JPH08247734A - Reflected light measuring instrument - Google Patents

Abstract

PURPOSE: To extract reflected light components from an observation point in distinction from multiply scattered light component by projecting two kinds of polarized light rays which are vertical and parallel to a plane containing a light receiving optical axis and light projecting optical axis in a state where the light rays can freely be switched to each other. CONSTITUTION: Light emitted from a light source 11 is condensed to an observation point R through a light projecting optical system 12 composed of a beam expanding optical system 121, polarizing plate 12, and objective lens 123. The light reflected at the point R in the direction of a light receiving optical axis 4 which is perpendicular to a light projecting optical axis 2 passes through a light receiving optical system 14 composed of an objective lens 141, polarizing plate 142, condenser lens 143, and pinhole plate 144 together with scattered light and only the light which passes through the pinhole 144a of the pinhole plate 144 is detected by means of a photodetector 13. Because of the polarizing plate 122, S-polarized light which is polarized in the direction perpendicular to a plane containing both optical axes 2 and 4 and P-polarized light which is polarized in the direction parallel to the plane is emitted from the optical system in a state where the polarized light can be switched to each other. Because of the polarizing plate 142, similarly, the S- and P-polarized light of the light made incident to the optical system 14 are emitted from the system 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflected light measuring device for measuring the amount of reflected light at an observation point inside a subject.

[0002]

2. Description of the Related Art Conventionally, the surface structure of the body surface or the inner wall of a body cavity of a subject, particularly a human body, is optically examined, and specifically, the state of the inner wall of the stomach is photographed by, for example, a gastric camera, and diagnosis is made based on the photograph And so on. In recent years, research for not only observing the surface condition of a subject such as a biological tissue or a pathological tissue sample obtained by excising it, but also optically observing the depth of the surface, that is, the inside of the subject Is being carried out. By observing not only the surface condition but also the internal condition, more information can be obtained and, for example, when applied clinically, more appropriate diagnosis can be performed.

Conventionally, CLSM (confocal scanning microscope), OCT (O
optical Coherence Tomograp
hy) is known. FIG. 9 is a diagram illustrating the principle of CLSM. A laser beam 80 having a good focusability is emitted through a pinhole 81a of the pinhole plate 81 toward a predetermined observation point R inside the subject 1 through a half mirror 82 and an objective lens 83. The reflected light from the observation point R passes through the objective lens 83, passes through the half mirror 82, and is condensed at the position of the pinhole 84a of the confocal pinhole plate 84. The reflected light at the point R ′ other than the observation point R spreads at the position of the confocal pinhole plate 84, or the pinhole 8 on the confocal pinhole plate 84.
Focus on a point other than 4a. Therefore, the reflected light from the observation point R selectively passes through the pinhole 84a. This reflected light is received by a detector (not shown). An image of the inside of the subject 1 can be obtained by scanning the subject 1 and obtaining reflected light signals at each observation point.

FIG. 10 is an explanatory diagram of the OCT apparatus. A light source that emits light with a short coherence length, such as SL in this example
D (Super Luminescent Period)
e) The light emitted from 91 is transmitted by being incident on the optical fiber 92, and is divided into the first light wave (object light) and the second light wave (reference light) by the fiber coupler 93, respectively It is transmitted by the fibers 94 and 95, and is transmitted to the subject 1 and the reference mirror 98 via the objective lens system 96 and the reference lens system 97, respectively. At this time, the reference mirror 98 is moving in the Z direction (the optical axis direction of the light beam).

Incidentally, in FIG. 10, PZT (Pi
ezo-electric Transducer) 9
9 is arranged and the frequency of the object light is shifted,
This is to enable the photodiode 101 to obtain a signal having a frequency suitable for the photodiode 101 or a signal processing system including the photodiode 101, and is necessarily required in the measurement principle of this device. In the following, the operation of PZT99 will be omitted and the case without PZT99 will be described.

The light beam applied to the subject 1 travels inside the subject, and is reflected at each point on the path of the light beam of the subject while traveling inside the subject, and the reflected light is the objective lens system 96. Incident on the optical fiber 94 via the fiber coupler 9
3 through the optical fiber 100, and then enters the photodetector, for example, the photodiode 101 in this example. Similarly, the reference light reflected by the reference mirror 98 again enters the optical fiber 95 via the reference lens system 97, the fiber coupler 93, the optical fiber 100, and the photodiode 101. To do.

