JP2003307608A - Method for manufacturing diffraction optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a diffraction optical element which can form uneven patterns in an accurate shape on the surface of an optical material made of resin. <P>SOLUTION: The method for manufacturing the diffraction optical element having the groove-shaped uneven pattern 13 formed on the border surface between two layers 11 and 12 made of different optical materials includes a forming process of forming the uneven pattern on the surface of the layer 11 made of the specified optical material, coating processes (a) to (b) of coating the uneven pattern with an uncured body 12a of a resin-made optical material having a different refractive index, and a curing process of curing the uncured body, and is characterized in that the uncured body is spread out along the direction of the groove in the coating process when applied. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a phase-type diffractive optical element that exhibits various optical functions by utilizing the diffraction phenomenon of light.

[0002]

2. Description of the Related Art Diffractive optical elements utilize various phenomena such as lens function (condensing and diverging), branching / multiplexing function, light intensity distribution conversion function, wavelength filter function, and spectral function by utilizing the diffraction phenomenon of light. It is known as an optical element that exhibits an optical function.
Incidentally, a diffractive optical element having a spectral function is also called a grating, and a diffractive optical element having a lens function is also called a zone plate.

Further, the phase type diffractive optical element is one in which a groove-shaped concavo-convex pattern is formed on the surface of an optical material (made of glass or resin), and its optical function is determined by the shape of the concavo-convex pattern. There is. For example, in the case of a grating such as a blazed grating, the concavo-convex pattern is a linear shape with equal intervals. In the case of a zone plate, the concavo-convex pattern is concentric.

[0004]

However, when an attempt is made to manufacture the above-mentioned phase type diffractive optical element with an optical material made of resin, the shape of the concavo-convex pattern formed on the surface of the optical material made of resin is inaccurate. Sometimes became. In particular, the shape of the top of the uneven pattern tends to be inaccurate.
If the shape of the concavo-convex pattern is inaccurate, the manufactured diffractive optical element cannot exert sufficient optical function.

An object of the present invention is to provide a method of manufacturing a diffractive optical element capable of forming a concavo-convex pattern having an accurate shape on the surface of an optical material made of resin.

[0006]

According to a first aspect of the present invention, there is provided a method of manufacturing a diffractive optical element in which a groove-shaped concavo-convex pattern is formed on a boundary surface between two layers made of different optical materials. Forming step of forming the concave-convex pattern on the surface of the layer made of an optical material, and applying step of applying an uncured resin optical material having a different refractive index from the predetermined optical material on the concave-convex pattern And a curing step of curing the uncured material, and in the applying step, the uncured material is spread along the groove direction of the uneven pattern when the uncured material is applied.

According to a second aspect of the present invention, there is provided a method of manufacturing a diffractive optical element in which a groove-shaped concave-convex pattern is formed on the surface of a layer made of a resin-made optical material, which has an inverted shape of the concave-convex pattern. An applying step of applying an uncured material of the optical material to the surface of the mold, a curing step of curing the uncured material, and a peeling step of peeling the cured optical material from the mold, the applying step Then, when applying the uncured material, the uncured material is spread along the groove direction of the inverted shape of the concavo-convex pattern.

According to a third aspect of the present invention, in the method of manufacturing a diffractive optical element according to the second aspect, in the peeling step, the cured optical material is deformed along the groove direction of the concavo-convex pattern. It peels off.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

(First Embodiment) The first embodiment of the present invention is as follows.
It corresponds to claim 1. Diffractive optical element 10 of the first embodiment
As shown in FIGS. 1A and 1B, is composed of a layer 11 made of an optical material made of glass and a layer 12 made of an optical material made of resin. Further, the two adjacent layers 11 and 12 are in close contact with each other, and the groove-shaped uneven pattern 13 is formed on the boundary surface 10a thereof. The uneven pattern 13 is
It is a linear pattern with equal intervals.

