JP2019013399A - OCT apparatus and optical attachment - Google Patents

Abstract

To provide an apparatus for acquiring excellent OCT data on the ocular fundus through an optical attachment.SOLUTION: An OCT apparatus includes an interference optical system, an optical scanner 156, an objective optical system 158, and an optical attachment 600. The objective optical system 158 is arranged between the optical scanner 156 and an eye E to be examined, and guides a measurement light passing through the optical scanner 156 to a first condensing surface without causing the measurement light to intersect with an optical axis of a measurement optical path, and condenses the measurement light on the first condensing surface. The optical attachment 600 is inserted into the measurement optical path between the eye E to be examined and the objective optical system 158, so that the measurement light passing through the objective optical system 158 is bent to an optical axis side, and forms a revolving point P3 of the measurement light at a conjugate position with the optical scanner 156 with respect to the objective optical system 158 and the optical attachment 600. Also, the measurement light passing through the revolving point P3 is condensed on a second condensing surface.SELECTED DRAWING: Figure 25

Description

  The present disclosure relates to an OCT apparatus and an optical attachment that is inserted into and removed from a measurement optical path of the OCT apparatus.

  2. Description of the Related Art Conventionally, an OCT apparatus that scans measurement light on a tissue of an eye to be inspected by an optical scanner and processes spectrum interference signals caused by the return light of the measurement light from the tissue and the reference light to acquire OCT data is known. ing. As a kind of OCT apparatus, an apparatus that switches an acquisition range of OCT data in an eye to be examined by inserting / removing an optical attachment to / from an optical path of measurement light has been proposed.

  For example, in Patent Document 1, the apparatus main body has an optical system applied to the acquisition of OCT data in the fundus, and an optical attachment is interposed between the apparatus main body and the eye to be examined. An apparatus for switching to an optical system is disclosed. Specifically, the optical system of the apparatus main body is formed on the fundus with the swivel point as the center by forming the swivel point of the measurement light by the objective optical system of the apparatus main body, and the swivel point is located in the anterior eye part of the eye to be examined. The measuring light is scanned with. When the optical attachment is present, the optical attachment refracts the measurement light emitted from the objective optical system of the apparatus main body and emits the light toward the eye to be examined as a light beam substantially parallel to the optical axis. As a result, the measurement light is scanned over a wide range of the anterior segment.

  Further, for example, in Patent Document 2, the apparatus main body has an optical system that scans the fundus, and an optical attachment is interposed between the apparatus main body and the eye to be examined, so that the scanning range of measurement light is expanded. Is disclosed. When the optical attachment is interposed, the second turning point is formed when the optical attachment largely bends the light beam passing through the turning point by the objective optical system of the apparatus main body to the optical axis side. When the second turning point is located in the anterior segment of the eye to be examined, the measurement light is scanned on the fundus around the second turning point.

JP 2011-147612 A JP 2016-123467 A

  However, under the premise of acquiring OCT data in the anterior segment via an optical attachment as in the device of Patent Document 1, there are various limitations on the design of the optical system of the device body. As an example of the limitation, it is difficult to widen the fundus scanning range of the apparatus main body.

  Further, in the apparatus of Patent Document 2, by design, the optical path length between the turning point formed by the objective optical system of the apparatus body and the second turning point where the measurement light passing through the optical attachment is turned is set. , Easy to be long. As a result, it is necessary to perform OPL adjustment in accordance with the insertion / removal of the optical attachment, and it is conceivable that the configuration for that purpose is likely to be enlarged.

  In addition, when the scanning range of the measurement light is expanded using an optical attachment, it is necessary to consider various aberration components affecting the OCT data, eye curvature, and the like.

  An object of the present disclosure is to obtain OCT data of a good fundus via an OCT apparatus and an optical attachment that can solve at least one of the problems of the related art.

  An OCT apparatus according to a first aspect of the present disclosure includes an optical splitter for dividing light from an OCT light source into a measurement optical path and a reference optical path, and measurement light guided to the subject's eye via the measurement optical path; An OCT optical system that detects a spectral interference signal with reference light from the reference optical path, and light that is arranged on the measurement optical path, deflects the measurement light from the optical splitter, and scans on the tissue of the eye to be examined A scanner is disposed between the optical scanner and the eye to be examined on the measurement optical path, and the measurement light passing through the optical scanner reaches the first light collection surface without intersecting the optical axis of the measurement optical path. An objective optical system for condensing the measurement light on the first condensing surface, and an optical attachment inserted into and removed from the measurement optical path between the objective optical system and the eye to be examined. The optical attachment comprises a front By being inserted into the measurement optical path, the measurement light that has passed through the objective optical system is bent toward the optical axis, and the swivel point of the measurement light is set at a position conjugate with the optical scanner with respect to the objective optical system and the optical attachment. At the same time, the measurement light passing through the turning point is condensed on the second condensing surface.

  An OCT apparatus according to a second aspect of the present disclosure includes an optical splitter for dividing light from an OCT light source into a measurement optical path and a reference optical path, and measurement light guided to the eye to be examined via the measurement optical path; An OCT optical system that detects a spectral interference signal with reference light from the reference optical path, and light that is arranged on the measurement optical path, deflects the measurement light from the optical splitter, and scans on the tissue of the eye to be examined A scanner, an objective optical system disposed between the optical scanner and the eye to be examined on the measurement optical path, and a lens inserted into and removed from the measurement optical path between the objective optical system and the eye to be examined An attachment, and the lens attachment bends the measurement light that has passed through the objective optical system toward the optical axis, and the measurement light is in a position conjugate with the optical scanner with respect to the objective optical system and the optical attachment. A lens having a positive power for forming the pivot point, the asymmetry of the aberration, and includes an aberration correcting lens for correcting at least one of curvature, the.

  An optical attachment according to a third aspect of the present disclosure includes a light splitter for dividing light from an OCT light source into a measurement optical path and a reference optical path, and measurement light guided to the eye to be examined via the measurement optical path An OCT optical system that detects a spectral interference signal with reference light from the reference optical path, an optical scanner that deflects the measurement light and scans it on the tissue of the eye to be examined, and the optical scanner and the eye to be examined An objective that is arranged and guides the measurement light that has passed through the optical scanner to the first light collection surface without intersecting the optical axis of the measurement light path, and collects the measurement light on the first light collection surface. An optical attachment that is attached to and detached from an inspection window of an apparatus main body of an OCT apparatus having an optical system, has one or more lenses, and is attached to the inspection window, whereby measurement through the objective optical system Fold light toward the optical axis In addition, a swivel point of the measurement light is formed at a position conjugate with the optical scanner with respect to the objective optical system and the optical attachment, and the measurement light passing through the swivel point is condensed on the second light collection surface. Let

  An optical attachment according to a fourth aspect of the present disclosure includes a light splitter for dividing light from an OCT light source into a measurement optical path and a reference optical path, and measurement light guided to the eye to be examined via the measurement optical path; An OCT optical system that detects a spectral interference signal with reference light from the reference optical path, an optical scanner that deflects the measurement light and scans it on the tissue of the eye to be examined, and the optical scanner and the eye to be examined An objective that is arranged and guides the measurement light that has passed through the optical scanner to the first light collection surface without intersecting the optical axis of the measurement light path, and collects the measurement light on the first light collection surface. An optical attachment that is attached to and detached from an inspection window of an apparatus main body of an OCT apparatus having an optical system, wherein the measurement light that has passed through the objective optical system is bent toward the optical axis, and the light is related to the objective optical system and the optical attachment. Comprising a lens having a positive power for forming the pivot point of the measurement light to the scanner and a position conjugate with the asymmetry of the aberration, and the aberration correcting lens for correcting at least one of curvature, the.

  According to the present disclosure, it is possible to solve at least one problem of the prior art and obtain good fundus OCT data via at least an optical attachment.

  An example of an embodiment of the present disclosure will be described based on the drawings. 1 to 25 are diagrams according to examples of the present embodiment. In addition, the items classified by <> below can be used independently or in association with each other.

  The OCT apparatus according to this embodiment includes an OCT optical system, and acquires OCT data of an eye to be examined by processing a spectrum interference signal output from a detector of the OCT optical system. In this case, the OCT optical system may be, for example, a Fourier domain OCT optical system (SS-OCT optical system, SD-OCT optical system). The OCT optical system uses light from the OCT light source as a measurement optical path and a reference optical path. And a spectral interference signal between the measurement light guided to the eye to be examined via the measurement optical path and the reference light from the reference optical path may be detected.

  The OCT apparatus includes an optical scanner and an objective optical system on a measurement optical path. The optical scanner is a device for deflecting the measurement light from the optical splitter and scanning it on the tissue of the eye to be examined. It is preferable that the measurement light can be scanned two-dimensionally on the tissue by the optical scanner. A plurality of optical scanners may be provided. In this case, two or more optical scanners that scan the measurement light in one direction may be provided in combination. Specific examples of such an optical scanner include a galvano mirror, a resonant mirror, a polygon mirror, an acoustooptic device, and a MEMS scanner. A two-degree-of-freedom optical scanner (a device capable of two-dimensional scanning alone) may be applied to this embodiment.

  The objective optical system is disposed between the optical scanner and the eye to be examined on the measurement optical path. The objective optical system guides the measurement light that has passed through the optical scanner to the first light collection surface without intersecting the optical axis of the measurement optical path. At this time, the measurement light is collected on the first light collection surface. For example, the objective optical system may be a telecentric optical system. In this case, the focal point in the objective optical system substantially coincides with the turning position of the measurement light by the optical scanner, so that the light beam that has passed through the objective optical system is emitted to the eye side as a telecentric light beam. Here, the “telecentric light beam” is not limited to a light beam whose principal ray is completely parallel to the optical axis, but may be a light beam whose chief ray is slightly inclined with respect to the optical axis. . Of course, the objective optical system is not limited to the telecentric optical system as described above.

  The objective optical system has a positive power (refractive power) as a whole, whereby the measurement light that has passed through the objective optical system is condensed (converged) on a plane or curved surface that intersects the optical axis. This plane or curved surface is the first light collecting surface. The working distance (distance from the end of the device to the cornea) Wd when obtaining the anterior segment OCT data is preferably set based on the position of the first light collection surface. That is, when the eye to be examined is located in the vicinity of the first light collection surface or in the vicinity thereof, the OCT data of the anterior eye part can be obtained satisfactorily, and the positional relationship between the eye to be examined and the device in that case The working distance may be set.

  In the present embodiment, the OCT optical system, the optical scanner, and the objective optical system belong to the apparatus main body of the OCT apparatus. Each part may be accommodated in the housing of the apparatus main body. This housing may be provided with an inspection window on the side surface on the eye side to be examined.

<Optical attachment>
In the present embodiment, the OCT apparatus includes an optical attachment. The optical attachment may be detachable on the measurement optical path between the objective optical system and the eye to be examined. The optical attachment may be a separate body from the main body of the OCT apparatus. At this time, the optical attachment is inserted into and removed from the measurement optical path by being attached to and detached from the inspection window of the housing in the apparatus main body. The optical attachment may be completely separable from the main body of the OCT apparatus. In addition, the optical attachment barrel may be attached in advance to the apparatus body of the OCT apparatus with a hinge or the like, and the optical attachment can be attached to and detached from the inspection window by rotating the optical attachment by the hinge. It may be.

  The optical attachment is inserted into the measurement optical path to bend the measurement light from the objective optical system toward the optical axis. Thereby, the turning point of the measurement light is formed at a position conjugate with the optical scanner with respect to the objective optical system and the optical attachment. Further, the measurement light that has passed through the turning point is collected on the second light collection surface. The working distance when obtaining fundus OCT data is preferably set based on the position of the turning point. That is, when the position of the anterior eye part (more preferably, the pupil) coincides with the turning point, the measurement light easily reaches the fundus without vignetting due to the iris. Therefore, the working distance may be set based on the positional relationship between the eye to be examined and the device when the anterior eye portion (more preferably, the pupil) coincides with the turning point. Moreover, it is preferable that the 2nd condensing surface is formed in the vicinity of the fundus.

  As described above, the OCT apparatus in the present embodiment is switched to the optical system applied to the acquisition of OCT data in the fundus by inserting / removing the optical attachment to / from the optical system applied to the acquisition of OCT data in the anterior segment. The acquisition range of OCT data can be switched by a novel switching method.

  Here, in the conventional optical system as shown in Patent Document 2, the pupil image is relayed in the optical attachment. Specifically, in the optical attachment, a Fourier transform image of the pupil is generated once, and this is further Fourier transformed to return it to the pupil again. As a result, the size of the optical attachment tends to increase. If the optical system is designed to have a large power in order to suppress the size of the optical system, there is a problem that aberrations that affect the OCT data are likely to occur in each part.

  In the OCT apparatus according to the present embodiment, a Fourier transform image of the pupil has already been generated by the optical system from the optical splitter to the objective optical system. Therefore, the optical attachment only needs to convert the Fourier transform image into a pupil image, that is, the number of times of Fourier transform between the pupil and the image by the optical attachment can be made one. Therefore, it becomes easy to make the optical attachment compact. As a result, aberration is easily suppressed when the desired power is provided. For this reason, according to the OCT apparatus in the present embodiment, it is easy to design such that the OCT data acquisition range in the fundus is wide when the optical attachment is inserted. For example, an OCT apparatus having a scanning range of φ80 ° or more on the fundus can be realized (Note that the “scanning range” here has a large angle of view depending on the optical system arranged on the eye side of the eye relative to the optical scanner. Sa).

  Further, for example, the optical attachment has a second solid angle indicating the scanning range of the measurement light in the vicinity of the turning point larger than the first solid angle indicating the scanning range of the measurement light in the vicinity of the optical scanner. The light beam may be bent to the optical axis side between the objective optical system and the eye to be examined.

  The optical attachment may be a refractive system (lens system), a reflective system (mirror system), or a combination of both.

<Optical attachment by lens system>
Here, as an example, a detailed configuration when the optical attachment is a lens attachment (that is, a refractive optical attachment) will be described. In this case, the optical attachment includes one or more lenses.

  The optical attachment may have two types of lens groups, a first lens group and a second lens group. At this time, they are arranged in the order of the first lens group → the second lens group from the objective optical system toward the eye to be examined. It is preferable that the first lens group has negative power and the second lens group has positive power. That is, since the light beam height of the measurement light in the optical attachment is maximized at a position closer to the eye to be examined, it is easy to ensure a longer working distance. This is the same as the back focus expansion by the retrofocus type as seen in, for example, US Pat. No. 4,867,555.

  Each lens included in the optical attachment may be a spherical lens. Of course, some or all of them may be aspherical lenses.

<Reducing aberrations with the optical attachment aberration correction lens>
The optical attachment may have an aberration correction lens. The aberration correction lens may be a lens that suppresses the occurrence of an aberration having a large influence on the OCT data in the fundus due to the optical attachment. Examples of aberrations that have a large effect on OCT data at the fundus include asymmetrical aberrations such as coma and asphalt, and curvature of field. In addition, the curvature of field for approximating the shape (mainly curvature) of the condensing surface (second condensing surface) formed by the measurement light via the optical attachment to the curved fundus surface. You may have a component. In other words, the aberration correction lens may have a field curvature component in consideration of the curvature on the fundus surface. The difference between the second condensing surface and the fundus surface is larger in the peripheral portion, and the image formation is worsened, which is likely to cause a problem in widening the scanning range. On the other hand, the aberration correction lens has a field curvature component for bringing the shape (mainly the curvature) of the condensing surface (second condensing surface) formed by the measurement light via the optical attachment. The above divergence can be suppressed, and it becomes easy to obtain good OCT data over a wide range of the fundus.

  The aberration correction lens may be included in the first lens group or may be included in the second lens group. Further, at least one may be arranged in each of the first lens group and the second lens group.

  A cemented lens can be applied to the aberration correction lens. The cemented lens is obtained by bonding a lens having a negative power (concave lens) and a lens having a positive power (convex lens). In the case where each lens in the first lens group and the second lens group is constituted by a spherical lens, the cemented lens is suitable for suppressing aberrations that have a large influence on the OCT data exemplified above.

