JP7060090B2 - Optical imaging device and image processing method - Google Patents

Description

The present invention relates to an optical imaging apparatus and an image processing method, and more particularly to an optical imaging apparatus and an image processing method for generating a phase distribution image.

Conventionally, an optical imaging device and an image processing method for generating a phase distribution image are known. Such an optical imaging apparatus and an image processing method are disclosed in, for example, International Publication No. 2014/030115.

The X-ray phase difference imaging system disclosed in International Publication No. 2014/030115 is configured to perform X-ray imaging with a Talbot low interferometer and generate a phase distribution image by a fringe scanning method.

Here, in the Talbot-Lago interferometer, imaging is performed using a multi-slit, a phase grid, and an absorption grid. Specifically, any one of the plurality of grids is imaged a plurality of times while being translated in a direction orthogonal to the pattern of the grids. Further, the fringe scanning method is a method of generating a phase contrast image based on a change in the intensity of the pixel value of each pixel of an X-ray image captured a plurality of times while moving the grid in translation. Specifically, the fringe scanning method determines the waveform of the function assuming that the change in the intensity of the pixel value of each pixel of the moire fringes reflected in the X-ray image is the data in each phase of the function of the period of the lattice, and the waveform. Is a method of generating a phase distribution image based on the determined function. The phase distribution image generated by the fringe scanning method includes a phase differential image. In addition, the fringe scanning method can generate an image including an absorption image and a dark field image. The phase differential image is an image imaged based on the phase shift of the X-rays generated when the X-rays pass through the subject. Further, the absorption image is an image imaged based on the attenuation of the X-rays generated when the X-rays pass through the subject. The dark field image is a Visibility image obtained by a change in Visibility based on small-angle scattering of an object. The dark field image is also called a small-angle scattered image. "Visibility" is sharpness.

Although not disclosed in International Publication No. 2014/030115, when a phase distribution image is generated using the fringe scanning method, in order to reduce the noise of the generated phase distribution image, the time for irradiating X-rays is set. It needs to be long. However, when the X-ray irradiation time is lengthened, the lattices thermally fluctuate due to heat generated from an X-ray source or the like, and the relative positions of the lattices are displaced. When the relative position of each grid is displaced, the phase of the moire fringes changes, so that an artifact occurs in the obtained phase distribution image.

In order to suppress the occurrence of such artifacts, a method of generating a phase distribution image by synthesizing a plurality of phase distribution images captured by shortening the irradiation time of X-rays can be considered. In this method, since the X-ray irradiation time is short, it is possible to suppress the influence of the thermal fluctuation of the lattice when generating each phase distribution image as much as possible. Therefore, it is possible to suppress the change in the phase of the moire fringes due to the thermal fluctuation of the lattice. Further, since a plurality of phase distribution images are integrated or averaged, the noise of the finally obtained phase distribution image can be reduced.

International Publication No. 2014/030115

However, even in the method of synthesizing a plurality of phase distribution images captured by shortening the irradiation time of X-rays as described above to obtain one phase distribution image, the phase distribution images are not limited to each other. It is difficult to suppress the influence of thermal fluctuations in the lattice. That is, in the method of acquiring a single phase distribution image by synthesizing a plurality of phase distribution images captured by shortening the X-ray irradiation time, it is possible to shorten the individual imaging time of the phase distribution images. Therefore, it is possible to suppress the occurrence of artifacts due to the thermal fluctuation of the lattice in each phase distribution image. However, even at times other than the imaging of the plurality of phase distribution images, the thermal fluctuation of the lattice is constantly occurring. Therefore, there is a disadvantage that the phase value in the same pixel region between the phase distribution images changes due to the thermal fluctuation of the grid. Therefore, when one phase distribution image is generated based on a plurality of phase distribution images in which the phase value in the same pixel region between each phase distribution image is changed, in the generated phase distribution image, between each phase distribution image. There is a problem that an artifact is generated based on a change in the phase value in the pixel region of the above, and the image quality of the phase distribution image is deteriorated. In addition to the Talbot-Lago interferometer disclosed in International Publication No. 2014/030115, a device that generates a plurality of images from a phase distribution and synthesizes a plurality of images to generate one phase distribution image. There is a similar problem with.

The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to generate one phase distribution image based on a plurality of phase distribution images. In the phase distribution image, it is possible to suppress the occurrence of artifacts due to the change in the phase value in the pixel region between the phase distribution images, and it is possible to suppress the deterioration of the image quality of the generated phase distribution image. It is to provide an optical imaging apparatus and an image processing method which can be performed.

In order to achieve the above object, the optical imaging apparatus according to the first aspect of the present invention includes a light source that irradiates a subject with light, a detector that detects the light emitted from the light source, and a signal detected by the detector. The image processing unit includes an image processing unit that generates a phase distribution image based on the above, and the image processing unit is located between a plurality of images in a pixel region of a plurality of phase distribution images acquired based on images captured at different timings. It is configured to generate one phase distribution image based on a plurality of phase distribution images obtained by correcting the phase value of the pixel region based on the change of the phase value and correcting the phase value of the pixel region. ing.

In the optical imaging apparatus according to the first aspect of the present invention, as described above, a plurality of corrected phase values in the pixel region based on changes in the phase values between the plurality of images in the pixel region of the plurality of phase distribution images. It is provided with an image processing unit that generates one phase distribution image by the phase distribution image. As a result, even if the phase value changes between the pixel regions of each phase distribution image, it is possible to suppress the change in the phase value between the pixel regions of a plurality of phase distribution images by correcting the phase value. can. As a result, in the generated phase distribution image, it is possible to suppress the occurrence of artifacts due to the change in the phase value in the pixel region between the phase distribution images, and the image quality of the generated phase distribution image is improved. Deterioration can be suppressed.

In the optical imaging apparatus according to the first aspect, preferably, the image processing unit shifts the phase value between the images of each pixel of the plurality of phase distribution images by one cycle as the phase value correction processing of the pixel region. It is configured to perform an unwrapping process that corrects the phase value of the discontinuous wrapping region so that the change is continuous. With this configuration, the positions of the wrapping regions between the images can be aligned by unwrapping the phase values between the images of each pixel. Therefore, when one phase distribution image is generated based on a plurality of phase distribution images, the phase values in the vicinity of the wrapping region are smoothed by synthesizing the phase distribution images in which the positions of the wrapping regions are scattered. It is possible to prevent it from being stored. As a result, it is possible to suppress the occurrence of artifacts in the generated phase distribution image due to the smoothing of the phase value in the wrapping region.

In the optical imaging apparatus according to the first aspect, preferably, the image processing unit has a phase value between images of each pixel of a plurality of phase distribution images arranged in the order of imaging of the plurality of phase distribution images or in the order opposite to the imaging. It is configured to perform unwrapping processing based on the change in. Here, the thermal fluctuation of the lattice occurs in a specific direction with the passage of time. Therefore, with the above configuration, changes in the phase value between the images of each pixel can be acquired in chronological order. As a result, it is possible to acquire changes in the phase value over time, so it is necessary to accurately grasp the changes in the phase value due to the influence of the thermal fluctuation of the lattice that occurs in a specific direction with the passage of time in each image. Is possible, and accurate unwrapping processing can be performed.

