Fundus observation device

A fundus observation device is provided capable of capturing both images of the surface of the fundus oculi and tomographic images of the fundus oculi, and capable of preventing alignment indicators from being reflected in the image of the fundus oculi. Image forming part 220 operates to form surface images based on results of detecting the reflection light by the fundus oculi Ef of the illumination light obtained from a fundus camera unit 1A, and operates to form tomographic images based on results of detecting interference light LC by the OCT unit 150. The fundus camera unit comprises alignment optical systems 110A and 190A, which project an alignment indicator. Detection timing controlling part 210B controls a fundus camera unit 1A and makes it detect the illumination light substantially simultaneously with detection of the interference light. Before the interference light LC and illumination light are substantially simultaneously detected, the alignment controlling part 210 controls the alignment optical system 110A and 190A and terminates the projection of the alignment light indicator. Correction processing part 225 corrects the image position of tomographic images using the surface images obtained substantially simultaneously.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fundus observation device, for observing the state of the fundus oculi of an eye.

2. Description of the Related Art

As a fundus observation device, conventionally a fundus camera has been widely used.FIG. 13shows one example of the appearance of a conventional fundus camera in general, andFIG. 14shows one example of an optical system composition to be internally accommodated therein (e.g. JP Patent laid-open No. 2004-350849). Furthermore, “observation” is intended to include at least a case in which produced fundus images are observed (fundus observations with the naked eye may be included).

First, referring toFIG. 13, an explanation is made regarding the appearance of a conventional fundus camera1000. This fundus camera1000is provided with a platform3mounted on a base2slidably in the front and rear, right and left (horizontal direction) directions. On this platform3, an operation panel3aand a control lever4are installed for an examiner to conduct various operations.

The examiner may place the platform3on the base2to be moved 3-dimensionally by operating the control lever4. On the top of the control lever4, an operation button4ais installed to be pressed down to obtain fundus oculi images.

On the base2, a post5is installed standing upwards. On the post5, a jaw rest6where the jaw of a patient is to be rested and an external fixation lamp7as a light source for fixing an eye E are provided.

On the platform3, a main body part8is installed to accommodate various optical systems or control systems of the fundus camera1000. Furthermore, the control system may be installed inside the base2or the platform3, etc., or in an external device such as a computer, etc. connected to the fundus camera1000.

On the side of the eye E of the main body part8(the left side of the page inFIG. 13), an objective lens part8adisposed opposite the eye E is installed. Also, on the examiner's side of the main body part8(the right side of the page inFIG. 13), an objective lens part8bfor observing the fundus oculi of the eye E with the naked is installed.

Furthermore, connected to the main body part8is a still camera9for producing a still image of a fundus oculi of the eye E and an imaging device10such as a TV camera, etc. for producing still images or moving images of a fundus oculi. The still camera9and the imaging device10are formed removably with respect to the main body part8.

As a still camera9, in accordance with various conditions such as the purpose of an examination or the saving method of produced images, etc., a digital camera equipped with imaging elements such as CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor), a film camera, and an instant camera, etc. may interchangeably be used when it is appropriate. The main body part8is equipped with a mounting part8cfor interchangeably mounting such a still camera9.

If the still camera9or the imaging device10is for taking digital images, the image data of the produced fundus image may be sent to a device such as a computer, etc. connected to the fundus camera1000and be observed as a fundus image by being displayed on the display. Also, the image data can be sent to an image storing device connected to the fundus camera1000to compile a database and be used as electronic data for creating medical charts, etc.

Furthermore, on the examiner's side of the main body part8, a touch panel monitor11is installed. On this touch panel monitor11, fundus images of the eye E created based on the video signals output from the still camera9(a digital method thereof) or the imaging device10are displayed. Moreover, on the touch panel monitor11, the xy coordinate system with the center of the screen as the origin is displayed overlapped with a fundus image. When the screen is touched by the examiner, the coordinate value corresponding to the touched position is displayed.

Next, referring toFIG. 14, a composition of an optical system of the fundus camera1000is described. The fundus camera1000is provided with an illuminating optical system100to light the fundus oculi Ef of an eye E, an imaging optical system120to guide the fundus reflection light of the illumination light to the eyepiece part8b, a still camera9, and an imaging device10.

The illuminating optical system100comprises: an observation light source101, a condenser lens102, an imaging light source103, a condenser lens104, an exciter filter105and106, a ring transparent plate107, a mirror108, a liquid crystal display (LCD)109, an alignment member110, a relay lens111, an aperture mirror112, and an objective lens113.

The observation light source101consists of a halogen lamp, etc. and emits continuous light for observing the fundus. The condenser lens102is an optical element that converges the continuous light (observation illumination light) emitted by the observation light source101and substantially evenly irradiates the observation illumination light to the fundus oculi.

The imaging light source103consists of a xenon lamp, etc. to be flashed when producing fundus oculi Ef images. The condenser lens104is an optical element that converges the flash light (imaging illumination light) emitted by the imaging light source103and irradiates the fundus oculi Ef evenly with the imaging illumination light.

The exciter filters105and106are the filters to be used when fluorography of images of a fundus oculi Ef takes a place. The exciter filters105and106respectively can be inserted and retracted on the optical path by a drive mechanism such as a solenoid, etc. The exciter filter105is disposed on the optical path in the event of FAG (fluorescein angiography). Whereas, the exciter filter106is disposed on the optical path in the event of ICG (indocyanine green angiography). Furthermore, when color images are being obtained, both exciter filters105and106are retracted from the optical path.

The ring transparent plate107is disposed in a conjugating location with a pupil of the eye E, and is equipped with a ring transparent part107ataking an optical axis of the illuminating optical system100as a center. The mirror108reflects the illumination light emitted by the observation light source101or by the imaging light source103in the direction of the optical axis of the imaging optical system120. The LCD109displays a fixation target (not illustrated) for fixing the eye E.

An alignment member110is detachably built into the optical path of an illuminating optical system100manually. A first alignment optical system110A having an optical path perpendicular to the optical path of the illuminating optical system100is built into the insert position of this alignment member110. This first alignment optical system110A is an optical system for projecting a split indicator used for the diopter scale (focus) adjustment for the fundus oculi Ef onto an eye (e.g., see JP Patent laid-open No. Hei 5-95906).

One example of the configuration of the first alignment optical system110A is shown inFIG. 15.FIG. 15Ais a side view of the first alignment optical system110A,FIG. 15Bis a side view of the alignment member110, andFIG. 15Cis a top view of the alignment member110.

The alignment member110has an inclined surface110sat the end on the side to be inserted into the optical path of the illuminating optical system100as shown inFIGS. 15Band C. This inclined surface110sacts as a reflection mirror for reflecting light from the first alignment optical system110A.

The first alignment optical system110A comprises a light source110a, a slit110b, a collective lens110c, a split prism110d, a reflection mirror110e, and a collective lens110fas well as this alignment member110as shown inFIG. 15(A). The light source110amay, for example, be a light-emitting diode (LED) for emitting light such as a near-infrared light (first alignment light). For example, a rectangle-shaped opening (slit) may be formed on the slit110b.

The first alignment light emitted from the light source110apasses through the opening of the slit110b, is collected by the collective lens110c, and is then injected into the split prism110d. The split prism110dsplits this first alignment light into two light fluxes. The first alignment light having been split into two is respectively reflected by the reflection mirror110cand focused on the inclined surface110sof the alignment member110by the collective lens110f. Then, the first alignment light is reflected by the inclined surface110s, combined with the optical path of the illuminating optical system100, and injected into the eye E via a relay lens111, an aperture mirror112, and an objective lens113. These two first alignment lights are designed to coincide with each other on the focus surface.

The first alignment light injected into the eye E is reflected by the fundus oculi Ef, received at the image pick up element10avia the imaging optical system120, and then displayed on a touch panel monitor11(or an external display). The displaying feature of this first alignment light is shown inFIG. 17.

The symbol110′ inFIG. 17indicates the shadow of an alignment member110. In addition, the symbols L1and L2inFIG. 17indicate bright lines which are based on the first alignment light reflected by the inclined surface110sof the alignment member110(alignment bright lines). This pair of alignment bright lines L1and L2configures the split indicator described above.

When the fundus oculi Ef does not coincide with the focus surface, the alignment bright lines L1and L2are displayed with misaligned each other, i.e. they are misaligned laterally on the paper as shown inFIG. 17A. On the other hand, when the fundus oculi Ef coincides with the focus surface, the alignment bright lines L1and L2are displayed in the state in which the crosswise positions coincide with each other as shown inFIG. 17B. An examiner adjusts the focus such that the crosswise positions of the alignment bright lines L1and L2coincide with each other.

The aperture mirror112is an optical element to combine an optical axis of the illuminating optical system100and an optical axis of the imaging optical system120. In the center region of the aperture mirror112an aperture part112ais opened. The light axis of the illuminating optical system100and the light axis of the imaging optical system120arc to be crossed at a substantially central location of this aperture part112a. The objective lens113is installed in the objective lens part8aof the main body part8.

The illuminating optical system100having such a composition illuminates a fundus oculi Ef in the following manner. First, the observation illumination light is emitted when the observation light source101is lit during fundus observation. This observation illumination light irradiates the ring transparent plate107through the condenser lenses102and104. (The exciter filters105and106are retracted from the optical path.) The light passed through the ring transparent part107aof the ring transparent plate107is reflected by the mirror108and is reflected along the optical axial direction of the imaging optical system120due to the aperture mirror112through the LCD109and the relay lens111. The alignment member110has been manually retracted from the optical path in advance. The observing illumination light reflected by the aperture mirror112advances in the optical axial direction of the imaging optical system120and is converged by the objective lens113, to be made incident onto the eye E, and illuminates the fundus oculi Ef.

Then, the ring transparent plate107is disposed in a conjugating location with the pupil of the eye E, and on the pupil a ring shaped image of the entering observation illumination light is formed. The fundus reflection light of the entered observation illumination light is to be emitted from the eye E through a central dark part of the ring image on the pupil. As described, it is to protect the effect of observing illumination light entering the eye E with respect to the fundus reflection light of the observing illumination light.

On the other hand, when imaging the fundus oculi Ef, flush light is emitted from the imaging light source103and the imaging illumination light is irradiated onto the fundus oculi Ef through the same path. In the event of photofluographing, either the exciter filter105or the exciter filter106is disposed selectively on the optical path depending on whether FAG imaging or ICG imaging is carried out. Furthermore, when imaging the fundus oculi Ef other than photofluography, or when observing the fundus oculi Ef, the exciter filter105and106are retracted from the optical path.

Whereas, imaging optical system120comprises: an objective lens113, an aperture mirror112(an aperture part112athereof), an imaging diaphragm121, a barrier filter122and123, a focusing lens124, half mirror190, a relay lens125, an imaging lens126, a quick return mirror127and an imaging media9a. Herein, the imaging media9ais an arbitrary imaging media (image pick-up elements such as CCD, camera film, instant film, etc.) used for a still camera9.

The fundus reflection light of the illumination light, emitted through the central dark part of the ring shaped image formed on the pupil from the eye E, enters the imaging diaphragm121through the aperture part112aof the aperture mirror112. The aperture mirror112reflects cornea reflection light of the illumination light and acts so as not to mix the cornea reflection light into the fundus reflection light made incident onto the imaging diaphragm121. As a result, the generation of flare on the observation images and/or produced images is prevented.

