JP2010256294A - Optical image measuring device - Google Patents

Abstract

An optical image measuring apparatus that can prevent a failure of a light source without using an isolator and can optically improve image quality.
A fiber coupler 162 splits low-coherence light L0 into signal light LS and reference light LR. An optical fiber 165 that guides the signal light LS toward the eye E, guides the signal light LS from the eye E to the fiber coupler 162, and an optical fiber 166 guides the signal light LS to the fiber coupler 167 in the signal optical path. Provided. In the reference optical path, an optical fiber 163 that guides the reference light LR, a corner cube 173 that reflects the reference light LR twice, an optical fiber 164 that guides the reference light LR to the fiber coupler 167, and a dispersion compensation member for improving image quality 172 and a polarization correction member 174 are provided. The fiber coupler 167 generates interference light LC between the signal light LS and the reference light LR. A tomographic image is formed based on the detection result of the interference light LC.
[Selection] Figure 2

Description

  The present invention relates to an optical image measurement device that forms a tomographic image of an object to be measured by using optical coherence tomography (Optical Coherence Tomography).

  In recent years, optical coherence tomography, which forms an image representing the surface form and internal form of an object to be measured using a light beam from a laser light source or the like, has attracted attention. Optical coherence tomography does not have invasiveness to the human body like an X-ray CT apparatus, and therefore is expected to be applied particularly in the medical field and biological field.

  Patent Document 1 discloses an apparatus to which optical coherence tomography is applied. In this device, the measuring arm scans an object with a rotary turning mirror (galvanomirror), a reference mirror is installed on the reference arm, and the intensity of the interference light of the light beam from the measuring arm and the reference arm is dispersed at the exit. An interferometer is provided for analysis by the instrument. Further, the reference arm is configured to change the phase of the reference light beam stepwise by a discontinuous value.

  The apparatus of Patent Document 1 uses a so-called “Fourier Domain OCT (Fourier Domain Optical Coherence Tomography)” technique. In other words, a low-coherence beam is irradiated onto the object to be measured, the reflected light and the reference light are superimposed to generate interference light, and the spectral intensity distribution of the interference light is acquired and subjected to Fourier transform. Thus, the form of the object to be measured in the depth direction (z direction) is imaged. This type of technique is also referred to as a spectral domain.

  Furthermore, the apparatus described in Patent Document 1 includes a galvanometer mirror that scans a light beam (signal light), thereby forming an image of a desired measurement target region of the object to be measured. Since this apparatus is configured to scan the light beam only in one direction (x direction) orthogonal to the z direction, the image formed by this apparatus is in the scanning direction (x direction) of the light beam. It becomes a two-dimensional tomogram in the depth direction (z direction) along.

  In Patent Document 2, a plurality of horizontal two-dimensional tomographic images are formed by scanning signal light in the horizontal direction (x direction) and the vertical direction (y direction), and the measurement range is determined based on the plurality of tomographic images. A technique for acquiring and imaging three-dimensional tomographic information is disclosed. Examples of the three-dimensional imaging include a method of displaying a plurality of tomographic images side by side in a vertical direction (referred to as stack data) and a method of rendering a plurality of tomographic images to form a three-dimensional image. Conceivable.

  Patent Documents 3 and 4 disclose other types of OCT apparatuses. Patent Document 3 scans the wavelength of light applied to an object to be measured, acquires a spectral intensity distribution based on interference light obtained by superimposing reflected light of each wavelength and reference light, On the other hand, an OCT apparatus for imaging the form of an object to be measured by performing Fourier transform on the object is described. Such an OCT apparatus is called a swept source type. The swept source type is an example of a Fourier domain type.

  In Patent Document 4, the traveling direction of light is obtained by irradiating the object to be measured with light having a predetermined beam diameter, and analyzing the component of interference light obtained by superimposing the reflected light and the reference light. An OCT apparatus for forming an image of an object to be measured in a cross-section orthogonal to is described. Such an OCT apparatus is called a full-field type or an en-face type.

  Patent Document 5 discloses a fundus oculi observation device in which optical coherence tomography is applied to the ophthalmic field. Note that a fundus camera is known as a fundus oculi observation device before optical coherence tomography is applied (see, for example, Patent Document 6). The fundus oculi observation device using optical coherence tomography has an advantage that a tomographic image and a three-dimensional image of the fundus can be acquired as compared with a fundus camera that only photographs the fundus from the front. Therefore, it is expected to contribute to improvement of diagnostic accuracy and early detection of lesions. An apparatus that acquires a tomographic image of the cornea using optical coherence tomography is also known (see, for example, Patent Document 7).

  Patent Document 8 also discloses an ophthalmologic apparatus (fundus observation apparatus) that applies optical coherence tomography. The optical system of this ophthalmic apparatus includes a first coupler that divides low-coherence light from a light source into reference light and signal light (measurement light), guides the signal light to the eye to be examined, and converts the fundus reflection light of the signal light to the first A signal optical path that leads to one coupler, a second coupler, an optical fiber that leads the signal light and the first coupler to the second coupler, and a reference optical path that guides the reference light from the first coupler to the second coupler The signal light and the reference light are superimposed by the second coupler to generate interference light, and the spectrum of the interference light is detected. Further, an isolator is provided between the light source and the first coupler to prevent failure of the light source and deterioration of performance when a large amount of light (strong intensity) is incident on the light source.

  In addition, the reference optical path of the ophthalmic apparatus includes an optical fiber connected to the first coupler and an optical fiber connected to the second coupler. Between these optical fibers, a collimator lens, an optical path length correction glass, an attenuation filter, and a focusing lens are provided. The fiber end of the optical fiber connected to the second coupler and the focusing lens can be moved integrally to change the optical path length of the reference light.

JP 11-325849 A JP 2002-139421 A JP 2007-24677 A JP 2006-153838 A JP 2008-73099 A JP-A-9-276232 Japanese Patent Laid-Open No. 8-206075 JP 2007-151622 A

  However, the conventional optical image measuring apparatus as described above has the following problems. First, an isolator for protecting the light source is expensive, and the device itself is also expensive. Furthermore, when passing through the isolator, the polarization state of the low-coherence light may change, and the image quality may deteriorate.

  Further, in the configuration like the apparatus of Patent Document 8, the polarization state correction (polarization correction) and the dispersion compensation (matching the wavelength dispersion characteristics of the signal light and the reference light) cannot be optically performed. There is a risk that the quality of the displayed image will deteriorate. Although it is possible to improve image quality by image processing, it is generally more accurate to optically perform dispersion compensation or the like. In the medical field, it is necessary to improve the accuracy of the image in order to grasp the state of the subject more accurately. For this purpose, the state of the subject is improved by optically improving the image quality rather than relying on image processing. It is desirable to acquire an image that more accurately reflects.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical image measurement device capable of preventing failure of a light source and performance deterioration without using an isolator. It is in. Another object of the present invention is to provide an optical image measuring device capable of optically improving the image quality.

