JPH0667594A - Method for reproducing hologram - Google Patents

Abstract

PURPOSE:To reproduce a good hologram by facilitating the adjustment of parallelism and preventing uneven thickness in the method for reproducing the hologram for reproduction of the good hologram from a master hologram. CONSTITUTION:This method for reproducing the hologram reproduces the hologram by forming a stamper 10 in accordance with the hologram of a surface relief type, diffusing a resin 11 to the stamper 10 and transferring the resin to a reproducing substrate 12. A part of the surface of the stamper 10 on which the hologram is formed is provided with a monitor region 10a for reflecting light and the hologram is reproduced while the thickness of the resin 11 is adjusted according to the reflected light of the light with which the monitor region 10a is irradiated.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a hologram duplication method for duplicating a good hologram from a master hologram.

In recent years, various devices using holograms as optical elements have been developed and put into practical use. For example,
The POS barcode scanner is equipped with an optical scanning device using a hologram to read the barcode attached to the product. In addition, applied research on optical systems such as laser printers is also active.

Since such a hologram is easy to handle and has a great advantage that it can be duplicated, it is excellent in mass productivity and is suitable for application to a mass-produced optical system or the like.

By the way, when a hologram is created, a master hologram is first created and a copy is created using this master hologram as a master disk. Therefore, there is a demand for a method capable of reproducing a high quality hologram.

[0005]

2. Description of the Related Art Conventionally, holograms are produced by, for example, a two-beam interference exposure method. The hologram created by such a method cannot obtain a diffraction grating that satisfies the desired specifications when there is fluctuation of interference fringes during exposure, and a hologram with a high rate of diffracting input light, that is, a highly efficient hologram is obtained. It is hard to be caught.

Since the fluctuation of the interference fringes is caused by the change of the ambient temperature, the fluctuation of the light source, the wind, etc., it is difficult to keep these environmental conditions constant, and the two-beam interference exposure method is used. It's nearly impossible to make a lot of good quality holograms.

Therefore, in order to inexpensively produce a large amount of holograms, a master hologram having no fluctuation of interference fringes is produced by using a two-beam interference exposure method under strict control.
A technique for replicating from this master hologram is essential. This duplication technique is being actively researched for each of the holograms of the refractive index modulation type and the surface relief type.

In the duplication of holograms, in the case of duplication of surface relief holograms, first, a fluctuation-free hologram created by the two-beam interference exposure method is created, and then a metal mold, for example, in which the irregularities of this hologram are reversed is used. Create and use this as a stamper.

Then, a resin (photopolymer) is dropped on the stamper prepared by the above method, a replica substrate is placed on the stamper to diffuse the resin, and the diffused resin is solidified and peeled off from the stamper. The hologram on which the interference fringes are formed by resin is duplicated.

However, for example, as shown in FIG.
When the stamper and the duplicate substrate 52 are not kept parallel to each other when the stamper on which the resin 51 is dropped is covered with the duplicate substrate 52, the hologram 53 is formed by the resin 51 having uneven thickness.

When the light source 54 irradiates the hologram 53 formed of the resin 51 having such uneven thickness, it should be diffracted as shown by the broken line in the figure, but the diffraction direction is shifted as shown by the solid line. There was a flaw.

Therefore, in order to eliminate such a defect, FIG.
A thickness correction method as shown in FIG.

That is, the resin 51 is attached to both surfaces of the duplicated substrate 52, and the duplicated substrate 52 is sandwiched by another substrate 55 having a good surface precision (hereinafter referred to as “correction substrate”) 55, and the inclination of the correction substrate 55 is corrected by the correction mechanism 5.
6 to maintain the parallelism between the correction substrate 55 and the surface of the stamper 50 within a predetermined range. In this state, the resin 51 is hardened and then peeled from the stamper 50 to remove the uneven thickness.

At this time, the adjustment of the parallelism is performed by the structure as shown in FIG. 6, for example. In the figure, 57 is a light source, 58 is a half mirror, and 59 is a screen.

In checking the parallelism, first, the resin 5
The position of the reflected light from the stamper 50 before 1 is dropped is obtained. That is, the light output from the light source 57 is reflected by the half mirror 58 and reaches the stamper 50. And
Since the light reflected by the stamper 50 passes through the half mirror 58 and forms an image on the screen 59, this image forming position is recorded.

