JPH09126947A - Hologram inspecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the photographing of a hologram, the inspection in manufacturing, the inspection after shipment and the verification simply and precisely in numerical evaluation by forming the reproduced image of the hologram on an optical sensor, and measuring the distribution of the optical intensity of the image. SOLUTION: A light source 2 projects the white light on a hologram 8 under inspection at an incident angle of the reproduced light determined at the time of photographing through a focal-point adjusting lens 1. A fiber head 3 receives the reproduced image reconstructed from the hologram 8. An optical fiber 4 guides the reproduced image to an optical head 5 as light ray. An image forming lens 6 forms the reproduced image on an optical sensor 7, and the optical-intensity distribution of the reproduced image is measured. Thus, the precise numerical measurement of the hologram can be performed. Furthermore, by recording the numerical-value information, a numerical-value control method can be applied, and the total quality can be effectively improved. In particular, since the numerical-value data as the reference remain even at the inspection after shipment, the sufficient investigation can be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram inspection apparatus used for hologram imaging, manufacturing inspection, post-shipment inspection, and hologram verification, and particularly for simple and precise numerical evaluation of holograms. The present invention relates to a hologram inspection device that can be performed.

[0002]

2. Description of the Related Art Conventionally, hologram recording and inspection in a manufacturing process (inspection of diffraction efficiency (brightness of reproduced image)) are performed by reproducing a hologram reproduced image by a reproduction light source.
A method is known in which it is visually observed or captured as a two-dimensional image by using an image pickup device such as a CCD camera, and its luminance distribution is measured.

Also known is a method of evaluating a stereoscopic image as a plurality of two-dimensional images by further changing the observation position by this method. Furthermore, as a special case, for holograms and the like created for the purpose of reading with an optical sensor, such as holograms for machine reading, a method of performing inspection using the reader is also known.

However, the hologram inspection method as described above has the following various problems. That is, first of all, the inspection by hand at the time of photographing the hologram or in the manufacturing process is not an inspection by quantitative numerical values, so it is difficult to apply a numerical control method and it is difficult to take measures for quality control. Has become.

In addition, in a quality follow-up survey of holograms after shipping, there is no quantitative numerical value to compare with the state at the time of shipping, so only the memory of the inspector is relied upon, so a sufficient survey is conducted. Is very difficult to do.

Further, in the determination of authenticity of a hologram used for security, as in the case of the inspection after shipping of the hologram, not only a clear determination criterion remains, but most of the users are laymen. There is a possibility of making a wrong decision even for a bad counterfeit product.

Even in this case, there is a problem that the price of the reader becomes expensive. Furthermore, when performing evaluation as an image, it is common to make a photographic evaluation such as shadow-based or highlight-based, but it is very difficult to obtain it numerically. Is.

[0008]

As described above, in the conventional hologram inspection method, the hologram photographing,
There is a problem in that it is difficult to carry out numerical inspections during manufacturing, post-shipment inspection, and hologram verification.

An object of the present invention is to provide a hologram inspecting device capable of easily and precisely performing numerical evaluations for photographing a hologram, inspecting at the time of manufacturing, inspecting after shipping, and verifying a hologram. It is in.

[0010]

In order to achieve the above object, first, a hologram inspection apparatus of the invention according to claim 1 is provided with an optical element for focus adjustment, and a hologram to be inspected is provided. A light source for injecting white light at a reproduction light incident angle determined at the time of shooting in a substantially vertical or oblique direction, and an optical system having an optical waveguide for guiding a reproduction image reproduced from a hologram by incidence of white light by the light source, The optical system is provided with an optical sensor that converts the reproduced image of the hologram guided as a light beam into an electric signal and detects it, and the reproduced image of the hologram is formed on the optical sensor to measure the light intensity distribution. .

On the other hand, the hologram inspection apparatus of the invention according to claim 2 is the hologram inspection apparatus of the invention according to claim 1, in which the relative positions of the light source, the optical system, and the optical sensor are held. And a mechanical movement mechanism for mechanically changing the relative position between the hologram and the inspection device body held by the hologram.

Here, as the optical waveguide of the above optical system, it is preferable to use an optical waveguide such as an optical fiber having mechanical flexibility as described in claim 3, for example. In addition, it is preferable that the optical waveguides such as the above-mentioned optical fibers are arranged in an array.

Therefore, first, in the hologram inspection apparatus of the invention according to claim 1, the reproduced image of the hologram from the area illuminated by the light source is picked up by the optical sensor through the optical system, so that the reproduced image of the hologram appears. Can be obtained as an electric signal.

Further, the diffraction efficiency, that is, the brightness of the reproduced image can be known from the intensity of the electric signal of the optical sensor, and the digitized extremely accurate measurement can be performed.

Further, since the distribution of the diffracted light can be grasped as the brightness distribution on the optical sensor surface, the grating pitch and the grating direction of the diffraction grating in the portion where the light is incident are calculated from the brightness distribution. Can be obtained by

As described above, it becomes possible to perform a simple and precise numerical evaluation of the hologram. On the other hand, claim 2
In the hologram inspection apparatus of the invention corresponding to the above, by adding a mechanical movement mechanism so that the hologram and the inspection apparatus main body can move relative to each other, partial measurement at a plurality of points on the hologram surface can be performed. It can be done arbitrarily and can easily perform photographic evaluation.

Further, in the hologram inspection apparatus according to the inventions corresponding to claims 3 and 4, the optical waveguides of the optical system are arranged by bundling the optical waveguides such as optical fibers having mechanical flexibility in an array. By using the optical sensor, the position of the optical sensor can be freely selected, so that the device itself can be made compact, and in addition, even if the mechanical arrangement is changed, it is possible to easily cope with it. be able to.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. (First Embodiment) FIG. 1 is a schematic diagram showing an example of the overall configuration of a hologram inspection apparatus according to this embodiment.

That is, as shown in FIG. 1, the hologram inspection apparatus of this embodiment has a light source 2 having a lens 1 which is an optical element for focus adjustment, a fiber head 3, and mechanical flexibility. An optical fiber 4 which is an optical waveguide,
Ejection side optical head 5, imaging lens 6, and optical sensor 7
And a support portion (not shown).

An optical system is composed of the fiber head 3, the optical fiber 4, the exit side optical head 5 and the image forming lens 6. Here, the light source 2 is arranged in a direction substantially perpendicular or oblique to the hologram 8 to be inspected.
The white light is incident at the reproduction light incident angle determined at the time of shooting.

As the light source 2, an ordinary white light source such as an incandescent lamp, a metal halide lamp, a mercury lamp, or a fluorescent lamp can be used. Also, the focus adjustment lens 1
Is to be incorporated into the light source 2 to obtain the desired light.

As the optical element for focus adjustment, the optical position of the light source 2 can be controlled with respect to the hologram 8, and for example, a convex lens, a concave lens or the like can be used alone or in combination. .

On the other hand, the fiber head 3 receives the reproduced image reproduced from the hologram 8 by the incident white light from the light source 2. The optical fiber 4 guides the reproduced image reproduced by the hologram 8 received by the fiber head 3 to the emission side optical head 5 as a light beam.

The optical fiber 4 can be composed of an optical element capable of designing a light beam in a two-dimensional manner, such as those arranged in a bundle in an array. Further, the emission side optical head 5 emits a reproduced image of the hologram guided as a light beam by the optical fiber 4.

FIG. 2 is a schematic view showing an example of the above optical system. That is, as shown in FIG. 2, both ends of the optical fiber 4 are geometrically arranged and fixed, and the middle part can be freely bent by the mechanical flexibility of the optical fiber 4 itself.

On the other hand, the image forming lens 6 forms the reproduced image emitted by the emission side optical head 5 on the optical sensor 7. Further, the optical sensor 7 converts the reproduced image (diffracted light) of the hologram imaged by the imaging lens 6 into an electric signal and detects it. Then, by recording and processing the converted signal from the optical sensor 7 as information, desired information can be obtained.

As the optical sensor 7, a two-dimensional light receiving element such as a CCD or an image pickup tube arranged in a plane can be appropriately selected according to the operating environment such as the brightness of the light source 2.

Further, a support portion (not shown) holds the relative positions of the light source 1, the optical system, and the optical sensor 7. The size of this supporting portion can be determined from the distribution of the grating pitch of the diffraction grating forming the hologram 8 to be measured and the range in the grating direction.

In this case, the following formula can be used to determine the dimensions. Λ = λ / (sin θ _o + sin θ _r ) Λ: Lattice pitch λ: Ray wavelength θ _o : Incident light incident angle θ _r : Diffracted light exit angle where λ, Λ, θ _o , and θ _r are holograms. Since it is set when shooting 8, the number is used for white light reproduction, so set the range of λ according to the case of white light reproduction,
The range is calculated, an appropriate position for image observation is determined, and the reproduction light incident position of the optical fiber 4 is set.

Next, the operation of the hologram inspection apparatus of this embodiment having the above-described structure will be described. First, the focus adjusting lens 1 is arranged in the light source 2 positioned so that the reproduction light is incident at an appropriate angle for reproducing the hologram 8, and the light source 2 is placed at the proper illumination position 9 that provides an appropriate reproduction condition. Adjust the virtual image position.

Next, the reproduced image of the hologram 8 reproduced under such an appropriate condition is formed on the optical sensor 7 by the image forming lens 6, and the fiber head 3 and the optical fiber 4 are provided in the path thereof. , And the exit side optical head 5 are arranged so that the optical fiber 4
The optical path can be deflected in a desired direction by utilizing the mechanical flexibility of.

In this case, the area 1 illuminated by the light source 2
By picking up the reproduced image of the hologram 8 from 0 by the optical sensor 7 through the optical system, the state of the reproduced image of the hologram 8 can be obtained as an electric signal.

Further, the diffraction efficiency, that is, the brightness of the reproduced image can be known from the intensity of the electric signal of the optical sensor 7 and the like, and the digitized extremely accurate measurement can be performed.

Further, the distribution of the diffracted light can be grasped as a luminance distribution on the surface of the optical sensor 7, and from the luminance distribution, the grating pitch and the grating direction of the diffraction grating at the portion where the light is incident are calculated. Can be obtained by

Further, the optical fiber 4 which is an optical waveguide is fixed by geometrically arranging both ends thereof, and the middle part can be freely bent by the mechanical flexibility of the optical fiber 4 itself. By doing so, since the position of the optical sensor 7 can be freely selected, it can be useful for downsizing the device itself, and in addition, even if the mechanical arrangement is changed, only the direction of the head is changed. Can be easily dealt with.

As described above, the hologram inspecting apparatus of this embodiment is provided with the focus adjusting lens 1 and is almost perpendicular or oblique to the hologram 8 to be inspected.
A light source 2 which emits white light at a reproduction light incidence angle determined at the time of shooting, a fiber head 3 which guides a reproduced image reproduced from a hologram 8 by incidence of white light by the light source 2, an optical fiber 4 which is an optical waveguide, An optical system including an exit side optical head 5 and an imaging lens 6, an optical sensor 7 for converting a reproduced image of a hologram 8 guided as a light beam by the optical system into an electric signal and detecting the electric signal, a light source 1, an optical system,
The optical sensor 7 is composed of a supporting portion for holding the relative positions of the three members, and a reproduced image of the hologram 8 is formed on the optical sensor 7 to measure its light intensity distribution.

Therefore, the following various effects can be obtained. (A) It becomes possible to perform the digitized and extremely accurate measurement of the hologram 8. Furthermore, by recording this numerical information, it is possible to adapt the numerical management method and effectively improve the overall quality. In particular, even in the inspection after shipping, since the reference numerical data remains, it is possible to perform a sufficient investigation.

(B) Since the device is integrated, the structure can be simplified and the device can be easily miniaturized. As a result, since anyone can perform accurate measurement, there is an advantage that it is possible to suppress variation in measurement by a measurer and to reduce failures.

(C) Not only can consumer products of various specifications be used for the light source 2 and the optical sensor 7, but also expensive parts such as lasers can be dispensed with, so the cost of the device can be reduced. It becomes easy to plan.

(D) Since the optical system is composed of mechanically flexible parts, it is easy to mechanically reduce the cost, and the optical system can be changed in accordance with the design change. There are many advantages such as unnecessary.

(Second Embodiment) In the hologram inspection apparatus of the first embodiment, a support for holding the relative positions of the light source 2, the optical system, and the optical sensor 7 which constitute the inspection apparatus main body. A mechanical movement mechanism that mechanically changes the relative position between the unit and the hologram 8 may be added.

Here, as the mechanical movement mechanism for mechanically changing the relative position between the inspection apparatus main body and the hologram 8, for example, a mechanism for mechanically moving the inspection apparatus main body,
Alternatively, a mechanism that mechanically moves the hologram 8 (for example, an XY stage or the like) can be used.

In the hologram inspection apparatus of the present embodiment configured as described above, the relative positional relationship between the hologram 8 and the inspection apparatus main body is changed by the mechanical movement mechanism, so that a portion on the hologram 8 surface is obtained. Can be illuminated to measure the reproduced image, that is, partial measurement at a plurality of points on the hologram 8 surface can be arbitrarily performed.

This makes it possible to quantitatively measure the reproduced image at any position on the hologram 8 (the point in the creation of the pattern forming the hologram 8), so that the photographic evaluation can be performed easily. Is possible.

As described above, the hologram inspection apparatus of the present embodiment is provided with the focus adjustment lens 1 and is almost perpendicular or oblique to the hologram 8 to be inspected.
A light source 2 which emits white light at a reproduction light incidence angle determined at the time of shooting, a fiber head 3 which guides a reproduced image reproduced from a hologram 8 by incidence of white light by the light source 2, an optical fiber 4 which is an optical waveguide, An optical system including an exit side optical head 5 and an imaging lens 6, an optical sensor 7 for converting a reproduced image of a hologram 8 guided as a light beam by the optical system into an electric signal and detecting the electric signal, a light source 1, an optical system,
The reproduced image of the hologram 8 is composed of a support portion that holds the relative positions of the three optical sensors 7 and a mechanical movement mechanism that mechanically changes the relative positions of the inspection device body and the hologram 8. Is imaged on the optical sensor 7 and the light intensity distribution thereof is partially measured.

Therefore, it is of course possible to obtain the same effect as that of the hologram inspection apparatus of the first embodiment.
In addition to this, the following various effects can be obtained.

That is, since a mechanical movement mechanism is added so that the hologram 8 and the inspection apparatus main body can move relative to each other, partial measurement can be arbitrarily performed at a plurality of points on the hologram 8 surface. It becomes possible to easily perform photographic evaluation.

Further, for the above reason, since the hologram 8 can be partially inspected, the light source 2 can be made smaller, so that the apparatus can be made more compact.

[0049]

As described above, according to the invention according to claim 1, the optical element for focus adjustment is provided, and it is determined at the time of photographing in a direction substantially perpendicular or oblique to the hologram to be inspected. A light source for injecting white light at an angle of reproduction light incidence, an optical system having an optical waveguide for guiding a reproduced image reproduced from the hologram by incidence of white light by the light source, and reproduction of the hologram guided as a light beam by the optical system. With an optical sensor that converts the image into an electrical signal and detects it,
Since the reproduced image of the hologram is formed on the optical sensor and its light intensity distribution is measured, the hologram is photographed,
It is possible to provide a compact and inexpensive hologram inspecting apparatus that can easily and precisely perform numerical inspections during manufacturing, post-shipment inspection, and hologram verification.

On the other hand, according to the invention corresponding to claim 2,
In the hologram inspection apparatus of the invention according to claim 1, a support portion that holds a relative position of the light source, the optical system, and the optical sensor, and an inspection apparatus main body held by the hologram and the support portion are provided. Since I added a mechanical movement mechanism that mechanically changes the relative position,
It is possible to provide a more compact and inexpensive hologram inspecting device that can perform partial measurement at a plurality of points on the hologram surface arbitrarily and can easily perform photographic evaluation.

According to the inventions corresponding to claims 3 and 4, in the hologram inspection apparatus of the invention according to claim 1 or 2, mechanical flexibility is provided as the optical waveguide of the optical system. Since an optical waveguide such as a certain optical fiber which is bundled and arranged in an array is used, it is possible to easily cope with a change in mechanical arrangement and to provide a more compact hologram inspection apparatus.

[Brief description of the drawings]

 .

FIG. 1 is a schematic diagram showing a first embodiment of a hologram inspection apparatus according to the present invention.

FIG. 2 is a schematic diagram showing an example of an optical system in the hologram inspection apparatus according to the first embodiment.

[Explanation of symbols]

 1 ... Focus adjustment lens, 2 ... Light source, 3 ... Fiber head, 4 ... Optical fiber, 5 ... Ejection side optical head, 6 ... Imaging lens, 7 ... Optical sensor, 8 ... Hologram, 9 ... Proper illumination position, 10 ... Lighting range.

Claims (4)

[Claims] 1. A light source comprising an optical element for focus adjustment, which emits white light at a reproduction light incident angle determined at the time of photographing, which light is substantially perpendicular or oblique to a hologram to be inspected, and the light source. An optical system having an optical waveguide that guides a reproduced image reproduced from the hologram by the incidence of white light, and an optical sensor that converts the reproduced image of the hologram guided as a light beam by the optical system into an electric signal and detects the electric signal. A hologram inspection apparatus, wherein a reproduced image of the hologram is formed on an optical sensor and its light intensity distribution is measured. 2. The hologram inspection apparatus according to claim 1, wherein a support portion that holds a relative position of the light source, the optical system, and the optical sensor is held by the hologram and the support portion. A hologram inspection apparatus characterized in that a mechanical movement mechanism for mechanically changing the relative position to the inspection apparatus main body is added. 3. The hologram inspection apparatus according to claim 1 or 2, wherein an optical waveguide such as an optical fiber having mechanical flexibility is used as the optical waveguide of the optical system. 4. The hologram inspection apparatus according to claim 3, wherein the optical waveguides such as the optical fibers are arranged in an array.