JP5206915B2 - Blindfold device and method for manufacturing blindfold device - Google Patents

Description

  The present invention relates to a blindfolding device in which a transmitted background cannot be clearly seen, and in particular, when a point light source is observed through a predetermined position using a phase type Fourier transform hologram, a predetermined image or message can be observed near the position of the point light source. And a method for manufacturing the blindfold device.

  Conventionally, as a blindfold device, there are ground glass, mold glass, blinds, roll screens and the like.

  In Patent Document 1, hologram glasses are proposed. The hologram glasses are configured as shown in a perspective view in FIG. That is, two transmission holograms 32 and 33 are fitted in the eyeglass frame 31 for both eyes. When a scene including light sources 34, 35, 36, and 37 having a small area as shown in FIG. 9B is viewed by wearing glasses using the transmission holograms 32 and 33, for example, as shown in FIG. 9C. Looks like. Alternatively, the pattern “NOEL” 38, 39, 40, 41 appears to overlap in the vicinity of the light sources 34, 35, 36, 37. That is, the light source having a small area in the actual scene shown in FIG. 9B is seen as a scene in which the patterns “NOEL” 38, 39, 40, and 41 are selected in advance. As the transmission holograms 32 and 33 having such characteristics, a Fourier transform hologram (Fraunhofer hologram) having the pattern “NOEL” configured as a computer generated hologram is used.

  FIG. 10A is a flowchart showing one method for creating such a transmission hologram (Patent Document 2). FIG. 10B is a schematic diagram for explaining the flowchart. In step 101, an original image 51 is created. Next, in step 102, a Fourier transform image 52 of the original image is created using a computer. Next, in step 103, the Fourier transform image 52 is multi-valued to a binary value or more to create a multi-valued Fourier transform image 53. In step 104, a reproduced image is simulated. In this simulation, an inverse Fourier transform is performed on the multi-valued Fourier transform image 53 to obtain a reconstructed image 54, and it is checked whether or not the processing in each of the above steps has been performed appropriately. Next, in step 105, the obtained multi-valued Fourier transform image is arranged to a desired range. For example, a computer generated hologram 55 is obtained by arranging four binarized Fourier transform images 53. Actually, for example, ten minimum unit images 53 are arranged vertically and horizontally. Next, in step 106, a master for duplication of the computer generated hologram 55 arranged in this way is produced using, for example, a semiconductor process (photolithography and etching). In step 107, the concave / convex relief pattern of the original for duplication is duplicated on, for example, an ultraviolet curable resin to obtain the transmission holograms 32 and 33.

  As a method for creating a computer generated hologram (CGH corresponding to the multi-valued Fourier transform image 53), for example, a Gerchberg-Saxton iterative calculation method as described in Non-Patent Document 1 is known. This method will be briefly described with reference to FIGS.

FIG. 11 is a diagram schematically showing a computer generated hologram 60 and an image region 70 reproduced therefrom. The computer generated hologram 60 is the Fourier transform hologram, small collection of cells 61 of the pitch dimension [delta] _x of the pitch dimension [delta] _y, the horizontal direction (x-axis direction) of the longitudinally arranged in a grid pattern (y-axis direction) Each cell 61 has only phase information. 2 ^m cells 61 are arranged in the x-axis direction and 2 ⁿ cells 61 are arranged in the y-axis direction.

On the other hand, the image region 70 arranged sufficiently far from the computer generated hologram 60 is a set of cells 71 arranged in the same 2 ^m pieces in the x-axis direction and the same 2 ⁿ pieces in the y-axis direction corresponding to the computer generated hologram 60. Each cell 71 has a vertical direction (y-axis direction) dimension Δ _y and a horizontal direction (x-axis direction) dimension Δ _x , and the length of the entire image region 70 in the x-axis direction is L _x and the length in the y-axis direction. it is is a L _y.

The x-axis direction length L _x and the y-axis direction length L _y of the image region 70 are related to the x-axis direction dimension δ _x and the y-axis direction dimension δ _y of the cell 61 of the computer generated hologram 60, respectively. (because the computer generated hologram 60 well there is the image area 70 to a distant location, L _x, L _y is better expressed in angle.) is represented by the diffraction angle from the computer generated hologram 60, L _x is the spatial frequency 1 / corresponds to ± 1 range sandwiched by order diffracted light of the diffraction grating (2δ _x), L _y corresponds to a range sandwiched by ± 1-order diffracted light of the diffraction grating spatial frequency 1 / (2δ _y). This corresponds to the maximum spatial frequency recorded in the computer generated hologram 60 being 1 / (2δ _x ) in the x-axis direction and 1 / (2δ _y ) in the y-axis direction.

