JP3257138B2 - Optical measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical measuring device, and more particularly, to an evanescent wave component generated by the propagation of an excitation light by introducing an excitation light into an optical waveguide and causing it to be totally reflected. For measuring optical properties near the surface of an optical waveguide.

[0002]

2. Description of the Related Art Conventionally, an antibody or the like is fixed on the surface of a slab type optical waveguide in advance, an antigen-antibody reaction is performed with an antigen or the like in a solution to be measured, and excitation light is introduced into the slab type optical waveguide. A fluorescence immunoassay method has been proposed in which an evanescent wave component generated by propagating while totally reflecting the light is used to measure the amount of a substance confined in the vicinity of the surface of the slab optical waveguide as a result of the antigen-antibody reaction. Further, as an apparatus for realizing this fluorescence immunoassay method, an apparatus having the configuration shown in FIG. 10 has been proposed (see Japanese Patent Application Laid-Open No. 63-270342). In this apparatus, a reaction tank 42 is integrally formed on one surface of a slab type optical waveguide 41, and excitation light emitted from an excitation light source 43 is reflected by a dichroic mirror 44 and introduced into the slab type optical waveguide 41. Then, by performing an antibody-antigen reaction with an antibody or the like previously labeled with a labeled fluorescent substance between the antigen or the like bound by the antigen-antibody reaction, the slab-type optical waveguide 41 is restrained in the vicinity of the surface thereof. The fluorescent label is excited by an evanescent wave component caused by the excitation light to emit fluorescent light, and the fluorescent light is emitted through the slab type optical waveguide 41. Further, the fluorescent light emitted from the slab type optical waveguide 41 is transmitted to the dichroic mirror 44 and the optical filter 4.
5 and is incident on the light receiving device 46.

In the above device, the slab type optical waveguide 41
The amount of antigens and the like confined in the vicinity of the surface by performing an antigen-antibody reaction with an antibody or the like previously fixed on the surface is determined based on the amount of the antigen or the like in the solution to be measured, and further performing the antigen-antibody reaction. The amount of the fluorescently labeled antibody or the like confined in the vicinity of the surface is also determined based on the amount of the antigen or the like in the solution to be measured. Then, the intensity of the fluorescence emitted from the labeling phosphor excited by the evanescent wave component and the intensity of the fluorescence emitted and transmitted through the slab-type optical waveguide are proportional to the amount of the antigen and the like in the solution to be measured. Become. Therefore, by measuring the intensity of the fluorescence by the light receiving device 46, the presence or absence of an immune reaction, the degree of the immune reaction, and the like can be measured.

[0004]

In the optical measuring device having the above structure, the intensity of the fluorescent light, which is a weak signal light, is measured, so that all the light other than the fluorescent light becomes noise light. In particular, since the excitation light and the fluorescent light share an optical axis at the light input / output portion of the slab-type optical waveguide 41, the excitation light reflected and scattered on the surface of the slab-type optical waveguide 41 is spatially combined with the fluorescent light. It becomes impossible to separate them. Further, the wavelength is discriminated by using the dichroic mirror 44 and the optical filter 45. However, the currently available optical elements cannot completely block the excitation light. Is received. And
The noise light becomes an offset value in a measurement value obtained by the light receiving device 46, and lowers and hinders measurement sensitivity.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and greatly reduces the reflection and scattering of excitation light on the light entrance / exit surface of an optical waveguide to improve measurement sensitivity based on signal light. It is an object of the present invention to provide an optical measuring device capable of performing the measurement.

[0006]

According to a first aspect of the present invention, there is provided an optical measuring apparatus, comprising: an excitation light source for emitting excitation light to be introduced into an optical waveguide; A device that emits light having a polarization direction component as a main component is employed. An optical measuring apparatus according to claim 2, wherein an excitation light source is arranged so that light having a polarization direction component parallel to the incident surface as a main component is incident on the incident surface at an incident angle equal to or less than the Brewster angle. It is.

According to a third aspect of the present invention, there is provided an optical measuring apparatus, wherein an excitation light source is provided so that light having a polarization direction component parallel to the incident surface as a main component is incident on the incident surface at an incident angle substantially equal to the Brewster angle. It is arranged. The optical measuring device according to claim 4, wherein a semiconductor laser and a λ / 2
And a plate.

