JP2002221488A - Sensor using total reflection attenuation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor using total reflection attenuation for detecting a refractive index of a specimen wherein generation of distortion of an image to examine distribution of the refractive index is prevented. SOLUTION: The sensor comprises a dielectric block 11, a thin film layer 13 which is formed on one face of the dielectric block 11 and brought into contact with the specimen 15, a light source 16 generating a light beam L, an incidence optical system 17 which emits the light beam L to the dielectric block 11 in a parallel light state so that total reflection conditions may be obtained and that the total reflection attenuation may be generated on an interface 11a between the dielectric block 11 and the thin film layer 13, and a light detecting means 23 which detects an image formed by the light beam L totally reflected from the interface 11a and detects distribution of the refractive index of the specimen 15 in a face along with the interface 112a, wherein a compensating optical system 21 comprising, for example, a dielectric block similar to the dielectric block 11 is provided, and the distortion of the image caused by the dielectric block 11 when an angle of incidence θof the light beam L changes is compensated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor utilizing attenuated total reflection, such as a surface plasmon sensor for detecting the refractive index of a sample by utilizing the generation of surface plasmons. The present invention relates to a sensor using attenuated total reflection for detecting a refractive index distribution of the light.

[0002]

2. Description of the Related Art In a metal, free electrons vibrate collectively to generate a compression wave called a plasma wave. And, the quantization of this compression wave generated on the metal surface is
It is called surface plasmon.

Conventionally, various surface plasmon sensors for quantitatively analyzing a substance in a sample by using the phenomenon that surface plasmons are excited by light waves have been proposed.
Among them, a particularly well-known one uses a system called a Kretschmann configuration (see, for example, JP-A-6-167443).

A surface plasmon sensor using the above-described system basically includes, for example, a dielectric block formed in a prism shape, a metal film formed on one surface of the dielectric block and brought into contact with a sample, and a light beam. A light source to be generated, and the above light beam with respect to a dielectric block, is in a condition of total reflection at an interface between the dielectric block and the metal film, and
An optical system for making incident so that various incident angles including surface plasmon resonance conditions can be obtained, and light detecting means for measuring the intensity of the light beam totally reflected at the interface to detect the state of surface plasmon resonance It becomes.

In the surface plasmon sensor having the above structure, when a light beam is incident on a metal film at a specific incident angle θ _SP equal to or larger than the total reflection angle, an evanescent wave having an electric field distribution is present in a sample in contact with the metal film. Is generated, and surface plasmons are excited at the interface between the metal film and the sample by the evanescent wave. When the wave number vector of the evanescent light is equal to the wave number of the surface plasmon and the wave number matching is established, both are in a resonance state, and the energy of light is transferred to the surface plasmon. The intensity of the reflected light is sharply attenuated. This attenuation of light intensity is generally detected as a dark line by the light detection means.

FIG. 2 schematically shows the relationship between the incident angle θ and the reflected light intensity I when this total reflection attenuation phenomenon occurs. The incident angle θ _SP shown here is equal to the total reflection attenuation (A
TR) occurs.

[0007] The above resonance occurs only when the incident beam is p-polarized. Therefore, it is necessary to set in advance so that the light beam is incident as p-polarized light.

When the wave number of the surface plasmon is known from the incident angle θ _{SP at} which the attenuated total reflection (ATR) occurs, the dielectric constant of the sample is obtained. That is, the wave number of the surface plasmon is K
_{When SP} and the angular frequency of the surface plasmon are ω, c is the speed of light in vacuum, ε _m and ε _s are the metal and the dielectric constant of the sample, respectively, there is the following relationship.

[0009]

(Equation 1) If the dielectric constant ε _s of the sample is known, the concentration of the specific substance in the sample can be determined based on a predetermined calibration curve or the like, so that by knowing the incident angle θ _{SP at} which the reflected light intensity decreases, the A specific substance can be quantitatively analyzed.

As similar sensors utilizing attenuated total reflection (ATR), for example, “Spectroscopy”, Vol. 47, No. 1 (1998), pp. 21-23 and 26-27.
A leak mode sensor described on the page is also known. This leak mode sensor is basically formed of, for example, a dielectric block formed in a prism shape, a clad layer formed on one surface of the dielectric block, and formed on the clad layer and brought into contact with a sample. An optical waveguide layer, a light source for generating a light beam, and the light beam with respect to the dielectric block, a condition of total reflection is obtained at an interface between the dielectric block and the cladding layer, and the light is guided by the optical waveguide layer. An optical system that enters at various angles so that total reflection attenuation can occur due to wave mode excitation, and the intensity of the light beam totally reflected at the interface is measured to determine the excited state of the waveguide mode, that is, the total reflection attenuation state. And a light detecting means for detecting.

In the leakage mode sensor having the above configuration,
When the light beam is incident on the cladding layer through the dielectric block at an incident angle equal to or greater than the total reflection angle, only light having a specific wave number at a specific incident angle is transmitted through the cladding layer. The light propagates in a guided mode. When the waveguide mode is excited in this way, most of the incident light is taken into the optical waveguide layer, so that total reflection attenuation occurs in which the intensity of light totally reflected at the interface sharply decreases.
Since the wave number of the guided light depends on the refractive index of the sample on the optical waveguide layer, the refractive index of the sample and the characteristics of the sample related thereto are analyzed by knowing the specific incident angle at which the total reflection attenuation occurs. be able to.

Conventionally, it has been considered to apply the above-mentioned surface plasmon sensor or leak mode sensor to measure the in-plane refractive index distribution along the interface of the sample. That is, taking the case of a surface plasmon sensor as an example, the relationship between the incident angle of the light beam with respect to the interface and the intensity of the total reflection light is as schematically shown in FIG. Here, what is indicated by θ _SP is the total reflection elimination angle. When the refractive index of the sample changes, the relationship changes in a manner that the sample moves in the horizontal axis direction in the same figure. Therefore, when the light beam is incident on the interface at an incident angle near the total reflection elimination angle θ _SP , the total reflection light Changes according to the refractive index of the sample. Therefore, if a parallel beam having a somewhat wide beam cross section is used as the light beam in this case, and an image of the light beam totally reflected at the interface (that is, the intensity distribution in the beam cross section) is detected, the surface along the interface is detected. The refractive index distribution of the sample in the inside can be detected.

The above is different for the leaky mode sensor, except that the total reflection attenuation is caused not by surface plasmon resonance but by the excitation of the guided mode in the waveguide layer. It is also possible to obtain the refractive index distribution of the sample in the same manner by applying a leak mode sensor.

[0014]

By the way, in the conventional sensor utilizing the attenuated total reflection in which the refractive index distribution of the sample is detected as described above, the image due to the totally reflected light is distorted. In some cases, the measurement accuracy of the refractive index distribution was impaired.

In view of the above circumstances, the present invention provides a surface-type sensor utilizing attenuated total reflection which can eliminate distortion of an image due to total reflection light and can obtain a refractive index distribution of a sample with high accuracy. The purpose is to provide.

[0016]

A sensor utilizing attenuated total reflection according to the present invention comprises a dielectric block as described above, and a thin film layer formed on one surface of the dielectric block and brought into contact with a sample. A light source that generates a light beam, and an incident light beam that is incident on the dielectric block in a parallel light state such that a total reflection condition is obtained at an interface between the dielectric block and the thin film layer. Optics,
A sensor using attenuated total reflection, comprising: a light detection unit that detects an image formed by a light beam totally reflected at the interface and detects a refractive index distribution of the sample in a plane along the interface. An adaptive optics system is provided for compensating for image distortion caused by the dielectric block when the angle of incidence of the beam changes.

Further, another sensor utilizing attenuated total reflection according to the present invention is particularly configured as the above-mentioned surface plasmon sensor, and includes a dielectric block and a sample formed on one surface of the dielectric block and applied to a sample. A thin film layer made of a metal film to be contacted, a light source for generating a light beam, and the light beam being applied to the dielectric block with respect to the dielectric block at an interface between the dielectric block and the thin film layer made of the metal film. As a result, an incident optical system for entering in a parallel light state and an image by a light beam totally reflected at the interface are detected, and a refractive index distribution of the sample in a plane along the interface is detected. In a sensor using a total reflection attenuation by surface plasmon resonance, comprising a light detection means,
An adaptive optics system is provided for compensating for image distortion caused by the dielectric block when the angle of incidence of the light beam changes.

Further, another sensor utilizing attenuated total reflection according to the present invention is particularly configured as the aforementioned leak mode sensor, and includes a dielectric block and a clad formed on one surface of the dielectric block. A thin film layer comprising a layer and an optical waveguide layer formed thereon, a light source for generating a light beam, and the light beam with respect to the dielectric block, at an interface between the dielectric block and the cladding layer. In order to obtain the condition of total reflection, an incident optical system that makes incident in a parallel light state and an image formed by a light beam totally reflected at the interface are detected, and the refractive index distribution of the sample in a plane along the interface is detected. In the sensor using the total reflection attenuation due to the excitation of the waveguide mode in the waveguide layer, comprising: It is characterized in that the compensation optical system for compensating for image distortion caused I is provided.

The above-described adaptive optics system is provided, for example, in the plane of incidence of the light beam incident on the interface (the plane containing the normal of the interface and the wavefront normal of the light beam). A compensating dielectric block having the same cross-sectional shape as the cross-sectional shape, and formed of a material having the same refractive index as the dielectric block, and arranged so that a light beam emitted from the dielectric block enters; And a screen for image observation formed on a surface of the compensation dielectric block corresponding to one surface of the dielectric block. The screen can be formed from, for example, a diffuser or a phosphor.

On the other hand, the dielectric block can be formed as a single block having all of the incident end face and the output end face of the light beam and the surface on which the thin film layer is formed. Is also such a configuration.

Alternatively, the dielectric block comprises a portion having an incident end face and an outgoing end face of a light beam, and a portion having a surface on which the thin film layer is formed, joined through a refractive index matching means. It may be. In that case, the compensation dielectric block also has such a configuration.

[0022]

According to the study of the present inventors, in the conventional surface-type sensor using attenuated total reflection, the image caused by the total reflection light is distorted because of the progress of the total reflection light traveling through the dielectric block. This is because the angle and the traveling angle of the light incident on the detection surface of the light detection means are different. Even if the installation angle of the light detection means is adjusted so as to eliminate the distortion, if the incident angle of the measurement light changes, the image on the detection surface of the light detection means will also be distorted. The change in the incident angle always occurs, for example, when scanning the incident angle of the measurement light in order to measure substances having different incident angle conditions of the total reflection attenuation.

In the sensor utilizing the attenuated total reflection of the present invention, a compensation optical system for compensating for the image distortion caused by the dielectric block when the incident angle of the light beam with respect to the interface between the dielectric block and the thin film layer changes. With the provision, the distortion of the image can be eliminated, and the refractive index distribution of the sample can be measured with high accuracy.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a schematic side view of a sensor using attenuated total reflection according to a first embodiment of the present invention.

The device of the present embodiment is formed as the above-mentioned surface plasmon sensor.
A transparent dielectric prism 11 formed, for example, in a triangular prism shape using a synthetic resin such as PMMA or an optical glass such as BK7;
For example, gold formed on the upper surface of the dielectric prism 11,
And a metal thin film 13 made of silver, copper, aluminum, or the like. The sample 15 to be analyzed is disposed on the metal thin film 13.

A laser light source 16 for emitting a light beam L
A collimator lens 17 for collimating the light beam L emitted in a divergent light state, a compensating dielectric prism 21 for compensating image distortion described later, and an imaging lens 22
And a CCD area sensor 23 as light detecting means. A diffusion film 24 forming a screen for image observation is formed on one surface 21a of the compensation dielectric prism 21, which is the lower surface in the figure.

The operation of the surface plasmon sensor having the above configuration will be described below. After being emitted from the laser light source 16, the collimated light beam L collimated by the collimator lens 17 enters the dielectric prism 11, and is collided with a metal thin film.
The light enters the interface 11a with the substrate 13. At this time, the incident angle θ of the light beam L with respect to the interface 11a is set to a value within a range where the condition of total reflection can be obtained at the interface 11a and surface plasmon resonance can occur.

In this embodiment, an incident optical system is constituted by the collimator lens 17. The light beam L is
It is necessary to enter the interface 11a with p-polarized light. To do so, the direction of the laser light source 16 may be set in advance in such a manner. In addition, the direction of polarization of the light beam L may be controlled by a wave plate or a polarizing plate.

The light beam L incident on the interface 11a is totally reflected there, and the totally reflected light beam L is emitted from the dielectric prism 11. The light beam L emitted from the dielectric prism 11 enters the compensating dielectric prism 21 and is totally reflected at the interface between the compensating dielectric prism 21 and the diffusion film 24. The evanescent light is diffused by the diffusion film 24. Therefore, an image is formed on the diffusion film 24 by the light beam L. This image is formed by the imaging lens 22 into C
An image is formed on the imaging surface of the CD area sensor 23 and is imaged.

As described above, when the light beam L is totally reflected at the interface 11a, an evanescent wave seeps from the interface 11a to the metal thin film 13 side. When the light beam L is incident on the interface 11a at a specific incident angle θ _SP , the evanescent wave resonates with the surface plasmon that is excited on the surface of the metal thin film 13. I decays sharply. That is, the relationship between the incident angle θ of the light beam L with respect to the interface 11a and the intensity of the total reflected light is as schematically shown in FIG. Here, what is indicated by θ _SP is the total reflection elimination angle.

This relationship changes as the refractive index of the sample 15 changes so as to move in the horizontal axis direction in the figure, so that the intensity of the totally reflected light beam L changes according to the refractive index of the sample 15. Therefore, the image formed by the diffusion film 24 and captured by the CCD area sensor 23, that is, the intensity distribution in the beam cross section of the totally reflected light beam L indicates the refractive index distribution of the sample 15 in a plane along the interface 11a. It will be.

Therefore, if the image signal S output from the CCD area sensor 23 is input to image display means such as a CRT or a liquid crystal display panel, and an image based on the image signal S is reproduced and displayed, the refractive index distribution of the sample 15 is reduced. Can be observed. Further, the video signal S can be input to an optical scanning recording device or the like, and an image based on the video signal S can be reproduced as a hard copy.

It is to be noted that a diffusion plate, a fluorescent plate, or the like may be provided instead of the diffusion film 24 so that an image formed by the light beam L can be observed.

Here, as described in detail above, the interface 11
When the angle of incidence θ of the light beam L with respect to a changes, the optical path of the light beam L in the dielectric prism 11 changes, which may cause distortion in the image formed by the light beam L totally reflected at the interface 11a. Hereinafter, a description will be given of how to eliminate the image distortion.

The compensating dielectric prism 21 is formed of the same material as the dielectric prism 11, and has a plane of incidence of the light beam L with respect to the interface 11a (the normal to the interface 11a and the wavefront normal to the light beam L). (A plane including the same) has the same cross-sectional shape as the cross-sectional shape of the dielectric prism 11. The compensating dielectric prism 21 is arranged such that the light beam L emitted from the dielectric prism 11 is incident along the same optical path as when the light beam L is incident on the dielectric prism 11. By arranging the compensating dielectric prism 21 in this manner, the image carried by the light beam L on one surface 21a (which corresponds to the surface forming the interface 11a of the dielectric prism 11) is provided. Is obtained by compensating for image distortion due to the change in the optical path.

Therefore, the diffusion film on the prism surface 21a
If the image formed by 24 is captured by the CCD area sensor 23 and the image is used, the refractive index distribution can be accurately obtained.

Next, a second embodiment of the present invention will be described with reference to FIG. In FIG. 3, elements that are the same as the elements in FIG. 1 are given the same reference numerals, and descriptions thereof will be omitted unless otherwise necessary (the same applies hereinafter).

The sensor using the attenuated total reflection according to the second embodiment is also a surface plasmon sensor. In this device, a sensing medium 14 is fixed on a dielectric prism 11 as compared with the sensor of FIG. The difference is that the sample 15 is placed on it, and the other points are basically the same as those in FIG.
The configuration is the same as that of the device.

The sensing medium 14 binds to a specific substance in the sample 15 to be analyzed. Examples of such a combination of the specific substance and the sensing medium 14 include an antigen and an antibody.

In this configuration, the refractive index of the sensing medium 14 changes according to the binding state between the specific substance in the sample 15 and the sensing medium 14. Therefore, prism surface 21
The image formed by the diffusion film 24 on the surface a is captured by the CCD area sensor 23, and if the image is used, the refractive index distribution of the sensing medium 14, that is, the coupling between the specific substance in the sample 15 and the sensing medium 14 is obtained. The distribution of states can be determined. In this case, the sample 15 and the sensing medium 14 are the samples targeted by the apparatus of the present invention.

In this embodiment, the provision of the compensating dielectric prism 21 also provides a distortion of the image caused when the incident angle θ of the light beam L with respect to the interface 11a changes, as in the first embodiment. Can be eliminated.

Next, a third embodiment of the present invention will be described with reference to FIG. The sensor using the attenuated total reflection according to the third embodiment is also a surface plasmon sensor, and the present device is different from that of FIG. 1 in the shape of the dielectric block used. That is, in the present embodiment, the dielectric prism 11 used in the apparatus of FIG.
Instead, a dielectric block 41 having a square cross section is used. Correspondingly, a compensation dielectric block 51 having a rectangular cross section is applied.

Also in this embodiment, the light beam L emitted from the laser light source 16 and converted into parallel light by the collimator lens 17 enters the dielectric block 41, and enters the interface 41a between the dielectric block 41 and the thin metal film 13. Incident. At this time, the incident angle θ of the light beam L with respect to the interface 41a is set to a value within a range where the condition for total reflection of the light beam L at the interface 41a is obtained and surface plasmon resonance can occur.

The light beam L incident on the interface 41 a is totally reflected there, and the totally reflected light beam L exits from the dielectric block 41. The light beam L emitted from the dielectric block 41 is incident on the compensation dielectric block 51 and is totally reflected at the interface between the compensation dielectric block 51 and the diffusion film 24. The evanescent light is diffused by the diffusion film 24 formed on one surface 51a of the compensation dielectric block 51. Therefore, an image is formed on the diffusion film 24 by the totally reflected light beam L. The imaging of this image and the measurement of the refractive index distribution of the sample 15 based on the image are the same as in the first embodiment.

The compensating dielectric block 51 is formed of the same material as the dielectric block 41, and has the same cross-sectional shape as that of the dielectric block 41 in the plane of incidence of the light beam L on the interface 41a. It is assumed. The compensating dielectric block 51 is arranged such that the light beam L emitted from the dielectric block 41 is incident along the same optical path as when the light beam L enters the dielectric block 41. By arranging the compensating dielectric block 51 in this manner, the image carried by the light beam L on one surface 51a thereof (this corresponds to the surface constituting the interface 41a of the dielectric block 41). That is, the image formed on the diffusion film 24 is one in which the image distortion due to the change in the optical path is eliminated.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The sensor using the attenuated total reflection according to the fourth embodiment is also a surface plasmon sensor, and the present device differs from that of FIG. 4 in the configuration of the dielectric block used. That is, in the present embodiment, the dielectric block 41 used in the apparatus of FIG.
Instead of a dielectric block 60 and a dielectric plate joined to the upper surface thereof through a refractive index matching oil 62
61 are used. The dielectric block 60 has an input end face 60a and an output end face 60b of the light beam L,
On the other hand, the dielectric plate 61 has a surface forming an interface 61 with the metal thin film 13.

In the present embodiment, a dielectric block 70 and a dielectric plate 71 joined to the lower surface of the dielectric block 70 via a refractive index matching oil 72 are used to compensate for image distortion. And this dielectric plate
The diffusion film 24 is formed on the lower surface 71a of the 71 (the surface corresponding to the surface constituting the interface 61 of the dielectric plate 61).

Also in the configuration of the present embodiment, the imaging of the image formed by the diffusion film 24, the measurement of the refractive index distribution of the sample 15 based on the image, and the compensation of the image distortion are performed as in the third embodiment. The same is done.

Next, a fifth embodiment of the present invention will be described with reference to FIG. The device according to the fifth embodiment is the leaky mode sensor described above. In this example, a cladding layer 80 is formed on one surface (the upper surface in the figure) of the dielectric prism 11, and an optical waveguide layer 81 is further formed thereon. Is formed. Except for the above points, this apparatus is basically configured in the same manner as the apparatus of the first embodiment shown in FIG.

In this embodiment, the dielectric prism 11 is
For example, it is formed using a synthetic resin or optical glass such as BK7. On the other hand, the cladding layer 80 is formed in a thin film shape using a dielectric material having a lower refractive index than the dielectric prism 11 or a metal such as gold. The optical waveguide layer 81 is also formed into a thin film using a dielectric material having a higher refractive index than the cladding layer 80, for example, PMMA. The thickness of the cladding layer 80 is, for example, 36.5 nm when formed from a gold thin film, and the thickness of the optical waveguide layer 81 is, for example, about 700 nm when formed from PMMA.

In the leakage mode sensor having the above configuration,
When the light beam L emitted from the laser light source 16 is incident on the cladding layer 80 through the dielectric prism 11 at an incident angle θ equal to or larger than the total reflection angle, the light beam L
Although the light is totally reflected at the interface 11a between the optical waveguide 11 and the cladding layer 80, the light having a specific wave number transmitted through the cladding layer 80 and incident on the optical waveguide layer 81 at a specific incident angle propagates through the optical waveguide layer 81 in a guided mode. I will be. When the waveguide mode is excited in this way, most of the incident light is taken into the optical waveguide layer 81, and
At 11a, total reflection attenuation occurs in which the intensity of light totally reflected is sharply reduced.

The wave number of the guided light in the optical waveguide layer 81 depends on the refractive index of the sample 15 on the optical waveguide layer 81. Therefore, also in this case, the diffusion film on the surface 21a of the compensating dielectric prism 21 is used.
By capturing an image formed by the CCD 24 with the CCD area sensor 23 and reproducing the image, the refractive index distribution in the sample 15 can be measured.

Also in this embodiment, since the compensation dielectric prism 21 is provided, an image generated when the incident angle θ of the light beam L with respect to the interface 11a changes as in the first embodiment. Can be eliminated.

[Brief description of the drawings]

FIG. 1 is a side view of a surface plasmon sensor according to a first embodiment of the present invention.

FIG. 2 is a graph showing a schematic relationship between an incident angle of a light beam in a surface plasmon sensor and a light intensity detected by a light detecting unit.

FIG. 3 is a side view of a surface plasmon sensor according to a second embodiment of the present invention.

FIG. 4 is a side view of a surface plasmon sensor according to a third embodiment of the present invention.

FIG. 5 is a side view of a surface plasmon sensor according to a fourth embodiment of the present invention.

FIG. 6 is a side view of a leaky mode sensor according to a fifth embodiment of the present invention.

[Description of Signs] 11 Transparent dielectric prism 13 Metal thin film 14 Sensing medium 15 Sample 16 Laser light source 17 Collimator lens 21 Compensating dielectric prism 22 Imaging lens 23 CCD area sensor 24 Diffusion film 41 Dielectric block 51 Compensating dielectric Body block 60 Dielectric block 61 Dielectric plate 62 Refractive index matching oil 70 Compensating dielectric block 71 Compensating dielectric plate 72 Refractive index matching oil L Light beam

Claims (8)

[Claims] 1. A dielectric block, a thin film layer formed on one surface of the dielectric block and brought into contact with a sample, a light source for generating a light beam, An incident optical system that makes incident in a parallel light state so that the total reflection condition is obtained at the interface between the dielectric block and the thin film layer. In a sensor using attenuated total reflection, comprising a light detection means for detecting a refractive index distribution of the sample in a plane along the plane, an image generated by the dielectric block when the incident angle of the light beam changes A sensor using attenuated total reflection, wherein an adaptive optics system for compensating distortion is provided. 2. A dielectric block, a thin film layer formed on one surface of the dielectric block and made of a metal film which is brought into contact with a sample, a light source for generating a light beam, and the light beam is transmitted to the dielectric block. On the other hand, an incident optical system that enters in a parallel light state so as to obtain a total reflection condition at an interface between the dielectric block and the thin film layer made of the metal film, and an image formed by a light beam totally reflected at the interface. And a light detecting means for detecting a refractive index distribution of the sample in a plane along the interface, wherein a sensor using attenuated total reflection by surface plasmon resonance, wherein the incidence of the light beam A sensor using attenuated total reflection, comprising: an compensation optical system for compensating for image distortion caused by the dielectric block when the angle changes. 3. A thin film layer comprising: a dielectric block; a cladding layer formed on one surface of the dielectric block; and an optical waveguide layer formed thereon; a light source for generating a light beam; Incident on the dielectric block so as to obtain a total reflection condition at an interface between the dielectric block and the cladding layer, in a parallel light state; and a light beam totally reflected at the interface. Light detecting means for detecting the image of the sample and detecting the refractive index distribution of the sample in a plane along the interface, utilizing the attenuated total reflection caused by the excitation of the waveguide mode in the waveguide layer. A sensor using attenuated total reflection, comprising: a compensating optical system that compensates for image distortion caused by the dielectric block when the angle of incidence of the light beam changes. 4. A material having the same sectional shape as the sectional shape of the dielectric block in the plane of incidence of the light beam incident on the interface and having the same refractive index as the dielectric block. And a compensating dielectric block disposed at a position where a light beam emitted from the dielectric block is incident. The compensating dielectric block is formed on a surface corresponding to one surface of the dielectric block. 4. A sensor using attenuated total reflection according to claim 1, further comprising a screen for image observation. 5. The sensor according to claim 4, wherein the screen is made of a diffuser. 6. The sensor according to claim 4, wherein the screen is made of a phosphor. 7. The dielectric block according to claim 1, wherein the dielectric block is formed as one block having all of an incident end face and an exit end face of the light beam, and a surface on which the thin film layer is formed. Item 7. A sensor using attenuated total reflection according to any one of Items 1 to 6. 8. The dielectric block, wherein a portion having an incident end face and an exit end face of the light beam and a portion having a surface on which the thin film layer is formed are joined via a refractive index matching means. The sensor using attenuated total reflection according to any one of claims 1 to 6, wherein: