JP2006284364A - Judging device for hologram flaw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a judging device for a hologram flaw capable of being reduced in size, low in power consumption and easy in maintenance. <P>SOLUTION: The flaw of the hologram is judged on the basis of the reference spatial frequency (f) of the hologram. The judging device 10 of the hologram flaw is equipped with a light source 21 for irradiating the surface S of the hologram 5 with inspection light of a wavelength λ, a moving part 30 for moving the light source 21 so as to irradiate the surface S of the hologram 5 with inspection light at an angle becoming sin<SP>-1</SP>(1/fλ)° with respect to the normal line direction of the surface S of the hologram 5, an imaging part 40 for imaging diffracted light when the inspection light is reflected from the surface S of the hologram 5, and a judging part 50 for judging the presence of the flaw of the hologram 5 on the basis of imaged diffracted light. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hologram defect determination apparatus that performs hologram defect determination, and more particularly, to a hologram defect determination apparatus that can be miniaturized and that can be easily maintained with low power consumption.

  The hologram can record a stereoscopic image that cannot be reproduced by a printing machine such as a color copying machine. In particular, a rainbow hologram can be mass-replicated by using a method of recording optical interference fringes of the hologram with irregularities and embossing it into a thin film. Therefore, in recent years, holograms have been used for security purposes such as banknotes and vouchers, credit cards, ID cards, identification cards, computer-related products, computers, music, game software, CDs, DVDs, videos, books, etc. The number of cases is increasing.

  As described above, since the hologram is often used for security purposes, sufficient attention is required for the manufacturing process and defect inspection before shipment.

  For example, in the manufacturing process, when foreign matter such as dust adheres to the stamper, if the hologram is embossed with the foreign matter still attached, the unevenness of the diffraction grating in the foreign matter adhesion portion is crushed and different diffraction gratings are formed. In this case, by attaching a defective hologram to the authentic product, there is a high possibility that the authentic product is mistaken for a counterfeit product.

In order to avoid such misperception, a hologram defect detection apparatus has been conventionally provided (see, for example, Patent Document 1). This hologram defect detection apparatus includes a light source for inspection light that irradiates inspection light from all directions substantially on the surface side of the hologram from the viewpoint of being able to be used universally for defect detection of holograms of any kind.
Japanese Patent Application Laid-Open No. 2004-239834

  However, in the conventional hologram defect detection apparatus as described above, it is assumed that the hologram lattice spacing, alignment direction, and the like are unknown. Therefore, in order to widen the incident angle of the inspection light, the light source must be enlarged to such an extent that the inspection light can be irradiated from substantially all directions on the surface side of the hologram.

  As a result, the production of the hologram itself must be stopped for each maintenance of the light source by taking the trouble of maintenance work such as replacement of the light source and the problem that the required power consumption increases in proportion to the size of the light source. There are problems such as not becoming.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hologram defect determination apparatus that can reduce the size of a light source, that is, low power consumption and easy maintenance.

  In order to achieve the above object, the following measures are taken.

The invention corresponding to claim 1 is an apparatus for determining a defect of a hologram to be inspected based on a reference value f of a spatial frequency of a diffraction grating in a reference hologram. A light source for irradiating light, and a moving means for moving the light source so as to irradiate inspection light from an angle θ that is θ = sin ⁻¹ (1 / fλ) degrees with respect to the normal direction of the surface of the hologram; An imaging means for imaging diffracted light generated in the normal direction when the inspection light is reflected by the surface of the hologram, and a determination means for determining the presence or absence of a defect in the hologram based on the captured diffracted light Is a hologram defect determination apparatus.

  The invention corresponding to claim 2 is the hologram defect determination apparatus corresponding to claim 1, wherein the light source includes a light emitting unit arranged in a ring shape around a normal to the surface of the hologram. Device.

  The invention corresponding to claim 3 is the hologram defect determination apparatus corresponding to claim 1 or claim 2, wherein the light source is a hologram defect determination apparatus provided with an LED as a light emitting unit for generating the inspection light.

  The invention corresponding to claim 4 is the hologram defect determination apparatus corresponding to claim 3, wherein the LED emits green light having the wavelength λ in the range of 540 to 580 nm.

  The invention corresponding to claim 5 is the hologram defect determination apparatus corresponding to any one of claims 1 to 4, wherein the hologram defect further comprises a cylindrical diffusion plate along the inner periphery of the light source. It is a determination device.

