JP6607491B2 - Hologram data generation device and program thereof - Google Patents

Description

  The present invention relates to a hologram data generation apparatus that generates hologram data and a program thereof.

  Conventionally, an invention has been proposed in which stereoscopic display is performed using hologram data generated from CG data (Patent Document 1). This prior art employs a Fourier transform hologram method in which light transmitted through a spatial light modulator (SLM) is converged by a reproducing lens and a stereoscopic image is formed near the focal position. And this prior art suppresses the distortion of the three-dimensional image resulting from the aberration of the reproduction lens by correcting the hologram data with the correction data representing the phase difference between the reproduction lens and the ideal lens.

JP 2014-215332 A

  In principle, in holography, when hologram data is recorded and reproduced on a hologram recording medium such as a silver salt sensitive material or a photopolymer, the reference light during hologram recording and the illumination light (reproduction light) during hologram reproduction are in the same direction. The object light equivalent to that during hologram recording can be reproduced. However, in reality, in holography, it is often difficult to illuminate the same light source as the reference light as reproduction light depending on the installation conditions and observation conditions of the hologram. If there is a difference between the direction of the reference light and the reproduction light, there arises a problem that the object light is not reproduced correctly.

  Here, in the technology for recording the object light reproduced by displaying the hologram data on the SLM onto the hologram recording medium (hereinafter referred to as “wavefront recording technology”), the hologram recording surface is divided into small regions and each small region is recorded sequentially. By doing so, the entire hologram recording surface is recorded. At this time, in many cases, the reference light is parallel light having a front face or a constant incident angle with respect to each small region. On the other hand, in order to illuminate the entire surface of the hologram with parallel light during hologram reproduction, a lens having a size larger than that of the hologram is required to collimate the light from the light source. Therefore, depending on the size of the hologram, it becomes difficult to prepare an illumination environment with parallel light, and illumination close to a point light source such as a halogen lamp or an LED light source is often used as reproduction light. In this case, not only the direction deviation between the reference light and the reproduction light occurs, but also the distance from each pixel position on the hologram recording surface to the point light source differs, so that a difference in luminance distribution (brightness unevenness) occurs.

  In the wavefront recording technique, the object light can be freely adjusted on the hologram data. For this reason, it is possible to previously correct the deviation in the direction of the incident angle and the difference in the luminance distribution between the reference light and the reproduction light with respect to the hologram recording medium using the hologram data.

  The above-described prior art can also correct a direction shift (phase shift) that occurs during hologram reproduction when calculating hologram data. However, the above-described conventional technique is a technique related to electronic holography in which object light reproduced by the SLM is not recorded on the hologram recording medium but directly observed through the reproducing lens. Differences in luminance distribution are not corrected. Furthermore, since the above-described prior art is intended only for Fourier transform holograms using a reproduction lens, it cannot be applied to Fresnel or image holograms that do not require a reproduction lens.

  Accordingly, it is an object of the present invention to provide a hologram data generation apparatus and a program thereof that can correctly reproduce the object light before correction in the wavefront recording technique.

  In view of the above-described problems, the hologram data generation apparatus according to the present invention irradiates reference light that is irradiated when recording hologram data on the hologram recording medium and irradiation when reproducing the hologram data recorded on the hologram recording medium. A hologram data generation device that corrects a direction deviation from reproduction light, and includes a complex amplitude distribution calculation unit, a corrected object light calculation unit, and a hologram data generation unit.

  According to such a configuration, the hologram data generation apparatus uses the complex amplitude distribution calculating unit to obtain the hologram recording surface for the object light to be reproduced (object light before correction), the reference light at the time of hologram recording, and the reproduced light at the time of hologram reproduction. Compute the complex amplitude distribution above.

  Here, the complex amplitude distribution of the object light before correction can be calculated by a known hologram calculation method used in a computer generated hologram (CGH) or the like. For example, the complex amplitude distribution of the object light before correction is obtained by a method of calculating the light wave propagation from each light source to the hologram recording surface assuming that the object light to be reproduced is a point light source or a polygon light source. Further, the complex amplitude distribution of the object light before correction may be obtained by a method of calculating the complex amplitude distribution on the hologram recording surface using high-density light ray information such as a multi-viewpoint image group.

