JP7119286B2 - OCT device - Google Patents

Description

The present disclosure relates to an OCT apparatus for obtaining OCT data of a subject (eg, eye).

As an OCT apparatus for obtaining OCT data of a subject, for example, an apparatus capable of obtaining OCT data by processing a spectral interference signal output from an OCT optical system is known. An arrangement for is disclosed. For example, whole-eye OCT that can image both the anterior segment and the fundus has been proposed.

For example, in the apparatus of Patent Literature 1, the positional relationship of different depth information is set on the basis of a reference interference signal from a reference portion provided in either the measurement optical path or the reference optical path, and a composite tomographic image is obtained.

JP 2016-32609 A

However, in the case of the apparatus disclosed in Patent Document 1, the following problems are conceivable. For example, when using a plurality of reference optical paths, it is necessary to switch and select the reference optical paths, which makes it difficult to simultaneously acquire a plurality of reference interference signals. As a result, it may be affected by fluctuations in the light source or the like. Also, since the reference optical system is arranged in series, there is a possibility that the signal from the reference optical system is attenuated.

In addition, the method using multiple reference optical paths is susceptible to the effects of multiple reflections from the reference optical system and, especially in the case of SS, false signals due to coherence revival, making it difficult to detect only specific signals.

A technical object of the present invention is to provide an OCT apparatus that can solve at least one of the problems of the prior art and that can satisfactorily acquire tomographic images over a wide range.

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

(1) Having a first light splitter for splitting the light from the OCT light source into the measurement optical path and the reference optical path, the measurement light guided to the test object via the measurement optical path and the reference light from the reference optical path An OCT apparatus comprising an OCT optical system for detecting a spectral interference signal from the OCT optical system and capable of acquiring OCT data of a subject by processing the spectral interference signal output from the OCT optical system,
The OCT optical system is
a first reference optical path as the reference optical path and a second reference optical path different from the first reference optical path;
a first detector for detecting a first interference signal between the reference light from the first reference optical path and the measurement light;
a second detector different from the first detector for detecting a second interference signal between the reference light from the second reference optical path and the measurement light; ,
an FPN generation optical system for generating an FPN signal , comprising at least one optical member for generating an FPN signal;
The measurement optical path is divided into an optical path toward the test object and an optical path of the FPN generation optical system, and the light from the test object and the light from the FPN generation optical system are separated without passing through the first optical splitter. a second light splitter for splitting into a light path towards a first detector and a light path through said first light splitter towards said second detector;
The first detector and the second detector are capable of detecting the FPN signal, and capable of simultaneously acquiring two pieces of OCT data each corrected based on the FPN signal,
The light amount division ratio of the reflected light from the test object by the second light splitter is: optical path toward the first detector<optical path toward the second detector via the first light splitter It is characterized by

According to the present disclosure, it is possible to solve at least one problem of the conventional technology and obtain a wide range tomographic image satisfactorily.

An example of an embodiment of the present disclosure will be described based on the drawings. 1 to 19 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 may include an OCT optical system and be capable of acquiring OCT data by processing spectral interference signals output from detectors 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). and detecting a spectral interference signal between the measurement light directed to the test object via the measurement light path and the reference light from the reference light path.

<Multiple detectors, FPN optical system>
The OCT optical system may comprise multiple reference optical paths, for example, a first reference optical path and a second reference optical path different from the first reference optical path. In this case, for example, the OCT optical system includes a first detector for detecting a first interference signal between the reference light and the measurement light from the first reference optical path, and a second detector different from the first detector. Two detectors may be provided, a second detector for detecting a second interference signal between the reference light and the measurement light from the second reference optical path.

<FPN optical system>
The OCT optics may be provided with FPN generation optics for generating FPN signals, for example, the FPN generation optics may comprise at least one optical member for generating FPN. The FPN generation optical system may be arranged in the measurement optical path or may be arranged in the reference optical path. Note that FPN is Fixed Pattern Noise, which is generated as a fixed noise signal on OCT data, for example.

At least one of the first detector and the second detector can detect FPN signals and can use the FPN signals to correct OCT data (eg, image synthesis, correction of mapping conditions, etc.). Good OCT data can be obtained by using the FPN signal. In this case, both the first detector and the second detector may be capable of detecting the FPN signal, so that processing using the FPN signal can be performed with higher accuracy.

<Second optical splitter>
The OCT optics may comprise a second light splitter, for example a second light splitter provided for splitting the measurement light path into the light path towards the test object and the light path of the FPN generation optics. may be For example, the second optical splitter further divides the light from the test object and the light from the FPN generation optical system into an optical path toward the first detector and a second optical path through the first optical splitter. and a light path towards the detector.

Here, the OCT optical system has a first optical path that guides the reflected light from the test object to the first detector via the second light splitter without passing through the first light splitter; and a second optical path that guides the reflected light from the test object to the second detector via the second optical splitter and the first splitter. can lead to

Note that the OCT optical system is not limited to the above configuration, and the reflected light from the test object passes through the first detector and the second light splitter without passing through the first light splitter. It may be configured to have an optical path leading to the detector. In this case, the OCT optical system directs the reflected light from the test object to the first detector on the detector side of the second light splitter. A third light splitter may be provided to split the light path into a light path towards the second detector and a light path towards the second detector.

<Light amount division ratio>
Regarding the light amount division ratio of the reflected light from the test object by the second light splitter, the light amount division ratio is such that the light path toward the first detector < the second detector via the first light splitter may be set so as to be an optical path directed to . Thereby, the first interference signal detected by the first detector and the second interference signal detected by the second detector can be detected with an appropriate balance.

Further, the light amount division ratio of the second light splitter may be set such that the light path toward the light source<the light path toward the second detector. Thereby, reflected light from the test object can be efficiently guided to the second detector.

Regarding the light amount division ratio of the first light splitter and the second light splitter, as a result, the light amount ratio of the light path toward the first detector and the light amount of the light path toward the second detector are the same. may be set to each other. This makes it possible to equalize the intensities of the first interference signal and the second interference signal, and as a result, it is possible to obtain good OCT data based on each interference signal.

In addition, regarding the light amount division ratio of the first light splitter and the second light splitter, the difference in the reflected light amount at the imaging site of the OCT data detected by the first detector and the second detector is taken into consideration. , the light amount division ratio may be set.

<Image synthesis using FPN>
The OCT apparatus may include, for example, a processing unit (eg, processor) for processing spectral interference signals output from the OCT optics to obtain OCT data of the subject. In this case, the arithmetic processing unit, for example, combines the first OCT data based on the first interference signal and the second OCT data based on the second interference signal with the FPN detected by the first detector. Synthetic OCT data may be obtained by synthesizing based on the FPN detected by the second detector. Thereby, a plurality of OCT data can be synthesized with high accuracy. The synthesis compensates for areas lacking in one piece of OCT data.

In this case, the arithmetic processing unit obtains relative position information of the two OCT data by using the FPN generated by the optical member for FPN generation to synthesize the OCT data, and synthesizes the data accurately. can be done. For example, the arithmetic processing unit may use the FPN generated by the surface reflection of the optical member for FPN generation to synthesize the OCT data. can. Of course, the arithmetic processing unit may synthesize OCT data using FPN generated by back surface reflection or a coated surface. In this case, the signal intensity is attenuated, but as data synthesis A certain effect can be obtained.

In the above configuration, for example, the FPN generation optical system includes a first optical member that generates a first FPN and a second optical member that generates a second FPN at a position different from the first FPN. FPN generation optics for at least comprising and generating at least two FPN signals.

In this case, the arithmetic processing unit, for example, combines the first OCT data based on the first interference signal and the second OCT data based on the second interference signal with the first data detected by the first detector. Synthetic OCT data may be obtained by combining based on the FPN due to the first optical member and the FPN due to the second optical member detected by the second detector. According to this, for example, the imaging range in the depth direction can be widened. In this case, for example, the first OCT data and the second OCT data may be aligned based on the distance between the FPN by the first optical member and the FPN by the second optical member.
For example, when imaging a certain range of a common portion with two OCT systems, overlapping regions between different data can be reduced. Furthermore, there may be a discontinuous area between the two imaging areas. When imaging the anterior segment, the first OCT data may include the anterior surface of the cornea to the anterior surface of the lens, and the second OCT data may include only the posterior surface of the lens. Such a configuration is particularly useful when the two OCT systems have different detectors and different depth ranges.