  In order to achieve the above object, the invention described in claim 1 is directed to a light source that outputs low-coherence light, and the output low-coherence light is divided into signal light and reference light, and is transmitted through a signal light path. An optical system that generates interference light by superimposing the signal light that has passed through the measurement object and the reference light that has passed through the reference optical path, and that generates the detection signal by detecting the generated interference light, and the generated And an image forming unit that forms an image of the object to be measured based on a detection signal, wherein the optical system guides the low-coherence light output from the light source. An optical fiber; a first fiber coupler that divides the guided low-coherence light into signal light and reference light; and a second fiber coupler. The first fiber coupler is used as the signal optical path. One end A second optical fiber for guiding the signal light toward the object to be measured and guiding the signal light passing through the object to be measured to the first fiber coupler, and the second light. And a third optical fiber for guiding the signal light guided to the first fiber coupler by a fiber to the second fiber coupler, and one end connected to the first fiber coupler as the reference optical path A fourth optical fiber that guides the reference light, a reflecting means that reflects the reference light emitted from the other end of the fourth optical fiber a plurality of times, and a reference light that passes through the reflecting means Dispersion adjustment for adjusting a dispersion characteristic of the reference light, which is provided on an optical path between the fifth optical fiber guided to the second fiber coupler and the fourth optical fiber and the fifth optical fiber. Means and / or said reference Polarization adjustment means for adjusting the polarization state of the second optical fiber, wherein the second fiber coupler is configured to receive the signal light guided by the third optical fiber and the reference light guided by the fifth optical fiber. The interference light is generated by superimposing the interference light.

  The invention according to claim 2 is the optical image measurement device according to claim 1, wherein the reflecting means reflects the reference light an even number of times.

  The invention according to claim 3 is the optical image measurement device according to claim 1 or 2, wherein the reflecting means includes a beam splitter for dividing the reference light, and one of the divided light beams. A first reflecting member that reflects the reference light a plurality of times and guides it to the beam splitter; and a second reflecting member that reflects the other reference light a plurality of times and guides it to the beam splitter. And the second reflecting member is disposed with respect to the beam splitter so that an optical path length of the one reference light and an optical path length of the other reference light are different, and the fifth optical fiber includes the first optical fiber The one reference light passing through one reflection member and / or the other reference light passing through the second reflection member are guided to the second fiber coupler, and the image forming means Interference between reference light and signal light An image of the first depth of the object to be measured is formed based on the detection signal of the second object, and an image of the second depth of the object to be measured is formed based on the detection signal of the interference light between the other reference light and the signal light. An image is formed.

  The invention according to claim 4 is the optical image measurement device according to any one of claims 1 to 3, wherein the optical system moves the reflecting means to move the reference optical path. It includes a changing means for changing the optical path length.

  The invention according to claim 5 is the optical image measurement device according to any one of claims 1 to 4, wherein the dispersion adjusting means includes a pair of prisms and the pair of prisms. And moving means for relatively moving.

  The invention according to claim 6 is the optical image measurement device according to any one of claims 1 to 4, wherein the polarization adjusting means converts circularly polarized light or elliptically polarized light into linearly polarized light or Two quarter-wave plates for converting linearly polarized light into circularly-polarized light or elliptically-polarized light, respectively, and a half-wave plate disposed between the two quarter-wave plates for changing the direction of the polarization plane of the reference light And rotating means for rotating the half-wave plate.

  The invention according to claim 7 is the optical image measurement device according to any one of claims 1 to 4, wherein the polarization adjusting means changes the polarization state of the reference light to linearly polarized light. It includes a polarizing plate for conversion, a quarter-wave plate for converting the reference light converted into linearly polarized light into circularly polarized light, and a rotating means for rotating the polarizing plate.

  The optical image measurement device according to the present invention superimposes a first fiber coupler that divides low-coherence light into signal light and reference light, and signal light that passes through the signal light path and reference light that passes through the reference light path. 2 fiber couplers.

  In the signal optical path, the second optical fiber that guides the signal light toward the object to be measured and guides the signal light passing through the object to be measured to the first fiber coupler, and the guided signal light And a third optical fiber that guides the light to the second fiber coupler.

  The reference optical path includes a fourth optical fiber that guides the reference light, a reflection unit that reflects the reference light emitted from the fourth optical fiber a plurality of times, and a second reference light that passes through the reflection unit. A fifth optical fiber guided to the fiber coupler, and a dispersion adjusting means and / or a polarization adjusting means provided on the optical path between the fourth optical fiber and the fifth optical fiber. .

  The second fiber coupler generates interference light by superimposing the signal light guided by the third optical fiber and the reference light guided by the fifth optical fiber to generate a detection signal. The image forming means forms an image of the object to be measured based on the generated detection signal.

  With such a configuration, the reference light can be prevented from entering the light source. In addition, a part of the signal light incident on the first fiber coupler via the object to be measured reaches the light source through the first optical fiber, but has passed through various optical elements in the signal light path and the object to be measured. The amount of signal light is relatively small, and only part of the signal light is incident on the light source. Taking these into consideration, the amount of light returning to the light source is sufficiently small, and therefore failure of the light source and performance deterioration can be prevented without using an isolator.

  Furthermore, since the dispersion adjusting means and the polarization adjusting means are provided in the reference optical path, it is possible to improve the image quality optically by adjusting the dispersion characteristics and the polarization state of the reference light using these.

  As described above, according to the optical image measurement device of the present invention, it is possible to prevent the failure of the light source and the performance deterioration without using an isolator, and it is possible to optically improve the image quality.

It is a schematic structure figure showing an example of the whole composition of the embodiment of the optical image measuring device (ophthalmic device) concerning this invention. It is a schematic block diagram showing an example of a structure of the OCT unit in embodiment of the optical image measuring device (ophthalmic apparatus) concerning this invention. It is a schematic block diagram showing an example of the composition of the control system of the embodiment of the optical image measuring device (ophthalmic device) concerning this invention. It is a schematic block diagram showing an example of a structure of the OCT unit in embodiment of the optical image measuring device (ophthalmic apparatus) concerning this invention. It is a schematic block diagram showing an example of the composition of the control system of the embodiment of the optical image measuring device (ophthalmic device) concerning this invention.

  An example of an embodiment of an optical image measurement device according to the present invention will be described in detail with reference to the drawings.

  The optical image measurement device according to the present invention forms a tomographic image or a three-dimensional image of an object to be measured using optical coherence tomography. As the optical image measurement device according to the present invention, any configuration for guiding signal light and reference light by an optical fiber is applied. Note that an image acquired by optical coherence tomography may be referred to as an OCT image.

  In the following embodiments, a configuration for acquiring an OCT image of the fundus or cornea using a Fourier domain type technique will be described in detail. In particular, in this embodiment, an ophthalmologic apparatus having a configuration in which a fundus camera and an optical image measurement device are combined is taken up as in the device disclosed in Patent Document 5.

  Even when other configurations are applied, the same operations and effects can be obtained by applying the same configuration of the optical image measurement device (fiber optical system) as in this embodiment. For example, the same configuration as that of this embodiment can be applied even when the configuration is a single optical image measurement device or when a type other than the Fourier domain (such as a swept source type) is used. is there.

<First Embodiment>
[Constitution]
As shown in FIG. 1, the ophthalmologic apparatus 1 includes a fundus camera unit 1 </ b> A, an OCT unit 150, and an arithmetic control device 200. The fundus camera unit 1A has an optical system that is substantially the same as that of a conventional fundus camera. The fundus camera is a device that captures the surface of the fundus and acquires a two-dimensional image. In addition, the fundus camera is used for photographing a fundus blood vessel. The OCT unit 150 stores an optical system for acquiring an OCT image of the fundus. The arithmetic and control unit 200 includes a computer that executes various arithmetic processes and control processes.

  One end of a connection line 152 is attached to the OCT unit 150. A connector 151 for connecting the connection line 152 to the retinal camera unit 1A is attached to the other end of the connection line 152. An optical fiber (optical fiber 165 shown in FIG. 2) that guides signal light is conducted through the connection line 152. The OCT unit 150 and the fundus camera unit 1A are optically connected via a connection line 152. The arithmetic and control unit 200 is connected to each of the fundus camera unit 1A and the OCT unit 150 via a communication line that transmits an electrical signal.

[Fundus camera unit]
The fundus camera unit 1A includes an optical system for forming a two-dimensional image representing the form of the fundus surface. Here, the two-dimensional image of the fundus surface includes a color image and a monochrome image obtained by photographing the fundus surface, and further a fluorescent image (fluorescein fluorescent image, indocyanine green fluorescent image, etc.) and the like.

  The fundus camera unit 1A is provided with an illumination optical system 100 and a photographing optical system 120, as in a conventional fundus camera. The illumination optical system 100 irradiates the fundus oculi Ef with illumination light. The imaging optical system 120 guides the fundus reflection light of the illumination light to the imaging devices 10 and 12. The imaging optical system 120 guides the signal light from the OCT unit 150 to the fundus oculi Ef and guides the signal light passing through the fundus oculi Ef to the OCT unit 150.

  The illumination optical system 100 includes an observation light source 101, a condenser lens 102, a photographing light source 103, a condenser lens 104, exciter filters 105 and 106, a ring translucent plate 107 (ring slit 107a), a mirror 108, as in a conventional fundus camera. An LCD (Liquid Crystal Display) 109, an illumination stop 110, a relay lens 111, a perforated mirror 112, and an objective lens 113 are included.

  The observation light source 101 outputs illumination light including a near-infrared wavelength in the range of about 700 nm to 800 nm, for example. This near-infrared light is set shorter than the wavelength of light used in the OCT unit 150 (described later). The imaging light source 103 outputs illumination light including wavelengths in the visible region in the range of about 400 nm to 700 nm, for example.

  The illumination light output from the observation light source 101 is a perforated mirror 112 through condenser lenses 102 and 104, (exciter filter 105 or 106) ring translucent plate 107, mirror 108, LCD 109, illumination diaphragm 110, and relay lens 111. To reach. Further, the illumination light is reflected by the perforated mirror 112 and enters the eye E through the objective lens 113 to illuminate the fundus oculi Ef. On the other hand, the illumination light output from the imaging light source 103 enters the eye E through the condenser lens 104 to the objective lens 113 and illuminates the fundus oculi Ef.

  The photographing optical system 120 includes an objective lens 113, a perforated mirror 112 (hole 112a), a photographing aperture 121, barrier filters 122 and 123, a variable power lens 124, a relay lens 125, a photographing lens 126, a dichroic mirror 134, and a field lens. (Field lens) 128, half mirror 135, relay lens 131, dichroic mirror 136, photographing lens 133, imaging device 10, reflection mirror 137, photographing lens 138, imaging device 12, lens 139 and LCD 140 are configured. The photographing optical system 120 has substantially the same configuration as a conventional fundus camera.

  The dichroic mirror 134 reflects fundus reflection light (having a wavelength included in a range of about 400 nm to 800 nm) of illumination light from the illumination optical system 100. The dichroic mirror 134 transmits the signal light LS (for example, having a wavelength included in the range of about 800 nm to 900 nm; see FIG. 2) from the OCT unit 150.

  The dichroic mirror 136 reflects the fundus reflection light of the illumination light from the observation light source 101. Further, the dichroic mirror 136 transmits the fundus reflection light of the illumination light from the imaging light source 103.

  The LCD 140 displays a fixation target (internal fixation target) for fixing the eye E to be examined. Light from the LCD 140 is collected by the lens 139, reflected by the half mirror 135, and reflected by the dichroic mirror 136 via the field lens 128. Further, this light is incident on the eye E through the photographing lens 126, the relay lens 125, the variable power lens 124, the aperture mirror 112 (the aperture 112a thereof), the objective lens 113, and the like. Thereby, the internal fixation target is projected onto the fundus oculi Ef.

  By changing the display position of the internal fixation target by the LCD 140, the fixation direction of the eye E can be changed. As the fixation direction of the eye E, for example, as with a conventional fundus camera, a fixation direction for acquiring an image centered on the macular portion of the fundus oculi Ef or an image centered on the optic disc is acquired. And the fixation direction for acquiring an image centered on the fundus center between the macula and the optic disc.

  The imaging device 10 includes an imaging element 10a. The imaging device 10 can particularly detect light having a wavelength in the near infrared region. That is, the imaging device 10 functions as an infrared television camera that detects near-infrared light. The imaging device 10 detects near infrared light and outputs a video signal. The imaging device 10a is an arbitrary imaging device (area sensor) such as a CCD (Charge Coupled Devices) or a CMOS (Complementary Metal Oxide Semiconductor).

  The imaging device 12 includes an imaging element 12a. The imaging device 12 can particularly detect light having a wavelength in the visible region. That is, the imaging device 12 functions as a television camera that detects visible light. The imaging device 12 detects visible light and outputs a video signal. The image sensor 12a is configured by an arbitrary image sensor (area sensor), similarly to the image sensor 10a.

  The touch panel monitor 11 displays the fundus oculi image Ef ′ based on the video signals from the image sensors 10a and 12a. The video signal is sent to the arithmetic and control unit 200.

  The fundus camera unit 1A is provided with a scanning unit 141 and a lens 142. The scanning unit 141 scans the irradiation position of the signal light LS output from the OCT unit 150 to the fundus oculi Ef.

  The scanning unit 141 scans the signal light LS on the xy plane shown in FIG. For this purpose, the scanning unit 141 is provided with, for example, a galvanometer mirror for scanning in the x direction and a galvanometer mirror for scanning in the y direction.

[OCT unit]
Next, the configuration of the OCT unit 150 will be described with reference to FIG. The OCT unit 150 divides the low-coherence light into reference light and signal light, and interferes the signal light passing through the object to be measured (eye to be examined) via the predetermined signal optical path and the reference light passing through the predetermined reference optical path An optical system that generates interference light and detects the interference light. The detection result (detection signal) of the interference light is sent to the arithmetic and control unit 200.

  The low coherence light source 160 is a broadband light source that outputs a broadband low coherence light L0. As this broadband light source, for example, a super luminescent diode (SLD), a light emitting diode (LED), or the like can be used. The low coherence light source 160 is an example of the “light source” of the present invention.

  The low coherence light L0 includes, for example, light having a wavelength in the near infrared region, and has a temporal coherence length of about several tens of micrometers. The low coherence light L0 includes a wavelength longer than the illumination light (wavelength of about 400 nm to 800 nm) of the fundus camera unit 1A, for example, a wavelength in the range of about 800 nm to 900 nm.

  The low coherence light L0 output from the low coherence light source 160 is guided to the fiber coupler 162 through the optical fiber 161. The optical fiber 161 is configured by, for example, a single mode fiber or a PM fiber (Polarization maintaining fiber). The fiber coupler 162 splits the low coherence light L0 into the reference light LR and the signal light LS. The fiber coupler 162 is configured, for example, so that 80% of the light amount of the low coherence light L0 is the reference light LR and 20% is the signal light LS. The division ratio of the low coherence light L0 by the fiber coupler 162 is determined in advance in consideration of the standard value of the amount of light that can be irradiated to the eye E, the output light amount of the low coherence light source 160, and the like.

  The fiber coupler 162 has both functions of a means for splitting light (splitter) and a means for superposing light (coupler), but here it is conventionally referred to as a “fiber coupler” ( The same applies to the fiber coupler 167).

  The reference light LR generated by the fiber coupler 162 is guided by an optical fiber 163 made of a single mode fiber or the like and emitted from the end of the fiber. A collimator 171 is attached to the fiber end. For example, the collimator 171 is provided with a collimator lens that converts the reference light LR emitted from the fiber end into a parallel light beam.

  The reference light LR converted into a parallel light beam by the collimator 171 passes through the dispersion compensation member 172. The dispersion compensation member 172 is constituted by, for example, a pair of (that is, two) prisms (a wedge prism, a triangular prism, etc.). The pair of prisms are relatively moved by a drive mechanism described later. The moving direction is, for example, a direction orthogonal to the traveling direction of the reference light LR. Note that “relatively move” means that one or both of the two prisms are moved, in other words, movement that changes the position of the other prism as viewed from one of the two prisms. .

  The pair of prisms are moved, for example, to positions where the formed OCT image has an optimum image quality. The image quality can be evaluated using any known image processing. Further, the positions of the pair of prisms may be determined while observing the OCT image with the naked eye.

  Further, a pair of prisms may be disposed at a position where the state of the detection signal of the interference light (amplitude level or the like) is suitable. The suitability of the state of the detection signal can be determined, for example, by referring to a preset threshold value.

  The positions of the pair of prisms can be determined at an arbitrary timing. For example, the position of the pair of prisms can be determined for each eye to be examined, for each measurement, or before actual measurement of the object to be measured, such as when the apparatus is activated every day. Further, the positions of the pair of prisms may be determined when performing maintenance of the apparatus. This position determination operation may be performed manually or automatically.

  Furthermore, it is possible to determine the positions of the pair of prisms in a state where the eye E is not measured. In that case, for example, a model eye can be used as an object to be measured.

  When determining the position of the pair of prisms while measuring the eye E, it is possible to consider not only the dispersion of the signal light path and the reference light path by the optical elements but also the dispersion of the eye E itself. . On the other hand, when the positions of the pair of prisms are determined in a state where the eye E is not measured, the dispersion of the signal light path by (at least a part of) the optical elements is matched with the dispersion of the reference light path by the optical elements. Dispersion compensation.

  It is also possible to previously obtain dispersion values of various optical elements arranged in the signal optical path and the reference optical path, and determine the positions of the pair of prisms by referring to this information.

  The reference light LR that has passed through the dispersion compensation member 172 reaches the corner cube 173. The corner cube 173 is a member that has, for example, two reflecting surfaces 173a and 173b orthogonal to each other and reflects the incident reference light LR in the same direction (however, the optical axes do not coincide). It is also possible to apply a corner cube having three reflecting surfaces.

  The corner cube 173 can be moved along the traveling direction of the reference light LR as shown by a double-sided arrow in FIG. Thereby, the optical path length of the reference light LR is changed. The optical path length of the reference light LR can be changed according to the axial length of the eye E and the working distance (distance between the objective lens 113 and the eye E).

  The reference light LR that has passed through the corner cube 173 passes through the polarization correction member 174. The polarization correction member 174 includes, for example, two ¼ wavelength plates and a ½ wavelength plate. The half-wave plate is disposed between two quarter-wave plates.

  A quarter-wave plate is a polarizer that shifts the phase difference between the ordinary ray component and extraordinary ray component of light passing therethrough by π / 2, and its action is to change circularly polarized light or elliptically polarized light into linearly polarized light, Alternatively, linearly polarized light is converted into circularly polarized light or elliptically polarized light. Note that linearly polarized light that is incident with the polarization plane inclined by 45 degrees with respect to the optical principal axis is converted into circularly polarized light. The half-wave plate is generally a polarizer that generates a phase difference of ½ wavelength between two linearly polarized light components that vibrate in directions orthogonal to each other, and rotates the polarization plane of the light beam. Acts as follows.

  The first quarter-wave plate converts the polarization state of the reference light LR that has passed through the corner cube 173. More specifically, when the reference light LR passing through the corner cube 173 is circularly polarized light, the first wave plate converts it into linearly polarized light. Conversely, when the reference light LR that has passed through the corner cube 173 is linearly polarized light, the first wave plate converts it to circularly polarized light. Note that the first wave plate may convert elliptically polarized light into linearly polarized light and linearly polarized light into elliptically polarized light.

  The half-wave plate changes the direction of the polarization plane of the reference light LR whose polarization state has been converted by the quarter-wave plate. The half-wave plate is rotated around the optical axis of the reference optical path by a drive mechanism described later. For example, the half-wave plate is rotated to a position where an OCT image to be formed has an optimum image quality. The image quality can be evaluated using any known image processing. Further, the rotational position of the half-wave plate may be determined while observing the OCT image with the naked eye. This position determination operation may be performed manually or automatically.

  Further, the half-wave plate may be rotated to a position where the state (amplitude level or the like) of the detection signal of the interference light is suitable. The suitability of the state of the detection signal can be determined, for example, by referring to a preset threshold value.

  The rotational position of the half-wave plate can be determined at an arbitrary timing. For example, the rotational position of the half-wave plate can be determined for each eye to be examined or for each measurement.

  Furthermore, the rotational position of the half-wave plate can be determined in a state where the eye E is not measured. In that case, for example, a model eye can be used as an object to be measured. Further, a reflection mirror may be arranged to determine the rotational position of the half-wave plate.

  The second quarter wave plate will be described. The half-wave plate is rotated so that the polarization plane of the reference light LR and the polarization plane of the signal light LS coincide (substantially), and then the second quarter-wave plate is rotated to adjust the degree of polarization. (Nearly) so that the optimum image quality is obtained. As an example, the second quarter-wave plate can be rotated with reference to the evaluation value of the quality of the image.

  Here, the optical path length correction of the reference light LR will be described. In this optical path length correction, in order to obtain a good interference signal, the optical path length of the signal light LS and the optical path length of the reference light LR are matched (substantially). As an example, the corner cube 173 disposed in the reference optical path is moved to a position where a good interference signal can be obtained. The quality of the interference signal can be evaluated, for example, by referring to the evaluation value of the quality of the image or by observing and evaluating the actual image.

  The reference light LR that has passed through the polarization correction member 174 is converted into focused light by the collimator 175, enters the optical fiber 164, and is guided to the fiber coupler 167. Note that an arbitrary optical element such as an optical element for reducing the amount of light can be appropriately provided in the reference optical path.

  The density filter 196 functions as a neutral density filter that reduces the amount of the reference light LR. The density filter 196 is configured by, for example, a rotary ND (Neutral Density) filter. The density filter 196 is rotationally driven by a drive mechanism (not shown) to change the amount of the reference light LR that contributes to the generation of the interference light LC.

  Next, the signal optical path will be described. The signal light LS generated by the fiber coupler 162 is guided by an optical fiber 165 (passing through the connection line 152) made of a single mode fiber or the like and guided to the fundus camera unit 1A. Further, the signal light LS passes through the lens 142, the scanning unit 141, the dichroic mirror 134, the photographing lens 126, the relay lens 125, the variable magnification lens 124, the photographing aperture 121, the hole 112 a of the aperture mirror 112, and the objective lens 113. The eye E is irradiated to the fundus Ef. When irradiating the fundus oculi Ef with the signal light LS, the barrier filters 122 and 123 are retracted from the optical path in advance.

  The signal light LS incident on the eye E is focused and reflected on the fundus oculi Ef. At this time, the signal light LS is not only reflected by the surface of the fundus oculi Ef, but also reaches the deep region of the fundus oculi Ef and is scattered at the refractive index boundary. Therefore, the signal light LS passing through the fundus oculi Ef includes information reflecting the surface form of the fundus oculi Ef and information reflecting the state of backscattering at the refractive index boundary of the deep tissue of the fundus oculi Ef. This light may be simply referred to as “fundus reflected light of the signal light LS”.

  The fundus reflection light of the signal light LS is guided on the same path as the signal light LS toward the eye E to be examined in the reverse direction and is collected on the end surface of the optical fiber 165. Further, the fundus reflection light of the signal light LS enters the OCT unit 150 through the optical fiber 165 and returns to the fiber coupler 162.

  A part of the signal light LS enters the optical fiber 166 via the fiber coupler 162 and is guided to the fiber coupler 167. The remaining portion of the signal light LS enters the optical fiber 161 and returns to the low-coherence light source 160, but the amount of the signal light LS attenuates when passing through the optical element on the signal light path or the eye E to be examined. Furthermore, considering that the light amount of the signal light LS generated by the fiber coupler 162 is sufficiently smaller than the light amount of the reference light LR (in the above example, signal light: reference light = 2: 8). There is no possibility that the return light of the signal light LS will cause the failure of the low-coherence light source 160 or the performance degradation.

  The fiber coupler 167 superimposes the reference light LR guided by the optical fiber 164 and the signal light LS guided by the optical fiber 166 to generate the interference light LC. The fiber coupler 167 superimposes the reference light LR and the signal light LS at a ratio of 1: 9, for example. The interference light LC is guided to the spectrometer 180 through an optical fiber 168 made of a single mode fiber or the like.

  The spectrometer (spectrometer) 180 detects the spectral component of the interference light LC. The spectrometer 180 includes a collimator lens 181, a diffraction grating 182, an imaging lens 183, and a CCD 184. The diffraction grating 182 may be transmissive or reflective. Further, in place of the CCD 184, other light detection elements (line sensor or area sensor) such as CMOS may be used.

  The interference light LC incident on the spectrometer 180 is converted into a parallel light beam by the collimator lens 181, and is split (spectral decomposition) by the diffraction grating 182. The split interference light LC is imaged on the imaging surface of the CCD 184 by the imaging lens 183. The CCD 184 detects each spectral component of the separated interference light LC and converts it into electric charges. The CCD 184 accumulates this electric charge and generates a detection signal. Further, the CCD 184 sends this detection signal to the arithmetic and control unit 200.

[Calculation control device]
The arithmetic and control unit 200 will be described. The arithmetic and control unit 200 analyzes the detection signal input from the CCD 184 and forms an OCT image of the fundus oculi Ef. The arithmetic processing for this is the same as that of a conventional Fourier domain type OCT apparatus.

  The arithmetic and control unit 200 controls each part of the fundus camera unit 1A and the OCT unit 150.

  As control of the fundus camera unit 1A, the arithmetic and control unit 200 controls the output of illumination light by the observation light source 101 and the imaging light source 103, and controls the insertion / retraction operation of the exciter filters 105 and 106 and the barrier filters 122 and 123 on the optical path. Then, operation control of a display device such as the LCD 140, movement control of the illumination aperture 110 (control of the aperture value), control of the aperture value of the photographing aperture 121, movement control of the variable power lens 124 (control of magnification), and the like are performed. Further, the arithmetic and control unit 200 controls the scanning unit 141 to scan the signal light LS.

  Further, as control of the OCT unit 150, the arithmetic and control unit 200 performs control of output of the low coherence light L0 by the low coherence light source 160, control of charge accumulation time, charge accumulation timing, and signal transmission timing by the CCD 184. Further, the arithmetic and control unit 200 performs movement control of the pair of prisms of the dispersion compensation member 172, movement control of the corner cube 173, rotation control of the half-wave plate of the polarization correction member 174, and the like.

  The arithmetic and control unit 200 includes a microprocessor, a RAM, a ROM, a hard disk drive, a keyboard, a mouse, a display, a communication interface, and the like, like a conventional computer. A computer program for controlling the ophthalmic apparatus 1 is stored in the hard disk drive. Further, the arithmetic and control unit 200 may include a dedicated circuit board that forms an OCT image based on a detection signal from the CCD 184.

  The arithmetic and control unit 200 may be stored in the same housing as the fundus camera unit 1A. In that case, the display may be the same as the touch panel monitor 11, and the operation device such as the mouse may be a joystick, a button, a switch, or the like similar to a conventional fundus camera. The OCT unit 150 may also be stored in the same housing as the fundus camera unit 1A.

[Control system]
The configuration of the control system of the ophthalmologic apparatus 1 will be described with reference to FIG.

(Control part)
The control system of the ophthalmologic apparatus 1 is configured around the control unit 210 of the arithmetic and control unit 200. The control unit 210 includes, for example, the aforementioned microprocessor, RAM, ROM, hard disk drive, communication interface, and the like.

  The control unit 210 is provided with a main control unit 211 and a storage unit 212. The main control unit 211 manages the various controls described above.

  The storage unit 212 stores various data. Examples of data stored in the storage unit 212 include image data of an OCT image, image data of a fundus oculi image Ef ′, and eye information to be examined. The eye information includes information about the subject such as patient ID and name, and information about the eye such as left / right eye identification information. The main control unit 211 performs a process of writing data to the storage unit 212 and a process of reading data from the storage unit 212.

(Image forming part)
The image forming unit 220 receives image signals from the imaging devices 10 and 12 and forms image data of the fundus oculi image Ef ′.

  The image forming unit 220 forms image data of a tomographic image of the fundus oculi Ef based on the detection signal from the CCD 184. This process includes processes such as noise removal (noise reduction), filter processing, and FFT (Fast Fourier Transform) as in the conventional Fourier domain type optical coherence tomography.

  The image forming unit 220 includes, for example, the above-described circuit board and communication interface. In this specification, “image data” and “image” presented based on the “image data” may be identified with each other.

(Image processing unit)
The image processing unit 230 performs various types of image processing and analysis processing on the image formed by the image forming unit 220. For example, the image processing unit 230 executes various correction processes such as image brightness correction and dispersion correction.

  In addition, the image processing unit 230 forms image data of a three-dimensional image of the fundus oculi Ef by executing an interpolation process for interpolating pixels between tomographic images formed by the image forming unit 220.

  Note that the image data of a three-dimensional image means image data in which pixel positions are defined by a three-dimensional coordinate system. As image data of a three-dimensional image, there is image data composed of voxels arranged three-dimensionally. This image data is called volume data or voxel data. When displaying an image based on volume data, the image processing unit 230 performs rendering processing (volume rendering, MIP (Maximum Intensity Projection), etc.) on the volume data, and views the image from a specific gaze direction. Image data of a pseudo three-dimensional image is formed. The pseudo three-dimensional image is displayed on a display device such as the display unit 240.

  It is also possible to form stack data of a plurality of tomographic images as image data of a three-dimensional image. The stack data is image data obtained by three-dimensionally arranging a plurality of tomographic images obtained along a plurality of scanning lines based on the positional relationship of the scanning lines. That is, stack data is image data obtained by expressing a plurality of tomographic images originally defined by individual two-dimensional coordinate systems by one three-dimensional coordinate system (that is, by embedding them in one three-dimensional space). is there.

  The image processing unit 230 performs image quality evaluation processing when performing dispersion compensation or polarization correction. As described above, this process is an arbitrary known process for evaluating the image quality. When image quality is evaluated by visual observation, the image processing unit 230 does not need to perform image evaluation processing.

  The image processing unit 230 includes, for example, the above-described microprocessor, RAM, ROM, hard disk drive, circuit board, and the like.

(Display section, operation section)
The display unit 240 includes a display. The operation unit 250 includes various input devices and operation devices such as a keyboard, a mouse, a joystick, a button, a key, and a switch.

  The display unit 240 and the operation unit 250 do not need to be configured as individual devices. For example, a device in which the display unit 240 and the operation unit 250 are integrated, such as a touch panel LCD, can be used.

(Drive mechanism)
As described above, the OCT unit 150 is provided with various drive mechanisms. The optical path length changing mechanism 260 changes the optical path length (reference optical path length) of the reference light LR by moving the corner cube 173 along the traveling direction of the reference light LR. The optical path length changing mechanism 260 corresponds to “changing means” of the present invention.

  The dispersion compensation drive mechanism 270 changes the dispersion state of the reference light LR by relatively moving the pair of prisms of the dispersion compensation member 172. The dispersion compensation drive mechanism 270 corresponds to the “moving unit” of the present invention. The polarization correction drive mechanism 280 rotates the half-wave plate of the polarization correction member 174. The polarization correction driving mechanism 280 corresponds to the “rotating unit” of the present invention.

  Each of these drive mechanisms 260, 270, and 280 includes a drive force generator such as a stepping motor (pulse motor) and a transmission member such as a gear that transmits the generated drive force to the drive target member. The The main control unit 211 transmits a control signal (pulse signal or the like) to each driving force generation unit and controls it to thereby control each driving target member (corner cube 173, dispersion compensation member 172, polarization correction member 174). ). Here, the drive mechanisms 260, 270, and 280 can be automatically controlled based on the results of image processing, signal processing, and the like. 270, 280 can also be configured. Here, the automatic control evaluates the image state of the tomographic image (image position of the fundus oculi Ef in the frame, the degree of noise mixing, etc.) while actually forming the tomographic image, and this evaluation value is predetermined. This can be realized by adjusting the dispersion characteristic and polarization state of the reference light LR so as to fall within the allowable range. Further, the detection signal output from the CCD 184 and the signal (spectral intensity distribution, etc.) obtained based on the detection signal are analyzed, and the dispersion characteristic is set so that the signal characteristic (maximum signal intensity, etc.) falls within a predetermined allowable range. Even if the configuration is such that the polarization state is adjusted, the control can be automated.

  Moreover, it is also possible to constitute so that each drive target member is moved manually. In that case, an operation member such as a handle or a lever is provided on the surface of the housing of the ophthalmologic apparatus 1, and a transmission member that transmits the operation content for the operation member is provided.

[Signal light scanning and OCT images]
Here, the scanning of the signal light LS and the OCT image will be described.

  Examples of the scanning mode of the signal light LS by the ophthalmologic apparatus 1 include a horizontal scan, a vertical scan, a cross scan, a radiation scan, a circular scan, a concentric scan, and a spiral scan. These scanning modes are selectively used as appropriate in consideration of the observation site of the fundus, the analysis target (such as retinal thickness), the time required for scanning, the precision of scanning, and the like.

  The horizontal scan scans the signal light LS in the horizontal direction (x direction). The horizontal scan also includes an aspect in which the signal light LS is scanned along a plurality of horizontal scanning lines arranged in the vertical direction (y direction). In this aspect, it is possible to arbitrarily set the scanning line interval. By sufficiently narrowing the interval between the scanning lines, the above-described three-dimensional image can be formed (three-dimensional scan). The same applies to the vertical scan.

  In the cross scan, the signal light LS is scanned along a cross-shaped trajectory composed of two linear trajectories (straight trajectories) orthogonal to each other. In the radiation scan, the signal light LS is scanned along a radial trajectory composed of a plurality of linear trajectories arranged at a predetermined angle. The cross scan is an example of a radiation scan.

  In the circle scan, the signal light LS is scanned along a circular locus. In the concentric scan, the signal light LS is scanned along a plurality of circular trajectories arranged concentrically around a predetermined center position. A circle scan is considered a special case of a concentric scan. The spiral scan scans the signal light LS along a spiral trajectory.

  The scanning unit 141 can scan the signal light LS independently in the x direction and the y direction, respectively, by the configuration as described above. Therefore, the scanning unit 141 can scan the signal light LS along an arbitrary locus on the xy plane. . Thereby, various scanning modes as described above can be realized.

  By scanning the signal light LS in the manner as described above, a tomographic image in the depth direction (x direction) along the scanning line (scanning locus) can be formed. In particular, when the scanning line interval is sufficiently narrow, the above-described three-dimensional image can be formed.

[Action / Effect]
The operation and effect of the ophthalmic apparatus 1 as described above will be described.

  The ophthalmologic apparatus 1 includes a fiber coupler 162 (first fiber coupler) that splits the low-coherence light L0 into the signal light LS and the reference light LR, and the signal light LS and the reference light path that pass through the eye E through the signal light path. And a fiber coupler 167 (second fiber coupler) that interferes with the reference light LR that has passed through.

  Here, the signal light LS is guided to the fiber coupler 167 via the fiber coupler 162. At this time, a part of the signal light LS is incident on the low coherence light source 160, but the amount of light is small as described above, and the reference light LR does not return to the low coherence light source 160. No performance degradation occurs.

  Optical fibers 165 and 166 are provided in the signal light path. One end of the optical fiber 165 is connected to the fiber coupler 162, and guides the signal light LS toward the eye E and guides the fundus reflection light of the signal light LS to the fiber coupler 162. The optical fiber 166 guides the fundus reflection light of the signal light LS guided to the fiber coupler 162 to the fiber coupler 167. The former corresponds to the “second optical fiber” of the present invention, and the latter corresponds to the “third optical fiber”. The optical fiber 161 corresponds to a “first optical fiber”.

  On the other hand, the reference light LR is guided to the fiber coupler 167 via a reference optical path that does not pass through the fiber coupler 162 and is superimposed on the signal light LS. In the reference optical path, optical fibers 163 and 164, collimators 171 and 175, a dispersion compensation member 172, a corner cube 173, and a polarization correction member 174 are provided.

  One end of the optical fiber 163 is connected to the fiber coupler 162 and corresponds to a “fourth optical fiber” of the present invention. The corner cube 173 is configured to reflect the reference light LR emitted from the optical fiber 163 a plurality of times (here, twice), and corresponds to “reflecting means”. The optical fiber 164 guides the reference light LR via the corner cube 173 to the fiber coupler 167, and corresponds to a “fifth optical fiber”.

  The dispersion compensation member 172 is for compensating for the difference in dispersion between the signal light LS and the reference light LR, and acts to adjust (change) the dispersion characteristics of the reference light LR. The dispersion compensation member 172 constitutes “dispersion adjusting means” together with the dispersion compensation drive mechanism 270. The polarization correction member 174 adjusts (changes) the polarization state of the reference light LR, and constitutes a “polarization adjustment unit” together with the polarization correction drive mechanism 280. The dispersion compensation member 172 and the polarization correction member 174 are disposed at arbitrary positions on the reference optical path between the optical fiber 163 and the optical fiber 164, respectively.

  The fiber coupler 167 generates the interference light LC by superimposing the signal light LS via the signal light path and the reference light LR via the reference light path. The spectrometer 180 detects the interference light LC (a spectral component thereof) and generates a detection signal. Based on a plurality of detection signals corresponding to a plurality of scanning points along the scanning line of the signal light LS, the image forming unit 220 (image forming unit) is a tomography that represents a cross-sectional form of the fundus oculi Ef along the scanning line. Form an image.

  According to such an ophthalmologic apparatus 1, it is possible to prevent failure and performance deterioration of the low-coherence light source 160 without using an isolator, and it is possible to optically improve image quality by performing dispersion compensation and polarization correction. It is.

  By the way, if the reflecting surface is obliquely arranged with respect to the traveling direction of the reference light emitted from the fourth optical fiber and the fifth optical fiber is arranged in the reflecting direction, the same effect can be obtained with one reflection. Can be obtained.

  However, such a configuration causes a problem that it is difficult to change the reference optical path length. That is, if the reflecting surface is moved to change the reference optical path length, the reflection direction of the reference light changes, and the position of the fifth optical fiber needs to be changed accordingly. In optical coherence tomography that requires extremely precise position adjustment, it is difficult to perform such an interlocking operation with high accuracy. In view of such circumstances, in this embodiment, the reference light is reflected a plurality of times.

  Further, in this embodiment, the reference light is reflected twice, because this is the configuration that can solve the above problem most simply. Further, by using the corner cube, the traveling directions of the reference light before reflection and after reflection can be made parallel. At this time, the vicinity of the exit end of the fourth optical fiber and the vicinity of the entrance end of the fifth optical fiber are arranged in parallel, but such an arrangement improves accuracy more than the case of a single reflecting surface. Easy to plan.

  In addition, as in Patent Document 8, in a configuration in which the output end of the fourth optical fiber and the input end of the fifth optical fiber are arranged to face each other and the reference light is not reflected, the reference optical path length is changed. It is necessary to move the optical fiber itself. In this case, the bending method (curvature and the like) of the optical fiber disposed in the housing changes, which may disturb the polarization state of the reference light and degrade the image quality. Furthermore, in the configuration according to this embodiment, when the reference optical path length is changed by a predetermined distance, the corner cube may be moved by a distance that is half the predetermined distance. It is necessary to move by distance. When the moving distance becomes long in this way, there is a possibility that a deviation occurs in the facing relationship between the positions of the fiber ends.

  This embodiment solves various problems as described above. The same is true even if the number of reflections is three using a three-dimensional corner cube. A case where the number of reflections is four times or more (particularly an even number) will be described in the second embodiment.

<Second Embodiment>
In this embodiment, an optical image measurement device configured to reflect the reference light as many times as in the first embodiment is exemplified.

  The optical image measurement device (ophthalmic device) according to this embodiment has the same overall configuration as the ophthalmic device 1 of the first embodiment (see FIG. 1). The fundus camera unit is the same as that in the first embodiment (see FIG. 1). Hereinafter, the same components as those in the first embodiment will be described with the same reference numerals.

  A configuration example of the OCT unit 150 of the ophthalmologic apparatus of this embodiment is shown in FIG. 4, and a configuration example of the control system is shown in FIG.

  The fiber optical system in the OCT unit 150 of this embodiment is the same as that of the first embodiment. That is, the OCT unit 150 includes a low coherence light source 160, two fiber couplers 162 and 167, six optical fibers 161, 163 to 166 and 168, and a spectrometer 180.

  A feature of this embodiment is a reference optical path. The reference light LR guided by the optical fiber 163 is converted into a parallel light beam by the collimator 171 and the polarization state is converted by the quarter wavelength plate 190. When the reference light LR is circularly polarized light or elliptically polarized light, the quarter wavelength plate 190 converts it into linearly polarized light. When the reference light LR is linearly polarized light, the quarter wavelength plate 190 converts it into circularly polarized light or elliptically polarized light.

  In this embodiment, since the reference light LR passes through the quarter-wave plate 190 twice, the reference light LR incident on the optical fiber 164 is in the original polarization state. The quarter-wave plate 190 is rotated around the optical axis of the reference optical path by the wavelength plate rotating mechanism 300, and thereby the polarization correction of the reference light LR is performed.

  The reference light LR that has passed through the reference light LR once is reflected by the corner cube 191 twice (or three times or more: the same applies hereinafter), changes the traveling direction, and enters the beam splitter 192. The beam splitter 192 divides the reference light LR into two. As in the first embodiment, the corner cube 191 may be configured to be movable along the traveling direction of the reference light LR.

  On each optical path divided into two by the beam splitter 192, shutters 193 and 195 are provided. The shutters 193 and 195 block the reference light LR traveling through the optical path. The shutters 193 and 195 can be inserted / retracted with respect to the optical path by the optical path switching mechanism 320.

  When the shutter 193 is retracted from the optical path, the reference light LR (a part of the light beam) transmitted through the beam splitter 192 is reflected twice (or more than three times) by the corner cube 194 to change the traveling direction. Re-enters 192. The reference light LR transmitted again through the beam splitter 192 is reflected twice by the corner cube 191 to change the traveling direction, passes through the quarter-wave plate 190 and is converted into the original type of polarization state, and is collimated by the collimator 175. The focused light is incident on the incident end of the optical fiber 164.

  On the other hand, a density filter 196 is provided in the optical path on the shutter 195 side. The density filter 196 is a filter that attenuates the amount of transmitted light. The density filter 196 can be inserted / retracted with respect to the optical path by the filter moving mechanism 330.

  When the shutter 195 is retracted from the optical path, (a part of) the reference light LR reflected by the beam splitter 192 (transmits through the density filter 196 as necessary) twice (or 3 times) by the corner cube 197. The direction of travel is changed after being reflected, and enters the beam splitter 192 again. The reference light LR reflected again by the beam splitter 192 is reflected twice by the corner cube 191 to change the traveling direction, passes through the quarter-wave plate 190 and is converted into the original type of polarization state, and the collimator 175 As a result, the light beam is focused into the incident end of the optical fiber 164.

  The corner cubes 194 and 197 can be moved along the traveling direction of the reference light LR by the optical path length changing mechanism 310. The optical path length changing mechanism 310 operates under the control of the control unit 210, and the two corner cubes 194 and 197 can be moved independently of each other or can be moved in conjunction with each other.

  In an actual ophthalmic examination, for example, the reference light LR that has passed through the corner cube 194 is used for measurement of the fundus, and the reference light LR that has passed through the corner cube 197 is used for measurement of the anterior segment (cornea or the like). . When the optical path length is changed according to the working distance, the movement of the two corner cubes 194 and 197 can be linked. On the other hand, when the optical path length is changed according to the axial length of the eye to be examined, the two corner cubes 194 and 197 can be moved independently. In addition, when only the fundus is measured, when only the anterior eye segment is measured, or when both parts are simultaneously measured and only one of the depths is adjusted, the independent movement mode can be applied.

  The reference light LR incident on the optical fiber 164 is guided to the fiber coupler 167. On the other hand, the signal light LS generated by the fiber coupler 162 is irradiated to the eye E through the optical fiber 165 and the fundus camera unit 1A. Further, the signal light LS reflected by the fundus oculi Ef and the anterior segment of the eye E is guided to the fiber coupler 167 via the fundus camera unit 1A, the optical fiber 165, the fiber coupler 162, and the optical fiber 166.

  The fiber coupler 167 superimposes the reference light LR from the optical fiber 164 and the signal light LS from the optical fiber 166 to generate the interference light LC. The interference light LC is guided to the spectrometer 180 by the optical fiber 168. The spectrometer 180 converts the interference light LC emitted from the optical fiber 168 into a parallel light beam by the collimator lens 181, and spectrally decomposes the interference light LC by the diffraction grating 182. Each spectral component of the interference light LC is imaged on the imaging surface of the CCD 184 by the imaging lens 183. The CCD 184 detects each spectral component and generates a detection signal.

  The image forming unit 220 forms a tomographic image of the eye E based on the detection signal from the CCD 184. The image processing unit 230 forms a three-dimensional image based on the plurality of tomographic images.

  The operation and effect of this ophthalmic apparatus (optical image measurement apparatus) will be described. The ophthalmic apparatus includes a corner cube 191 and a beam splitter 192 that divides the reference light LR, and a corner cube 194 (first reflecting member) that reflects the divided reference light LR a plurality of times and guides it to the beam splitter 192. And a corner cube 197 (second reflecting member) that reflects the other reference light LR a plurality of times and guides it to the beam splitter 192.

  Further, the ophthalmologic apparatus generates and detects interference light LC by superimposing the reference light LR passed through the corner cube 194 and the fundus reflection light of the signal light LS, and based on the detection result (detection signal). An OCT image of the fundus oculi Ef (first depth) is formed.

  Further, the ophthalmologic apparatus generates and detects the interference light LC by superimposing the reference light LR that has passed through the corner cube 197 and the reflected light of the signal light LS at the anterior eye portion, and this detection result (detection signal) ) To form an OCT image of the anterior segment (second depth).

  Further, a ¼ wavelength plate 190 for correcting the polarization of the reference light LR is provided in the reference optical path of this ophthalmologic apparatus. It is also possible to provide the same dispersion adjustment means and polarization adjustment means as in the first embodiment.

  According to such an ophthalmologic apparatus, it is possible to prevent failure and performance degradation of the low-coherence light source 160 without using an isolator as in the first embodiment. Further, according to such an ophthalmologic apparatus, it is possible to optically improve image quality by performing dispersion compensation and polarization correction.

  The number of reflections of the reference light in this ophthalmic apparatus is 4 or 6 times (reciprocating) in the corner cube 191, 0 or 2 times in the beam splitter 192, and 2 times in each corner cube 194 or 197, for a total of 6 or 8 times. It is. These members correspond to “reflecting means” of the present invention.

  Various configurations described in the first embodiment can be applied to the ophthalmologic apparatus according to the second embodiment.

[Modification]
The configuration described above is merely an example for suitably carrying out the present invention. Therefore, arbitrary modifications within the scope of the present invention can be made as appropriate.

  For example, in the first embodiment, both the dispersion adjustment unit and the polarization adjustment unit are provided, but a configuration in which only one of them is provided may be employed. Further, the dispersion adjusting unit and the polarization adjusting unit are not limited to those described in the above embodiment, and can be replaced with an optical element having an arbitrary configuration having the same function.

  For example, as polarization adjusting means, a polarizing plate that converts the polarization state of the reference light into linearly polarized light, a quarter wavelength plate that converts the reference light converted into linearly polarized light into circularly polarized light, and a rotating means that rotates the polarizing plate Can be provided. Thereby, polarization correction can be performed by determining the rotational position of the polarizing plate while evaluating the image quality.

  In the second embodiment, an OCT image having two depths is formed by dividing the reference light into two, but an OCT image having three or more depths can be formed by dividing the reference light into three or more. It is also possible to form it. For this purpose, for example, two or more beam splitters may be provided, and a reflecting member (corner cube or the like), a shutter, or the like may be provided in each of the three or more reference optical paths after the division.

  In the above embodiment, the optical path length difference between the optical path of the signal light LS and the optical path of the reference light LR is changed by moving the corner cube, but the method of changing the optical path length difference is limited to this. is not. For example, the optical path length difference can be changed by moving the fundus camera unit or the OCT unit relative to the eye to be examined to change the optical path length of the signal light. In particular, when the measured object is not a living body part, the optical path length difference can be changed by moving the measured object in the depth direction (z direction).

  The configuration according to the present invention can also be applied to an optical image measurement device used in fields other than ophthalmology. For example, the configuration according to the present invention can be applied to an optical image measurement device used in other medical fields (dermatology, dentistry, etc.), biology field, industrial field, and the like.

  The computer program in the above embodiment can be stored in any recording medium that can be read by the drive device of the computer. As this recording medium, for example, an optical disk, a magneto-optical disk (CD-ROM / DVD-RAM / DVD-ROM / MO, etc.), a magnetic storage medium (hard disk / floppy (registered trademark) disk / ZIP, etc.), etc. are used. Is possible. It can also be stored in a storage device such as a hard disk drive or memory. Furthermore, this program can be transmitted and received through a network such as the Internet or a LAN.

DESCRIPTION OF SYMBOLS 1 Ophthalmic apparatus 1A Fundus camera unit 141 Scan unit 150 OCT unit 160 Low coherence light source 161,163,164,165,166,168 Optical fiber 162,167 Fiber coupler 173,191,194,197 Corner cube 172 Dispersion compensation member 174 Polarization Correction member 180 Spectrometer 182 Diffraction grating 184 CCD
190 1/4 wavelength plate 192 Beam splitter 193, 195 Shutter 196 Density filter 200 Arithmetic control device 210 Control unit 220 Image forming unit 230 Image processing unit 240 Display unit 250 Operation unit 260, 310 Optical path length changing mechanism 270 Dispersion compensation driving mechanism 280 Polarization correction driving mechanism 300 Wave plate rotating mechanism 320 Optical path switching mechanism 330 Filter moving mechanism

Claims (7)

A light source that outputs low coherence light;
The output low-coherence light is divided into signal light and reference light, and interference light is generated by superimposing the signal light passing through the object to be measured and the reference light passing through the reference light path via the signal light path. An optical system for detecting the generated interference light and generating a detection signal;
Image forming means for forming an image of the object to be measured based on the generated detection signal;
An optical image measuring device having
The optical system is
A first optical fiber that guides the low-coherence light output from the light source; a first fiber coupler that divides the guided low-coherence light into signal light and reference light; and a second fiber coupler. And including
One end of the signal light path is connected to the first fiber coupler, guides the signal light toward the object to be measured, and guides the signal light passing through the object to be measured to the first fiber coupler. A second optical fiber that emits light, and a third optical fiber that guides the signal light guided to the first fiber coupler by the second optical fiber to the second fiber coupler,
As the reference optical path, one end is connected to the first fiber coupler, and the fourth optical fiber that guides the reference light and the reference light emitted from the other end of the fourth optical fiber are reflected a plurality of times. Reflecting means, a fifth optical fiber for guiding the reference light passing through the reflecting means to the second fiber coupler, and an optical path between the fourth optical fiber and the fifth optical fiber. A dispersion adjusting means for adjusting a dispersion characteristic of the reference light and / or a polarization adjusting means for adjusting a polarization state of the reference light,
The second fiber coupler generates interference light by superimposing the signal light guided by the third optical fiber and the reference light guided by the fifth optical fiber;
An optical image measuring device characterized by that. The reflecting means reflects the reference light an even number of times;
The optical image measuring device according to claim 1. The reflecting means includes a beam splitter that divides the reference light, a first reflecting member that reflects the divided reference light a plurality of times and guides it to the beam splitter, and reflects the other reference light a plurality of times. A second reflecting member that leads to the beam splitter,
The first reflecting member and the second reflecting member are disposed with respect to the beam splitter so that an optical path length of the one reference light and an optical path length of the other reference light are different from each other.
The fifth optical fiber guides the one reference light passing through the first reflecting member and / or the other reference light passing through the second reflecting member to the second fiber coupler. ,
The image forming means forms a first depth image of the object to be measured based on a detection signal of interference light between the one reference light and the signal light, and the other reference light and the signal light A second depth image of the object to be measured is formed based on the detection signal of the interference light of
The optical image measurement device according to claim 1, wherein the optical image measurement device is an optical image measurement device. The optical system includes changing means for changing the optical path length of the reference optical path by moving the reflecting means,
The optical image measurement device according to any one of claims 1 to 3, wherein The dispersion adjusting unit includes a pair of prisms and a moving unit that relatively moves the pair of prisms.
The optical image measuring device according to any one of claims 1 to 4, wherein The polarization adjusting means is arranged between two quarter-wave plates that convert circularly polarized light or elliptically polarized light into linearly polarized light, or linearly polarized light into circularly polarized light or elliptically polarized light, respectively, and the two quarter-wave plates, A half-wave plate for changing the direction of the polarization plane of the reference light, and a rotating means for rotating the half-wave plate,
The optical image measuring device according to any one of claims 1 to 4, wherein The polarization adjusting unit rotates a polarizing plate that converts a polarization state of the reference light into linearly polarized light, a quarter-wave plate that converts the reference light converted into linearly polarized light into circularly polarized light, and the polarizing plate. Including rotating means,
The optical image measuring device according to any one of claims 1 to 4, wherein

Images