JP2005049605A - Hologram with recorded three-dimensional image whose shape is different according to viewing direction - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hologram recorded in such a way that, for example, a specified shape can be observed when viewed from a regular observation direction and another shape can be observed or a meaningless shape is observed when viewed from another observation direction different from the regular direction. <P>SOLUTION: The hologram for reconstructing three-dimensional images is recorded in such a way that three-dimensional images can be observed as a specified shape 21 as a whole in observation from a prescribed direction, and in observation from another direction different from the prescribed direction, three-dimensional images 11 can be reconstructed by which another specified shape is observed or a shape from which the specified shape 21 is difficult to recognize is observed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hologram in which a stereoscopic image having a different shape depending on the viewing direction is recorded, and in particular, a specific stereoscopic shape can be observed only when viewed from a specific direction, and is different when viewed from a different direction. The present invention relates to a hologram recorded such that a specific three-dimensional shape is observed or a meaningless three-dimensional shape is observed. For example, the present invention relates to a hologram that can be used as authentication information.

  Conventionally, there has been known a forgery preventing means for recording authentication information by printing so fine that it cannot be copied by a copying machine. However, since the fine pattern can be copied by improving the performance of the copying machine, it does not function as a forgery prevention means.

  Thereafter, a technique (Patent Document 1) for forming a fine pattern by a diffraction grating, which cannot be copied by a normal copying machine, was devised. If this technology is used, since it is possible to record authenticity determination information having such a size that the shape cannot be recognized with the naked eye, it is still used as a forgery prevention means.

  However, since a device for recording a fine diffraction grating is becoming available at a low cost, it is considered that a fine pattern by the diffraction grating will not function as authentication information in the future.

  By the way, a computer-generated hologram (CGH) capable of reproducing a three-dimensional image is conventionally known, and there are roughly two methods for creating such a CGH, one of which is non-patent literature 1, 2, etc. This is a method of replacing the object surface known by the above with a set of point light sources. The other is a holographic stereogram method known from Patent Document 2, Non-Patent Document 3, and the like.

  Here, as a representative example, a method of replacing the former object surface with a set of point light sources will be described.

  As an example of CGH, an outline of a binary hologram in which the intensity distribution of interference fringes is recorded and the reproduced image has only a horizontal parallax and is observed with white light from above will be described with reference to FIG. In step ST1, the shape of the object to be converted to CGH is defined. Next, in step ST2, the spatial arrangement of the object, the CGH surface, and the reference light is defined. Next, in step ST3, the object is vertically divided by slicing on a horizontal plane, and further replaced with a set of point light sources on the slice plane. Then, in step ST4, based on these spatial arrangements, the intensity of interference fringes between the light reaching from each point light source constituting the object and the reference light is obtained by calculation at each sample point defined on the CGH plane. Interference fringe data is obtained. Next, in step ST5, the obtained interference fringe data is quantized, and then converted into EB drawing rectangular data in step ST6. In step ST7, the data is recorded on the medium by the EB drawing apparatus to obtain CGH. .

  When calculating the interference fringes, hidden surface removal processing is performed. This hidden surface erasure process is a process of making the portion hidden behind the front object invisible when observing the object from a certain viewpoint, and this process adds information on the overlap of the object to the retinal image, This is a process capable of obtaining a three-dimensional effect, and in the case of CGH recording, a hidden surface removal process is performed by the following procedure.

  As shown in FIG. 4, for each point light source constituting the object 1, a region (hatched portion in FIG. 4) where the point light source is hidden by the objects 1 and 2 is obtained. In the case of the CGH created by the procedure of FIG. 3, the objects 1 and 2 are sliced in the horizontal plane and have parallax only in the horizontal direction. The area is obtained by the positional relationship between the points and the line segments on each slice plane. When the interference fringe sample points distributed on the CGH plane are included in the area where the point light source obtained above is hidden (black circle in FIG. 4), the point light source is calculated for the interference fringe intensity at the sample point. The hidden surface removal process is excluded from the target. From the image of the object 1 reproduced by the CGH subjected to such processing, when the reproduction light is not diffracted in the shaded portion in FIG. 4 and the observer's viewpoint enters the area, it corresponds to the point light source. The area of the object 1 is hidden by the image of the object 2 and cannot be seen.

  In addition, in GGH by the method of replacing such an object surface with a set of point light sources, an apparatus that reproduces color when reproduced with white light is proposed in Patent Document 3.

  In view of these circumstances, the present inventor has placed a minute object, which is authenticity information, in a hologram that reproduces a stereoscopic image behind a shielded object of a size that is easily recognizable with the naked eye. A hologram with high anti-counterfeiting effect was devised, in which information is shielded by a shielding object and cannot be observed, and is recorded so as to be observable from another direction different from the predetermined direction (Japanese Patent Application No. 2001-365628 (Japanese Patent Application No. 2002-2002)). 299874)). In this Japanese Patent Application No. 2001-365628 (Japanese Patent Application No. 2002-299874), fine authentication information is arranged behind a shielded object of a size that can be easily recognized by the naked eye, so that the hologram is illuminated with an appropriate light source. The use of magnified observation means such as a loupe from an appropriate observation direction makes it possible to observe the authenticity determination information for the first time, thereby providing a hologram with a high forgery prevention effect.

Further, Patent Document 4 discloses a method in which a laser beam is incident on a hologram, the reflected or transmitted light is projected as a specific pattern on the screen, and the authenticity is determined by confirming the pattern. Has been.
Registered Utility Model No. 2,582,857 Japanese Patent No. 3,155,263 JP 2000-214751 A Japanese Patent Laid-Open No. 58-200305 “Image Lab” April 1997 (Vol.8, No.4) 34-37 "3D Image Conference '99 -3D Image Conference '99-" Lecture Collection CD-ROM (June 30-July 1, 1999 at Kogakuin University Shinjuku Campus) 3)-Improvement of stereoscopic effect by hidden surface removal and shading- "The 3rd Hodic Lecture Lecture Collection" (November 15, 1996, Nihon University Surugadai Campus Building No. 1 Second Conference Room), " Acceleration of 2D image sequence generation for holographic stereograms "

  However, in order to confirm the conventional authentication information, an auxiliary tool for observing the authentication information such as a laser beam or a loupe is required, and simple authentication cannot be performed without using an observing tool. There's a problem.

  The present invention has been made in view of such problems of the prior art, and the object thereof is to observe a specific shape (figure) when viewed from the normal observation direction, for example, and different from that direction. To provide a recorded hologram so that another shape (figure) can be observed or a meaningless shape is observed when viewed from the observation direction, for example, using a special observation aid It is possible to provide a hologram which is recorded so as to be able to judge authenticity without any problem and has a high anti-counterfeit effect.

  The hologram in which a stereoscopic image having a different shape depending on the viewing direction of the present invention that achieves the above object is recorded is a hologram that reproduces a stereoscopic image, and when viewed from a predetermined direction, the stereoscopic image can be observed as a specific shape as a whole. When observed from another direction different from the predetermined direction, a stereoscopic image is recorded so as to be reproducible so that another specific shape is observed or a shape in which the specific shape is difficult to recognize is observed. It is what.

  In this case, the stereoscopic image is composed of a number of partial stereoscopic shapes, and in the observation from the predetermined direction, the large number of partial stereoscopic shapes can be observed as a specific shape as a whole and observed from a different direction different from the predetermined direction. In this case, another specific shape may be observed as a whole of the many partial solid shapes, or a shape that is difficult to recognize the specific shape may be observed.

  In addition, the hologram in which a stereoscopic image having a different shape depending on the viewing direction according to the present invention may be recorded as a computer-generated hologram.

  The specific shape may be a character form.

  The predetermined direction is preferably a direction other than the front surface of the hologram.

  In that case, it is desirable that the predetermined direction is in the range of 10 ° to 30 ° from the front of the hologram.