Further, the two layers 11 and 12 have different refractive indexes from each other, and both of them are used in a wavelength range of the diffractive optical element 10 (for example, an infrared wavelength range of 1.4 μm to 1.7 μm or 400 n.
It is transparent to light in the visible light range of m to 700 nm). The diffractive optical element 10 of the first embodiment configured as described above uses the concavo-convex pattern 13 to convert the transmitted light into the 0th order light,
It is an element that divides into primary light, secondary light, ....

Next, a method of manufacturing the diffractive optical element 10 of the first embodiment will be described. The diffractive optical element 10 is generally manufactured according to the following procedure << 11 >> → << 12 >> → << 13 >>. The procedure << 11 >> forms the uneven pattern 13 on the surface of the layer 11. In the procedure << 12 >>, an uncured product of a resin-made optical material (optical resin) which is a material of the layer 12 is applied onto the uneven pattern 13. Procedure << 13 >>
The applied uncured material is cured.

First, in the procedure << 11 >>, the concavo-convex pattern 13 is formed by processing the optical material (optical glass) made of glass constituting the layer 11. As the processing method, for example, any of the following three methods (A) to (C) can be used. (A) Layer 11 by machining such as cutting or grinding
Is directly processed to form an uneven pattern 13 on the surface.
(B) A finely processed resist layer is formed on the layer 11 by photolithography, and then the pattern shape of the resist layer is transferred to optical glass by ion etching.
The uneven pattern 13 is formed on the surface of the layer 11.

(C) Layer 11 using a mold such as a mold
Then, the pattern shape is transferred to and the uneven pattern 13 is formed on the surface (glass molding method). In this method, when a low melting point glass having a yield point of 500 ° C. or lower is used as the optical glass used for the layer 11, the temperature at the time of molding can be lowered and the restriction on the heat resistance of the mold can be relaxed. Therefore, a metal material that can be easily processed by cutting or grinding can be used as the material of the mold.

As the optical glass constituting the layer 11,
Is mainly composed of SiO₂-PbO-R₂O, SiO₂-PbO-
BaO-R₂O, SiO₂-B₂O₃-PbO-BaO, (Si
O₂) -B₂O₃-La₂O₃-PbO-Al₂O₃, (SiO₂) -B
₂O₃-La₂O₃-PbO-RO, (SiO₂) -B₂O₃-La₂
O₃-ZnO-TiO₂-ZrO₂, B₂O₃-La₂O₃-Gd₂
O₃-Y₂O₃-Ta₂O_Five, SiO₂-TiO₂-KF, SiO₂
-B₂O₃-R₂O-Sb₂O₃, B ₂O₃-(Al₂O₃) -PbO-
So-called flint glass such as RO, and the main component is SiO₂-
RO-R₂O, SiO₂-BaO-R₂O, SiO₂-B₂O₃-
BaO, (SiO₂) -B₂O₃-La₂O₃-RO-ZrO₂,
(SiO₂) -B₂O₃-La₂O₃-ZnO-Nb₂O_Five, B ₂O₃-
La₂O₃-Gd₂O₃-Y₂O₃, SiO₂-B₂O₃-R₂OB
aO, P₂O_Five-(Al ₂O₃-B₂O₃) -R₂O-BaO, Si
O₂-B₂O₃-K₂O-KF, SiO₂-R₂With O-ZnO, etc.
Various glass materials such as certain crown glass, quartz glass, and fluorspar
A fee can be used.

Next, the procedure << 12 >> will be described. This step << 12 >> is a step of applying an uncured optical resin on the concave-convex pattern 13 formed in the above step << 11 >>. In the first embodiment, as shown in FIGS. 2A and 2B, first, the uncured product 12a of the optical resin is dropped on one end side of the concave / convex pattern 13 in the groove direction. Then, using the flat plate-shaped pressing plate 14, the uncured product 12a is spread to the other end side along the groove direction.

At this time, the uncured material 12a easily flows along the groove direction of the concavo-convex pattern 13 and also enters the fine valley portion 15 (FIG. 2C) of the concavo-convex pattern 13. That is, bubbles do not remain in the valleys 15 of the uneven pattern 13. Finally, the uncured material 12a is filled between the pressing plate 14 and the entire concavo-convex pattern 13 (see FIG. 2).
(state of (d)), the application process of the uncured product 12a is completed.