FIG. 11 is a diagram showing signals obtained by the photodiode 101. The horizontal axis of this figure corresponds to the position of the reference mirror 98 in the Z direction, and since this reference mirror 98 moves in the Z direction at a constant speed, the horizontal axis of this figure is also the time axis t. The vertical axis in this figure represents the amplitude of the received light signal of the photodiode 101, and the alternate long and short dash line represents the envelope of the received light signal. This figure shows the case where reflection occurs at only one point in the subject and the reflected light and reference light transmitted to the photodiode 101 have the same intensity.

When the reference mirror 98 is continuously moved in the Z direction at a constant speed, the reference light reflected by the reference mirror 98 is
Compared with the light that has entered the reference mirror 98, its frequency is converted into light that has transitioned by the Doppler frequency. Therefore, on the photodiode 101, the reflected light and the reference light interfere with each other, and a signal having a frequency difference between the frequency of the reflected light and the frequency of the reference light is observed.

By the way, assuming that the light emitted from the SLD 91 has a short coherence length, and therefore the reflection occurs at only one point of the subject 1, the light emitted from the SLD 91 is radiated to the subject as object light. , The optical path length (optical distance) of the light reflected by a certain point in the subject to reach the photodiode 101, and emitted from the SLD 91, reflected by the reference mirror 98 and reflected by the photodiode 1 as the reference light.
The origin 0 shown in FIG. 10 is completely the same as the optical path length up to 01, and only the width (time width) in the Z direction corresponding to the coherence length of the light emitted from the SLD 91 is shown. Such a burst wave is observed. Actually, reflection occurs at various points along the optical path of the light beam that travels inside the subject 1, and by moving the reference mirror 98 in the Z direction, the reference mirror 98 at each point in time during the movement is reflected. A signal in which the information of the reflected light inside the subject corresponding to the position in the Z direction is continuously and sequentially extracted is obtained.

Application of the OCT apparatus as shown in FIG. 10 mainly to the ophthalmic field has been studied.

[0011]

In both the CLSM and OCT apparatus described above, it is not possible to detect only the reflected light that is reflected at the observation point of the subject 1 and multiplexes on the surface or inside of the subject 1. There is a problem that mixing of scattered scattered light cannot be avoided. FIG. 12 is an explanatory view schematically showing how the scattered light is mixed.

Here, as shown in FIG. 12A, light is emitted from a light source 111 toward an observation point R inside the subject 1 via an optical path 112, and reflected light reflected at the observation point R. Are again received by the photodetector 113 via the optical path 112. At this time, in addition to the reflected light reflected at the observation point R, variously scattered light variously scattered on the surface or inside of the subject 1 as shown in FIG.
And enters the photodetector 113.

FIG. 12B is a time delay frequency of the output light returning to the photodetector 113 when an extremely narrow pulsed incident light is incident on the subject 1 from the light source 111 shown in FIG. 6 is a graph schematically showing the distribution (the intensity of light detected by the photodetector 113) and the frequency of the number of times of scattering. Assuming that the time when the incident light reaches the observation point R and is reflected by the observation point R and returned to the photodetector 113 is t _o , the light incident on the photodetector 113 at the time t ₀ is Even if limited, the number of times of scattering of the incident light includes not only the reflected light reflected once at the observation point R but also the scattered light scattered multiple times at a large ratio.

In the CSLM shown in FIG. 9, there is a problem that the above-mentioned multiple scattering components cannot be removed from entering the photodetector, which causes a large measurement error. Further, in the CSLM, the objective lens 83 (see FIG. 9)
Even if the aperture angle is increased, the resolution in the optical axis direction (depth direction of the subject 1) is, for example, about several hundred μm, which is significantly inferior to the resolution in the direction orthogonal to the optical axis (for example, about 10 μm).

In the OCT apparatus shown in FIG. 10, since the interferometer is configured, it is possible to remove the influence of the multiple scattered light on the components of the multiple scattered light that do not interfere with the reference light. In this multiple scattered light,
A large proportion of the components that interfere with the reference light, which enter the photodetector at the same time (time t ₀ ) as the reflected light reflected at the observation point R, are included. There is a problem that the influence cannot be removed.
Further, in the OCT apparatus, since the scanning is performed in the optical axis direction, the aperture angle of the objective lens cannot be set large,
Only extremely weak reflected light can be obtained from the deep part of the subject.

As described above, in order to know the tissue structure inside the subject with high resolution, it is extremely important to remove the multiple scattering component from the light incident on the photodetector. In view of the above circumstances, it is an object of the present invention to provide a reflected light measuring device capable of accurately extracting a reflected light component reflected at an observation point from a multiple scattering component.

[0017]

A first reflected light measuring device of the present invention which achieves the above object is (1-1) at a predetermined observation point inside a subject in a direction along a predetermined light receiving optical axis. Receiving optical system for guiding the reflected light reflected (1-2) From a direction along an irradiation optical axis orthogonal to the above-mentioned receiving optical axis to a direction perpendicular to a plane including both the receiving optical axis and the irradiation optical axis at the observation point. Irradiation optical system for switchingably irradiating linearly polarized first polarized light and linearly polarized second polarized light in a direction parallel to the plane (1-3) of reflected light guided by a light receiving optical system Photodetector for detecting intensity (1-4) First light intensity detected by the photodetector when the observation point is illuminated with the first polarized light, and the observation point is the second Of the reflected light and the surface of the subject based on both the second light intensity when illuminated with the polarized light of It is characterized in that a reflected light extracting means for extracting the light intensity of the reflected light among the scattered light scattered on the surface or inside and incident on the light receiving optical system is provided.

Here, in the above-mentioned first reflected light measuring apparatus of the present invention, the (1-1) light receiving optical system is a first polarized light of the reflected light which is linearly polarized in a direction perpendicular to the plane. A polarized light extracting means for extracting the component may be provided. Further, the second reflected light measuring device of the present invention which achieves the above object is: (2-1) Irradiation optics for irradiating a predetermined observation point inside a subject with irradiation light from a direction along a predetermined irradiation optical axis. System (2-2) At the observation point, while guiding the reflected light reflected in the direction along the light receiving optical axis orthogonal to the irradiation optical axis, the reflected light is directed to a plane including both the irradiation optical axis and the light receiving optical axis. A light-receiving optical system that switchesably extracts a first polarized light component that is linearly polarized in a vertical direction and a second polarized light component that is linearly polarized in a direction parallel to the plane (2-3) is extracted by a light-receiving optical system. Photodetector for detecting the intensity of the polarization component of the reflected light (2-4) First light intensity detected by the photodetector when the first polarization component is incident on the photodetector, Both the second light intensity when the second polarized component is incident on the photodetector On the basis of the above, a reflected light extraction means for extracting the light intensity of the reflected light of the reflected light and the scattered light scattered on the surface or inside of the subject and incident on the light receiving optical system is provided. And

In the second reflected light measuring apparatus of the present invention, the irradiation optical system of (2-1) irradiates, as the irradiation light, first polarized light linearly polarized in a direction perpendicular to the plane. It may be one that does. In the first reflected light measuring device or the second reflected light measuring device of the present invention, the reflected light extracting means of (1-4) to (2-4) is typically the first reflected light measuring device. The calculation including the difference calculation between the light intensity of the second light intensity and the light intensity of the second light intensity is performed.

Further, in the first reflected light measuring device and the second reflected light measuring device of the present invention, each of the first optical axis and the second optical axis orthogonal to each other at a predetermined observation point inside the subject. And (2) to (2) are switchable.
-1) irradiation optical system, and the above (1-1) to (2)
-2) may be provided with the first optical system and the second optical system used as the light receiving optical system.

Further, in the first reflected light measuring device and the second reflected light measuring device of the present invention, the irradiation optical system, the light receiving optical system, and the photodetector are provided with the irradiation optical axis and the received optical axis. It may be provided with a rotating mechanism for rotating the equally divided shaft as a rotating shaft, and the second received light which is orthogonal to both the irradiation optical axis and the received optical axis at the observation point. A second light receiving optical system for guiding the reflected light reflected in the direction along the axis may be provided.

Further, the first reflected light measuring device or the second reflected light measuring device of the present invention has a light source that emits light having a predetermined coherence distance, and emits the light emitted from the light source. It may be provided with an interference optical system that divides the first light and the second light into two and makes the first light incident on the irradiation optical system and guides the second light to the photodetector. Further, in the above-mentioned first reflected light measuring device or second reflected light measuring device of the present invention, the irradiation optical system irradiates a plurality of observation points arranged one-dimensionally or two-dimensionally, and the light receiving optical system. Is provided with an imaging optical system for forming images of the plurality of observation points on the photodetector, and the photodetector detects each of the reflected light reflected at each of the plurality of observation points. It may be one.

[0023]

In the following, the principle of the present invention will be described first. FIG. 1 is a schematic diagram showing a concept of a basic arrangement of an optical system and a state of scattered light generation in the case of the arrangement of the optical system in the present invention. As shown in FIG. 1, the light emitted from the light source 11 travels along the irradiation optical axis 2 via the irradiation optical system 12 and irradiates the observation point R inside the subject 1. Observation point R
The reflected light that is reflected by and travels toward the light receiving optical axis 4 side is
It is incident on the photodetector 13 via 4. Here, the irradiation optical axis 2 and the reception optical axis 4 are orthogonal to each other at the observation point R.

Also in such an optical arrangement, as in the case described with reference to FIG. 12, the photodetector 13 displays the reflected light reflected only once at the observation point R and the surface of the subject 1. Or, scattered light that is multiply scattered inside is also incident. Figure 2
FIG. 6 is a diagram showing a reflection intensity distribution with respect to a reflection direction of linearly polarized light. When the light having the electric field E only in the vertical direction of FIG. 2, that is, the irradiation light linearly polarized in the vertical direction of FIG.
The reflected light in the plane perpendicular to the paper surface including the optical axis C of the irradiation light (or the transmitted light transmitted through the observation point R) has a certain intensity, and the reflected light is observed at the point A, for example. However, at the observation point R, the reflected light from the observation point R is not observed in the direction perpendicular to the plane, for example, the point B.

The present invention utilizes the property of the linearly polarized light described with reference to FIG. 2, and in principle, the reflected light from the observation point R and the scattered light are scattered by the arrangement of the optical system as shown in FIG. Of the light, only reflected light is extracted. The first reflected light measuring device of the present invention is a first polarized light (hereinafter, referred to as “S”) obtained by linearly polarizing the observation point R in a direction perpendicular to the paper surface of FIG.
The polarized light) and the second polarized light linearly polarized in the direction parallel to the paper surface of FIG. 1 (hereinafter, this may be referred to as “P polarized light”) are switchably emitted.

When the subject 1 is illuminated with S-polarized light,
The reflected light at the observation point R is the received light while maintaining its polarization state.
It enters the academic system 14. On the other hand, on the surface of the subject 1 or inside
Light scattered multiple times loses its polarization state. Accordingly
Then, when the subject 1 is illuminated with S-polarized light, light detection is performed.
Light intensity I detected by the device 13_S Is the reflected light at observation point R
Of the intensity detected by the photodetector 13_RS, Multiple scattering
The intensity of the minute (noise) is n _S When I said_S = I_RS+ N_S ... (1)

On the other hand, when the subject 1 is illuminated with P-polarized light, the reflection at the observation point R does not occur on the light receiving optical system side, and therefore the intensity of the reflected light at the observation point R at this time is zero. . On the other hand, the multiple scattering component (noise) still exists, and when the intensity is n _P , the light intensity I _P detected by the photodetector 13 is I _P = n _P (2)

Here, the subject 1 is S-polarized and P-polarized with the same light amount.
If polarized light is irradiated, the noise intensity n _S when _S polarized light is irradiated and the noise intensity n _P when P polarized light is irradiated.
Are considered to be equal to each other (n _S = n _P ). Therefore, when the difference ΔI between the equations (1) and (2) is calculated, ΔI = I _S −I _P = I _RS + n _S −n _P = I _RS (3), and the noise component is canceled, The light intensity I _RS due to the reflected light reflected at the observation point R is extracted.

Here, in the above-described first reflected light measuring apparatus of the present invention, when the light receiving optical system 14 is provided with polarization extracting means for extracting only the S-polarized component, such as a polarizing plate, the signal component of the formula (1) is obtained. I _RS passes through the polarized light extraction means as it is,
The noise components n _S and n _P are the noise components n _S and n.
Only the S-polarized components n _SS and n _{PS of P} pass through the polarization extracting means. Therefore, in this case, the S / N of the light itself entering the photodetector 13 is improved, and the reflection intensity I _RS at the observation point R is more accurately extracted by the above-described calculation, for example.

The second reflected light measuring apparatus of the present invention irradiates the subject 1 with irradiation light that is not in a polarized state, and the S of the light that has entered the light receiving optical system 14 is directed toward the light receiving optical system 14.
The polarization component and the P polarization component are switchably extracted and led to the photodetector 13. When the irradiation light is irradiated to the subject 1, I _R intensity of the reflected light from the observation point R, when the scattered light intensity is n, the sum of the light intensities I _R of the light incident on the light-receiving optical system 14 The + n S-polarized component I _S can represent I _S = I _RS + n _S (4). As described with reference to FIG. 2, the reflected light incident on the light receiving optical system already has only the S-polarized component, and therefore I _R = I _RS . On the other hand, the P polarization component I _P of the total light intensity I _R + n of the light incident on the light receiving optical system is
Since there is no P-polarized component of the reflected light, I _P = n _P (5) Again, it is considered that n _S = n _P. Therefore,
When the difference ΔI between the equations (4) and (5) is calculated, ΔI = I _S −I _P = I _RS + n _S −n _P = I _RS (6), which is the first aspect of the present invention described above. Similar to the reflected light measuring device, the scattered light component is canceled and only the reflected light component from the observation point P is extracted.

Here, as described above, since the reflected light from the observation point R to the light receiving optical axis 4 side is only the S polarization component,
Originally, it is not necessary to irradiate the subject 1 with the P-polarized component,
The irradiation light may be S-polarized light. In that case, the ratio of scattered light intensity n is reduced with respect to the reflection intensity I _P from the observation point P, originally incident light of high S / N to the optical detector 13,
Therefore, the reflected light intensity at the observation point R is extracted with higher accuracy.

[0032]

Embodiments of the present invention will be described below. FIG. 3 is a configuration diagram of the first embodiment of the reflected light measuring apparatus of the present invention. The light emitted from the light source 11 passes through the irradiation optical system 12 including the beam expanding optical system 121, the polarizing plate 122, and the objective lens 123, and is condensed at the observation point R. At the observation point R, the reflected light reflected in the direction of the light receiving optical axis 4 orthogonal to the irradiation optical axis 2 is transmitted from the objective lens 141, the polarizing plate 142, the condenser lens 143, and the pinhole plate 144 together with the scattered light (not shown). The light that has passed through the light receiving optical system 14 and has passed through the pinhole 144a is detected by the photodetector 13.

In this embodiment, the polarizing plate 122 constituting the irradiation optical system 12 is S polarized in a direction perpendicular to the paper surface of FIG.
The polarized light and the P-polarized light polarized in the direction parallel to the paper surface of FIG. 3 can be freely rotated by 90 ° so as to be switchably emitted from the irradiation optical system 12. Further, in the present embodiment, the polarizing plate 142 that constitutes the light receiving optical system 14 is also
The S-polarized component of the light incident on the light receiving optical system 14,
The P-polarized component is configured to be freely rotatable by 90 ° so as to be emitted from the light receiving optical system 14. As described above, the embodiment shown in FIG. 3 is an embodiment of the first reflected light measuring device of the present invention because the polarizing plate 122 on the irradiation optical system side can be rotated.
At the same time, the polarizing plate 142 on the light receiving optical system side can be rotated, which is also an embodiment of the second reflected light measuring apparatus of the present invention.

When the reflected light measuring device shown in FIG. 3 is used as the first reflected light measuring device of the present invention, the S-polarized light component is emitted from the polarizing plate 142 of the light receiving optical system side. The orientation is fixed, and the rotation angle of the polarizing plate 122 on the irradiation optical system side is alternately changed to the direction in which the S-polarized component is emitted and the direction in which the P-polarized component is emitted,
The light intensity is measured by the photodetector 13 each time. The measured light intensity is input to the reflected light extraction unit 15. The reflected light extraction unit 15 further calculates the average of the difference calculation described above, and thereby obtains the intensity of the reflected light at the observation point R.

When the reflected light measuring device shown in FIG. 3 is used as the second reflected light measuring device of the present invention, the polarizing plate 122 on the irradiation optical system side emits the S-polarized component from the polarizing plate 122. And the rotation angle of the polarizing plate 142 on the light receiving optical system side is the direction in which the S-polarized component is emitted,
The rotation angle is alternately changed in the direction in which the P polarization component and the P polarization component are emitted, and the same detection and calculation as described above are performed.

Here, the portion of the reflected light measuring device shown in FIG. 3 excluding the reflected light extracting portion 15 is the irradiation optical axis 2 and the received optical axis 4.
It is configured to be rotatable about an axis that bisects and as a rotation axis, detection at a large number of rotation angles and difference calculation are performed, and an average value of the differences at the large number of rotation angles is obtained. The error factors different from each other in the part deviating from R are equalized, and only the reflected light information from the observation point R can be obtained with higher accuracy.

When the subject 1 can be rotated, instead of rotating the device, the subject 1 is always observed at the observation point R by the irradiation optical axis 2 and the receiving optical axis 4. You may rotate so that it may correspond to the intersection of. By the way, on the light receiving optical system side, S
It is necessary to extract the polarized component or the P polarized component, but on the irradiation optical system side, S from the light emitted from the light source 11 is extracted.
It is not necessary to "extract" the polarized component or the P polarized component,
Instead of providing the polarizing plate 122, as the light source 11,
For example, an S-polarized light and a P-polarized light may be obtained by using a light source that originally emits linearly polarized light, such as a semiconductor laser, and rotating the light source by 90 ° about the irradiation optical axis 2, or as shown in the drawing. The linearly polarized light emitted from the light source 11 or the linearly polarized light emitted from the polarizing plate 122 is provided by rotating the 1/2 wavelength plate about the irradiation optical axis 2 as a center. The direction of the polarized light may be adjusted to S-polarized light or P-polarized light.

In FIG. 4, the focal point of the irradiation light emitted from the irradiation optical system (focus of the objective lens 121) and the observation point R (focus of the objective lens 141) gazed by the light receiving optical system are matched with high accuracy. It is a schematic diagram of the optical system which can be made. In FIG. 4, the optical system is configured such that the aperture angle of the irradiation optical system 12 is larger than the aperture angle of the light receiving optical system 14, and the irradiation optical system 12 having a large aperture angle is arranged in the extending direction of the irradiation optical axis 2. Moving mechanism 125 for finely moving (in the direction of arrow D in the figure)
Is provided. By finely moving the irradiation optical system having a large opening angle in the direction of the arrow D by the moving mechanism 125, the focal point of the irradiation optical system 12 and the focal point of the light receiving optical system 14 can be accurately matched.

Although FIG. 4 shows an example in which the aperture angle of the irradiation optical system 12 is larger than the aperture angle of the light receiving optical system 14, the aperture angle of the light receiving optical system 14 is larger than the aperture angle of the irradiation optical system 12. May be configured larger. At that time, the light receiving optical system 14 having a larger aperture angle is finely moved in the direction along the light receiving optical axis 4. FIG. 5 is a schematic diagram of a second embodiment of the reflected light measuring device of the present invention.

Compared to the first embodiment shown in FIG. 3, the second embodiment is provided with reflecting mirrors 16 and 17 and a double-sided reflecting mirror 18, and the double-sided reflecting mirror 18 is shown by a solid line in FIG. The double-sided reflection mirror 18 can be freely rotated between the rotation position and the rotation position indicated by the broken line. When the double-sided reflection mirror 18 is rotated to the position indicated by the broken line, the irradiation optical system 12 and the light receiving optical system 1
The roles of 4 change. Therefore, in the case of the second embodiment, the difference obtained in the mode of irradiating from the left side of the drawing and receiving the light on the right side of the drawing without rotating the device or the subject 1,
The average value with the difference obtained in the mode of irradiating from the right side of the drawing and receiving on the left side can be obtained, and compared with the case of not rotating the device or the subject 1 in the first embodiment shown in FIG. It can be extracted with higher accuracy.

FIG. 6 is a diagram showing the optical axis in the third embodiment of the reflected light measuring apparatus of the present invention. Here, the optical system itself is not shown in order to avoid complication of illustration. Three-dimensionally, there are three optical axes 21, 22, 23 that are orthogonal to each other at the observation point R of the subject 1, as shown in FIG. Therefore, by using one of them as the irradiation optical axis and the remaining two as the reception optical axis, it is possible to obtain information of reflection in two directions by one measurement, and It doubles and the measurement accuracy improves. Furthermore, if any one of these three optical axes 21, 22, 23 is used as an irradiation optical axis and the other two are used as a light receiving optical axis, it is switchable so that measurement accuracy can be improved. Can be further improved. Furthermore, the device or the subject 1 is connected to the normal line 30 passing through the observation point R.
If it is configured to be rotatable about the rotation axis, the measurement accuracy can be further improved.

FIG. 7 is a block diagram of the fourth embodiment of the reflected light measuring apparatus of the present invention. Compared to the first embodiment shown in FIG. 3, half mirrors 20 and 22 are provided, and a reflection mirror 2 is further provided.
1 is provided. Furthermore, in the fourth embodiment, as the light source 11, a light source that emits light with a short coherence length, for example, an SLD is used. The light emitted from the light source 11 is
The light 5 for irradiating the subject 1 with the half mirror 20,
Reference light 6 guided to the photodetector 13 without passing through the subject 1
Is divided into two. The reference light 6 is further reflected by the reflection mirror 21, and is combined by the other half mirror 22 with the light that has entered the light receiving optical system 14 via the subject 1 and enters the photodetector 13. Here, the light path length until the light emitted from the light source 11 passes through the half mirror 20 and enters the photodetector 13 via the observation point R, and the light incident from the light source 11 is reflected by the half mirror 20 and is referred to. To match the optical path length until the light 6 is incident on the photodetector 13,
The position of the reflection mirror 21 is adjusted by the optical path length adjusting mechanism 23.

In the fourth embodiment, an interferometer is constructed and light having a short coherence length is used. Therefore, as described with reference to FIGS. Then, of the light that has entered the light receiving optical system 14 and has further passed through the polarizing plate 142, only the component that interferes with the reference light is extracted. This interfering component includes the reflected light from the observation point R as it is, and the scattered light is a part of the scattered light.
Since only the interfering component is detected, a signal with a high S / N is detected before performing the above-mentioned difference calculation, and therefore, in combination with the above-mentioned difference calculation, a higher precision measurement is performed.

FIG. 8 is a block diagram of the fifth embodiment of the reflected light measuring apparatus of the present invention. In the fifth embodiment, the two-dimensional array sensor 13A in which the photosensors are two-dimensionally arranged is adopted as the photodetector, and the pin on the front surface of the photodetector is compared with the first embodiment shown in FIG. Hall plate 144 (see FIG. 3)
Has been removed. The light-receiving optical system 14 shown in the fifth embodiment, instead of the focal point R ₀ by the irradiation optical system 12, staring the observation point R of deviation slightly irradiation optical system 12 than the focal point R ₀ There is. Further, the light receiving optical system 14 is
An image of a two-dimensional plane centered on the observation point R is formed on the two-dimensional array sensor 13A.

In the fifth embodiment, with the above configuration,
The two-dimensional array sensor 13A can detect the reflection intensities of a large number of points on the plane with the observation point R as the center, as the observation points. The present invention, when trying to know the two-dimensional planar reflection distribution in the subject, configured to obtain the reflection information of one observation point at a time, it is also possible to obtain a two-dimensional image by scanning,
As shown in the embodiment of FIG. 8, a two-dimensional reflection distribution of each point can be obtained at once without scanning.

Further, for example, in the first embodiment shown in FIG. 3, a cylindrical lens or the like is arranged to irradiate each linear point including the observation point R and extending in the direction perpendicular to FIG.
The reflected light from each of these points is detected simultaneously by using a photodetector in which photosensors are arranged one-dimensionally in a direction perpendicular to the paper surface of FIG. It is also possible to obtain reflection information at the observation point. In this case, it goes without saying that necessary changes such as changing the pinhole plate 144 to a slit plate in which slits extending in the direction perpendicular to the paper surface of FIG. 3 are formed.

As described above, the reflected light measuring device of the present invention is
It can be configured to obtain the reflection information of one observation point at a time, or it can be configured to obtain the reflection information of many observation points lined up on a straight line at a time. It can also be configured to obtain the reflection information of the observation point.

[0048]

As described above, according to the reflected light measuring apparatus of the present invention, the information of the reflected light from the observation point inside the object is scattered light which is multiply scattered on the surface of the object or inside the object. Can be separated and extracted with high accuracy.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a concept of a basic optical system arrangement and a state of scattered light generation in the case of the optical system arrangement in the present invention.

FIG. 2 is a diagram showing a reflection intensity distribution with respect to a reflection direction of linearly polarized light.

FIG. 3 is a configuration diagram of a first embodiment of a reflected light measuring device of the present invention.

FIG. 4 is a condensing point of irradiation light emitted from the irradiation optical system,
FIG. 3 is a schematic diagram of an optical system capable of highly accurately matching an observation point R to which a light receiving optical system gazes.

FIG. 5 is a schematic view of a second embodiment of the reflected light measuring device of the present invention.

FIG. 6 is a diagram showing an optical axis in a third embodiment of the reflected light measuring device of the invention.

FIG. 7 is a configuration diagram of a fourth embodiment of the reflected light measuring apparatus of the present invention.

FIG. 8 is a configuration diagram of a fifth embodiment of the reflected light measuring apparatus of the present invention.

FIG. 9 is a diagram illustrating the principle of CLSM.

FIG. 10 is an explanatory diagram of an OCT apparatus.

11 is a diagram showing signals obtained by a photodiode in the OCT apparatus shown in FIG.

FIG. 12 is an explanatory diagram schematically showing how scattered light is mixed.

[Explanation of symbols]

 1 Subject 2 Irradiation Optical Axis 4 Receiving Optical Axis 11 Light Source 12 Irradiation Optical System 13 Photodetector 14 Light Receiving Optical System 122, 142 Polarizing Plate R Observation Point

Claims (10)

[Claims] 1. A light receiving optical system that guides reflected light reflected at a predetermined observation point inside a subject in a direction along a predetermined light receiving optical axis, and from a direction along an irradiation optical axis orthogonal to the light receiving optical axis, At the observation point, first polarized light linearly polarized in a direction perpendicular to a plane including both the light receiving optical axis and the irradiation optical axis, and second polarized light linearly polarized in a direction parallel to the plane,
An irradiation optical system that emits light in a switchable manner, a photodetector that detects the intensity of the reflected light guided by the light receiving optical system, and the observation point detected by the photodetector is the first polarized light. On the basis of both the first light intensity when illuminated with and the second light intensity when the observation point is illuminated with the second polarized light. A reflected light measuring device comprising: a reflected light extracting unit that extracts a light intensity of the reflected light out of scattered light that is scattered on the surface or inside and is incident on the light receiving optical system. 2. The light receiving optical system according to claim 1, further comprising polarization extracting means for extracting a first polarization component of the reflected light, which is linearly polarized in a direction perpendicular to the plane. Reflected light measuring device. 3. An irradiation optical system for irradiating a predetermined observation point inside the subject with irradiation light from a direction along a predetermined irradiation optical axis, and a light reception optical axis orthogonal to the irradiation optical axis at the observation point. A first polarization component linearly polarized in a direction perpendicular to a plane including both the irradiation light axis and the received light axis of the reflected light while guiding the reflected light reflected in the direction along the direction, and a direction parallel to the plane. A light receiving optical system for extracting the second polarization component linearly polarized in a switchable manner, a photodetector for detecting the intensity of the polarization component of the reflected light extracted by the light receiving optical system, and the photodetector. Of the detected first light intensity when the first polarized component is incident on the photodetector and the second light intensity when the second polarized component is incident on the photodetector. Based on both of them, the reflected light is scattered on the surface or inside of the subject. A reflected light measuring device comprising: a reflected light extracting unit that extracts a light intensity of the reflected light out of scattered light that is disturbed and enters the light receiving optical system. 4. The irradiation optical system, as the irradiation light,
The reflected light measuring device according to claim 3, wherein the reflected light measuring device emits linearly polarized first polarized light in a direction perpendicular to the plane. 5. The reflected light extraction means performs a calculation including a difference calculation between the first light intensity and the second light intensity. The reflected light measuring device according to item 1. 6. A first optical axis and a second optical axis that are orthogonal to each other at a predetermined observation point inside the subject, and are switchably used as the irradiation optical system and the light receiving optical system. The reflected light measuring device according to claim 1 or 3, further comprising a first optical system and a second optical system. 7. A rotating mechanism for rotating the irradiation optical system, the light receiving optical system, and the photodetector with an axis bisecting the irradiation optical axis and the light receiving optical axis as a rotation axis. The reflected light measuring device according to claim 1 or 3, further comprising: 8. A second light receiving optical system for guiding the reflected light reflected at the observation point in a direction along a second light receiving optical axis orthogonal to both the irradiation light axis and the light receiving optical axis. The reflected light measuring device according to claim 1 or 3, characterized in that. 9. A light source that emits light having a predetermined coherence length, and the light emitted from the light source is a first light and a second light.
4. The interference optical system for splitting the first light into the irradiation optical system and guiding the second light to the photodetector is divided into two. Reflected light measuring device. 10. The irradiation optical system irradiates a plurality of observation points arranged one-dimensionally or two-dimensionally with light, and the light-receiving optical system displays images of the plurality of observation points on the photodetector. 4. An image forming optical system for forming an image, wherein the photodetector detects each of the reflected lights reflected at each of the plurality of observation points. Reflected light measuring device.