JP2023049396A - Ophthalmologic imaging device and ophthalmologic imaging program - Google Patents

Abstract

To provide an ophthalmologic imaging device and an ophthalmologic imaging program capable of acquiring appropriate OCT data on an eye to be examined.SOLUTION: An ophthalmologic imaging device for imaging an eye to be examined includes: an OCT optical system for dividing light from a light source into a measurement light path and a reference light path, and detecting, by a detector, a spectral interference signal of return light of the measurement light guided to the eye to be examined through an objective lens and the reference light corresponding to the measurement light; OCT data acquisition means for acquiring OCT data based on the spectral interference signal without using a saturation signal based on the reflection light generated when the measurement light is reflected by the objective lens, the saturation signal being generated in part of the spectral interference signal; and output means for outputting the OCT data.SELECTED DRAWING: Figure 7

Description

The present disclosure relates to an ophthalmic imaging apparatus and an ophthalmic imaging program for imaging an eye to be examined.

2. Description of the Related Art In order to obtain OCT data of an eye to be inspected, an ophthalmologic imaging apparatus is known which has an OCT optical system in which a detector detects an interference signal between measurement light and reference light reflected from the eye to be inspected.

JP 2015-195874 A

In the above apparatus, the reflected light of the measurement light reflected by the objective lens may be received by the detector. In such a case, there is a possibility that the interference signal will saturate and appropriate OCT data cannot be acquired, such as noise occurring in the OCT data.

In view of the above problems, the technical problem of the present disclosure is to provide an ophthalmologic imaging apparatus and an ophthalmologic imaging program capable of acquiring appropriate OCT data of an eye to be examined.

In order to solve the above problems, the present invention is characterized by having the following configurations.

(1) An ophthalmologic imaging apparatus according to a first aspect of the present disclosure divides light from a light source into a measurement optical path and a reference optical path, returns light of measurement light guided to the subject's eye via an objective lens, OCT optics for detecting by a detector a spectral interference signal of a reference beam corresponding to light and a saturation signal occurring in a portion of said spectral interference signal, said measuring beam reflected by said objective lens. An OCT data acquisition means for acquiring OCT data based on the spectral interference signal without using a saturation signal based on reflected light, and an output means for outputting the OCT data.
(2) An ophthalmologic imaging program according to a second aspect of the present disclosure is an ophthalmologic imaging apparatus for imaging an eye to be examined, in which light from a light source is divided into a measurement optical path and a reference optical path, and an objective lens is attached to the eye to be examined. An ophthalmologic imaging program for use in an ophthalmologic imaging apparatus having an OCT optical system for detecting, by a detector, a spectrum interference signal between the return light of the measurement light guided through the optical path and the reference light corresponding to the measurement light, the ophthalmic imaging program comprising: Based on the spectral interference signal without using the saturation signal generated in the part of the spectral interference signal by being executed by the processor of the imager, wherein the saturation signal is based on the reflected light of the measurement light reflected by the objective lens. An OCT data acquisition step of acquiring OCT data and an output step of outputting OCT data are executed by the ophthalmologic imaging apparatus.

It is a figure which shows the optical system and control system of the ophthalmologic imaging device which concerns on a present Example. It is a figure which shows an example of the screen displayed on the display part which concerns on a present Example. FIG. 10 is a diagram showing an example of a fundus image in which noise is generated due to reflection of an objective lens; FIG. 4 is a diagram for explaining a method of suppressing reflection of light with a predetermined wavelength by coating; FIG. 4 is a flowchart of control operations executed by the ophthalmologic imaging apparatus of the embodiment; FIG. 10 is a diagram for explaining a method of setting scan lines; FIG. 4 is a flow chart of control operations when obtaining a tomographic image; It is a figure for demonstrating a saturation signal. FIG. 10 is a diagram showing an example of a spectral interference signal with DC components removed; FIG. 11 shows an example of a spectral interference signal with saturated signals interpolated; FIG. 3 is a diagram showing an example of a fundus image acquired by the ophthalmologic imaging apparatus according to the embodiment;

[overview]
An embodiment of an ophthalmologic imaging apparatus according to the present disclosure will be described. The items classified in <> below can be used independently or in conjunction with each other.

An ophthalmologic imaging apparatus (for example, an ophthalmologic imaging apparatus 1) of the present embodiment is an apparatus for imaging an eye to be examined. The ophthalmic imaging apparatus includes an OCT optical system (eg, OCT optical system 200). The ophthalmologic imaging apparatus also includes OCT data acquisition means (for example, control unit 70). Furthermore, the ophthalmologic imaging apparatus includes output means (for example, display unit 75) for outputting OCT data.

<OCT optical system>
The OCT optical system divides light from a light source (for example, the OCT light source 102) into a measurement light path and a reference light path, and returns the measurement light guided to the eye to be examined through an objective lens (for example, the objective lens 25), A spectral interference signal of the reference light corresponding to the measurement light and the spectral interference signal are detected by a detector (eg, detector 120). The objective lens may be an objective lens group consisting of a plurality of lenses.

For example, the OCT optical system may be based on a Fourier domain OCT optical system. The Fourier domain OCT optics may be spectral domain OCT (SD-OCT) optics. In this case, a broadband light source may be used as the light source and a spectrometer may be used as the detector. Also, for example, the Fourier domain OCT optical system may be a wavelength-swept OCT (SS-OCT) optical system. In this case, a variable wavelength light source may be used as the light source and a balance detector may be used as the detector.

In addition, intensity OCT for detecting the reflection intensity of the eye to be examined, OCT angiography (for example, Doppler OCT) for detecting motion contrast data of the eye to be examined, polarization sensitive OCT (PS-OCT), intensity OCT and PS- It is also possible to apply the technology of this embodiment to multi-function OCT combined with OCT.

OCT data may be data generated from spectral interference signals. For example, OCT data includes A-scan data (e.g., A-scan tomographic image data, etc.), B-scan data (e.g., B-scan tomographic image data, two-dimensional OCT angio data, etc.), three-dimensional data (e.g., three-dimensional tomographic data). image data, three-dimensional OCT angio data, etc.). Note that the B-scan tomographic image data may be tomographic image data acquired by scanning the measurement light along the scanning line (transverse position) in any one of the XY directions. This may include 2D OCT angio data and the like. The three-dimensional tomographic image data may be tomographic image data obtained by two-dimensional scanning with measurement light. This may include 3D OCT angio data. Further, for example, the tomographic image data of the subject's eye may be en face image data based on such tomographic image data. This may include OCT frontal image data, frontal motion contrast data, and the like.

<OCT data acquisition means>
The OCT data acquisition means acquires OCT data based on the spectral interference signal without using a saturated signal generated in a part of the spectral interference signal and based on the reflected light of the measurement light reflected by the objective lens. . For example, a saturation signal can be generated by a detector detecting the reflected light of the measurement light reflected by the objective lens. More specifically, the saturation signal is generated by detecting a signal due to the reflected light of the measurement light in addition to the spectral interference signal, and part of the spectral interference signal reaches the detection limit (dynamic range) of the detector. obtain. In other words, it can occur when the combined intensity of the spectral interference signal and the reflected light exceeds the detection limit of the detector. If the spectral interference signal contains a saturated signal, noise may occur in the OCT data. However, by not using the saturated signal, appropriate OCT data with reduced noise can be obtained.

The OCT data acquisition means may acquire OCT data without using the saturation signal of the spectral interference signal when the saturation signal in the spectral interference signal is detected by the detection means described later. For example, when a saturation signal is detected in the spectral interference signal, the OCT data acquisition means may appropriately remove the saturation signal and acquire OCT data based on a signal different from the saturation signal. As an example, instead of obtaining again a spectral interference signal that does not include a saturation signal separately from the initially obtained spectral interference signal by adjusting the gain of the detection means, etc., the saturation of the initially obtained spectral interference signal may be obtained. OCT data may be acquired by using a signal with a different wavelength band from the signal. This makes it possible to obtain good OCT data.

The OCT data acquisition means may acquire OCT data based on the spectral interference signal in which the saturation signal is interpolated by an interpolation means described later. For example, the OCT data acquisition means can acquire good OCT data by estimating signal strength that a saturation signal can have and using the estimated signal instead of the saturation signal.

The OCT data acquisition means can also acquire OCT data without using the saturation signal by discarding the saturation signal in the spectral interference signal. This also makes it possible to reduce noise caused by saturation signals. However, for example, when the saturated signal is interpolated, the resolution in the depth direction for the portion where noise is reduced may be higher than when the saturated signal is discarded. Therefore, better OCT data can be obtained by interpolating the saturated signal in the spectral interference signal.

Further, the OCT data acquisition means can acquire better OCT data when the saturation signal is detected by the detection means described later and the saturation signal is interpolated by the interpolation means described later. For example, when a position (for example, wavelength band, frequency, etc.) to be treated as a saturated signal is set in advance from experiments or simulations, and a position different from this is used for arithmetic processing for interpolation, the actual saturated signal Signals that do not have the same value may also be treated as saturated signals and interpolated. In other words, there is a possibility that even signals that do not affect noise are removed and interpolated. Therefore, for example, by detecting and interpolating the saturation signal, only the saturation signal can be appropriately replaced.

The OCT data acquisition means may acquire OCT data without using the saturation signal of the spectral interference signal when the focus control means, which will be described later, places the focus adjustment unit at a predetermined position. For example, the predetermined position of the focus adjustment unit may be a position at which the reflected light of the measurement light reflected by the objective lens is easily detected by the detector. As an example, the lens surface of the objective lens and the fiber end of the OCT optical system may be in a conjugate positional relationship. Also, as an example, the center of curvature of the objective lens and the fiber end of the OCT optical system may be in a conjugate positional relationship. Note that these predetermined positions may be set in advance through experiments, simulations, or the like. According to this, the focus position is adjusted according to the diopter of the subject's eye, and even if the reflected light of the measurement light from the objective lens is detected, the OCT data with reduced noise based on the saturation signal can be obtained. can be obtained. Further, according to this, when it is difficult to detect the reflected light of the measurement light from the objective lens (that is, it is difficult to generate the saturation signal), execution of arithmetic processing for interpolating the saturation signal can be omitted.

The OCT data acquisition means may acquire OCT data without using the saturation signal of the spectral interference signal when the measurement light passes through a predetermined position in the objective lens. For example, the predetermined position on the objective lens may be a position on the objective lens where the measurement light is likely to be reflected by the objective lens. As an example, it may be the center position of the lens surface of the objective lens and the position near the center. The position where the measurement light is likely to be reflected by the objective lens exists in a wider range from the center of the lens surface as the radius of curvature of the objective lens increases. That is, the predetermined position of the objective lens can change according to the shape of the lens surface. Further, whether or not the measurement light passes through a predetermined position of the objective lens may change depending on the scanning conditions (scanning position, scanning pattern, etc.) of the measurement light. Therefore, the predetermined position of the objective lens may be set in advance by experiments, simulations, or the like based on at least one of the shape of the lens surface of the objective lens and the scanning conditions of the measurement light. According to this, even if the reflected light of the measuring light from the objective lens is detected depending on the scanning conditions of the measuring light, it is possible to acquire OCT data with reduced noise based on the saturation signal. Further, according to this, when it is difficult to detect the reflected light of the measurement light from the objective lens, it is possible to omit the execution of arithmetic processing for interpolation of the saturation signal.

<Detection Means>
In this embodiment, the ophthalmologic imaging apparatus may include detection means (for example, control unit 70). A detection means detects a saturation signal of the spectral interference signal. The detection means may detect whether a saturation signal is present on the spectral interference signal. For example, in this case, it may be detected whether or not the signal intensity of the spectral interference signal includes the value of the detection limit of the detector, and if the value is included, the saturation signal may be present. Also, the detection means may detect the position where the saturation signal is present on the spectral interference signal. For example, in this case, the wavelength band or frequency range in which the signal intensity of the spectral interference signal reaches the detection limit of the detector may be detected. Of course, the detection means may detect whether a saturation signal is present on the spectral interference signal and the position of the saturation signal on the spectral interference signal, respectively.

The detection means may detect the spectral interference signal, or may detect the interference signal obtained by applying noise removal processing (for example, DC subtraction) or the like to the spectral interference signal.

<Interpolation means>
In this embodiment, the ophthalmologic photographing apparatus may include interpolation means (eg, control unit 70). Interpolating means interpolate the saturated signal of the spectral interference signal based on a signal different from the saturated signal. The interpolating means should be able to compensate for the saturation signal of the spectral interference signal based on a signal different from the saturation signal, and calculate the possible signal strength of the spectral interference signal. For example, the possible signal strength of the spectral interference signal may be calculated based on a signal having a wavelength band different from that of the saturated signal among the spectral interference signals.

The interpolator may utilize regression analysis on the spectral interference signal to interpolate the saturated signal. For example, the signal strength corresponding to the saturated signal of the spectral interference signal, which would be obtained assuming that the detector has no detection limit, may be estimated by regression analysis. The spectral interference signal may be interpolated by replacing the saturated signal with the signal estimated in this way. As an example of regression analysis, an autoregressive model may be applied. As an example of regression analysis, GAPES (gapped amplitude and phase estimation) method may be applied.

Note that the interpolation means may perform interpolation on the saturated signal of the spectral interference signal, or may perform interpolation on the saturated signal included in the interference signal obtained by applying noise removal processing (for example, DC subtraction) or the like to the spectral interference signal. Interpolation may be performed.

<Focus adjustment part>
In this embodiment, the ophthalmologic imaging apparatus may include a focus adjustment section (for example, control section 70). The focus adjustment unit adjusts the focus position of the measurement light in the OCT optical system. For example, the focus adjustment may be a lens (eg, focusing lens 124) that is moved along the optical axis. Also, the focus adjustment unit may be a lens that can be inserted and removed on the optical axis. Also, the focus adjustment unit may be a variable focus lens arranged on the optical axis.

<Focus control means>
In this embodiment, the ophthalmologic imaging apparatus may include focus control means (for example, control unit 70). The focus control means arranges the focus adjustment section at a focus position corresponding to the diopter of the subject's eye. For example, the focus control means may be configured to adjust the focus position by controlling a driving section for moving or inserting/removing the focus adjusting section (lens) on the optical axis. Further, for example, the focus adjustment control means may be configured to adjust the focus position by changing the refractive index of the focus adjustment section (variable focus lens).

The focus control means may be configured to appropriately correct the diopter even when the eye to be examined has a large refractive error. For example, the focus position may be adjustable so that the dioptric power can be corrected for refractive errors of −10D or less and +10D or more, which are regarded as high-diopter eyes. As an example, the focus position may be adjustable so as to be compatible with at least -15D.

When the focus control means adjusts the focus position according to the diopter, the reflected light of the measurement light reflected by the objective lens may be easily detected by the detector of the OCT optical system. For example, when the focus adjustment unit is arranged at a predetermined first position as the focus position is adjusted by the focus control means, the lens surface of the objective lens and the fiber end of the measurement optical system have a conjugate positional relationship, and the reflection Since the light is collected at the end of the fiber, the reflected light is more likely to be detected by the detector. Further, for example, when the center of curvature of the objective lens and the end of the fiber are in a conjugate positional relationship by arranging the focus adjustment unit at the predetermined second position, the reflected light is similarly detected by the detector. easy to be Note that the first position and the second position are not necessarily the same position.