  When the three-dimensional image is configured with a large number of partial stereoscopic shapes, it is desirable that the multiple partial stereoscopic shapes are arranged so as not to overlap each other when observed from at least the predetermined direction.

  In addition, the hologram in which the stereoscopic image having a different shape depending on the viewing direction of the present invention is recorded can be observed in the second specific shape in a second predetermined direction different from the predetermined direction in which the specific shape can be observed. It can also be.

  The hologram on which a three-dimensional image having a different shape depending on the viewing direction according to the present invention can be used by being attached to a card or a document, for example.

  As is clear from the above description, according to the hologram in which a stereoscopic image having a different shape depending on the viewing direction of the present invention is recorded, the stereoscopic image can be observed as a specific shape as a whole when viewed from a predetermined direction. When observing from a different direction, a stereoscopic image in which another specific shape is observed or a shape in which the specific shape is difficult to recognize is recorded reproducibly. It is difficult to notice the existence of a record of a specific shape, and the specific shape as authentication information can be confirmed with the naked eye without using a special authentication information observation aid such as a laser beam or a loupe. Therefore, it is possible to achieve both high confidentiality of the authenticity determination information and easy confirmation of the authenticity determination information, and it is possible to provide a hologram with a high forgery prevention effect.

  Hereinafter, the basic principle and examples of a hologram in which a stereoscopic image having a different shape depending on the viewing direction of the present invention is recorded will be described.

  The hologram in which a stereoscopic image having a different shape depending on the viewing direction of the present invention is recorded can be observed as a specific shape (figure) as a whole when viewed from a predetermined direction, and observed from a different direction different from the predetermined direction. In some cases, it is recorded so that another specific shape (graphic) can be observed or a meaningless shape is observed. For example, a large number of cubes are distributed in a three-dimensional space, and a specific observation is performed. It is a hologram that gradually appears in a specific shape as it approaches the direction.

  Hereinafter, such a hologram of the present invention will be described based on its principle. As will be described later, the hologram of the present invention can also be created by a normal hologram photographing method, but is created by computer synthesis. First, a computer-generated hologram (CGH) will be described.

  A method for creating CGH is well known (for example, see Non-Patent Document 2). As an example of CGH, a binary hologram that records the intensity distribution of interference fringes, and a reproduced image has only a horizontal parallax, An outline of the case of observation with white light from above will be described. As shown in FIG. 3, in step ST1, 3D-CAD for computer graphics is used to observe the entire stereoscopic image in observation from a predetermined direction. Can be observed as a specific shape, and when viewed from another direction different from the predetermined direction, a three-dimensional object (3D object) in which another shape can be observed or a meaningless shape is observed is created and converted to CGH The shape of the object to be defined is defined. Next, in step ST2, the spatial arrangement of the 3D object, the CGH surface, and the reference light is defined. Next, in step ST3, the 3D object is divided in the vertical direction by slicing on the horizontal plane, and further replaced with a set of point light sources on the slice plane, and while performing the hidden surface removal processing of FIG. Based on the spatial arrangement, the interference fringe intensity between the light and the reference light arriving from each point light source constituting the 3D object is obtained by calculation at each sample point defined on the CGH plane, and interference fringe data is obtained. It is done. Next, after the obtained interference fringe data is quantized in step ST5, it is converted into EB drawing rectangular data in step ST6, and is recorded on the medium by the EB drawing apparatus in step ST7. A hologram in which a three-dimensional image having a different shape depending on the viewing direction according to the present invention is obtained, which is composed of CGH created by using a method of replacing a light source with a set of point light sources.

  In the above observation from the predetermined direction, the stereoscopic image can be observed as a specific shape as a whole, and when observing from a different direction different from the predetermined direction, another specific shape can be observed or a meaningless shape is observed. As a specific example of the 3D object, a partial solid shape group 11 including a large number of partial solid shapes 12a, 12b, 12c,... Is arranged as shown in the perspective view of FIG. Each of these partial solid shapes 12a, 12b, 12c,... Has a rectangular parallelepiped shape in the case of FIG. These partial solid shapes 12a, 12b, 12c,... Are arranged so as not to contact each other in the three-dimensional space, and when the partial solid shape group 11 is observed from the viewpoint direction of FIG. As you can see, it is impossible to observe any meaningful figure as a whole.

  FIG. 2 shows an image when the same partial solid shape group 11 as in FIG. 1 is observed from a plurality of directions. Among these, in the case of FIG. 2B observed from a specific direction, the partial solid shape group 11 which is a set of a large number of partial solid shapes 12a, 12b, 12c,. Can be observed. In FIG. 2B, the character form “1” is used as the specific shape 21. On the other hand, the character form “1” cannot be observed in FIG. 2A in which the partial three-dimensional shape group 11 is observed from a slightly left side of the direction of FIG. Further, the character form “1” cannot be observed even in FIG. 2C in which the partial solid shape group 11 is observed from the right side of the direction of FIG.

  As described above, in the present invention, as a 3D object to be recorded on a hologram capable of reproducing a stereoscopic image, the stereoscopic image can be observed as a specific shape (figure) as a whole when viewed from a predetermined direction, and is different from the predetermined direction. When observed from the direction, a 3D object in which another specific shape (figure) can be observed or a meaningless shape is observed is used. An example of such a 3D object will be described below.

  5A, as shown in FIG. 5A, a specific shape (figure) 32 is projected onto one surface of the rectangular parallelepiped 31 with parallel light, and a portion according to the projected image is cut out from the rectangular parallelepiped 31 and FIG. In a hologram in which such a 3D object 33 is recorded as a three-dimensional image, it corresponds to the normal direction of the surface on which the specific shape (figure) 32 of the cuboid 31 is projected. The specific shape (graphic) can be observed only when viewed from the direction to be performed, in this example, the character form “1” can be observed, and the specific shape cannot be observed from other directions.

  In the example of FIG. 5, the rectangular parallelepiped 31 is formed by three-dimensionally stacking a large number of partial rectangular parallelepipeds 12, and the 3D object 33 cut out from the rectangular parallelepiped 31 is quantized by the partial rectangular parallelepiped 12 and has irregular jaggedness. It is a character that is bordered by various plane groups.

  In FIG. 6, as shown in FIG. 6A, a large number of partial rectangular parallelepipeds 12 are arranged vertically and horizontally (xy plane) to form one partial rectangular parallelepiped group 34, and a specific shape (figure) is formed in the one partial rectangular parallelepiped group 34. Only the partial rectangular parallelepiped 12 ′ of the projected portion is colored, and then, as shown in FIG. 6B, each of the partial rectangular parallelepipeds 12 and 12 ′ constituting each row (x direction) in the partial rectangular parallelepiped group 34 is displayed. A 3D object 35 as shown in FIG. 6C is moved by moving the partial rectangular parallelepiped 12 by a random unit distance in the depth direction (z direction) orthogonal to the layer of the partial rectangular parallelepiped group 34 as one unit. In a hologram in which such a 3D object 35 is recorded as a three-dimensional image, the color is changed only when viewed from a direction corresponding to the normal direction (z direction) of the surface of the partial rectangular parallelepiped group 34. The attached partial rectangular parallelepiped 12 ' Its particular shape as the body (figure), can also observe the character form "1" In this example, the particular shape becomes unobservable from other directions.

  In the 3D object 35 in the example of FIG. 6C, if only the colored partial rectangular parallelepiped 12 ′ is left and the other partial rectangular parallelepiped 12 is removed, a 3D object 36 ′ as shown in FIG. 7 is obtained. 1 is the same as the partial solid shape group 11 of FIG. 1, and as shown in FIGS. 2A to 2C, only when viewed from a specific direction, the character form “1” of the specific shape (figure). Can be observed, and the specific shape cannot be observed from other directions.

  8 and 9, as shown in FIGS. 8A and 9A, a first specific shape (graphic) 37 is perpendicular to one surface (xy surface) of the rectangular parallelepiped 36 (z direction). The second specific shape (graphic) 38 is projected on another surface (yz surface) orthogonal to the surface (xy surface) on which the first specific shape (graphic) 37 of the rectangular parallelepiped 36 is projected. Projecting with parallel light (x direction) perpendicular to the surface, and cutting out a portion according to the projection images orthogonal to each other from the rectangular parallelepiped 36, a 3D object 39 as shown in FIGS. 8B and 9B is obtained. In the hologram in which such a 3D object 39 is recorded as a stereoscopic image, the normal direction (z direction) of the plane (xy plane) on which the first specific shape (graphic figure) 37 of the rectangular parallelepiped 36 is projected is an example. When viewed from the direction corresponding to the first specific shape (graphic), in this example, the character form “2” is From the direction corresponding to the normal direction (x direction) of the surface (yz plane) on which the second specific shape (graphic figure) 38 of the rectangular parallelepiped 36 is projected (FIG. 8C, FIG. 9C). When viewed, the second specific shape (graphic), in this case, the character form “1” can be observed (FIGS. 8 (g) and 9 (g)), and any of the two directions can be observed. Even from the direction, those specific shapes cannot be observed (FIGS. 8D to 8F and FIGS. 9D to 9F). Here, FIG. 8D and FIG. 9D are shown in FIG. 8G by 22.5 ° with respect to the observation direction (z direction) in the case of FIG. 8C and FIG. FIG. 8 (e) and FIG. 9 (e) are the same as the case of FIG. 8 (c) and FIG. 9 (c). 8 (g) and FIG. 9 (g), when viewed from an intermediate observation direction. FIGS. 8 (f) and 9 (f) are the cases of FIGS. 8 (g) and 9 (g). FIG. 8C and FIG. 9C are observation images in the case of being close to the observation direction (z direction) in the case of FIG. 8C and FIG.

  In the case of FIG. 8, the shape according to the projection image cut out from the rectangular parallelepiped 36 is a character bordered by an analog curve, whereas in the case of FIG. 9, the rectangular parallelepiped 36 is a portion similar to the partial rectangular parallelepiped 12. It is a three-dimensional laminate of rectangular parallelepipeds, and the difference is that the portion cut out from the rectangular parallelepiped 36 is quantized by the partial rectangular parallelepiped and becomes a character bordered by orthogonal jagged straight line groups.

  Next, FIG. 10 does not cut out the 3D object 39 according to the specific shapes (figures) 37 and 38 projected from the two orthogonal directions as shown in FIGS. 8 and 9, but is orthogonal as in the case of FIG. This is an example of coloring according to specific shapes (figures) 37 and 38 projected from two directions. As a preparation stage, as in the case of FIG. 6A, a large number of partial rectangular parallelepipeds 12 are arranged vertically and horizontally (xy plane). Before forming the partial rectangular parallelepiped group 34 and coloring the partial rectangular parallelepiped group 34, as shown in FIG. 10A, the partial rectangular parallelepiped 12 constituting each row (x direction) in one partial rectangular parallelepiped group 34. Each of the partial rectangular parallelepiped groups 34 is moved by a random unit distance in the depth direction (z direction) orthogonal to the layer of the partial rectangular parallelepiped group 34, with the depth distance being one unit. Normal direction of group 34 (Z direction) Even when observed from a, or even when observed from a direction (x direction) b orthogonal to the direction and parallel to each row, no gap is visible between the plurality of partial rectangular parallelepipeds 12 in the row. The partial rectangular parallelepiped 12 is moved and arranged.

  When the partial rectangular parallelepiped 12 of the partial rectangular parallelepiped group 34 is moved and arranged in this way, as shown in FIG. 10B, when viewed from both specific observation directions a and b, the partial rectangular parallelepiped in which no gap is visible. A 3D object 40 consisting of 12 sets is obtained. In this state, a first specific shape (graphic) 37 is projected from the observation direction (z direction) a of the 3D object 40, and for example, a white color is applied only to the partial rectangular parallelepiped 12 corresponding to the first specific shape (graphic). Add. Further, the second specific shape (graphic) 38 is projected from the observation direction (x direction) b of the 3D object 40, and a black color is applied only to the partial rectangular parallelepiped 12 corresponding to the second specific shape (graphic). .

  In a hologram in which the 3D object 40 colored from two directions is recorded as a stereoscopic image, when viewed from the observation direction a, the first specific shape (graphic), in this example, the character form “2” ”Can be observed (FIG. 10D), and when viewed from the observation direction b, the second specific shape (graphic) can be observed. In this example, the character form“ 1 ”can be observed (FIG. 10H). ), The specific shape cannot be observed from any direction between the two directions (FIGS. 10E to 10G). Here, FIG. 10E shows a case where the observation direction b is close to the observation direction a by 22.5 °, and FIG. 10F shows an observation between the observation direction a and the observation direction b. FIG. 10G is an observation image when viewed from the observation direction b by 22.5 ° with respect to the observation direction b, both of which are “1” of a specific shape (figure). "And" 2 "are not visible.

  By the way, as shown in FIGS. 8 to 10, when different specific shapes (figures) are selectively visible only from two specific directions, the two directions are orthogonal to each other (90 °). However, in a hologram in which such 3D objects 39 and 40 are recorded as a three-dimensional image, in order to enable observation of the two specific shapes (figures) by changing the viewing angle, the viewing angle of the hologram is displayed. The area must include a range of at least ± 45 °.

  In order to narrow the viewing area so that two different specific shapes (figures) can be selectively seen even in a viewing area narrower than 90 °, for example 40 °, instead of the rectangular parallelepiped 36 and the partial rectangular parallelepiped 12, the smaller one is used. It is sufficient to use an oblique body with an apex angle of 40 ° and project the specific shapes (figures) 37 and 38 from two directions forming the smaller apex angle. An example will be described with reference to FIG. FIG. 11A is a diagram corresponding to FIG. 10A (the upper diagram in FIG. 11A shows the depth of the partial rectangular parallelepipeds 12 constituting each row in the one-layer partial rectangular parallelepiped group 34. When the elements constituting the 3D object 40 are configured by such a set of partial rectangular parallelepipeds 12, the directions are 90 ° to each other. Separate specific shapes (figures) can be seen only from a and b, but as shown in FIG. 11B, a partial rhomboid group is formed using a partial rhomboid 12 ″ instead of the partial rectangular parallelepiped 12. , If the projection directions a and b are mutually in a direction of 40 °, for example, the angular relationships in FIGS. 10 (d), (e), (f), (g) and (h) are −20 °, A holo recording such a 3D object as a stereoscopic image in directions of −10 °, 0 °, + 10 °, and + 20 °. Viewing zone of the ram is fully intended to include a range of ± 20 °.

  By the way, in the above description, in the description of FIGS. 1 to 2, 5 to 7, 9, and 10 to 11, the partial solid shape group 11, the 3D objects 33, 35, 36 ′, The partial solid shapes 12a, 12b, 12c,..., 12, 12 ′, 12 ″, etc. constituting 39, 40, etc. have been described as having a rectangular parallelepiped shape or a rectangular parallelepiped shape. It is good also as a thing of the shape of.

  Further, the arrangement of these partial three-dimensional shapes 12a, 12b, 12c,..., 12, 12 ′, 12 ″, etc., instead of arranging them in the vertical and horizontal depth directions as shown in these drawings, is shown in FIG. As illustrated in FIG. 5 (this figure is a two-dimensional arrangement), the arrangement may be shifted in one direction or two directions.

  The 3D objects 11, 33, 35, 36 ′, 39, 40, etc. exemplified as described above can be easily created using a three-dimensional CAD for computer graphics. When used as the above-described CGH object, in the case of FIGS. 1 to 2 and FIGS. 5 to 7, when observed from the front direction (z direction), a specific shape, for example, the character form “1” is used. A hologram that can be observed and cannot be observed as a specific shape when observed from a direction other than the front can be realized. In the case of FIGS. 8 to 10, when observed from the −45 ° direction (z direction), it can be observed as the first specific shape, for example, the character form “2”, and the + 45 ° direction (x When observed from the (direction), a hologram that can be observed as the second specific shape, for example, the character form “1”, and cannot be observed as the specific shape when observed from other directions can be realized. Furthermore, in the case of FIG. 11, when observed from the −20 ° direction, the first specific shape, for example, the character form “2” can be observed, and when observed from the + 20 ° direction, the second specific shape can be observed. It is possible to realize a hologram that can be observed as a specific shape, for example, the character form “1” and cannot be observed as a specific shape when observed from other directions. Therefore, by using these specific shapes as authenticity determination information, the hologram according to the present invention can be used as a hologram for preventing forgery.

  In the case of FIGS. 1 to 2 and FIGS. 5 to 7 in which the specific shape can be observed only from the above one direction, the front direction of the hologram is selected as the direction in which the specific shape can be observed. In order to improve the confidentiality of the image, it is desirable that the direction in which the specific shape can be observed be other than the front direction of the hologram. In this case, if the recorded 3D objects 11, 33, 35, and 36 ′ are rotated around the vertical line (y axis) and recorded, the specific shape that is the authenticity determination information cannot be observed in the front direction. The confidentiality of the authenticity determination information is increased and the forgery prevention effect is increased.

  In this case, if the angle at which the 3D object 11, 33, 35, 36 ′ is rotated about the y-axis is smaller than 10 °, when observing the hologram from the front of the hologram, a shape close to the specific shape is observed, and authenticity information The secrecy of is reduced. If the rotation angle is larger than 30 °, the angle of the diffracted light from the hologram becomes large, and it becomes difficult to observe the specific shape as a reproduced image of the hologram. Therefore, the angle for rotating the 3D object 11, 33, 35, 36 ′ around the y-axis is preferably between 10 ° and 30 °. For example, the specific shape can be observed in the vicinity of 15 °. be able to.

  Similarly, when different specific shapes can be observed from two different directions, each specific shape can be observed between ± 10 ° and ± 30 ° with respect to the front of the hologram (FIG. 11). It is desirable for the same reason.

  The specific shape can be observed only from one direction as exemplified in FIGS. 1 to 2 and FIGS. 5 to 7, and the specific shape can be observed from two directions as illustrated in FIGS. 8 to 11. In comparison with the case, the latter case has a higher anti-counterfeit effect because the specific shapes visible on the left and right sides are different.

  According to the above hologram of the present invention, it is possible to confirm the specific shape of the authentication information with the naked eye without using an auxiliary tool for observing the authentication information such as a laser beam or a loupe, and in a normal observation direction. For example, since it is difficult to notice the presence of the authentication information from the front of the hologram, it is possible to provide a hologram in which the authentication information can be easily confirmed while enhancing the confidentiality of the authentication information.

  In the above description, the object shape (3D) has been described as being created by three-dimensional CAD and the hologram is created by CGH. However, the 3D objects 11, 33, 35, 36 ′, 39, described so far have been described. Since a similar hologram can be recorded by a conventional hologram creating method in which 40 or the like is actually created as a model and is created by two-beam interference of laser light, the hologram of the present invention is not limited to CGH.

  In addition, since the same thing can be recorded by a stereogram created based on a large number of parallax images of computer graphics or a parallax image obtained by photographing a real object from many directions, the present invention creates a stereogram. Holograms (holographic stereograms) are also included.

  Such a hologram in which a three-dimensional image having a different shape depending on the viewing direction of the present invention is recorded and used on an object to be prevented from being counterfeited such as a card or a document. The effect can be demonstrated.

  The hologram of the present invention can be used not only for such anti-counterfeiting and authenticity determination, but also for graphic arts and toys.

  As described above, the hologram on which a three-dimensional image having a different shape depending on the viewing direction of the present invention has been described based on the principle and the examples. However, the present invention is not limited to these examples and can be variously modified.

It is a perspective view which shows the specific example of the three-dimensional object used in the hologram of this invention. It is a figure which shows the image at the time of observing the three-dimensional object of FIG. 1 from several directions. It is a flowchart for demonstrating the outline | summary of the preparation process of CGH by the method of replacing the object surface with the set of point light sources. It is a figure for demonstrating the hidden surface deletion process of CGH recording. It is a figure for demonstrating an example of the production method of the three-dimensional object which can observe a specific shape only from one direction. It is a figure for demonstrating another preparation method of the three-dimensional object which can observe a specific shape only from one direction. It is a figure for demonstrating the modification of the preparation method of FIG. 6 of the three-dimensional object which can observe a specific shape only from one direction. It is a figure for demonstrating an example of the production method of the three-dimensional object which can observe a different specific shape from two different directions. It is a figure for demonstrating the creation method similar to the creation method of FIG. It is a figure for demonstrating another preparation method of the three-dimensional object which can observe a different specific shape from two different directions. It is a figure for demonstrating the preparation method of the three-dimensional object for narrowing the angle of the two directions in preparation of the three-dimensional object which can observe a different specific shape from two different directions. It is a figure for demonstrating the modification of the arrangement | sequence method in the case of comprising many partial solid shapes and comprising a three-dimensional object.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Partial solid shape group 12 ... Partial rectangular parallelepiped 12a, 12b, 12c, ... Partial solid shape 12 '... Partial rectangular parallelepiped 12 "... Partial rhomboid 21 ... Specific shape 31 ... Rectangular solid 32 ... Specific shape (figure)
33 ... 3D object 34 ... partial rectangular parallelepiped group 35 ... 3D object 36 ... rectangular parallelepiped 36 '... 3D object 37 ... first specific shape (figure)
38 ... 2nd specific shape (figure)
39 ... 3D object 40 ... 3D object

Claims (10)

In a hologram that reproduces a three-dimensional image, when observing from a predetermined direction, the three-dimensional image can be observed as a specific shape as a whole, and when observing from another direction different from the predetermined direction, is another specific shape observed? A hologram on which a three-dimensional image having a different shape depending on a viewing direction is recorded, wherein a three-dimensional image in which a shape in which the specific shape is difficult to recognize is observed is recorded reproducibly. When the stereoscopic image is composed of a number of partial stereoscopic shapes, and the observation from the predetermined direction allows the multiple partial stereoscopic shapes to be observed as a specific shape as a whole, and when observed from a different direction different from the predetermined direction 2. The three-dimensional image having different shapes depending on the viewing direction according to claim 1, wherein a different specific shape is observed as a whole or a shape in which the specific shape is difficult to recognize is observed. Recorded hologram. 3. The hologram on which a three-dimensional image having a different shape depending on a viewing direction is recorded as a computer-generated hologram. 4. The hologram on which a three-dimensional image having a different shape depending on a viewing direction is recorded, according to any one of claims 1 to 3, wherein the specific shape is in a character form. 5. The hologram on which a stereoscopic image having a different shape depending on a viewing direction is recorded, according to any one of claims 1 to 4, wherein the predetermined direction is a direction other than the front of the hologram. 6. The hologram on which a stereoscopic image having a different shape depending on the viewing direction is recorded, wherein the predetermined direction is in a range of 10 [deg.] To 30 [deg.] From the front of the hologram. 7. The solid having different shapes depending on the viewing direction according to claim 2, wherein the plurality of partial solid shapes are arranged so as not to overlap each other when observed from at least the predetermined direction. Hologram with recorded image. The shape according to the viewing direction according to any one of claims 1 to 7, wherein the second specific shape is observable in a second predetermined direction different from the predetermined direction in which the specific shape is observable. Hologram in which three-dimensional images are recorded. 9. The hologram on which a three-dimensional image having a different shape is recorded depending on the viewing direction according to any one of claims 1 to 8, wherein the hologram is pasted on a card or a document. 9. A card or a document on which a hologram on which a three-dimensional image having a different shape is recorded depending on the viewing direction according to claim 1 is attached.

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