The invention corresponding to claim 6 is the hologram defect determination apparatus corresponding to any one of claims 1 to 5, further comprising an acquisition means for acquiring the reference value f of the spatial frequency, wherein the acquisition means is The acquisition light source that irradiates the surface of the reference hologram with inspection light having a wavelength λ, and the acquisition light source is rotated so as to alternately face the front and back surfaces of the reference hologram with the reference hologram as a rotation center. The acquisition moving means to be moved and the acquisition light source are irradiated with inspection light inclined at an angle θ (where 0 ° <θ <90 °) from the normal direction of the surface of the hologram while the acquisition light source is rotationally moved. When the light is reflected by the surface of the reference hologram, the acquisition imaging means for imaging the diffracted light generated in the normal direction, the angle θ, the wavelength λ, and the formula θ when the diffracted light is imaged = Sin ^-1 ( 1 / fλ) is a hologram defect determination apparatus including a spatial frequency acquisition unit that acquires the reference value f of the spatial frequency.

<Terminology>
In the present invention, the “spatial frequency reference value” is a spatial frequency value obtained from a design value in a hologram design process. The “reference value of spatial frequency” is also referred to as “reference spatial frequency”.

<Action>
Therefore, the invention corresponding to claim 1 is directed to a light source for irradiating the hologram surface with inspection light having a wavelength λ, and a light source having a sin ⁻¹ (1 / fλ) degree relative to the normal direction of the hologram surface. By moving the light source by moving the light source so as to irradiate the inspection light from a certain angle and the imaging means for imaging the diffracted light when the inspection light is reflected by the hologram surface, The diffracted light can be accurately imaged without increasing the size more than necessary. That is, it is possible to provide a hologram defect determination apparatus that can reduce the size of the light source, that is low power consumption, and that is easy to maintain.

  In the invention corresponding to claim 2, in addition to the operation corresponding to claim 1, the light source includes a light emitting portion arranged in a ring shape along the periphery in the normal direction to the surface of the hologram. The diffracted light can be imaged without depending on the arrangement direction of the diffraction gratings. Thereby, it is possible to provide a hologram defect determination device capable of determining a defect of a hologram whose diffraction grating arrangement direction is unknown.

  The invention corresponding to claim 3 provides the hologram defect determination device with low power consumption and easy maintenance because the light source includes the LED as the light emitting unit in addition to the operation corresponding to claim 1 or claim 2. it can.

  In the invention corresponding to claim 4, in addition to the action corresponding to claim 3, since the LED emits green light, it emits red light without using many LEDs compared to the case of emitting blue light. As a result, it is possible to provide a hologram defect determination device that can be easily imaged as compared with the case where it is performed.

  The invention corresponding to claim 5 is the hologram defect determination apparatus corresponding to any one of claims 1 to 4, and further includes a cylindrical diffusion plate along the inner periphery of the light source. The intensity unevenness of the inspection light can be reduced. That is, it is possible to provide a hologram defect determination device that improves unevenness due to the light source.

  The invention corresponding to claim 6 is the hologram defect determination apparatus corresponding to any one of claims 1 to 5, and further comprises an acquisition means for acquiring a reference value f of the spatial frequency of the reference hologram. In addition, it is possible to provide a hologram defect determination apparatus capable of executing defect determination of an inspection target hologram with reference to an arbitrary hologram.

  ADVANTAGE OF THE INVENTION According to this invention, the light source can be reduced in size, and the hologram defect determination apparatus with low power consumption and easy maintenance can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a conceptual diagram of a configuration of a hologram defect determination apparatus according to the first embodiment of the present invention.

  The hologram defect determination device 10 is provided in an inspection area 11 for inspecting a hologram, and performs defect determination of the hologram 5 conveyed to the inspection area 11 by the conveyance platform 6.

  Here, the hologram 5 is, for example, a rainbow hologram (hereinafter referred to as an embossed hologram) obtained by embossing, and here, an embossed hologram in which the spatial frequency f of the diffraction grating is in the range of 500 to 2000 [lines / mm]. Etc. The embossed hologram is a reflective hologram in which aluminum or the like is vapor-deposited on the press surface and is suitable for mass production. The embossed hologram has a diffraction grating region and a plain region, and has various diffraction grating arrangement directions and pitch values. There may be different diffraction gratings on the diffraction grating. Due to the difference in the diffraction grating arrangement direction and the pitch value, various patterns and colors are projected according to the light irradiation angle.