Next, the resin 51 is dropped on the stamper 50 to cover the duplicate substrate 52, and the resin 5 is further placed on the duplicate substrate 52.
1 is dropped to cover the correction substrate 55. Light source 5 in this state
Light is output from 7. The light output from the light source 57 is reflected by the half mirror 58 and reaches the correction substrate 55. Then, the light reflected by the correction substrate 55 passes through the half mirror 58 and forms an image on the screen 59.

Here, the stamper 50 previously recorded
When the image forming position of the reflected light from the image forming device differs from the image forming position of the correction substrate 55, the correction mechanism 56 (see FIG. 5) is driven to adjust the image forming positions so that they coincide with each other. The stamper 50 and the correction substrate 55 at the time when the two image formation positions match.
It is determined that are parallel.

However, this parallelism measuring method has a drawback that it is difficult to confirm the parallelism over the entire stamper. Further, in this method, even if the correction substrate 55 is tilted for 10 seconds, for example, the deviation of the image formation position of the reflected light is about 1 millimeter at 10 meters, and the accuracy is low.

As another method for confirming parallelism, FIG.
As shown in, stamper 50, resin 51, and duplicate substrate 5
2. In the state where the resin 51 and the correction substrate 55 are sequentially laminated, collimated laser light is irradiated to observe the interference fringes of the reflected light from the upper surface of the stamper 50 and the reflected light from the upper surface of the correction substrate 55. There is a method in which the correction mechanism 56 is operated to bring the interference fringes into a predetermined specification value.

According to this method, since the entire area of the stamper 50 can be observed at one time, there is a great advantage that the parallelism of the entire stamper can be confirmed at one time.

However, since the hologram pattern is provided on the surface of the stamper 50 of the surface relief type hologram, there is a drawback that the incident light is heavily scattered and it is not easy to observe the interference fringes.

[0022]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a hologram duplication method capable of duplicating a good hologram by facilitating adjustment of parallelism and preventing unevenness in thickness. The purpose is to

[0023]

The invention according to claim 1 is
In order to achieve the above object, as shown in principle in FIG. 1, a stamper 10 based on a surface relief type hologram is used.
In the hologram duplication method in which the hologram is duplicated by making the resin 11 on the stamper 10 and transferring the resin 11 to the duplication substrate 12, a monitor for reflecting light on a part of the surface of the stamper 10 on which the hologram is formed. Area 1
0a is provided, and the hologram is duplicated while adjusting the thickness of the resin 11 according to the reflected light of the light emitted to the monitor area 10a.

Further, the invention according to claim 2 is a hologram duplication in which the stamper 10 is formed based on the surface relief type hologram, and the resin 11 is diffused in the stamper 10 and transferred to the duplication substrate 12 to duplicate the hologram. In the method, a monitor area 10a is provided on a part of a surface of the stamper 10 on which a hologram is formed,
0 is covered with a duplicate substrate 12 with a resin 11 interposed therebetween, the duplicate substrate 12 is further covered with a correction substrate 13 with a resin 11 interposed therebetween, and the stamper 1 is irradiated with light from the correction substrate 13 side.
0 from the monitor area 10a and the correction substrate 13
The hologram is reproduced while adjusting the thickness of the resin 11 by observing the interference fringes with the reflected light from the hologram.

[0025]

According to the first aspect of the present invention, a monitor area 10a for reflecting light is provided on a part of the stamper 10, and the monitor area 1a is provided.
The hologram is duplicated while adjusting the parallelism of the resin 11 by using the reflected light from 0a.

As a result, it is possible to prevent the irradiation light from being scattered, as in the case of adjusting the parallelism by irradiating the conventional hologram pattern area with light.
Therefore, the thickness of the resin 11 can be easily adjusted, and a good hologram can be reproduced.

The invention according to claim 2 is the stamper 1
0, resin 11, duplicate substrate 12, resin 11 and correction substrate 1
3 is sequentially superposed, and light is irradiated from the correction substrate 13 to cause the reflected light from the monitor region 10a of the stamper 10 and the correction substrate 13 to interfere with each other, and the stamper 10 and the correction substrate 13 are parallel while observing interference fringes. The hologram is reproduced while adjusting the degree, that is, the thickness of the resin 11.

The method of adjusting the parallelism while observing the interference fringes has the advantage that the entire replica substrate can be observed and the parallelism can be confirmed with extremely high accuracy, as described in the prior art. Have. In addition to this advantage, the contrast of the interference fringes can be improved by providing the monitor region 10a as described above, so that the parallelism can be adjusted more easily, and thus a good hologram can be reproduced. Has become.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the hologram duplication method of the present invention will be described below with reference to the drawings. Note that the same or corresponding parts as in FIG.

FIG. 2 is a diagram for explaining an example in which the hologram duplication method according to the present invention is applied to a disk stamper. FIG. 1A shows the disc stamper 10. Since the method of creating this stamper is well known, its description is omitted here.

In the figure, the disk stamper 10a is
It is configured to have a normal hologram area 10b and a monitor area 10a. In the figure, a disk having six facets is shown in order to perform six scans with one rotation of the disk.

The normal hologram area 10b is an area in which concave and convex grooves are formed by interference fringes, and is a portion which realizes various optical functions by diffraction of light.

The monitor area 10a is an area in which a hologram pattern is not formed, which is provided on the outer or inner circumference of the disk and between the facets. This monitor area 10a
It is desirable that the hologram pattern is flat without any hologram pattern, but a hologram pattern with shallow grooves may be formed.

As shown in FIG. 1, a resin 11 is dropped onto the stamper 10 having the above-described structure, a duplicate substrate 12 is placed on the resin 11, and then the resin 11 is dropped onto the correction substrate 13. Then, the hologram is duplicated.

As the duplicate substrate 12, for example, a glass or acrylic plate formed in a disk shape is used.

As the resin on which the interference fringes are formed, for example, a photopolymer which is cured by irradiation with ultraviolet rays is used. This photopolymer is made of a material whose refractive index when cured is approximately the same as that of the replica substrate 12. As a result, the influence of the joint surface between the correction substrate 12 and the resin 11 on the diffraction of light is eliminated.

The correction substrate 13 is made of, for example, a glass plate having high flatness and high reflectance. A correction mechanism (not shown) similar to that described in the conventional example is provided on the upper side of the correction substrate 13 in the drawing.
You can press.

In the above structure, the hologram is duplicated as follows.

First, a resin (photopolymer) 11 is dropped on the ordinary hologram area 10b of the prepared disk stamper 10. Then, the duplicate substrate 12 is put on the same. Furthermore, the resin 11 is dropped on the duplicate substrate 12,
The correction substrate 13 is placed.

In this state, the work of adjusting the parallelism of the correction substrate 13 is performed. That is, collimated light, for example, laser light is emitted from the upper side of the correction substrate 13 in the figure (see FIG. 1). At this time, the optical path is adjusted so that the collimated light that has passed through the correction substrate 13, the resin 11, the duplicate substrate 12, and the resin 11 is applied to the monitor region 10 a of the stamper 10.

A part of the collimated light is corrected by the correction substrate 13.
It is reflected on the upper surface, and the other part is corrected substrate 13, resin 11,
It passes through the duplicate substrate 12 and the resin 11 and is reflected by the monitor region 10 a of the stamper 10. In the reflection in the monitor area 10a, the hologram pattern is not formed in the monitor area 10a or the groove of the hologram pattern is shallow, so that the scattering of light is suppressed and the reflection is efficiently performed.

The light reflected by the monitor area 10a passes through the resin 11, the duplicate substrate 12, the resin 11 and the correction substrate 13 and is emitted to the outside of the correction substrate 13.

At this time, if the correction substrate 13 and the stamper 10 are completely parallel, the light reflected by the correction substrate 13 and the light reflected by the monitor area 10a of the stamper 10 are also parallel light, and the light interference occurs. Does not happen. Therefore, interference fringes cannot be observed even when viewed from the reflected light side.

However, if there is an inclination between the correction substrate 13 and the stamper 10, interference fringes are observed, and the number of the interference fringes differs depending on the degree of inclination. Therefore, the inclination of the correction substrate 13 is adjusted by operating the correction mechanism while observing the number of interference fringes and appropriately adjusting the number of interference fringes.

By the way, the number of interference fringes due to light interference changes in the order of the wavelength of light. Therefore, it is difficult to adjust the correction substrate 13 and the stamper 10 in parallel with each other by using the correction mechanism.

Therefore, the hologram is adjusted so as to obtain parallelism within a predetermined range according to the purpose of use of the hologram.

For example, when the hologram is used as an optical scanning device of a laser printer, a horizontal line can be drawn in a straight line on the drum on which the light beam is imaged.
As shown in (B), the interference fringes between the facets are adjusted to be a predetermined number or less.

Further, in order for the vertical lines to be drawn straight on the drum on which the light beam is imaged, as shown in FIG. 2 (C), the interference fringes on the outer circumference of the hologram disc are less than a predetermined number. To adjust.

In this way, after adjusting the parallelism between the correction substrate 13 and the stamper 10 and thus the parallelism of the hologram formed by the resin 11 formed on the duplicated substrate 12 within a predetermined range, for example, ultraviolet rays are applied. Irradiate to solidify the resin. Next, the duplicate substrate 12 to which the cured resin 11 is adhered is peeled off from the disc stamper 10, and the hologram duplication is completed.

In this way, a monitor area 10a having no hologram pattern or a shallow groove hologram pattern is formed on a part of the stamper 10, and the monitor area 10a is formed.
Since interference fringes are generated by the interference between the reflected light from the and the reflected light from the correction substrate 13, the interference fringes with high contrast can be obtained.

Therefore, it becomes easy to count the number of interference fringes, so that the parallelism between the correction substrate 13 and the stamper 10, and thus the parallelism of the hologram formed by the resin 11 formed on the replica substrate 12 is within a predetermined range. Since the adjustment is easy, a good hologram can be easily duplicated without unevenness in thickness over the entire area.

FIG. 3 is a diagram for explaining an example in which the hologram duplication method according to the present invention is applied to a plate stamper. In the figure, the plate stamper 10 is also configured to have a normal hologram area 10b and a monitor area 10a.

As described above, the normal hologram area 10b is an area in which concave and convex grooves due to interference fringes are formed, and is a portion that realizes various optical functions by diffracting light. This normal hologram area 10b is provided inside the plate.

As described above, the monitor area 10a is also an area where the hologram pattern is not formed and is provided on the outer periphery of the plate. It is desirable that the monitor area 10a has no hologram pattern and is flat, but a hologram pattern having shallow grooves may be formed.

In the hologram duplication using the plate stamper 10 having the above-described structure, the correction substrate 13 can be obtained by observing the interference fringes of the monitor regions 10a on the left and right sides and the upper and lower sides in the figure, like the disc stamper. Since it is easy to adjust the parallelism between the stamper 10 and the stamper 10, and thus the parallelism of the hologram formed by the resin 11 formed on the replica substrate 12 to be within a predetermined range, it is possible to reproduce a good hologram without uneven thickness over the entire area. It is easy to do.

[0056]

As described in detail above, according to the present invention, it is possible to provide a hologram duplication method capable of duplicating a good hologram by facilitating the adjustment of the parallelism and preventing the uneven thickness.

[Brief description of drawings]

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

FIG. 2 is a diagram for explaining an embodiment of the hologram duplication method of the present invention.

FIG. 3 is a diagram for explaining another embodiment of the hologram duplication method of the present invention.

FIG. 4 is a diagram for explaining an influence of uneven thickness of a conventional hologram.

FIG. 5 is a diagram for explaining a conventional method for correcting unevenness in hologram thickness.

FIG. 6 is a diagram for explaining an example of a conventional method for confirming unevenness in thickness of a hologram.

FIG. 7 is a diagram for explaining another example of the conventional method for confirming the uneven thickness of a hologram.

[Explanation of symbols]

 10 Stamper 10a Monitor Area 11 Resin 12 Duplicate Substrate 13 Correction Substrate

Claims (3)

[Claims] 1. A hologram duplication in which a hologram is duplicated by forming a stamper (10) based on a surface relief type hologram, diffusing a resin (11) in the stamper (10) and transferring the resin (11) to a duplication substrate (12). In the method, a monitor area (10a) for reflecting light is provided on a part of the surface of the stamper (10) on which the hologram is formed, and the resin is applied according to the reflected light of the light irradiated to the monitor area (10a). A hologram duplication method, characterized in that the hologram is duplicated while adjusting the thickness of (11). 2. A hologram duplication in which a hologram is duplicated by forming a stamper (10) based on a surface relief type hologram, diffusing a resin (11) in the stamper (10) and transferring the resin to a duplication substrate (12). In the method, a monitor region (10a) is provided on a part of the surface of the stamper (10) on which the hologram is formed, and a resin (11) is interposed in the stamper (10) to form a duplicate substrate (12).
And the resin (11) is further interposed on the duplicate substrate (12) to correct the correction substrate (1
3) and irradiate light from the correction substrate (13) side to observe interference fringes between the reflected light from the monitor area (10a) of the stamper (10) and the reflected light from the correction substrate (13). By doing the resin (11)
A hologram duplication method characterized by duplicating a hologram while adjusting the thickness of the hologram. 3. The stamper according to claim 1,
The hologram duplication method, wherein the monitor area (10a) provided in (10) is a flat area without a hologram pattern or a shallow groove-shaped hologram pattern area.