WO2014129578A1 - Dispositif de préparation de données et procédé de préparation de données pour hologramme informatique - Google Patents

Dispositif de préparation de données et procédé de préparation de données pour hologramme informatique Download PDF

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WO2014129578A1
WO2014129578A1 PCT/JP2014/054132 JP2014054132W WO2014129578A1 WO 2014129578 A1 WO2014129578 A1 WO 2014129578A1 JP 2014054132 W JP2014054132 W JP 2014054132W WO 2014129578 A1 WO2014129578 A1 WO 2014129578A1
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sampling signal
quinkanx
unit
spatial domain
frequency domain
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PCT/JP2014/054132
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English (en)
Japanese (ja)
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川井　清幸
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アルプス電気株式会社
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/04—Processes or apparatus for producing holograms
    • G03H1/08—Synthesising holograms, i.e. holograms synthesized from objects or objects from holograms
    • G03H1/0808—Methods of numerical synthesis, e.g. coherent ray tracing [CRT], diffraction specific
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/04—Processes or apparatus for producing holograms
    • G03H1/08—Synthesising holograms, i.e. holograms synthesized from objects or objects from holograms
    • G03H1/0841—Encoding method mapping the synthesized field into a restricted set of values representative of the modulator parameters, e.g. detour phase coding
    • G03H2001/085—Kinoform, i.e. phase only encoding wherein the computed field is processed into a distribution of phase differences
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/26—Processes or apparatus specially adapted to produce multiple sub- holograms or to obtain images from them, e.g. multicolour technique
    • G03H1/30—Processes or apparatus specially adapted to produce multiple sub- holograms or to obtain images from them, e.g. multicolour technique discrete holograms only
    • G03H2001/303—Interleaved sub-holograms, e.g. three RGB sub-holograms having interleaved pixels for reconstructing coloured holobject
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H2210/00—Object characteristics
    • G03H2210/40—Synthetic representation, i.e. digital or optical object decomposition
    • G03H2210/45—Representation of the decomposed object

Definitions

  • the present embodiment relates to a data creation apparatus and a data creation method for a computer generated hologram.
  • a recording of interference fringes generated as a result of interference between object light and reference light is known as a hologram.
  • the interference fringes can be obtained by calculation, and if a computer and a display device that displays the interference fringes are provided, a hologram can be synthesized.
  • a hologram is called a computer generated hologram (CGH).
  • this computer generated hologram is that an object for recording does not have to exist. Further, with this computer generated hologram, a three-dimensional image of an imaginary object can be obtained.
  • Such computer generated hologram technology occupies an important position in application fields such as interference measurement, optical information processing, and security.
  • a Fourier transform hologram reproduces an object image in the spatial domain by irradiating a parallel laser beam on a hologram defined in the frequency domain and optically Fourier transforming it through a lens.
  • the hologram data can be obtained from the original image data of the object using fast Fourier transform (FFT).
  • FFT fast Fourier transform
  • the amplitude modulation type is low efficiency
  • the phase modulation type is high efficiency.
  • the diffraction efficiency is theoretically (theoretical) low. It is known that it can be 100%.
  • the diffraction efficiency is defined as the ratio (I 1 / I 0 ) of the first-order diffracted light intensity (I 1 ) to the intensity (I 0 ) of the reproduction illumination light incident on the hologram.
  • phase modulation type SLM information originally expressed by amplitude and phase is approximated by only the phase.
  • phase modulation hologram data since the creation of phase modulation hologram data requires nonlinear processing, the best solution cannot be obtained analytically with a phase modulation SLM.
  • Patent Document 1 a method of creating a computer generated hologram that realizes target accuracy (error) by repeating Fourier transform and inverse Fourier transform has been disclosed (for example, Patent Document 1). reference).
  • optimization processes for phase modulation type Fourier transform holograms are known as optimization processes for phase modulation type Fourier transform holograms. Since these are techniques for increasing the accuracy of phase modulation by non-linear iterative processing and optimizing it, for example, it requires 10 or more iterations, and in some cases several hundreds of iterations. , Increased in proportion to the number of pixels.
  • the computer generated hologram data generation apparatus acquires an original image, converts the acquired original image into a real quinkanks sampling signal, and synthesizes the real quinkanks sampling signal.