In the next step << 13 >>, light (for example, ultraviolet rays) is irradiated from the side of the layer 11 or heated in a state after the uncured material 12a is spread (FIG. 2 (d)). Thus, the uncured product 12a is cured. And finally,
The push plate 14 is released (FIG. 2 (e)). As a result, the optical resin layer 12 is formed on the uneven pattern 13, and the diffractive optical element 10 of the first embodiment is completed.

Here, the valley portion 15 (FIG. 2C) of the concavo-convex pattern 13 is the shape of the completed diffractive optical element 10 as viewed from the layer 11 (optical glass) side. It is expressed by pointing. Therefore, when the valley 15 is viewed from the side of the layer 12 (optical resin), it corresponds to the top of the concavo-convex pattern 13. The optical resin forming the layer 12 includes polycarbonate, polystyrene, polymethyl methacrylate, Poly (trifluoroethyl methacrylate), poly (isobutyl methacrylate), poly (methyl acrylate), diethylene glycol bisallyl carbonate, poly (methyl methacrylate), poly (α-bromomethyl acrylate), poly (methacrylic acid) -2,3-dibromopropyl, diallyl phthalate , Polyphenylmethacrylate, polyvinylbenzoate, pentachlorophenylmethacrylate, polychlorostyrene, polyvinylnaphthalene, polyvinylcarbazole, silicone polymers, acrylic resins,
Various resin materials classified into urethane-based resins, epoxy-based resins, ene-thiol-based resins, thiourethane-based resins, and photopolymers can be used.

As described above, in the first embodiment, in manufacturing the diffractive optical element 10, in the step of applying the uncured product 12a of the optical resin on the concave-convex pattern 13, the concave-convex pattern 13 is formed along the groove direction. Since the uncured product 12a is spread out by the uncured product 12a, the uncured product 12a can be spread to every corner of the fine valley portion 15 (FIG. 2C) of the concavo-convex pattern 13.

Therefore, the valley portion 15 of the uneven pattern 13 is formed.
Bubbles remain in the valleys 15 (FIG. 2C) of the uneven pattern 13 regardless of the depth (that is, the lattice height) of FIG. 2C and the viscosity of the uncured product 12a. There is no problem. If air bubbles remain, the layer 1 of the completed diffractive optical element is completed.
Between 1 and 12, an air layer having a different refractive index from the two layers 11 and 12 is included, and the desired performance cannot be obtained.

In the first embodiment, as described above, since the uncured material 12a can be spread to every corner of the fine valley portion 15 (FIG. 2C) of the concavo-convex pattern 13, it is made of an optical resin. The concavo-convex pattern 13 having an accurate shape can be formed on the surface of the layer 12 (the boundary surface 10a with the layer 11).

In particular, the top of the concavo-convex pattern 13 when viewed from the side of the layer 12 made of optical resin (corresponding to the valley 15 in FIG. 2C).
The shape of is also accurate. Therefore, the spectral function of the manufactured diffractive optical element 10 can also exhibit sufficient performance. That is, the diffractive optical element 10 having a highly accurate spectral function can be obtained. In the first embodiment described above, the example in which the layer 11 is made of optical glass has been described, but the layer 11 may be made of optical resin. In this case, the concavo-convex pattern 13 is formed on the surface of the layer 11 by using a mold such as a mold having an inverted shape of the concavo-convex pattern 13 to transfer the pattern shape to the uncured product of the optical resin, and then the uncured product. By curing.

(Second Embodiment) The second embodiment of the present invention is as follows.
It corresponds to claim 2 and claim 3. As shown in FIGS. 3 (a) and 3 (b), the diffractive optical element 20 of the second embodiment is composed of a layer 21 made of a resin-made optical material, and one surface 20a of the layer 21 has a groove-like shape. The uneven pattern 22 is formed. The uneven pattern 22 is a linear pattern with equal intervals.

The surface 20a of the layer 21 is a boundary surface with the surrounding air layer, and the layer 21 and the air layer have different refractive indexes. In addition, the layer 21 is used in the wavelength range of the diffractive optical element 20 (for example, an infrared wavelength range of 1.4 μm to 1.7 μm or 400 n
It is transparent to light in the visible light range of m to 700 nm). The diffractive optical element 20 of the second embodiment configured as described above is an element that divides the transmitted light into 0th-order light, 1st-order light, 2nd-order light, ... By the spectral function of the concavo-convex pattern 22.

Next, a method of manufacturing the diffractive optical element 20 of the second embodiment will be described. The diffractive optical element 20 is generally manufactured according to the following procedure << 21 >> → << 22 >> → << 23 >>. The procedure << 21 >> is a step of applying an uncured product of a resin optical material (optical resin), which is the material of the layer 21, to the surface of the mold having the inverted shape of the concavo-convex pattern 22. The procedure << 22 >> is a step of curing the applied uncured material. In the procedure << 23 >>, the cured optical resin is peeled from the mold.

First, the procedure << 21 >> will be described. This procedure << 21 >> is the same as the procedure << 12 >> in the above-described first embodiment, except that the mold 23 shown in FIG. 4 is used in place of the optical glass layer 11 (FIG. 2). ing. The concavo-convex pattern 24 formed on the surface of the mold 23 corresponds to an inverted shape of the concavo-convex pattern 22 (FIG. 3). In the second embodiment, as shown in FIG. 4A, first, the uncured product 21a of the optical resin is dropped on one end side of the concave / convex pattern 24 of the mold 23 in the groove direction. Then, using the flat plate-shaped pressing plate 25, the uncured product 21a is spread to the other end side along the groove direction.

At this time, the uncured material 21a easily flows along the groove direction of the concavo-convex pattern 24 and also enters the fine valley portion 26 (FIG. 4B) of the concavo-convex pattern 24. That is, bubbles do not remain in the valleys 26 of the uneven pattern 24. Then, finally, the uncured product 21a is filled between the pressing plate 25 and the entire concavo-convex pattern 24, and the application process of the uncured product 21a is completed.

In the next step << 22 >>, after the uncured product 21a is spread out, light (for example, ultraviolet rays) is radiated from the side of the flat plate-shaped pressing plate 25 or it is heated, The cured product 21a is cured. Here, the valley portion 26 (FIG. 4B) of the concave-convex pattern 24 described above means the mold 2
This is expressed by pointing to the shape as viewed from the side of 3. Therefore, when the valley portion 26 is viewed from the side of the cured optical resin (layer 21), the concavo-convex pattern 22 (FIG. 3A)
Equivalent to the top of the.

Then, in the next step << 23 >>, the cured optical resin (layer 21) is peeled from the concavo-convex pattern 24 of the mold 23. At this time, in the second embodiment, as shown in FIG. 4C, the optical resin (layer 21) is peeled off together with the pressing plate 25. Further, at the time of peeling, the optical material (layer 21) is deformed along the groove direction of the concavo-convex pattern 24.

That is, first, the uneven pattern 2 of the die 23
At one end of the groove 4 in the groove direction, a force is applied to the optical resin (layer 21) and the pressing plate 25 in a direction away from the mold 23 (X direction in the drawing). As a result, a trigger for peeling can be easily provided. After that, by continuously applying a force in the X direction, the deformation of the pressing plate 25 and the optical material (layer 21) progresses toward the other end side (Y direction in the drawing) along the groove direction of the concavo-convex pattern 24. As a result, the uneven pattern 24
And the optical resin (layer 21) is peeled off.

Therefore, without forcibly applying an excessive force to the optical resin (layer 21) and the pressing plate 25 or greatly deforming the optical resin (layer 21) and the pressing plate 25,
The optical resin (layer 21) can be easily peeled from the uneven pattern 24. Therefore, in the surface 20a of the layer 21 after peeling (FIG. 4 (d)), the top portion 27 of the uneven pattern 22 is not chipped.

Finally, the pressing plate 25 is released from the peeled layer 21. As a result, the surface 2 of the optical resin layer 21
The diffractive optical element 20 of the second embodiment in which the uneven pattern 22 is formed on 0a is completed. As described above, in the second embodiment, when manufacturing the diffractive optical element 20, the uncured product 21 of the optical resin is formed on the uneven pattern 24 of the mold 23.
In the step of applying a, the uncured product 21a is spread along the groove direction of the concave-convex pattern 24.
It is possible to spread a to every corner of the fine valley portion 26 (FIG. 4B) of the concavo-convex pattern 24.

Therefore, the valley portion 26 of the uneven pattern 24 is formed.
Bubbles remain in the valleys 26 (FIG. 4B) of the uneven pattern 24 regardless of the depth (that is, the lattice height) of FIG. 4B and the viscosity of the uncured material 21a. There is no problem. If air bubbles remain, the layer 2 of the completed diffractive optical element will be
On the surface 20a of No. 1, the shape of the concavo-convex pattern 22 becomes inaccurate, and desired performance cannot be obtained.

Furthermore, in the second embodiment, when manufacturing the diffractive optical element 20, the concave-convex pattern 24 of the mold 23 is used.
In the step of peeling off the cured optical resin (layer 21) from, the optical material (layer 21) is deformed along the groove direction of the concavo-convex pattern 24. Therefore, on the surface 20a of the layer 21 after peeling, the concavo-convex pattern 22 is formed. The top portion 27 (FIG. 4 (d)) is not chipped.

As described above, in the second embodiment, the uneven pattern 22 having an accurate shape can be formed on the surface 20a of the layer 21 made of the optical resin. In particular, the shape of the top 27 (corresponding to the valley 26 in FIG. 4B) of the uneven pattern 22 of the layer 21 is also accurate. Therefore, the spectral function of the manufactured diffractive optical element 20 can also exhibit sufficient performance.
That is, the diffractive optical element 20 having a highly accurate spectral function
Is obtained.

In the above-described embodiment, the example of the diffractive optical elements 10 and 20 having the spectral function has been described, but the present invention is not limited to this. For example, although the diffractive optical element 20 in the second embodiment is manufactured as a transmissive diffractive optical element, the layer 21 is made of a material that is opaque to the used wavelength range and is incident on the surface on which the concavo-convex pattern 22 is formed. It may be manufactured as a reflection type diffractive optical element that does not transmit light but reflects while diffracting. In this case, a reflective film is formed on the surface on which the uneven pattern 22 is formed.

Further, also in the manufacturing method, in order to form the uneven pattern 22 on the layer 21, the uneven pattern 2 is formed.
Although the mold 23 having the inverted shape of 2 is used, the mold may be formed of a material that transmits light in a wavelength range that cures the uncured product 21a other than the metal mold. By using such a mold, light for curing the uncured product 21a can be irradiated from the mold side.

The present invention can also be applied to the diffractive optical element 30 (FIG. 5) having a lens function. Diffractive optical element 3
0 is a layer 31 made of an optical material made of glass or resin
And a layer 32 made of a resin optical material, and a ring-shaped concavo-convex pattern 3 is formed on a boundary surface 30a between the layers 31 and 32.
3 is formed. The manufacturing method of the diffractive optical element 30 is
Similar to the diffractive optical element 10 of the first embodiment, the layer 31
In the step of applying the uncured product of the optical resin on the uneven pattern 33, the uncured product may be spread along the groove direction of the uneven pattern 33. As a result, the uncured material can be spread to every corner of the fine valley portion of the uneven pattern 33.

Therefore, the concavo-convex pattern 33 having an accurate shape can be formed on the surface of the layer 32 made of the optical resin (the boundary surface 30a with the layer 31). In particular, the shape of the top of the concavo-convex pattern 33 seen from the side of the layer 32 made of optical resin is also accurate. Therefore, the lens function of the manufactured diffractive optical element 30 can also exhibit sufficient performance. That is, the diffractive optical element 30 having a highly accurate lens function can be obtained.