  As described above, the reference light is often parallel light having a front angle or a constant incident angle with respect to the hologram recording surface. In this case, since the amplitude information of the reference light is constant over the entire hologram recording surface, only the phase distribution that changes according to the position on the hologram recording surface needs to be obtained as the complex amplitude distribution of the reference light.

As described above, the reproduction light can often be assumed to be parallel light, one or a plurality of point light sources.
Assuming parallel light, the complex amplitude distribution of the reproduction light can be obtained by the same method as the reference light.
Assuming one point light source, the complex amplitude distribution of the reconstructed light is calculated from the Kirchhoff diffraction integral formula from the point light source to the hologram recording surface, exact light wave propagation calculation such as the angular spectrum method, or approximate calculation such as Fresnel diffraction. Is required.
When it is assumed that there are a plurality of point light sources, the complex amplitude distribution of the reproduction light is obtained by calculating the light wave propagation from each point light source and calculating the complex sum of the calculation results.

  In the hologram data generation apparatus, a calculation formula representing the complex amplitude distribution of the corrected object light whose direction deviation is corrected is set in advance by the corrected object light calculation means. This calculation formula contributes to both the phase and the amplitude of the object light before correction, and can correct the direction deviation.

Then, the hologram data generation device uses the corrected object light calculation unit to calculate the complex amplitude distribution of the corrected object light based on the preset calculation formula and the complex amplitude distribution of the uncorrected object light, the reference light, and the reproduction light. Is calculated. At this time, the post-correction object light calculation means calculates the complex amplitude distribution of the pre-correction object light represented by the amplitude A _O and the phase φ _O for each pixel position (x, y) of the hologram recording medium , the amplitude A _R, and Correction is performed by substituting the complex amplitude distribution of the reference light represented by the phase φ _R and the complex amplitude distribution of the reproduction light represented by the amplitude A _P and the phase φ _P into Equation (4) as a calculation formula. A complex amplitude distribution C of the rear object light is calculated. Further, the hologram data generation device generates hologram data reflecting the complex amplitude distribution of the corrected object light by the hologram data generation means.

  Here, the hologram data generating apparatus according to the present invention can correct not only the above-described direction deviation but also the difference in luminance distribution between the reference light at the time of hologram recording and the reproduced light at the time of hologram reproduction.

According to the present invention, the following excellent effects can be obtained.
Since the hologram data generation apparatus according to the present invention generates hologram data in which the direction deviation and luminance unevenness are corrected, the object light before correction can be correctly reproduced.

In this invention, it is explanatory drawing explaining recording of hologram data. In this invention, it is explanatory drawing explaining the direction shift | offset | difference at the time of hologram reproduction. In this invention, it is explanatory drawing explaining the difference in the luminance distribution at the time of hologram reproduction. In this invention, it is explanatory drawing explaining correction | amendment of the direction shift and the difference in luminance distribution with a reflection type hologram at the time of hologram recording. In this invention, at the time of hologram reproduction | regeneration, it is explanatory drawing explaining correction | amendment of the direction shift and the difference in luminance distribution with a reflection type hologram. In this invention, it is explanatory drawing explaining correction | amendment of the direction shift and the difference in luminance distribution with a transmission type hologram at the time of hologram recording. In the present invention, at the time of hologram reproduction, it is an explanatory view for explaining correction of a difference in direction deviation and a luminance distribution in a transmission type hologram. It is a block diagram which shows the structure of the hologram data recording system which concerns on embodiment of this invention. In this invention, when the light source of reproduction | regeneration light is a several point light source, it is explanatory drawing explaining calculation of a complex amplitude distribution. In this invention, when the light source of reproduction | regeneration light is a line light source, it is explanatory drawing explaining calculation of a complex amplitude distribution. In this invention, when the light source of reproduction | regeneration light is a surface light source, it is explanatory drawing explaining calculation of a complex amplitude distribution. It is a flowchart which shows operation | movement of the hologram data production | generation apparatus of FIG.

(Correction method for difference in direction and luminance distribution)
With reference to FIGS. 1 to 3, after explaining the correction method of the difference in direction deviation and the luminance distribution in the present invention, the configuration of the hologram data recording system according to the embodiment of the present invention will be described.

