Information processing device, optical coherence tomography device, information processing method, and program

Abstract

To provide a new technology for optimizing scan data acquired in a full range OCT.SOLUTION: An information processor includes an identification part and a resize processing part. The identification part identifies redundancy in a lateral direction on the basis of B scan data obtained by performing B scanning to an object to be measured by using an optical coherence tomography. The resize processing part changes data size of the B scan data on the basis of the redundancy identified by the identification part.SELECTED DRAWING: Figure 16

Description

[Technical Field]

[0001] The present invention relates to an information processing device, an optical coherence tomography device, an information processing method, and a program. [Background technology]

[0002] Optical Coherence Tomography (OCT), which uses a light beam from a laser or other source to form images that represent the surface and internal morphology of an object, has been attracting attention in recent years. Unlike X-ray computed tomography (CT), OCT is non-invasive, and is therefore expected to be particularly applicable in the medical and biological fields. For example, in the field of ophthalmology, OCT devices are being put to practical use to form images of the fundus and cornea, and to measure intraocular distances such as the axial length.

[0003] It is known that various artifacts appear in images (tomographic images, OCT images) of a measured object acquired using OCT. In particular, complex conjugate artifacts (ghost images, mirror images) appear in images acquired using Fourier Domain OCT (FD-OCT), such as Spectral Domain OCT (SD-OCT) and Swept Source OCT (SS-OCT). Complex conjugate artifacts are virtual images that appear on the opposite side of the real image from the zero-delay position, where the optical path length of the measurement light irradiated on the measured object is equal to the optical path length of the reference light. Complex conjugate artifacts limit the observable depth range. Eliminating complex conjugate artifacts enables observation of deeper areas of a measured object and wide-angle observation.

[0004] One method for removing such complex conjugate artifacts is full-range OCT, which uses a phase shift method to restore the complex interference spectrum. Techniques for realizing full-range OCT using such a phase shift method are disclosed in, for example, Non-Patent Documents 1, 2, and 3. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Y. Yasuno et al., “Simultaneous BM-mode scanning method for real-time full-range Fourier domain optical coherence tomography”, APPLIED OPTICS, March 10, 2006, Vol.45, No.8, pp.1861-1865 [Non-patent document 2] B. Baumann et al., “Full range complex spectral domain optical coherence tomography without additional phase shifters”, OPTICS EXPRESS, October 1, 2007, Vol.15, No.20, pp.13375-13387 [Non-patent document 3] S. Makita et al., “Full-range, high-speed, high-resolution, 1-μm spectral-domain optical coherence tomography using BM-scan for volumetric imaging of the human posterior eye”, OPTICS EXPRESS, June 9, 2008, Vol.16, No.12, pp.8406-8420 Summary of the Invention [Problem to be solved by the invention]

[0006] To realize full-range OCT using the phase shift method disclosed in Non-Patent Documents 1 to 3, it is necessary to perform A-scans in the lateral direction at intervals finer than the lateral resolution of the imaging light (measurement light) irradiated onto the object to be measured.

[0007] However, the present inventors' analysis revealed that the scan data acquired by the above scans has a high degree of lateral redundancy compared to the data considered necessary for observation or analysis. If the scan data can be optimized to reduce redundancy without reducing the amount of information, it will be possible to achieve observation over a long range in the depth direction using full-range OCT, while also achieving secondary benefits such as reduced processing time and resource savings.

[0008] The present invention has been made in view of the above circumstances, and one of its objects is to provide a new technique for optimizing scan data acquired in full-range OCT. [Means for solving the problem]

[0009] One aspect of the embodiment is an information processing device including: an identification unit that identifies lateral redundancy from B-scan data obtained by performing a B-scan on a measured object using optical coherence tomography; and a resizing processing unit that changes the data size of the B-scan data based on the redundancy identified by the identification unit. Another aspect of the embodiment is an optical coherence tomography device including an optical scanner, an interference optical system that splits light from a light source into reference light and measurement light, irradiates the measurement light deflected by the optical scanner onto the object to be measured, and detects interference light between return light of the measurement light from the object to be measured and the reference light, a control unit that controls the optical scanner and also controls the interference optical system to change the difference between the optical path length of the reference light and the optical path length of the measurement light for each A scan, a scan data generation unit that generates the B scan data based on the detection result of the interference light, and the above-mentioned information processing device. Yet another aspect of the embodiment is an information processing method including: a specifying step of specifying a lateral redundancy from B-scan data obtained by performing a B-scan on a measured object using optical coherence tomography; and a resizing step of changing a data size of the B-scan data based on the redundancy specified in the specifying step. Yet another aspect of the embodiment is a program that causes a computer to execute each step of the above-described information processing method. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a new technique for optimizing scan data acquired in full-range OCT. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram illustrating an example of the configuration of an OCT apparatus according to an embodiment. [Figure 2] 1 is a schematic diagram illustrating an overview of the operation of an OCT device according to an embodiment. [Figure 3] FIG. 2 is an explanatory diagram of the operation of an information processing method according to the embodiment. [Figure 4] FIG. 2 is an explanatory diagram of the operation of an information processing method according to the embodiment. [Figure 5] FIG. 2 is an explanatory diagram of the operation of an information processing method according to the embodiment. [Figure 6] FIG. 2 is an explanatory diagram of the operation of an information processing method according to the embodiment. [Figure 7] FIG. 2 is an explanatory diagram of the operation of an information processing method according to the embodiment. [Figure 8] FIG. 2 is an explanatory diagram of the operation of an information processing method according to the embodiment. [Figure 9] FIG. 2 is an explanatory diagram of the operation of an information processing method according to the embodiment. [Figure 10] FIG. 2 is an explanatory diagram of the operation of an information processing method according to the embodiment. [Figure 11] 1 is a schematic diagram illustrating an example of the configuration of an optical system of an ophthalmologic apparatus according to an embodiment. [Figure 12] 1 is a schematic diagram illustrating an example of the configuration of an optical system of an ophthalmologic apparatus according to an embodiment. [Figure 13] FIG. 2 is a schematic diagram illustrating an example of the configuration of a processing system of an ophthalmologic apparatus according to an embodiment. [Figure 14] 3A to 3C are diagrams illustrating the operation of the ophthalmologic apparatus according to the embodiment. [Figure 15] FIG. 2 is a schematic diagram illustrating an example of the configuration of a processing system of an ophthalmologic apparatus according to an embodiment. [Figure 16] FIG. 2 is a schematic diagram illustrating an example of the configuration of a processing system of an ophthalmologic apparatus according to an embodiment. [Figure 17] FIG. 4 is a flowchart of an example of the operation of the ophthalmologic apparatus according to the embodiment. [Figure 18] FIG. 4 is a flowchart of an example of the operation of the ophthalmologic apparatus according to the embodiment. [Figure 19] FIG. 4 is a flowchart of an example of the operation of the ophthalmologic apparatus according to the embodiment. [Figure 20] FIG. 10 is a schematic diagram illustrating an example of the configuration of an optical system of an ophthalmologic apparatus according to a first modified example of an embodiment. [Figure 21] FIG. 10 is a schematic diagram illustrating an example of the configuration of an optical system of an ophthalmologic apparatus according to a second modified example of the embodiment. [Figure 22] FIG. 10 is a schematic diagram illustrating an example of the configuration of a processing system of an ophthalmologic apparatus according to a second modified example of an embodiment. [Figure 23] FIG. 10 is a schematic diagram illustrating an example of the configuration of an optical system of an ophthalmologic apparatus according to a third modified example of the embodiment. [Figure 24] FIG. 10 is a schematic diagram illustrating an example of the configuration of an optical system of an ophthalmologic apparatus according to a fourth modified example of the embodiment. [Figure 25] FIG. 10 is a schematic diagram illustrating an example of the configuration of an optical system of an ophthalmologic apparatus according to a fifth modified example of an embodiment. [Figure 26] FIG. 13 is a schematic diagram illustrating an example of the configuration of an optical system of an ophthalmologic apparatus according to a sixth modified example of an embodiment. [Figure 27] FIG. 2 is a schematic diagram illustrating an example of the configuration of an optical system of an ophthalmic apparatus according to an embodiment or first to fifth modified examples of the embodiment. [Figure 28]FIG. 13 is a schematic diagram illustrating an example of the configuration of an optical system of an ophthalmologic apparatus according to a sixth modified example of an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The following describes in detail exemplary embodiments of an information processing device, an optical coherence tomography (OCT) device, an information processing method, and a program according to the present invention, with reference to the accompanying drawings. Note that the contents of documents cited in this specification and any publicly known techniques may be incorporated into the following exemplary embodiments.

[0013] An information processing device according to an embodiment identifies redundancy in the lateral direction (B-scan direction) from B-scan data obtained by performing a B-scan on an object to be measured using OCT (SD-OCT or SS-OCT), and changes the data size of the B-scan data based on the identified redundancy. The B-scan data may be an interference signal obtained by performing a B-scan, or image data of a B-scan image. The information processing device resizes the data size by reducing the B-scan data in the lateral direction based on the redundancy. The information processing device can display an image (OCT image, tomographic image) of the object to be measured on a display unit based on the B-scan data whose data size has been changed.

[0014] Examples of data size reduction in the lateral direction include averaging two or more A-scan data adjacent in the lateral direction, thinning out A-scan data arranged in the lateral direction, etc. Examples of objects to be measured include biological tissues such as intraocular tissue, internal skin tissue, teeth, oral tissue, and organ tissue, as well as objects to be inspected in non-destructive testing.

[0015] The OCT device according to the embodiment includes the information processing device according to the embodiment, and acquires B-scan data by performing an OCT scan using an optical scanner. The OCT device is capable of identifying redundancy in the lateral direction from the acquired B-scan data and changing the data size of the B-scan data based on the identified redundancy.

[0016] An information processing method according to an embodiment includes one or more steps for realizing the functions of the information processing device described above. A program according to an embodiment causes a computer (processor) to execute each step of the information processing method according to an embodiment. A recording medium according to an embodiment is a non-transitory recording medium (storage medium) that can be read from a computer and that has a program according to an embodiment recorded thereon.

[0017] In this specification, a processor includes circuits such as a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), or a field programmable gate array (FPGA)). The processor realizes the functions of the embodiments by, for example, reading and executing a program stored in a memory circuit or a storage device. The memory circuit or storage device may be included in the processor. Alternatively, the memory circuit or storage device may be provided external to the processor.

[0018] In some embodiments, the B-scan data whose data size is changed is scan data that is frequency modulated in the lateral direction by shifting the phase for each A-scan. Examples of such scan data include B-scan data acquired by a BM scan disclosed in Non-Patent Documents 1 to 3.

[0019] In the following embodiment, a case will be described in which the data size of B-scan data acquired by performing a BM scan on a measured object is reduced. However, the configuration according to the embodiment is not limited to the configuration in which the B-scan data acquired by the BM scan is resized.

[0020] First, a BM scan according to the embodiment will be described. Hereinafter, the direction (left-right direction, horizontal direction) perpendicular to the optical axis direction of the optical system (interference optical system) will be referred to as the x direction, the direction (up-down direction, vertical direction) perpendicular to the optical axis direction will be referred to as the y direction, and the optical axis direction will be referred to as the z direction.

[0021] <BMスキャン> BM scanning is one of the scans that achieves full-range OCT using an interference optical system. The interference optical system splits the light from a light source into reference light and measurement light, irradiates the measurement light onto the object under test, and detects the interference light between the reference light and the measurement light returned from the object under test. At this time, the measurement light is deflected by an optical scanner, moving the incident position of the measurement light on the object under test (A-scan position) in the lateral direction. BM scanning performs phase modulation (frequency modulation) in the lateral direction by shifting the phase for each A-scan while performing a B-scan on the object under test.

[0022] Hereinafter, for convenience of explanation, the lateral direction is defined as the x direction, but unless otherwise specified, the lateral direction may be the y direction. Here, the electric field output from the measurement light at the scan position x and wave number k is defined as E S (x, k), and the electric field output from the reference light at wave number k is E R If the phase shift amount of the interference light corresponding to the scan position x of the A-scan is denoted as ψ(x) using the symbol ψ(psi), the output I(x, k) of the detector that detects the interference light is expressed as in equation (1).

[0023]

number

[0024] In formula (1), E S * (x,k) is E S represents the complex conjugate of (x,k), and E R * (k) is E Rrepresents the complex conjugate of (k). exp(iψ(x)) represents the effect of the phase shift at scan position x. The first term on the right-hand side of equation (1) represents the signal component of the measurement light, and the second term represents the signal component of the reference light. One of the third and fourth terms represents the signal component of the interference light (interference signal component) of the object of observation, and the other represents the signal component of the ghost image. Comparing the third and fourth terms, it can be seen that the interference signal component of the object of observation and the signal component of the ghost image are components with phase shifts in different directions. A BM scan is an OCT scan that acquires the above-mentioned interference signal components while shifting the phase for each A-scan.

[0025] The detector output I(x, k) shown in equation (1) obtained by performing a BM scan is Fourier transformed along the lateral direction (spatial direction, x direction) to be expressed as equation (2).

[0026]

number

[0027] In equation (2), FT x {} represents the Fourier transform along the x direction (lateral direction). Since the scan position x is a function of time t that changes over time t, the x direction may also be the t direction.

[0028] For convenience of explanation, the following will describe the case where the phase shift amount ψ(x) of the BM scan increases at a constant rate depending on the scan position x. In this case, the phase shift amount ψ(x) can be expressed as ψ(x)=Φx using the phase change amount Φ of the interference signal. In this case, the third term on the right side of equation (2) can be transformed into equation (3).

[0029]

number

[0030] In Equation (3), the operator "*" represents a convolution integral operation along the u direction (time frequency direction, spatial frequency direction), and δ represents a delta function. The cross-correlation term E between the measurement light and the reference light S (x,k)E R * The term FT obtained by Fourier transforming (k) in the x direction x {E S (x,k)E R * (k)} is expressed as B(u,k), then equation (3) can be expressed as equation (4).

[0031]

number

[0032] That is, equation (3) showing the third term on the right side of equation (2) is a component obtained by translating B(u,k) by the phase change amount (modulation amount) Φ along the u direction.

[0033] Similarly, the fourth term on the right side of equation (2) can be expressed as equation (5).

[0034]

number

[0035] In equation (5), B * (u,k) represents the complex conjugate of B(u,k).

[0036] Using equations (4) and (5), equation (2) can be expressed as equation (6).

[0037]

number

[0038] That is, by acquiring the interference signal while adding the phase shift amount Φ, the interference signal component B of the OCT of the observation target and the signal component B of the ghost image are obtained. *and can be shifted in different directions in the spatial frequency domain (time frequency domain).

[0039] Here, signal component B (or signal component B * When the spectrum is weighted with a window function to extract only the component (x), and an inverse Fourier transform is performed in the u direction, it is expressed as in equation (7). Examples of window functions include the Heaviside step function, Gaussian window function, Hann window function, Hamming window function, and raised cosine filter. In equation (7), the Heaviside step function is used as the window function.

[0040]

number

[0041] Equation (7) expresses the complex-valued interference signal I′(x,k), which contains only the interference signal of the observed OCT. Similar to the well-known Fourier-domain OCT, by performing a Fourier transform on this interference signal I′(x,k) along the wavenumber k direction, a full-range OCT image with ghost images removed can be reconstructed.

[0042] Here, the spatial spectrum (spread) of the cross-correlation between the measurement light and the reference light is expressed by the above B(u, k). R (k) and E S Assuming that there is no phase shift effect on (x, k) and that the spread h(x) of the measurement light does not depend on the depth direction of the object for the scattering spatial spectrum (distribution) S(x, k) of the object, E S (x, k) is expressed as the convolution integral of the scattering spatial spectrum S(x, k) of the object to be measured and the spread h(x) of the measurement light, as shown in equation (8).

[0043]

number

[0044] E shown in equation (8) SWhen (x, k) is Fourier transformed in the x direction, it is expressed as in equation (9).

[0045]

number

[0046] In equation (9), H(u) represents the spatial spectrum distribution of the measurement light. The spatial spectrum H(u) of the spread h(x) of the measurement light can be calculated based on the optical parameters of the OCT optical system (imaging system).

[0047] B(u,k) is FT x {E S (x,k)E R * (k)}, and the electric field E generated in the reference path R * (k) does not depend on the scan position x. Therefore, the spatial spectrum distribution of B(u,k) in the u direction depends on the spatial spectrum H(u) of the measurement light spread h(x) and the scattering spatial spectrum S(x,k) of the object under test.

[0048] The spatial spectrum H(u) is determined by, for example, the diameter of the beam (cross section) of the measurement light. If we assume that the spread of the measurement light (spatial distribution of intensity) h(x) follows a Gaussian distribution, the intensity is expressed as (1 / e 2 When the diameter of the measurement light beam at the position where the diameter is d, the intensity of the spatial spectrum H(u) is (1 / e 2 ) doubles the bandwidth at f d is expressed as in equation (10) (see Non-Patent Document 3).

[0049]

number

[0050] In equation (10), f Arepresents the number of A-scans in a B-scan (number of A-scan positions), and Δx represents the interval between A-scans (interval between A-scan positions). In other words, the bandwidth f of the spatial spectrum H(u) of the measurement light d is the diameter d of the measurement light beam (cross section) and the number of A scans in the B scan f A and the A-scan interval Δx.

[0051] As described above, when the object to be measured is the same (the same scattering spatial spectrum S(x,k)), B(u,k) changes depending on the spatial spectrum H(u) of the measurement light. Therefore, the bandwidth f d is one of the indicators of the spatial spectrum spread represented by B(u,k).

[0052] As described in Non-Patent Document 3, the bandwidth f d represents the spread in the spatial frequency domain (time frequency domain). In order to sufficiently suppress ghost images, theoretically, the bandwidth f d As shown in equation (10), the bandwidth f d To reduce this, it is necessary to increase the diameter d of the measurement light beam or reduce the A-scan interval Δx. At a certain diameter d, it is necessary to reduce Δx.

[0053] As described above, in a BM scan that performs phase modulation, the interval (=Δx) between adjacent A-scan positions in the x direction (lateral direction) needs to be small. When a BM scan is performed while satisfying this condition, the measurement light is irradiated so that it overlaps with the A-scan positions that are close to the object being measured, which tends to increase the redundancy of the scan data.

[0054] For example, in Non-Patent Document 3, in order to most effectively suppress ghost images, it is described that the phase is shifted by π / 2 for each adjacent A scan, and a BM scan is performed with Δx = ~3 [μm] and d = ~20 [μm]. At this time, the scan density (Δx / d) becomes 0.15. In this case, the BM scan is performed with a margin from the theoretical value ((Δx / d) < (π / 8) = ~0.39, see Non-Patent Document 3) (so that the interval between A scan positions becomes smaller).

[0055] For example, in an ophthalmic apparatus that performs an OCT scan with measurement light having a lateral resolution of 20 [μm] on a living eye as the object to be measured, when 1024 A scans are performed with a scan length of 6 mm (in the B scan direction) on the fundus, the interval Δx between adjacent A scan positions is approximately 5.9 [μm]. Therefore, the scan density (Δx / d) of the A scan is approximately 0.3. At this time, a high-definition tomographic image of the fundus as the object to be measured can be obtained.

[0056] For example, the information processing apparatus according to the embodiment can resize the data size so that the scan density becomes a predetermined value (for example, 0.3 as described above) for the B scan data frequency-modulated in the lateral direction by shifting the phase for each A scan. Thereby, the redundancy can be reduced without reducing the amount of information, and the scan data can be optimized. Therefore, while realizing observation in a long range in the depth direction by full-range OCT, secondary effects such as shortening of the processing time and saving of resources can be obtained.

[0057] Next, the configuration and method according to the embodiment will be described.

[0058] <OCT apparatus> FIG. 1 shows a block diagram of a configuration example of an OCT apparatus to which the information processing apparatus according to the embodiment is applied.

[0059] The OCT device 500 according to the embodiment includes an interference optical system 510, an optical scanner 520, a scan data generation unit 530, a control unit 540, and an information processing unit 600. In some embodiments, the information processing unit 600 is provided as an information processing device outside the OCT device 500. In this case, the information processing unit 600 can acquire scan data generated by the OCT device 500 using a known communication means. In some embodiments, the information processing unit 600 includes the function of the scan data generation unit 530.

[0060] The interference optical system 510 splits light from a light source into reference light and measurement light, irradiates the measurement light onto the object under test 700 via the optical scanner 520, and detects interference light between the reference light and the measurement light returned from the object under test 700. The object under test 700 may be any object as long as a tomographic image can be acquired by OCT scanning. The optical scanner 520 deflects the measurement light from the interference optical system 510 and guides it to the object under test 700, and also guides the measurement light returned from the object under test 700 to the interference optical system 510. Under the control of the control unit 540, the optical scanner 520 sequentially deflects the measurement light so that the incident position (A-scan position) of the measurement light on the object under test 700 moves in a predetermined lateral direction. The scan data generation unit 530 generates B-scan data based on the detection results of the interference light obtained by the interference optical system 510. The functions of the scan data generation unit 530 are realized by one or more processors, as described below.

[0061] The control unit 540 controls each of the interference optical system 510, the optical scanner 520, the scan data generation unit 530, and the information processing unit 600. In particular, the control unit 540 can perform a BM scan by controlling the interference optical system 510 to change (phase modulate) the difference between the optical path length of the reference light and the optical path length of the measurement light for each A-scan in synchronization with deflection control of the optical scanner 520. This allows the scan data generation unit 530 to generate B-scan data that is frequency modulated (phase modulated) in the lateral direction by shifting the phase for each A-scan. The functions of the control unit 540 are realized by one or more processors, as described below.

[0062] The information processing unit 600 realizes the functions of the information processing device according to the embodiment. The information processing unit 600 identifies redundancy in the lateral direction (B-scan direction) from the B-scan data generated by the scan data generating unit 530. The information processing unit 600 can identify redundancy based on a spatial spectrum in the spatial frequency domain (time frequency domain).

[0063] In some embodiments, the information processing unit 600 identifies the scan density of the A-scans based on the spatial spectrum, and identifies the redundancy based on a predetermined reference scan density and the identified scan density.

[0064] In some embodiments, the information processing unit 600 determines the redundancy based on the width of the spatial spectrum in the spatial frequency direction. For example, the information processing unit 600 performs a function fitting process on the spatial spectrum and determines the width of the spatial spectrum based on the function obtained by the fitting process.

[0065] The information processing unit 600 resizes the data size by reducing the B-scan data in the lateral direction based on the identified redundancy. For example, the information processing unit 600 forms a tomographic image of the object under test 700 based on the B-scan data whose data size has been changed. The functions of the information processing unit 600 are realized by one or more processors, as will be described later.

[0066] This makes it possible to optimize scan data to reduce redundancy without reducing the amount of information, enabling observation over a long depth range using full-range OCT while also achieving secondary benefits such as reduced processing time and resource savings.

[0067] 2 to 10 show an example of the operation of the OCT device 500 of FIG. 1. FIG. 2 is a schematic diagram showing an outline of the operation of the scan data generation unit 530 and the information processing unit 600 of FIG. 1. FIGS. 3 to 10 are diagrams explaining the operation of steps SQ2 to SQ8 of FIG. 2. FIGS. 3 to 10 show a case where an OCT scan is performed on a mirror tool as the object to be measured 700. In this case, the measurement light is reflected at a substantially constant z position (depth position) in the z direction (depth direction).

[0068] The OCT device 500 sequentially executes processes SQ1 to SQ8 shown in Fig. 2. In process SQ7, redundancy is calculated using the processing result obtained in process SQ3. In process SQ8, the data size of the B-scan data is resized in the x direction (lateral direction, B-scan direction) using the redundancy calculated in process SQ7.

[0069] (SQ1: OCT scan) First, the control unit 540 controls the interference optical system 510 and the optical scanner 520 to perform an OCT scan on the object 700 to be measured.

[0070] Specifically, the control unit 540 controls the optical scanner 520 to deflect the measurement light in a preset x-direction, and controls the interference optical system 510 to change (phase-modulate) the difference between the optical path length of the reference light and the optical path length of the measurement light for each A-scan. As a result, multiple A-scan data items that are frequency-modulated in the lateral direction are acquired by shifting the phase for each A-scan.

[0071] (SQ2: Rescaling) Next, the control unit 540 controls the scan data generation unit 530 to perform a rescaling process on the A-scan data obtained by the interference optical system 510. The rescaling process converts the scan data in wavelength (λ) space into scan data in wavenumber (k) space. For example, in process SQ2, the scan data shown in equation (1) is obtained.

[0072] The scan data obtained in process SQ2 is shown schematically in Figure 3. The horizontal axis represents the x-direction, and the vertical axis represents the wave number direction.

[0073] As described above, A-scans that change the difference between the optical path length of the reference light and the optical path length of the measurement light for each A-scan are performed sequentially in the x direction for the mirror tool as the object to be measured 700, so that the stripe pattern (the shading represents the difference in intensity) shifts in the x direction as shown in Figure 3.

[0074] (SQ3: Fourier transform in the x direction) Next, the control unit 540 controls the scan data generation unit 530 to perform a Fourier transform in the x direction on the scan data after the rescaling process obtained by process SQ2. The scan data generation unit 530 performs the process as shown in equations (2) to (6), for example.

[0075] The scan data obtained in process SQ3 is shown schematically in Figure 4. The horizontal axis represents the positive u direction and the negative u direction centered on the origin of the u (spatial frequency, temporal frequency) axis, and the vertical axis represents the wave number direction.

[0076] As shown in Figure 4, with the origin of the u axis as the reference, signal component B is in the +u direction, and signal component B, which is the complex conjugate of signal component B, is in the -u direction. * (See equation (6), which is a transformation of equation (2)).

[0077] (SQ4: Multiply the window function in the u direction) Next, the control unit 540 controls the scan data generation unit 530 to multiply the scan data after Fourier transform processing obtained by process SQ3 by a window function in the u direction, thereby extracting, for example, a signal component B in the +u direction from the equation shown in equation (6).

[0078] For example, as described above, the window function may be the Heavyside step function, which outputs a function value of "1" for a positive argument u and a value of "0" for a negative argument u that is equal to or less than 0.

[0079] The scan data obtained in step SQ4 is shown schematically in Figure 5. The horizontal axis represents the +u and -u directions centered on the origin of the u axis, and the vertical axis represents the wave number direction.

[0080] As shown in Figure 5, by multiplying the scan data after Fourier transform processing obtained by process SQ3 by a Heavyside step function in the u direction, only the signal component B in the +u direction is output. At this time, scan data where u=0 is also removed, making it possible to remove pattern noise superimposed on all A-scan data. In practice, taking into account that the pattern noise components superimposed on all A-scan data may have a width around u=0, a Heavyside step function shifted in the +u direction may be used instead of the Heavyside step function.

[0081] (SQ5: Inverse Fourier transform in the u direction) Next, the control unit 540 controls the scan data generation unit 530 to perform an inverse Fourier transform in the u direction on the window function processed scan data obtained in the process SQ4, as shown in equation (7).

[0082] Figure 6 shows a schematic representation of the scan data obtained in step SQ5. Figure 6 shows the real and imaginary parts of the scan data after inverse Fourier transform processing. For each of the real and imaginary parts shown in Figure 6, the horizontal axis represents the x-direction, and the vertical axis represents the wavenumber direction.

[0083] Although it is difficult to distinguish in Figure 6, the stripe pattern is shifted in the x direction by the amount of phase shift for each A-scan relative to the real part.

[0084] (SQ6: Fourier transform in k direction) Next, the control unit 540 controls the scan data generation unit 530 to perform a Fourier transform process in the k direction on the scan data after the inverse Fourier transform process obtained in process SQ5.

[0085] 7 shows a schematic representation of the B-scan data obtained in step SQ6, where the horizontal axis represents the x-direction and the vertical axis represents the z-direction.

[0086] As shown in FIG. 7, a mirror tool (reflecting surface) placed at a substantially constant z position (depth position) in the z direction is visualized.

[0087] As described above, the B-scan data obtained in process SQ7 is processed so that the A-scans overlap excessively in the x direction, resulting in high redundancy in the x direction of the scan data. Therefore, in this embodiment, redundancy is calculated based on the scan data obtained in process SQ3, and the B-scan data obtained in process SQ7 is resized in the x direction according to the calculated redundancy.

[0088] (SQ7: Calculate redundancy) The control unit 540 controls the information processing unit 600 to calculate redundancy based on the scan data after the Fourier transform process obtained in process SQ3.

[0089] Here, when the above formula (10) is transformed, it is expressed as formula (11).

[0090]

number

[0091] In equation (11), f d ′ represents the spatial spectrum bandwidth of the B-scan interference signal. As mentioned above, the number of A-scans f A The A-scan interval Δx is given by the scan conditions. The bandwidth f of the spatial spectrum B(u,k) (or B(u-Φ,k)) of the B-scan interference signal, which indicates the cross-correlation between the measurement light and the reference light, is d ' varies depending on the object 700. In this case, the spatial spectrum B(u,k) of the interference signal of the B scan is obtained from the scan data obtained by the OCT scan, and the bandwidth f is calculated from the obtained spatial spectrum B(u,k) (or B(u-Φ,k)). dIt is possible to specify

[0092] Fig. 8 shows a schematic representation of the spatial spectrum B(u, k) that indicates the cross-correlation between the measurement light and the reference light. Fig. 8 shows a schematic representation of the u cross section of the spatial spectrum B(u, k) at a given wave number k. The horizontal axis represents the +u and -u directions centered on the origin of the u axis, and the vertical axis represents the amplitude of the spectrum.

[0093] As shown in equation (6), the spatial spectrum B(u,k) appears in the range of the +u direction, and the spatial spectrum B * Here, the information processing unit 600 extracts the spatial spectrum B(u, k) in the +u direction from the spatial spectrum B(u, k) of the processing SQ3 obtained by the scan data generation unit 530.

[0094] 9 shows a schematic diagram of the spatial spectrum B(u, k) in the +u direction. The horizontal axis represents the u (spatial frequency, temporal frequency) direction, and the vertical axis represents the amplitude of the spectrum.

[0095] The information processing unit 600 performs fitting processing on the extracted spatial spectrum B(u,k) using a fitting function. Here, the Gaussian function g(u) shown in equation (12) is used as the fitting function.

[0096]

number

[0097] In equation (12), P represents the amplitude of the spectral signal, Q represents the baseline, c represents the center position of g(u), and σ represents the spread of the spatial spectrum.

[0098] The parameter σ of the fitting function (Gaussian function g(u) shown in Equation (12)) obtained by the fitting process is four times (the amplitude is 1 / e 2 (bandwidth f d In equation (11), f dBy substituting ′=4σ, the diameter d′ of the apparent measurement beam can be estimated as shown in equation (13).

[0099]

number

[0100] Therefore, the scan density, which is the interval Δx between the A-scan positions with respect to the diameter d of the measurement light beam, can be calculated as shown in equation (14).

[0101]

number

[0102] As described above, it is known that a high-resolution tomographic image can be acquired when the scan density is about 0.3, and when the scan density is less than 0.3, it is considered that the A-scans overlap excessively. Therefore, the information processing unit 600 calculates the redundancy R as shown in equation (15) by setting the reference scan density to 0.3.

[0103]

number

[0104] 9 shows a schematic diagram of the spatial spectrum B(u,k) and the Gaussian function g(u) obtained by fitting. The horizontal axis represents the u direction, and the vertical axis represents the amplitude of the spatial spectrum.

[0105] For example, in Figure 9, the amplitude P = 2.84 × 10 4 and the baseline Q = 9.41 × 10 2 The central position c is 3.87 × 10, and the spatial spectrum spread σ is 3.5. The number of A-scans f A = 256, and the A-scan position interval Δx = 5.9 × 10 -3 [mm], then from equation (13), the diameter of the apparent measuring light beam d' = 1.36 × 10 -1In this case, the redundancy R is calculated as 6.98 from equation (15).

[0106] As described above, the redundancy in the x direction can be calculated from the scan data acquired by the phase modulation method.

[0107] The redundancy is not limited to that obtained as described above.

[0108] For example, the information processing unit 600 may obtain the width in the u direction at a predetermined amplitude of the spatial spectrum B(u, k) or the fitting function (Gaussian function g(u) in FIG. 9) shown in FIG. 9, and identify the redundancy R corresponding to the obtained width in the u direction.

[0109] (SQ8: resize in x direction) Following process SQ6 and process SQ7, the information processing unit 600 resizes the post-Fourier transform B-scan data obtained in process SQ6 in the x direction based on the redundancy R obtained in process SQ7.

[0110] The information processing unit 600 resizes the data size of the B-scan data after the Fourier transform by (1 / R) times. Specifically, the information processing unit 600 resizes the data size of the B-scan data after the Fourier transform by (1 / R) times in the x direction.

[0111] Figure 10 shows a schematic representation of the B-scan data obtained in step SQ8, where the horizontal axis represents the x-direction and the vertical axis represents the z-direction.

[0112] For example, when the redundancy R is 6.98 as described above, the information processing unit 600 calculates the number of A-scans f A = 256 B-scan data, and the number of A-scans = 36.7 (= f A / R) or close to it. This allows the data size (image size) to be resized to an extent that does not affect the observation, without reducing the amount of information contained in the original B-scan data.

[0113] The information processing unit 600 outputs the resized B-scan data obtained in process SQ8 as full-range OCT scan data. The control unit 540 can use the output full-range OCT scan data to display on a display unit (not shown).

[0114] Next, the OCT device 500 according to the embodiment will be specifically described.

[0115] <Ophthalmological equipment> The following describes a case where the OCT device 500 according to the embodiment is applied to an ophthalmic device (i.e., when the object to be measured is an eye), but the device to which the OCT device according to the embodiment is applied is not limited to an ophthalmic device.

[0116] The ophthalmic apparatus may include, in addition to the OCT apparatus according to the embodiment, one or more of an ophthalmic imaging apparatus, an ophthalmic measurement apparatus, and an ophthalmic treatment apparatus. The ophthalmic imaging apparatus included in the ophthalmic apparatus of some embodiments is, for example, one or more of a fundus camera, a scanning laser ophthalmoscope, a slit lamp ophthalmoscope, a surgical microscope, etc. The ophthalmic measurement apparatus included in the ophthalmic apparatus of some embodiments is, for example, one or more of an eye refraction examination apparatus, a tonometer, a specular microscope, a wavefront analyzer, a perimeter, a microperimeter, etc. The ophthalmic treatment apparatus included in the ophthalmic apparatus of some embodiments is, for example, one or more of a laser treatment apparatus, a surgical apparatus, a surgical microscope, etc.

[0117] The ophthalmologic apparatus according to the following embodiment includes an OCT apparatus capable of OCT measurement and a fundus camera.

[0118] The following description will be given taking an ophthalmic apparatus capable of performing OCT measurement of the fundus of a test eye as an example, but the ophthalmic apparatus according to the embodiment may also be capable of OCT measurement of the anterior segment of the test eye. In some embodiments, the range and measurement site of the OCT measurement are changed by moving a lens that changes the focal position of the measurement light. In some embodiments, by adding one or more attachments (objective lens, front lens, etc.), a configuration is possible in which OCT measurement of the fundus, OCT measurement of the anterior segment, and OCT measurement of the entire eye including the fundus and the anterior segment are possible. In some embodiments, in an ophthalmic apparatus for fundus measurement, a front lens is placed between the objective lens and the test eye, and measurement light converted into a parallel beam is incident on the test eye, thereby performing OCT measurement of the anterior segment.

[0119] In this specification, images acquired by OCT may be collectively referred to as OCT images, and the measurement operation for forming an OCT image may be referred to as OCT measurement.

[0120] In the following embodiments, a case where a swept-source OCT technique is used in measurement or imaging using OCT will be described in detail. However, the configuration according to the embodiment can also be applied to an ophthalmic apparatus that uses another type of OCT (for example, a spectral domain type).

[0121] In the following embodiments, the x direction is the direction perpendicular to the optical axis direction of the objective lens (left-right direction, horizontal direction), the y direction is the direction perpendicular to the optical axis direction of the objective lens (up-down direction, vertical direction), and the z direction is the optical axis direction of the objective lens (interference optical system, OCT unit described later).

[0122] [composition] (Optical system configuration) As shown in Figures 11 and 12, the ophthalmologic apparatus 1 includes a fundus camera unit 2, an OCT unit 100, and an arithmetic and control unit 200. The fundus camera unit 2 has an optical system substantially similar to that of a conventional fundus camera. The OCT unit 100 is provided with an optical system for acquiring an OCT image of the fundus (or anterior segment). The arithmetic and control unit 200 includes a computer that executes various arithmetic processes, control processes, etc.

[0123] [Fundus camera unit 2] The fundus camera unit 2 shown in FIG. 11 is provided with an optical system for acquiring a two-dimensional image (fundus image) representing the surface morphology of the fundus Ef of the subject's eye E. Fundus images include observed images and photographed images. The observed images are, for example, monochrome moving images formed at a predetermined frame rate using near-infrared light. The photographed images may be, for example, color images obtained by flashing visible light, or monochrome still images using near-infrared light or visible light as illumination light. The fundus camera unit 2 may also be configured to acquire other images, such as fluorescein fluorescent images, indocyanine green fluorescent images, and autofluorescent images.

[0124] The fundus camera unit 2 is provided with a chin rest and a forehead rest for supporting the face of the subject. The fundus camera unit 2 is further provided with an illumination optical system 10 and a photographing optical system 30. The illumination optical system 10 irradiates the fundus Ef with illumination light. The photographing optical system 30 guides the fundus reflection light of this illumination light to an imaging device (CCD image sensors (sometimes simply referred to as CCDs) 35, 38). The photographing optical system 30 also guides measurement light from the OCT unit 100 to the fundus Ef, and also guides measurement light that has passed through the fundus Ef to the OCT unit 100.

[0125] The observation light source 11 of the illumination optical system 10 includes, for example, a halogen lamp. Light output from the observation light source 11 (observation illumination light) is reflected by a reflecting mirror 12 having a curved reflecting surface, passes through a condenser lens 13, and passes through a visible light cut filter 14 to become near-infrared light. The observation illumination light is then focused near the imaging light source 15, reflected by a mirror 16, and passes through relay lenses 17 and 18, an aperture 19, and a relay lens 20. The observation illumination light is then reflected by the peripheral portion (the area surrounding the hole) of the apertured mirror 21, passes through a dichroic mirror 48, and is refracted by the objective lens 22 to illuminate the fundus Ef. Note that an LED (Light Emitting Diode) can also be used as the observation light source.

[0126] The fundus reflected light of the observation illumination light is refracted by the objective lens 22, transmitted through the dichroic mirror 48, passes through the hole formed in the central region of the aperture mirror 21, transmitted through the dichroic mirror 55, passes through the focusing lens 31, and is reflected by the mirror 32. This fundus reflected light then transmits through the half mirror 33A, is reflected by the dichroic mirror 33, and is focused by the condenser lens 34 onto the light receiving surface of the CCD image sensor 35. The CCD image sensor 35 detects the fundus reflected light at, for example, a predetermined frame rate. An image (observation image) based on the fundus reflected light detected by the CCD image sensor 35 is displayed on the display device 3. When the focus of the photographing optical system 30 is adjusted to the anterior segment, an observation image of the anterior segment of the subject's eye E is displayed.

[0127] The imaging light source 15 includes, for example, a xenon lamp. Light (imaging illumination light) output from the imaging light source 15 is irradiated onto the fundus Ef along the same path as the observation illumination light. Fundus reflection light of the imaging illumination light is guided to the dichroic mirror 33 along the same path as the observation illumination light, passes through the dichroic mirror 33, is reflected by a mirror 36, and is focused on the light receiving surface of a CCD image sensor 38 by a condenser lens 37. An image (photographed image) based on the fundus reflection light detected by the CCD image sensor 38 is displayed on the display device 3. The display device 3 that displays the observation image and the display device 3 that displays the photographed image may be the same or different. When similar photography is performed by illuminating the subject's eye E with infrared light, an infrared photographed image is displayed. An LED may also be used as the imaging light source.

[0128] The LCD (Liquid Crystal Display) 39 displays a fixation target and a visual target for visual acuity measurement. The fixation target is a visual target for causing the subject's eye E to fixate, and is used during fundus photography, OCT measurement, and the like.

[0129] A portion of the light output from the LCD 39 is reflected by the half mirror 33A, reflected by the mirror 32, passes through the focusing lens 31 and the dichroic mirror 55, and passes through the hole in the aperture mirror 21. The light that has passed through the hole is transmitted through the dichroic mirror 48, refracted by the objective lens 22, and projected onto the fundus Ef.

[0130] The fixation position of the subject's eye E can be changed by changing the display position of the fixation target on the screen of the LCD 39. As with conventional fundus cameras, the fixation position of the subject's eye E can be, for example, a position for acquiring an image centered on the macular region of the fundus Ef, a position for acquiring an image centered on the optic disc, or a position for acquiring an image centered on the center of the fundus between the macular region and the optic disc. It is also possible to arbitrarily change the display position of the fixation target.

[0131] Furthermore, the fundus camera unit 2 is provided with an alignment optical system 50 and a focus optical system 60, similar to conventional fundus cameras. The alignment optical system 50 generates an index (alignment index) for aligning the device optical system with the subject's eye E. The focus optical system 60 generates an index (split index) for focusing on the fundus Ef.

[0132] Light (alignment light) output from an LED 51 of the alignment optical system 50 passes through apertures 52, 53 and a relay lens 54, is reflected by a dichroic mirror 55, and passes through the hole in the aperture mirror 21. The light that has passed through the hole is transmitted through a dichroic mirror 48 and is projected onto the cornea of ​​the subject's eye E by the objective lens 22.

[0133] The corneal reflection light of the alignment light passes through the objective lens 22, dichroic mirror 48, and the hole, and a portion of it passes through the dichroic mirror 55, passes through the focusing lens 31, is reflected by the mirror 32, and passes through the half mirror 33A. The corneal reflection light that passes through the half mirror 33A is reflected by the dichroic mirror 33 and is projected onto the light-receiving surface of the CCD image sensor 35 by the condenser lens 34. The light-receiving image (alignment index) by the CCD image sensor 35 is displayed on the display device 3 together with the observation image. The user performs alignment by performing operations similar to those of a conventional fundus camera. Alternatively, alignment may be performed by the arithmetic and control unit 200 analyzing the position of the alignment index and moving the optical system (auto-alignment function).

[0134] When performing focus adjustment, the reflecting surface of a reflecting rod 67 is obliquely disposed on the optical path of the illumination optical system 10. Light (focusing light) output from an LED 61 of the focusing optical system 60 passes through a relay lens 62, is split into two beams by a split indicator plate 63, passes through a two-hole diaphragm 64, and is reflected by a mirror 65. The light reflected by the mirror 65 is once imaged on the reflecting surface of the reflecting rod 67 by a condenser lens 66 and is then reflected. The focusing light further passes through a relay lens 20, is reflected by an apertured mirror 21, passes through a dichroic mirror 48, is refracted by an objective lens 22, and is projected onto the fundus Ef.

[0135] The fundus reflection light of the focusing light travels the same path as the cornea reflection light of the alignment light and is detected by the CCD image sensor 35. The light image (split index) received by the CCD image sensor 35 is displayed on the display device 3 together with the observation image. As in the conventional method, the arithmetic and control unit 200 analyzes the position of the split index and moves the focusing lens 31 and the focus optical system 60 to adjust the focus (autofocus function). Alternatively, the focus may be adjusted manually while visually checking the split index.

[0136] The dichroic mirror 48 branches the optical path for OCT measurement from the optical path for fundus imaging. The dichroic mirror 48 reflects light in the wavelength band used for OCT measurement and transmits light for fundus imaging. The optical path for OCT measurement is provided with, in order from the OCT unit 100 side, a collimating lens unit 40, an electro-optic modulation element (EOM) 80, a retroreflector 41, an optical scanner 42, a collimating lens 43, a mirror 44, an OCT focusing lens 45, and a field lens (relay lens) 46.

[0137] The EOM 80 is disposed between the collimating lens unit 40 and the retroreflector 41. The EOM 80 changes the refractive index in response to a control signal (voltage) 200 supplied from an arithmetic and control unit (described later). By changing the refractive index, the optical path length of the measurement light LS passing through the EOM 80 is changed. The EOM 80 is configured to change the refractive index uniformly over the cross section of the beam of the measurement light LS passing through it.

[0138] The retroreflector 41 reflects the incident measurement light LS in a direction parallel to and opposite to the incident direction of the measurement light LS. The retroreflector 41 is configured to be movable in the direction of the arrow shown in Figure 11, and changes the optical path length of the optical path for OCT measurement. This change in the optical path length is used to correct the optical path length according to the axial length of the subject's eye E, adjust the interference state, etc.

[0139] When photographing the fundus, the optical scanner 42 is placed at a position optically conjugate with the pupil of the subject's eye (pupil conjugate position) or in the vicinity thereof. When photographing the anterior segment, the optical scanner 42 is placed at a position optically non-conjugate with the pupil of the subject's eye. The optical scanner 42 changes the traveling direction of light (measurement light) passing through the optical path for OCT measurement. The optical scanner 42 is controlled by the arithmetic and control unit 200 (described later) and can deflect the measurement light one-dimensionally or two-dimensionally.

[0140] The optical scanner 42 includes, for example, a first galvanometer mirror, a second galvanometer mirror, and a mechanism for independently driving them. The first galvanometer mirror deflects the measurement light LS so as to scan the imaging site (fundus oculi Ef or anterior segment) in a vertical direction (y direction) perpendicular to the optical axis of the interference optical system included in the OCT unit 100. The y direction is the vertical direction in a plane perpendicular to the optical axis of the interference optical system. The second galvanometer mirror deflects the measurement light LS deflected by the first galvanometer mirror so as to scan the imaging site in a horizontal direction (x direction) perpendicular to the optical axis of the interference optical system. The x direction is the horizontal direction in a plane perpendicular to the optical axis of the interference optical system. This allows the imaging site to be scanned with the measurement light LS in any direction on the xy plane.

[0141] For example, it is possible to move the irradiation position of the measurement light along any trajectory on the xy plane by simultaneously controlling the orientations of the first galvanometer mirror and the second galvanometer mirror included in the optical scanner 42. This makes it possible to scan the imaging region according to a desired scan pattern.

[0142] The OCT focusing lens 45 is movable along the optical path (optical axis of the interference optical system) of the measurement light LS. The OCT focusing lens 45 is controlled by an arithmetic and control unit 200 (described later) and moves along the optical path of the measurement light LS.

[0143] In some embodiments, a liquid crystal lens or an Alvarez lens is provided instead of the OCT focusing lens 45. The liquid crystal lens or the Alvarez lens is controlled by the arithmetic and control unit 200, similar to the OCT focusing lens 45.

[0144] [OCT Unit 100] An example of the configuration of the OCT unit 100 will be described with reference to FIG. 12. The OCT unit 100 is provided with an optical system for acquiring an OCT image of the fundus Ef. This optical system has the same configuration as a conventional swept-source type OCT device. That is, this optical system is an interference optical system that splits light from a wavelength scanning (wavelength swept) light source into measurement light and reference light, causes the measurement light that has passed through the fundus Ef to interfere with the reference light that has passed through a reference light path to generate interference light, and detects this interference light. The detection result (detection signal) of the interference light in the interference optical system is a signal indicating the spectrum of the interference light, and is sent to the arithmetic and control unit 200.

[0145] The light source unit 101 includes a wavelength scanning (wavelength sweeping) light source that can scan (sweep) the wavelength of emitted light, similar to a general swept-source type OCT device. The light source unit 101 changes the output wavelength over time in the near-infrared wavelength band that is invisible to the human eye.

[0146] Light L0 output from the light source unit 101 is guided by an optical fiber 102 to a polarization controller 103, where its polarization state is adjusted. The polarization controller 103 adjusts the polarization state of the light L0 guided through the optical fiber 102, for example, by applying stress from the outside to the looped optical fiber 102.

[0147] The light L0, whose polarization state has been adjusted by the polarization controller 103, is guided by an optical fiber 104 to a fiber coupler 105, where it is split into a measurement light LS and a reference light LR.

[0148] The reference light LR is guided by an optical fiber 110 to a collimator 111 and converted into a parallel beam. The parallel beam of reference light LR passes through an optical path length correction member 112 and a dispersion compensation member 113 and is guided to a corner cube 114. The optical path length correction member 112 acts as a delay means for matching the optical path lengths (optical distances) of the reference light LR and the measurement light LS. The dispersion compensation member 113 acts as a dispersion compensation means for matching the dispersion characteristics of the reference light LR and the measurement light LS.

[0149] The corner cube 114 reverses the traveling direction of the reference light LR, which has been converted into a parallel beam by the collimator 111. The optical path of the reference light LR incident on the corner cube 114 is parallel to the optical path of the reference light LR emerging from the corner cube 114. The corner cube 114 is movable in directions along the incident and emerging optical paths of the reference light LR. This movement changes the length of the optical path (reference optical path) of the reference light LR.

[0150] The reference light LR that has passed through the corner cube 114 passes through a dispersion compensation member 113 and an optical path length correction member 112, is converted from a parallel beam into a convergent beam by a collimator 116, and enters an optical fiber 117. The reference light LR that has entered the optical fiber 117 is guided to a polarization controller 118, where the polarization state of the reference light LR is adjusted.

[0151] The polarization controller 118 has, for example, the same configuration as the polarization controller 103. The reference light LR whose polarization state has been adjusted by the polarization controller 118 is guided to an attenuator 120 by an optical fiber 119, and the light intensity is adjusted under the control of the arithmetic and control unit 200. The reference light LR whose light intensity has been adjusted by the attenuator 120 is guided to a fiber coupler 122 by an optical fiber 121.

[0152] The measurement light LS generated by the fiber coupler 105 is guided by the optical fiber 127 and collimated by the collimating lens unit 40. The collimated measurement light LS passes through the EOM 80, retroreflector 41, optical scanner 42, collimating lens 43, mirror 44, OCT focusing lens 45, and field lens 46 to reach the dichroic mirror 48. The measurement light LS is then reflected by the dichroic mirror 48, refracted by the objective lens 22, and irradiated onto the fundus Ef. The measurement light LS is scattered (including reflected) at various depth positions in the fundus Ef. The backscattered light of the measurement light LS by the fundus Ef travels in the opposite direction along the same path as the outward path and is guided to the fiber coupler 105, and reaches the fiber coupler 122 via the optical fiber 128.

[0153] Fiber coupler 122 generates interference light by combining (causing interference between) measurement light LS incident via optical fiber 128 and reference light LR incident via optical fiber 121. Fiber coupler 122 splits the interference light between measurement light LS and reference light LR at a predetermined splitting ratio (for example, 1:1) to generate a pair of interference light LC. The pair of interference light LC emitted from fiber coupler 122 is guided to detector 125 by optical fibers 123 and 124, respectively.

[0154] The detector 125 is, for example, a balanced photodiode that has a pair of photodetectors that respectively detect a pair of interference light beams LC and outputs the difference between the detection results. The detector 125 sends the detection result (interference signal) to a DAQ (Data Acquisition System) 130. A clock KC is supplied to the DAQ 130 from the light source unit 101. The clock KC is generated in synchronization with the output timing of each wavelength swept (scanned) within a predetermined wavelength range by the wavelength swept light source in the light source unit 101. For example, the light source unit 101 optically delays one of two branched beams obtained by branching light beam L0 of each output wavelength, and then generates the clock KC based on the result of detecting the combined light. The DAQ 130 samples the detection result of the detector 125 based on the clock KC. The DAQ 130 sends the sampled detection result of the detector 125 to the arithmetic and control unit 200.

[0155] Although a Michelson interferometer is used in the embodiment, any type of interferometer, such as a Mach-Zehnder interferometer, may be appropriately used. In the embodiment, the interference optical system may include the collimating lens unit 40, EOM 80, retroreflector 41, optical scanner 42, collimating lens 43, mirror 44, OCT focusing lens 45, and field lens 46 shown in FIG. 11 in addition to the configuration shown in FIG. 12 .

[0156] [Arithmetic and control unit 200] The configuration of the arithmetic and control unit 200 will be described.

[0157] 13, 15, and 16 show functional block diagrams of an example configuration of a processing system of the ophthalmologic apparatus 1 according to the embodiment. FIG. 15 shows a functional block diagram of an example configuration of the image forming unit 220 in FIG. 13. FIG. 16 shows a functional block diagram of an example configuration of the data processing unit 230 in FIG. 13. In each of FIGS. 13, 15, and 16, parts that are the same as those in FIG. 11 or 12 are given the same reference numerals, and descriptions thereof will be omitted as appropriate. FIG. 14 shows an example of control timing for the EOM 80 according to the embodiment.

[0158] The arithmetic and control unit 200 forms an OCT image of the fundus oculi Ef by analyzing the detection signal input from the detector 125. The arithmetic and control process for this purpose is the same as that of a conventional swept source type OCT device.

[0159] 13, the arithmetic and control unit 200 includes a control unit 210, and controls the fundus camera unit 2, a user interface 240 having the function of a display device 3, and each part of the OCT unit 100. For example, the arithmetic and control unit 200 forms an OCT image (tomographic image, three-dimensional image) of the fundus oculi Ef, and causes the formed OCT image to be displayed on the display device 3.

[0160] The control of the fundus camera unit 2 includes operation control of the observation light source 11, the imaging light source 15 and the LEDs 51 and 61, operation control of the CCD image sensors 35 and 38, operation control of the LCD 39, movement control of the focusing lens 31, movement control of the OCT focusing lens 45, movement control of the reflecting rod 67, movement control of the focus optical system 60, movement control of the retroreflector 41, operation control of the optical scanner 42, and drive control of the EOM 80.

[0161] The control of the OCT unit 100 includes operation control of the light source unit 101, movement control of the corner cube 114, operation control of the detector 125, operation control of the DAQ 130, operation control of the attenuator 120, operation control of the polarization controllers 103 and 118, and the like.

[0162] The arithmetic and control unit 200 controls the optical system, as well as performs image formation processing and various data processing.

[0163] The arithmetic and control unit 200 includes, for example, a processor, a random access memory (RAM), a read only memory (ROM), a hard disk drive, a communication interface, and the like, similar to a conventional computer. A computer program for controlling the ophthalmologic apparatus 1 is stored in a storage device such as a hard disk drive. The arithmetic and control unit 200 may include various circuit boards, for example, a circuit board for forming an OCT image. The arithmetic and control unit 200 may also include operation devices (input devices) such as a keyboard and a mouse, and a display device such as an LCD. In some embodiments, the functions of the arithmetic and control unit 200 are realized by one or more processors.

[0164] The fundus camera unit 2, the display device 3, the OCT unit 100 and the arithmetic and control unit 200 may be configured integrally (i.e., within a single housing) or may be configured separately in two or more housings.

[0165] The control unit 210 includes a main control unit 211 and a storage unit 212 .

[0166] (Main control unit 211) The main controller 211 performs various controls by outputting control signals to each component of the above-described ophthalmologic apparatus 1. In particular, the main controller 211 controls the CCD image sensors 35, 38, LCD 39, focusing driver 31A, retroreflector driver 41A, optical scanner 42, OCT focusing driver 45A, and EOM driver 80A for the fundus camera unit 2. Furthermore, the main controller 211 controls the light source unit 101, reference driver 114A, polarization controllers 103, 118, attenuator 120, detector 125, and DAQ 130 for the OCT unit 100.

[0167] The main control unit 211 controls the exposure time (charge accumulation time), sensitivity, frame rate, etc. of the CCD image sensor 35 or the CCD image sensor 38. In some embodiments, the main control unit 211 controls the CCD image sensor 35 or the CCD image sensor 38 so as to acquire an image of desired image quality.

[0168] The main control unit 211 controls the display of fixation targets and visual targets for visual acuity measurement on the LCD 39. This allows the visual targets presented to the subject's eye E to be switched or the type of visual target to be changed. In addition, by changing the display position of the visual target on the LCD 39, it is possible to change the visual target presentation position relative to the subject's eye E.

[0169] The focusing driver 31A moves the focusing lens 31 in the optical axis direction. The main controller 211 controls the focusing driver 31A so that the focusing lens 31 is positioned at a desired focusing position. This changes the focusing position of the photographing optical system 30.

[0170] For example, the main controller 211 analyzes the position of the split target in the received light image (split target) obtained by the CCD image sensor 35, and controls the focusing driver 31A and the focus optical system 60. Alternatively, for example, the main controller 211 controls the focusing driver 31A and the focus optical system 60 in response to an operation performed by a user on an operation unit 240B (described later) while displaying a live image of the subject's eye E on a display unit 240A (described later).

[0171] The retroreflector driver 41A moves the retroreflector 41 in the incident direction of the measurement light LS or in the direction opposite to the incident direction. The main controller 211 controls the retroreflector driver 41A to move the retroreflector 41 in the incident direction of the measurement light LS or in the direction opposite to the incident direction, thereby changing the optical path length of the measurement light LS. This changes the difference between the optical path length of the measurement light LS and the optical path length of the reference light LR.

[0172] For example, the main controller 211 analyzes the detection results of the interference light LC obtained by the OCT measurement (or an OCT image formed based on the detection results), and controls the retroreflector driver 41A so that the measurement site is at a desired depth position.

[0173] The main control unit 211 controls the optical scanner 42. The optical scanner 42 deflects the measurement light LS one-dimensionally or two-dimensionally under the control of the main control unit 211. The main control unit 211 controls the optical scanner 42 to deflect the measurement light LS according to a deflection pattern corresponding to a preset scan mode. Examples of such scan modes include line scan, cross scan, circle scan, radial scan, concentric circle scan, multi-line cross scan, spiral scan, Lissajous scan, and three-dimensional scan.

[0174] By scanning the imaging area with the measurement light LS according to the deflection pattern corresponding to the scan mode described above, an OCT image can be obtained in the plane defined by the direction along the scan line (scan trajectory) and the fundus depth direction (z direction).

[0175] The OCT focusing driver 45A moves the OCT focusing lens 45 along the optical path of the measurement light LS. The main controller 211 controls the OCT focusing driver 45A so that the OCT focusing lens 45 is positioned at a desired focusing position. This changes the focusing position of the measurement light LS. The focusing position of the measurement light LS corresponds to the depth position (z position) of the beam waist of the measurement light LS.

[0176] For example, the main control unit 211 controls the OCT focusing drive unit 45A based on the signal-to-noise ratio of the detection result of the interference light LC obtained by OCT measurement, or an evaluation value (including a statistical value of the evaluation value) corresponding to the image quality of the OCT image formed based on the detection result.

[0177] When a liquid crystal lens or an Alvarez lens is provided instead of the OCT focusing lens 45, the main control unit 211 can control the liquid crystal lens or the Alvarez lens in the same way as it controls the OCT focusing driver 45A.

[0178] The EOM driver 80A drives the EOM 80. The main controller 211 controls the EOM driver 80A to change the refractive index of the EOM 80, thereby changing the optical path length of the measurement light LS.

[0179] The main controller 211 outputs a control signal to the EOM driver 80A according to the control timing shown in FIG. 14 to change the difference between the optical path length of the reference light LR and the optical path length of the measurement light LS for each A-scan, thereby performing phase modulation. Specifically, the main controller 211 changes the optical path length of the measurement light LS so that a phase shift amount Ps is sequentially imparted at intervals of the A-scan time T, in synchronization with the start timing of the A-scan corresponding to the deflection control of the optical scanner 42. As described in Non-Patent Document 3, ghost images can be most effectively separated (removed) when the phase shift is π / 2 for each A-scan. In this embodiment, because the measurement light LS passes through the EOM 80 twice during an A-scan, the main controller 211 sequentially outputs a control signal to the EOM driver 80A so that the phase shift amount Ps is shifted by π / 4 for each A-scan. However, the phase shift amount for each A-scan does not have to be π / 2. In this case, the main controller 211 can shift the phase by 2×V for each A-scan by sequentially outputting control signals to the EOM driver 80A so that the phase shift amount Ps shifts by V for each A-scan.

[0180] Specifically, the main controller 211 controls the retroreflector driver 41A so that the measurement region is at a desired depth when an OCT scan is started. Then, during a B scan performed with the retroreflector driver 41A positioning the retroreflector 41 at a predetermined position, the main controller 211 controls the EOM driver 80A to change the optical path length of the measurement light LS for each A scan. This changes the difference between the optical path length of the reference light LR and the optical path length of the measurement light LS for each A scan, thereby acquiring phase-modulated scan data. The B scan may be not only a line scan, but also a cross scan, circle scan, radial scan, concentric circle scan, multi-line cross scan, spiral scan, or Lissajous scan, which is performed in a direction intersecting the A scan direction.

[0181] The main control unit 211 controls the light source unit 101. Control of the light source unit 101 includes switching the light source on and off, controlling the intensity of the emitted light, changing the center frequency of the emitted light, changing the sweep speed of the emitted light, changing the sweep frequency, changing the sweep wavelength range, and the like.

[0182] The reference driver 114A moves the corner cube 114 provided in the optical path of the reference light along this optical path, thereby changing the difference between the optical path length of the measurement light LS and the optical path length of the reference light LR.

[0183] For example, the main controller 211 analyzes the detection result of the interference light LC obtained by the OCT measurement (or an OCT image formed based on the detection result), and controls the reference driver 114A so that the measurement region is at a desired depth position. In some embodiments, only one of the retroreflector 41 and the reference driver 114A is provided.

[0184] The main control unit 211 controls the polarization controllers 103 and 118. For example, the main control unit 211 controls the polarization controllers 103 and 118 based on the signal-to-noise ratio of the detection result of the interference light LC obtained by OCT measurement, or an evaluation value (including a statistical value of the evaluation value) corresponding to the image quality of the OCT image formed based on the detection result.

[0185] The main controller 211 controls the attenuator 120. For example, the main controller 211 controls the attenuator 120 based on the signal-to-noise ratio of the detection result of the interference light LC obtained by OCT measurement, or an evaluation value (including a statistical value of the evaluation value) corresponding to the image quality of the OCT image formed based on the detection result.

[0186] The main control unit 211 controls the detector 125. The control of the detector 125 includes control of the exposure time (charge accumulation time), sensitivity, frame rate, and the like.

[0187] The main control unit 211 controls the DAQ 130. The control of the DAQ 130 includes control of sampling timing and the like.

[0188] The moving mechanism 150 moves the fundus camera unit 2 (OCT unit 100) three-dimensionally relative to the subject's eye E. For example, the main controller 211 can control the moving mechanism 150 to move the optical system provided in the fundus camera unit 2 three-dimensionally. This control is used for alignment and tracking. Tracking is the movement of the device optical system in accordance with the movement of the subject's eye E. When tracking is performed, alignment and focusing are performed in advance. Tracking is a function that maintains an appropriate positional relationship where alignment and focus are achieved by moving the device optical system in real time in accordance with the position and orientation of the subject's eye E based on images obtained by capturing a video of the subject's eye E.

[0189] In the case of manual alignment, the user operates a user interface 240 described below to move the optical system and the eye E relative to each other so that the displacement of the eye E relative to the optical system is canceled. For example, the main controller 211 controls the movement mechanism 150 by outputting a control signal corresponding to the operation content of the user interface 240 to the movement mechanism 150, thereby moving the optical system and the eye E relative to each other.

[0190] In the case of auto-alignment, the main controller 211 controls the moving mechanism 150 to move the optical system relative to the subject's eye E so that displacement of the subject's eye E relative to the optical system is canceled. In some embodiments, the main controller 211 controls the moving mechanism 150 to move the optical system relative to the subject's eye E by outputting a control signal to the moving mechanism 150 so that the optical axis of the optical system approximately coincides with the axis of the subject's eye E and the distance of the optical system from the subject's eye E is a predetermined working distance. Here, the working distance is a predetermined value also called the working distance of the objective lens 22, and corresponds to the distance between the subject's eye E and the optical system during measurement (photography) using the optical system.

[0191] The main controller 211 controls fundus photography and anterior segment photography by controlling the fundus camera unit 2 and the like. The main controller 211 also controls OCT measurement by controlling the fundus camera unit 2 and the OCT unit 100 and the like. The main controller 211 can perform multiple preliminary operations before performing OCT measurement. The preliminary operations include alignment, coarse focus adjustment, polarization adjustment, and fine focus adjustment. The multiple preliminary operations are performed in a predetermined order. In some embodiments, the multiple preliminary operations are performed in the above order.

[0192] In some embodiments, the main controller 211 corrects the position of the scan range (second scan range) for OCT imaging in real time based on tracking information obtained by tracking control (tracking information obtained by tracking the optical system (interference optical system) with respect to the movement of the subject's eye E). The main controller 211 can control the optical scanner 42 to scan the corrected scan range with the measurement light LS.

[0193] Furthermore, the main control unit 211 causes the display device 3 (or the display unit 240A described later) to display various information. The information displayed on the display device 3 includes the imaging results (observation image, OCT image), the measurement results (measurement values), and information indicating the results of changing the imaging conditions described later.

[0194] In addition to the display control of the display device 3 as described above, the main control unit 211 can also perform display control of images formed by the image forming unit 220 described below, and display control of data processing results obtained by the data processing unit 230 described below.

[0195] For example, a provisional imaging (provisional measurement) is performed before the actual imaging (actual measurement). The imaging conditions for the actual imaging are adjusted based on the detection result of the interference light LC acquired in the provisional imaging or the OCT image formed from the detection result.

[0196] Furthermore, the main control unit 211 performs processing to write data to the storage unit 212 and processing to read data from the storage unit 212 .

[0197] (Storage unit 212) The storage unit 212 stores various types of data. Examples of data stored in the storage unit 212 include image data of OCT images, image data of fundus images, and information about the subject's eye. The information about the subject's eye includes information about the subject, such as a patient ID and name, and information about the subject's eye, such as identification information for the left eye or right eye.

[0198] At least a part of the data stored in the storage unit 212 may be stored in a storage unit provided outside the ophthalmic apparatus 1. For example, the ophthalmic apparatus 1 is communicably connected to a server device having a function of storing at least a part of the data via a network such as an in-hospital LAN (Local Area Network). Here, the ophthalmic apparatus 1 and the server device may be connected via a WAN (Wide Area Network) such as the Internet. Alternatively, the ophthalmic apparatus 1 and the server device may be connected via a network that combines a LAN and a WAN.

[0199] (Image forming unit 220) The image forming unit 220 forms image data of a tomographic image based on the detection signal (interference signal) detected by the detector 125 and sampled by the DAQ 130. That is, the image forming unit 220 forms an OCT image of the subject's eye E based on the detection result of the interference light LC by the interference optical system. This processing includes processes such as noise removal (noise reduction), filtering, and FFT (Fast Fourier Transform), as in conventional swept-source type optical coherence tomography.

[0200] As shown in FIG. 15, the image forming unit 220 includes a rescaling processing unit 221, a first Fourier transform processing unit 222, a window function processing unit 223, an inverse Fourier transform processing unit 224, and a second Fourier transform processing unit 225.

[0201] (Rescaling processing unit 221) The rescaling processor 221 performs rescaling processing to convert B-scan data in wavelength space acquired using the OCT unit 100 into B-scan data in wavenumber space. The rescaling processing is processing to rearrange the scan data obtained by sampling the detection results of the interference light LC at equal intervals on the time axis using the clock KC so that the wavenumber changes linearly (straight line) on the time axis. The rescaling processor 221 can execute processing equivalent to processing SQ2 in FIG. 2.

[0202] (First Fourier transform processing unit 222) The first Fourier transform processing unit 222 performs Fourier transform processing in the x direction as shown in equation (2) on the B-scan data after the rescaling processing performed by the rescaling processing unit 221. The first Fourier transform processing unit 222 can execute processing equivalent to processing SQ3 in FIG.

[0203] (Window function processing unit 223) The window function processing unit 223 extracts signal components in the +u direction by performing window function processing in the u direction as described above on the B-scan data after the Fourier transform processing performed by the first Fourier transform processing unit 222. The window function processing unit 223 can execute processing equivalent to processing SQ4 in FIG.

[0204] (Inverse Fourier transform processing unit 224) The inverse Fourier transform processing unit 224 performs inverse Fourier transform processing in the u direction as shown in equation (7) on the B-scan data after the window function processing performed by the window function processing unit 223. The inverse Fourier transform processing unit 224 can execute processing equivalent to processing SQ5 in FIG.

[0205] (Second Fourier transform processing unit 225) The second Fourier transform processing unit 225 performs Fourier transform processing in the k direction on the B-scan data after the inverse Fourier transform processing performed by the inverse Fourier transform processing unit 224. The second Fourier transform processing unit 225 can execute processing equivalent to processing SQ6 in FIG.

[0206] The functions of imager 220 are performed by one or more processors, in some embodiments, the functions of imager 220 are performed by a single processor.

[0207] To improve image quality, multiple data sets (scan data) collected by repeating the same pattern multiple times can be superimposed (averaged).

[0208] The image forming unit 220 is configured to include, for example, the circuit board described above. In this specification, "image data" and an "image" based on the image data may be considered to be the same thing. Also, a portion of the fundus Ef and an image thereof may be considered to be the same thing.

[0209] (Data processing unit 230) The data processing unit 230 performs various data processing (image processing) and analysis processing on the detection result of the interference light LC or the image formed by the image forming unit 220. For example, the data processing unit 230 performs various correction processing such as analysis of the signal-to-noise ratio of the interference signal, image brightness correction, optical path length correction, optical magnification correction, and dispersion correction.

[0210] Furthermore, the data processing unit 230 performs various image processing and analysis processes on the images (fundus images, anterior eye images, etc.) obtained by the fundus camera unit 2.

[0211] The data processing unit 230 performs known image processing, such as interpolation processing that interpolates pixels between tomographic images, to form image data of a three-dimensional image of the fundus oculi Ef. Note that image data of a three-dimensional image means image data in which pixel positions are defined by a three-dimensional coordinate system. Image data of a three-dimensional image includes image data consisting of three-dimensionally arranged voxels. This image data is called volume data or voxel data, etc. When displaying an image based on the volume data, the data processing unit 230 performs rendering processing (volume rendering, MIP (Maximum Intensity Projection), etc.) on the volume data to form image data of a pseudo three-dimensional image as viewed from a specific line of sight. This pseudo three-dimensional image is displayed on a display device, such as the display unit 240A.

[0212] It is also possible to form stack data of multiple tomographic images as image data of a three-dimensional image. Stack data is image data obtained by arranging multiple tomographic images obtained along multiple scanning lines in a three-dimensional manner based on the positional relationship of the scanning lines. In other words, stack data is image data obtained by expressing multiple tomographic images that were originally defined using separate two-dimensional coordinate systems using a single three-dimensional coordinate system (i.e., embedding them in a single three-dimensional space).

[0213] The data processing unit 230 can perform various rendering operations on the acquired three-dimensional data set (volume data, stack data, etc.) to generate B-mode images (longitudinal and axial cross-sectional images) at any cross-section, C-mode images (transverse and horizontal cross-sectional images) at any cross-section, projection images, shadowgrams, and the like. Images of any cross-section, such as B-mode images and C-mode images, are generated by selecting pixels (voxels) on a specified cross-section from the three-dimensional data set. Projection images are generated by projecting the three-dimensional data set in a predetermined direction (z direction, depth direction, axial direction). Shadowgrams are generated by projecting a portion of the three-dimensional data set (e.g., partial data corresponding to a specific layer) in a predetermined direction. Images viewed from the front side of the subject's eye, such as C-mode images, projection images, and shadowgrams, are called en-face images.

[0214] The data processing unit 230 can construct a B-mode image or a front image (a vessel-enhanced image, angiogram) in which retinal blood vessels and choroidal blood vessels are emphasized based on data collected in time series by OCT (for example, B-scan image data). For example, time-series OCT data can be collected by repeatedly scanning approximately the same region of the subject's eye E.

[0215] In some embodiments, the data processor 230 compares time-series B-scan images obtained by B-scanning approximately the same region and converts pixel values ​​of portions of signal intensity change into pixel values ​​corresponding to the change to construct an enhanced image in which the changed portion is emphasized. Furthermore, the data processor 230 extracts information of a predetermined thickness of a desired region from the constructed multiple enhanced images and constructs the image as an en-face image, thereby forming an OCTA image.

[0216] Images generated by the data processing unit 230 (for example, a three-dimensional image, a B-mode image, a C-mode image, a projection image, a shadowgram, and an OCTA image) are also included in the OCT image.

[0217] 16, the data processing unit 230 includes a redundancy identifying unit 231, a resizing processing unit 232, and an analyzing unit 233. The redundancy identifying unit 231 includes a fitting processing unit 231A.

[0218] (Redundancy identification unit 231) The redundancy specifying unit 231 specifies the redundancy in the x direction based on the B-scan data acquired using the OCT unit 100. The redundancy specifying unit 231 can specify the redundancy based on the scan density in the x direction.

[0219] Specifically, the redundancy determination unit 231 determines the spatial spectrum (B(u, k)) of the cross-correlation between the measurement light LS and the reference light LR from the B-scan data after Fourier transform processing obtained by the first Fourier transform processing unit 222 (image forming unit 220), and determines the redundancy from the determined spatial spectrum.

[0220] The redundancy identification unit 231 can execute processing equivalent to processing SQ7 in Fig. 2. In this case, the redundancy identification unit 231 performs fitting processing on the determined spatial spectrum and identifies the redundancy corresponding to the scan density using the identified fitting function.

[0221] (Fitting processing unit 231A) The fitting processing unit 231A performs a known fitting process on the spatial spectrum B(u, k) obtained as described above, using a Gaussian function g(u) shown in equation (12) as a fitting function, thereby determining the parameters of the Gaussian function g(u).

[0222] The redundancy identification unit 231 obtains the scan density (Δx / d) based on the Gaussian function g(u) as a fitting function obtained by the fitting process executed by the fitting processing unit 231A. The redundancy identification unit 231 calculates (r×d / Δx) as the redundancy R using a predetermined reference scan density r, as shown in equation (15). In this embodiment, the reference scan density r=0.3.

[0223] In some embodiments, the redundancy identifying unit 231 obtains a width in the u direction at a predetermined amplitude in the Gaussian function g(u) as a fitting function obtained by the fitting process executed by the fitting processing unit 231A. The redundancy identifying unit 231 identifies a redundancy corresponding to the identified width in the u direction. For example, the redundancy identifying unit 231 stores correspondence information in which multiple redundancies are previously associated with multiple widths in the u direction at a predetermined amplitude in the Gaussian function g(u), and identifies the redundancy corresponding to the identified width in the u direction by referring to the correspondence information.

[0224] In some embodiments, the redundancy identifying unit 231 obtains a width in the u direction at a predetermined amplitude in the spatial spectrum B(u,k). The redundancy identifying unit 231 identifies a redundancy corresponding to the identified width in the u direction. For example, the redundancy identifying unit 231 stores correspondence information in which multiple redundancies are previously associated with multiple widths in the u direction at a predetermined amplitude in the spatial spectrum B(u,k), and identifies the redundancy corresponding to the identified width in the u direction by referring to the correspondence information.

[0225] The fitting function according to the above embodiment may be any function other than the Gaussian function.

[0226] (Resize processing unit 232) The resizing processing unit 232 resizes the data size of the B-scan data obtained by the image forming unit 220 in the x direction based on the redundancy specified by the redundancy specifying unit 231. Specifically, the resizing processing unit 232 resizes the data size of the B-scan data after Fourier transform processing obtained by the second Fourier transform processing unit 225 by a factor of (1 / R) in the x direction based on the redundancy R specified by the redundancy specifying unit 231.

[0227] The resizing unit 232 may determine whether to perform resizing processing according to a result of comparing the identified redundancy with a predetermined threshold, and may perform the resizing processing when it is determined that the resizing processing should be performed. For example, when the identified redundancy is greater than 1, the resizing unit 232 performs the resizing processing.

[0228] The resizing processing unit 232 can resize the B-scan data in the x direction by averaging the A-scan data at scan positions adjacent in the x direction in the number corresponding to the redundancy identified by the redundancy identification unit 231.

[0229] For example, assume that the redundancy is "3." In this case, the resizing processor 232 averages the A-scan data at three scan positions P1 to P3 among scan positions P1, P2, P3, P4, P5, and P6 that are adjacent in order in the x direction, in the x direction, and averages the A-scan data at three scan positions P4 to P6 in the x direction. If the redundancy has a decimal part, the averaging can be performed at a ratio corresponding to the decimal part, or the A-scan data can be thinned out at a ratio corresponding to the decimal part. In this case, at least one of the A-scan data at scan positions P1 to P3 is weighted according to the decimal part, and the three scan data including the weighted A-scan data are averaged.

[0230] In some embodiments, the resizing unit 232 can resize the B-scan data in the x direction by averaging the A-scan data at scan positions adjacent in the x direction by a number corresponding to the redundancy identified by the redundancy identification unit 231 using a moving average in the x direction.

[0231] For example, assume that the redundancy is "3." In this case, the resizing processing unit 232 averages, in the x direction, the A-scan data at three scan positions P1 to P3 out of scan positions P1, P2, P3, P4, P5, and P6 that are adjacent in order in the x direction, averages, in the x direction, the A-scan data at three scan positions P2 to P4, averages, in the x direction, the A-scan data at three scan positions P3 to P5, and averages, in the x direction, the A-scan data at three scan positions P4 to P6.

[0232] Furthermore, the resizing unit 232 may resize the B-scan data in the x direction by thinning out the A-scan data in accordance with the redundancy specified by the redundancy specifying unit 231.

[0233] For example, assume that the redundancy is "3." In this case, the resizing processor 232 thins out, for example, three scan positions P2, P3, P5, and P6 from among scan positions P1, P2, P3, P4, P5, and P6 that are adjacent in order in the x direction, to generate B-scan data in which A-scan data at two scan positions P1 and P4 are arranged. If the redundancy has a decimal part, it is possible to average the data at a ratio corresponding to the decimal part, or to thin out the A-scan data at a ratio corresponding to the decimal part.

[0234] For example, the resizing unit 232 may select one of the A-scan data sets corresponding to the redundancy identified by the redundancy identifying unit 231 as representative scan data, and resize the data by extracting the selected representative scan data. In some embodiments, the representative scan data set is selected based on the A-scan position, data in a predetermined depth range, or a comparison result with A-scan data sets at other A-scan positions.

[0235] (Analysis Department 233) The analysis unit 233 analyzes at least the detection result of the interference light LC, the OCT image formed by the image formation unit 220, and the OCT image (B-scan data, B-scan image) after resizing processing executed by the resizing processing unit 232. In some embodiments, the analysis unit 233 analyzes the detection result of the interference light LC or the OCT image, and outputs an evaluation value (including a statistical value of the evaluation value) corresponding to the image quality (signal-to-noise ratio) of the OCT image as the analysis result. The main control unit 211 is capable of controlling at least one of the OCT focusing driver 45A, the retroreflector 41, and the polarization controllers 103 and 118 based on the analysis result obtained by the analysis unit 233.

[0236] For example, the analysis unit 233 analyzes the detection results of the interference light obtained by OCT measurement to determine the focus state of the measurement light LS in focus fine adjustment control. For example, the main control unit 211 performs repetitive OCT measurement while controlling the OCT focusing driver 45A according to a predetermined algorithm. The analysis unit 233 calculates a predetermined evaluation value related to the image quality of the OCT image by analyzing the detection results of the interference light LC repeatedly obtained by OCT measurement. The analysis unit 233 determines whether the calculated evaluation value is equal to or less than a threshold. In some embodiments, the focus fine adjustment is continued until the calculated evaluation value is equal to or less than the threshold. In other words, when the evaluation value is equal to or less than the threshold, it is determined that the focus state of the measurement light LS is appropriate, and the focus fine adjustment is continued until it is determined that the focus state of the measurement light LS is appropriate.

[0237] In some embodiments, the main controller 211 performs the above-described repetitive OCT measurements to acquire interference signals, while monitoring the intensity (interference intensity, interference sensitivity) of the successively acquired interference signals. Furthermore, while performing this monitoring process, the main controller 211 moves the OCT focusing lens 45 to search for the position of the OCT focusing lens 45 where the interference intensity is maximized. By performing such fine focus adjustment, the OCT focusing lens 45 can be guided to a position where the interference intensity is optimized.

[0238] Furthermore, the analysis unit 233 analyzes the detection results of the interference light obtained by the OCT measurement to determine the polarization state of at least one of the measurement light LS and the reference light LR. For example, the main control unit 211 performs repetitive OCT measurement while controlling at least one of the polarization controllers 103 and 118 according to a predetermined algorithm. In some embodiments, the main control unit 211 controls the attenuator 120 to change the attenuation amount of the reference light LR. The analysis unit 233 calculates a predetermined evaluation value related to the image quality of the OCT image by analyzing the detection results of the interference light LC repeatedly acquired by the OCT measurement. The analysis unit 233 determines whether the calculated evaluation value is equal to or less than a threshold. This threshold is set in advance. The polarization adjustment is continued until the calculated evaluation value is equal to or less than the threshold. In other words, when the evaluation value is equal to or less than the threshold, it is determined that the polarization state of the measurement light LS is appropriate, and the polarization adjustment is continued until it is determined that the polarization state of the measurement light LS is appropriate.

[0239] In some embodiments, the main controller 211 can also monitor the interference intensity during polarization adjustment.

[0240] Furthermore, the analysis unit 233 performs predetermined analytical processing on the detection results of the interference light obtained by the OCT measurement or on the OCT image formed based on the detection results. The predetermined analytical processing includes identifying predetermined regions (tissues, lesions) in the subject's eye E; calculating the distance (interlayer distance), area, angle, ratio, and density between specified regions; performing calculations using specified formulas; identifying the shape of the predetermined regions; calculating statistical values ​​of these; calculating the distribution of measurement values ​​and statistical values; and image processing based on the results of these analytical processing. Predetermined tissues include blood vessels, the optic disc, the fovea, the macula, etc. Predetermined lesions include exudates, hemorrhage, etc.

[0241] In some embodiments, the analysis unit 233 serves as a segmentation processing unit and identifies multiple layer regions in the A-scan direction based on the acquired data of the subject's eye. In this case, the analysis unit 233 performs segmentation processing on the three-dimensional OCT data to identify multiple partial data sets corresponding to multiple tissues of the subject's eye. The segmentation processing is image processing for identifying specific tissues or tissue boundaries. For example, the analysis unit 233 calculates the gradient of pixel values ​​(brightness values) in each A-scan image included in the scan data and identifies positions with large gradients as tissue boundaries. Note that the A-scan image is one-dimensional image data extending in the depth direction of the fundus. Note that the depth direction of the fundus is defined as, for example, the z direction, the incident direction of the measurement light LS, the axial direction, the optical axis direction of the interference optical system, etc.

[0242] In a typical example, the analysis unit 233 analyzes three-dimensional OCT data representing the fundus (retina, choroid, etc.) and vitreous body to identify multiple partial datasets corresponding to multiple layer tissues of the fundus. Each partial dataset is defined by the boundary of the layer tissue. Examples of layer tissues identified as partial datasets include layer tissues constituting the retina. Layer tissues constituting the retina include the internal limiting membrane, nerve fiber layer, ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer, outer nuclear layer, external limiting membrane, photoreceptor layer, and RPE. The analysis unit 233 can identify partial datasets corresponding to Bruch's membrane, choroid, sclera, vitreous body, etc. In some embodiments, the analysis unit 233 identifies partial datasets corresponding to lesions. Examples of lesions include detachments, edema, hemorrhage, tumors, drusen, etc.

[0243] In some embodiments, the analysis unit 233 identifies a layer of tissue of a predetermined number of pixels on the sclera side of the RPE as Bruch's membrane, and acquires a partial data set corresponding to the layer of tissue as a partial data set of Bruch's membrane.

[0244] The data processing unit 230 can align the fundus image and OCT image acquired using the imaging optical system 30. When the fundus image and OCT image are acquired in parallel, the two optical systems are coaxial, so the simultaneously (or substantially simultaneously) acquired fundus image and OCT image can be aligned with each other using the optical axis of the imaging optical system 30 as a reference. Regardless of the timing of acquisition of the fundus image and the OCT image, it is also possible to align the OCT image and the fundus image by aligning the image obtained by projecting the OCT image onto the xy plane with the fundus image. This alignment method can also be applied when the optical system for acquiring the fundus image and the optical system for OCT measurement are not coaxial. Even when the optical systems are not coaxial, if the relative positional relationship between the two optical systems is known, alignment similar to the case of coaxial alignment can be performed by referring to this relative positional relationship.

[0245] The data processing unit 230 that functions as described above is configured to include, for example, one or more processors, RAM, ROM, a hard disk drive, a circuit board, etc. A computer program that causes the microprocessor to execute the above functions is stored in advance in a storage device such as a hard disk drive.

[0246] (User Interface 240) The user interface 240 includes a display unit 240A and an operation unit 240B. The display unit 240A includes the display device of the arithmetic and control unit 200 and the display device 3 described above. The operation unit 240B includes the operation device of the arithmetic and control unit 200 described above. The operation unit 240B may include various buttons and keys provided on the housing of the ophthalmologic apparatus 1 or on the outside. For example, if the fundus camera unit 2 has a housing similar to that of a conventional fundus camera, the operation unit 240B may include a joystick, an operation panel, etc. provided on this housing. Furthermore, the display unit 240A may include various display devices such as a touch panel provided on the housing of the fundus camera unit 2.

[0247] It should be noted that the display unit 240A and the operation unit 240B do not need to be configured as separate devices. For example, it is possible to use a device in which the display function and the operation function are integrated, such as a touch panel. In this case, the operation unit 240B is configured to include this touch panel and a computer program. The operation content on the operation unit 240B is input to the control unit 210 as an electrical signal. Furthermore, operations and information input may be performed using a graphical user interface (GUI) displayed on the display unit 240A and the operation unit 240B.

[0248] The information processing unit 600 or the arithmetic and control unit 200 (the control unit 210, the image forming unit 220, and the data processing unit 230) is an example of an "information processing device" according to an embodiment. The OCT device 500, or the OCT unit 100 and the optical scanner 42 is an example of an "OCT device" according to an embodiment. The x direction (t direction) or the B-scan direction is an example of a "lateral direction" according to an embodiment. The redundancy identifying unit 231 is an example of an "identifying unit" according to an embodiment. The control unit 210 and the main control unit 211 are an example of a "display control unit" according to an embodiment. The interference optical system 510, or the optical system through which the measurement light LS passes from the OCT unit 100 to the objective lens 22, is an example of an "interference optical system" according to an embodiment. The scan data generating unit 530 or the image forming unit 220 is an example of a "scan data generating unit" according to an embodiment. The object 700 or the eye E is an example of a "object" according to an embodiment. The display device 3 or the display unit 240A is an example of a "display means" according to an embodiment.

[0249] [Example of operation] An example of the operation of the ophthalmologic apparatus 1 according to the embodiment will be described.

[0250] 17, 18, and 19 show flow diagrams of an example of operation of the ophthalmologic apparatus 1 according to the embodiment. FIG. 17 shows a flowchart of an example of operation of the ophthalmologic apparatus 1 according to the embodiment. FIG. 18 shows a flowchart of an example of operation of step S7 in FIG. 17. FIG. 19 shows a flowchart of an example of operation of step S8 in FIG. 17. The storage unit 212 stores a computer program for realizing the processes shown in FIGS. 17, 18, and 19. The main control unit 211 operates in accordance with this computer program to execute the processes shown in FIGS. 17, 18, and 19.

[0251] (S1: Alignment) First, in a state where a fixation target is presented at a predetermined fixation position, the main controller 211 performs alignment adjustment of the optical system with respect to the subject's eye E. As an example of the alignment adjustment, there are a case where it is performed manually and a case where it is performed automatically.

[0252] When performing alignment adjustment manually, the main controller 211 projects a pair of alignment indicators onto the subject's eye E using the alignment optical system 50. The display unit 240A displays a pair of alignment bright spots as received light images of these alignment indicators. The main controller 211 also causes the display unit 240A to display an alignment scale indicating positions to which the pair of alignment bright spots should be moved. The alignment scale is, for example, a parenthetical image.

[0253] When the positional relationship between the subject's eye E and the fundus camera unit 2 (objective lens 22) is appropriate, a pair of alignment bright spots are first imaged at a predetermined position (for example, a position midway between the corneal apex and the center of corneal curvature) and then projected onto the subject's eye E by a known method. Here, the above-mentioned positional relationship being appropriate means that the distance (working distance) between the subject's eye E and the fundus camera unit 2 is appropriate, and that the optical axis of the optical system of the fundus camera unit 2 and the axis of the subject's eye E (corneal apex position) coincide (or nearly coincide). The examiner (user) can adjust the alignment of the optical system with respect to the subject's eye E by moving the fundus camera unit 2 three-dimensionally so as to guide the pair of alignment bright spots into the alignment scale.

[0254] When performing automatic alignment adjustment, a movement mechanism 150 is used to move the fundus camera unit 2. The data processing unit 230 identifies the position of each alignment bright spot on the screen displayed on the display unit 240A and calculates the displacement between the identified position of each alignment bright spot and the alignment scale. The main control unit 211 moves the fundus camera unit 2 using the movement mechanism 150 to cancel this displacement. The position of each alignment bright spot can be identified, for example, by calculating the luminance distribution of each alignment bright spot and then calculating the center of gravity position based on this luminance distribution. Since the position of the alignment scale is constant, the desired displacement can be obtained, for example, by calculating the displacement between its center position and the center of gravity position. The movement direction and movement distance of the fundus camera unit 2 can be determined by referring to the unit movement distances in the x, y, and z directions that are preset. The unit movement distance is determined, for example, from the results of prior measurement of how far the alignment indicator moves in each direction when the fundus camera unit 2 is moved in each direction. The main control unit 211 generates a signal according to the determined movement direction and movement distance, and transmits this signal to the movement mechanism 150. As a result, the position of the optical system with respect to the eye E is automatically adjusted.

[0255] (S2: Set scan conditions) Next, the main control unit 211 sets the scan conditions, which include the scan mode, scan position, and scan range (scan start position and scan end position).

[0256] For example, the main controller 211 sets a scan mode designated by the user using the operation unit 240 B. The main controller 211 may set the scan mode based on the imaging mode designated by the user using the operation unit 240 B and corresponding to the imaging region.

[0257] Furthermore, for example, the main controller 211 sets a scan position and a scan range specified by the user on a fundus image of the fundus oculi Ef using the operation unit 240B. Examples of fundus images include a photographed image acquired using the photographing optical system 30 and a live OCT image (projection image, en-face image) obtained by OCT measurement. The main controller 211 may set a scan range to an imaging region associated in advance with an imaging mode based on an imaging mode corresponding to an imaging region specified by the user using the operation unit 240B.

[0258] (S3: Adjust depth position) Next, the main controller 211 adjusts the depth position at which the image region corresponding to the site of interest in the subject's eye E is rendered so that the image region corresponding to the site of interest falls within a predetermined depth range in the tomographic image.

[0259] For example, the main controller 211 displays a fixation target for OCT measurement at a predetermined position on the LCD 39. The main controller 211 can display the fixation target at a display position on the LCD 39 that corresponds to the position of the optical axis of the optical system on the fundus Ef.

[0260] Next, the main controller 211 controls the OCT unit 100 to perform provisional OCT measurement and acquire an adjustment tomographic image for adjusting the reference position of the measurement range in the depth direction. Specifically, the main controller 211 controls the optical scanner 42 to deflect the measurement light LS generated based on the light L0 emitted from the light source unit 101 and scan the fundus Ef of the subject's eye E with the deflected measurement light LS. The detection result of the interference light obtained by scanning with the measurement light LS is sampled in synchronization with a clock KC and then sent to the image forming unit 220. The image forming unit 220 forms a tomographic image (OCT image) of the subject's eye E from the obtained interference signal.

[0261] Next, for example, the main controller 211 causes the analyzer 233 to identify a predetermined region (e.g., the sclera) in the obtained tomographic image, and sets a position a predetermined distance in the depth direction from the position of the identified predetermined region as the reference position of the measurement range. The main controller 211 controls at least one of the retroreflector 41 and the reference driver 114A in accordance with the reference position. Alternatively, a predetermined position may be set as the reference position of the measurement range so that the optical path lengths of the measurement light LS and the reference light LR are approximately the same.

[0262] (S4: Focus adjustment) Next, the main control unit 211 executes focus adjustment control.

[0263] For example, the main controller 211 controls the OCT focusing driver 45A to move the OCT focusing lens 45 by a predetermined distance, and then controls the OCT unit 100 to perform OCT measurement. As described above, the main controller 211 causes the data processor 230 to determine the focus state of the measurement light LS based on the detection result of the interference light obtained by the OCT measurement. When it is determined that the focus state of the measurement light LS is not appropriate based on the determination result by the data processor 230, the main controller 211 controls the OCT focusing driver 45A again, and repeats this process until it is determined that the focus state is appropriate.

[0264] (S5: Polarization adjustment) Next, the main control unit 211 performs polarization adjustment.

[0265] For example, the main control unit 211 controls at least one of the polarization controllers 103, 118 to change the polarization state of at least one of the light L0 and the measurement light LS by a predetermined amount, and then controls the OCT unit 100 to perform OCT measurement and causes the image forming unit 220 to form an OCT image based on the detection result of the acquired interference light. As described above, the main control unit 211 causes the data processing unit 230 to determine the image quality of the OCT image obtained by the OCT measurement. When it is determined based on the determination result by the data processing unit 230 that the polarization state of the measurement light LS is not appropriate, the main control unit 211 controls the polarization controllers 103, 118 again, and repeats this process until it is determined that the polarization state is appropriate.

[0266] (S6: OCT scan) Next, the main controller 211 controls the optical scanner 42, the OCT unit 100, etc. to perform an OCT scan under the measurement environment adjusted in steps S1 to S5.

[0267] At this time, the main controller 211 executes a BM scan by controlling the EOM driver 80A to change (phase modulate) the difference between the optical path length of the reference light and the optical path length of the measurement light for each A-scan in synchronization with the deflection control of the optical scanner 42 corresponding to the scan mode set in step S2, as described above. This shifts the phase for each A-scan, thereby acquiring B-scan data that is frequency modulated (phase modulated) in the lateral direction.

[0268] (S7: Forming an OCT image) Next, the main control unit 211 controls each unit of the image forming unit 220 shown in FIG. 15 to generate an OCT image (B-scan data) as described above.

[0269] (S8: resize processing) Next, the main controller 211 controls the redundancy specifying unit 231 of the data processor 230 shown in Fig. 16 to specify the redundancy in the x direction based on the B-scan data obtained by the OCT scan. Furthermore, the main controller 211 controls the resizing processor 232 of the data processor 230 shown in Fig. 16 to resize the data size of the B-scan data generated in step S7 in the x direction based on the specified redundancy.

[0270] (S9:Display) Next, the main controller 211, as a display controller, causes the display unit 240A to display a tomographic image of the subject's eye E based on the B-scan data after the resizing process obtained in step S8.

[0271] This is the end of the operation of the ophthalmologic apparatus 1 (END).

[0272] In step S7 in FIG. 17, for example, the process shown in FIG. 18 is executed.

[0273] (S31: Rescaling process) First, the main control unit 211 controls the rescaling processing unit 221 to execute a rescaling process for converting the B-scan data in the wavelength space acquired in step S6 of FIG. 17 into B-scan data in the wavenumber space.

[0274] (S32: Fourier transform in the x direction) Next, the main control unit 211 controls the first Fourier transform processing unit 222 to perform Fourier transform processing in the x direction as shown in equation (2) on the B-scan data after the rescaling processing executed in step S31.

[0275] (S33: Window function processing) Next, the main control unit 211 controls the window function processing unit 223 to perform window function processing in the u direction as described above on the B-scan data after the Fourier transform processing executed in step S32, thereby extracting signal components in the +u direction.

[0276] (S34: Inverse Fourier transform in the u direction) Next, the main control unit 211 controls the inverse Fourier transform processing unit 224 to perform inverse Fourier transform processing in the u direction as shown in equation (7) on the B-scan data after the window function processing executed in step S33.

[0277] (S35: Fourier transform in k direction) Next, the main control unit 211 controls the second Fourier transform processing unit 225 to perform Fourier transform processing in the k direction on the B-scan data after the inverse Fourier transform processing executed in step S34.

[0278] This is the end of the process in step S7 of FIG. 17 (END).

[0279] In step S8 in FIG. 17, for example, the process shown in FIG. 19 is executed.

[0280] (S41: Fitting process) First, the main control unit 211 controls the redundancy identification unit 231 to execute fitting processing on the B-scan data acquired in step S7 of FIG.

[0281] As described above, the fitting processing unit 231A of the redundancy identification unit 231 performs fitting processing on the spatial spectrum (B(u, k)) of the cross-correlation between the measurement light LS and the reference light LR obtained from the B-scan data after the Fourier transform processing obtained in step S35 of Fig. 18. For example, the fitting processing unit 231A identifies a fitted Gaussian function g(u) as the fitting function.

[0282] (S42: Calculate redundancy) Next, the main control unit 211 controls the redundancy identification unit 231 to calculate the redundancy in the x direction based on the fitting function (Gaussian function g(u)) identified by the fitting process executed in step S41.

[0283] (S43: Resize in x direction) Next, the main control unit 211 controls the resizing processing unit 232 to resize the data size of the B-scan data obtained in step S35 of FIG. 18 in the x direction based on the redundancy calculated in step S42.

[0284] For example, the resizing processing unit 232 resizes the data size of the B-scan data after Fourier transform processing obtained in step S35 of Fig. 18 by a factor of (1 / R) in the x direction based on the redundancy R calculated in step S42 as described above. The resizing processing unit 232 resizes the data size of the B-scan data in the x direction by averaging adjacent A-scan data in the x direction or thinning out the A-scan data based on the redundancy R as described above.

[0285] This is the end of the process in step S8 in FIG. 17 (END).

[0286] As described above, according to the embodiment, the spatial spectrum of the cross-correlation between the measurement light LS and the reference light LR is obtained from B-scan data that has been frequency-modulated in the lateral direction by shifting the phase for each A-scan using OCT, the redundancy is identified from the obtained spatial spectrum, and the B-scan data (B-scan image) is resized in the lateral direction based on the identified redundancy. This allows the data size (image size) to be resized without reducing the amount of information contained in the original B-scan data, so as not to affect the observation. In other words, it is possible to optimize the scan data to reduce redundancy without reducing the amount of information, thereby achieving observation over a long range in the depth direction using full-range OCT, while also achieving secondary effects such as shortening processing time and saving resources.

[0287] <Modification> The configuration according to the embodiment is not limited to the configuration described in the above embodiment. Various modifications of the embodiment will be described below, focusing on the differences from the embodiment.

[0288] (First Modification) In the configuration shown in FIG. 11, the EOM 80 is disposed in the optical path of the measurement light LS between the collimator lens unit 40 and the retroreflector 41, but the configuration according to the embodiment is not limited to this.

[0289] An example of the configuration of an optical system of an ophthalmologic apparatus 1a according to a first modified example of the embodiment is shown in Fig. 20. In Fig. 20, the same parts as those in Fig. 11 are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0290] The configuration of the optical system of the ophthalmic apparatus 1a according to the first modification differs from the configuration of the optical system of the ophthalmic apparatus 1 shown in FIG. 11 in the arrangement of the EOM 80. In FIG. 11, the EOM 80 is arranged in the optical path between the collimating lens unit 40 and the retroreflector 41. In contrast, in FIG. 20, the EOM 80 is arranged in the optical path between the collimating lens unit 40 and the retroreflector 41 and in the optical path between the retroreflector 41 and the optical scanner 42. The EOM 80 may be arranged in the optical path between the collimating lens unit 40 and the optical scanner 42. Alternatively, the EOM 80 may be arranged in the optical path between the optical scanner 42 and the collimating lens 43.

[0291] In the first modified example, as in the embodiment, the main controller 211 outputs a control signal to the EOM driver 80A according to the control timing shown in FIG. 14 to change the difference between the optical path length of the reference light LR and the optical path length of the measurement light LS for each A-scan, thereby performing phase modulation. In this case, the main controller 211 changes the optical path length of the measurement light LS so that a phase shift amount Ps is sequentially imparted at intervals of the A-scan time T, in synchronization with the start timing of the A-scan corresponding to the deflection control of the optical scanner 42. However, in the first modified example, the measurement light LS passes through the EOM 80 four times during an A-scan. Therefore, in order to shift the phase by π / 2 for each A-scan so as to most effectively separate (remove) ghost images, the main controller 211 sequentially outputs a control signal to the EOM driver 80A so that the phase shift amount Ps shifts by π / 8 for each A-scan.

[0292] As in the embodiment, in the first modified example, the phase shift amount for each A-scan does not have to be π / 2. In this case, the main controller 211 can shift the phase by 4×V for each A-scan by sequentially outputting control signals to the EOM driver 80A so that the phase shift amount Ps shifts by V for each A-scan.

[0293] Except for the above, the configuration and operation of the ophthalmic apparatus 1a according to the first modified example are similar to the configuration and operation of the ophthalmic apparatus 1 according to the embodiment.

[0294] According to the first modification, the same effect as in the embodiment can be obtained by using the EOM 80 with a small change in refractive index.

[0295] (Second Modification) In the embodiment or the first modification, a case where phase modulation is performed using the EOM 80 has been described, but the configuration according to the embodiment is not limited to this.

[0296] An example of the configuration of an optical system of an ophthalmologic apparatus 1b according to a second modified example of the embodiment is shown in Fig. 21. In Fig. 21, the same parts as those in Fig. 11 are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0297] The configuration of the optical system of the ophthalmic apparatus 1b according to the second modified example differs from the configuration of the optical system of the ophthalmic apparatus 1 shown in Fig. 11 in that a piezoelectric element 81 attached to the retroreflector 41 is provided instead of the EOM 80. The piezoelectric element 81 receives a control signal from the control unit 210 (main control unit 211) and moves the retroreflector 41 in the direction of the arrow shown in Fig. 21. Note that the function of the piezoelectric element 81 may be realized by the retroreflector driving unit 41A.

[0298] Fig. 22 is a block diagram showing an example of the configuration of a processing system of an ophthalmologic apparatus 1b according to a second modified example of the embodiment. In Fig. 22, the same parts as in Fig. 13 are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0299] The configuration of the processing system of the ophthalmic apparatus 1b according to the second modification differs from the configuration of the processing system of the ophthalmic apparatus 1 shown in FIG. 13 in that an arithmetic control unit 200b is provided instead of the arithmetic control unit 200 and a piezoelectric element driver 81A is provided instead of the EOM driver 80A. The main controller 211 in the arithmetic control unit 200b outputs a control signal to the piezoelectric element driver 81A according to the control timing shown in FIG. 14 to change the difference between the optical path length of the reference light LR and the optical path length of the measurement light LS for each A-scan, thereby performing phase modulation. In this case, the main controller 211 changes the optical path length of the measurement light LS so that a phase shift amount Ps is sequentially imparted at intervals of the A-scan time T in synchronization with the start timing of the A-scan corresponding to the deflection control of the optical scanner 42. In the second modification, the optical path length changes by twice the movement amount of the retroreflector 41, and the measurement light LS passes through the retroreflector 41 twice during an A-scan. Therefore, in order to shift the phase by π / 2 for each A-scan so as to separate (remove) ghost images most effectively, the main control unit 211 sequentially outputs control signals to the piezoelectric element driving unit 81A so that the phase shift amount Ps shifts by π / 8 for each A-scan.

[0300] As in the embodiment, in the second modified example, the phase shift amount for each A-scan does not have to be π / 2. In this case, the main controller 211 can shift the phase by 2×V for each A-scan by sequentially outputting control signals to the EOM driver 80A so that the phase shift amount Ps shifts by V for each A-scan.

[0301] Except for the above, the configuration and operation of the ophthalmologic apparatus 1b according to the second modified example are similar to the configuration and operation of the ophthalmologic apparatus 1 according to the embodiment.

[0302] According to the second modification, the same effect as that of the embodiment can be obtained without providing the EOM 80.

[0303] (Third Modification) In the embodiment, the first variant, and the second variant, the case where phase modulation is performed by changing the optical path length of the measurement light LS has been described, but the configuration of the embodiment is not limited to this.

[0304] Fig. 23 shows an example of the configuration of the optical system of an OCT unit 100c of an ophthalmic apparatus according to a third modified example of the embodiment. In Fig. 23, the same parts as in Fig. 12 are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0305] The optical system configuration of the OCT unit 100c according to the third modified example differs from the optical system configuration of the OCT unit 100 shown in FIG. 12 in that an EOM 80 is disposed in the optical path of the reference light LR that is incident on the corner cube 114 between the dispersion compensation member 113 and the corner cube 114.

[0306] In the third modified example, as in the embodiment, the main controller 211 outputs a control signal to the EOM driver 80A according to the control timing shown in FIG. 14 to change the difference between the optical path length of the reference light LR and the optical path length of the measurement light LS for each A-scan, thereby performing phase modulation. In this case, the main controller 211 changes the optical path length of the reference light LR so that a phase shift amount Ps is sequentially imparted at intervals of the A-scan time T, in synchronization with the start timing of the A-scan corresponding to the deflection control of the optical scanner 42. In the third modified example, the reference light LR passes through the EOM 80 once during an A-scan. Therefore, in order to shift the phase by π / 2 for each A-scan so as to most effectively separate (remove) ghost images, the main controller 211 sequentially outputs a control signal to the EOM driver 80A so that the phase shift amount Ps shifts by π / 2 for each A-scan.

[0307] As in the embodiment, in the third modified example, the phase shift amount for each A-scan does not have to be π / 2. In this case, the main controller 211 can shift the phase by V for each A-scan by sequentially outputting control signals to the EOM driver 80A so that the phase shift amount Ps shifts by V for each A-scan.

[0308] Except for the above, the configuration and operation of the ophthalmologic apparatus according to the third modified example are similar to the configuration and operation of the ophthalmologic apparatus 1 according to the embodiment.

[0309] According to the third modified example, the same effect as that of the embodiment can be obtained without changing the optical path length of the measurement light LS.

[0310] (Fourth Modification) In the third modified example, the EOM 80 is disposed in the optical path of the reference light LR that is incident on the corner cube 114, but the configuration according to the embodiment is not limited to this.

[0311] Fig. 24 shows an example of the configuration of the optical system of an OCT unit 100d of an ophthalmic apparatus according to a fourth modified example of the embodiment. In Fig. 24, the same parts as in Fig. 23 are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0312] The configuration of the optical system of the OCT unit 100d according to the fourth modified example differs from the configuration of the optical system of the OCT unit 100c shown in Fig. 23 in the arrangement of the EOM 80. In Fig. 23, the EOM 80 is arranged in the optical path of the reference light LR that enters the corner cube 114. In contrast, in Fig. 24, the EOM 80 is arranged in the optical path of the reference light LR that enters the corner cube 114 and the optical path of the reference light LR that exits from the corner cube 114.

[0313] In the fourth modification, similarly to the third modification, the main controller 211 outputs a control signal to the EOM driver 80A according to the control timing shown in FIG. 14 to change the difference between the optical path length of the reference light LR and the optical path length of the measurement light LS for each A-scan, thereby performing phase modulation. In this case, the main controller 211 changes the optical path length of the reference light LR so that a phase shift amount Ps is sequentially imparted at intervals of the A-scan time T, in synchronization with the start timing of the A-scan corresponding to the deflection control of the optical scanner 42. However, in the fourth modification, the reference light LR passes through the EOM 80 twice during an A-scan. Therefore, in order to shift the phase by π / 2 for each A-scan so as to most effectively separate (remove) ghost images, the main controller 211 sequentially outputs a control signal to the EOM driver 80A so that the phase shift amount Ps shifts by π / 4 for each A-scan.

[0314] As in the embodiment, in the fourth modified example, the phase shift amount for each A-scan does not have to be π / 2. In this case, the main controller 211 can shift the phase by 2×V for each A-scan by sequentially outputting control signals to the EOM driver 80A so that the phase shift amount Ps shifts by V for each A-scan.

[0315] Except for the above, the configuration and operation of the ophthalmologic apparatus according to the fourth modified example are similar to the configuration and operation of the ophthalmologic apparatus according to the third modified example.

[0316] According to the fourth modification, the same effect as in the embodiment can be obtained by using an EOM 80 with a small change in refractive index.

[0317] (Fifth Modification) In the third and fourth modified examples, the case where phase modulation is performed using the EOM 80 has been described, but the configuration according to the embodiment is not limited to this.

[0318] Fig. 25 shows an example of the configuration of the optical system of an OCT unit 100e of an ophthalmic apparatus according to a fifth modified example of the embodiment. In Fig. 25, the same parts as in Fig. 12 are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0319] The configuration of the optical system of the OCT unit 100e according to the fifth modification differs from the configuration of the optical system of the OCT unit 100 shown in Fig. 12 in that a piezoelectric element 81 attached to the corner cube 114 is provided instead of the EOM 80. The piezoelectric element 81 receives a control signal from the control unit 210 (main control unit 211) and moves the corner cube 114 in the direction of the arrow shown in Fig. 25. Note that the function of the piezoelectric element 81 may be realized by the reference driver 114A.

[0320] The processing system of the ophthalmic apparatus according to the fifth modification includes a piezoelectric element driver 81A, as in FIG. 22 . The main controller 211 outputs a control signal to the piezoelectric element driver 81A according to the control timing shown in FIG. 14 to change the difference between the optical path length of the reference light LR and the optical path length of the measurement light LS for each A-scan, thereby performing phase modulation. In this case, the main controller 211 changes the optical path length of the reference light LR so that a phase shift amount Ps is sequentially imparted at intervals of the A-scan time T, in synchronization with the start timing of the A-scan corresponding to the deflection control of the optical scanner 42. In the fifth modification, the phase shift occurs by twice the movement amount of the corner cube 114 while the reference light LR passes through the corner cube 114 once during an A-scan. Therefore, in order to shift the phase by π / 2 for each A-scan so as to most effectively separate (remove) ghost images, the main controller 211 sequentially outputs a control signal to the piezoelectric element driver 81A so that the phase shift amount Ps shifts by π / 4 for each A-scan.

[0321] As in the embodiment, in the fifth modified example, the phase shift amount for each A-scan does not have to be π / 2. In this case, the main controller 211 can shift the phase by V for each A-scan by sequentially outputting control signals to the EOM driver 80A so that the phase shift amount Ps shifts by V for each A-scan.

[0322] Except for the above, the configuration and operation of the ophthalmologic apparatus according to the fifth modified example are similar to the configuration and operation of the ophthalmologic apparatus 1 according to the embodiment.

[0323] According to the fifth modification, the same effect as that of the embodiment can be obtained without providing the EOM 80.

[0324] (Sixth Modification) In the embodiment and its modified example, the case where phase modulation is performed using the EOM 80 or the piezoelectric element 81 has been described, but the configuration according to the embodiment is not limited to this.

[0325] An example of the configuration of an optical system of an ophthalmic apparatus 1f according to a sixth modified example of the embodiment is shown in Fig. 26. In Fig. 26, the same parts as those in Fig. 11 are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0326] The configuration of the optical system of the ophthalmic apparatus 1f according to the sixth modification is different from the configuration of the optical system of the ophthalmic apparatus 1 shown in FIG. 11 in that an optical scanner 42f is provided instead of the optical scanner 42.

[0327] First, an optical scanner 42 according to the embodiment or first to fifth modified examples of the embodiment will be described.

[0328] FIG. 27 schematically shows an example of the configuration of an optical scanner 42 according to the embodiment or the first to fifth modified examples of the embodiment.

[0329] The optical scanner 42 includes a first galvanometer mirror 421 as a first optical scanner and a second galvanometer mirror 422 as a second optical scanner. The first galvanometer mirror 421 deflects the measurement light LS so as to scan the imaging region (fundus Ef or anterior segment) in the y direction perpendicular to the optical axis O of the OCT unit 100. The second galvanometer mirror 422 deflects the measurement light LS deflected by the first galvanometer mirror 421 so as to scan the imaging region in the x direction perpendicular to the optical axis O of the OCT unit 100.

[0330] The scan rotation center of the first galvanometer mirror 421 is located on the optical axis O along which the parallel beam of measurement light LS travels. Similarly, the scan rotation center SC of the second galvanometer mirror 422 is also located on the optical axis O. This allows the measurement light LS to scan the xy plane at the imaging site without generating a difference in optical path length depending on the rotation angles of the deflection surfaces of the first galvanometer mirror 421 and the second galvanometer mirror 422.

[0331] Fig. 28 is a schematic diagram showing an example of the configuration of an optical scanner 42f according to the sixth modified example. In Fig. 28, the same parts as those in Fig. 27 are denoted by the same reference numerals, and the description thereof will be omitted where appropriate.

[0332] The optical scanner 42f includes a first galvanometer mirror 421 as a first optical scanner and a second galvanometer mirror 423 as a second optical scanner. The first galvanometer mirror 421 deflects the measurement light LS so as to scan the imaging region (fundus oculi Ef or anterior segment) in the y direction perpendicular to the optical axis O of the OCT unit 100. The second galvanometer mirror 423 deflects the measurement light LS deflected by the first galvanometer mirror 421 so as to scan the imaging region in the x direction perpendicular to the optical axis O of the OCT unit 100.

[0333] However, the scan rotation center of the first galvanometer mirror 421 is located on the optical axis O along which the parallel beam of measurement light LS travels, whereas the scan rotation center SC of the second galvanometer mirror 423 is located at a position eccentric to the optical axis O. Such an arrangement of the second galvanometer mirror 423 is disclosed in, for example, Non-Patent Document 2. When the amount of deviation of the scan rotation center SC with respect to the optical axis O is s, the deflection angle is Δβ, the number of A scans in a B scan is N, and the central frequency of the measurement light LS is λ, the amount of phase change Φ between two A scans adjacent in the x direction is expressed by Equation (16) (see Non-Patent Document 2).

[0334]

number

[0335] Except for the above, the configuration and operation of the ophthalmologic apparatus according to the sixth modified example are similar to the configuration and operation of the ophthalmologic apparatus 1 according to the embodiment.

[0336] According to the sixth variant, the optical path length of the measurement light LS can be changed according to the rotation angle of the deflection surface of the second galvanometer mirror 423, so that the same effect as in the embodiment can be obtained without using the EOM 80 or the piezoelectric element 81.

[0337] In the sixth modification, the scan rotation center of the first galvanometer mirror 421 may be disposed at a position eccentric to the optical axis O, and the scan rotation center of the second galvanometer mirror 423 may be disposed on the optical axis O. In some embodiments, the relative position of the scan rotation center of the second galvanometer mirror 423 with respect to the optical axis O is configured to be changeable.

[0338] In some embodiments, a program for causing a computer to execute the above-described information processing method is provided. Such a program can be stored on any non-transitory computer-readable recording medium. The recording medium may be an electronic medium that utilizes magnetic, optical, magneto-optical, or semiconductor materials. Typically, the recording medium is a magnetic tape, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, a solid-state drive, or the like. The program can also be transmitted and received via a network such as the Internet or a LAN.

[0339] [Effect] An information processing device, an OCT device, an information processing method, and a program according to an embodiment will be described.

[0340] A first aspect of the embodiment is an information processing device (information processing unit 600, arithmetic and control unit 200 (control unit 210, image forming unit 220, data processing unit 230)) including an identification unit (redundancy identification unit 231) and a resizing processing unit (232). The identification unit identifies redundancy in the lateral direction (x direction, t direction, B-scan direction) from B-scan data obtained by performing a B-scan on an object to be measured (700, subject's eye E) using optical coherence tomography. The resizing processing unit changes the data size of the B-scan data based on the redundancy identified by the identification unit.

[0341] According to this aspect, it is possible to optimize the scan data acquired by full-range OCT without reducing the amount of information, thereby achieving observation over a long range in the depth direction using full-range OCT, while also achieving secondary effects such as shortening processing time and saving resources.

[0342] In a second aspect of the embodiment, in the first aspect, the B-scan data is scan data that has been frequency modulated in the lateral direction by shifting the phase for each A-scan.

[0343] According to this embodiment, it is possible to optimize the data size of scan data obtained by a B scan using a phase modulation method such as a BM scan without reducing the amount of information.

[0344] In a third aspect of the embodiment, in the first or second aspect, the specifying unit specifies the redundancy based on a spatial spectrum in the spatial frequency domain.

[0345] According to this aspect, the redundancy is determined based on the spatial spectrum in the spatial frequency domain obtained from the B-scan data, so that it is possible to optimize the amount of information according to the scan data without reducing it.

[0346] In a fourth aspect of the embodiment, in the third aspect, the spatial spectrum is a spatial spectrum of a cross-correlation between the measurement light and the reference light.

[0347] According to this aspect, the redundancy in the lateral direction is determined based on the spatial spectrum of the cross-correlation between the measurement light and the reference light, so that it is possible to optimize the data size of the B-scan data without reducing the amount of information.

[0348] In a fifth aspect of the embodiment, in the third or fourth aspect, the specifying unit specifies the redundancy based on the width of the spatial spectrum in the spatial frequency direction.

[0349] According to this aspect, the redundancy is determined based on the width of the spatial spectrum in the spatial frequency domain obtained from the B-scan data, so that it is possible to optimize the amount of information according to the scan data without reducing it.

[0350] In a sixth aspect of the embodiment, in the fifth aspect, the determination unit performs a function fitting process on the spatial spectrum, and determines the width of the spatial spectrum based on the function obtained by the fitting process.

[0351] According to this aspect, the width of the spatial spectrum is specified by fitting processing, so that it is possible to specify the redundancy with high accuracy by simple processing.

[0352] In a seventh aspect of the embodiment, in the third or fourth aspect, the identification unit identifies the scan density of the A-scans based on the spatial spectrum, and identifies the redundancy based on a predetermined reference scan density and the identified scan density.

[0353] According to this aspect, the redundancy is determined from the scan density of the A-scans determined based on the spatial spectrum, using a predetermined reference scan density as a reference, so that the redundancy can be determined with high accuracy using simple processing.

[0354] In an eighth aspect of the embodiment, when the redundancy is R in any of the first to seventh aspects, the resizing processing unit changes the data size of the B-scan data by (1 / R) times.

[0355] According to this aspect, it is possible to optimize the scan data without reducing the amount of information.

[0356] In a ninth aspect of the embodiment, in any of the first to eighth aspects, the resizing processing unit changes the data size of the B-scan data by averaging two or more pieces of A-scan data adjacent in the lateral direction in the lateral direction.

[0357] According to this aspect, it is possible to optimize the data size of the scan data while minimizing the reduction in the amount of information and ensuring the amount of information necessary for observation.

[0358] In a tenth aspect of the embodiment, in any of the first to eighth aspects, the resizing processing unit changes the data size of the B-scan data by thinning out the A-scan data.

[0359] According to this aspect, it is possible to optimize the data size of the scan data through simple processing while ensuring the amount of information necessary for observation.

[0360] An eleventh aspect of the embodiment includes a display control unit (control unit 210, main control unit 211) that displays an image of the object to be measured (OCT image, tomographic image) on a display means (display device 3, display unit 240A) based on B-scan data whose data size has been changed by a resizing processing unit in any of the first to tenth aspects.

[0361] According to this embodiment, it is possible to observe an image of the object to be measured based on B-scan data with an optimized data size.

[0362] A twelfth aspect of the embodiment is an OCT device (500, OCT unit 100, and optical scanner 42 (42f)) including an optical scanner (520, 42, 42f), an interference optical system (510, an optical system through which measurement light LS passes from the OCT unit 100 to the objective lens 22), a control unit (540, 210), a scan data generation unit (530, image formation unit 220), and any of the information processing devices of the first to eleventh aspects. The interference optical system splits light (LO) from a light source (light source unit 101) into reference light (LR) and measurement light (LS), irradiates the measurement light deflected by the optical scanner onto a measured object, and detects interference light (LC) between return light of the measurement light from the measured object and the reference light. The control unit controls the optical scanner and also controls the interference optical system to change the difference between the optical path length of the reference light and the optical path length of the measurement light for each A-scan. The scan data generation unit generates B-scan data based on the detection result of the interference light.

[0363] According to this aspect, it is possible to provide an OCT device that can acquire full-range OCT scan data with an optimized data size without reducing the amount of information.

[0364] A thirteenth aspect of the embodiment is an information processing method including a specifying step and a resizing step. The specifying step specifies redundancy in the lateral direction (x direction, t direction, B-scan direction) from B-scan data obtained by performing a B-scan on an object to be measured (700, subject's eye E) using optical coherence tomography. The resizing step changes the data size of the B-scan data based on the redundancy specified in the specifying step.

[0365] According to this aspect, it is possible to optimize the scan data acquired by full-range OCT without reducing the amount of information, thereby achieving observation over a long range in the depth direction using full-range OCT, while also achieving secondary effects such as shortening processing time and saving resources.

[0366] In a fourteenth aspect of the embodiment, in the thirteenth aspect, the B-scan data is scan data frequency modulated in the lateral direction by shifting the phase for each A-scan.

[0367] According to this embodiment, it is possible to optimize the data size of scan data obtained by a B scan using a phase modulation method such as a BM scan without reducing the amount of information.

[0368] In a fifteenth aspect of the embodiment, in the thirteenth or fourteenth aspect, the specifying step specifies the redundancy based on a spatial spectrum of a cross-correlation between the measurement light and the reference light in the spatial frequency domain.

[0369] According to this aspect, the redundancy is determined based on the spatial spectrum in the spatial frequency domain obtained from the B-scan data, so that it is possible to optimize the amount of information according to the scan data without reducing it.

[0370] In a sixteenth aspect of the embodiment, in the fifteenth aspect, the spatial spectrum is a spatial spectrum of a cross-correlation between the measurement light and the reference light.

[0371] According to this aspect, the redundancy in the lateral direction is determined based on the spatial spectrum of the cross-correlation between the measurement light and the reference light, so that it is possible to optimize the data size of the B-scan data without reducing the amount of information.

[0372] In a seventeenth aspect of the embodiment, in the fifteenth or sixteenth aspect, the specifying step specifies the redundancy based on a width of the spatial spectrum in the spatial frequency direction.

[0373] According to this aspect, the redundancy is determined based on the width of the spatial spectrum in the spatial frequency domain obtained from the B-scan data, so that it is possible to optimize the amount of information according to the scan data without reducing it.

[0374] In an eighteenth aspect of the embodiment, in the seventeenth aspect, the specifying step performs a function fitting process on the spatial spectrum, and specifies the width of the spatial spectrum based on the function obtained by the fitting process.

[0375] According to this aspect, the width of the spatial spectrum is specified by fitting processing, so that it is possible to specify the redundancy with high accuracy by simple processing.

[0376] In a 19th aspect of the embodiment, in the 15th or 16th aspect, the identifying step identifies the scan density of the A-scans based on the spatial spectrum, and identifies redundancy based on a predetermined reference scan density and the identified scan density.

[0377] According to this aspect, the redundancy is determined from the scan density of the A-scans determined based on the spatial spectrum, using a predetermined reference scan density as a reference, so that the redundancy can be determined with high accuracy using simple processing.

[0378] In a twentieth aspect of the embodiment, when the redundancy is R in any of the thirteenth to nineteenth aspects, the resizing step changes the data size of the B-scan data by (1 / R) times.

[0379] According to this aspect, it is possible to optimize the scan data without reducing the amount of information.

[0380] In a 21st aspect of the embodiment, in any of the 13th to 20th aspects, the resizing processing step changes the data size of the B-scan data by averaging two or more A-scan data adjacent in the lateral direction in the lateral direction.

[0381] According to this aspect, it is possible to optimize the data size of the scan data while minimizing the reduction in the amount of information and ensuring the amount of information necessary for observation.

[0382] In a 22nd aspect of the embodiment, in any of the 13th to 20th aspects, the resizing step changes the data size of the B-scan data by thinning out the A-scan data.

[0383] According to this aspect, it is possible to optimize the data size of the scan data through simple processing while ensuring the amount of information necessary for observation.

[0384] A 23rd aspect of the embodiment, in any of the 13th to 22nd aspects, includes a display step of displaying an image of the object to be measured (OCT image, tomographic image) on a display means (display device 3, display unit 240A) based on the B-scan data whose data size has been changed in the resizing processing step.

[0385] According to this embodiment, it is possible to observe an image of the object to be measured based on B-scan data with an optimized data size.

[0386] A twenty-fourth aspect of the embodiment is a program for causing a computer to execute each step of the information processing method of any one of the thirteenth to twenty-third aspects.

[0387] According to this aspect, it is possible to provide a program that optimizes scan data acquired by full-range OCT without reducing the amount of information, thereby achieving observation over a long range in the depth direction using full-range OCT, while also achieving secondary effects such as shortening processing time and saving resources.

[0388] According to this aspect, an optical element is placed in the optical path of the measurement light, and an optical path length difference relative to the reference position of the A-scan is imparted to the measurement light for each A-scan position, making it possible to expand the imaging range of OCT in the depth direction simply and at low cost.

[0389] The configuration described above is merely one example for suitably implementing the present invention. Therefore, any modifications (omissions, substitutions, additions, etc.) can be made as appropriate within the scope of the gist of the present invention. The configuration to be applied is selected, for example, depending on the purpose. Furthermore, depending on the configuration to be applied, effects that are obvious to those skilled in the art or the effects described in this specification can be obtained. [Explanation of symbols]

[0390] 1, 1a, 1b, 1f Ophthalmic equipment 42, 42f, 520 optical scanner 80 EOM 81 Piezo element 100, 100c, 100d, 100e OCT units 200, 200b arithmetic and control unit 210, 540 Control unit 211 Main control unit 212 Storage section 220 Image forming unit 221 Rescaling processing unit 222 First Fourier transform processing section 223 Window function processing section 224 Inverse Fourier transform processing section 225 Second Fourier transform processing section 230 Data Processing Unit 231 Redundancy identification part 231A Fitting Processing Section 232 Resize processing section 233 Analysis Department 240A display section 240B Operation section 500 OCT equipment 510 Interference Optical System 530 Scan data generation unit 600 Information Processing Department E. Examined eye LC interference light LR reference light LS measurement light

Claims

1. an identification unit that identifies the scan density of the A scan based on a width in the spatial frequency direction of a spatial spectrum in the spatial frequency domain of the cross-correlation between the measurement light and the reference light from B scan data obtained by performing a B scan on the object to be measured using optical coherence tomography, and identifies a redundancy in the lateral direction based on a predetermined reference scan density and the identified scan density; a resizing processing unit that reduces a data size of the B-scan data in a lateral direction based on the redundancy identified by the identifying unit; An information processing device comprising:

2. The B-scan data is frequency-modulated in the lateral direction by shifting the phase for each A-scan.

2. The information processing apparatus according to claim 1, wherein:

3. The specifying unit performs a function fitting process on the spatial spectrum, and specifies a width of the spatial spectrum based on the function obtained by the fitting process.

2. The information processing apparatus according to claim 1, wherein:

4. When the redundancy is R, the resizing processing unit reduces the data size of the B-scan data by (1 / R) times in the lateral direction.

4. The information processing device according to claim 1, wherein the information processing device is a computer.

5. The resizing processing unit reduces the data size of the B-scan data in the lateral direction by averaging two or more pieces of A-scan data adjacent in the lateral direction in the lateral direction.

5. The information processing device according to claim 1, wherein the information processing device is a computer.

6. The resizing processing unit reduces the data size of the B-scan data in the lateral direction by thinning out the A-scan data.

5. The information processing device according to claim 1, wherein the information processing device is a computer.

7. a display control unit that displays an image of the object to be measured on a display unit based on the B-scan data whose data size has been reduced in the lateral direction by the resizing processing unit; 7. The information processing device according to claim 1, wherein the information processing device is a computer.

8. An optical scanner; an interference optical system that splits light from a light source into reference light and measurement light, irradiates the measurement light deflected by the optical scanner onto the object to be measured, and detects interference light between return light of the measurement light from the object to be measured and the reference light; a control unit that controls the optical scanner and also controls the interference optical system so as to change the difference between the optical path length of the reference light and the optical path length of the measurement light for each A-scan; a scan data generation unit that generates the B-scan data based on a detection result of the interference light; An information processing device according to any one of claims 1 to 7; An optical coherence tomography device comprising:

9. a specifying step of specifying a scan density of an A-scan based on a width in a spatial frequency direction of a spatial spectrum in a spatial frequency domain of a cross-correlation between a measurement light and a reference light from B-scan data obtained by performing a B-scan on a measurement object using optical coherence tomography, and specifying a redundancy in a lateral direction based on a predetermined reference scan density and the specified scan density; a resizing step of reducing a data size of the B-scan data in a lateral direction based on the redundancy identified in the identifying step; An information processing method, including:

10. The B-scan data is frequency-modulated in the lateral direction by shifting the phase for each A-scan.

10. The information processing method according to claim 9.

11. The identifying step performs a function fitting process on the spatial spectrum, and identifies a width of the spatial spectrum based on the function obtained by the fitting process.

10. The information processing method according to claim 9.

12. When the redundancy is R, the resizing step reduces the data size of the B-scan data by (1 / R) times in the lateral direction. The information processing method according to any one of claims 9 to 11.

13. The resizing step reduces the data size of the B-scan data in the lateral direction by averaging two or more pieces of A-scan data adjacent in the lateral direction in the lateral direction. The information processing method according to any one of claims 9 to 12.

14. The resizing step reduces the data size of the B-scan data in the lateral direction by thinning out the A-scan data. The information processing method according to any one of claims 9 to 12.

15. a display step of displaying an image of the object on a display means based on the B-scan data whose data size has been reduced in the lateral direction in the resizing step. The information processing method according to any one of claims 9 to 14.

16. A program causing a computer to execute each step of the information processing method according to any one of claims 9 to 15.

Images