JP2008287272A - Holographic stereogram formulating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a holographic stereogram formulating apparatus which improves light utilization efficiency, and by which the noise positioned in an infinitely remote point can be eliminated and a high picture quality holographic stereogram can be produced. <P>SOLUTION: The holographic stereogram printing apparatus includes: a laser light source 31 for emitting a laser light beam; a display device 41 for displaying a picture in association with coordinate positions of a holographic recording medium 30; and an optical system for making object light L4 and reference light L3 incident on the hologram recording medium 30 so as to sequentially form element holograms on the hologram recording medium 30. A rod type light integrator 63 for uniformizing light intensity of the object light L4 and also controlling the parallelism of the object light L4 is positioned at the front stage of the display device, and a lens 70 for uniformizing the light intensity of the object light in a non-parallax direction is positioned at the front stage of the light integrator 63. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a holographic stereogram creating apparatus that creates a holographic stereogram capable of three-dimensionally recognizing a real image or a computer-generated image.

  In the holographic stereogram, a large number of images obtained by sequentially photographing a subject from different observation points are used as original images, and these are converted into strip-like or dot-like elements on a single hologram recording medium by a holographic stereogram creation device. It is created by sequentially recording as a hologram.

  For example, in a holographic stereogram having parallax information only in the horizontal direction, as shown in FIG. 14, a plurality of original images 101a to 101e are obtained by sequentially photographing the subject 100 from different observation points in the horizontal direction. The holographic stereogram is created by sequentially recording these original images 101a to 101e on the hologram recording medium 102 as strip-shaped element holograms by a creating device.

  When this holographic stereogram is viewed with one eye from a certain position, a two-dimensional image that is a collection of image information of a part of each element hologram can be seen. A two-dimensional image that is a collection of image information of another part of the element hologram can be seen. Therefore, when the observer views the holographic stereogram with both eyes, the positions of the left and right eyes are different in the horizontal direction, so that the two-dimensional images captured in these eyes are slightly different. Thereby, the observer feels parallax and recognizes the reproduced image as a three-dimensional image.

  By the way, the holographic stereogram creating apparatus branches a laser light source having good coherence emitted from a laser light source by a half mirror. The holographic stereogram creating apparatus makes one laser beam incident on a photoconductor as a projection image obtained by two-dimensional image modulation by an image display means such as a liquid crystal panel, that is, object light. The holographic stereogram creation apparatus directly enters the photoconductor using the other laser beam as reference light. The holographic stereogram creation device creates a holographic stereogram by recording interference fringes as a change in the refractive index of the photosensitive member using object light and reference light (see, for example, Patent Document 1).

  In a holographic stereogram creation device, it is known that, for example, a diffusion plate is effective in the vicinity of an image display means in order to obtain a high-quality hologram (Non-patent Document 1 and Non-Patent Document 2). See).

Japanese Patent Laid-Open No. 10-20747 Endo, Yamaguchi et al., 1992 23rd Image Optic Conference p317 Michael Klug et al. 1993 Proc SPIE # 1914 Practical Holography VII

  By the way, in the holographic stereogram creating apparatus, there is a problem that uneven noise localized at infinity is observed in the obtained hologram even when the diffusion plate is arranged in the vicinity of the image display means. In the holographic stereogram creation apparatus described in Patent Document 1, the diffusion plate is moved to reduce noise in order to reduce the noise. However, even in such a holographic stereogram creation device, there are problems in terms of vibration resistance when there are many moving mechanisms, and there is also a problem that the light utilization efficiency decreases when a diffusion plate is used. ing.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a holographic stereogram creation device capable of improving light utilization efficiency, eliminating noise localized at infinity, and obtaining a high-quality holographic stereogram.

  A holographic stereogram creation device according to the present invention includes a laser light source that emits laser light, a display device that displays an image corresponding to the coordinate position of the hologram recording medium, and object light and reference light incident on the hologram recording medium. And an optical system for sequentially creating strip-shaped or dot-shaped element holograms. In the holographic stereogram creation device, an optical system splits a laser beam, transmits one laser beam through a display device, modulates an image, and enters the hologram recording medium as an object beam, and transmits the other laser beam. The object light is directly incident on the hologram recording medium as reference light. The holographic stereogram creation device is located in the front stage of the display device in the optical path of the object light, and a rod-type light integrator that equalizes the light intensity of the object light incident on the display device and controls the parallelism. A lens body is provided that is disposed on the object light incident surface side of the light integrator and uniformizes the light intensity in the non-parallax direction of the object light.

  In the holographic stereogram creation device according to the present invention, the light integrator makes the light intensity uniform by guiding the incident laser light to the exit surface while making multiple reflections inside and making it incident on the display device. And parallel to control the parallelism. Therefore, in the holographic stereogram creation device, the element hologram forming portion of the hologram recording medium can be illuminated uniformly, and a holographic stereogram with high uniformity and high diffraction efficiency can be obtained. In the holographic stereogram creation device, the lens body condenses the laser light emitted from the light integrator only in the non-parallax direction and supplies it to the display device. In the holographic stereogram creation device, high-quality holographic stereograms are achieved by reducing the influence of the moire pattern caused by the laser light that causes interference fringe characteristics due to multiple reflection in the light integrator and the pixel pitch of the display device. Get.

  According to the holographic stereogram creation device according to the present invention, by arranging a rod-type light integrator that is combined with a lens body that is positioned in the front stage of the display device and uniformizes the light intensity in the non-parallax direction of the object light, Without using a diffuser or the like, it is possible to optimally control the parallelism of object light, and as a result, it is possible to minimize light that is wasted by a slit or the like. Further, according to the holographic stereogram creating apparatus, the beam use efficiency is also improved in this respect because the beam expansion by the objective lens and the pinhole is unnecessary. According to the holographic stereogram creation device, the light intensity in the non-parallax direction is made uniform by the influence of interference fringes generated in the object light whose light intensity is made uniform and the parallelism is controlled by transmitting through the rod-type light integrator. It is reduced by the action of the lens body. According to the holographic stereogram creation device, it is possible to obtain a high-quality holographic stereogram without being limited by the parameters of the optical system.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the example given below, It is possible to change a structure suitably in the range which does not deviate from the summary.

  First, a configuration example of a holographic stereogram creation system that creates a holographic stereogram (hereinafter abbreviated as a creation system) will be described. The creation system is a creation system that creates a holographic stereogram having horizontal parallax information by recording a plurality of strip-shaped element holograms on the hologram recording surface of one hologram recording medium 30. Take an example. The present invention is directed to a creation system for creating a holographic stereogram having horizontal and vertical parallax information by recording a plurality of dot-shaped element holograms on a single hologram recording medium. It goes without saying that is also applicable.

  The creation system described below is a system for creating a so-called one-step holographic stereogram in which a hologram recording medium in which interference fringes between object light and reference light are recorded is used as it is as a holographic stereogram. As shown in FIG. 1, the creation system includes a data processing unit 1 for processing image data to be recorded, a control computer 2 for controlling the entire system, and an optical system for creating a holographic stereogram. And a holographic stereogram printer device (hereinafter abbreviated as a printer device) 3.

  The creation system uses a plurality of image data D1 including parallax information supplied from a parallax image sequence photographing device 13 including a multi-lens camera, a mobile camera, and the like, and a computer 14 for generating image data. A plurality of image data D2 including the generated parallax information is supplied. In the creation system, the data processing unit 1 generates parallax image sequence data D3 based on the image data D1 and D2.

  Here, the plurality of pieces of image data D1 including the parallax information supplied from the parallax image sequence photographing device 13 is obtained by converting a real object in the horizontal direction by, for example, simultaneous photographing with a multi-lens camera or continuous photographing with a mobile camera. It is image data for a plurality of images obtained by photographing from a plurality of different observation points.

  The plurality of pieces of image data D2 including the disparity information generated by the image data generation computer 14 are, for example, a plurality of CAD (Computer Aided Design) images and CG (Computer Graphics) created by sequentially giving disparity in the horizontal direction. ) Image data such as an image.

  In the creation system, the data processing unit 1 performs predetermined image processing for the holographic stereogram by the image processing computer 11 on the parallax image sequence data D3. The creation system stores image data D4 that has undergone predetermined image processing in a storage device 12 such as a memory or a hard disk.

  In the creation system, when the data processing unit 1 records an element hologram image on a hologram recording medium 30 to be described later, a process of sequentially reading data from the image data D4 stored in the storage device 12 for each element hologram image I do. In the creation system, the data processing unit 1 sends the read image data D5 to the control computer 2.

  In the creation system, the control computer 2 drives the printer device 3 based on the recording operation of the element hologram image. In the creation system, the control computer 2 outputs the image data D5 output from the data processing unit 1 to the printer device 3, and sequentially records images based on the image data D5 as strip-shaped element holograms on the hologram recording medium 30. To control the operation.

  The control computer 2 controls the shutter 32, the display device 41, the recording medium feeding mechanism, and the like provided in the printer device 3. The control computer 2 controls the opening / closing operation of the shutter 32 by sending a control signal S 1 to the shutter 32. The control computer 2 supplies the display device 41 with the image data D5, thereby causing the display device 41 to display an image based on the image data D5. The control computer 2 controls the feeding operation of the hologram recording medium 30 by the recording medium feeding mechanism by sending a control signal S2 to the recording medium feeding mechanism.

  The optical system of the printer apparatus 3 will be described in detail with reference to FIG. FIG. 2 is a view of the optical system of the printer apparatus 3 as viewed from above. As shown in FIG. 2, the printer apparatus 3 includes a laser light source 31 that emits laser light L1 having a predetermined wavelength, a shutter 32 and a half mirror disposed on the optical axis of the laser light L1 emitted from the laser light source 31. 33. The printer device 3 uses, for example, a YAG laser having a wavelength of 532 nm and an output of 400 mW as the laser light source 31.

  The shutter 32 is controlled to open and close by the control computer 2 and is closed when the hologram recording medium 30 is not exposed to shut off the laser light L1, and is opened when the hologram recording medium 30 is exposed to emit the laser light L1. Let it pass. The half mirror 33 is for branching the laser light L2 that has passed through the shutter 32 into reference light and object light. The laser light L3 reflected by the half mirror 33 becomes reference light, and the half mirror 33 is The transmitted laser light L4 becomes object light.

  The printer device 3 is reflected by the half mirror 33 in the optical system described above and is incident on the hologram recording medium 30 through the optical path length of the reference light L3 that is incident on the hologram recording medium 30 and the half mirror 33. The difference from the optical path length of the object light L4 is set to be equal to or less than the coherent length of the laser light source 31. Thus, the printer device 3 can create a holographic stereogram in which the coherence between the reference light L3 and the object light L4 is enhanced and a clear reproduced image can be obtained.

  The printer device 3 is provided with an optical system for reference light on the optical axis of the reference light L3 reflected by the half mirror 33. The reference light optical system includes a cylindrical lens 34, a collimator lens 35 for making the reference light L3 parallel light, a total reflection mirror 36 that reflects the parallel light transmitted through the collimator lens 35 and guides it to the hologram recording medium 30. Are arranged in this order.

  The printer device 3 is provided with an optical system for object light on the optical axis of the object light L4 transmitted through the half mirror 33. The object light optical system is roughly composed of an image illumination optical system 50 and an image projection optical system 51.

  The image projection optical system 51 is shown in FIG. 3A is a view of the image projection optical system 51 as viewed from above, that is, from the parallax direction (short axis direction of the element hologram), and FIG. 3B is a view of the image projection optical system 51. It is the figure seen from the side, ie, the non-parallax direction (major axis direction of an element hologram).

  As shown in FIG. 3, the image projection optical system 51 includes a projection lens 42 disposed on the optical axis of the object light L4 between the display device 41 and the hologram recording medium 30, a slit body 43, and a projection lens. 44, a cylindrical lens 45, and a one-dimensional diffusion plate 46. As shown in FIG. 3A, the image projection optical system 51 forms an image on the display device 41 on the hologram recording surface of the hologram recording medium 30 by the projection lenses 42 and 44 in the non-parallax direction.

  Further, the image projection optical system 51 causes the cylindrical lens 45 to focus the entire light beam on the hologram recording surface of the hologram recording medium 30 in the parallax direction as shown in FIG. The image projecting optical system 51 plays a role in that the slit body 43 in which a slit having a predetermined opening size is formed prevents the object light L4 from protruding from the element hologram to expose the adjacent element hologram forming portion. In the image projection optical system 51, the main surface of the slit body 43 and the hologram recording surface of the hologram recording medium 30 are in an imaging relationship by the projection lens 44 and the cylindrical lens 45. In the image projection optical system 51, a one-dimensional diffusion plate 46 is disposed between the cylindrical lens 45 and the hologram recording medium 30, and the role of the one-dimensional diffusion plate 46 will be described later.

  The image illumination optical system 50 is characteristic in the present invention, and FIG. 4 shows the first embodiment. The image illumination optical system 50 is disposed between the half mirror 33 and the display device 41, and includes a condenser lens 62, a glass rod 63, a deflection plate 67, and lenses 65 and 66, as shown in FIG. Composed. The optical system 50 for image illumination displays the incident beam 61 (object light L4) emitted from the laser light source 31 and transmitted through the half mirror 33 by uniformizing the light intensity and controlling the parallelism as will be described later. 41 is supplied.

  In the image illumination optical system 50, the glass rod 63 constitutes a rod-type light integrator, and the incident beam 61 condensed by the condenser lens 62 is incident thereon. In the optical system 50 for image illumination, the glass rod 63 guides the incident beam 61 incident to the exit surface 64 while performing multiple reflection inside. In the image illumination optical system 50, the glass rod 63 adds the light from various directions in a state where the incident beam 61 is guided to the emission surface 64 so that the light intensity becomes uniform.

  In the image illumination optical system 50, the lens 65 and the lens 66 enlarge and project the emission surface 64 of the glass rod 63 onto the display device 41. The projection magnification A at this time is given by the ratio of the focal lengths of the lens 65 and the lens 66. In the image illumination optical system 50, a polarizing plate 67 is disposed in the optical path so as to oppose the emission surface 64 of the glass rod 63 in order to correct the rotation of the polarization plane due to multiple reflection in the glass rod 63.

  The image illumination optical system 50 can be provided with a rod-type light integrator such as the glass rod 63 described above to widen the incident beam 61 and make the light intensity uniform. The parallelism of 61 can also be controlled. In the optical system 50 for image illumination, a rod-type light integrator such as a glass rod 63 plays an important role for improving the quality of the holographic stereogram.

Here, the parallelism required for the illumination light of the display device 41 is determined by the focal lengths of the slit body 43 and the lens 42, as can be seen from FIG. That is, if the focal length of the lens 42 is f ₁ , the slit width of the slit body 43 is w, and the optical parallelism is θ _{2.
2 × f 1 × tan (θ} 2/2) = w
It becomes.

As can be seen from FIG.
θ ₁ = A × θ ₂ where A: projection magnification.

  In an optical system using coherent light such as laser light, the light integrator of the incident beam 61 can be made uniform and the parallelism can be controlled by using the light integrator as described above. By the way, this optical system also has the following problems, and a method for solving the problem will be described.

In the image illumination optical system 50, as described above, the incident beam 61 incident on the glass rod 63 constituting the rod-type light integrator causes multiple reflection inside and is guided to the exit surface 64. In the image illumination optical system 50, the incident beam 61 is equivalent to a wavefront generated when light comes from many point light sources on the exit surface 64 as shown in FIG. In the image illuminating optical system 50, an interference fringe similar to the interference fringe in the multiple slits as shown in FIG. 6 is thereby generated.
I≈ {sin (πNWY / Lλ) / sin (πWY / Lλ)} ²
Interference fringes having an intensity distribution represented by As shown in FIG. 7, L is the length of the glass rod 63, and W is the thickness of the glass rod 63. N represents the number of times the light is reflected inside the glass rod 63, λ represents the wavelength of the laser light incident on the glass rod 63, and Y represents the position on the end face 64 of the glass rod 63. Further, it is assumed that the angle θ formed by the optical axis of the laser light reflected inside the glass rod 63, that is, the laser light from the virtual point light source S, and the optical axis of the laser light incident on the glass rod 63 is sufficiently small. is doing.

In consideration of the refractive index of the glass rod 63, the interval d between the interference fringes generated on the exit surface 64 of the glass rod 63 is
d = λ × L / (n × W)
It becomes. However, n is the refractive index of the glass rod 63, and is normally about 1.5.

  The interference fringes generated on the exit surface 64 of the glass rod 63 are projected onto the display device 41 by lenses 65 and 66 as shown in FIG. Therefore, for example, when a liquid crystal panel is used as the display device 41, a moire pattern may occur between the interference fringes generated by the glass rod 63 and the pixels constituting the image displayed on the liquid crystal panel. . This moire pattern tends to appear more prominently when the liquid crystal pixel interval and the interference fringe interval d are close.

  In the image illumination optical system 50, there are a method of avoiding or reducing the generation of the above-described moire pattern, a method of sufficiently narrowing the interference fringe spacing, and a method of not equalizing the light intensity in the parallax direction. Hereinafter, each method will be described.

  First, a method of sufficiently narrowing the interference fringe interval will be described as a first method for countering moire patterns. When the inventor conducted an experiment, if the interference fringe interval is about ½ or less of the pixel pitch of the image displayed on the display device 41, the moire pattern becomes inconspicuous enough for practical use. Furthermore, it was confirmed that the moire pattern is hardly noticeable if it is about 1/3 or less.

Therefore, in the image illumination optical system 50, the interval between the interference fringes generated on the end surface 64 of the glass rod 63 is d, the pixel pitch of the image displayed on the display device 41 is P, and the display device of the end surface 64 of the glass rod 63 is displayed. If the projection magnification to 41 is A,
d × A <P / 2
The parameters of the optical system are set so as to satisfy this condition.

In the image illumination optical system 50, more preferably,
d × A <P / 3
The parameters of the optical system may be set so as to satisfy

Here, the interval d of the interference fringes is as described above.
d = λ × L / (n × W)
It is represented by Therefore, in the image illumination optical system 50, in order to make the interference fringe spacing d sufficiently narrow so that the moire pattern is not noticeable,
λ × L × A / (n × W) <P / 2
It is sufficient that the above condition is satisfied, and more preferably,
λ × L × A / (n × W) <P / 3
It is sufficient to satisfy the above condition.

  The image illumination optical system 50 uses, for example, a liquid crystal panel having a pixel pitch P of about 30 μm as the display device 41, and when W = 8.4 mm, A = 2, λ = 532 nm, and n = 1.5, A glass rod 63 having a length L of about 17 cm or less, more preferably about 12 cm or less may be used from the above-described conditions.

  That is, in the image illumination optical system 50, if the length L of the glass rod 63 is about 17 cm or less under the above conditions, the distance d × A between the interference fringes projected on the display device 41 is set in the display device 41. It is possible to make it about ½ or less of the pixel pitch of the displayed image. In the image illumination optical system 50, this makes it possible to make the moire pattern inconspicuous to a practically sufficient level.

  Furthermore, in the optical system for image illumination 50, the distance d × A of the interference fringes projected on the display device 41 is set to the display device 41 by setting the length L of the glass rod 63 to about 12 cm or less under the above conditions. It is possible to make it about 1/3 or less of the pixel pitch of the image displayed on the screen. In the image illumination optical system 50, this makes it possible to make the moire pattern almost inconspicuous.

  In the optical system 50 for image illumination, the moire pattern is made inconspicuous by sufficiently narrowing the interference fringe spacing d generated by guiding light by causing multiple reflections in the glass rod 63 as described above. Therefore, the image illumination optical system 50 can create a high-quality holographic stereogram without being adversely affected by the moire pattern.

  By the way, the above-described method of sufficiently reducing the interference fringe spacing d may not be used depending on the conditions of the optical system. Here, an object light optical system in which the image illumination optical system 50 and the image projection optical system 51 are combined is shown in FIG. In FIG. 8 and FIGS. 9 to 12 to be described later, the polarizing plate 67 and the one-dimensional diffusion plate 46 are not shown.

  In the object light optical system, as can be seen from FIG. 8, the focal point of the condensing lens 62 arranged in front of the glass rod 63, the main surface of the slit body 43, and the hologram recording surface of the hologram recording medium 30 are All are conjugate surfaces. Therefore, in the object light optical system, a virtual point light source generated by multiple reflection inside the glass rod 63 also forms an image on the main surface of the slit body 43 and the hologram recording surface of the hologram recording medium 30. For this reason, in the object light optical system, the method of making the moire pattern inconspicuous by sufficiently narrowing the interference fringe interval as described above cannot be applied due to the parameters of the optical system. It may not be possible.

  In the object light optical system, as a second method of countering the moire pattern, the light intensity is not made uniform in the parallax direction of the holographic stereogram in the image illumination optical system 50, whereby a moire pattern is obtained. There is a method for avoiding the occurrence of this, and this method will be described below. This second moire pattern countermeasure method can be applied without depending on the parameters of the optical system. Therefore, in the object light optical system, this second moire pattern countermeasure method is applied to an optical system in which the method of making the moire pattern inconspicuous by sufficiently narrowing the interference fringe spacing d is not applicable. do it.

  The optical system 50 for image illumination shown in FIG. 9 does not uniformize the light intensity in the parallax direction of the holographic stereogram, and uniformizes the light intensity only in the non-parallax direction, thereby generating a moire pattern. It is an example of the optical system for image illumination to which the 2nd method to avoid is applied.

  In the first method described above, when light is introduced into the glass rod 63, a normal rotationally symmetric lens is used as the condensing lens 62 disposed in front of the glass rod 63. On the other hand, in the second method, as shown in FIG. 9, a cylindrical lens that condenses incident light only in the non-parallax direction is used as the condensing lens 62 disposed in the front stage of the glass rod 63.

  In the second method, as described above, a cylindrical lens that condenses incident light only in the non-parallax direction is used as the condensing lens 62 arranged in the preceding stage of the glass rod 63, so that the glass rod 63 is only in the non-parallax direction. Multiple reflections occur inside the light to make the light intensity uniform. In the second method, multiple reflection does not occur in the parallax direction and the light intensity is not uniformed, so that interference fringes are not generated due to multiple reflection inside the glass rod 63. Accordingly, the image illumination optical system 50 can avoid the generation of the moire pattern by adopting the second method and supplying the object light L4 to the display device 41.

  In the image illumination optical system 50, when the second method is applied to avoid the generation of the moire pattern, the holographic stereogram created is not obtained because the light intensity is not made uniform in the parallax direction. When observation is performed with an angle in the parallax direction, the brightness may slightly change. However, holographic stereograms usually do not care much about unevenness of brightness in this direction, so there are few problems caused by not performing homogenization.

  Next, a second embodiment of the image illumination optical system 50 will be described with reference to FIGS. In the optical system 50 for image illumination mentioned as the second embodiment, as shown in FIG. 10, the condensing lens in the first embodiment shown in FIG. Instead of 62, a lenticular lens 70 is used. As is well known, the lenticular lens 70 is a lens whose surface has a number of kamaboko-shaped irregularities.

  The optical system for image illumination 50 constitutes a light integrator by combining a glass rod 63 with a lenticular lens 70. The image illuminating optical system 50 arranges the lenticular lens 70 so as to have refractive power in the non-parallax direction, thereby achieving uniform light intensity in the non-parallax direction. The image illumination optical system 50 uses the lenticular lens 70 as a lens arranged in front of the glass rod 63 as described above, so that the interference fringes due to the virtual point light source as described in the first embodiment are conspicuous. There is an advantage that it is difficult.

  In addition, when the image illumination optical system 50 uses the lenticular lens 70 as a lens disposed in front of the glass rod 63, as shown in FIG. 11, a pair of lenticular lenses 70a and 70b are arranged in a condensing direction. You may make it arrange | position so that it may orthogonally cross. That is, the image illumination optical system 50 includes a lenticular lens 70b having a refractive power in the non-parallax direction as shown in FIG. 11A and a lenticular lens having a refractive power in the parallax direction as shown in FIG. 11B. 70a is combined and disposed in front of the glass rod 63.

  The optical system 50 for image illumination uses the pair of lenticular lenses 70a and 70b as lenses arranged in front of the glass rod 63 as described above, thereby making the light intensity in the non-parallax direction uniform and the light intensity in the parallax direction. It is possible to perform both of the homogenization. The image illumination optical system 50 has an advantage that interference fringes due to the virtual point light source as described in the first embodiment are not noticeable. In the image illumination optical system 50, interference may occur even when both the light intensity in the non-parallax direction and the light intensity in the parallax direction are made uniform by using the pair of lenticular lenses 70 a and 70 b. It is possible to avoid the generation of moire patterns with almost no stripes.

  The image illumination optical system 50 is preferably set independently so that the refractive power of the pair of lenticular lenses 70a and 70b is an optimum value determined by the optical system. The optical system 50 for image illumination includes the refractive power of the lenticular lens 70a (refractive power in the parallax direction, that is, the refractive power in the minor axis direction of the element hologram) and the refractive power of the lenticular lens 70b (refractive power in the non-parallax direction, that is, element). The refractive power in the major axis direction of the hologram is different, and each refractive power is set to an optimum value determined by the optical system.

  FIG. 12 shows a specific example of the object light optical system of the printer apparatus in which the second embodiment is applied to the image illumination optical system 50 as described above. 12A is a view of the object light optical system as viewed from above, that is, from the parallax direction (short axis direction of the element hologram), and FIG. FIG. 5 is a diagram viewed from the non-parallax direction (the major axis direction of the element hologram). FIG. 12 also shows specific numerical examples of optical system parameters.

  In such an object light optical system, as shown in FIG. 12A, when the laser light passes through the lenticular lens 70b, the luminous flux has a spread angle in the non-parallax direction as described above. . In the object light optical system, the spread angle in the non-parallax direction generated by the laser light passing through the lenticular lens 70b has a greater degree of freedom than the spread angle in the parallax direction, and may have a considerably large spread angle. . As a result of actual experiments by the present inventor, the non-parallax direction has a result that the uniformity is improved as a whole when the divergence angle by the lenticular lens 70b is set to 20 ° or more.

  Therefore, in the object light optical system, for example, a lenticular lens 70b having a lens pitch of 200 μm and a spread angle of 40 ° is used. In the object light optical system, the light intensity is made uniform in the non-parallax direction, and a holographic stereogram with excellent image quality can be created.

  In the object light optical system, as shown in FIG. 12B, the laser beam passes through the lenticular lens 70a, so that the light beam has a spread angle in the parallax direction. In the object light optical system, the spread angle in the parallax direction generated by the laser light passing through the lenticular lens 70a is determined by the width of the element hologram formed on the hologram recording medium 30 and the parameters of this optical system. it can.

For example, when the width of the element hologram formed on the hologram recording medium 30 is set to 0.2 mm, the object light optical system is configured such that the focal length f of the projection lens 44 is 80 mm and the focal length f of the cylindrical lens 45 is 8.4 mm. The slit width of the body 43 needs to be 0.2 × 80 / 8.4≈1.905 mm. Further, in the object light optical system, when the focal length f of the projection lens 42 is 80 mm, in order to uniformly diffuse light into the slit portion of the slit body 43, the illumination light incident on the display device 41 is tan ⁻¹ (1.905 / 80) ≈1.364 ° needs to be spread. Here, the projection magnification A onto the display device 41 of the end face 64 of the glass rod 63 is A = 10. Therefore, the spread angle in the parallax direction by the lenticular lens 70a is theoretically preferably about 13.64 °.

  In the object light optical system, if the spread angle in the parallax direction by the lenticular lens 70a is too larger than the calculated theoretical value described above, the light emitted from the slit body 43 increases and the light use efficiency deteriorates. On the other hand, if the divergence angle of the object light optical system is too small than the theoretical value, light is not uniformly applied to the element hologram forming portion and the image quality of the holographic stereogram is lowered. Therefore, it is preferable to use the object light optical system as the lenticular lens 70a having a divergence angle in the parallax direction as close to the theoretical value as possible.

  However, since there is actually an influence of aberrations, it does not have to be exactly the theoretical value. When the present inventor actually created a holographic stereogram using a lens pitch of 200 μm and a focal length of about 1 mm as the lenticular lens 70a under the above conditions, sufficient light utilization efficiency and sufficient It was confirmed that it was possible to achieve both good image quality.

  In the above example, the pair of lenticular lenses 70 a and 70 b are disposed in front of the glass rod 63, but a fly-eye lens is disposed in front of the glass rod 63 instead of these lenticular lenses 70 a and 70 b. May be. That is, the object light optical system may be configured as a light integrator by combining the fly-eye lens and the glass rod 63.

  In the object light optical system, when a light integrator is configured by combining a fly-eye lens and a glass rod 63, the light intensity in the non-parallax direction is made uniform as in the case of using the pair of lenticular lenses 70a and 70b. It is possible to perform both of uniforming the light intensity in the parallax direction. However, when the light integrator is configured by combining the fly-eye lens and the glass rod 63, a fly-eye lens having a predetermined refractive power characteristic is selected as the object light optical system. In the optical system for object light, the fly-eye lens determines the refractive power in the major axis direction of the element hologram and the refractive power in the minor axis direction of the element hologram, and the refractive power in each direction is determined by the optical system. An optimum value is preferable.

  In the object light optical system, even when the light integrator is configured by combining the lenticular lens 70 and the glass rod 63, or when the light integrator is configured by combining the fly-eye lens and the glass rod 63, the It is preferable to dispose a polarizing plate in the subsequent stage. In the object light optical system, by arranging a polarizing plate after the glass rod 63, it is possible to correct the rotation of the polarization plane due to multiple reflection inside the glass rod 63 and to align the polarization plane of the luminous flux. .

  The image illumination optical system 50 and the image projection optical system 51 constituting the object light optical system described above are characteristic optical systems in the present invention. The object light optical system guides the laser light having a uniform in-plane distribution of light intensity to the hologram recording medium 30 by passing through the image illumination optical system 50 and the image projection optical system 51. Then, the element hologram is exposed on the hologram recording surface. The exposure of the hologram recording medium 30 will be described again with reference to FIG.

  In a printer device that creates a reflection-type holographic stereogram, a one-dimensional diffusion plate is generally disposed immediately before the hologram recording medium 30. In this example, the one-dimensional diffusion plate is disposed immediately before the hologram recording medium 30. 46 is arranged. This one-dimensional diffuser plate 46 is used to ensure a vertical (vertical) viewing angle by one-dimensionally diffusing the condensed object light L4 in the longitudinal direction of the strip-shaped element hologram. is there.

  The one-dimensional diffusion plate 46 can be fixed, but is moved with respect to the hologram recording medium 30 every exposure of each element hologram in order to eliminate noise localized on the hologram recording surface. It may be. In the printer device 3, when the one-dimensional diffuser plate 46 is moved, it is preferably moved in the major axis direction of the strip-shaped element hologram in order to eliminate streaks generated in the parallax direction of the holographic stereogram.

  The display device 41 is a transmissive image display device made of, for example, a liquid crystal panel, and is controlled by the control computer 2 to display an image based on the image data D5 sent from the control computer 2. When the present inventor actually created a holographic stereogram, a monochrome liquid crystal panel having a pixel number of 480 × 1068 and a size of 16.8 mm × 29.9 mm was used as the display device 41.

  The printer device 3 projects the image displayed on the display device 41 onto the hologram recording surface of the hologram recording medium 30 by the image projection optical system 51. The printer device 3 simultaneously irradiates the hologram recording medium 30 with the projection light (that is, the object light L4) and the reference light L3, so that the interference fringes of these laser beams are formed into a strip-shaped element hologram on the hologram recording medium 30. To be recorded.

  The printer device 3 sequentially records the above-described strip-shaped element holograms on the hologram recording medium 30 for each image constituting the parallax image sequence data D3. The printer device 3 uses the recording medium feed mechanism to transfer the hologram recording medium 30 to the one-element hologram every time the exposure of the one-element hologram is completed so that the element holograms corresponding to the images constituting the parallax image string data D3 are arranged in the parallax direction. Move it every minute. Thus, the printer device 3 creates a holographic stereogram formed by sequentially forming element holograms on the hologram recording medium 30.

  Although specific embodiments to which the present invention is applied have been described above, the present invention is not limited to the above examples, and various modifications can be made.

  For example, in the above-described creation system, a holographic stereogram having only a horizontal parallax, that is, a creation system of a holographic stereogram having a strip-shaped element hologram has been described. The present invention can also be applied to a system for producing a holographic stereogram having a rectangular or circular dot-shaped element hologram and having both vertical and horizontal parallaxes.

  In the above-described creation system, the reflection type holographic stereogram has been described as an example. However, the present invention can be similarly applied to a transmission type holographic stereogram and an edge-lit type holographic stereogram. it can.

  In the above-described production system, a lens body (lens 62, lenticular lens 70, lenticular lenses 70a and 70b) for condensing and entering laser light to the glass rod 63 is fixed on the optical path. Explained as a thing. In the present invention, these lens bodies may be moved each time an element hologram is recorded on the hologram recording medium 30 as in the case of the one-dimensional diffusion plate 46. The creation system can reduce noise localized at infinity when a holographic stereogram is created by adopting such a configuration.

  In the above-described production system, an example in which the glass rod 63 is used as the light integrator has been described. However, it is obvious that the same effect can be obtained even if another light integrator is used. Examples of other light integrators include a light integrator using a fly-eye lens.

  A light integrator using a fly-eye lens is often used for uniforming the light intensity of, for example, a stepper that is a semiconductor exposure apparatus, and is disposed facing the optical axis as shown in FIG. A pair of fly-eye lenses 81 and 82 is provided. In such a fly-eye light integrator, an incident beam 80 is first incident on a fly-eye lens 81, and then an image of the fly-eye lens 81 is formed by another fly-eye lens 82.

  In the fly-eye light integrator, by changing the constants of the fly-eye lens 81 and the fly-eye lens 82, images of a plurality of lenses of the fly-eye lens 81 are displayed on the illuminated object 83 as shown in FIG. Can be projected on top of each other. In the fly-eye light integrator, the beams are overlapped in this way, so that the non-uniformity of the incident beam 80 can be eliminated and the light intensity can be made uniform.

  In the above-described creation system, the case where a single color holographic stereogram is created using one laser beam has been described. However, a color holographic stereogram is created using three primary color laser beams. In this case, the present invention can be similarly applied. When the present invention is applied, the light use efficiency can be increased, so that a realistic color hologram printer can be created using three small lasers.

It is a figure showing an example of 1 composition of a holographic stereogram creation system. It is a figure which shows an example of the optical system of a holographic stereogram printer apparatus. It is a figure which shows an example of the optical system for image projection. It is a figure which shows an example of the optical system for image illumination. It is a figure which shows the mode of the multiple reflection in a glass rod. It is a figure which shows the principle of the interference fringe generation | occurrence | production by a multiple slit. It is a figure which shows the virtual point light source produced by the multiple reflection in a glass rod and a glass rod. It is a figure which shows an example of the optical system for image illumination, and the optical system for image projection. It is a figure which shows an example of the optical system for image illumination in the case of avoiding generation | occurrence | production of a moire pattern by equalizing light intensity only in a non-parallax direction. It is a figure which shows an example of the optical system for image illumination which used the lenticular lens as a lens arrange | positioned in the front | former stage of a glass rod. It is a figure which shows an example of the optical system for image illumination which used a pair of lenticular lens as a lens arrange | positioned in the front | former stage of a glass rod. It is a figure which shows the specific example of the optical system for object light which used a pair of lenticular lens as a lens arrange | positioned in the front | former stage of a glass rod. It is a figure which shows the structure of a fly eye type | mold light integrator. It is a schematic diagram which shows the preparation method of a holographic stereogram.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Data processing part, 2 Control computer, 3 Holographic stereogram printer apparatus (printer apparatus), 30 Hologram recording medium, 31 Laser light source, 32 Shutter, 33 Half mirror, 34 Cylindrical lens, 35 Collimator lens, 36 Total reflection mirror , 41 Display device, 42 Projection lens, 43 Slit body, 44 Projection lens, 45 Cylindrical lens, 46 One-dimensional diffuser plate, 50 Image illumination optical system, 51 Image projection optical system, 62 Condensing lens, 63 Glass rod ( Rod-type light integrator), 64 exit surface, 65 lens, 66 lens, 67 deflecting plate, 70 lenticular lens, 81 fly eye lens

Claims (6)

A laser light source for emitting laser light;
A display device for displaying an image corresponding to the coordinate position of the hologram recording medium;
The laser beam is branched, one laser beam is transmitted through the display device, image-modulated and incident on the hologram recording medium as object light, and the other laser beam is used as reference light and the hologram simultaneously with the object light. An optical system that sequentially records strip-shaped or dot-shaped element holograms on the hologram recording medium by being incident on the recording medium;
Located in the front stage of the display device in the optical path of the object light,
A rod-type light integrator that equalizes the light intensity of the object light incident on the display device and controls parallelism;
A holographic stereogram creation device provided with a lens body that is arranged on the object light incident surface side of the light integrator and uniformizes the light intensity in the non-parallax direction of the object light.   The holographic stereogram creation device according to claim 1, wherein the lens body is a cylindrical lens that collects the object light only in a non-parallax direction.   The holographic stereogram creation device according to claim 1, wherein the lens body is a lenticular lens having refractive power in a non-parallax direction.   2. The holographic stereogram creation according to claim 1, wherein the lens body is a lenticular lens formed by combining a first lenticular lens having a refractive power in a non-parallax direction and a second lenticular lens having a refractive power in a parallax direction. apparatus.   The holographic stereogram creation device according to claim 4, wherein the first lenticular lens and the second lenticular lens have different refractive powers.   The holographic stereogram creation device according to claim 1, wherein the lens body is a fly-eye lens.

Images