JPH0651124A - Diffraction grating pattern consisting of volume phase type holographic grating and article having the same - Google Patents

Abstract

PURPOSE:To improve the security and prevent the article from being forged by an optical technique, and to enable anybody to easily ascertain the truth of the article. CONSTITUTION:In the diffraction grating pattern formed by arranging plural dots of fine diffraction gratings on the surface of a plane substrate 1, volume phase type holographic gratings 2 which have angle dependency and wavelength dependency are formed as the fine diffraction gratings, the spatial frequency and angle of the diffraction gratings are varied by the dots of the respective fine diffraction gratings, and a real image reproduction type hologram is formed as at least one of the diffraction gratings at need.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diffraction grating pattern formed by arranging a plurality of fine diffraction grating dots on a surface of a flat substrate, and a display and an article having the diffraction grating pattern. In particular, the present invention relates to a diffraction grating pattern composed of a volume phase holographic grating and a display and an article having the same, which enhances its security to prevent counterfeiting and enables anyone to make a very easy visual judgment of authenticity. is there.

[0002]

2. Description of the Related Art Conventionally, a display in which a diffraction grating pattern is formed by arranging a plurality of fine diffraction grating dots on a surface of a flat substrate has been used.

However, this type of conventional display is a collection of surface relief type diffraction gratings. Therefore, for example, it is theoretically not impossible to forge by a contact exposure method or a method of taking a mold of a relief pattern, and there is a risk of forgery.

On the other hand, holograms or diffraction grating patterns for mechanically reading recorded data by knowing the direction of diffracted light have been used.

However, since this type of hologram is a surface relief type hologram or a diffraction grating pattern having a relatively shallow depth, the diffraction efficiency cannot be increased so much, and a highly sensitive light receiving element is required. It

Further, when an observer who does not have sufficient knowledge of a diffraction grating or a hologram observes the diffraction grating pattern as described above, only a glittering pattern of various colors is recognized, and the same phenomenon is observed. As long as it has an effect, it is not different even if it is not a diffraction grating pattern.

Therefore, especially when used for security purposes, there is a problem regarding the forgery prevention effect and the authenticity determination.

[0008]

As described above, in the conventional diffraction grating pattern, not only is there a risk of forgery, but an observer who does not have sufficient knowledge of the diffraction grating or hologram etc. There is a problem that it is difficult to make a false decision.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to improve security and prevent forgery by an optical method, and at the same time, anyone can very easily visually judge the authenticity. It is an object of the present invention to provide a diffraction grating pattern composed of a volume phase type holographic grating capable of performing, a display and an article having the same.

[0010]

In order to achieve the above object, first, in the invention described in claim 1, a plurality of fine diffraction grating dots are arranged side by side on the surface of a flat substrate. In the diffraction grating pattern formed by
Each minute diffraction grating is a volume phase holographic grating having angle dependence and wavelength dependence, and the spatial frequency and angle of the diffraction grating are changed for each dot of each minute diffraction grating.

Further, in the invention described in claim 2, in the diffraction grating pattern formed by arranging a plurality of dots of the minute diffraction grating on the surface of the planar substrate, each minute diffraction grating is formed. At least one of them is a real image reproduction type hologram, and each of the remaining minute diffraction gratings is a volume phase holographic grating having angle dependence and wavelength dependence, and a minute volume consisting of the volume phase holographic grating. The spatial frequency and the angle of the diffraction grating are changed for each dot of the diffraction grating.

Furthermore, a third aspect of the present invention is characterized in that the volume phase type holographic device has a diffraction grating pattern comprising the volume phase type holographic grating according to the first or second aspect of the present invention by sticking or scissoring. An article having a diffraction grating pattern composed of a graphic grating.

Here, in particular, the diffraction angle of the light diffracted by the dots of at least one of the minute diffraction gratings is recorded so as to correspond to a certain data pattern.

[0014]

Therefore, in the diffraction grating pattern composed of the volume phase holographic grating of the present invention, and the display and the article having the same, each minute diffraction grating is used as a volume phase holographic grating, and each minute diffraction grating By changing the spatial frequency and angle of the diffraction grating for each dot, it is not possible to take a relief pattern model, and the wavelength and angle at which diffraction occurs for each minute dot are different, so forgery is required. Becomes extremely difficult.

Further, by embedding at least one of the minute diffraction gratings as a real image reproducing hologram and embedding the real image reproducing hologram in the diffraction grating pattern, anyone can very easily visually judge the authenticity. Can be done.

Furthermore, since the diffraction efficiency can be increased by using a volume phase holographic grating for each minute diffraction grating, a highly sensitive light receiving element is not required.

Furthermore, by recording the diffraction angle of the light diffracted by the dots of at least one of the minute diffraction gratings so as to correspond to a certain data pattern, the above-mentioned security is improved. With the improvement of
Machine reading of recorded information can be performed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a plan view showing a structural example of a diffraction grating pattern according to the present invention.

That is, the diffraction grating pattern of the present embodiment is formed by arranging a plurality of circular dots of a minute diffraction grating side by side on the surface of a flat substrate 1, as shown in FIG. In the diffraction grating pattern, each minute diffraction grating is a volume phase type holographic grating 2 which records interference fringes in the depth direction and has angle dependence and wavelength dependence. Further, for each dot of each minute diffraction grating, as shown in FIG. 2, for example, the spatial frequency and angle of the diffraction grating are changed (different).

Next, in the diffraction grating pattern of the present embodiment configured as described above, each minute diffraction grating is the volume phase holographic grating 2, and the diffraction grating is formed for each dot of each minute diffraction grating. It is extremely difficult to forge because the spatial frequency and angle of are changed.

That is, since the volume phase holographic grating 2 is not a relief pattern but an interference fringe is recorded inside the recording material, the relief pattern cannot be formed and can be forged. It is impossible.

Further, the volume phase holographic grating 2 has an angle dependency and a wavelength dependency like the multilayer film used for an interference filter or the like, and the angle determined by the spatial frequency and angle of the diffraction grating. Diffraction does not occur unless the wavelength is determined by. Therefore, as shown in FIG. 2, when a large number of minute diffraction gratings having different spatial frequencies and angles are arranged for each dot, diffraction occurs for each minute dot, that is, the reproducible wavelength and angle are different. .

For this reason, in addition to the original display effect of shining in various colors, there are a large number of dots that do not cause diffraction even if an attempt is made to counterfeit by a contact exposure method as in the conventional case, that is, a certain dot is reproduced. Even if it is possible, the dots next to it cannot be reproduced because they have different reproduction angles, and they have the effect that they cannot be forged.

Therefore, in addition to the effect of the original diffraction grating pattern as a display, the security can be further improved by the angle dependence and wavelength dependence of the volume phase holographic grating 2.

As described above, in this embodiment, in the diffraction grating pattern formed by arranging a plurality of circular dots of a minute diffraction grating on the surface of the flat substrate 1, each minute pattern is formed. The diffraction grating is a volume phase type holographic grating 2 having interference fringes recorded in the depth direction and having angle dependence and wavelength dependence, and for each dot of each minute diffraction grating, the spatial frequency of the diffraction grating and The angle is changed (different).

Therefore, the relief pattern cannot be formed, and the wavelength and the angle at which diffraction occurs are different for each minute dot, so that it is possible to reliably prevent forgery and security. It is possible to improve the sex.

Further, since each minute diffraction grating constituting the diffraction grating pattern is the volume phase type holographic grating 2 having angle dependency and wavelength dependency,
Diffraction efficiency can be increased, and a highly sensitive light receiving element as in the past is not required.

Further, even if multiple exposures of several kinds of diffraction gratings are carried out on one minute diffraction grating, the diffraction efficiency does not decrease so much, so that the data storage capacity can be increased.

Next, the second embodiment of the present invention will be described in detail.

FIG. 3 is a plan view showing another example of the structure of the diffraction grating pattern according to the present invention, and the same elements as those in FIG. 1 are designated by the same reference numerals.

That is, the diffraction grating pattern of the present embodiment is formed by arranging a plurality of circular dots of a minute diffraction grating side by side on the surface of a flat substrate 1, as shown in FIG. In the diffraction grating pattern, at least one (four in this example) of the minute diffraction gratings is used as the real image reproducing hologram 3, and the remaining minute diffraction gratings record interference fringes in the depth direction. The volume phase holographic grating 2 having the above angle dependency and wavelength dependency is used. In addition, the spatial frequency and angle of the diffraction grating are changed (different) for each dot of the minute diffraction grating including the volume phase holographic grating 2 as in the case of FIG.

Next, in the diffraction grating pattern of this embodiment configured as described above, each minute diffraction grating is the volume phase holographic grating 2, and the diffraction grating is formed for each minute diffraction grating dot. Since the spatial frequency and angle of are changed, similar to the above case, in addition to the original display effect of shining in various colors, even if the counterfeiting is attempted by the conventional contact exposure method, the diffraction There is a large number of dots that do not generate, that is, even if a certain dot can be reproduced, the adjacent dot cannot be reproduced because the reproduction angle is different, and thus it cannot be forged.

Furthermore, since at least one of the minute diffraction gratings is the real image reproducing hologram 3, laser light is irradiated to form an image or character for authenticity determination at a position apart from the diffraction grating pattern. By forming an image, even an observer who does not have sufficient knowledge of a diffraction grating, a hologram, etc. can easily make a true / false decision.

That is, when observing a normal diffraction grating pattern under general illumination such as a fluorescent lamp or an incandescent lamp,
It just looks like a lot of dots of various colors. Therefore, if an observer who does not have sufficient knowledge of the diffraction grating or hologram, it is difficult to determine whether the diffraction grating pattern is true or false, whether it is due to the diffraction of light or not. .

In this respect, the diffraction grating pattern of this embodiment is
As shown in FIG. 3, four of the minute diffraction gratings constituting the diffraction grating pattern are made into a real image reproducing hologram 3 for reproducing a real image such as a plane image or a character at a position distant from the diffraction grating pattern. When laser light is incident on a position of a minute hologram from a predetermined angle, an image or a character that an ordinary observer can easily make a genuine / counterfeit judgment appears. Since the position of the reproduced image is farther from the hologram surface in such a hologram, the image is greatly blurred under ordinary illumination, and it looks like other diffraction gratings, but from a specific angle, a single image like a laser beam appears. When illuminated with light of one wavelength, images and characters are reproduced.

As a result, when the authenticity determination device having the structure as shown in FIG. 4 is used, for example, an image or a character recorded in the diffraction grating pattern appears on the screen, and the authenticity determination can be easily performed. In FIG. 4, 5 is a laser light source, 6 is a screen, and 7 is a diffraction grating pattern.

As described above, in this embodiment, in the diffraction grating pattern formed by arranging a plurality of circular dots of a minute diffraction grating on the surface of the flat substrate 1, each minute pattern is formed. Four of the diffraction gratings are real image reproducing holograms 3, and the remaining minute diffraction gratings are recorded with interference fringes in the depth direction, and the volume phase holographic grating has angle dependence and wavelength dependence. 2 and the spatial frequency and angle of the diffraction grating are changed for each dot of the minute diffraction grating composed of the volume phase holographic grating 2.

Therefore, the relief pattern cannot be formed, and the wavelength and the angle at which diffraction occurs are different for each minute dot, so that it is possible to reliably prevent forgery and security. It is possible to improve the sex.

Further, since each minute diffraction grating constituting the diffraction grating pattern is the volume phase type holographic grating 2 having angle dependence and wavelength dependence,
Diffraction efficiency can be increased, and a highly sensitive light receiving element as in the past is not required.

Further, even if multiple exposures of several kinds of diffraction gratings are carried out on one minute diffraction grating, the diffraction efficiency does not decrease so much, so that the data storage capacity can be increased.

Furthermore, since at least one of the minute diffraction gratings is used as the real image reproducing hologram 3 and the real image reproducing hologram 3 is embedded in the diffraction grating pattern, it is very easy for anyone to visually see. It is possible to make a false decision.

The present invention is not limited to the above embodiment, but can be implemented in the same manner as described below.

(A) In the diffraction grating pattern of each embodiment shown in FIG. 1 or FIG. 3, the diffraction angle of light diffracted by at least one diffraction grating dot of each minute diffraction grating is By recording the data so as to correspond to the data pattern, it is possible to improve the security as described above and enable the machine reading of the recorded information.

That is, for example, E, W, S, and N are 4
When recording two continuous data in the diffraction grating pattern, as shown in FIG. 5, the diffracted light is in the right direction in the first dot, the diffracted light is in the left direction in the second dot,
The diffraction grating is recorded so that the diffracted light is directed downward in the third dot and the diffracted light is directed upward in the fourth dot. The data recorded in this diffraction grating pattern can be read by using, for example, an information reading device having a configuration shown in FIG. In FIG. 6, 8a, 8b, 8
Reference numerals c and 8d denote light receiving elements, and 9 denotes a light emitting element.

In this case, the light receiving element 8a receives data E, the light receiving element 8b receives data W, the light receiving element 8c receives data S,
By determining that the light receiving element 8d reads the data N, the recorded data EWSN can be mechanically read by the direction of the diffracted light.