  Note that the working distance Wd when the optical attachment is not attached (the working distance when obtaining the OCT data of the anterior segment) is a positional relationship such that the focusing point of the measurement light does not coincide with the surface of the lens. Is placed.

  If the first lens group includes a cemented lens, the range of the distance from the objective optical system to the first cemented lens is determined by the following expression to reduce the influence of reflection by the lens surface. In addition, it is preferable.

Z <Wd <Z + D
Here, Z is a distance from an optical surface (for example, a lens surface) closest to the eye to be examined in the objective optical system of the apparatus body to a lens surface closest to the objective optical system in the first cemented lens. D is the thickness on the optical axis L in the first cemented lens.

  In addition, when a cemented lens is provided in the second lens group, the second lens group further includes a lens that bends the measurement light toward the optical axis at a position where the light beam height is highest with respect to the optical axis. You may have. This lens may have a major positive power in the optical attachment. Since the lens for reducing aberrations and the lens for bending light rays toward the optical axis are separate, it is easy to achieve good imaging performance at an expected angle of view. Of course, an aspheric lens or the like may be used for the purpose of correcting aberrations while having the main positive power. Further, it is preferable that the lens that bends the measurement light toward the optical axis is arranged closer to the eye to be examined than the cemented lens. That is, since the light beam height of the measurement light becomes maximum at a position closer to the eye to be examined, a longer working distance can be secured. This is the same as the back focus expansion by the retrofocus type as seen in, for example, US Pat. No. 4,867,555.

  The cemented lens may have a meniscus shape in which the front surface of the lens and the rear surface of the lens are convex toward the eye to be examined. By adopting such a meniscus shape, it becomes close to a concentric configuration, and the generation of asymmetrical aberrations such as coma and asphalt is suppressed.

  When a cemented lens is provided in the second lens group, a lens having negative power in the cemented lens may be formed of a material having a low refractive index with respect to a lens having positive power. As a result, the occurrence of field curvature due to the measurement light being largely refracted toward the optical axis by the second lens group is reduced. In this case, if a cemented lens is also provided in the first lens group, a lens having a negative power in the cemented lens of the first lens group is higher than a lens having a positive power. It may be made of a material having a refractive index. Thus, when each of the first lens group and the second lens group has a cemented lens, a lens with higher dispersion among a lens having a negative power and a lens having a positive power in the cemented lens. The first lens group and the second lens group may be different from each other. As a result, at least part of the field curvature that occurs in each cemented lens is canceled out, which is advantageous when it is desired to suppress the field curvature that occurs in the optical attachment.

  In addition, in the case where a total of two cemented lenses are provided in each of the first lens group and the second lens group, the aberration suppressing effect of the two cemented lenses is a field curvature rather than chromatic aberration. It is preferable that a greater weight is applied. In this case, the condition to be satisfied by the two cemented lenses is expressed by the following equation.

式２において、Ｎは、レンズの屈折率であり、ｆは、レンズの焦点距離である。添え字の１ｐは、第１レンズ群の接合レンズにおける正のパワーを持つレンズ、１ｎは、同接合レンズにおける負のパワーを持つレンズ、２ｐは、第２レンズ群の接合レンズにおける正のパワーを持つレンズ、２ｎは、同接合レンズにおける負のパワーを持つレンズ、の値であることをそれぞれ示している。

In Equation 2, N is the refractive index of the lens, and f is the focal length of the lens. The subscript 1p is a lens having positive power in the cemented lens of the first lens group, 1n is a lens having negative power in the cemented lens, and 2p is the positive power in the cemented lens of the second lens group. The lens 2n indicates the value of the lens having negative power in the cemented lens.

  In the field of ophthalmology, an OCT apparatus in which a fundus camera, an imaging apparatus for capturing a front image of the fundus, such as an SLO, is integrated is known. In this type of apparatus, an objective optical system is shared between an optical system for capturing a front image (front imaging optical system) and the OCT apparatus. In the present embodiment, it can be considered that the optical attachment is also shared. At this time, when color photographing is performed in the front photographing optical system, the aberration suppression effect in the two cemented lenses of the optical attachment may be weighted with greater chromatic aberration than curvature of field.

<OPL adjustment with insertion / removal of optical attachment>
The OCT apparatus may include an adjustment unit that adjusts an optical path length difference (OPL) between the measurement optical path and the reference optical path. For example, OPL adjustment may be required depending on the depth region from which the OCT data is acquired. The adjustment unit adjusts at least one of the optical path length of the reference optical path and the optical path length from the division unit to the objective optical system in the measurement optical path. The adjustment unit may be controlled by a control unit of the OCT apparatus. The control unit may cancel at least a part of the change in OPL accompanying the insertion / removal of the optical attachment by executing the switching operation for switching the optical path length by controlling the adjustment unit.

  In addition, the OCT apparatus may have a detector that detects the insertion / removal state of the optical attachment. In this case, the control unit detects the switching operation of the OPL accompanying the insertion / removal of the optical attachment from the detection unit. You may perform based on a signal. That is, the control unit may drive the adjustment unit based on the detection signal from the detector, and at least partially cancel the change in the optical path length difference associated with the attachment / detachment of the attachment. That is, when the optical attachment is withdrawn from the measurement optical path, the adjustment unit adjusts the optical path length in a direction to reduce the optical path length of the measurement optical path. When the optical attachment is attached, the adjustment unit adjusts the optical path length in a direction in which the optical path length of the measurement optical path is increased. By suppressing the change in the optical path length difference before and after the attachment insertion / removal, the OCT data of the desired imaging region can be acquired smoothly after the attachment / detachment. At this time, the adjustment unit may adjust the optical path length difference by an amount of correction that takes into account the optical path length corresponding to the optical attachment and the optical path length corresponding to the axial length.

<Final fundus photography>
The OCT optical system may be an OCT optical system that can guide the measurement light to a wide-angle region including the fundus center and the fundus periphery in one transverse direction in which the measurement light crosses over the fundus. In this case, as the wide-angle region, for example, when the measurement light crosses on the fundus in a specific transverse direction (for example, the horizontal direction), the wide-angle region is a wide-angle region so as to cross both the fundus center and the fundus periphery. May be. In addition, with regard to the transverse region where the measurement light traverses, for example, the transverse region at the fundus center and the transverse region at the fundus periphery may be continuous in the transverse direction. The wide angle region may be, for example, a region of 18 mm (corresponding to φ60 °) or more on the fundus. Needless to say, the wide-angle region may be used when obtaining a region narrower than 18 mm, and the apparatus of the present embodiment is particularly useful when imaging a peripheral region of the eye to be examined with a large fundus curvature.

  As the fundus center, for example, an area including at least the macular region of the fundus and the nipple is set, and as the fundus peripheral part, an area including each region outside the both ends of the fundus center with respect to one transverse direction is set. May be. Of course, the present invention is not limited to this. For example, a region including at least the macular region of the fundus is set as the center of the fundus, and regions outside the both ends of the fundus center with respect to one transverse direction are included as the fundus periphery. An area may be set.

  The OCT optical system may include a plurality of reference light paths. For example, the OCT optical system has a first reference optical path having an optical path length set to obtain OCT data including the fundus center and an optical path length set to obtain OCT data including the fundus periphery. And a second reference optical path different from the first reference optical path. In this case, the optical path length difference between the first reference optical path and the second reference optical path may be set corresponding to the optical path length difference of the measurement light between the fundus center and the fundus periphery. In consideration of the curvature of the eyeball, for example, the optical path length of the second reference optical path may be set shorter than that of the first reference optical path.

  The OCT apparatus according to this embodiment may include an image processor, and the image processor may be able to acquire OCT data by processing a spectral interference signal output from the OCT optical system.

  In this case, for example, the image processor may obtain OCT data including the fundus center based on an interference signal between the measurement light guided to the fundus center and the reference light from the first reference light path, OCT data including the fundus periphery may be obtained based on an interference signal between the measurement light guided to the fundus periphery and the reference light from the second reference light path. In this case, for example, the OCT data including the fundus center and the OCT data including the fundus periphery may be continuous in at least one of the transverse direction and the depth direction.

  According to this, for example, by providing the reference optical path corresponding to the fundus central part and the reference optical path corresponding to the fundus peripheral part, for example, OCT data in a wide-angle region can be acquired with good signal intensity.

  Note that the image processor may synthesize OCT data including the fundus center and OCT data including the fundus periphery to obtain wide-angle OCT data of the fundus of the eye to be examined. Thereby, one piece of wide-angle OCT data can be obtained.

  The OCT optical system may include an optical scanning unit (optical scanner) for scanning the measurement light on the fundus of the eye to be examined. In this case, the optical scanning unit may scan a wide-angle region including the fundus central part and the fundus peripheral part by scanning the measurement light on the fundus in one scanning direction. In this case, for example, the scanning region in the center of the fundus and the scanning region in the periphery of the fundus may be continuous in the transverse direction. Further, the optical scanning unit may be configured to scan the measurement light up to a scanning angle at which a wide-angle region on the fundus can be scanned, for example. Further, the optical scanning unit may be arranged at a position substantially conjugate with the pupil of the eye to be measured, for example, and may measure the measurement light with the pupil center as a turning point.

  When the optical scanning unit is provided, the measurement light is scanned in a wide-angle region including the fundus central part and the fundus peripheral part by one B scan by the optical scanning part, and includes the OCT data including the fundus central part and the fundus peripheral part. OCT data may be acquired. Thereby, for example, OCT data in a wide-angle region can be acquired smoothly.

  The OCT optical system may include, for example, a first detector corresponding to the fundus center and a second detector corresponding to the fundus periphery. In this case, the OCT optical system includes a first detector for detecting an interference signal between the measurement light guided to the fundus center and the reference light from the first reference optical path, and the first detector. A second detector for detecting an interference signal between the measurement light guided to the fundus periphery and the reference light from the second reference light path, which is a different second detector, may be provided. According to this, for example, since the first detector and the second detector can be used in parallel, the OCT data of the fundus central part and the fundus peripheral part can be reliably detected, and each OCT can be detected. Data can be acquired smoothly and with good signal strength.

<The optical path length of the reference optical path>
In the first reference optical path, for example, first OCT data in a state where the choroid at the center of the fundus is formed in front of the zero delay position where the optical path lengths of the measurement light and the reference light coincide with each other is acquired. The optical path length may be set as described above. According to this, for example, in the first OCT data, mixing of a mirror image and a real image can be reduced, and the contrast on the choroid side can be improved.

  The second reference optical path is acquired, for example, by the second OCT data in a state in which the retina in the vicinity of the fundus is formed on the back side from the zero delay position where the optical path lengths of the measurement light and the reference light match. The optical path length may be set as described. According to this, for example, in the second OCT data, it is possible to reduce the mixture of the mirror image and the real image, and it is possible to reduce the influence of the light amount decrease in the fundus periphery.

  In addition, by setting the first reference optical path and the second reference optical path as described above, it is possible to reduce the mixture of the mirror image and the real image in both the first OCT data and the second OCT data, The entire OCT data in the wide angle region can be obtained with good signal strength.

  The first reference optical path and the second reference optical path are not limited to the above configuration. For example, the optical path length may be set so that the first OCT data in a state where the retina at the center of the fundus is formed on the back side with respect to the first delay optical path, For example, the optical path length of the reference optical path 2 may be set so that the second OCT data in a state where the choroid around the fundus is formed in front of the zero delay position.

  The OCT optical system may further be capable of detecting, by a detector, an interference signal between the measurement light guided to the anterior eye part to be examined via the measurement optical path and the reference light from the reference optical path. In this case, the first reference optical path and the second reference optical path are set to different optical path lengths, and one of the first reference optical path and the second reference optical path is the cornea (for example, the cornea and the lens front surface) of the eye to be examined. The optical path length for obtaining the included OCT data is set, and the other of the first reference optical path and the second reference optical path is set to the optical path length for obtaining the OCT data including the crystalline lens of the eye to be examined (for example, the posterior surface of the crystalline lens). May be. According to this, in addition to the OCT data in the wide-angle region, OCT data in a wide range of the anterior segment can be acquired with a good signal intensity.

  In the above description, two reference light paths corresponding to the fundus center and the fundus periphery are provided, but the present invention is not limited to this, and three or more reference light paths may be provided. For example, the entire fundus is divided into a fundus central part, a first fundus peripheral part outside the fundus central part, and a second fundus peripheral part outside the first fundus peripheral part. There may be provided a first reference optical path corresponding to the first part, a second reference optical path corresponding to the first fundus peripheral part, and a third reference optical path corresponding to the second fundus peripheral part.

  In addition, the first wide angle set to the first reference optical path corresponding to the fundus center and the second reference optical path corresponding to the first fundus periphery by adjusting the optical path lengths of the two reference optical paths The second wide-angle imaging mode set to the imaging mode, the first reference optical path corresponding to the fundus central part or the first fundus peripheral part, and the second reference optical path corresponding to the second fundus peripheral part And may be switchable.

<Example>
In this embodiment, an optical coherence tomography (OCT) apparatus shown in FIG. 1 is used as the OCT apparatus. The OCT apparatus according to the present embodiment has, for example, a wavelength sweep type OCT (SS-OCT: Swept Source-OCT) as a basic configuration, a wavelength variable light source 102, an interference optical system (OCT optical system) 100, an arithmetic controller ( Calculation control unit) 70. In addition, the OCT apparatus may be provided with a memory 72, a display unit 75, a front image observation system and a fixation target projection system (not shown). An arithmetic controller (hereinafter referred to as a control unit) 70 is connected to the variable wavelength light source 102, the interference optical system 100, the memory 72, and the display unit 75.

  The interference optical system 100 guides the measurement light to the eye E by the light guide optical system 150. The interference optical system 100 guides reference light to the reference optical system 110. The interference optical system 100 causes the detector (light receiving element) 120 to receive the interference signal light acquired by the interference between the measurement light reflected by the eye E and the reference light. Further, the interference optical system 100 of this embodiment includes an FPN generation optical system 200 (details will be described later). The interference optical system 100 is mounted in a housing (device main body) (not shown), and the housing is three-dimensionally moved with respect to the eye E by a known alignment moving mechanism via an operation member such as a joystick. The alignment with respect to the eye to be examined may be performed.

  For the interference optical system 100, the SS-OCT method is used, and a variable wavelength light source (wavelength scanning light source) that changes the emission wavelength at a high speed in time is used as the light source 102. The light source 102 includes, for example, a laser medium, a resonator, and a wavelength selection filter. Examples of the wavelength selection filter include a combination of a diffraction grating and a polygon mirror, and a filter using a Fabry-Perot etalon. A VCSEL wavelength tunable light source may be used as the light source 102.

  The coupler (splitter) 104 is used as a first light splitter, and splits the light emitted from the light source 102 into a measurement optical path and a reference optical path. For example, the coupler 104 guides light from the light source 102 to the optical fiber 105 on the measurement optical path side and guides it to the reference optical system 110 on the reference optical path side.

  The coupler (splitter) 130 is used as a second light splitter, and splits light (measurement light) from the optical fiber 105 into an optical path of the light guide optical system 150 and an optical path of the FPN generation optical system 200. That is, the light guide optical system 150 and the FPN generation optical system 200 are provided in the measurement optical path. The coupler (splitter) 130 may be a beam splitter or a circulator.

<Light guide optical system>
The light guide optical system 150 is provided to guide the measurement light to the eye E. In the light guide optical system 150, for example, an optical fiber 152, a coupler 153, a collimator lens 154, an optical scanner 156, and an objective lens system 158 may be sequentially provided. In this case, the measurement light is converted into a parallel beam by the collimator lens 154 via the optical fiber 152 and the coupler 153 and travels toward the optical scanner 156. The light that has passed through the optical scanner 156 is applied to the eye E via the objective lens system 158. Measurement light is applied to both the anterior eye segment and the posterior eye segment, and is scattered and reflected by each tissue.