  With this arrangement relationship, when parallel light 80 having a predetermined wavelength is incident from the front of the computer generated hologram 60, diffracted light 81 is generated on the back side of the computer generated hologram 60, and the pattern recorded on the computer generated hologram 60 in the distant image area 70. Is played.

Here, for easy understanding, the amplitude distribution (pixel value) of the original image on the reproduced image plane 70 is A _IMG (x, y), and the phase distribution of the original image on the reproduced image plane 70 is φ _IMG (x, y), The amplitude distribution on the hologram surface 60 is A _HOLO (u, v), and the phase distribution on the hologram surface 60 is φ _HOLO (u, v). As shown in FIG. 12, in step 201, the pixel value of the original image to be recorded is given as A _IMG (x, y) in the reproduction image plane 70 region, and the phase distribution of the original image is initialized to a random value. The Fourier transform is applied to the initialized value. In step 203, the constraint condition that the amplitude distribution A _HOLO (u, v) on the hologram surface 60 obtained by Fourier transform is set to 1 and the phase distribution φ _HOLO (u, v) is multi-valued (quantized) in a predetermined manner. Is granted. After such a constraint condition is given, in step 204, an inverse Fourier transform is performed on the amplitude distribution A _HOLO (u, v) and the phase distribution φ _HOLO to which the constraint condition is given. When it is determined in step 205 that the amplitude distribution A _IMG (x, y) on the reproduced image plane 70 obtained by the inverse Fourier transform is substantially equal to the pixel value of the original image, the multivalue conversion (step 203) The quantized phase distribution φ _HOLO (u, v) is the phase distribution given to the cell 61 of the computer _generated hologram 60. If it is determined in step 205 that the amplitude distribution A _IMG (x, y) obtained by the inverse Fourier transform is not equal to the pixel value of the original image, the amplitude obtained by the inverse Fourier transform is obtained in step 206. Instead of the distribution A _IMG (x, y), a constraint condition is given in which the pixel value of the original image is given and the phase distribution φ _IMG (x, y) obtained by inverse Fourier transform is left as it is. After such a binding condition is applied, the loop of step 202 → 203 → 204 → 205 → 206 is repeated until the condition of step 205 is satisfied (until convergence), and the final desired computer generated hologram 60 is obtained. can get.

It should be _noted that the processing for multileveling the phase distribution φ _HOLO (u, v) in step 203 may not be performed, and the predetermined multilevel processing may be performed after the condition in step 205 is satisfied.

The actual hologram depth distribution is obtained from the multivalued phase distribution φ _HOLO (u, v) obtained in this way. The phase distribution φ _HOLO (u, v) is converted into the depth D (u, v) of the computer _generated hologram 60 based on the following equation (1).

D (u, v) = λφ _HOLO (u, v) / {2π (n ₁ −n ₀ )} (1)
Here, λ is a use center wavelength, and n ₁ and n ₀ are refractive indexes of two materials constituting the transmission hologram. In the case of the transmission type, as shown in a sectional view in FIG. 13, a computer generated hologram 60 is obtained by forming a relief pattern 83 having a depth of D (u, v) obtained by the above equation (1). In the case of FIG. 13, φ _HOLO (u, v) is an example of multi-leveling in four stages of 0, π / 2, π, and 3π / 2. The coordinates (u, v) on the hologram surface 60 are for distinction from the coordinates (x, y) on the reproduced image plane 70. As the direction of the coordinate axis, the u-axis direction is the x axis. Direction, the v-axis direction corresponds to the y-axis direction.
US Pat. No. 5,546,198 Japanese Patent Laid-Open No. 10-153943 Textbook "Holograms and diffractive optical elements-from basic theory to industrial application" sponsored by The Optical Society of Japan (Applied Physics Society) pp. 36-39 Junpei Kajiuchi, “Physics Selections 22. Holography” pp. 33-36 (published by Hankabo Co., Ltd. (November 5, 1997))

  However, the conventional blindfold device proposed so far is not optically designed but has a single purpose so that a transparent background cannot be clearly seen. Many of them look mediocre and uninteresting. Also, optical information transmission was impossible.

