JP6701659B2 - Fundus imaging device - Google Patents

Description

  The present invention relates to a fundus imaging apparatus.

  2. Description of the Related Art Conventionally, as a fundus imaging apparatus, there is known an apparatus that obtains an image of a fundus of an eye to be inspected by scanning light with an optical scanner. For example, there is known an optical coherence tomography (OCT) that obtains a tomographic image of the fundus based on the principle of optical interference between measurement light scanned on the fundus and reference light (see Patent Document 1). ..

  A scanning laser ophthalmoscope (SLO), which is a type of fundus imaging apparatus, obtains a front image of the fundus as a result of scanning on the fundus. In the scanning laser ophthalmoscope, it has been attempted to image a wide range of the fundus (for example, refer to Patent Document 2).

JP, 2014-057899, A JP, 2014-138904, A

  The inventor of the present invention has attempted to image a wide area of the fundus with an optical coherence tomography (OCT). As a result, it was discovered that when imaging a wide area of the fundus with an optical tomographic interferometer, the optical path length difference between the measurement light and the reference light is likely to change with the change of the scanning position of the optical scanner.

  In view of at least one of the problems of the related art, the present disclosure has an object to provide a fundus imaging apparatus capable of obtaining OCT data in a wide range of the fundus.

The fundus imaging apparatus according to the first aspect of the present disclosure has an optical scanner that scans the measurement light from the light source on the fundus of the eye to be inspected, and the interference between the reference light and the measurement light reflected by the fundus. Through an OCT optical system that detects the light with a detector and a mirror system that is arranged between the eye to be inspected and the optical scanner. An objective mirror system that forms a point, an acquisition unit that obtains OCT data of the fundus by processing a signal from the detector, and the optical scanner from the optical scanner to the eye to be examined at each scanning position of the optical scanner. possess a correction means for correcting the variation of the optical path length difference between the measuring light according to the distance measuring light and the reference light, wherein the correction means, the positional information of the depth direction in each of the plurality of the OCT data A two-dimensional OCT data is formed based on the OCT data after the correction process, including a data processing unit that corrects the relative depth position between the OCT data at each scanning position by performing the correction process. .

  According to the present disclosure, OCT data can be satisfactorily obtained over a wide range of the fundus.

It is a figure which shows schematic structure of the optical system in the fundus imaging|photography apparatus of this embodiment. FIG. 3 is a diagram showing an objective optical system according to Example 1. FIG. 3 is a block diagram showing an electrical configuration of the fundus imaging apparatus according to the first example. It is the figure which showed the objective optical system which concerns on 2nd Example. It is the figure which showed the objective optical system which concerns on 3rd Example.

  Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.

  First, an outline of a fundus imaging apparatus (hereinafter, abbreviated as “imaging apparatus”) according to the present disclosure will be described with reference to FIGS. 1 and 2. The image capturing apparatus 100 acquires an image of the fundus of the eye by scanning light on the fundus of the eye. The image of the fundus may be a front image or a tomographic image. In the imaging device 100 of the present disclosure, the scanning range of light on the fundus may be wide. For example, the light may be scanned in a range of full angle of 100° or more, and an image within the scanning range may be obtained. First, examples of the optical system according to the present embodiment will be described with reference to FIGS. 1, 2, 4, and 5.

<First embodiment>
An image pickup apparatus 100 according to the first embodiment will be described with reference to FIG. The image pickup apparatus 100 in the first example has a scanning optical system 1 shown in FIG. 1 and an objective optical system 2 shown in FIG. The scanning optical system 1 includes an SLO optical system 10, an OCT optical system 20, and a dichroic mirror 40 (optical path coupling member in the first embodiment).

<SLO optical system>
First, the SLO optical system 10 will be described. The SLO optical system 10 mainly includes an optical scanner 15 that two-dimensionally scans light (illumination light) emitted from a light source on the fundus and a detector 18, and passes through a confocal point of the fundus Er (illumination). And a light receiving optical system 10a that causes the detector to receive the light reflected by the fundus. Further, in the first embodiment, the SLO optical system 10 is a line scan type, and the detector 18 uses a line sensor. In this case, the SLO optical system 10 includes, in addition to the optical scanner 15 and the detector 18, a light source 11, a collimating lens 12, a cylindrical lens 13, a perforated mirror 14, a scan lens 16, and a condenser lens. 17 may be included. Of these, the optical scanner 15, the scan lens 16, the condenser lens 17, and the line sensor (detector) 18 constitute the light receiving optical system 10a of the SLO optical system 10 in the first embodiment.

  In the present embodiment, the light source 11 emits light having a wavelength in the infrared region (for example, laser light), for example. As the light source 11, for example, an LED light source, an SLD light source, or the like may be used. The light from the light source 11 is collimated by the collimator lens 12 and then condensed by the cylindrical lens 13. After that, the light passes through the opening of the perforated mirror 14 and is guided to the optical scanner 15. The light emitted from the light source 11 is not necessarily limited to infrared light. For example, the light may be white light, or may be combined light in which lights of two or more colors (for example, red, blue, green) are combined.

  In the first embodiment, the optical scanner 15 may be a galvanometer mirror. However, the present invention is not limited to this, and it may be replaced with any other optical scanner that operates the reflection mirror (for example, a resonant mirror, a polygon mirror, etc.), or an acousto-optic element. The optical scanner 15 is arranged at a position conjugate with the pupil of the eye E to be inspected.

  The light passing through the optical scanner 15 is converted into a light beam (that is, a telecentric light beam) parallel to the optical axis L1 of the scanning optical system 1 by the scan lens 16. That is, in the first example, the scan lens 16 is arranged so that its focus coincides with the optical scanner 15 (the turning point r3 of the optical scanner 15). As a result, the SLO optical system 10 in the present embodiment becomes the object side telecentric. The light that has passed through the scan lens 16 further passes through the dichroic mirror 40 and enters the objective optical system 2. In the first embodiment, the dichroic mirror 40 has a spectral characteristic of transmitting the light from the SLO optical system 10 and reflecting the light from the OCT optical system 20. The object-side telecentric in the present embodiment means a state in which the eye E side is telecentric when viewed from the light sources 11 and 22 side.

  The light from the SLO optical system 10 is guided to the fundus Er by the objective optical system 2 and scattered and reflected by the fundus Er. As a result, it is emitted from the pupil as the fundus reflected light and follows the optical path opposite to that at the time of light projection. Then, the fundus reflected light is emitted from the objective optical system 2 toward the scanning optical system 1, passes through the dichroic mirror 40, and enters the light receiving optical system 10a of the SLO optical system 10. In the light receiving optical system 10a, the fundus reflected light passes through the scan lens 16, is reflected by the optical scanner 15, and goes to the perforated mirror 14. Then, the fundus reflected light reflected by the perforated mirror 14 is condensed by the condenser lens 17 and received by the detector 18. In the present embodiment, the front image of the fundus is formed based on the signal output from the detector 18 based on the optical scanning of one frame by the optical scanner 15.

<OCT optical system>
Next, the OCT optical system 20 will be described. The OCT optical system 20 may include, for example, a light source 21, a light splitting unit (a coupler in the example of FIG. 1) 23, an optical scanner 27, and a detector 31. The OCT optical system 20 may further include a scan lens 29 and a reference optical system 25.

  As such an OCT optical system 20, a Fourier domain system such as an SS-OCT (Swept Source-OCT) system or an SD-OCT (Spectral domain-OCT) system may be used. Here, as an example, it is assumed that the SS-OCT (Swept Source-OCT) method is used.

  The light source 21 is a variable wavelength light source (wavelength scanning light source) that changes the emission wavelength at high speed with time. The light source 21 changes the wavelength of emitted light. The detector 31 may be, for example, a balanced detector including a light receiving element.

  The OCT optical system 20 splits the light emitted from the light source 21 into measurement light and reference light by a coupler (splitter) 23.

  The OCT optical system 20 guides the measurement light to the objective optical system 2 via the optical scanner 27. Further, the reference light is guided to the reference optical system 25. The optical scanner 27 scans the measurement light on the fundus Er in the XY directions (transverse direction). The optical scanner 27 is, for example, two galvanometer mirrors, and its reflection angle may be arbitrarily adjusted by a drive mechanism (not shown). Further, instead of the galvanometer mirror, other optical scanners that operate the reflection mirror (for example, a resonant mirror, a polygon mirror, etc.), and an acousto-optic element may be used.

