JP2007178409A - Apparatus for measuring optical image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for measuring an optical image resistant against an environment such as a temperature change and vibration. <P>SOLUTION: A photocoupler 4 divides a low-coherent light LO of a linear polarization into a signal light SL of linear polarization and a reference light LR having a polarization axis direction same thereto. The signal light SL is guided to an examined eye E while keeping the polarization axis direction by a PM fiber 6, and is returned to the photocoupler 4 through the PM fiber 6, after passing an eye ground Er. The reference light LR is guided to a reference mirror 14 while keeping the polarization axis direction by a PM fiber 5, and is returned to the photocoupler 4 through the PM fiber 5, after reflected by the reference mirror 14. The signal light SL and the reference light LR returned to the photocoupler 4 are superposed each other to generate an interference light LC. The interference light LC is detected by a spectrometer 30, and a computer 40 forms an image of the examined eye E, based on a detection signal therein. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, in particular, the object to be measured of the light scattering medium is irradiated with a light beam, the reflected light or transmitted light is used to measure the surface form and internal form of the object to be measured, and the image is formed. The present invention relates to an optical image measurement device.

  2. Description of the Related Art In recent years, an optical image measurement technique that forms an image representing a surface form or an internal form of an object to be measured using a light beam output from a laser light source or the like has attracted attention. Since this optical image measurement technique does not have invasiveness to the human body like conventional X-ray CT, it is expected to be applied particularly in the medical field.

  In Patent Document 1, a measurement arm scans an object with, for example, a rotary turning mirror (galvanomirror), and a reference mirror is installed on the reference arm. An interferometer is used in which the intensity of light that appears due to interference is also analyzed by a spectroscope, and the reference arm is equipped with a device that changes the phase of the reference light beam stepwise with a discontinuous value. Is disclosed.

  This apparatus uses a so-called "Fourier Domain OCT (Fourier Domain Optical Coherence Tomography)" technique based on Patent Document 2. That is, the object to be measured is irradiated with a light beam, the spectral intensity distribution of the reflected light is acquired, and Fourier transform is performed on the object to image the form of the object to be measured in the depth direction (z direction). It is.

  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. In this apparatus, since the light beam is scanned only in one direction (x direction) orthogonal to the z direction, the formed image is along the scanning direction (x direction) of the light beam. It becomes a two-dimensional cross-sectional image in the depth direction (z direction).

  Patent Document 3 discloses an optical image measurement device configured to guide a light beam from a light source, signal light, reference light, and interference light through optical fibers. One end of each of these four optical fibers is connected to an optical coupler (splitter / combiner), thereby generating interference light.

JP 11-325849 A German Patent Application Publication No. DE43009056A1 JP-T-2001-527659

  However, when a normal optical fiber (single mode fiber or multimode fiber) is used for the light guide as in Patent Document 3, the following problems have been pointed out. First, the optical propagation performance of optical fibers (especially the polarization state of light) is sensitive to environmental conditions such as temperature and vibration, and the ambient environmental conditions when transporting or installing the device. It was difficult to handle the apparatus. For example, in order to suitably generate interference light, the polarization axis directions of the signal light and the reference light need to match, but if the polarization state of the light changes due to the influence of environmental conditions, the polarization axes of each other The directions do not match and interference light cannot be obtained.

  Second, if a single-mode fiber or multi-mode fiber is used as the light guide, the polarization state of the light propagating in the fiber is disturbed, so the polarization state must be adjusted using a polarization controller. was there. As a result, complication of the configuration of the apparatus and increase in cost have been problems.

  The present invention has been made to solve such problems, and generates interference light even when exposed to an environment such as temperature change and vibration that may affect the polarization characteristics of signal light and reference light. An object of the present invention is to provide an optical image measurement device capable of performing the above.

  Another object of the present invention is to provide an optical image measurement device capable of simplifying the device configuration and reducing the cost.

  In order to achieve the above object, the invention described in claim 1 is directed to a light output means for outputting linearly polarized low-coherence light, and the output low-coherence light having the same polarization axis direction as that of the low-coherence light. Splitting means for splitting each of the linearly polarized signal light and the reference light, respectively, and guiding the linearly polarized signal light obtained by the splitting toward the object to be measured while maintaining the polarization axis direction. A first light guiding unit configured to guide the signal light passing through the measurement object while maintaining a polarization axis direction; and linearly polarized reference light obtained by the division is directed to the reference object while maintaining the polarization axis direction. A second light guiding means for guiding the reference light passing through the reference object while maintaining a polarization axis direction, and the object to be measured guided by the first light guiding means. And the signal light via Superimposing means for generating interference light by superimposing the reference light guided by the light guiding means via the reference object, and detecting means for receiving the generated interference light and outputting a detection signal; And an image forming means for forming an image of the object to be measured based on the output detection signal.

The invention according to claim 2 is the optical image measurement device according to claim 1, wherein the first light guide means is arranged in a polarization axis direction of the linearly polarized signal light obtained by the division. a polarization-maintaining fiber disposed so that the fast axis or the slow axis coincides,
It is characterized by that.

  The invention according to claim 3 is the optical image measurement device according to claim 1 or 2, wherein the second light guide means is configured to transmit the linearly polarized reference light obtained by the division. The polarization plane holding fiber is arranged so that the fast axis or the slow axis coincides with the polarization axis direction.

  The invention according to claim 4 is the optical image measurement device according to any one of claims 1 to 3, wherein the linearly polarized low-coherence light output by the light output means is polarized. It is further characterized by further comprising third light guiding means for guiding light toward the dividing means while maintaining the axial direction.

  Further, the invention according to claim 5 is the optical image measurement device according to claim 4, wherein the third light guide means is a polarization of linearly polarized low-coherence light output from the light output means. The polarization-maintaining fiber is disposed so that the fast axis or the slow axis coincides with the axial direction.

  The invention according to claim 6 is the optical image measurement device according to claim 1, wherein the first light guide means is arranged in a polarization axis direction of the linearly polarized signal light obtained by the division. a polarization-maintaining fiber disposed so that one of the fast axis and the slow axis coincides, and the second light guide means has a polarization axis direction of the linearly polarized reference light obtained by the division. The polarization-maintaining fiber is disposed so that the one axis coincides with the other.

  The invention according to claim 7 is the optical image measurement device according to claim 6, wherein the one axis coincides with the polarization axis direction of the linearly polarized low-coherence light output by the light output means. And a polarization plane holding fiber that guides the output low-coherence light toward the splitting means.

  The invention according to claim 8 is the optical image measurement device according to any one of claims 1 to 7, wherein the interference light generated by the superimposing means is directed toward the detecting means. A fourth light guide means for guiding light is further provided.

  The invention according to claim 9 is the optical image measurement device according to claim 8, wherein the fourth light guide means guides the generated interference light while maintaining a polarization axis direction. It is characterized by.

  The invention according to claim 10 is the optical image measurement device according to any one of claims 1 to 9, wherein the object to be measured and signal light passing through the object to be measured are present. A polarization axis direction when the signal light is guided toward the object to be measured by the first light guide unit on an optical path between the incident end that is incident on the first light guide unit; A linear polarizer that transmits a polarization component in the same direction is provided.

  The invention according to claim 11 is the optical image measurement device according to any one of claims 1 to 10, wherein the first light guide means passes through the object to be measured. The signal light that has passed through the object to be measured is incident on the exit end from which the previous signal light is emitted, and a quarter wavelength is on the optical path between the object to be measured and the exit end. A board is provided.

  The invention according to claim 12 is the optical image measurement device according to any one of claims 1 to 11, wherein the light output means includes a light source that outputs low-coherence light, And a polarization characteristic converting means for converting the polarization characteristic of the output low coherence light into linearly polarized light.

  The invention according to claim 13 is the optical image measurement device according to claim 12, wherein the polarization characteristic conversion means converts the low-coherence light output from the light source into linearly polarized light. Means, a second polarization means for rotating the polarization axis direction of the low-coherence light converted into the linearly polarized light by 45 degrees, and a third polarization means for transmitting only the polarization component in the polarization axis direction of the low-coherence light rotated by 45 degrees. And a Faraday isolator having a polarizing means.

  The optical image measurement device according to the present invention divides linearly polarized low-coherence light output by the light output means into linearly polarized signal light and reference light having the same polarization axis direction as the first and second light beams. The light guide means guides the signal light and the reference light while maintaining the polarization axis direction, and superimposes the signal light passing through the object to be measured and the reference light passing through the reference object. As a result, the signal light and the reference light whose polarization axis directions coincide with each other can be superimposed, so that the signal light and the reference light interfere with each other to generate interference light. The interference light is detected by the detection means, and an image of the object to be measured is formed based on the detection signal.

  Thus, according to the present invention, the first and second light guides guide the signal light and the reference light while maintaining the polarization axis direction even when exposed to an environment such as temperature change and vibration. Therefore, it is possible to obtain interference light. Therefore, it is possible to provide an optical image measurement device that is resistant to environments such as temperature changes and vibrations.

  Further, by using such first and second light guiding means, it is not necessary to mount a polarization controller for controlling the polarization characteristics of the signal light and the reference light. Reduction can be achieved.

  In addition, according to the present invention, a linear polarizer is provided on the optical path between the signal light passing through the object to be measured and the incident end where the light is incident on the first light guide, and the signal light is transmitted to the object to be measured. A linear polarizer that transmits a polarization component in the direction of the polarization axis when guided toward the surface is provided. As a result, even if the polarization characteristic of the signal light changes to elliptical polarization or circular polarization when passing through the object to be measured, it can be returned to linearly polarized light in the same polarization axis direction as before passing through the object to be measured. The interference light can be generated from the signal light and the reference light.

  In addition, according to the present invention, the signal light that has passed through the measured object is incident on the emission end of the first light guide unit from which the signal light before passing through the measured object is emitted, and the measured object. And a quarter-wave plate is provided on the optical path between this and the emission end. As a result, even if the polarization direction of the signal light changes when passing through the measured object, it can be returned to the same polarization direction as before passing through the measured object. Can be generated.

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

[Device configuration]
First, the configuration of the optical image measurement device according to the present embodiment will be described with reference to FIGS. FIG. 1 illustrates an example of the overall configuration of the optical image measurement device according to the present embodiment. FIG. 2 shows an example of the configuration of the control system of this optical image measurement device. FIG. 3 shows an example of the hardware configuration of the computer of this optical image measurement device. FIG. 4 shows an example of the configuration of the light source device of the optical image measurement device. FIG. 5 shows an example of the configuration of an optical fiber (PM fiber) used in this optical image measurement device.

  The optical image measurement device 1 according to the present embodiment divides the low-coherence light output from the light source into reference light and signal light, and passes through the reference light and the measured object via the reference object, as in the conventional case. An interferometer that generates interference light by superimposing the signal light is provided, and the detection result of the generated interference light is analyzed to form an image of the object to be measured.

[Low coherence light source device]
As shown in FIG. 4, the low coherence light source device 2 includes a low coherence light source 2a, a collimator lens 2b, a Faraday isolator 2c, a condensing lens 2g, and a fiber end holding portion 2h. The fiber end holding part 2h holds one end of the PM fiber 3 (described later).

  The low coherence light source 2a outputs a low-coherence light L0 having a wide band, and is composed of a wide-band light source such as a super luminescent diode (SLD) or a light emitting diode (LED). The low coherence light L0 output from the low coherence light source 2a has a wavelength in the near infrared region, for example, and a temporal coherence length of about several tens of micrometers.

  The Faraday isolator 2c is an optical system that propagates light only in one direction by utilizing rotation in the polarization axis direction by a magnetic field (Faraday effect), and includes a polarizer (incident polarizer) 2d, a Faraday rotator ( Faraday rotator) 2e and analyzer (outgoing polarizer) 2f.

  The polarizer 2d is an optical element (polarizing plate) that transmits only a polarized light component in a specific direction. The Faraday rotator 2e includes, for example, a crystal having a magneto-optical effect such as a YIG (yttrium, iron, garnet) crystal, and means for applying a magnetic field to the crystal. The light passing through the crystal is rotated by 45 degrees in the direction of the polarization axis in a predetermined direction due to the Faraday effect. The analyzer 2f is an optical element (polarizing plate) that transmits only the polarization component in the polarization axis direction of the light transmitted through the Faraday rotator 2e.

  The low coherence light L0 output from the low coherence light source 2a is collimated by the collimator lens 2b and enters the Faraday isolator 2c. The low coherence light L0 is converted into linearly polarized light in a specific polarization axis direction by the polarizer 2d, and the polarization axis direction is rotated 45 degrees by the Faraday rotator 2e. The low coherence light L0 that has passed through the Faraday rotator 2e passes through the analyzer 2f as it is. The low coherence light L0 transmitted through the analyzer 2f is linearly polarized light in the same direction as the polarization direction of the analyzer 2f. The low coherence light L0 is condensed by the condenser lens 2g and enters one end of the core of the PM fiber 3.

  Note that light (return light) that returns to the low-coherence light source device 2 through the PM fiber 3 is blocked by the action of the Faraday isolator 2c and does not reach the low-coherence light source 2a. That is, the return light is converted into linearly polarized light in a certain direction by the analyzer 2f, and then rotated by 45 degrees in the same direction as the low-coherence light L0 by the Faraday rotator 2e, and is polarized orthogonally to the direction transmitting the polarizer 2d. The light has an axial direction. Therefore, the return light is blocked by the polarizer 2d. Thereby, the low coherence light source 2a is not adversely affected by the return light.

  Such a Faraday isolator 2c corresponds to an example of the “polarization characteristic converting means” of the present invention. Further, the polarizer 2d, the Faraday rotator 2e, and the analyzer (outgoing polarizer) 2f correspond to examples of “first polarizing means”, “second polarizing means”, and “third polarizing means”, respectively. .

[About PM fiber]
The low coherence light L0 output from the low coherence light source device 2 is guided to the optical coupler 4 through the PM fiber 3. Here, the PM fiber will be described. A PM fiber (Polarization maintaining fiber) is a kind of optical fiber called a polarization-maintaining fiber. This PM fiber has the characteristic of propagating light having linearly polarized light while maintaining its polarization axis direction.

An example of the configuration of the PM fiber 3 is shown in FIG. The PM fiber 3 shown in the figure has a core 3a serving as a light guide and a clad 3b formed around the core 3a as in the case of a normal single mode fiber or multimode fiber. The core 3a is made of, for example, GeO ₂ -added quartz, and the cladding 3b is made of, for example, pure quartz.

A feature of the PM fiber 3 is that a pair of stress applying portions 3c and 3d are provided so as to sandwich the core 3a. The stress applying portions 3c and 3d are made of, for example, B ₂ O ₃ added quartz. An arrangement direction of the core 3a and the stress applying portions 3c and 3d is defined as an X-axis direction, and a direction orthogonal thereto is defined as a Y-axis direction.

  Each of the stress applying portions 3c and 3d applies a stress in the direction toward the core 3a (X-axis direction). Thereby, the core 3a has a structure in which the refractive index is different between the X-axis direction and the Y-axis direction, that is, a structure having a birefringence. At this time, the X-axis direction is the direction of the axis (slow axis) in which the phase of the light propagating in the core 3a is delayed, and the Y-axis direction is the direction of the axis (fast axis) in which the phase advances.

  When linearly polarized light is incident on the core 3a of the PM fiber 3 as described above, the light is maintained in the polarization axis direction by making the polarization axis direction of the light coincide with the slow axis direction or the fast axis direction. It propagates in the core 3a in the state. That is, when the polarization axis direction is made incident on the core 3a with the slow axis (fast axis) aligned, the light propagates through the core 3a while keeping the polarization axis direction in the slow axis direction (fast axis direction).

  In the following, it is assumed that the PM fiber 3 is arranged so that the slow axis coincides with the polarization axis direction of the low coherence light L0 (the same applies to the case where the fast axis coincides).

  Note that the other PM fibers 5, 6, and 7 constituting the optical image measurement device 1 are also constituted by the same PM fibers as the PM fibers 3. The PM fiber 3 corresponds to an example of the “third light guide unit” of the present invention, the PM fiber 5 corresponds to an example of the “second light guide unit”, and the PM fiber 6 corresponds to the “first guide unit”. The PM fiber 7 corresponds to an example of a “fourth light guide unit”. Here, the optical fiber that guides the interference light LC may be an optical fiber other than the PM fiber (for example, a single mode fiber). It is also possible to configure an optical image measurement device that does not have the third and fourth light guiding means (see the following modification).

  The low coherence light L0 output from the low coherence light source device 2 is guided to the optical coupler 4 while maintaining the polarization axis direction by the PM fiber 3, and is divided into the reference light LR and the signal light LS. For example, the optical coupler 4 converts 80% of the light amount of the low-coherence light L0 into the reference light LR and 20% into the signal light LS. The reference light LR and the signal light LS are each light having linearly polarized light in the same polarization axis direction as that of the optical coherence light L0.

  The optical coupler 4 has both functions of a splitting unit (splitter) for splitting light and a superimposing unit (coupler) for superimposing light. Here, it is conventionally referred to as an “optical coupler”. To.

  The PM fiber 5 that guides the reference light LR is arranged so that the slow axis coincides with the polarization axis direction of the reference light LR. The reference light LR is guided by the PM fiber 5 while maintaining the polarization axis direction, and is emitted from the fiber end. The emitted reference light LR is collimated by the collimator lens 11 and then reflected by the reference mirror 14 (reference object) via the glass block 12 and the density filter 13.

  The reference light LR reflected by the reference mirror 14 passes through the density filter 13 and the glass block 12 again, and is condensed on the fiber end of the PM fiber 5 by the collimator lens 11. The condensed reference light LR has the same polarization axis direction as that emitted from the end of the fiber, and is guided to the optical coupler 4 by the PM fiber 5 while maintaining the polarization axis direction.

  The glass block 12 and the density filter 13 serve as delay means for matching the optical path lengths (optical distances) of the reference light LR and the signal light LS, and as means for matching the dispersion characteristics of the reference light LR and the signal light LS. It works.

  On the other hand, the PM fiber 6 that guides the signal light LS is disposed so that the slow axis coincides with the polarization axis direction of the signal light LS. The signal light LS is guided by the PM fiber 6 while maintaining the polarization axis direction, and emitted from the end of the fiber. The emitted signal light LS is converted into a parallel light beam by the collimator lens 21, passes through the linear polarizer 27 and the quarter wavelength plate 28, and is guided to the galvanometer mirrors 22 and 23.

  The linear polarizer 27 transmits the polarization component in the same direction as the polarization axis direction of the signal light LS, and makes the polarization characteristic linearly polarized light. The quarter-wave plate 28 converts the polarization characteristic of the signal light LS from linearly polarized light to circularly polarized light, and further changes the polarization characteristic of the signal light LS reflected by the fundus Er to return from circularly polarized light to linearly polarized light. Convert. That is, since the signal light LS passes through the wave plate 28 twice, the polarization axis is rotated by a half wavelength (π = 180 degrees) in total. The linear polarizer 27 and the quarter wavelength plate 28 are for correcting the influence of the eye E on the polarization characteristics of the signal light LS (described later).

  The galvanometer mirrors 22 and 23 are rotated around the rotation shafts 22a and 23a, respectively. The rotation shafts 22a and 23a are arranged so as to be orthogonal to each other. The rotation shaft 22a of the galvanometer mirror 22 is disposed in parallel with the paper surface of FIG. 1 and at a predetermined angle (for example, 45 degrees) with respect to the traveling direction of the signal light LS. Further, the rotation shaft 23a of the galvanometer mirror 23 is arranged perpendicular to the paper surface of FIG. That is, the galvano mirror 23 can be rotated in the direction indicated by the double-sided arrow in FIG. 1, and the galvano mirror 22 can be rotated in the direction orthogonal to the double-sided arrow. By the two galvanometer mirrors 22 and 23, the reflection direction of the signal light LS is changed to two directions orthogonal to each other.

  The signal light LS reflected by the galvanometer mirror 23 is reflected by the dichroic mirror 25 while being condensed by the lens 24, temporarily forms an image, and enters the eye E through the objective lens 26. The signal light LS incident on the eye E is collected on the fundus (retina) Er.

  At this time, the signal light LS reaches not only the surface of the fundus oculi Er but also the deep region of the fundus oculi Er and is scattered at the refractive index boundary. Thereby, the fundus reflection light of the signal light LS becomes light including information indicating the surface form of the fundus Er and information indicating the backscattering state at the refractive index boundary of the deep tissue.

  The dichroic mirror 25 acts to reflect light in the (near) infrared region and transmit light in the visible region.

  The signal light LS reflected by the fundus Er passes through the objective lens 26, the dichroic mirror 25, the lens 24, and the galvanometer mirrors 22 and 23. The signal light LS is converted from the quarter-wave plate 28 into linearly polarized light having a polarization axis in the direction of the slow axis of the PM fiber 6 and passes through the linear polarizer 27 as it is. The signal light LS transmitted through the linear polarizer 27 is condensed on the fiber end of the PM fiber 6 by the collimator lens 21. The collected signal light LS is guided to the optical coupler 4 by the PM fiber 6 while maintaining the polarization axis direction.

  The optical coupler 4 superimposes the reference light LR reflected and returned from the reference mirror 14 and the signal light LS reflected and returned from the fundus Er of the eye E to be examined. Each of the reference light LR and the signal light LS has a polarization axis in the same direction as when it is divided from the low-coherence light L0. Therefore, the reference light LR and the signal light LS preferably interfere with each other to generate the interference light LC. The generated interference light LC has linearly polarized light, and is guided to the spectrometer 30 by the PM fiber 7 while maintaining the polarization axis direction.

  The spectrometer 30 includes a collimator lens 31, a diffraction grating 32, an imaging lens 33, and a CCD (Charge Coupled Device) 34. The diffraction grating 32 is a transmission diffraction grating, but of course, a reflection diffraction grating can also be used. Further, in place of the CCD 34, any image sensor (detection means) such as a CMOS (Complementary Metal Oxide Semiconductor) can be used.

  The interference light LC that has entered the spectrometer 30 is converted into a parallel light beam by the collimator lens 31 and then split (spectral decomposition) by the diffraction grating 32. The split interference light LC is imaged on the imaging surface of the CCD 34 by the imaging lens 33. The CCD 34 receives the interference light LC, converts it into an electrical detection signal, and outputs it to the computer 40.

  The computer 40 analyzes the detection signal input from the CCD 34 and forms a tomographic image of the fundus oculi Er of the eye E to be examined. The analysis method at this time is the same as the conventional Fourier domain OCT method.

  The computer 40 controls each part of the optical image measurement device 1. For example, the control of the rotation operation of the galvanometer mirrors 22 and 23, the operation control of the alignment mechanism (not shown) of the optical image measuring device 1 with respect to the eye E, the output control of the low coherence light by the low coherence light source device 2, etc. I do.

  The observation apparatus (imaging apparatus) 50 is an arbitrary observation apparatus and / or imaging apparatus used in the ophthalmic field, such as a slit lamp (slit lamp microscope) or a fundus camera. The observation device 50 may be provided integrally with the optical image measurement device 1 or may be provided separately. The examiner performs manual alignment of the optical image measurement device 1 with respect to the eye E while observing the eye E using the observation device 50, confirms the state of the fundus Er at the time of measurement, You can shoot.

[Scanning signal light]
As described above, the reflection direction of the signal light LS is changed by the galvanometer mirrors 22 and 23. By changing the directions of the reflecting surfaces of the galvanometer mirrors 22 and 23, the signal light LS can be irradiated to various positions on the fundus Er. That is, the signal light LS can be scanned on the fundus Er.

  A signal light LS indicated by a broken line and a signal light LS ′ indicated by a dotted line in FIG. 1 represent the signal light traveling in two different optical paths corresponding to the change in the direction of the galvano mirror 23. The signal light LS is superimposed on the reference light LR by the optical coupler 4 to generate the interference light LC. Similarly, the signal light LS ′ is superimposed on the reference light LR to generate the interference light LC ′.

  The signal light LS ′ indicated by the dotted line represents the signal light when the orientation of the galvanometer mirror 23 in the description of the above [apparatus configuration] is changed by a certain angle in the downward direction (−y direction) in FIG. Yes. Compared with the case where the signal light LS before the change in direction is condensed at the substantially central position of the fundus Er, the signal light LS ′ after the change in direction is separated upward (+ y direction) from the center position of the fundus Er. It is condensed at the position. In this case, the signal light LS reflected by the fundus Er becomes light including information (surface and deep information) at a substantially central position of the fundus Er, whereas the reflected light of the signal light LS ′ The light includes information on the position away from the + y direction (information on the surface and the deep part).

  Therefore, by rotating the galvanometer mirror 23 in the + y direction in FIG. 1 (that is, changing the direction of the reflecting surface so as to reduce the incident angle of the signal light), the condensing position of the signal light on the fundus Er is −y. Can be moved in the direction. Conversely, by rotating the galvanometer mirror 23 in the −y direction (that is, changing the direction of the reflecting surface so as to increase the incident angle of the signal light), the condensing position of the signal light on the fundus Er is in the + y direction. Can be moved.

  Similarly, by rotating the galvanometer mirror 22 toward the front side (+ x direction) of FIG. 1, the condensing position of the signal light on the fundus Er can be moved to the back side (−x direction) of the paper surface. By rotating the galvanometer mirror 22 in the −x direction, the condensing position of the signal light on the fundus Er can be moved in the + x direction.

  In addition, by rotating both the galvanometer mirrors 22 and 23 simultaneously, the condensing position of the signal light can be moved in a direction in which the x direction and the y direction are combined. That is, the signal light can be scanned in an arbitrary direction on the xy plane by controlling the two galvanometer mirrors 22 and 23, respectively.

[Control system configuration]
Next, the control system of the optical image measurement device 1 will be described. The block diagrams shown in FIG. 2 and FIG. 3 each show an example of the configuration of the control system of the optical image measurement device 1. FIG. 2 shows a functional configuration of the control system of the optical image measurement device 1. FIG. 3 shows a hardware configuration of the computer 40.

[Computer hardware configuration]
First, the hardware configuration of the computer 40 will be described with reference to FIG. The computer 40 has the same hardware configuration as a conventional computer. Specifically, it includes a CPU 100 (such as a microprocessor), RAM 101, ROM 102, hard disk drive (HDD) 103, keyboard 104, mouse 105, display 106, communication interface (I / F) 107, and the like. These units are connected via a bus 108.

  The CPU 100 executes an operation characteristic of the present invention by expanding the control program 103 a stored in the hard disk drive 103 on the RAM 101. Further, the CPU 100 executes control of each part of the apparatus, various arithmetic processes, and the like. For example, in addition to the control of the low-coherence light source device 2 and the galvanometer mirrors 22 and 23 described above, the control of each part of the device corresponding to the operation signal from the keyboard 104 and the mouse 105, the control of the display process by the display 106, the data by the communication interface 107 And control of transmission / reception processing of control signals and the like.

  The keyboard 104, the mouse 105, and the display 106 are used as a user interface of the optical image measurement device 1. The keyboard 104 is used as a device for inputting characters and numbers. The mouse 105 is used as a device for performing various input operations on the display screen of the display 106.

  The display 106 is an arbitrary display device such as an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube), and an image of the eye E formed by the optical image measurement device 1 and various operation screens and settings. Display the screen. In addition, the display 106 may be arrange | positioned so that it may be fitted on the housing | casing outer surface of the optical image measuring device 1, and may be arrange | positioned as a monitor apparatus with which a normal computer is equipped.

  The user interface of the optical image measurement device 1 is not limited to such a configuration, and various information such as a trackball, a joystick, a touch panel type liquid crystal display or a pen tablet, and a control panel for ophthalmic examination can be obtained. It can be configured by arbitrary user interface means having a function of displaying and outputting and a function of inputting various kinds of information.

  The communication interface 107 performs a process of transmitting a control signal from the CPU 100 to each part of the apparatus such as the low coherence light source device 2 and the galvanometer mirror 22 and a process of receiving a detection signal from the CCD 34. Further, when the computer 40 is connected to a network such as a LAN (Local Area Network) or the Internet, the communication interface 107 is provided with a network adapter such as a LAN card and a communication device such as a modem, and is connected via the network. It is possible to configure to perform data communication.

[Functional configuration]
Next, the configuration of the control system of the optical image measurement device 1 having the above hardware configuration will be described with reference to FIG.

  The optical image measurement device 1 is provided with a mirror drive mechanism 22A that rotationally drives the galvanometer mirror 22, and a mirror drive mechanism 23A that rotationally drives the galvanometer mirror 23. Each of the mirror drive mechanisms 22A and 23A has the same configuration as the conventional one, and includes a drive device such as a stepping motor and a power transmission mechanism that transmits the power generated by the drive device to the galvanometer mirrors 22 and 23. Yes.

  The computer 40 includes a control unit 41, an image processing unit 42, and a user interface (UI) 43 based on the hardware configuration shown in FIG. The image processing unit 42 corresponds to an example of the “image forming unit” of the present invention.

  The control unit 41 and the image processing unit 42 each include a CPU 100 and a RAM 101 that execute the control program 103a. The control unit 41 includes a storage device such as the ROM 102 and the HDD 103. The user interface 43 includes a keyboard 104, a mouse 105, and a display 106.

  The control unit 41 transmits a control signal to each of the low coherence light source device 2 and the mirror driving mechanisms 22A and 23A. Based on the control signal from the control unit 41, the low coherence light source device 2 performs switching of output start / stop of the low coherence light L0, adjustment of output intensity (output light amount), and the like. Further, the mirror drive mechanism 22A (mirror drive mechanism 23A) drives the galvano mirror 22 (galvano mirror 23) based on a control signal from the control unit 41, and rotates it by an angle required by the control signal.

  Further, the control unit 41 receives a detection signal from the CCD 34 and provides it to the image processing unit 42. Furthermore, the control unit 41 controls the operation of each unit of the apparatus based on the operation signal from the user interface 43 and the display processing of images and screens.

  The image processing unit 42 performs processing for forming an image (tomographic image) of the fundus oculi Er of the eye E based on the detection signal of the CCD 34 provided from the control unit 41. Hereinafter, an example of specific modes of detection signal acquisition processing of the CCD 34 and processing of the image processing unit 42 will be specifically described.

[Detection signal acquisition processing]
The detection signal from the CCD 34 is generated corresponding to the scanning of the signal light LS. The control unit 41 controls the galvanometer mirrors 22 and 23 to sequentially move the scanning point of the signal light LS on the fundus Er (the incident target position (condensing target position) of the signal light LS on the fundus Er). At the same time, the low-coherence light source device 2 is controlled to continuously switch the output / stop of the low-coherence light L0 at a predetermined timing (synchronized with the movement of the scanning point). Thereby, the signal light LS is sequentially collected at a plurality of scanning points on the fundus Er.

  An example of the scanning mode of the signal light LS is shown in FIG. FIG. 6A illustrates an example of a scanning mode of the signal light LS when the fundus Er is viewed from the incident side (−z direction) of the signal light LS. FIG. 6B shows an example of an arrangement mode of scanning points on each scanning line.

  As shown in FIG. 6A, the signal light LS is scanned in a rectangular scanning region R set in advance. In the scanning region R, a plurality (m) of scanning lines R1 to Rm extending in the −x direction are set. When the signal light LS is scanned along each scanning line Ri (i = 1 to m), a detection signal of the interference light LC is generated (described later).

  Here, the direction of each scanning line Ri is referred to as a “main scanning direction”, and a direction orthogonal to the direction is referred to as a “sub-scanning direction”. Accordingly, the signal light LS is scanned in the main scanning direction by the galvano mirror 22, and the scanning in the sub scanning direction is performed by the galvano mirror 23.

  On each scanning line Ri, as shown in FIG. 6B, a plurality (n) of scanning points Ri1 to Rin are set in advance.

  First, the control unit 41 controls the galvanometer mirrors 22 and 23 to set the incident target of the signal light LS to the scanning start position RS (scanning point R11) on the first scanning line R1. Then, the low-coherence light source device 2 is controlled to flash the low-coherence light L0, and the signal light LS is incident on the scanning start position RS. The CCD 34 receives the interference light LC based on the reflected light and outputs a detection signal to the control unit 41.

  Next, the control unit 41 controls the galvanometer mirror 22 to set the incident target of the signal light LS to the scanning point R12, and causes the low-coherence light L0 to flash and cause the signal light LS to enter the scanning point R12. . The CCD 34 receives the interference light LC based on the reflected light and outputs a detection signal.

  Similarly, the low-coherence light L0 irradiated to each scanning point is sequentially flashed while sequentially moving the incidence target of the signal light LS to the scanning points R13, R14,..., R1 (n−1), R1n. The detection signal from the CCD 34 is acquired.

  When the measurement at the last scanning point R1n of the first scanning line R1 is completed, the control unit 41 controls the galvanometer mirrors 22 and 23 at the same time, and sets the incidence target of the signal light LS to the second along the line changing scan r. Is moved to the first scanning point R21 of the scanning line R2. Then, the measurement at each scanning point R2j (j = 1 to n) of the second scanning line R2 is similarly performed, and the detection signal corresponding to each scanning point R2j is obtained.

  Similarly, measurement is performed for each of the third scanning line R3,..., The m−1th scanning line R (m−1), and the mth scanning line Rm, and a detection signal corresponding to each scanning point. To get. Thereby, the control unit 41 acquires m × n detection signals corresponding to m × n scanning points Rij (i = 1 to m, j = 1 to n) in the scanning region R. Hereinafter, the detection signal corresponding to the scanning point Rij may be represented as Dij.

  The linked control of the movement of the scanning point and the output of the low coherence light L0 as described above includes, for example, the transmission timing of the control signal for the mirror driving mechanisms 22A and 23A and the control signal (output request signal) for the low coherence light source device 2. The transmission timing can be synchronized with each other.

[Image formation processing]
Next, the image forming process executed by the image processing unit 42 will be described with further reference to FIG.

  The image processing unit 42 forms a tomographic image of the fundus oculi Er along each scanning line Ri by performing two-stage arithmetic processing, as in the conventional case. In the first stage arithmetic processing, the image processing unit 42 obtains an image in the depth direction (z direction shown in FIG. 1) of the fundus Er at the scanning point Rij based on the detection signal Dij corresponding to each scanning point Rij. Form. In the second-stage calculation process, a tomographic image of the fundus oculi Er along the scanning line Ri is formed for each scanning line Ri based on the image in the depth direction at the n scanning points Ri1 to Rin on the scanning line Ri. To do.

  That is, in the first stage, for each of the n incident positions (scanning points Rij) of the signal light LS along the main scanning direction (direction of the scanning line Ri), the signal light LS and the reference light that have passed through the incident position. This is a calculation process for forming an image in the depth direction (z direction) of the fundus Er at the incident position based on the detection signal Dij based on the interference light LC generated from the LR. The second stage is a calculation process for forming a tomographic image along the main scanning direction based on the images at the respective incident positions formed in the first stage. Thereby, m tomographic images at different positions in the sub-scanning direction (y direction) are obtained.

  An image Gmj shown in FIG. 7 represents an image in the depth direction (z direction) at the scanning point Rmj on the scanning line Rm, which is formed in the first stage. Similarly, the image in the depth direction at each scanning point Rij on each scanning line Ri, which is formed in the first stage arithmetic processing, may be represented as “image Gij”.

  In addition, images G1 to Gm in FIG. 7 are images formed in the second stage, and for each scanning line Ri, images Gij in the depth direction at n scanning points Rij (j = 1 to n) are obtained. It is an image formed by being arranged in the x direction (interpolation processing may be performed if necessary).

  The image processing unit 42 performs a process of forming a three-dimensional image representing the surface form and the internal form of the fundus oculi Er based on the m number of tomographic images obtained by the calculation process. This three-dimensional image forming process can be executed by a method similar to the conventional technique such as an interpolation process between adjacent tomographic images. The image processing unit 42 can also form a tomographic image in a direction other than the main scanning direction (the direction of the scanning line Ri; the x direction).

[Mode of operation]
An example of the operation mode of the optical image measurement device 1 having the above configuration will be described.

  First, the direction of the galvanometer mirrors 22 and 23 is changed so that the signal light LS is condensed at the scanning point R11, and the linearly polarized low-coherence light L0 is output from the low-coherence light source device 2. Since the polarization axis direction of the low coherence light L0 coincides with the direction of the slow axis (fast axis) of the PM fiber 3, the low coherence light L0 is guided to the optical coupler while maintaining the polarization axis direction.

  The optical coupler 4 splits the low coherence light L0 into the reference light LR and the signal light LS. The reference light LR and the signal light LS are linearly polarized light having the same polarization axis direction as that of the low coherence light L0. Since the PM fiber 5 is disposed such that the slow axis (fast axis) coincides with the polarization axis direction of the reference light LR, the reference light LR travels in the PM fiber 5 while maintaining the polarization axis direction. . In addition, since the PM fiber 6 is arranged so that the slow axis (fast axis) coincides with the polarization axis direction of the signal light LS, the signal light LS passes through the PM fiber 6 while maintaining the polarization axis direction. proceed.

  The reference light LR emitted from the PM fiber 5 is reflected by the reference mirror 14 via the collimator lens 11, the glass block 12, and the density filter 13, and is then PM by the collimator lens 11 via the density filter 13 and the glass block 12. The light is condensed on the fiber end of the fiber 5. The polarization axis direction of the reference light LR coincides with the slow axis (fast axis) of the PM fiber 5. Accordingly, the reference light LR travels through the PM fiber 5 while maintaining its polarization axis direction and returns to the optical coupler 4.

  On the other hand, the signal light LS emitted from the PM fiber 6 is converted into a parallel light beam by the collimator lens 21, and is a linear polarizer 27, quarter wave plate 28, galvanometer mirrors 22, 23, lens 24, dichroic mirror 25, objective lens. 26 enters the eye E through 26, and is focused on the scanning point R11 on the fundus Er.

  The signal light LS (including scattered light in the deep region of the fundus Er) reflected at the scanning point R11 is emitted from the eye E to be examined, the objective lens 26, the dichroic mirror 25, the lens 24, and the galvanometer mirrors 23, 22, and 1. The light is condensed on the fiber end of the PM fiber 6 by the collimator lens 21 via the / 4 wavelength plate 28 and the linear polarizer 27. The polarization axis direction of the signal light LS coincides with the slow axis (fast axis) direction of the PM fiber 6. Therefore, the signal light LS travels through the PM fiber 6 while maintaining its polarization axis direction and returns to the optical coupler 4.

  The optical coupler 4 superimposes the reference light LR that has passed through the reference mirror 14 and the signal light LS that has passed through the eye E to generate interference light LC. The polarization axis direction of the interference light LC coincides with the slow axis (fast axis) of the PM fiber 7. Accordingly, the interference light LC travels in the PM fiber 7 while being kept in the polarization axis direction and is guided to the spectrometer 30.

  The interference light LC is collimated by the collimator lens 31 of the spectrometer 30, is spectrally resolved by the diffraction grating 32, and is imaged on the imaging surface of the CCD 34 by the imaging lens 33. The CCD 34 receives the interference light LC and outputs a detection signal to the computer 40. The computer 40 analyzes the detection signal input from the CCD 34 and forms an image G11 in the depth direction at the scanning point R11 of the fundus oculi Er.

  The above operation is executed for each scanning point Rij to form an image Gij in the depth direction (i = 1 to m, j = 1 to n). The computer 40 forms a tomographic image Gi along each scanning line R1 based on these images Gij. If necessary, a three-dimensional image of the fundus oculi Er is formed based on these tomographic images Gij.

[effect]
According to the optical image forming apparatus 1 as described above, the following effects can be obtained.

  First, the optical image measurement apparatus 1 is configured to use linearly polarized low-coherence light L0 as measurement light and to guide the reference light LR and the signal light LS through the PM fibers 5 and 6, respectively. The directions of the polarization axes of the reference light LR and the signal light LS coincide with the slow axis or the fast axis of the PM fibers 5 and 6, respectively. Therefore, the reference light LR and the signal light LS travel through the PM fibers 5 and 6 while maintaining their polarization axis directions, respectively, and return to the optical coupler 4 in a state where the polarization axis directions coincide with each other. By maintaining such a polarization axis direction, it is possible to obtain the interference light LC that accurately reflects the information included in the signal light LS.

  By guiding the light using the PM fiber while maintaining the polarization axis direction in this way, high-accuracy image measurement is possible even if the device is used or transported in an environment where there is a temperature change or vibration. It can be performed. In addition, since it is not necessary to control the polarization state of the reference light and signal light using a polarization controller as in the prior art, the apparatus configuration is simplified and the cost is reduced.

  Further, since the linearly-polarized low-coherence light L0 output from the low-coherence light source device 2 is guided using the PM fiber 3 while maintaining the polarization axis direction, the reference light having linearly polarized light is used. LR and signal light LS can be generated without being influenced by the environment.

  In addition, the interference light LC generated from the reference light LR and the signal light LS is also guided using the PM fiber 7 while maintaining the polarization axis direction, so that it is not affected by the environment. It is possible to detect a suitable interference light LC.

  Further, since the linear polarizer 27 is provided on the optical path of the signal light LS, the influence on the polarization state by the eye E is corrected, and the linearly polarized signal light LS in the same polarization axis direction as the original is converted into the PM fiber. 6 can be made incident.

  That is, the polarization characteristics of the signal light LS incident on the eye E with linearly polarized light change due to the influence of the eyeball optical system. The polarization characteristics shown in FIG. 8 represent the case where the signal light LS is elliptically polarized by the eye E. Here, the polarization axis direction of the signal light LS or the like coincides with the slow axis, and the linear polarizer 27 is disposed so as to transmit the polarization component in the slow axis direction.

  The signal light LS that has been converted to elliptically polarized light P by the eye E generally forms an angle with respect to the slow axis of the PM fiber 6. The linear polarizer 27 transmits the polarization component in the slow axis direction of the signal light LS of the elliptically polarized light P, thereby converting the polarization characteristic of the signal light LS into the linearly polarized light Px in the slow axis direction. Thereby, the interference light LC can be generated using the signal light LS having linearly polarized light in the slow axis direction.

  The above-described effect can be obtained even if only the linear polarizer 27 is used. However, the amount of the signal light LS transmitted through the linear polarizer 27 is reduced according to the polarization direction of the signal light LS. There is also. This inconvenience is eliminated by using the quarter wavelength plate 28 together as described below.

  The operation of the quarter wave plate 28 will be described with reference to FIG. The elliptically polarized light P represents the polarization state of the signal light LS influenced by the eye E as in FIG. The signal light LS passes through the quarter-wave plate 28 before and after entering the eye E, and the polarization axis is rotated by π = 180 degrees. As a result, as shown in FIG. 9, the polarization characteristic (elliptical polarization P) of the signal light LS affected by the eye E has elliptic polarization in the slow axis direction (elliptical polarization having a major axis in the slow axis direction) P. Converted to ′. Thus, by converting the signal light LS incident on the linear polarizer 27 into elliptical polarized light in the slow axis direction, the amount of the signal light LS transmitted through the linear polarizer 27 can be increased.

  In addition, when the influence of the linearly polarized light on the signal light LS by the eye E is only the rotation of the polarization axis, it can be dealt with only by the quarter wavelength plate 28 (that is, the linear polarizer 27 is unnecessary). However, in general, it is desirable to use the linear polarizer 27 and the quarter-wave plate 28 together in consideration of the influence of the eye E to be examined as a change in elliptical polarization or circular polarization occurs as the polarization direction rotates.

  Further, in the optical image measurement device 1 of the present embodiment, the Faraday isolator 2c is built in the low coherence light source device 2 so as to block the return light. Therefore, it is possible to prevent an adverse effect on the low-coherence light source 2a due to the return light of the reference light LR and the signal light LS.

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

  FIG. 10 shows (part of) an optical image measurement device 60 of the present invention having a configuration different from that of the above embodiment. The low coherence light output from the low coherence light source 61 is converted into a parallel light beam by the collimator lens 62 and guided to the Faraday isolator 63. The Faraday isolator 63 includes a polarizer 64, a Faraday rotator 65, and an analyzer 66. A beam splitter 67 is provided obliquely ahead of the low-coherence light that has been linearly polarized by the Faraday isolator 63.

  The low coherence light is split into reference light and signal light by the beam splitter 67. Here, light transmitted through the beam splitter 67 is referred to as reference light, and light reflected by the beam splitter 67 is referred to as signal light. The beam splitter 67 transmits, for example, 80% of the amount of low-coherence light (reference light) and reflects 20% (signal light). Each of the reference light and the signal light is light having linearly polarized light in the same polarization axis direction as that of the optical coherence light.

  The reference light is condensed on the fiber end of the PM fiber 70 by the condenser lens 68. The fiber end of the PM fiber 70 is held by a fiber end holding portion 69. The PM fiber 70 is disposed so that the slow axis (or fast axis) coincides with the polarization axis direction of the linearly polarized reference light. The reference light travels in the PM fiber 70 while maintaining the polarization axis direction, and exits from the opposite fiber end. The emission end is held by the fiber end holding portion 71.

  The reference light emitted from the PM fiber 70 is collimated by the collimator lens 72 and reflected by the reference mirror 73. The reflected reference light is condensed on the fiber end held by the fiber end holding portion 71 by the collimator lens 72, travels in the PM fiber 70 while maintaining the polarization axis direction, and exits from the opposite fiber end. . Then, after being converted into a parallel light beam by the condenser lens 68, it proceeds toward the beam splitter 67.

  On the other hand, the signal light is condensed on the fiber end of the PM fiber 76 by the condenser lens 74. The fiber end of the PM fiber 76 is held by a fiber end holding portion 75. The PM fiber 76 is disposed so that the slow axis (or fast axis) coincides with the polarization axis direction of the linearly polarized signal light. The signal light travels in the PM fiber 76 while maintaining the polarization axis direction, and exits from the opposite fiber end. The emission end is held by the fiber end holding portion 77.

  The signal light emitted from the PM fiber 76 is converted into a parallel light beam by the collimator lens 78 and guided toward the eye to be examined (not shown) via the linear polarizer 79 and the quarter wavelength plate 80. Although not shown, a galvanometer mirror, a lens, a dichroic mirror, an objective lens, and the like are disposed between the quarter-wave plate 79 and the eye to be examined, for example, as in the configuration shown in FIG. Yes.

  The signal light reflected from the fundus of the subject's eye (including scattered light in the deep region) passes through these optical members, the quarter-wave plate 80, and the linear polarizer 79, and is then converted into PM by the collimator lens 78. The light is collected at the fiber end of the fiber 76. The signal light travels in the PM fiber 76 while maintaining the polarization axis direction, and is emitted from the opposite fiber end. Then, after being converted into a parallel light beam by the condenser lens 74, it proceeds toward the beam splitter 67.

  Here, the linear polarizer 79 operates in the same manner as the linear polarizer 28 of the optical image measurement device 1 described above. Further, the quarter wavelength plate 80 operates in the same manner as the quarter wavelength plate 28 of the optical image measurement device 1.

  The reference light that has passed through the reference mirror 73 and the signal light that has passed through the eye to be examined are both linearly polarized light, and their polarization axes are the same. Therefore, the reference light and the signal light are superimposed by the beam splitter 67 to generate interference light. The generated interference light is condensed on the fiber end of the single mode fiber 83 by the collimator lens 81. The fiber end of the single mode fiber 83 is held by a fiber end holding portion 82.

  The single mode fiber 83 is guided to a detection unit (not shown). This detection unit is configured to include a spectrometer, for example, similarly to the configuration shown in FIG. The spectrometer detects interference light and transmits a detection signal to a computer (not shown).

  This computer has the same configuration as that shown in FIGS. 2 and 3, for example, and analyzes the detection signal from the spectrometer to form an image of the fundus of the eye to be examined. The image forming process can be performed in the same manner as the optical image measurement device 1.

  According to such an optical image forming apparatus 60, the reference light and the signal light are respectively guided by the PM fiber, and the polarization axis direction of the reference light and the signal light is the slow axis of the PM fiber. (Or the fast axis), the reference light and the signal light return to the optical coupler 4 in a state in which the directions of the polarization axes of the reference light and the signal light coincide with each other. Accordingly, it is possible to obtain interference light that accurately reflects information included in the signal light.

  By guiding the light using the PM fiber while maintaining the polarization axis direction in this way, high-accuracy image measurement is possible even if the device is used or transported in an environment where there is a temperature change or vibration. It can be performed. In addition, since it is not necessary to control the polarization state of the reference light and signal light using a polarization controller as in the prior art, the apparatus configuration is simplified and the cost is reduced.

  Note that, unlike the optical image measurement device 1, the optical image measurement device 60 includes only the first light guide means (PM fiber 76) and the second light guide means (PM fiber 70) of the present invention. The third and fourth light guiding means are not provided. That is, in the optical image measuring device 60, the output linearly polarized low-coherence light is directly incident on the beam splitter 67 without using the optical fiber, and the interference light is guided using the single mode fiber 83. It is supposed to be. Even with such a configuration, signal light and reference light having the same polarization axis direction as linearly polarized low-coherence light can be generated, and interference light can be suitably generated from the signal light and reference light. There is no particular inconvenience.

  In the above-described optical image measurement apparatuses 1 and 60, the fundus of the human eye is applied as the object to be measured, but the present invention is limited to any part of an arbitrary living organism (limited to a part that can be measured by the optical image measurement apparatus). It is possible to apply to. Further, the present invention is not limited to the medical field and the biological field, and can be applied to other fields such as the industrial field.

  Further, in the optical image measurement devices 1 and 60, the optical image measurement device configured to measure the surface form and internal form of the measurement object using the reflected light from the measurement object has been described. The present invention can also be applied to an optical image measurement device configured to measure the surface form and the internal form using the measured light.

It is a schematic block diagram showing an example of the whole structure of suitable embodiment of the optical image measuring device which concerns on this invention. It is a schematic block diagram showing an example of the structure of the control system of suitable embodiment of the optical image measuring device which concerns on this invention. It is a schematic block diagram showing an example of the hardware constitutions of the computer with which suitable embodiment of the optical image measuring device which concerns on this invention comprises. It is the schematic showing an example of the structure of the low coherence light source device apparatus with which suitable embodiment of the optical image measuring device which concerns on this invention comprises. It is the schematic showing an example of the structure of PM fiber with which suitable embodiment of the optical image measuring device which concerns on this invention comprises. FIG. 5A is a perspective view of the PM fiber, and FIG. 5B is a cross-sectional view of the PM fiber. It is the schematic showing an example of the scanning aspect of the signal light by suitable embodiment of the optical image measuring device which concerns on this invention. FIG. 6A illustrates an example of a scanning mode of the signal light when the fundus is viewed from the incident side (−z direction) of the signal light. FIG. 6B shows an example of an arrangement mode of scanning points on each scanning line. It is the schematic showing an example of the scanning aspect of the signal light by the suitable embodiment of the optical image measuring device which concerns on this invention, and the form of the tomographic image formed along each scanning line. It is a schematic explanatory drawing for demonstrating the effect | action of the linear polarizer with which suitable embodiment of the optical image measuring device which concerns on this invention comprises. It is a schematic explanatory drawing for demonstrating the effect | action of the quarter wavelength plate with which suitable embodiment of the optical image measuring device which concerns on this invention comprises. It is a schematic block diagram showing the structure of other suitable embodiment of the optical image measuring device which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 60 Optical image measuring device 2 Low coherence light source device 2a, 61 Low coherence light source 2b, 62, 72, 78 Collimator lens 2c, 63 Faraday isolator 2d, 64 Polarizer (incident polarizer)
2e, 65 Faraday rotator 2f, 66 Analyzer 2g, 68, 74, 81 Condensing lens 2h, 69, 71, 75, 77, 81 Fiber end holding part 3, 5, 6, 7, 70, 76 PM fiber 3a Core 3b Clad 3c, 3d Stress applying part X Slow axis Y Fast axis 4 Optical coupler 11, 21, 31 Collimator lens 12 Glass block 13 Density filter 14, 73 Reference mirror 22, 23 Galvano mirror 22a, 23a Rotating shaft 22A, 23A Mirror Drive mechanism 24 Lens 25 Dichroic mirror 26 Objective lens 27, 79 Linear polarizer 28, 80 1/4 wavelength plate 30 Spectrometer 32 Diffraction grating 33 Imaging lens 34 CCD
40 Computer 41 Control Unit 42 Image Processing Unit 43 User Interface (UI)
67 Beam splitter 83 Single mode fiber 100 CPU
103 Hard Disk Drive 103a Control Program 104 Keyboard 105 Mouse 106 Display 50 Observation Device (Photographing Device)
L0 low coherence light LR reference light LS, LS ′ signal light LC, LC ′ interference light R scanning region R1 to Rm scanning line RS scanning start position RE scanning end position Rij (i = 1 to m, j = 1 to n) scanning Points G1 to Gm Tomographic image Gij (i = 1 to m, j = 1 to n) Image in depth direction E Eye to be examined Er Fundus

Claims (13)

Light output means for outputting linearly polarized low-coherence light;
Splitting means for splitting the outputted low coherence light into linearly polarized signal light and reference light each having the same polarization axis direction as the low coherence light;
The linearly polarized signal light obtained by the division is guided toward the object to be measured while maintaining the polarization axis direction, and the signal light that has passed through the object to be measured is guided while maintaining the polarization axis direction. First light guiding means for
The linearly polarized reference light obtained by the division is guided toward the reference object while maintaining the polarization axis direction, and the reference light passing through the reference object is guided while maintaining the polarization axis direction. Two light guiding means;
The signal light that has passed through the object to be measured guided by the first light guiding unit and the reference light that has passed through the reference object guided by the second light guiding unit are superimposed on each other. Superimposing means for generating interference light;
Detecting means for receiving the generated interference light and outputting a detection signal;
Image forming means for forming an image of the measured object based on the output detection signal;
Comprising
An optical image measuring device characterized by that. The first light guiding means is a polarization-maintaining fiber disposed so that a fast axis or a slow axis is aligned with a polarization axis direction of linearly polarized signal light obtained by the division.
The optical image measuring device according to claim 1. The second light guide means is a polarization-maintaining fiber disposed so that the fast axis or the slow axis is aligned with the polarization axis direction of the linearly polarized reference light obtained by the division.
The optical image measurement device according to claim 1, wherein the optical image measurement device is an optical image measurement device. A third light guide means for guiding the linearly polarized low-coherence light output by the light output means toward the splitting means while maintaining a polarization axis direction;
The optical image measurement device according to any one of claims 1 to 3, wherein The third light guiding means is a polarization-maintaining fiber disposed so that the fast axis or the slow axis is aligned with the polarization axis direction of the linearly polarized low-coherence light output from the light output means.
The optical image measuring device according to claim 4. The first light guide means is a polarization-maintaining fiber disposed so that one of the fast axis and the slow axis coincides with the polarization axis direction of the linearly polarized signal light obtained by the division. ,
The second light guide means is a polarization-maintaining fiber disposed so that the one axis coincides with the polarization axis direction of the linearly polarized reference light obtained by the division.
The optical image measuring device according to claim 1. Arranged so that the one axis coincides with the polarization axis direction of the linearly polarized low-coherence light output by the light output means, and guides the output low-coherence light toward the dividing means. A polarization maintaining fiber;
The optical image measuring device according to claim 6. A fourth light guide means for guiding the interference light generated by the superimposing means toward the detection means;
The optical image measurement device according to any one of claims 1 to 7, wherein The fourth light guide means guides the generated interference light while maintaining a polarization axis direction;
The optical image measuring device according to claim 8. On the optical path between the measured object and an incident end where the signal light passing through the measured object is incident on the first light guide means, the signal light is transmitted by the first light guide means. A linear polarizer that transmits the polarization component in the same direction as the polarization axis when guided toward the object to be measured is provided.
The optical image measuring device according to any one of claims 1 to 9, wherein The first light guide means is configured such that the signal light passing through the object to be measured is incident on an emission end from which the signal light before passing through the object to be measured is emitted,
A quarter wave plate was provided on the optical path between the object to be measured and the exit end,
The optical image measurement device according to any one of claims 1 to 10, wherein the optical image measurement device is an optical image measurement device. The light output means includes a light source that outputs low-coherence light, and polarization characteristic conversion means that converts the polarization characteristic of the output low-coherence light into linearly polarized light.
The optical image measurement device according to any one of claims 1 to 11, wherein The polarization characteristic converting unit includes a first polarization unit that converts the low-coherence light output from the light source into linearly polarized light, and a second polarization that rotates the polarization axis direction of the low-coherence light converted into the linearly polarized light by 45 degrees. A Faraday isolator having means and third polarization means for transmitting only the polarization component in the polarization axis direction of the low-coherence light rotated by 45 degrees.
The optical image measurement device according to claim 12.

Images