet of the dropped resin as shown in FIG.
Next, mold clamping is performed using a jig or the like (not shown) so that the resin thickness becomes constant as shown in FIG. After the molding, a composite diffraction grating as shown in FIG.

[0004]

However, in the above-mentioned conventional manufacturing process, bubbles 24 may be generated at the moment when the base material 21 and the resin droplet 23 shown in FIG. That is, the contact process between the apex of the droplet 23 and the plane of the base material 21 is a point contact in theory, but in reality, the droplet spreads over time immediately after dropping, and the apex becomes flat, and the apex becomes flat. The contact with the material 21 is a face-to-face contact, and there are many opportunities to generate bubbles.

In the process of spreading the liquid resin 23 from FIG. 10 (b) to FIG. 10 (c), when the molding die 22 is a diffraction grating or a Fresnel lens, the molding surface of the molding die 22 is not formed. Since the resin liquid spreads on the uneven surface, bubbles 24 are easily generated. In addition, even when the surface of the aspherical lens or the like is flat, if the resin liquid spreads at a high speed, bubbles 24 may be generated due to defects or dust on the surface of the mold 22. In particular, when the composite molded article is an optical element, the air bubbles cause light scattering and have been a major problem in function.

In order to solve this problem, Japanese Patent Application Laid-Open No. 4-46303 discloses a method of removing a generated bubble by placing a molded product in a vacuum vessel 25 as shown in FIG. I have. However, in this method, the molded article must be taken in and out of the vacuum vessel every molding, which is troublesome and time-consuming. In addition, when actually evacuated and viewed, there is a problem that the air bubbles are contained and the resin liquid protrudes from the end of the mold and drips, thereby causing stains.

The present invention has solved the above problems,
An object is to obtain a method for manufacturing a diffractive optical element.

In the method of manufacturing a diffractive optical element according to the first aspect of the present invention, a grating-shaped portion for forming a diffraction grating is formed on a surface of a mold, and a base material is arranged facing the mold. The active energy ray-curable resin is placed between the molding die and the base material at a distance at which the active energy ray-curable resin flows by capillary action, and the active energy ray-curable resin forms a grid on the outer peripheral surface of the base material by the surface tension action. Manufacturing a diffractive optical element by forming a chamfer in which the thickness in the vicinity of the outer peripheral portion of the space gradually increases so as to be drawn into the shape portion, and irradiating the active energy ray-curable resin in the lattice shape portion with active energy rays. It is characterized by.

[0009]

[0010]

[0011]

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a diffraction grating as a composite molded article according to the present invention will be described below with reference to FIGS.

First, a molding surface of a base material 1 made of a glass plate for supporting a molding resin layer and a surface of a molding die 2 having a diffraction grating shape on its surface are spaced apart from each other in FIG. Face each other.

Here, the base material 1 has a desired component shape, and may be a transparent material in the case of a transmission type diffraction grating, and may be either transparent or opaque in the case of a reflection type diffraction grating. The material is not limited to glass, but may be any material such as metal, plastic, and ceramic. Further, the base material 1 may be a material which has been washed in advance, and the surface on which the resin adheres may be subjected to a silane coupling treatment or the like for promoting the adhesion.

The mold 2 is made of, for example, a material such as quartz, silicon, or metal, and is formed by processing such as photolithography. Although shown in a simple shape in FIG. 1, a base material holding means 4 for supporting the base material 1 is provided.

Next, as shown in FIG. 1B, the base material 1 is made to approach the forming die 2 by the base material holding means 4, and the distance between the forming die 2 and the base material 1 is adjusted to the thickness of the target resin layer. (First step).