The imaging diaphragm121is a plate shaped member at which plural circular light transparent parts of different sizes are formed. The plural light transparent parts constitute different diaphragms with different diaphragm values (F value), and are to be disposed alternatively on the optical path by a drive mechanism (not illustrated herein).

The barrier filters122and123can be inserted and retracted on the optical path by a drive mechanism such as a solenoid, etc. In the event of FAG imaging, the barrier filter122is disposed on the optical path while in the event of ICG imaging the barrier filter123is inserted onto the optical path. Furthermore, when imaging the fundus oculi Ef other than photofluography, or when observing the fundus oculi Ef, the barrier filters122and123are to be retracted from the optical path.

The focusing lens124is enabled to move in the light axial direction of the imaging optical system120by a drive mechanism (not illustrated herein). This movement of the focusing lens124allows to change the magnifying ratio in observation and the magnifying ratio in imaging, and to focus images of a fundus oculi (focus adjustment). The imaging lens126is a lens to focus the fundus reflection light from an eye E on the imaging media9a.

The quick return mirror127is disposed rotatably around a rotary shaft127aby a drive mechanism not illustrated herein. In the event of imaging a fundus oculi Ef with the still camera9, the fundus reflection light is supposed to be guided to the imaging media9aby springing up the quick return mirror127that is obliquely mounted on the optical path. Whereas, in the event of imaging a fundus oculi with an imaging device10or of observing the fundus oculi with the naked eye of the examiner, the quick return mirror127is to be obliquely mounted on the optical path to upwardly reflect the fundus reflection light.

The imaging optical system120is further provided, for guiding the fundus reflection light reflected by the quick return mirror127, with a field lens128, a switching mirror129, an eyepiece130, a relay lens131, a reflection mirror132, an imaging lens133and an image pick up element10a. The image pick up element10ais an image pick up element such as CCD, etc. installed internally in the imaging device10. On the touch panel monitor11a fundus oculi image Ef′ imaged by the image pick up element10ais be displayed.

The switching mirror129is to be rotatable around the rotary shaft129aas well as the quick return mirror127. This switching mirror129is obliquely disposed on the optical path during observation with the naked eye and guides reflected light on the fundus oculi to the eyepiece130.

Also, when a fundus image is formed by the imaging device10, the switching mirror129is retracted from the optical path, and the fundus reflection light is guided toward an image pick-up element10a. In this case, the fundus reflection light is directed toward a relay lens131, is reflected by the mirror132, and is focused on the image pick-up element10aby the imaging lens133.

A half mirror190is provided on the optical path between the focusing lens124and the relay lens125while the half mirror190is inclined. This half mirror190acts to combine the path of the second alignment optical system190A shown inFIG. 16Awith the path of the imaging optical system120(photographing optical path). This second alignment optical system190A is an optical system for projecting a bright point (alignment bright point) used for the position adjustment (particularly adjustment of the working distance) of an optical system in relation to an eye E onto an eye E (e.g., see JP Patent laid-open No. Hei11-4808).

The second alignment optical system190A comprises a light source190aconsisting of, for example, LED for emitting light such as a near-infrared light (second alignment light), a light guide190b, a reflection mirror190c, a two-hole aperture190d, and a relay lens190eas well as the half mirror190.

The two-hole aperture190dhas two holes190d1and190d2as shown inFIG. 16B. The holes190d1and190d2are formed on, for example, the symmetric position for the center position190d3of the circular two-hole aperture190d. The two-hole aperture190dis arranged so that this center position190d3is located on the optical axis of the second alignment optical system190A.

The second alignment light ejected from an ejection end190β of the light guide190bis reflected by the reflection mirror190cand guided to the holes190d1and d2of the two-hole aperture190drespectively. The alignment lights that have passed the hole190d1and190d2are guided to the aperture mirror112by passing through the relay lens190eand by being reflected by the half mirror190. Then, the relay lens190efocuses the image of the ejection end190β of the light guide190bon the center position of the hole112aof the aperture mirror112(the position on the optical axis of the imaging optical system120). The second alignment light that has passed through the hole112aof the aperture mirror112is projected onto the cornea of the eye E via objective lens113.

Herein, suppose that the positional relationship between the eye E and a fundus oculi camera1000(objective lens113) is appropriate, i.e. that the distance from the eye E to the fundus oculi camera1000(working distance) is appropriate, and that the optical axis of the optical system of the fundus oculi camera1000and the eye axis of the eye E (top position of the cornea) are (almost) coincident with each other. In this case, two light fluxes (alignment light fluxes) formed by the two-hole aperture190dare projected onto the eye E so as to be focused on the intermediate position between the top of the cornea and the center of corneal curvature. Meanwhile, when the working distance W from the eye E to the device main body is not appropriate, two alignment light fluxes will be separately projected onto the eye E, respectively.

The corneal reflection lights of the two alignment light fluxes (the second alignment light) are received by the image pick up element10avia the imaging optical system120. The photographed images by the image pick up element10aare displayed on the touch panel monitor11(or an external display). The displaying feature of this second alignment light is shown inFIG. 17.

The symbol S inFIG. 17indicates the scale having bracket shape, and symbols P1and P2indicate the light received image of two alignment light fluxes (alignment bright points). The scale S is displayed on the touch panel monitor11so that its center position coincides with the optical axis of the imaging optical system120.

When the positional relationship between the eye E and the fundus oculi camera1000is not appropriate, the alignment bright points P1and P2are displayed in the state of being separated from each other as shown inFIG. 17A. Particularly, when the positions of the eye E and the fundus oculi camera1000are out of alignment together in the up-and-down direction or the right-and-left direction, the alignment bright points P1and P2are displayed at the position, in which they are out of alignment to the scale S in the up-and-down direction or the right-and-left direction.

On the other hand, when the positional relationship between the eye E and the fundus oculi camera1000is appropriate, the alignment bright points P1and P2are displayed in the scale S in the state of being overlapped with each other as shown inFIG. 17B. An examiner adjusts the positional relationship between the eye E and the fundus oculi camera1000such that the alignment bright points P1and P2overlap each other and are displayed on the scale S.

Such a fundus camera1000is a fundus observation device to be used for observing the state of the surface of a fundus oculi Ef, that is, the retina. In other words, a fundus camera1000is a fundus observation device to obtain a 2-dimensional fundus oculi image when it sees the fundus oculi Ef from the corneal direction onto the eye E. On the other hand, in the deep layer of retina tissues such as the choroidea or sclera exist, technology for observing these deep layer tissues has been desired, but, in recent years, devices for observing these deep layer tissues have been practically implemented (e.g. JP Patent laid-open No. 2003-000543, JP Patent laid-open No. 2005-241464).

The fundus observation device disclosed in JP Patent laid-open No. 2003-000543 and JP Patent laid-open No. 2005-241464 are devices to which so called OCT (Optical Coherence Tomography) technology is applied. With such fundus observation devices, low coherence light is split into two, one of which (signal light) is guided to a fundus oculi and the other one (reference light) is guided to a given reference object, and this is a device to form tomographic images of the surface and the deep layer tissue of a fundus oculi,and to form the 3-dimensional image from the tomographic images, by detecting and analyzing the interference light obtained by overlaying the signal light that has reached the fundus oculi and the reference light that has been reflected by the reference object. Such devices are in general called a Fourier domain OCT.

For such an optical image measuring device, the focus and position of the optical image measuring device in relation to the eye should be adjusted by using alignment indicators such as the same alignment bright line and alignment bright point as the fundus oculi camera1000described above.

In addition, the present inventors proposed a fundus observation device capable of capturing both images of the surface and tomographic images of the fundus oculi (e.g., see JP Patent Application No. 2006-003065 and JP Patent Application No. 2006-003878), but there was a disadvantage in that when an alignment indicator is projected onto the eye during capturing images of the surface of the fundus oculi, the image of the projected region cannot be observed. Particularly, as a configuration described in Patent Application No. 2006-003878, in the case of using an image of the surface of the fundus oculi to correct the position of a tomographic image, and when using an image of the surface of the fundus oculi into which an alignment indicator is reflected, correction may not be accomplished adequately.

The present invention is designed to solve such disadvantages and therefore is intended to provide a fundus observation device capable of capturing both images of the surface of the fundus oculi and tomographic images of the fundus oculi, and capable of preventing alignment indicators from being reflected in the image of the fundus oculi.

Particularly, the present invention is intended to provide technology that prevents alignment indicators from being reflected into the image of the surface of the fundus oculi, while the image is used for correcting the position of tomographic images of the fundus oculi.

SUMMARY OF THE INVENTION

The first aspect of the present embodiment is constructed as follows: a fundus observation device comprising: a first image forming part having an illuminating optical system configured to emit illumination light onto fundus oculi of an eye and an imaging optical system configured to detect the illumination light having reached said fundus oculi by the first detection part, wherein the first image forming part forms a 2-dimensional image of the surface of said fundus oculi based on the detection results by said first detection part; a second image forming part having a light source configured to emit low coherent light with a wavelength which is different from said illumination light; an interference optical generating part configured to split said emitted low coherent light into the signal light directed towards said fundus oculi and the reference light directed towards a reference object and to generate interference light by superposing the signal light having reached said fundus oculi and the reference light having reached said reference object; and a second detection part configured to detect said interference light generated, wherein said second image forming part forms tomographic images of said fundus oculi based on the detected results by said second detection part; an optical path combination and separation part configured to combine the photographing optical path formed by said imaging optical system and the optical path of a signal light directed toward said fundus oculi so as to illuminate said signal light onto said fundus oculi through said photographing optical path, and configured to separate said photographing optical path from the optical path of the signal light toward said fundus oculi so as to superpose said signal light on said reference light by said interference optical generating part; an alignment optical system configured to project an alignment indicator on said eye to preliminarily adjust a device for said eye; and a controlling part configured to control said alignment optical system to terminate projection of said alignment indicator on said eye before said illumination light is detected by said first detection part.

The first aspect of the present embodiment is constructed as follows: a first image forming part having an illuminating optical system configured to emit illumination light onto fundus oculi of an eye and a imaging optical system configured to detect the illumination light having reached said fundus oculi by the first detection part, wherein the first image forming part forms a 2-dimensional image of the surface of said fundus oculi based on the detection results by said first detection part; a second image forming part having a light source configured to emit light with a wavelength which is different from said illumination light; an interference optical generating part configured to split said light emitted from said light source into the signal light directed towards said fundus oculi and the reference light directed towards a reference object and to generate interference light by superposing the signal light having reached said fundus oculi and the reference light having reached said reference object; and a second detection part configured to detect said interference light generated, wherein said second image forming part forms tomographic images of said fundus oculi based on the detected results by said second detection part; an optical path combination and separation part configured to combine the photographing optical path formed by said imaging optical system and the optical path of a signal light directed toward said fundus oculi and so as to illuminate said signal light onto said fundus oculi through said photographing optical path, and configured to separate said photographing optical path from the optical path of the signal light having reached said fundus oculi so as to superpose said signal light on said reference light by said interference optical generating part; an alignment optical system configured to project an alignment indicator on said eye to preliminarily adjust a device for said eye; a detection timing controlling part configured to cause said first detection part to detect said illumination light substantially simultaneously with detection of said interference light by said second detection part; a controlling part configured to control said alignment optical system to terminate projection of said alignment indicator on said eye before said detection by said first detection part; and a correction part configured to correct the image position of the tomographic image of said fundus oculi according to a 2-dimensional image of the surface of said fundus oculi.

DETAILED DESCRIPTION OF THE REFERENCE EMBODIMENTS

One example of favorable embodiments of a fundus observation device related to the present invention is described in detail referring to figures. Furthermore, for constitutional parts that are the same as conventional ones, the same symbols used inFIG. 13andFIG. 14are used.

In the present invention, “alignment indicator” shall refer to an indicator projected onto the eye for the task of the fundus observation device adjusting in relation to the eye prior to photographing a two-dimensional image of the surface of the fundus oculi or measuring a tomographic image. This alignment indicator has, for example, a split indicator used in the focus adjustment work to the eye (alignment bright line), an alignment bright point used in the adjustment work to the eye (work for matching the eye axis (top position of the cornea) of the eye and the optical axis of the optical system) and so on (described above).

First, by referring toFIG. 1throughFIG. 6, the constitution of the fundus observation device related to the present invention is described.FIG. 1shows the entire constitution of the fundus observation device I related to the present invention.FIG. 2shows a constitution of a scanning unit141in a fundus camera unit IA.FIG. 3shows a constitution of an OCT unit150.FIG. 4shows a hardware configuration of an arithmetic and control unit200.FIG. 5andFIG. 6show a configuration of a control system of the fundus observation device1.

The Entire Constitution

As shown inFIG. 1, the fundus observation device1is comprised of a fundus camera unit1A that functions as a fundus camera, an OCT unit150accommodating the optical system of an optical image measuring device (OCT device), and an arithmetic and control unit200that executes various arithmetic processes and control processes, etc.

The fundus observation device1is a component of one example of the “the first image forming part” with the arithmetic and control unit200. The OCT unit150is a component of one example of the “the second image forming part” with the arithmetic and control unit200. Further, this “the second image forming part” also includes each optical element through the signal light such as a scanning unit141provided in the fundus camera unit1A, etc.

To the OCT unit150, one end of a connection line152is attached. To the other end of this connection line152, a connector part151is attached. This connector part151is attached to a mounting part8cshown inFIG. 13. Furthermore, a conductive optical fiber runs through the inside of the connection line152. The OCT unit150and the fundus camera unit1A are optically connected through the connection line152. The constitution details of the OCT unit150are to be described later referring toFIG. 3.

Constitution of Fundus Camera Unit

The fundus camera unit1A has substantially the same appearance as the conventional fundus camera1000shown inFIG. 13. Furthermore, as in the conventional optical system shown inFIG. 14, the fundus camera unit1A is provided with an illuminating optical system100to light a fundus oculi Ef of an eye E, and an imaging optical system120for guiding the fundus reflection light of the illumination light to an imaging device10.

In addition, although the details are to be described later, an imaging device10in an imaging optical system120of the present embodiment is used for detecting the illumination light with a wavelength in the near-infrared region. Furthermore, in this imaging optical system120, an imaging device12for detecting the illumination light with a wavelength in the visible region is provided separately. In addition, in this imaging optical system120, it can guide the signal light from the OCT unit150to the fundus oculi Ef and the signal light through the fundus oculi Ef to the OCT unit150.

Also, the illuminating optical system100is comprised as in conventional ones including: an observation light source101, a condenser lens102, an imaging light source103, a condenser lens104, an exciter filter105and106, a ring transparent plate107, a mirror108, an LCD109, an alignment member110, a relay lens111, an aperture mirror112, and an objective lens113.

The observation light source101, for example, emits the illumination light of a wavelength in the visible region included within about 400 nm to 700 nm. Furthermore, the imaging light source103, for example, emits the illumination light of a wavelength in the near-infrared region included within about 700 nm to 800 nm. The near-infrared light emitted from this imaging light source103is provided shorter than the wavelength of the light used by the OCT unit150(to be described later).

The alignment member110has an inclined surface110sat the end which is on the side to be inserted to the optical path of the illuminating optical system100as shown inFIG. 15BandFIG. 15C. This inclined surface110sacts as a reflection mirror for reflecting light from the first alignment optical system110A shown inFIG. 15A(first alignment light). Incidentally, the inclined surface110shas an area sufficiently small compared to the cross-section area of the illuminating light at its insert position. In addition, the alignment member110inserted onto the optical path is positioned such that the center position of the inclined surface110sis on the optical axis of the illuminating optical system100.

This first alignment optical system110A is an optical system for projecting split indicators used for the focus adjustment to the fundus oculi Ef (alignment bright lines L1and L2; seeFIG. 17) onto an eye E.

The first alignment optical system110A comprises an alignment member110, a light source110afor emitting the first alignment light (e.g., near-infrared light with the wavelength of approximately 700 nm to 800 nm), a slit110b, a collective lens110c, a split prism110d, a reflection mirror110e, and a collective lens110f, as shown inFIG. 15A.

The split indicators (referred to as “L1” and “L2”) are indicators equivalent to one example of the “first alignment indicator” relating to the present invention. In addition, the light source110ais equivalent to one example of the “first alignment light source” relating to the present invention, and (the inclined surface110sof) the alignment member110is equivalent to one example of the “first optical path combination part” relating to the present invention.

The alignment member110is inserted in and/or detached from the optical path by being moved using the following alignment drive mechanism110gto be described. As a moving feature of the alignment member110, the alignment member110may, for example, be moved in parallel in the direction perpendicular to the optical path, or be moved rotationally centering around the end on the side opposite to the inclined surface110s. Incidentally, it is also possible to configure the alignment member110to be inserted in and/or detached from the optical path by configuring the alignment optical system110A in an integrated fashion as a unit and by moving this unit.

At the same time, the imaging optical system120comprises: an objective lens113, an aperture mirror112(aperture part112athereof), an imaging diaphragm121, a barrier filter122and123, a focusing lens124, a half mirror190, a relay lens125, an imaging lens126, a dichroic mirror134, a field lens128, a half mirror135, a relay lens131, a dichroic mirror136, an imaging lens133, an imaging device10(an image pick-up element10a), a reflection mirror137, an imaging lens138, an imaging device12(an image pick-up element12a), and a lens139and LCD (Liquid crystal Display)140.

Focusing lens124is designed to move in the direction of the optical axis of the imaging optical system120in response to, for example, operations for a focusing operating part such as a knob (focusing knob) or the like provided on the package of the fundus camera unit1A. Incidentally, a mechanism for moving the focusing lens124may consist of only a mechanical mechanism such as a gear, or may be a configuration to which an electrical member such as a motor would be added.

The half mirror190acts to combine the optical path of the second alignment optical system190A shown inFIG. 16Awith the optical path of the imaging optical system120(photographing optical path). This second alignment optical system190A comprises a half mirror190, a light source190afor emitting a second alignment light (e.g., near-infrared light with the wavelength of approximately 700 nm to 800 nm), a light guide190b, a reflection mirror190c, a two-hole aperture190d, and a relay lens190e. The two-hole aperture190dhas two holes190d1and190d2as shown inFIG. 16B.

This second alignment optical system190A is an optical system for projecting a pair of alignment bright points P1and P2(seeFIG. 17) onto an eye E, the pair being used in the adjustment work of the position of the device to the eye, that is, in the work for matching the optical axes of the illuminating optical system100and the imaging optical system120to the eye axis (top position of the cornea) of the eye E.

The alignment bright points P1and P2are the indicators equivalent to one example of the “second alignment indicators” relating to the present invention. In addition, the light source190ais equivalent to one example of the “second alignment light source” relating to the present invention, and the half mirror190is equivalent to one example of the “second optical path combination part” relating to the present invention.

The imaging optical system120related to the present embodiment is different from the conventional imaging optical system120shown inFIG. 14in that the dichroic mirror134, the half mirror135, a dichroic mirror136, the reflection mirror137, the imaging lens138, and the lens139and LCD140are provided.

The dichroic mirror134reflects the fundus reflection light of the illumination light (with a wavelength included within about 400 nm to 800 nm) from the illuminating optical system100, and transmits the signal light LS (with a wavelength included within about 800 nm to 900 nm; to be described later) from the OCT unit150. This dichroic mirror134is the equivalent of one example of the “optical combination and separation part” relating to the present invention.

Furthermore, the dichroic mirror136transmits the illumination light with a wavelength in the visible region from the illuminating optical system100(the visible light of a wavelength within about 400 nm to 700 nm for emitting from the observation light source101), and reflects the illumination light with a wavelength in the near-infrared region (the near-infrared light of a wavelength within about 700 nm to 800 nm for emitting from the imaging light source103). Therefore, illumination light with the wavelength in the visible region will be guided to the imaging device12and illumination light with the wavelength in the near-infrared region will be guided to the imaging device10.

Incidentally, the first and second alignment lights passing through the eye E will be reflected by a dichroic mirror134and a dichroic mirror136so as to be guided to the imaging device10.

The LCD140shows an internal fixation target, etc. The light from this LCD140is reflected by the half mirror135after being converged by the lens139, and reflects the dichroic mirror136through the field lens128. Further, it enters the eye E passing through the imaging lens126, the relay lens125, the half mirror190, the focusing lens124, the aperture mirror112(aperture part112athereof), the objective lens113, etc. As a result, an internal fixation target, etc. is displayed in a fundus oculi Ef of an eye E.

The image pick up element10ais the image pick up element of CCD and CMOS, etc. installed internally in an imaging device10such as a TV camera, and is particularly used for detecting light of a wavelength in the near-infrared region (that is, the imaging device10is the infrared TV camera for detecting near-infrared light). The imaging device10outputs the image signal as a result of detecting near-infrared light. A touch panel monitor11displays a 2-dimensional image (fundus image Ef′) of the surface of the fundus oculi Ef based on this image signal. Also, this image signal is sent to the arithmetic and control unit200, and the fundus oculi image is displayed on the display (to be described later). Furthermore, when the fundus oculi are being imaged by this imaging device10, the illumination light emitted from the imaging light source103of the illuminating optical system100, having a wavelength in the near-infrared region, is used. This (image pick up element10aof) imaging device10is equivalent to one example of “the first detection part” relating to the present invention.

Also, the image pick up element12ais the image pick up element of CCD and CMOS, etc. installed internally in an imaging device12such as a TV camera, and is particularly used for detecting light of a wavelength in the visible region (that is, the imaging device12is the TV camera for detecting visible light). The imaging device12outputs the image signal as a result of detecting visible light. A touch panel monitor11displays a 2-dimensional image (fundus image Ef′) of the surface of the fundus oculi Ef based on this image signal. Also, this image signal is sent to the arithmetic and control unit200, and the fundus oculi image is displayed on the display (to be described later). Furthermore, when the fundus oculi are being imaged by this imaging device12, the illumination light emitted from the observation light source101of the illuminating optical system100, having a wavelength in the near-infrared region, is used. This (image pick up element12aof) imaging device12is equivalent to one example of “the first detection part” relating to the present invention when the light having a wavelength in the near-infrared region is used as the first and second alignment light.

Furthermore, the imaging optical system120of the present embodiment is provided with a scanning unit141and a lens142. The scanning unit141is equipped with a constitution to scan the light output (signal light LS; to be described later) from the OCT unit150on a fundus oculi Ef.

The lens142incidents the signal light LS from the OCT unit150in the form of parallel light flux onto the scanning unit141. Furthermore, the lens142acts so as to converge the fundus reflection light of the signal light LS that has reached through the scanning unit141.

InFIG. 2, one example of a concrete constitution of the scanning unit141is shown. The scanning unit141is comprised including Galvano mirrors141A,141B, and reflection mirrors141C,141D.

The Galvano mirrors141A and141B are to be rotatable centering around rotary shafts141aand141brespectively. The rotary shaft141aand141bare arranged perpendicular to each other. InFIG. 2, the rotary shaft141aof the Galvano mirror141A is arranged parallel to the paper face, while the rotary shaft141bof the Galvano mirror141B is arranged perpendicular to the paper face. That is, the Galvano mirror141B is to be rotatable in the directions indicated by an arrow pointing in both directions inFIG. 2, while the Galvano mirror141A is to be rotatable in the directions perpendicular to the arrow pointing in both directions. As a result, this pair of Galvano mirrors141A and141B act so that the reflecting direction of the signal light LS changes to a direction perpendicular to each other. Furthermore, the rotary movement of the Galvano mirror141A and141B respectively is driven by a drive mechanism (seeFIG. 5) to be described later.

The signal light LS reflected by the Galvano mirrors141A and141B is to be reflected by reflection mirrors141C and141D, and is to advance in the same direction as having entered into the Galvano mirror141A

As described previously, a conductive optical fiber152aruns inside the connection line152, and the end face152bof the optical fiber152ais arranged opposing the lens142. The signal light LS emitted from this end face152badvances while gradually expanding its beam diameter toward the lens142until being converged to a parallel light flux by this lens142. On the contrary, the fundus reflection light of the signal light LS is converged toward the end face152bby this lens142.

Constitution of OCT Unit

Next, referring toFIG. 3, the constitution of an OCT unit150is described. The OCT unit150shown inFIG. 3has substantially the same optical system as a conventional optical image measuring device, and is equipped with an interferometer that splits the light emitted from a light source into reference light and signal light, and generates interference light by the reference light that has passed through a reference object and the signal light that has passed through an object to be measured (fundus oculi Ef).

A low coherence light source160is composed of a broad band light source such as super luminescent diode (SLD) or a light emitting diode (LED), etc that emits low coherence light L0. This low coherence light L0, for instance, has a wave length in the near-infrared region and is supposed to be light having a time wise coherence length of approximately several tens of micro-meters. The low coherence light LO emitted from the low coherence light source160has a longer wavelength than the illumination light (wavelength: about 400 nm to 800 nm) of the fundus camera unit1A, for example, a wavelength included within about 800 nm to 900 nm. This low coherence light source160corresponds to an example of the “light source” relating to the present invention.

The low coherence light L0emitted from the low coherence light source160is guided to an optical coupler162through an optical fiber161composed of, e.g. a single mode fiber, or PM (Polarization maintaining) fiber, and then split into reference light LR and signal light LS.

Furthermore, the optical coupler162has both actions, i.e. splitting lights (as a splitter), and superposing lights (as a coupler); however, herein conventionally referred to as an “optical coupler”.

The reference light LR generated by the optical coupler162is guided by an optical fiber163consisting of such as a single mode fiber, and emitted from the end face of the fiber. The emitted reference light LR is reflected by a reference mirror174(reference object) through a glass block172and a density filter173after having been converged into a parallel light flux by a collimator lens171.

The reference light LR reflected by the reference mirror174is converged to the end face of the optical fiber163by the collimator lens171again through the density filter173and the glass block172. The converged reference light LR is guided to the optical coupler162through the optical fiber163.

Furthermore, the glass block172and the density filter173act as a delaying device for matching the optical path length (optical distance) between the reference light LR and the signal light LS, and as a device for matching the dispersion characteristics of reference light LR and the signal light LS.

Furthermore, the reference mirror174is provided to be movable in the propagating direction of the reference light LR. As a result, it ensures the light path length of the reference light LR according to the axial length, etc. of an eye E. Moreover, the reference mirror174is operated to move by a drive mechanism including a motor, etc.

Whereas, the signal light LS generated by the optical coupler162is guided to the end part of the connection line152by an optical fiber164consisting of such as a single mode fiber. A conductive optical fiber152aruns inside the connection line152. Herein, the optical fiber164and the optical fiber152amay be composed of a single optical fiber, or may be jointly formed by connecting each end. In either case, it is sufficient as long as the optical fiber164and152aare composed so as to be capable of transferring the signal light LS between the fundus camera unit1A and the OCT unit150.

The signal light LS is guided within the connection line152to the fundus camera unit1A. Then, the signal light LS enters into the eye E through the lens142, the scanning unit141, the dichroic mirror134the imaging lens126, the relay lens125, the half mirror190, the focusing lens124, the imaging diaphragm121, the aperture part112aof an aperture mirror112, and the objective lens113(then, the barrier filter122and123are retracted from the optical path respectively).

The signal light LS that has entered into the eye E forms an image on a fundus oculi (retina) Ef and is then reflected. Then, the signal light LS is not only reflected on the surface of the fundus oculi Ef, but is also scattered at the refractive index boundary reaching the deep area of the fundus oculi Ef. As a result, the signal light LS reached the fundus Ef becomes a light containing the information reflecting the surface state of the fundus oculi Ef and the information reflecting the scattered state in the rear at the refractive index boundary of the deep area tissue. The light is simply referred as “fundus reflection light of the signal light LS.

The fundus reflection light of the signal light LS advances reversely on the above path and converges at the end face152bof the optical fiber152a, then enters into the OCT unit150through this optical fiber152a, and returns to the optical coupler162through the optical fiber164. The optical coupler162overlays this signal light LS on the reference light LR reflected at the reference mirror174to generate interference light LC. The generated interference light LC is guided into a spectrometer180through an optical fiber165consisting of such as a single mode fiber.

Herein, the “interference light generation part” in the present invention is comprised of an interferometer including at least an optical coupler162, an optical fiber163and164, and a reference mirror174. Furthermore, although a Michelson type interferometer has been adopted in the present embodiment, for instance, a Mach Zender type, etc. or any optional type of interferometer may be adopted appropriately.

The spectrometer180is comprised of a collimator lens181, a diffraction grating182, an image forming lens183, and a CCD (Charge Coupled Device)184. The diffraction grating182in the present embodiment is a transmission type diffraction grating; however, needless to say, a reflection type diffraction grating may also be used. Furthermore, in place of CCD184, it is also possible to adopt other photo-detecting elements such as CMOS etc. This type of photo-detecting element that detects the interference light LC is equivalent to the one example of the “second detecting part” relating to the present invention.

The interference light LC entered the spectrometer180is to be resolved into spectra by the diffraction grating182after having been converged into a parallel light flux by the collimator lens181. The split interference light LC forms an image on the image pick up surface of the CCD184by the image forming lens183. The CCD184receives this interference light LC that is to be converted to an electrical detection signal, and outputs this detection signal to the arithmetic and control unit200.

Constitution of Arithmetic and Control Unit

Next, referring toFIG. 4,FIG. 5, andFIG. 6, the configuration of the the arithmetic and control unit200is described. This arithmetic and control unit200analyzes the detection signal input from the CCD184of the spectrometer180of the OCT unit150, and performs a process of forming tomographic images of a fundus oculi Ef of an eye E. The analysis technique then is the same technique as the conventional Fourier domain OCT technique.

Also, the arithmetic and control unit200operates to form a (image data of) 2-dimensional image showing the state of the surface of a fundus oculi Ef (retina) based on the video signal output from the imaging device10and12of the fundus camera unit1A.

Furthermore, the arithmetic and control unit200executes the control of each part of the fundus camera unit1A and the control of each part of the OCT unit150.

Examples of control performed by the fundus camera unit1A include emission of illumination light by the observation light source101or the imaging light source103, the control of the photographic timing of the fundus oculi image by the imaging devices10and12, the control of insertion/evacuation operations of the exciter filters105and106or the barrier filters122and123onto the optical path, the control of display operations of the LCD140, the control of the aperture value of the photographing aperture121, the movement control of the focusing lens124(the control of the focus adjustment operation and the control of the photographing magnification), the control of rotational operations of the Galvano mirrors141A and141B in the scanning unit141, the emission of the first alignment light by the light source110aof the first alignment optical system110A, the control of insertion/evacuation operations of the alignment member110onto the optical path of the illuminating optical system100, the emission of the second alignment by the light source190aof the second alignment optical system190A, and so on.

Whereas, as for the control of the OCT unit150, emission of the low coherence light by a low coherence light source160, control of accumulated time of the CCD184, and movement control of reference mirror174, etc. are to be performed.

The hardware configuration of the arithmetic and control unit200that acts as described above is explained referring toFIG. 4. The arithmetic and control unit200is provided with a hardware configuration that is the same as conventional computers. To be specific, the configuration includes: a microprocessor201(CPU, MPU, etc.), a RAM202, a ROM203, a hard disk drive (HDD)204, a keyboard205, a mouse206, a display207., an image forming board208, and a communication interface (I/F)209. Each part of these is connected through a bus200a.

The microprocessor201executes operations characteristic to the present embodiment by loading a control program204athat has been stored in the hard disk drive204, on the RAM202.

Furthermore, the microprocessor201executes control of each part of the device that has previously been described and various arithmetic processes, etc. Moreover, control of each part of the device that responds to an operation signal from the keyboard205or the mouse206, control of display processes by the display207, and control of transmitting/receiving processes of various types of data or control signals, etc. are executed by the communication interface209.

The keyboard205, the mouse206and the display207are used as a user interface of the fundus observation device1. The keyboard205is used as a device for inputting letters or figures, etc. by typing. The mouse206is used as a device to perform various input operations with respect to the display screen of the display207.

Furthermore, the display207as an arbitrary display device such as LCD (Liquid Crystal Display) or CRT (Cathode Ray Tube), etc. displays images of a fundus oculi Ef formed by the fundus observation device1and displays various operation screens or set up screens, etc,

Furthermore, the user interface of the fundus observation device1is not limited to such a configuration but may be configured by using any user interfaces equipped with a function to display various information and a function to input various information such as track ball, control lever, touch panel type LCD, control panel for ophthalmology examinations.

An image forming board208is a dedicated electronic circuit for operating to form the image of the fundus oculi Ef of an eye E. In this image forming board208, the fundus image forming board208aand OCT image forming board208bare installed. The fundus image forming board208ais a dedicated electronic circuit for operating in order to form the image of the fundus oculi based on the video signal from the imaging device10or the imaging device12of the fundus camera unit1A. Furthermore, the OCT image forming board208bis a dedicated electronic circuit for operating in order to form fundus images (tomographic images) based on the detecting signal from CCD184of the spectrometer180in the OCT unit150. The image forming board208allows the processing speed for forming fundus images to improve.

A communication interface209operates to send the control signal from a microprocessor201to the fundus camera unit1A and OCT unit150. Also, the communication interface209operates to receive the video signal from the imaging device10and12in the fundus camera unit1A and the detecting signal from CCD184in the OCT unit150, and it operates to input the signals to the image forming board208. At this time, the communication interface209operates to input the video signal from the imaging device10and12to the fundus image forming board208a, and it operates to input the detecting signal from CCD184to OCT image forming board208b.

Moreover, when the arithmetic and control unit200is connected to a network such as LAN (Local Area Network) or Internet, etc., the communication interface209may be configured to be equipped with a network adopter such as LAN card, etc. or a communication equipment such as modem, etc. so as to be able to perform data communication through the network. In this case, a server accommodating the control program204amay be installed, and at the same time, the arithmetic and control unit200may be configured as a client terminal of the server.

Control System Configuration

Then, the configuration of the control system of the fundus observation device1is explained with reference toFIG. 5andFIG. 6.FIG. 5shows the entire configuration of the control system andFIG. 6shows the detailed configuration of a portion thereof. Incidentally, among the configurations that the fundus observation device1comprises, parts related to the operation or processes related to the present invention are particularly selected and described inFIG. 5andFIG. 6.

The control system of the fundus observation device1is configured mainly having a controlling part210of the arithmetic and control unit200. The controlling part210is comprised including: the microprocessor201, the RAM202, the ROM203, the hard disk drive204(control program204a), and the communication interface209.

A controlling part210executes various control processes by a microprocessor201that runs based on a control program204a. In particular, the controlling part210controls the detection timing of the reflection light by the fundus oculi Ef of the illumination light, or in other words, controls the radiographic timing of the fundus oculi image by the imaging devices10,12of the fundus camera unit1A. Similarly, the controlling part210controls the timing of the radiogram of the fundus oculi image by the CCD184of the spectrometer180on the OCT unit150, or in other words, controls the timing of detection of the interference light LC.

The controlling part210comprises a main controller210A, a detection timing controlling part210B, and an alignment controlling part210C, as shown inFIG. 6. The detection timing controlling part210B acts as one example of the “detection timing controlling part” relating to the present invention. In addition, the alignment controlling part210C acts as an example of the “controlling part” relating to the present invention.

The main controller210A functions as a central unit of the controlling part210and controls the each part of the device. For example, the main controller210A controls the display of two types of images obtained by the fundus observation device1, that is, the two-dimensional image of the surface of the fundus oculi Ef by the fundus camera unit1A (the fundus oculi image Ef′) and the image of the fundus oculi Ef formed based on detection signals obtained by the OCT unit150(the tomographic image or the three-dimensional image) on the display part240A (display207) of the user interface240. These fundus oculi images may be displayed on the display part240A separately, or both images may be displayed side-by-side at the same time. In addition, the main controller210A causes the display part240A to display the scale S shown inFIG. 17when the alignment bright points P1and P2are displayed on the display part240A.

The detection timing controlling part210B controls the timing of photographing the fundus oculi images by the fundus camera unit1A or the OCT unit150. Specifically, the detection timing controlling part210B controls, for example, the frame rate of the imaging devices10and12or the CCD184by controlling the storage time of the image pick up element10a,12aand the CCD184and by controlling the electronic shutter similar as before.

In addition, the detection timing controlling part210B controls the timing of power delivery to the observation light source101, the imaging light source103, and the low coherence light source160and thereby controls the emission timing of light by these light sources.

Particularly, the detection timing controlling part210B controls the imaging light source103and the imaging device10(or the observation light source101and the imaging device12) and the low coherence light source160and the CCD184respectively. Thereby, the detection timing controlling part210B acts so as to synchronize the photographic timing of the two-dimensional image of the surface of the fundus oculi Ef and the photographic timing of the tomographic image of the fundus oculi Ef. At this time changes in orientation of Galvano mirrors141A and141B are synchronously controlled. The detection timing controlling part210B controls the frame rate of the imaging device10(or imaging device12) and the frame rate of the CCD184. The ratio of the frame rates of the imaging device10(12) to the CCD184is adjusted to, for example, between 10:1 and 1:1.

In addition, the detection timing controlling part210B controls the mirror drive mechanisms241and242of the fundus camera unit1A respectively so as to operate each of the Galvano mirrors141A and141B independently and thereby controls scanning of the signal light LS. Furthermore, the detection timing controlling part210B controls the reference mirror drive mechanism243and moves the reference mirror174in the direction of travel of the reference light LR (optical path direction).

The alignment controlling part210C controls the timing of projecting the split indicators L1and L2onto the eye E by the first alignment optical system110A, and controls the timing of projecting the alignment bright points P1and P2onto the eye E by the second alignment optical system190A.

When projecting the split indicators L1and L2, the alignment controlling part210C inserts the inclined surface110sof the alignment member110into the optical path by controlling the alignment drive mechanism110gand illuminates the light source110a. In addition, when terminating the projection of the split indicators, the alignment controlling part210C evacuates the inclined surface110sof the alignment member110from the optical path by controlling the alignment drive mechanism110gand turns the light source110aoff. Incidentally, it is also allowed to configure so as to control the projection timing of the split indicators only by inserting and/or detaching the inclined surface110sof the alignment member110onto the optical path. In addition, it is allowed to configure so as to control the timing of projecting the split indicators only by illuminating/turning off the light source110a.

When projecting the alignment bright points P1and P2, the alignment controlling part210C illuminates the light source190a. In addition, when terminating the projection of the alignment bright points P1and P2, the alignment controlling part210C turns the light source190aoff. Incidentally, it is also allowed to control the timing of projecting the alignment bright points P1and P2by configuring the half mirror190insertable and/or detachable to the optical path as well as the alignment member110.

An image forming part220is intended to operate the process forming the fundus image based on the video signal from the imaging device10and12of the fundus camera unit1A and to operate the process forming the fundus image based on the detecting signal from CCD184in the OCT unit150. This image forming part220comprises an image formation board208.

The image processing part230is used for various image processes to the fundus images formed by the image forming part220. For example, it operates to form a 3-dimensional image of the fundus oculi Ef based on the tomographic images of the fundus oculi Ef corresponding to the detection signal from the OCT unit150and various corrections, such as brightness adjustment. This image processing part230may be comprised with the inclusion of a microprocessor201, and may be comprised with the inclusion of an OCT image formation board208b.

In addition, the image processing part230performs processes such as extracting layers in the tomographic image of the fundus oculi Ef (retina layer, choroid membrane, sclera, and so on), measuring the layer thickness, obtaining a distribution of layer thickness, and the calculating the difference in layer thickness.

The correction processing part225performs the process of correcting image positions of the tomographic images of fundus oculi Ef based on results of detecting interference light LC from the CCD184on the OCT unit150based on two-dimensional images of the surface of the fundus oculi Ef based on results of detecting the reflection light by fundus oculi Ef of the illumination light by the imaging device10(or imaging device12) on the fundus camera unit1A. This correction processing part225is equivalent to one example of “correction part” relating to the present invention and consists of the inclusion of a microprocessor201or the like.

The process of correcting the image positions of the tomographic images executed by the correction processing part225will now be described more specifically. An extraction processing part, which is not shown in any Figures, is built into the correction processing part225. This extraction processing part analyzes the two-dimensional images of the surface of the fundus oculi Ef based on results of detection from the imaging device10(or imaging device12) and extracts the characteristic part among these two-dimensional images. The characteristic parts subject to extraction are, for example, the optic papilla, macula lutea, a specific blood vessel or vascular bifurcation. The extraction processing part extracts the characteristic parts that are subject to extraction by analyzing the luminance and color of the two-dimensional images of the fundus oculi Ef, for example.

The correction processing part225acquires the image positions of the characteristic part extracted by the extraction processing part. These coordinate positions are expressed by a xy coordinate system shown, for example, inFIG. 1. In addition, the xy coordinate system is connected in advance to the two-dimensional coordinate system defined on the detection side of the image pick up element10a(or imagine sensor element12aof the imaging device12) on the imagining device10. The correction processing part225acquires the image positions of the relevant characteristic part by converting the image positions of the characteristic part expressed by the two-dimensional coordinate system on this detection surface to the image positions by means of the relevant xy coordinate system.

The correction processing part225corrects the image positions of the tomographic images of the fundus oculi Ef using the image positions of the characteristic part acquired in this way. Details of this correction process are described below.

The user interface (UI)240comprises a display part240A consisting of display devices such as a display207, and an operation part240B consisting of operation devices or input devices such as a keyboard205and a mouse206. Incidentally, the display part240A may include any displaying part such as a touch panel monitor11provided on the fundus camera unit1A. In addition, the operation part240B may include any operating part such as a joystick4, an operation button4a, or other buttons or keys that are not shown.

The controlling feature of the scanning signal light LS by the controlling part210and the process feature to the detecting signal from the OCT unit150by the image forming part220and the image processing part230are respectively described below. Furthermore, an explanation regarding the process of the image forming part220, etc., to the video signal from the fundus camera unit1A is omitted because it is the same as the conventional process.

Regarding the Signal Light Scanning

Scanning of signal light LS is performed by changing the facing direction of the reflecting surfaces of the Galvano mirrors141A and141B of the scanning unit141in the fundus camera unit1A. By controlling the mirror drive mechanisms241and242respectively, the controlling part210changes the facing direction of the reflecting surfaces of the Galvano mirror141A and141B, and scans the signal light LS on the fundus oculi Ef.

Once the facing direction of the reflecting surface of the Galvano mirror141A is changed, the signal light LS is scanned in a horizontal direction (x-direction inFIG. 1) on the fundus oculi Ef. Whereas, once the facing direction of the reflecting surface of the Galvano mirror141B is changed, the signal light LS is scanned in a vertical direction (y-direction inFIG. 1) on the fundus oculi Ef. Furthermore, by changing the facing direction of the reflecting surfaces of both Galvano mirrors141A and141B simultaneously, the signal light LS may be scanned in the composed direction of x-direction and y-direction. That is, by controlling these two Galvano mirrors141A and141B, the signal light LS may be scanned in an arbitrary direction on the xy plane.

FIG. 7represents one example of scanning features of signal light LS for forming images of a fundus oculi Ef.FIG. 7Arepresents one example of scanning features of the signal light LS, when the signal light LS sees the fundus oculi Ef from an incident direction onto the eye E (that is, +direction of z is seen from −direction of z inFIG. 1). Furthermore,FIG. 7Brepresents one example of arrangement features of scanning points (positions at which image measurement is carried out) on each scanning line on the fundus oculi Ef.

As shown inFIG. 7A, the signal light LS is scanned within a rectangular shaped scanning region R that has been preset. Within this scanning region R, plural (m number of) scanning lines R1through Rm have been set in the x-direction. When the signal light LS is scanned along each scanning line Ri (i=1 through m), detection signals of interference light LC are to be generated.

Herein, the direction of each scanning line Ri is referred as the “main scanning direction” and the orthogonally crossing direction is referred as the “sub-scanning direction”. Therefore, the scanning of the signal light LS in a main scanning direction is performed by changing the facing direction of the reflecting surface of the Galvano mirror141A, and the scanning in a sub-scanning direction is performed by changing the facing direction of the reflecting surface of the Galvano mirror141B.

On each scanning line Ri, as, shown inFIG. 7B, plural (n number of) of scanning points Ri1through Rin have been preset.

In order to execute the scanning shown inFIG. 7, the controlling part210controls the Galvano mirrors141A and141B to set the incident target of the signal light LS with respect to a fundus oculi Ef at a scan start position RS (scanning point R11) on the first scanning line R1. Subsequently, the controlling part210controls the low coherence light source160to flush the low coherence light L0for emitting the signal light LS to the scan start position RS. The CCD184receives the interference light LC based on the fundus reflection light of this signal light LS at the scan start position RS, and outputs the detection signal to the controlling part210.

Next, by controlling the Galvano mirror141A the controlling part210scans the signal light LS in a main scanning direction and sets the incident target at a scanning point R12, triggering a flush emission of the low coherence light L0for making the signal light LS incident onto the scanning point R12. The CCD184receives the interference light LC based on the fundus reflection light of this signal light LS at the scanning point R12, and then outputs the detection signal to the controlling part210.

Likewise, the controlling part210obtains detection signals output from the CCD184responding to the interference light LC with respect to each scanning point, by flush emitting the low coherence light L0at each scanning point while shifting the incident target of the signal light LS from scanning point R13, R14, . . . , R1(n-1), R1n in order.

Once the measurement at the last scanning point R1n of the first scanning line RI is finished, the controlling part210controls the Galvano mirrors141A and141B simultaneously and shifts the incident target of the signal light LS to the first scanning point R21of the second scanning line R2following a line switching scan r. Then, by conducting the previously described measurement with regard to each scanning point R2j (j=1 through n) of this second scanning line R2, a detection signal corresponding to each scanning point R2j is obtained.

Likewise, by conducting a measurement with respect to the third scanning line R3, . . . , the m-1th scanning line R (m-1), the mth scanning line Rm respectively to obtain the detection signal corresponding to each scanning point. Furthermore, the symbol RE on a scanning line Rm is a scan end position in accordance with a scanning point Rmn.

As a result, the controlling part210obtains m×n number of detection signals corresponding to m×n number of scanning points Rij (i=1 through m, j=1 through n) within the scanning region R. Hereinafter, a detection signal corresponding to the scanning point Rij may be represented as Dij.

Such interlocking control of such shifting of scanning points and the emission of the low coherence light L0may be realized by synchronizing, for instance, the transmitting timing of control signals with respect to the mirror drive mechanisms241,242and the transmitting timing of control signals (output request signal) with respect to the low coherence light source160.

As described, when each Galvano mirror141A and141B is being operated, the controlling part210stores the position of each scanning line Ri or the position of each scanning point Rij (coordinates on the xy coordinate system) as information indicating the content of the operation. This stored content (scan positional information) is used in an image forming process as was conducted conventionally.

Regarding Image Processing

Next, one example of the process relating to OCT images is described of the image forming part220and the image processing part230. Only the process of forming tomographic images of the fundus oculi Ef and the process of forming three-dimensional images based on tomographic images are explained here, and the process of forming three-dimensional images including image position correction of tomographic images by the correction processing part225on the arithmetic and control unit200will be described later.

The image forming part220executes the formation process of tomographic images of a fundus oculi Ef along each scanning line Ri (main scanning direction). The image processing part230executes the formation process of a 3-dimensional image of the fundus oculi Ef based on these tomographic images formed by the image forming part220.

The formation process of a tomographic image by the image forming part220, as was conventionally done, includes a 2-step arithmetic process. In the first step of the arithmetic process, based on a detection signal Dij corresponding to each scanning point Rij, an image in the depth-wise direction (z-direction inFIG. 1) of a fundus oculi Ef at the scanning point Rij is formed.

FIG. 8represents a feature of a tomographic image formed by the image forming part220. In the second step of the arithmetic process, with regard to each scanning line Ri, based on the images in the depth-wise direction at the n number of scanning points Ri1through Rin thereon, a tomographic image Gi of a fundus oculi Ef along this scanning line Ri is formed. Then, the image forming part220determines the arrangement and the distance of each scanning point Ri1through Rin while referring to the positional information (said scan positional information) of each scanning point Ri1through Rin, and forms a tomographic image Gi along this scanning line Ri. Due to the above process, m number of tomographic images G1through Gm at different positions of the sub-scanning direction (y-direction) are obtained.

Formation Process of 3-Dimensional Images

Next, the formation process of a 3-dimensional image of a fundus oculi Ef by the image processing part230is explained. A 3-dimensional image of a fundus oculi Ef is formed based on the m number of tomographic images (at least a plurality of tomographic images whereof) whose image positions have been corrected by the correction processing part225. The image processing part230forms a 3-dimensional image of the fundus oculi Ef by performing a known interpolating process to interpolate an image between the adjacent tomographic images Gi and G (i+1).

Then, the image processing part230determines the arrangement and the distance of each scanning line Ri while referring to the positional information of each scanning line Ri to form this 3-dimensional image. For this 3-dimensional image, a 3-dimensional coordinate system (x,y,z) is set up, based on the positional information (said scan positional information) of each scanning point Rij and the z coordinate in the images of the depth-wise direction.

Furthermore, based on this 3-dimensional image, the image processing part230is capable of forming a tomographic image of the fundus oculi Ef at a cross-section in an arbitrary direction other than the main scanning direction (x-direction). Once the cross-section is designated, the image processing part230determines the position of each scanning point (and/or an image in the depth-wise direction that has been interpolated) on this designated cross-section, and extracts an image (and/or image in the depth-wise direction that has been interpolated) in the depth-wise direction at each determined position to form a tomographic image of the fundus oculi Ef at the designated cross-section by arranging plural extracted images in the depth-wise direction.

Furthermore, the image Gmj inFIG. 8represents an image in the depth-wise direction (z-direction) at the scanning point Rmj on the scanning line Rm. Likewise, an image in the depth-wise direction at each scanning point Rij on the scanning line Ri formed by the arithmetic process of said first step may be represented as “image Gij.”

In addition, the process of forming three-dimensional images of fundus oculi Ef described here is assumed to be when m number of tomographic images G1-Gm are displaced in the xy direction, or in other words, when eye movement of the eye subject to examination E occurs during image measurement of the tomographic images G1-Gm. The following [Operation] section describes operation of the fundus observation device1for optimally forming three-dimensional images even if eye movement of the eye subject to examination E occurs during image measurement of the tomographic images G1-Gm.

Operation

Next, operations of the fundus observation device1related to the present embodiment are described. The flowchart shown inFIG. 9andFIG. 10shows an example of procedure of the fundus observation device1.FIG. 11is a schematic diagram of this image position correction process.

Also described is the case in which the ratio of the frame rate of the fundus camera unit1A (imaging device10and/or12.) to the frame rate of the OCT unit150(CCD184) is 2:1. However, even when the ratio of these frame rates is other than 2:1, it is possible for a similar process to be executed.

First, an examiner arranges an eye E at the predetermined examination position by mounting a subject's jaw on a jaw holder6(S1), and powers on the fundus observation device1by operating a power switch or the like not shown (S2).

The main controller210A initializes the device in response to the power-on (S3). This initialization may be processes of clearing the memory (RAM202inFIG. 4) and moving the movable optical devices such as the Galvano mirrors141A/141B and the reference mirror174to predetermined initial positions. Incidentally, it is also possible to configure to move these optical devices to the initial position corresponding to an eye E with reference to information related to that eye.

Next, the detection timing controlling part210B controls the observation light source101and the imaging device12and photographs the image of the surface of the fundus oculi Ef. The main controller210A causes the display part240A to display this photographic image (fundus oculi observation image) (S4).

Alignment and Focus Adjustment: Steps S5to S13

Then, the position (alignment) and focus for an eye E are adjusted. For that purpose, first, the alignment controlling part210C illuminates the light source190aof the second alignment optical system190A and projects the alignment bright points P1and P2onto the eye E (S5). In addition, the main controller210A causes the display part240A to display the scale S ofFIG. 17(S6). Thus, the fundus observation image, the alignment bright points P1and P2, and the scale S are displayed on the display part240A at the same time.

The examiner adjusts the position of the device to the eye E by operating the joystick4shown inFIG. 1and adjusting the position of the device such that the alignment bright points P1and P2are within the scale S (S7).

When the position adjustment of the device terminates, the alignment controlling part210C turns the light source190aoff and terminates the projection of the alignment bright points P1and P2onto the eye E (S8), and the main controller210A terminates the display of the scale S (S9).

Incidentally, it is possible to configure the termination of the position adjustment to be detected based on the manual operation or to be detected automatically. As one example of the configuration to be operated manually, the termination of the position adjustment is detected by configuring such that the examiner performs a predetermined operation (such as pressing the operation button4aon the top of the joystick4) when terminating the position adjustment. On the contrary, one example of the configuration for automatic operation is as follows. At first, the pixel value (luminance value) on the display screen is analyzed to detect the coordinates (display position) of the alignment bright points P1and P2. Then, it is determined whether they are within the scale S. Finally, the termination of the position adjustment is detected when it is determined that they are within the scale S. Herein, it may configure to determine that the position adjustment terminates when positions of the alignment bright points P1and P2have not moved for a predetermined period.

Next, while the alignment controlling part210inserts the alignment member110into the optical path by controlling the alignment drive mechanism110g(S10), the alignment controlling part210projects the split indicators L1and L2onto the eye E by illuminating the light source110aof the first alignment optical system110A (S11). As a result, a fundus observation image and the split indicators L1and L2are displayed on the display part240A.

The examiner operates the focusing knob described above to adjust the focus such that the lateral positions of the split indicators L1and L2are coincident with each other (S12). When the focus adjustment terminates, the alignment controlling part210C turns off the light source1110aand evacuates the alignment member110from the optical path so as to terminate the projection of the split indicators L1and L2onto the eye E (S13).

Then, the eye E is fixated in the predetermined direction in order to observe the region of interest of the fundus oculi Ef. For that purpose, the main controller210A by controls the LCD140to display an internal fixation target that is not shown. As a result, the internal fixation target is presented on the eye E (S14). This internal fixation target is, for example, a target (such as a bright point) displayed on the LCD140, and acts so as to guide the eye-gaze direction of the eye E by changing its display position.

The examiner operates the focusing operation part240B and determines the present position of the internal fixation target, that is, the fixation position of the eye E so that the image of the region for observation in the fundus oculi Ef is displayed on the display part240A (S15). The main controller210A causes the display part240A to display the information regarding the determined fixation position.

Next, the position of the reference mirror174during capturing a cross-sectional image is determined. For that purpose, the detection timing controlling part210B moves the reference mirror174by controlling the reference mirror drive mechanism243, changes the orientations of the Galvano mirrors141A and141B by controlling the mirror drive mechanisms241A and241B, and has the CCD184to detect the interference light LC at the predetermined frame rate (e.g., at approximately 5 to 15 (frame/second)) by having the low coherence light source160to emit the low coherence light LO.

At this time, the timing of change in orientation of the Galvano mirrors141A and141B, the emission timing of the low coherence light LO, and the detection timing of the interference LC by the CCD184are synchronized with each other. In addition, movement of the reference mirror174may be controlled based on the manual operation by the examiner or may be performed automatically.

The main controller210A causes the display part240A to displays the tomographic image of the fundus oculi Ef at that frame rate based on the detection signals input from the CCD184(S16). As a result, the fundus oculi observation image and the tomographic image are displayed on the display part240A.

The examiner determines the position of the reference mirror174such that the tomographic image is in the desired display state (such as the desired depth (z position) and the precision of the image) (S17). At this time, if required, the orientations of the polarizing axes of the low coherence light LO, the signal light LS, the reference light LR, and the interference light LC are corrected. Consequently, the preparation for capturing a tomographic image of the fundus oculi Ef is completed. The operation for capturing the tomographic image is explained below.

Detection of Low Coherence Light LO; Steps S18, S19

When the predetermined operation for starting to capture the tomographic image (e.g. putting down the operation button4aetc) is instructed, the detection timing controlling part210B illuminates the observation light source101and controls the imaging device12so as to detect the reflection light by the fundus oculi Ef of the illumination light from the observation light source101by the frame rate f1(first/second) (S18), and then controls low coherence light source160and the CCD184and cause CCD184to-detect the interference light LC by the frame rate f2(frames/second) (S119). At this time, the frame rate f1of the imaging device12and the frame rate f2of the OCT unit150are mutually synchronized by the detection timing controlling part210B.

The image forming part220sequentially forms surface images of the fundus oculi based on image signals sequentially output from the imaging device12(S20), and sequentially forms tomographic images of fundus oculi Ef based on detection signals input sequentially from the CCD184(S21).

FIG. 11shows one example of the formation of surface images and tomographic images of the fundus oculi Ef formed in steps S20and S21.FIG. 11shows surface images and tomographic images of the fundus oculi Ef sequentially formed by the image forming part220when the ratio of the frame rate f1of the imaging device12to the frame rate of the CCD184is f1:f2=2:1.

FIG. 11A,FIG. 11B,FIG. 11C, andFIG. 11Dshow the image formed based on the interference light LC and the reflection light by the fundus oculi Ef of the illumination light detected at times t=t1, t2, t3, and t4, respectively. In addition, these images show only some of the images formed in the serial process of forming images. Furthermore, the intervals of detection times t(k+1)−tk (k=1, 2, 3, . . . )=Δt are constant.

In time t=t1, both the imaging device12and the CCD184are controlled so as to detect light, and the surface image Ef1′ and the tomographic image G1of the fundus oculi Ef (SeeFIG. 7and FIG.8;) are formed based on each of the detected results (SeeFIG. 11A).

In time t=t2, only the imaging device12is controlled so as to detect light, and the surface image Ef2′ of the fundus oculi Ef is formed based on these detected results (SeeFIG. 11B).

In time t=t3, both the imaging device12and the CCD184are controlled so as to detect light similar to the case with time t=t1, and based on each of the detected results, the surface image Ef3′ and the tomographic images G2of the fundus oculi Ef (SeeFIG. 7andFIG. 8) are formed (SeeFIG. 11C).

In time t=t4, only the imaging device12is controlled so as to detect light similar to the case with time t2, and the surface image Ef4′ of the fundus oculi Ef is formed based on the detected results (SeeFIG. 11D).

Below, fundus oculi images are similarly formed for t=t5, t6, t7, etc. In other words, when the ratio of the frame rate f1of the imaging device12to the frame rate f2of the CCD184is 2:1, both the imaging device12and the CCD184detect light at time t=tk (k=odd number), and a surface image Efk′ and tomographic image G((k+1)/2) of the fundus oculi Ef are acquired, and only the imaging device12detects light at time t=tk (k=even number) and only the surface image Efk′ on the locus oculi Ef is acquired.

The surface images Ef1′-Ef4′ of the fundus oculi Ef shown inFIG. 11differ in the positions of the images of optic papilla and blood vessels among the frames. This indicates the occurrence of eye movement of the eye E during the examination. Described below is the process for forming three-dimensional images under such circumstances.

Image Position Correction for Tomographic Images: Steps S22-S25

The extraction processing part (previously described) of the correction processing part225extracts the characteristic part of each surface image produced at the same time as the tomographic images (S22). In the example shown inFIG. 11, the correction processing part225analyzes each of the surface images Efk′ (k=odd number) and extracts the image area corresponding to the optic papilla in the fundus oculi Ef by extracting the image area of an approximate round shape having a roughly equal luminance value.

The correction processing part225finds the coordinate values of the extracted characteristic part (S23). As an example of this process, the correction processing part225determines the coordinate values (x coordinate, y coordinate) of predetermined positions in the image areas of the extracted optic papilla extracted in Step S22, such as the coordinate values of pixels having the greatest luminance value.

Next, the correction processing part225calculates the displacement of coordinate values for the characteristic part obtained from another surface image Efk′ (k=odd number) for coordinate values of a characteristic part obtained from one of the surface images Efk′ (k=odd number) (S24). For example, displacement (Δ xk=xk−x1, Δ yk=yk−y1) of the coordinate values (xk, yk) of the characteristic part of each surface image Efk′ (k=3, 5, 7, etc.) is calculated for the coordinate values (x1, y1) of the characteristic part of the surface image Ef1′. In other words, the correction processing part225calculates the relative displacement of image positions of a plurality of extracted characteristic parts.

Furthermore, the correction processing part225corrects image positions of the tomographic images using the displacement of the coordinate values of the characteristic part calculated in Step S24(S25). In the example mentioned above, for each of k=3, 5, 7, etc. (odd numbers), the image position of the tomographic image G((k+1)/2) is moved by (−Δ xk, −Δ yk), correcting it so as to match the image position of the tomographic image G1.

Then, a three-dimensional image of the fundus oculi Ef is formed. For that purpose, among a plurality of tomographic images in which the image position has been corrected, the image processing part230selects the inappropriate images such as those that have been captured when the eye E blinked and those whose misalignment of the image position is larger than the predetermined value (S26). Such selection can be accomplished by analyzing the pixel value of the tomographic image or by basing on the correction amount of the image position. Incidentally, it is also possible to employ the conventional way of blink detection.

The main controller210A causes the display part240A to display thumbnails of plurality of tomographic images side-by-side and to display the identification information enabling to identify the tomographic image selected at the step S26(S27). This identification in-formation may be a mark showing an inappropriate tomographic image (e.g., “x”) or a list of inappropriate tomographic images.

The examiner operates the operation part240B with reference to the identification information so as to specify the tomographic image to be eliminated from formation of a three-dimensional image (S28).

The image processing part230forms a three-dimensional image of the fundus oculi Ef based on the tomographic images not specified at the step S28(S29). Consequently, formation of a three-dimensional image of the fundus oculi Ef by the fundus observation device1is completed.

When capturing a tomographic image or a three-dimensional image of the fundus oculi Ef terminated, the main controller210A stores the image data of these images and the images of the surface of the fundus oculi Ef (fundus oculi photographing image) in the hard disk drive204or an external memory device (such as database) (S30). Incidentally, the fundus oculi photographing image may be an image photographed by the imaging device10by illuminating the imaging light source103, for example, immediately after capturing the tomographic image (step S21). Incidentally, it is preferable to configure so as to save the patient information such as name of subjects and patient ID and the associated information during capturing images (e.g., examination date and time, fixation position, interference position, and so on) with the image data of the image of the fundus oculi Ef.

An examiner (doctor) reads, out the saved images of the fundus oculi Ef by performing the predetermined operation, and has the image processing part230to analyze the image such as extracting layers in a tomographic image of the fundus oculi Ef, measuring the thickness of the layers, creating a distributed image of the layer thickness, calculating the difference of layer thickness, and creating images of any cross-section of a three-dimensional image depending on the diagnostic purpose (S31). Then, that eye is diagnosed with reference to the result of such analysis.

Effect and Advantage

The operation and effect of the fundus observation device1related to the present embodiment having the constitution as above is explained.

This fundus observation device1comprises the fundus camera unit1A for operating as the fundus camera in order to capture 2-dimensional images showing the state of the surface of the fundus oculi Ef and the OCT unit150for operating as an optical image measuring device in order to capture tomographic images (and 3-dimensional images) of the fundus oculi Ef.

The optical path of the signal light used for image forming by the OCT unit150is guided to an eye E by combining the optical path (the imaging optical path) for forming by the imaging optical system120of the fundus camera unit1A. The combining of this optical path is performed by the dichroic mirror134.

In addition, the fundus reflection light of the signal light LS is guided to the dichroic mirror134along the imaging path, and goes to the OCT unit150by being separated from the imaging optical path via this dichroic mirror134.

As a result, by setting the dichroic mirror134for operating in order to combine and separate the imaging optical path of the fundus camera unit1A and the optical path of the signal light LS, it is possible to capture both 2-dimensional images of the surface of the fundus oculi Ef and tomographic images of the fundus oculi Ef (and 3-dimensional images).

In particular, to an eye E, if illumination of the illumination light by the fundus camera unit1A and illumination of the signal light LS by the OCT unit150are simultaneously operated, each fundus reflection light can be separated via the dichroic mirror134and images formed by detecting each of them, making it possible to simultaneously produce both 2-dimensional images of the surface of the fundus oculi Ef and tomographic images of the fundus oculi Ef.

At this time, the signal light LS from the OCT unit150and the simultaneously illumination light may be near-infrared light from the imaging light source103and also visible light from the observation light source101.

In addition, according to the fundus observation device1related to the present embodiment, it is configured to capture a tomographic image or a surface image of the fundus oculi Ef after automatically terminating the projection of the alignment bright points P1and P2or the split indicators L1and L2(alignment indicators) onto the eye E, and therefore it is possible to prevent the alignment indicators from being reflected in the image of the fundus oculi Ef.

Particularly, the image position can be corrected adequately because it is possible to prevent alignment indicators from being reflected in the image of the surface of the fundus oculi (fundus oculi observation image) for correcting the position of tomographic images of the fundus oculi. Therefore, even if the eye subject to examination E moves while measuring the tomographic images of the fundus oculi Ef, the image positions of the tomographic images can be corrected using the surface images of the fundus oculi Ef produced at the same time as detecting the interference light LC that forms the base of the tomographic images, and it is possible to form highly reliable three-dimensional images based on the tomographic images for which the image positions have been corrected.

Incidentally, in the present embodiment, it is configured to terminate the projection of the alignment indicators immediately after the termination of the alignment and focus adjustment, but the timing of the termination of the projection is not limited to this. In other words, the Liming of the termination of projecting the alignment indicators can be at any timing between immediately after the termination of the alignment or the like and immediately before the image capturing of the fundus oculi Ef (step S18).

In addition, when applying the configuration in which plurality of kinds of alignment indicator can be projected as the present embodiment, the projection of each alignment indicator can be terminated individually, or the projection of two or more kinds of alignment indicators can be terminated at the same time.

In addition, the fundus observation device1of the present embodiment is configured to be capable of projecting both the alignment bright points P1and P2and the split indicators L1and L2onto an eye E, but it is also possible to configure it to project only one of them (that is, the configuration can be provided with just one of the first alignment optical system110A and the second alignment optical system190A.).

As an example, the timing of terminating the projection of alignment indicators can be immediately after the presentation of the internal fixation target (step S14), immediately after the determination of the fixation position (step S15), immediately after the displaying of the tomographic image of the fundus oculi Ef (step S16), immediately after the determination of the position of the reference mirror174(S17), and so on. However, it is preferable to terminate the projection immediately after the termination of the alignment or immediately after the termination of the focus adjustment in order to obtain an advantage to be explained next.

In other words, since the fundus observation device1is configured to adjust the fixation position or the position determination of the reference mirror174after automatically terminating projection of the alignment indicators, the tasks of fixation position adjustment or reference mirror position determination can be easily and adequately accomplished without alignment indicators being reflected in the fundus observation image or the tomographic image.

Incidentally, in the present embodiment, both alignment bright points P1and P2for position adjustment of the device in relation to an eye E and the split indicators for focus adjustment are employed, but it is also possible to adopt a configuration in which only one of these is employed. In addition, it is also possible to use alignment indicators of any feature other than these. In that case, the similar advantage on the present embodiment can be obtained by a configuration to terminate the projection of that alignment indicator onto the eye E at any timing between immediately after using that alignment indicator and image capturing of the fundus oculi Ef, and more preferably, immediately after using that alignment indicator.

MODIFIED EXAMPLE

The constitution described above is merely one example to preferably implement the fundus observation device related to the present invention. Therefore, optional modifications may be implemented appropriately within the scope of the present invention.

FIG. 12shows an example of the operation timing of the fundus observation device related to the present invention.FIG. 12describes the capture timing of tomographic images by the OCT unit150, the capture timing of fundus oculi observation images by the observation light source101and the imaging device12, the capture timing of fundus oculi photographing images by the imaging light source103and the imaging device10, and the projection timing of alignment indicators onto an eye E.

Incidentally, the detection timing controlling part210B controls the capture timing of images and the alignment controlling part210C controls the projection timing of alignment indicators. In addition, linkage (synchronization) between the capture timing of images and the projection timing of alignment indicators is performed by the main controller210A.

In addition, the alignment bright points P1and P2shall be projected onto the eye E as alignment indicators. The main controller210A may cause to display the scale S when projecting the alignment bright points P1and P2.

FIG. 12describes the case of capturing four tomographic images, but the number of tomographic images to be captured is arbitrary.

When the instruction or capturing tomographic images of the fundus oculi Ef is operated, first, at time T=T1, tomographic images of the fundus oculi Ef (tomographic image G1ofFIG. 8) and the fundus oculi observation image G1′ are captured.

Next, at time T=T2, the alignment bright points P1and P2are projected onto the eye E and the fundus oculi observation image G2′ is captured.

Next, at time T=T3, the tomographic image G2of the fundus oculi Ef and the fundus oculi observation image G3′ are captured.

Next, at time T=T4, the alignment bright points P1and P2are projected onto the eye E and the fundus oculi observation image G4′ is captured.

Next, at time T=T5, the tomographic image G3of the fundus oculi Ef and the fundus oculi observation image G5′ are captured.

Next, at time T=T6, the alignment bright points P1and P2are projected onto the eye E and the fundus oculi observation image G6′ is captured.

Next, at time T=T7, the tomographic image G4of the fundus oculi Ef and the fundus oculi observation image G7′ are captured.

Next, at time T=T8, the alignment bright points P1and P2are projected onto the eye E and the fundus oculi observation image G8′ is captured.

Finally, at time T=T9, the fundus oculi observation image G′ is captured.

The correction processing unit225corrects the image positions of each tomographic image G1, G2, G3, and G4based on the fundus oculi observation images G1′, G3′, G5′, and G7′ captured at the same time with them, respectively. In this way, the correction precision can be improved by correcting the image position of tomographic images by using the fundus oculi observation images captured at the same time, thereby forming three-dimensional images with high degree of certainty.

The alignment bright points P1and P2are respectively reflected into the fundus oculi observation images (12′, G4′, G6′, and G8′ captured immediately after capturing each tomographic image G1, G2, G3, and G4. Each fundus oculi observation image G2′, G4′, G6′, and G8′ is captured during the line change scanning r shown inFIG. 7. The main controller210A causes the display part240A to display the fundus oculi observation images G2′, G4′, G6′, and G8′ and the scale S when the tomographic images G1, G2, G3, and G4, for example, are displayed after capturing images or the like (e.g., during the image analysis at step S31ofFIG. 11).

Incidentally, it is also possible to configure to project the alignment bright points P1and P2and capture the fundus oculi observation images immediately before capturing each tomographic image G1to G4. Herein, the time interval between the time of capturing the tomographic image and the time of capturing the fundus oculi observation image into which the alignment bright points P1and P2are reflected (T2-T1or the like) corresponds to one example of the “predetermined time” relating to the present invention.

An examiner can have visual contact with the positional relationship between the scale S and the alignment bright points P1and P2in the fundus oculi observation image G6′, so as to determine whether the position of an eye E is out of alignment when the tomographic image G3has been captured.

The fundus oculi photographing image G′ can also be photographed before or during capturing tomographic images, but it is preferred to be photographed in the end as described above because the pupil of the eye E might become miotic due to the projection of the flush light form the imaging light source103. This fundus oculi photographing image G′ is saved with tomographic images G1to G4and used as diagnostic material.

The embodiment mentioned above is comprised so as to correct the image positions of the tomographic images using the surface images of the fundus oculi Ef produced while detecting interference light LC that forms the base of the tomographic images, but it is not limited to this. For example, if the degree of discrepancy between the time when the interference light LC is detected and the time when the surface images are produced can be ignored regarding movement of the eye subject to examination E, it is possible to compose the embodiment so as to correct the image positions of the relevant tomographic images using the relevant surface images.

For example, as shown inFIG. 11, it is possible to correct the image positions of the relevant tomographic images using surface images produced with frames before and after the relevant tomographic images such as correcting the image positions of a tomographic image G2using the surface image Ef4′.

Furthermore, it is not necessary for the timing of obtaining the surface images of fundus oculi Ef and the timing of detecting the interference light LC to always coincide. For example, it is allowable for the difference in timing of movement of the eye subject to examination E to be an ignorable degree. Such difference of timing within the accepted range is referred to as “substantially simultaneous” in the present embodiment. However, it is possible to improve the precision of correction of the tomographic images based on the relevant interference light LC by simultaneously obtaining the surface images and detecting the interference light LC as in the embodiment mentioned above.

Furthermore, in the embodiment mentioned above, the ratio of the frame rate of the fundus camera unit1A and the frame rate of the OCT unit150is set to about 1:1 to 10:1, but it is not limited to this range. However, in order to secure surface images for correction of image positions of all of tomographic images, it is preferable to set the frame rate of the fundus camera unit1A above the frame rate of the OCT unit150. In particular, by setting the ratio of frame rates at 1:1, it is possible to perform an effective and efficient correction process by synchronizing the timing of imaging surface images with the timing of detecting the interference light LC.

Incidentally, in the above embodiment, the photographic timing of the surface image of the fundus oculi Ef and the detection timing of the interference light LC are synchronized, but the present invention is not limited to this. For example, it may be configured to save surface images of plurality of the fundus oculi Ef captured successively at the frame rate of the imaging devices12aon the side of the fundus camera unit1A into a memory device such as a memory together with its capturing time and to save the detection data of the interference light LC by the CCD184into the memory device together with the detection timing (detection time). Then, it is possible to configure the detecting data of each interference light LC to correct tomographic images based on that interference light LC by reading the surface image of the capturing time corresponding to the detection timing. Herein, as the “surface image of the capturing time corresponding to the detection timing of the interference light LC,” it is possible, for example, to select the surface image of the capturing time that is closest to the detection timing among a plurality of the surface images of fundus oculi Ef. This modified example is not configured to directly synchronize the photographic timing of the surface image with the detection timing of the interference light LC, but a similar advantage on the above embodiment can be obtained because the tomographic image can be corrected using the surface image obtained almost simultaneously with the tomographic image.

For example, in the above embodiment, as the low coherence light LO, near-infrared light with a wavelength of about 800 nm to 900 nm is used, but light of longer wavelengths can be used to measure images in the deeper region of the fundus oculi Ef. For example, near-infrared light of a wavelength within about 900 nm to 1000 nm is used, and also near-infrared light of a wavelength within about 1000 nm to 1100 nm can be used.

Moreover, when low coherence light L0of a wavelength within about 900 nm to 1000 nm is used, the near-infrared light of a wavelength within about 700 nm to 900 nm can be used as the illumination light for the fundus camera unit1A. Moreover, when the low coherence light LO of a wavelength within about 1000 nm to 1100 nm is used, near-infrared light of a wavelength within about 850 nm to 1000 nm can be used as the illumination light for the fundus camera unit1A. Herein, in each case, it is desirable to set a longer wavelength for the low coherence light LO than the wavelength of the illumination light of the fundus camera unit1A, but it is possible to adapt the composition such that the relationship of short and long wavelengths is reversed.

A first image forming part of the fundus observation device related to the present embodiment is not limited to a fundus camera (unit), an arbitrary ophthalmologic device capable of forming a 2-dimensional image of a fundus surface may also be applied. For example, a slit lamp (slit lamp microscopic device) may be used as a first image forming part.

Moreover, in the above embodiment, the forming process of the fundus image by the image forming part220(image forming board208) and each controlling process are operated by the controlling part210(microprocessor201, etc.), but it can be composed to operate these two processes by one or several computers.

Advantages

The fundus observation device related to the present embodiment comprises a first image forming means for forming 2-dimensional images of the surface of the fundus oculi and a second image forming means for forming tomographic images of the fundus oculi. The imaging optical system of the first image forming means forms the imaging optical path. The second image forming means generates the interference light by overlapping the signal light passing through the fundus oculi to the reference light, and forms tomographic images of the fundus oculi based on this interference light.

Optical combination and separation means operates to combine the optical path of the signal light toward the fundus oculi and the imaging optical path. The signal light irradiates onto the fundus oculi through this imaging optical path. Also, optical combination and separation means are used for separating the signal light toward the fundus oculi from the imaging optical path. The separating signal light generates the interference light by overlapping the reference light.

Such optical combination and separation means permits to capture both 2-dimensional images of the surface of the fundus oculi and tomographic images of the fundus oculi. In particular, when the illumination light from the first image forming means irradiates and the illumination from the signal light by the second image forming means irradiate simultaneously, each light through the fundus oculi is separated by the optical path combination and separation means, each light is detected so that the image is formed. Therefore, by the fundus observation device related to the present invention, it is possible to capture both 2-dimensional images of the surface of the fundus oculi and tomographic images of the fundus oculi to be captured simultaneously.

According to the fundus observation device in an aspect of the embodiment, it is possible to prevent alignment indicators from being reflected in the image of the fundus oculi because of: an alignment optical system for projecting an alignment indicator onto the eye, and EL controlling part configured to control the alignment optical system so as to terminate the projection of the alignment indicators onto the eye prior to the detection of the illumination light by the first detection part.

In addition, according to the fundus observation device in an aspect of the embodiment, it is possible to prevent alignment indicators from being reflected in the image of the fundus oculi, while the image is used for correcting the position of the tomographic image of the fundus oculi because of: an alignment optical system for projecting alignment indicators onto the eye, a detection timing controlling part configured to cause the first detection part to detect the illumination light substantially simultaneously with the detection of the interference light by the second detection part, a controlling part configured to control an alignment optical system so as to terminate the projection of the alignment indicators onto the eye prior to the detection by the first detection part, and a correction part configured to correct the image position of the tomographic image of the fundus oculi, which in turn is based on the two-dimensional image of the surface of the fundus oculi.

In addition, for the fundus observation device in an aspect of the embodiment, the detection timing controlling part operates so as to cause the first detection part to detect the illumination light at a certain period prior to and/or after the detection of the interference light by the second detection part, and the controlling part operates so as to cause the alignment optical system to project the alignment indicator onto the eye when the detection by the first detection part is operated during this time prior to and/or after the detection. Therefore, alignment indicators are reflected in the image of the surface of the fundus oculi captured at that certain time prior to and/or after the detection. The examiner can understand the state of the adjustment of the device to the eye (e.g., the state of focus or the state of the position of the device) when capturing a tomographic image by having visual contact with the alignment indicator.