The FPN generation optical system may include an optical path dividing member, the first optical member is arranged in the first optical path divided by the optical path dividing member, and the second optical member is arranged in the first optical path divided by the optical path dividing member. It may be arranged in a split second optical path. When two FPN signals are used, the signal strength of each should be equally high, as the less sensitive signal will reduce the accuracy, so that the light from each optical element can be controlled independently. becomes. In this case, for example, the first optical path and the second optical path may have different optical path lengths, and the amount of dispersion in the first optical path may be equal to the amount of dispersion in the second optical path. As a result, the effect of dispersion on each FPN signal can be made uniform, each FPN signal can be uniformly detected, and image synthesis can be performed with high accuracy. Moreover, it is even better if the optical path length difference is small enough to fit both within the acquisition range of the first or second OCT data. By acquiring and analyzing OCT data such that both are within the acquisition range, the separation of the two FPNs can be calibrated at arbitrary timing. For example, the position of the FPN itself may fluctuate depending on the operating environment (temperature, etc.) of the apparatus, and the separation of the FPN may also fluctuate due to the influence of wavelength shifts due to aged deterioration of the light source. However, by using information about the distance between FPNs when synthesizing according to the present embodiment, and by performing measurement and calibration at arbitrary timing, images can be stably synthesized for a long time.

The first optical path and the second optical path have different optical path lengths within the depth-range of at least one of the OCT channels, and the dispersion amount of the first optical path and the dispersion of the second optical path are may be equal in quantity. This allows accurate calibration in one OCT channel.

In the above description, data synthesis using an FPN generation optical system for generating at least two FPN signals is shown, but the present invention is not limited to this. Different OCT data may be generated using FPN signals from members. In this case, the configuration of the FPN generation optical system can be simplified.

<Wavenumber mapping correction>
The arithmetic processing unit may use the FPN signal both to synthesize OCT data and to obtain correction information for correcting the mapping state of each wavenumber component. Thereby, the correction information of the wave number mapping can be acquired with high accuracy, and the synthetic OCT data can be preferably acquired.

In this case, for example, the arithmetic processing unit processes the FPN signals detected by the first detector and the second detector, and maps each wavenumber component based on the mapping information of each wavenumber component based on the FPN signal. Correction information for correcting the condition may be obtained, and first OCT data based on the first interference signal and second OCT data based on the second interference signal may be obtained using the correction information. . Furthermore, the arithmetic processing unit may synthesize based on the FPN detected by the first detector and the FPN detected by the second detector.

<Polarization adjustment mechanism>
For example, a polarization adjuster (polarizer) may be provided in the optical path of the OCT optical system, and the polarization adjuster may be provided to adjust the polarization state of at least one of the measurement light and the reference light. . The polarization adjuster may be arranged in at least one of the optical path of the measurement light and the optical path of the reference light. The polarization adjuster may be arranged in an optical path after the optical path of the measurement light and the optical path of the reference light are branched, and used to match the polarization states of the measurement light and the reference light.

For example, the polarization adjuster may rotate the optical fiber in the optical path or apply pressure to adjust the polarization direction. Also, the polarization adjusting section may adjust the polarization direction using a half-wave plate or a quarter-wave plate. Also, the polarization adjusting section may be realized by combining a prism (for example, a Fresnel Rhomb) or the like having the same effect as a half-wave plate or a quarter-wave plate. The polarization adjusting section may be configured to be able to adjust the polarization direction between at least linearly polarized S-polarized light, linearly polarized P-polarized light, and circularly polarized light.

The polarization adjuster may be arranged, for example, in at least one of the first reference optical path and the second reference optical path, and adjust the polarization state of the reference light. In this case, for example, a plurality of polarization adjustment units may be provided. The polarization state of the reference light passing through the second reference light path and the polarization state of the reference light passing through the second reference light path may be adjusted. Further, as a second example, the polarization adjustment section is arranged in either one of the first reference optical path and the second reference optical path and the measurement optical path, and is arranged in either the first reference optical path or the second reference optical path. The polarization state of the reference light passing through one and the polarization state of the measurement light passing through the measurement optical path may be adjusted. By providing a plurality of polarization adjustment units in this way, for example, the first OCT data based on the first detector and the second OCT data based on the second detector can be properly adjusted. detectable at

In the OCT apparatus, a polarization controller may be provided for controlling the polarization adjusters, for example, the controller controls the plurality of polarization adjusters to obtain first OCT data from a first detector and a first The polarization state may be adjusted such that the second OCT data based on the two detectors each meet predetermined tolerances. In this case, the predetermined permissible condition may be, for example, a state in which the OCT data reaches a predetermined signal strength, or a state in which the signal strength of the OCT data reaches near its peak. In this case, by adjusting the polarization state based on the first OCT data and adjusting the polarization state based on the second OCT data, each OCT data can be acquired in a favorable state. In this case, for example, an evaluation value for evaluating the signal intensity may be calculated each time the polarization state is changed, and the polarization state may be adjusted based on the evaluation value.

Also, for example, the polarization control unit controls the polarization adjustment unit so that the signal intensity ratio between the FPN detected by the first detector and the FPN detected by the second detector satisfies a predetermined allowable condition. The polarization state may be adjusted to satisfy. In this case, the predetermined permissible condition may be, for example, a state in which the signal strength ratio reaches a predetermined signal strength ratio, or a state in which the signal strength difference is the smallest. In this case, for example, an evaluation value for evaluating the signal intensity may be calculated each time the polarization state is changed, and the polarization state may be adjusted based on the evaluation value. Moreover, when the variance of the FPN signal is equal in the first or second OCT data, the similarity of the signal spread (PSF) may be used for evaluation. For example, each FPN has a unique sidelobe due to the distribution of the light source, but when the peak heights are multiplied by a factor, the correlation (degree of overlap) between the two will determine the degree of matching of the polarization. may be judged.

Note that the polarization adjustment unit may be arranged, for example, in the optical path of the FPN generation optical system and provided to adjust the polarization state of light passing through the FPN generation optical system. In this case, for example, the polarization controller may control the polarization adjuster to adjust the signal strength of the FPN signal acquired by either of the two OCT systems. As a result, the FPN signal can be obtained with an appropriate signal strength, so various processes using the FPN signal can be properly performed. After that, if the other OCT system has another polarization adjustment member, this may be controlled so that the same FPN performs polarization adjustment according to a predetermined intensity ratio or PSF characteristic.

<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-swept OCT (SS-OCT: Swept Source-OCT) as a basic configuration, a variable wavelength light source 102, an interference optical system (OCT optical system) 100, an arithmetic controller ( Arithmetic 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 controller) 70 is connected to the variable wavelength light source 102 , the interference optical system 100 , the memory 72 and the display 75 .

The interference optical system 100 guides the measurement light to the eye E by the light guiding optical system 150 . Interference optical system 100 guides reference light to reference optical system 110 . The interference optical system 100 causes the detector (light receiving element) 120 to receive interference signal light obtained by interference between the measurement light reflected by the eye E and the reference light. Furthermore, 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 (apparatus main body) (not shown), and the housing is three-dimensionally moved with respect to the eye E by a well-known alignment movement mechanism via an operation member such as a joystick. Alignment with respect to the subject's eye may be performed by .

The interference optical system 100 employs the SS-OCT method, and a wavelength variable light source (wavelength scanning light source) that changes the emission wavelength at high speed as the light source 102 is used. The light source 102 is composed of, for example, a laser medium, a resonator, and a wavelength selective 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 also be used as the light source 102 .

A 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. The coupler 104, for example, guides the light from the light source 102 to the optical fiber 105 on the measurement optical path side and to the reference optical system 110 on the reference optical path side.

A coupler (splitter) 130 is used as a second optical splitter and splits the 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. Coupler (splitter) 130 may be a beam splitter or a circulator.

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

The optical scanner 156 may scan the eye E with measurement light in the XY directions (transverse directions). The optical scanner 156 is, for example, two galvanometer mirrors, the reflection angles of which are arbitrarily adjusted by a driving mechanism. The light beam emitted from the light source 102 is changed in its reflection (advancement) direction and scanned in an arbitrary direction on the fundus. As the optical scanner 156, for example, an acoustooptic device (AOM) that changes the traveling (deflecting) direction of light may be used in addition to a reflecting mirror (galvanomirror, polygon mirror, resonant scanner).

In this case, scattered light (reflected light) from the eye E due to 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 . Coupler 130 couples light from optical fiber 152 along an optical path toward first detector 120a (eg, optical fiber 115-coupler 350a) and an optical path toward second detector 120b (eg, optical fiber 105-coupler 104-optical fiber). 117 to coupler 350b).

Of the measurement light split by the coupler 130, the measurement light passing through the optical path toward the first detector 120a is combined with the reference light from the first reference optical path 110a at the coupler 350a and interferes. Also, the measurement light passing through the optical path toward the second detector 120b is combined with the reference light from the second reference optical path 110b at the coupler 350b and interferes.