  The optical scanner 156 may scan the measurement light on the eye E in the XY direction (transverse direction). The optical scanner 156 is, for example, two galvanometer mirrors, and the reflection angle thereof is arbitrarily adjusted by a driving mechanism. The reflection (advance) direction of the light beam emitted from the light source 102 is changed and scanned in an arbitrary direction on the fundus. As the optical scanner 156, for example, an acousto-optic device (AOM) that changes the traveling (deflection) direction of light may be used in addition to a reflecting mirror (galvano mirror, polygon mirror, resonant scanner).

  In this case, the scattered light (reflected light) from the eye E by the measurement light reaches the coupler 130 after passing through the objective lens system 158, the optical scanner 156, the collimator lens 154, the coupler 153, and the optical fiber 152. The coupler 130 causes the light from the optical fiber 152 to travel toward the first detector 120a (for example, the optical fiber 115-coupler 350a) and the optical path toward the second detector 120b (for example, the optical fiber 105-coupler 104-optical fiber). 117 to coupler 350b).

  Of the measurement light split by the coupler 130, the measurement light that has passed through the optical path toward the first detector 120a is combined with the reference light from the first reference optical path 110a and interferes with the coupler 350a. In addition, the measurement light that has passed through the optical path toward the second detector 120b is combined with the reference light from the second reference optical path 110b and interferes by the coupler 350b.

<Reference optical system>
The reference optical system 110 generates reference light that is combined with reflected light acquired by reflection of measurement light by the eye E. The reference light that has passed through the reference optical system 110 is combined with light from the measurement optical path by a coupler (for example, couplers 350a and 350b) and interferes therewith. The reference optical system 110 may be a Michelson type or a Mach-Zehnder type.

  The reference optical system 110 may be formed by, for example, a reflection optical system, and may guide the light from the coupler 104 to the detector 120 by reflecting the light from the reflection optical system. The reference optical system 110 may be formed by a transmission optical system. In this case, the reference optical system 110 guides the light from the coupler 104 to the detector 120 by transmitting the light without returning.

  An optical member for adjusting the optical path length difference between the measurement light and the reference light may be disposed in at least one of the measurement light path and the reference light path. For example, the optical path length of the measurement light may be adjusted by integrally moving the collimator lens 154 and the coupler 153, and as a result, the optical path length difference between the measurement light and the reference light may be adjusted. Of course, by moving the optical member arranged in the reference optical path, as a result, the optical path length difference between the measurement light and the reference light may be adjusted.

  In the present embodiment, a plurality of reference light paths may be provided as the reference optical system 110. For example, a first reference light path 110a and a second reference light path 110b may be provided.

  In the reference optical system 110, for example, an optical splitter (for example, a coupler 111) for dividing the reference optical path into a first reference optical path 110a and a second reference optical path 110b may be provided. For example, an optical member 112 that is moved to change the optical path length of the reference light may be provided in at least one of the first reference optical path 110a and the second reference optical path 110b. The optical member 112 may be moved by a drive unit (not shown) controlled by the control unit 70.

  For example, the reference light from the coupler 104 is divided by the coupler 111 into a first reference light path 110a and a second reference light path 110b. The reference light that has passed through the first reference light path 110a is combined with the measurement light from the optical fiber 115 and interferes by the coupler 350a. The reference light that has passed through the second reference light path 110b is combined with the measurement light from the optical fiber 117 and interferes by the coupler 350b.

  The first reference optical path 110a and the second reference optical path 110b may be set to different optical path lengths. Thereby, for example, interference signals corresponding to different depth regions can be simultaneously acquired, and as a result, a wide range of OCT data can be simultaneously acquired.

  For example, the first reference light path 110a is provided to obtain an interference signal corresponding to a first depth region (for example, the crystalline lens, the fundus) in the eye to be examined, and the second reference light path 110b is the first reference light path 110b in the eye to be examined. It may be provided to obtain an interference signal corresponding to two depth regions (eg, cornea). In this case, the second depth region is set to a region different from the first depth region. In this case, the first depth region and the second depth region may be regions that are separated from each other, may be regions that are adjacent to each other, or may be regions that partially overlap each other. Good.

  Note that the first reference optical path 110a and the second reference optical path 110b may be set to the same optical path length. Thereby, for example, interference signals corresponding to the same depth region can be simultaneously acquired, and as a result, a plurality of OCT data regarding the same region can be simultaneously acquired.

<Photodetector>
The detector 120 is provided to detect interference caused by light from the measurement optical path and light from the reference optical path. The detector 120 may be a light receiving element. For example, the detector 120 may be a point sensor having only one light receiving unit, and for example, an avalanche photodiode may be used.

  In the present embodiment, the detector 120 may be provided with a first detector 120a and a second detector 120b different from the first detector 120a. The first detector 120a may be provided as a detector for detecting a first interference signal between the reference light from the first reference light path 110a and the measurement light from the optical fiber 115. The second detector 120b may be provided as a detector for detecting a second interference signal between the reference light from the second reference light path 110b and the measurement light from the optical fiber 117. In this case, the first interference signal and the second interference are detected by detecting the first interference signal by the first detector 120a and simultaneously detecting the second interference signal by the second detector 120b. Signals can be detected simultaneously. The sampling rates of these detectors may be different from each other or the same.

  Each of the first detector 120a and the second detector 120b may be a balanced detector. In this case, each of the first detector 120a and the second detector 120b includes a plurality of light receiving elements, obtains a difference between the interference signal from the first light receiving element and the interference signal from the second light receiving element, Unnecessary noise included in the interference signal can be reduced.

<FPN generation optical system>
The FPN generation optical system 200 may be provided to generate an FPN signal. The FPN generation optical system 200 may include at least one optical member (for example, the first optical member 204 or the second optical member 206) that generates FPN. In this embodiment, the FPN generation optical system 200 is arranged at a position where the measurement light is branched from the optical path toward the eye to be examined.

  As the FPN generation optical system 200, for example, a reflection optical system may be used, and as the FPN generation optical member, for example, a light reflection member (for example, a mirror) may be used. In this embodiment, a plurality of optical members that generate FPN are provided. However, the present invention is not limited to this, and the FPN generation optical system 200 may be configured to include one optical member that generates FPN.

  The first detector 120a detects the FPN signal together with the first interference signal, and the second detector 120b detects the FPN signal together with the second interference signal. For example, the FPN signal is a combination of first OCT data based on the first interference signal and second OCT data based on the second interference signal (details will be described later), wave number mapping correction of each interference signal, It may be used for polarization adjustment or the like.

  For example, the FPN generation optical system 200 may be provided to generate a first FPN signal and a second FPN signal. For example, the FPN generation optical system 200 may include at least a first optical member 204 that generates a first FPN and a second optical member 206 that generates a second FPN. The second optical member 206 may be arranged so that the light passing through the second optical member is different from the optical path length of the light passing through the first optical member 204. Thereby, the second FPN is generated at a different position with respect to the first FPN. A zero delay position to be described later corresponds to a position where the optical path length of the measurement light and the optical path length of the reference light coincide with each other on the OCT data.

  By using the first optical member 204 and the second optical member 206 at the same time, it is possible to generate two FPN signals at the same time, so that the time required for processing the two FPN signals is increased. The effect of slack can be reduced. Note that the FPN optical system 200 may include three or more FPN generation optical members, and by using these simultaneously, it is possible to simultaneously generate three or more FPN signals.

  As the FPN generation optical system 200, for example, a reflection optical system may be used, and as the FPN generation optical member, for example, a light reflection member (for example, a mirror) may be used. In this embodiment, mirrors are used as the first FPN generating optical member 204 and the second FPN generating optical member 206, but the present invention is not limited to this.

  In this case, the light from the coupler 130 passes through the first optical member 204 or the second optical member 206 and then returns to the coupler 130, and passes through the same path as the light from the light guide optical system 150. 350a reaches the coupler 350b. The light from the FPN generation optical system 200 is combined with the reference light by the couplers 350a and 350b and interferes therewith. The optical path lengths of the light source 102 to the FPN generation optical system 200 to the couplers 350a and 350b and the optical path length from the light source 102 to the reference optical system 110 to the couplers 350a and 350b may be set to substantially the same length.

  For example, when the light passing through the first optical member 204 interferes with the reference light, an interference signal light corresponding to the first FPN is generated, and a first FPN signal is generated in the detector 120. The light passing through the second optical member 206 interferes with the reference light, whereby interference signal light corresponding to the second FPN is generated, and the detector 120 generates a second FPN signal. As a result, for example, the detector 120 detects both the first FPN signal and the second FPN signal simultaneously.

  When the FPN signal is used for predetermined processing, both the first FPN signal and the second FPN signal may be detected simultaneously in each of the detector 120a and the detector 120b, or one FPN is detected in the detector 120a. The signal may be detected and the other FPN signal may be detected at the detector 120b. In addition, one of the detector 120a and the detector 120b detects both the first FPN signal and the second FPN signal simultaneously, and the other of the detector 120a and the detector 120b detects the first FPN signal and the second FPN signal. One of the FPN signals may be detected. Further, at least one FPN signal may be detected by one of the detector 120a and the detector 120b, and the FPN signal may not be detected by the other of the detector 120a and the detector 120b.

  Note that a light amount monitor 210 may be disposed in the FPN generation optical system 200, and light from the light source 102 is detected by the light amount monitor 120 via the beam splitter 208. The output signal from the light amount monitor 120 may be used to determine whether or not the amount of light emitted from the light source 102 is appropriate.

<Light splitting ratio>
Here, the coupler 130 divides the light from the coupler 104 into the optical path of the light guide optical system 150 and the optical path of the FPN generation optical system 200, and the light from the light guide optical system 150 and the FPN generation optical system 200, It divides | segments into the optical path (for example, optical fiber 115-coupler 350a) which goes to the 1st detector 350a, and the optical path (for example, optical fiber 105-coupler 104-optical fiber 117-coupler 350b) which goes to the coupler 104. FIG.

  The light amount division ratio S <b> 1 of the coupler 130 when dividing the light from the fiber 105 may be set so that more light is guided to the FPN generation optical system 200 than to the light guide optical system 150. In this case, the light amount ratio by which the light from the fiber 105 is divided by the coupler 130- is the light guide optical system 150 <FPN generation optical system 200.

  The light quantity division ratio S2 of the coupler 130 when dividing the light from the light guide optical system 150 depends on the light quantity division ratio S1. As a result, with respect to the light from the light guide optical system 150, more light is guided to the optical path toward the second detector 120a than to the optical path toward the first detector 120a. In this case, the light amount ratio by which the light from the light guide optical system 150 is divided by the coupler 130 is such that the optical path toward the first detector 120a <the optical path toward the coupler 104.

  The measurement light that has passed through the optical path toward the first detector 120a interferes with the light from the first reference optical path 110a, and then is detected as a first interference signal by the first detector 120a. On the other hand, the measurement light traveling toward the coupler 104 is split by the coupler 104 into an optical path toward the light source 102 and an optical path toward the second detector 120b (for example, the optical fiber 117 to the coupler 350b). The light amount division ratio S4 when the light from the coupler 130 is divided depends on the light amount division ratio S3 when the light from the light source 102 is divided into the measurement optical path and the reference optical path. When the light quantity division ratio S3 is set so that more light is guided to the reference optical path than the measurement optical path, the light quantity ratio by which the light from the coupler 130 is divided by the coupler 104 is such that the optical path toward the light source 102 <second. This is an optical path toward the detector 120b. As a result, with respect to the light from the coupler 130, more light is guided to the optical path toward the second detector 120 b than to the optical path toward the light source 102. The measurement light that has passed through the optical path toward the second detector 120b interferes with the light from the second reference optical path 110b, and then is detected as a second interference signal by the second detector 120b.

  In summary, the optical path toward the first detector 120a <the optical path toward the coupler 104 with respect to the light quantity division ratio S2 of the coupler 130, and the optical path toward the light source 102 with respect to the light quantity division ratio S4 of the coupler 104 <second. It is set in the optical path toward the detector 120b.

  As a result, the first interference signal detected by the first detector 120a and the second interference signal detected by the second detector 120b can be detected with an appropriate balance. That is, in the case of an optical path directed to the second detector 120b via the coupler 104, the light from the light guide optical system 150 passes through a plurality of optical splitters (for example, the coupler 130 and the coupler 104), and thus the light amount Whereas the number of attenuations is large, in the case of the optical path toward the first detector 120a, the light from the light guide optical system 150 reaches the first detector 120a via the coupler 130, and therefore the amount of light attenuation is reduced. The number of times is relatively small.

  Therefore, regarding the light amount division ratio S2 of the coupler 130, the optical path toward the first detector 120a <the optical path toward the coupler 104, and regarding the light amount division ratio S4 of the coupler 104, the optical path toward the light source 102 <the second detector 120b. Since the light path is directed to, even if the light amount attenuation is performed a plurality of times, the light amount attenuation can be reduced, and as a result, the difference in signal intensity between the first detector 120a and the second detector 120b can be reduced. Less. Therefore, the difference in signal intensity between the OCT data obtained by the first detector 120a and the OCT data obtained by the second detector 120b is reduced, and appropriate OCT data can be acquired.

  It should be noted that the light quantity division ratio S2 of the coupler 130 and the light quantity division ratio S4 of the coupler 104 are set so that the light quantity ratio between the optical path toward the first detector 120a and the optical path toward the second detector 120b is the same. May be. As an example, regarding the light amount division ratio S2 of the coupler 130, the optical path toward the first detector 120a: the optical path toward the coupler 104 = 6: 4, and the light path toward the light source 102 regarding the light amount division ratio S4 of the coupler 102: No. The optical path toward the second detector 120b may be set to be 1: 2.

  The light amount split ratio S2 of the coupler 130 and the light amount split ratio S4 of the coupler 104 are not limited to the above, and the amount of reflected light at the imaging region of the OCT data detected by the first detector 120a and the second detector 120b is related. In consideration of the difference, the light quantity division ratio may be set. That is, the reflected light from the cornea of the eye to be examined has a large amount of reflected light, but the light from the crystalline lens and the fundus has a relatively small amount of reflected light. Therefore, in consideration of the ratio of the amount of light reflected by the imaging region, as a result, the light amount of the coupler 130 so that the signal intensity of the OCT data between the first detector 120a and the second detector 120b is the same. The division ratio S2 and the light amount division ratio S4 of the coupler 104 may be set.

  In this embodiment, when the light from the light guide optical system 150 is guided to a plurality of detectors, the light traveling toward the first detector 120a via one light splitter (for example, the coupler 130) The light divided into the light directed to the second detector 120b through a plurality of couplers (for example, the coupler 130 and the coupler 104) can more efficiently guide the light from the light guide optical system 150 to each detector. To be free. Such an optical arrangement is particularly advantageous when the amount of light emitted from the light source 120 is limited and the reflected light from the eye to be examined is weak.

  FIG. 2 is a diagram illustrating an example of an FPN generation optical system according to the present embodiment. The FPN generation optical system 200 may include at least a first optical path 203 including a first optical member 204 and a second optical path 205 including a second optical member 206, for example. Here, between the first optical path 203 and the second optical path 205, the optical path length of the first optical path 203 and the optical path length of the second optical path 205 are different. It is generated at a position different from the FPN. For example, when the optical path length of the second optical path 205 is longer than the optical path length of the first optical path 203, the optical path length is generated at a position farther from the zero delay than the first FPN.

  The FPN generation optical system 200 may include an optical path splitting member 202 (for example, a beam splitter). The optical path splitting member 202 splits the light path on the light source side into a first optical path 203 and a second optical path 205. May be provided for this purpose. The first optical member 204 is arranged in the first optical path 203 divided by the optical path dividing member 202, and the second optical member 206 is arranged in the second optical path divided by the optical path dividing member 202. ing.

  The first optical path 203 and the second optical path 205 have different optical path lengths. That is, the optical path length from the branch position of the optical path dividing member 202 to the first optical member 204 and the optical path length from the branch position of the optical path dividing member 202 to the second optical member 206 are different. As a result, the first FPN formed by the first optical member 204 and the second FPN formed by the second optical member 206 are formed at different positions in the depth direction on the OCT image. . Note that the distance between the first FPN and the second FPN in the depth direction is due to the optical path length difference between the first optical path 203 and the second optical path 205.

  Further, the first optical path 203 and the second optical path 205 are set (constructed) to have the same optical dispersion amount. As a result, mapping information of each wave number component calculated using the first FPN (hereinafter referred to as first wave number mapping information) and mapping information of each wave number component calculated using the second FPN (hereinafter referred to as “first wave number mapping information”). When calculating correction information for correcting the mapping state of each wave number component based on the difference from the second wave number mapping information), the dispersion component included in each mapping information can be canceled appropriately. The correction information can be obtained with high accuracy (details will be described later). In this case, the equal dispersion amounts do not necessarily have to be exactly the same, as long as a certain degree of accuracy is ensured and the dispersion components can be canceled appropriately.

<Polarization adjustment mechanism>
In the OCT optical system 100 of the present embodiment, a plurality of polarization adjustment units may be provided. For example, in the optical path of the OCT optical system 100, a first polarization adjustment unit 300, a second polarization adjustment unit 302, and a second polarization adjustment unit are provided. 3 polarization adjustment units 304 may be provided (see FIG. 1).

  The first polarization adjusting unit 300 may be provided in order to adjust the polarization state of the reference light that is disposed in the optical path of the first reference optical path 110a and passes through the first reference optical path 110a. The second polarization adjustment unit 302 may be provided in order to adjust the polarization state of the reference light that is disposed in the optical path of the second reference optical path 110b and passes through the second reference optical path 110b. The third polarization adjustment unit 304 may be disposed in the optical path of the FPN generation optical system 200 and may be provided to adjust the polarization state of light passing through the optical path of the FPN generation optical system 200.

<Acquisition of depth information>
When the emission wavelength is changed by the light source 102, the corresponding interference signal light is received by the detector 120, and as a result, detected by the detector 120 as a spectrum signal. The control unit 70 processes (Fourier analysis) the spectrum signal detected by the detector 120 to obtain OCT data of the eye to be examined.

  The spectrum signal (spectrum data) may be rewritten as a function of the wavelength λ and converted into a function I (k) that is equally spaced with respect to the wave number k (= 2π / λ). Alternatively, it may be acquired from the beginning as a function I (k) that is equally spaced with respect to the wave number k (K-CLOCK technique). The arithmetic controller may obtain OCT data in the depth (Z) region by performing a Fourier transform on the spectrum signal in the wave number k space.

  Furthermore, the information after the Fourier transform may be expressed as a signal including a real component and an imaginary component in the Z space. The control unit 70 may obtain OCT data by obtaining absolute values of real and imaginary components in the signal in the Z space.

  In the present embodiment, the control unit 70 processes the first interference signal detected by the first detector 120a to obtain first OCT data, and the second detector 120b detects the second signal detected by the second detector 120b. The second OCT data may be obtained by processing the interference signal. Here, when the first reference optical path 110a and the second reference optical path 120b are set to different optical path lengths, the first OCT data and the second OCT data are at least partially different in the depth direction. When the first reference optical path 110a and the second reference optical path 120b are set to the same optical path length, the first OCT data and the second OCT data are the same region in the depth direction. OCT data is acquired.

<Control system>
The control unit 70 may include a CPU (processor), a RAM, a ROM, and the like (see FIG. 1). For example, the CPU of the control unit 70 may control the OCT apparatus. The RAM temporarily stores various information. Various programs for controlling the operation of the OCT apparatus, initial values, and the like may be stored in the ROM of the control unit 70.

  A non-volatile memory (hereinafter abbreviated as “memory”) 72 as a storage unit, a display unit 75, and the like may be electrically connected to the control unit 70. The memory 72 may be a non-transitory storage medium that can retain stored contents even when power supply is interrupted. For example, a hard disk drive, a flash ROM, and a USB memory that is detachably attached to the OCT apparatus can be used as the memory 72. The memory 72 may store a control program for controlling acquisition of OCT data and imaging of an OCT image, an arithmetic processing program for synthesizing an OCT image using FPN, and a mapping state of each wave number component An arithmetic processing program for obtaining correction information for correcting the above may be stored. In addition to the OCT image generated from the OCT data, the memory 72 may store various types of information related to imaging. The display unit 75 may display an OCT image generated from the OCT data.

<Image composition using FPN>
The control unit 70 converts the first OCT data based on the first interference signal and the second OCT data based on the second interference signal into the FPN signal detected by the first detector 120a and the second OCT data. The synthesized OCT data may be obtained by synthesis based on the FPN signal detected by the detector 120b (see FIGS. 3 to 5). That is, the FPN signal may be used as a reference signal for combining a plurality of OCT data. Here, the second OCT data may be different from the first OCT data in at least a part of the depth region on the eye to be examined.

  As an example, since the arrangement position of the optical member (for example, the optical members 204 and 206) for generating the FPN in the FPN generation optical system 200 is known, the positional relationship between the first OCT data and the second OCT data is determined. You may set using a FPN signal.

  Thereby, the positional relationship between the first OCT data and the second OCT data can be set appropriately. In the present embodiment, the first OCT data is detected by the first detector 120a and the second OCT data is detected by the second detector 120b at the same time. Positional misalignment due to such as can be reduced.

  For example, the FPN generation optical system 200 generates a first FPN that generates a first FPN (for example, the first optical member 204) and a second FPN that generates a second FPN at a position different from the first FPN. And an FPN generation optical system for generating at least two FPN signals, at least two optical members (for example, the second optical member 206).

  The control unit 70 uses the first optical member detected by the first detector 120a to generate the first OCT data based on the first interference signal and the second OCT data based on the second interference signal. The synthesized OCT data may be obtained by synthesis based on the FPN and the FPN by the second optical member detected by the second detector 120b.

  FIGS. 3 and 4 are diagrams showing an example of data when a plurality of OCT data is synthesized using an FPN signal. FIG. 3 is a diagram before synthesis, and FIG. 4 is an image diagram after synthesis. FPN1 is an FPN signal generated by the first optical member 204, and FPN2 is an FPN signal generated by the second optical member 206.

In FIG. 3, FPN1 is formed in the first OCT data, and FPN2 is formed in the second OCT data. The first OCT data is acquired using the first reference optical path 110a and the first detector 110a, and the second OCT data is acquired using the second reference optical path 110b and the second detector 110b. May be.

  When setting the positional relationship between the OCT data using the FPN signal, the control unit 70 uses, for example, the position between the OCT data using FPN1 included in the first OCT data and FPN2 included in the second OCT data. A relationship may be set. Here, the control unit 70 may detect the position of the FPN in the depth direction and synthesize a plurality of OCT data based on the detected position of the FPN (see FIG. 4).

  Here, since the positional relationship between the first optical member 204 and the second optical member 204 is known (for example, the optical path length ΔD), the control unit 70 performs the first OCT data and the second OCT data. When combining data, the positions of FPN1 and FPN2 may be detected and combined so that the detection position of FPN1 and the detection position of FPN2 are separated by the optical path length ΔD. It should be noted that any one of the OCT data may be used for the synthesis of the overlapping portion between the plurality of OCT data, or the average of both OCT data may be obtained.

  The control unit 70 may measure the dimensions of the eye to be examined (for example, anterior chamber depth, axial length, etc.) based on the synthesized OCT data synthesized as described above, and further, the obtained measurement results are displayed. You may display on the display part 75. FIG.

  FIG. 5 is a diagram showing an example of data transformation when combining a plurality of OCT data using the FPN signal. FPN1 and FPN2 are formed in the third OCT data. Here, the third OCT data may be acquired using the first reference optical path 110a and the first detector 110a, and the third OCT data is adjusted by adjusting the optical path length of the first reference optical path 110a. OCT data may be acquired.

  Here, the control unit 70 may set the positional relationship between the first OCT data and the second OCT data using the third OCT data. In this case, for example, the control unit 70 determines the positional relationship so that the detection position of FPN1 on the first OCT data and the detection position of FPN1 on the third OCT data are the same position in the depth direction. Further, for example, the control unit 70 may detect the FPN2 detection position on the second OCT data and the FPN2 detection position on the third OCT data at the same position in the depth direction. The positional relationship may be set so that According to this, even if the position of the optical member for generating FPN fluctuates due to secular change, the actual positional relationship can be used, so that the positional relationship between the first OCT data and the second OCT data can be further increased. It can be set stably.

  When detecting the position of the FPN in the depth direction, for example, the control unit 70 processes the OCT data acquired by the detectors 120a and 120b, and generates an optical member for generating FPN (for example, the first optical unit). The FPN signal from the member 204 or the second optical member 206) may be extracted. Since the signal strength of the FPN signal is known, the control unit 70 determines whether or not the luminance signal of the OCT data exceeds a threshold set for obtaining the FPN signal, for example, for generating the FPN. FPN signals (reference signals) corresponding to the optical members can be extracted. Note that FPN1 and FPN2 can be determined using a known arrangement.

  Note that the present invention is not limited to the above-described method, and the third OCT data in FIG. 5 may be used as the first OCT data and may be combined as the second OCT data in FIG. 5 (see FIG. 6). In this case, FPN1 and FPN2 are formed in the first OCT data, and FPN2 is formed in the second OCT data. The first OCT data is acquired using the first reference optical path 110a and the first detector 110a, and the second OCT data is acquired using the second reference optical path 110b and the second detector 110b. May be.

  In this case, the control unit 70 may detect the position of the FPN 2 and set the positional relationship between the OCT data using the detected position, or the FPN 2 of the first OCT data and the second OCT data The positional relationship may be set by matching the FPN2 with image processing. In this case, the controller 70 may combine the combined OCT data so that the FPN1 of the first OCT data and the FPN1 of the second OCT data match in the depth direction.

  In the present embodiment, in the FPN generation optical system 200, the first optical path 203 in which the first optical member 204 is disposed and the second optical path 205 in which the second optical member 206 is disposed are equal to each other. The optical dispersion amount is set (constructed). As a result, since the PSF signal by FPN has a similar shape, for example, even when the quality of the light source is poor and the PSF is not unimodal, the corresponding peak position can be easily detected and the separation can be easily determined. .

  FIG. 6 can also be considered as an example in which image synthesis is performed using one FPN. The generation of FPN1 is not necessarily essential. That is, even if the FPN optical system 200 of the present embodiment includes a single optical member for generating FPN, image composition is possible and the configuration of the apparatus can be simplified. The imaging range in the depth direction is narrower than when it is used, and the overlapping area between different OCT data increases. On the other hand, when providing a common area, by using a plurality of FPN signals, the imaging range in the depth direction can be widened, and the overlapping area between different OCT data can be reduced. In addition, a discontinuous area may be included. Also in this case, since the distance between the two can be accurately determined, it is useful, for example, when examining an eye accommodation function.

  In the FPN generation optical system 200 according to the present embodiment, the optical members for FPN generation (for example, the first optical member 204 and the second optical member 206) used for the synthesis of the OCT data are arranged in the air. Since the FPN generated by the surface reflection is used for image synthesis, as a result, it is possible to reduce the decrease in the signal strength (SNR) of the FPN, so that the OCT data using the FPN is accurately synthesized. be able to.

  The timing for obtaining the FPN signal may be implemented, for example, when the power is turned on, or may be implemented every time the subject is changed. Further, it may be performed at the time of optimization control for optimizing imaging conditions in the OCT optical system. Of course, the present invention is not limited to this and may be always performed. For example, the control unit acquires OCT data including the FPN signal in advance, and performs synthesis of the OCT data acquired later, correction of the mapping state, polarization adjustment, and the like using the previously acquired FPN signal. May be.

<Light shielding member>
Note that a light blocking member or a light reducing member may be disposed in the optical path of the FPN generation optical system 200 to reduce the FPN signal of OCT data used for observation or imaging of the eye to be examined. In this case, the FPN signal on the OCT data may be reduced by blocking or dimming at least one of the first optical path and the second optical path. These are effective in obtaining OCT data used for diagnosis and observation. Further, the present invention is not limited to this, and the FPN signal included in the OCT data may be removed by signal processing.

  For example, the optical path of the FPN generation optical system 200 includes a first light shielding member 210 for shielding the first optical path and a second light shielding member 212 for shielding the second optical path in each optical path. On the other hand, it may be arranged to be detachable.

<Correction of wave number mapping>
FIG. 7 is a diagram illustrating an example of the OCT data according to the present embodiment, and the first FPN signal and the second FPN signal are simultaneously formed on the OCT data. Note that the OCT data may include an OCT image of the eye to be examined.

  In this case, the control unit 70 processes a signal including both the first FPN and the second FPN at the same time, and acquires correction information for correcting the mapping state of each wave number component. That is, the control unit 70 may be used as an arithmetic processor that obtains correction information, for example. Further, the correction information may be acquired by a processor different from the control unit that drives the OCT optical system. Note that the control unit 70 generates correction information by using phase difference information of at least two FPN signals that are associated with the wavelength being swept by the light source 102 during or before the OCT image is captured. Also good.

  More specifically, the control unit 70 corrects the mapping state (wave number sampling mapping) of each wavelength component (wave number component) with respect to the sampling point p based on at least two FPN signals generated by the FPN generation optical system 200. May be.

  For example, the control unit 70 may obtain φ (k) in the spectrum signal at the position corresponding to the FPN by analyzing the intensity level of the FPN. φ (k) indicates a change in the phase φ of the spectrum signal according to the sweep wavelength (wave number). φ (k) may be represented by a function having a horizontal axis: wave number k and a vertical axis: phase φ. Polynomial fitting may be performed on φ (k) in the wave number k region where the signal strength (amplitude) is large, and φ (k) in the wave number k region where the signal strength is low may be obtained by extrapolation or interpolation. For example, φ (k) may be obtained from Arc Tangent (inverse tangent) of the ratio of the real part RealF and the imaginary part ImagF of the Fourier transform value (intensity value) F at the depth position corresponding to the FPN. Here, arc tangent of the ratio of the real part and the imaginary part of the Fourier transform value is calculated by Arc Tangent processing, and φ (k) is obtained.

  When at least two FPN signals are obtained at the same time, the control unit 70 processes the first FPN to obtain the first wave number mapping information φ1 (k), and processes the second FPN to obtain the second wave number. Mapping information φ2 (k) may be obtained (see FIG. 8). In this case, each wave number mapping information may be obtained as phase information of each wave number component.

  Further, the control unit 70 may obtain difference information Δφ (k) between the first wave number mapping information φ1 (k) and the second wave number mapping information φ2 (k) (see FIG. 5). The difference information may be obtained as phase difference information of each wave number component. When obtaining the difference information Δφ (k), since the phase advance of the second FPN is faster, the difference information may be obtained by Δφ (k) = φ2 (k) −φ1 (k). In addition, the dispersion | distribution component contained in each wave number mapping information can be canceled by calculating | requiring difference information. In this case, as described above, it is preferable that the amount of dispersion between the first optical path 203 and the second optical path 205 be equal.

  Here, if the optical distance (optical path length difference) between the first FPN and the second FPN is ΔZ, and the difference information Δφ (k) is ideal, the following equation (1)

に示されるような直線となるはずである。

It should be a straight line as shown in.

  Here, ΔZ is obtained as follows. The interference component can be generalized as exp (ikz), and k and z have a relationship of kz = 2π. From this, z is the following equation (2), where N is the number of sampling points and kmax and kmin are the maximum and minimum values of the k value detected at each sampling point.

として、表すことができる。なお、ｉ＝０，１，２，・・・，Ｎ／２
ここで、ΔＺに相当する干渉信号が、ｉ（ΔＺ）に対応するサンプリングポイントで検出されるとすると、ΔＺは以下の式（３）

Can be expressed as: I = 0, 1, 2,..., N / 2
If an interference signal corresponding to ΔZ is detected at a sampling point corresponding to i (ΔZ), ΔZ is expressed by the following equation (3).

と表すことができる。

It can be expressed as.

  Since Δφ (k) should ideally be a straight line with a slope ΔZ and an intercept 0, assuming that the second-order and third-order nonlinear terms are σ, k is expressed by the following equation (4):

と補正される。これから補正された波長λ´がλ´＝２π／ｋ´と決まる。ここでσは以下の式（５）

It is corrected. The corrected wavelength λ ′ is determined as λ ′ = 2π / k ′. Where σ is the following equation (5)

と展開したときの非線形項σ＝ｂ２ｋ２+ｂ３ｋ３である。なお、上記例では、非線形項が３次となっているが、これに限定されず、さらに多い非線形項であってもよい。例えば、９次程度であってもよい。あるいは、他のフィット方法（チャープされた正弦波によるフィット方法）が用いられてもよい。

And the nonlinear term σ = b2k2 + b3k3. In the above example, the nonlinear term is the third order. However, the present invention is not limited to this, and more nonlinear terms may be used. For example, it may be about the 9th order. Alternatively, another fitting method (a fitting method using a chirped sine wave) may be used.

  FIG. 9 is a diagram schematically illustrating mapping of spectrum signals to be corrected by performing correction calculation. Further, the corrected values of Δφ (kmin) and Δφ (kmax) are within a predetermined allowable range (for example, about 1E-5) from the ideal values z (peak) · kmin, z (peak) · kmax. If so, it is determined that it has converged. If this condition is not satisfied, the same calculation is repeated again using the above-mentioned corrected λ ′.

  As described above, the control unit 70 may obtain correction information from at least two FPN signals generated by using the FPN generation optical system 200 by calculation, and store the obtained correction information in the memory 72. Thereby, the correspondence between each wavelength component detected by the detector 120 and each sampling point is obtained more accurately. The obtained correction information may be used for acquiring OCT data. For the method of obtaining φ (k) from FPN and the method of obtaining wave number mapping information, refer to JP2013-156229A, JP2015-68775A, and the like.

  In the above description, the case where the wave number mapping information is corrected in SS-OCT is shown. However, the present invention is not limited to this, and the present embodiment can be applied to the case where wave number mapping information is corrected in SD-OCT. It is. In this case, for example, the control unit 70 may correct the mapping state for each wavelength (wave number) for each light receiving element of the spectrometer based on at least two FPN signals generated by the FPN generation optical system 200. . In this case, JP 2010-220774 A may be referred to.

  For the wave number mapping correction according to this embodiment, refer to Japanese Patent Application No. 2017-0117156.

  In addition, as timing which acquires the correction information for correcting the mapping state of each wave number component, for example, it may be performed when the power is turned on, or may be performed every time the subject is changed. Further, it may be performed at the time of optimization control for optimizing imaging conditions in the OCT optical system. Of course, the present invention is not limited to this and may be always performed. Note that after correction of the mapping state, the FPN on the OCT image may be removed by noise removal processing.

  In the above description, the FPN generation optical system is provided at a position branched from the measurement optical path. For example, the FPN generation optical system may be arranged at a position branched from the reference optical path of the OCT optical system. In this case, for example, an FPN signal due to interference between light from the FPN generation optical system and reference light (or measurement light) may be obtained. Further, for example, the FPN generation optical system may be arranged at a position branched from the optical path after the measurement optical path and the reference optical path merge. In this case, for example, an FPN signal is obtained by interference between the interference light that goes directly to the optical path of the interference light and the interference light from the FPN generation optical system provided at a position branched from the optical path of the interference light. May be detected. In addition, when the detector 120 includes the first detector 120a and the second detector 120b, the FPN generation optical system is arranged before being divided into the optical paths of each detector, so that each detector A similar FPN signal may be detected.

<Application example to the eye to be examined>
This apparatus may be an ophthalmic OCT apparatus for acquiring OCT data of an eye to be examined. For example, the ophthalmic OCT apparatus may be configured to be able to acquire fundus OCT data and anterior segment OCT data including the cornea and the lens, and based on the cornea and fundus OCT data. The structure which can measure axial length is also possible.

  For example, the ophthalmic OCT apparatus may be configured such that the optical arrangement of the OCT optical system 100 can be switched in accordance with an automatic or manual mode switching signal. Hereinafter, an example in which the mode is switched among the fundus photographing mode, the anterior segment photographing mode, and the axial length measurement mode will be described.

<Fundus photography mode>
When the fundus photographing mode is set, the control unit 70 may control the light guide optical system 150 and switch to an optical arrangement for obtaining fundus OCT data. In this case, for example, the control unit 70 optically arranges the light guide optical system 150 so that the turning point of the measurement light is formed on the eye pupil to be examined and the condensing position of the measurement light is formed on the fundus. May be switched. For the configuration related to the switching of the optical arrangement of the light guide optical system 150, see, for example, Japanese Patent Application Laid-Open No. 2006-209577.

  When the fundus imaging mode is set, the control unit 70 may adjust the optical path length of at least one of the measurement light and the reference light, and set the OCT data acquisition region in the fundus. In this case, for example, the control unit 70 sets the measurement light and the reference light so that the optical path length of the reference light passing through at least one of the plurality of reference optical paths matches the optical path length of the measurement light passing through the fundus. The optical path length difference between them may be adjusted. When the optical path length difference is adjusted, the OCT data may be adjusted so that the retina is formed on the back side with respect to the zero delay position, or the choroid may be on the front side with respect to the zero delay position. It may be adjusted so that the OCT data is acquired in the formed state.

  In the present embodiment, for example, the measurement is performed by moving the optical member disposed in the measurement optical path so that the optical path length of the measurement light from the fundus coincides with the reference light from the first reference optical path 110a. The optical path length of light may be adjusted. Thereby, at least the first OCT data obtained based on the output signal from the first detector 110a includes fundus OCT data.

  FIG. 10 is a diagram illustrating an example of OCT data acquired in the fundus imaging mode. The control unit 70 may move the optical member 112 and adjust the optical path length of the second reference optical path 110b so as to have the same optical path length as that of the first reference optical path 110a. As a result, the first OCT data based on the first detector 110a and the second OCT data based on the second detector 110b become the same region of the fundus. In this case, the control unit 70 may obtain synthesized OCT data (for example, an addition average image, a super-resolution image, etc.) based on the first OCT data and the second OCT data. Thus, good fundus OCT data regarding a predetermined imaging region can be obtained in a short time.

<Ocular length measurement mode>
When the axial length measurement mode is set, the control unit 70 may control the light guide optical system 150 to switch to the same optical arrangement as the above-described fundus photographing mode. In this case, for example, the control unit 70 switches the optical arrangement of the light guide optical system 150 so that the turning point of the measurement light is formed on the pupil and the condensing position of the measurement light is formed on the fundus. May be. Thereby, in the OCT data obtained at the time of measuring the axial length, the fundus morphology information (for example, information around the macula) can be acquired in detail, and as a result, the axial length of the eye to be examined can be accurately measured. .

  When the axial length measurement mode is set, the control unit 70 adjusts the optical path length of at least one of the measurement light and the reference light, and the OCT data by one of the first detector 120a and the second detector 120b. May be set on the fundus and the OCT data acquisition region by the other of the first detector 120a and the second detector 120b may be set on the cornea.

  FIG. 11 is a diagram illustrating an example of OCT data acquired in the axial length imaging mode. In the present embodiment, for example, the measurement is performed by moving the optical member disposed in the measurement optical path so that the optical path length of the measurement light from the fundus coincides with the reference light from the first reference optical path 110a. The optical path length of light may be adjusted. Thereby, at least the first OCT data obtained based on the output signal from the first detector 110a includes fundus OCT data.

  In a state in which the position of the optical member arranged in the measurement optical path is adjusted so that the first OCT data includes the fundus OCT data, for example, the control unit 70 includes the optical path length of the measurement light from the cornea, By moving the optical member 112 disposed in the second reference optical path 110b so that the reference light from the second reference optical path 110b matches, the optical path length of the reference light in the second reference optical path 110b is increased. It may be adjusted. Accordingly, the second OCT data obtained based on the output signal from the second detector 110b includes the corneal OCT data.

  When the fundus OCT data and the cornea OCT data are acquired, the control unit 70 may detect the retinal position based on the fundus OCT data and may detect the cornea position based on the cornea OCT data. The control unit 70 may measure the axial length using the detection result of the retinal position, the detection result of the corneal position, and the optical path length difference between the first reference optical path 110a and the second reference optical path 110b. .

  In this case, for example, the optical path length difference between the first reference optical path 110a and the second reference optical path 110b may be obtained by the drive position of the drive unit for moving the optical member 112, or It may be detected based on the position. When the optical path length difference between the first reference optical path 110a and the second reference optical path 110b is fixed, a known optical path length difference may be used. In addition, the FPN generation optical system 200 is not limited to this, and includes an FPN generation optical member for generating an FPN signal corresponding to the cornea and an FPN generation optical member for generating an FPN signal corresponding to the fundus. Alternatively, the optical path length difference may be acquired using the position of a known optical member. In this case, three or more FPN generating optical members may be used to cope with the optical path length difference.

<Anterior segment photography mode>
When the anterior segment imaging mode is set, the control unit 70 may control the light guide optical system 150 to switch to an optical arrangement for obtaining OCT data of the anterior segment including the cornea and the crystalline lens. In this case, the optical arrangement of the light guide optical system 150 is switched so that the turning point of the measuring light is formed on the apparatus side of the eye pupil to be examined and the condensing position of the measuring light is formed on the anterior eye part. May be. For the configuration related to the switching of the optical arrangement of the light guide optical system 150, refer to, for example, JP-A-2006-209577 in addition to FIGS. 23A and 23B described later.

  When the anterior segment imaging mode is set, the control unit 70 adjusts the optical path length of at least one of the measurement light and the reference light, and the first detector 120a and the second detector 120b. The OCT data acquisition region by one of the first detector 120a and the second detector 120b may be set in the cornea, and the OCT data acquisition region by the other one may be set in the cornea. Here, the OCT data acquired by the first detector 120a and the OCT data acquired by the second detector 120b differ in at least a part of the acquisition region on the eye to be examined with respect to the depth direction. Thereby, OCT data including the cornea region and OCT data including the lens region may be acquired. In this case, the OCT data including the cornea region may include at least the cornea and the front surface of the lens, and the OCT data including the lens region may include at least the rear surface of the lens. That is, the OCT data of the front region in the anterior eye region and the OCT data of the rear region in the anterior eye region may be acquired separately.

  The control unit 70 may synthesize, for example, OCT data including the crystalline lens region and OCT data including the corneal region. In this case, the above-described synthesis process using the FPN signal may be used, so that the optical path length of the measurement light from the cornea and the crystalline lens coincides with the optical path length of the measurement light passing through the FPN generation optical system 200. The optical path length of the FPN generation optical system 200 may be set. In other words, in the state in which the optical path length difference between the measurement light of the light guide optical system 150 and the reference light is set so that OCT data including the cornea region and OCT data including the lens region can be acquired, FPN is added to each OCT data. The FPN generation optical system 200 may be set so that the signal is included.

  When the optical path length difference is adjusted, adjustment is made so that OCT data including the cornea region is acquired in a state where the front surface of the cornea is formed on the back side with respect to the zero delay position. It may be adjusted so that OCT data including the crystalline lens region is acquired in a state of being formed on the front side. Thereby, the influence by the mirror image at the time of image composition can be avoided. In addition, the first reference optical path 110a and the second reference optical path 110b are arranged so that a part of the acquisition region on the eye to be examined overlaps in the depth direction between the first OCT data and the second OCT data. The optical path length difference may be set. Thereby, connection in image composition can be performed smoothly.

  FIG. 12 is a diagram illustrating an example of OCT data acquired in the anterior ocular segment imaging mode. In the present embodiment, for example, the measurement is performed by moving the optical member arranged in the measurement optical path so that the optical path length of the measurement light from the crystalline lens matches the reference light from the first reference optical path 110a. The optical path length of light may be adjusted. Accordingly, at least the first OCT data obtained based on the output signal from the first detector 110a includes the OCT data of the crystalline lens region.

  In a state in which the position of the optical member arranged in the measurement optical path is adjusted so that the first OCT data includes the OCT data of the crystalline lens, for example, the control unit 70 includes the optical path length of the measurement light from the cornea, By moving the optical member 112 disposed in the second reference optical path 110b so that the reference light from the second reference optical path 110b matches, the optical path length of the reference light in the second reference optical path 110b is increased. It may be adjusted. Accordingly, the second OCT data obtained based on the output signal from the second detector 110b includes the corneal OCT data.

  When the OCT data of the crystalline lens and the OCT data of the cornea are acquired, for example, the control unit 70 may synthesize the OCT data of the crystalline lens and the OCT data of the cornea to acquire the combined OCT data. Furthermore, the control unit 70 may detect the corneal position, the lens position, and the like based on the synthetic OCT data, and measure the anterior chamber depth, the lens thickness, and the like of the eye to be examined.

<Correction of OCT data using FPN signal included in other OCT data>
The control unit 70 acquires OCT data including the FPN signal in one of the first OCT data and the second OCT data, and the OCT not including the FPN signal in the other of the first OCT data and the second OCT data. Data may be acquired. Further, the control unit 70 may obtain wave number mapping information based on the FPN signal in the OCT data including the FPN signal and correct the OCT data not including the FPN signal. According to this configuration, when a plurality of detectors are used, it is not always necessary to provide an FPN generation optical system according to each detector. In this case, the control unit 70 may correct the OCT data not including the FPN signal in real time, and according to this, the correction of the OCT data can be corrected with higher accuracy.

  In this case, for example, the control unit 70 adjusts the optical path length of at least one of the measurement light and the reference light, and sets an acquisition region of OCT data by one of the first detector 120a and the second detector 120b to a predetermined value. You may set to imaging | photography site | parts (for example, a fundus, a cornea, a crystalline lens). In addition, the control unit 70 sets an acquisition region of OCT data by the other of the first detector 120a and the second detector 120b in the optical member (for example, the optical member 204, the optical member 206) of the FPN generation optical system 200. To do.

  FIG. 13 is a diagram illustrating an example of applying real-time correction in the fundus photographing mode. For example, the control unit 70 adjusts the optical path length of at least one of the measurement light and the reference light, and sets an acquisition region of OCT data by one of the first detector 120a and the second detector 120b in the fundus ( (Refer to fundus photographing mode above).

  In addition, the control unit 70 sets an acquisition region of OCT data by the other of the first detector 120a and the second detector 120b in the optical member (for example, the optical member 204, the optical member 206) of the FPN generation optical system 200. To do. In this case, the optical path length of the FPN generation optical system 200 is set to a length different from the optical path length of the measurement light that reaches the detector 120a via the fundus. For example, the control unit 70 determines the measurement light and the reference light so that the optical path length of the reference light that passes through at least one of the plurality of reference optical paths matches the optical path length of the measurement light that passes through the FPN generation optical system 200. The optical path length difference between the two may be adjusted.

  In the present embodiment, for example, the measurement is performed by moving the optical member disposed in the measurement optical path so that the optical path length of the measurement light from the fundus coincides with the reference light from the first reference optical path 110a. The optical path length of light may be adjusted. Thereby, at least the first OCT data obtained based on the output signal from the first detector 110a includes fundus OCT data.

  In addition, in the state where the position of the optical member arranged in the measurement optical path is adjusted so that the first OCT data includes the OCT data of the fundus, the control unit 70, for example, By moving the optical member 112 arranged in the second reference optical path 110b so that the optical path length of the measurement light from the optical member of the system 200 matches the reference light from the second reference optical path 110b. The optical path length of the reference light in the second reference optical path 110b may be adjusted. Thus, the second OCT data obtained based on the output signal from the second detector 110b includes OCT data including the FPN signal. In this case, as a result, signals such as a cornea and a crystalline lens may be included in addition to the FPN signal.

  In the above description, the application example in the fundus imaging mode has been described. However, the present invention is not limited to this, and the above configuration may be applied in other imaging modes.

  In the above description, the OCT data including the FPN signal (for example, only the FPN signal) is acquired from one of the first OCT data and the second OCT data, and the first OCT data and the second OCT data On the other hand, when OCT data of an eye to be examined that does not include an FPN signal is acquired, the light path length adjustment is not limited to the above, and a light shielding member may be used. For example, the control unit 70 may obtain first OCT data that does not include FPN (for example, FPN1) by arranging the light blocking member 210 in the first optical path. In this case, since the light shielding member 212 is removed from the second optical path, second OCT data including FPN (for example, FPN2) is obtained. When only the FPN signal is obtained, correction using the FPN signal can be performed with high accuracy.

<Polarization adjustment>
The control unit 70 controls the polarization adjustment unit (for example, the first polarization adjustment unit 300, the second polarization adjustment unit 302, and the third polarization adjustment unit 304), and adjusts the polarization state when obtaining the OCT data. You may do it. The timing for adjusting the polarization state may be implemented, for example, when the power is turned on, or may be implemented every time the subject is changed. Further, it may be performed at the time of optimization control for optimizing imaging conditions in the OCT optical system.

  Hereinafter, the adjustment of the polarization state in the anterior segment imaging mode will be described as an example. FIG. 14 is a diagram illustrating an example of OCT data when polarization adjustment is performed in the anterior segment imaging mode. First, the control unit 70 controls the second polarization adjustment unit 302 to adjust the polarization state so that the signal intensity of the corneal image in the second OCT data is maximized. Thereby, a cornea image in the second OCT data is acquired with a good signal intensity.

  FIG. 15 is a diagram showing an example of FPN signal strength. Next, the control unit 70 controls the third polarization adjustment unit 304 to adjust the polarization state so that the signal intensity of the FPN signal in the second OCT data is maximized. Thereby, the FPN signal in the second OCT data is acquired with a good signal strength. As a result, the cornea image and the FPN signal in the second OCT data are acquired with good signal strength.

  Next, the control unit 70 controls the first polarization adjusting unit 300 so that the signal intensity ratio between the FPN signal in the second OCT data and the FPN signal in the first OCT data is a predetermined signal intensity ratio. (For example, the polarization state is adjusted so that the signal intensity ratios are equal to each other.) As a result, the FPN signal in the first OCT data is acquired with a good signal strength, and the crystalline lens image in the first OCT data is acquired with a good signal strength.

  According to the control as described above, the balance of the signal intensity between the first OCT data and the second OCT data can be adjusted. Further, in the adjustment of the polarization state of the OCT data including the crystalline lens, the polarization state using the crystalline lens image is obtained by using the signal intensity ratio between the FPN signal in the second OCT data and the FPN signal in the first OCT data. The polarization state is adjusted with higher accuracy than adjusting the. That is, the crystalline lens image in this case may be limited to only information on the rear surface of the crystalline lens, and since the amount of information as an image is relatively small, the accuracy as a signal evaluation value may be low. As a result, it may not be possible to adjust to a good polarization state. On the other hand, since the FPN signal is used, a stable signal strength can be secured, so that the accuracy as the signal evaluation value can be secured, and the polarization state can be adjusted well.

  In addition, in the case of the polarization state optimized only for the information on the back surface of the lens, a mismatch of the detected polarization occurs between the first OCT data and the second OCT data, thereby causing a connection region between the two. As a result, an intensity signal gap is generated. This is remarkable, for example, when the lens is in the gap position. In other words, the intensity signal of the lens (generally weak) becomes discontinuous, which can be fatal when trying to quantitatively evaluate turbidity. On the other hand, if the mismatch of the polarization detected between the first OCT data and the second OCT data is eliminated according to the present embodiment, such a gap does not occur.

  In the above description, since the FPN signal can be detected with high accuracy by adjusting the polarization state of the FPN generation optical system, various processes using the FPN signal can be appropriately performed.

  In the above description, the polarization state relating to the OCT data including the crystalline lens is adjusted using the FPN signal. However, the present invention is not limited to this, and the polarization state may be adjusted using the signal intensity of the entire crystalline lens image in the OCT data. Good.

  In the above description, when the first detector 120a and the second detector 120b are used, the OCT data obtained by the first detector 120a and the OCT data obtained by the second detector 120b Each OCT data can be acquired with a good signal intensity by adjusting the polarization state. Of course, the present invention is not limited to this, and the polarization state may be adjusted only for one of the OCT data.

  Moreover, when using any one of the 1st detector 120a and the 2nd detector 120b, a polarization state may be adjusted regarding the OCT data obtained by the detector used, for example.

<Wide-angle fundus shooting mode>
The fundus imaging mode may be a wide-angle fundus imaging mode for obtaining OCT data in a wide-angle region including the fundus center and the fundus periphery. Further, the normal fundus photographing mode as described above and the wide-angle fundus photographing mode may be switched. In the wide-angle fundus photographing mode, the scanning range of the measurement light on the fundus by the optical scanner 156 may be set to a wide-angle region including the center and the periphery of the fundus. In this case, a lens attachment for wide-angle shooting may be used. An example of the lens attachment will be described later with reference to FIGS.

  FIG. 16 is a diagram illustrating an example of OCT data acquired in the wide-angle fundus imaging mode. When the wide-angle fundus photographing mode is set, the control unit 70 adjusts the optical path length of at least one of the measurement light and the reference light, and obtains the OCT data acquisition region by the first detector 120a and the second detector 120b. May be set to a wide-angle region including the center of the fundus and the periphery of the fundus. For example, the control unit 70 sets the acquisition region of the OCT data by the first detector 120a in the center of the fundus and sets the acquisition region of the OCT data by the second detector 120b in the periphery of the fundus. Good. In the present embodiment, the first OCT data may be acquired by the first detector 120a, and the second OCT data may be acquired by the second detector 120b.

  Here, the eye has a spherical shape centered on the center of the eyeball, and the fundus has a concave shape with the center of the fundus at the bottom. However, the measurement light is swiveled around the center of the pupil to scan the fundus. Is done. In this case, the optical path length from the scanning center to the fundus periphery is shorter than the optical path length from the scanning center to the fundus center. Normally, the imageable range in the depth direction when obtaining the OCT data is a predetermined distance from the zero delay position, and when the fundus is scanned at a wide angle, there is a possibility that the imageable range is deviated from the imageable range in the depth direction.

  Therefore, for example, the optical path length difference between the first reference optical path 110a and the second reference optical path 110b is set in consideration of the optical path length difference between the fundus center and the fundus periphery, and the eye to be examined By adjusting the optical path length difference between the measurement light and the reference light with respect to the fundus, first OCT data including OCT data in the center of the fundus, second OCT data including OCT data in the vicinity of the fundus, Can be acquired. In this case, for example, the optical path length of the first reference optical path 110a is set in accordance with the optical path length of the measurement light from the center of the fundus, and the optical path length of the second reference optical path 110b is the measurement light from the periphery of the fundus. It may be set according to the optical path length. In this case, in consideration of the eyeball shape, the optical path length of the reference optical path 110b corresponding to the fundus periphery may be set shorter than the reference optical path 110a corresponding to the fundus center. Of course, in some cases, the optical path length of the reference optical path 110b corresponding to the fundus periphery may be set longer than the reference optical path 110a corresponding to the fundus center.

  For example, the OCT data of the fundus periphery included in the second OCT data is the OCT data in which the OCT data in the center of the fundus included in the first OCT data is continuous in at least one of the transverse direction and the depth direction at the end. It may be data. In this case, for example, part of each other's OCT data may be OCT data that overlaps at least one of the transverse direction and the depth direction and is continuous at the end. Note that the optical path length difference between the first reference optical path 110a and the second reference optical path 110b when obtaining the OCT data in the wide-angle region may be fixed or variable.

  For example, the first OCT data includes OCT data in a first fundus region including at least the macular region and the papilla of the fundus, and the second OCT data is outside of both ends of the first fundus region. Each region may be included. Further, the present invention is not limited to this, and the first OCT data includes OCT data in the first fundus region including at least the macular region of the fundus, and the second OCT data is obtained from both ends of the first fundus region. May also include outer regions, respectively.

  For example, the first OCT data and the second OCT data may have different data acquisition regions on the eye in the depth direction. In this case, between the first OCT data and the second OCT data, The optical path length difference between the first reference optical path 110a and the second reference optical path 110b may be set so that a part of the acquisition area on the eye to be examined overlaps in the depth direction. As a result, the connection process when the first OCT data and the second OCT data are combined can be performed smoothly.

  FIG. 17 is a diagram illustrating an example of combining OCT data acquired in the wide-angle fundus imaging mode. For example, the control unit 70 may acquire wide-angle OCT data based on the first OCT data and the second OCT data by combining the first OCT data and the second OCT data. In this case, the first OCT data and the second OCT data may be combined so as to be continuous in the depth direction.

  In this case, the control unit 70 may perform the synthesis process using the FPN signal described above, and the optical path length of the measurement light from the center and the peripheral part of the fundus and the measurement light that has passed through the FPN generation optical system 200. The optical path length of the FPN generation optical system 200 may be set so that the optical path lengths match.

  A state in which the optical path length difference between the measurement light and the reference light is set so that the first OCT data including the OCT data in the center of the fundus and the second OCT data including the OCT data in the vicinity of the fundus can be acquired. The FPN generation optical system 200 may be set so that each OCT data includes an FPN signal.

  Note that the synthesis process is not limited to the process using FPN. For example, the control unit 70 performs the first process by the matching process using the overlapping area between the first OCT data and the second OCT data. Data composition may be performed by defining the positional relationship between the OCT data and the second OCT data. In addition, the control unit 70 defines the positional relationship between the first OCT data and the second OCT data by using the optical path length difference between the first reference optical path 110a and the second reference optical path 110b. Synthesis may be performed. At this time, if there is an overlapping region, a signal with higher sensitivity may be adopted, or a side with less noise artifact may be adopted. Further, various kinds of smoothing processing may be performed at the connection portion so that a sudden change does not occur at the connection portion.

<Wide-angle shooting with one B-scan>
The control unit 70 controls the optical scanner 156, and scans the measurement light in a wide-angle region including the center portion and the peripheral portion of the fundus oculi by one B scan, and the first B scan OCT data and the second B scan. OCT data may be acquired (see FIG. 16).

  For example, when one B scan from the start point A to the end point D in the horizontal direction is performed, when the fundus region near the point B is scanned from the start point A, the output signal from the second detector 120b is used. Then, OCT data based on the reflected light and the reference light from the fundus periphery (left side) is acquired. Further, based on the output signal from the first detector 120a, OCT data based on reflected light and reference light from the fundus central part close to the fundus peripheral part (left side) is acquired.

  Next, when the fundus region from the vicinity of point B to the vicinity of point C is scanned, OCT data based on the reflected light from the center and the reference light is acquired based on the output signal from the first detector 120a. The Further, when the fundus region from the vicinity of the point C to the end point D is scanned, OCT data based on the reflected light and the reference light from the peripheral portion (right side) is acquired based on the output signal from the second detector 120b. Is done. Further, based on the output signal from the first detector 120a, OCT data based on the reflected light and the reference light from the fundus central part close to the fundus peripheral part (right side) is acquired.

  According to the above control, B-scan OCT data in a wide-angle region can be acquired smoothly. In this case, wide-angle B-scan OCT data may be acquired by combining the acquired first OCT data and second OCT data.

  In addition, B scans may be performed for a plurality of wide-angle regions on the fundus (for example, cross scan, multiline scan, radial scan, etc.). However, the present invention is not limited to this, and the wide-angle region including the fundus central part and the fundus peripheral part is divided into a plurality of times and B scan is performed to obtain the first B scan OCT data and the second B scan OCT data. May be.

  In addition, the control unit 70 scans the measurement light in a wide-angle region including the fundus central part and the fundus peripheral part in each scanning line by one raster scan, and performs the first three-dimensional OCT data and the second three-dimensional data. OCT data may be acquired. In this case, the measurement light is scanned with respect to a plurality of scanning lines constituting the raster scan. Each scanning line may have a scanning range corresponding to the wide-angle region. Thereby, the three-dimensional OCT data in the wide-angle region can be acquired smoothly. In this case, for example, the control unit 70 scans the measurement light a plurality of times for each scanning line constituting the raster scan, and based on a plurality of temporally different OCT data in each scanning line, a three-dimensional motion contrast at a wide angle. OCT data (OCT angio data) may be acquired.

  Note that the scanning range in one B-scan is not limited to the scanning range for the front image shown in FIG. 16, and this embodiment can also be applied to scanning a wide-angle fundus region. Needless to say. In this case, two reference optical paths may be used, or three or more reference optical paths may be used.

<Optical path length adjustment>
Hereinafter, an example of the optical path length adjustment in the wide-angle fundus photographing mode will be described below. In the present embodiment, for example, the optical member arranged in the measurement optical path is arranged so that the optical path length of the measurement light from the center of the fundus and the optical path length of the reference light from the first reference optical path 110a substantially coincide with each other. Thus, the optical path length of the measurement light may be adjusted. Thus, at least the first OCT data obtained based on the output signal from the first detector 110a includes OCT data including the fundus center.

  In a state where the position of the optical member arranged in the measurement optical path is adjusted so that the OCT data of the fundus center is acquired, for example, the control unit 70 determines the optical path length of the measurement light from the fundus periphery and the second By arranging the optical member 112 arranged in the second reference optical path 110b so that the optical path length of the reference light from the reference optical path 110b of the second reference optical path 110b substantially coincides, the optical path of the reference light in the second reference optical path 110b The length may be adjusted. As a result, the second OCT data obtained based on the output signal from the second detector 110b includes OCT data of the fundus periphery. In the above, instead of adjusting the optical path length of the measurement light, the optical path length of the reference light of the first reference optical path 110a may be adjusted.

<First embodiment regarding optical path length setting>
The optical path length of the first reference optical path 110a may be set so that the first OCT data is acquired in a state where the choroid at the center of the fundus is formed in front of the zero delay position (see FIG. 16). . According to this, for example, the deterioration of the choroid image due to sensitivity attenuation is reduced in the OCT data at the center of the fundus, and the mixing of the mirror image (virtual image) and the real image in the first OCT data can be reduced. .

  Further, the optical path length of the second reference optical path 110b may be set such that the second OCT data is acquired in a state where the retina in the vicinity of the fundus is formed on the back side with respect to the zero delay position (FIG. 16). According to this, for example, it is possible to reduce the deterioration of the image due to the decrease in the amount of light in the fundus periphery, and to reduce the mixture of the mirror image (virtual image) and the real image in the second OCT data.

  Note that when OCT data is obtained in a wide-angle region, the tendency that the amount of light decreases as it goes to the periphery appears prominently. This is because, due to the characteristics of the objective optical system, the center of the pupil does not necessarily match the fundus curvature, and there is a divergence between the direction of the irradiated light and the direction of the reflected and scattered light as it moves away from the center. It is because it ends. For example, the amount of return light at the position farthest from the center in the fundus periphery is the lowest. This is because, in the fundus OCT image, a saturated portion due to surface reflection occurs near the center where light is irradiated perpendicularly to the surface and coincides with the direction of the detection system, whereas this phenomenon is not seen in the peripheral portion. It is clear from As a result, the signal intensity at the fundus periphery tends to be lower than that at the fundus center. Furthermore, it is generally known that the optical performance of the light projecting system is reduced due to the occurrence of aberration as it becomes off-axis, and in view of the influence thereof, it can be said that the return light amount at the outermost periphery is unavoidable. The effect is not linear, and contributes at least by the square of the half angle of view, so that it becomes prominent as the system is widened.

  Therefore, considering the tendency that the amount of return light decreases toward the periphery and the sensitivity characteristic in the depth direction that the sensitivity increases as it approaches the zero delay position, the retina around the fundus is deeper than the zero delay position. By setting the optical path length so that the second OCT data is acquired in the state formed on the side, the sensitivity can be increased toward the periphery. Can be reduced.

  The first OCT data is acquired with the choroid at the center of the fundus formed in front of the zero delay position, and the second OCT data, the retina at the fundus periphery is more than the zero delay position. By being formed on the back side, it is possible to reduce the mixture of the mirror image and the real image in both the first OCT data and the second OCT data, and obtain the entire OCT data in a wide-angle region with a good signal intensity. Can do.