According to a fifth aspect of the present invention, the semiconductor laser is embedded in the temperature control housing, and the λ / 2 plate covers the laser light emission opening of the temperature control housing. It is arranged so as to be thermally coupled to the temperature control housing as much as possible. The optical measuring device according to claim 6, wherein an optical filter means for removing at least the excitation light component is disposed immediately before the light receiving device that receives the signal light having the optical property near the surface of the optical waveguide. It is.

[0009]

According to the optical measuring device of the present invention, the excitation light is introduced into the optical waveguide and propagated while being totally reflected, and the surface of the optical waveguide is generated based on the evanescent wave component generated by the propagation of the excitation light. Obtain signal light showing nearby optical properties,
In measuring the optical properties near the surface of the optical waveguide by emitting the signal light from the excitation light incident surface of the optical waveguide and receiving the signal light emitted from the excitation light incident surface, as an excitation light source, Since the one that emits light whose main component is the polarization direction component parallel to the incident surface is adopted, the reflection component of the excitation light at the incident surface can be reduced, and the measurement sensitivity of the optical properties based on the signal light can be reduced. Can be enhanced.

According to the optical measuring apparatus of the present invention, an excitation light source is provided so that light having a polarization direction component parallel to the incident surface as a main component is incident on the incident surface at an incident angle of less than the Brewster angle. Are arranged, it is possible to achieve a higher effect of reducing the reflection component of the excitation light on the incident surface, and further increase the measurement sensitivity of the optical property based on the signal light.

According to the optical measuring device of the third aspect, the excitation light is applied so that light having a polarization direction component parallel to the incident surface as a main component is incident on the incident surface at an incident angle substantially equal to the Brewster angle. Since the light source is provided, a sufficiently high reduction effect of the reflection component of the excitation light on the incident surface can be achieved, and the measurement sensitivity of the optical property based on the signal light can be significantly increased.

According to the optical measuring device of the fourth aspect, in addition to the function of any one of the first to third aspects, since the excitation light source includes a semiconductor laser and a λ / 2 plate, Most of the laser light emitted from the laser can be used as the excitation light to be introduced into the optical waveguide, so that it is not necessary to use a semiconductor laser having a higher output than necessary. According to the optical measuring device of the fifth aspect, in addition to the function of the fourth aspect, the semiconductor laser is disposed embedded in the temperature control housing, and the λ / 2 plate is provided in the temperature control housing. Since it is arranged in a state of being thermally coupled to the temperature control housing so as to cover the laser light emission opening, the temperature control of the semiconductor laser and the temperature control of the λ / 2 plate can be achieved at the same time, and both are temperature controlled. Device can be simplified.

According to the optical measuring device of the sixth aspect, in addition to the function of any one of the first to fifth aspects, immediately before the light receiving device for receiving the signal light showing the optical properties near the surface of the optical waveguide. In addition, since the optical filter means for removing at least the excitation light component is disposed, the size of the optical filter means can be easily reduced. More specifically, when the excitation light is introduced into the optical waveguide and propagated while being totally reflected, the evanescent wave caused by a component wave whose polarization direction is perpendicular to the plane of incidence (hereinafter referred to as an S-wave). It is known that the seepage range of a wave component is larger than the seepage range of an evanescent wave component caused by a wave of a component whose polarization direction is parallel to the incident surface (hereinafter, referred to as a P wave). Therefore, for example, as described above, when the fluorescent-labeled antibody or the like is confined near the surface of the optical waveguide by the antigen-antibody reaction and the labeled phosphor is excited by the evanescent wave component, the S-wave is used as the excitation light. (Angular distribution of fl
uorescence from liquids and monodispersed spheres
by evanescent wave exitation: El-Hang Lee, REBen
ner, JBFenn, and RKChang: Applied Optics / Vol.1
8, No. 6/15 March 1979).

However, as a result of the inventor's intensive studies on the measurement of the optical properties near the surface of the optical waveguide based on the evanescent wave component, the signal light intensity can be increased by employing the S wave. It has been found that the reflection and scattering of the excitation light significantly increase, and as a result, the measurement sensitivity based on the signal light cannot be increased. Further, when the P-wave having a small exudation range of the evanescent wave component was adopted and the optical properties near the surface of the optical waveguide were measured, the signal light intensity was considerably reduced as compared with the case where the S-wave was adopted. However, the inventors have found that the reflection and scattering of the excitation light are reduced at a rate larger than the rate of reduction of the signal light intensity, and as a result, the measurement sensitivity based on the signal light can be increased, and the present invention has been completed.

As shown in FIG. 2, the excitation light has a refractive index n0.
Incident on the substance having the refractive index n1 existing in the medium
When the incident light is incident on the incident surface, the reflectance at the incident surface is given by Rp = {tan (ir) / tan (i + r)} ² for the P wave, and Rs = {Sin (ir) / sin (i + r)} ² . Note that sini / sinr = n1 / n0. In FIG. 2, a black circle indicates S-polarized light, and a line segment perpendicular to the traveling direction of light indicates P-polarized light.

For example, when the medium having the refractive index n0 is air and the substance having the refractive index n1 is glass, the relationship between the reflectance and the incident angle is as shown in FIG. That is, while Rs monotonically increases from 4% to 100% as the incident angle increases, Rp temporarily decreases as the incident angle increases, and the incident angle is equal to the Brewster angle. To 0 and then increase to 100%. In the case of light having no polarization characteristics, such as natural light, R
The reflectance is given by the average value of s and Rp. Therefore, it can be understood that the reflectance of the incident surface of the P wave becomes the smallest except when the incident angles are 0 ° and 90 °.

As a result, it can be understood that the reflection component of the excitation light on the incident surface can be reduced by making the excitation light a P wave. In particular, by setting the excitation light to a P-wave and setting the incident angle to substantially the Brewster angle, the reflection of the excitation light on the incident surface can be made almost zero.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a view schematically showing a fluorescence immunoassay apparatus as one embodiment of an optical measurement apparatus according to the present invention. The fluorescence immunoassay apparatus is provided for performing an antigen-antibody reaction on any one side surface of the slab type optical waveguide 1. The reaction tank 2 is integrally formed, and the excitation light incident prism 3 is integrally formed at one end of the slab type optical waveguide. Then, the laser beam emitted from the semiconductor laser 4 is rotated by 90 ° through the λ / 2 plate 5 to obtain a P-polarized light, which is guided to the collimating lens 6 to be converted into a parallel light, and the cylindrical lens 7 and the dichroic mirror 8 are converted. Thus, the light is focused at a predetermined position on the upstream side of the incident surface, and the P-polarized light diffused after the light is focused is introduced into the slab type optical waveguide 1 and propagated while being totally reflected. Further, the signal light emitted from the excitation light incidence prism 3 is transmitted through the dichroic mirror 8 and passes through a sharp cut filter 9 and a condenser lens 10 to form a light receiving device 1 comprising a photomultiplier tube or the like.
1 to receive light. Reference numeral 12 denotes an aperture for cutting unnecessary portions of the excitation light.

Therefore, in the case of this embodiment, since P-polarized light is employed as the excitation light, it is reflected by the dichroic mirror 8 while being condensed by the cylindrical lens 7 and is reflected from the entrance surface of the excitation light incidence prism 3. When introduced into the slab type optical waveguide 1, the reflection and scattering components of the excitation light can be reduced, and thus the dichroic mirror 8, sharp cut filter 9, condenser lens 10
The intensity of the excitation light guided to the light receiving device 11 through the through hole can be sufficiently reduced. As a result, the offset noise (including noise light caused by the reflection and scattering of the excitation light) can be reduced, and the fluorescence immunoassay sensitivity can be increased.

In the above description, the angle of incidence of the P-polarized light is not particularly specified, but as described above with reference to FIG. 3, it is preferable to set the angle of incidence to a Brewster angle or less. Most preferably, the angle of incidence is set to approximately the Brewster angle. This is a case in which P-polarized light, S-polarized light, and non-polarized light are incident as excitation light using the fluorescence immunoassay apparatus having the above configuration.
Table 1 shows the offset noise, the fluorescence signal, and the ratio of the fluorescence signal to the offset noise when the cutoff wavelength was changed. The excitation light wavelength was 650 nm, the incident light amount was 35 μW, the incident angle of the excitation light was 55 °, the antigen concentration was 30 ng / ml β ₂ M, and the fluorescence-labeled antibody concentration was 10 μg / ml C
MI-antiβ ₂ M, the material of the slab type optical waveguide 1 is polymethyl methacrylate (PMMA, refractive index 1.498)
3) are set respectively.

As is clear from Table 1, when the P-polarized light is used, the fluorescence signal is the smallest, but the offset noise is also small, and the ratio of the fluorescence signal to the offset noise is smaller when the P-polarized light is used. Is the largest.
Therefore, it is understood that the measurement sensitivity can be improved by using P-polarized light. In particular, if the cut-off wavelength of the sharp cut filter 9 is made sufficiently large, the variation in the fluorescence signal due to the difference in the excitation light becomes small, so that the measurement sensitivity can be significantly increased.

[0022]

[Table 1] In this embodiment, the excitation light is a dichroic mirror 8
Although it is possible to transmit the light and to reflect the signal light by the dichroic mirror 8, it is possible to adjust the optical axis of the excitation light only by adjusting the angle of the dichroic mirror 8 in consideration of FIG. It is preferable to adopt a configuration.

[0023]

Embodiment 2 FIG. 4 is a diagram schematically showing a fluorescence immunoassay apparatus as another embodiment of the optical measurement apparatus of the present invention. The difference from the embodiment of FIG.
Instead of placing a sharp cut filter 9 between
The only difference is that the sharp cut filter 9 is arranged immediately before the light receiving device 11. In addition, CMI (Carb
oxymethylindocyanine) and the wavelength of laser light is 65
It is set to 0 nm, and the cutoff wavelength of the sharp cut filter 9 is set to 695 nm.

Therefore, in the case of this embodiment, the size of the sharp cut filter 9 can be reduced, and the same operation as that of the embodiment of FIG. 1 can be achieved. FIT as labeling phosphor
When C (Fluorescei isothiocyanate) is used and an Ar laser having a laser light wavelength of approximately 488 nm is used as a laser light source, the cutoff wavelength of the sharp cut filter 9 is set to, for example, 515 nm. In this case, as shown by a broken line in FIG. 5, the present inventor has confirmed that the sharp cut filter 9 itself emits fluorescence by excitation light. Therefore, when configuring the fluorescence immunoassay apparatus according to the above setting, in order to reduce the influence of the fluorescence emitted from the sharp cut filter 9 on the light receiving device 11, as shown in FIG. Must be arranged near the condenser lens 10.

However, when CMI is used as the labeling phosphor and the wavelength of the laser beam is set to 650 nm and the cutoff wavelength of the sharp cut filter 9 is set to 695 nm as in this embodiment, the solid line in FIG. As shown, the present inventor has found that the sharp cut filter 9 itself can significantly reduce the fluorescence emitted by the excitation light. As a result, the sharp cut filter 9 can be disposed immediately before the light receiving device 11, and the sharp cut filter 9 can be downsized due to being disposed immediately before the light receiving device 11.

FIGS. 6 to 8 are schematic diagrams showing examples of the configuration of an optical system for excitation light applicable to the optical measuring apparatus of the present invention. Each section of these schematic diagrams shows the cross-sectional shape and the polarization direction of the laser light. The hatched rectangular area is a portion that functions as excitation light. The optical system for excitation light shown in FIG. 6 is a combination of a cylindrical lens, and converts an elliptical laser beam emitted from the semiconductor laser 4 into a parallel light beam by a collimating lens 21, and a parallel light beam by a concave cylindrical lens 22. The converted laser light is enlarged, and a circular laser light is obtained by a pair of cylindrical lenses 23 and 24 which are arranged opposite to each other. Then, unnecessary portions are removed by the aperture 25 to obtain P-polarized excitation light.

Therefore, in the case of this specific example, the unnecessary portion is removed by the aperture 25 after obtaining the circular laser beam once, and the portion to be removed is considerably large. It has the disadvantage of being low. In addition, it is necessary to control the focal positions of all the above lenses, adjust the optical axis, and the like, which disadvantageously complicates the operation for obtaining a desired optical system. Further, since a holder and the like are required, the cost is increased.

The optical system for excitation light shown in FIG. 7 employs a prism pair, and converts an elliptical laser beam emitted from the semiconductor laser 4 into a parallel light beam by a collimating lens 21 so as to be directed in opposite directions. A pair of prisms 26 and 27 disposed in the laser beam expand the parallel laser beam in the short axis direction to obtain a circular laser beam, and the cylindrical lens 28 condenses the circular laser beam. At the same time, unnecessary portions are removed by the aperture 29 to obtain P-polarized excitation light.

Therefore, also in this specific example, the unnecessary portion is removed by the aperture 25 after obtaining the circular laser beam once, and the portion to be removed is considerably large. It has the disadvantage of being low. In addition, since the accuracy of the prisms 26 and 27 and the accuracy of the relative position between the prisms 26 and 27 must be improved, there is a disadvantage that the operation for obtaining a desired optical system becomes extremely complicated. Further, since the optical axis of the semiconductor laser 4 and the optical axis of the cylindrical lens 28 are inevitably deviated, there is a disadvantage that the arrangement of each component with respect to the excitation light incidence prism 3 becomes complicated.

The optical system for excitation light shown in FIG.
The laser beam emitted from the semiconductor laser 4 has an elliptical shape and the polarization direction is the short axis direction, but the polarization direction is 90 ° by transmitting through the λ / 2 plate 5. Rotated, the polarization direction becomes the long axis direction. The laser light is guided to the collimating lens 6 to be converted into a parallel light flux, condensed by the cylindrical lens 7, and unnecessary portions are removed by the aperture 12 to obtain P-polarized excitation light.

Therefore, in the case of this specific example, since the cross-sectional shape of the laser light remains elliptical, the unnecessary portion removed by the aperture 12 can be significantly reduced, and the efficiency of using the laser light can be improved. In addition, unlike the optical system for excitation light shown in FIGS. 6 and 7, an optical element requiring various adjustments is not required, and the operation for obtaining a desired optical system can be greatly simplified.

FIG. 9 is a longitudinal sectional view showing an example of a specific arrangement of the semiconductor laser 4 and the λ / 2 plate 5.
The semiconductor laser 4 is surrounded by a pair of copper blocks 31 and 32 in which an accommodation space is formed, and the semiconductor laser 4 is fixed by an O-ring 33. Then, the copper block 31 on the back side is brought into contact with the heat absorbing surface of the Peltier device 34, and the heat generating surface of the Peltier device 34 is brought into contact with a heat sink 35 made of aluminum or the like. The λ / 2 plate 5 is arranged so as to cover the opening of the copper block 32 on the front side, that is, on the laser beam emission side. 36 is a copper block holder, 3
7 is a λ / 2 plate holder, 38 is an O-ring, and 39 is an opening for emitting laser light. A broken line indicates a laser beam.

The λ / 2 plate 5 may be made of any material, but it is preferable to use quartz made of a material having a large polarization ratio of transmitted light and a small light loss. However, the λ / 2 plate 5 made of quartz is
Since it has a temperature dependency of about −0.01% / ° C.,
In performing high-precision optical measurement, it is necessary to ensure the temporal stability of the λ / 2 plate 5 irrespective of the temperature dependency.

Further, since the semiconductor laser 4 has a considerably large temperature dependence of the oscillation wavelength, when a semiconductor laser is used as a light source for performing high-precision optical measurement, the temperature change is compensated. Generally, temperature control is performed as much as possible. The configuration of FIG. 9 can satisfy both of the above requirements at the same time. For example, the copper block 3 is controlled by PID control using a Peltier element 34 or the like.
The case temperature of the semiconductor laser 4 is set to ± 0.
By controlling the temperature of the λ / 2 plate 5 at ± 0.01 ° C. without providing a dedicated temperature control device, the temperature of the λ / 2 plate 5 can be controlled by ± 0.01 ° C.
Can be stabilized in the range of ° C. Also, copper blocks 31, 32
The semiconductor laser 4 housing space is isolated from the outside air by the λ / 2 plate 5, so that the temperature stability of the semiconductor laser 4 can be improved. Further, the size of the λ / 2 plate 5 can be reduced.

[0035]

As described above, the first aspect of the present invention employs, as the excitation light source, a light source that emits light having a polarization direction component parallel to the incident surface as a main component. This has a specific effect that the reflection component of light can be reduced, and the measurement sensitivity of the optical property based on the signal light can be increased.

According to a second aspect of the present invention, the excitation light source is arranged so that light having a polarization direction component parallel to the plane of incidence as a main component is incident on the plane of incidence at an angle of incidence smaller than the Brewster angle. Therefore, of the reflected component of the excitation light on the incident surface,
It is possible to achieve a higher reduction effect, and furthermore, it has a unique effect that the measurement sensitivity of the optical property based on the signal light can be further increased.

According to a third aspect of the present invention, an excitation light source is disposed so that light having a polarization direction component parallel to the incident surface as a main component is incident on the incident surface at an incident angle substantially equal to the Brewster angle. Therefore, a sufficiently high effect of reducing the reflection component of the excitation light on the incident surface can be achieved, and as a result, a unique effect that the measurement sensitivity of the optical property based on the signal light can be remarkably increased.

The invention according to claim 4 is the invention according to claims 1 to 3.
In addition to the above-mentioned effects, most of the laser light emitted from the semiconductor laser can be used as excitation light to be introduced into the optical waveguide, which eliminates the need to use a semiconductor laser having an output larger than necessary. Has the effect of The invention of claim 5 has a unique effect that, in addition to the effect of claim 4, the temperature control of the semiconductor laser and the temperature control of the λ / 2 plate can be simultaneously achieved, and the device for controlling the temperature of both can be simplified. Play.

The invention of claim 6 is the invention of claims 1 to 5
In addition to the effect of any one of the above, there is an effect that the size of the optical filter means can be easily reduced.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a fluorescence immunoassay apparatus as one embodiment of an optical measurement apparatus of the present invention.

FIG. 2 is a diagram schematically illustrating reflection of excitation light.

FIG. 3 illustrates a case where incident light is P-polarized light and S-polarized light.
It is a figure which shows the relationship between each reflectance and an incident angle.

FIG. 4 is a diagram schematically showing a fluorescence immunoassay apparatus as another embodiment of the optical measurement apparatus of the present invention.

FIG. 5 is a diagram showing the wavelength and intensity of fluorescence emitted from a sharp cut filter itself.

FIG. 6 is a schematic diagram showing a configuration example of an excitation light optical system applicable to the optical measuring device of the present invention.

FIG. 7 is a schematic diagram showing a configuration example of an excitation light optical system applicable to the optical measuring device of the present invention.

FIG. 8 is a schematic diagram showing a configuration example of an excitation light optical system applicable to the optical measuring device of the present invention.

FIG. 9 is a longitudinal sectional view showing a specific arrangement configuration example of a semiconductor laser and a λ / 2 plate.

FIG. 10 is a diagram schematically showing a conventional fluorescence immunoassay apparatus.

[Explanation of symbols]

 Reference Signs List 1 slab type optical waveguide 4 semiconductor laser 5 λ / 2 plate 9 sharp cut filter 11 light receiving device 31, 32 copper block 39 laser light emitting aperture

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-63-273042 (JP, A) JP-A-5-52740 (JP, A) JP-A-4-262244 (JP, A) JP-A-5-27044 288749 (JP, A) Table 2 Hei 504313 (JP, A) Table 6 Hei 6-503889 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB name) G01N 21/00-21 / 01 G01N 21/17-21/74 JICST file (JOIS)

Claims (6)

(57) [Claims] An excitation light is introduced into an optical waveguide (1), propagated while being totally reflected, and an optical signal near the surface of the optical waveguide (1) is generated based on an evanescent wave component generated by the propagation of the excitation light. An optical waveguide (1) is obtained by obtaining signal light having properties, emitting the signal light from the excitation light incident surface of the optical waveguide (1), and receiving the signal light emitted from the excitation light incident surface.
An optical measuring device for measuring optical properties near the surface of the device, which emits light mainly composed of a polarization direction component parallel to the incident surface as the excitation light sources (4) and (5). An optical measuring device, characterized in that: 2. Excitation light sources (4) and (5) are arranged so that light having a polarization direction component parallel to the plane of incidence as a main component is incident on the plane of incidence at an angle of Brewster angle or less. The optical measuring device according to claim 1. 3. Excitation light sources (4) and (5) are arranged so that light having a polarization direction component parallel to the plane of incidence as a main component is incident on the plane of incidence at an angle of incidence substantially equal to the Brewster angle. The optical measuring device according to claim 1, wherein 4. The optical measurement according to claim 1, wherein the excitation light sources (4) and (5) include a semiconductor laser (4) and a λ / 2 plate (5). apparatus. 5. A semiconductor laser (4) is embedded in a temperature control housing (31) (32), and a λ / 2 plate (5) is mounted on the temperature control housing (31) (32). The optical measuring device according to claim 4, wherein the optical measuring device is arranged so as to cover the laser light emission opening (39) of the temperature control housing (32) so as to cover the laser light emission opening (39). 6. An optical filter means (9) for removing at least an excitation light component immediately before a light receiving device (11) for receiving signal light having optical properties near the surface of the optical waveguide (1). The optical measuring device according to claim 1, wherein the optical measuring device is arranged.