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

Reference optics 110 may be formed, for example, by reflective optics to direct light from coupler 104 to detector 120 by reflecting it through the reflective optics. Reference optics 110 may be formed by transmissive optics. In this case, the reference optics 110 direct the light from the coupler 104 to the detector 120 by transmitting it rather than returning it.

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

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

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

For example, the reference beam from coupler 104 is split by coupler 111 into first reference beam path 110a and second reference beam 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 at the coupler 350a and interferes. The reference light passing through the second reference light path 110b is combined with the measurement light from the optical fiber 117 at the coupler 350b and interferes.

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

For example, a first reference optical path 110a is provided to obtain an interference signal corresponding to a first depth region (e.g., lens, fundus) in the eye to be examined, and a second reference optical path 110b is provided to obtain a first depth region in the eye to be examined. It may be provided to obtain interference signals corresponding to two depth regions (eg, the cornea). In this case, the second depth area is set to a different area with respect to the first depth area. In this case, the first depth region and the second depth region may be regions separated from each other, regions adjacent to each other, or regions partially overlapping each other. good.

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

<Photodetector>
A detector 120 is provided to detect interference between light from the measurement path and light from the reference path. The detector 120 may be a light-receiving element, for example, a point sensor having only one light-receiving part, such as an avalanche photodiode.

In this embodiment, as the detector 120, a first detector 120a and a second detector 120b different from the first detector 120a may be provided. A first detector 120 a may be provided as a detector for detecting a first interference signal between the reference light from the first reference optical path 110 a and the measurement light from the optical fiber 115 . A second detector 120 b may be provided as a detector for detecting a second interference signal between the reference light from the second reference optical path 110 b and the measurement light from the optical fiber 117 . In this case, by detecting the first interference signal with the first detector 120a and detecting the second interference signal with the second detector 120b at the same time, the first interference signal and the second interference signal are detected. Signals can be detected simultaneously.

Note that the first detector 120a and the second detector 120b may each be a balanced detector. In this case, the first detector 120a and the second detector 120b each have a plurality of light receiving elements, obtain the 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>
FPN generation optics 200 may be provided to generate an FPN signal. The FPN generation optical system 200 may include at least one optical member (eg, first optical member 204 or 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 subject's eye.

The FPN generating optical system 200 may be, for example, a reflecting optical system, and the FPN generating optical member may be, for example, a light reflecting member (for example, a mirror). In this embodiment, a plurality of optical members for generating FPN are provided, but the present invention is not limited to this, and the FPN generation optical system 200 may be configured to include one optical member for generating 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. The FPN signal is, for example, 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, FPN generation optics 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 such that light traveling through the second optical member has a different optical path length than light traveling through the first optical member 204 . This causes the second FPN to be generated at a different location with respect to the first FPN. A zero-delay position, which will 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 match on the OCT data.

The simultaneous use of the first optical member 204 and the second optical member 206 makes it possible to generate two FPN signals simultaneously, thereby providing a temporal advantage in processing the two FPN signals. It is possible to reduce the influence of slippage. Note that the FPN optical system 200 may include three or more FPN generating optical members, and by using these at the same time, it is possible to generate three or more FPN signals at the same time.

The FPN generating optical system 200 may be, for example, a reflecting optical system, and the FPN generating optical member may be, for example, a light reflecting member (for example, a mirror). Although mirrors are used as the first FPN-generating optical member 204 and the second FPN-generating optical member 206 in this embodiment, 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, is returned to the coupler 130, passes through the same path as the light from the light guiding optical system 150, and passes through the coupler 130. 350a, reaching coupler 350b. The light from the FPN generation optical system 200 is combined with the reference light at couplers 350a and 350b and interferes. The optical path length from the light source 102 to the FPN generating 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, interference signal light corresponding to the first FPN is generated by the light passing through the first optical member 204 interfering with the reference light, the detector 120 generates the first FPN signal, and the first FPN signal is generated. Interference signal light corresponding to a second FPN is generated by the light passing through the two optical members 206 interfering with the reference light, and a second FPN signal is generated at the detector 120 . As a result, for example, detector 120 will detect both the first FPN signal and the second FPN signal at the same time.

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 detectors 120a and 120b, or one FPN signal may be detected in the detector 120a. A signal may be detected and the other FPN signal detected at detector 120b. Further, one of the detectors 120a and 120b simultaneously detects both the first FPN signal and the second FPN signal, and the other of the detectors 120a and 120b detects the first FPN signal and the second FPN signal. One of the FPN signals may be detected. At least one FPN signal may be detected by one of the detectors 120a and 120b, and no FPN signal may be detected by the other of the detectors 120a and 120b.

A light amount monitor 210 may be arranged in the FPN generation optical system 200 , and the 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 the amount of light emitted from the light source 102 is appropriate.

<Light amount branching ratio>
Here, the coupler 130 splits the light from the coupler 104 into the optical path of the light guiding optical system 150 and the optical path of the FPN generating optical system 200, and splits the light from the light guiding optical system 150 and the FPN generating optical system 200 into It is divided into an optical path toward the first detector 350a (eg, optical fiber 115-coupler 350a) and an optical path toward coupler 104 (eg, optical fiber 105-coupler 104-optical fiber 117-coupler 350b).

The light amount division ratio S1 of the coupler 130 when splitting 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 ratio of the amount of light in which the light from the fiber 105 is split by the coupler 130− is light guiding optical system 150<FPN generating optical system 200.

The light quantity splitting ratio S2 of the coupler 130 when splitting the light from the light guiding optical system 150 depends on the light quantity splitting ratio S1. As a result, more light from the light guiding optical system 150 is guided to the optical path toward the second detector 120a than toward the first detector 120a. In this case, the light amount ratio of the light from the light guiding optical system 150 divided by the coupler 130 is optical path toward the first detector 120a<optical path toward the coupler 104. FIG.

After the measurement light passing through the optical path toward the first detector 120a interferes with the light from the first reference optical path 110a, it is detected by the first detector 120a as a first interference signal. On the other hand, the measurement light directed to coupler 104 is split by coupler 104 into an optical path directed to light source 102 and an optical path directed to second detector 120b (eg, optical fiber 117 to coupler 350b). The light intensity split ratio S4 when splitting the light from the coupler 130 depends on the light intensity split ratio S3 when splitting the light from the light source 102 into the measurement light path and the reference light path. If the light splitting ratio S3 is set such that more light is guided to the reference light path than to the measurement light path, the light split ratio at which the light from the coupler 130 is split by the coupler 104 is such that the light path toward the light source 102<second becomes an optical path toward the detector 120b. As a result, more light from the coupler 130 is directed toward the second detector 120 b than toward the light source 102 . After the measurement light passing through the optical path toward the second detector 120b interferes with the light from the second reference optical path 110b, it is detected by the second detector 120b as a second interference signal.

To summarize the above configuration, with respect to the light amount division ratio S2 of the coupler 130, the optical path toward the first detector 120a<optical path toward the coupler 104, and with respect to the light amount division ratio S4 of the coupler 104, the optical path toward the light source 102<second 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 the optical path toward the second detector 120b via the coupler 104, the light from the light guide optical system 150 passes through a plurality of light splitters (for example, the coupler 130 and the coupler 104). Although the number of times of attenuation 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, so the amount of light is attenuated. Relatively few times.

Therefore, with respect to the light amount division ratio S2 of the coupler 130, the optical path toward the first detector 120a<optical path toward the coupler 104, and with respect to the light amount division ratio S4 of the coupler 104, the optical path toward the light source 102<second detector 120b. , the light intensity attenuation can be reduced even if the light intensity attenuation is performed multiple times. As a result, the difference in signal intensity between the first detector 120a and the second detector 120b is can be 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 obtained.

The light amount division ratio S2 of the coupler 130 and the light amount division ratio S4 of the coupler 104 are set so that the light amount 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 regarding the light amount division ratio S4 of the coupler 102, the optical path toward the light source 102: The optical paths to the two detectors 120b may be set to be 1:2.

Not limited to the above, regarding the light amount division ratio S2 of the coupler 130 and the light amount division ratio S4 of the coupler 104, the amount of reflected light at the imaging site of the OCT data detected by the first detector 120a and the second detector 120b Considering the difference, the light amount division ratio may be set. In other words, the amount of reflected light from the cornea of the subject's eye is large, but the amount of reflected light from the lens and the fundus is relatively small. Therefore, considering the reflected light amount ratio depending on the imaging site, the light amount of the coupler 130 is adjusted so that the signal intensity of the OCT data is the same between the first detector 120a and the second detector 120b. 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 directed to the first detector 120a via one light splitter (for example, the coupler 130) and the light directed to the first detector 120a , splitting the light toward the second detector 120b through a plurality of couplers (e.g., coupler 130, coupler 104) to more efficiently guide the light from the light guide optics 150 to each detector. It is because they will be taken away. 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 subject's eye is weak.

FIG. 2 is a diagram showing an example of the FPN generating optical system according to this embodiment. The FPN generation optics 200 may comprise at least a first optical path 203 comprising a first optical member 204 and a second optical path 205 comprising 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 location different from FPN. For example, since the optical path length of the second optical path 205 is longer than the optical path length of the first optical path 203, it is generated at a position farther from zero delay than the first FPN.

The FPN generation optical system 200 may include an optical path dividing member 202 (eg, a beam splitter), which divides the optical path on the light source side into a first optical path 203 and a second optical path 205. may be provided for 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 is different from the optical path length from the branch position of the optical path dividing member 202 to the second optical member 206 . 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 .

Also, 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 wavenumber component calculated using the first FPN (hereinafter referred to as first wavenumber mapping information) and mapping information of each wavenumber component calculated using the second FPN (hereinafter referred to as , and the second wavenumber mapping information), the dispersion component included in each mapping information can be properly canceled when calculating the correction information for correcting the mapping state of each wavenumber component. , the correction information can be obtained with high accuracy (details will be described later). In this case, the mutually equal variance amounts do not necessarily have to be exactly the same, as long as a certain degree of accuracy is ensured and the variance components can be properly canceled.

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

The first polarization adjustment section 300 may be arranged in the optical path of the first reference optical path 110a and provided to adjust the polarization state of the reference light passing through the first reference optical path 110a. The second polarization adjuster 302 may be arranged in the optical path of the second reference optical path 110b and provided to adjust the polarization state of the reference light passing through the second reference optical path 110b. The third polarization adjuster 304 may be arranged in the optical path of the FPN generation optical system 200 and 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 emitted wavelength is changed by the light source 102, the corresponding interference signal light is received by the detector 120 and is consequently detected by the detector 120 as a spectral signal. The control unit 70 processes (Fourier analysis) the spectral signal detected by the detector 120 to obtain OCT data of the eye to be examined.

The spectral signal (spectral data) may be rewritten as a function of wavelength λ and transformed into a function I(k) equally spaced with respect to wavenumber k (=2π/λ). Alternatively, it may be acquired as a function I(k) equally spaced with respect to wavenumber k from the beginning (K-CLOCK technique). The arithmetic controller may obtain OCT data in the depth (Z) domain by Fourier transforming the spectral signal in wavenumber k-space.

Furthermore, information after Fourier transformation may be represented as a signal containing real and imaginary components in Z space. The control unit 70 may obtain OCT data by obtaining the absolute values of the real and imaginary components of the signal in Z space.

In this embodiment, the control unit 70 processes the first interference signal detected by the first detector 120a to obtain first OCT data and the second interfering signal detected by the second detector 120b. may be processed to obtain second OCT data. Here, when the first reference optical path 110a and the second reference optical path 120b are set to have different optical path lengths, the first OCT data and the second OCT data are at least partially different regions in the depth direction. are obtained, and the first and second reference optical paths 110a and 120b are set to have the same optical path length, the first and second OCT data are obtained in the same region in the depth direction. of OCT data are acquired.

<Control system>
The control unit 70 may include a CPU (processor), RAM, ROM, etc. (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, initial values, and the like for controlling the operation of the OCT apparatus may be stored in the ROM of the control unit 70 .

The control unit 70 may be electrically connected to a nonvolatile memory (hereinafter abbreviated to memory) 72 as a storage unit, a display unit 75, and the like. The memory 72 may be a non-transitory storage medium that can retain stored content even when the power supply is interrupted. For example, a hard disk drive, a flash ROM, a USB memory that is detachably attached to the OCT apparatus, or the like 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 wavenumber component. An arithmetic processing program or the like for obtaining correction information for correcting may be stored. In addition, the memory 72 may store OCT images generated from OCT data as well as various information related to imaging. The display unit 75 may display an OCT image generated from OCT data.

<Image synthesis using FPN>
The control unit 70 combines the first OCT data based on the first interference signal and the second OCT data based on the second interference signal with the FPN signal detected by the first detector 120a and the second OCT data. Synthetic OCT data may be obtained by synthesizing based on the FPN signal detected by detector 120b (see FIGS. 3-5). That is, the FPN signal may be used as a reference signal for synthesizing a plurality of OCT data. Here, the second OCT data may differ from the first OCT data in at least part of the depth region on the subject's eye.

As an example, since the arrangement positions of the optical members for FPN generation (for example, the optical members 204 and 206) in the FPN generation optical system 200 are known, the positional relationship between the first OCT data and the second OCT data is It may be set using an FPN signal.

This makes it possible to properly set the positional relationship between the first OCT data and the second OCT data. In this 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. It is also possible to reduce the positional deviation due to such as.

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

The control unit 70 obtains first OCT data based on the first interference signal and second OCT data based on the second interference signal by the first optical member detected by the first detector 120a. Composite OCT data may be obtained by combining based on the FPN and the FPN by the second optical member detected by the second detector 120b.

3 and 4 are diagrams showing an example of data when a plurality of OCT data are synthesized using FPN signals, FIG. 3 is an image diagram before synthesis, and FIG. 4 is an image diagram after synthesis. FPN1 is the FPN signal generated by the first optical member 204 and FPN2 is the 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. First OCT data is acquired using a first reference optical path 110a and a first detector 110a, and second OCT data is acquired using a second reference optical path 110b and a second detector 110b. may be

When setting the positional relationship between OCT data using the FPN signal, the control unit 70 uses, for example, FPN1 included in the first OCT data and FPN2 included in the second OCT data to set the position between the OCT data. Relationships may be established. 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 controller 70 uses the first OCT data and the second OCT When combining the data, the positions of FPN1 and FPN2 may be detected and combined so that the detected position of FPN1 and the detected position of FPN2 are separated by an optical path length ΔD. Note that for the synthesis of overlapping portions between a plurality of OCT data, either one of the OCT data may be used, or the average of both OCT data may be obtained.

The control unit 70 may measure the dimensions of the subject's eye (e.g., anterior chamber depth, eye axial length, etc.) based on the synthesized OCT data synthesized as described above, and further uses the obtained measurement results as It may be displayed on the display unit 75 .

FIG. 5 is a diagram showing an example of transformation of data when combining a plurality of OCT data using an 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 by adjusting the optical path length of the first reference optical path 110a, the third of OCT data may be obtained.

Here, the control unit 70 may use the third OCT data to set the positional relationship between the first OCT data and the second OCT data. In this case, the control unit 70 controls the positional relationship such that, for example, the detection position of FPN1 on the first OCT data and the detection position of FPN1 on the third OCT data are the same positions in the depth direction. Further, the control unit 70, for example, the detection position of FPN2 on the second OCT data and the detection position of FPN2 on the third OCT data are the same positions in the depth direction You may set a positional relationship so that it may become. According to this, even if the position of the optical member for FPN generation fluctuates due to secular change, the actual positional relationship can be used, so the positional relationship between the first OCT data and the second OCT data can be more easily understood. It can be set stably.

When detecting the position of FPN in the depth direction, for example, the control unit 70 processes OCT data acquired by the detectors 120a and 120b, and uses an optical member for FPN generation (for example, the first optical The FPN signal by 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, for example, whether each luminance signal of the OCT data exceeds a threshold set for obtaining the FPN signal. An FPN signal (reference signal) corresponding to the optical member can be extracted. It should be noted that FPN1 and FPN2 can be distinguished using a known arrangement.

The method is not limited to the above method, and the third OCT data in FIG. 5 may be used as the first OCT data and the second OCT data in FIG. 5 may be synthesized (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. First OCT data is acquired using a first reference optical path 110a and a first detector 110a, and second OCT data is acquired using a second reference optical path 110b and a second detector 110b. may be

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

In this embodiment, in the FPN generation optical system 200, the first optical path 203 on which the first optical member 204 is arranged and the second optical path 205 on which the second optical member 206 is arranged are equal to each other. It is set (constructed) to the amount of optical dispersion. As a result, the PSF signal by FPN has a similar shape, so even if 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 of image synthesis using one FPN. Generation of FPN1 is not necessarily essential. In other words, even if the FPN optical system 200 of this embodiment includes one optical member for FPN generation, image synthesis is possible and the configuration of the apparatus can be simplified. The imaging range in the depth direction becomes narrower and the overlapped area between different OCT data increases as compared with the case of using it. On the other hand, when a common area is provided, the imaging range in the depth direction can be widened by using a plurality of FPN signals, and overlapping areas between different OCT data can be reduced. In addition, discontinuous regions may be included in between. In this case as well, the distance between the two can be accurately determined, which is useful when examining the accommodation function of the eye, for example.

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

As for the timing of obtaining the FPN signal, for example, it may be performed when the power is turned on, or may be performed each time the subject is changed. Also, it may be performed during optimization control for optimizing the imaging conditions in the OCT optical system. Of course, it is not limited to this, and may be performed all the time. For example, the control unit acquires OCT data including an FPN signal in advance, and uses the FPN signal acquired in advance to perform synthesis of OCT data acquired later, correction of the mapping state, polarization adjustment, and the like. may

<Light shielding member>
A light shielding member or a light reducing member may be placed in the optical path of the FPN generating optical system 200 to reduce the FPN signal of the OCT data used for observing or photographing the subject's eye. In this case, at least one of the first optical path and the second optical path may be blocked or dimmed to reduce the FPN signal on the OCT data. These are effective in obtaining OCT data used for diagnosis, observation, and the like. Also, without being limited to this, the FPN signal included in the OCT data may be removed by signal processing.

For example, in the optical path of the FPN generation optical system 200, 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 are provided in each optical path. You may arrange|position so that insertion/removal is possible with respect to.

<Correction of wavenumber mapping>
FIG. 7 is a diagram showing an example of OCT data according to the present embodiment, in which a first FPN signal and a second FPN signal are simultaneously formed on the OCT data. Note that the OCT data may include an OCT image of the subject's eye.

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

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

The control unit 70 may determine φ(k) in the spectral signal at the position corresponding to the FPN, for example, by analyzing the intensity level of the FPN. φ(k) indicates the change in the phase φ of the spectral signal according to the sweep wavelength (wavenumber). φ(k) may be represented by a function in which the horizontal axis is wavenumber k and the vertical axis is phase φ. Polynomial fitting may be performed on φ(k) in the wavenumber k region where the signal intensity (amplitude) is large, and φ(k) in the wavenumber k region where the signal intensity is small may be obtained by extrapolation or interpolation. For example, φ(k) may be obtained from the arc tangent of the ratio between the real part RealF and the imaginary part ImagF of the Fourier transform value (intensity value) F at the depth position corresponding to FPN. Here, the arc tangent of the ratio between 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 simultaneously, the control unit 70 processes the first FPN to obtain the first wavenumber mapping information φ1(k) and processes the second FPN to obtain the second wavenumber mapping information φ1(k). Mapping information φ2(k) may be obtained (see FIG. 8). In this case, each wavenumber mapping information may be obtained as phase information of each wavenumber component.

Furthermore, the control unit 70 may obtain difference information Δφ(k) between the first wavenumber mapping information φ1(k) and the second wavenumber mapping information φ2(k) (see FIG. 5). Note that the difference information may be obtained as phase difference information of each wavenumber component. When obtaining the difference information Δφ(k), the second FPN advances the phase faster, so the difference information may be obtained by Δφ(k)=φ2(k)−φ1(k). By obtaining the difference information, the dispersion component included in each wave number mapping information can be canceled. In this case, as described above, it is preferable to equalize the amount of dispersion between the first optical path 203 and the second optical path 205 .

Here, if the optical distance (optical path length difference) between the first FPN and the second FPN is ΔZ, and if 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。

should be a straight line as shown in

Here, ΔZ is obtained as follows. The interference component can be generalized as exp(ikz), where k and z are related by kz=2π. From this, z is the following equation (2) where N is the number of sampling points, kmax and kmin are the maximum and minimum values of k values 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 Note that i=0, 1, 2, . . . , N/2
Here, if an interference signal corresponding to ΔZ is detected at a sampling point corresponding to i(ΔZ), ΔZ is given by the following equation (3)

と表すことができる。

It can be expressed as.

Δφ(k) should ideally be a straight line with a slope of ΔZ and an intercept of 0;

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）

and corrected. From this, the corrected wavelength λ' is determined as λ'=2π/k'. where σ is the following formula (5)

と展開したときの非線形項σ＝ｂ_２ｋ^２+ｂ_３ｋ^３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。

The nonlinear term σ=b ₂ k ² +b ₃ k ³ when expanded as follows. In the above example, the nonlinear term is of the third order, but the number of nonlinear terms is not limited to this, and may be greater. For example, it may be about the 9th order. Alternatively, other fitting methods (fitting with a chirped sine wave) may be used.

Note that FIG. 9 is a diagram schematically showing the mapping of spectral signals corrected by performing the correction calculation. In addition, the corrected Δφ (kmin) and Δφ (kmax) values are within a predetermined allowable range (for example, about 1E ^-5 ) from the ideal values of z (peak) · kmin and z (peak) · kmax If so, it is determined that convergence has occurred, and if this condition is not met, the above-described corrected λ' is used to repeat the same calculation again.

As described above, the control unit 70 may calculate correction information from at least two FPN signals generated using the FPN generation optical system 200 and store the obtained correction information in the memory 72 . Thereby, the correspondence relationship between each wavelength component detected by the detector 120 and each sampling point can be 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, please refer to Japanese Patent Application Laid-Open Nos. 2013-156229 and 2015-68775.

In the above description, the case of correcting the wavenumber mapping information in SS-OCT is shown, but it is not limited to this, and the present embodiment can be applied even when correcting the wavenumber mapping information in SD-OCT. 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, Japanese Unexamined Patent Application Publication No. 2010-220774 may be referred to.

For the wavenumber mapping correction according to this embodiment, see Japanese Patent Application No. 2017-017156.

The timing of acquiring the correction information for correcting the mapping state of each wavenumber component may be, for example, when the power is turned on, or may be performed each time the subject is changed. Also, it may be performed during optimization control for optimizing the imaging conditions in the OCT optical system. Of course, it is not limited to this, and may be performed all the time. After the mapping state is corrected, the FPN on the OCT image may be removed by noise removal processing.

Also, in the above description, the FPN generation optical system is provided at a position branched from the measurement optical path, but the present invention is not limited to this, and is not limited to this as long as it is in the optical path of the OCT optical system. 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 may be obtained by interference between the light from the FPN generation optical system and the reference light (or measurement light). 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 join. In this case, for example, an FPN signal is obtained by interference between interference light directly directed to the optical path of the interference light and interference light from the FPN generation optical system provided at a position branched from the optical path of the interference light. may be detected by In addition, when the detector 120 includes a first detector 120a and a second detector 120b, the FPN generation optical system is arranged before the optical path of each detector is divided. A similar FPN signal may be detected.

<Example of application to eye to be examined>
The apparatus may be an ophthalmic OCT apparatus for acquiring OCT data of an eye to be examined. For example, the ophthalmologic OCT apparatus may be configured to acquire OCT data of the fundus and OCT data of the anterior segment including the cornea and lens. The configuration may be such that the axial length can be measured.

For example, the ophthalmic OCT apparatus may be configured to switch the optical arrangement of the OCT optical system 100 according to an automatic or manual mode switching signal. An example of mode switching among the fundus imaging mode, the anterior segment imaging mode, and the axial length measurement mode will be described below.

<Fundus photography mode>
When the fundus imaging mode is set, the controller 70 may control the light guide optical system 150 to switch to an optical arrangement for obtaining OCT data of the fundus. In this case, for example, the controller 70 controls the optical arrangement of the light guiding optical system 150 so that the turning point of the measurement light is formed on the pupil of the subject's eye and the condensing position of the measurement light is formed on the fundus. can be switched. For the configuration related to the switching of the optical arrangement of the light guide optical system 150, see Japanese Patent Application Laid-Open No. 2016-209577, for example.

When the fundus imaging mode is set, the controller 70 may adjust the optical path length of at least one of the measurement light and the reference light to set the OCT data acquisition region to the fundus. In this case, for example, the controller 70 controls the distance between the measurement light and the reference light so that the optical path length of the reference light that has passed through at least one of the plurality of reference light paths matches the optical path length of the measurement light that has passed through the fundus. You may adjust the optical path length difference between. When the optical path length difference is adjusted, it may be adjusted so that the OCT data is acquired with the retina formed on the back side of the zero delay position, or the choroid may be adjusted on the front side of the zero delay position. Arrangements may be made to acquire OCT data as formed.

In the present embodiment, for example, the optical member arranged in the measurement light path is moved so that the optical path length of the measurement light from the fundus and the reference light from the first reference light path 110a match, whereby the measurement is performed. 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 fundus.

FIG. 10 is a diagram showing an example of OCT data acquired in the fundus imaging mode. The controller 70 may move the optical member 112 to adjust the optical path length of the second reference optical path 110b so that it has the same optical path length as 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 are the same region of the fundus. In this case, the control unit 70 may obtain synthetic OCT data (eg, arithmetic mean image, super-resolution image, etc.) based on the first OCT data and the second OCT data. As a result, good OCT data of the fundus of the predetermined imaging region can be obtained in a short period of time.

<Axial length measurement mode>
When the axial length measurement mode is set, the controller 70 may control the light guide optical system 150 to switch to the same optical arrangement as in the fundus imaging mode described above. In this case, for example, the control unit 70 switches the optical arrangement of the light guiding 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 As a result, detailed morphological information of the fundus (for example, information near the macula) can be obtained from the OCT data obtained when measuring the axial length of the eye, and as a result, the axial length of the subject's eye can be measured with high accuracy. .

When the eye axial length measurement mode is set, the controller 70 adjusts the optical path length of at least one of the measurement light and the reference light, and the OCT data obtained by one of the first detector 120a and the second detector 120b. may be set to the fundus, and the other of the first detector 120a and the second detector 120b may be set to the cornea.

FIG. 11 is a diagram showing an example of OCT data acquired in the axial length imaging mode. In the present embodiment, for example, the optical member arranged in the measurement light path is moved so that the optical path length of the measurement light from the fundus and the reference light from the first reference light path 110a match, whereby the measurement is performed. 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 fundus.

In a state where the positions of the optical members arranged in the measurement optical path are adjusted so that the OCT data of the fundus are included in the first OCT data, for example, the control unit 70 controls the optical path length of the measurement light from the cornea, By moving the optical member 112 arranged 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 to may be adjusted. Thereby, the second OCT data obtained based on the output signal from the second detector 110b includes OCT data of the cornea.

When the OCT data of the fundus and the OCT data of the cornea are acquired, the control unit 70 may detect the position of the retina based on the OCT data of the fundus and the position of the cornea based on the OCT data of the cornea. The control unit 70 may measure the axial length using the detection result of the retina position, the detection result of the cornea 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 from the driving position of the driving section for moving the optical member 112, or It may be detected based on location. Note that 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 generating optical system 200 may be configured to include an FPN generating optical member for generating an FPN signal corresponding to the cornea and an FPN generating optical member for generating an FPN signal corresponding to the fundus. , the known optical member positions may be used to obtain the optical path length difference. In this case, three or more FPN-generating optical members may be used to accommodate the optical path length difference.

<Anterior segment imaging mode>
When the anterior segment imaging mode is set, the controller 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 lens. In this case, the optical arrangement of the light guiding optical system 150 is switched so that the turning point of the measurement light is formed on the apparatus side of the pupil of the subject's eye and the condensing position of the measurement light is formed on the anterior segment of the eye. may For the configuration related to the switching of the optical arrangement of the light guide optical system 150, see Japanese Patent Application Laid-Open No. 2016-209577, for example.

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 controls the first detector 120a and the second detector 120b. One of the OCT data acquisition regions may be set to the lens, and the OCT data acquisition regions of the other of the first detector 120a and the second detector 120b may be set to the cornea. Here, the OCT data acquired by the first detector 120a and the OCT data acquired by the second detector 120b are different in at least part of the acquired region on the subject's eye in the depth direction. Thereby, OCT data including the corneal area and OCT data including the lens area may be obtained. In this case, the OCT data including the corneal area may include at least the cornea and the anterior surface of the lens, and the OCT data including the lens area may include at least the posterior surface of the lens. That is, the OCT data of the anterior segment of the anterior segment and the OCT data of the posterior segment of the anterior segment may be acquired separately.

Note that the control unit 70 may synthesize, for example, OCT data including the lens region and OCT data including the cornea region. In this case, the synthesis process using the FPN signal described above may be used so that the optical path length of the measurement light from the cornea and lens matches the optical path length of 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. In other words, in a state in which the optical path length difference between the measurement light and the reference light of the light guide optical system 150 is set so as to acquire OCT data including the corneal area and OCT data including the lens area, FPN is added to each OCT data. FPN generation optics 200 may be set to include the signal.

When the optical path difference is adjusted, it is adjusted so that the OCT data including the corneal region is acquired in a state where the anterior corneal surface is formed deeper than the zero-delay position, and the posterior surface of the lens is adjusted more than the zero-delay position. Arrangements may be made to acquire OCT data that includes the lens region in the anteriorly formed state. As a result, it is possible to avoid the influence of the mirror image when synthesizing the images. In addition, between the first OCT data and the second OCT data, the first reference optical path 110a and the second reference optical path 110b are arranged so that part of the acquired region on the subject's eye overlaps in the depth direction. may be set. As a result, the connection in image synthesis can be performed smoothly.

FIG. 12 is a diagram showing an example of OCT data acquired in the anterior segment imaging mode. In the present embodiment, for example, the optical member arranged in the measurement light path is moved so that the optical path length of the measurement light from the crystalline lens and the reference light from the first reference light path 110a match, thereby enabling the measurement. 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 lens region.

In a state where the positions of the optical members arranged in the measurement optical path are adjusted so that the first OCT data includes the OCT data of the lens, for example, the control unit 70 controls the optical path length of the measurement light from the cornea, By moving the optical member 112 arranged 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 to may be adjusted. Thereby, the second OCT data obtained based on the output signal from the second detector 110b includes OCT data of the cornea.

When the OCT data of the lens and the OCT data of the cornea are acquired, for example, the control unit 70 may combine the OCT data of the lens and the OCT data of the cornea to acquire combined OCT data. Furthermore, the control unit 70 may detect the corneal position, the lens position, etc. based on the synthesized OCT data, and measure the anterior chamber depth, the lens thickness, etc. of the subject's eye.

<Correction of OCT data using FPN signal included in other OCT data>
The control unit 70 acquires OCT data containing an FPN signal from one of the first OCT data and the second OCT data, and obtains OCT data containing no FPN signal from the other of the first OCT data and the second OCT data. data may be obtained. Further, the control unit 70 may obtain wavenumber 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 using a plurality of detectors, it is not always necessary to provide an FPN generation optical system for each detector. In this case, the control unit 70 may correct the OCT data that does not include the FPN signal in real time, whereby 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 to set the OCT data acquisition region by one of the first detector 120a and the second detector 120b to a predetermined value. It may be set to an imaging site (for example, fundus, cornea, lens). In addition, the control unit 70 sets the acquisition area of the OCT data by the other of the first detector 120a and the second detector 120b to the optical member (for example, the optical member 204 and the optical member 206) of the FPN generation optical system 200. do.

FIG. 13 is a diagram showing an example of applying real-time correction in the fundus imaging 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 the acquisition area of the OCT data by one of the first detector 120a and the second detector 120b to the fundus ( See fundus photography mode above).

In addition, the control unit 70 sets the acquisition area of the OCT data by the other of the first detector 120a and the second detector 120b to the optical member (for example, the optical member 204 and the optical member 206) of the FPN generation optical system 200. 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 controls the measurement light and the reference light such that the optical path length of the reference light that has passed through at least one of the plurality of reference light paths matches the optical path length of the measurement light that has passed through the FPN generation optical system 200. You may adjust the optical path length difference between.

In the present embodiment, for example, the optical member arranged in the measurement light path is moved so that the optical path length of the measurement light from the fundus and the reference light from the first reference light path 110a match, whereby the measurement is performed. 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 fundus.

Further, in a state in which the positions of the optical members arranged in the measurement optical path are adjusted so that the OCT data of the fundus oculi is included in the first OCT data, the control unit 70, for example, controls the FPN generating optical 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 and the reference light from the second reference optical path 110b match , the optical path length of the reference light in the second reference optical path 110b may be adjusted. Thereby, 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 of the cornea, lens, etc. may be included in addition to the FPN signal.

In the above description, an example of application in the fundus photographing mode is shown, but the present invention is not limited to this, and the above configuration may be applied to other photographing modes.

In the above description, OCT data containing an FPN signal (for example, only the FPN signal) is obtained from one of the first OCT data and the second OCT data, and the first OCT data and the second OCT data are obtained. On the other hand, when acquiring OCT data of an eye to be examined that does not include an FPN signal, the optical path length adjustment is not limited to that described 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 placing the light blocking member 210 in the first optical path. In this case, since the light blocking member 212 is removed from the second optical path, second OCT data including FPN (for example, FPN2) is obtained. Note that 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 units (eg, the first polarization adjustment unit 300, the second polarization adjustment unit 302, and the third polarization adjustment unit 304) to adjust the polarization state when obtaining OCT data. You may do so. Note that the timing of adjusting the polarization state may be, for example, when the power is turned on, or may be performed each time the subject is changed. Also, it may be performed during optimization control for optimizing the 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 showing 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 corneal image in the second OCT data is acquired with good signal intensity.

FIG. 15 is a diagram showing an example of FPN signal strength. Next, the controller 70 controls the third polarization adjuster 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 obtained with good signal strength. As a result, the corneal image and the FPN signal in the second OCT data are acquired with good signal intensity.

Next, the control unit 70 controls the first polarization adjustment 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. The polarization state is adjusted so that the signal intensity ratio is equal to each other, for example. As a result, the FPN signal in the first OCT data is obtained with good signal strength, and the lens image in the first OCT data is obtained with good signal strength.

According to the control as described above, it is possible to adjust the signal strength balance between the first OCT data and the second OCT data. Furthermore, in adjusting the polarization state for OCT data including the lens, the signal intensity ratio between the FPN signal in the second OCT data and the FPN signal in the first OCT data is used to obtain the polarization state using the lens image. The polarization state is adjusted more accurately than adjusting . In other words, the crystalline lens image in this case may be limited to information on the posterior surface of the crystalline lens, and the amount of information as an image is relatively small, so 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, by using the FPN signal, stable signal strength can be ensured, so accuracy as a signal evaluation value can be ensured, and the polarization state can be adjusted satisfactorily.

In addition, if the polarization state is optimized only for information on the posterior surface of the lens, there will be a polarization mismatch detected between the first OCT data and the second OCT data, resulting in a connecting region between the two. A gap occurs in the intensity signal. This is noticeable, for example, when the lens is at the gap position. In other words, the (generally weak) intensity signal of the lens becomes discontinuous, which can be fatal when trying to quantitatively evaluate the degree of opacity. On the other hand, if the polarization mismatch detected between the first OCT data and the second OCT data is eliminated by this embodiment, such a gap will not occur.

Further, in the above description, by adjusting the polarization state of the FPN generation optical system, the FPN signal can be detected with high accuracy, so various processes using the FPN signal can be properly performed.

In the above description, the FPN signal is used to adjust the polarization state of the OCT data including the lens, but the present invention is not limited to this, and the polarization state may be adjusted using the signal intensity of the entire 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 are By adjusting the polarization state for each, each OCT data can be acquired with good signal intensity. Of course, it is not limited to this, and the polarization state may be adjusted for only one of the OCT data.

Also, when using either the first detector 120a or the second detector 120b, for example, the polarization state may be adjusted with respect to the OCT data obtained by the detector used.

<Alignment detection using OCT signal>
For example, the control unit 70 adjusts the optical path length of at least one of the measurement light and the reference light, and determines the acquisition area of OCT data by one of the first detector 120a and the second detector 120b to be the cornea and the pupil ( or iris), and relative position information of the device main body with respect to the subject's eye may be detected based on the position of the characteristic region on the OCT data. In this case, the optical path length difference between the measurement light and the reference light in the OCT optical system 100 can be obtained in advance (may be stored in memory in advance, or detected based on the position of the optical member, etc.). Since the zero-delay position is known, it is possible to detect relative position information of the device main body with respect to the subject's eye by detecting the position of the characteristic region with respect to the zero-delay position.

As the relative position information, for example, the working distance of the apparatus main body with respect to the eye to be examined may be detected, the distance of the apparatus main body with respect to the eye to be examined in the vertical and horizontal directions may be detected, and the position of the apparatus main body with respect to the eye may be detected. may be detected three-dimensionally. In this case, for example, the amount of deviation from the proper alignment position may be detected.

For example, the control unit 70 analyzes the OCT data of the anterior segment to detect the position of the characteristic part of the subject's eye (for example, the corneal vertex, the center of the pupil), and automatically adjusts the device main body to the detected characteristic part. You may make it carry out automatic alignment which moves to. In this case, the control unit 70 may three-dimensionally detect the position of the characteristic site and perform three-dimensional automatic alignment with respect to the detected characteristic site. According to this, since the three-dimensional position can be accurately detected from the OCT data, it is possible to accurately align the subject's eye.

When detecting a characteristic part, for example, after performing image processing such as edge detection, an image area corresponding to the characteristic part is searched, and the position where the image area corresponding to the characteristic part is detected is called the position of the characteristic part. may be detected as In addition, in the automatic alignment control, a drive mechanism for three-dimensionally moving the apparatus body may be provided.

An example of alignment detection using anterior segment data will be described below. For example, the control unit 70 controls the optical scanner 156 to repeatedly perform cross-scanning on the anterior segment of the subject's eye. Cross scan may be a scanning pattern in which each scanning line is orthogonal to each other, for example, a scanning pattern in which line scanning in the X direction and line scanning in the Y direction are orthogonal to each other.

16 and 17 are examples of OCT data obtained by cross scanning. The left diagram in FIG. 16 is OCT data obtained by line scanning in the X direction, and the right diagram in FIG. OCT data acquired by directional line scan. FIG. 16 shows an example before completion of alignment, and FIG. 17 shows an example after completion of alignment.

In this case, the optical scanner 156 (eg, the central voltage of the galvanometer) and the OCT optical system 100 are adjusted so that the characteristic site (eg, corneal vertex) in the OCT data is formed at the predetermined position in the OCT data at the proper alignment position. Adjust (calibrate) the optical path length, etc. Coordinate data regarding the optical arrangement and the predetermined position during adjustment may be stored in advance in the memory. The appropriate alignment position may be, for example, an alignment position in which the optical axis of the OCT optical system 100 and the distance in the front-rear direction are appropriate with respect to the eye to be examined.

For example, the control unit 70 may detect the positions of the characteristic regions in the OCT data by image processing, and may perform automatic alignment based on the amount of deviation of the characteristic regions with respect to the preset predetermined positions. In this case, the amount of deviation in the X direction may be detected from the OCT data obtained by line scanning in the X direction, and the amount of deviation in the Y direction may be detected from the OCT data obtained by line scanning in the Y direction. For the amount of displacement in the Z direction, OCT data obtained by at least one of line scanning in the X direction and line scanning in the Y direction may be used.

Rough alignment until the OCT data of the anterior segment is acquired may be automatically performed based on an imaging signal from an imaging device for observing the anterior segment (not shown). In the automatic alignment using the anterior segment observation imaging device, an alignment index projected onto the anterior segment may be used.

Further, the control unit 70 may perform rough alignment and severe alignment by changing the scanning range. For example, the control unit 70 may widen the scanning angle of view of the measurement light when performing rough alignment, and narrow the scanning angle of view of the measurement light when performing severe alignment.

In the above description, the case of cross-scanning is illustrated, but alignment in one direction is also possible to some extent. For example, the control unit 70 performs automatic alignment in the X direction so that the tomographic image of the cornea is bilaterally symmetrical in OCT data obtained by line scanning in the X direction, and then in the normal direction (for example, the Y direction). The device body may be moved until the corneal curvature becomes maximum with respect to .

In addition, in the description of FIG. 16, the case where the corneal vertex is set as the characteristic part is illustrated, but the present invention is not limited to this. For example, the pupil position and the pupil diameter are detected by detecting the iris part by image processing. However, automatic alignment may be performed based on the detection result of at least one of the pupil position and the pupil diameter.

When performing alignment detection using OCT signals, for example, the fundus may be set as the OCT data acquisition region by the other of the first detector 120a and the second detector 120b. This allows accurate alignment with the fundus. In addition, the control unit 70 utilizes the relative position information of the device main body with respect to the anterior segment detected as described above and the optical path length difference between the first reference optical path 110a and the second reference optical path 110b to Relative position information of the device main body with respect to the fundus of the optometric eye may be detected. In this case, the position of the fundus on the OCT data may be detected. In addition, not limited to the fundus, an imaging region different from the fundus may be set as the OCT data acquisition region by the other of the first detector 120a and the second detector 120b. For example, the crystalline lens may be set. may

<Optical path length difference adjustment function according to the depth of the object>
In this embodiment, the optical path is arranged in at least one of the first reference optical path 110a and the second reference optical path 110b, and changes the optical path length difference between the first reference optical path 110a and the second reference optical path 110b. A length changer may be provided. The optical path length difference changing section may be configured to change the optical path length of at least one of the first reference optical path 110a and the second reference optical path 110b.

FIG. 18 is a diagram showing an example of synthesized OCT data after the optical path length difference has been adjusted according to the depth of the object. In this case, the control unit 70 synthesizes the first OCT data and the second OCT data acquired after being changed by the optical path difference changing unit, to obtain a predetermined portion of the subject eye (for example, the anterior segment of the eye). ) may acquire synthetic OCT data according to the depth. Accordingly, excellent synthetic OCT data can be obtained regardless of the depth of the predetermined region of the eye to be examined.

There is a possibility that the preset depth range (imageable range) of the synthesized OCT data is not appropriate for the depth range of the anterior segment that is desired to be acquired. For example, if the preset depth range of synthetic OCT data is set to a depth range that allows sufficient imaging from the anterior surface of the cornea to the posterior surface of the crystalline lens of a typical eye, the following situation may occur. For example, children's eyes, eyes shorter than normal eyes, pathological eyes such as IOL eyes (lens thickness, anterior chamber thickness, and corneal shape are not common), where the distance from the anterior cornea to the posterior lens is short. When photographing the subject's eye, changing the position of the fixation target, etc., for near vision (lens thickness) and distance vision (lens thinness). Due to the distance to the cornea or the posterior surface of the lens with respect to the zero delay position, there is a possibility that the anterior segment image cannot be imaged satisfactorily due to the influence of sensitivity attenuation.

Therefore, for example, based on the OCT data of the anterior segment that has been updated once or in real time, the control unit 70 determines the position of the shallowest characteristic region (for example, the corneal position) in the anterior segment included in one of the OCT data. , or the position of the deepest characteristic region (for example, the position of the posterior surface of the lens) included in the other OCT data may be detected by image processing. Next, the control unit 70 controls the optical path length difference changing unit to arrange the first reference optical path 110a and the second reference optical path 110a so that the detected feature site is arranged at a predetermined position with respect to the zero delay position. The optical path length difference with 110b may be changed. As a result, for example, the distance from the zero-delay position to the characteristic region of the anterior segment can be made close to optimum. If so, more sensitive synthetic anterior segment OCT data can be obtained.

In addition, when combining the first OCT data and the second OCT data, for example, FPN may be used. It should be noted that when the optical path length difference is adjusted, the FPN can be used for synthesis as long as the FPN is within the depth range of the first OCT data and the second OCT data.

<Function to switch between full anterior segment imaging and crystalline lens imaging>
In the anterior segment imaging modes described above, a first anterior segment imaging mode for imaging the entire anterior segment and a second anterior segment imaging mode for imaging the crystalline lens may be provided.

For example, in the first anterior segment imaging mode, the control unit 70 determines that one of the first OCT data based on the first detector 120a and the second OCT data based on the second detector 120b is the cornea and the lens. OCT data including the anterior surface is acquired, and the other of the first OCT data based on the first detector 120a and the second OCT data based on the second detector 120b is acquired as OCT data including the posterior surface of the lens. Alternatively, the optical path length difference between the first reference optical path 110a and the second reference optical path 110b may be adjusted (see FIG. 4, for example).

FIG. 19 is a diagram showing an example of OCT data obtained in the second anterior segment imaging mode for imaging the crystalline lens. For example, in the second anterior segment imaging mode, the control unit 70 controls whether one of the first OCT data based on the first detector 120a and the second OCT data based on the second detector 120b is positioned on the front surface of the lens. and the other of the first OCT data based on the first detector 120a and the second OCT data based on the second detector 120b is obtained as OCT data including the posterior surface of the lens, The optical path length difference between the first reference optical path 110a and the second reference optical path 110b may be adjusted. In this case, the optical path length difference may be set such that the zero delay position is located between the cornea and the anterior surface of the lens.

By synthesizing the first OCT data and the second OCT data acquired in the first anterior segment imaging mode, the control unit 70 performs synthetic anterior segment OCT over a wide range including the cornea and the anterior and posterior surfaces of the lens. data may be obtained. In addition, the control unit 70 synthesizes the first OCT data and the second OCT data acquired in the second anterior segment imaging mode to obtain local synthetic crystalline lens OCT data including the anterior and posterior surfaces of the crystalline lens. can be obtained.

According to this, for example, in the first anterior segment imaging mode, when the image quality of the front surface of the lens is unclear due to the influence of the depth of the anterior chamber being long, etc., in the second anterior segment imaging mode, the front surface of the lens is image quality can be ensured.

In the above description, SS-OCT is taken as an example, but the present embodiment may be applied to SD-OCT without being limited to this. In this case, multiple spectrometers may be used as multiple detectors.

In the above description, an OCT apparatus for imaging an eye to be inspected is taken as an example, but the invention is not limited to this, and the present embodiment is applied to an OCT apparatus for imaging OCT data of an object to be inspected. good too. In addition, the test object may be, for example, an eye (anterior ocular segment, ocular fundus, etc.), a living body such as 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 generation optical system which concerns on a present Example. FIG. 4 is a diagram showing an example of data when combining a plurality of OCT data using an FPN signal, and showing the data before combining; FIG. FIG. 4 is a diagram showing an example of data when a plurality of OCT data are synthesized using FPN signals, and is an image diagram after synthesis. FIG. FIG. 10 is a diagram showing an example of data transformation when combining a plurality of OCT data using an FPN signal; FIG. 10 is a diagram showing an example of data transformation when combining a plurality of OCT data using an FPN signal; It is a figure which shows an example of the OCT data used for wavenumber mapping correction|amendment. FIG. 4 is a diagram showing an example of wavenumber mapping information obtained by processing FPN; FIG. 4 is a diagram showing an example for correcting a mapping state when obtaining difference information Δφ(k) between first wavenumber mapping information φ1(k) and second wavenumber mapping information φ2(k); FIG. 4 is a diagram showing an example of OCT data acquired in fundus imaging mode; FIG. 4 is a diagram showing an example of OCT data acquired in an axial length imaging mode; FIG. 4 is a diagram showing an example of OCT data acquired in an anterior segment imaging mode; FIG. 10 is a diagram showing an example of applying real-time correction in the fundus imaging mode; FIG. 10 is a diagram showing an example of OCT data when polarization adjustment is performed in an anterior segment imaging mode; FIG. 4 is a diagram showing an example of FPN signal strength; It is an example of each OCT data acquired by cross scanning before the completion of alignment. It is an example of each OCT data acquired by cross scanning at the time of completion of alignment. FIG. 10 is a diagram showing an example of synthesized OCT data after the optical path length difference has been adjusted according to the depth of the object; FIG. 10 is a diagram showing an example of OCT data obtained in a second anterior segment imaging mode for imaging the crystalline lens;

70 arithmetic controller 100 OCT optical system 110 reference optical system 120 detector 200 FPN optical system 300, 302, 304 polarization adjustment section

Claims (3)

A spectrum of the measurement light guided to the test object via the measurement light path and the reference light from the reference light path, having a first light splitter for splitting the light from the OCT light source into the measurement light path and the reference light path An OCT apparatus comprising an OCT optical system for detecting an interference signal and capable of acquiring OCT data of a subject by processing a spectral interference signal output from the OCT optical system,
The OCT optical system is
a first reference optical path as the reference optical path and a second reference optical path different from the first reference optical path;
a first detector for detecting a first interference signal between the reference light from the first reference optical path and the measurement light;
a second detector different from the first detector for detecting a second interference signal between the reference light from the second reference optical path and the measurement light; ,
an FPN generation optical system for generating an FPN signal , comprising at least one optical member for generating an FPN signal;
The measurement optical path is divided into an optical path toward the test object and an optical path of the FPN generation optical system, and the light from the test object and the light from the FPN generation optical system are separated without passing through the first optical splitter. a second light splitter for splitting into a light path towards a first detector and a light path through said first light splitter towards said second detector;
The first detector and the second detector are capable of detecting the FPN signal, and capable of simultaneously acquiring two pieces of OCT data each corrected based on the FPN signal,
The light amount division ratio of the reflected light from the test object by the second light splitter is: optical path toward the first detector<optical path toward the second detector via the first light splitter An OCT apparatus characterized by: First OCT data based on the first interference signal and second OCT data based on the second interference signal, the FPN signal detected by the first detector and the second detector 2. The OCT apparatus according to claim 1, further comprising an arithmetic processing unit that obtains synthetic OCT data by synthesizing based on the FPN signals detected by. a first polarization adjusting means arranged in at least one of the first reference optical path and the second reference optical path and adjusting the polarization state of the reference light;
The first polarization adjusting means is controlled such that the signal strength ratio between the FPN signal detected by the first detector and the FPN signal detected by the second detector satisfies a predetermined tolerance condition. a control means for adjusting the polarization state such that
The OCT apparatus according to any one of claims 1 and 2, comprising:

Images