In the configuration in which the image processing unit performs unwrapping processing as the correction processing of the phase value of the pixel region, preferably, the image processing unit is used for pixels in the vicinity of the boundary where the phase values are discontinuous in a plurality of phase distribution images. On the other hand, it is configured to perform unwrapping processing. With this configuration, it is possible to suppress the unwrapping process from performing the unwrapping process on the region of the pixels included in the plurality of phase distribution images that does not require the unwrapping process. As a result, it is possible to reduce the number of regions to be unwrapped, so that the load on the image processing unit can be reduced. The pixels in the vicinity of the boundary where the phase values are discontinuous include the pixels themselves at the positions of the boundaries where the phase values are discontinuous and the pixels adjacent to the positions of the boundaries where the phase values are discontinuous. ..

In the configuration in which the image processing unit performs unwrapping processing as the phase value correction processing of the pixel region, the light source is preferably configured to irradiate X-rays, and the detector is configured to detect X-rays. A plurality of grids, which are arranged between the light source and the detector and include a first grid in which X-rays are emitted from the light source and a second grid in which X-rays are emitted from the first grid. Further, the image processing unit acquires a plurality of phase distribution images and, based on the change in the phase value between the images of each pixel of the plurality of phase distribution images, the phase value between the images of the plurality of phase distribution images. It is configured to generate one phase distribution image by performing the unwrapping process of the above and integrating or averaging a plurality of phase distribution images subjected to the unwrapping process. With this configuration, by performing unwrapping processing on a plurality of phase distribution images in which the positions of the wrapping regions are scattered, it is possible to align the positions of the wrapping regions in each phase distribution image. When integrating or averaging the phase distribution images, it is possible to suppress the smoothing of the phase values between each pixel in the vicinity of the wrapping region of the plurality of phase distribution images. As a result, even in the phase distribution image, it is possible to suppress the occurrence of artifacts due to the change in the phase value in each pixel between the phase distribution images in the generated phase distribution image, and it is also generated. It is possible to suppress the deterioration of the image quality of the phase distribution image.

In this case, preferably, a grid moving mechanism for moving any of the plurality of grids is further provided, and the image processing unit is based on a plurality of phase distribution images captured while moving any of the plurality of grids. It is configured to generate a number of phase distribution images. With this configuration, even in the fringe scanning method in which imaging is performed while moving a plurality of grids, an artifact occurs in the generated phase distribution image due to the change in the phase value in each pixel between the phase distribution images. This can be suppressed, and the deterioration of the image quality of the generated phase distribution image can be suppressed.

In a configuration in which the image processing unit generates one phase distribution image by integrating or averaging a plurality of unwrapped phase distribution images, preferably, the plurality of grids include a light source and a first grid. It further contains a third grid arranged between. With this configuration, the coherence of X-rays emitted from the light source by the third lattice can be enhanced. As a result, it is possible to form a self-image of the first grid independently of the focal diameter of the light source, so that the degree of freedom in selecting the light source can be improved.

In a configuration in which the image processing unit generates one phase distribution image by integrating or averaging a plurality of unwrapped phase distribution images, preferably, the image processing units are imaged at different timings. It is configured to generate a plurality of phase distribution images by performing a Fourier transform process and an inverse Fourier transform process on the image. With this configuration, even in the Fourier transform method that generates a phase distribution image by Fourier transform processing and inverse Fourier transform processing, the phase value changes in each pixel between each phase distribution image in the generated phase distribution image. It is possible to suppress the occurrence of the resulting artifacts, and it is also possible to suppress the deterioration of the image quality of the generated phase distribution image.

The image processing method in the second aspect of the present invention includes a step of acquiring a plurality of phase distribution images acquired based on images captured at different timings, and a plurality of images in a pixel region of the plurality of phase distribution images. One phase distribution image is created based on a step of performing a process of correcting the phase value of the pixel region based on the change of the phase value between the two and a plurality of phase distribution images of which the phase value of the pixel region is corrected. Includes steps to generate.

As described above, the image processing method in the second aspect of the present invention performs processing for correcting the phase value of the pixel region based on the change in the phase value between the plurality of images in the pixel region of the plurality of phase distribution images. It includes a step and a step of generating one phase distribution image based on a plurality of phase distribution images in which the phase value of the pixel region is corrected. With this configuration, similar to the optical imaging device in the first aspect, when a single phase distribution image is generated based on a plurality of phase distribution images, each phase is generated in the generated phase distribution image. An image processing method capable of suppressing the occurrence of artifacts based on changes in the phase value in the pixel region between distributed images and suppressing deterioration of the image quality of the generated phase distributed images. Can be provided.

According to the present invention, as described above, when one phase distribution image is generated based on a plurality of phase distribution images, in the generated phase distribution image, the phase value in the pixel region between the phase distribution images. It is possible to provide an optical imaging device and an image processing method capable of suppressing the occurrence of artifacts based on the change in the image and suppressing the deterioration of the image quality of the generated phase distribution image. ..

It is a schematic diagram which showed the whole structure of the optical imaging apparatus by 1st Embodiment. It is a schematic diagram for demonstrating the structure of the grid position adjustment mechanism by 1st Embodiment. It is a schematic diagram for demonstrating the process which the image processing part by 1st Embodiment generates a phase contrast image including a phase distribution image. It is a schematic diagram for demonstrating the change of the position of the wrapping region in a plurality of phase distribution images. It is a schematic diagram of the graph before the unwrapping process and the schematic diagram of the graph after the unwrapping process. It is a flowchart for demonstrating the process which the optical imaging apparatus by 1st Embodiment integrates a phase distribution image. It is a schematic diagram for demonstrating the change of the position of the wrapping region of each phase distribution image by 1st comparative example, and the smoothing of a phase value by integrating a plurality of phase distribution images. It is a schematic diagram for demonstrating the change of the phase value in one phase distribution image and the change of the phase value in the integrated phase distribution image by 1st Embodiment and 1st comparative example. It is a schematic diagram of the phase distribution image by 1st comparative example. It is a schematic diagram of the phase distribution image by 1st Embodiment. It is a schematic diagram for demonstrating the unwrapping process by 2nd comparative example. It is a schematic diagram for demonstrating the process which the image processing part by 2nd Embodiment generates a phase contrast image including a phase distribution image. It is a flowchart for demonstrating the process which the optical imaging apparatus by 2nd Embodiment integrates a phase distribution image. It is a schematic diagram which showed the whole structure of the optical imaging apparatus by 3rd Embodiment. It is a schematic diagram which showed the whole structure of the optical imaging apparatus by the modification of 1st Embodiment.

Hereinafter, embodiments embodying the present invention will be described with reference to the drawings.

[First Embodiment]
With reference to FIGS. 1 to 5, the configuration of the optical imaging apparatus 100 according to the first embodiment of the present invention and the method by which the optical imaging apparatus 100 generates an integrated phase distribution image 14 (see FIG. 3) will be described.

(Configuration of optical imaging device)
First, with reference to FIG. 1, the configuration of the optical imaging apparatus 100 according to the first embodiment will be described.

As shown in FIG. 1, the optical imaging device 100 is a device that images the inside of the subject Q by utilizing the Talbot effect. The optical imaging device 100 can be used for imaging the inside of the subject Q, for example, in non-destructive inspection applications.

FIG. 1 is a view of the optical imaging device 100 as viewed from the X direction. As shown in FIG. 1, the optical imaging apparatus 100 includes an X-ray source 1, a first grid 2, a second grid 3, a detector 4, an image processing unit 5, a control unit 6, and a storage unit 7. And a grid moving mechanism 8. The X-ray source 1 is an example of a "light source" in the claims. Further, in the present specification, the direction from the X-ray source 1 toward the first grid 2 is the Z2 direction, and the direction opposite to the direction is the Z1 direction. Further, the vertical direction in the plane orthogonal to the Z direction is the Y direction, the upward direction is the Y1 direction, and the downward direction is the Y2 direction. Further, the left-right direction in the plane orthogonal to the Z direction is the X direction, the direction toward the back of the paper surface in FIG. 1 is the X2 direction, and the direction toward the front side of the paper surface in FIG. 1 is the X1 direction.

The X-ray source 1 generates X-rays by applying a high voltage. The X-ray source 1 is configured to irradiate the generated X-rays in the Z2 direction.

The first grid 2 has a plurality of slits 2a arranged in a fixed direction with a predetermined period (pitch) p1 and an X-ray phase changing portion 2b. Each of the slits 2a and the X-ray phase changing portion 2b is formed so as to extend linearly. Further, each of the slits 2a and the X-ray phase changing portion 2b is formed so as to extend in parallel. In the example shown in FIG. 1, each slit 2a and the X-ray phase changing portion 2b are arranged in the Y direction with a predetermined period (pitch) p1 and are formed so as to extend in the X direction. The first grid 2 is a so-called phase grid.

The first grid 2 is arranged between the X-ray source 1 and the second grid 3, and X-rays are emitted from the X-ray source 1. The first grid 2 is provided to form a self-image (not shown) of the first grid 2 by the Talbot effect. When X-rays having coherence pass through the lattice in which the slit is formed, an image of the lattice (self-image) is formed at a position separated from the lattice by a predetermined distance (Talbot distance). This is called the Talbot effect.

The second lattice 3 has a plurality of X-ray transmitting portions 3a and X-ray absorbing portions 3b arranged in a predetermined direction with a predetermined period (pitch) p2. Each of the X-ray transmitting portion 3a and the X-ray absorbing portion 3b is formed so as to extend linearly. Further, each X-ray transmitting portion 3a and X-ray absorbing portion 3b are formed so as to extend in parallel. In the example shown in FIG. 1, the X-ray transmitting portions 3a and the X-ray absorbing portions 3b are arranged in the Y direction with a predetermined period (pitch) p2, and are formed so as to extend in the X direction. The second grid 3 is a so-called absorption grid. The first lattice 2 has a function of changing the phase of X-rays depending on the difference in refractive index between the X-ray phase changing portion 2b and the slit 2a. The second grid 3 has a function of shielding a part of X-rays by the X-ray absorbing unit 3b.

The second grid 3 is arranged between the first grid 2 and the detector 4, and is irradiated with X-rays that have passed through the first grid 2. Further, the second grid 3 is arranged at a position separated from the first grid 2 by a Talbot distance. The second grid 3 interferes with the self-image of the first grid 2 to form a moire fringe mf (see FIG. 3) on the detection surface of the detector 4.

The detector 4 is configured to detect X-rays, convert the detected X-rays into an electric signal, and read the converted electric signal as an image signal. The detector 4 is, for example, an FPD (Flat Panel Detector). The detector 4 is composed of a plurality of conversion elements (not shown) and pixel electrodes (not shown) arranged on the plurality of conversion elements. The plurality of conversion elements and pixel electrodes are arranged in an array in the X direction and the Y direction at a predetermined period (pixel pitch). Further, the detector 4 is configured to output the acquired image signal to the image processing unit 5.

The image processing unit 5 is configured to generate an integrated phase distribution image 14 (see FIG. 11) based on the image signal output from the detector 4. The image processing unit 5 includes, for example, a processor such as a GPU (Graphics Processing Unit) or an FPGA (Field-Programmable Gate Array) configured for image processing. Further, the image processing unit 5 is configured to generate an average value image 11 (see FIG. 3) and a visibility image 15 (see FIG. 3) based on the image signal output from the detector 4.

The control unit 6 is configured to control the grid movement mechanism 8 to move the first grid 2. The control unit 6 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like.

The storage unit 7 is configured to store the X-ray image 10, the average value image 11, the integrated phase distribution image 14, the visibility image 15, and the like generated by the image processing unit 5. The storage unit 7 includes, for example, an HDD (Hard Disk Drive), a non-volatile memory, and the like.

The grid moving mechanism 8 is configured to be able to move the first grid 2 under the control of the control unit 6. Further, the grid moving mechanism 8 holds the first grid 2.

(Lattice movement mechanism)
As shown in FIG. 2, the grid moving mechanism 8 has a rotation direction Rz around the X-direction, Y-direction, Z-direction, and Z-direction axes, a rotation direction Rx around the X-direction axis, and around the Y-direction axis. The first lattice 2 is configured to be movable in the rotation direction Ry. Specifically, the grid moving mechanism 8 includes an X-direction linear motion mechanism 80, a Y-direction linear motion mechanism 81, a Z-direction linear motion mechanism 82, a linear motion mechanism connection unit 83, and a stage support unit drive unit 84. , A stage support unit 85, a stage drive unit 86, and a stage 87. The X-direction linear motion mechanism 80 is configured to be movable in the X-direction. The X-direction linear motion mechanism 80 includes, for example, a motor and the like. The Y-direction linear motion mechanism 81 is configured to be movable in the Y-direction. The Y-direction linear motion mechanism 81 includes, for example, a motor and the like. The Z-direction linear motion mechanism 82 is configured to be movable in the Z-direction. The Z-direction linear motion mechanism 82 includes, for example, a motor and the like.

The grid moving mechanism 8 is configured to move the first grid 2 in the X direction by the operation of the linear movement mechanism 80 in the X direction. Further, the grid moving mechanism 8 is configured to move the first grid 2 in the Y direction by the operation of the Y-direction linear motion mechanism 81. Further, the grid moving mechanism 8 is configured to move the first grid 2 in the Z direction by the operation of the Z-direction linear motion mechanism 82.

The stage support portion 85 supports the stage 87 from below (Y1 direction). The stage drive unit 86 is configured to reciprocate the stage 87 in the X direction. The bottom of the stage 87 is formed in a convex curved surface shape toward the stage support portion 85, and is configured to rotate around an axis in the Z direction (Rz direction) by being reciprocated in the X direction. There is. Further, the stage support unit drive unit 84 is configured to reciprocate the stage support unit 85 in the Z direction. Further, the bottom of the stage support portion 85 is formed in a convex curved surface shape toward the linear motion mechanism connecting portion 83, and by being reciprocated in the Z direction, the stage support portion 85 rotates around the axis in the X direction (Rx direction). It is configured as follows. Further, the linear motion mechanism connecting portion 83 is provided in the X-direction linear motion mechanism 80 so as to be rotatable around an axis in the Y direction (Ry direction). Therefore, the grid moving mechanism 8 can rotate the grid around the central axis in the Y direction.

Next, with reference to FIGS. 3 to 5, the optical imaging apparatus 100 according to the first embodiment performs an integrated average value image 12 (see FIG. 3), an integrated phase distribution image 14 (see FIG. 3), and an integrated visibility image 16. A configuration for generating (see FIG. 3) will be described.

(Acquisition of multiple phase distribution images)
First, with reference to FIG. 3, the image 10 acquired by the optical imaging apparatus 100 according to the first embodiment, the plurality of average value images 11, the phase distribution image 13, and the visibility image 15 to be generated will be described. The average value image 11, the phase distribution image 13, and the visibility image 15 are each for a change in the pixel value of each pixel in a plurality of images 10 acquired while translating the second grid 3 in the fringe scanning method. , It is an image obtained by mapping the average value of the function fitted by the sine function, the phase value, and the visibility value, respectively.

The example shown in FIG. 3 is based on four images 10 (an image set including an image 10a, an image 10b, an image 10c, and an image 10d) obtained by translating the second grid 3 four times by the grid moving mechanism 8. , An example of generating an average value image 11, a phase distribution image 13, and a visibility image 15. In the first embodiment, the image processing unit 5 has a plurality of average value images 11, a phase distribution image 13, and a visibility image 15 based on each set of images 10 (images 10a to 10d) captured at different timings. To get. Further, the image processing unit 5 generates an integrated phase distribution image 14 by integrating a plurality of phase distribution images 13. Further, the image processing unit 5 generates the integrated average value image 12 and the integrated visibility image 16 by integrating the plurality of average value images 11 and the visibility images 15, respectively. The phase distribution image 13 and the integrated phase distribution image 14 are images showing the distribution of the phase values of the moire fringes mf. The possible range of the phase values of the phase distribution image 13 and the integrated phase distribution image 14 is −π to π, and the phase value is a periodic value that repeats the range. Therefore, in the phase distribution image 13 (integrated phase distribution image 14), a wrapping region that becomes discontinuous is generated due to the phase value being deviated by one cycle. In the example shown in FIG. 3, since the range of the phase value is −π to π, the sign of the phase value is inverted in the wrapping region.

When the second lattice 3 undergoes thermal fluctuation, the position of the wrapping region in each phase distribution image 13 shifts. When a plurality of phase distribution images 13 in which the positions of the wrapping regions are displaced are integrated as they are, the phase values in the wrapping region are smoothed and an artifact is generated in the integrated phase distribution image 14. Therefore, in the first embodiment, the image processing unit 5 determines the phase value of the pixel region Ra based on the change in the phase value between the images of the pixel region Ra (see FIG. 4) of the acquired plurality of phase distribution images 13. Is corrected, and one integrated phase distribution image 14 is generated based on the plurality of phase distribution images 13 obtained by correcting the phase value of the pixel region Ra. Specifically, the image processing unit 5 acquires a plurality of phase distribution images 13, and based on the change in the phase value between the images of each pixel of the plurality of phase distribution images 13, the plurality of phase distribution images 13 of the plurality of phase distribution images 13. It is configured to generate one integrated phase distribution image 14 by performing unwrapping processing of phase values between images and integrating a plurality of phase distribution images 13 that have undergone unwrapping processing. The phase distribution image 13 and the integrated phase distribution image 14 are examples of the "phase distribution image" in the claims. Further, a detailed description of the phase value correction process and the unwrapping process between images will be described later.

Further, in the first embodiment, the image processing unit 5 is configured to generate one integrated phase distribution image 14 based on a plurality of phase distribution images 13 captured while moving the second grid 3. ing. That is, the image processing unit 5 generates a plurality of phase distribution images 13 by a so-called fringe scanning method.

Here, when the phase distribution image 13 is acquired by the fringe scanning method, when the thermal fluctuation of the lattice occurs due to heat generation from the X-ray source 1 or the like, between the images of the plurality of images 10 (images 10a to 10d), The phase of the moire fringe mf is out of phase. When the phase value of the moire fringe mf is deviated between the images of the plurality of images 10, an artifact occurs in the phase distribution image 13, and the image quality of the phase distribution image 13 deteriorates. When the image quality of the phase distribution image 13 deteriorates, the image quality of the integrated phase distribution image 14 also deteriorates. Since the thermal fluctuations of the grid accumulate over time, increasing the imaging time to obtain a high-contrast image increases the effect of artifacts caused by the thermal fluctuations. Therefore, in the first embodiment, in order to suppress the influence of heat fluctuation of the lattice due to heat generation from the X-ray source 1 as much as possible, the imaging time (X-ray exposure time) of each image 10 is shortened and imaged. There is. Since the imaging time of each image 10 is short, the contrast of each image 10 is lowered. Therefore, each phase distribution image 13 generated based on the image 10 is also an image having low contrast.

In the first embodiment, as shown in FIG. 3, by integrating a plurality of phase distribution images 13 having low contrast, one integrated phase distribution image 14 having high contrast is acquired. Since it is possible to suppress the deterioration of the image quality of each phase distribution image 13, it is possible to suppress the deterioration of the image quality of the integrated phase distribution image 14. However, when thermal fluctuation occurs in the grid, the distribution of the phase values between the images of each phase distribution image 13 changes.

FIG. 4 is a schematic diagram of a plurality of phase distribution images 13 and a schematic diagram of an image 17 (a part of the phase distribution image 13) in which the pixel region Ra of each phase distribution image 13 is enlarged. The example shown in FIG. 4 is an example in which the distribution of the phase values in each phase distribution image 13 changes due to the change in the phase of the moire fringes mf due to the thermal fluctuation of the second lattice 3. Further, the example shown in FIG. 4 is an example showing a change in the distribution of the phase value by focusing on the pixel G among the pixels included in the pixel region Ra of each phase distribution image 13. The example shown in FIG. 4 shows the difference in phase value depending on the presence or absence of hatching. That is, the region with hatching is a region having a lower phase value than the region without hatching. Further, the region without hatching is a region having a higher phase value than the region with hatching. Further, at the boundary pb between the region with hatching and the region without hatching, the sign of the phase value is inverted and becomes discontinuous. Such an area is called a wrapping area.

In the first phase distribution image 13a, the position of the wrapping region is on the left side of the position of the pixel G, and the pixel G is located in the region where the phase value is high (the region without hatching). In the second phase distribution image 13b, the position of the wrapping region and the position of the pixel G are substantially the same. Further, in the Nth phase distribution image 13c, the position of the wrapping region is on the right side of the position of the pixel G, and the pixel G is located in the region where the phase value is low. That is, in the example shown in FIG. 4, the phase of the moire fringe mf changes between the first X-ray image set and the NX-ray image set due to the thermal fluctuation of the second grid 3 with the passage of time. This is an example in which the wrapping region in the phase distribution image 13 gradually moves to the right side of the image.

When the plurality of phase distribution images 13 shown in FIG. 4 are integrated, the phase value in the pixel region Ra is smoothed, and the change in the phase value in the wrapping region becomes gentle. When the change in the phase value in the wrapping region becomes gentle, an artifact occurs in the integrated phase distribution image 14. Further, since the phase value also changes abruptly at the boundary portion between the subject Q and the background or the boundary portion of the internal structure of the subject Q, when the phase value between each image changes, the phase value changes at the boundary portion. Since the surface becomes gentle, the edge of the subject Q becomes unclear, which causes deterioration of the image quality of the integrated phase distribution image 14. Therefore, in the first embodiment, it is configured to correct the phase value of each pixel region Ra.

(Correction processing of phase distribution image)
In the first embodiment, the image processing unit 5 is configured to correct the phase value of the pixel in the pixel region Ra based on the change in the phase value of the pixel G of each phase distribution image 13. Specifically, the image processing unit 5 performs a wrapping region in which the phase value between the images of each pixel of the plurality of phase distribution images 13 is deviated by one cycle to correct the phase value of the pixel region Ra. It is configured to perform an unwrapping process that corrects the phase value of the image so that it changes continuously. In the example shown in FIG. 4, for convenience, a part of the wrapping region is shown as a pixel region Ra, but the pixel region Ra is a region in which the sign of the phase value is inverted, and exists at a plurality of locations in the phase distribution image 13. do. Further, the image processing unit 5 also performs phase value correction processing in a region other than the pixel region Ra. That is, the image processing unit 5 determines whether or not phase value wrapping occurs between the images in each pixel of the phase distribution image 13, and performs unwrapping processing on the pixels where the wrapping occurs between the images. ..

FIG. 5 is a schematic diagram of the graph 18 before the unwrapping process in the image processing unit 5 and the graph 20 after the unwrapping process. In the graph 18 and the graph 20, the horizontal axis is the image No. (N) and the vertical axis is the phase value (rad). The unit (N) of the pixel No. on the horizontal axis is the imaging order of the phase distribution image 13, and is an integer value including 0 (zero). In the present embodiment, the imaging order of the first captured image is set to 0th. Further, the plot pv shown in the graph 18 and the graph 20 shows the phase value of the pixel G of each phase distribution image 13.

As shown in the graph 18 of FIG. 5, the image processing unit 5 plots the phase values of the pixels G of the plurality of phase distribution images 13 in the order in which the phase distribution images 13 are captured. Since the phase of the moire fringe mf due to the thermal fluctuation is changed, the phase value of each pixel G shown in the graph 18 has a wrapping region in the portion surrounded by the ellipse Rb.

As shown in Graph 18, when each phase value is integrated in a state where a wrapping region is generated in the phase value of the pixel in the pixel region Ra of each phase distribution image 13, the phase value of each pixel region Ra is shown by the line segment 19. It becomes a phase value (an average value of the phase values of each pixel G), and the value of the phase value of each pixel region Ra fluctuates significantly. Such a large variation at the boundary pb of the phase value causes deterioration of the image quality of the integrated phase distribution image 14.

Therefore, in the first embodiment, as shown in the graph 20, the image processing unit 5 changes the phase value between the images of each pixel of the plurality of phase distribution images 13 arranged in the order of imaging of the plurality of phase distribution images 13. It is configured to perform unwrapping processing based on this. In the present embodiment, the unwrapping process is a process of correcting the phase value of each pixel G after the wrapping region so that the phase value of each pixel G becomes continuous before and after the wrapping region. In the graph 20 after the unwrapping process, the phase values of the pixels G of the phase distribution image 13 are continuous in the portion surrounded by the ellipse Rc, and the wrapping region is eliminated. When the phase distribution images 13 after correcting the phase values in this way are integrated, the phase value of each pixel region Ra becomes the phase value indicated by the line segment 21 (the average value of the phase values of each pixel G), and each of them becomes. The value of the phase value of the pixel region Ra does not fluctuate so much. Therefore, deterioration of the image quality of the integrated phase distribution image 14 can be suppressed.

Further, the image processing unit 5 is configured to perform unwrapping processing on pixels in the vicinity of the boundary pb whose phase values are discontinuous in the plurality of phase distribution images 13. Specifically, the image processing unit 5 refers to the pixels included in the range mr in the pixel region Ra from the first phase distribution image 13a to the Nth phase distribution image 13c in which the boundary pb of the phase value moves. It is configured to perform unwrapping processing. The example shown in FIG. 5 is an example in which the pixel G of each phase distribution image 13 is unwrapped as pixels in the vicinity of the boundary pb whose phase values are discontinuous. That is, the image processing unit 5 performs unwrapping processing on the same pixel G of each image from the first phase distribution image 13a to the Nth phase distribution image 13c.

Next, with reference to FIG. 6, the flow of the process of generating the integrated phase distribution image 14 by the optical imaging apparatus 100 according to the first embodiment will be described.

In step S1, the image processing unit 5 acquires a plurality of phase distribution images 13 based on the images 10 captured at different timings. In step S1, the image processing unit 5 acquires a plurality of phase distribution images 13 by the fringe scanning method. After that, the process proceeds to step S2.

In step S2, the image processing unit 5 performs a process of correcting the phase value of the pixel region Ra based on the change of the phase value between the images of the pixel region Ra of the plurality of phase distribution images 13. After that, the process proceeds to step S3.

In step S3, the image processing unit 5 generates one integrated phase distribution image 14 based on the plurality of phase distribution images 13 for which the phase value of the pixel region Ra has been corrected, and ends the processing.

(First comparative example)
Here, with reference to FIGS. 7 to 10, the optical imaging apparatus according to the first comparative example that generates one phase distribution image 13 by integrating a plurality of phase distribution images 13 as they are, and the light in the present embodiment. The imaging device 100 and the like will be described.

FIG. 7 is a schematic diagram of a plurality of phase distribution images 13, a schematic diagram of an integrated phase distribution image 22 in which a plurality of phase distribution images 13 are integrated, and a schematic diagram of an enlarged image 17 in which the pixel region Ra of each image is enlarged.

The integrated phase distribution image 22 is an image obtained by integrating a plurality of phase distribution images 13. Since the positions of the wrapping regions are slightly deviated in each phase distribution image 13, the change in the phase value in the wrapping region becomes gentle. Therefore, as shown in FIG. 7, in the wrapping region of the integrated phase distribution image 22, the phase value of the first phase distribution image 13 changes in a gradation pattern.

FIG. 8 is a schematic diagram of a graph 23 showing a change in the phase value of the wrapping region in the integrated phase distribution image 14, and a graph showing a change in the phase value in the region Rd of the pixel region Ra of the second phase distribution image 13b. It is a schematic diagram of the graph 25 which shows the change of the phase value in the region Re in the schematic diagram of 24 and the pixel region Ra of the integrated phase distribution image 22.

As shown in the graph 24, the phase value is inverted in the wrapping region of the second phase distribution image 13b. On the other hand, as shown in the graph 25, the phase value changes stepwise in the wrapping region of the integrated phase distribution image 22, and the change of the phase value is gentle as compared with the wrapping region of the graph 24. In such an integrated phase distribution image 22, as shown in FIG. 9, vertical stripe artifact 26 is generated at the position of the wrapping region.

In the present embodiment, since the phase value of each pixel region Ra is unwrapped and then each phase distribution image 13 is integrated, the phase value in the wrapping region of the integrated phase distribution image 14 after integration is shown in Graph 23. Invert as shown in. Therefore, as shown in FIG. 10, in the integrated phase distribution image 14, it is possible to suppress the occurrence of the artifact 26.

(Second comparative example)
Next, with reference to FIG. 11, a second comparative example of integration after performing unwrapping processing on each of the phase distribution images 13 will be described. In order to suppress the deterioration of the image quality of the integrated phase distribution image 14 due to the change in the position of the wrapping region caused by the phase shift of the moire fringe mf, as shown in FIG. 11, for each phase distribution image 13, each phase distribution image 13 is used. A method of acquiring a plurality of images 27 obtained by unwrapping the images and integrating the plurality of images 27 can be considered. However, for example, when the pixel of the detector 4 has a defect, noise due to the pixel defect occurs in the phase distribution image 13. When each phase distribution image 13 in which noise is generated is unwrapped, the noise caused by the loss of pixels in the same image affects other pixels in the unwrapped image 27, and is striped (streak-shaped). ), The artifact 28 is generated. When the images 27 in which these artifacts 28 are generated are integrated, the artifacts 28 of each image 27 are also integrated in the image 29 after the integration. If the artifact 28 is generated in the integrated image 29, it causes deterioration of the image quality of the integrated phase distribution image 14.

In the present embodiment, since the phase distribution image 13 after correcting the phase value of the pixel region Ra (unwrapping process) is integrated, the influence of pixel loss in each image occurs only in the same pixel, so that other It is possible to suppress the influence on the pixels. That is, since the influence of the missing pixel can be limited to only that pixel, it is possible to suppress the occurrence of the striped artifact 28 in the phase distribution image 13.

(Effect of the first embodiment)
In the first embodiment, the following effects can be obtained.

In the first embodiment, as described above, the optical imaging apparatus 100 includes an X-ray source 1 that irradiates the subject Q with light, a detector 4 that detects the light radiated from the X-ray source 1, and a detector 4. The image processing unit 5 includes an image processing unit 5 that generates a phase distribution image 13 based on the signal detected by the image processing unit 5, and the image processing unit 5 has a plurality of phase distribution images acquired based on the images 10 captured at different timings. Based on the change in the phase value between the images of the pixel region Ra of 13, the phase value of the pixel region Ra is corrected, and the phase value of the pixel region Ra is corrected. It is configured to generate an integrated phase distribution image 14. As a result, even if the phase value changes between the pixel regions Ra of each phase distribution image 13, the phase value changes by correcting the phase value so that the phase value changes between the pixel regions Ra of the plurality of phase distribution images 13. It can be suppressed. As a result, in the generated integrated phase distribution image 14, it is possible to suppress the occurrence of an artifact 26 based on the change in the phase value in the pixel region Ra between the respective phase distribution images 13, and it is possible to suppress the occurrence of the generated integrated phase. It is possible to suppress the deterioration of the image quality of the distributed image 14.

Further, in the first embodiment, as described above, the image processing unit 5 shifts the phase value between the images of each pixel of the plurality of phase distribution images 13 by one cycle as the phase value correction processing of the pixel region Ra. As a result, the unwrapping process is configured to correct the phase value of the wrapping region that becomes discontinuous so that the change is continuous. This makes it possible to align the positions of the wrapping regions between the images by unwrapping the phase values between the images of each pixel. Therefore, when one integrated phase distribution image 14 is generated based on the plurality of phase distribution images 13, the phase values in the vicinity of the wrapping region are smoothed by synthesizing each phase distribution image 13 in which the wrapping region is dispersed. It can be suppressed that it is done. As a result, it is possible to suppress the occurrence of artifacts in the generated integrated phase distribution image 14 due to the smoothing of the phase value in the wrapping region.

Further, in the first embodiment, as described above, the image processing unit 5 is based on the change in the phase value between the images of each pixel of the plurality of phase distribution images 13 arranged in the order of imaging of the plurality of phase distribution images 13. It is configured to perform unwrapping processing. Here, the thermal fluctuation of the second lattice 3 occurs in a specific direction with the passage of time. Therefore, by configuring as described above, it is possible to acquire the change in the phase value between the images of each pixel in time series. As a result, it becomes possible to acquire the change of the phase value in the time series, so that the change of the phase value due to the influence of the thermal fluctuation of the second lattice 3 that occurs in a specific direction with the passage of time in each image can be accurately obtained. It becomes possible to grasp and perform accurate unwrapping processing.

Further, in the first embodiment, as described above, the image processing unit 5 performs unwrapping processing on the pixels in the vicinity of the boundary pb where the phase values are discontinuous in the plurality of phase distribution images 13. It is configured in. As a result, it is possible to suppress the unwrapping process from performing the unwrapping process on the region of the pixels included in the plurality of phase distribution images 13 that does not require the unwrapping process. As a result, the number of regions to be unwrapped can be reduced, so that the load on the image processing unit 5 can be reduced.

Further, in the first embodiment, as described above, the X-ray source 1 is configured to irradiate X-rays, and the detector 4 is configured to detect X-rays. A plurality of cells arranged between the source 1 and the detector 4, including a first lattice 2 to be irradiated with X-rays from the X-ray source 1 and a second lattice 3 to be irradiated with X-rays from the first lattice 2. Further, the image processing unit 5 acquires a plurality of phase distribution images 13 and, based on the change in the phase value between the images of each pixel of the plurality of phase distribution images 13, the plurality of phase distribution images 13 It is configured to generate one integrated phase distribution image 14 by performing unwrapping processing of phase values between images and integrating a plurality of phase distribution images 13 that have undergone unwrapping processing. As a result, by performing unwrapping processing on a plurality of phase distribution images 13 in which the positions of the wrapping regions are scattered, it is possible to align the positions of the wrapping regions in each phase distribution image 13, and thus a plurality of phase distributions. When integrating the images 13, it is possible to prevent the phase values from being smoothed between the pixels in the vicinity of the wrapping region of the plurality of phase distribution images 13. As a result, in the integrated phase distribution image 14, it is possible to suppress the occurrence of artifacts due to the change in the phase value in each pixel between the phase distribution images 13 in the generated integrated phase distribution image 14. At the same time, it is possible to suppress deterioration of the image quality of the generated integrated phase distribution image 14.

Further, in the first embodiment, as described above, the grid moving mechanism 8 for moving the second grid 3 is further provided, and the image processing unit 5 has a plurality of phase distribution images imaged while moving the second grid 3. It is configured to generate one integrated phase distribution image 14 based on 13. As a result, even in the fringe scanning method in which imaging is performed while moving the second grid 3, an artifact is generated in the generated integrated phase distribution image 14 due to the change in the phase value in each pixel between the phase distribution images 13. This can be suppressed, and the deterioration of the image quality of the generated integrated phase distribution image 14 can be suppressed.