  The light passing through the optical scanner 27 is converted into a light beam (that is, a telecentric light beam) parallel to the optical axis of the scanning optical system 1 by the scan lens 29. That is, in the first embodiment, the scan lens 29 is arranged so that its focus coincides with the optical scanner 27 (for example, the intermediate point r4 between the X-scan optical scanner and the Y-scan optical scanner). There is. As a result, the OCT optical system 20 in the present embodiment becomes object-side telecentric. The light that has passed through the scan lens 29 is reflected by the dichroic mirror 40 and enters the objective optical system 2.

  Like the light from the SLO optical system 10, the light from the OCT optical system 20 is guided to the fundus Er by the objective optical system 2 and is scattered and reflected by the fundus. As a result, the fundus reflected light of the measurement light is emitted toward the scanning optical system 1 by tracing the objective optical system 2 in the opposite direction to the time of projection. As a result, the fundus reflection light of the measurement light is reflected by the dichroic mirror 40 and enters the detection optical system 20a of the OCT optical system 20 (the light receiving optical system of the OCT optical system 20). That is, the fundus reflected light passes through the scan lens 29, passes through the optical scanner 27, and enters the coupler (splitter) 23. After that, the reflected light of the measurement light is combined with the reference light by the optical coupling section (coupler) 23 and interferes.

  The reference optical system 25 generates reference light that is combined with reflected light acquired by reflection of the measurement light on the fundus Er. The reference optical system 25 may be, for example, a Michelson type or a Mach-Zehnder type. In FIG. 1, the reference optical system 25 is formed by, for example, a reflection optical system (for example, a reference mirror), and guides the reference light to the detector 31 by reflecting the light from the coupler 23 by the reflection optical system. As another example, the reference optical system 25 may be formed by a transmission optical system (for example, an optical fiber), and may guide the light from the coupler 23 to the detection optical system 31 by transmitting the light without returning it.

  The imaging apparatus 100 moves at least a part of the optical member arranged in the OCT optical system 20 in the optical axis direction in order to adjust the optical path length difference between the measurement light and the reference light. For example, the reference optical system 25 has a configuration that adjusts the optical path length difference between the measurement light and the reference light by moving an optical member (for example, a reference mirror (not shown)) in the reference light path. For example, the reference mirror is moved in the optical axis direction by driving the driving mechanism 25a. The configuration for changing the optical path length difference may be arranged in the optical path of the measurement light. That is, the optical path length difference between the measurement light and the reference light may be adjusted by changing the optical path length of the measurement light.

  The interference signal light in which the measurement light and the reference light are combined is received by the detector 31. The detector 31 detects the interference signal light. Here, when the emission wavelength is changed by the light source 21, the interference signal light corresponding to this is received by the detector 31, and as a result, the interference signal light is received by the detector 31 as spectrum interference signal light. Based on the spectral interference signal output from the detector 31, a depth profile (A scan or OCT data) at one point on the fundus is formed. The depth profile is a reflection intensity distribution of measurement light in the depth direction of the fundus. By arranging the depth profiles (OCT data), two-dimensional OCT data (for example, a tomographic image of the fundus and OCT angiography) is formed.

<Objective optical system>
Next, the objective optical system 2 in the first embodiment will be described with reference to FIG. In the example of FIG. 2, the second mirror 60 is one spheroidal mirror. The second mirror 60 has two focal points r1 and r2. The eye E to be inspected is arranged at one of the focal points r2.

  In the first embodiment, the first mirror 50 is a parabolic mirror. The parabolic mirror is an example of an aspherical mirror for widening the shooting angle of view, and is not limited to this.

  Further, in the first embodiment, in addition to the first mirror 50 and the second mirror 60, correction mirror systems 71 and 72 are provided in the objective optical system 2. In the first embodiment, the correction mirror systems 71 and 72 are composed of a parabolic mirror 71 and a plane mirror 72. That is, the tilt of the image plane caused by the reflection of the fundus reflected light by the parabolic mirror that is the first mirror 50 and the spheroidal mirror that is the second mirror 60 is corrected by the correction mirror systems 71 and 72. .

