JPH0784501A - Method and device for verifying hologram - Google Patents

Abstract

PURPOSE:To discriminate the quality of a hologram with high accuracy by comparing the wave surface of diffracted light reproduced from a master hologram being the reference of verification with the wave surface of the diffracted light reproduced from the hologram to be verified being an object whose quality is discriminated. CONSTITUTION:A hologram verifying device is constituted of a 1st reproducing illumination light source 1, a 2nd reproducing illumination light source 2, a half mirror 3 being an interference optical system, a lens for enlargement 4 and a diffusing plate for observation 5. The diffracted light from the master hologram 6 illuminated by the light source 1 and the diffracted light from the hologram to be verified 7 are reflected to the same direction by the half mirror 3 and the interfered light enlarged by the lens 4 to be wholly uniform or to be partially deviated so as to be projected on the diffusing plate 5. Consequently, the result obtained by comparing the diffracted light reproduced from two holograms 6 and 7 is expressed as a projected image on the diffusing plate 5, so that the quality of the hologram 7 is discriminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram verification method and apparatus for determining the quality of a hologram, and particularly with a very high accuracy regardless of the hologram reproduction conditions and the individual differences of the measurer. The present invention relates to a hologram verification method and device capable of discriminating the quality of.

[0002]

2. Description of the Related Art Conventionally, as a method for determining the quality of a hologram, there is known a method in which a hologram is reproduced under a predetermined condition and the reproduced image is verified by an image processing device.

Further, instead of verifying by an image processing apparatus, a method of preparing a hologram as a reference for verification (hereinafter referred to as a master hologram) in advance and visually comparing it with the hologram to determine the quality of the hologram is also available. Are known.

However, in the method of reproducing a hologram under a predetermined condition and then verifying the hologram, the reproduction condition of the hologram is almost the same in most cases, but the reproduction condition is intentionally changed. In such a case, since the recorrection condition is different, it is necessary to separately prepare a master hologram as a reference for verification, which is a problem.

Further, in the method of visually inspecting,
Even if the hologram reproduction conditions are different, this does not pose a problem so much, but since the measurer (human) performs the verification, the problem is that the measurer tends to have variations in the measurement results.

Furthermore, any of the above methods is not suitable for performing more accurate verification.

[0007]

As described above, in the conventional hologram quality determination method, it is necessary to separately prepare a master hologram as a reference for verification when hologram recorrection conditions are different. There is a problem that the measurement result varies depending on the person and high-precision verification cannot be performed.

The present invention has been made in order to solve the above problems, and determines whether a hologram is good or bad with extremely high accuracy, regardless of the hologram reproduction conditions and the individual differences of the measurers. An object of the present invention is to provide a hologram verification method and device capable of performing the hologram verification.

[0009]

In order to achieve the above object, first, in the invention corresponding to claim 1, in a hologram verification method for determining the quality of a hologram, the hologram is reproduced from a master hologram serving as a verification reference. The quality of the hologram to be verified is judged by comparing the wavefront of the diffracted light with the wavefront of the diffracted light reproduced from the hologram to be verified which is the object of the quality judgment.

Here, in particular, an optical interference method is used as a method of comparing the wavefronts of the diffracted lights.

On the other hand, in the invention corresponding to claim 3, in the hologram verification device for judging the quality of the hologram,
Illuminated by a first reproduction illumination light source that illuminates a master hologram that serves as a reference for verification, a second reproduction illumination light source that illuminates a verification target hologram that is a target of quality determination, and a first reproduction illumination light source. Interference optical system that interferes with the wavefront of the diffracted light reproduced from the master hologram and the wavefront of the diffracted light reproduced from the hologram to be verified illuminated by the second reproduction illumination light source. An interference fringe projection means for projecting the interference light, which is the comparison result of the wavefronts of the diffracted light, as an interference fringe.

Further, in the invention according to claim 4, in the hologram verifying device of the invention according to claim 3, the state of the interference fringes projected by the interference fringe projection means is evaluated by image processing, An image processing means for automatically determining the quality of the verification hologram is added.

Further, in the invention corresponding to claim 5, in the hologram verifying device of the invention according to claim 3 or 4, the interference light which is the comparison result by the interference optical system is enlarged to the interference fringe projecting means. An interference light magnifying means for projecting is added.

Here, in particular, as the image processing means,
The number of interference fringes projected by the interference fringe projecting means is counted and compared with a reference value for the quality determination to determine the quality of the hologram to be verified.

[0015]

Therefore, in the hologram verification method and apparatus of the present invention, the wavefront of the diffracted light reproduced from the master hologram illuminated by the first reproduction illumination light source and the second reproduction illumination light source are illuminated. The wavefront of the diffracted light reproduced from the hologram to be verified is interfered by an interference optical system to directly compare the two wavefronts, and the interference light that is the comparison result of the wavefronts of the respective diffracted light is used as an interference fringe. Since the quality of the hologram to be verified is judged by displaying the image with the image output means, the measurement can be performed regardless of the reproduction condition of the hologram, and the measurement can be performed regardless of the individual difference of the measurer.

Since the measurement with the wavelength resolution of the reproducing illumination light source can be performed, the quality of the hologram can be determined with higher accuracy than the conventional method.

Further, by using an optical interference method as a method of comparing the wavefronts of the respective diffracted lights, it is possible to sensitively measure distortion, scratches, dust, etc. as well as image distortion. .

Further, in the hologram verifying apparatus of the invention according to claim 5, the interference light as the comparison result by the interference optical system is enlarged by the interference light expanding means and projected on the interference fringe projecting means. It can be observed even if it becomes a fine interference fringe.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a master hologram serving as a reference for verification is prepared in advance, and for reproducing monochromatic light or white light whose illumination position can be freely changed by an optical or mechanical method. Using the diffracted light from the master hologram reproduced by the illumination light source as a reference, the diffracted light from the hologram to be verified which is reproduced by another illumination light source for reproduction and which is the object of the quality judgment is used by the optical interference method. Then, a method of comparing both wavefronts and judging the quality of the hologram to be verified from the comparison result (state of interference fringes) is used.
A method such as visual inspection or mechanical measurement is used to determine the comparison result.

An embodiment of the present invention based on the above concept will be described below in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing a configuration example of a hologram verification device according to the present invention. Here, a case where a Michelson interferometer is used will be described as an example.

That is, the hologram verification apparatus of this embodiment, as shown in FIG. 1, includes a first reproduction illumination light source 1, a second reproduction illumination light source 2, and a half mirror 3 which is an interference optical system. It is composed of a magnifying lens 4 which is an interference light magnifying means, and an observation diffusion plate 5 which is an interference fringe projecting means.

Here, the first reproduction illumination light source 1 illuminates the master hologram 6, which is a reference for verification, with monochromatic light or white light.

The second reproduction illumination light source 2 illuminates the hologram 7 to be verified, which is the object of quality judgment, with monochromatic light or white light.

Further, the half mirror 3 has the wavefront of the diffracted light reproduced from the master hologram 6 illuminated by the first reproduction illumination light source 1 and the hologram to be verified illuminated by the second reproduction illumination light source 2. This is to interfere with the wavefront of the diffracted light reproduced from 7.

The magnifying lens 4 is a half mirror 3.
Diffusing plate 5 for observation by enlarging the interference light which is the comparison result by
Is to be projected on.

Further, the observation diffusion plate 5 is composed of, for example, a screen, and projects the interference light from the magnifying lens 4 as interference fringes.

FIG. 2 is a schematic diagram showing a configuration example of each of the reproduction illumination light sources 1 and 2 in FIG.

That is, the reproduction illumination light sources 1 and 2 are
As shown in FIG. 2, a stand 8 with position adjustment, which is a jig for freely changing the angle when the holograms 6, 7 are illuminated from arbitrary positions, and an optical system for changing the optical distance. The zoom lens 9 and the light source 10 are provided. By adjusting these components, a desired reproduction condition can be created.

Next, a hologram verifying method by the hologram verifying apparatus of this embodiment having the above-mentioned structure will be described.

In FIG. 1, the diffracted light from the master-hologram 6 illuminated by the first reproduction illumination light source 1 and the diffracted light from the hologram to be verified 7 are reflected by the half mirror 3 in the same direction. , The interfered light is magnifying lens 4
In the whole is uniformly or partially biased and expanded,
It is projected on the observation diffusion plate 5. And as a result,
The result of comparing the diffracted light reproduced from the two holograms 6 and 7 is displayed as a projected image on the observation diffusion plate 5,
The quality of the hologram 7 to be verified can be determined from the image.

FIG. 3 is a conceptual diagram showing an example of the state of interference fringes when determining the quality of the hologram to be verified 7.

That is, when the hologram to be verified 7 is a non-defective product, there is no difference in the wavefront of each diffracted light.
As shown in FIG. 3A, no interference fringes are formed, and when the hologram to be verified 7 is a defective product, there is a slight difference in the wavefront of each diffracted light. As shown in FIG. 3C, since interference fringes are formed but the number of fringes is small, and when the hologram to be verified 7 is a defective product, a large difference occurs in the wavefront of each diffracted light. As described above, the interference fringes are formed in a state where the number of fringes is large.

Therefore, the quality of the hologram to be verified 7 can be determined by visually evaluating the state of the interference fringes projected on the observation diffusion plate 5.

In the case of this example, the magnifying lens 7 is inserted between the half mirror 3 and the observing diffuser plate 5, so that observation is possible even if fine interference fringes are formed. You can

On the other hand, in order to illuminate the holograms 6 and 7 from arbitrary positions, its angle and distance may be changed. Therefore, in this case, as shown in FIG. 2, in each of the reproduction illumination light sources 1 and 2, the stand 8 with position adjustment, the zoom lens 9, and the light source 10 are adjusted so that the incident angles to the holograms 6 and 7 are increased. By freely changing the distance to the light source 10, the desired reproduction condition can be created.

As described above, in the present embodiment, the first reproduction illumination light source 1 for illuminating the master hologram 6 as a reference for verification with monochromatic light or white light, and the hologram to be verified which is the object of quality judgment. Second reproduction illumination light source 2 for illuminating 7 with monochromatic light or white light, wavefront of diffracted light reproduced from master hologram 6 illuminated by first reproduction illumination light source 1, and second reproduction Half mirror 3 that interferes with the wavefront of the diffracted light reproduced from the hologram to be verified 7 illuminated by the illumination light source 2 for interference, and the interference light that is the comparison result by the half mirror 3 is enlarged and projected on the observation diffusion plate 5. The hologram verifying device is composed of the magnifying lens 4 and the observing diffuser plate 5 that projects the interference light from the magnifying lens 4 as interference fringes, and is illuminated by the first reproducing illumination light source 1. The wavefront of the diffracted light reproduced from the target hologram 6 and the wavefront of the diffracted light reproduced from the hologram to be verified 7 illuminated by the second reproduction illumination light source 2 are caused to interfere with each other by the half mirror 3. Is directly compared, and the interference light, which is the comparison result of the wavefronts of the respective diffracted lights, is projected as interference fringes by the observation diffusion plate 5 through the magnifying lens 4 to determine the quality of the hologram to be verified 7. It was done like this.

Therefore, the following various effects can be obtained.

(A) Since the wavefront of the diffracted light reproduced from the master-hologram 6 and the wavefront of the diffracted light reproduced from the hologram to be verified 7 are directly compared, the measurement is performed irrespective of the unique reproduction condition of each hologram. Can be performed.

(B) Since the wavefront of the diffracted light reproduced from the master-hologram 6 and the wavefront of the diffracted light reproduced from the hologram to be verified 7 are directly compared, the measurement is performed without depending on the individual difference of the measurer. Is possible.

(C) Since the measurement can be performed with the wavelength resolution of the reproduction illumination light sources 1 and 2, the quality of the hologram to be verified 7 can be determined with extremely high accuracy as compared with the conventional method. .

(D) Since the optical interference method is used as a method of comparing the wavefronts of the respective diffracted lights, the image distortion and the like as well as dirt, scratches, dust and the like are extremely sensitively measured. It becomes possible.

(E) Since the interference light, which is the result of comparison by the half mirror 3, is magnified by the magnifying lens 4 and projected on the observation diffusion plate 5, it is possible to observe even a fine interference fringe.

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

(A) In the above embodiment, the quality of the hologram 7 to be verified is judged by visually evaluating the state of the interference fringes projected on the observation diffusion plate 5. Not limited to this, if necessary, the state of the interference fringes projected on the observation diffusion plate 5 is evaluated by image processing to automatically determine the quality of the hologram to be verified 7 (for example, the observation diffusion plate). (5) A method of counting the number of interference fringes projected on the image 5 and comparing it with the reference value of the quality judgment to judge the quality of the hologram to be verified 7) An image processing device is added to form a hologram verification device. You may do it.

