JPH0916059A - Production of hologram - Google Patents

Abstract

PURPOSE: To provide a process for producing a hologram capable of suppressing a ghost hologram by the surface reflected light forming at the boundary with the outdoor air. CONSTITUTION: Both sides of a photosensitive plate 81 are held by a first prism 25 having a vertax angle ψ and a second prism 26 having a vertex angle ψand the photosensitive plate 81 is irradiated with reference light 31 from the side of the first prism 25 and object light 32 from the side of the second prism 26. The reference light 31 and the object light 32 are P polarized light. The relation between the vertex angle ψ and an incident angle θof the reference light 31 is so determined that the angle (a) formed by the normal reference light 311 which is made incident on the first prism 25 and heads toward the photosensitive plate 81 and the surface reflected light 312 is made perpendicular. An antireflection film 14 (or λ/4 wavelength plate) is formed on the front surface on the atmospheric side of the first prism 25.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is formed by noise light. The present invention relates to a hologram manufacturing method for suppressing a ghost hologram.

[0002]

2. Description of the Related Art When a hologram forming dry plate is irradiated with object light and reference light to form a hologram, the object light or reference light may enter from outside the regular optical path to form a ghost hologram. A major factor that causes such a ghost hologram is surface reflected light of object light or reference light at the interface with the outside air having different refractive indexes.

For example, as shown in FIG.
1 is brought into contact with the master hologram 93 via the refractive index adjusting liquid 92, the reference light 31 is incident from the surface of the dry plate 91, and the transmitted light 311 is diffracted and reflected by the master hologram 93, and this is used as the object light 32 as the dry plate. There is a method of forming an interference fringe at 91 (one-beam method using a master hologram).

In this case, for example, the transmitted light 311 is transmitted through the master hologram 93 and re-reflected at the interface 931 with the outside air, and this surface reflected light (not shown) is shown between the reference light 31 and the reflected light 31 in FIG. Such a ring-shaped interference fringe 99 is formed, and this becomes a ghost hologram. Alternatively, the object light 32 transmitted through the dry plate 91 is reflected again at the interface 911 with the outside air,
This surface-reflected light (not shown) forms an interference fringe with the regular object light 32. The same applies to the case where a reflective optical element is used instead of the master hologram 93 in FIG.

Also, in the two-beam method in which the object light and the reference light are incident from both the upper and lower sides of the dry plate, the surface reflected light at the interface similarly forms a ghost hologram. Then, if a hologram having such a ghost is used as a master hologram and the hologram is duplicated, a similar ghost hologram is formed in the duplicated hologram.

Several proposals have been made in order to suppress the generation of such a ghost due to surface reflected light. For example, as shown in FIG. 11, a first non-reflective coating glass 95 is arranged at the interface with the atmosphere to suppress surface reflected light.
Has been proposed (see Japanese Patent Laid-Open No. 4-198981).

That is, the refractive index adjusting liquid 92 is provided on both sides of the dry plate 91.
Antireflection treated glass 9 having an antireflection film 95 applied through
4 is arranged, and the surface reflected light 3 of the object light 32 and the reference light 31
22 and 312 are suppressed. Further, as shown in FIGS. 10 and 12, the reference light 31 or the surface reflected light 31 of the object light 32 is used.
In order to prevent 2,322 from re-incident on the dry plate 91,
A second method has been proposed in which prisms 961 and 962 for changing the optical path are arranged (see Japanese Patent Laid-Open No. 4-198980).

[0008]

However, the first and second methods for suppressing the surface reflected light have the following problems. In the first method (FIG. 11) of providing antireflection coated glass, the incident angle θ with respect to antireflection coated glass is
When becomes larger, there is a problem that the reflectivity increases and a sufficient effect cannot be obtained.

