JP3224244B2 - Hologram duplication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram duplication method for duplicating a surface relief type hologram, and more particularly to a hologram duplication method for mass-producing holograms using a stamper on which a hologram pattern is transferred from a master hologram.

In recent years, natural stereoscopic image display using holograms, optical elements, image recording, optical operation / optical memory, and the like have been developed and widely used for displays in cards and publications, optical equipment, optical information processing, and the like. I have. This hologram is created by the two-beam interference exposure method. However, if the interference fringes fluctuate due to the vibration of the optical system during the exposure, the fluctuation of the air, the vibration of the target object, etc., a hologram with high diffraction efficiency cannot be obtained. For this reason, strict photographic conditions must be satisfied for hologram production, and it is very difficult to repeat exposure and produce many holograms with high efficiency. Therefore, in order to produce a large number of identical holograms at low cost, it is essential to create a master hologram and duplicate it from the master hologram.

[0003] Holograms are roughly classified into two types, an amplitude type and a phase type. Generally, the phase type has higher diffraction efficiency. The phase type is divided into a refractive index modulation type that realizes a phase distribution by changing the internal refractive index, and a surface relief type that realizes a phase distribution by unevenness of the surface. Gelatin or the like is used, and for the latter, a photoresist, a thermosensitive material or the like is used.
In particular, the latter surface relief type is intensively studied for mass production because it can be easily copied by molding. The 2P method using an ultraviolet curable resin (photopolymer method) and the compression molding method using a thermoplastic resin (embossing method). Method) and the injection molding method.

[0004]

2. Description of the Related Art FIG. 11 shows a conventional method of duplicating a surface relief hologram by the 2P method.
First, a dry plate 13 coated with a photoresist 12 on a substrate 11 is prepared, and holographic exposure is performed by a two-beam interference exposure method through a mask 14 using an object beam 15 and a reference beam 16 to obtain a surface relief type master hologram (resist hologram). ) 17 is created. The surface of the master hologram 17 has an area where a desired hologram pattern is formed (FIG. 1).
1A) and an area without a pattern (see B in FIG. 11)
Divided into Next, a Ni film 18 is formed on the surface of the master hologram 17 by vapor deposition or the like, and a Ni plating layer 19 is formed sufficiently thick by electroforming.
7 and finally, an Al base 20 is lined on the back side of the Ni plating layer 19 to form a stamper 21.

[0005] Then, an ultraviolet curable resin (photopolymer) 22 is dropped on the relief surface of the stamper 21 and a duplicate substrate 23 such as a glass or plastic plate is overlaid.
After UV curing from the outside of the duplicate substrate 24 and UV curing, the work (ultraviolet curing resin 22 and duplicate substrate 23)
24 is peeled from the stamper 21 to obtain a duplicate hologram 25 in which the relief of the stamper 21 is modeled. Stamper 21
By repeating the dropping of the ultraviolet curing resin 22 on the substrate, the superposition of the duplicate substrate 23, the UV curing, and the peeling of the work 24 from the stamper 21, a large number of holograms having a desired hologram pattern can be produced at low cost. The method of creating a duplicate hologram by other compression molding method or injection molding method is a well-known technique, and a description thereof will be omitted.

[0006]

By the way, in the surface relief type hologram, the deeper the groove of the hologram pattern, the greater the modulation degree and the higher the efficiency. On the other hand, if the light wavelength at the time of exposure is small, the pitch becomes smaller. When the pitch is constant, as shown in FIG. 12, the deeper the groove of the hologram pattern, the greater the adhesion between the stamper and the UV-cured work (ultraviolet curable resin), and when the groove depth is constant, as shown in FIG. As shown in FIG. 13, as the pitch of the hologram pattern becomes smaller, the adhesion between the stamper and the UV-cured work (ultraviolet curable resin) increases.

For this reason, if the hologram pattern has a deep groove or a narrow pitch, the adhesion between the stamper 21 and the ultraviolet curable resin 22 becomes very large,
When the work 24 is peeled off from the stamper 21, there is a problem that stress concentration occurs and the work 24 is damaged.

For example, as shown in the upper part of FIG. 14, when there is an area A on which a desired hologram pattern is formed and an area B without a pattern on the relief surface side of the stamper 21, the stamper 21 after UV curing is used. As shown in the lower part of FIG. 14, the adhesion between the area A and the workpiece 24 is considerably large in the area A and is considerably small in the area B. Therefore, a considerably large step is formed at the boundary of the area A. A considerable stress concentration occurs on the upper portion, and the duplicate substrate 23 is broken.

Further, as shown in the upper part of FIG. 15, only a region A where a desired hologram pattern is formed is present on the surface of the stamper 21A, and a portion corresponding to a surrounding region having no pattern is processed and removed. In this case, the adhesion force between the stamper 21A and the work 24A after the UV curing becomes considerably large in the area A as shown in the lower part of FIG. 15, while it becomes zero in the periphery and a very large step is formed at the boundary of the area A. At the time of peeling, a very large stress concentration occurs on the boundary, and the duplicate substrate 23 is broken. These problems also exist in the compression molding method and the injection molding method.

Accordingly, an object of the present invention is to provide a hologram duplication method capable of easily duplicating a hologram pattern without damaging a work even if a desired hologram pattern has a deep groove or a narrow pitch. It is to be.

[0011]

FIG. 1 is a diagram illustrating a first principle of the present invention. Reference numeral 21 denotes a stamper having a region A on which a desired hologram pattern is formed and a region B having no surrounding pattern, 22 denotes an ultraviolet curable resin dropped on the stamper 21, and 23 denotes a duplicate substrate superimposed on the ultraviolet curable resin 22. , 24 are an ultraviolet curable resin 22 and a duplicate substrate 23
Consisting workpiece 26 at the boundary of the region A from the region A from
Placing and a mask to continuously reduce the amount of UV irradiation.

FIG. 2 is an explanatory view of the second principle of the present invention.
21B is a stamper having a region a where a desired hologram pattern is formed on the surface and a buffer region c adjacent to the region a where a groove having a shallower groove than the desired hologram pattern region a is formed. 22 is dropped on the stamper 21B. UV-curable resin, 23 is a duplicate substrate superimposed on UV-curable resin 22, 24B is UV-curable resin 22 and duplicate substrate 23
It is a work consisting of

[0013]

In FIG. 1, when the work 24 is irradiated with UV light from above the mask 26 using a UV lamp, the UV-curable resin 22 is UV-cured. At this time, the surface relief of the stamper 21 is transferred to the UV-curable resin 22. Is done. The irradiation amount of the ultraviolet light applied to the ultraviolet curable resin 22 is large near the center of the region A where the desired hologram pattern is formed, and decreases as approaching the boundary of the region A. For a hologram pattern with a certain groove depth and pitch,
The relationship between the amount of UV irradiation and the adhesion between the stamper and the work is
As the irradiation dose of ultraviolet light increases to a certain irradiation dose, the adhesive force increases almost in proportion, and becomes saturated when the irradiation dose exceeds that. Therefore, as shown in the lower part of FIG. 1, the adhesion between the stamper 21 and the work 24 after UV curing continuously decreases from the inside of the area A where the desired hologram pattern is formed to the boundary, and the area A And the step of the adhesion force at the boundary between the pattern and the region B without the pattern are reduced. If you do this,
When the work 24 is separated from the stamper 21, even if the groove of the desired hologram pattern is deep or the pitch is narrow, the stress concentration at the boundary of the region A where the desired hologram pattern is formed is weakened, and the duplicate substrate 23 and the like are removed. No breakage occurs, and the yield is improved.

In FIG. 2, U
When the work side is irradiated with ultraviolet rays using a V lamp, the ultraviolet curing resin 22 is cured by UV, and at this time, the stamper 21B
Is transferred to the ultraviolet curable resin 22. When the groove of the hologram pattern becomes shallower , the adhesion between the stamper and the work becomes smaller even with the same irradiation dose. Therefore, as shown in the lower part of FIG.
The adhesion force between the workpiece 1B and the work 24B is greatest in the area a where the desired hologram pattern is formed, and is reduced by one step in the buffer area c adjacent to the area a, and the area without the pattern formed around the buffer area c b further reduces the size by one step.
In this way, when the workpiece 24B is peeled from the stamper 21B, even if the groove of the desired hologram pattern is deep or the pitch is narrow, the boundary of the area a where the desired hologram pattern is formed or the area without the pattern is formed. b
And the stress concentration at the boundary is weakened and the duplicated substrate 23 and the like are not damaged.

[0015]

FIG. 3 is an explanatory view showing a hologram duplicating method according to a first embodiment of the present invention, and the same parts as those in FIG. 11 are denoted by the same reference numerals. The production of the master hologram 17 by holographic exposure and the production of the stamper 21 from the master hologram 17 are exactly the same as those in the prior art shown in FIG. 11, and the surface of the stamper 21 is formed around the area A where the desired hologram pattern is formed and the surrounding area. Area B without a pattern.

When a duplicate hologram is formed from the stamper 21 by the 2P method, an ultraviolet curable resin 22 is dropped by a predetermined thickness on the entire relief surface side of the stamper 21, and a duplicate substrate 23 made of a glass plate, a plastic plate or the like is applied from above. Overlaid. UV curable resin 22 and duplicate substrate 2
3 constitutes the work 24. Then, on the work 24, the ultraviolet transmittance continuously decreases from the inside of the desired hologram pattern area A of the stamper 21 to the boundary, and almost 100% for the central part of the area A and the surrounding area B without the pattern. %, And a UV lamp 27 irradiates the work 24 with ultraviolet light from above the mask 26 for a predetermined period of time.

When the ultraviolet ray is irradiated, the ultraviolet curable resin 22 becomes U
V-curing is performed, and the surface relief of the stamper 21 is transferred by molding. Thereafter, the work 24 is peeled from the stamper 21 to obtain a duplicate hologram 25.
Is large near the center of the area A where the desired hologram pattern is formed, and decreases as the border of the area A is approached. For a hologram pattern having a constant groove depth and pitch, the relationship between the amount of ultraviolet irradiation and the adhesion between the stamper and the work is almost proportional to the amount of ultraviolet irradiation up to a certain amount of irradiation, as shown in FIG. As a result, the adhesive strength increases, and when the irradiation amount exceeds that, it saturates. Therefore, as shown in the lower part of FIG. 5, the adhesion between the stamper 21 and the work 24 after UV curing continuously decreases from the inside of the area A where the desired hologram pattern is formed to the boundary, and the area A And the step of the adhesion force at the boundary between the pattern and the region B without the pattern are reduced.

Therefore, when the work 24 is peeled from the stamper 21, the groove of the desired hologram pattern may be deep,
Even if the pitch is small, the stress concentration at the boundary of the region A where the desired hologram pattern is formed is weakened, and the peeling operation can be easily performed without incurring the damage of the work 24 such as the destruction of the duplicate substrate 23. . As described above, the step of the adhesive force between the stamper and the work at the boundary of the region A can be reduced by reducing the amount of ultraviolet irradiation from the inside of the region A where the desired hologram pattern is formed to the boundary. In the work peeling step of the hologram duplication work, breakage of the work can be avoided, and the yield can be improved.

In the above-described first embodiment, the amount of ultraviolet radiation is continuously reduced from the inside of the region A where the desired hologram pattern is formed to the boundary.
As shown in FIG. 6, it may be reduced stepwise. Further, as shown in the upper part of FIG. 7, 2P using a stamper 21A in which a pattern-free region B around a region A where a desired hologram pattern is formed is removed by processing.
When the hologram is duplicated by the method, as shown in the lower part of FIG. 7, the step of the adhesion force between the stamper and the work at the boundary of the area A can be considerably reduced, and the stress concentration at the time of peeling the work can be considerably reduced. Can be avoided.

FIG. 8 is an explanatory view showing a hologram forming method according to a second embodiment of the present invention, and the same parts as those in FIG. 2 are denoted by the same reference numerals. First, a dry plate 13 on which a photoresist 12 is applied on a substrate 11 is prepared.
4A, object light 15 and reference light 1
6 performs the first normal holographic exposure.
Next, a portion having a predetermined width adjacent to the already exposed portion of the dry plate 13 is not masked, and the angle with respect to the object light 15 is made smaller than the first time through a second mask 14B that masks other portions, In addition, a second holographic exposure is performed with the reference light 16A whose light intensity has been weakened, thereby creating a master hologram (resist hologram) 17B of a surface relief type. In the second exposure, the light intensity of both the object light 15 and the reference light 16A may be reduced.

The surface of the master hologram 17B has a region a where a desired hologram pattern is formed, a buffer region c adjacent to the region a, which has a shallower groove depth than the pattern of the region a and has a coarse pitch and a predetermined width. The area around c is divided into an area b without a pattern. Next, a Ni film 18 is formed on the surface of the master hologram 17B by vapor deposition or the like, and further, a Ni plating layer 19 is formed sufficiently thick by electroforming, and then separated from the master hologram 17B. Backing the aluminum base 20 on the back side of the stamper 21B
And Also on the relief surface of the stamper 21B, a region a where a desired hologram pattern is formed, a buffer region c having a predetermined pitch with a coarser pitch, a shallower groove depth than the pattern of the region a, and a buffer region c adjacent to the region a Is formed around the area b without a pattern.

The stamper 21B thus created
UV curable resin (photopolymer) 2 on the entire relief side
2 is dropped and a predetermined duplicate substrate 23 is overlaid. Work 24B with ultraviolet curing resin 22 and duplicate substrate 23
Is configured. Then, ultraviolet rays are irradiated from above the work 24B to the work 24B side by a UV lamp for a predetermined fixed time.

When the ultraviolet curable resin 22 is irradiated with ultraviolet rays,
V-curing is performed, and the surface relief of the stamper 21B is transferred by molding. After this, the work 24B from the stamper 21B
Is peeled to obtain a duplicate hologram 25B, but if the hologram pattern has a shallow groove or a coarse pitch,
As shown in FIGS. 12 and 13, even with the same irradiation amount,
The adhesion between the stamper and the work is reduced. Therefore, as shown in the lower part of FIG. 6, the adhesion force between the stamper 21B and the work 24B after the UV curing is largest in the area a where the desired hologram pattern is formed, and is one step lower in the buffer area c adjacent to the area a. The size becomes smaller in the region b without a pattern formed around the buffer region c.

As a result, the stamper 21B moves the work 24
When peeling B, even if the groove of the desired hologram pattern is deep or the pitch is narrow, the stress concentration is weakened at any of the boundary of the region a where the desired hologram pattern is formed and the boundary of the region b where no pattern is formed. , Duplicate substrate 23
The work can be easily performed without damaging the work 24B such as breakage of the work. By forming a buffer region having a shallow groove and a coarse pitch adjacent to the region a where the desired hologram pattern is formed, the region a
And the step of the adhesive force between the stamper and the work at the boundary of the region (b) and the region (b) can be reduced, and in the work separation step of the hologram duplication work by the 2P method, the work can be prevented from being damaged, and the yield can be improved.

In the above-described second embodiment, the buffer region having a pattern that is shallower than the desired hologram pattern and has a longer pitch is formed. However, the pitch is the same as the desired hologram pattern. The buffer region may be replaced by a buffer region in which only the groove is shallow, or a buffer region in which the desired hologram pattern and the groove have the same depth and are coarse by the pitch. Also, when creating the master hologram, the buffer region c is formed. However, the master hologram is created in the same manner as before, and when forming the stamper, etching is performed adjacent to the region of the desired hologram pattern. By such a method, a shallow groove or a buffer may be formed by engraving a predetermined pattern with a coarse pitch,
In short, it is sufficient to form a buffer region on the relief surface side of the stamper adjacent to the region of the desired hologram pattern, in which the adhesive force with the work drops by one step.