<Second embodiment regarding optical path length setting>
In the above description, the technique for reducing the mixture of the mirror image and the real image is illustrated, but the present invention is not limited to this. FIG. 18 is a diagram showing another example of OCT data acquired in the wide-angle fundus imaging mode. For example, when acquiring the second OCT data, the choroid in the fundus periphery is formed in front of the zero delay position, and the retina in the fundus center is formed in the back of the zero delay position. An optical path length may be set for the. In this case, a mixture of a mirror image when the fundus center is scanned and a real image when the fundus periphery is scanned occurs, but the fundus is a planar tissue with a relatively small thickness. The overlapping range is small, and it may be possible to use in fundus diagnosis by appropriately cutting out the use area.

  FIG. 19 is a diagram illustrating an example when the OCT data illustrated in FIG. 18 is synthesized. For example, when the first OCT data and the second OCT data are combined, the influence of the mirror image is generated by combining the peripheral data in the second OCT data and the central data in the first OCT data. Can be reduced.

  In addition to acquiring the second OCT data as described above, for example, when acquiring the first OCT data, the optical path length is set so that the choroid in the center of the fundus is formed in front of the zero delay position. May be set. As a result, the choroid side has high sensitivity in each OCT data, so that tissue changes in the choroid can be more easily discriminated in the wide-angle region.

<Third embodiment regarding optical path length setting>
For example, when acquiring the first OCT data, the optical path length is set so that the retina at the center of the fundus is formed on the back side with respect to the zero delay position, and at the periphery of the fundus from the zero delay position. The optical path length may be set so that the choroid is formed on the front side. In this case, a mixture of a mirror image when the fundus periphery is scanned and a real image when the fundus center is scanned occurs, but the fundus is a planar tissue having a relatively small thickness. The overlapping range is small and may be usable in fundus diagnosis.

  Further, for example, when the first OCT data and the second OCT data are combined, the peripheral image data in the second OCT data and the central portion data in the first OCT data are combined to create a mirror image. Can reduce the effects of

  In addition to acquiring the first OCT data as described above, for example, when acquiring the second OCT data, the optical path so that the retina in the fundus periphery is formed on the back side from the zero delay position. A length may be set. As a result, the retina side has high sensitivity in each OCT data, so that tissue changes in the retina can be more easily discriminated in the wide-angle region.

<Using multiple detectors for wide-angle photography>
FIG. 20 is a diagram illustrating an example when OCT data of the fundus center and the fundus periphery is obtained using a plurality of reference light paths and a plurality of detectors. FIG. 21 and FIG. 22 are diagrams showing an example when OCT data of the fundus center and the fundus periphery is obtained using one reference optical path and one detector. Note that ΔW in FIGS. 20 to 22 indicates a region where photographing can be performed while maintaining a predetermined amount of sensitivity with respect to the sensitivity at the zero delay position.

In this embodiment, by providing a reference optical path and detector for obtaining OCT data of the fundus central part and a reference optical path and detector for obtaining OCT data in the fundus peripheral part, OCT data around the fundus can be obtained simultaneously with good signal strength (see FIG. 20).
In this case, the first OCT data is acquired by one of the first detector 120a and the second detector 120b, and the second OCT is acquired by the other of the first detector 120a and the second detector 120b. Data may be acquired.

  In addition, when it is going to acquire OCT data of a fundus center part and a fundus periphery part simultaneously with only one reference optical path and one detector, the fundus center part is arranged in front of the zero delay position as a first configuration. (See FIG. 21), or as a second configuration, the fundus periphery may be arranged on the back side of the zero delay position (see FIG. 22). In this case, it is affected by the sensitivity attenuation characteristic in the depth direction in which the sensitivity decreases as the distance from the zero delay position increases, and the light intensity reduction characteristic in which the light intensity decreases toward the periphery.

  In the case of the first configuration, the retina and choroid near the center appear to have a relatively high contrast, but the image quality around the fundus is greatly reduced due to the double effect of the sensitivity attenuation characteristic and the light quantity reduction characteristic. Therefore, even if the image is taken at a wide angle, the sensitivity is not sufficient in the wide angle region, and the improvement of the diagnostic ability due to the wide angle must be limited. On the other hand, in the case of the second configuration, the retina and choroid near the periphery appear to have a relatively high contrast, but the image quality at the macula and papilla, which are important in fundus disease, is greatly reduced (see FIG. 21). In recent years, studies have been known that structural changes due to eye diseases appear in the vicinity of the choroid prior to the retina. In the case of the second configuration, the wide angle makes it possible to lower the diagnostic ability on the choroid side.

  In the above configuration, the detector is provided in each of the fundus central part and the fundus peripheral part. However, the detector may also be used in the fundus central part and the fundus peripheral part. The reference optical path may be selectively switched by an optical switch or the like. Even with such a configuration, OCT data of the fundus center and the fundus periphery can be obtained with good signal strength.

<Combination with anterior segment imaging mode>
In this embodiment, the reference optical path and detector for obtaining OCT data of the fundus central part and the reference optical path and detector for obtaining OCT data of the fundus peripheral part are arranged on the cornea and the front and rear surfaces of the lens. OCT data of the center and periphery of the fundus and OCT data of the anterior eye including the cornea and the front and back surfaces of the lens are obtained with good signal intensity by using the acquired OCT data of the anterior eye including OCT data for the entire eyeball can be obtained with good signal strength. Note that the anterior segment imaging mode has been described above, and a special description thereof will be omitted.

  Note that simultaneous detection is possible by using separate detectors for the cornea and the crystalline lens, but the cornea and the crystalline lens may also be used as a detector. In this case, for example, a plurality of reference optical paths are connected to an optical switch. It may be configured to selectively switch by, for example.

<Configuration related to switching of optical arrangement of light guide optical system>
Here, an example of a configuration related to switching of the optical arrangement of the light guide optical system 150 will be described with reference to FIGS. 23A and 23B.

  23A and 23B show an example in which an example of a configuration related to switching of the optical arrangement is applied to the light guide optical system 150. 23A and 23B, in order to switch the optical arrangement in the light guide optical system 150 according to the mode switching between the fundus imaging mode and the anterior ocular segment imaging mode, the first switching unit 410 and the second switching are mainly performed. The unit 420 is further provided in the OCT apparatus.

  As an example, the first switching unit 410 illustrated in FIGS. 23A and 23B includes mirrors 411 and 412, and changes the optical path length between the objective optical system 158 and the optical scanner 156 by moving the mirrors 411 and 412. (FIG. 23A-FIG. 23B). As a result of the change in the optical path length between the objective optical system 158 and the optical scanner 156, the focal position of the objective optical system 158 and the relative position of the optical scanner 156 are switched.

  The mirrors 411 and 412 in the first switching unit 410 shown in FIGS. 23A and 23B are disposed on the stage 440, and are moved by the drive unit 430 driving the stage 440. The objective optical system 158 and the optical scanner 156 are moved. Change the optical path length between. The driving unit 430 is driven by the control unit 70. Along with the change of the optical path length, the relative position is related to the first position (the position where the optical scanner 156 is arranged substantially coincident with the focal point of the objective optical system 156, see FIG. 23A) and the second position objective optical system 158. The position is switched between a position where the optical scanner 156 and the anterior eye portion are in a conjugate relationship (see FIG. 23B).

  In the case of the first position, the measurement light that has passed through the objective optical system 158 via the optical scanner 156 is light that is telecentric or near telecentric on the object side (that is, at or near an infinite point on the optical axis). The light having a turning point is irradiated on the eye E. As a result, OCT data can be acquired in a wide range of the anterior segment Ea.

  As described above, the relative position between the focal position in the objective optical system 158 and the optical scanner 156 is switched by the first switching unit 410, so that OCT data can be favorably acquired in each of the anterior segment and the fundus. However, at this time, the first switching unit 410 changes the optical path length difference between the measurement optical path and the reference optical path. In FIGS. 23A and 23B, at least a part of the variation in the optical path length difference is canceled by the second switching unit 420.

  In FIG. 23A and 23B, the 2nd switching part 420 has the mirrors 421-424. The second switching unit 420 is switched between a retracted state in which the mirrors 421 to 424 are retracted from the measurement optical path and an insertion state in which the mirrors 421 to 424 are disposed on the measurement optical path. Among the mirrors 421 to 424, the mirrors 421 and 422 are arranged on the stage 440, and the drive unit 430 drives the stage 440 to be inserted into and removed from the measurement optical path. When the mirrors 421 and 422 are inserted into the measurement optical path, the mirrors 421 to 424 form a bypass optical path, and the optical path length between the coupler 153 and the optical scanner 156 is increased before the insertion. In this way, the optical path length of the measurement optical path between the optical scanner 156 and the coupler 153 is changed by the second switching unit 420.

  Here, the mirrors 411 and 414 of the first switching unit 410 and the mirrors 421 and 422 of the second switching unit 420 are arranged on one stage 440, and each of the mirrors 411, 414, 421, and 422 is arranged. By integrally displacing, the first switching unit 410 and the second switching unit 420 are interlocked. That is, when the first switching unit 410 shortens the optical path between the optical scanner 156 and the eye E, the second switching unit 420 forms detour optical paths by the mirrors 421 to 424. As a result, the optical scanner The optical path from 156 to the coupler 153 is extended (FIG. 23B → FIG. 23A). At this time, the optical path length difference between the measurement optical path and the reference optical path is increased before and after the stage 440 is driven. As a result, the adjustment of the reference optical system after driving can be omitted or simplified. On the other hand, when the optical path between the optical scanner 156 and the eye E is shortened by the first switching unit 410, the mirrors 421 and 422 are retracted from the measurement optical path in the second switching unit 420. Thus, the bypass of the measurement light is eliminated, and as a result, the optical path from the optical scanner 156 to the coupler 153 is shortened (FIG. 23A → FIG. 23B). At this time, the optical path investigation of the measurement optical path and the reference optical path is reduced before and after the stage 440 is driven. As a result, the adjustment of the reference optical system after driving can be omitted or simplified. In addition, since the optical path length is adjusted in the two folded optical paths, the second switching unit 420 can reduce the drive amount and contribute to the compactness of the apparatus.

  In this way, a change in the optical path length in the measurement optical path (in other words, a change in the optical path length difference between the measurement optical path and the reference optical path) accompanying the change in the position of the turning point by the first switching unit 410 is caused by the second switching unit 420. It is reduced.

  In FIGS. 23A and 23B, the mirrors 411 and 412 in the first switching unit 410 and the mirrors 421 to 424 in the second switching unit 420 may be replaced with, for example, prisms.

<Removal of optical attachment>
In the OCT apparatus 1 having the light guide optical system 150 shown in FIGS. 23A and 23B, the first optical attachment 500 (see FIG. 24) or the second optical attachment 600 (see FIG. 25) may be detachable. . The optical attachments 500 and 600 are attached to the side surface of the subject-side casing of the OCT apparatus 1 in order to photograph the fundus. Both of the optical attachments 500 and 600 are attached to enlarge the photographing range on the fundus (that is, the scanning range of the measurement light) as compared to the case where the fundus photographing mode is not attached (see FIG. 23B). .

<First optical attachment worn in fundus photography mode>
When the light guide optical system 150 is in the fundus imaging mode (see FIG. 23B), the first optical attachment 500 is not attached to the fundus OCT data by being attached to the side of the subject-side casing. Compared to the state (that is, fundus photographing mode (see FIG. 23B)), the image can be acquired from a wider range.

  With reference to FIG. 24, an optical system when the first optical attachment 500 is mounted will be described. FIG. 24 shows the light guide optical system 150 with the first optical attachment 500 attached. For the sake of convenience, in FIG. 24, the optical scanner 156 to the eye E to be examined are shown more simply than in FIGS. 23A and 23B. A dotted line 170 indicates a side surface on the subject side in the housing of the OCT apparatus 1. In this embodiment, the light guide optical system 150 is accommodated in a housing. An inspection window (not shown) is provided in at least a region through which the measurement light passes on the side surface 170 of the housing. The inspection window transmits the measurement light passing through the objective optical system 150 toward the eye to be examined. The inspection window may be shared by a lens closest to the eye to be examined in the objective optical system 150. In the present embodiment, the first optical attachment 500 is attached to and detached from the inspection window. The OCT apparatus 1 may have a sensor 180 that detects attachment / detachment of the first optical attachment 500 in the vicinity of the inspection window. The detection signal output from the sensor 180 indicates the attachment / detachment state of the first optical attachment 500 and is input to the control unit 70.

  The control unit 70 automatically adjusts the optical path length difference between the measurement light and the reference light when a mounting signal (a signal indicating that the first optical attachment 500 is mounted or being mounted) is input. To do. When the first optical attachment 500 is attached, the optical path length from the coupler 153 to the fundus in the measurement optical path simply increases by that amount. The optical path length that increases at this time is, for example, the first switching unit 410, the first switching unit. 2 may be canceled by driving the switching unit 420 (see FIGS. 23A and 23B). For example, of the first switching unit 410 and the second switching unit 420, only the first switching unit 410 shortens the optical path length with respect to that before the first optical attachment 500 is mounted. As a result, the increase in the optical path length difference due to the mounting of the first optical attachment 500 may be at least partially offset. Of course, the optical path length in the reference optical system may be adjusted to be longer than that before the first optical attachment 500 is mounted.

<Second optical attachment mounted in the anterior segment imaging mode>
When the light guide optical system 150 is in the anterior ocular segment imaging mode (see FIG. 23A), the second optical attachment 600 is attached to the side surface of the subject-side casing, so that the OCT data of the fundus is obtained. Compared to the non-wearing state (that is, fundus photographing mode (see FIG. 23B)), the image can be acquired from a wider range. Although details will be described later, the change in the optical path length accompanying the attachment / detachment is reduced when the second optical attachment 600 is used, compared to the case where the first optical attachment 500 shown in FIG. 24 is attached / detached. It becomes easy to let you.

  With reference to FIG. 25, an optical system when the second optical attachment 600 is attached and detached will be described. FIG. 25 shows the light guide optical system 150 with the second optical attachment 600 mounted.

  In FIG. 25, the light guide optical system 150 is arranged so that the focal point of the objective optical system 158 coincides with the optical scanner 156, as in the anterior segment imaging mode (see FIG. 23A). Therefore, the measurement light is emitted from the objective optical system 158 to the eye E side as a light beam telecentric with respect to the optical axis L of the measurement optical path. The measurement light is guided to the eye E through the inspection window and the second optical attachment 600. The second optical attachment 600 has a positive power as a whole and forms a turning point P3 of the measurement light. The measurement light is scanned on the fundus by matching the pupil position of the eye E with the turning point P3. Thus, the second optical attachment 600 bends toward the optical axis L so that the telecentric light beam has an expected angle in the inspection window.

  By the way, the working distance when the optical attachment is mounted can be set longer as the maximum value of the height of the measuring light in the optical attachment is larger. Here, in the optical system shown in FIG. 24, the measurement light emitted from the objective optical system 158 always goes to the optical axis once between the objective optical system 158 and the first optical attachment 500. If it is going to obtain the height of the light beam to do, the optical path length in the 1st optical attachment 500 will become long easily. In contrast, in the optical system shown in FIG. 25, a telecentric light beam is incident on the second optical attachment 600. Therefore, the second optical attachment 600 can easily reach the intended light beam height with a shorter optical path length. Thereby, the 2nd optical attachment 600 can be formed more compactly. In addition, a change in the optical path length in the measurement optical path due to the attachment / detachment (insertion / detachment) of the second optical attachment 600 is relatively easily suppressed. As a result, it is advantageous in OPL adjustment accompanying the attachment / detachment (insertion / detachment) of the second optical attachment 600. In detail, it is considered that there is an advantage that the configuration for OPL adjustment can be easily simplified or the OPL adjustment can be completed more quickly.