  • a spatial domain condition setting unit that generates a spatial domain complex quinkunk sampling signal with an amplitude adjusted based on the spatial domain complex quinkunk sampling signal, and the spatial domain complex quinkunk sampling received from the spatial domain condition setting unit
  • a spatial domain decomposition unit that decomposes a signal into a rectangular sampling signal, an inverse transformation unit that independently performs inverse fast Fourier transform on the rectangular sampling signal decomposed by the spatial domain decomposition unit, and the inverse transformation unit
  • Inverse frequency Fourier transformed rectangular sampling signal in frequency domain A frequency domain synthesizing unit that generates a frequency domain complex quinkanx sampling signal, a frequency domain condition setting unit that replaces the amplitude value of the frequency domain complex quinkanx sampling signal with a predetermined value, and the amplitude value is predetermined.
  • the frequency domain decomposition unit that decomposes the frequency domain complex quinkanx sampling signal replaced with the value of into the square sampling signal, and the fast sampling frequency analysis for the rectangular sampling signal decomposed by the frequency domain decomposition unit
  • a spatial domain synthesis unit that synthesizes a rectangular sampling signal fast Fourier transformed by the transformation unit to generate the synthesized spatial domain complex quinkanx sampling signal and gives the spatial domain condition setting unit Prepare.
  • Explanatory drawing which shows an example of the reproducing
  • 1 is an overall configuration diagram showing an example of a data generation device for a phase modulation type computer generated hologram according to a first embodiment.
  • a phase modulation data creation apparatus for creating phase modulation data of a computer generated hologram by performing fast Fourier transform or the like on a reproduced image to be acquired by the phase modulation type computer generated hologram data generation apparatus according to the first embodiment.
  • Explanatory drawing which showed the data structure before and behind the conversion which the acquired image conversion part converted with respect to the original image.
  • Explanatory drawing which shows the characteristic in the frequency domain at the time of performing an inverse fast Fourier transform with respect to the image converted into the quinkanx sampling signal.
  • Explanatory drawing which showed the data structure in case a spatial domain decomposition part decomposes
  • Explanatory drawing which shows the spectrum characteristic in the frequency domain which the inverse transformation part performed reverse fast Fourier transformation each independently with respect to two decomposed
  • combination part is the explanatory drawing which showed the state which synthesize
  • FIG. 10 is an explanatory diagram illustrating an example in which a display position adjuster multiplies data of two rectangular sample structures by a phase term and a spatial light modulator displays a reproduced image in the second embodiment.
  • the computer generated hologram data creation apparatus when creating phase modulation hologram data (also called kinoform), performs fast Fourier transform (Fast Fourier Transform: FFT) and inverse fast Fourier transform (Inverse Fast Fourier). This is to reduce the amount of calculation when iterating (Transform: IFFT).
  • FFT Fast Fourier Transform
  • IFFT inverse fast Fourier transform
  • the computer generated hologram data creation apparatus can reduce the amount of calculation in the reproduction apparatus of the phase modulation type Fourier transform holography constituted by the existing technology. Therefore, in order to show that the computer generated hologram data creation apparatus according to the present embodiment can reduce the amount of calculation in the reproduction apparatus of the phase modulation type Fourier transform holography constituted by the existing technology, the iterative Fourier transform algorithm is used. First, I will explain.
  • FIG. 1 is an explanatory diagram showing an example of a reproduction apparatus 400 for phase modulation type Fourier transform holography.
  • a phase modulation type Fourier transform holography reproducing device 400 includes a coherent light source 300, a phase modulation type spatial light modulator 310, a Fourier transform optical lens 320, a focal plane 330, a data creation device 100, and the like. It is configured.
  • the coherent light source 300 includes a laser 301, an optical lens 302, and the like.
  • the optical lens 302 is an optical element for improving the quality of projection so that the light emitted from the laser 301 becomes plane wave light with respect to the phase modulation spatial light modulator 310.
  • the coherent light source 300 includes a laser 301 and an optical lens 302 so that the phase-modulated spatial light modulator 310 is irradiated with parallel light.
  • the phase modulation type spatial light modulator 310 performs phase modulation on the plane wave light having the same phase in the frequency domain.
  • the Fourier transform optical lens 320 optically performs Fourier transform from the frequency domain to the spatial domain, and generates a reproduced image of the spatial domain on the focal plane 330.
