JPH09330010A - Hologram photographing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce undesired interference fringes due to undesired light such as boundary reflection, high order diffraction, is recorded when a hologram is photographed, and copied. SOLUTION: This method is a hologram photographing method having a relief hologram for an original plate 7', arranging photosensitive material 13 close to its relief surface, making a luminous flux 9 incident on the form 7' and copying the interference fringes 31 in the photosensitive material 13 by the interference of the prescribed number-th diffraction light 10' diffracted from the form 7' with incident light or 0-order transmission light 11. Then, for preventing the undesired interference fringes 32 due to the diffraction light 15 excepting the prescribed number-th from being recorded simultaneously, when the photosensitive material 13 is displaced by nearly a half of a pitch ▵2 in the displacing direction of the undesired interference fringes 32 while photographing the hologram, since the undesired interference fringes 32 are canceled each other by themselves to be smoothened, the undesired interference fringes 32 are removed without adversely affecting the interference fringes 31 to be aimed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hologram photographing method, and more particularly to a hologram duplication / photographing method for reducing recording of unnecessary interference fringes.

[0002]

2. Description of the Related Art In recent years, many kinds of hologram optical elements have been put into practical use. Diffraction grating, hologram lens,
In addition to ordinary hologram optical elements such as a hologram lens array and a hologram light polarizing element, the present applicant has proposed a hologram color filter for a liquid crystal display device in Japanese Patent Application No. 5-121.
No. 70, etc. The structure is composed of an eccentric Fresnel zone plate-shaped micro hologram array. Further, in the above application, as another hologram color filter for liquid crystal display device that performs the same operation as this minute hologram array, a hologram or diffraction grating composed of parallel and uniform interference fringes and its entrance side or exit side is arranged. It also proposes a lens array with a condensing lens array. The hologram color filter will be briefly described below.

A liquid crystal display device using a hologram color filter composed of a fine hologram array will be described with reference to the sectional view of FIG. In the figure, a hologram array 5 constituting this hologram color filter is arranged at a distance from the backlight 3 incident side of a liquid crystal display element 6 which is regularly divided into liquid crystal cells 6 '(pixels). On the back surface of the liquid crystal display element 6, a black matrix 4 provided between the liquid crystal cells 6 'is arranged. In addition to the above, polarizing plates (not shown) are arranged on both sides of the liquid crystal display element 6. It should be noted that an absorption type color filter that transmits light of colors corresponding to R, G, and B color separation pixels is arranged between the black matrix 4 as in the conventional color liquid crystal display device. Is also good.

The hologram array 5 has a repetition period of R, G, and B color separation pixels, that is, a set of three liquid crystal cells 6 ′ adjacent to each other in the direction of the liquid crystal display element 6 in the plane of the paper. The micro holograms 5 'are arranged in an array at the same pitch as the repetition pitch. The micro holograms 5' are aligned with each set of three liquid crystal cells 6 'adjacent to each other in the direction of the plane of the liquid crystal display element 6, and each hologram 5' Each of the micro holograms 5 ′ corresponds to the light of the green component in the backlight 3 that enters at an angle θ with respect to the normal to the hologram array 5 and corresponds to the micro hologram 5 ′. It is formed in a Fresnel zone plate shape so that light is condensed on the liquid crystal cell G at the center of the three color separation pixels R, G, and B. The micro hologram 5 ′ has a relief type, which has no or little wavelength dependence of the diffraction efficiency.
It consists of transmission holograms such as phase type and amplitude type. Here, the fact that there is no or little wavelength dependence of the diffraction efficiency is not a type that diffracts only a specific wavelength and does not diffract other wavelengths like a Lippman hologram,
Means that one diffraction grating diffracts any wavelength,
The diffraction grating having a small wavelength dependence of the diffraction efficiency diffracts at different diffraction angles according to the wavelength.

[0005] With such a configuration, when the white backlight 3 that enters at an angle θ with respect to the normal line from the surface of the hologram array 5 opposite to the liquid crystal display element 6 is incident, the wavelength is reduced. Accordingly, the diffraction angle of the minute hologram 5 'is different, and the light condensing position for each wavelength is dispersed in a direction parallel to the hologram array 5 surface. Among them, the red wavelength component is located at the position of the liquid crystal cell R displaying red, the green component is located at the position of the liquid crystal cell G displaying green, and the blue component is located at the position of the liquid crystal cell B displaying blue. By arranging the hologram array 5 so as to diffract and collect light, each color component passes through each liquid crystal cell 6 ′ with almost no attenuation in the black matrix 4 and the liquid crystal cell 6 ′ at the corresponding position. Color display can be performed according to the state.

As described above, by using the hologram array 5 as a color filter, each wavelength component of the conventional color filter backlight can be made incident to each liquid crystal cell 6'without being absorbed, and its utilization efficiency is improved. Can be significantly improved.

Next, with reference to the sectional view of FIG. 4, a hologram or a diffraction grating having parallel and uniform interference fringes and a condensing lens array arranged on the incident side or the exit side thereof are used as a hologram color filter. A liquid crystal display device using will be described. In the figure, a hologram color filter 10 of the second type comprises a hologram 7 and a condensing microlens array 8, and microlenses 8 'constituting the microlens array 8 are R, G, B color separation. The pixels are arranged in an array at the same pitch as the repetition cycle of the pixels, that is, each set of three liquid crystal cells 6 ′ adjacent to each other in the direction of the paper surface of the liquid crystal display element 6. The hologram 7 is composed of parallel and uniform interference fringes acting as a diffraction grating, and is formed of a transmission hologram such as a relief type, a phase type, and an amplitude type having little or no wavelength dependence of diffraction efficiency. On the back surface of the liquid crystal display element 6, a black matrix 4 provided between the liquid crystal cells 6 'is arranged. In addition to the above, polarizing plates (not shown) are arranged on both sides of the liquid crystal display element 6. In addition,
As in the conventional color liquid crystal display device, an absorption type color filter which transmits light of colors corresponding to the R, G and B color separation pixels is additionally arranged between the black matrixes 4. May be.

With such a configuration, the hologram 7
When the backlight 3 is incident on the surface opposite to the liquid crystal display element 6 at an angle θ with respect to the normal line, the light is diffracted at different angles depending on the wavelength and dispersed on the exit side of the hologram 7. . Due to the microlenses 8 ′ arranged on the entrance side or the exit side of the hologram 7, this dispersed light
The light is separated and focused on the focal plane for each wavelength. Among them,
The red wavelength component is diffracted and condensed at the position of the liquid crystal cell R for displaying red, the green component is diffracted and condensed at the position of the liquid crystal cell G for displaying green, and the blue component is condensed at the position of the liquid crystal cell B for displaying blue. As described above, by arranging the color filter 10, each color component passes through each liquid crystal cell 6 'with little attenuation by the black matrix 4, and corresponds to the state of the liquid crystal cell 6' at the corresponding position. Color display can be performed.

In such an arrangement, as the hologram 7, a transmission hologram having uniform interference fringes and having a small wavelength dependency of diffraction efficiency, which is not a light-collecting property, can be used. And the pitch of the microlens array 8 is different from that of each liquid crystal cell 6 '.
It is three times as large as the conventional case where one microlens is arranged corresponding to each, and is characterized in that it is easy to manufacture and easy to align.

As a modification of FIG. 4, as shown in FIG. 5, the arrangement of the microlens array 8 and the liquid crystal display element 6 is as shown in FIG. Hologram 7 into micro lens array 8
Even if it is disposed in the backlight 3 so as to be substantially perpendicular to the traveling direction, each wavelength component of the backlight can be similarly incident on each liquid crystal cell 6 ′ without waste and without absorption. Thus, a color filter whose use efficiency has been greatly improved can be realized.

The color filter 5 composed of the hologram array as described above is manufactured by, for example, a duplication method by the two-beam interference of the multi-point converged light and the zero-order transmitted light emitted from the minute hologram lens array composed of the computer generated hologram (Japanese Patent Application No. 2000-242242). Hei 5-14572). Figure 6 shows the duplication method.
Briefly described with reference to the cross-sectional view of FIG. 5, a hologram interference fringe of the minute hologram 5 'is calculated by a computer, and the interference fringe is drawn by an electron beam on a glass substrate coated with an electron beam resist, for example, and developed. , Relief type computer generated hologram (CGH: Computer Ge)
An array 7'of a related hologram 5 "is prepared. Next, as shown in FIG. 6, the hologram photosensitive material 18 is brought into close contact with the relief surface of the CGH array 7'prepared in this way or overlapped with a slight gap. In addition, the laser beam 9 is made incident from the CGH array 7 ′ side at an angle θ corresponding to the backlight 3 of FIG. 3, and the convergent diffracted light 10 ′ and the straight transmitted light 11 generated by each CGH 5 ″ of the CGH array 7 ′ are hologramed. The CGH array 7'is reproduced by causing interference in the photosensitive layer 13 of the photosensitive material 18. This duplicated hologram is used as the hologram array 5 in FIG. The hologram array 5 can be manufactured by further duplicating the duplicate hologram as an original plate.