Next, as shown in FIG. 1 (c), the active mold beam-curable resin liquid 3 (hereinafter abbreviated as "resin liquid 3") is opposed by a dispenser 5 or the like to the mold 2 and the base material 1. Is gradually supplied from a part of the periphery of the space.
The active energy ray-curable resin used here may be any one such as an ultraviolet ray-curable resin, a visible ray-curable resin, and an X-ray-curable resin. It's easy to do. As the resin, a resin such as an acrylic resin, an epoxy resin, or an thiol resin is used. Among them, an acrylic ultraviolet curable resin is preferable because it has a short curing time and good environmental durability.

The dispenser 5 used here may be of any type, such as a gas pressure type, a mechanical pressure type, a rotary pump type, a gear pump type, and may simply be a dropper or a syringe.

Resin liquid 3 supplied from dispenser 5
Is only dripped onto a part of the peripheral end of the space between the base material 1 and the molding die 2 facing each other, and it is not necessary to apply pressure as in injection molding. Resin liquid 3 entering from the end of the space
Naturally fills the space from the state shown in FIG. 1 (c) to the state shown in FIG. 1 (d) under the atmospheric pressure by capillary action (second step).

Therefore, the thickness of the resin layer at this time needs to be set to a thickness at which the above-mentioned capillary phenomenon can occur. For example, in the case of an acrylic ultraviolet curable resin having a viscosity of 50 to 10000 cps, the resin thickness is set to 0. 0.3 mm or less is preferable, and if possible, 0.1 mm or less is optimal. That is, when the thickness of the resin is 0.3 mm or more, the capillary phenomenon hardly occurs, and the filling speed of the resin liquid into the space is too slow or the speed becomes zero and the filling may not be possible.

The positional relationship between the dispenser 5 and the space described above is, for example, as shown in FIG. 2, if the resin liquid 3 is in a fan-like shape due to the capillary phenomenon as shown by an arrow in FIG. It is efficient because it permeates in a short time.
However, the contact position of the dispenser 5 is not limited to the above, but may be a corner. Also, the number of dispensers 5 is not limited to one, and two or more dispensers 5 may be used to efficiently supply the resin liquid 3 from two or more places. good. It is desirable that these are appropriately determined by a combination of the shape and mold of the desired composite molded article, the surface tension of the base material, the viscosity and the surface tension of the resin used, and the like.

It is desirable that the filling amount of the resin is slightly excessive to the space volume. On the other hand, if the amount of the resin is slightly insufficient, it is likely to cause a short-circuit (partially insufficient filling) of the molded product.

As described above, by filling the resin liquid 3 using a natural phenomenon called a capillary phenomenon, even if the surface of the mold has irregularities such as a diffraction grating, bubbles which have been a problem in the past can be removed. It is possible to easily supply the resin liquid 3 without generation.

Next, as shown in FIG. 1E, the filled resin liquid 3 is cured by irradiating active energy hν through the base material 1 or the molding die 2, and the base material 1 and the resin layer 3a are cured. (3rd step), the integrated base material 1 and resin layer 3a
By peeling off from the mold 2 (fourth step), FIG.
A composite diffraction grating as shown in (f) is obtained.

As described above, the resin liquid 3 is formed by utilizing the capillary phenomenon.
When the thickness around the space formed by the base material 1 and the molding die 2 is constant as shown in FIG. 4, the resin liquid 3 is supplied somewhat slightly more than the space volume.
The peripheral shape becomes a shape protruding due to surface tension. Therefore, the molded product is as shown in FIG. 1 (f), and depending on the purpose of use, the resin protruding from the side surface may be obstructed such that the side surface of the molded product cannot be used as an assembly reference surface. On the other hand, if the resin liquid 3 is slightly short of the space volume, uneven filling may be caused.

Therefore, it is desirable to gradually increase the thickness in the vicinity of the outer peripheral portion of the space, and to provide a chamfered portion 6 having a size larger than the thickness of the resin layer 3a over the entire peripheral portion of the base material as shown in FIG. As a result, the resin liquid 3 in the peripheral portion is drawn into the space by the surface tension corresponding to the change in the thickness of the space as shown in the figure, and the molded product is moved from the end face of the base material 1 as shown in FIG. A composite diffraction grating having a good appearance can be obtained without protruding the resin layer 3a.

As a method of supplying the active energy ray-curable resin, a liquid reservoir 8 of the active energy ray-curable resin liquid 3 is provided in contact with the outer peripheral portion of the space as a method different from the method using the dispenser 5 described above. That is, FIG.
Also, as shown in FIG. 7C, at least a part of the molding surface of the molding die 2 is made wider than the base material 1, and as shown in FIG. The liquid pool 8 of the cured resin liquid is set so as to be in contact with the space. From this state, the resin liquid 3 gradually fills the space naturally by the capillary phenomenon as shown in FIG. 7B, so that the liquid can be easily supplied and no bubbles are mixed, which is preferable.

As a similar method, as shown in FIG. 8, a molding die 2 and a base material 1 are placed vertically facing each other, and a liquid droplet is placed on the upper end of the molding die 2 and the base material 1 facing each other. The reservoir 8 may be provided and filled by capillary action as described above. Further, as shown in FIG. 9, the mold 2 and the base material 1 are placed vertically facing each other, and the resin liquid 3 is stored in the container 9. The filling may be performed by using the phenomenon and gravity, and after the filling, the mold 2 and the base material 1 may be removed from the container 9 and the upper resin stain may be wiped off.

The method of manufacturing a diffraction grating has been described above. However, the integrated molded product according to the manufacturing method of the present invention is not limited to this, and optical elements such as Fresnel lenses and aspheric lenses, and other composite precision molded products can be used. It can also be applied to the manufacture of goods.

Example 1. A base material of 20 mm square and 2 mm thick soda lime glass and a 20 mm x 20 mm x 1 mm outer diameter and a diffraction grating in a central 16 mm square, the pitch of the diffraction grating being 4 μm A diffraction grating mold made of crystalline silicon having a protrusion width of 2 μm, a recess width of 2 μm, and a groove depth of 1 μm was prepared.

Next, the molding surface side of the base material is treated in advance with a silane coupling agent (γ-acryloylpropyltrimethoxysilane), and the side surface of the base material is held by a jig, so that the molding die and the outer peripheral portion match. A polyester film having a width of 5 mm and a thickness of 50 μm is placed at two locations around the mold, and a base material is placed on the polyester film. After fixing, the polyester film is pulled out, and the base material is opposed to the mold. The thickness of the space at the interval is set to 50 μm.

Next, a bifunctional urethane acrylate (Toa Gosei Co., Ltd.,
-1200) 30 μl of a mixture of 30 parts by weight, 70 parts by weight of cyclohexyl methacrylate, and 2 parts by weight of 1-hydroxycyclohexyl phenyl ketone is gradually dropped into the end of the space for about 1 minute, and left for 1 minute. Thereby, filling of the space with the resin was completed.

After that, the resin is irradiated with ultraviolet light of a 200 W mercury xenon lamp for 2 minutes from above to cure the resin.
Release was performed. No bubbles were observed inside the resin layer of the molded product, and a good molded product was obtained.

Example 2 A 20 mm square, 2 mm thick,
A base material of a soda lime glass having a chamfer of 0.5 mm on four sides on one side and a molding die similar to that of Example 1 was prepared.

Next, the surface having the chamfered portion of the base material is treated in advance with a silane coupling agent in the same manner as in Example 1, and the space between the base material and the mold surface is formed in the same manner as in Example 1. The interval was set to 100 μm.

Next, a bifunctional epoxy acrylate (Kyoeisha fats and oils,
3002A) A 50 μl mixture of 40 parts by weight, 60 parts by weight of isobornyl methacrylate, and 2 parts by weight of 1-hydroxycyclohexyl phenyl ketone was filled in the above space in the same manner as in Example 1.