Further, in the first embodiment, as described above, step S1 for acquiring a plurality of phase distribution images 13 acquired based on the images 10 captured at different timings, and a pixel region of the plurality of phase distribution images 13 Based on the step S2 in which the phase value of the pixel region Ra is corrected based on the change in the phase value between the images of Ra, and the plurality of phase distribution images 13 in which the phase value of the pixel region Ra is corrected. A step S3 for generating one integrated phase distribution image 14 is included. As a result, in the generated integrated phase distribution image 14, it is possible to suppress the occurrence of artifacts due to changes in the phase value in the pixel region Ra between the respective phase distribution images 13, and it is possible to suppress the occurrence of artifacts and the generated integrated phase. It is possible to provide an image processing method capable of suppressing deterioration of the image quality of the distributed image 14.

[Second Embodiment]
Next, the optical imaging apparatus 200 (see FIG. 1) according to the second embodiment will be described with reference to FIGS. 1 and 12. Unlike the first embodiment in which a plurality of phase distribution images 13 are acquired based on a plurality of images 10 captured while moving the second grid 3, in the second embodiment, the image processing unit 5 generates moire fringes mf. It is configured to generate a plurality of phase distribution images 13 based on the image 30 in which the subject Q is captured in the generated state. The same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

(Configuration of optical imaging device)
First, the configuration of the optical imaging apparatus 200 according to the second embodiment will be described with reference to FIG. 1.

In the second embodiment, the image processing unit 5 slightly shifts the position of the second grid 3 by the grid moving mechanism 8 and has a plurality of phase distributions based on the image 30 taken in a state where moire fringes mf are generated in advance. Acquire the image 13. Specifically, the image processing unit 5 is configured to generate a plurality of phase distribution images 13 by performing a Fourier transform process and an inverse Fourier transform process on the images 30 captured at different timings.

Next, with reference to FIG. 13, the flow of the process of generating the integrated phase distribution image 14 by the optical imaging apparatus 200 according to the second embodiment will be described. The description of the same steps as in the first embodiment will be omitted.

In step S4, the image processing unit 5 acquires a plurality of phase distribution images 13 based on the images 10 captured at different timings. In step S4, the image processing unit 5 performs a Fourier transform process on the image 30 imaged in a state where moire fringes mf are generated in advance, instead of the fringe scanning method in which the second grid 3 is imaged while being translated. A plurality of phase distribution images 13 are acquired by a Fourier transform method that performs an inverse Fourier transform process. After that, the process proceeds to steps S2 and S3, generates one integrated phase distribution image 14 based on the plurality of phase distribution images 13 in which the phase value of the pixel region Ra is corrected, and ends the process.

The other configurations of the second embodiment are the same as those of the first embodiment.

(Effect of the second embodiment)
In the second embodiment, the following effects can be obtained.

In the second embodiment, as described above, the image processing unit 5 generates a plurality of phase distribution images 13 by performing a Fourier transform process and an inverse Fourier transform process on the images 30 captured at different timings. It is configured in. As a result, even in the Fourier transform method in which the phase distribution image 13 is generated by the Fourier transform process and the inverse Fourier transform process, the phase value changes in each pixel between the phase distribution images 13 in the generated integrated phase distribution image 14. It is possible to suppress the occurrence of the resulting artifacts, and it is also possible to suppress the deterioration of the image quality of the generated integrated phase distribution image 14.

The other effects of the second embodiment are the same as those of the first embodiment.

[Third Embodiment]
Next, with reference to FIG. 14, the optical imaging apparatus 300 according to the third embodiment will be described. Unlike the first and second embodiments in which the subject Q is irradiated with X-rays to acquire the phase distribution image 13, in the third embodiment, the optical imaging apparatus 300 is the light reflected by the reference surface 37 and the subject Q. It is configured to generate a phase distribution image based on the phase difference of. The same configurations as those of the first and second embodiments are designated by the same reference numerals, and the description thereof will be omitted.

(Configuration of optical imaging device)
As shown in FIG. 14, the optical imaging device 300 includes a light source 31, a filter 32, a first beam splitter 33, an objective lens 34, a second beam splitter 35, a subject mounting table 36, and a reference surface 37. , A detector 38, and an image processing unit 39.

The light source 31 is configured to irradiate white light toward the first beam splitter 33. The light source 31 includes, for example, a white laser or a white LED. The filter 32 is provided between the light source 31 and the first beam splitter 33. The filter 32 is configured to transmit light having a predetermined wavelength among the light emitted from the light source 31. The filter 32 includes, for example, a bandpass filter.

The first beam splitter 33 is configured to reflect the white light emitted from the light source 31 that has passed through the filter 32 toward the objective lens 34. Further, the first beam splitter 33 is configured to transmit the light reflected by the subject Q and the reference surface 37.

The objective lens 34 is provided between the first beam splitter 33 and the second beam splitter 35.

The second beam splitter 35 transmits the light transmitted through the objective lens 34 toward the subject mounting table 36. Further, the second beam splitter 35 reflects the light transmitted through the objective lens 34 toward the reference surface 37.

The subject mounting table 36 mounts the subject Q. The reference surface 37 is configured to reflect the irradiated light. The reference surface 37 includes, for example, a reflection mirror.

The detector 38 is configured to detect the light reflected by the subject Q placed on the subject mounting table 36 and the light reflected by the reference surface 37. Further, the detector 38 is configured to convert the detected light into an electric signal and read the converted electric signal as an image signal. The detector 38 includes, for example, an image sensor such as a CCD (Charged Coupled Devices) or a CMOS (Complementary Metal Oxide Sensor).

The image processing unit 39 is configured to generate a phase distribution image based on the signal detected by the detector 38. The image processing unit 39 includes, for example, a processor such as a GPU or an FPGA configured for image processing.

The optical imaging device 300 in the third embodiment is a so-called scanning white interferometer.

(Generation of phase distribution image)
In the third embodiment, the image processing unit 39 is configured to generate a phase distribution image based on the phase difference between the light reflected by the subject Q and the light reflected by the reference surface 37. The pixel value of the phase distribution image is a phase value based on the phase difference between the light reflected by the subject Q and the light reflected by the reference surface 37. Further, the image processing unit 39 is configured to generate one phase distribution image by synthesizing a plurality of phase distribution images captured at different imaging times.

Here, when the optical systems such as the first beam splitter 33, the objective lens 34, and the second beam splitter 35 thermally fluctuate due to the heat of the light source 31 and the like, the phase value of each phase distribution image changes. Therefore, also in the third embodiment, as in the first and second embodiments, the image processing unit 39 integrates the phase values of the wrapping region in the pixel region Ra of the plurality of phase distribution images after unwrapping processing. By doing so, it is configured to generate one phase distribution image.

The other configurations of the third embodiment are the same as those of the first and second embodiments.

(Effect of the third embodiment)
In the third embodiment, the following effects can be obtained.

In the third embodiment, as described above, the image processing unit 39 that generates a phase distribution image based on the phase difference between the light reflected by the subject Q and the light reflected by the reference surface 37 is included. As a result, as in the first and second embodiments, the optical systems such as the first beam splitter 33, the objective lens 34, and the second beam splitter 35 thermally fluctuate even when a plurality of phase distribution images are integrated. Therefore, in the generated phase distribution image, it is possible to suppress the occurrence of an artifact based on the change in the phase value in the pixel region between the phase distribution images, and the image quality of the generated phase distribution image is deteriorated. It can be suppressed.