  In the first embodiment, the parabolic mirror 71 has a concave surface formed symmetrically with respect to the axis of symmetry z1. The light from the scanning optical system 1 enters parallel to the axis of symmetry z1. Further, the plane mirror 72 is disposed so as to face the parabolic mirror 71 at the focus position r5 of the parabolic mirror 71. When the light from the scanning optical system 1 enters the correction mirror systems 71 and 72, the parabolic mirror 71→the plane mirror 72 (that is, the focus r5 of the parabolic mirror)→the parabolic mirror 71 in this order. And is emitted parallel to the axis of symmetry z1. Therefore, the light flux is telecentric on both sides of the correction mirror systems 71 and 72. Further, the image plane is tilted by the reflection on the correction mirror systems 71 and 72 (see the intermediate image Ic2 in FIG. 2). This tilt is performed in a direction to cancel the tilt of the image plane caused by the first mirror 50 and the second mirror 60. Note that, as shown in FIG. 2, when the tilts generated by the first mirror 50 and the second mirror 60 are non-linear, the correction mirror systems 71 and 72 preferably cancel at least the non-linear component of this tilt. ..

  The first mirror 50 in the first embodiment is a convex mirror whose convex surface faces the parabolic mirror 71 and the second mirror 60. That is, the first mirror 50 has a negative power. The first mirror 50 is arranged eccentrically (off-axis) with respect to the parabolic mirror 71. That is, the axis of symmetry z2, which is the axis of symmetry of the first mirror 50 (that is, the target axis of the parabolic surface), is parallel to the axis of symmetry z1 of the parabolic mirror 71 with a gap. For this reason, the parabolic mirror 71 irradiates the first mirror 50 with light rays parallel to the axis of symmetry z2. Further, the first mirror 50 is arranged such that one of the two focal points r1 and r2 of the second mirror 60, which is a spheroidal mirror, has a focal point r1 which is one of the focal points r1 and r2. Therefore, when light is irradiated from the parabolic mirror 71 to a certain position of the first mirror 50, the light is reflected on the straight line connecting the irradiation position and the focal point r1. That is, the light traveling from the first mirror 50 to the second mirror 60 revolves around the focal point r1 of the spheroidal mirror, which is the second mirror, as the optical scanner 15 (or the optical scanner 27) is driven. In other words, the turning point of the light traveling toward the second mirror 60 via the optical scanner 15 (or the optical scanner 27) is formed at the focal point r1 by the first mirror 50. In the first embodiment, since the light is reflected by the mirror surface of the first mirror 50, the swing angle of the light traveling from the first turning point r1 to the second mirror is incident on the first mirror 50 from the scanning optical system 1. Increased with respect to the swing angle of light. For this reason, in the first embodiment, the swing angle of the light incident on the first mirror 50 is suppressed more than the swing angle of the light incident on the second mirror 60. As an example, as shown in FIG. 1, telecentric light may be incident. In this case, it is assumed that the swing angle=0.

  Further, due to the general characteristics of the spheroidal mirror that is the second mirror 60, the light passing through the focal point r1 and reflected by the mirror surface of the spheroidal mirror is guided to the other focal point r2. Therefore, the turning point (second turning point) of the light reflected by the second mirror 60 is formed at the other focus r2 (that is, the position of the anterior segment of the eye E to be examined). The swing angle of light at this turning point (focus point r2) is determined by the swing angle at the focus point r1 and the shape of the mirror surface of the second mirror 60. The second mirror 60 may have a shape that makes the swing angle at the focus r2 larger than the swing angle at the focus r1. However, it is not necessarily limited to this.

  As described above, in the first embodiment, light is incident from the scanning optical system 1 to the objective optical system 2 (more specifically, the parabolic mirror 71) with telecentricity (swing angle=0), and the fundus It becomes possible to photograph a wide range of Er. In the first embodiment, the optical coupling member 40 (dichroic mirror 40) for coupling the optical paths of the SLO optical system 10 and the OCT optical system 20 is telecentric with each of the SLO optical system 10 and the OCT optical system 20. The front image and the tomographic image having a wide angle of view can be satisfactorily obtained because they are arranged at the positions where

  Here, since the second mirror 60 is a spheroidal mirror, it causes asymmetrical image plane distortion (for example, trapezoidal distortion) in the fundus reflected light. On the other hand, in the present embodiment, the image plane distortion is suppressed by arranging the first mirror 50 so as to be inclined with respect to the second mirror 60. That is, the first mirror 50 is arranged so as to be inclined with respect to the light beam passing through the center of the optical path between the first mirror 50 and the second mirror 60. The correction amount of the image plane distortion changes according to the tilt amount of the first mirror 50. The tilt amount of the first mirror 50 may be set, for example, so that the remaining image plane distortion is axially symmetric.

<Second embodiment>
Next, a second embodiment will be described with reference to FIG. In the second embodiment, the same components as those in the first embodiment are designated by the same reference numerals as those in the first embodiment, and detailed description will be omitted.

  The second embodiment is different from the first embodiment in a part of the scanning optical system 1 and the objective optical system 2. For example, in the first example, each of the SLO optical system 10 and the OCT optical system 20 was telecentric on the object side, but in the second example, the scanning optical system 1 (more specifically, the SLO optical system 10). The light incident on the objective optical system 2 from the OCT optical system 20) is swung around a turning point at a finite distance from the objective optical system 2. In the second embodiment, for convenience of description, the light from the SLO optical system 10 when entering the objective optical system 2 is rotated about the turning point r3, and OCT optics when entering the objective optical system 2 is used. It is assumed that the light from the system 20 is turned around the turning point r4.

  The objective optical system 2 of the second embodiment has a parabolic mirror 171 between the first mirror 50 and the optical scanners 15 and 27. The parabolic mirror 171 is a concave mirror arranged so that its focal point coincides with the turning points r3 and r4. Therefore, on the object side of the parabolic mirror 171, the light beam is telecentric. Furthermore, in the second embodiment, the target axis of the mirror surface of the parabolic mirror 171 (that is, the symmetry axis of the parabolic surface, not shown) is parallel to the symmetry axis z2 of the mirror surface of the first mirror 50. It is arranged. Therefore, similarly to the first embodiment, the first mirror 50 is irradiated with a light beam parallel to the axis of symmetry z2 from the optical scanner 15, 27 side (that is, the parabolic mirror 171). As a result, the light traveling from the first mirror 50 to the second mirror 60 is swiveled around the first swivel point r1 where the focal point of the first mirror 50 and the focal point of the second mirror 60 overlap. Then, the light is further reflected by the second mirror 60, so that the light is swung with the other focus r2 of the spheroidal mirror as the turning point. In this way, also in the second example, the swing angle of the light incident from the scanning optical system 1 to the objective optical system 2 (more specifically, the parabolic mirror 171) is suppressed and the fundus Er of the fundus Er is reduced. It becomes possible to scan the light favorably over a wide range. As a result, it is possible to prevent the image quality of the image of the fundus from being partially deteriorated due to the incident angle dependency of the optical coupling member 40 (dichroic mirror 40).

  According to the inventor of the present invention, when the optical system of the first embodiment and the optical system of the second embodiment are designed under certain conditions, the second embodiment has higher imaging performance. It was confirmed to play.

  By the way, the parabolic mirror 171 provided in place of the correction optical systems 71 and 72 of the first embodiment does not correct the inclination of the image plane. On the other hand, in the second embodiment, in order to suppress the inclination of the image plane in at least the SLO optical system 10, at least the detector 18 which is arranged to be inclined with respect to the optical axis of the light receiving optical system 10a is provided. Good. In addition, in addition, either the lens 12 or the lens 13 in the SLO optical system 10 may be tilted with respect to the optical axis. In the second embodiment as described above, the tilt amount of the detector 18 is adjusted so as to have a Scheimpflug relationship with the fundus Er and the objective optical system 2. As a result, it is possible to prevent the image quality from being deteriorated due to the inclination of the image plane (that is, the focus being different depending on the scanning position).

<Third embodiment>
Next, a third embodiment will be described with reference to FIG. In the third embodiment, the same components as those in the first embodiment are designated by the same reference numerals as those in the first embodiment, and detailed description will be omitted. The third example shows an example of a configuration in which a mirror system is not included between the first mirror 50 and the scanning optical system 1. In the third embodiment, a part of the scanning optical system 1 and the objective optical system 2 is different from that of the first embodiment. For example, in the first example, each of the SLO optical system 10 and the OCT optical system 20 was telecentric on the object side, but in the third example, the scanning optical system 1 (more detailed) as in the second example. In the above, the light incident on the objective optical system 2 from the SLO optical system 10 and the OCT optical system 20) is swung around a turning point at a finite distance from the objective optical system 2.

  In the third embodiment, the first mirror 50 is one hyperboloidal mirror (one of a pair of hyperboloids). The hyperboloidal mirror is an aspherical mirror that contributes to widening the angle in the third embodiment. The second mirror 60 may be a spheroidal mirror as in the first embodiment. The hyperbolic mirror that is the first mirror 50 is arranged so that the virtual image side focus (focus on the convex surface side) coincides with the turning points r3 and r4. The first mirror 50 is arranged so that the focal point on the real image side (the focal point on the concave surface side) coincides with one focal point of the second mirror 60. That is, the first mirror 50 is irradiated with the light emitted from the focus on the virtual image side (the hyperboloid side that pairs with the first mirror 50). As a result, due to the general characteristics of the hyperboloidal mirror, the reflected light reflected by the first mirror 50 is driven by the optical scanner 15 (or the optical scanner 27) and is focused on the real image side of the first mirror 50. It turns around r1. Here, the focal point r1 is also the focal point of the second mirror 60 which is a spheroidal mirror, so that the turning point of the light reflected by the first mirror 50 is the focal point r1 of the spheroidal mirror, depending on the arrangement of the first mirror 50. Formed in. In the third embodiment, since the light is reflected by the mirror surface of the first mirror 50, the swing angle of the light traveling from the first turning point r1 to the second mirror 60 is incident on the first mirror 50 from the scanning optical system 1. It is increased with respect to the swing angle of the light. Then, the light reflected by the second mirror 60 is turned with another focus r2 of the second mirror 60 as a turning point. In this way, also in the third example, the swing angle of the light incident from the scanning optical system 1 to the objective optical system 2 (more specifically, the first mirror 50) is suppressed, and the wide range of the fundus Er is obtained. In, it becomes possible to scan the light satisfactorily.

  As shown in FIG. 5, the first mirror 50 may be tilted with respect to the second mirror 60. In order to correct the inclination of the image plane that occurs in this case, for example, the detector 18 or the like of the SLO optical system 10 may be arranged to be inclined with respect to the optical axis.

<Control system>
Next, a control system of the image capturing apparatus 100 will be described with reference to FIG. The control unit 70 is a processor (for example, a CPU) that controls the entire apparatus of the image capturing apparatus 100.

  In the first embodiment, a memory 72, a monitor 75, etc. are electrically connected to the control unit 70. The light sources 11, 21, the optical scanners 15, 27, the detectors 18, 31, the drive mechanism 25a, etc. are electrically connected to the control unit 70.

  The memory 72 stores various control programs and fixed data. Further, the memory 72 may store images captured by the image capturing apparatus 100, temporary data, and the like.

  In this embodiment, the control unit 70 also serves as an image processing unit. For example, the received light signals from the detector 18 and the detector 31 are input to the control unit 70, respectively. The control unit 70 forms a front image of the fundus Er based on the signal from the detector 18. The control unit 70 also forms a tomographic image of the fundus Er based on the signal from the detector 31. At this time, the control unit 70 drives the light from the light source 11 and the light from the light source 21 simultaneously and independently of the optical scanner 15 and the optical scanner 27 to thereby obtain a front image and a tomographic image. May be acquired in parallel. The front image and the tomographic image obtained at the same time may be simultaneously displayed on the monitor 75 as a moving image. In the first embodiment, since the optical scanner 15 of the SLO optical system 10 and the optical scanner 27 of the OCT optical system 20 are provided independently, the control unit 70 makes the front image and the tomographic image different from each other. It may be acquired at the frame rate.

<Operation of the device when acquiring a tomographic image>
The objective optical system 2 of each of the above-described embodiments is in front of the eye E to be inspected via a mirror system (for example, the first mirror 50 and the second mirror 60) arranged between the eye E and the optical scanner 27. This is an objective mirror system that forms a turning point (turning point r2 in the above embodiments) that is turned along with the operation of the optical scanner 27 in the eye (for example, pupil position). In the objective optical system 2, for example, in each of the above-described embodiments, the second mirror 60 immediately in front of the eye E to be inspected is a spheroidal mirror, and one of the two focal points r1 and r2 of the spheroidal mirror has The turning point r2 is formed. Of the two focal points of the spheroidal mirror, the light entering from one of the focal points toward the mirror surface and guided to the other focal point has a constant optical path length between the two focal points. However, in each of the above-described embodiments, since the mirrors such as the first mirror 50 are arranged between the optical scanner 27 and the second mirror 60, the measurement light from the optical scanner 27 to the second turning point r2 is changed. The distance may vary depending on the scanning position of the optical scanner 27.

  Further, in each of the above-described embodiments, the optical path length of the measurement light from the second turning point r2 (pupil position) to the surface of the fundus Er is different for each scanning position. That is, the distance of the measurement light from the second turning point r2 to the fundus Er may differ depending on the scanning position of the optical scanner 27 due to the curvature of the fundus.

  In this way, the distance of the measurement light from the optical scanner 27 to the eye E to be examined may be different at each scanning position of the optical scanner 27. That is, it is conceivable that the optical path length difference between the measurement light and the reference light changes depending on the distance of the measurement light from the optical scanner 27 to the eye E at each scanning position of the optical scanner 27.

  In this state, when the depth profile (OCT data) is obtained based on the signal from the detector 31, the depth position of the region in the eye E where the depth profile (OCT data) is acquired is the optical scanner 27. It may be different for each scanning position. Further, depending on the scanning position, there is a possibility that the range in which the sensitivity of the detector 31 is high and the range in which the interference between the measurement light and the reference light occurs are relatively greatly deviated due to the large optical path length difference.

  On the other hand, the control unit 70 corrects the change in the optical path length difference between the measurement light and the reference light depending on the distance of the measurement light from the optical scanner 27 to the eye E at each scanning position of the optical scanner 27.

  Here, the change in the optical path length difference between the measurement light and the reference light may be corrected on the data (by processing the OCT data). For example, the control unit 30 may correct the position information in the depth direction of the OCT data when the control unit 30 acquires the OCT data based on the signal from the detector 31.

  Further, the control unit 30 may correct the relative depth position between the OCT data at each scanning position when arranging the plurality of OCT data to form the two-dimensional OCT data.

  As a result of such processing, OCT data (or two-dimensional OCT data) can be satisfactorily obtained.

  Further, the change in the optical path length difference between the reference light and the measurement light may be optically corrected. For example, the correction may be performed by driving and controlling the optical path length adjusting mechanism 25a (driving mechanism) according to the scanning position of the optical scanner 27. As described above, the drive mechanism 25a displaces the optical member (for example, the mirror) arranged on the optical path of the reference light (or the optical path of the measurement light), so that the difference in optical path length between the measurement light and the reference light. May be adjusted. For example, in this embodiment, the drive mechanism 25a changes the optical path length of the reference light in accordance with the change of the optical path length of the measurement light accompanying the operation of the optical scanner 27. As a result, a signal based on the interference between the measurement light and the reference light is easily detected in the range where the detector 31 has a high sensitivity, and OCT data (or two-dimensional OCT data) can be satisfactorily obtained. In this case, the range in which the difference in optical path length changes is suppressed so that the signal based on the interference between the measurement light and the reference light is detected in the range in which the sensitivity of the detector 31 is relatively high, regardless of the scanning position. It is only necessary that the drive mechanism 25a is not necessarily driven and controlled so that the optical path length difference between the measurement light and the reference light is constant (for example, zero) at each scanning position.

  Here, the control unit 70 corrects the change in the optical path length difference between the measurement light and the reference light in consideration of at least the change in the distance (optical path length) of the measurement light from the optical scanner 27 to the second turning point r2. .. Further, the control unit 70 further considers the change in the optical path length of the measurement light at each scanning position due to the curvature of the fundus (that is, the change in the optical path length of the measurement light from the second turning point r2 to the fundus Er), Correction may be performed. Here, the correspondence relationship between the optical path length of the measurement light from the optical scanner 27 to the second turning point r2 and each scanning position of the optical scanner 27 is determined by the design of the optical system. The correspondence between the optical path length of the measurement light from the second turning point to the fundus Er and each scanning position of the optical scanner 27 is also roughly determined by the design of the optical system (mainly the swing angle at the second turning point). Determined.

  Therefore, for example, the correction amount for correcting the change in the optical path length difference (for example, the change amount of the optical path length or the correction amount of the position information in the depth direction in the OCT data) corresponds to each scanning position of the optical scanner 27. The attached correction table may be prepared in advance in the memory 72. Then, the control unit 70 may perform the correction process of the change in the optical path length difference using this correction table. The correction amount in such a table is a value that takes into consideration the change in the optical path length of the measurement light from at least the optical scanner 27 to the second turning point r2. Further, it may be a value that takes into consideration the change in the optical path length from the second turning point r2 to the fundus E2. Such a correspondence relationship between the optical path length difference and the correction amount (in other words, a correspondence relationship between the scanning position and the correction amount) may be obtained in advance by, for example, simulation and calibration.

  In the above embodiment, the optical scanner 27 includes two optical scanners. That is, a first optical scanner (for example, an X galvano scanner) that performs main scanning of the measurement light and a second optical scanner (for example,) that sub-scans the measurement light in a direction intersecting with the main scanning direction are provided. include. When the main scan is performed in the depth direction of the paper surface of each figure and the sub-scan is performed in a direction that intersects the depth direction of the paper surface, the change in the optical path length of the measurement light ( Specifically, it is possible to employ the objective optical system 2 in which the change in the optical path length from the optical scanner 27 to the second turning point r2) occurs. For example, the objective optical system 2 as described above can be realized by using a concave mirror and a convex mirror formed of a rotating curved surface such as a spheroidal mirror and a rotary parabolic mirror as in this embodiment.

  With respect to such an objective optical system 2, the control unit 30 may acquire two-dimensional OCT data in a plurality of scan lines by raster-scanning the measurement light. That is, the control unit 30 drives and controls the optical scanner 27 to acquire a plurality of two-dimensional OCT data acquired by the main scanning in scan lines in different sub-scanning directions. Then, the drive mechanism 25a may be drive-controlled according to the scanning position of the second scanner. That is, the drive mechanism 2 may be driven according to the scanning position of the second scanner to correct the change in the optical path length difference between the reference light and the measurement light.

  In this case, the optical path length difference between the measurement light and the reference light may change due to the sub scanning, but the sub scanning speed is slower than that in the main scanning. Therefore, it is possible to suppress a temporal change in the optical path length difference. Therefore, the drive mechanism 25a can be driven so that the change in the optical path length difference between the reference light and the measurement light is corrected more reliably. As a result, a plurality of two-dimensional OCT data can be satisfactorily acquired.

  Although the above description has been given based on the embodiment, the present disclosure is not limited to the above embodiment, and various changes may be made.

  For example, in the above-described embodiment, the scanning optical system 1 has the optical paths of the two imaging optical systems (the SLO optical system 10 and the OCT optical system 20 in the above-described embodiment) each having an optical scanner. Described when combined by. However, the scanning optical system 1 is not necessarily limited to this, and the optical paths of the imaging optical system and the irradiation optical system that emits light for treatment or stimulation may be combined by the optical path combining unit 40. .. Here, the photographing optical system drives the first optical scanner to scan the light from the first light source for photographing to scan the fundus and to detect the fundus reflected light of the light from the first light source. And a container may be provided. In this case, for example, either the SLO optical system 10 or the OCT optical system 20 in the above embodiment may be used as the imaging optical system. On the other hand, the light emitted to the eye E by the irradiation optical system may be, for example, a therapeutic laser for performing photocoagulation on the fundus. Further, it may be stimulating light for visual field inspection. Of course, the light for treatment or stimulation is not limited to this. Such an irradiation optical system may include at least a second optical scanner that determines the irradiation position of the light on the fundus by deflecting the light from the second light source that emits the therapeutic or stimulating light. Good. Such an irradiation optical system may be replaced with either the SLO optical system 10 or the OCT optical system 20 in the above embodiment, and the second optical scanner may be replaced with any of the optical scanners 15, 27 in the above embodiment. May be arranged.

2 Objective optical system 20 OCT optical system 21 Light source 25a Optical path length adjusting mechanism 27 Optical scanner 31 Detector 70 Control unit 72 Memory 100 Fundus imaging device r2 Second turning point E Eye E to be examined Er fundus

Claims (2)

An OCT optical system that has an optical scanner that scans the measurement light from the light source on the fundus of the eye to be inspected, and detects the interference between the reference light and the measurement light reflected by the fundus with a detector.
An objective mirror system that forms a swivel point swiveled with the operation of the optical scanner in the anterior segment of the subject's eye via a mirror system arranged between the subject's eye and the optical scanner,
Acquisition means for obtaining fundus OCT data by processing the signal from the detector;
Have a, and correcting means for correcting the variation of the optical path length difference between the measurement light and the reference light from the optical scanner according to the distance of the measurement light to the subject's eye at each scanning position of the optical scanner,
The correction means corrects a relative depth position between OCT data at each scanning position by performing correction processing on position information in the depth direction in each of the plurality of OCT data. Including,
A fundus imaging apparatus that forms two-dimensional OCT data based on the OCT data after the correction processing . Said correction means further includes a drive mechanism for correcting the optical path length difference, and controls the drive mechanism in response to the scanning position, corrects the change in the optical path length difference, the control means The fundus imaging apparatus according to claim 1 , further comprising: