JP2007256343A - Holographic three dimensional hard copy producing method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decrease the number of times of movement of a photosensitive material during hologram photography for a holographic three dimensional hard copy and the number of times of holding for a certain time until vibrations generated after the movement converge. <P>SOLUTION: Parallel light is modulated by a spatial modulating element 17 having a regular array and converged by a lens to generate diffracted light of high order with high intensity. The diffracted light of high order is used as object light, transmitted through an imaging region of the diffracted light of high order by a spatial filter 18, and made incident on a local region on the photosensitive material 14. Reference light is made incident from the reverse surface of the photosensitive material 14 so as to interfere with the object light, thereby exposing an element holograph. Then an aperture of the spatial filter 18 is shifted in position, other diffracted light of high order is used as object light, and then the reference light is accordingly changed in position to expose a next element hologram without moving the photosensitive material 14. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method and apparatus for producing a holographic solid hard copy using a hologram.

  In recent years, three-dimensional image processing technology has been widely used. For example, in the medical field, three-dimensional information of a human body is collected by X-ray CT (Computed Tomography), MRI (Magnetic Resonance Imaging), etc. It is useful for planning. In addition, a three-dimensional CAD system is used for architecture, product design, and the like.

  Currently, photographs such as two-dimensional tomographic images and projected images are used as hard copies that are output from these three-dimensional image processing systems. However, as a more efficient and easy-to-understand thing, a hard copy that expresses a three-dimensional object in a planar manner is desired.

  Further, a holographic stereogram (hereinafter referred to as HS) is the best as a hard copy capable of stereoscopically displaying a three-dimensional object processed and generated by a computer. This HS combines a planar image of an object viewed from various angles into a single hologram, and is suitable for three-dimensional recording and display of an imaginary object.

  However, an HS method that satisfies the conditions as a hard copy of a three-dimensional object has not been reported so far. For this reason, in the conventional method, the vertical parallax cannot be recorded, and the reproduced image is distorted depending on the observation position. In addition, the method of combining in two steps cannot automatically record a hologram.

  On the other hand, multiplex holograms, Alcove Holograms, etc. have been proposed as automatic synthesis methods, but these are not only capable of recording parallax information in the vertical direction, but are also cylindrical and semi-cylindrical. Therefore, since a playback device is required for observation, it is not suitable for general hard copy.

Therefore, recently, various holographic solid hard copy manufacturing methods have been proposed (see, for example, Patent Documents 1 and 2, Non-Patent Document 1, etc.).
For example, the method of Patent Document 1 displays an image pattern created by a computer on a spatial modulation element such as a liquid crystal panel 17 and transmits the transmitted light through a lens 12 as shown in FIG. The light is focused on the local region 19 as object light (converging spherical wave) on the surface (photosensitive material) 14, and the reference light (plane wave) is incident on the local region (same point) 19 from the opposite direction. The interference fringe pattern is recorded on the hologram surface 14 as a dot-shaped element hologram. Then, the photosensitive material 14 is moved little by little in the vertical and horizontal directions, sequentially exposed, and dot-shaped hologram elements are exposed on the entire surface of the hologram to produce a holographic solid hard copy.

The holographic solid hard copy produced by this method is a flat type, can be synthesized in one step, and parallax information in the vertical direction is also recorded, so that a three-dimensional image can be accurately recorded and displayed. Further, in this method, since dot-shaped hologram elements are sequentially recorded on the surface of the substrate, recording can be performed in a manner similar to a conventional dot printer. Therefore, it is optimal for realizing a 3-D printer as a three-dimensional data hard copy machine.
That is, a three-dimensional hard copy can be produced with one optical system, and a holographic three-dimensional hard copy can be produced automatically.
JP-A-3-249686 Japanese Patent No. 3324328 FY2004 Research Report on 3D Image Display March 2005 P30-31

  However, in the optical system for realizing the above-described method, it is easy to pick up vibration, and measures against vibration are required. Therefore, in order to expose the hologram element in a local region on the photosensitive material, each time the photosensitive material is moved in the vertical and horizontal directions, it is necessary to wait for a certain period of time until the vibration is settled. It takes time.

  Therefore, an object of the present invention is to provide a holographic solid hard copy manufacturing method and manufacturing apparatus capable of reducing the number of standby times and manufacturing HS in an extremely short time.

  In order to achieve the above-described object, the holographic solid hard copy manufacturing method of the present invention forms a three-dimensional image by forming an element hologram by causing object light and reference light to interfere in each of a plurality of local regions on a photosensitive material. In which a coherent light output from a light source is bifurcated, and one of the two coherent lights is spatially separated by an element having a regular arrangement. A step of outputting the modulated high-order diffracted light of the coherent light as object light, and a step of causing the object light to be incident on a local region on the photosensitive material using a position variable spatial filter; A step of allowing the other coherent light branched into two to be incident on a local area on the photosensitive material following the movement of the object light from a side opposite to the side on which the object light is incident. Specially To.

  The holographic solid hard copy production apparatus of the present invention produces a hard copy that displays a three-dimensional image by forming an element hologram by causing object light and reference light to interfere with each other in a plurality of local regions on a photosensitive material. A light source that outputs coherent light, an optical branching unit that splits the coherent light output from the light source into two, and one coherent light that has been split into two by the optical branching unit is ordered Object light generating means for spatially modulating by means of an element having an array and outputting the modulated higher order diffracted light as object light, and object light output from the object light generating means An object light optical system having a position-variable spatial filter for making the light incident on a local region on the photosensitive material, and the other coherent light bifurcated by the light branching means as a reference light, the object light From the opposite side of the incident, characterized in that a reference beam optical system to be incident to follow the movement of the object light to a localized area on the photosensitive material.

  In the above configuration, a hard copy is produced without using zero-order light as diffracted light used as the object light. The reference light optical system is provided with a position-variable spatial filter for making the reference light enter a local region on the photosensitive material. Further, a liquid crystal panel is used as the position variable spatial filter.

According to the holographic solid hard copy manufacturing method and manufacturing apparatus of the present invention, since the hologram element is exposed, a certain period of time until the vibration that had to be performed each time the photosensitive material is moved in the vertical and horizontal directions is settled. It is possible to reduce the number of standby times, and it is possible to perform HS production time in an extremely short time.
In addition, a uniform hologram element can be produced by not using 0th-order diffracted light, which exhibits high intensity with respect to high-order diffracted light, as object light. In addition, as a mechanism for making the reference light incident on the local region on the photosensitive material, by providing a position variable spatial filter, the local region can be easily moved as in the case of the object light.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.
FIG. 1 is an overall configuration diagram showing an outline of a holographic solid hard copy manufacturing apparatus according to an embodiment of the present invention, and FIG. 2 is a configuration showing details on the object light side of the holographic solid hard copy manufacturing apparatus shown in FIG. FIG. In addition, the same code | symbol is attached | subjected about the same component as FIG.

The holographic solid hard copy production apparatus according to the present embodiment is an apparatus for producing HS by exposing a plurality of element holograms on a photosensitive material 14, and includes a laser light source 11, a lens 12, a mirror 13, a beam splitter 15, A random phase plate 16 and liquid crystal panels 17 and 18 are provided.
In this apparatus, coherent light output from the laser light source 11 is branched into two by a beam splitter 15, and one is spread by a lens 12 to be converted into parallel light. Thereafter, after passing through the random phase plate 16, the parallel light is spatially modulated by the liquid crystal panel 17 and condensed by the lens 12.
Thereafter, an aperture of about 0.1 mm to 1 mm is displayed on the liquid crystal panel 18 as a spatial filter, allowing coherent light to pass therethrough and forming an image on the photosensitive material 14 as object light.
Further, the other of the two branches is used as a reference light to cause interference between the object light and the local region 19 on the photosensitive material 14 to expose the element hologram.

  At this time, the distance between the liquid crystal panel 17 as the spatial modulation element and the lens 12 and the liquid crystal panel 18 as the spatial filter is the focal length of the lens 12. Therefore, a Fraunhofer diffraction image of the liquid crystal panel 17 is generated on the liquid crystal panel 18.

When the pixel pitch of the liquid crystal panel 17 is 0.3 mm, the first-order diffracted image is generated at a position 2.5 mm away from the zero-order diffracted light (imaging region 20). Therefore, by arranging the opening of the spatial filter in the image formation region 21 of the first-order diffraction image, it is possible to expose the next element hologram without moving the photosensitive material 14.
By repeating such a process, it is possible to expose a large number of element holograms without moving the photosensitive material 14, and to produce HS in a short time.

  At this time, the reference side also uses the liquid crystal panel as the spatial filter 18 to facilitate alignment with the local region 19 where the object light is condensed.

  As described above, in the holographic solid hard copy manufacturing method and manufacturing apparatus of this example, the diffracted light transmitted through the spatial modulation element is 0 by making the coherent light incident on the spatial modulation element having a regular arrangement. Not only the secondary light but also the high-order diffracted light such as ± first-order light and ± second-order light shows high intensity due to the periodic structure of the spatial modulation element. This higher-order diffracted light has the same intensity distribution shape and phase distribution as the zero-order light. Therefore, it can be used as object light.

  Then, by selecting the diffracted light with a position-variable spatial filter and exposing the element hologram by interfering with the reference light, it is possible to expose the element hologram without moving the photosensitive material by the number of diffracted lights to be used. Become.

  As a result, in the holographic solid hard copy manufacturing method and apparatus of the present embodiment, the local region can be moved without moving the photosensitive material in the vertical and horizontal directions. Therefore, it is possible to reduce the number of standby times for a certain period of time until vibration that occurs each time the photosensitive material is moved is reduced, and HS can be manufactured in a very short time.

1 is an overall configuration diagram showing an outline of a holographic solid hard copy manufacturing apparatus according to an embodiment of the present invention. It is a detailed block diagram explaining the object light side of the holographic solid hard copy production apparatus shown in FIG. It is a block diagram which shows the optical system of the conventional 1 step Lippman HS.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Light source, 12 ... Lens, 13 ... Mirror, 14 ... Photosensitive material, 15 ... Beam splitter, 16 ... Random phase plate, 17 ... Liquid crystal panel (spatial modulation element), 18 ... Liquid crystal panel (Spatial filter), 19... Local region, 20... 0th-order diffracted light imaging region, 21.

Claims (8)

A method for producing a hard copy for displaying a three-dimensional image by forming an element hologram by causing interference between object light and reference light in each of a plurality of local regions on a photosensitive material,
Bifurcating the coherent light output from the light source;
A step of spatially modulating one of the two coherent beams separated by an element having a regular arrangement, and outputting a higher-order diffracted beam of the modulated coherent beam as an object beam;
Making the object light incident on a local region on the photosensitive material using a position-variable spatial filter;
A step of making the other coherent light that has been bifurcated as a reference light incident on a local area on the photosensitive material from the side opposite to the side on which the object light is incident, following the movement of the object light; and
A method for producing a holographic solid hard copy, comprising:   The holographic solid hard copy manufacturing method according to claim 1, wherein a hard copy is manufactured without using zero-order light as diffracted light used as the object light.   3. The method for producing a holographic solid hard copy according to claim 1, wherein the reference light optical system includes a position variable spatial filter for making the reference light incident on a local region on the photosensitive material.   4. The method for producing a holographic solid hard copy according to claim 3, wherein a liquid crystal panel is used as the position-variable spatial filter. An apparatus for producing a hard copy for displaying a three-dimensional image by forming an element hologram by causing interference between object light and reference light in each of a plurality of local regions on a photosensitive material,
A light source that outputs coherent light;
Light branching means for branching the coherent light output from the light source into two;
The light branching means spatially modulates one of the coherent light beams branched into two by an element having a regular arrangement, and outputs the higher-order diffracted light of the modulated coherent light as object light. Object light generating means;
An object light optical system comprising a position-variable spatial filter for causing the object light output from the object light generating means to enter a local region on the photosensitive material;
The other coherent light bifurcated by the light branching means is used as a reference light and incident on the local area on the photosensitive material following the movement of the object light from the side opposite to the side on which the object light is incident. A reference beam optical system;
A holographic solid hard copy production apparatus characterized by comprising:   6. The holographic solid hard copy production apparatus according to claim 5, wherein a hard copy is produced without using zero-order light as diffracted light used as the object light.   7. The holographic solid hard copy manufacturing apparatus according to claim 5, wherein the reference light optical system includes a position-variable spatial filter for causing the reference light to enter a local region on the photosensitive material. 8. The holographic solid hard copy manufacturing apparatus according to claim 7, wherein a liquid crystal panel is used as the position-variable spatial filter.

Images