In this way, the diffraction angle of the light diffracted by the dots of at least one diffraction grating of each minute diffraction grating is recorded so as to correspond to a certain data pattern, and the data is read by a machine. As a result, in addition to the effect of a data memory, it is possible to make a genuine / counterfeit judgment by a machine and enhance security. In addition to this, by using each of the minute diffraction gratings that form the diffraction grating pattern as the volume phase holographic grating 2, it becomes possible to increase the diffraction efficiency, and a highly sensitive light receiving element as in the past can be obtained. do not need.

(B) In the above embodiment, the case where the dots of the minute diffraction grating have a circular shape has been described.
It is needless to say that the shape is not limited to this, and may be, for example, a bar shape as shown in FIG. 7, or other shapes such as a triangular shape, a quadrangular shape, and a star shape.

(C) A product (for example, a credit card) or an article such as a product having the diffraction grating pattern of each embodiment shown in FIG. 1 or FIG. 3 by sticking or scissoring for the purpose of display or security. By doing so, it is extremely advantageous for the forgery prevention effect and the authenticity determination, especially when used for security purposes.

[0050]

As described above, according to the present invention, in a diffraction grating pattern formed by arranging a plurality of dots of a minute diffraction grating on the surface of a flat substrate, each minute diffraction pattern is formed. The grating is a volume phase holographic grating with angle dependence and wavelength dependence, and the spatial frequency and angle of the diffraction grating are changed for each dot of each minute diffraction grating. Since at least one of the minute diffraction gratings is a real image reproduction type hologram, it is possible to improve security and prevent forgery by an optical method.
It is possible to provide a diffraction grating pattern composed of a volume phase holographic grating, a display having the same, and an article having the same, which anyone can very easily visually judge whether or not they are true or false.

[Brief description of drawings]

FIG. 1 is a plan view showing a first embodiment of a diffraction grating pattern according to the present invention.

FIG. 2 is a diagram showing an example in the first embodiment.

FIG. 3 is a plan view showing a second embodiment of the diffraction grating pattern according to the present invention.

FIG. 4 is a diagram showing an example in the second embodiment.

FIG. 5 is a principal part diagram showing a third embodiment of the diffraction grating pattern according to the present invention.

FIG. 6 is a diagram showing an example of the third embodiment.

FIG. 7 is a plan view showing another example of the shape of the dots of the diffraction grating in the diffraction grating pattern according to the present invention.

[Explanation of symbols]

1 ... Planar substrate, 2 ... Volume phase holographic grating, 3 ... Real image reproducing hologram, 5 ... Laser light source, 6 ... Screen, 7 ... Diffraction grating pattern, 8a
8d ... light receiving element, 9 ... light emitting element.

Claims (5)

[Claims] 1. A diffraction grating pattern formed by arranging a plurality of dots of a minute diffraction grating side by side on a surface of a flat substrate, wherein each of the minute diffraction gratings has angular dependence or wavelength dependence. A diffraction grating pattern comprising a volume phase type holographic grating, wherein the volume phase type holographic grating is changed, and the spatial frequency and angle of the diffraction grating are changed for each dot of each minute diffraction grating. 2. A diffraction grating pattern formed by arranging a plurality of dots of a minute diffraction grating side by side on a surface of a planar substrate, wherein at least one of the minute diffraction gratings is reproduced as a real image. Type hologram, and each of the remaining minute diffraction gratings is a volume phase holographic grating having angle dependence and wavelength dependence, and for each dot of the minute diffraction grating composed of the volume phase holographic grating. A diffraction grating pattern composed of a volume phase holographic grating, characterized in that the spatial frequency and angle of the diffraction grating are changed. 3. A diffraction grating pattern composed of a volume phase holographic grating, characterized in that the diffraction grating pattern composed of the volume phase holographic grating according to claim 1 or 2 is attached or held by scissors. Goods. 4. The diffraction angle of the light diffracted by the dots of at least one diffraction grating of the respective minute diffraction gratings,
The diffraction grating pattern comprising the volume phase holographic grating according to claim 1 or 2, wherein the diffraction grating pattern is recorded so as to correspond to a certain data pattern. 5. The diffraction angle of the light diffracted by the dots of at least one diffraction grating of the respective minute diffraction gratings,
An article having a diffraction grating pattern composed of the volume phase holographic grating according to claim 3, wherein the article is recorded so as to correspond to a certain data pattern.