JP3324141B2 - Hologram manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hologram manufacturing method,
More specifically, the present invention relates to a hologram manufacturing method for manufacturing by copying a hologram for reading a barcode from a master hologram.

[0002]

2. Description of the Related Art Generally, a bar code reader is disclosed in Japanese Patent Application Laid-Open No. 63-150777.
Holograms incorporating multifocal, multi-diffraction angle holograms
The disk is irradiated with a reproducing laser beam to obtain diffracted light (scanning beam), and the scanning beam scans a barcode label, and receives the reflected light to determine the barcode.

[0003] The hologram is generally manufactured by copying from a master hologram. In manufacturing the hologram, when copying from a master hologram photographed using divergent light as both object light and reference light, copy is performed. By irradiating divergent light as reference light to the master hologram superimposed on the hologram dry plate, a copy hologram is manufactured.

An optical system for photographing a copy hologram of this type generally has a structure as shown in FIG.
It comprises an argon laser oscillator 3, a balance 22, four mirrors 23, 24, 25, 26, two spatial filters 27, 28, and the like. When shooting, first
Mirrors 23 and 24 and one spatial filter 2
7 is used to take an image of the upper portion of the copy hologram dry plate 2 (the vertical direction is determined based on the drawing). Next, the remaining two mirrors 25 and 26 and the remaining 1
The lower part of the copy hologram dry plate 2 is photographed using the spatial filters 28.

[0005]

However, in the above-described hologram manufacturing method, the two spatial filters 27 and 28 require a long working time to remove the mirror 23 closest to the argon laser oscillator 3.
, Adjustment work is required for each spatial filter, and these two adjustment works are complicated.
There was a problem that energy loss due to the partition 22 was large.

The present invention solves the above-mentioned problems, and can eliminate the operation of removing the mirror. Further, only one spatial filter is required, and the complicated adjustment operation can be reduced. Further, the screen can be omitted. It is another object of the present invention to provide a hologram manufacturing method capable of reducing energy loss due to this.

[0007]

In order to solve such a problem, a method of manufacturing a hologram according to a first aspect of the present invention is a method of manufacturing a hologram .
Lay the copy hologram plate on the star hologram ,
A hologram manufacturing method for manufacturing a hologram copy the recorded image of the master hologram to the copy hologram dry plate, and the laser oscillator, and Luz page tangential filter caused to diverge the laser beam from the laser oscillator, the space a lens for changing the parallel light divergent light from the tangential filter, a first mirror for reflecting the collimated light from the lens, a second mirror causes reflects part of reflected light from said first mirror , The first mirror
A small amount of light that is not reflected by the second mirror
Ku and also and a third mirror for reflecting a part, the
The master hologram is illuminated by the reflected light of the second mirror.
And reflected light of the third mirror.
Irradiating a master hologram .

Further, in the hologram manufacturing method according to the second invention , a copy hologram dry plate is superimposed on the master hologram.
Combined, a hologram manufacturing method by copying the recorded images of the master hologram to the copy hologram dry plate to produce a hologram, a laser oscillator, and Luz page tangential filter caused to diverge the laser beam from the laser oscillator, A fourth mirror that reflects a part of the light from the spatial filter, and a fifth mirror that reflects the light reflected from the fourth mirror, wherein the master
The hologram directs the light from the spatial filter.
And is reflected by the fifth mirror.
Is irradiated .

[0009]

According to the first and second aspects of the present invention, it is possible to simultaneously photograph both the upper side and the lower side of the copy hologram dry plate in one photographing, so that the mirror removing operation can be omitted. it can. Further, since only one spatial filter is used, complicated adjustment work can be reduced. Also, since there is no partition, energy loss due to this is not caused.

[0010]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram of an apparatus for performing the hologram manufacturing method according to the first embodiment.

This apparatus superimposes a copy hologram dry plate 2 on a master hologram 1 and
This is an apparatus for manufacturing a hologram for reading a bar code by copying the recorded image of the master hologram 1 to the hologram. Here, the master hologram 1 is a master hologram photographed by the object light and the reference light, both of which are divergent light, as described later.

This apparatus comprises an argon laser oscillator 3, one spatial filter 4, and a convex lens 5.
, A first mirror 6, a second mirror 7, and a third mirror 8.

The spatial filter 4 is composed of a combination of a lens and an aperture, and diverges a laser beam from the argon laser oscillator 3.

The convex lens 5 changes divergent light from the spatial filter 4 into parallel light.

The first mirror 6 is a flat mirror, and reflects parallel light from the convex lens 5 to bend it.

The second mirror 7 is a flat mirror.
A part of the reflected light from the mirror 6 is reflected and bent.

The third mirror 8 is a flat mirror.
The remaining part of the light reflected from the mirror 6 is reflected and bent.

The reflected light, which is the parallel light of the second mirror 7, is either the upper side or the lower side of the master hologram 1 (the upper side in this embodiment. The vertical relationship is determined based on the drawings. ), And the reflected light, which is the parallel light of the third mirror 8, irradiates the other side (the lower side in this embodiment) as the reference light L.

In photographing a copy hologram using the apparatus having the above-described configuration, the first, second, and third mirrors 6, 7, 8, the convex lens 5, and the spatial filter 4 are set at predetermined positions, respectively. , The spatial filter 4 is adjusted so that desired divergent light can be obtained. Then, as in the usual method, the laser beam is emitted from the argon laser oscillator 3 to perform photographing.

According to the hologram manufacturing method of this embodiment,
Since the operation of removing the mirror as in the related art can be omitted, the operation time can be shortened, and since only one spatial filter 4 is used, the adjustment operation can be performed only once. Labor can be reduced, and energy loss can be reduced because no screen is provided.

When the recorded image of the master hologram 1 photographed by the object light and the reference light, both of which are divergent light, is copied onto the copy hologram dry plate 2 by the parallel light reference light L, it is determined whether the diffraction efficiency is reduced. It becomes a problem.

In general, when the wavelengths of the photographing light and the reproduction light are different, it is necessary to correct the incident angle of the reproduction light. Therefore, when the reproduction light is divergent light, for example, as shown in FIGS. 2, 3, and 4, the correction angle θ (= 6.5 °) depends on the position, and is 5.7 °, 7.3 °, As shown as 8.0 °, the diffraction efficiency is reduced.

On the other hand, when the reproduction light is parallel light, since the correction angles coincide at all positions, the diffraction efficiency does not decrease, which is a preferable condition.

However, the ratio of first-order light / zero-order light deviates from the ratio in the original divergent light. However, this ratio is 1
Since a hologram with a high diffraction efficiency can be formed in a wide range in the vicinity (0.8 to 1.8), a copy hologram with a high diffraction efficiency can be formed uniformly and at a high yield even when exposed to parallel light.

Next, a method for manufacturing the master hologram 1 will be described with reference to FIGS.

FIG. 5 is a conceptual diagram of an apparatus for photographing the master hologram 1.

This photographing apparatus comprises an argon laser oscillator 3, a plurality of spatial filters 4, a plurality of mirrors 9, a plurality of beam splitters 10, a partition 11, and the like. It is configured to use divergent light.

The reason why the diverging light is used for both the object light and the reference light is based on the following reason.

Generally, a laser oscillator is large due to the influence of sensitivity wavelength and power at the time of photographing. However, it is desirable that the laser oscillator is small at the time of reproduction, so that there is a difference between the wavelengths of photographing light and reproduction light (for example, a laser oscillator for photographing). The wavelength of the photographing light when using an argon laser oscillator is 488 nm or 514 nm, while the wavelength of the reproducing light is 670 nm or 633 nm when using a semiconductor laser oscillator or a He-Ne laser oscillator as the reproducing laser oscillator. Become.). For this reason, when photographing with parallel reference light, astigmatism (a phenomenon in which the focal length of the laser beam is shifted in the vertical direction and the horizontal direction) occurs during reproduction, and a beam of diffracted light (scanning beam) is generated. The shape becomes elliptical. When the scanning beam becomes elliptical, as shown in FIG. 6, when the barcode label 12 is scanned obliquely, the reflected light (information light) becomes unclear and the reading performance is reduced. In other words, the convergence performance is reduced. Reading performance is insufficient.

On the other hand, if the scanning beam has a substantially perfect circular shape,
As shown in FIG. 7, even when the barcode label 12 is scanned obliquely, the reading performance does not decrease and sufficient convergence performance and reading performance can be obtained.

Therefore, in this embodiment, divergent light is used as reference light so that a scanning beam having a substantially perfect circular shape can be obtained. Then, shooting was performed under the following shooting conditions.

Hereinafter, the setting of the photographing conditions of the master hologram 1 will be described in order with reference to FIG.

(1) Setting of photographing and reproduction conditions Calculation of laser crossing angle An optical system as shown in FIG. 9 is set, and the laser crossing angle θ ₂ at the time of photographing (the optical axis of divergent light from object light divergence point A and from crossing angle theta _a to the vertical axis of the master hologram 1 dry plate, the angle obtained by subtracting the crossing angle theta _b between the vertical axis and the optical axis of the master hologram 1 dry plate of divergent light from the reference light diverging point B, that is, theta _a
−θ _b ) is calculated.

In this calculation method, the relationship shown in the following equation (1) is established between the interference fringe interval ΔX, the laser beam wavelength λ, and the laser crossing angle θ as shown in FIG. Therefore, under the condition of △ X, between the laser beam wavelength λ ₁ and the laser crossing angle θ ₁ at the time of reproduction and the laser beam wavelength λ ₂ and the laser crossing angle θ ₂ at the time of shooting, Equation (2) holds, and from this equation (2), the laser crossing angle θ ₂ during imaging is determined.

[0036] △ X = λ / [2sin ( θ / 2)] (1) λ 1 / [2sin (θ 1/2)] = λ 2 / [2sin (θ 2/2)] (2) correction angle of The calculated correction angle θ _b is determined by the laser
This is necessary because the maximum efficiency incidence angle differs depending on the wavelength λ of the beam.

[0037] The correction angle θ _b is calculated as follows. That is, as shown in FIG. 11, the interval ΔX of the interference fringes at the time of photographing, the intersection angle θ _i between the interference fringes and the vertical axis of the master hologram 1 dry plate, the correction angle θ _b , the laser cross angle θ _2, and the laser beam Between the wavelengths λ _2, the following equation (3) holds, and the following equation (4) based on the above equation (1) holds.
On the other hand, as shown in FIG. 12, _{assuming that} the maximum efficiency can be obtained when the intersection angle between the optical axis of the laser beam and the vertical axis of the master hologram 1, that is, the incident angle is θ _d during reproduction, the incident angle θ _d Needs to satisfy the Bragg condition expressed by the following equation (5). Therefore, θ _{i of the following} equation (3) and ΔX of the following equation (4) are substituted into the following equation (5), and the incident angle θ _d during reproduction is considered to be zero. Substituting θ _d = 0, thereby obtaining θ _b .

[0038] _{θ i -θ b = θ 2/} 2 (3) △ X = λ 2 / [2sin (θ 2/2)] (4) θ d -θ i = sin -1 [λ 1 / (2 △ X)] (5) The optical axis of the object light divergence point A and the optical axis of the reference light divergence point B are determined from the laser crossing angle θ ₂ and the correction angle θ _b, and any point on these optical axes is determined as the object light. The divergence point A and the reference light divergence point are defined.

The following hologram imaging formulas (6), (7), (8)
Then, the coordinates of the reproduced image divergence point are obtained.

(1 / λ ₁ ) (x _1a / R _1a -x _1b / R _1b ) = (1 / λ ₂ ) (x _2a / R _2a -x _2b / R _2b ) (6) (1 / λ _{1 ) (y 1a / R 1a -y} 1b / R 1b) = (1 / λ 2) (y 2a / R 2a -y 2b / R 2b) (7) (1 / λ 1) (1 / R 1a -1 / R _1b ) = (1 / λ ₂ ) (1 / R _2a −1 / R _2b ) (8) Here, although not shown, x _1a and y _1a are the x and y coordinates of the reproduced image divergence point, x _1b and y _1b are the x and y coordinates of the divergence point of the reproduction light, R _1a is the distance between the divergence point of the reproduction image and the center point of the master hologram 1 (that is, the focal length during reproduction), and R _1b is the divergence point of the reproduction light. And the center point of the master hologram 1. As shown in FIG. 9, x _2a and y _2a are the x and y coordinates of the divergence point A of the object light at the time of shooting, x _2b and y _2b are the x and y coordinates of the divergence point B of the reference light at the time of shooting, and R _2a the distance between the object beam divergence point a and the master hologram 1 dry plate center point O at the time of photographing (i.e., object beam distance), R _2b reference beam divergence point of time of photographing B
And the distance between the master hologram 1 and the center point O of the dry plate (that is, the reference light distance). Note that x _1b , y _1b ,
R _1b is predetermined.

(2) Calculation of Diffraction Direction The diffraction direction is calculated based on the x and y coordinates (x _1a , y _1a ) of the reproduced image divergence point.

(3) Evaluation Surface Distance Setting The distance from the master hologram center point O of the evaluation surface is calculated based on the x and y coordinates (x _1a , y _1a ) of the reproduced image divergence point and the diffraction direction. Here, the evaluation surface refers to a surface that is set perpendicular to the focal position (reproduced image divergence point) of the diffracted light (scanning beam) with respect to the diffracted light.

(4) Formula Calculation of Evaluation Surface An expression representing the evaluation surface is calculated from the evaluation surface distance and the diffraction direction.