  The conveyance stand 6 is a belt conveyor or the like installed in a manufacturing factory or the like, and conveys the hologram so as to pass through the inspection area 11 below the hologram defect determination apparatus 10. A hologram installation portion 6A on which the hologram 5 is placed is provided on a part of the transport table 6.

  On the other hand, the hologram defect determination apparatus 10 includes a light irradiation unit 20, a moving unit 30, an imaging unit 40, a determination unit 50, and a control unit 60 (not shown).

  Note that the arrangement of the light irradiation unit 20, the moving unit 30, and the imaging unit 40 is supported by a support body (not shown) in order to enable defect determination of the hologram 5 supplied to the inspection area 11.

  The light irradiation unit 20 irradiates the surface S of the hologram 5 with inspection light, and includes a light source 21 and a diffusion plate 22.

  The light source 21 is an LED or the like that emits inspection light having a wavelength λ, and is held by the moving unit 30 so as to be movable in the vertical direction (the normal direction of the surface of the hologram 5).

  The LED is suitable for downsizing the light source, and wavelength selection is relatively easy. The light source 21 includes a large number of LEDs (light emitting portions) arranged in a donut shape (annular shape) along the periphery in the normal direction to the surface S of the hologram 5.

  The wavelength λ of the incident light needs to be adjusted according to the maximum spatial frequency fs [lines / mm] of the hologram, and needs to be a value smaller than 1,000,000 / fs [nm]. In order to minimize the energy loss, the center wavelength λc of the incident light may be selected to be {(1,000,000 / fs) -20} [nm]. This is because the half-value width of the wavelength of a normal LED is 20 nm.

  Specifically, an LED that emits green light (wavelength in the vicinity of 560 nm: for example, a wavelength in the range of 540 to 580 nm) is used. Since the amount of light is insufficient with blue light, it is necessary to use a large number of LEDs. Also, in the case of red light, when the spatial frequency of the hologram 5 is large, the diffraction of the diffracted light becomes large, so that imaging becomes difficult. From this point of view, it is preferable to use a green light emitting element. The LED may be a bullet type or a chip type. The bullet-type LED has a strong directivity, and the inspection light is irradiated linearly. Therefore, when a bullet-type LED is used, it is necessary to dispose a diffusion plate in front of the LED so as not to cause illumination unevenness (unevenness). On the other hand, the chip-type LED has relatively uniform illumination and can be easily arranged.

  As the light source 21, an annular fluorescent lamp may be used instead of the LED. Since it is a donut-shaped light source, it becomes possible to generate diffracted light without depending on the arrangement direction of the diffraction gratings of the hologram 5.

  The diffusion plate 22 is provided so as to be cylindrical along the inner periphery of the light source 21, and diffuses the inspection light with the LED irradiation direction directed toward the center of the hologram 5 to realize uniform illumination. It is. By providing the diffusion plate 22, unevenness of incident light can be reduced.

  When the reference spatial frequency f of the hologram 5 is set, the moving unit 30 illuminates the inspection light from an angle that is sin-1 (1 / fλ) with respect to the normal direction of the surface S of the hologram 5. 20 is a mechanism for moving 20.

Specifically, the moving unit 30 is 1 / tan (sin ⁻¹ (1 / fλ)) times the radius R of the light source 20 when the height of the surface S of the hologram 5 is used as a position reference. The light source 20 is moved to this position. Here, the position of the light source 20 is adjusted based on the value of the diffraction angle θ shown in FIG. 2 by the driving units 32A and 32B (not shown) attached to the two columns 31A and 31B. The

  Here, FIG. 2 is a diagram showing a list of diffraction angles θ of diffracted light in the hologram 5. The vertical axis corresponds to the wavelength λ of the incident light, and the horizontal axis corresponds to the reference spatial frequency f of the hologram 5. Here, the column where a certain wavelength λ intersects with a certain reference spatial frequency f represents the diffraction angle θ at that λ, f. Note that FIG. 2 is an example, and a table representing the relationship between the wavelength λ, the reference spatial frequency f, and the diffraction angle θ may be used with a finer resolution than in FIG. Further, in FIG. 2, the display of “-” means that the diffraction angle exceeds 90 degrees.

  For example, under the condition in which light having a wavelength λ of 700 nm is irradiated onto a region where the spatial frequency f of the hologram 5 is 1500 [lines / mm], the intersection of the two f and λ is displayed as “−”. Diffracted light cannot be generated in the normal direction of S. That is, when the imaging unit 40 is fixed in the normal direction of the surface S of the hologram 5 under the condition that the display is “−”, the diffracted light cannot be imaged.

  Therefore, when the height of the light source 21 is adjusted, the driving units 32A and 32B are configured to have the height of the light source 20 based on the relationship between the hologram reference spatial frequency f and the inspection light wavelength λ as shown in FIG. Adjust the appropriate position mechanically.

  Needless to say, the moving mechanism of the moving unit 30 is not limited to this.

  The imaging unit 40 includes a CCD camera 41 that captures diffracted light when the inspection light emitted from the light source 21 is reflected by the surface S of the hologram 5, and the imaging data obtained by the imaging is input to the determination unit 50. Has a function to send. The imaging unit 40 is fixed on the perpendicular line of the hologram installation unit 6A. As a result, when diffracted light is generated, it is always possible to image on the normal line of the inspection surface of the hologram 5. The inspection surface is a diffraction grating formation surface on which diffraction grating formation is formed on the surface S of the hologram 5.

  The reason for this will be described with reference to FIG.

When light is incident from the point P on the normal line to the inspection surface S1 of the embossed hologram perpendicularly to the point O on the inspection surface S1, the angle sin ⁻¹ (mλ from the normal line in the direction in which the diffraction gratings of the hologram are arranged. Diffracted light is generated in the direction / d). Here, λ is the wavelength of the incident light, d is the pitch of the diffraction grating, and m = ± 1, ± 2, ± 3,... In FIG. 3A, two diffracted lights are generated symmetrically in the directions of L1 and L2.

  Conversely, when light is incident on point O from points L1 and L2, diffracted light is generated at points P and P1 or points P and P2 for the same reason (FIG. 3B). ).

That is, by irradiating light of a specific wavelength λ from the direction of angle sin ⁻¹ (mλ / d), it is possible to image diffracted light generated in the normal direction of the inspection surface S1. Here, since the height of the light source 20 is adjusted by the moving unit 30, when diffracted light is generated, an image can always be taken on the normal line of the inspection surface of the hologram 5.

  Needless to say, it is possible to effectively image diffracted light by using the telecentric lens 42 to form an image of only the light traveling straight along the normal direction of the hologram 5. For example, an imaging system including a light source 21 (LED), a diffusing plate 22, a direct light incident prevention shade 23, a CCD camera 41, and a telecentric lens 42 as shown in FIG. 4 can be used.

  The determination unit 50 determines the presence or absence of a hologram defect based on the diffracted light imaged by the imaging unit 40, and has a function of sending the determination result to the control unit 60. Here, the defect determination of the hologram is performed based on the comparison with the reference hologram 5S whose spatial frequency is the reference value f. For example, the brightness distribution of the diffracted light in the reference hologram 5S is imaged in advance and compared with the brightness distribution of the diffracted light of the hologram 5 captured by the imaging unit 40. Thereby, when there is a part with different luminance (for example, a part where diffracted light is not imaged), it is determined that the hologram has a defect. Further, from the viewpoint of examining the entire surface of the hologram in order to prevent the defect from being overlooked, the luminance distribution in the reference hologram 5S is held as master image data, the luminance distribution in the imaged hologram 5 is used as captured image data, and both image data are stored. It is preferable that a difference image is generated by comparison and defect determination is performed based on a luminance difference and a threshold value of the area.

  The control unit 60 controls input / output of data in the hologram defect determination apparatus 10 and has a function of controlling the units 10 to 50 so as to execute the operation shown in the flowchart of FIG. When the determination result is received from the determination unit 50, it has a function of removing the defective hologram 5 from the transport table 6 by an exclusion mechanism (not shown). In addition, user command information input from input / output means such as a keyboard is transmitted to the corresponding units. Here, the command information includes, for example, the reference value f of the spatial frequency of the hologram 5 and the start of inspection.

  Note that the hologram defect device 10 includes devices such as a keyboard, a display, and an audio speaker as necessary.

(Operation of hologram defect determination device)
Next, the operation of the hologram defect determination apparatus according to the present embodiment will be described using the flowchart of FIG.

  In step ST <b> 1, the hologram 5 of the subject is installed on the hologram installation unit 6 </ b> A of the transport table 6. The hologram 5 is transported to the inspection area 11 as the transport table 6 is driven.

  In step ST <b> 2, the spatial frequency reference value f of the hologram 5 is input to the hologram defect determination apparatus 10 by a user operation. The input information is transmitted to the moving unit 30 via the control unit 60.

  In step ST3, the moving unit 30 mechanically adjusts the height of the light source 21 based on the inputted reference value f.

  In step ST <b> 4, the inspection light having the specific wavelength λ is emitted toward the center point O of the surface S of the hologram 5 by the LED of the light source 21. At this time, the center wavelength λC of the inspection light is set to {1,000,000 / fs-20} [nm]. Thereby, the incident inspection light is diffracted and reflects the diffracted light.

  In step ST <b> 5, the diffracted light from the hologram 5 is imaged by the imaging unit 40.

  In step ST <b> 6, the determination unit 50 compares the imaged data D <b> 1 of the imaged hologram 5 and the reference imaged data D <b> 0 of the reference hologram 5 </ b> S having a spatial frequency of the reference value f that has been imaged in advance. Specifically, the luminance distribution of the imaging data D1 and the luminance distribution of the reference imaging data D0 are compared.

  In step ST7, when the determination unit 50 determines that the luminance distribution of the imaging data D1 matches the luminance distribution of the reference imaging data D0, the determination unit 50 determines that the hologram has no defect, and the control unit 60 determines the result. Is sent out.

  In step ST8, when the determination unit 50 determines that the luminance distribution of the imaging data D1 and the luminance distribution of the reference imaging data D0 do not match, the determination unit 50 determines that the hologram has a defect and controls the control unit 60. Send the result to.

  In step ST9, the control unit 60 receives the result of the defect determination from the determination unit 50, causes the display display or the like to output the determination result, and ends the process.

As described above, according to the present embodiment, the light source 21 that irradiates the surface S of the hologram 5 with the inspection light having the wavelength λ and the light source 21 are set to sin ⁻¹ ( 1 / fλ) A moving unit 30 that moves so as to irradiate inspection light from an angle of (degree) and an imaging unit 40 that images diffracted light when the inspection light is reflected by the surface S of the hologram 5 is provided. Thus, by moving the light source, the diffracted light can be accurately imaged without enlarging the light source more than necessary.

  Supplementally, the conventional light source needs to be large enough to irradiate the inspection light from all directions substantially on the surface side of the hologram. On the other hand, since the light source 21 of the present embodiment can be moved by the moving unit 30, for example, when moving in the range of an incident angle of 5 to 85 degrees (= | 80 |) in increments of 1/80 of the conventional light source. Double size is acceptable.

  That is, according to the present embodiment, it is possible to provide the hologram defect determination apparatus 10 that can reduce the size of the light source, and that can be easily maintained with low power consumption.

  Further, since the light source 21 has a donut shape (annular shape) along the periphery in the normal direction to the surface S of the hologram 5, the diffracted light does not depend on the arrangement direction of the diffraction gratings of the hologram 5. Can be imaged. Accordingly, it is possible to provide the hologram defect determination device 10 that can determine the defect of a hologram whose diffraction grating arrangement direction is unknown.

  Furthermore, since the light source 21 includes an LED, it is possible to provide the hologram defect determination apparatus 10 with low power consumption and easy maintenance. Note that since the LED emits green light, the number of LEDs is less than that in the case of emitting blue light, and imaging can be performed more easily than in the case of emitting red light.

  Moreover, the light irradiation part 20 can relieve | moderate the intensity | strength nonuniformity of test | inspection light by the structure further provided with the cylindrical diffusion plate 22. FIG. That is, it is possible to provide the hologram defect determination device 10 in which unevenness due to the light source is improved.

  Moreover, if the hologram defect determination apparatus 10 according to the present embodiment is installed in a manufacturing factory, defect determination can be performed immediately after the hologram 5 is manufactured. Thereby, the time to shipment can be shortened, and as a result, mass production of holograms becomes possible in a short period of time.

<Second Embodiment>
FIG. 6 is a diagram showing a concept of a hologram defect determination apparatus 10S according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the part same as the already demonstrated part, and the overlapping description is abbreviate | omitted.

  The second embodiment is a modification of the first embodiment, and from the viewpoint of realizing defect determination even for a hologram whose spatial frequency reference value f is unknown, the hologram defect determination device 10S includes the hologram described above. The defect determination apparatus 10 further includes a reference value acquisition unit 70.

  The reference value acquisition unit 70 acquires a reference value f of the spatial frequency of the hologram, and includes an acquisition light source 71, an acquisition moving unit 72, and an acquisition imaging unit 73.

  The acquisition light source 71 is moved by the acquisition moving unit 72 and irradiates the inspection light to the hologram 5 at an angle θ inclined by an arbitrary angle from the normal direction of the surface of the hologram 5. Note that the acquisition light source 71 includes a beam expander and irradiates the entire hologram surface with inspection light.

  The acquisition moving unit 72 rotates the acquisition light source 71 along the periphery of the rotation stage 7 with the rotation stage 7 on which the hologram 5 is placed as the rotation center. In other words, the acquisition moving unit 72 rotates the acquisition light source 71 so as to alternately face the front and back surfaces of the hologram 5 with the hologram 5 as the rotation center. At this time, each time the rotary stage 7 rotates by a unit angle, the acquisition light source 71 rotates.

  Further, the rotary stage 7 lifts and rotates the hologram 5 through a hole (not shown) provided in the transport table 6.

  The acquisition imaging unit 73 irradiates the inspection light with the acquisition light source 71 being rotated and inclined at an angle θ (where 0 ° <θ <90 °) with respect to the normal direction of the surface of the hologram. When reflected on the surface S of the hologram 5, the diffracted light generated in the normal direction is imaged, and has a function of sending imaging data to a spatial frequency acquisition unit.

The spatial frequency acquisition unit includes the angle θ of the acquisition light source 71 when the diffracted light is imaged in the imaging data received from the acquisition moving unit 72, the wavelength λ of the inspection light, and the equation θ = sin ⁻¹ (1 / fλ ) To obtain the reference value f of the spatial frequency, and has a function of inputting the obtained reference value f to the hologram defect determination device 10 described above. Here, the relationship of the equation θ = sin ⁻¹ (1 / fλ) means the relationship of the wavelength θ, the spatial frequency f, and the diffraction angle θ as shown in FIG.

  Next, the operation of the hologram defect determination apparatus according to this embodiment will be described. From the viewpoint of simplifying the description, the operation of the reference value acquisition unit 70 will be mainly described here.

  First, the hologram 5 is transported and gets on the rotary stage 7.

  Subsequently, the acquisition light source 71 irradiates the hologram 5 with inspection light. The diffracted light is reflected by the surface S of the hologram by the inspection light, and the diffracted light is imaged by the acquisition imaging unit 73 under certain conditions.

  The imaging operation of such diffracted light is performed while the acquisition light source 71 makes a round around the rotary stage 7 while the rotary stage 7 rotates by a unit angle.

  As a result, the position (incident angle) of the acquisition light source 71 that can image the diffracted light as shown in FIG. 6A and the position (incidence angle) of the acquisition light source 71 that cannot image the diffracted light as shown in FIG. Incident angle), and the angle θ of the diffracted light can be obtained from the obtained imaging data of the diffracted light.

Thereby, the reference value f of the spatial frequency of the hologram can be obtained from the wavelength λ and the diffraction angle θ of the incident light. Specifically, for example, based on the incident angle θ (diffraction angle) when the diffracted light is imaged, the wavelength λ of the inspection light of the acquisition light source 71 and the relational expression θ = sin ⁻¹ (1 / fλ), the hologram It is sufficient to obtain the spatial frequency f.

  The operation after obtaining the reference value f is the same as that of the hologram defect determination apparatus 10 according to the first embodiment. If the reference spatial frequency f is checked once, the subsequent hologram defect is determined based on the reference value. Judgment can be made. This is suitable for hologram defect determination in mass production of holograms.

  As described above, according to the present embodiment, the hologram defect determination apparatus 10 </ b> S that can realize defect determination of an arbitrary hologram 5 by the configuration further including the reference value acquisition unit 70 that acquires the reference spatial frequency f of the hologram 5 is provided. it can. Specifically, for example, it is possible to realize defect determination even for a hologram whose spatial frequency reference value f is unknown.

  Moreover, if the hologram defect determination apparatus according to each of the above embodiments is incorporated into a supermarket money calculator (registry), it is possible to determine the authenticity of a banknote by determining the defect of the hologram attached to the banknote.

  In addition, if the hologram defect determination apparatus according to each of the above embodiments is incorporated in a reproduction device such as a CD and a DVD, it is possible to prevent duplicate copying by determining the defect of the hologram of a CD and DVD with a hologram.

  In this way, if the hologram defect determination device according to each of the above embodiments becomes widespread, banknotes and coins, cash vouchers, credit cards, ID cards, identification cards, computer-related products, computers, music, game software and CDs, Needless to say, it promotes the embedding of holograms that can display patterns and characters in the ultraviolet and infrared regions in everything such as DVDs, videos, and books, and contributes to improving security in society as a whole.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments. For example, some components may be deleted from all the components shown in each embodiment. Furthermore, you may combine a component suitably in different embodiment.

It is a conceptual diagram of a structure of the hologram defect determination apparatus which concerns on the 1st Embodiment of this invention. It is the figure which showed the list | wrist of diffraction angle (theta) which concerns on the same embodiment. It is a figure for demonstrating the diffracted light of the hologram which concerns on the same embodiment. It is a figure which shows an example of the imaging system which concerns on the same embodiment. It is a flowchart which shows operation | movement of the hologram defect determination apparatus 10 which concerns on the same embodiment. It is a figure which shows the concept of the hologram defect determination apparatus 10S which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

      DESCRIPTION OF SYMBOLS 5 ... Hologram, 5S ... Standard hologram, 6 ... Conveyance stand, 6A ... Hologram installation part, 10, 10S ... Hologram defect determination apparatus, 11 ... Inspection area, 15 ... Support body, 20 ... light irradiation part, 21 ... light source, 22 ... diffuser plate, 23 ... direct light incident prevention shade, 30 ... moving part, 31A, 31B ... strut, 32A, 32B ... Drive unit, 40 ... Imaging unit, 41 ... CCD camera, 42 ... Telecentric lens, 50 ... Determining unit, 60 ... Control unit, 70 ... Reference value Acquisition unit, 71 ... acquisition light source, 72 ... acquisition movement unit, 73 ... acquisition imaging unit, f ... reference spatial frequency, S ... surface, S1 ... inspection surface, θ: diffraction angle, λ: wavelength of incident light, d: pitch of diffraction grating.

Claims (6)

In the hologram defect determination apparatus for determining the defect of the hologram to be inspected based on the reference value f of the spatial frequency of the diffraction grating in the reference hologram,
A light source for irradiating the surface of the hologram with inspection light having a wavelength λ,
Moving means for moving the light source so as to irradiate the inspection light from an angle θ which is θ = sin ⁻¹ (1 / fλ) degrees with respect to the normal direction of the surface of the hologram;
An imaging means for imaging diffracted light generated in the normal direction when the inspection light is reflected by the surface of the hologram;
A hologram defect determination apparatus, comprising: a determination unit that determines presence or absence of a defect of the hologram based on the captured diffracted light. The hologram defect determination apparatus according to claim 1,
2. The hologram defect determination apparatus according to claim 1, wherein the light source includes a light emitting portion arranged in a ring shape along a periphery of a normal line to the surface of the hologram. In the hologram defect determination apparatus according to claim 1 or 2,
The hologram defect determination apparatus according to claim 1, wherein the light source includes an LED as a light emitting unit that generates the inspection light. In the hologram defect determination apparatus according to claim 3,
The LED emits green light having the wavelength λ in the range of 540 to 580 nm. In the hologram defect determination device according to any one of claims 1 to 4,
A hologram defect determination apparatus, further comprising a cylindrical diffusion plate along an inner periphery of the light source. In the hologram defect determination apparatus according to any one of claims 1 to 5,
An acquisition means for acquiring a reference value f of the spatial frequency;
The acquisition means includes
A light source for acquisition that irradiates the surface of the reference hologram with inspection light of wavelength λ,
An acquisition moving means for rotating the acquisition light source so as to alternately face the front and back surfaces of the reference hologram with the reference hologram as a rotation center;
A rotating stage for rotating the reference hologram;
While the acquisition light source is rotating, the inspection light is irradiated at an angle θ (where 0 ° <θ <90 °) with respect to the normal direction of the surface of the hologram, and the inspection light is irradiated on the surface of the reference hologram. An imaging device for acquisition that images diffracted light generated in the normal direction when reflected;
Spatial frequency acquisition means for acquiring a reference value f of the spatial frequency based on the relationship between the angle θ, the wavelength λ, and the equation θ = sin ⁻¹ (1 / fλ) when the diffracted light is imaged. A hologram defect determination apparatus comprising:

Images