  As shown in FIG. 1, in the wavefront recording technique, when hologram data is recorded on the hologram recording medium 9 (at the time of hologram recording), the reference light R is irradiated from the front of the object light (object light before correction) O, and the object light O Consider that interference fringes of the reference light R are recorded (printed) on the hologram recording medium 9. At this time, if the hologram recording medium 9 is irradiated with the same reproduction light as the reference light R, the stereoscopic image U of the subject T is reproduced as it is.

As shown in FIG. 2, when the observer V observes a stereoscopic image in front of the hologram recording medium 9, it is difficult to arrange the light source of the reproduction light in front of the hologram recording medium 9. Therefore, since the reproduction light P is irradiated from a direction deviated by the angle θ with respect to the reference light R, the object light is not correctly reproduced due to the direction misalignment between the reference light R and the reproduction light P. As a result, the stereoscopic image U of the subject T is reproduced with distortion at a position shifted from the original position (that is, the position of the subject T).
In FIG. 2, the object T is illustrated with reference light R and a broken line for the sake of explanation. However, when reproducing hologram data recorded on the hologram recording medium 9 (during hologram reproduction), the reference light R is not irradiated. The subject T does not exist.

Further, as shown in FIG. 3, the reproduction light when the P of the light source is a point light source 90 _P, holographic recording medium 9 center distance L ₁ to the point light source 90 _P from the end point light source 90 from the hologram recording medium 9 the distance to the _{P L 2} is different. Due to the difference between the distances L ₁ and L _2, a difference in luminance distribution with respect to the reference light R at the time of hologram recording occurs due to luminance unevenness such that the center of the hologram recording medium 9 is bright and the edge is dark.

  If the above-described reference light R and reproduction light P are misaligned or have a difference in luminance distribution, the object light is not reproduced correctly. Therefore, at the time of hologram recording, the direction deviation and the difference in luminance distribution are corrected in advance on the hologram data.

  As shown in FIG. 4, a reflection hologram is recorded on the hologram recording medium 9. In FIG. 4, the object light O at the time of hologram recording is illustrated by a broken line, and the reference light R is illustrated by a solid line. In FIG. 4, the propagation direction of the object light O is indicated by a block arrow.

Here, the complex amplitude distribution O (x, y) of the object light is defined as the following formula (1). In this equation (1), A _O represents the amplitude of the object light O, φ _O represents the phase of the object light O, j represents an imaginary unit, and exp represents an exponential function. Further, (x, y) represents a two-dimensional coordinate system with the central pixel of the hologram recording medium 9 as the origin (0, 0).

Further, the complex amplitude distribution R (x, y) of the reference light that is regularly reflected by the hologram recording medium 9 is defined as the following equation (2). In the equation (2), A _R represents the amplitude of the reference light R, phi _R represents a phase of the reference light R.

In FIG. 5, the reproduction light P at the time of hologram recording is shown by a solid line.
Here, the complex amplitude distribution P (x, y) of the reproduction light that is regularly reflected by the hologram recording medium 9 is defined as the following equation (3). In this equation (3), A _P represents the amplitude of the reproduction light P, and φ _P represents the phase of the reproduction light P.

  As shown in FIGS. 4 and 5, when the propagation direction of the object light O is the positive direction, the reference light R and the reproduction light P reflected by the hologram recording medium 9 also propagate in the positive direction. In this case, the complex amplitude distribution C (x, y) of the corrected object light in which the difference in direction deviation and the luminance distribution is corrected can be expressed by a calculation formula of Formula (4).

  This equation (4) corrects only the direction deviation when only the direction deviation occurs. Further, Equation (4) corrects only the difference in luminance distribution when only the difference in luminance distribution occurs. Furthermore, the equation (4) can correct both the direction deviation and the difference in luminance distribution when both the direction deviation and the difference in luminance distribution occur.

  Here, a case where a transmission hologram is recorded on the hologram recording medium 9 is also considered. In this case, the object light O and the reference light R propagate in the positive direction as shown in FIG. 6 at the time of hologram recording, and the reproduction light P propagates in the positive direction as shown in FIG. 4) can be used as it is. That is, the formula (4) can be applied regardless of whether the hologram recorded on the hologram recording medium 9 is a reflection type or a transmission type.

From the above, the complex amplitude distribution O (x, y) of the object light, the complex amplitude distribution R (x, y) of the reference light, and the complex amplitude distribution P (x, y) of the reproduction light are obtained. It decomposes into _{O 2} , A _R , A _P and phases φ _O , φ _R , φ _P. Then, by substituting the amplitudes A _O , A _R , A _P and the phases φ _O , φ _R , φ _P into the equation (4), the complex amplitude distribution C (x, y) of the corrected object light can be obtained. .

Thereafter, hologram data reflecting the complex amplitude distribution C (x, y) of the corrected object light is generated, the generated hologram data is displayed on the SLM and reproduced, and the reproduced corrected object light is reproduced as a hologram recording medium. Record in 9. For example, the interference fringe H (x, y) represented by the hologram data is defined by the following equation (5). In this equation (5), the superscript “*” represents the complex conjugate, and R ₂ represents the reproduction light irradiated to the SLM in order to reproduce the corrected object light by the SLM. That is, R ₂ is different from the reference light applied to the hologram recording medium 9 during hologram recording.

(Configuration of hologram data recording system)
With reference to FIG. 8, the structure of the hologram data recording system 1 which concerns on embodiment of this invention is demonstrated.
As shown in FIG. 8, the hologram data recording system 1 records hologram data on a hologram recording medium 9 and includes a hologram data recording device 10 and a hologram data generating device 20.

  The hologram recording medium 9 is for recording hologram data. Specifically, as a material of the hologram recording medium 9, for example, a material in which a photopolymer and a photosensitive material are laminated on a glass or plastic substrate can be cited.

[Configuration of hologram data recording apparatus]
First, the configuration of the hologram data recording apparatus 10 will be described.
The hologram data recording apparatus 10 includes a laser 100, a half-wave plate 101, lenses 102 and 103, a polarization beam splitter 104, an object light optical system 110, a reference light optical system 120, and a stage 130. .

  The laser 100 is a laser device that oscillates laser light. For example, a laser device that oscillates laser light such as a continuous wave laser or a pulse laser can be used as the laser 100 in accordance with the recording method of the hologram recording medium 9.

  The half-wave plate 101 changes the polarization direction of the laser light from the laser 100 in order to adjust the balance between P-polarized light and S-polarized light branched by the polarizing beam splitter 104 described later.

The lens 102 is, for example, a convex lens that expands the beam diameter of the laser light from the half-wave plate 101. The lens 102 may be a single lens or a compound lens as long as it satisfies the function (the same applies to lenses 103, 113, and 115 to 117 described later).
Note that the center of the optical axis of the laser beam magnified by the lens 102 is indicated by a long broken line, and both ends of the laser beam are indicated by a short broken line.

The lens 103 is, for example, a convex lens that converts laser light from the lens 102 into parallel light.
The polarization beam splitter 104 branches the laser light from the lens 103 into object light (P-polarized light) and reference light (S-polarized light). That is, the polarization beam splitter 104 branches the laser light from the lens 103 into P-polarized light and S-polarized light that are orthogonal to each other. In the present embodiment, the laser light transmitted through the polarizing beam splitter 104 is used as object light, and the laser light reflected by the polarizing beam splitter 104 is used as reference light.

  The object light optical system 110 is an optical system that emits the object light transmitted through the polarization beam splitter 104 to the hologram recording medium 9. The object light optical system 110 is arranged so that the object light from the object light optical system 110 and the reference light from the reference light optical system 120 are irradiated to the same position on the recording surface of the hologram recording medium 9. The object light optical system 110 includes a polarization beam splitter 111, an SLM 112, a lens 113, an HZP (half zone plate) processing mask 114, and lenses 115 to 117.

  The polarization beam splitter 111 transmits the object light from the polarization beam splitter 104 to the SLM 112 and reflects the object light from the SLM 112 toward the lens 113. That is, the polarizing beam splitter 111 reflects the object light whose amplitude is modulated by the SLM 112 toward the lens 113.

The SLM 112 is an amplitude modulation element that displays hologram data input from the hologram data generation device 20. The SLM 112 modulates the amplitude of the object light from the polarization beam splitter 111 according to the hologram data, and reflects the object light reflecting the hologram data (interference fringes) to the polarization beam splitter 111.
The hologram data is data representing the interference fringes of the hologram. In the present embodiment, the hologram data reflects correction information (complex amplitude distribution of the corrected object light) obtained by correcting the direction deviation and the difference in luminance distribution.

The lens 113 is, for example, a convex lens that condenses the object light reflected by the polarization beam splitter 111 on the HZP processing mask 114.
The HZP processing mask 114 is a mask that blocks half of the object light from the lens 113 in order to perform the HZP processing for removing interference light.

The lens 115 is, for example, a convex lens that converts object light from the HZP processing mask 114 into parallel light.
The lens 116 is, for example, a convex lens that condenses the object light from the lens 115 on the lens 117.
The lens 117 is a convex lens that emits object light from the lens 116 to the hologram recording medium 9, for example.

  The reference light optical system 120 is an optical system that emits the reference light reflected by the polarization beam splitter 104 to the hologram recording medium 9, and includes a spatial filter 121 and mirrors 122 and 123.

The spatial filter 121 is a filter that blocks the outer periphery of the reference light reflected by the polarization beam splitter 104.
The mirror 122 reflects the reference light from the spatial filter 121 to the mirror 123.
The mirror 123 reflects the reference light from the mirror 122 to the hologram recording medium 9.

  The stage 130 mounts the hologram recording medium 9 and moves it to an arbitrary position. For example, when recording hologram data in element cell units, the stage 130 may move the mounted hologram recording medium 9 in the biaxial direction.

  With the above configuration, the polarization direction of the laser light emitted from the laser 100 is adjusted by the half-wave plate 101. Then, this laser light is branched into object light and reference light by the polarization beam splitter 104.

  The object light passes through the polarization beam splitter 111 and enters the SLM 112. At this time, the SLM 112 displays the hologram data reflecting the correction information. Therefore, the amplitude of the object light incident on the SLM 112 is modulated in accordance with the hologram data displayed on the SLM 112 and emitted to the hologram recording medium 9 as P-polarized light.

  Further, the reference light is narrowed down to the same beam diameter as the object light by the spatial filter 121 and reflected by the mirror 122. Then, the reference light is emitted to the hologram recording medium 9 via the reference light optical system 120. In this way, both the object beam and the reference beam are applied to the same position of the hologram recording medium 9, and hologram data (interference fringes) is recorded.

[Configuration of hologram data generation apparatus]
Next, the configuration of the hologram data generation device 20 will be described.
The hologram data generation device 20 generates hologram data in which the direction deviation between the reference light at the time of hologram recording and the reproduction light at the time of hologram reproduction or the difference in luminance distribution is corrected.

  As shown in FIG. 8, the hologram data generation apparatus 20 includes parameter input means 21, complex amplitude distribution calculation means 22, correction information calculation means (corrected object light calculation means) 23, and hologram data generation means 24. .

  The parameter input unit 21 inputs parameters necessary for calculating the complex amplitude distribution of the object light, the reference light, and the reproduction light. For example, a user of the hologram data recording apparatus 10 inputs parameters to the parameter input unit 21 using an operation unit such as a mouse or a keyboard (not shown).

  For example, the complex amplitude distribution O (x, y) of the object light is calculated by a point light source model, a polygon model, or a light sampling surface. Therefore, information used for a known hologram calculation method such as a light source information such as a point light source model, a polygon point light source model, or a multi-viewpoint image group is input to the parameter input unit 21 as a parameter relating to the object light. More specifically, when the point light source model or the polygon light source model is used, the parameter is three-dimensional information or luminance information of each light source. In addition, when the light ray information is used, the parameters are luminance information of each light ray, spatial sampling information of the light ray, and angle sampling information.

  Usually, the reference light applied to the hologram recording medium 9 during hologram recording is often parallel light. In this case, the parameter input means 21 inputs the wavelength of the reference light, the initial phase at the origin, and the angle formed with respect to the x-axis and the y-axis as parameters relating to the reference light.

If the light source 90 _P of reproducing light of the point light source, the complex amplitude distribution P (x, y) is it can be calculated by the Fresnel diffraction. Therefore, the parameter input unit 21 as a parameter relating to the reproduction light, and inputs the wavelength and amplitude of the point light source, the position of the initial phase, the light source 90 _P.
As shown in FIG. 9, there may be a plurality of light sources 90 _{P for} reproduction light, such as light sources 90 _{P1 ,.} In this case, the parameter input means 21, for all the light sources 90 _P, enter parameters.

Further, as shown in FIG. 10, there is also a case where the light source 90 _P of reproducing light of line light sources. In this case, the linear light source is preset in the parameter input means 21 as a set of n light sources 90 _P1 ,..., Light source 90 _Pn (n is an integer of 2 or more), and parameters are input for all light sources 90 _P. To do.
Furthermore, as shown in FIG. 11, the light source 90 _P of the reproduced light is the case of the surface light source. In this case, the parameter input means 21 presets the surface light sources as a set of m × n light sources 90 _P11 ,..., Light sources 90 _Pmn (m and n are integers of 2 or more), and all the light sources 90 _P are set. Enter the parameters.

Thereafter, the parameter input means 21 outputs the input parameters to the complex amplitude distribution calculation means 22.
Returning to FIG. 8, the description of the configuration of the hologram data generation apparatus 20 will be continued.

The complex amplitude distribution calculating unit 22 refers to the parameter input from the parameter input unit 21 and calculates a complex amplitude distribution for the object light, the reference light, and the reproduction light.
Specifically, the complex amplitude distribution calculating unit 22 calculates the complex amplitude distribution O (x, y) of the object light by a known hologram calculation method using a point light source model, a polygon point light source model, or light ray information.

For example, in the case of a point light source model and a polygon point light source model, the methods described in the following references 1 and 2 can be used as hologram calculation methods.
Reference 1: M. Lucente, “Interactive computation of holograms of holograms using a look-up table”, Journal of Electronic Imaging, Vol. 2, No. 1, 1993
Reference 2: K. Matsushima, S. Nakahara, “Extremely high-definition full-parallax computer-generated hologram created by the polygon-based method”, Applied optics, Vol. 48, Issue 34, 2009

In the case of ray information, the methods described in the following references 3 and 4 can be used as a hologram calculation method.
Reference 3: T.Yatagai, “Stereoscopic approach to 3-D display using computer-generated hologram”, Applied Optics Vol.15, Issue 11,1976
Reference 4: K. Wakunami, M. Yamaguchi, “Calculation for computer generated hologram using ray-sampling plane”, Optics Express, Vol. 19, Issue 10, 2011

Further, the complex amplitude distribution calculating means 22 calculates the complex amplitude distribution R (x, y) of the reference light that is parallel light by the following equation (6). In this formula (6), k represents the wave number (k = 2π / λ _R ), and λ _R represents the wavelength of the reference light R. Φ _(0,0) represents the initial phase at the origin (0,0) of the two-dimensional coordinate system (x, y). Θ _x and θ _y represent angles formed with respect to the x-axis and the y-axis, respectively.

Moreover, the complex amplitude distribution calculating means 22, the light source 90 _P is a point light source reproduction light complex amplitude distribution P (x, y) is calculated by the Fresnel diffraction. This Fresnel diffraction is defined by the following equation (7). In this equation (7), A _P represents the amplitude of the reproduction light, λ _z represents the wavelength of the reproduction light, and (x _P , y _P , z) represents the position of the light source 90 _P.

Here, when there are a plurality of light sources 90 _{Pn for} reproduction light, the complex amplitude distribution calculation means 22 calculates a complex amplitude distribution P _n (x, y) of reproduction light for each light source 90 _Pn . Then, the complex amplitude distribution calculating means 22 calculates the sum of the complex amplitude distributions P _n (x, y) of the reproduction light calculated for each light source 90 _Pn by the following equation (8), and the complex amplitude distribution of one reproduction light Calculated as P (x, y).

Incidentally, the complex amplitude distribution calculation means 22, when the light source 90 _P of reproducing light of line light sources or a surface light source, preset the line light source or a surface light source as a set of point light sources, using equation (8), reproducing light The complex amplitude distribution P (x, y) of is calculated.

  Thereafter, the complex amplitude distribution calculating means 22 calculates the calculated complex amplitude distribution O (x, y) of the object light, the complex amplitude distribution R (x, y) of the reference light, and the complex amplitude distribution P (x, y) of the reproduction light. y) is output to the correction information calculation means 23.

The correction information calculation unit 23 calculates correction information.
Specifically, the correction information calculation means 23 has the formula (4) as a calculation formula representing the complex amplitude distribution C (x, y) of the corrected object light in which the direction shift and the difference in luminance distribution are corrected. It is set in advance.
Further, the correction information calculation unit 23 includes the complex amplitude distribution O (x, y) of the object light input from the complex amplitude distribution calculation unit 22, the complex amplitude distribution R (x, y) of the reference light, and the reproduction light. The complex amplitude distribution P (x, y) is decomposed into the amplitudes A _O , A _R , A _P and the phases φ _O , φ _R , φ _P using the equations (1) to (3), respectively.
Then, the correction information calculation means 23 substitutes the amplitudes A _O , A _R , A _P and the phases φ _O , φ _R , φ _P into the above equation (4), so that the complex amplitude distribution C ( x, y) is calculated.
Thereafter, the correction information calculation unit 23 outputs the calculated complex amplitude distribution C (x, y) of the corrected object light to the hologram data generation unit 24.

The hologram data generation unit 24 generates hologram data in which the complex amplitude distribution C (x, y) of the corrected object light input from the correction information calculation unit 23 is reflected.
Specifically, the hologram data generation unit 24 generates hologram data using the equation (5). That is, the hologram data generating unit 24 encodes the complex amplitude distribution C (x, y) of the corrected object light by a general hologram encoding method, and generates hologram data.
Thereafter, the hologram data generation unit 24 outputs the generated hologram data to the SLM 112.

[Operation of hologram data generator]
The operation of the hologram data generation apparatus 20 will be described with reference to FIG. 12 (see FIG. 8 as appropriate).

The hologram data generation apparatus 20 inputs parameters necessary for calculating the complex amplitude distribution of the object light, the reference light, and the reproduction light by using the parameter input unit 21 (step S1).
The hologram data generation apparatus 20 calculates a complex amplitude distribution for the object light, the reference light, and the reproduction light by using the complex amplitude distribution calculation unit 22 with reference to the parameters input in step S1 (step S2).

The hologram data generation apparatus 20 calculates the complex amplitude distribution C (x, y) of the corrected object light as the correction information by the correction information calculation unit 23 (step S3).
The hologram data generation device 20 generates hologram data reflecting the complex amplitude distribution C (x, y) of the corrected object light by the hologram data generation unit 24 (step S4).

Thereafter, the hologram data generated in step S4 is output and displayed on the SLM 112 and recorded on the hologram recording medium 9.
At the time of hologram reproduction, the reproduction light may be illuminated on the hologram recording medium 9 under the same conditions as the parameters input to the parameter input means 21.

(Action / Effect)
Since the hologram data generation apparatus 20 according to the present invention generates hologram data in which the direction deviation and the luminance distribution are corrected, the distortion of the stereoscopic image and the luminance distribution due to the direction deviation are suppressed, and the object before correction Light can be reproduced correctly.

  Furthermore, the hologram data generation apparatus 20 can generate hologram data corresponding to various illumination light sources according to the hologram display environment. As a result, it is possible to reproduce the stereoscopic image and the object light before correction intended by the content creator with high reproducibility.

  As mentioned above, although each embodiment of this invention was explained in full detail, this invention is not limited to above-described embodiment, The design change etc. of the range which does not deviate from the summary of this invention are also included.

  In the above-described embodiment, the complex amplitude distribution calculation unit has been described as calculating the complex amplitude distribution of the reproduction light by Fresnel diffraction, but the present invention is not limited to this. For example, the complex amplitude distribution calculating means may calculate the complex amplitude distribution of the reproduction light by not only approximate calculation such as Fresnel diffraction but also exact calculation such as Kirchhoff diffraction integral formula and angular spectrum method.

The configuration of the hologram data recording apparatus (for example, the configuration of the optical system) is not limited to the above-described embodiment.
In the above-described embodiment, the spatial light modulator is described as an amplitude modulation element, but the present invention is not limited to this. For example, the spatial light modulator may be a phase modulation element or an element capable of modulating both phase and amplitude, such as a DPH (double phase hologram) optical system. In this way, when unnecessary light such as conjugate light or zero-order light is not generated, the optical system for filtering (the lenses 113 and 115 and the HZP processing mask 114 in FIG. 1) may be omitted.
In the above-described embodiment, the hologram data generation apparatus has been described as independent hardware, but the present invention is not limited to this. For example, hardware resources such as a CPU, a memory, and a hard disk included in a computer can be realized by a hologram data generation program that performs a cooperative operation as a hologram data generation apparatus. This program may be distributed through a communication line, or may be distributed by writing in a recording medium such as a CD-ROM or a flash memory.

DESCRIPTION OF SYMBOLS 1 Hologram data recording system 9 Hologram recording medium 10 Hologram data recording apparatus 20 Hologram data generation apparatus 21 Parameter input means 22 Complex amplitude distribution calculation means 23 Correction information calculation means (corrected object light calculation means)
24 Hologram data generating means 100 Laser 101 Half-wave plate 102, 103, 113, 115-117 Lens 104, 111 Polarizing beam splitter 110 Object light optical system 112 SLM
114 HZP processing mask 120 Reference light optical system 121 Spatial filter 122, 123 Mirror 130 Stage

Claims (5)

A hologram data generation device that corrects a direction shift between reference light irradiated when recording hologram data on a hologram recording medium and reproduction light irradiated when reproducing hologram data recorded on the hologram recording medium. ,
Complex amplitude distribution calculating means for calculating a complex amplitude distribution for the pre-correction object light, the reference light, and the reproduction light irradiated when recording hologram data on the hologram recording medium;
A calculation formula representing the complex amplitude distribution of the corrected object light in which the direction deviation is corrected is preset, and the preset calculation formula and the complex amplitude of the pre-correction object light, the reference light, and the reproduction light are preset. Corrected object light calculating means for calculating a complex amplitude distribution of the corrected object light based on the distribution;
Hologram data generating means for generating hologram data reflecting the complex amplitude distribution of the corrected object light,
Equipped with a,
The post-correction object light calculation means includes a complex amplitude distribution of the pre-correction object light represented by an amplitude A _O and a phase φ _O for each pixel position (x, y) of the hologram recording medium , an amplitude _AR, and Substituting the complex amplitude distribution of the reference light represented by the phase φ _R and the complex amplitude distribution of the reproduction light represented by the amplitude A _P and the phase φ _P into the equation (4) as the calculation formula so,

A hologram data generation apparatus that calculates a complex amplitude distribution C of the corrected object light . A hologram data generation apparatus for correcting a difference in luminance distribution between reference light irradiated when recording hologram data on a hologram recording medium and reproduction light irradiated when reproducing hologram data recorded on the hologram recording medium There,
Complex amplitude distribution calculating means for calculating a complex amplitude distribution for the pre-correction object light, the reference light, and the reproduction light irradiated when recording hologram data on the hologram recording medium;
A calculation formula representing the complex amplitude distribution of the corrected object light in which the difference in luminance distribution is corrected is set in advance, and the calculation formula and the pre-correction object light, the reference light, and the reproduction light set in advance are set. A corrected object light calculating means for calculating a complex amplitude distribution of the corrected object light based on a complex amplitude distribution;
Hologram data generating means for generating hologram data reflecting the complex amplitude distribution of the corrected object light,
Equipped with a,
The post-correction object light calculation means includes a complex amplitude distribution of the pre-correction object light represented by an amplitude A _O and a phase φ _O for each pixel position (x, y) of the hologram recording medium , an amplitude _AR, and Substituting the complex amplitude distribution of the reference light represented by the phase φ _R and the complex amplitude distribution of the reproduction light represented by the amplitude A _P and the phase φ _P into the equation (4) as the calculation formula so,

A hologram data generation apparatus that calculates a complex amplitude distribution C of the corrected object light . When the reproduction light source is a plurality of point light sources, the complex amplitude distribution calculation means calculates a sum of complex amplitude distributions obtained from each point light source as one complex amplitude distribution of the reproduction light. The hologram data generation device according to claim 1 or 2 . When the light source of the reproduction light is a line light source or a surface light source, the complex amplitude distribution calculation unit presets the line light source or the surface light source as a set of point light sources, and calculates a complex amplitude distribution obtained from each point light source. hologram data generating apparatus according to claim 1 or claim 2, characterized in that for calculating the total sum as a complex amplitude distribution of one of said reproducing light. A hologram data generation program for causing a computer to function as the hologram data generation apparatus according to any one of claims 1 to 4 .

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