(5) Setting of Incident Spot It is assumed that the reproduction light incident on the master hologram 1 is composed of a light beam group.

(6) Calculation of the diffraction direction of each point The diffraction direction is calculated for each ray.

(7) Calculation of intersection coordinates with evaluation plane The coordinates of the intersection with the evaluation plane are calculated for each ray. The beam shape on the evaluation plane is determined by obtaining the intersection coordinates for all the light groups.

(8) A focal length and a beam diameter at the time of reproduction are calculated from the determined beam shape.

The focal length and beam diameter during reproduction are determined based on the following equation (9).

D (z) = 2W₀ [1+ (Z-Z₀ )^Two / (K^Two W₀ ^Four)]^1/2 (9) where D (z) is the beam diameter at a distance of z from the lens,
k is wavelength constant = 2π / λ, λ is wavelength, W₀ Is Beamwe
Strike radius, ie, W₀ = R^Two / [1+ (k^Two r ^Four ) / 4
f^Two ], Z₀ Is the beam waist position, that is, Z₀ = F /
[1 + 4f^Two / (K^Two r^Four )], R is the incident beam radius,
f represents the focal length of the lens.

(9) Recording and reproduction conditions are set again based on the focal length and beam diameter during reproduction.
The same processing as described above is performed, and finally, an object light divergence point A and a reference light divergence point B are set such that a beam having a substantially circular shape and a minimum diameter is obtained on the evaluation surface.

As described above, the object light divergence point A
Then, the divergence point B of the reference light is set, and the imaging system shown in FIG. Note that, when the diffraction angle is set differently between the upper side and the lower side of the master hologram 1, for example, at 45 ° and 48 °, the relationship between the object light distance R _2a , the reference light distance R _2b, and the focal length R _1a during reproduction is set. Was as shown in FIG.

When the bar code was read using the master hologram 1 in which the astigmatism was corrected in this manner, the result shown in FIG. 14 could be obtained by simulation. When the aberration correction was not performed, the result is as shown in FIG. Although not shown, when the above-described aberration correction is performed,
It has been found that both the reading area and the reading depth are improved.

A copy hologram 13 obtained by copying the recorded image from the master hologram 1 photographed as described above is used in a bar code reader as shown in FIG.

In this bar code reader,
The laser beam from the reproducing laser oscillator 14 is reflected by the mirror 15, the reflected light is applied to the hologram disk 16, the diffracted light is reflected by the five-sided mirror 17, and the bar code label 12 is scanned. Barcode label 1
The reflected light 2 is condensed by the convex lens 18 via the five-sided mirror 17 and the hologram disc 16 and the light receiving element 1
Light 9 is input, and a bar code is recognized in an electronic circuit (not shown).

FIG. 17 conceptually shows an apparatus for carrying out the hologram manufacturing method according to the second embodiment.

In the second embodiment, the parallel light is used as the reference light when the recorded image is copied from the master hologram 1 to the copy hologram as in the first embodiment described above. This is a hologram manufacturing method suitable for a case where the ratio of the next light deviates from 1 relatively large.

This apparatus is similar to the first embodiment in that the copy hologram plate 2 is superimposed on the master hologram 1 and the recorded image of the master hologram 1 is copied on the copy hologram plate 2 to produce a hologram for reading a bar code. Device. Here, the master hologram 1
Similar to the embodiment, this is a master hologram captured by the object light and the reference light, both of which are divergent light.

This device includes an argon laser oscillator 3, one spatial filter 4, a fourth mirror 20, and a fifth mirror 21.

The spatial filter 4 diverges the laser beam from the laser oscillator.

The fourth mirror 20 is a flat mirror, and reflects a part of the divergent light from the spatial filter 4 to bend it.

The fifth mirror 21 is a flat mirror, and reflects the light reflected from the fourth mirror 20 and bends it.

The remainder of the divergent light from the spatial filter 4 directly irradiates one of the upper side and the lower side of the master hologram 1, and the reflected light of the fifth mirror irradiates the other side.

In photographing a copy hologram using the apparatus having the above configuration, the fourth and fifth mirrors 20 and
21 and the spatial filter 4 are respectively set at predetermined positions, and the spatial filter 4 is adjusted so that desired divergent light can be obtained. Then, as in the usual method, the laser beam is emitted from the argon laser oscillator 3 to perform photographing.

Also according to the hologram manufacturing method of the second embodiment, the work for removing the mirror as in the conventional case can be omitted, so that the work time can be shortened. Adjustment work is 1
Since the rotation is completed, labor required for complicated adjustment work can be reduced, and energy loss can be reduced because no partition is provided.

Further, according to the second embodiment, the deviation of the incident angle can be minimized by dividing the divergent light.

The hologram dry plate in the above embodiment is made of DCG (dichromate gelatin), photopolymer,
Any of Ag salt dry plates may be used.

The method for producing a DCG dry plate is 30 to 50 ° C.
5-30% of gelatin is added to water and stirred and dissolved for 1 to 4 hours, and then ammonium bichromate is added for 1 to 20 hours.
% Of the solution is applied to glass or resin by spin coating, and dried at 20 ° C. and 50% RH for 1 to 14 days to complete. Here, the film thickness is 5 to 10 μm. D
Since the CG dry plate has a high sensitivity in the ultraviolet region, an image is taken using a wavelength of 488 nm or 514 nm of an argon laser.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a copy hologram photographing system for implementing a first embodiment.

FIG. 2 is a first diagram for describing a problem when a copy hologram is photographed by reproducing a master hologram with divergent light.
Illustration of

FIG. 3 is also a second explanatory view

FIG. 4 is also a third explanatory view

FIG. 5 is a conceptual diagram of an imaging system of a master hologram in the first embodiment.

FIG. 6 is an explanatory diagram for explaining a problem when aberration correction is not performed;

FIG. 7 is an explanatory diagram for explaining an effect when aberration correction is performed.

FIG. 8 is a flowchart showing a procedure for setting a master hologram photographing condition.

FIG. 9 is a diagram showing an optical system set for explaining the above procedure.

FIG. 10 is an explanatory diagram for explaining a method of calculating a laser crossing angle.

FIG. 11 is an explanatory diagram for explaining a method of calculating a correction angle.

FIG. 12 is an explanatory diagram for explaining a method of calculating a correction angle.

FIG. 13 is a diagram showing a relationship between a reference light distance, an object light distance, and a reproduction focal length set by the master hologram photographing condition.

FIG. 14 is a diagram illustrating a beam diameter and an ellipticity when aberration is corrected.

FIG. 15 is a diagram illustrating a beam diameter and an ellipticity when aberration correction is not performed.

FIG. 16 is a conceptual diagram of a barcode reader.

FIG. 17 is a conceptual diagram of a copy hologram photographing system for implementing the second embodiment.

FIG. 18 is a conceptual diagram of a conventional copy hologram photographing system.

[Explanation of symbols]

 Reference Signs List 1 master hologram 2 copy hologram dry plate 3 argon laser oscillator 4 spatial filter 6 first mirror 7 second mirror 8 third mirror 20 fourth mirror 21 fifth mirror

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-74086 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03H 1/00-1/34 G02B 5 / 32

Claims (5)

(57) [Claims] 1. A superposition copy hologram dry plate to the master hologram, a hologram manufacturing method for manufacturing a hologram copy the recorded image of the master hologram to the copy hologram dry plate, a laser oscillator, from the laser oscillator Diverge the laser beam
And Luz page Shall filter, a lens for changing the divergent light from the spatial filter to the parallel light, a first mirror for reflecting the collimated light from the lens, one light reflected from said first mirror The second reflecting part
And mirrors, anti the second mirror of the reflected light from the first mirror
A third mirror that reflects at least a part of the light that is not emitted
And the master hologram is formed by reflected light of the second mirror.
And reflected light of the third mirror
A method for manufacturing a hologram, comprising irradiating the master hologram . 2. A superimposing a copy hologram dry plate to the master hologram, a hologram manufacturing method for manufacturing a hologram copy the recorded image of the master hologram to the copy hologram dry plate, a laser oscillator, from the laser oscillator Diverge the laser beam
Comprising a Luz page Shall filter, and a fourth mirror for reflecting a portion of light from said spatial filter, and a fifth mirror for reflecting the reflected light from the fourth mirror, the master hologram Is the spatial filter
Of the fifth mirror,
A method for producing a hologram, wherein the hologram is irradiated with reflected light . 3. The method according to claim 1 or 2 ,
2. The hologram manufacturing method according to claim 1, wherein the master hologram is photographed under a condition that a scanning beam at the time of reproduction has a substantially perfect beam shape. 4. At least according to claim 1 or claim 2.
2. The hologram according to claim 1, wherein the hologram is a bar code.
Hologram manufacturing method characterized by being a hologram for use
Law. 5. At least one of claim 1 and claim 2.
Item 1. In the item 1, the master holograms are both divergent lights.
Characterized by being photographed with a certain object light and reference light
Hologram manufacturing method.