The hologram 7 composed of parallel and uniform interference fringes acting as a diffraction grating of the hologram color filter 10 has a glass substrate 12 as shown in FIG.
The hologram light-sensitive material 18 on which the photosensitive layer 13 is provided has two parallel light beams 21 and 22 that form an angle with each other from the photosensitive layer 13 side.
Is made incident to cause interference in the photosensitive layer 13 and recording is performed.

[0013]

By the way, when the hologram is photographed by the duplication of FIG. 6, the laser beam 9 is CGH.
In addition to the 0th-order light 11 that passes through 7 ′ without being diffracted and the + 1st-order light 10 ′ that is diffracted in the + first-order direction, there is a + second-order light 15 (FIG. 1) that is partially diffracted in the + second-order direction. Originally CGH
The interference fringe to be copied from 7'is the interference fringe 31 (solid line in FIG. 1) between the 0th-order light 11 and the + 1st-order light 10 ', but the 0th-order light 11 and the + 2nd-order light 15 also interfere and are unnecessary interference. The stripe 32 (dotted line in FIG. 1) is recorded. This interference fringe 32 is used as the hologram color filter 5 as shown in FIG.
The backlight 3 does not disperse the light at a predetermined position into the corresponding pixels R, G, and B, but becomes a stray light component, which hinders display contrast and color reproducibility.

Also, as shown in FIG. 2, when two light beams 21 and 22 are made incident on the photosensitive layer 13 from the same direction to cause interference, a part of the light (dotted line) passes through the photosensitive layer 13 to cause the glass. The light is reflected by the interface such as the back surface of the substrate 12 and returns to the photosensitive layer 13 again, and interferes with the incident lights 21 and 22, and unnecessary interference fringes 32 (dotted lines) are recorded in the direction along the photosensitive layer 13. When this interference fringe 32 is also used as the hologram 7 of the hologram color filter 10 as shown in FIG. 4, a part of the backlight 3 is diffracted in the reflection direction instead of the predetermined direction,
A part of the backlight 3 is wasted, and it is not possible to achieve sufficient utilization efficiency.

In the above description, the hologram color filter was taken as an example of the hologram. However, when photographing / reproducing a hologram for other purposes, for example, a diffraction grating, a hologram lens, a hologram lens array, a hologram light polarization element, or the like. Also has a problem that similar unnecessary interference fringes are recorded.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to record unnecessary interference fringes based on unnecessary light such as interface reflection and high-order diffraction at the time of hologram photographing and duplication. It is to provide a method of reducing the risk of being lost.

[0017]

The hologram photographing method of the present invention which achieves the above object is a hologram photographing method of recording interference fringes in a photosensitive material by interference of two light beams. In order to prevent simultaneous recording, the photosensitive material is displaced by approximately half the pitch of the unwanted interference fringes in the displacement direction during hologram recording.

In another hologram photographing method of the present invention, a relief hologram is used as an original plate, a photosensitive material is arranged in the vicinity of the relief surface, a light beam is incident on the original plate, and a predetermined order diffracted from the original plate is obtained. In a hologram photographing method in which interference fringes are reproduced in the photosensitive material by interference between diffracted light and the incident light or the 0th-order transmitted light, unnecessary interference fringes based on diffracted light other than the predetermined order are simultaneously recorded. In order to prevent this, the photosensitive material is displaced by approximately half the pitch in the displacement direction of the unwanted interference fringes during hologram recording.

In this case, in particular, the diffracted light of the predetermined order is +1.
This is the diffracted light of the second order, and is effective when the unnecessary interference fringe is the interference fringe of the 0th-order transmitted light and the + 2nd-order diffracted light.

The displacement direction may be a direction along the layer of the photosensitive material or a direction orthogonal thereto. Of course, it may be in any other direction.

An example of the hologram imaged according to the present invention is an array in which condensing element holograms are periodically arranged, and each element hologram is incident on the recording surface at an angle to white. There are hologram color filters that disperse light into wavelengths in the direction along the recording surface to disperse light, and holograms that are composed of parallel and uniform interference fringes.

In the present invention, since the photosensitive material is displaced by approximately half the pitch in the displacement direction of the unwanted interference fringes during hologram recording, the unwanted interference fringes are canceled and smoothed by themselves, so that the desired interference is obtained. Unwanted interference fringes can be removed without adversely affecting the fringes. As a result, it is possible to manufacture a hologram such as a hologram color filter having good performance without unnecessary interference fringes.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the hologram photographing method of the present invention will be described below with reference to the drawings. FIG. 1 is FIG.
FIG. 9 is a diagram showing an arrangement in which a hologram such as the hologram color filter 5 of FIG. 2 is copied from a computer generated hologram (GGH) 7 ′ and photographed. The CGH 7 ′ calculates the hologram interference fringes by the computer as described above, and, for example, An interference fringe is drawn on a glass substrate coated with an electron beam resist by an electron beam and developed to form a relief hologram. A hologram photosensitive layer (photosensitive material) 13 provided on a glass substrate (not shown) is superposed from the photosensitive layer 13 side to the relief surface of the CGH 7'with a slight gap, and a laser is emitted from the CGH 7'side at a predetermined incident angle. The light 9 is made incident, and the + 1st order diffracted light 10 ′ generated by the CGH 7 ′ and the straight 0th order light 11 interfere with each other in the photosensitive material 13 to generate a desired interference fringe 31, which is recorded in the photosensitive material 13. To replicate CGH7 '.

By the way, as described above, from the CGH 7 ', in addition to the 0th-order light 11 and the + 1st-order light 10', there exists the + 2nd-order light 15 diffracted in a different direction. This +2
The second light 15 and the zeroth light 11 also interfere with each other, and the unwanted interference fringes 32 (dotted line) are simultaneously recorded. Stray light or the like is generated by the interference fringes 32, which has an adverse effect.

Therefore, in the present invention, the unnecessary interference fringes 3
Paying attention to the fact that the pitch of 2 is smaller than the desired pitch of the interference fringes 31, the photosensitive material 13 is vibrated with a small amplitude during hologram recording, and the unnecessary interference fringes 32 are smoothed within a range that does not adversely affect the useful interference fringes 31. The unnecessary interference fringes 32 are prevented from being recorded by smoothing (cancelling each other).

That is, in the case of the hologram color filter 5 of FIG. 3, for example, the pitch Δ ₁ of the desired interference fringes 31 (solid line) by the 0th order light 11 and the + _1st order light 10 'in the direction along the photosensitive layer 13 is 0.7 μm. 0 degree light 1
The pitch Δ ₂ of the unwanted interference fringes 32 due to the 1st and + _2nd order lights 15 in the direction along the photosensitive layer 13 is about 0.35 μm. Therefore, by using the vibrator 30, in the direction along the photosensitive layer 13, half the pitch Δ ₂ of the unnecessary interference fringes 32 is 0.175 μm.
The photosensitive layer 13 is vibrated (displaced) during the CGH7 'replication with the amplitude of
Let it.

In this way, the unnecessary interference fringes 32 can be removed by displacing them by about half the pitch Δ ₂ of the unnecessary interference fringes 32 during hologram recording. In contrast, since the pitch delta ₁ of the desired interference pattern 31 is Δ _1> Δ _2, since there is no be canceled even when the displacement of the order of delta _2/2 in the hologram imaging, useful by the displacement The influence of the interference fringe 31 is in a negligible range. As a result, it is possible to manufacture a hologram optical element such as a hologram color filter having good performance without unnecessary interference fringes. Examples of the oscillator 30 that can be used include a tuning fork oscillator, an electrostrictive oscillator, a magnetostrictive oscillator, a piezoelectric oscillator, and a crystal oscillator.

While FIG. 1 shows an embodiment in which a hologram is photographed by duplication, FIG. 2 shows an arrangement of the present invention when the hologram 7 of the hologram color filter 10 in FIG. 4 is photographed by two-beam interference. In the hologram photographing in this case, in the photosensitive layer 13, two holograms 21 and 22 forming an angle with each other are made incident on the hologram photosensitive material 18 having the photosensitive layer 13 provided on the glass substrate 12 from the photosensitive layer 13 side. The interference is generated to generate a desired parallel and uniform interference fringe 31 (solid line), and the image is recorded in the photosensitive material 13.

In this case, as described above, the incident light 2
Part (dotted line) of 1 and 22 passes through the photosensitive layer 13, is reflected by an interface such as the back surface of the glass substrate 12 and returns to the photosensitive layer 13 again, and interferes with the incident light 21 and 22 and follows the photosensitive layer 13. Directional unwanted interference fringes 32 (dotted lines) are generated. In this case, the pitch of the unnecessary interference fringes 32 in the direction orthogonal to the photosensitive layer 13 is smaller than the pitch of the useful interference fringes 31.

Therefore, in this case, the vibrator 30 is used to vibrate (displace) the hologram photosensitive material 18 in the direction orthogonal to the photosensitive layer 13 at a half amplitude of the pitch of the unnecessary interference fringes 32 during hologram recording, and the same result is obtained. By removing the unnecessary interference fringes 32 in principle, it is possible to capture an image of a hologram optical element such as a diffraction grating having good performance without unnecessary interference fringes.

The hologram photographing method of the present invention has been described above by taking the duplication and photographing of the hologram color filter as an example. However, the present invention is not limited to these duplication methods and photographing methods, and various known arrangements are possible. Can be applied to the hologram duplication method and the hologram photographing method. Further, the hologram itself is not limited to the hologram color filter and the diffraction grating, and the imaging method of the present invention can be applied to a hologram optical element such as a hologram lens, a hologram lens array, and a hologram light polarization element.

[0032]

As is apparent from the above description, according to the hologram photographing method of the present invention, the photosensitive material is displaced by about half of the pitch in the displacement direction of the unnecessary interference fringes during the hologram photographing, so that the unnecessary interference fringes themselves Since they cancel each other and are smoothed, unnecessary interference fringes can be removed without adversely affecting the intended interference fringes. As a result, it is possible to manufacture a hologram such as a hologram color filter having good performance without unnecessary interference fringes.

[Brief description of drawings]

FIG. 1 is a diagram showing an arrangement in which a hologram is duplicated and photographed from a computer generated hologram according to the present invention.

FIG. 2 is a diagram showing an arrangement when a hologram is photographed by two-beam interference according to the present invention.

FIG. 3 is a cross-sectional view of a liquid crystal display device using a hologram color filter.

FIG. 4 is a cross-sectional view of a liquid crystal display device using a composite hologram color filter.

FIG. 5 is a sectional view of a liquid crystal display device showing a modification of FIG.

FIG. 6 is a cross-sectional view for explaining a conventional duplication method.

[Explanation of symbols]

 3 ... Backlight 4 ... Black matrix 5 ... Hologram array (hologram color filter) 5 '... Micro hologram 5 "... CGH 6 ... Liquid crystal display element 6' ... Liquid crystal cell 7 ... Hologram 7 '... CGH array original plate (CGH) 8 Condensing microlens array 8 '... Microlens 9 ... Laser light 10 ... Hologram color filter 10' ... Convergent diffracted light (+ 1st order diffracted light) 11 ... Straight transmitted light (0th order light) 12 ... Glass base material 13 ... Photosensitive Layer (photosensitive material) 14 ... Cover film 15 ... + Second-order diffracted light 18 ... Holographic light-sensitive material 21, 22 ... Parallel light 30 ... Transducer 31 ... Desired interference fringe 32 ... Unwanted interference fringe

Claims (7)

[Claims] 1. A hologram photographing method for recording interference fringes in a photosensitive material by interference of two light fluxes, in order to prevent unnecessary interference fringes due to unnecessary light from being simultaneously recorded, the photosensitive medium is exposed during hologram photographing. A hologram photographing method characterized in that a material is displaced by approximately half the pitch in the displacement direction of unnecessary interference fringes. 2. A relief hologram is used as an original plate, a photosensitive material is arranged close to the relief surface, a light beam is made incident on the original plate, and diffracted light of a predetermined order diffracted from the original plate and the incident light or 0 In a hologram photographing method for reproducing interference fringes in the photosensitive material by interference with secondary transmitted light, hologram recording is performed in order to prevent unnecessary interference fringes based on diffracted light other than the predetermined order from being simultaneously recorded. A hologram photographing method, characterized in that the photosensitive material is displaced by approximately half the pitch of the unwanted interference fringes in the displacement direction. 3. The hologram photographing according to claim 2, wherein the diffracted light of the predetermined order is + first-order diffracted light, and the unnecessary interference fringes are interference fringes of 0th-order transmitted light and + 2nd-order diffracted light. Method. 4. The hologram photographing method according to claim 1, wherein the displacement direction is a direction along a layer of the photosensitive material. 5. The hologram photographing method according to claim 1, wherein the displacement direction is a direction orthogonal to the layer of the photosensitive material. 6. A hologram to be photographed comprises an array in which condensing element holograms are periodically arranged, and each element hologram makes white light incident at an angle with respect to a recording surface along a recording surface. 2. A hologram color filter that disperses wavelengths into light and disperses the light.
6. The hologram photographing method according to any one of 1 to 5. 7. The hologram photographing method according to claim 1, wherein the hologram to be photographed is a hologram having parallel and uniform interference fringes.