  In addition, in a device that converts a point light source into a desired pattern using a hologram in a blindfold device, it is extremely difficult to increase the size, so that a large size has not been created and a manufacturing method has not been established.

  The present invention has been made in view of such problems of the prior art, and the purpose thereof is optically, has a design property, is visually interesting, and enables transmission of optical information. To provide a blindfold device applicable to various uses and a method of manufacturing the blindfold device.

The blindfolding apparatus of the present invention solves the above-mentioned problem, and blinds the background transmitted through when viewed from the light source side by making the diffraction efficiency of the 0th-order light 30% or less so as not to be seen clearly. At the same time, when the point light source on the light source side is seen through from the side opposite to the light source and when the point light source on the side opposite to the light source is seen through from the light source side, it is converted into a desired pattern. one relief Fourier transform hologram, characterized by using the.

  Further, the Fourier transform hologram is configured as a phase-type computer generated hologram.

  The Fourier transform hologram is affixed to a window.

  Further, the Fourier transform hologram is sandwiched between windows constituted by two transparent plates.

  Further, the Fourier transform hologram is a slide type capable of covering a window so as to freely enter and exit.

  Further, the Fourier transform hologram is a roll screen type capable of covering a window so as to freely enter and exit.

  Further, the Fourier transform hologram has a pitch of 20 μm or less.

Furthermore, the present invention is a method for solving the above-mentioned problems, and by concealing the background transmitted through when viewed from the light source side by making the diffraction efficiency of 0th-order light 30% or less , it is blinded. When the point light source on the light source side is seen through from the side opposite to the light source and when the point light source on the side opposite to the light source is seen through from the light source side, it is converted into a desired pattern 1 A method for manufacturing a blindfolding device using a relief-type Fourier transform hologram , wherein the Fourier transform hologram is produced by duplication using an original stamper.

Moreover, a side opposite to the light source with the point light source of the light source side blindfolded as background passes is not visible clearly when viewed from the light source side by the diffraction efficiency of 0-order light to 30% or less Blindfolding device using one relief-type Fourier transform hologram that converts a point light source opposite to the light source into a desired pattern when viewed from the light source side. The Fourier transform hologram is manufactured by replicating an original plate on a UV resin.

Moreover, a side opposite to the light source with the point light source of the light source side blindfolded as background passes is not visible clearly when viewed from the light source side by the diffraction efficiency of 0-order light to 30% or less Blindfolding device using one relief-type Fourier transform hologram that converts a point light source opposite to the light source into a desired pattern when viewed from the light source side. The Fourier transform hologram is manufactured by exposing a Fourier transform image obtained by Fourier transforming an original image in a step-and-repeat manner.

According to the blindfold device of the present invention, the diffraction efficiency of 0th-order light is set to 30% or less so that the transmitted background is not clearly seen when viewed from the light source side, and the point light source on the light source side is provided. Relief type Fourier transform that transforms into a desired pattern when viewed from the opposite side of the light source and when viewed from the point light source opposite to the light source from the light source side holograms, so using, optically, comprising a design property, there are interesting visually, also enables the transmission of optical information.

Further, the present invention conceals the background transmitted through when viewed from the light source side by making the diffraction efficiency of the 0th-order light 30% or less, and the point light source on the light source side is the light source. A relief-type Fourier transform hologram that is converted into a desired pattern when viewed from the side opposite to the light source and when viewed from the point light source opposite to the light source from the light source side , The method of manufacturing a blindfolding apparatus, wherein the Fourier transform hologram is duplicated using a stamper of the original, the original is duplicated on a UV resin, or the Fourier transform image obtained by Fourier transforming the original is exposed in a step-and-repeat manner. Therefore, a large-scale blindfold device can be created, and the application can be expanded and applied to various devices.

  FIG. 1 is a diagram showing an embodiment of a blindfold device of the present invention. In FIG. 1, 1 is a hologram, 2 is a base material, 3 is an adhesive layer, 4 is a window glass, I is indoors, O is outdoor, M1 is a person in a room constituting a shielding object, Z is a person and a hologram The distance, θ, is the diffraction angle. Usually, the blindfold device is composed of a hologram 1 and a base material 2 and is attached to the window glass 4 with an adhesive layer 3 and used to prevent the indoor person M1 from being clearly seen from the outdoor O.

  In this embodiment, the hologram 1 is a phase type Fourier transform hologram. The Fourier transform hologram may be a computer generated hologram, or may be a surface relief type, an amplitude type, or a volume type. In the volume hologram, the blinding angle can be controlled by the angle selectivity. Furthermore, the Fourier transform hologram may be configured using a spatial modulator such as a liquid crystal so that the degree of blinding can be controlled entirely or partially. Further, it may be a Fourier transform hologram in which the diffraction efficiency of zero-order light (non-diffracted light) is 30%, preferably 10% or less.

When the room is viewed from the outdoor O of the window glass 4 through the blindfold device 1, if Z is the distance between the person M1 to be shielded and the hologram 1 and θ is the diffraction angle, images in the range of 2Z tan θ are mixed and clear. Become invisible. In the present embodiment, assuming a person sitting in a restaurant or the like, the distance Z between the person M1 in the room and the hologram 1 is set to 500 mm. Further, assuming that human eyes cannot be recognized if images of human eyes are mixed, the size of human eyes is set to about 30 mm, and 2Z tan θ is set to 30 mm. Then, 2 × 500 mm × tan θ = 30 mm, and θ = arctan (30/2/500) = 1.718 degrees. Here, when the pitch when the hologram 1 is configured as a computer generated hologram is d, when d = λ / sin θ and λ = 600 nm (λ is a wavelength), d = 600 nm / sin 1.718 degree = about 20 μm. That is, the cell of the hologram 1 has a pitch of about 20 μm or less. The base material 2 should just be transparent members, such as PET and a polycarbonate. Moreover, the adhesion layer 3 and the window glass 4 should just be a transparent member.

  FIG. 2 shows a view when the point light source L is viewed through the blindfold device of the present embodiment. L1 is an indoor point light source, L2 is an outdoor point light source, IMG1 is an indoor pattern, IMG2 is an outdoor pattern, and M2 is a person outdoors. First, as described with reference to FIG. 1, the person M1 who is indoors cannot be recognized from the person M2 who is outdoors. Next, when a person M2 who is outdoors looks at the indoor point light source L1, the indoor pattern IMG1 is observed to emerge along with the indoor point light source L1. In addition, when the person M1 in the room looks at the outdoor point light source L2, the outdoor pattern IMG2 is observed to emerge along with the outdoor point light source L2.

  In addition, the hologram 1 may be configured so that the glass window 4 is configured by two transparent plates and is sandwiched between them to facilitate attachment. Furthermore, the hologram 1 may be used only when necessary by using a slide type or a roll screen type that can cover the window so as to freely enter and exit. In that case, you may enable it to store in a wall.

  Further, the pitch d of the hologram 1 can be changed depending on where the unrecognizable position is set, and it is not only a window that separates the room from the outside, but also vehicles such as vehicles, trains, aircraft, ships, partitions, show windows, etc. You may make it adaptable to various places. In particular, when the pitch is 20 μm or less, the window is optimal for restaurants, vehicles, and the like. When applied to a vehicle, the vehicle may be provided with a point light source.

  Hereinafter, with reference to the drawings, a method of manufacturing the hologram 1 used in the blindfold device of the present invention will be described. FIG. 3 is a diagram showing steps for carrying out the method for producing a hologram original plate according to the present invention. 5 is an original image, 6 is a Fourier transform image, 7 is a substrate, 8 is a chromium layer, 9 is a photoresist, and 10 is an original. The substrate 7 is glass or a silicon original plate.

  First, in step (1), the original image 5 is created. Next, in step (2), the Fourier transform image 6 of the original image 5 is created by calculation such as FFT with a computer. The Fourier transform image 6 is a Fourier transform image 6 that is multi-valued into two or more values. Next, in step (3), electron beam drawing exposure, mask exposure, or the like is performed on the substrate 7 on which the chromium layer 8 and the photoresist 9 are laminated, and a latent image of the uneven pattern is formed on the photoresist 9. Next, in step (4), the latent image of the photoresist is positively developed. Next, in step (5), the chromium layer 8 is etched by wet etching in accordance with the photoresist pattern to remove excess chromium. Subsequently, in step (6), the substrate 7 is etched by a predetermined depth by dry etching and removed. Next, in step (7), the remaining photoresist 9 is stripped.

  Next, in step (8), a photoresist 9 is applied again on the entire surface. Next, in step (9), electron beam drawing exposure and mask exposure are performed, and development is performed in step (10). Subsequently, in step (11), the chromium layer 8 is etched by wet etching in accordance with the photoresist pattern. Next, in step (12), the substrate 7 is etched by dry etching. At this time, the etching is carried out only for half the depth of the etching performed in step (6). Subsequently, in step (13), the remaining photoresist is stripped, and in step (14), all the remaining chromium is removed. By performing such processing, the original plate 10 is obtained.

  4 to 7 are diagrams showing a method for producing a Fourier transform hologram of the present invention. 4 and 5 show a case where a stamper is used as the first embodiment. FIG. 4 is a diagram illustrating a process of manufacturing a stamper. 10 is an original plate, 11 is a conductive film, and 12 is a stamper. First, in step (15a), the conductive film 11 is deposited on the original plate 10 obtained in step (14). Next, in step (16a), nickel plating (electroforming) is performed, and in step (17a), the original plate 10 is peeled off to form a mold as the stamper 12.

  Next, FIG. 5 shows a process of enlarging the Fourier transform hologram with the stamper created in FIG. 12 is a stamper, and 13 is a thermoplastic resin. In step (18a), the stamper 12 created in step (17a) is used to press stamp the thermoplastic resin 13, and the thermoplastic resin 13 is conveyed by the width of the stamper 12 and stopped. In step (19a), a separate stamp is applied to the portion adjacent to the portion stamped in step (18a) of the thermoplastic resin 13, and the thermoplastic resin 13 is conveyed again by the width of the stamper 12 and stopped. By repeating this, the size can be increased.

  6 and 7 show a case where the UV replication original plate as the second embodiment is used. FIG. 6 is a diagram showing a process of creating a UV replication original plate. 10 is an original plate, 14 is a substrate for a replication original plate, 15 is a UV curable resin, and 16 is a UV replication original plate. First, in step (15b), the UV curable resin 15 is applied to the original plate 10 obtained in step (14), and the replica original substrate 14 is pressed thereon. The replica original substrate 14 uses a PET film or a polycarbonate film. Next, in step (16b), UV irradiation is performed to cure the UV curable resin 15. Subsequently, in step (17b), when the original 10 is peeled off, the UV replication original 16 is formed.

  Next, FIG. 7 shows a process of enlarging the Fourier transform hologram with the UV replication original plate 16 created in FIG. 16 is a UV replication original plate, 17 is an embossing roller, 18 is a substrate coated with a UV curable resin, and 19 is a UV irradiation apparatus. In step (18 b), the UV replication original plate 16 created in step (17 b) is arranged around the embossing roller 17. Subsequently, in step (19b), the substrate 18 coated with the UV curable resin is sandwiched between the embossing roller 17 around which the UV replication original plate 16 is disposed and the other roller provided below the embossing roller 17, and the embossing is performed. By rotating the roller 17, the base material 18 coated with the UV curable resin is conveyed while an emboss pattern is formed, and is irradiated with UV by a UV irradiation device downstream thereof, cured, and enlarged.

  Next, another embodiment of an increase in size will be described with reference to FIG. FIG. 8 is a diagram showing a step-and-repeat method for directly increasing the size without creating the original plate 10. Reference numeral 20 denotes a large substrate. Step (1) and step (2) are the same steps as those described with reference to FIG. 3, and the Fourier transform image 6 is created. As the UV replication original plate 16, the enlarged Fourier transform hologram obtained in step (19a) of FIG. 5 may be used.

  Next, in step (3-1), the chrome layer 8 and the photoresist 9 are applied to the large substrate 20 in the same manner as in step (3) in FIG. Then, an electron beam drawing exposure, a mask exposure, etc. are performed to form a latent image of a concavo-convex pattern on the photoresist, and then the large substrate 20 is stopped to be conveyed by the width of the Fourier transform image 6. Subsequently, in step (3-2), the large substrate 20 is again subjected to electron beam drawing exposure, mask exposure, and the like to form a latent image of the concavo-convex pattern on the photoresist, and then the large substrate 20 is subjected to Fourier transform image. Stop feeding for the width of 6. By repeating this, the large substrate 20 is exposed.

  Next, the size is increased by applying the steps from step (4) to step (14) shown in FIG. Therefore, a large-scale blindfold device can be created, and the application can be expanded and applied to various things.

The figure which shows embodiment of the blindfold apparatus of this invention The figure which shows the other function which the blindfold device of this invention has The figure which shows the manufacturing method of the original plate of the blindfold apparatus of this invention The figure which shows the manufacturing method of the stamper of this invention The figure which shows the 1st manufacturing method of the enlarged blindfold apparatus of this invention. The figure which shows the manufacturing method of UV replication of this invention The figure which shows the 2nd manufacturing method of the enlarged blindfold apparatus of this invention. The figure which shows the other manufacturing method of the blindfolded apparatus which enlarged the present invention. Figure showing a conventional hologram The figure which shows the manufacturing method of conventional copying A diagram schematically showing a conventional computer generated hologram and the image area reproduced from it The figure which shows the flowchart for obtaining the conventional computer generated hologram Sectional drawing which shows the structural example of the conventional computer hologram

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hologram, 2 ... Base material, 3 ... Adhesive layer, 4 ... Window glass, 5 ... Original image, 6 ... Fourier transform image, 7 ... Substrate, 8 ... Chrome, 9 ... Photoresist, 10 ... Original plate, 11 ... Conductivity Membrane, 12 ... Stamper, 13 ... Thermoplastic resin, 14 ... Substrate for replication master, 15 ... UV curable resin, 16 ... UV replication master, 17 ... Embossing roller, 18 ... Substrate coated with UV curable resin, 19 ... UV Irradiation device, 20 ... large substrate, I ... indoor, O ... outdoor, Z ... distance between person and hologram, .theta .... diffraction angle, L1 ... indoor point light source, L2 ... outdoor point light source, IMG1 ... indoor pattern , IMG2 ... outdoor pattern, M1 ... indoors, M2 ... outdoors

Claims (10)

The diffraction efficiency of 0-order light while blindfolded as background passes when viewed from the light source side is not visible clearly by 30% or less, transmitting a point light source of the light source side from the side opposite to the light source A relief-type Fourier transform hologram for converting into a desired pattern when viewed as a point light source opposite to the light source and viewed from the light source side ,
A blindfolding device characterized by using.   The blindfolding device according to claim 1, wherein the Fourier transform hologram is configured as a phase-type computer generated hologram.   The blindfolding device according to claim 1, wherein the Fourier transform hologram is attached to a window.   The blindfolding device according to claim 1 or 2, wherein the Fourier transform hologram is sandwiched between windows configured by two transparent plates.   The blindfolding device according to any one of claims 1 to 4, wherein the Fourier transform hologram is a slide type capable of covering a window so as to freely enter and exit.   The blindfolding device according to any one of claims 1 to 4, wherein the Fourier transform hologram is a roll screen type capable of covering a window so as to freely enter and exit. The blindfolding device according to any one of claims 2 to 6, wherein the cells of the Fourier transform hologram have a pitch of 20 µm or less. The diffraction efficiency of 0-order light while blindfolded as background passes when viewed from the light source side is not visible clearly by 30% or less, transmitting a point light source of the light source side from the side opposite to the light source A relief-type Fourier transform hologram for converting into a desired pattern when viewed as a point light source opposite to the light source and viewed from the light source side ,
A method of manufacturing a blindfold device using
The method of manufacturing a blindfold device, wherein the Fourier transform hologram is manufactured by duplicating using a stamper of an original plate. When viewed from the light source side by setting the diffraction efficiency of the 0th-order light to 30% or less , the transmitted light background is hidden so that the transmitted background is not clearly visible, and the point light source on the light source side is viewed from the side opposite to the light source. One relief-type Fourier transform hologram that converts to a desired pattern when viewed through and when viewed from the point light source opposite to the light source through the light source ,
A method of manufacturing a blindfold device using
The method of manufacturing a blindfold device, wherein the Fourier transform hologram is produced by replicating an original plate on a UV resin. The diffraction efficiency of 0-order light while blindfolded as background passes when viewed from the light source side is not visible clearly by 30% or less, transmitting a point light source of the light source side from the side opposite to the light source A relief-type Fourier transform hologram for converting into a desired pattern when viewed as a point light source opposite to the light source and viewed from the light source side ,
A method of manufacturing a blindfold device using
The Fourier transform hologram is produced by exposing a Fourier transform image obtained by Fourier transforming an original image in a step-and-repeat manner.

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