JP2014203029A - Data generation device of fourier transform hologram - Google Patents

Abstract

A Fourier transform hologram data creation device that realizes a multi-color hologram without a reduction in conversion efficiency or resolution with a single spatial light modulator. A Fourier transform hologram data creation device according to an embodiment of the present invention is a data creation device that creates data to be supplied to a single spatial light modulator used in a multi-color reproduction device of a Fourier transform hologram. The resolution of the reproduced image is set for each color, and based on the set resolution, the pixel number converting means for distributing the number of pixels for each color, and the phase modulation data in the frequency domain according to the allocated number of pixels Phase modulation data creation means for each color and the pixel area of the spatial light modulator are divided for each color, and the phase modulation data is rearranged for each corresponding color for each of the divided pixel areas. And data rearranging means for creating data to be supplied to the spatial light modulator. [Selection] Figure 2

Description

  The present embodiment relates to a data creation apparatus for a Fourier transform hologram.

  Currently, projectors that attempt to reproduce the natural color of an object are known. The projector is an additive color mixture with three primary colors of red, green, and blue, and a color image is generated by superimposing light of each color.

  Here, a general projector has a total of three spatial modulators of red, green, and blue, and a method of synthesizing with a dichroic mirror is known. Such a projector requires a complex optical element in addition to the three spatial light modulators, and requires a complex optical element of red, green, and blue. In addition, there is a method of configuring a projector with a single spatial light modulation element by combining each pixel with an RGB color filter, but there are few practical examples because the conversion efficiency decreases and the resolution also decreases with the color filter. It was.

  On the other hand, it is known that a highly efficient projector can be configured by applying holography using multi-level phase modulation. A projector in which red, green, and blue full-color holography is combined with three spatial light modulators and means for combining three colors is also disclosed (for example, see Patent Document 1).

JP 2009-53234 A

  As described above, a general color hologram has three spatial modulators of red, green, and blue, and the modulation signal is synthesized by a dichroic mirror by a synthesis optical system, so that it has a complicated configuration. It was.

  In addition, a color sequential method is known in which time division processing is performed using one spatial light modulator and color modulation is switched in units of time. However, a spatial light modulator that operates at high speed is necessary. . Specifically, in order to switch the colors of red, green, and blue, 3 × speed (180 Hz) is necessary for calculation. However, in reality, the 3 × speed is visually insufficient, so 6 × speed ( 360 Hz) or more.

  This is because, in the case of a fast moving object, a color break phenomenon occurs in which the colors of red, green, and blue located at the edge are shifted and viewed. Similarly, when a person viewing in a still image moves his / her line of sight, a phenomenon may occur in which the colors red, green, and blue are shifted and viewed.

  For this reason, an optical element for synthesizing red, green and blue is not required, and a spatial light modulator that operates at high speed is not required. There has been a demand for an apparatus for creating data of a Fourier transform hologram that realizes a multi-color hologram without deterioration.

  A Fourier transform hologram data creation device according to the present embodiment is a data creation device that creates data to be supplied to a single spatial light modulator used in a multi-color playback device of a Fourier transform hologram. Is set for each color, and based on the set resolution, the pixel number conversion means for distributing the number of pixels for each color, and the phase modulation data in the frequency domain according to the allocated number of pixels for each color The phase modulation data creation means to create and the pixel area of the spatial light modulator are divided for each color, and the phase modulation data is rearranged for each corresponding color and arranged for each of the divided pixel areas. Data rearranging means for creating data to be supplied to the spatial light modulator.

The schematic block diagram which showed the schematic structure of the reproducing | regenerating apparatus of phase modulation type Fourier-transform holography. The functional block diagram which showed the function of the reproducing | regenerating apparatus of Fourier-transform holography. Explanatory drawing which showed the concept of each process in the reproduction | regeneration apparatus of Fourier-transform holography. Explanatory drawing which showed the distribution pixel number in the horizontal resolution of a reproduced image. The functional block diagram which showed the function of Example 2 of the reproducing | regenerating apparatus of Fourier-transform holography. The structure of the image data when the reduction / enlargement pixel number conversion means converts N × M samples into N × (M / 2) samples with a RGB sampling ratio of 4: 2: 2 for each original image data. FIG. The green (G) phase modulation data composed of N × M samples and the blue (B) and red (R) phase modulation data composed of N × M samples are converted into phase modulation spatial light modulators. Explanatory drawing when making it drive to a pixel area by a time division.