  The second optical attachment 600 includes a first lens 601, a second lens 602, a third lens 603, and a fourth lens 604. The first lens 601, the second lens 602, the third lens 603, and the fourth lens 604 are arranged in this order from the objective optical system 158 toward the eye E to be examined. The first lens 601 belongs to the first lens group in this embodiment, and the second lens 602 to the fourth lens 604 belong to the second lens group in this embodiment. The first lens 601 is a main lens that increases the light beam height in order to ensure a working distance. The second lens 602 mainly contributes to aberration reduction. The third lens 603 and the fourth lens 604 are main lenses that bend the measurement light toward the optical axis L (in other words, lenses having a main positive power in the second optical attachment 600).

  The first lens 601 has a negative power and increases the height of the measurement light emitted from the objective optical system 158. The first lens 601 also reduces the occurrence of asymmetric aberrations and image plane distortion. Specifically, the first lens 601 has a meniscus shape in which the lens front surface and the lens rear surface are convex toward the eye to be examined. Such a meniscus shape suppresses the generation of aberrations asymmetric with respect to the optical axis L such as coma and astigmatism.

  Further, the first lens 601 is formed by joining two spherical lenses of a concave lens 601a and a convex lens 601b. Of the lenses 601a and 601b, the concave lens 601a is formed of a material having a higher refractive index. Thereby, the light beam height is likely to be favorably increased.

  Similarly to the first lens 601, the second lens 602 has a meniscus shape in which the lens front surface and the lens rear surface are convex toward the eye to be examined. Therefore, also in the second lens 602, the occurrence of an asymmetric aberration with respect to the optical axis L is suppressed. The second lens 602 has a concave lens 602a and a convex lens 602b joined. Of the lenses 602a and 602b, the convex lens 602b is formed of a material having a higher refractive index. That is, one of the convex lens and the concave lens forming the cemented lens, which is formed of a material having a high refractive index, is different between the first lens 601 and the second lens 602. As a result, at least a part of the curvature of field generated by the first lens 601 is canceled by the second lens 602, and as a result, the field distortion generated in the second optical attachment 600 is suppressed.

  In the present embodiment, the aberration suppression effect of the first lens 601 and the second lens 602 is weighted more in the field curvature than in the chromatic aberration. In this case, the condition to be satisfied by the two cemented lenses is expressed by the following equation.

  In this embodiment, N is the refractive index of the lens, and f is the focal length of the lens. The subscript 1p indicates that the convex lens 601a, 1n is the concave lens 601b, 2p is the convex lens 602a, and 2n is the value for the concave lens 602b.

  In addition, the solid angle Ωa indicating the scanning range of the measurement light in the vicinity of the turning point P3 when the second optical attachment 600 is attached is measured in the vicinity of the turning point P1 in the fundus photographing mode in the non-attached state (see FIG. 23B). It is preferably larger than twice (more preferably 3 times or more) the solid angle Ωb indicating the light scanning range.

  The optical attachment 500 shown in FIG. 24 is attached to the apparatus in the anterior ocular segment imaging mode, thereby widening the scanning range of the measurement light on the fundus.

  When the optical attachment 500 is attached, the optical path length from the coupler 153 to the fundus is increased. At this time, the increasing optical path length may be canceled by the first switching unit 410 and the second switching unit 420. For example, of the first switching unit 410 and the second switching unit 420, only the first switching unit 410 shortens the optical path length before the optical attachment 500 is mounted, and thereby the optical path due to the mounting of the optical attachment 500. The increase in length difference may be offset at least in part.

  In FIG. 24, the first switching unit 410 and the second switching unit 420 are integrally driven by a common driving unit 430, but can be driven independently of the first switching unit 410 and the second switching unit 420. In some cases (in other words, each of the first switching unit 410 and the second switching unit 420 includes a driving unit), the optical path when the optical attachment 500 is mounted by driving only the second switching unit 420. An increase in the length difference may be suppressed. That is, the second switching unit 420 discretely changes the optical path length difference by a certain amount. The amount of change and the amount of change in the optical path length difference that increases when the attachment is attached may coincide with each other.

  In the OCT apparatus 1, attachment / detachment of the second optical attachment 600 may be detected by the sensor 180. When a plurality of optical attachments (specifically, the optical attachments 500 and 600) are attached as in the present embodiment, the sensor 180 may further detect the type of the optical attachment to be attached.

  The control unit 70 automatically adjusts the optical path length difference between the measurement light and the reference light when a mounting signal (a signal indicating that the second optical attachment 600 is mounted or being mounted) is input. To do. When the second optical attachment 500 is mounted, the optical path length of the measurement light is increased not only by the optical path length of the second optical attachment 600 but also by the optical path length from the anterior segment to the fundus. The optical path length that increases at this time may be offset by driving the first switching unit 410 and the second switching unit 420 (see FIGS. 23A and B), for example. Of course, the optical path length in the reference optical system may be adjusted to be longer than that before the second optical attachment 600 is mounted.

  In addition, when the sensor 180 detects not only the attachment state of the optical attachment attached to the inspection window but also the type, the control unit 70 varies the adjustment amount of the optical path length according to the type of the optical attachment. May be.

  In the above description, SS-OCT is taken as an example, but the present invention is not limited to this, and the present embodiment may be applied to SD-OCT. In this case, a plurality of spectrometers may be used as the plurality of detectors.

  In the above description, the OCT apparatus for imaging the eye to be examined has been described as an example. Also good. The test object may be, for example, a living body such as an eye (anterior eye portion, fundus, etc.), skin, or a material other than a living body.

  In the above description, SS-OCT is taken as an example, but the present invention is not limited to this, and the present embodiment may be applied to SD-OCT. In this case, a plurality of spectrometers may be used as the plurality of detectors.

  In the above description, the OCT apparatus for imaging the eye to be examined is taken as an example. However, the present embodiment is not limited to this, and the present embodiment is applied to an OCT apparatus for imaging OCT data of the object to be examined. Also good. The test object may be, for example, a living body such as an eye (anterior eye portion, fundus, etc.), skin, or a material other than a living body.

It is a figure which shows an example of the OCT apparatus which concerns on a present Example. It is a figure which shows an example of the FPN production | generation optical system which concerns on a present Example. It is a figure which shows an example of the data at the time of synthesize | combining several OCT data using a FPN signal, and is a figure which shows before a synthesis | combination. It is a figure which shows an example of the data at the time of synthesize | combining several OCT data using a FPN signal, and is an image figure after a synthesis | combination. It is a figure which shows the example of a data change in the case of synthesize | combining several OCT data using a FPN signal. It is a figure which shows the example of a data change in the case of combining several OCT data using an FPN signal. It is a figure which shows an example of OCT data used for wave number mapping correction | amendment. It is a figure which shows an example of the wave number mapping information obtained by processing FPN. It is a figure which shows an example for correct | amending a mapping state, when calculating | requiring the difference information (DELTA) (phi) (k) between 1st wave number mapping information (phi) 1 (k) and 2nd wave number mapping information (phi) 2 (k). It is a figure which shows an example of the OCT data acquired in fundus imaging mode. It is a figure which shows an example of the OCT data acquired in an axial length imaging | photography mode. It is a figure which shows an example of the OCT data acquired in anterior eye part imaging | photography mode. It is a figure which shows an example in the case of applying real time correction in fundus photography mode. It is a figure which shows an example of OCT data in case polarization adjustment is performed in the anterior ocular segment imaging mode. It is a figure which shows an example of the signal strength of FPN. It is a figure which shows an example of OCT data acquired in wide-angle fundus imaging mode. It is a figure which shows an example at the time of synthesize | combining the OCT data acquired in wide-angle fundus imaging mode. It is a figure which shows the other example of OCT data acquired in wide-angle fundus imaging mode. It is a figure which shows an example at the time of synthesize | combining the OCT data illustrated in FIG. It is a figure which shows an example at the time of obtaining OCT data of a fundus center part and a fundus periphery part using a plurality of reference light paths and a plurality of detectors. It is a figure which shows the example which concerns on a 1st structure at the time of obtaining OCT data of a fundus center part and a fundus periphery part using one reference optical path and one detector. It is a figure which shows the example which concerns on a 2nd structure at the time of obtaining OCT data of a fundus center part and a fundus periphery part using one reference optical path and one detector. It is a figure for demonstrating the switching operation | movement of an optical arrangement | positioning in a light guide optical system. The optical arrangement in the anterior segment imaging mode is shown. It is a figure for demonstrating the switching operation | movement of an optical arrangement | positioning in a light guide optical system. The optical arrangement in fundus photographing mode is shown. It is a figure explaining the switching operation | movement of the optical arrangement | positioning in a light guide optical system by the attachment or detachment of a 1st optical attachment. It is a figure explaining the switching operation | movement of the optical arrangement | positioning in a light guide optical system by the attachment or detachment of a 2nd optical attachment.

70 control unit 100 interference optical system 102 light source 104 coupler 130 coupler 150 light guide optical system 156 optical scanner 158 objective optical system 600 optical attachment

Claims (21)

A spectral interference signal between the measurement light guided to the eye to be examined via the measurement optical path and the reference light from the reference optical path, having an optical splitter for dividing the light from the OCT light source into the measurement optical path and the reference optical path OCT optical system for detecting
An optical scanner disposed on the measurement optical path and deflecting the measurement light from the optical splitter and scanning the tissue of the eye to be examined;
The measurement light path is disposed between the optical scanner and the eye to be examined, and guides the measurement light that has passed through the optical scanner to the first light collection surface without intersecting the optical axis of the measurement optical path, An objective optical system for condensing the measurement light on the first condensing surface;
An optical attachment that is inserted into and removed from the measurement optical path between the objective optical system and the eye to be examined.
The optical attachment is inserted into the measurement optical path, thereby bending the measurement light that has passed through the objective optical system toward the optical axis, and at a position conjugate with the optical scanner with respect to the objective optical system and the optical attachment. An OCT apparatus that forms a turning point of measurement light and collects the measurement light that has passed through the turning point on a second light collection surface. A housing that houses at least a part of the OCT optical system, the optical scanner, and the objective optical system;
Provided on the side surface of the case on the eye side to be examined, and an inspection window through which the measurement light passing through the objective optical system passes,
The OCT apparatus according to claim 1, wherein the optical attachment is inserted into and removed from the measurement optical path by being attached to and detached from the inspection window. The optical attachment has a second solid angle indicating the scanning range of the measurement light in the vicinity of the turning point larger than a first solid angle indicating the scanning range of the measurement light in the vicinity of the optical scanner. The OCT apparatus according to claim 1, wherein the measurement light that has passed through the objective optical system is bent toward the optical axis.
The optical attachment has the second solid angle that is the scanning solid angle of the measurement light at the turning point larger than the first solid angle that is the scanning solid angle of the measurement light in the optical scanner. The OCT apparatus according to claim 1, wherein the telecentric light beam is bent toward the optical axis.   The OCT apparatus according to claim 1, wherein the optical attachment is a lens attachment including one or more lenses.   The OCT apparatus according to claim 4, wherein the optical attachment includes a first lens group having a negative power and a second lens group having a positive power arranged in order from the objective optical system toward the eye to be examined. .   The optical attachment has a cemented lens in which a lens having a negative power and a lens having a positive power are bonded to one or each of the first lens group and the second lens group. The OCT apparatus according to claim 5.   The OCT apparatus according to claim 5, wherein the cemented lens corrects at least one of an asymmetrical aberration and a field curvature.   The OCT apparatus according to claim 5, wherein the cemented lens has a field curvature component in consideration of curvature on a surface of the fundus.   The second lens group includes the cemented lens, and further includes a lens that bends the measurement light toward the optical axis at a position where the height of the light beam with respect to the optical axis is the highest, separately from the cemented lens. The OCT apparatus in any one of 8-8.   The second lens group includes the cemented lens, and the lens having negative power in the cemented lens is formed of a material having a refractive index lower than that of a lens having positive power. An OCT apparatus according to the above. The OCT apparatus according to claim 6, wherein the cemented lens is formed in a meniscus shape in which a lens front surface and a lens rear surface are convex toward the eye to be examined.
⇒Asymmetric aberrations are less likely to occur on the optical axis.   Each of the first lens group and the second lens group includes the cemented lens, and a lens having higher dispersion among a negative power lens and a positive power lens constituting the cemented lens. The OCT apparatus according to claim 6, wherein the first lens group and the second lens group are different from each other. Each of the first lens group and the second lens group includes the cemented lens,
The contribution of the measurement light to the refraction of the cemented lens of the second lens group is smaller than that of the cemented lens of the first lens group, and the contribution to the correction of the field curvature of the cemented lens of the second lens group. The OCT apparatus according to claim 6, which is larger than a cemented lens in the first lens group. A spectral interference signal between the measurement light guided to the eye to be examined via the measurement optical path and the reference light from the reference optical path, having an optical splitter for dividing the light from the OCT light source into the measurement optical path and the reference optical path OCT optical system for detecting
An optical scanner disposed on the measurement optical path and deflecting the measurement light from the optical splitter and scanning the tissue of the eye to be examined;
An objective optical system disposed between the optical scanner and the eye to be examined on the measurement optical path;
A lens attachment that is inserted into and removed from the measurement optical path between the objective optical system and the eye to be examined.
The lens attachment bends the measurement light that has passed through the objective optical system toward the optical axis and forms a positive turning point of the measurement light at a position conjugate with the optical scanner with respect to the objective optical system and the optical attachment. An OCT apparatus comprising: a lens having power; and an aberration correction lens that corrects at least one of the asymmetrical aberration and the field curvature.   The OCT apparatus according to claim 14, wherein the aberration correction lens has a component of curvature of field in consideration of curvature on the surface of the fundus.   16. The OCT apparatus according to claim 15, wherein each lens in the lens attachment is a spherical lens, and the aberration correction lens is a cemented lens in which lenses having different refractive indexes are bonded together.   The OCT apparatus according to claim 16, wherein the aberration correction lens is formed in a meniscus shape in which a lens front surface and a lens rear surface are convex toward the eye to be examined.   Performing the switching operation of switching at least a part of the optical path length in the reference optical path and the optical path length from the light splitting unit to the objective optical system in the measurement optical path, and performing the measurement accompanying insertion / removal of the optical attachment The OCT apparatus according to claim 1, further comprising a correction unit that cancels at least part of a change in optical path length difference between an optical path and the reference optical path. Having detection means for detecting an insertion / removal state of the optical attachment;
The OCT apparatus according to claim 18, wherein the correction unit performs the switching operation based on a detection signal from the detection unit. A spectral interference signal between the measurement light guided to the eye to be examined via the measurement optical path and the reference light from the reference optical path, having an optical splitter for dividing the light from the OCT light source into the measurement optical path and the reference optical path An OCT optical system for detecting light, an optical scanner that deflects the measurement light and scans the tissue of the eye to be examined, and the measurement light that is disposed between the optical scanner and the eye to be examined and passes through the optical scanner An objective optical system for guiding the measurement light onto the first light collection surface without crossing the optical axis of the measurement light path, and focusing the measurement light on the first light collection surface. An optical attachment that is attached to and detached from the inspection window,
By having one or more lenses and being attached to the inspection window, the measurement light that has passed through the objective optical system is bent toward the optical axis, and the objective optical system and the optical attachment are conjugate with the optical scanner. An optical attachment that forms a turning point of the measurement light at a position and condenses the measurement light that has passed through the turning point on a second light collection surface. A spectral interference signal between the measurement light guided to the eye to be examined via the measurement optical path and the reference light from the reference optical path, having an optical splitter for dividing the light from the OCT light source into the measurement optical path and the reference optical path An OCT optical system for detecting light, an optical scanner that deflects the measurement light and scans the tissue of the eye to be examined, and the measurement light that is disposed between the optical scanner and the eye to be examined and passes through the optical scanner An objective optical system for guiding the measurement light onto the first light collection surface without crossing the optical axis of the measurement light path, and focusing the measurement light on the first light collection surface. An optical attachment that is attached to and detached from the inspection window,
A lens having a positive power for bending the measurement light that has passed through the objective optical system toward the optical axis to form a turning point of the measurement light at a position conjugate with the optical scanner with respect to the objective optical system and the optical attachment; An aberration correction lens that corrects at least one of the asymmetrical aberration and the field curvature.

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