  • the data creation device 100 is configured by an information processing device that performs information processing, a personal computer, and the like, and in the phase modulation spatial light modulator 310, phase modulation hologram data (hereinafter, referred to as phase modulation hologram data for performing phase modulation on plane wave light in the frequency domain). This is simply called phase modulation data).
  • phase modulation hologram data for performing phase modulation on plane wave light in the frequency domain. This is simply called phase modulation data.
  • phase modulation data creation process by the data creation device 100 will be briefly described.
  • the frequency domain condition is set to replace the amplitude of the complex modulation data in the frequency domain with 1, distortion (error) occurs with respect to the original information, but phase modulation data can be obtained in form.
  • the frequency domain signal with the amplitude replaced by 1 is subjected to fast Fourier transform, an image (Fourier transform image) represented by a complex number in the spatial domain is obtained.
  • the data creation apparatus 100 repeats the series of processes (one cycle) of the inverse fast Fourier transform, frequency domain condition setting, fast Fourier transform, and spatial domain condition setting described above, so that the real number of the Fourier transform image in the spatial domain is obtained. Amplitude distortion (error) with respect to the original image is reduced. Specifically, the above series of processing is repeated until the distortion (error) of the amplitude reaches the target value.
  • the phase data in the frequency domain when the amplitude distortion (error) reaches a target value (for example, the error is within a predetermined threshold) is given to the phase modulation spatial light modulator 310 as phase modulation data.
  • the real original image data in the spatial domain is replaced with the amplitude of the complex data, but the phase initial value of the spatial domain complex number is set so that the data is evenly distributed in the frequency domain. Is set to a random value.
  • this cycle is performed 10 times or more (in some cases several hundred times).
  • the main calculation in this case is “fast Fourier transform / inverse fast Fourier transform”.
  • the number of additions / times of fast Fourier transform or inverse fast Fourier transform of the number of pixels N ⁇ M is represented by 5 (N ⁇ M) log 2 ⁇ (N ⁇ M) ⁇ . . Further, if the above cycle is performed K times, 10K (N ⁇ M) log 2 ⁇ (N ⁇ M) ⁇ is obtained. Therefore, it is approximately proportional to the number of pixels MN.
  • the computer generated hologram data creation apparatus 100 converts the acquired reproduced image (original image) of N ⁇ M pixels into a spatial domain complex quinkanx sampling signal of (N ⁇ M) / 2 pixels. And transforming the converted space-domain complex quinkanx sampling signal into a square sampling signal, and performing inverse fast Fourier transform on each of the decomposed square sampling signals independently, thereby reducing the computation load. To reduce.
  • FIG. 2 is an overall configuration diagram showing an example of a data generation apparatus 100 for a phase modulation type computer generated hologram according to the first embodiment.
  • the computer generated hologram data creation apparatus 100 includes an acquired image conversion unit 110, a spatial domain condition setting unit 115, a spatial domain decomposition unit 120, an inverse transformation unit 125, a frequency domain synthesis unit 130, and a frequency domain condition setting.
  • the data creation device 100 may be configured to include a data conversion unit 160 as shown in FIG. 2, and may further include a phase modulation type spatial light modulator 310.
  • the acquired image conversion unit 110 has a function of acquiring an original image and converting the acquired original image into a real number quinkanx sampling signal (see FIG. 4B).
  • the acquired original image data and the amplitude of the real quinkanx sampling signal are stored in, for example, a predetermined storage medium included in the data creation device 100.
  • the spatial domain condition setting unit 115 replaces the amplitude of the Fourier-transformed spatial domain complex quinkanx sampling signal (spatial domain complex quinkanx sampling signal) with the amplitude of the real quinkanx sampling signal.
  • the initial value phase gives a random phase (or alternately 0, ⁇ ). It is assumed that the phase other than the initial value maintains the phase of the signal received from the conversion unit 150.
  • the spatial domain decomposition unit 120 has a function of decomposing the converted spatial domain complex quinkanx sampling signal into a rectangular sampling signal.
  • the spatial domain decomposition unit 120 can decompose the spatial domain complex quinkanx sampling signal into, for example, two rectangular sampling signals (see FIGS. 6A to 6C). Further, the square sampling signal includes a square sampling signal.
  • the inverse transform unit 125 has a function of independently performing inverse fast Fourier transform on the rectangular sampling signal decomposed by the space domain decomposition unit 120.
  • the inverse transform unit 125 includes an inverse fast Fourier transform unit 126 and an inverse fast Fourier transform unit 127.
  • the inverse fast Fourier transform unit is applied to one of the rectangular sampling signals that are decomposed into two.
  • 126 performs inverse fast Fourier transform
  • the inverse fast Fourier transform unit 127 performs inverse fast Fourier transform on the other rectangular sampling signal.
  • the frequency domain synthesizing unit 130 has a function of synthesizing rectangular sampling signals, which are separately subjected to inverse fast Fourier transform, into one in the frequency domain.
  • the frequency domain decomposition unit 140 can decompose the frequency domain synthesized signal into, for example, two rectangular sampling signals similar to those shown in FIGS. Further, the square sampling signal includes a square sampling signal.
  • the conversion unit 150 has a function of performing fast Fourier transform independently on each of the rectangular sampling signals decomposed by the frequency domain decomposition unit 140.
  • the transform unit 150 includes a fast Fourier transform unit 151 and a fast Fourier transform unit 152, and the fast Fourier transform unit 151 performs fast Fourier transform on one of the square sampling signals that are decomposed into two.
  • the fast Fourier transform unit 152 performs fast Fourier transform on the other rectangular sampling signal.
  • the spatial domain synthesis unit 155 synthesizes the fast sampling-transformed rectangular sampling signal and gives it to the spatial domain condition setting unit 115.
  • the spatial domain condition setting unit 115 determines whether or not the amplitude of the spatial domain complex quinkanx sampling signal synthesized by the spatial domain synthesis unit 155 matches the amplitude of the real quinx sampling signal acquired by the acquired image conversion unit 110. judge. This determination may be replaced with a determination as to whether or not the mutual amplitude error has reached a preset target value (for example, within a predetermined threshold).
  • the amplitude of the spatial domain complex quinkanx sampling signal synthesized by the spatial domain synthesizing unit 155 is used as the real number quinkanx sampling acquired by the acquired image converting unit 110. It replaces with the amplitude of the signal and gives it to the space domain decomposition unit 120 again.
  • the phase modulation spatial light modulator 310 has a function of controlling the spatial phase distribution of light by receiving coherent plane wave light and changing the phase in units of pixels.
  • the spatial light modulator is often a pixel array having a rectangular region. Therefore, in order to display a pixel region having a diamond-shaped region as shown in FIG. 5, the data conversion unit 160 converts data outside the diamond-shaped region in the rectangular region to zero. Based on the output data of the data converter 160, the phase modulation spatial light modulator 310 gives a spatial phase distribution of light to a plane wave of coherent light.
  • Phase modulation data creation process Next, the operation of the phase modulation data creation processing in the computer generated hologram data creation device 100 according to the first embodiment will be described in detail.
  • FIG. 3 illustrates a phase modulation data creation process in which the computer generated hologram data creation apparatus 100 according to the first embodiment creates phase modulation data of a computer generated hologram by performing, for example, fast Fourier transform on the acquired original image. It is the flowchart which showed the procedure. In FIG. 3, a symbol with a number added to S indicates each step of the flowchart.
  • the computer generated hologram data creation apparatus 100 acquires an original image a (original image taking an amplitude value a) in the acquired image conversion unit 110, and converts the acquired original image a into a real quinkanx sampling signal. (Step S001).
  • an original image a original image taking an amplitude value a
  • the computer generated hologram data creation apparatus 100 acquires an original image a (original image taking an amplitude value a) in the acquired image conversion unit 110, and converts the acquired original image a into a real quinkanx sampling signal.
  • FIG. 4 is an explanatory diagram showing the structure before and after conversion, in which the acquired image conversion unit 110 converts the original image a.
  • FIG. 4A shows an N ⁇ M rectangular sample structure in which the original image a is displayed as an image of 6 ⁇ 6 samples as an example.
  • the original image a is a sampling signal having an N ⁇ M rectangular sample structure
  • the acquired image conversion unit 110 converts the sampling signal of the N ⁇ M rectangular sample structure into a quincunx shape (5 dice). Sub-sampling).
  • FIG. 4B shows, as an example, a sampling structure in which the original image a is converted into a real quinkanx sampling signal. Specifically, the vertical component and the horizontal component of the original image a are thinned out by one sample.
  • the method of thinning out one sample at a time can be converted into a real quinkanx sampling signal by assigning 0 to the thinned data.
  • FIG. 5 is an explanatory diagram showing characteristics in the frequency domain when an inverse Fourier transform is performed on an image converted into a real quinkanx sampling signal in the first embodiment. .
  • N and M are obtained in the frequency domain for an image converted into a real quinkanx sampling signal, indicating that the characteristics of the horizontal resolution and the vertical resolution are not changed.
  • the acquired image conversion unit 110 sends the converted real quinkanx sampling signal to the spatial domain condition setting unit 115.
  • the spatial domain decomposition unit 120 decomposes the converted spatial domain complex quinkanx sampling signal into two rectangular samplings (step S005).
  • FIG. 6 is an explanatory diagram showing a data structure when the spatial domain decomposition unit 120 decomposes the converted spatial domain complex quinkanx sampling signal into two rectangular sampling signals.
  • FIG. 6 (a) shows a spatial domain complex quinkanx sampling signal.
  • the spatial domain decomposition unit 120 decomposes the spatial domain complex quinkanx sampling signal every other row in units of rows.
  • FIG. 6 (b) and 6 (c) show the data structure decomposed by the space domain decomposition unit 120.
  • the inverse transform unit 125 performs inverse fast Fourier transform on each of the two rectangular sampling signals decomposed by the space domain decomposition unit 120 independently (step S007). Since the inverse transform unit 125 includes the inverse fast Fourier transform unit 126 and the inverse fast Fourier transform unit 127, the inverse transform unit 125 performs one square sampling signal decomposed into two (for example, a circle in FIG. 6B). ), The inverse fast Fourier transform unit 126 performs the inverse fast Fourier transform, and the inverse fast Fourier transform unit 127 performs the inverse fast Fourier transform on the other rectangular sampling signal (for example, ⁇ mark in FIG. 6C). Do.
  • FIG. 7 is an explanatory diagram showing spectral characteristics in the frequency domain in which the inverse transform unit 125 independently performs inverse fast Fourier transform on two decomposed rectangular sampling signals.
  • FIG. 7A shows the spectral characteristics of the frequency domain obtained by performing the inverse fast Fourier transform by the inverse fast Fourier transform unit 126 on the rectangular sampling signal indicated by a circle in FIG. Show.
  • FIG. 7B shows the spectral characteristics of the frequency domain obtained by performing the inverse fast Fourier transform on the rectangular sampling signal indicated by ⁇ in FIG. 6C by the inverse fast Fourier transform unit 127.
  • the number of times of inverse fast Fourier transformation for two (N / 2) ⁇ (M / 2) is 2 ⁇ 5 (N / 2) ⁇ (M / 2) log 2 ⁇ (N / 2) ⁇ (M / 2) ⁇ . That is, in the data creation device 100 according to the first embodiment, the amount of calculation related to addition and multiplication of the inverse fast Fourier transform is approximately halved.
  • the computer generated hologram data creation apparatus 100 when performing inverse fast Fourier transform, it is possible to reduce the calculation amount per time to about half the calculation amount.
  • the frequency domain synthesizer 130 synthesizes two rectangular sampling signals subjected to inverse fast Fourier transform into one in the frequency domain (step S009).
  • the computer generated hologram data generation apparatus 100 generates a frequency domain composite signal (frequency domain complex quinkanx sampling signal) of the original quinkanx data.
  • FIG. 8 is an explanatory diagram showing a state in which the frequency domain synthesis unit 130 synthesizes two rectangular sampling signals into one in the frequency domain.
  • the frequency domain decomposition unit 140 decomposes the frequency domain synthesized signal replaced with a predetermined value in the frequency domain condition setting unit 135 into a rectangular sampling signal (step S013).
  • the added signals shown in FIG. 8 (c) are two (N / 2) ⁇ (M / 2) signals. It is shown that it is decomposed. Specifically, N / 2 to N data centered on N / 2 are added back to the low frequency side from the added signal (N ⁇ M signal) shown in FIG.
  • the reason why only one data is multiplied by a phase corresponding to one pixel movement in the N ⁇ M space is to correct a shift of one pixel in the spatial domain in the frequency domain.
  • the reason for performing the folding addition is that the high frequency component is folded in order to prevent the information contained in the N ⁇ M signal from being erased.
  • 9A and 9B show a state in which the N ⁇ M signal is added back to the (N / 2) ⁇ (M / 2) signal, but FIG. Only the multiplication corresponding to one pixel movement in the N ⁇ M space is multiplied, and then the folding addition is performed.
  • the conversion unit 150 performs fast Fourier transform on the two rectangular sampling signals decomposed by the frequency domain decomposition unit 140 independently (step S015).
  • the fast Fourier transform unit 151 performs fast Fourier transform on the rectangular sampling signal of FIG. 9A
  • the fast Fourier transform unit 152 performs fast Fourier transform on the rectangular sampling signal of FIG. 9B. ing.
  • FIG. 10 is an explanatory diagram illustrating a state in which the conversion unit 150 independently performs fast Fourier transform on the two decomposed rectangular sampling signals.
  • FIG. 10 (a) shows a state in which fast Fourier transform is performed on the signal (N / 2) ⁇ (M / 2) shown in FIG. 9 (a).
  • FIG. 10B shows a state in which fast Fourier transform is performed on the (N / 2) ⁇ (M / 2) signal shown in FIG. 9B.
  • the space domain synthesis unit 155 synthesizes two rectangular sampling signals that have been subjected to the fast Fourier transform in the transformation unit 150 (step S017).
  • FIG. 11 is an explanatory diagram showing a state in which the space domain synthesis unit 155 synthesizes two rectangular sampling signals subjected to fast Fourier transform.
  • the spatial domain synthesis unit 155 is shifted by one pixel with respect to the two rectangular sampling signals (FIGS. 10A and 10B) subjected to the fast Fourier transform by the conversion unit 150. Synthesized into a complex quinkanx shape. Then, the synthesized spatial domain complex quinkanx sampling signal is sent to the spatial domain condition setting unit 115, and it is determined whether the amplitude coincides with the real quinkanx sampling signal.
  • the spatial domain condition setting unit 115 determines whether or not the amplitude of the synthesized spatial domain complex quinkanx sampling signal matches the amplitude of the real quinkanx sampling signal (step S019), and the synthesized spatial domain complex quinn. If the amplitude of the Kanks sampling signal matches that of the real quinkanx sampling signal (YES in step S019), the frequency domain synthesized signal is sent to the data converter 160.
  • the data converter 160 rearranges the data into the diamond shape shown in FIG. 5 and causes the phase modulation spatial light modulator 310 to drive the rearranged data. Then, the phase modulation spatial light modulator 310 performs phase modulation of light (illumination) (step S021).
  • step S019 if the amplitude of the spatial domain complex quinkanx sampling signal does not match the amplitude of the real quinkanx sampling signal (NO in step S019), the process proceeds to step S003, where the spatial domain condition setting unit 115 Replace the amplitude of the quinkanx sampling signal with the amplitude of the real quinkanx sampling signal.
  • the spatial domain complex quinkanx sampling signal synthesized by the spatial domain synthesis unit 155 is decomposed into two rectangular sampling signals by the spatial domain decomposition unit 120 and repeated until they match in step S019.
  • the acquired original image is converted into a spatial domain complex quinkanx sampling signal, and the converted spatial domain complex quinkanx sampling signal is converted into a rectangular parallelepiped.
  • the signal is decomposed into sampling signals, and inverse fast Fourier transform is performed independently for each of the decomposed rectangular sampling signals.
  • the computer generated hologram data creation apparatus 100 performs the inverse fast Fourier transform by the inverse transform unit 125 or the fast Fourier transform by the transform unit 150 after the spatial domain complex quinkanx sampling signal is squarely sampled. Therefore, the calculation amount can be reduced to about half of the calculation amount as compared with the data generation device of the conventional phase modulation type Fourier transform holography.
  • illumination efficiency can be increased as a secondary effect.
  • FIG. 12 is an explanatory diagram illustrating the relationship between the laser 301 having an elliptical light source (FIG. 1) and the phase modulation spatial light modulator 310 (FIG. 1) in the first embodiment.
  • (theta) is the angle
  • the illumination efficiency is constant regardless of the aspect ratio.
  • the illumination efficiency is 1.25 times higher in the rhombus area.
  • FIG. 13 is an overall configuration diagram showing an example of a computer generated hologram data creation apparatus 200 according to the second embodiment.
  • the computer generated hologram data creation apparatus 200 according to the second embodiment is substantially the same as the computer generated hologram data creation apparatus 100 according to the first embodiment shown in FIG.
  • the overall structure is the same, and the procedure for creating rank / BR> tone data is the same.
  • the difference between the computer generated hologram data creation device 200 according to the second embodiment and the computer generated hologram data creation device 100 according to the first embodiment is displayed instead of the data conversion unit 160 of the first embodiment.
  • the position adjuster 170 is provided.
  • the configuration is the same as that of the computer generated hologram data creation apparatus 100, and therefore, the same reference numerals are given and description thereof is omitted as appropriate.
  • the display position adjuster 170 adjusts reproduction of an original image using data of a rectangular sample structure created by an iterative Fourier transform algorithm (iterative Fourier transform method).
  • the phase modulation spatial light modulator 310 uses the adjusted data of the rectangular sample structure to drive the frequency domain rectangular sampling signal.
  • FIG. 14 shows an example in which the display position adjuster 170 multiplies data of two rectangular sample structures by the phase term and the phase modulation spatial light modulator 310 displays a reproduced image in the second embodiment. It is explanatory drawing.
  • FIG. 14A shows that the phase modulation spatial light modulator 310 drives two different rectangular areas in the frequency domain.
  • the display position adjuster 170 adjusts the display position by multiplying the data of two rectangular sample structures by an appropriate phase term, and is displayed in the same spatial region with a quinkanx pixel arrangement. It shows that two different rectangular regions adjusted in this way are driven by the phase modulation spatial light modulator 310.
  • each step of the flowchart shows an example of processing that is performed in time series in the order described.
  • the process to be executed is also included.
  • Data creation device 110 Acquisition image conversion unit 115 Spatial domain condition setting unit 120 Spatial domain decomposition unit 125 Inverse transform unit 126, 127 Inverse fast Fourier transform unit 130 Frequency domain synthesis unit 135 Frequency domain condition setting unit 140 Frequency domain decomposition unit 150 Conversion Units 151, 152 Fast Fourier Transform Unit 155 Spatial Domain Synthesis Unit 160 Data Conversion Unit 170 Display Position Adjuster 301 Laser 302 Optical Lens 300 Coherent Light Source 310 Phase Modulation Spatial Light Modulator (Spatial Light Modulator) 320 Fourier transform optical lens 330 focal plane

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Abstract

La présente invention a pour objet de pourvoir à un dispositif de préparation de données et à un procédé de préparation de données pour un hologramme informatique aptes à réduire la quantité de calculs. Le dispositif de préparation de données pour hologramme informatique selon le présent mode de réalisation comprend : une unité de conversion d'image acquise qui acquiert une image originale et convertit l'image en un signal d'échantillonnage en quinconce réel ; une unité de réglage de condition du domaine spatial pour générer un signal d'échantillonnage en quinconce de nombre complexe du domaine spatial ; une unité de décomposition dans le domaine spatial pour décomposer le signal d'échantillonnage en quinconce de nombre complexe du domaine spatial ; une unité de conversion inverse pour appliquer une transformation de Fourier inverse respectivement aux signaux décomposés ; une unité de synthèse dans le domaine fréquentiel pour synthétiser les signaux soumis à la transformation de Fourier inverse ; une unité de réglage de condition du domaine fréquentiel pour remplacer la valeur d'amplitude du signal synthétisé par une valeur prescrite ; une unité de décomposition dans le domaine fréquentiel pour décomposer le signal de synthèse ayant la valeur d'amplitude remplacée par la valeur prescrite ; une unité de conversion pour appliquer une transformation de Fourier aux signaux d'échantillonnage décomposés ; et une unité de synthèse dans le domaine spatial pour synthétiser les signaux d'échantillonnage soumis à la transformation de Fourier.
PCT/JP2014/054132 2013-02-25 2014-02-21 Dispositif de préparation de données et procédé de préparation de données pour hologramme informatique WO2014129578A1 (fr)

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JP2013034989A JP6101109B2 (ja) 2013-02-25 2013-02-25 計算機ホログラムのデータ作成装置及びそのデータ作成方法
JP2013-034989 2013-02-25

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