Further, in the above-described embodiment, the example of the diffractive optical elements 10 to 30 having a single optical function has been described, but the diffractive optical element 40 of FIG. 6 capable of simultaneously realizing a plurality of optical functions is used. The present invention can also be applied. Diffractive optical element 40
Is a layer 41 made of an optical material made of glass or resin,
Composed of layers 42 and 43 made of a resin optical material,
On the boundary surface 40a of the layers 41 and 42, the groove-shaped uneven pattern 4 is formed.
4 is formed, and a groove-shaped concavo-convex pattern 45 is formed on the boundary surface 40b of the layers 42 and 43. Uneven pattern 44
Is a linear pattern at equal intervals, and the concavo-convex pattern 45 is
It is a concentric pattern.

The method of manufacturing the diffractive optical element 40 is the same as that of the diffractive optical element 10 of the first embodiment. In the step of applying an uncured optical resin on the uneven pattern 44 of the layer 41, the uneven pattern 44 is formed. The uncured product may be pushed and spread along the groove direction. As a result, the uncured material can be spread to every corner of the fine valley portion of the uneven pattern 44.

Further, similarly, the uneven pattern 45 of the layer 42 is formed.
In the step of applying the uncured product of the optical resin on the above, the uncured product may be spread along the groove direction of the concavo-convex pattern 45. As a result, the uncured material can be spread to every corner of the fine valley portion of the concavo-convex pattern 45. Therefore, the surface of the layer 42 made of the optical resin (the boundary surface 40 a with the layer 41) and the surface of the layer 43 (the boundary surface 40 with the layer 42).
It is possible to form the concavo-convex patterns 44 and 45 having an accurate shape in b). Therefore, the diffractive optical element 40 can also exhibit sufficient performance in the spectral function and the lens function. That is, it is possible to obtain the diffractive optical element 40 capable of simultaneously realizing a highly accurate spectral function and lens function.

[0044]

As described above, according to the manufacturing method of the present invention, it is possible to form a groove-shaped concavo-convex pattern having an accurate shape on the surface of the optical material made of resin.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a diffractive optical element 10 according to a first embodiment.

FIG. 2 is a diagram illustrating a method of manufacturing the diffractive optical element 10.

FIG. 3 is a schematic diagram showing an overall configuration of a diffractive optical element 20 of a second embodiment.

FIG. 4 is a diagram illustrating a method of manufacturing the diffractive optical element 20.

FIG. 5 is a schematic diagram showing an overall configuration of a diffractive optical element 30 of a modified example.

FIG. 6 is a schematic diagram showing an overall configuration of a diffractive optical element 40 of a modified example.

[Explanation of symbols] 10, 20, 30, 40 Diffractive optical element 11, 12, 21, 31, 32, 41, 42, 43 layers 12a, 21a uncured product 13, 22, 24, 33, 44, 45 Concavo-convex pattern 14,25 push plate 15,26 Tanibe 23 Mold 27 top

Claims (3)

[Claims] 1. A method of manufacturing a diffractive optical element in which a groove-shaped uneven pattern is formed on a boundary surface between two layers made of different optical materials, the uneven pattern being formed on a surface of a layer made of a predetermined optical material. A forming step of forming, an applying step of applying an uncured product of a resin optical material having a different refractive index from the predetermined optical material on the concavo-convex pattern, and a curing step of curing the uncured product. The method for manufacturing a diffractive optical element, characterized in that, in the applying step, when the uncured product is applied, the uncured product is spread along the groove direction of the concavo-convex pattern. 2. A method of manufacturing a diffractive optical element in which a groove-shaped concavo-convex pattern is formed on the surface of a layer made of a resin optical material, wherein the optical material is formed on the surface of a mold having an inverted shape of the concavo-convex pattern. The coating step of applying an uncured product, a curing step of curing the uncured material, and a peeling step of peeling the cured optical material from the mold, in the coating step, A method for manufacturing a diffractive optical element, which comprises spreading the uncured material along the groove direction of the inverted shape of the concavo-convex pattern when applying. 3. The method for manufacturing a diffractive optical element according to claim 2, wherein in the peeling step, the cured optical material is deformed along the groove direction of the concavo-convex pattern and peeled. Method of manufacturing diffractive optical element.