A buffer region c is provided between the region a where the desired hologram pattern is formed and the region b where no pattern is formed.
Although only the steps were provided, as shown in the upper part of FIG.
A second buffer region c2 having a shallower groove and a longer pitch is provided adjacent to the first buffer region c1 formed on the relief surface of the stamper 21C, as shown in the lower part of FIG. From the boundary of the region a to the boundary of the region b, the adhesive force between the stamper and the work may be reduced in multiple stages. Further, in the above-described second embodiment, the case where the duplicate hologram is created by the 2P method has been described as an example. However, the present invention can be similarly applied to the case where the duplicate hologram is duplicated by the compression molding method or the injection molding method. In the case of duplication by the 2P method, the first embodiment and the second embodiment can be applied in combination. that's all,
Although the present invention has been described by way of examples, the present invention can be variously modified in addition to the above in accordance with the gist of the present invention described in the claims, and the present invention does not exclude these.

[0027]

As described above, according to the present invention, a desired hologram on the stamper is used when irradiating the ultraviolet curable resin superimposed on the stamper with ultraviolet rays and curing the surface relief of the stamper into the ultraviolet curable resin. Since the irradiation amount of the ultraviolet light is reduced continuously or stepwise from within the pattern area to the boundary of the hologram pattern area, the adhesion between the stamper and the work after the UV curing is required to form the desired hologram pattern. When the work is peeled off from the stamper in the last step at the time of creating the duplicate hologram by the 2P method, since the step is reduced continuously or stepwise from the inside of the region to the boundary from the inside of the region and the step of the adhesion force at the boundary is reduced. Even if the groove of the desired hologram pattern is deep or the pitch is narrow, the boundary of the area where the desired hologram pattern is formed Weakened stress concentration of, damage to the work does not occur.

According to the present invention, when a master hologram or a stamper is formed, a groove is formed adjacent to a desired hologram pattern region from the desired hologram pattern region.
Since the structure is such that a shallow buffer region is formed, the step of the adhesion between the stamper and the work at the boundary of the region where the desired hologram pattern is formed becomes small. When the work is separated from the stamper, even if the groove of the desired hologram pattern is deep or the pitch is narrow, the stress concentration at the boundary of the region where the desired hologram pattern is formed is weakened, and the work is not broken.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a first principle of the present invention.

FIG. 2 is a diagram illustrating a second principle of the present invention.

FIG. 3 is an explanatory diagram showing a first embodiment of the present invention.

FIG. 4 is a diagram showing the relationship between the amount of ultraviolet irradiation and the adhesion.

FIG. 5 is an explanatory diagram showing a distribution of adhesion force between a stamper and a work.

FIG. 6 is an explanatory diagram showing a modification of the first embodiment.

FIG. 7 is an explanatory view showing another modification of the first embodiment.

FIG. 8 is an explanatory diagram showing a second embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a distribution of adhesion force between a stamper and a work.

FIG. 10 is an explanatory diagram showing a modification of the second embodiment.

FIG. 11 is an explanatory diagram of a hologram duplication method by a general 2P method.

FIG. 12 is a diagram showing a relationship between a depth of a groove of a holographic pattern and an adhesion force.

FIG. 13 is a diagram showing a relationship between a pitch of a holographic pattern and an adhesive force.

FIG. 14 is an explanatory view showing a drawback of the conventional method.

FIG. 15 is an explanatory view showing a disadvantage of the conventional method.

[Explanation of symbols]

 17, 17B Master hologram 21, 21A, 21B, 21C Stamper 22 UV curable resin 23 Duplicate substrate 26 Mask 27 UV lamp

Claims (2)

(57) [Claims] 1. A stamper is created from a surface relief type master hologram created by holographic interference, an ultraviolet curable resin is superimposed on the stamper, and then irradiated with ultraviolet light to cure and mold the ultraviolet curable resin. Thereafter, the hologram replicating method for peeling the stamper from the ultraviolet curing resin, when irradiated with ultraviolet rays, subjected to the boundary of the hologram pattern area from the desired hologram pattern region on the stamper
Te, hologram replicating wherein the, decreasing continuously or stepwise dose. 2. A hologram duplication method, comprising: forming a stamper from a surface relief type master hologram created by holographic interference, superimposing a predetermined resin on the stamper, and removing the stamper from the predetermined resin; Forming a master hologram or a stamper, forming a buffer area adjacent to the desired hologram pattern area and having a shallower groove than the desired hologram pattern area.