Two-dimensional-image acquisition device and two-dimensional-image acquisition method

Abstract

A two-dimensional-image acquisition device 1 comprises a stage 12, an optical system 13, and an image reconstruction unit 14, in addition to comprising a two-dimensional-projection-data acquisition sensor 11. The two-dimensional-projection-data acquisition sensor 11 outputs a one-dimensional light intensity profile (X-direction projection data) x1-xN obtained by integrating a two-dimensional light intensity profile for a light-receiving unit in an X direction, and outputs a one-dimensional light intensity profile (Y-direction projection data) y1-yM obtained by integrating a two-dimensional light intensity profile for the light-receiving unit in a Y direction. The image reconstruction unit 14 performs image reconstruction on the basis of the X-direction projection data x1-xN and the Y-direction projection data y1-yM acquired for each of a plurality of directions to obtain a two-dimensional light intensity profile for the light-receiving unit of the two-dimensional-projection-data acquisition sensor 11. Thus, there are realized a two-dimensional-image acquisition device and a two-dimensional-image acquisition method with which it is possible to acquire a two-dimensional image using a two-dimensional-projection-data acquisition sensor.

Description

Two-dimensional image acquisition device and two-dimensional image acquisition method

[0001] The present disclosure relates to an apparatus and method for acquiring two-dimensional images.

[0002] The two-dimensional projection data acquisition sensors described in Non-Patent Documents 1 and 2 are area sensors specialized for acquiring projection data, and are also called profile sensors. The two-dimensional projection data acquisition sensor can acquire a one-dimensional light intensity profile by integrating the two-dimensional light intensity profile at the light receiving unit in each of the X and Y directions.

[0003] 1 is a diagram showing the configuration of a light receiving section of a sensor for acquiring two-dimensional projection data. In the light receiving section of the sensor for acquiring two-dimensional projection data, a plurality of pixels, each including two photodiodes, are two-dimensionally arranged in M ​​rows and N columns. The two photodiodes included in the pixel in the mth row and nth column are referred to as PD1. ｍ,ｎ , PD2 ｍ,ｎ Here, M and N are integers of 2 or more, m is an arbitrary integer of 1 or more and M or less, and n is an arbitrary integer of 1 or more and N or less.

[0004] M photodiodes PD1 in the nth column １,ｎ ~PD1 Ｍ,ｎ The output terminals of the M photodiodes are connected by a common wiring, and the entirety of these M photodiodes is essentially one pixel (H), and a signal value x corresponding to the total amount of light received by these photodiodes is output. ｎ are output through a common wiring. As a result, the two-dimensional projection data acquisition sensor outputs a one-dimensional light intensity profile (X-direction projection data) x obtained by integrating the two-dimensional light intensity profile in the light receiving section in the X direction. １ ~x Ｎ can be output.

[0005] N photodiodes PD2 in the m-th row ｍ,１ ~PD2 ｍ,Ｎ The output terminals of the N photodiodes are connected by a common wiring, and the entirety of these N photodiodes is essentially one pixel (V), and a signal value y corresponding to the total amount of light received by these photodiodes is output. ｍare output through a common wiring. As a result, the two-dimensional projection data acquisition sensor outputs a one-dimensional light intensity profile (Y-direction projection data) y １ ~y Ｍ can be output.

[0006] X-direction projection data x output from the two-dimensional projection data acquisition sensor １ ~x Ｎ and Y-direction projection data y １ ~y Ｍ The amount of data (N+M) is smaller than the amount of data (MN) output from a normal area sensor that acquires a two-dimensional light intensity profile (two-dimensional image) at the light receiving section. Therefore, the sensor for acquiring two-dimensional projection data can detect the position of a spot light incident on the light receiving section and a moving object at high speed compared to a normal area sensor.

[0007] Hamamatsu Photonics K.K., Profile Sensor S9132, Datasheet, December 2022; Hamamatsu Photonics K.K., Profile Sensor S15366 Series, Datasheet, April 2023; Hiroyuki Kudo, "New Method of Computer Tomography and Compressed Sensing," Journal of the Japan Society for Precision Engineering, Vol. 82, No. 6, pp. 506-512 (2016)

[0008] Although a sensor for acquiring two-dimensional projection data can quickly detect the position of a spot light or a moving object at the light receiving unit, it cannot acquire a two-dimensional light intensity profile (two-dimensional image) at the light receiving unit.

[0009] For example, a sensor for acquiring two-dimensional projection data is used to monitor some phenomenon or situation based on the detection results of the spot light position or moving object at the light receiving unit. When an abnormality is detected during this monitoring, it may be necessary to measure the two-dimensional light intensity profile at the light receiving unit in order to investigate the abnormal condition in detail.

[0010] In such a case, it is conceivable to use a normal area sensor instead of the two-dimensional projection data acquisition sensor, to switch the direction of light using a movable mirror so that the light is selectively incident on either the two-dimensional projection data acquisition sensor or the normal area sensor, or to split the light into two using a beam splitter so that the light is incident on both the two-dimensional projection data acquisition sensor and the normal area sensor simultaneously. However, with any of these methods, it is not easy to adjust the optical system.

[0011] An object of the present invention is to provide an apparatus and method capable of acquiring a two-dimensional image using a sensor for acquiring two-dimensional projection data.

[0012] An embodiment of the present invention is a two-dimensional image acquisition device that includes: (1) a two-dimensional projection data acquisition sensor that acquires a one-dimensional light intensity profile by integrating a two-dimensional light intensity profile at a light receiving unit in each of an x ​​direction and a y direction, (2) an orientation change unit that changes the relative orientation of the two-dimensional light intensity profile at the light receiving unit, and (3) an image reconstruction unit that performs image reconstruction based on data of the one-dimensional light intensity profile acquired by the two-dimensional projection data acquisition sensor when the two-dimensional light intensity profile at the light receiving unit is set in each of a plurality of orientations by the orientation change unit, to obtain the two-dimensional light intensity profile at the light receiving unit.

[0013] An embodiment of the present invention is a two-dimensional image acquisition method, which includes: (1) a two-dimensional projection data acquisition step of acquiring a one-dimensional light intensity profile by integrating a two-dimensional light intensity profile at a light receiving unit in each of an x ​​direction and a y direction using a two-dimensional projection data acquisition sensor, (2) an orientation change step of changing a relative orientation of the two-dimensional light intensity profile at the light receiving unit, and (3) an image reconstruction step of performing image reconstruction based on data of the one-dimensional light intensity profile acquired by the two-dimensional projection data acquisition sensor when the two-dimensional light intensity profile at the light receiving unit is set in each of a plurality of orientations by the orientation change step, thereby obtaining the two-dimensional light intensity profile at the light receiving unit.

[0014] According to an embodiment of the present invention, a two-dimensional image can be acquired using a sensor for acquiring two-dimensional projection data.

[0015] FIG. 1 is a diagram showing the configuration of a light receiving unit of a sensor for acquiring two-dimensional projection data. FIG. 2 is a diagram showing the configuration of a two-dimensional image acquisition device 1 equipped with a sensor 11 for acquiring two-dimensional projection data. FIGS. 3(a) and 3(b) are diagrams showing an example configuration of an optical system 13. FIG. 4 is a flowchart of a two-dimensional image acquisition method. FIG. 5 is a diagram showing a two-dimensional light intensity profile obtained by image reconstruction processing in an embodiment. FIG. 6 is a diagram showing a two-dimensional light intensity profile obtained by image reconstruction processing in an embodiment.

[0016] Hereinafter, embodiments of a two-dimensional image acquisition device and a two-dimensional image acquisition method will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate explanations will be omitted. The present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0017] 2 is a diagram showing the configuration of a two-dimensional image acquisition device 1 equipped with a two-dimensional projection data acquisition sensor 11. In addition to the two-dimensional projection data acquisition sensor 11, the two-dimensional image acquisition device 1 also includes a stage 12, an optical system 13, and an image reconstruction unit 14. For ease of explanation, an x-y-z Cartesian coordinate system is shown in this diagram. The x-axis and y-axis are parallel to the light receiving unit of the two-dimensional projection data acquisition sensor 11.

[0018] As described with reference to FIG. 1, the two-dimensional projection data acquisition sensor 11 acquires a one-dimensional light intensity profile by integrating the two-dimensional light intensity profile at the light receiving unit in the X direction and the Y direction. The two-dimensional projection data acquisition sensor 11 acquires a one-dimensional light intensity profile (X-direction projection data) x １ ~x Ｎ In addition, a one-dimensional light intensity profile (Y-direction projection data) y １ ~y Ｍcan be output.

[0019] The stage 12 supports the two-dimensional projection data acquisition sensor 11. The stage 12 may be capable of rotating the two-dimensional projection data acquisition sensor 11 around a line perpendicular to the light receiving portion of the two-dimensional projection data acquisition sensor 11 (a line parallel to the z-axis).

[0020] The optical system 13 is an optical system through which light passes before it is incident on the light receiving section of the two-dimensional projection data acquisition sensor 11. The optical system 13 may be any optical system, but may be capable of rotating the orientation of the two-dimensional light intensity profile at the light receiving section of the two-dimensional projection data acquisition sensor 11.

[0021] Either or both of the stage 12 and the optical system 13 are used as an orientation changer that changes the relative orientation of the two-dimensional light intensity profile at the light receiving portion of the two-dimensional projection data acquisition sensor 11 .

[0022] When the two-dimensional light intensity profile is set in each of a plurality of orientations in the light receiving section of the two-dimensional projection data acquisition sensor 11 by the stage 12 or the optical system 13, which is an orientation changing section, the image reconstruction section 14 converts the data of the one-dimensional light intensity profile (X-direction projection data x １ ~x Ｎ , Y-direction projection data y １ ~y Ｍ )

[0023] The image reconstruction unit 14 calculates the X-direction projection data x acquired for each of the multiple directions. １ ~x Ｎ and Y-direction projection data y １ ~y Ｍ Image reconstruction is performed based on the above, and a two-dimensional light intensity profile at the light receiving portion of the two-dimensional projection data acquisition sensor 11 is obtained.

[0024] The image reconstruction unit 14 may be a computer equipped with a processing unit (e.g., a CPU, etc.) that performs calculation processing, a memory unit (e.g., a hard disk drive, ROM, RAM, etc.) that stores programs and various data required for calculation processing, a display unit (e.g., an LCD display, etc.) that displays calculation conditions and calculation results, and an input unit (e.g., a keyboard, mouse, etc.) that accepts various inputs.

[0025] X-direction projection data x acquired for each of a plurality of directions １ ~x Ｎ and Y-direction projection data y １ ~y Ｍ is equivalent to a sinogram formed from data acquired by a radiation detector in an X-ray CT (Computed Tomography) device or a PET (Positron Emission Tomography) device.

[0026] Therefore, the image reconstruction unit 14 uses an algorithm for performing image reconstruction based on a sinogram in an X-ray CT device or a PET device to reconstruct the X-direction projection data x acquired for each of the multiple directions. １ ~x Ｎ and Y-direction projection data y １ ~y Ｍ By performing image reconstruction based on the above, a two-dimensional light intensity profile at the light receiving portion of the two-dimensional projection data acquisition sensor 11 can be obtained.

[0027] As the image reconstruction algorithm, for example, Filtered Back Projection (FBP), Maximum Likelihood Expectation Maximization (MLEM), Ordered Subset Expectation Maximization (OSEM), and Dynamic Row Action Maximum Likelihood Algorithm (DRAMA) can be used.

[0028] The image reconstruction algorithm may also be combined with compressed sensing (Non-Patent Document 3). When light is incident on a partial area of ​​the light receiving section of the two-dimensional projection data acquisition sensor 11, it is effective to use an image reconstruction algorithm combined with compressed sensing. This reduces the number of measurements and enables faster image reconstruction processing.

[0029] 3A and 3B are diagrams showing an example of the configuration of the optical system 13. The optical system 13 shown in these figures includes a Dove prism 13a as an orientation changer. By rotating the Dove prism 13a around its major axis, the light pattern after passing through the Dove prism 13a can be rotated. The rotation angle of the light pattern after passing through the Dove prism 13a is twice the rotation angle of the Dove prism 13a. Note that multiple Dove prisms may be arranged in series.

[0030] 4 is a flowchart of the two-dimensional image acquisition method. The two-dimensional image acquisition method includes an initialization step S1, a two-dimensional projection data acquisition step S2, a determination step S3, an orientation change step S4, and an image reconstruction step S5. Here, a rotatable stage 12 is used as an orientation change unit that changes the orientation θ of the two-dimensional light intensity profile in the light receiving unit of the two-dimensional projection data acquisition sensor 11, and the orientation θ is set to an initial value θ ０ to the end value θ １ The value is sequentially increased by a constant update amount Δθ up to

[0031] In the initialization step S1, the stage 12 sets the direction θ to the initial value θ ０ In the two-dimensional projection data acquisition step S2, the two-dimensional projection data acquisition sensor 11 acquires X-direction projection data x １ ~x Ｎ and Y-direction projection data y １ ~y Ｍ Get.

[0032] In the determination step S3, the azimuth θ is equal to the end value θ １ In the determination step S3, it is determined whether the azimuth θ reaches the final value θ １If it is determined that the final value θ has not been reached, Δθ is added to θ in the direction change step S4 to obtain a new θ, and the direction θ is changed to the new direction θ by the stage 12, and then the process returns to the two-dimensional projection data acquisition step S2. １ Steps S2 to S4 are repeated until the azimuth θ reaches the final value θ １ If it is determined that the value of the image reconstruction step S5 has been reached, the process proceeds to the image reconstruction step S5.

[0033] In the image reconstruction step S5, the image reconstruction unit 14 performs image reconstruction in a plurality of directions (initial value θ ０ to the end value θ １ The X-direction projection data x obtained for each direction θ with an update amount Δθ up to １ ~x Ｎ and Y-direction projection data y １ ~y Ｍ Image reconstruction is performed based on the above, and a two-dimensional light intensity profile at the light receiving portion of the two-dimensional projection data acquisition sensor 11 is obtained.

[0034] Since projection data in two directions is acquired, θ １ +Δθ-θ ０ For example, the initial value θ ０ is 0° and the update amount Δθ is 10°, the end value θ １ It is sufficient if the angle is 80°.

[0035] 2 includes an aperture and a lens, and the aperture, the lens, and the two-dimensional projection data acquisition sensor 11 are arranged so that the light receiving portion of the two-dimensional projection data acquisition sensor 11 and the aperture are in an optically conjugate positional relationship with each other.

[0036] Laser light output from the laser light source was made incident through an aperture and a lens onto the light receiving section of the two-dimensional projection data acquisition sensor 11. A rotatable stage 12 was used as an orientation change section that changes the orientation θ of the two-dimensional light intensity profile in the light receiving section of the two-dimensional projection data acquisition sensor 11, and the orientation θ was sequentially increased by a fixed update amount of 10° from an initial value of 0° to an end value of 80°.

[0037] Furthermore, prior to the image reconstruction process by the image reconstruction unit 14, the X-direction projection data x acquired for each direction θ (each direction θ with an update amount of 10° from an initial value of 0° to a final value of 80°) １ ~x Ｎ and Y-direction projection data y １ ~y Ｍ After subtracting an offset from the projection data, alignment was performed using the center of gravity. The offset is the value of the projection data output when no light is incident on the light receiving section of the two-dimensional projection data acquisition sensor 11, and in this example, it was 25. The FBP method was used as the image reconstruction algorithm.

[0038] 5 and 6 are diagrams showing two-dimensional light intensity profiles obtained by image reconstruction processing in the example. Fig. 5 shows an image of an aperture. Fig. 6 shows an image obtained when a wire is placed in part of the aperture, and an image is obtained in which part of the aperture is shielded by the wire.

[0039] As described above, according to this embodiment, a two-dimensional image can be acquired using a two-dimensional projection data acquisition sensor. That is, the two-dimensional projection data acquisition sensor can be used to detect the position of a spot light or a moving object on the light receiving unit, and can also measure a two-dimensional light intensity profile on the light receiving unit without using a normal area sensor.

[0040] The two-dimensional image acquisition device and the two-dimensional image acquisition method are not limited to the above-described embodiment and configuration example, and various modifications are possible.

[0041] The two-dimensional image acquisition device of the first aspect according to the above embodiment includes: (1) a two-dimensional projection data acquisition sensor that acquires a one-dimensional light intensity profile obtained by integrating the two-dimensional light intensity profile in the light receiving unit in each of the x and y directions; (2) an orientation change unit that changes the relative orientation of the two-dimensional light intensity profile in the light receiving unit; and (3) an image reconstruction unit that performs image reconstruction based on data of the one-dimensional light intensity profile acquired by the two-dimensional projection data acquisition sensor when the two-dimensional light intensity profile in the light receiving unit is set in each of a plurality of orientations by the orientation change unit, thereby determining the two-dimensional light intensity profile in the light receiving unit.

[0042] In the second aspect of the two-dimensional image acquisition device, in the configuration of the first aspect, the orientation change unit may be configured to include a stage that rotates the two-dimensional projection data acquisition sensor around a straight line perpendicular to the light receiving unit of the two-dimensional projection data acquisition sensor.

[0043] In the two-dimensional image acquisition device of the third aspect, in the configuration of the first or second aspect, the orientation change unit may be configured to include an optical system that rotates the orientation of the two-dimensional light intensity profile in the light receiving unit of the sensor for acquiring two-dimensional projection data.

[0044] The two-dimensional image acquisition method of the first aspect according to the above embodiment includes: (1) a two-dimensional projection data acquisition step of acquiring a one-dimensional light intensity profile by integrating the two-dimensional light intensity profile at the light receiving unit in each of the x direction and the y direction using a two-dimensional projection data acquisition sensor; (2) an orientation change step of changing the relative orientation of the two-dimensional light intensity profile at the light receiving unit; and (3) an image reconstruction step of performing image reconstruction based on data of the one-dimensional light intensity profile acquired by the two-dimensional projection data acquisition sensor when the two-dimensional light intensity profile at the light receiving unit is set in each of a plurality of orientations by the orientation change step, to obtain the two-dimensional light intensity profile at the light receiving unit.

[0045] In the two-dimensional image acquisition method of the second aspect, in the configuration of the first aspect, the orientation change step may be configured to change the relative orientation of the two-dimensional light intensity profile in the light receiving section using a stage that rotates the two-dimensional projection data acquisition sensor around a straight line perpendicular to the light receiving section of the two-dimensional projection data acquisition sensor.

[0046] In the two-dimensional image acquisition method of the third aspect, in the configuration of the first or second aspect, the orientation change step may be configured to change the relative orientation of the two-dimensional light intensity profile in the light receiving unit using an optical system that rotates the orientation of the two-dimensional light intensity profile in the light receiving unit of the sensor for acquiring two-dimensional projection data.

[0047] The present invention can be used as a two-dimensional image acquisition device and a two-dimensional image acquisition method that can acquire a two-dimensional image using a sensor for acquiring two-dimensional projection data.

[0048] 1... two-dimensional image acquisition device, 11... two-dimensional projection data acquisition sensor, 12... stage, 13... optical system, 14... image reconstruction unit

Claims

1. A two-dimensional image acquisition device comprising: a two-dimensional projection data acquisition sensor that acquires a one-dimensional light intensity profile obtained by integrating a two-dimensional light intensity profile in the light receiving unit in the x direction and the y direction respectively; an orientation change unit that changes the relative orientation of the two-dimensional light intensity profile in the light receiving unit; and an image reconstruction unit that performs image reconstruction based on the data of the one-dimensional light intensity profile acquired by the two-dimensional projection data acquisition sensor when the two-dimensional light intensity profile is set in each of a plurality of orientations in the light receiving unit by the orientation change unit, and obtains the two-dimensional light intensity profile in the light receiving unit.

2. The two-dimensional image acquisition device according to claim 1, wherein the orientation change unit includes a stage that rotates the two-dimensional projection data acquisition sensor around a straight line perpendicular to the light receiving unit of the two-dimensional projection data acquisition sensor.

3. The two-dimensional image acquisition device according to claim 1 or 2, wherein the orientation change unit includes an optical system that rotates the orientation of the two-dimensional light intensity profile in the light receiving unit of the two-dimensional projection data acquisition sensor.

4. A two-dimensional image acquisition method comprising: a two-dimensional projection data acquisition step of acquiring a one-dimensional light intensity profile obtained by integrating a two-dimensional light intensity profile in the light receiving unit in the x direction and the y direction respectively using a two-dimensional projection data acquisition sensor; an orientation change step of changing the relative orientation of the two-dimensional light intensity profile in the light receiving unit; and an image reconstruction step of performing image reconstruction based on the data of the one-dimensional light intensity profile acquired by the two-dimensional projection data acquisition sensor when the two-dimensional light intensity profile is set in each of a plurality of orientations in the light receiving unit by the orientation change step, and obtaining the two-dimensional light intensity profile in the light receiving unit.

5. The two-dimensional image acquisition method according to claim 4, wherein in the orientation change step, the relative orientation of the two-dimensional light intensity profile in the light receiving unit is changed using a stage that rotates the two-dimensional projection data acquisition sensor around a straight line perpendicular to the light receiving unit of the two-dimensional projection data acquisition sensor.

6. The two-dimensional image acquisition method according to claim 4 or 5, wherein in the orientation change step, an optical system that rotates the orientation of the two-dimensional light intensity profile in the light receiving unit of the two-dimensional projection data acquisition sensor is used to change the relative orientation of the two-dimensional light intensity profile in the light receiving unit.

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