JP3912700B2 - Composite hologram - Google Patents

Composite hologram Download PDF

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Publication number
JP3912700B2
JP3912700B2 JP29376997A JP29376997A JP3912700B2 JP 3912700 B2 JP3912700 B2 JP 3912700B2 JP 29376997 A JP29376997 A JP 29376997A JP 29376997 A JP29376997 A JP 29376997A JP 3912700 B2 JP3912700 B2 JP 3912700B2
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Prior art keywords
hologram
angle
light
composite
recorded
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JPH11133232A (en
Inventor
西川真悟
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Dai Nippon Printing Co Ltd
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Dai Nippon Printing Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/328—Diffraction gratings; Holograms
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/0005—Adaptation of holography to specific applications
    • G03H1/0011—Adaptation of holography to specific applications for security or authentication
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/02—Details of features involved during the holographic process; Replication of holograms without interference recording
    • G03H1/024—Hologram nature or properties
    • G03H1/0248—Volume holograms
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/22—Processes or apparatus for obtaining an optical image from holograms
    • G03H1/2202—Reconstruction geometries or arrangements
    • G03H2001/2223—Particular relationship between light source, hologram and observer
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/26—Processes or apparatus specially adapted to produce multiple sub- holograms or to obtain images from them, e.g. multicolour technique
    • G03H2001/2605—Arrangement of the sub-holograms, e.g. partial overlapping
    • G03H2001/261—Arrangement of the sub-holograms, e.g. partial overlapping in optical contact
    • G03H2001/2615—Arrangement of the sub-holograms, e.g. partial overlapping in optical contact in physical contact, i.e. layered holograms

Description

【０００１】
【発明の属する技術分野】
本発明は、複合ホログラムに関し、特に、特定方向から特定波長の光が入射したのときのみ特定方向へ回折する複合ホログラムに関するものである。
【０００２】
【従来の技術】
従来から、ＣＤカード、プリペイドカード、定期券、通帳、パスポート、身分証明書、商品等が真実なもので偽造されたものでないことを保証するために、立体像、模様等を記録したレリーフホログラム又はリップマンホログラムからなるラベル、シール等を対象物に貼着することが広く行われている。
【０００３】
【発明が解決しようとする課題】
これらのホログラムは、単純な再生照明光あるいは白色光により再生可能であり、これを複製等の手法を用いて偽造することは必ずしも困難なことではない。そのため、このようなホログラムからなるラベル、シール等のセキュリティー性は必ずしも高いものではなかった。
【０００４】
本発明はこのような従来技術の問題点に鑑みてなされたものであり、その目的は、特定方向から特定波長の光が入射したのときのみ特定方向へ回折するホログラムであって、偽造防止ホログラム、狭帯域波長フィルター等の光学素子として使用可能な複合ホログラムを提供することである。
【０００５】
【課題を解決するための手段】
上記目的を達成する本発明の複合ホログラムは、一様な平面の干渉縞が記録された複数の体積型ホログラムが重畳されるか多重記録されてなる複合ホログラムであって、特定の入射角の特定の波長の光のみがこれら複数の体積型ホログラムを順にブラッグ回折して特定の出射角で出射するように、前記複数の体積型ホログラム各々の干渉縞のスラント角とピッチが設定されていることを特徴とするものである。
【０００６】
この場合、例えば２枚の体積型ホログラムが重畳されるか多重記録されてなるものとすることができる。
【０００７】
本発明の複合ホログラムは、例えば偽造防止ホログラムとして用いることができ、立体物、模様等の物体像が記録された体積型ホログラムの一部の所定パターン領域にのみその複数の体積型ホログラムを重畳するか多重記録して構成することもできる。
【０００８】
本発明の複合ホログラムは、また、高指向性狭帯域波長フィルターとして用いることができる。
【０００９】
本発明においては、特定の入射角の特定の波長の光のみが複数の体積型ホログラムを順にブラッグ回折して特定の出射角で出射するように、その複数の体積型ホログラム各々の干渉縞のスラント角とピッチが設定されているので、特定の入射角で特定の波長の光が入射したときのみ、特定の出射角でその光が回折し、他の入射角及び波長においてはその出射角の方向へ回折しないので、例えば偽造防止ホログラムとして有用であり、また、高指向性狭帯域波長フィルター等の光学素子として使用可能なものである。
【００１０】
【発明の実施の形態】
以下に、本発明の複合ホログラムの原理と実施例について説明する。
図１に断面を示すように、一様な平面の干渉縞３、４（フリンジ）が記録された２枚の体積型ホログラム１、２が重畳されいる場合を考える。図１においては、干渉縞３、４はそれぞれ１面しか図示していないが、実際には一定ピッチで平行に多数の干渉縞が形成されている。以下に、ホログラム１に入射した光５がホログラム１の干渉縞３でブラッグ回折を受け、その回折光が今度はホログラム２に入射してその干渉縞４でブラッグ回折を受け、再びホログラム１あるいはホログラム２から回折光６として出射する場合について検討する。
【００１１】
ホログラム１、２の干渉縞３、４の法線Ｎ’、Ｎ”が何れも図１の平面内にあるとし、また、ホログラム１、２の平均屈折率は同じｎとする。
ホログラム１の干渉縞のスラント角（ホログラム１の平面に対する角度）をθ、干渉縞のピッチ（隣接する干渉縞間の距離）をＰとする。
ホログラム２の干渉縞のスラント角をφ、干渉縞のピッチをＱとする。
空気中から入射角Ｉで入射した光５のホログラム１内での屈折角をＩ’で表す。
【００１２】
空気中からホログラム１の法線に対して入射角Ｉで入射した光５で、ホログラム１のフリンジ３の面にその法線Ｎ’から（Ｉ’−θ）の角度で入射し、ホログラム１の平面に垂直な法線Ｎから（２θ−Ｉ’）の角度で回折し、ホログラム２のフリンジ４の面にその法線Ｎ”から（π＋２θ−φ−Ｉ’）の角度で入射し、ホログラム１（２）の平面に垂直な法線Ｎから（２φ＋Ｉ’−２θ−π）の角度で回折し、空気中に屈折角Ｄで出射する光６を考える。
【００１３】
ホログラム１のブラッグ波長は、
（２Ｐ／ｎ）×ｃｏｓ（Ｉ’−θ） ・・・（１）
ホログラム２のブラッグ波長は、
（２Ｑ／ｎ）×ｃｏｓ（π＋２θ−φ−Ｉ’） ・・・（２）
である。この両波長が一致するときのみ光は上記のような回折を行う。
【００１４】
つまり、
Ｐｃｏｓ（Ｉ’−θ）＝−Ｑｃｏｓ（２θ−φ−Ｉ’） ・・・（３）
ここで、
Ａ＝（θ−φ）／２
Ｂ＝（２Ｉ’−３θ＋φ）／２
ｒ＝−Ｐ／Ｑ
とおくと、上記（３）式は次のように書ける。
【００１５】
ｒｃｏｓ（Ａ＋Ｂ）＝ｃｏｓ（Ａ−Ｂ） ・・・（４）
（ｒ−１）ｃｏｓＡｃｏｓＢ＝（ｒ＋１）ｓｉｎＡｓｉｎＢ・・・（５）
ｔａｎＢ＝（ｒ−１）／｛（ｒ＋１）ｔａｎＡ｝ ・・・（６）
ｔａｎ｛（２Ｉ’−３θ＋φ）／２｝
＝（−Ｐ−Ｑ）／［（−Ｐ＋Ｑ）ｔａｎ｛（θ−φ）／２｝］・（７）
Ｉ’＝ｔａｎ-1〔（Ｐ＋Ｑ）／［（Ｐ−Ｑ）ｔａｎ｛（θ−φ）／２｝］〕
＋（３θ−φ）／２ ・・・（８）
となる。
【００１６】
つまり、入射光５の入射角Ｉは、

Figure 0003912700
となる。
【００１７】
また、そのときのブラッグ波長λは、
λ＝（２Ｐ／ｎ）ｃｏｓ〈ｔａｎ-1〔（Ｐ＋Ｑ）／［（Ｐ−Ｑ）×
ｔａｎ｛（θ−φ）／２｝］〕＋（θ−φ）／２〉・・（10）
となり、回折光６の回折角Ｄは、
Ｄ＝−ｓｉｎ-1《ｎｓｉｎ〈ｔａｎ-1〔（Ｐ＋Ｑ）／［（Ｐ−Ｑ）×
ｔａｎ｛（θ−φ）／２｝］〕＋（３φ−θ）／２〉》・（11）
となる。
【００１８】
以上の検討より明らかなように、一様な平面状の干渉縞を記録した２枚の体積型ホログラムを重畳するか、あるいは、１枚のホログラム媒体中に多重記録することにより、２つの干渉縞により順次回折される回折波長は（１０）式を満たす特定の単波長であり、その際の（９）式を満たす入射角Ｉ、（１１）式を満たす回折角Ｄも特定の１つの値であることが分かる。なお、光線の可逆性から、入射角Ｉと回折角Ｄを入れ換えても良いから、このような複合ホログラムは、特定の入射角Ｉ又はＤで特定の波長λの光が入射したときのみ、特定の出射角Ｄ又はＩでその光が回折し、他の入射角及び波長においてはその出射角の方向へ回折しないことが分かる。なお、３枚以上の体積型ホログラムを重畳するか、あるいは多重記録したものも同様な解析によりこのような解が存在し得る。
【００１９】
実際の数値例を示す。図２はホログラム１の干渉縞のスラント角θが−５０°、そのピッチＰが７００ｎｍ、ホログラム２の干渉縞のスラント角φが６０°、そのピッチＱが８００ｎｍ、両ホログラム１、２の平均屈折率ｎが１．５２のときの、図１の構成の複合ホログラムの入射角Ｉに対する回折角（出射角）Ｄ（太い実線）、ホログラム１の入射角Ｉに対するブラッグ波長λ（▲角系列）、ホログラム２の入射角Ｉに対するブラッグ波長λ（◇系列）を示す。図２から、両ホログラム１、２で順番にブラッグ回折される波長λは、λ＝８０１．１５７９ｎｍ、入射角Ｉは、Ｉ＝３２．０５９０１°、回折角（出射角）Ｄは、Ｄ＝−３０．５９１８１°となる。この値は、上記（９）〜（１１）式から求めた値と一致する。なお、当然、入射角Ｉと出射角Ｄは入替え可能である。
【００２０】
図３はホログラム１の干渉縞のスラント角θが−４０°、そのピッチＰが７００ｎｍ、ホログラム２の干渉縞のスラント角φが４５°、そのピッチＱが８００ｎｍ、両ホログラム１、２の平均屈折率ｎが１．５２のときの、図２と同様の図であり、λ＝６６２．５０２７ｎｍ、入射角Ｉは、Ｉ＝６．０９２９３４°、回折角（出射角）Ｄは、Ｄ＝−９．１３５６２６°となる。この場合も、上記（９）〜（１１）式から求めた値と一致する。また、同様に入射角Ｉと出射角Ｄは入替え可能である。
【００２１】
さて、以上のような複合ホログラムは、特定の２つの方向の一方から入射した特定の狭い波長帯域の光のみをその特定の２つの方向の他方へ回折し、他の方向、波長の光は直通するなり全く別の方向へ回折する特性を有するが、このような複合ホログラムを複製等の手法で偽造することは極めて困難であるのと同時に、再生のために光源、読み取り受光素子を所定の厳密な相対位置、方向に配置しなければならない。したがって、このようなホログラムは、例えば偽造防止ホログラムとして有用なものである。偽造防止ホログラムとして用いる場合は、図１のような２層のホログラム１、２が重ねてなるホログラム媒体、あるいは、干渉縞３、４を多重記録してなる１層構成のホログラム媒体をそのまま用いて、ＣＤカード、プリペイドカード、定期券、通帳、パスポート、身分証明書、商品等の対象物に貼り付けて用いることができる。また、図４に示すように、立体物、模様等の物体像１１を記録したフォトポリマー等の体積型ホログラム媒体１０の一部の所定パターン領域１２にのみ２つの干渉縞３、４を記録しておき、所定の方向（入射角Ｉ又はＤ）から所定波長（λ）の光を入射したときに、所定の方向（回折角Ｄ又はＩ）からこの所定パターン領域１２のパターンが読み取れるか否かにより、その媒体１０が真実なものか偽造されたものかを判断することができる。
【００２２】
また、本発明の複合ホログラムは、例えば指向性の強い狭帯域波長フィルターとしても用いることができる。その場合は、例えば図５に示すように、メタルハライドランプ等の高輝度の白色光源２１からの発散光を正レンズ２２により略平行な光束２３に変換して、高指向性狭帯域波長フィルター２０として用いる本発明の体積型ホログラム１と２を重畳あるいは多重記録してなる複合ホログラム２０にその光束２３の主光線が入射角Ｉ又はＤで入射するようにすればよい。このような配置で本発明の複合ホログラム２０を用いれば、出射角（回折角）Ｄ又はＩで出射する光２４は、光源２１からの放射された光の中の特定波長λの光であって、出射角がフィルター２０の何れの位置でも同じ角度Ｄ又はＩのもののみが選択されるので、出射光２４は単色波長で平行性が高いものとなる。すなわち、本発明による複合ホログラムは高指向性狭帯域波長フィルターとして用いることができる。
【００２３】
以上、本発明の複合ホログラムを原理といくつかの用途の例について説明してきたが、本発明はこれらに限定されず種々の変形、用途が可能である。
【００２４】
【発明の効果】
以上の説明から明らかなように、本発明の複合ホログラムによると、特定の入射角の特定の波長の光のみが複数の体積型ホログラムを順にブラッグ回折して特定の出射角で出射するように、その複数の体積型ホログラム各々の干渉縞のスラント角とピッチが設定されているので、特定の入射角で特定の波長の光が入射したときのみ、特定の出射角でその光が回折し、他の入射角及び波長においてはその出射角の方向へ回折しないので、例えば偽造防止ホログラムとして有用であり、また、高指向性狭帯域波長フィルター等の光学素子として使用可能なものである。
【図面の簡単な説明】
【図１】本発明の複合ホログラムの原理を説明するための図である。
【図２】本発明の１例の複合ホログラムの入射角に対する回折角、入射角に対する各ホログラムのブラッグ波長を示す図である。
【図３】別の例の複合ホログラムの図２と同様の図である。
【図４】本発明の複合ホログラムを偽造防止ホログラムとして用いる場合の１例の構成を示す模式図である。
【図５】本発明の複合ホログラムを高指向性狭帯域波長フィルターとして用いる場合の配置を示す模式図である。
【符号の説明】
１、２…体積型ホログラム
３、４…干渉縞
５…入射光
６…出射（回折）光
１０…体積型ホログラム媒体
１１…物体像
１２…所定パターン領域
２０…高指向性狭帯域波長フィルター（複合ホログラム）
２１…白色光源
２２…正レンズ
２３…略平行光束
２４…出射光[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a composite hologram, and more particularly to a composite hologram that diffracts in a specific direction only when light of a specific wavelength is incident from a specific direction.
[0002]
[Prior art]
Conventionally, relief holograms that record 3D images, patterns, etc. to ensure that CD cards, prepaid cards, commuter passes, passbooks, passports, identification cards, merchandise, etc. are genuine and not forged It is widely practiced to attach a label, a seal, or the like made of a Lippmann hologram to an object.
[0003]
[Problems to be solved by the invention]
These holograms can be reproduced by simple reproduction illumination light or white light, and it is not always difficult to forge them using a technique such as replication. For this reason, security such as labels and seals made of such holograms is not always high.
[0004]
The present invention has been made in view of such problems of the prior art, and an object thereof is a hologram that diffracts in a specific direction only when light of a specific wavelength is incident from a specific direction, and is a forgery prevention hologram. It is to provide a composite hologram that can be used as an optical element such as a narrow band wavelength filter.
[0005]
[Means for Solving the Problems]
The composite hologram of the present invention that achieves the above object is a composite hologram in which a plurality of volume holograms on which uniform plane interference fringes are recorded are superimposed or multiple-recorded, and a specific incident angle is specified. The slant angle and pitch of the interference fringes of each of the plurality of volume holograms are set so that only the light of the wavelength of the plurality of volume holograms is sequentially Bragg diffracted and emitted at a specific emission angle. It is a feature.
[0006]
In this case, for example, two volume holograms can be superimposed or multiple-recorded.
[0007]
The composite hologram of the present invention can be used as, for example, an anti-counterfeit hologram, and a plurality of volume holograms are superimposed only on a predetermined pattern area of a volume hologram on which an object image such as a three-dimensional object or a pattern is recorded. Alternatively, multiple recording can be performed.
[0008]
The composite hologram of the present invention can also be used as a highly directional narrow band wavelength filter.
[0009]
In the present invention, the slant of the interference fringes of each of the plurality of volume holograms is emitted so that only light of a specific wavelength at a specific incident angle sequentially emits the plurality of volume holograms by Bragg diffraction. Since the angle and pitch are set, the light is diffracted at a specific exit angle only when light of a specific wavelength is incident at a specific incident angle, and the direction of the exit angle at other incident angles and wavelengths. For example, it is useful as an anti-counterfeit hologram and can be used as an optical element such as a highly directional narrow band wavelength filter.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The principle and examples of the composite hologram of the present invention will be described below.
Consider a case where two volume holograms 1 and 2 on which interference fringes 3 and 4 (fringes) having a uniform plane are recorded are superimposed as shown in a cross section in FIG. In FIG. 1, only one surface of each of the interference fringes 3 and 4 is shown, but actually, a large number of interference fringes are formed in parallel at a constant pitch. Below, the light 5 incident on the hologram 1 is subjected to Bragg diffraction by the interference fringe 3 of the hologram 1, and the diffracted light is incident on the hologram 2 and is subjected to Bragg diffraction by the interference fringe 4 again. Consider the case where the diffracted light 6 is emitted from 2.
[0011]
It is assumed that the normal lines N ′ and N ″ of the interference fringes 3 and 4 of the holograms 1 and 2 are in the plane of FIG. 1, and the average refractive index of the holograms 1 and 2 is the same n.
The slant angle of the interference fringes of the hologram 1 (angle with respect to the plane of the hologram 1) is θ, and the pitch of the interference fringes (distance between adjacent interference fringes) is P.
The slant angle of the interference fringes of the hologram 2 is φ, and the pitch of the interference fringes is Q.
A refraction angle in the hologram 1 of the light 5 incident at an incident angle I from the air is denoted by I ′.
[0012]
The light 5 incident at an incident angle I with respect to the normal line of the hologram 1 from the air enters the surface of the fringe 3 of the hologram 1 at an angle of (I′−θ) from the normal line N ′. Diffracted at an angle of (2θ−I ′) from the normal N perpendicular to the plane, and incident on the surface of the fringe 4 of the hologram 2 at an angle of (π + 2θ−φ−I ′) from the normal N ″. Consider light 6 that is diffracted from a normal N perpendicular to the plane (2) at an angle of (2φ + I′−2θ−π) and emitted into the air at a refraction angle D.
[0013]
The Bragg wavelength of hologram 1 is
(2P / n) × cos (I′−θ) (1)
The Bragg wavelength of hologram 2 is
(2Q / n) × cos (π + 2θ−φ−I ′) (2)
It is. Only when these two wavelengths match, the light diffracts as described above.
[0014]
That means
Pcos (I′−θ) = − Qcos (2θ−φ−I ′) (3)
here,
A = (θ−φ) / 2
B = (2I′−3θ + φ) / 2
r = −P / Q
The above equation (3) can be written as follows.
[0015]
rcos (A + B) = cos (AB) (4)
(R-1) cosAcosB = (r + 1) sinAsinB (5)
tanB = (r−1) / {(r + 1) tanA} (6)
tan {(2I'-3θ + φ) / 2}
= (-PQ) / [(-P + Q) tan {(θ-φ) / 2}] (7)
I ′ = tan −1 [(P + Q) / [(P−Q) tan {(θ−φ) / 2}]]
+ (3θ−φ) / 2 (8)
It becomes.
[0016]
That is, the incident angle I of the incident light 5 is
Figure 0003912700
It becomes.
[0017]
The Bragg wavelength λ at that time is
λ = (2P / n) cos <tan −1 [(P + Q) / [(P−Q) ×
tan {(θ−φ) / 2}]] + (θ−φ) / 2> (10)
The diffraction angle D of the diffracted light 6 is
D = −sin −1 << nsin <tan −1 [(P + Q) / [(PQ) ×
tan {(θ−φ) / 2}]] + (3φ−θ) / 2 >>> (11)
It becomes.
[0018]
As is clear from the above examination, two interference fringes can be obtained by superimposing two volume holograms on which uniform planar interference fringes are recorded or by multiplex recording in one hologram medium. The diffraction wavelength sequentially diffracted by is a specific single wavelength satisfying the equation (10), the incident angle I satisfying the equation (9) at that time, and the diffraction angle D satisfying the equation (11) is also a specific one value. I understand that there is. Since the incident angle I and the diffraction angle D may be interchanged due to the reversibility of the light beam, such a composite hologram is specified only when light of a specific wavelength λ is incident at a specific incident angle I or D. It can be seen that the light is diffracted at the exit angle D or I and is not diffracted toward the exit angle at other incident angles and wavelengths. It should be noted that such a solution can exist by a similar analysis even when three or more volume holograms are superimposed or recorded in a multiplexed manner.
[0019]
An actual numerical example is shown. 2 shows that the slant angle θ of the interference fringe of the hologram 1 is −50 °, the pitch P is 700 nm, the slant angle φ of the interference fringe of the hologram 2 is 60 °, the pitch Q is 800 nm, and the average refraction of both holograms 1 and 2 is shown. When the rate n is 1.52, the diffraction angle (outgoing angle) D (thick solid line) with respect to the incident angle I of the composite hologram having the configuration of FIG. 1, the Bragg wavelength λ (angle series) with respect to the incident angle I of the hologram 1, The Bragg wavelength λ (◇ series) with respect to the incident angle I of the hologram 2 is shown. From FIG. 2, the wavelength λ that is Bragg diffracted in order by both holograms 1 and 2 is λ = 801.1579 nm, the incident angle I is I = 32.05901 °, and the diffraction angle (outgoing angle) D is D = −. 30.59181 °. This value coincides with the value obtained from the equations (9) to (11). Of course, the incident angle I and the outgoing angle D can be interchanged.
[0020]
3 shows that the slant angle θ of the interference fringe of the hologram 1 is −40 °, the pitch P is 700 nm, the slant angle φ of the interference fringe of the hologram 2 is 45 °, the pitch Q is 800 nm, and the average refraction of both holograms 1 and 2 is shown. 2 is a diagram similar to FIG. 2 when the rate n is 1.52, λ = 662.5027 nm, the incident angle I is I = 6.092934 °, and the diffraction angle (outgoing angle) D is D = −9. .135626 °. In this case as well, it agrees with the value obtained from the above equations (9) to (11). Similarly, the incident angle I and the outgoing angle D can be interchanged.
[0021]
The composite hologram as described above diffracts only light in a specific narrow wavelength band incident from one of the two specific directions to the other of the two specific directions, and light in the other direction and wavelength is directly transmitted. Although it has a characteristic of diffracting in a completely different direction, it is extremely difficult to forge such a composite hologram by a method such as duplication, and at the same time, a light source and a reading light receiving element are set to a predetermined exact for reproduction. Must be placed in the correct relative position and direction. Therefore, such a hologram is useful as, for example, a forgery prevention hologram. When used as a forgery-preventing hologram, the hologram medium in which the two-layer holograms 1 and 2 are overlapped as shown in FIG. 1 or the one-layer hologram medium in which the interference fringes 3 and 4 are multiplexed and recorded is used as it is. , CD cards, prepaid cards, commuter passes, passbooks, passports, identification cards, products, etc. In addition, as shown in FIG. 4, two interference fringes 3 and 4 are recorded only in a predetermined pattern region 12 of a volume hologram medium 10 such as a photopolymer in which an object image 11 such as a three-dimensional object or a pattern is recorded. Whether or not the pattern of the predetermined pattern region 12 can be read from a predetermined direction (diffraction angle D or I) when light having a predetermined wavelength (λ) is incident from a predetermined direction (incidence angle I or D). Thus, it can be determined whether the medium 10 is true or forged.
[0022]
The composite hologram of the present invention can also be used as a narrow band wavelength filter having strong directivity, for example. In this case, for example, as shown in FIG. 5, divergent light from a high-intensity white light source 21 such as a metal halide lamp is converted into a substantially parallel light beam 23 by a positive lens 22 to obtain a highly directional narrowband wavelength filter 20. The principal ray of the light beam 23 may be incident at an incident angle I or D on the composite hologram 20 formed by superimposing or multiplex recording the volume holograms 1 and 2 of the present invention to be used. If the composite hologram 20 of the present invention is used in such an arrangement, the light 24 emitted at the emission angle (diffraction angle) D or I is light of a specific wavelength λ in the light emitted from the light source 21. Since only the same angle D or I is selected at any position of the filter 20, the emitted light 24 has a monochromatic wavelength and high parallelism. That is, the composite hologram according to the present invention can be used as a highly directional narrow band wavelength filter.
[0023]
As described above, the principle and some examples of the application of the composite hologram of the present invention have been described. However, the present invention is not limited to these, and various modifications and applications are possible.
[0024]
【The invention's effect】
As is clear from the above description, according to the composite hologram of the present invention, only light of a specific wavelength at a specific incident angle is Bragg diffracted in order to emit a plurality of volume holograms at a specific emission angle. Since the slant angle and pitch of the interference fringes of each of the volume holograms are set, the light is diffracted at a specific emission angle only when light of a specific wavelength is incident at a specific incident angle, Since the incident angle and wavelength do not diffract in the direction of the emission angle, it is useful as, for example, a forgery prevention hologram and can be used as an optical element such as a highly directional narrow band wavelength filter.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the principle of a composite hologram of the present invention.
FIG. 2 is a diagram showing a diffraction angle with respect to an incident angle of a composite hologram of one example of the present invention, and a Bragg wavelength of each hologram with respect to the incident angle.
FIG. 3 is a view similar to FIG. 2 of another example of a composite hologram.
FIG. 4 is a schematic diagram showing a configuration of an example when the composite hologram of the present invention is used as an anti-counterfeit hologram.
FIG. 5 is a schematic diagram showing an arrangement when the composite hologram of the present invention is used as a highly directional narrow band wavelength filter.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 2 ... Volume type hologram 3, 4 ... Interference fringe 5 ... Incident light 6 ... Output (diffraction) light 10 ... Volume type hologram medium 11 ... Object image 12 ... Predetermined pattern area 20 ... High directivity narrow band wavelength filter (composite) hologram)
21 ... White light source 22 ... Positive lens 23 ... Substantially parallel light beam 24 ... Outgoing light

Claims (5)

一様な平面の干渉縞が記録された複数の体積型ホログラムが重畳されるか多重記録されてなる複合ホログラムであって、特定の入射角の特定の波長の光のみがこれら複数の体積型ホログラムを順にブラッグ回折して特定の出射角で出射するように、前記複数の体積型ホログラム各々の干渉縞のスラント角とピッチが設定されていることを特徴とする複合ホログラム。A composite hologram in which a plurality of volume holograms on which interference fringes of a uniform plane are recorded are superimposed or multiple-recorded, and only the light with a specific wavelength at a specific incident angle is used. The slant angle and pitch of the interference fringes of each of the plurality of volume holograms are set so as to sequentially Bragg diffract and emit at a specific emission angle. ２枚の体積型ホログラムが重畳されるか多重記録されてなることを特徴とする請求項１記載の複合ホログラム。2. The composite hologram according to claim 1, wherein two volume holograms are superimposed or multiple-recorded. 偽造防止ホログラムとして用いられることを特徴とする請求項１又は２記載の複合ホログラム。3. The composite hologram according to claim 1, wherein the composite hologram is used as a forgery prevention hologram. 立体物、模様等の物体像が記録された体積型ホログラムの一部の所定パターン領域にのみ前記複数の体積型ホログラムが重畳されるか多重記録されてなることを特徴とする請求項３記載の複合ホログラム。4. The volume holograms according to claim 3, wherein the plurality of volume holograms are superimposed or multiple-recorded only on a predetermined pattern area of a part of the volume hologram on which an object image such as a three-dimensional object or a pattern is recorded. Composite hologram. 高指向性狭帯域波長フィルターとして用いられることを特徴とする請求項１又は２記載の複合ホログラム。3. The composite hologram according to claim 1, wherein the composite hologram is used as a highly directional narrow band wavelength filter.
JP29376997A 1997-10-27 1997-10-27 Composite hologram Expired - Fee Related JP3912700B2 (en)

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KR100463453B1 (en) * 2002-01-31 2004-12-23 이철원 An Apparatus and A method for Smart Card Reader of the Hologram Data using the Angle Multiplexing Hologram
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DE102007050277A1 (en) * 2007-10-18 2009-04-23 Bundesdruckerei Gmbh Security and / or value document with holograms arranged in different layers
JP5170426B2 (en) * 2008-08-11 2013-03-27 大日本印刷株式会社 Anti-counterfeiting system using volume hologram for anti-counterfeiting
JP5170425B2 (en) * 2008-08-11 2013-03-27 大日本印刷株式会社 Photosynthetic element
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