  The Fourier transform hologram data creation apparatus according to the present embodiment realizes multi-color Fourier transform holography using one (or one) spatial light modulator.

  Hereinafter, a Fourier transform holography reproducing device will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram showing a schematic configuration of a reproduction apparatus 300 for phase modulation type Fourier transform holography.

  As shown in FIG. 1, a Fourier transform holography reproducing device 300 includes a coherent light source 100, a phase modulation spatial light modulator 110, a Fourier transform optical lens 120, a data creation device 200, and the like. The coherent light source 100 includes a laser 101 and an optical lens 102.

  The optical lens 102 is a collimating optical element for causing the light emitted from the laser 101 to become plane wave light with respect to the phase modulation spatial light modulator 110.

  The coherent light source 100 includes a laser 101 and an optical lens 102 to irradiate the phase modulation spatial light modulator 110 with parallel light.

  The phase modulation spatial light modulator 110 performs phase modulation in the frequency domain on plane wave light having a uniform phase.

  The Fourier transform optical lens 120 optically performs a Fourier transform from the frequency domain to the spatial domain, and generates a reproduced image of the spatial domain on the focal plane 130.

  The data creation device 200 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 110, phase modulation hologram data (hereinafter, referred to as phase modulation hologram data for performing phase modulation on plane wave light in the frequency domain). Simply referred to as phase modulation data) from the original image data. Note that the data creation device 200 is configured to send the created phase modulation data to the phase modulation spatial light modulator 110 when the phase modulation data is created.

  The schematic operation of the Fourier transform holography reproducing apparatus 300 shown in FIG. 1 is to collimate the coherent light emitted by the laser 101 by the optical lens 102 to generate plane wave light. The plane wave light is subjected to phase modulation in the frequency domain using the phase modulation spatial light modulator 110. Thereafter, the phase-modulated light is subjected to optical Fourier transform by the Fourier transform optical lens 120, and a reproduced image is generated on the focal plane 130 which is a spatial region.

Example 1
In terms of human visual characteristics, green (G) has higher visibility in terms of resolution than blue (B) and red (R). Conversely, since it is difficult to detect a decrease in the resolution of blue (B) or red (R) compared to the resolution of green (G), the resolution of blue (B) or red (R) is intentionally set low. can do.

  In addition, the size of a reproduced image by holography differs depending on the wavelength (color). For example, assuming that the pixel pitch of the phase modulation spatial light modulator 110 is p, the wavelength of light λ, and the focal length of the Fourier transform optical lens 120 is f, the displayed size of the reproduced image is represented by λf / p. The

  Therefore, since the wavelength becomes longer in the order of blue (B), green (G), and red (R), the display size of the reproduced image increases in this order.

  Here, in order to make the reproduced image have the same size for each color, it is conceivable to correct the size of the original image data in advance. For example, when green (G) is used as a reference, blue (B) original image data is expanded in advance according to a wavelength ratio, and red (R) original image data is reduced in advance according to a wavelength ratio. As a result, the sizes of the reproduced images of the respective colors can be matched.

  Therefore, the Fourier transform holography reproducing device 300 shown in FIG. 1 has the following configuration by including a coherent light source 100, a phase modulation spatial light modulator 110, a Fourier transform optical lens 120, and a data creation device 200. Such functional blocks can be configured.

  FIG. 2 is a functional block diagram showing functions of the reproduction apparatus 301 for Fourier transform holography.

  As shown in FIG. 2, the Fourier transform holography reproducing device 301 includes a coherent light source 100, a data creation device 201, a phase modulation spatial light modulator 110, and an optical Fourier transform 121. In addition, the same code | symbol is attached | subjected to the same structure and description is abbreviate | omitted suitably.