<Photographing optical system>
In this embodiment, the ophthalmologic imaging apparatus may include an imaging optical system (for example, the fundus camera optical system 100). The imaging optical system irradiates the subject's eye with visible light through an objective lens, and captures a color fundus image of the subject's eye. Additionally, the imaging optical system may be capable of capturing a monochrome fundus image. By having such a configuration, the ophthalmologic imaging apparatus can acquire a color fundus image of the eye to be inspected by the imaging optical system while acquiring OCT data of the eye to be inspected by the OCT optical system.

In this embodiment, the measurement light of the OCT optical system is infrared light, and the objective lens may be coated to suppress reflection of visible light from the imaging optical system. For example, reflection of the measurement light from the objective lens can result in saturation signals, as described above. Further, for example, there is a possibility that noise (white spots) may occur on the color fundus image due to detection by the imaging device of visible light of the imaging optical system reflected by the objective lens. However, it is difficult to sufficiently suppress the reflection of broadband wavelengths including visible light and infrared light by coating the objective lens. Therefore, in this embodiment, infrared light reflected by the objective lens is removed by processing the saturation signal, and visible light reflected by the objective lens is removed by coating. This makes it possible to appropriately acquire both OCT data in which noise caused by reflected light of measurement light (infrared light) is suppressed and a color fundus image in which noise caused by reflected light of visible light is suppressed.

If a color fundus image is to be captured with visible light, the imaging conditions (e.g., exposure time, image sensor size, etc.) should be adjusted based on the acquired color fundus image in order to suppress noise caused by reflected light from the objective lens of visible light. gain, etc.) may change the color and brightness of the color fundus image. In this embodiment, by suppressing the reflected light of visible light with a coating, it is possible to obtain a color fundus image that is less affected by noise (white spots) while suppressing changes in color and brightness of the color fundus image. .

<Output means>
The output means outputs OCT data based on the spectral interference signal. The output means may output the OCT data to the display means (for example, monitor 75) to display the OCT data. Also, the output means may output the OCT data to the printing means to print the OCT data. Also, the output means may output the OCT data to a storage means (for example, memory 74, server, cloud, etc.) to store the OCT data. Note that the output means may output the OCT data by at least one of display, printing, storage, and the like.

Note that the present disclosure is not limited to the apparatus described in this embodiment. For example, terminal control software (program) that performs the functions of the above embodiments is supplied to a system or device via a network or various storage media, and a control device (for example, CPU, etc.) of the system or device reads the program. It is also possible to execute

[Example]
FIG. 1 is a schematic configuration diagram for explaining the configuration of an ophthalmologic imaging apparatus according to this embodiment. In the following description, as an ophthalmologic imaging apparatus, an ophthalmologic imaging apparatus that captures a tomographic image of the fundus of the subject's eye using infrared light and a front image of the fundus of the subject's eye using visible light will be taken as an example. to explain.

The ophthalmologic imaging apparatus 1 of this embodiment mainly includes an illumination optical system 10, a fundus imaging optical system 30, and an interference optical system 200 (hereinafter also referred to as an OCT optical system). Furthermore, the optical system may include a focus index projection optical system 40 , an alignment index projection optical system 50 , and an anterior segment observation optical system 60 . The illumination optical system 10 and the fundus photographing optical system 30 are used as a fundus camera optical system 100 for obtaining a color fundus image by photographing the fundus with visible light (for example, in a non-mydriatic state). The fundus imaging optical system 30 captures a fundus image of the subject's eye. The OCT optical system 200 noninvasively obtains a tomographic image of the fundus of the subject's eye using optical interference technology.

<OCT optical system>
The OCT optical system 200 has a device configuration of a so-called ophthalmic optical coherence tomography (OCT), and captures a tomographic image of the eye E. FIG. The OCT optical system 200 splits light emitted from the OCT light source 102 into measurement light (sample light) and reference light by a coupler (light splitter) 104 . The OCT optical system 200 then guides the measurement light to the fundus Ef of the eye E and guides the reference light to the reference optical system 110 . The measurement light passes through the collimator lens 123 and the focus lens 124 to reach the scanning unit 108, and the direction of reflection is changed by driving two galvanomirrors, for example. Then, the measurement light reflected by the scanning unit 108 is reflected by the dichroic mirror 24 and then focused on the fundus of the subject's eye via the objective lens 25 . After that, the detector (light-receiving element) 120 receives interference light obtained by synthesizing the measurement light reflected by the fundus oculi Ef and the reference light.

A detector 120 detects the state of interference between the measurement light and the reference light. In this embodiment, the spectral intensity of the interference light (hereinafter referred to as a spectral interference signal) is detected by the detector 120, and a depth profile (A-scan signal) in a predetermined range is obtained by Fourier transforming the spectral intensity data. In this embodiment, a broadband light source is used as OCT light source 102 and a spectrometer is used as detector 120 .

The scanning unit 108 scans the fundus of the subject's eye with light emitted from the measurement light source. For example, the scanning unit 108 scans the measurement light two-dimensionally (XY directions (transverse direction)) on the fundus. The scanning unit 108 is arranged at a position substantially conjugate with the pupil. The scanning unit 108 is, for example, two galvanometer mirrors, the reflection angles of which are arbitrarily adjusted by the driving unit 151 .

As a result, the luminous flux emitted from the OCT light source 102 is changed in its reflection (advancing) direction, and the fundus is scanned in an arbitrary direction. This changes the imaging position on the fundus oculi Ef. The scanning unit 108 may be configured to deflect light. For example, in addition to reflecting mirrors (galvanomirrors, polygon mirrors, resonant scanners), acousto-optic devices (AOMs) that change the traveling (deflecting) direction of light are used.

The reference optical system 110 generates reference light that is combined with reflected light obtained by reflection of the measurement light on the fundus oculi Ef. The reference optical system 110 may be of the Michelson type or of the Mach-Zehnder type.

The reference optical system 110 may change the optical path length difference between the measurement light and the reference light by moving an optical member in the reference light path. For example, the reference mirror 131 is moved along the optical axis. The arrangement for changing the optical path length difference may be arranged in the measurement optical path of the measurement optics.

More specifically, the reference optical system 110 mainly includes a collimator lens 129, a reference mirror 131, and a reference mirror driver 150, for example. The reference mirror driver 150 is arranged in the reference light path and is configured to be movable in the optical axis direction so as to change the optical path length of the reference light. The light is returned to the coupler 104 by being reflected by the reference mirror 131 and guided to the detector 120 . As another example, reference optics 110 may be formed by transmissive optics (eg, optical fibers) to direct light from coupler 104 to detector 120 by transmitting it rather than returning it.

<Retinal camera optical system>
Next, an example of the optical arrangement of the retinal camera optical system 100 is shown.

<Illumination optical system>
The illumination optical system 10 has, for example, an observation illumination optical system and a photographing illumination optical system. The photographic illumination optical system mainly includes a photographic light source 14 , a condenser lens 15 , a ring slit 17 , a relay lens 18 , a mirror 19 , a black dot plate 20 , a relay lens 21 , a perforated mirror 22 and an objective lens 25 . The imaging light source 14 may be a flash lamp, an LED, or the like. The black dot plate 20 has a black dot in the center. The imaging light source 14 is used, for example, to photograph the fundus of the subject's eye with light in the visible range.

The observation illumination optical system mainly includes an observation light source 11 , an infrared filter 12 , a condenser lens 13 , a dichroic mirror 16 , a ring slit 17 and an objective lens 25 . The observation light source 11 may be a halogen lamp, an LED, or the like. The observation light source 11 is used, for example, to observe the fundus of the subject's eye with light in the near-infrared region. The infrared filter 12 is provided to transmit near-infrared light with a wavelength of 750 nm or more and cut light in a wavelength band shorter than 750 nm. A dichroic mirror 16 is arranged between the condenser lens 13 and the ring slit 17 . Also, the dichroic mirror 16 has the characteristic of reflecting light from the observation light source 11 and transmitting light from the photographing light source 14 . Note that the observation light source 11 and the photographing light source 14 may be arranged in series on the same optical axis.

<Photographing optical system>
The fundus photographing optical system 30 mainly includes, for example, an objective lens 25, a photographing diaphragm 31, a focusing lens 32, an imaging lens 33, and an image sensor . A photographing diaphragm 31 is located near the aperture of the perforated mirror 22 . The focusing lens 32 is movable in the optical axis direction. The imaging device 35 can be used for imaging with sensitivity in the visible range. The photographing diaphragm 31 is arranged at a position substantially conjugate with the pupil of the subject's eye E with respect to the objective lens 25 . The focusing lens 32 is moved in the optical axis direction by a moving mechanism 49 having a motor.

A dichroic mirror 37 is arranged between the imaging lens 33 and the imaging element 35 and has the property of reflecting a part of infrared light and visible light and transmitting most of the visible light. In the reflection direction of the dichroic mirror 37, an observation imaging device 38 having sensitivity in the infrared region is arranged. A flip-up mirror may be used instead of the dichroic mirror 34 . For example, the flip-up mirror is inserted into the optical path when observing the fundus, and retracted from the optical path when photographing the fundus.

Between the objective lens 25 and the perforated mirror 22, an insertable and removable dichroic mirror (wavelength selective mirror) 24 is provided as an optical path branching member. The dichroic mirror 24 reflects the wavelength light of the OCT measurement light, and the wavelength light (for example, center wavelength 940 nm) of the alignment index projection optical system 50 and the anterior segment illumination light source 58 . In addition, the dichroic mirror 24 has a characteristic of transmitting a wavelength of 800 nm or less including the light source wavelength (for example, the central wavelength of 780 nm) of the wavelength light of the illumination for observing the fundus. At the time of photographing, the dichroic mirror 24 is flipped up in conjunction with the inserting/removing mechanism 66 and retreats out of the optical path. The insertion/removal mechanism 66 can be composed of a solenoid, a cam, and the like.

Further, an optical path correction glass 28 is disposed on the imaging element 35 side of the dichroic mirror 24 so that it can be flipped up by driving the insertion/removal mechanism 66 . When inserting the optical path, the optical path correction glass 28 has a role of correcting the position of the optical axis L1 shifted by the dichroic mirror 24. FIG.

A light beam emitted from the observation light source 11 is turned into an infrared light beam by an infrared filter 12 and reflected by a condenser lens 13 and a dichroic mirror 16 to illuminate a ring slit 17 . The light transmitted through the ring slit 17 reaches the perforated mirror 22 through the relay lens 18 , the mirror 19 , the black dot plate 20 and the relay lens 21 . The light reflected by the perforated mirror 22 passes through the correction glass 28 and the dichroic mirror 24, converges once near the pupil of the subject's eye E by the objective lens 25, and then diffuses to illuminate the fundus of the subject's eye.

The reflected light from the fundus is captured through the objective lens 25, the dichroic mirror 24, the correction glass 28, the aperture of the perforated mirror 22, the imaging diaphragm 31, the focusing lens 32, the imaging lens 33, and the dichroic mirror 37. An image is formed on element 38 . The imaging device 38 is arranged at a conjugate position with the fundus. The output of the imaging device 38 is input to the control unit 70 , and the control unit 70 displays a fundus observation image (fundus front observation image) 82 of the subject's eye imaged by the imaging device 38 on the display unit 75 .

A light beam emitted from the imaging light source 14 passes through a dichroic mirror 16 via a condenser lens 15 . After that, the fundus is illuminated with visible light through the same optical path as illumination light for observing the fundus. Reflected light from the fundus passes through the objective lens 25 , the opening of the perforated mirror 22 , the imaging diaphragm 31 , the focusing lens 32 and the imaging lens 33 and forms an image on the imaging device 35 . In this way, the imaging element 35 captures a color fundus image of the subject's eye.

In this embodiment, the objective lens 25 is coated to suppress reflection of light in the visible range from the imaging light source 14 . Therefore, it is possible to suppress the occurrence of noise on the color fundus image due to the reflected light from the objective lens being received by the imaging device 35 (details will be described later).

<Focus index projection optical system>
The focus index projection optical system 40 mainly includes an infrared light source 41 , a slit index plate 42 , two deflection prisms 43 , a projection lens 47 , and a spot mirror 44 obliquely provided in the optical path of the illumination optical system 10 . Two deflection prisms 43 are attached to the slit optotype plate 42 . A spot mirror 44 is obliquely provided in the optical path of the illumination optical system 10 . Also, the spot mirror 44 is fixed to the tip of the lever 45 . The spot mirror 44 is normally obliquely arranged on the optical axis, but is retracted out of the optical path by rotating the axis of the rotary solenoid 46 at a predetermined timing before photographing.

Note that the spot mirror 44 is arranged at a position conjugate with the fundus of the eye E to be examined. The light source 41 , the slit index plate 42 , the deflection prism 43 , the projection lens 47 , the spot mirror 44 and the lever 45 are moved in the optical axis direction by the movement mechanism 49 in conjunction with the focusing lens 32 . Also, the luminous flux of the slit index plate 42 of the focus index projection optical system 40 passes through the deflection prism 43 and the projection lens 47, is reflected by the spot mirror 44, and then passes through the relay lens 21, the aperture mirror 22, the dichroic mirror 24, It is projected onto the fundus of the subject's eye E through the objective lens 25 . Then, the focus index image projected onto the fundus of the subject's eye is captured together with the fundus image by the imaging device 38 .

<Alignment target projection optical system>
The alignment index projection optical system 50 for projecting the alignment index light flux has a plurality of infrared light sources arranged concentrically around the photographing optical axis L1 at intervals of 45 degrees, as shown in the diagram within the upper left dotted line in FIG. are placed. The ophthalmologic imaging apparatus in this embodiment mainly includes a first target projection optical system (0 degrees and 180 degrees) and a second target projection optical system. The first target projection optical system has an infrared light source 51 and a collimating lens 52 . The second target projection optical system is arranged at a position different from that of the first target projection optical system, and has six infrared light sources 53 . The infrared light sources 51 are arranged symmetrically with respect to a vertical plane passing through the photographing optical axis L1. In this case, the first index projection optical system projects an index at infinity onto the cornea of the eye E to be examined from the left and right. The second index projection optical system is configured to project a finite index onto the cornea of the eye E to be examined from the vertical direction or oblique direction. 1 only shows the first target projection optical system (0 degrees and 180 degrees) and part of the second target projection optical system (45 degrees and 135 degrees) for convenience. .

<Anterior segment observation optical system>
An anterior segment observation (photographing) optical system 60 for imaging the anterior segment of the subject's eye includes a dichroic mirror 61, an aperture 63, a relay lens 64, a two-dimensional imaging element (light receiving element: hereinafter referred to as a 65 (sometimes abbreviated as imaging device 65). The imaging device 65 has sensitivity in the infrared region. The imaging device 65 also serves as imaging means for detecting alignment indices, and images the anterior segment and the alignment indices illuminated by the anterior segment illumination light source 58 emitting infrared light. The anterior segment illuminated by the anterior segment illumination light source 58 is received by the imaging device 65 from the objective lens 25 , the dichroic mirror 24 and the dichroic mirror 61 via the optical system of the relay lens 64 . Further, the alignment light beam emitted from the light source of the alignment target projection optical system 50 is projected onto the cornea of the subject's eye. The corneal reflection image is received (projected) by the imaging device 65 via the objective lens 25 to the relay lens 64 .

The output of the two-dimensional imaging device 65 is input to the control unit 70, and as shown in FIG. be done. The anterior segment observation optical system 60 also serves as a detection optical system for detecting the alignment state of the apparatus body with respect to the subject's eye.