The other effects of the third embodiment are the same as those of the first and second embodiments.

(Modification example)
It should be noted that the embodiments disclosed this time are exemplary in all respects and are not considered to be restrictive. The scope of the present invention is shown by the scope of claims, not the description of the above-described embodiment, and further includes all modifications (modifications) within the meaning and scope equivalent to the scope of claims.

For example, in the first and second embodiments, the grid moving mechanism 8 moves the second grid 3, but the present invention is not limited to this. The grid moved by the grid moving mechanism 8 may be any grid.

Further, in the first and second embodiments, the first grid 2 and the second grid 3 are provided as a plurality of grids, but the present invention is not limited to this. For example, as in the optical imaging apparatus 400 shown in FIG. 15, a third grid 40 may be provided between the X-ray source 1 and the first grid 2. The third grid 40 has a plurality of slits 40a and an X-ray absorption unit 40b arranged in the Y direction with a predetermined period (pitch) p3. Each of the slits 40a and the X-ray absorbing portion 40b is formed so as to extend linearly. Further, each of the slits 40a and the X-ray absorbing portion 40b is formed so as to extend in parallel. Further, the third grid 40 is arranged between the X-ray source 1 and the first grid 2, and X-rays are emitted from the X-ray source 1. The third grid 40 is configured to use X-rays that have passed through each slit 40a as a line light source corresponding to the position of each slit 40a. This makes it possible to increase the coherence of X-rays emitted from the X-ray source 1 by the third grid 40. As a result, the self-image of the first lattice 2 can be formed independently of the focal diameter of the X-ray source 1, so that the degree of freedom in selecting the X-ray source 1 can be improved.

Further, in the first and second embodiments, an example of a configuration in which the image processing unit 5 generates an integrated phase distribution image 14 by integrating a plurality of phase distribution images 13 is shown, but the present invention is limited to this. I can't. For example, the image processing unit 5 may be configured to generate an integrated phase distribution image 14 by averaging a plurality of phase distribution images 13.

Further, in the first embodiment, an example of the configuration in which the image processing unit 5 performs unwrapping processing based on the change in the phase value between the images of each pixel of the plurality of phase distribution images 13 arranged in the order of imaging is shown. However, the present invention is not limited to this. For example, the image processing unit 5 may be configured to perform unwrapping processing based on the change in the phase value between the images of each pixel of the plurality of phase distribution images 13 arranged in the order opposite to the imaging.

Further, in the first and second embodiments, the image processing unit 5 has shown an example of a configuration in which the phase value of the pixel G included in the pixel region Ra of each phase distribution image 13 is corrected. Not limited to. For example, the image processing unit 5 determines the phase value of the pixel G included in the pixel region Ra of each phase distribution image 13 and the phase value of the pixels other than the pixel G among the pixels included in the range mr of the pixel region Ra. It may be configured to perform the unwrapping process based on the change of.

Further, in the first and second embodiments, the image processing unit 5 has shown an example of a configuration in which a process of increasing the phase value of a pixel having a low phase value is performed as an unwrapping process. Not limited. For example, the image processing unit 5 may be configured to perform unwrapping processing by lowering the phase value of a pixel having a high phase value.

Further, in the first to third embodiments, the X-ray source 1 (light source 31) irradiates X-rays (white light), and the image processing unit 5 (image processing unit 39) has the phase of X-rays (white light). An example of a configuration for generating a phase distribution image 13 (phase distribution image) based on a distribution has been shown, but the present invention is not limited to this. For example, the optical imaging device 100 (200, 300, 400) is configured to irradiate the subject Q with light other than the visible region such as infrared rays or ultraviolet rays in addition to X-rays and white light (visible light). You may. If the image processing unit 5 (image processing unit 39) can image using the phase distribution, what kind of light is emitted by the optical imaging device 100 (200, 300, 400) to the subject Q? It may be light.

1 X-ray source (light source)
2 1st grid 3 2nd grid 4, 38 Detector 5, 39 Image processing unit 6 Control unit 8 Grid movement mechanism 13 Phase distribution image (phase distribution image)
14 Integrated phase distribution image (phase distribution image)
31 Light source 40 Third grid 100, 200, 300, 400 Optical imaging device Ra Pixel area Q Subject

Claims (9)

A light source that illuminates the subject and
A detector that detects the light emitted from the light source, and
An image processing unit that generates a phase distribution image based on the signal detected by the detector is provided.
The image processing unit determines the phase value of the pixel region based on the change in the phase value between the plurality of images of the pixel region of the plurality of phase distribution images acquired based on the images captured at different timings. An optical imaging device configured to generate one phase distribution image based on a plurality of phase distribution images corrected and corrected for the phase value of the pixel region. As a process for correcting the phase value of the pixel region, the image processing unit obtains the phase value of the wrapping region which becomes discontinuous due to the phase value of each pixel of the plurality of phase distribution images being deviated by one cycle. The optical imaging apparatus according to claim 1, which is configured to perform an unwrapping process for compensating for continuous changes. The image processing unit performs unwrapping processing based on the change in the phase value between the images of each pixel of the plurality of the phase distribution images arranged in the imaging order of the plurality of phase distribution images or in the order opposite to the imaging. The optical imaging apparatus according to claim 1, which is configured in the above. The optical imaging according to claim 2, wherein the image processing unit performs unwrapping processing on pixels in the vicinity of a boundary where the phase values are discontinuous in the plurality of phase distribution images. Device. The light source is configured to irradiate X-rays.
The detector is configured to detect X-rays.
A plurality of grids arranged between the light source and the detector and including a first grid to be irradiated with X-rays from the light source and a second grid to be irradiated with X-rays from the first grid are further added. Prepare,
The image processing unit acquires a plurality of the phase distribution images, and based on the change in the phase value between the images of each pixel of the plurality of phase distribution images, the phase value between the images of the plurality of phase distribution images. 2. The second aspect of the present invention is configured to generate one phase distribution image by performing the unwrapping process of the above and integrating or averaging the plurality of the phase distribution images subjected to the unwrapping process. Optical imaging device. Further equipped with a grid moving mechanism for moving any of the plurality of grids,
5. The image processing unit is configured to generate one phase distribution image based on a plurality of phase distribution images captured while moving any of the plurality of lattices. The optical imaging apparatus according to. The optical imaging apparatus according to claim 5, wherein the plurality of grids further include a third grid arranged between the light source and the first grid. The fifth aspect of claim 5, wherein the image processing unit is configured to generate a plurality of the phase distribution images by performing a Fourier transform process and an inverse Fourier transform process on images captured at different timings. Optical imaging device. The step of acquiring a plurality of phase distribution images acquired based on the images captured at different timings, and
A step of performing a process of correcting the phase value of the pixel region based on a change in the phase value between a plurality of images of the pixel region of the plurality of phase distribution images, and a step of performing the process.
An image processing method comprising a step of generating one phase distribution image based on a plurality of phase distribution images for which the phase value of the pixel region has been corrected.

Images