  The data creation device 201 includes reduction / enlargement pixel number conversion means (pixel number conversion means) 240 and 241, phase modulation data creation means 210, 211, and 212, and data rearrangement means 230. Note that the data creation device 201 includes an information processing device that performs information processing, a personal computer, and the like.

  The reduced / enlarged pixel number conversion means 240, 241 has a function of setting the resolution of the reproduced image in the spatial region for each color and allocating the number of pixels for each color based on the set resolution. That is, the reduction / enlargement pixel number conversion means 240, 241 performs color matching in the spatial domain so as to match the RGB pixel area of the preset frequency domain from the RGB signal of the original image data stored in the data creation device 201. In addition, pixel number conversion processing for reducing and enlarging the original image data (this is also referred to as reduction / enlargement pixel number conversion processing) is performed. Note that when describing three colors of green (G), blue (B), and red (R), they may be simply expressed as RGB.

  The phase modulation data creation means 210, 211, and 212 have a function of creating phase modulation data in the frequency domain for each color in accordance with the allocated number of pixels. Specifically, the pixel number conversion processing for reducing and enlarging the original image data in the reduction / enlargement pixel number conversion means 240 and 241 performs Fourier transform on the number of pixels for each color, respectively, in the frequency domain. Phase modulation data is generated. For example, the phase modulation data generation unit 210 generates green (G) phase modulation data, the phase modulation data generation unit 211 generates blue (B) phase modulation data, and the phase modulation data generation unit 212 Red (R) phase modulation data is generated.

  The data rearrangement unit 230 has a function of writing the phase modulation data generated by the phase modulation data generation units 210, 211, and 212 into the phase modulation spatial light modulator 110. Specifically, the data rearranging unit 230 divides the pixel area of the phase modulation spatial light modulator 110 for each color, and arranges the phase modulation data for each corresponding color for each of the divided pixel areas. The data to be supplied to the phase modulation type spatial light modulator 110 is created by arranging them in place.

  Next, a concept until the reproduction apparatus 301 of Fourier transform holography shown in FIG. 2 reproduces a reproduced image from original image data will be described. In addition, in order to clarify the content of an Example, it demonstrates using a one-dimensional image as an example.

  FIG. 3 is an explanatory diagram showing the concept of each process in the reproduction apparatus 301 for Fourier transform holography.

  In the RGB original image data, all colors are represented by 5 pixels. Here, when green (G) is used as a reference in order to correct the influence of the wavelength when reproducing holography, red (R) is reduced to a size of three pixels. Blue (B) is enlarged to a size of 7 pixels, but the pixels are thinned out to 3 pixels.

  As described above, the reduction / enlargement pixel number conversion means 240, 241 performs the pixel number conversion process for reducing / enlarging the original image data, and the size of red (R) and blue (B) is 3 pixels, and green. The number of pixels is converted so that (G) has a size of 5 pixels. That is, the reduction / enlargement pixel number conversion means 240, 241 converts the red original image data and the blue original image data based on the wavelength in the reproduction image so as to have the same size as the green original image data in the reproduction image. Reduce or enlarge.

  The phase modulation data creation means 210, 211, 212 are frequency regions corresponding to each of image data composed of 3 pixels of red (R) and blue (B) and 5 pixels of green (G). The phase modulation data at is generated.

  The data rearranging unit 230 writes the generated phase modulation data in the phase modulation spatial light modulator 110. The Fourier transform optical lens 120 optically performs an optical Fourier transform 121 from the frequency domain to the spatial domain, and a reconstructed image in which red (R) and blue (B) are 3 pixels and green (G) is 5 pixels. Are generated on the focal plane 130.

  This process flow is the concept of each process in the reproduction apparatus 301 for Fourier transform holography.

  By the way, the reduction / enlargement pixel number conversion means 240 and 241 perform thinning when performing the pixel number conversion processing. The pixel number conversion processing will be described in detail.

  The reduction / enlargement pixel number conversion means 240, 241 distributes the red (R), green (G), and blue (B) pixels (hereinafter, this is allocated) in accordance with the process of changing the number of pixels of the original image data. This is called the number of pixels). Here, regarding the number of allocated pixels, Nr is the number of allocated pixels for red (R), Ng is the number of allocated pixels for green (G), and Nb is the number of allocated pixels for blue (B). Further, the wavelength of red (R) is λr, the wavelength of green (G) is λg, and the wavelength of blue (B) is λb.

  In this case, assuming that the red (R) reproduction image resolution is Rr, the green (G) reproduction image resolution is Rg, the blue (B) reproduction image resolution is Rb, and the green (G) reproduction image resolution Rg is a reference. The reconstructed image resolution of red (R) and blue (B) is expressed by the following equation.

Rr = (Nr / Ng) (λg / λr) Rg
Rb = (Nb / Ng) (λg / λb) Rg (1)

  Here, using the visual characteristics, the pixels so that the red (R) reproduction image resolution Rr and the blue (B) reproduction image resolution Rb are intentionally equal to or less than the green (G) reproduction image resolution Rg. By distributing the number, the phase modulation spatial light modulator 110 can be driven efficiently. In this case, the number of green (G) pixels is preferably equal to or greater than the number of red (R) pixels and the number of blue (B) pixels.

  FIG. 4 is an explanatory diagram showing the number of allocated pixels in the horizontal resolution of the reproduced image. Specifically, in FIG. 4, when λr = 640 nm, λg = 515 nm, and λb = 450 nm, red (R) and blue (B) are reproduced with respect to a green (G) reproduced image horizontal resolution Rg = 500 pix. It is explanatory drawing which showed the distribution pixel number of the horizontal direction when the horizontal resolution of an image is 400 pix (80%).

  Note that the distribution pixel number Ng of green (G) is 500 pix. The reproduced image horizontal resolution refers to the number of pixels included in the horizontal width of the green (G) reproduced image in the spatial region.

  Here, when each of the above numerical values is substituted into the above-described equation (1), the following equation is obtained.

Rr = (Nr / 500) (515) / 640) 500 = 400 (2)
Nr = 400 × 640 / 515≈500 [pix]
Rb = (Nb / 500) (515) / 450) 500 = 400 (3)
Nb = 400 × 450 / 515≈350 [pix]

  As a result, the red (R) distribution pixel number Nr is 500 pix, while the blue (B) distribution pixel number Nb is 350 pix.

  Thus, the number of pixels in the frequency domain (pixel area) can be set in advance from the wavelength and the required resolution. Similarly, the number of allocated pixels can be set in the vertical direction.

(Example 2)
Next, a second embodiment in which the first embodiment is further provided with a time division processing means for performing time division processing will be described.

  FIG. 5 is a functional block diagram showing the function of the second embodiment of the reproduction apparatus 302 for Fourier transform holography.

  In FIG. 5, the time division processing unit 250 is further provided as compared with the first embodiment of the reproduction apparatus 301, while the data rearrangement unit 231 rearranges the phase modulation data of green (G) N × M samples. Has been deleted. In addition, since the other structure is the same structure, the same code | symbol is attached | subjected to the same structure and description is abbreviate | omitted suitably.

  In the second embodiment of the reproduction apparatus 302 for Fourier transform holography shown in FIG. 5, the phase modulation data generating means 210 generates phase modulation data from the number of green (G) N × M samples, and the generated green (G) The phase modulation data is sent to the time division processing means 250.

  In the second embodiment, the RGB original image data is composed of N × M samples in advance, and the red (R) and blue (B) original image data is reduced by the reduction / enlargement pixel number conversion means 240 and 241. It is assumed that the number of pixels is converted into N × (M / 2) samples with a sampling ratio of 4: 2: 2 by the enlargement pixel number conversion process.

  FIG. 6 shows that the reduction / enlargement pixel number conversion means 240 and 241 convert N × M samples into N × (M / 2) samples with a RGB sampling ratio of 4: 2: 2 for each original image data. It is explanatory drawing which showed the structure of the image data in a case. That is, the green (G) phase modulation data is composed of N × M samples, while the red (R) and blue (B) phase modulation data is composed of N × (M / 2) samples. .

  The data rearrangement unit 231 rearranges the phase modulation data for the blue (B) and red (R) N × (M / 2) sample phase modulation data, respectively, and converts the phase modulation data into N × M sample phase modulation data. Deploy.

  The time division processing unit 250 converts the phase modulation data arranged in the pixel area to the green (G) phase modulation data and the rearranged blue (B) and red (R) phase modulation data. The corresponding color is changed every predetermined time. Specifically, the time division processing unit 250 sets the pixel region of the phase modulation spatial light modulator 110 corresponding to green (G) and the rearranged blue (B) and red (R) for a predetermined time. Drive every.

  FIG. 7 shows a phase modulation type space in which green (G) phase modulation data composed of N × M samples and blue (B) and red (R) phase modulation data composed of N × M samples. FIG. 6 is an explanatory diagram when the pixel region of the optical modulator 110 is driven in a time division manner. For example, the predetermined time can be set to 16 ms, 20 ms, or the like.

  As shown in FIG. 7, the reproduction apparatus 302 according to the second embodiment switches between green (G), rearranged blue (B), and red (R), and thus a conventional reproduction apparatus that switches between three colors of RGB. Compared to the above, it is not necessary to switch at high speed, and the computer holography reproducing apparatus 302 can be realized at low cost.

  In the second embodiment, the RGB original image data is composed of N × M samples in advance, and the red (R) and blue (B) original image data is reduced by the reduction / enlargement pixel number conversion means 240 and 241. Although it has been converted to N × (M / 2) samples by the enlargement pixel number conversion process, it is not limited to this. For example, for red (R) and blue (B), the original image data may be composed of N × (M / 2) samples in advance.

  The green (G) original image data is composed of N × M samples, while the red (R) and blue (B) original image data is reduced / enlarged pixels of the reduced / enlarged pixel number conversion means 240 and 241. It may be converted into (N / 2) × M samples by a number conversion process. For example, the original image data of red (R) and blue (B) is previously composed of (N / 2) × M samples. May be.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 100 Coherent light source 101 Laser 102 Optical lens 110 Phase modulation type spatial light modulator 120 Fourier transform optical lens 121 Optical Fourier transform 130 Focal plane 200, 201, 202 Data creation device 210, 211, 212 Phase modulation data creation means 230, 231 data Rearrangement means 240, 241 Reduction / enlargement pixel number conversion means (pixel number conversion processing means)
300, 301, 302 Playback device

Claims (4)

In a data creation device for creating data to be supplied to a single spatial light modulator used in a multi-color reproduction device of a Fourier transform hologram,
A pixel number conversion means for setting the resolution of the reproduced image in the spatial domain for each color and allocating the number of pixels for each color based on the set resolution;
Phase modulation data creating means for creating phase modulation data in the frequency domain for each color according to the allocated number of pixels;
The pixel area of the spatial light modulator is divided for each color, and the phase modulation data is rearranged for each color corresponding to each of the divided pixel areas and supplied to the spatial light modulator. Data rearranging means for creating data to be processed;
A Fourier transform hologram data creation device comprising: The pixel number converting means includes
2. The Fourier according to claim 1, wherein the red original image data and the blue original image data are reduced or enlarged based on a wavelength in the reproduced image so as to have the same size as the green original image data in the reproduced image. Conversion hologram data creation device. The pixel number converting means includes
The number of green pixels of the reproduced image is equal to or greater than the number of red pixels and blue pixels of the reproduced image, and the red reproduced image resolution and the blue reproduced image resolution of the reproduced image are green reproduced. The Fourier transform hologram data creation device according to claim 1 or 2, wherein the number of pixels is distributed so as to be equal to or less than an image resolution. Time division processing means for changing a color corresponding to the phase modulation data arranged for the divided pixel region at predetermined time intervals;
The Fourier transform hologram data creation device according to any one of claims 1 to 3, further comprising:

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