(B) In the above embodiment, the case where the magnifying lens 4 is used as the interference light magnifying means has been described.
Not limited to this, as the interference light magnifying means, for example, a convex mirror,
Other elements such as concave mirrors, prisms, etc. may be used.

(C) In the above embodiment, the interference light magnifying means (magnifying lens 4 and the like) is not an essential element of the present invention, and may be provided if necessary.

(D) In the above embodiment, the optical interference method is used as a method of comparing the wavefronts of the diffracted lights, but the method is not limited to this, and other methods may be used.

[0049]

As described above, according to the present invention, the first reproduction illumination light source that illuminates the master hologram that serves as a reference for verification and the second illumination light source that illuminates the hologram to be verified that is the object of quality judgment. The reproduction illumination light source, the wavefront of the diffracted light reproduced from the master hologram illuminated by the first reproduction illumination light source, and the diffracted light reproduced from the verification target hologram illuminated by the second reproduction illumination light source. An interference optics system that interferes with the wavefront, an interference fringe projection device that projects the interference light that is the comparison result of the wavefronts of the diffracted lights by the interference optical system as an interference fringe, and, if necessary, an interference fringe projection device. The image processing means evaluates the state of the interference fringes projected by the image processing to automatically determine the quality of the hologram to be verified, and, if necessary, the comparison result by the interference optical system. Equipped with an interference light magnifying means for magnifying the light and projecting it on the interference fringe projection means, it is reproduced from the wavefront of the diffracted light reproduced from the master hologram which is the reference of verification and the hologram to be verified which is the object of quality judgment Since the quality of the hologram to be verified is determined by comparing it with the wavefront of the diffracted light, the hologram can be recorded with extremely high accuracy regardless of the reproduction condition of the hologram and the individual difference of the measurer. A hologram verification method and device capable of determining pass / fail can be provided.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a hologram verification device according to the present invention.

FIG. 2 is a schematic diagram showing a configuration example of a reproduction illumination light source in the embodiment.

FIG. 3 is a conceptual diagram showing an example of a state of interference fringes when determining the quality of a hologram to be verified in the same embodiment.

[Explanation of symbols]

1 ... 1st reproduction | regeneration illumination light source, 2 ... 2nd reproduction | regeneration illumination light source, 3 ... Half mirror, 4 ... Enlarging lens, 5 ... Observation diffuser plate, 6 ... Master hologram, 7 ... Verification hologram, 8 … Stand with position adjustment, 9… Zoom lens, 1
0 ... light source.

Claims (6)

[Claims] 1. A hologram verification method for determining the quality of a hologram, the wavefront of a diffracted light reproduced from a master hologram serving as a reference for verification, and the wavefront of a diffracted light reproduced from a hologram to be verified which is a target of quality determination. The hologram verification method is characterized in that the quality of the hologram to be verified is judged by comparing with the hologram. 2. The hologram verification method according to claim 1, wherein an optical interference method is used as a method of comparing the wavefronts of the respective diffracted lights. 3. A hologram verification device for determining the quality of a hologram, wherein a first reproduction illumination light source illuminates a master hologram that serves as a reference for verification, and a second illumination light that illuminates a hologram to be verified that is a target for quality determination.
Of the reproduction illumination light source, the wavefront of the diffracted light reproduced from the master hologram illuminated by the first reproduction illumination light source, and the verification hologram illuminated by the second reproduction illumination light source. An interference optical system that interferes with the wavefront of the diffracted light, and an interference fringe projecting unit that projects the interference light that is the result of comparison of the wavefronts of the diffracted lights by the interference optical system as interference fringes. Hologram verification device. 4. The hologram verification apparatus according to claim 3, wherein the state of the interference fringes projected by the interference fringe projection means is evaluated by image processing, and the quality of the hologram to be verified is automatically determined. A hologram verification device characterized by being provided with an image processing means. 5. The hologram verifying device according to claim 3, further comprising an interference light expanding unit that expands interference light as a comparison result of the interference optical system and projects the interference light onto the interference fringe projecting unit. A hologram verification device comprising: 6. The image processing means is for counting the number of interference fringes projected by the interference fringe projecting means, and comparing the result with a reference value for judging the quality of the hologram to judge the quality of the hologram to be verified. The hologram verification device according to claim 4 or 5, characterized in that: