JPH1014859A - Scattering reflection type image pick-up device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to obtain an image of a deep position inside an examine from the surface of the examine by providing the device with a display system which displays an image carrying information about the inside of the examine, that is obtained by a deep part scattered light detecting system which obtains the image by receiving light guided to a receiving optical system. SOLUTION: A high-directivity receiving optical system 11 is pointed toward the photographic region 10a of an examine 10, and of light beams emitted from the photographic region 10a, parallel light components that go rightward are guided to the receiving optical system 11 and received by an image pick-up sensor 12, and an image obtained is input to a data processing control part 13, where it is subjected to image processing and displayed on a display part 14. Also, a light source 15 for illuminating deep parts emits deep part illuminating light under control of the data processing control part 13, and the deep part illuminating light is guided to a plurality of optical fibers 16 and emitted from a plurality of illuminating heads 17 to illuminate the examine 10. This light illuminates the examine 10 from a sufficiently wider area than the viewing field of the receiving optical system 11, so that the light which is strong as a whole is emitted and allowed to reach the depth of the examine 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scattered-reflection type imaging apparatus for imaging, for example, a medium having a high scattering property, in particular, a living body or the like as an object, from the surface side thereof.

[0002]

2. Description of the Related Art Various studies have been made as a challenging area to image the inside of a living body or the like which is a high scattering medium with light. In particular, research on a scattering-reflection-type device that requires only disposing the device on one side of the surface of the subject has been energetically conducted due to its wide application range. As a technology that has progressed to the stage of clinical application, a so-called OCT (optical coherer) that uses a light source having low coherence to discriminate reflected light from a subject in the depth direction by measuring interference with reference light.
ence tomography, which is known to be significant in ophthalmic retinal diagnosis.

[0003] In the field of clinical diagnosis, this OCT technique can be applied to, for example, a breast diagnostic apparatus, a dermatological diagnostic apparatus, and a diagnostic apparatus for a superficial portion of a body cavity combined with a fiberscope. For example, application to non-destructive inspection such as painting and plating, appraisal of art objects, and identification of freshness of fruits can be considered.

[0004]

The problem with OCT is that in the case of a highly scattering medium such as a living body, the depth at which a sufficient amount of reflected light can be obtained is limited to at most about 1 mm. This is a factor that limits the scope of application to be extremely narrow. Particularly when considering clinical applications, the incident light intensity has an upper limit from the viewpoint of safety, and this problem is serious.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a scattered-reflection type imaging apparatus capable of obtaining an image of the inside of a subject from the surface side of the subject at a deeper position than before.

[0006]

According to the present invention, there is provided a scatter-reflection type imaging apparatus which achieves the above object. (1) Selectively receives light scattered in a subject and emitted from a surface of the subject in a predetermined direction. (2) Deep illumination light source that emits deep illumination light for illuminating the inside of the subject (3) Deep illumination light emitted from the deep illumination light source from an area wider than the field of view of the light reception optical system Illumination optical system for illuminating the inside of the subject (4) Deep scattered light detection system that receives light guided to the light receiving optical system and obtains an image bearing information inside the subject (5) Deep scattered light detection system And a display system for displaying the image obtained in step (1).

Here, the illumination optical system of (3) illuminates the subject with the illumination light emitted from the light source for deep illumination through an annular region surrounding the field of view of the light receiving optical system. You may. In the scattering / reflection imaging apparatus of the present invention, the deep scattered light detection system of (4) may include a two-dimensional imaging element for obtaining a two-dimensional image in the field of view of the light receiving optical system.

In the above-mentioned scattered reflection type imaging apparatus according to the present invention, (6) a surface illumination light source for emitting surface illumination light for illuminating an area including a field of view of a light receiving optical system on the surface of the subject; A surface scattered light detection system for receiving an image of a region including a field of view of a light receiving optical system on the surface of the object by receiving surface illumination light emitted from the light source and scattered on the surface of the object; It is preferable that the display system of (1) displays an image obtained by the deep scattered light detection system and an image obtained by the surface scattered light detection system (7) so as to overlap each other.

Further, in the scattering / reflection type imaging apparatus of the present invention, the light source for deep illumination of the above (2) emits predetermined low interference light, and the illumination optical system of the above (3) is used for the deep illumination. An optical path splitting unit for splitting the low interference light emitted from the light source into an illumination light for illuminating the subject and a predetermined reference light beam, wherein the light receiving optical system of the above (1) is provided within the field of view of the light receiving optical system. Corresponding to an arbitrary point in the two-dimensional spread of the optical path of the light scattered inside the subject and the optical path superimposing means for superimposing the optical path of the reference light beam split from the deep illumination light by the optical path dividing means. (8) between the optical path dividing means and the optical path superimposing means;
An optical path length adjustment mechanism arranged on the optical path of the reference light beam, which adjusts the optical path length of the reference light beam, and the optical path of the reference light beam is different from each other in the two-dimensional spread within the field of view of the light receiving optical system. It is also a preferable embodiment to provide a reference optical system including a scanning unit that scans the reference light beam so as to be sequentially superimposed on the optical path of the light scattered inside the subject corresponding to the point.

Further, in the scattering / reflection imaging apparatus of the present invention, the illumination optical system of (3) blocks deep illumination light between the outer edge of the field of view of the light receiving optical system and the inner edge of the annular region. It is preferable to provide a light shielding plate capable of adjusting the distance from the outer edge to the inner edge. In the conventional OCT, incident light irradiated toward the inside of the subject via the objective lens facing the subject and reflected light scattered back inside the subject come and go. Therefore, in order to increase the amount of incident light and the amount of reflected light, it is conceivable to obtain a large aperture angle using an objective lens having a large aperture. However, the use of a large-aperture objective lens increases the degree to which the wavefront is distorted due to the complex refractive index distribution in the subject,
As a result, the interference signal components having the same phase are reduced. Therefore, in the conventional OCT, it is necessary to collect at an aperture angle of about 0.1, which means that the depth at which information within the subject can be obtained including the relationship with the safety limit of the surface light intensity is 1 mm. Limited to the extent.

Since the present invention has the above-described configuration and irradiates the subject from a wide illumination area around the imaging area, the imaging area has a predetermined depth (from the surface of the object) that is deeper than before. For example, at a depth of 10 mm),
An equivalent set of light sources is generated as a result of multiple scattering within the subject. According to the present invention, of the light emitted from the equivalent light source group, light emitted from the surface of the subject substantially parallel to the light receiving optical system toward the light receiving optical system is received to obtain a transmitted light intensity distribution. As described above, in the present invention, since the subject is irradiated from a wide illumination area around the imaging area, the depth discrimination ability is somewhat sacrificed, but the safety of the surface light intensity is satisfied and the inside of the subject is satisfied. It is possible to illuminate a deeper part.

[0012]

Embodiments of the present invention will be described below. FIG. 1 shows a first embodiment of a scattered reflection type imaging apparatus according to the present invention.
It is a schematic diagram of the embodiment. Here, an example of a breast examination is given, in which a light receiving optical system 11 having high directivity is arranged toward an imaging region 10a of the breast which is the subject 10, and out of the light emitted from the imaging region 10a, The rightward parallel light component is guided to the light receiving optical system 11 and received by the image sensor 12. The image obtained by the image sensor 12 is input to the data processing / control unit 13 and subjected to appropriate image processing, and the image is displayed on the display unit 14.

The diffuse reflection type imaging apparatus shown in FIG. 1 is provided with a deep illumination light source 15 for irradiating light to a deep portion of the subject 10.
5 emits deep illumination light under the control of the data processing / control unit 13. The deep illumination light emitted from the deep illumination light source 15 is guided to a plurality of optical fibers 16 constituting an illumination optical system according to the present invention, and from a plurality of illumination heads 17 also constituting an illumination optical system according to the present invention. The emitted light illuminates the subject 10. Here, this illumination is performed by the light receiving optical system 1.
1, the subject 10 is illuminated from a region sufficiently larger than the imaging region surface 10a of the subject 10, so that the light intensity per unit area of the surface of the subject 10 is reduced, and as a whole, Intense light can be emitted, and the light reaches the deep part of the subject 10.

FIG. 2 is a schematic view of a second embodiment of the scattered reflection type imaging apparatus according to the present invention, and FIG. 3 is a schematic view showing an illumination area and an imaging area on the surface of the subject. Light source 15 for deep illumination
The deep illumination light 15a emitted from the lens is expanded by the concave lens 21 and condensed at a predetermined point in the deep part of the imaging region by the large diameter condensing lens 22 having an opening for disposing the light receiving optical system 11 in the center. The illumination area 10b of the subject 10 is illuminated in the direction.

The light incident on the inside of the subject 10 is scattered inside the subject 10, and among the scattered light, it passes through the imaging region 10 a indicated by oblique lines in FIG.
Only light (highly directional scattered light) emitted parallel to the optical axis of the light receiving optical system 11 is guided to the light receiving optical system 11, received by the image sensor 12, and converted into an image signal. A ring-shaped light shielding plate 23 is provided around the field of view of the light receiving optical system 11 for separating the deep illumination light from the path of light incident on the light receiving optical system 11. The details of the light shielding plate 23 will be described later.

Also in the embodiment shown in FIG. 2, the subject 10 is illuminated from the illumination area 10b which is sufficiently larger than the imaging area 10a as shown in FIG. The light intensity around is reduced. FIG. 4 is a configuration diagram of the light receiving optical system of the second embodiment shown in FIG. 2, and FIG. 5 is a plan view of a mirror employed in the light receiving optical system shown in FIG.

An imaging area 10a of the subject 10 (see FIG. 2)
The light emitted from the optical system enters the light receiving optical system 11 and passes through the objective lens 111. At the focal position of the objective lens 111, as shown in FIG. 5, a reflection mirror 112 configured to reflect light only at the center pinpoint 112a is provided. Of the light, only light incident parallel to the optical axis of the objective lens 111 is reflected by the reflection mirror 112. The light reflected by the reflection mirror 112 is converted into parallel light by the collimator lens 113 and enters the image sensor 12. This figure 4
In the light receiving optical system 11 shown in FIG. 2, only light emitted from the subject 10 in parallel to the optical axis is selectively guided to the image sensor 12 (see FIG. 2) by devising the reflection mirror 112.

FIG. 6 is a block diagram of another light receiving optical system which can be employed in the second embodiment shown in FIG. 2 instead of the light receiving optical system shown in FIG. On the focal plane of the objective lens 111, there is provided a pinhole plate 114 having a pinhole 114a for passing only light incident parallel to the optical axis of the objective lens 111, and light passing through the pinhole 114a is provided. The light is converted into parallel light by the collimator lens 113, is further reflected by the reflection mirror 115, and is guided to the image sensor 12 (see FIG. 2). The reflecting mirror 115 is different from the reflecting mirror shown in FIG. 5, and is a reflecting mirror that reflects incident light on the entire surface.

In the light receiving optical system shown in FIG. 6, only the light emitted from the subject 10 in parallel to the optical axis is selectively guided to the image sensor by the arrangement of the pinhole plate 114. Here, when a high scattering medium such as a living body is used as a subject,
The behavior of the irradiation light in the subject will be described. FIG.
FIG. 3 is a conceptual diagram of a multiple scattering locus of illumination light.

Here, as a representative example, the light receiving optical system 11
Of the light emitted from the subject 10 as return light parallel to the optical axis of the light beam A, which is scattered only once at the point A1 and is incident on the light receiving optical system 11, and a total of three times at the points B1, B2, and B3. Two light beams A and B, which are scattered and incident on the light receiving optical system 11, and a light beam B are shown. As in the example shown here, when the distance to the virtual light convergence point 0 to which the illumination light emitted from the illumination light-side objective lens 22 travels is sufficiently longer than the mean free path of the light incident on the subject 10, There is very little once-scattered light carrying information on a specific position in 10, that is, light that is scattered only in the hatched area in FIG.

FIG. 8 is a schematic diagram of a trajectory frequency distribution of multiple scattering in a subject, and FIG. 9 is a schematic diagram of an equivalent light source group. The hatched portions in FIG. 8 indicate regions where the frequency of multiple scattering is high, which is generally known as a result of actual measurement or simulation of various biological samples. As a result of multiple scattering having such a scattering frequency distribution, a group of light rays returning to the imaging region 10a along the optical axis, as shown in FIG.
The equivalent light source group (equivalent light source group) 20 is arranged at the position of the maximum frequency (the hatched portion in FIG. 8), and the light emitted from the equivalent light source group 20 passes through the subject surface portion 10c. It can be considered that the light is emitted from the subject 10. The depth position at which the group of transmitted light sources 20 is arranged is shown in FIG.
Varies depending on the width of the light shielding plate 23 shown in FIG. Therefore, it is preferable that a variable width light shielding plate is used as the light shielding plate 23 so that the depth position of the equivalent light source group 10 can be adjusted.

FIGS. 10 to 13 show the light shielding plate 2 respectively.
3 is a plan view in a state where the width is widened, a plan view in a state where the width of the light shielding plate is reduced, a plan view of a base annular portion constituting the light shielding plate, and AA ′ in FIG. 10. It is sectional drawing. The light shielding plate 23 includes a base annular portion 23a, and a movable split annular portion 23 divided into four parts, which is slidably attached to the base annular portion 23a in a direction indicated by an arrow in FIG.
b. FIG. 1 shows the movable split annular portion 23b.
The depth position of the equivalent light source group 20 shown in FIG. 9 can be adjusted by expanding as shown in FIG. 9 or narrowing as shown in FIG.

FIG. 14 is a schematic view of a light receiving optical system according to a third embodiment of the scattered reflection type image pickup apparatus of the present invention. Here, in addition to the optical components constituting the light receiving optical system shown in FIG. 4 and the imaging sensor 12 for obtaining an image of the inside of the subject 10, a surface illumination for illuminating the surface of the imaging region 10a of the subject 10 is provided. A light source 31, a collimating lens 32 for collimating light emitted from the surface illumination light source 31, a half mirror 33, a dichroic mirror 34, and a surface imaging sensor 35 for imaging the surface of the subject 10 are provided.

The wavelength of light emitted from the light source 13 for surface illumination is different from the wavelength of deep illumination light emitted from the light source 15 for deep illumination (see FIG. 2), and is emitted from the light source 31 for surface illumination. The light is collimated by the collimating lens 32, passes through the half mirror 33, further passes through the dichroic mirror, and passes through the lens 113 and the reflecting mirror 1.
The surface of the imaging area 10a of the subject 10 is illuminated via the lens 12 and the lens 111.

The subject 1 emitted from the surface illumination light source 31
The light reflected on the surface of the lens 111 and the reflection mirror 1
12, via the lens 113, the dichroic mirror 3
4 and reflected by the half mirror 33 are received by the surface imaging sensor 35, and an image of the surface of the subject 10 is obtained. Light emitted from the deep illumination light source 15 shown in FIG. 2, incident on the inside of the subject 10, reflected inside the subject 10, and emitted from the imaging region 10 a is, as described above,
The light is reflected by the dichroic mirror 34 via the lens 111, the reflection mirror 112, and the lens 113 and is input to the imaging sensor 12 for deep imaging.

2 obtained by the two image sensors 12 and 35
The two images are input to the data processing / control unit 13, where the two images are superimposed on each other, and the superimposed image is displayed on the display unit 14. As shown in this embodiment, by obtaining an image of the surface of the subject 10 and displaying the image superimposed on the image of the inside of the subject 10, which surface part of the subject 10 is being observed in the back image Is apparent at a glance, and the usability of the device is improved.

FIG. 15 is a schematic view of a fourth embodiment of the scattered reflection type image pickup apparatus according to the present invention. Elements corresponding to the elements constituting the previous embodiment are denoted by the same reference numerals, and different points will be described. FIG. 16 is a diagram showing the timing of illumination by the deep illumination light and the surface illumination light.

As shown in FIG. 15, in this embodiment,
Chopper 41 for chopping deep illumination light emitted from light source 15 for deep illumination, and chopper 42 for chopping surface illumination light emitted from light source 31 for surface illumination.
And control the chopping timing of the two choppers 41 and 42 and
As shown in FIG. 16, the chopper control / drive unit 43 drives the deep illumination light source 15 and the surface illumination light source 31 emitted from the deep illumination light source 15. The two choppers 41 and 42 are so arranged that the surface illumination light emitted from the
42 is controlled and driven. Light illuminated with deep illumination light and scattered inside the subject 10 and light illuminated with surface illumination light and scattered on the surface of the subject 10 are alternately incident on the imaging sensor 12. 10 deep images and surface images are obtained alternately.

As shown in this embodiment, when illumination by deep illumination light and illumination by surface illumination light are performed in a time-sharing manner,
The imaging sensor 12 can be shared. FIG. 17 is a schematic view of a fifth embodiment of the scatter reflection type imaging device of the present invention. In the present embodiment, a light source (e.g., SLD) that emits predetermined low coherence light is used as the deep illumination light source 15, and the deep illumination light emitted by the deep illumination light source 15 is A part is reflected and becomes a reference light beam. The deep illumination light transmitted through the glass plate 51 passes through an acousto-optic element (AOM) 52 that shifts the frequency of light, is spread by a concave lens 21, and illuminates the subject 10 via a condenser lens 22.

On the other hand, the reference light beam reflected by the glass plate 51 passes through another AOM 53, is reflected by a mirror 54, is further reflected by a mirror 55, and is scanned by a scanning optical system 56 so that the reference light beam The laser beam is scanned while maintaining the parallelism, and is guided to the optical sensor 121 via the half mirror 57 and further via the condenser lens 58. On the other hand, the light scattered inside the subject 10 and emitted from the imaging region 10a and incident on the light receiving optical system 11 passes through the lens 111, the reflection mirror 112 (see FIG. 5), and the lens 113, and passes through the half mirror 57. The light is transmitted, condensed by the lens 58, and enters the optical sensor 121. The optical sensor 121 is a sensor that is not spatially divided and detects the total amount of light incident thereon. In the optical sensor 121, the amount of light (light (line) indicated by a broken line in FIG. 17) of the parallel light scattered inside the subject 10 and emitted from the imaging region 10a is superimposed on the reference light beam (two AOMs 52). , 5
3 is detected as a signal having a difference frequency between the frequencies shifted by 3. Since the reference light beam is scanned by the scanning optical system 56, the spatial light intensity distribution of the light emitted from the imaging region 10a is detected in time series in synchronization with the scanning of the reference light beam by the scanning optical system 56. You. The mirror 55 is movable in the direction of the arrow shown in the figure. By moving the mirror 55, images of the subject 10 at different depths from the surface can be obtained according to the OCT principle.

[0031]

As described above, according to the scattered reflection type imaging apparatus of the present invention, it is possible to obtain an image of the subject in a deeper area than before.

[Brief description of the drawings]

FIG. 1 is a schematic view of a first embodiment of a scattered reflection type imaging apparatus according to the present invention.

FIG. 2 is a schematic diagram of a second embodiment of the scattering / reflection imaging device of the present invention.

FIG. 3 is a schematic diagram showing an illumination area and an imaging area on the surface of a subject.

FIG. 4 is a configuration diagram of a light receiving optical system according to a second embodiment shown in FIG.

FIG. 5 is a plan view of a mirror employed in the light receiving optical system shown in FIG.

FIG. 6 is a configuration diagram of another light receiving optical system that can be adopted in the second embodiment shown in FIG. 2 instead of the light receiving optical system shown in FIG. 4;

FIG. 7 is a conceptual diagram of multiple scattering trajectories of illumination light.

FIG. 8 is a schematic diagram of a frequency distribution of multiple scattering in a subject.

FIG. 9 is a schematic diagram of an equivalent light source group.

FIG. 10 is a plan view of the light shielding plate in a state where the width is increased.

FIG. 11 is a plan view of the light shielding plate in a state where the width is reduced.

FIG. 12 is a plan view of a base annular portion constituting the light shielding plate.

FIG. 13 is a cross-sectional view of the light shielding plate, taken along AA ′ of FIG. 10;

FIG. 14 is a schematic diagram of a light-receiving optical system in a third embodiment of the scattering / reflection imaging apparatus of the present invention.

FIG. 15 is a schematic diagram of a fourth embodiment of the scattering / reflection imaging device of the present invention.

FIG. 16 is a diagram showing the timing of illumination by deep illumination light and surface illumination light.

FIG. 17 is a schematic diagram of a fifth embodiment of the scattering / reflection imaging device of the present invention.

[Explanation of symbols]

 Reference Signs List 10 subject 10a imaging region 10b illumination region 11 light receiving optical system 12 imaging sensor 13 data processing / control unit 14 display unit 15 deep illumination light source 16 optical fiber 17 illumination head 20 equivalent light source group 21 concave lens 22 condensing lens 23 light shielding plate Reference Signs List 31 light source for surface illumination 32 collimator lens 33 half mirror 34 dichroic mirror 35 surface imaging sensor 41, 42 chopper 43 chopper control / drive unit 51 glass plate 52, 53 AOM 54, 55 mirror 56 scanning optical system 57 half mirror 58 lens 121 light Sensor

Claims (6)

[Claims] 1. A light receiving optical system for selectively receiving light scattered within a subject and emitted from a surface of the subject in a predetermined direction, and a deep part for emitting deep illumination light for illuminating the inside of the subject. A light source for illumination, a deep illumination light emitted from the light source for deep illumination, from a region wider than the field of view of the light receiving optical system, an illumination optical system for illuminating the inside of the subject, and the light receiving optical system. A deep scattered light detection system that receives the guided light to obtain an image carrying information on the inside of the subject; and a display system that displays an image obtained by the deep scattered light detection system. And a scattering reflection type imaging device. 2. The illumination optical system according to claim 1, wherein the illumination optical system illuminates the subject with illumination light emitted from the deep illumination light source through an annular region surrounding a field of view of the light receiving optical system. The scattered-reflection imaging device according to claim 1. 3. The scattered reflection imaging apparatus according to claim 1, wherein said deep scattered light detection system includes a two-dimensional imaging device for obtaining a two-dimensional image in a field of view of said light receiving optical system. 4. A surface illumination light source that emits surface illumination light for illuminating a region including a field of view of the light receiving optical system on the surface of the object, and is scattered on the surface of the object emitted from the surface illumination light source. A surface scattered light detection system that receives surface illumination light to obtain an image of a region including the field of view of the light receiving optical system on the surface of the subject, and wherein the display system is obtained by the deep scattered light detection system. The scattered reflection type imaging apparatus according to claim 1, wherein the obtained image and an image obtained by the surface scattered light detection system are displayed so as to be superimposed on each other. 5. The deep illumination light source emits predetermined low interference light, and the illumination optical system illuminates the inside of the subject with the low interference light emitted from the deep illumination light source. An optical path splitting unit that bisects the illumination light and a predetermined reference light beam, wherein the light receiving optical system corresponds to an arbitrary point in a two-dimensional spread within a field of view of the light receiving optical system, An optical path superposing means for superposing an optical path of light scattered inside and an optical path of a reference light beam split from the deep illumination light by the optical path splitting means, between the optical path splitting means and the optical path overlapping means, An optical path length adjustment mechanism arranged on the optical path of the reference light beam, for adjusting the optical path length of the reference light beam, and the optical path of the reference light beam has a two-dimensional spread within the field of view of the light receiving optical system. The test corresponding to different points in 2. The scattered reflection imaging apparatus according to claim 1, further comprising a reference optical system including a scanning unit that scans the reference light beam so as to be sequentially overlapped with an optical path of light scattered inside the body. 6. The illumination optical system blocks the deep illumination light between the outer edge of the field of view of the light receiving optical system and the inner edge of the annular region, and the distance from the outer edge to the inner edge can be adjusted freely. The scattered reflection type imaging apparatus according to claim 1, further comprising a light shielding plate.