After that, the resin was irradiated with ultraviolet rays from a 200 W mercury xenon lamp for 2 minutes from above to cure the resin.
Release was performed. No air bubbles were observed inside the resin layer of the molded product, and the four sides of the molded product were quite smooth, and a good molded product was obtained in which the protrusion of the resin was suppressed in the chamfered portion.

Embodiment 3 FIG. Base material 1 similar to Example 1 above
And the external dimensions are 26 × 26 × 1 mm and the others are Example 1.
A completely same mold was prepared.

Next, the base material was previously treated with a silane coupling agent in the same manner as in Example 1, and the space between the base material and the mold surface was set to 20 μm in the same manner as in Example 1.

Next, as shown in FIG. 7C, 15 μl of the same ultraviolet curable resin as in Example 1 was dropped by contacting a part of the space with a microsyringe and left for about 1 minute. The resin was filled over the entire space. Thereafter, the resin was irradiated with ultraviolet light from a 200 W mercury xenon lamp for 2 minutes from above to cure the resin and then released.
No bubbles were observed inside the resin layer of the molded product, and a good molded product was obtained.

Comparative Example 1 A base material and a molding die similar to those in Example 1 were prepared.

Next, the base material was previously treated with a silane coupling agent in the same manner as in Example 1, and 30 μl of a mixed liquid of an ultraviolet-curable resin similar to that in Example 1 was dropped on the center of the above-mentioned molding die. The treated surface side of the material is gradually brought into contact with the resin liquid,
As shown in FIG. 10 (c), the mold was clamped by a jig or the like (not shown) so that the thickness of the resin layer was 50 μm while the outer periphery of the mold and the base material were aligned.

After that, the resin was irradiated with ultraviolet rays from a 200 W mercury xenon lamp for 2 minutes from above to cure the resin.
Release was performed. The releasability and surface transferability were good,
Many bubbles of 5 to 20 μm were confirmed inside the molded resin layer.

As described above, according to the first aspect of the present invention,
A diffractive optical element having no appearance of bubbles and a good appearance can be obtained.

[0045]

[0046]

[0047]

[Brief description of the drawings]

FIG. 1 is a process chart showing a method for manufacturing a diffractive optical element of the present invention.

FIG. 2 is a perspective view showing one step of a method for manufacturing a diffractive optical element of the present invention.

FIG. 3 is a plan view showing one step of the method for manufacturing a diffractive optical element of the present invention.

FIG. 4 is a front view showing one step of a method for manufacturing a diffractive optical element of the present invention.

FIG. 5 is a front view showing one step of a method of manufacturing another diffractive optical element according to the present invention.

FIG. 6 is a front view of the diffractive optical element obtained by the manufacturing method of FIG. 5;

FIG. 7 is a process chart for explaining a method of filling a resin liquid in another method of manufacturing a diffractive optical element according to the present invention.

FIG. 8 is a front view illustrating another way of filling the resin liquid.

FIG. 9 is a front view illustrating another way of filling the resin liquid.

FIG. 10 is a process chart showing a conventional method for producing a composite molded article.

FIG. 11 is a front view showing one step of another conventional method for producing a composite molded article.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base material 2 Mold 3 Active energy ray hardening resin 6 Chamfered part 7 Resin layer peripheral part 8 Liquid pool

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 39/00-39/44 B29C 35/00-35/18 G02B 5/00-5/32

Claims (1)

(57) [Claims] 1. A mold for forming a diffraction grating is formed on a surface of a mold, and a base material is arranged to face the mold. Active energy is applied between the mold and the base material. At a distance where the line-curable resin flows by capillary action, the outer peripheral surface of the base material is positioned near the outer peripheral portion of the space so that the active energy ray-curable resin is drawn into the lattice-shaped portion of the mold by the action of surface tension. Gradually widens
A method for manufacturing a diffractive optical element, comprising: forming a chamfered portion, and irradiating active energy ray-curable resin in the lattice-shaped portion with active energy rays to manufacture a diffractive optical element.