JP3291178B2 - Hologram fabrication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hologram, and more particularly to a method for producing a screen hologram using a hologram as a screen.

[0002]

2. Description of the Related Art There is a screen hologram in which display contents outputted from a display are projected on a transparent screen made of a hologram, and the display contents can be confirmed while seeing through a background. By utilizing this, it becomes possible to serve customers while checking customers and patients at the counters of banks and hospitals. There are two types of display contents: one for the customer, one for the customer service side, and one for both. As a usage method other than the above, an advertisement or the like can be displayed in a showroom such as a department store or an underground shopping mall, or a head-up display of an automobile or the like can be used.

FIG. 26 shows a display device using a transmissive screen, in which a projector 42 is arranged on the back side of a screen hologram 41, and a display image is projected from the projector 42 so that an observer 43 can see the display image. Can be. FIG. 27 shows a display device using a reflection type screen, in which a projector 45 is arranged in front of a screen hologram 44, and a display image is projected from the projector 45 so that a viewer 46 can see the display image.

As one method for producing this screen hologram, a method of diffusing a laser beam through a diffuser such as frosted glass and recording the interference fringes formed by using the diffused beam as an object beam and a reference beam on a photosensitive dry plate. There is. More specifically, as shown in FIG. 28, exposure is performed with two light fluxes of object light and reference light, which are diffused light transmitted through the diffuser 47, and interference fringes are recorded on the photosensitive dry plate 48. At this time, there are a transmission type in which light enters the dry plate 48 in the same direction as shown in FIG. 28 and a reflective type in which light enters the dry plate 49 in the opposite direction as shown in FIG. This is used properly according to the use situation at the time of reproduction.

[0005]

However, since the interference fringes are recorded on the dry plate through a diffuser such as frosted glass, the screen hologram is turbid or cloudy as in the case of frosted glass. Therefore, the transparency is poor and the background cannot be visually recognized clearly. Also, when viewing the screen hologram from a position other than the viewing position of the display image, or when viewing the screen hologram from the observer's position when the display image is not being projected, it looks like a dull glass and looks very strange. is there.

That is, in the fabrication shown in FIGS. 28 and 29, the exposure is performed by setting E _R / E _O which is originally the ratio of the object light (O) to the reference light (R) to “1”. E here
_R / E _O is the light intensity ratio of object light and reference light on a hologram recording dry plate for recording interference fringes, that is, E _R / E _O =
(Reference light intensity) / (object light intensity). However, with such exposure, taking the reflection type shown in FIG. 29 as an example,
As shown in FIG. 30, the interference fringes originally required by the reference light R ₁ and the object lights O ₁ and O ₂ are recorded,
O _1, the interference fringes in O ₂ of the object beam between the cause of fogging from being recorded (Fresnel noise).

As a method of producing a screen hologram having excellent transparency, a method of producing a screen hologram by irradiating a photosensitive dry plate with light having directivity (object light) from various directions and performing multiple exposures, etc. However, there is a problem that it takes time and the number of parts of the exposure apparatus increases.

Accordingly, an object of the present invention is to provide a method for producing a hologram which can easily produce a hologram (for example, a screen hologram) with little cloudiness or haze.

[0009]

According to the first aspect of the present invention, the diffraction efficiency η at the interference fringes formed by the object light beams.
_OO and the ratio η _RO / η _OO of the diffraction efficiency η _RO at the interference fringe formed by the reference light and the object light is at least “10”,
The intensity E _{O of the} object light and the intensity E _{R of the} reference light are adjusted so that the diffraction efficiency η _OO does not exceed 5%. Therefore, interference fringes due to mutual interference between object light beams are less likely to be formed,
A hologram with little cloudiness or haze is obtained.

That is, η _RO / η _OO is at least “10”.
By doing so, the intensity of the light diffracted by the hologram is reduced, and it is possible to avoid, for example, a dark display image and poor visibility. The diffraction efficiency η _OO is 5
By not exceeding%, it is possible to avoid a situation in which the noise rate increases, cloudiness and fogging become remarkable, the transparency is deteriorated, and the background is difficult to recognize.

[0011] According to the second aspect of the present invention, the light diffuser is passed through.
Screen hologram using the focused object light
Diffraction efficiency η at interference fringes formed by body light_OOWhen,
Diffraction efficiency at interference fringes formed by reference light and object light
η_RORatio η_RO/ Η_OOIs at least "10" and
Folding efficiency η_OOSo that the intensity E of the object light does not exceed 5%. _O
And the intensity E of the reference light_RAnd adjust. Therefore, object light
Interference fringes due to the mutual interference of
A screen hologram with less haze can be obtained.

That is, η _RO / η _OO is at least “10”.
By doing so, the intensity of the light diffracted by the hologram is reduced, and it is possible to avoid, for example, a dark display image and poor visibility. The diffraction efficiency η _OO is 5
By not exceeding%, it is possible to avoid a situation in which the noise rate increases, cloudiness and fogging become remarkable, the transparency is deteriorated, and the background is difficult to recognize.

According to the third aspect of the invention, the intensity of the object light is set outside the sensitivity range of the photosensitive dry plate to be used. Therefore, unnecessary interference fringes between the object beams are not recorded on the photosensitive dry plate.

According to the fourth aspect of the present invention, the intensity of the object light is determined by the diffraction efficiency η of the interference fringes formed by the object lights.
_OO was set to a range not _exceeding 2%. Therefore, a hologram with little cloudiness or haze can be obtained (for example, in a screen hologram, the background can be clearly recognized without hindering the transparency).

[0015] That is, as shown in FIG. 9, by setting the light intensity of the interference fringes of the diffused light between the object light O ₂ to each other like the object beam O ₁ for example in FIG. 30 40 mJ / cm ² or less, the screen hologram The noise rate can be set to 2% or less.

As shown in FIG. 25, when the light transmitted through the diffuser 47 is in only three directions, the exposure amount of the interference fringes formed by the object lights O ₁ and O ₂ and O ₁ and O ₃ is , 20m each
J / cm ² . At this time, the object beam O ₁ and O _2, O ₁ and O ₃ 1: since it thinks 1, the diffraction efficiency of the hologram than 6 is considered to 5%.

Since the light transmitted through the actual diffuser 47 is multidirectional, the diffraction efficiency of the individual interference fringes formed by the object lights is 5% or less, and the dullness and white turbidity of the screen hologram are prevented. it can.

According to the present invention, the reference light is diverged.
Magnification n of the reference light lens to be_REmits object light to
Magnification n of the object light lens_ORatio n_O/ N_RTo
"4" or more. Therefore, the intensity E of the object light_OAgainst
Reference light intensity E_RRatio E_R/ E _OIs larger and the object light
Diffraction efficiency η at interference fringes due to mutual interference between_OOAnd reference
Diffraction efficiency η at interference fringes due to interference fringes between light and object light_ROWhen
Ratio η_RO/ Η_OOCan be "10" or more
You.

According to the sixth aspect of the present invention, the light diffuser and the photosensitive dry plate are arranged at a distance larger than a predetermined distance. Therefore, the ratio E of the intensity E _R of the reference light to the intensity E _O of the object light is obtained.
_R / E _O increases, and the ratio η _RO / η between the diffraction efficiency η _OO at the interference fringes due to the mutual interference between the object lights and the diffraction efficiency η _RO at the interference fringes due to the interference fringes between the reference light and the object light. _OO says "1
0 ”or more.

According to the seventh aspect of the present invention, the light intensity attenuating member is disposed in the middle of the path of the object light. Therefore, the ratio E _R / E _O of the intensity of the reference light to the intensity E _O of the object light E _R is increased, and the diffraction efficiency eta _OO of interference fringes due to the mutual interference between the object light, the reference light and object light The ratio η _RO / η _OO to the diffraction efficiency η _RO of the interference fringes due to the interference fringes can be set to “10” or more.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows the configuration of a display device incorporating a screen hologram. This display device uses a transmission screen. That is, the projector 1 is arranged on the back side of the screen hologram 3, the display image is projected from the projector 1, and the display image 5 can be viewed from the observer 4.

The projector 1 has a display 1a and a projection lens 1b. A screen hologram 3 is erected by a screen mount 2 at a position separated from the projector 1 by a predetermined distance. Also, projector 1
On the other hand, the observer 4 is located at a position separated from the screen mount 2.

The light emitted from the display 1a of the projector 1 forms an image on the screen hologram 3 by the projection lens 1b. At this time, the display 1a is inclined with respect to the optical axis L1, and the display image 5 of the display 1a is focused on the entire surface of the screen hologram 3. Display image 5
Is partially converted into diffracted light 6 by the screen hologram 3. The diffracted light 6 is scattered light, and the directivity of the diffracted light 6 is directed toward the eyes of the observer 4.

FIG. 1 shows an exposure optical system for producing the screen hologram 3. A mirror 8 is arranged facing the laser emission port with respect to the laser oscillator 7, and a semi-transmissive mirror 9 is arranged on an optical axis formed by the mirror 8. Further, a mirror 10 is arranged on an extension of the semi-transmissive mirror 9 on the optical axis formed by the mirror 8. An off-axis parabolic mirror 12 is arranged on an optical axis formed by the mirror 10 via an objective lens 11. The light is spread by the objective lens 11, but becomes parallel light by the off-axis parabolic mirror 12.

On the optical axis L2 formed by the off-axis parabolic mirror 12, a semi-transmissive mirror 14 is arranged via a diffusion plate (light diffuser) 13, and furthermore, the light formed by the semi-transmissive mirror 14 is formed. On the axis (reflection axis) L3, a photosensitive dry plate (hologram dry plate) 15 serving as a screen hologram is arranged.

Here, dichromated gelatin (DCG) is used as the photosensitive dry plate 15. Also, a single-sided ground glass of # 1000 is used as the diffusion plate 13. In addition, the diffusion plate 13 obtains a desired diffusion characteristic by using a lenticular lens or an opal glass in addition to frosted glass, or by bonding a material of “2” or “3” among those materials. You may.

A mirror 16 is arranged on the optical axis formed by the reflection of the semi-transmissive mirror 9, and a mirror 17 is arranged on the optical axis formed by the mirror 16.
On the optical axis formed by 7, a photosensitive dry plate 15 is arranged via an objective lens 18 and a semi-transmissive mirror 14. That is, the front side (the right side in FIG. 1) with respect to the semi-transmissive mirror 14
In FIG. 1, a photosensitive dry plate 15 is arranged, and an objective lens 18 is arranged on the back side (the left side in FIG. 1).
Further, the transflective mirror 14 and the photosensitive dry plate 15 are arranged close to each other, and the transflective mirror 14 and the objective lens 18 are arranged close to each other. Therefore, the distance S ₁ between the photosensitive dry plate 15 and the objective lens 18 is small and both are arranged close to each other.

The transflective mirror 14 is movable, and can change the direction of light from the diffusion plate 13 in the vertical and horizontal directions with respect to the photosensitive dry plate 15. In FIG. 1, the lower end of the semi-transmissive mirror 14 serves as a rotation axis 19, which can rotate around the rotation axis 19 to change the light from the diffusion plate 13 in the vertical direction with respect to the photosensitive dry plate 15. it can. That is, the semi-transmissive mirror 14
Is adjusted, and the angle θ at which the object light emitted from the diffusion plate 13 enters the photosensitive dry plate 15 can be freely adjusted. Therefore, when the semi-transmissive mirror 14 is tilted by 5 ° (Δθ1 = 5
°), the incident angle θ on the photosensitive dry plate 15 is inclined by 10 °.

The description of the mechanism for changing the direction of light in the left-right direction is omitted. In the present embodiment, the intensity of the object light is set outside the sensitivity range of the photosensitive dry plate 15, the intensity of the object light is set to 40 mJ / cm ² or less, and a reference light lens for diverging the reference light is used. Magnification n _{R of} 18
The ratio n _O / n _R of the magnification n _O of the object light lens 11 for diverging the object light with respect to is set to “4” or more. In this manner, the ratio E _R / E _O of the reference light intensity E _R to the intensity E _O of the object light, the diffraction efficiency eta _OO of interference fringes due to the mutual interference between the object light and the reference light and object light The ratio η _RO / η _OO to the diffraction efficiency η _RO at the interference fringes due to the interference fringes is at least “10”, and the diffraction efficiency η _OO does not exceed 5%. More specifically, the diffraction efficiency η
_OO is set within the range not _exceeding 2%.

Next, the procedure for producing the screen hologram 3 will be described. First, the transflective mirror 14 is fixed at an angle indicated by a solid line in FIG. Then, laser light is emitted from the laser oscillator 7. The laser light emitted from the laser oscillator 7 is divided into two directions by the semi-transmissive mirror 9. After changing the direction of one laser beam with the mirror 10,
The light is converted into divergent light by the objective lens 11. Next, the light is made parallel by the off-axis parabolic mirror 12 and is incident on the diffusion plate 13 to become diffused light. After being reflected by the semi-transmissive mirror 14, it is incident on the photosensitive dry plate 15 as object light. On the other hand, the laser light reflected by the semi-transmissive mirror 9 passes through the mirror 16 and the mirror 17,
The light is converted into divergent light by the objective lens 18. Next, after passing through the semi-transmissive mirror 14, it is incident on the photosensitive dry plate 15 as reference light. Interference fringes caused by the object light passing through the diffusion plate 13 and the reference light are recorded on the photosensitive dry plate 15.

Thereafter, the semi-transmissive mirror 14 is tilted by 5 ° (Δθ1 = 5 °) as shown by the broken line in FIG. 1 to tilt the incident angle θ to the photosensitive dry plate 15 by 10 °. In this state, laser light is emitted from the laser oscillator 7. Then, interference fringes due to the object light passing through the diffusion plate 13 and the reference light are recorded on the photosensitive dry plate 15. Accordingly, when the semi-transmissive mirror 14 is combined with the interference fringes recorded without tilting, the viewing area in the vertical direction is widened.

Similarly, the laser beam is emitted from the laser oscillator 7 by changing the direction (angle) of the transflective mirror 14 to the left and right, and the interference fringe caused by the object light passing through the diffusion plate 13 and the reference light is exposed to the photosensitive dry plate. Record at 15. This widens the viewing area in the left-right direction.

As described above, the photosensitive dry plate 15 is made of heavy chromium.
Using acid gelatin (DCG) and diffusion plate 13
Using # 1000 single-sided frosted glass
The object light intensity E_OReference light intensity E for_RRatio E
_R/ E_OFig. 3 shows the measurement results of the noise ratio when
You. The noise rate referred to here will be described. As shown in FIG.
As shown, the screen hologram 99
Color light 100 (incident light intensity I ₀). Then the projection
Of the light 102 transmitted and scattered by the screen hologram
The vertically transmitted light 101 transmitted in the vertical direction of the incident light
Transmitted light intensity I₁Is measured. At this time, the incident light intensity I₀
And vertical transmitted light intensity I₁And the result shown in FIG.
Becomes At this time, the portion 110 in FIG.
111 indicates the noise ratio and screen
It is the sum of the program absorptions. In the case of DCG, the absorption is almost
Since it can be considered almost 0, the hatched part is
Defined. When this noise rate increases, screen holog
The rum becomes cloudy and dull, and the background is dull.
I can't. The noise rate of the interference fringes formed by the object beams
The method of measurement is the exposure of the screen hologram
In the optical system, only the same amount of object light is
Light, then irradiate only the reference light for the dura and develop
Measure the noise ratio.

From FIG. 3, it can be seen that, by setting E _R / E _O = “5” or more, a noise factor (white turbidity, dullness) can be reduced to 2% or less, and a transparent, cloudless transmission screen hologram can be obtained. I understand.

As a method of setting E _R / E _O to “5” or more, more specifically, in the optical system shown in FIG. 1, the magnification n _O of the object light lens 11 is increased, and the reference light lens is increased. The magnification n _R of 18 is reduced. The ratio (n _O / n _R ) between the magnification n _O of the object light lens 11 and the magnification n _R of the reference light lens 18 is represented by the magnification n of the object light lens 11.
_O: magnification of the magnification n _R of the reference light lens 18 = 4: 1
It is desirable to set it to about 8: 1, and a ratio higher than that may be used.

In other words, by increasing the lens magnification, the laser light can be further expanded, so that the intensity of light incident on the dry plate can be reduced. Where E _R / E _O
Is set to “5” or more, the sense of transparency increases and the noise rate decreases.

To record interference fringes, two interference
Is required to some extent. As shown in FIG.
Now, object light O₁And object light O_TwoThe two lights of the photosensitive dry plate 20
It is assumed that interference fringes are formed above. Of the photosensitive dry plate 20
FIG. 5 is a graph showing an exposure amount necessary for recording interference fringes.
Show. Object light O₁And object light O_TwoWhen the sum of the light intensity of
(A region in FIG. 5) is the object light O₁And object light O_TwoInterference
Stripes can be recorded. However, the object light O₁And object light O_TwoLight of
When the sum of the intensities is small (region B in FIG. 5), the interference fringes are recorded.
Recording is impossible. Therefore, DCG is used as the photosensitive dry plate 20.
When using a dry plate, the minimum required for recording interference fringes
Exposure value P_minI asked. That is, the object light O₁And object light
O_TwoFIG. 6 shows the results obtained when the intensity ratio was 1: 1. Figure
6, when a DCG plate is used as the photosensitive plate 20,
And P_minIs 10 mJ / cm ^TwoIt became.

In consideration of the above, a transparent screen holograph
Consider the case of producing a system. For reflective screens
For example, FIG. 30 shows an example of the exposure optical system.
You. Now, from one point S of the diffuser 47 to the photosensitive dry plate 49
The object light that reaches one point U₁And likewise one point T
The object light coming to point U from_TwoAnd Also, it enters the point U
Set the reference light to R₁And At this time, at a point U on the photosensitive dry plate 49,
As shown in FIG. 7, the interference fringes formed are O₁When
O_Two, O₁And R₁, O_TwoAnd R₁There are three. This time, Toru
It is necessary to make a clear screen hologram
The interference fringe is O ₁And R₁, O_TwoAnd R₁With two interference fringes
is there. Also, the transparency of the screen hologram is reduced,
The cause of the high noise rate is O₁And O_TwoInterference fringes
Which is called Fresnel noise. Yo
And O₁And R₁Or O_TwoAnd R₁Only interference fringes
And O₁And O_TwoIf no interference fringes are recorded, cloudiness
Clear and transparent screens can be made.

Here, the ratio between the light intensities of O ₁ and O ₂ is generally considered to be 1: 1. D as photosensitive dry plate 20
When a CG dry plate is used, O ₁ and O
_If the sum of the light intensities of ₂ is 10 mJ / cm ² or less, O ₁ and O
_No interference fringe (Fresnel noise) is recorded. Now, O
Assuming that the ratio of the light intensities of ₁ and R ₁ or O ₂ and R ₁ is 1: 1 (that is, E _R / E _O = 1), the sum of the light intensities of O ₁ and R ₁ or O ₂ and R ₁ is obtained. If is set to 10 mJ / cm ² or more, the originally required interference fringes can be recorded, but at the same time, Fresnel noise is also recorded and cannot be made transparent.

[0041] That is, the interference fringes formed by the object light O _1, O ₂ utilizes e.g. dichromated gelatin (DCG) hologram dry plate, as shown in FIG. 6, the light amount of the object light (O _1, O ₂ 10 mJ / c)
not recorded as long as m ² or less. On the other hand, the interference fringes originally required for the screen hologram (the interference fringes between the originally desired object light O ₁ or O ₂ and the reference light R ₁ ) have an exposure amount of 10 mJ.
/ Cm ² or more can be recorded. At this time, the light intensities of the object lights O ₁ and O ₂ are considered to be approximately 1: 1. Therefore, by increasing the ratio E _R / E _O of the object light O and reference light R, the interference fringes of O ₁ (or O ₂₎ and R ₁ is recorded, cloudy, O ₁ is responsible for the cloudy A transparent screen hologram can be produced without recording interference fringes of O ₂ and O ₂ (Fresnel noise of a diffuser).

Then, the ratio E _R / E _O of the light intensity of O ₁ and R ₁ or O ₂ and R ₁ is, for example, 1:20 (E _R / E _O =
20). Here, FIG. 8 is a graph showing an exposure amount at which interference fringes can be recorded when a DCG dry plate is used as the photosensitive dry plate 20 when the intensity ratio of the two lights is 1:20. From FIG. 8, if the sum of the light intensities of R ₁ and O ₁ (or R ₁ and O ₂ ) in FIG. 30 is 25 mJ / cm ² or more, it is possible to record interference fringes.

Therefore, in FIG. 30, O ₁ = O ₂ = 3 m
J / cm ² , R ₁ = 60 mJ / cm ² (O ₁ : R ₁ = 1: 2
If 0), a transparent screen hologram that satisfies both of the above conditions and has no Fresnel noise can be manufactured.

As described above, by setting E _R / E _O to “5” or more, as shown in FIG. 24, the diffraction efficiency η _OO at the interference fringe due to the mutual interference between the object beams, the reference beam and the object beam, Ratio η _RO / η _{OO to} diffraction efficiency η _RO at interference fringes due to interference with
Is "10" or more, and a transparent screen hologram having a small noise rate can be obtained.

The same effect can be obtained in a transmission screen hologram. As described above, FIG.
As shown in, the noise ratio of the screen hologram than increasing the E _R / E _O (cloudy, dullness) can be reduced, also to the noise ratio 2% or less, "5 E _R / E _O Is desirable.

Further, as shown in FIG. 9, a certain degree of dullness and white turbidity are allowed in the screen hologram when the emission intensity of the interference fringes between the diffused light of the object light O ₁ and the object light O ₂ is 40 mJ / cm ² or less. 40m
It has been confirmed that the noise ratio of the screen hologram can be reduced to 2% or less by setting it to J / cm ² or less.

In FIG. 1, the sectional area of the light beam passing through the diffusion plate 13 is larger than the area of the photosensitive dry plate 15. That is, as shown in the schematic diagram of FIG.
1 is a size larger than the photosensitive dry plate 15. In FIG. 10, the object light incident on the diffusion plate 21 is emitted as scattered light, and the scattered light 22a, 22b, 22c is recorded so as to diverge from one point of the photosensitive dry plate 15. Here, assuming that the diffusion plate 23 and the photosensitive dry plate 15 have the same size as shown in FIG. 11, since light in the direction corresponding to the scattered light 22a is not recorded, the screen produced by the optical system of FIG. When the hologram is observed as shown in FIG. 2, the peripheral portion of the screen hologram 3 is dark and looks colored due to chromatic dispersion. In contrast, FIG.
If the hologram is manufactured by the method of No. 0, the coloring is lost and the brightness of the peripheral portion can be secured.

As described above, according to the present embodiment, the diffraction efficiency η _OO at the interference fringe formed by the object lights and the diffraction efficiency η _RO at the interference fringe formed by the reference light and the object light.
The intensity E _{O of the} object light and the intensity E _{R of the} reference light were adjusted such that the ratio η _RO / η _OO of the object light was at least “10” and the diffraction efficiency η _OO did not exceed 5%. Therefore, interference fringes due to mutual interference between the object beams are less likely to be formed, and a screen hologram with less cloudiness and haze can be obtained. That is, η
_By setting _RO / _ηOO to be at least “10”, the intensity of light diffracted by the hologram is reduced, and for example, it is possible to avoid a dark display image and poor visibility. By preventing the diffraction efficiency η _{OO from exceeding} 5%, it is possible to avoid that the noise rate increases, cloudiness and cloudiness become remarkable, the transparency is deteriorated, and the background becomes difficult to recognize. . In this way, interference fringes due to mutual interference between object light beams are less likely to be formed, and in a hologram used as a screen, when a diffuser such as ground glass is recorded on the hologram, an originally necessary interference fringe is recorded, Interference fringes that cause clouding and the like can be prevented from being recorded, and a transparent screen hologram with a low noise rate can be manufactured.

Further, the intensity of the object light is determined by using the photosensitive dry plate 1 to be used.
5 out of the sensitivity range, unnecessary interference fringes between object beams
Is not recorded on the photosensitive plate. In addition, the object light
Diffraction effect by interference fringes formed by object beams
Rate η _OOWas set to a range not exceeding 2%. Therefore, cloudiness
A hologram with less fogging and screen hologram
The background can be clearly recognized and recognized in the ram without disturbing the transparency.
You.

That is, as shown in FIG. 9, by setting the light intensity of the interference fringes between the diffused lights such as the object light O ₁ and the object light O ₂ in FIG. 30 to be 40 mJ / cm ² or less, a screen hologram can be obtained. The noise rate can be set to 2% or less.

As shown in FIG. 25, when the light transmitted through the diffuser 47 is in only three directions, the exposure amount of the interference fringes formed by the object lights O ₁ and O ₂ and O ₁ and O ₃ is , 20m each
J / cm ² . At this time, the object beam O ₁ and O _2, O ₁ and O ₃ 1: since it thinks 1, the diffraction efficiency of the hologram than 6 is considered to 5%.

Since the light transmitted through the actual diffuser 47 is multi-directional, the diffraction efficiency of each interference fringe formed by the object light is 5% or less, and the dullness and white turbidity of the screen hologram are prevented. it can.

Further, the ratio n _O / n _R of the magnification n _O of the object light lens 11 for diverging the object light to the magnification n _R of the reference light lens 18 for diverging the reference light is set to “4” or more. Therefore, the intensity E of the reference light with respect to the intensity E _O of the object light
The ratio E _R / E _O of _R, it is possible to "5" or more.

Further, since the photosensitive dry plate 15 and the objective lens 18 are disposed close to each other by using the semi-transmissive mirror 14, uneven brightness of various display images projected by the projector can be reduced over the entire screen. Observers can observe a wide area. Further, the transmission screen hologram can perform full-color reproduction on the entire surface.

Here, the usefulness of reflecting the object light by the semi-transmissive mirror 14 will be described. In FIG. 12, when the observer 25 views the real image formed on the screen hologram 24, the screen hologram 24 may have the function of a field lens in order to minimize the unevenness of the brightness of the entire screen. That is, the projector projection lens 2
It is sufficient that the screen hologram 24 has a lens function so that the position 6 and the position of the observer 25 have a conjugate relationship. However, the focal length of the field lens becomes shorter than the distance S ₂ between the projector projection lens 26 and the screen hologram 24 in FIG. 12 from the imaging relationship of the lens. To create a short focus transmission hologram, see FIG.
Since the objective lens 27 enters the luminous flux of the object light as shown in FIG.

However, in the present embodiment, the semi-transmissive mirror 14 is disposed in the optical path of the object light to transmit the object light to the semi-transmissive mirror 1.
4 irradiates the photosensitive dry plate 15 and irradiates the photosensitive dry plate 15 with the reference light through the semi-transmissive mirror 14 to reduce the distance S ₁ between the objective lens 18 and the photosensitive dry plate 15 to shorten the short focus. Can be produced. In addition, even if the semi-transmissive mirror 14 is arranged in the optical path, the contrast of the interference fringes formed by the reflection of the front and back surfaces of the semi-transmissive mirror 14 is low, and there is no problem. (Second Embodiment) Next, a second embodiment of the present invention will be described, focusing on differences from the first embodiment.

[0057] In this embodiment, as shown in FIG. 14, the E _R / E _O in order to "5" or more, the distance between the photosensitive dry plate (hologram dry plate) 28 and the diffuser 29 (FIG. 14
The distance S ₃ ) shown in FIG. Specifically, the diffuser 29 and the photosensitive dry plate 28 are spaced apart by 5 mm or more. Assuming that the intensity of the object light incident on the diffuser 29 is constant, E _R / E _O can be changed from 2 to 8 by changing the distance S ₃ from “5” to 400 mm, and 40
By separating them by 0 mm or more, E _R / E _O can be made 8 or more.

As described above, according to the present embodiment, since the diffuser 29 and the photosensitive dry plate 28 are arranged at a distance larger than the predetermined distance (5 mm), the intensity E _{R of the} reference light with respect to the intensity E _O of the object light. the ratio E _R / E _O of the can be a "5" or more. (Third Embodiment) Next, a third embodiment of the present invention will be described, focusing on differences from the first embodiment.

In this embodiment, as shown in FIG. 15, a laser intensity attenuator 30 such as a half mirror or a filter is disposed on the object light side in order to set E _R / E _O to “5” or more. . This reduces the intensity of the object light,
E _R / E _{O is set} to “5” or more.

As described above, according to the present embodiment, since the laser intensity attenuator 30 (light intensity attenuating member) is disposed in the middle of the path of the object light, the intensity E _R of the reference light with respect to the intensity E _O of the object light is obtained. The ratio E _R / E _O can be set to “5” or more. (Fourth Embodiment) Next, a fourth embodiment of the present invention will be described, focusing on differences from the first embodiment.

In this embodiment, as shown in FIG. 16, the first, second and third embodiments are combined in order to make E _R / E _{O equal} to or more than “5”. That is,
(A) The ratio n _O / n _R of the magnification n _O of the object light lens 11 to the magnification n _R of the reference light lens 18 is set to “4” or more, and (b) the photosensitive dry plate (hologram dry plate) 28 and the diffuser 2
To increase the distance S ₃ between 9, are disposed (c) laser intensity attenuator 30. This is effective when it is difficult to achieve the above due to conditions such as laser power and optical path length. In addition, the combination of (a), (b), and (c) gives E
_R / E _O ≧ 5 and E _R / E _O is “5”
The setting is more stepwise and variable in the above area. (Fifth Embodiment) Next, a fifth embodiment of the present invention will be described, focusing on differences from the first embodiment.

In the present embodiment, in order to stabilize the hologram characteristics, the DCG dry plate as the photosensitive dry plate 15 is made thinner. More specifically, a thickness of 10 mm
By setting the degree, a hologram having stable characteristics can be manufactured.

In addition to those described above, the present invention may be implemented as follows. At the time of hologram recording (exposure), the incident angles of the object light and the reference light are calculated in consideration of the incident angles and the intensities of the light transmitted through the diffuser at various angles, and E _R / E is calculated over the entire surface of the hologram dry plate. _By setting _O to “5” or more, transparency over the entire surface of the produced hologram may be ensured.

As the photosensitive dry plate (hologram dry plate) 15, a photosensitive material such as dye-sensitized dichromated gelatin or photopolymer may be used. In the description so far,
The case of the transmissive screen has been described, but as shown in FIG. 27, a display image is projected from the projector 45 from the front of the screen hologram 44, and reflection is observed from the observer 46 in the same direction as the display. The present invention may be embodied when manufacturing a mold screen.

Further, the present invention may be implemented as shown in FIG.
That is, the two transflective mirrors 31 and 32 are arranged with different inclinations, and the object light converted into the diffused light by the diffusion plate 13 is reflected by the two transflective mirrors 31 and 32 having different inclinations, respectively. And enters the photosensitive dry plate 15. Then, the photosensitive dry plate 1 interferes with the reference light which has been diverged by the objective lens 18.
5, an interference fringe is formed.

Further, the present invention may be implemented as shown in FIG.
That is, a wedge-shaped wedge prism 33 is used instead of the two transflective mirrors 31 and 32 in FIG. Since the reflection directions on the front surface and the rear surface of the wedge prism 33 are different, the same effect as the arrangement of the two semi-transmissive mirrors 31 and 32 at different angles as shown in FIG. 17 is obtained.

Further, the present invention may be implemented as shown in FIG.
Holograms 34 and 35 having directivities in different directions are separately manufactured and superimposed. By doing so, the viewing area is widened as a whole, and the display luminance is also increased.

Further, the present invention may be implemented as shown in FIG.
Reflecting mirrors 37a to 37a are provided on each side of the diffusion plate 36 having a square plate shape.
37d are arranged. These reflecting mirrors 37a to 37d have the same effect as increasing the area of the diffusion plate 36. The principle is shown in FIG. It is assumed that the incident light 38 enters the diffusion plate 36 and diffuses at the diffusion point P1. It is assumed that, of the diffused light, light that hits the reflecting mirror 37a is reflected at the reflection point P2. This reflected light is reflected at the virtual diffusion point P
Since it is equivalent to diffusion from 2 ′, the diffusion plate 3
Even if the area of 6 is small, the same effect as the diffusion plate having a large area can be obtained.

The semi-transmissive mirror 14 does not need to be subjected to any particular treatment such as surface treatment, but may be subjected to a process of increasing the reflection of the dielectric multilayer film on the surface. By performing this process, the intensity of the reflected light is increased, thereby increasing the light utilization rate (normal glass alone has a high transmittance and a large amount of wasted light). Of the interference fringes due to the vibration of.

Further, as a material for producing a hologram,
Not only DCG but also a photopolymer or a silver salt photosensitive material may be used. Further, the present invention may be embodied not only in a screen hologram but also in other general holograms. That is, the present invention may be used for a hologram for photographing an object such as a display or a hologram used as an optical element, and is effective in a case where an object has irregularities and stripes (noise) may be generated in the object light due to mutual interference. Method.

[Brief description of the drawings]

FIG. 1 is a diagram showing an optical system for producing a screen hologram according to a first embodiment.

FIG. 2 is a configuration diagram of a display device incorporating a screen hologram.

FIG. 3 is a diagram showing a relationship between E _R / E _O and a noise rate.

FIG. 4 is a view showing object light passing through a photosensitive dry plate.

FIG. 5 is a diagram showing a relationship between an exposure amount and a recording ratio of interference fringes.

FIG. 6 is a diagram showing a relationship between an exposure amount and diffraction efficiency.

FIG. 7 is a cross-sectional configuration diagram of a screen hologram for explaining originally required interference fringes and Fresnel noise.

FIG. 8 is a diagram showing a relationship between an exposure amount and diffraction efficiency.

FIG. 9 is a diagram showing a relationship between an object light exposure amount and a noise rate.

FIG. 10 is a diagram showing an optical system for producing a screen hologram.

FIG. 11 is a diagram showing an optical system for producing a screen hologram for comparison.

FIG. 12 is a diagram showing an optical system.

FIG. 13 is a diagram showing an optical system.

FIG. 14 is a diagram illustrating an optical system according to a second embodiment.

FIG. 15 illustrates an optical system according to a third embodiment.

FIG. 16 is a diagram illustrating an optical system according to a fourth embodiment.

FIG. 17 is a diagram showing an optical system for producing a screen hologram.

FIG. 18 is a diagram showing an optical system for producing a screen hologram.

FIG. 19 is a sectional view of a screen hologram.

FIG. 20 is a perspective view illustrating an optical system for producing a screen hologram.

FIG. 21 is a diagram illustrating the principle.

FIG. 22 is a diagram illustrating a method for measuring a noise rate.

FIG. 23 is a view for explaining the definition of a noise rate.

FIG. 24 is a diagram showing diffraction efficiency due to interference fringes between object light beams and diffraction efficiency due to interference fringes between object light and reference light.

FIG. 25 is a view showing object light passing through a photosensitive dry plate.

FIG. 26 is a diagram showing a transmission screen.

FIG. 27 is a view showing a reflection type screen.

FIG. 28 is a view showing an exposure optical system for producing a transmission screen hologram.

FIG. 29 is a view showing an exposure optical system for producing a reflection type screen hologram.

FIG. 30 shows an optical system for producing a screen hologram.

[Explanation of symbols]

11: Objective lens (lens for object light), 13: Diffusion plate (light diffuser), 15: Photosensitive dry plate, 18: Objective lens (lens for reference light), 30: Laser intensity attenuator (light intensity attenuating member)

──────────────────────────────────────────────────続 き Continued on the front page (72) Katsumi Kamiya 1-1-1, Showa-cho, Kariya-shi, Aichi, Japan Denso Co., Ltd. (72) Inventor Atsuro Ishizuka 14, Iwatani, Shimowasumi-cho, Nishio-shi, Aichi Japan Co., Ltd. (72) Inventor Tomoyuki Kanda 1-1-1 Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) G03B 21/56 G03H 1/04

Claims (7)

(57) [Claims] 1. A method for producing a hologram in which an interference fringe formed by an object light having a diffusive / scattering property and a reference light is recorded on a photosensitive dry plate, wherein diffraction by an interference fringe formed by the object lights is performed. Efficiency η
_OO and the ratio eta _RO / eta _OO of the diffraction efficiency eta _RO of the interference fringes formed by said object light and said reference light at least '1
A method for producing a hologram, wherein the intensity E _{O of the} object light and the intensity E _{R of the} reference light are adjusted to be “0” and the diffraction efficiency η _OO does not exceed 5%. 2. A method for producing a screen hologram in which interference fringes formed by object light and reference light passing through a light diffuser are recorded on a photosensitive dry plate, the method comprising: Diffraction efficiency η
_OO and the ratio eta _RO / eta _OO of the diffraction efficiency eta _RO of the interference fringes formed by said object light and said reference light at least '1
A method for producing a hologram, wherein the intensity E _{O of the} object light and the intensity E _{R of the} reference light are adjusted to be “0” and the diffraction efficiency η _OO does not exceed 5%. 3. The method for producing a hologram according to claim 1, wherein the intensity of the object light is outside the sensitivity range of the photosensitive dry plate to be used. 4. The apparatus according to claim 1, wherein the intensity of the object light is set so that a diffraction efficiency η _OO of an interference fringe formed by the object lights does not exceed 2%. Hologram manufacturing method. 5. The ratio n _O / n _R of the magnification n _O of the object light lens for diverging the object light to the magnification n _R of the reference light lens for diverging the reference light is set to “4” or more. The method for producing a hologram according to claim 1. 6. The method for producing a hologram according to claim 2, wherein the light diffuser and the photosensitive dry plate are spaced apart from each other by more than a predetermined distance. 7. The method for producing a hologram according to claim 1, wherein a light intensity attenuating member is arranged in the course of the object light.