JP2013113587A - Optical image measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten scan time in OCT measurement.SOLUTION: In an optical image measuring apparatus, a first division part divides light from a light source into signal light and reference light. A second division part divides an optical path of the signal light into a plurality of signal optical paths having respectively different optical path lengths. A synthesis part synthesizes a plurality of signal lights through the plurality of signal optical paths. A third division part divides the optical path of the reference light into a plurality of reference optical paths respectively having optical path lengths corresponding to the plurality of signal optical paths. A superposition part superposes return lights of the plurality of synthesized signal lights from an object to be measured to the plurality of reference lights passed through the plurality of reference optical paths to generate interference light. A fourth division part divides an optical path of the interference light into a plurality of interference optical paths. A detection part is arranged on each interference optical path to detect the interference light. A scanning part scans the signal light. A formation part forms a plurality of tomographic images of the object to be measured based on detection results of a plurality of detection parts respectively detecting interference lights between the return lights of scanned signal lights and the reference lights.

Description

  The present invention relates to an optical image measurement device that acquires an image of an object to be measured by using optical coherence tomography (OCT).

  In recent years, OCT that forms an image representing the surface form or internal form of an object to be measured using a light beam from a laser light source or the like has attracted attention. Since OCT has no invasiveness to the human body like X-ray CT, it is expected to be applied particularly in the medical field and the biological field. For example, in the field of ophthalmology, an apparatus for forming an image of the fundus oculi or cornea has been put into practical use.

  Patent Document 1 discloses an apparatus to which OCT 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 OCT)” 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. Note that this technique is also called 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. This apparatus is configured to scan the light beam only in one direction (x direction) orthogonal to the z direction. An image formed by this apparatus is a two-dimensional tomographic image in the depth direction (z direction) along the scanning direction (x direction) of the light beam.

  In Patent Document 2, a plurality of two-dimensional tomographic images in the horizontal direction are formed by scanning (scanning) the signal light in the horizontal direction (x direction) and the vertical direction (y direction), and based on the plurality of tomographic images. A technique for acquiring and imaging three-dimensional tomographic information of a measurement range is disclosed. As this three-dimensional imaging, for example, a method of displaying a plurality of tomographic images side by side in a vertical direction (referred to as stack data or the like), volume data (voxel data) based on the stack data is rendered, and a three-dimensional image is rendered. There is a method of forming.

  Patent Documents 3 and 4 disclose other types of OCT apparatuses. In Patent Document 3, the wavelength of light irradiated to a measured object is scanned (wavelength sweep), and interference intensity obtained by superimposing reflected light of each wavelength and reference light is detected to detect spectral intensity distribution. And an OCT apparatus for imaging the form of an object to be measured by performing Fourier transform on the obtained image. Such an OCT apparatus is called a swept source type. The swept source type is a kind of 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 configuration in which OCT is applied to the ophthalmic field. Prior to the application of OCT, a fundus camera, a slit lamp, or the like was used as an apparatus for observing the eye to be examined (see, for example, Patent Document 6 and Patent Document 7). A fundus camera is a device that shoots the fundus by illuminating the subject's eye with illumination light and receiving the fundus reflection light. A slit lamp is a device that acquires an image of a cross-section of the cornea by cutting off a light section of the cornea using slit light.

  An apparatus using OCT has an advantage over a fundus camera or the like in that a high-definition image can be acquired, and further, a tomographic image or a three-dimensional image can be acquired.

  As described above, an apparatus using OCT can be applied to observation of various parts of an eye to be examined, and can acquire high-definition images, and thus has been applied to diagnosis of various ophthalmic diseases.

  In the type of OCT that scans an object to be measured as in the Fourier domain OCT, it is desired to reduce the scan time, that is, the measurement time. In particular, when the object to be measured moves, as in ophthalmic OCT, if the object to be measured moves during the measurement, the accuracy and accuracy of the image are reduced. Therefore, shortening the scan time is an important issue. It is supposed to be. For example, Patent Documents 8 and 9 are known as techniques for shortening the scan time.

JP 11-325849 A JP 2002-139421 A JP 2007-24677 A JP 2006-153838 A JP 2008-73099 A JP-A-9-276232 JP 2008-259544 A JP 2010-249484 A JP 2010-261858 A

  Patent Documents 8 and 9 describe an optical system that irradiates a measured object with a plurality of signal lights (sample light) and detects interference light between the return light and reference light. However, this optical system is very complicated, and there is a problem that adjustment for obtaining a suitable interference signal is difficult and the cost is high. Furthermore, in the apparatuses described in Patent Documents 8 and 9, it is desired to scan a wide range, but for this purpose, it is necessary to use a galvano scanner having a large shake width, which also causes an increase in cost. .

  An object of the present invention is to provide an optical image measurement device capable of shortening a scan time.

In order to achieve the above-mentioned object, the invention according to claim 1 has a first splitting unit that splits light from a light source into signal light and reference light, and the optical paths of the signal light have different optical path lengths. A second division unit that divides the plurality of signal light paths, a combining unit that combines a plurality of signal lights that have passed through the plurality of signal light paths, and an optical path length corresponding to the plurality of signal light paths. A third dividing unit that divides the light into a plurality of reference light paths, return light from the object to be measured of the plurality of signal lights combined by the combining unit, and a plurality of reference lights that pass through the plurality of reference light paths Are superimposed on each other to generate interference light, a fourth division unit that divides the optical path of the interference light into a plurality of interference optical paths, and a plurality of interference optical paths, and guides the interference optical paths. A detecting unit for detecting the interference light, and a scanning unit for scanning the signal light. And a plurality of tomographic images of the object to be measured based on the detection results of the interference light obtained by superimposing the scanned return light of the signal light on the reference light And an optical image measurement device having a forming unit.
The invention according to claim 2 is the optical image measurement device according to claim 1, wherein the second dividing unit converts the signal light generated by the first dividing unit into two signal lights. It is characterized by dividing into two.
The invention according to claim 3 is the optical image measurement device according to claim 2, wherein the traveling directions of the two signal lights are symmetric with respect to the optical axis.
According to a fourth aspect of the present invention, there is provided the optical image measuring device according to the third aspect, wherein the second dividing unit is an optical element formed by connecting a prism to the first reflecting surface of an erecting prism. It is characterized by being.
The invention according to claim 5 is the optical image measurement device according to any one of claims 2 to 4, wherein the scanning unit is a signal generated by the first dividing unit. A first scanning unit that scans light in a predetermined direction, and a second scanning unit that scans signal light combined by the combining unit in a direction orthogonal to the predetermined direction are included.
The invention according to claim 6 is the optical image measurement device according to any one of claims 2 to 4, wherein the scanning unit is a signal generated by the first dividing unit. It includes a first scanning unit that scans light in a predetermined direction, and a second scanning unit that scans the signal light in a direction orthogonal to the predetermined direction.
The invention according to claim 7 is the optical image measurement device according to any one of claims 2 to 4, wherein the two signal lights are generated by the first dividing unit. The P-polarized component and the S-polarized component of the signal light.
The invention according to claim 8 is the optical image measurement device according to claim 7, wherein a half-wave plate provided in each optical path of the P-polarized component and the S-polarized component; And a mechanism for rotating the half-wave plate, wherein the third splitting unit is a polarization beam splitter.

  According to the present invention, a plurality of signal lights passing through a plurality of signal light paths having different optical path lengths are combined and irradiated on an object to be measured, and interference light obtained by superimposing the return light and the reference light is applied to the plurality of interference lights. It is possible to form a plurality of tomographic images based on the detection results detected by the detection units and the detection results by these detection units. Therefore, it is possible to shorten the scan time.

It is a schematic diagram showing an example of composition of an optical image measuring device concerning a 1st embodiment. It is a schematic diagram showing an example of composition of an optical image measuring device concerning a 1st embodiment. It is a schematic block diagram showing an example of composition of an optical image measuring device concerning a 1st embodiment. It is the schematic showing an example of the scanning aspect by the optical image measuring device which concerns on 1st Embodiment. It is the schematic showing an example of a structure of the optical image measuring device which concerns on 2nd Embodiment. It is a schematic block diagram showing an example of composition of an optical image measuring device concerning a 2nd embodiment. It is the schematic showing an example of the scanning aspect by the optical image measuring device which concerns on 2nd Embodiment. It is the schematic showing an example of a structure of the optical image measuring device which concerns on 3rd Embodiment. It is a schematic block diagram showing an example of the structure of the optical image measuring device which concerns on 3rd Embodiment.

  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 apparatus according to the present invention forms a tomographic image or a three-dimensional image of an object to be measured using OCT. In this specification, images acquired by OCT may be collectively referred to as OCT images. In addition, a measurement operation for forming an OCT image may be referred to as OCT measurement. In addition, it is possible to use suitably the description content of the literature described in this specification as the content of the following embodiment.

  In the following embodiment, an apparatus that performs OCT measurement by applying Fourier domain type OCT, where an object to be measured is an eye to be examined (fundus). In particular, the apparatus according to the embodiment uses a spectral domain OCT technique. Note that the configuration according to the present invention can be applied to an optical image measurement apparatus using a type other than the spectral domain, for example, a swept source OCT technique.

<First Embodiment>
An example of the configuration of the optical system of the optical image measurement device according to this embodiment is shown in FIG. The light output from the light source 2 of the optical image measuring device 1 is refracted by the lens 3 and reaches the half mirror 4. The light transmitted through the half mirror 4 becomes signal light irradiated to the eye E. On the other hand, the light reflected by the half mirror 4 becomes reference light. In the spectral domain OCT, a broadband low-coherence light source is used as the light source 2. In the swept source OCT, a broadband wavelength swept light source is used as the light source 2.

  First, the signal light and its optical path will be described. A galvanometer mirror 11 and an optical element 12 are provided in the optical path (signal optical path) A of the signal light. The galvanometer mirror 11 scans the signal light in the horizontal direction (x direction). That is, the galvanometer mirror 11 changes the traveling direction of the signal light in the x direction.

  The signal light that has passed through the galvanometer mirror 11 enters the optical element 12. The optical element 12 divides the signal optical path A into a plurality of signal optical paths having different optical path lengths. In this embodiment, the optical element 12 divides the signal light path A into two signal light paths A1 and A2.

  An example of the configuration of the optical element 12 is shown in FIG. The optical element 12 is obtained by connecting a prism 12B to the first reflecting surface 12a of the erecting prism 12A. The erecting prism 12A is generally an optical element that converts an inverted image into an erect image. The optical element 12 of this embodiment is configured such that the prism 12a (an inclined surface) is attached to a surface (reflecting surface 12a) on which the signal light incident on the erecting prism 12A is first reflected. The

Thereby, the incident signal light is divided into two at this reflection surface 12a (attachment surface). Components transmitted through the reflecting surface 12a is emitted from the optical element 12 as the light (first signal light) having the same traveling direction D _{out 1} to the traveling direction D _in the incident signal light. Meanwhile, component reflected by the reflecting surface 12a is compared with the traveling direction D _in the incident signal light, light having a (horizontal direction i.e. in the x-direction) symmetrical traveling direction D _{out 2} with respect to the optical axis ( The second signal light is emitted from the optical element 12. Thus, the traveling direction _{D out} 1 of the first signal light emitted from the optical element 12, the traveling direction _{D out} 2 of the second signal light is subject to the optical axis.

  The first signal light emitted from the optical element 12 reaches the half mirror 18 via the relay lenses 13 and 14 provided in the first signal light path A1. On the other hand, the second signal light emitted from the optical element 12 reaches the half mirror 18 via the relay lenses 15 and 16 and the reflection mirror 17 provided in the second signal light path A2.

  The half mirror 18 combines the first signal light and the second signal light. That is, the half mirror 18 combines the first and second signal light paths A1 and A2 to form the signal light path A3. The first signal light transmitted through the half mirror 18 and the second signal light reflected by the half mirror 18 are scanned in the vertical direction (y direction) by the galvanometer mirror 19 provided in the signal light path A3. The signal light deflected by the galvanometer mirror 19 is incident on the eye E through the focusing lens 20 and the objective lens 21 and is irradiated on the fundus oculi Ef. The focusing lens 20 is movable along the signal optical path A3 (its optical axis) and is used for focusing the optical system with respect to the fundus oculi Ef.

  The signal light applied to the fundus oculi Ef is scattered (including reflection) at various depth positions of the fundus oculi Ef. The backscattered light of the signal light from the fundus oculi Ef travels in the opposite direction on the same path as the forward path and is guided to the half mirror 4.

  Next, reference light and its optical path will be described. A half mirror 31 is provided in the optical path (reference optical path) B of the reference light. The half mirror 31 divides the reference optical path B into a first reference optical path B1 and a second reference optical path B2. The component reflected by the half mirror 31 is guided to the first reference light path B1, and the component transmitted through the half mirror 31 is guided to the second reference light path B2.

  The first reference light guided to the first reference light path B1 is imaged on the reflecting surface of the reference mirror 33 by the collimator lens 32. The first reference light reflected by the reference mirror 33 travels in the opposite direction on the same path and is guided to the half mirror 4. The collimator lens 32 and the reference mirror 33 are movable along the optical axis of the first reference optical path B1. The optical distance from the half mirror 4 via the first signal light path A1 to the fundus oculi Ef and the optical distance from the half mirror 4 to the reference mirror 33 in the first reference light path B1 are substantially equal. The position of the reference mirror 33 is adjusted.

  A reflection mirror 34, a collimator lens 35, and a reference mirror 36 are provided in the second reference light path B2. The second reference light guided to the second reference light path B2 is reflected by the reflecting mirror 34 and then imaged on the reflecting surface of the reference mirror 36 by the collimator lens 35. The second reference light reflected by the reference mirror 36 travels in the opposite direction on the same path and is guided to the half mirror 4. The collimator lens 35 and the reference mirror 36 are movable along the optical axis of the second reference optical path B2. The optical distance from the half mirror 4 via the second signal light path A2 to the fundus oculi Ef and the optical distance from the half mirror 4 to the reference mirror 36 in the second reference light path B2 are substantially equal. The position of the reference mirror 36 is adjusted.

  As described above, the half mirror 4 includes the backscattered light of the signal light (first return light) that has passed through the first signal light path A1 and the backscattered light of the signal light that has passed through the second signal light path A2. (Second return light), the first reference light passing through the first reference light path B1, and the second reference light passing through the second reference light path B2 are returned. Due to the principle of the low coherence interference optical system used for OCT, the first return light and the second reference light interfere, and the second return light and the second reference light interfere. Note that the difference in optical path length between the first signal optical path A1 and the second signal optical path A2 is sufficiently larger than the coherent length of the light from the light source 1.

  The interference light generated by the half mirror 4 is guided along the interference light path C. A half mirror 41 is provided in the interference optical path C. The first interference light reflected by the half mirror 4 is incident on the first interference optical path C 1, is split (spectral decomposition) by the spectroscope 42, and is projected onto the light receiving surface of the CCD image sensor 43. The CCD image sensor 43 is, for example, a line sensor, and detects each spectral component of the split first interference light and converts it into electric charges. The CCD image sensor 43 accumulates this electric charge, generates a detection signal, and outputs it. The first interference light is light obtained by interference between the first return light and the first reference light.

  On the other hand, the second interference light transmitted through the half mirror 4 enters the second interference optical path C2, is reflected by the reflection mirror 44, is dispersed by the spectroscope 45, and is projected onto the light receiving surface of the CCD image sensor 46. . The CCD image sensor 46 is, for example, a line sensor, and detects each spectral component of the split second interference light and converts it into electric charges. The CCD image sensor 46 accumulates this electric charge, generates a detection signal, and outputs it. The second interference light is light obtained by interference between the second return light and the second reference light.

  In this embodiment, a Michelson type interferometer is employed, but any type of interferometer such as a Mach-Zehnder type can be appropriately employed. Further, in place of the CCD image sensor, another form of image sensor such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor can be used.

  The optical image measurement device 1 is provided with an alignment optical system, a focus optical system, and a fixation optical system (all are not shown) as in a conventional ophthalmologic apparatus (fundus camera or the like). The alignment optical system projects an index (alignment index) for performing alignment (alignment) in the xy direction of the apparatus optical system with respect to the eye E to be examined E. The focus optical system projects an index (split index) for focusing on the fundus oculi Ef onto the fundus oculi Ef. The fixation optical system projects a fixation target for fixing the eye E to be examined in a predetermined direction onto the fundus oculi Ef.

  The configuration of the control system of the optical image measurement device 1 will be described. An example of the configuration of the control system is shown in FIG. The control system is configured around the control unit 100. The control unit 100 includes a main control unit 101 and a storage unit 102. The main control unit 101 controls each unit of the optical image measurement device 1. The storage unit 102 stores various data. Examples of data stored in the storage unit 102 include OCT image image data, fundus image data, eye information to be examined, and the like. The storage unit 102 stores in advance a computer program for control and a computer program for arithmetic processing. The main control unit 101 executes various controls and calculations based on these computer programs.

  The main control unit 101 controls the operation of the light source 2. The main control unit 101 scans the signal light in the xy direction by independently controlling the galvanometer mirrors 11 and 19. The main control unit 101 moves the focusing lens 20 along the optical axis by controlling the focusing drive unit 20A. The main control unit 101 controls the reference driving units 33A and 36A to move the collimator lens 32 and the reference mirror 33 integrally along the optical axis, and to integrally move the collimator lens 35 and the reference mirror 36. Move along the optical axis. The main control unit 101 controls the operations (sensitivity, accumulation time, etc.) of the CCD image sensors 43 and 46.

  Each of the CCD image sensors 43 and 46 detects the interference light, generates an electrical signal (detection signal), and sends it to the image forming unit 110. The image forming unit 110 forms tomographic image data of the fundus oculi Ef based on detection signals from the CCD image sensors 43 and 46, respectively. This process includes processes such as noise removal (noise reduction), filter processing, FFT (Fast Fourier Transform), and the like, as in the conventional spectral domain type optical coherence tomography. In the case of another type of OCT apparatus, the image forming unit 110 executes a known process corresponding to the type. The image forming unit 110 functions as an example of a “forming unit”. The image forming unit 110 includes, for example, a circuit board specialized for image forming processing.

The image processing unit 120 performs various types of image processing and analysis processing on the image formed by the image forming unit 110. For example, the image processing unit 120 executes various correction processes such as image brightness correction and dispersion correction. The image processing unit 120 executes known image processing such as interpolation processing for interpolating pixels between tomographic images to form image data (volume data) of a three-dimensional image of the fundus oculi Ef. Further, the image processing unit 120 performs rendering processing on the volume data to form image data of a pseudo three-dimensional image when viewed from a specific viewing direction.
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.

  The user interface 130 includes a display unit 131 and an operation unit 132. The display unit 131 displays OCT images and various data. The operation unit 132 is used for operation of the optical image measurement device 1 and information input thereto. The operation unit 132 includes buttons and keys provided on the housing of the optical image measurement device 1 or an external device. The display unit 131 and the operation unit 132 need not be configured as individual devices. For example, a device in which a display function and an operation function are integrated, such as a touch panel monitor, can be used. In that case, the operation unit 132 includes the touch panel display and a computer program. The operation content for the operation unit 132 is input to the control unit 132 as an electrical signal. Further, operations and information input may be performed using the graphic user interface (GUI) displayed on the display unit 131 and the operation unit 132.

The optical image measurement device 1 includes the following components:
A half mirror 4 (first dividing unit) for dividing light from the light source 2 into signal light and reference light;
An optical element 12 (second division unit) that divides the optical path A of the signal light into a plurality (two) of signal optical paths A1 and A2 having different optical path lengths;
A half mirror 18 (combining unit) that combines a plurality (two) of signal lights via a plurality (two) of signal light paths A1 and A2.
A half mirror 31 (third dividing unit) that divides the optical path B of the reference light into a plurality of (two) reference optical paths B1 and B2 having optical path lengths corresponding to the plurality (two) of signal optical paths A1 and A2.
The return light from the fundus oculi Ef of the plurality (two) of signal lights synthesized by the half mirror 18 is superimposed on the plurality (two) of reference lights via the plurality (two) of the reference light paths B1 and B2. Half mirror 4 (superimposing section) that generates interference light
A fourth dividing unit that divides the optical path C of the interference light into a plurality of (two) interference optical paths C1 and C2,
A plurality (two) of CCD image sensors 43 and 46 (a plurality of detection units) provided in each of a plurality (two) of interference light paths C1 and C2 and detecting the interference light guided through the interference light paths C1 and C2. ;
Galvano mirrors 11 and 19 (scanning unit) that scan the signal light;
Based on the detection results of the plurality (two) of CCD image sensors 43 and 46 of the interference light obtained by superimposing the return light of the scanned signal light on the reference light, a plurality (two) of tomograms of the fundus oculi Ef. An image forming unit 110 (forming unit) that forms an image.

  Here, the scanning unit scans the signal light generated by the half mirror 4 in a predetermined direction (x direction) and the galvano mirror 11 (first scanning unit) and the signal light combined by the half mirror 18 in a predetermined direction. And a galvanometer mirror 19 (second scanning unit) that scans in a direction (y direction) orthogonal to (x direction).

  According to such an optical image measurement device 1, the characteristic of the optical element 12, that is, the characteristic that the traveling directions of the two signal lights emitted from the optical element 12 are symmetric with respect to the optical axis, Since the galvanometer mirrors 11 and 19 are provided on the side and the rear side, respectively, the signal light can be simultaneously scanned in the opposite directions to the same scanning line.

  As a specific example, as shown in FIG. 4, the first signal light passing through the first signal light path A1 is scanned in the manner indicated by reference numeral S1, and simultaneously the second signal light passing through the second signal light path A2. Can be scanned in the manner indicated by reference numeral S2. This scanning mode is realized by scanning the galvanometer mirror 11 for x-direction scanning in the + x direction with the galvanometer mirror 19 for y-direction scanning fixed.

  Thus, by making it possible to simultaneously scan in the reverse direction on the same scanning line, it is possible to shorten the measurement time when the same scanning line is repeatedly scanned. In addition, it is frequently performed in OCT measurement to repeatedly scan the same scanning line. Specifically, image quality is improved by scanning the scanning line a plurality of times and forming one tomographic image based on a plurality of data obtained thereby.

  For example, in the case of measuring an object to be measured with movement such as the eye E, when the same scanning line is scanned a plurality of times, the position of the plurality of scans may be shifted due to the movement of the object to be measured. However, according to the optical image measurement device 1 according to this embodiment, the time required for scanning is halved, so that the possibility of being affected by the movement of the subject is reduced.

  In this embodiment, the signal light, the reference light, and the interference light are each divided into two. However, the signal light, the reference light, and the interference light may be divided into three or more. In that case, it is possible to further shorten the measurement time and the scanning time. However, since this increase in the number of divisions leads to complication of the device configuration, it is desirable to determine the number of divisions in consideration of both the device configuration and the measurement time. In this embodiment, the half mirror 4 serves as both the first dividing unit and the overlapping unit. However, the dividing unit and the overlapping unit may be separate members according to the configuration of the applied interference optical system. .

<Second Embodiment>
In the above embodiment, the configuration in which the same scanning line is simultaneously scanned in the reverse direction has been described. In this embodiment, a configuration in which different scanning lines are simultaneously scanned will be described. Note that description of components similar to those in the first embodiment may be omitted.

  A configuration example of the optical image measurement apparatus according to this embodiment is shown in FIG. The optical image measurement device 200 has substantially the same configuration as the optical image measurement device 1 of the first embodiment. The main difference between the two is that a galvano scanner 201 is provided in place of the galvanometer mirrors 11 and 19 of the first embodiment. The galvano scanner 201 scans the signal light generated by the half mirror 4 in an arbitrary direction on the xy plane. The galvano scanner 201 includes, for example, a galvano mirror that scans signal light in the x direction, a galvano mirror that scans in the y direction, and a mechanism that drives these independently. The galvano scanner 201 serves as both the “first scanning unit” and the “second scanning unit”. The configuration of the control system of the optical image measurement apparatus 200 is substantially the same as that of the first embodiment, and an example thereof is shown in FIG.

  According to such an optical image measurement device 200, the characteristic of the optical element 12, that is, the characteristic that the traveling directions of the two signal lights emitted from the optical element 12 are symmetric with respect to the optical axis, By providing the galvano scanner 201 for two-dimensionally scanning the signal light on the side, two different scanning lines can be scanned simultaneously.

  As a specific example, as shown in FIG. 7, the first signal light passing through the first signal light path A1 is scanned in the manner shown by reference numeral S11, and at the same time, the second signal light passing through the second signal light path A2 is used. Can be scanned in the manner indicated by reference numeral S21. Further, the first signal light passing through the first signal light path A1 is scanned in the manner indicated by reference numeral S12, and at the same time, the second signal light passing through the second signal light path A2 is scanned in the manner indicated by reference numeral S22. be able to. That is, in this embodiment, it is possible to irradiate two signal lights simultaneously at a point-symmetrical position around the origin (optical axis) of the xy plane. In the scanning mode shown in FIG. 7, the scanning in the x direction is performed in a state where the scanning in the y direction is fixed, and then the scanning in the x direction and the scanning in the y direction are performed simultaneously to switch the scanning lines. This is realized by performing scanning in the x direction with the scanning in the y direction fixed.

  Thus, the measurement time can be shortened by enabling scanning on a plurality of scanning lines simultaneously. Further, for example, when measuring a wide range of a measured object such as the eye E to be examined (for example, when forming a three-dimensional image), the time required for scanning the range is halved. The possibility of being affected by the movement of the specimen is reduced. In addition, if the deflection width of the galvano scanner is controlled so as to scan half of the scanning target region, it is possible to scan the entire region, so it is possible to use a low-cost galvanometer mirror with a small deflection width. .

  Note that the optical image measurement device 200 according to this embodiment can also be configured to divide the signal light, the reference light, and the interference light into three or more. In this embodiment, the half mirror 4 serves as both the first dividing unit and the overlapping unit. However, the dividing unit and the overlapping unit may be separate members according to the configuration of the applied interference optical system. .

<Third Embodiment>
In this embodiment, an optical image measurement device capable of measuring the polarization characteristics of an object to be measured will be described. Note that description of components similar to those in the above embodiment may be omitted.

A configuration example of the optical image measurement apparatus according to this embodiment is shown in FIG. The optical image measurement device 300 has substantially the same configuration as the optical image measurement device 1 of the first embodiment. The main differences between the two are:
Instead of the optical element 12 of the first embodiment, an optical element 301 whose first reflecting surface (surface that divides signal light) 301a (corresponding to the reflecting surface 12a in FIG. 2) functions as a polarizing beam splitter is used. Provided;
Half-wave plates (half-wave plates, λ / 2 plates) 302 and 303 are provided in the first signal light path A1 and the second signal light path A2, respectively;
Instead of the half mirror 18 of the first embodiment, a polarization beam splitter 304 is provided.

  The signal light generated by the half mirror 4 is divided into a P-polarized component and an S-polarized component by the reflecting surface 301 a of the optical element 301. The P-polarized component is a component of signal light that passes through the reflecting surface 301a and is guided to the first signal light path A1. The S-polarized component is a component of signal light reflected by the reflecting surface 301a, and is guided to the second signal light path A2.

  Each half-wave plate 302 and 303 is rotatable about the optical axis. The half-wave plate 302 changes the deflection direction of the P-polarized component incident on the first signal light path A1 in a direction corresponding to the rotation angle. The rotation angle of the half-wave plate 302 is determined so that, for example, the light reaching the polarization beam splitter 304 becomes P-polarized light.

  Further, the half-wave plate 303 changes the deflection direction of the S-polarized component incident on the second signal light path A2 in a direction corresponding to the rotation angle. The rotation angle of the half-wave plate 303 is determined so that, for example, the light reaching the polarization beam splitter 304 becomes S-polarized light.

  The polarization beam splitter 304 transmits the P-polarized light that passes through the first signal light path A1, and reflects the S-polarized light that passes through the second signal light path A2. Thereby, these two signal lights are combined. The combined signal light is applied to the fundus oculi Ef via the galvanometer mirror 19, the focusing lens 20 and the objective lens 21.

  The backscattered light of the signal light from the fundus oculi Ef reaches the half mirror 4 through the same path as the forward path and is superimposed on the reference light. The interference light generated thereby is dispersed by the spectroscopes 42 and 45 and detected by the CCD image sensors 43 and 46 as in the first embodiment.

  An example of the configuration of the control system of the optical image measurement device 300 is shown in FIG. The optical image measurement device 300 includes wave plate driving units 302A and 303A in addition to the configuration of the first embodiment (see FIG. 3). Wave plate driving units 302A and 303A rotate half-wave plates 302 and 303, respectively, independently.

  The image forming unit 110 receives electrical signals from the CCD image sensors 43 and 46 and generates images based on the electrical signals from the CCD image sensors 43 and 46, respectively. This image includes information representing the polarization characteristics of the fundus oculi Ef in the region irradiated with the signal light. Such OCT measurement is called polarization OCT, and is used, for example, to detect the amount of circularly polarized light of backscattered light from a measured object having birefringence and to obtain a birefringence distribution in the measured object. It is done.

  According to such an optical image measurement device 300, it is possible to reduce the time required for measuring the polarization characteristics of the object to be measured.

  In addition, although this embodiment demonstrated the structure based on 1st Embodiment, it is also possible to apply the structure based on 2nd Embodiment.

<Modification>
The configuration described above is merely an example for favorably implementing the present invention. Therefore, arbitrary modifications (omitted, replacement, addition, etc.) within the scope of the present invention can be made as appropriate.

  For example, in the above embodiment, the optical path length difference between the signal optical path and the reference optical path is changed by changing the optical path length of the reference light. However, the method for changing the optical path length difference is limited to this. It is not something. For example, the optical path length difference can be changed by arranging an optical path length changing member (for example, a corner cube) in the optical path of the signal light. Further, the optical path length difference can be changed by moving the apparatus optical system with respect to the object to be measured. 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).

  A computer program for realizing the above embodiment can be stored in any recording medium readable by a computer. Examples of the recording medium include a semiconductor memory, 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.), and the like. Can be used.

  It is also possible to transmit / receive this program through a network such as the Internet or a LAN.

DESCRIPTION OF SYMBOLS 1, 200, 300 Optical image measuring device 2 Light source 4 Half mirror 11, 19 Galvano mirror 12 Optical element 12A Erecting prism 12B Prism 18 Half mirror 20 Focusing lens 20A Focusing drive part 31 Half mirror 33, 36 Reference mirror 33A, 36A Reference drive unit 41 Half mirror 43, 46 CCD image sensor 100 Control unit 101 Main control unit 102 Storage unit 110 Image forming unit 120 Image processing unit 131 Display unit 132 Operation unit 201 Galvano scanner 301 Optical element 301a Reflecting surface (polarizing beam splitter) )
302, 303 Half-wave plate 302A, 303A Wave plate driving unit 304 Polarizing beam splitter E Eye Ef Fundus A, A1, A2 Signal path B, B1, B2 Reference path C, C1, C2 Interference path

Claims (8)

A first divider that divides light from the light source into signal light and reference light;
A second dividing unit that divides the optical path of the signal light into a plurality of signal optical paths having different optical path lengths;
A combining unit that combines a plurality of signal lights via the plurality of signal light paths;
A third dividing unit that divides the optical path of the reference light into a plurality of reference optical paths having optical path lengths corresponding to the plurality of signal optical paths;
A superimposing unit that generates interference light by superimposing the return light from the measurement object of the plurality of signal lights synthesized by the synthesizing unit and the plurality of reference lights via the plurality of reference optical paths;
A fourth dividing unit for dividing the optical path of the interference light into a plurality of interference optical paths;
A detection unit that is provided in each of the plurality of interference optical paths and detects the interference light guided through the interference optical path;
A scanning unit that scans the signal light;
A forming unit that forms a plurality of tomographic images of the object to be measured based on detection results of the interference light obtained by superimposing the scanned return light of the signal light on the reference light. And an optical image measurement device.   The optical image measurement device according to claim 1, wherein the second dividing unit divides the signal light generated by the first dividing unit into two signal lights.   The optical image measurement device according to claim 2, wherein the traveling directions of the two signal lights are symmetric with respect to the optical axis.   The optical image measurement device according to claim 3, wherein the second division unit is an optical element formed by connecting a prism to a first reflection surface of an erecting prism. The scanning unit
A first scanning unit that scans the signal light generated by the first dividing unit in a predetermined direction;
The optical image according to any one of claims 2 to 4, further comprising: a second scanning unit that scans the signal light combined by the combining unit in a direction orthogonal to the predetermined direction. Measuring device. The scanning unit
A first scanning unit that scans the signal light generated by the first dividing unit in a predetermined direction;
The optical image measurement device according to claim 2, further comprising: a second scanning unit that scans the signal light in a direction orthogonal to the predetermined direction.   5. The light according to claim 2, wherein the two signal lights are a P-polarized component and an S-polarized component of the signal light generated by the first dividing unit. Image measuring device. A half-wave plate provided in the optical path of each of the P-polarized component and the S-polarized component;
And a mechanism for rotating the half-wave plate,
The optical image measurement device according to claim 7, wherein the third division unit is a polarization beam splitter.

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