Further, in the second method (FIGS. 10 and 12) in which the surface reflected lights 312 and 322 are prevented from re-incident on the dry plate 91 by using the prisms 961 and 962, the prism 9 is used.
Since the vertex angles α and β of 6 are considerably large, there is a problem that the hologram manufacturing space becomes large. In view of such conventional problems, the present invention can suppress the generation of a ghost hologram due to the surface reflected light at the interface,
In addition, it is an object of the present invention to provide a hologram manufacturing method that does not significantly increase the manufacturing space.

[0010]

According to a first aspect of the present invention, both sides of a photosensitive plate are sandwiched between a first prism having an apex angle of ψ1 and a second prism having an apex angle of ψ2, and a reference light is supplied from a side of the first prism to a second prism. A method of manufacturing a hologram in which object light is irradiated from the prism side to the photosensitive plate to form interference fringes on the photosensitive plate, wherein the reference light is P-polarized light (the direction of the electric field is parallel to the incident surface). It is polarized light, and the angle a formed by the normal reference light that is incident on the first prism toward the photosensitive plate and the surface reflected light reflected by the reference light on the surface of the second prism on the atmosphere side is at a right angle. The above apex angles ψ 1, ψ
2 and the incident angle θ of the reference light are defined, the object light is also P-polarized linearly polarized light, and
In the hologram manufacturing method, the atmosphere-side surface of the first prism is antireflection-treated.

What is most noticeable in the first invention is that
The reference light and the object light are both P-polarized linearly polarized light, a regular reference light that enters the first prism and travels toward the photosensitive plate, and this reference light is reflected on the surface of the second prism on the atmosphere side. The angle a formed by the surface-reflected light has a value close to a right angle, and the surface of the first prism on the atmosphere side is subjected to antireflection treatment.

On the other hand, according to the second invention of the present application, both sides of the photosensitive plate are sandwiched by a first prism having an apex angle ψ1 and a second prism having an apex angle ψ2, and the reference light is supplied from the side of the first prism to the second prism. Is a method for manufacturing a hologram in which object light is radiated from the side of the photosensitive plate to form interference fringes on the photosensitive plate, and the reference light is P-polarized linearly polarized light and is incident on the first prism. Then, the apex angle ψ1 is set so that the angle a formed between the normal reference light traveling toward the photosensitive plate and the surface reflected light reflected by the reference light on the surface of the second prism on the atmosphere side is close to a right angle. , Ψ2 and the incident angle θ of the reference light are defined, the object light is also P-polarized linearly polarized light, and the surface of the first prism on the atmosphere side has λ / 4. A wave plate is placed, and the reference light passes through this λ / 4 wave plate and is polarized circularly. In the manufacturing method of the hologram which is a light converted into P-polarized light from.

The manufacturing method according to the second invention is the manufacturing method of the first invention, in which a λ / 4 wavelength plate is provided in place of the antireflection treatment, and the reference light is a circularly polarized light passing through the λ / 4 wavelength plate. It is to convert it into polarized light. The angle a in the first invention and the second invention is determined by the magnitude of the noise level to be suppressed. The closer the angle a is to the right angle, the greater the effect of suppressing the ghost due to the interface reflection of the reference light. .

In the first and second inventions, the two prisms are arranged such that the apex angle positions are on the same side of the photosensitive plate, and both apex angles ψ ₁ and ψ ₂ are equal. It is preferable (see FIGS. 7 and 1). The reason is as follows.

If the angle formed by the light (refraction light) 311 entering the first prism 25 shown in FIG. 7 and the normal is θ ₁ ,
The angle θ ₂ formed by the incident light 311 and the normal line of the dry plate 81 is shifted by the apex angle ψ ₁ (θ ₂ = θ ₁ + ψ ₁ ), and the incident light 311 forms the normal line at the interface 261 of the second prism 26. The angle θ ₃ increases by the sum of the apex angles (ψ ₁ + ψ ₂ ) (θ ₃ = θ ₁ + ψ ₁ + ψ ₂ ). That is, the above θ ₂ is the apex angle ψ
It is shifted by ₁ and the above θ ₃ is the sum of vertex angles (ψ ₁ + ψ ₂ )
Only shifted.

The same applies to the light 321 incident on the second prism at the angle θ ₁ ′ from the opposite direction (the apex angles ψ ₁ and ψ ₂ are exchanged, and θ ₂ ′ = θ ₁ ′ + ψ ₂ , θ
₃ ′ = θ ₁ ′ + ψ ₁ + ψ ₂ ). Now, as mentioned above,
It is preferable that ψ ₁ = ψ ₂ because both prisms can be arranged in a well-balanced manner on both sides of the dry plate without protruding in only one direction above or below the dry plate.

If the hologram produced by the methods of the first and second inventions is used as a master hologram to duplicate the hologram, a duplicate hologram with less ghost can be efficiently produced with a simple optical system and a small space. Is preferred. This is because, as will be described in detail later, the holograms manufactured by the first and second inventions are good quality holograms with little ghost due to surface reflected light. A hologram can be obtained.

The method for producing a duplicate hologram using the master hologram requires less production space than the case where a hologram is produced using another optical element such as a lens (see FIG. 12). There is an advantage that a complicated image can be easily recorded on the hologram.

That is, since the hologram is a thin plate, it does not occupy more space than a lens or other optical element, and its size does not change even if it has a complicated diffraction characteristic.
On the other hand, in the case of optical elements such as lenses, in order to realize complicated optical characteristics, the manufacturing apparatus becomes large, such as stacking multiple optical elements, and the optical system becomes complicated. It is difficult to manufacture.

Then, there is, for example, the following method for producing a hologram by the one-beam method using the master hologram produced by the first and second inventions. That is, a duplication prism having the same apex angle ψ ₁ as the first prism in the first and second inventions is used, and a duplication photosensitive plate is arranged on the first surface forming the apex angle of the duplication prism. , Arranging the master hologram on a second surface forming an apex angle, and irradiating from the first surface side with substantially the same reference light as that used for manufacturing the master hologram from substantially the same angle. The light and the reproduction light obtained by diffracting the reference light by the master hologram form interference fringes on the duplication plate.

By using this method, it is possible to use the same first prism as that used to manufacture the master hologram according to the first and second inventions as a duplication prism, and to use the same reference light as used to manufacture the master hologram. A duplicate hologram can be manufactured by irradiating the replica prism from an angle of. That is, the master hologram manufacturing conditions and the duplicate hologram manufacturing conditions can be very similar.

At this time, since the same reference light used for manufacturing the master hologram is applied to the master hologram from the same direction, the reproduced light of the master hologram is the same as the object light used for manufacturing the master hologram. Become. The reproduced light contains very little ghost hologram noise due to the surface-reflected light, and is extremely high quality object light. Therefore, the production conditions for the duplicate hologram and the master hologram are very similar, and it is possible to produce a duplicate hologram having a very high similarity to the master hologram.

In the method for producing a duplicate hologram by the one-beam method, it is preferable to provide a non-reflective coating glass on the interface (outside air side) of the duplicating photosensitive plate. This is because if the non-reflective coated glass is provided, it is possible to prevent the reproduction light (object light) of the master hologram from being reflected at the interface, which becomes noise light and forms a ghost on the duplicate hologram. See Examples 1 and 2). Further, at this time, if P-polarized light is used as the reference light,
Since the reflectance at the interface decreases, the surface reflection noise can be further suppressed.

Further, a λ / 4 wavelength plate may be provided at the interface of the duplication photosensitive plate instead of the antireflection coated glass. In this case, the reproduction light of the master hologram changes its polarization direction by reciprocating the λ / 4 wavelength plate (S polarization → circular polarization → P
Since polarized light, P-polarized light → circularly polarized light → S-polarized light), no interference fringe is formed between the surface-reflected light and the reproduction light at the interface. However, in this case, the reference light incident on the λ / 4 wavelength plate needs to be circularly polarized. Then, by passing through the λ / 4 wavelength plate, it is converted into P-polarized light and enters the duplication photosensitive plate.