Around the hole of the perforated mirror 22, infrared light sources (two in this embodiment, but not limited to) for forming an optical alignment index (working dot W) on the cornea of the subject's eye are provided. ) 55 are arranged. The light source 55 may be configured to guide the infrared light to an optical fiber whose end face is arranged near the perforated mirror 22 . The light reflected from the cornea by the light source 55 forms an image on the imaging surface of the imaging device 38 when the working distance between the subject's eye E and the imaging unit 3 (apparatus main body) is appropriate. As a result, the examiner can finely adjust the alignment using the working dots formed by the light source 55 while the fundus image is displayed on the monitor 75 .

<Control unit>
The control unit 70 includes a CPU (processor), RAM, ROM, and the like. The CPU controls the ophthalmologic photographing apparatus 1 . The RAM temporarily stores various information. Various programs, initial values, etc. for controlling the operation of the ophthalmologic imaging apparatus 1 are stored in the ROM.

A nonvolatile memory (hereinafter abbreviated as memory) 74 , an operation unit 76 , a device driving unit 6 , a display unit 75 , and the like are electrically connected to the control unit 70 . The memory 72 is a non-transitory storage medium that can retain stored content even when power supply is interrupted. For example, a hard disk drive, a flash ROM, a USB memory detachably attached to the ophthalmologic photographing apparatus 1, and the like can be used as the memory 72 . The memory 72 also stores an imaging control program for controlling imaging of tomographic images and color fundus images by the ophthalmologic imaging apparatus 1 . In addition, the memory 72 stores various information related to imaging such as a tomographic image (OCT data) in a scanning line, a three-dimensional tomographic image (three-dimensional OCT data), a color fundus image, and tomographic image imaging position information.

Various operation instructions are input to the operation unit 76 by the examiner. The operation unit 76 outputs a signal to the CPU 71 according to the input operation instruction. At least one of user interfaces such as a mouse, a joystick, a keyboard, and a touch panel may be used for the operation unit 76, for example.

The device driving unit 6 relatively moves the ophthalmologic imaging device 1 with respect to the eye E to be examined in the left-right direction, the up-down direction, and the front-rear direction. The control unit 70 can change the positional relationship between the ophthalmologic photographing apparatus 1 and the subject's eye E by controlling the device driving unit 6 . For example, the control section 70 may control the device driving section 6 based on the input of the operation section 76 .

The display unit 75 may be a display mounted on the main body of the apparatus, or may be a display connected to the main body. A display of a personal computer (hereinafter referred to as "PC") may be used. Multiple displays may be used together. Moreover, the display unit 75 may be a touch panel. When the display section 75 is a touch panel, the display section 75 functions as the operation section 76 . For example, the display unit 75 displays image data or the like obtained by processing the spectral interference signal acquired by the OCT optical system 100 .

Note that the controller 70 may be configured by a plurality of controllers (that is, a plurality of processors). For example, the control unit 70 of the ophthalmologic imaging apparatus 10 may be configured by a setting control unit provided in a PC and an operation control unit that controls operations of the OCT optical system 100 and the like. In this case, for example, the setting control unit of the PC sets the imaging position of the tomographic image based on the operation of the operation unit connected to the PC, and instructs the operation control unit of the set contents. The operation control section may control the photographing operations of each component of the ophthalmic photographing apparatus 10 in accordance with instructions from the setting control section. Further, the process of generating (obtaining) an image based on the spectral interference signal may be performed by either the operation control section or the setting control section.

The control unit 70 controls the fundus camera optical system 100, the OCT optical system 200, the focus index projection optical system 40, the alignment index projection optical system 50, and the anterior segment observation optical system 60 based on the operation signal output from the operation unit 76. to control each member of

For example, the control unit 70 acquires a tomographic image by image processing based on the spectral interference signal output from the detector 120 of the OCT optical system 200, and the light receiving elements (two-dimensional light receiving element 35, Alternatively, a fundus image (fundus front image) is obtained based on the light receiving signal output from the imaging device for observation 38). Also, for example, the control unit 70 acquires an anterior segment image based on the light receiving signal output from the imaging device 65 . The acquired tomographic image, fundus image, and anterior segment image are output to the display unit 75 as still images or moving images, and are also stored in the memory 72 .

<Reflection of measuring light and photographing light by objective lens>
Here, when the measurement light in the OCT optical system 200 irradiated toward the eye to be examined is reflected by the objective lens 25 and the reflected light of the measurement light is detected by the detector 120, a tomographic image is obtained as shown in FIG. may generate noise N. In addition, when the visible light in the retinal camera optical system 100 irradiated toward the subject's eye is reflected by the objective lens 25 and the reflected light of the visible light is captured by the imaging device 35, noise (for example, , blown-out highlights in a color fundus image, etc.) may occur.

In order to reduce these noises, coating the objective lens 25 may suppress reflection of measurement light (infrared light) from the OCT optical system and visible light from the retinal camera optical system 100. be done. Specifically, as shown in FIG. 4, a coating is applied so that the reflected light of the measuring light and the photographing light reflected by the coating film has an opposite phase with respect to the reflected light of the measuring light and the photographing light from the objective lens. Apply. According to this, the reflected light R1 from the objective lens and the reflected light R2 from the coating film interfere and weaken each other, and as a result, the reflected light R1 from the objective lens 25 is reduced. In addition, for example, by laminating a plurality of antireflection films as coating films, it is possible to suppress reflection of a plurality of lights having different wavelengths.

However, the wider the wavelength band in which reflection is suppressed by the coating film, the more complicated the structure of the antireflection film. For example, when an antireflection film is coated to suppress reflection of light of a specific wavelength, the phase of light of other wavelengths may be shifted by the thickness of the antireflection film. As a result, there may arise problems such as reflection of light of unintended wavelengths and reduction in the amount of reflected light reduction.

Moreover, as the number of coating films laminated on the objective lens increases, the application of the coating itself becomes more difficult. For example, it is assumed that when one layer of antireflection film is coated, a manufacturing error (tolerance) of −0.01 to +0.01 mm (numerical value is an example) occurs in thickness. In this case, if 10 antireflection films are laminated, the total thickness error of the laminated antireflection films is −0.1 to +0.1 mm. In other words, there is an individual difference in thickness within the range of 0.2 mm for each manufactured lens. This may cause problems such as different wavelengths that can suppress reflection and differences in the amount of reflected light that is reduced for each lens. Therefore, as the number of laminated antireflection films increases, more severe conditions are required for coating.

In the present embodiment, for the reasons described above, in an apparatus that combines the OCT optical system 200 and the retinal camera optical system 100, the reflection of the measurement light from the objective lens is suppressed to the extent that noise does not occur in the tomographic image, and It is difficult to coat an objective lens with an antireflection film that suppresses the reflection of visible light from the objective lens to an extent that does not introduce noise into the color fundus image. Even if the reflection of both the measurement light and the visible light can be suppressed to some extent by coating the objective lens, if the amount of reduction of the reflected light is insufficient, at least one of the tomographic image and the color fundus image may generate noise.

For example, in the ophthalmologic imaging apparatus 1 of the present embodiment, the objective lens is coated so that reflection suppression in the visible light band is prioritized over reflection suppression in the infrared light band. As a result, the reflected light of the photographing light of the retinal camera optical system 100 is removed, and a color retinal image with suppressed noise is obtained. In addition, the reflected light of the measurement light from the OCT optical system 200, which was not removed by the coating, is removed by processing the saturation signal included in a part of the spectral interference signal, thereby obtaining a tomographic image with suppressed noise (details are described later). That is, the ophthalmologic apparatus 1 of the present embodiment can acquire both a color fundus image and a tomographic image with suppressed noise.

It should be noted that it is not always necessary to suppress reflection in the infrared band by coating.

[motion]
A control operation of the ophthalmologic photographing apparatus 1 will be described with reference to the flow chart of FIG. In this embodiment, a case of obtaining a tomographic image and a color fundus image of the fundus oculi Ef of the subject's eye will be described.

As shown in FIG. 2, the control unit 70 displays an anterior segment observation image 81 from the imaging device 65, a fundus observation image 82 from the imaging device 38, and a tomographic image 83 from the control unit 70 as an observation screen. may be displayed on the screen of For example, the anterior segment observation image 81, the fundus observation image 82, and the tomographic image 83 may be live images updated in real time, or may be still images.

<S1: Alignment>
The examiner causes the face support unit (not shown) to support the subject's face. Then, the examiner instructs the subject to gaze at the fixation target (not shown). At this time, the dichroic mirror 24 is inserted in the optical path of the fundus imaging optical system 30 , and the anterior segment image captured by the imaging device 65 is displayed on the display section 75 . While observing the image of the anterior segment, the examiner changes the positional relationship between the ophthalmologic photographing apparatus 1 and the subject's eye E by controlling the operation unit 76 to perform alignment. For example, the examiner performs alignment in the left-right direction, the up-down direction, and the back-and-forth direction based on the image height of the alignment index image projected onto the anterior segment of the subject's eye by the alignment index projection optical system 50 . For example, the control unit 70 may automatically perform alignment by detecting an alignment index image through image analysis of the anterior segment image. For details of the alignment method, the method described in JP-A-2015-195874 may be referred to.

After completing the alignment, the controller 70 may determine whether the pupillary condition of the subject's eye is appropriate based on the pupillary edge detected from the anterior segment image. For details of the method of determining whether the pupil state is appropriate, the method described in Japanese Patent Application Laid-Open No. 2005-160549 may be referred to.

Further, after completing the alignment, the control unit 70 may adjust the focus of the retinal camera optical system 100 (autofocus). For example, the control unit 70 acquires a fundus image of the subject's eye from the imaging device 38 . Then, the control unit 70 detects the focus state based on the focus index projected by the focus index projection optical system 40 . The control unit 70 may control driving of the moving mechanism 49 to move the focusing lens 32 along the optical axis and adjust the focus on the fundus. For details of the autofocus method, the method described in Japanese Patent Application Laid-Open No. 2015-195874 may be referred to.

<S2: Setting Scanning Position>
After completing the alignment, the examiner sets the position for acquiring the tomographic image. For example, the examiner may set a position where the tomographic image is desired to be acquired with respect to the fundus oculi observation image 82 on the display unit 75 . As an example of such a case, as shown in FIG. 6, the examiner uses the touch panel display unit 75 to perform a drag operation to move the line 85 with respect to the fundus oculi observation image 82, thereby moving the line 85 to the scan position. set. FIG. 6A is a diagram showing the scan position before the drag operation, and FIG. 6B is a diagram showing the scan position after the drag operation.

<S3: Optimization of shooting conditions>
After setting the scan position, the control unit 70 optimizes the imaging conditions of the OCT optical system 200 . The control unit 70 issues a trigger signal for starting optimization of imaging conditions, and starts optimization control operation. In this embodiment, optimization control is control of optical path length adjustment, focus adjustment, and polarization state adjustment (polarizer adjustment). In addition, in optimization control, it is only necessary to satisfy a certain allowable condition for the fundus, and it is not always necessary to adjust to the most appropriate state.

In the optimization control, the control unit 70 sets the positions of the reference mirror 131 and the focusing lens 124 to initial positions as initialization control. After completion of the initialization, the control unit 70 moves the reference mirror 131 in one direction from the set initial position in predetermined steps to perform the first optical path length adjustment (first automatic optical path length adjustment). Also, in parallel with the first optical path length adjustment, the control unit 70 controls the focus position information (for example, the movement of the lens 32) with respect to the fundus of the subject's eye based on the above-described focus result of the fundus camera optical system with respect to the fundus of the subject's eye. amount). When the focus position information is acquired, the control unit 70 controls the drive unit 124a to move the focusing lens 124 to the focus position, and performs autofocus adjustment (focus adjustment). Note that the in-focus position may be any position at which contrast of a tomographic image acceptable as an observation image can be obtained, and does not necessarily have to be the optimum position for the focus state.

After the focus adjustment is completed, the control unit 70 moves the reference mirror 131 in the optical axis direction again to perform the second optical path length adjustment for readjusting the optical path length (fine adjustment of the optical path length). After the second optical path length adjustment is completed, the controller 70 drives the polarizer 133 for adjusting the polarization state of the reference light to adjust the polarization state of the measurement light (for details, see Japanese Patent Application No. 2012-56292).

By completing the optimization control operation as described above, the examiner can observe the fundus region desired by the examiner with high sensitivity and high resolution.

<S4: Acquisition of tomographic image>
When the optimization of the imaging conditions is completed, the examiner inputs imaging signals to the control section 70 via the operation section 76 . Acquisition of a tomographic image is thereby started. Details of the control operation for acquiring a tomographic image will be described with reference to the flowchart of FIG.

<S401: Acquisition of spectrum interference signal>
First, the control unit 70 acquires a tomographic image by B-scan based on the set scanning position. The control unit 70 drives the scanning unit 108 to scan the measurement light so that a tomographic image of the fundus corresponding to the display position of the line 85 set on the fundus observation image 82 is obtained.

A spectral interference signal is obtained by receiving interference light obtained by combining the return light of the measurement light reflected by the subject's eye and the reference light by the detector (light receiving element) 120 . A spectral interference signal (spectral data) is expressed as signal intensity for each wavelength. The spectral interference signal may also be rewritten as a function of wavelength λ and transformed into an equidistant function with respect to wavenumber k (=2π/λ).

Here, as shown in FIG. 8, when the reflected light of the measurement light reflected by the objective lens 25 is received by the detector 120, the detected spectral interference signal Sp0 has a higher signal intensity than the original spectral interference signal Sp1. increases such that a portion of the spectral interference signal may exceed the detection range Ra of detector 120 . In this case, the portion exceeding the detection range (Sp2 in FIG. 8) is saturated, and the signal strength of the portion is output as a signal having a detection limit value (for example, signal strength Ia). In this embodiment, the portion (Sp3 in FIG. 8) where the signal intensity is output as the value of the detection limit is treated as a saturated signal.

<S402: Detect saturation signal on spectrum interference signal>
If a tomographic image is acquired using a saturated signal, it may not be possible to obtain a suitable tomographic image. As an example, as shown in FIG. 3, noise N may occur on the tomographic image. Therefore, the control unit 70 detects a saturated signal on the spectral interference signal and performs interpolation processing. Thereby, a tomographic image in which noise N is suppressed is obtained.

The control unit 70 detects whether a saturation signal is included in the spectral interference signal by analyzing the acquired spectral interference signal. If the spectral interference signal is detected to contain a saturating signal, the control unit 70 detects where in frequency the saturating signal appears. As an example, when there is a portion having a predetermined signal strength Ia in the spectrum interference signal, the control section 70 detects that portion as a saturation signal.

After detecting the saturation signal, the controller 70 performs DC subtraction to remove the DC component. FIG. 9 is a diagram showing a spectral interference signal with the DC component removed. For example, even if the DC component is removed, the portion corresponding to the saturation signal is not removed. For example, the control unit 70 may perform arithmetic processing for removing noise components such as compensation for group velocity dispersion.

Note that when no saturation signal is detected, there is no saturated portion in the interference signal and no noise occurs in the fundus image, so the interpolation processing described below need not be performed.

<S403: Interpolation processing>
When the saturation signal is detected on the spectrum interference signal, the control unit 70 performs interpolation processing described below to detect the saturation signal (that is, the signal strength exceeds the detection limit of the detector 120, so that the signal strength Ia detected part).

As interpolation processing, the control unit 70 interpolates the saturation signal by performing arithmetic processing on the spectral interference signal from which the DC component has been removed using a portion other than the saturation signal. An example of arithmetic processing using portions other than the saturation signal will be described below.

First, the control unit 70 performs regression analysis on the spectral interference signal to estimate the missing portion of the spectral interference signal. As an example of regression analysis, the control unit 70 applies an autoregressive model to the spectral interference signal to estimate missing portions of the spectral interference signal. The controller 70 then interpolates the saturated signal for the spectral interference signal by replacing the estimated signal with the saturated signal. FIG. 10 is an example of a spectral interference signal after interpolation. For example, by performing arithmetic processing on the spectral interference signal from which the DC component has been removed, the spectral interference signal can be interpolated more accurately.

By performing regression analysis in this way, the missing interference signal can be interpolated with higher accuracy. Of course, the application of the autoregressive model is an example of a method of estimating the waveform of the missing portion on the spectral interference signal, and is not limited to this. For example, like application of an autoregressive model, arithmetic processing using a portion other than the saturated signal of the spectral interference signal can interpolate the missing portion of the waveform with higher accuracy.

<S404: Fourier Transform>
The control unit 70 acquires a tomographic image as information in the depth domain (Z space) by performing Fourier transform on the interpolated spectral interference signal. Information after Fourier transform may be expressed as a signal containing real and imaginary components in the Z space. The control unit 70 may acquire the tomographic image by obtaining the absolute values of the real number component and the imaginary number component of the signal in the Z space.

According to the above, a tomographic image in which the noise N due to the reflection of the objective lens 25 is reduced is acquired. FIG. 11 is an example of a tomographic image in which noise due to reflection of the objective lens 25 is reduced.

<S5: Acquisition of color fundus image>
When the tomographic image is obtained, the control unit 70 acquires a color fundus image 82 with the fundus camera optical system 100 . While observing the fundus observation image 82 displayed on the display unit 75, the examiner operates the operation unit 76 to finely adjust the alignment and focus so that the image can be captured in a desired state. Then, when the examiner inputs to start imaging, imaging is performed. The control unit 70 drives the inserting/removing mechanism 66 based on a trigger signal from a photographing start switch (not shown), thereby removing the dichroic mirror 24 from the optical path and causing the photographing light source 14 to emit light.

When the imaging light source 14 emits light, the fundus of the subject's eye is illuminated with visible light. Reflected light from the fundus passes through the objective lens 25 , the opening of the perforated mirror 22 , the photographing diaphragm 31 , the focusing lens 32 , the imaging lens 33 and the dichroic mirror 37 and forms an image on the two-dimensional light receiving element 35 . A color fundus image captured by the two-dimensional light receiving element 35 is stored in the memory 72 .

Here, as described above, the objective lens 25 is coated so as to suppress reflection of light from the imaging light source 14 . For this reason, the occurrence of noise in the front fundus image due to reflection by the objective lens 25 is suppressed. Therefore, a color fundus image can be preferably acquired.

As described above, for example, the ophthalmologic imaging apparatus of this embodiment does not use a saturated signal generated in a part of the spectral interference signal, which is based on the reflected light of the measurement light reflected by the objective lens. , to obtain OCT data based on the spectral interference signal. This provides OCT data with reduced noise due to objective lens reflection.

Further, for example, the ophthalmologic imaging apparatus of the present embodiment detects a saturation signal generated in a part of the spectral interference signal, and when the saturation signal is detected, the OCT data is obtained without using the saturation signal of the spectral interference signal. to get According to this, since the saturation signal is detected, the OCT data can be obtained by appropriately removing the saturation signal from the spectral interference signal.

Also, for example, the ophthalmologic imaging apparatus of this embodiment interpolates the saturated signal of the spectral interference signal based on a signal different from the saturated signal, and acquires OCT data based on the interpolated spectral interference signal. According to this, OCT data can be acquired favorably compared to the case where the saturation signal is discarded without being interpolated. For example, when interpolation is performed, the resolution in the depth direction may be higher for a noise-reduced portion than when interpolation is not performed.

Also, for example, the ophthalmologic imaging apparatus of this embodiment interpolates the saturation signal by using regression analysis for the spectral interference signal. Regression analysis can be used to estimate the signal in the saturated signal portion (saturated and missing portion) on the spectral interference signal. For example, by replacing the estimated signal with the saturated signal, the spectral interference signal can be better interpolated.

Further, for example, the ophthalmologic imaging apparatus of the present embodiment includes a fundus camera optical system 100 that emits visible light through an objective lens and captures a color fundus image of the subject's eye. According to this, it is possible to acquire a color fundus image of the eye to be inspected while acquiring OCT data of the eye to be inspected.

Further, for example, in the ophthalmologic imaging apparatus of this embodiment, the measurement light of the OCT optical system 200 is infrared light, and the objective lens 25 is coated to suppress the reflection of visible light in the retinal camera optical system 100. be. Furthermore, the ophthalmologic imaging apparatus of this embodiment removes infrared light reflected by the objective lens by processing the saturation signal, and removes visible light reflected by the objective lens by coating. As a result, both a color fundus image in which noise due to the reflection of the objective lens is suppressed and OCT data in which noise due to the reflection of the objective lens is suppressed can be obtained.

[Transformation example]
Although the present disclosure has been described above based on the embodiments, the present disclosure is not necessarily limited thereto.

For example, in the OCT optical system 200, when the positions of the fiber end 125 (see FIG. 1) of the measurement optical path and the lens surface (either the front surface or the back surface) of the objective lens 25 are in a conjugate relationship, or when the fiber end When the positions of the portion 125 and the center of curvature of the objective lens 25 are in a conjugate positional relationship, the reflected light of the measuring light from the objective lens is likely to be received by the detector 120 . Therefore, when the position of the fiber end 125 and the position of the lens surface of the objective lens 25 or the center of curvature of the objective lens 25 has a conjugate positional relationship, the control unit 70 controls the above <S402: detection of saturation signal> and <S403>. : Interpolation processing> may be performed. As an example, when the focusing lens 124 is arranged at a position corresponding to a predetermined diopter (-15D as an example) as a result of optimizing the shooting conditions, the control unit 70 detects <S402: saturation signal detection> and <S403: Interpolation processing> may be performed. Of course, the diopter values are just an example.

According to this, the ophthalmologic imaging apparatus can acquire OCT data in which noise caused by this is reduced even when measurement light is likely to be reflected by the objective lens. Further, according to this, it is possible to omit arithmetic processing such as interpolation processing when the reflected light of the objective lens in the measuring light is difficult to be received (that is, the saturation signal is difficult to generate). That is, it is possible to suppress the addition of arithmetic processing to the spectral interference signal when noise does not occur.

Further, for example, there may be a region where the measurement light is likely to be reflected depending on the shape of the objective lens 25 . As an example, the vicinity of the center of the curved surface of the lens may reflect the measurement light more easily than other areas. Therefore, the control unit 70 may perform <S402: detection of saturation signal> and <S403: interpolation processing> when the measurement light passes through a predetermined region of the objective lens 25 . As an example, the control unit 70 may determine whether the measurement light passes through a predetermined region of the objective lens 25 when the examiner sets the scan line 85 . Alternatively, when controlling the scanning unit 108 to scan the measurement light, the control unit 70 may determine whether the measurement light has passed through a predetermined area of the objective lens 25 based on the operation of the scanning unit 108 . When the measurement light passes through the predetermined area of the objective lens 25, the controller 70 may perform <S402: detection of saturation signal> and <S403: interpolation processing>.

According to this, calculations such as interpolation processing can be omitted when reflection is difficult to occur due to the objective lens. Therefore, it is possible to suppress execution of the interpolation process when the spectral interference signal does not include the saturation signal.

Further, for example, the retinal camera optical system 100 may be a slit scan type optical system. In that case, the fundus camera optical system 100 may be an optical system that scans the fundus of the subject's eye with a slit of light and obtains a front image of the fundus based on the reflected light from the fundus. For example, the configuration described in JP-A-2021-104229 may be referred to for the configuration of the slit scan type optical system.

In the above embodiment, the spectral interference signal detected by the detector 120 is rewritten as a function of the wavelength λ, converted into a function with equal intervals with respect to the wavenumber k (=2π/λ), and then the saturation signal is detected. Although described as an example, it is not limited to this. For example, saturation signal detection may be performed on the raw data of the spectral interference signal acquired by the detector 120 . In that case, the portion where the intensity of the light detected by the detector 120 has acquired a predetermined value (for example, 4096) may be detected as a saturation signal. Even in this case, it is possible to obtain a tomographic image in which noise is suitably reduced by similarly performing arithmetic processing such as interpolation processing.

In the above embodiment, the case where the saturated signal is interpolated by performing interpolation processing on the spectral interference signal from which the DC component is removed has been described as an example, but the present invention is not limited to this. For example, interpolation processing may be performed on the spectral interference signal before removing the DC component (that is, the raw data of the spectral interference signal acquired by the detector 120). As interpolation processing in this case, the same interpolation processing as in the above embodiment can be used.

In the above embodiment, the control section 70 detects whether or not a saturation signal is included in the spectral interference signal, but it is not necessary to detect the saturation signal. For example, interpolation processing may be performed on the spectral interference signal whether or not the saturated signal is included. In this case, the easily saturated portion of the spectral interference signal is obtained in advance by experiments, simulations, etc., and the easily saturated portion of the spectral interference signal obtained by actually measuring the eye to be examined is interpolated. processing may be performed.

It should be noted that it is possible to detect whether or not a saturated signal exists on the spectral interference signal, and when it is determined that the saturated signal exists, interpolation processing may be performed on the easily saturated portion that is obtained in advance as described above. .

In the above embodiment, <S402: detection of saturation signal> and <S403: detection of saturation signal> are performed on the spectral interference signal acquired after the imaging signal is input to the control unit 70, as an example of the case where a tomographic image is acquired. Interpolation processing> is performed as an example, but for example, <S402: Saturation signal detection> and <S403: Interpolation processing> are also performed on OCT data acquired as a live image in the control operation. may

In the above embodiment, the case where the objective lens 25 is composed of one lens has been described as an example, but the present invention is not limited to this. The objective lens 25 may be configured as an objective lens unit including a plurality of lenses. For example, even if the measurement light is reflected in the objective lens unit and a saturation signal is generated, noise-suppressed OCT data can be obtained by processing the saturation signal in the same manner as in the above embodiment. When the objective lens unit is coated, at least one lens in the objective lens unit may be coated.

In the above embodiment, the case of suppressing reflection caused by the objective lens 25 has been described as an example, but the present invention is not limited to this. For example, in the OCT optical system 200, even if the measurement light is reflected by optical members (for example, lenses, mirrors, etc.) other than the objective lens 25 and a saturation signal is generated, the saturation signal can be processed to obtain OCT data with suppressed noise.

The ophthalmologic apparatus of this embodiment may be capable of acquiring OCT data without performing complementary processing on spectral interference signals. In that case, it may be possible to switch between performing the interpolation process for the saturated signal of the spectral interference signal or not performing the interpolation process. That is, the ophthalmologic imaging apparatus has switching means for switching between a first mode for acquiring OCT data without using the saturation signal of the spectral interference signal and a second mode for acquiring OCT data using the saturation signal of the spectral interference signal. may be provided. In this case, the OCT data acquisition means acquires OCT data based on the mode set by the switching means. Note that the OCT data acquisition means may acquire both OCT data based on the first mode and the second mode.

The switching means may set each mode based on a switching signal for switching modes. For example, the switching signal may be output by operating the operating unit 76 by the examiner. For example, a button for switching the mode may be displayed on the display unit 75, and the output may be output when the examiner operates the button. In addition, such a button is an example, and it is not limited to this.

The ophthalmologic imaging apparatus of this embodiment may notify the examiner of the execution of interpolation processing for the saturated signal of the spectral interference signal. In other words, the ophthalmologic imaging apparatus may include notification means for notifying execution of saturation signal interpolation by the interpolation means. It should be noted that such notification means may at least notify that interpolation is to be performed, and may also notify that interpolation is not to be performed. For example, the notification means may cause the display unit 75 to display an icon or a message to the effect that the interpolation process is to be executed (or has been executed). Also, a similar message may be generated by a speaker or the like. Also, the same effect may be expressed by a change in the light color or blinking of the lamp.

1 ophthalmic photographing device 25 objective lens 70 control unit 75 monitor 102 OCT light source 120 detector

Claims (9)

An ophthalmic imaging apparatus for imaging an eye to be examined,
Light from a light source is divided into a measurement optical path and a reference optical path, and a spectrum interference signal of the return light of the measurement light guided to the eye to be inspected through the objective lens and the reference light corresponding to the measurement light is detected by a detector. an OCT optical system that detects by
OCT data for acquiring OCT data based on the spectral interference signal without using a saturation signal generated in a part of the spectral interference signal, the saturation signal based on the reflected light of the measurement light reflected by the objective lens. acquisition means;
output means for outputting the OCT data;
An ophthalmologic imaging apparatus comprising: The ophthalmic imaging apparatus of claim 1,
detecting means for detecting the saturation signal of the spectral interference signal;
The OCT data acquisition means acquires the OCT data without using the saturation signal of the spectral interference signal when the saturation signal is detected by the detection means. 2. In the ophthalmic imaging apparatus of claim 1 or 2,
interpolating means for interpolating the saturated signal of the spectral interference signal based on a signal different from the saturated signal;
The ophthalmologic imaging apparatus, wherein the OCT data acquiring means acquires OCT data based on the spectral interference signal interpolated by the interpolating means. In the ophthalmic imaging apparatus according to claim 3,
The ophthalmologic imaging apparatus, wherein the interpolating means interpolates the saturation signal using regression analysis of the spectral interference signal. In the ophthalmic imaging apparatus according to any one of claims 1 to 4,
a focus adjustment unit that adjusts the focus position of the measurement light;
focus control means for arranging the focus adjustment unit at the focus position corresponding to the diopter of the subject's eye;
with
The OCT data acquisition means acquires the OCT data without using the saturation signal of the spectral interference signal when the focus adjustment unit is placed at a predetermined position. In the ophthalmic imaging apparatus according to any one of claims 1 to 5,
The OCT data acquisition means acquires the OCT data without using the saturation signal of the spectral interference signal when the measurement light passes through a predetermined position in the objective lens. Device. In the ophthalmic imaging apparatus according to any one of claims 1 to 6,
An ophthalmologic imaging apparatus, comprising: an imaging optical system for irradiating the eye to be examined with visible light through the objective lens and photographing a color fundus image of the eye to be examined. In the ophthalmic imaging apparatus according to any one of claims 7,
The measurement light of the OCT optical system is infrared light,
A coating for suppressing reflection of the visible light is applied to the objective lens,
An ophthalmic imaging apparatus, wherein the reflected light of the infrared light from the objective lens is removed by processing the saturation signal, and the reflected light of the visible light from the objective lens is removed by the coating. An ophthalmologic photographing apparatus for photographing an eye to be examined, wherein light from a light source is divided into a measurement optical path and a reference optical path, return light of the measurement light guided to the eye to be examined via an objective lens, and the measurement light. An ophthalmic imaging program for use in an ophthalmic imaging apparatus having an OCT optical system that detects a spectral interference signal of a corresponding reference beam and a detector,
By being executed by the processor of the ophthalmic imaging apparatus,
OCT data for acquiring OCT data based on the spectral interference signal without using a saturation signal generated in a part of the spectral interference signal, the saturation signal based on the reflected light of the measurement light reflected by the objective lens. an acquisition step;
an output step of outputting the OCT data;
is executed by the ophthalmologic imaging apparatus.

Images