In addition, in the above-mentioned duplication method by the one-beam method, λ / 4 is also applied to the interface of the master hologram with the outside air.
It is preferable to provide a wave plate. By providing the λ / 4 wavelength plate, the surface reflected light of the P-polarized reference light is λ / 4
Since the light travels back and forth through the wave plate, it becomes S-polarized light (the electric field direction is perpendicular to the incident surface). As a result, interference fringes are not formed between the surface-reflected light (S-polarized light) and the reference light (P-polarized light) at the interface of the master hologram, and the ghost hologram due to the surface-reflected light of the master hologram is not formed. .

Alternatively, instead of the λ / 4 wave plate, a light absorbing film may be provided on the interface (outside air side) of the master hologram. If the light absorbing film is provided, the reference light transmitted through the master hologram is absorbed at the interface of the master hologram. As a result, the surface reflected light is significantly reduced, and it is possible to suppress the formation of a ghost in the duplicate hologram due to the surface reflected light of the master hologram.

[0027]

In the manufacturing method of the present invention, as shown in FIG. 7, both sides of the photosensitive plate 81 on which the hologram is formed are first and second sides.
The second prisms 25 and 26 sandwich it. The apex angle of the first prism 25 is ψ ₁ , and the apex angle of the second prism 26 is ψ ₂ .

The reference light 31 enters from the first prism 25 and travels in the first prism 25 toward the photosensitive plate 81.
Angle θ ₁ with the normal line N ₁ at the first interface 251 of No. 11
Assuming that (refraction angle θ ₁ ), the incident angle θ ₂ on the photosensitive plate 81 is
Is (θ ₁ + φ ₁ ). (Φ ₁ is negative when the apex angle of the first prism 25 is arranged on the opposite side of the photosensitive plate).

The second interface 2 formed by the second prism 26
The incident angle θ _{3 at} 61 is (θ ₂ + ψ ₂ ), that is, (θ ₁ +
ψ ₁ + ψ ₂ ). Since the angle a formed between the surface-reflected light 33 of the reference light 311 and the reference light 311 at the second prism 26 is 2θ ₃ , 2 (θ ₁ + ψ ₁ + ψ
₂ ) (a = 2 (θ ₁ + ψ ₁ + ψ ₂ )).

Since the angle a is close to a right angle (π / 2), (ψ ₁ + ψ ₂ ) ≈π / 4−θ ₁ ... (1) (where, ≈ indicates a close value). Further, the reference light 31 is P-polarized light. Since the reference light 311 directed to the photosensitive plate 81 and the surface-reflected light 33 are close to a right angle as described above, the electric fields of both lights 311 and 33 are close to a right angle, and almost no interference fringes are formed. That is, the surface reflection light 3 of the reference light 31 on the second prism 3
The ghost hologram of 3 is not formed on the photosensitive plate 81 (first effect). This is because when the interference fringes are formed by two P-polarized lights, the contrast (intensity) of the interference fringes created by the two is, when the angle between them is Φ,
This is because it is proportional to cosΦ.

Further, since the incident angle θ ₂ (= ψ ₁ + θ ₁ ) of the reference light 311 to the photosensitive plate 81 is usually in the range of 20 ° to 50 °, the apex angle ψ ₂ is calculated from the equation (1). It is about -5 to 25 °, and both the apex angles ψ ₁ and ψ ₂ can be suppressed to small values. Therefore, even if the prisms 25 and 26 are provided, the manufacturing space is not significantly increased (second effect).

Further, in the case of the first invention, the first prism 2
5, the surface 251 on the atmosphere side is subjected to antireflection treatment, while in the case of the second invention, the surface 251 of the first prism 25 is provided with a λ / 4 wavelength plate. Therefore, the reflected light 3 of the object light 32 on the surface 251 of the first prism 25
The interference fringes (ghost hologram) of noise due to 22 are
Almost never formed (third effect). That is, the first
In the case of the invention, the first prism 2 is processed by the antireflection treatment.
In the case of the second invention, the reflected light 322 reflected by the surface 251 of the first prism 25 after passing through the λ / 4 wave plate is S-polarized.
No interference fringe is formed with the regular object light 32 that is polarized light.

The spectral characteristics of the antireflection film of the antireflection treatment of the first aspect of the invention must be determined by the wavelength of the photographing laser light and the photographing angle. Further, since the spectral characteristic changes depending on the polarization direction, it is necessary to reduce the reflectance of the photographing laser light having the spectral characteristic as P-polarized light.

As described above, since the noise caused by the reflected light on the surface of the first prism and the noise caused by the reflected light on the surface of the second prism are all suppressed, a high quality hologram can be obtained. As described above, according to the present invention, it is possible to suppress the generation of a ghost hologram due to surface reflected light at the interface with the atmosphere, and to provide a hologram manufacturing method that does not require a large manufacturing space. .

[0035]

【Example】

Example 1 This example is a vehicle head-up display 40 (FIG. 2).
Hologram 42 having the characteristics of a concave mirror used for
It is an example of manufacturing (FIG. 2). In this example, as shown in FIG. 1, both sides of the photosensitive plate 81 are sandwiched by a first prism 25 having an apex angle ψ and a second prism 26 having an apex angle ψ, and the reference light 31 is emitted from the first prism 25 side. , Is a method of manufacturing a hologram in which the object light 32 is applied to the photosensitive plate 81 from the second prism 26 side to form interference fringes on the photosensitive plate 81.

The reference light 31 is P-polarized (the direction of the electric field is parallel to the incident surface) linearly polarized light, and enters the first prism 25 and travels toward the photosensitive plate 81. 311 is the surface 26 on the atmosphere side of the second prism 26.
1 so that the angle a formed by the surface reflected light 312 reflected at 1 becomes a right angle, and the apex angle ψ and the incident angle θ of the reference light 31 are
The relationship between and is defined. And the object light 32 is also P
It is polarized linearly polarized light, and an antireflection film 14 (or λ / 4 wavelength plate) is formed on the surface of the first prism 25 on the atmosphere side (note that in the case of a λ / 4 wavelength plate). Is circularly polarized light which is incident on the first prism 25, is transmitted through the λ / 4 wave plate and is converted into P polarized light).

As shown in FIG. 2, the head-up display 40 reflects the emitted light 38 radiated from the display 41 by the hologram 42 having an image enlarging action (concave mirror characteristic), and the reproduced light 39 is reflected by the windshield 43. The display image 45 is re-reflected by the viewer to visually recognize the display image 45.
A reflective film or the like is deposited on the surface of the windshield 43 to enhance the reflectance. And the viewer 4
Reference numeral 4 visually recognizes the reflected reproduction light 39 and visually recognizes a display image 45 (for example, speed display) as a virtual image in front of the windshield 43. In this example, the hologram 4
2, the interference fringes 51 as shown in FIG. 4 are formed on the hologram 42.

In FIG. 1, the reference light 31 is P-polarized divergent light. Then, the interface 261 of the second prism 26
Surface reflection light 31 of the reference light 31 reflected to the photosensitive plate 81 side by
As shown in FIG. 3, the angle a between 2 and the reference light 311 that enters from the first prism 25 and travels toward the photosensitive plate 81 is
The apex angle ψ and the incident angle θ of the reference light 311 should be set to be a right angle.
Has been established. The object light 32 is P-polarized parallel light. In addition, the surface 25 of the first prism 25 on the atmosphere side
1, an antireflection film (or λ / 4 wavelength plate) 14 having a reflectance of the photographing laser light of 1% or less is formed.

The refractive index adjusting liquid 12 is provided on both sides of the photosensitive plate 81.
Prisms 25 and 26 are arranged through 1,122. The reference light 31 is P-polarized light, is incident on the first prism 25 at an incident angle θ, and is incident on the first prism 25 at a refraction angle θ.
Enter at ₁ (see Figure 7).

The transmitted light 311 that has entered the first prism 25 enters the photosensitive plate 81 at an incident angle θ ₂ (= θ ₁ + ψ), and enters the interface 261 of the second prism 26 at an incident angle θ ₃ (=
It is incident at θ ₁ + 2ψ) (see FIG. 7). The surface-reflected light 312 reflected by the interface 261 is reflected by the photosensitive plate 81 at a reflection angle θ _3.
Go backwards toward.

Surface reflected light 312 and reference light 31 transmitted light 3
The angle a with 11 is equal to 2θ ₃ and its value is π
/ 2. _{a = 2θ 3 = 2 (θ} 1 + 2ψ) = π / 2 ······· (3) Therefore, it is _{ψ = π / 8-θ 1} /2 ······· (4).

Surface reflected light 312 and reference light 31 transmitted light 3
Since the angle with 11 is a right angle and the light is P-polarized light, no interference fringes are formed on the photosensitive plate 81 by the two lights 311 and 112. That is, the ghost hologram by the surface reflected light 312 is not formed on the photosensitive plate 81.

In this example, the antireflection film (or λ / 4 wave plate) 14 is formed on the surface 251 of the first prism 25 on the atmosphere side.
Are formed. Therefore, the surface 251 of the object light 32
The ghost hologram by the reflected light 320 at the photosensitive plate 8
1 is not formed. This is because when the antireflection film is provided, the reflected light 320 does not occur, whereas in the case of the λ / 4 wave plate, the object light 32 (P-polarized light) and the reflected light 320 (S) are generated due to the difference in the polarization direction. This is because no interference fringe is formed between the polarized light and the polarized light.

Next, the size of the second prism 26 in this example will be compared with that of the conventional second method (FIG. 10). Assuming that the apex angle of the prism 961 shown in FIG. 10 is α, as shown in FIG.
The condition to prevent the incidence on 1 is (2θ ₃ +2
α) is π or more. 2θ ₃ + 2α ≧ π (5)

Then, in FIG. 10, θ ₃ = θ ₁ + ψ +
an alpha, because ψ in Figure 1 is represented by equation (4), an _{α ≧ 3 / 16π-θ 1} /4 ······· (6). Thus, α-ψ ≧ π / 16 + θ 1/4 ······ (7) i.e., alpha> [psi next, from the prism 961 in a conventional second method, the second prism 26 of this embodiment is more compact be able to.

The hologram 42 manufactured by the above manufacturing method is formed with regular interference fringes 51 as shown in FIG. 4 showing the characteristics of the concave mirror. On the other hand, the ghost hologram formed by the surface-reflected light 320, 312 of the first and second prisms 25, 26 has the characteristic of a plane mirror, and noise interference fringes 52, 53 as shown in FIG. Has been formed. However, the major difference between the first noise interference fringe 52 due to the surface reflected light 320 and the second noise interference fringe 53 due to the surface reflected light 312 is that the normal line (optical axis) N of the first noise interference fringe 52 is N. Interference fringe 5 that is normal in _one direction
However, the normal line (optical axis) N _{2 of} the second noise interference fringe 53 is largely deviated from the normal interference fringe 51 by an angle 2ψ.

As a result, when used as a head-up display as shown in FIG. 5, the noise image 64 due to the second noise interference fringes 53 is a regular image 61 (a cubic image in this example).
Since the angle is shifted by an angle 4ψ that is twice the angle 2ψ, the images are not simultaneously observed within the visual field of the viewer 44, and the degree of influence is small. On the other hand, in the case of the first noise interference fringes 52, since they are formed in the same direction as the regular interference fringes 51, as shown in FIG. , 63 are formed.

That is, the noise image 62 simply reflected in the interference fringes 52 is a small image which is not magnified through the plane mirror.
The noise image 63 obtained by multiple reflection of the interference fringes 52 and the regular interference fringes 51 is a further enlarged large image, which is a regular image 61.
Will be overlaid. However, in the hologram manufacturing method of this example, the antireflection film 14 (or λ / 4 wavelength plate) is provided on the surface of the first prism 25 on the atmosphere side so that the first interference fringes 52 are not formed. The malicious noise images 62 and 63 as described above are not formed.
Therefore, the head-up display 4 having good display characteristics
0 can be obtained. As described above, according to this example,
It is possible to provide a hologram manufacturing method capable of suppressing the generation of a ghost hologram due to the surface-reflected light of the reference light and causing no increase in manufacturing space.

Example 2 This example is another example of producing a duplicate hologram using the hologram produced by the production method of Example 1 as a master hologram. In this example, the hologram manufactured by the hologram manufacturing method shown in FIG. 1 is used as a master hologram 83, and as shown in FIG. 6, a duplication prism having the same apex angle ψ as the first prism 25 (FIG. 1). Two
7, the first surface 27 forming the apex angle of the prism 27
The duplication photosensitive plate 82 is arranged on the first side, and the master hologram 83 is arranged on the second surface 272 forming the apex angle.

Then, the first surface 27 of the replica prism 27
From the 1st side, the same reference light 31 as that used to manufacture the master hologram 83 as shown in FIG. 6 (either P-polarized light or S-polarized light can be used. However, from the viewpoint of the effect of suppressing surface reflection noise during replication, P-polarized light is used. 1), and a reproduction light 34 obtained by reflecting the reference light 31 by the master hologram 83 and the reference light 31 to form interference fringes on the duplication photosensitive plate 82. Is.

At the interface 831 of the master hologram 83, a light absorbing film (or non-reflection coated glass) 15 is provided to suppress the surface reflected light 333 at the interface 831.
Is arranged. In addition, the refractive index adjusting liquids 121, 122, 123 are interposed between the prism 27 and the photosensitive plate 82 and the master hologram 83, and between the master hologram 83 and the light absorbing film (or non-reflective coating glass) 15. There is.

Since the reference light 31 similar to that shown in FIG. 1 is emitted, the reproduction light 34 of the master hologram 83 becomes reproduction light 34 which is exactly the same as the object light 32 shown in FIG. Therefore, in FIG. 6, almost the same manufacturing conditions as those shown in FIG. 1 are reproduced, and a hologram similar to the master hologram 83 with few ghost holograms is formed on the duplication photosensitive plate 82.

Since the surface reflection light 333 is absorbed by the optical absorption film 15, the ghost hologram due to the surface reflection light 333 can be suppressed. In addition, the duplication prism 27 can use the first or second prisms 25 and 26 as they are, and the reference light 31
Since the optical system for irradiating the laser beam can be used in its entirety, many facilities can be shared between the production of the master hologram and the production of the duplicate hologram. Therefore, the utilization efficiency of the equipment is high.

Further, the same manufacturing conditions are surely ensured, and a good duplicate hologram can be obtained. Also,
Since the master hologram is duplicated, the manufacturing space is small (the structure shown in FIG. 6 is significantly space-saving as compared with FIGS. 1, 10 and 11). As described above, according to this example, it is possible to manufacture a high quality duplicate hologram having extremely high identity from the master hologram in a small manufacturing space.

Embodiment 3 This embodiment is another embodiment in which a λ / 4 wave plate is arranged in place of the light absorption film 15 at the interface 831 of the master hologram 83 in the embodiment 2 (FIG. 6). . In this example, the reference light 31 is P-polarized light as in the case of the fourth embodiment, and in FIG. 6, a λ / 4 wavelength plate is provided instead of the light absorption film 15. Therefore, the surface-reflected light 333 becomes S-polarized light that travels back and forth through the λ / 4 wavelength plate.

Therefore, the surface reflected light 333 does not form an interference film with the reference light 31 which is P-polarized light. Therefore, the ghost hologram by the surface reflected light 333 is not formed on the duplication photosensitive plate 82. Others are described in Example 2.
Is the same as

[Brief description of the drawings]

FIG. 1 is a system configuration diagram (two-beam method) of a hologram manufacturing method according to a first embodiment.

FIG. 2 is a system configuration diagram of a head-up display using the hologram obtained by the hologram manufacturing method of the first embodiment.

FIG. 3 is an enlarged view of an arrow A in FIG.

FIG. 4 is a schematic diagram of interference fringes of a hologram obtained by the hologram manufacturing method of Example 1.

5 is a schematic diagram of an image formed on a head-up display by the interference fringes 51, 52, 53 shown in FIG.

FIG. 6 is a system configuration diagram (one-beam method) of the hologram manufacturing method according to the second embodiment.

FIG. 7 is a system configuration diagram of a hologram manufacturing method according to the present invention.

FIG. 8 is an explanatory diagram of a conventional hologram manufacturing method.

9 is an example of a ghost hologram manufactured by the method of FIG.

FIG. 10 shows a conventional improved hologram manufacturing method (second method).

FIG. 11 is a conventional improved hologram manufacturing method (first method).

FIG. 12 shows a conventional improved hologram manufacturing method (another second method).

[Explanation of symbols]

 14． . . Antireflection film (λ / 4 wavelength plate) 25. . . First prism 26. . . Second prism 31, 311, 312. . . Reference light 32. . . Object light 81. . . Photosensitive plate

Claims (5)

[Claims] 1. A photosensitive plate is sandwiched on both sides by a first prism having an apex angle of ψ1 and a second prism having an apex angle of ψ2, the reference light from the side of the first prism and the object light from the side of the second prism. A method for manufacturing a hologram, which comprises irradiating a photosensitive plate to form interference fringes on the photosensitive plate, wherein the reference light is P-polarized light (electric field direction is polarized parallel to an incident plane), and The angle a formed between the normal reference light that is incident on the first prism and is directed toward the photosensitive plate and the surface-reflected light that is reflected by the surface of the second prism on the atmosphere side is close to a right angle. , The apex angles ψ 1, ψ 2 and the incident angle θ of the reference light are defined, the object light is also P-polarized linearly polarized light, and the surface of the first prism on the atmosphere side is The hologram is characterized by being subjected to antireflection treatment. Production method. 2. The both sides of the photosensitive plate are sandwiched by a first prism having an apex angle ψ1 and a second prism having an apex angle ψ2, and the reference light from the side of the first prism and the object light from the side of the second prism are described above. A method of manufacturing a hologram in which an interference fringe is formed on a photosensitive plate by irradiating the photosensitive plate, wherein the reference light is P-polarized linearly polarized light, which is incident on the first prism and is directed toward the photosensitive plate. So that the angle a formed between the reference light and the surface-reflected light reflected by the surface of the second prism on the atmosphere side is close to a right angle.
2 and the incident angle θ of the reference light are defined, the object light is also P-polarized linearly polarized light, and
A λ / 4 wavelength plate is arranged on the surface of the first prism on the atmosphere side, and the reference light is light that is converted from circularly polarized light to P polarized light through the λ / 4 wavelength plate. Method for manufacturing hologram. 3. The first apex angle ψ1 and the second apex angle ψ2 have the same angle according to claim 1 or 2, and the both apex angles are on the same side of the photosensitive plate. A method of manufacturing a hologram, characterized in that the prism is arranged so as to be positioned. 4. The master hologram is irradiated with the reference light directly incident on the photosensitive plate and the reference light transmitted through the photosensitive plate,
A method of manufacturing a hologram, in which interference fringes are formed on the photosensitive plate by the reproduced light thus obtained and the master hologram is duplicated, wherein the master hologram is defined by claim 1, claim 2, or claim 3. A method of manufacturing a hologram, which is a hologram obtained by the manufacturing method. 5. The hologram manufacturing method according to claim 4, wherein a duplication prism having the same apex angle ψ 1 as that of the first prism for producing the master hologram is prepared, and the duplication prism is used. A photosensitive plate is arranged on the first surface forming the apex angle of the, the master hologram is arranged on the second surface forming the apex angle, and the master hologram is manufactured from the side of the first surface. A method of manufacturing a hologram, characterized in that substantially the same reference light is incident from substantially the same angle, and the reference light and the reproduction light diffracted and reflected by the master hologram form interference fringes on the photosensitive plate.