JP3390355B2 - Surface plasmon sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface plasmon sensor for quantitatively analyzing a substance in a sample by utilizing the generation of surface plasmon, and more particularly, to a surface having improved light source section and improved measurement accuracy. It relates to plasmon sensors.

[0002]

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

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

A surface plasmon sensor using the above system basically emits a light beam and 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. A light source to be generated and the light beam are introduced into a dielectric block, and total reflection conditions are established at the interface between the dielectric block and the metal film, and
An optical system is provided that allows various incident angles including surface plasmon generation conditions to be obtained, and light detection means that is capable of detecting the intensity of the light beam totally reflected at the interface at various incident angles. It will be.

As described above, in order to obtain various incident angles, a relatively thin light beam may be deflected to be incident on the interface, or a component which is incident on the light beam at various angles may be included. As described above, a relatively thick light beam may be incident so as to be focused at the interface. In the former case, a light beam whose reflection angle changes with the deflection of the light beam can be detected by a small photodetector that moves synchronously with the deflection of the light beam, or by an area sensor extending along the direction of change of the reflection angle. Can be detected. On the other hand, in the latter case, each light beam reflected at various reflection angles can be detected by an area sensor extending in a direction in which all the light beams can be received.

In the surface plasmon sensor having the above structure, when a light beam is incident on the metal film at a specific incident angle θ _SP which is equal to or greater than the total reflection angle, an evanescent wave having an electric field distribution in the 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 this evanescent wave. When the wave 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 the light is transferred to the surface plasmon, so that at the interface between the dielectric block and the metal film. The intensity of the reflected light sharply decreases.

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

[0008]

[Equation 1]

[0009] Knowing the dielectric constant epsilon _s of the sample, since it is found the concentration of a specific substance in the sample based on a predetermined calibration curve or the like, after all, by knowing the incident angle theta _SP that the reflected light intensity is lowered, The specific substance in the sample can be quantitatively analyzed.

[0010]

In the conventional surface plasmon sensor of the type described above, a laser has been generally used as a light source. In particular, when a single mode laser is used, the curve of attenuation of total reflection becomes sharp, which enables highly sensitive measurement.

However, even the conventional surface plasmon sensor using this laser does not always provide sufficiently high measurement accuracy, and there is room for improvement in this respect.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a surface plasmon sensor which can realize sufficiently high measurement accuracy.

[0013]

A surface plasmon sensor according to the present invention comprises a dielectric block as described above, a metal film, a light source for generating a light beam, an optical system, and a light detecting means. The surface plasmon sensor is characterized in that a laser provided with an oscillation wavelength stabilizing means incorporating a wavelength selecting means is used as a light source.

As the laser for the light source, a semiconductor laser which is advantageous in reducing the size and weight of the device can be preferably used. In that case, as the oscillation wavelength stabilizing means, for example, an optical system for feeding back a part of the laser beam emitted from the semiconductor laser to the semiconductor laser, and a diffraction grating (grating for selecting the wavelength of the fed-back laser beam) ), A bandpass filter, and other wavelength selecting means can be used.

When the wavelength selecting means is composed of, for example, a bulk grating, the optical system for performing the optical feedback described above is arranged in the optical path of the laser beam from the semiconductor laser to the dielectric block, and a part of the laser beam is provided. And a reflective grating that reflects the laser beam branched by the optical branching means so as to follow the optical path in the opposite direction, and use this reflective grating also as a wavelength selecting means. You can

Further, the optical system and the wavelength selection means for performing the optical feedback are constituted by a partial reflection type grating arranged in the optical path of the laser beam from the semiconductor laser to the dielectric block and reflecting a part of the laser beam. It is also possible.

Further, the optical system for performing the optical feedback and the wavelength selecting means may be constituted by a reflection type grating which reflects backward emitted light emitted in a direction opposite to the laser beam directed from the semiconductor laser to the dielectric block. It is possible.

On the other hand, when the wavelength selecting means is composed of, for example, a narrow transmission bandpass filter, an optical system for performing optical feedback is arranged in the optical path of the laser beam from the semiconductor laser to the dielectric block. The optical beam splitting unit splits a part of the beam, and the mirror for reflecting the laser beam split by the optical splitting unit so as to follow the optical path in the opposite direction, and the laser beam between the mirror and the semiconductor laser. A narrow transmission band-pass filter can be arranged in the optical path of the above.

Further, the optical system for performing the optical feedback is constituted by a half mirror arranged in the optical path of the laser beam from the semiconductor laser toward the dielectric block and reflecting a part of the laser beam. A narrow transmission band-pass filter may be arranged in the optical path of the laser beam to and from the laser.

Further, the optical system for performing the optical feedback is composed of a mirror for reflecting backward emitted light emitted in a direction opposite to the laser beam directed from the semiconductor laser to the dielectric block, and between the mirror and the semiconductor laser. It is also possible to use a narrow transmission bandpass filter arranged in the optical path of the laser beam.

Further, as the wavelength selecting means, it is also possible to apply a fiber grating which is composed of an optical fiber in which a plurality of refractive index changing portions are formed at equal intervals in a core and which reflects and diffracts a laser beam.

When such a fiber grating is applied, for example, an optical system for performing the optical feedback is arranged in the optical path of the laser beam from the semiconductor laser to the dielectric block, and a part of the laser beam is branched. And a fiber grating for reflecting the laser beam branched by the optical branching means so as to follow the optical path in the opposite direction, and this fiber grating can also be used as the wavelength selecting means.

Further, the optical system and the wavelength selecting means for performing the above-mentioned optical feedback are provided by a partially reflective fiber grating which is arranged in the optical path of the laser beam from the semiconductor laser to the dielectric block and reflects a part of the laser beam. It can also be configured.

Further, the optical system and the wavelength selecting means for performing the optical feedback may be constituted by a fiber grating which reflects backward emitted light emitted in a direction opposite to the laser beam directed from the semiconductor laser to the dielectric block.

On the other hand, it is possible to stabilize the oscillation wavelength without performing the optical feedback as described above. For example, a DFB (distributor) is used as a light source for generating a light beam.
butedfeedback: distributed feedback type laser, DBR (distr
ibuted Bragg reflector: By using a distributed Bragg reflector laser, the oscillation wavelength can be stabilized.

Further, the oscillation wavelength stabilizing means is not limited to the one described above, but other means such as a means for electrically and precisely controlling the drive current and temperature of the laser may be used.

[0027]

According to the research conducted by the present inventor, it has been found that the problem that it is difficult to obtain high measurement accuracy in the conventional surface plasmon sensor using a laser as a light source is caused by the fluctuation of the oscillation wavelength of the laser. In other words, when the oscillation wavelength of the laser fluctuates, it affects the generation condition of the surface plasmon and causes noise in the surface plasmon detection signal (the intensity detection signal of the light totally reflected at the interface between the dielectric block and the metal film). , Which led to a decrease in measurement accuracy.

In the surface plasmon sensor of the present invention, since the oscillation wavelength stabilizing means is provided, the oscillation wavelength variation of the laser is suppressed and the above-mentioned noise generation is suppressed, so that sufficiently high measurement accuracy is realized.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a planar shape of a surface plasmon sensor according to a first embodiment of the present invention, and FIG. 2 shows a side surface shape of the surface plasmon detecting portion.

As shown in the figure, this surface plasmon sensor is formed of glass as a dielectric, and has a triangular prism 10 whose major axis extends in a direction perpendicular to the plane of FIG. 2 (vertical direction in FIG. 1). A metal film 12 made of, for example, gold, silver or the like formed on one surface of the prism 10 and brought into contact with the sample 11, a semiconductor laser 14 for generating one light beam (laser beam) 13, Beam 13 prism
An optical system 15 that allows light to pass through the interface 10a between the prism 10 and the metal film 12 so that various incident angles can be obtained.
A first light detecting means 16 and a second light detecting means 17 for detecting the light quantity of the light beam 13 totally reflected at the interface 10a;
It is provided with a comparator 18 connected to these light detecting means 16 and 17.

The incident optical system 15 includes a collimator lens 20 for collimating the light beam 13 emitted from the semiconductor laser 14 in a diverging state, and a beam expander 21 for expanding the diameter of the collimated light beam 13. And a condenser lens 22 for converging the expanded light beam 13 on the interface 10a.

An oscillation wavelength stabilizing means 30 is provided between the collimator lens 20 and the beam expander 21, which will be described later.

Since the light beam 13 is condensed by the condenser lens 22 as described above, as shown in FIG. 2 showing the minimum incident angle θ ₁ and the maximum incident angle θ ₂ , the light beam 13 is incident on the interface 10a. It includes components incident at various incident angles θ. The incident angle θ is set to an angle equal to or larger than the total reflection angle. Therefore, the light beam 13 is totally reflected at the interface 10a, and the reflected light beam
13 includes components that reflect at various reflection angles.

On the other hand, the first light detecting means 16 and the second light detecting means 17 are, for example, two-division photodiodes and the like. The first light detecting means 16 is arranged so as to detect the light quantity of the component in the first reflection angle range (relatively low angle range) of the light beam 13 totally reflected by the interface 10a, and The light detection means 17 is a light beam totally reflected by the interface 10a.
It is arranged so as to detect the amount of light of a component in the second reflection angle range (relatively high angle range) among the 13 angles.

The sample analysis by the surface plasmon sensor having the above structure will be described below. The sample 11 to be analyzed is held in contact with the metal film 12. Then, the light beam 13 condensed as described above is irradiated toward the metal film 12. The light beam 13 totally reflected at the interface 10a between the metal film 12 and the prism 10 is detected by the first light detecting means 16 and the second light detecting means 17.

At this time, the light amount detection signal S1 output by the first light detecting means 16 and the light amount detection signal S2 output by the second light detecting means 17 are input to the comparator 18, which then outputs both signals. A difference signal S indicating the difference between S1 and S2 is output.

Here, a specific incident angle θ _SP at the interface 10a
Since the light incident on the light excites surface plasmons at the interface between the metal film 12 and the sample 11, the reflected light intensity I of this light sharply decreases. That is, the relationship between the intensity I of the totally reflected light beam 13 and the incident angle θ is as shown by curves a and b in FIGS. 3A and 3B, respectively. If the incident angle θ _{SP of} attenuated total reflection (ATR) and the relationship curve between the reflected light intensity I and the incident angle θ are known, the specific substance in the sample 11 can be quantitatively analyzed. Hereinafter, the reason will be described in detail.

_Assuming that the first reflection angle range and the second reflection angle range are continuous and the reflection angle at the boundary between the two ranges is θ _M , the incident angle is smaller than the incident angle θ _M. The light in the small range and the light in the large range are detected by one and the other of the light detecting means 16 and 17, respectively.

As an example, the light in the range where the incident angle is smaller than θ _M is detected by the first light detecting means 16, and the light beam in the range where the incident angle is larger than θ _M is the second light detecting means.
If it is detected by 17, the first light detection means
16 detects the light in the shaded areas in FIGS. 3A and 3B, and the detected light amount is larger in the case of (B) than in the case of (A). On the contrary, the second
The amount of light detected by the light detecting means 17 is smaller in the case of (B) than in the case of (A). As described above, the amount of light detected by the first photodetector 16 and the amount of light detected by the second photodetector 17 cause a unique difference depending on the relationship between the incident angle θ and the reflected light intensity I.

Therefore, by referring to the calibration curve or the like for each sample that is obtained in advance, the light amount detection signal S1 output by the first light detecting means 16 and the light amount detection signal output by the second light detecting means 17 are obtained. Based on the output of the comparator 18 indicating the difference from S2, that is, the difference signal S, the attenuated total reflection (ATR) incident angle θ _SP for the analysis sample 11 and the relationship curve between the incident angle θ and the reflected light intensity I are estimated. This makes it possible to quantitatively analyze the substance in the sample 11.

Although the case where the first reflection angle range and the second reflection angle range are continuous has been described above, the first light detecting means 16 can be used even when both ranges are not continuous. The quantity of light detected by the second light detecting means 16 and the quantity of light detected by the second light detecting means 16 have a peculiar difference depending on the relationship between the incident angle θ and the reflected light intensity I. Therefore, quantitatively analyze the substance in the sample 11 in the same manner. You can

Next, the oscillation wavelength stabilizing means 30 will be described. The oscillation wavelength stabilizing means 30 includes a λ / 2 plate 31 that controls the polarization of the light beam 13 and a beam splitter 32 that partially reflects and branches the light beam 13 that has passed through the λ / 2 plate 31.
And a reflective grating (diffraction grating) 33 arranged at a position where the branched light beam 13R is incident.

The light beam 13R branched and incident on the reflection type grating 33 is wavelength-selected by the grating 33 in such a state that the spectrum is extremely narrow, and is reflected so as to follow the incident optical path in the opposite direction. The light beam 13R is fed back to the semiconductor laser 14 via the beam splitter 32 and the λ / 2 plate 31. In this way, the external cavity is formed by the rear end surface (the left end surface in FIG. 1) of the semiconductor laser 14 and the reflective grating 33, and the oscillation wavelength of the semiconductor laser 14 is the selected wavelength of the reflective grating 33. Locked in.

When the oscillation wavelength of the semiconductor laser 14 is stabilized as described above, noise is prevented from being generated in the differential signal S due to fluctuations in the oscillation wavelength, and high measurement accuracy for sample analysis is realized.

Next, a second embodiment of the present invention will be described with reference to FIG. All of the devices of the embodiments described below are basically different from the device shown in FIG. 1 only in the oscillation wavelength stabilizing means, and other surface plasmon detection parts and the like are formed in the same manner. ing. Also, in FIG. 4, the same elements as those in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted unless necessary (the same applies hereinafter).

The oscillation wavelength stabilizing means 30A of the device of the second embodiment is composed of an optical system for performing optical feedback and a partial reflection type grating 34 which also serves as wavelength selecting means. This partially reflective grating 34
Is arranged in the optical path of a light beam (laser beam) 13 directed from the semiconductor laser 14 to the prism 10 (see FIG. 2) and reflects a part of the light beam 13.

The reflected light beam 13 is a semiconductor laser 14
And the oscillation wavelength of the semiconductor laser 14 is locked to the selected wavelength of the partially reflective grating 34.

Next, a third embodiment of the present invention will be described with reference to FIG. The oscillation wavelength stabilizing means 30B of the device of the third embodiment is composed of a reflection type grating 33 and a collimator lens 35.

The reflection type grating 33 constitutes an optical system for performing optical feedback together with the collimator lens 35, and also serves as a wavelength selecting means. That is, the backward emission light 13Q emitted from the semiconductor laser 14 in the direction opposite to the prism 10 (see FIG. 2) is collimated by the collimator lens 35 and then incident on the reflective grating 33.

The backward emission light 13Q reflected by the reflection type grating 33 is fed back to the semiconductor laser 14,
As a result, the oscillation wavelength of the semiconductor laser 14 is locked to the selected wavelength of the reflective grating 33.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The oscillation wavelength stabilizing means 40 of the device of the fourth embodiment comprises a narrow transmission band bandpass filter 41 arranged at a position where the light beam 13R split by the beam splitter 32 is incident, and a light beam 13R transmitted therethrough.
And a mirror 43 arranged at the position where the light beam 13R is converged by the condenser lens 42.

The light beam 13R is wavelength-selected by the narrow transmission band-pass filter 41 to have an extremely narrow spectrum, and is reflected by the mirror 43 to follow the incident light path in the opposite direction. This light beam 13R is formed by the beam splitter 32 and λ.
It is fed back to the semiconductor laser 14 via the / 2 plate 31. As a result, the oscillation wavelength of the semiconductor laser 14 is locked to the selected wavelength of the narrow pass band bandpass filter 41, and high measurement accuracy is realized in this case as well.

A half mirror may be used instead of the beam splitter 32.

Next, a fifth embodiment of the present invention will be described with reference to FIG. The oscillation wavelength stabilizing means 40A of the device of the fifth embodiment is provided with the semiconductor laser 14 to the prism 10.
(See FIG. 2) The narrow transmission band-pass filter 41, the condenser lens 44, the half mirror 45, and the collimator lens, which are sequentially arranged in the optical path of the light beam (laser beam) 13 toward
It consists of 46.

The condenser lens 44 and the half mirror 45 form an optical system for performing optical feedback. That is, a part of the light beam 13 is reflected by the half mirror 45 arranged at the converging position of the condenser lens 44 and fed back to the semiconductor laser 14.

At this time, the light beam 13 is wavelength-selected by the narrow transmission bandpass filter 41 and fed back to the semiconductor laser 14. As a result, the oscillation wavelength of the semiconductor laser 14 is locked to the selected wavelength of the narrow pass band bandpass filter 41, and high measurement accuracy is realized in this case as well.

Next, a sixth embodiment of the present invention will be described with reference to FIG. The oscillation wavelength stabilizing means 40B of the device of the sixth embodiment includes a collimator lens 47 for collimating the backward emission light 13Q emitted from the semiconductor laser 14,
A narrow transmission bandpass filter 41 arranged in the optical path of the backward outgoing light 13Q after passing through the collimator lens 47, and a condenser lens 42 for focusing the backward outgoing light 13Q transmitted therethrough.
And a mirror 43 arranged at a position where the backward emission light 13Q is converged by the condenser lens 42.

The condenser lens 42 and the mirror 43 constitute an optical system for performing optical feedback, and the narrow transmission bandpass filter 41 constitutes a wavelength selecting means. That is, the backward emission light 13Q is wavelength-selected by the narrow transmission bandpass filter 41, is reflected by the mirror 43, follows the incident optical path in the opposite direction, and is fed back to the semiconductor laser 14. As a result, also in this case, the oscillation wavelength of the semiconductor laser 14 is locked to the selection wavelength of the narrow transmission bandpass filter 41.

Next, a seventh embodiment of the present invention will be described with reference to FIG. The oscillation wavelength stabilizing means 50 of the device of the seventh embodiment includes a beam splitter 51 for partially reflecting and splitting the light beam 13 emitted from the semiconductor laser 14,
A mirror 52 for reflecting the branched light beam 13R, a condenser lens 53 for condensing the reflected light beam 13R, and an arrangement such that one end face is located at the converging position of the condenser lens 53 for the light beam 13R. And a reflective fiber grating 54 that has been formed.

The reflective fiber grating 54 is an optical fiber in which a core having a higher refractive index than that is embedded in the clad, and a plurality of refractive index changing portions are formed at equal intervals in the core. This reflective fiber grating 54 has an outer cladding diameter of 125 μm as an example.
Interference fringes are formed on the core of an optical fiber for optical communication with a core diameter of about 10 μm by two-beam interference exposure using excimer laser light in the ultraviolet range, and the refractive index of the light-irradiated portion of the core is changed (increased) It is created by It is considered that this change in the refractive index is caused by the chemical change of germanium oxide doped in the core due to the irradiation of ultraviolet rays.

Light beam 13 condensed by the condenser lens 53
R enters the core from the end face of the reflective fiber grating 54 and propagates there. The refractive index changing portion formed on the core constitutes a grating (diffraction grating) along the propagation direction of the light beam 13R. This grating reflects and diffracts only the light of a specific wavelength corresponding to the period of the light beam 13R propagating through the core and feeds it back to the semiconductor laser 14. Therefore, the oscillation wavelength of the semiconductor laser 14 is locked to the selected wavelength of the reflective fiber grating 54.

Next, an eighth embodiment of the present invention will be described with reference to FIG. The oscillation wavelength stabilizing means 50A of the device of the eighth embodiment has a condenser lens 55 for condensing the light beam 13 emitted from the semiconductor laser 14, a first fiber 56 and a second fiber constituting a fiber coupler. It consists of 57 and. The first fiber 56 has the refractive index changing portion as described above, and the second fiber 57 is coupled to the first fiber 56.

A part of the light beam 13 which is incident on the second fiber 57 from one end face side and propagates therethrough is partially moved to the first fiber 56 at the coupling portion of the two fibers 56 and 57, and The system is branched. The light beam 13 propagating through the second fiber 57 and emitted from the other end face is used for sample analysis by surface plasmons.

On the other hand, the light beam 13 transferred to the first fiber 56 propagates through the first fiber 56 and is reflected and diffracted at the refractive index changing portion thereof. Reflected and diffracted light beam 13
Is fed back to the semiconductor laser 14 via the condenser lens 55, and the oscillation wavelength of the semiconductor laser 14 is locked to the selected wavelength of the first fiber 56.

Next, a ninth embodiment of the present invention will be described with reference to FIG. The oscillation wavelength stabilizing means 50B of the device of the ninth embodiment includes a condenser lens 55 that condenses the light beam 13 emitted from the semiconductor laser 14, and the condenser lens 55.
It is composed of a partially reflective fiber grating 58 whose one end face is located at the converging position of the light beam 13 by 55.

Partial reflection type fiber grating 58
Is basically the same as the reflective fiber grating 54, of the light beam 13 propagating through the core,
Only light of a specific wavelength corresponding to the period is partially reflected and diffracted and fed back to the semiconductor laser 14. Therefore,
The oscillation wavelength of the semiconductor laser 14 is locked to the selected wavelength of the partially reflective fiber grating 58.

In this case, the light beam 13 transmitted through the partial reflection type fiber grating 58 is used for the sample analysis by the surface plasmon.

Next, a tenth embodiment of the present invention will be described with reference to FIG. The oscillation wavelength stabilizing means 50C of the device of the tenth embodiment is provided with a condenser lens 59 for converging the backward emitted light 13Q emitted from the semiconductor laser 14 and a converging position of the backward emitted light 13Q by the condenser lens 59. It is composed of a reflection type fiber grating 54 arranged so that the end faces are located.

The backward emission light 13Q reflected by the reflection type fiber grating 54 is fed back to the semiconductor laser 14, whereby the oscillation wavelength of the semiconductor laser 14 is locked to the selected wavelength of the reflection type fiber grating 54.

Next, an eleventh embodiment of the present invention will be described with reference to FIG. The device of the eleventh embodiment is basically different from the device shown in FIG. 2 in that a substantially rectangular parallelepiped dielectric block 62 made of glass is used in place of the prism 10. This dielectric block 62
Are coupled to the upper surface of the prism 60 via a refractive index matching liquid 61.

In this apparatus, the light beam 13 is introduced through the prism 60 so as to be totally reflected at the interface 62a between the dielectric block 62 and the metal film 12. The dielectric block 62 and the prism 60 are formed of the same material as each other, and are coupled via the refractive index matching liquid 61 having the same refractive index as those of the dielectric block 62, so that they are optically integrated. The structure is the same as that when a prism is used.

Although the embodiment in which the oscillation wavelength of the light source is stabilized by the optical feedback has been described above, the present invention does not use such an optical feedback method, but uses a DFB (distributed feedback) as the light source.
Laser or DBR (distributed Bragg reflec)
tor: distributed Bragg reflection type) laser or the like, and it is also possible to use a light source originally provided with oscillation wavelength stabilizing means.
In that case, the same effect is obtained.

Further, as the oscillation wavelength stabilizing means, means for stabilizing the oscillation wavelength by electrically and precisely controlling the driving current and temperature of the laser can also be applied.

The present invention is not limited to the surface plasmon sensor of the type described above, but, for example, a layer of a substance that specifically binds to the substance to be measured is provided on the metal film to detect only a specific component. The present invention can also be applied to a surface plasmon sensor, for example, a sensor for detecting an antigen-antibody reaction, a surface plasmon sensor for measuring a two-dimensional distribution of physical properties of an object to be measured placed on a metal film, and the like.

[Brief description of drawings]

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

FIG. 2 is a side view showing a part of the surface plasmon sensor shown in FIG.

FIG. 3 is a graph showing a schematic relationship between an incident angle of a light beam on a surface plasmon sensor and a light intensity detected by a light detecting means.

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

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

FIG. 6 is a plan view of a surface plasmon sensor according to a fourth embodiment of the present invention.

FIG. 7 is a plan view of a surface plasmon sensor according to a fifth embodiment of the present invention.

FIG. 8 is a plan view of a surface plasmon sensor according to a sixth embodiment of the present invention.

FIG. 9 is a plan view of a surface plasmon sensor according to a seventh embodiment of the present invention.

FIG. 10 is a plan view of a surface plasmon sensor according to an eighth embodiment of the present invention.

FIG. 11 is a plan view of a surface plasmon sensor according to a ninth embodiment of the present invention.

FIG. 12 is a plan view of a surface plasmon sensor according to a tenth embodiment of the present invention.

FIG. 13 is a side view showing a part of the surface plasmon sensor according to the eleventh embodiment of the present invention.

[Explanation of symbols]

10 prism 10a Interface between prism and metal film 11 samples 12 Metal film 13 light beam 13R branched light beam 13Q rear emission light 14 Semiconductor laser 15 Incident optical system 16 First light detecting means 17 Second light detecting means 18 Comparator 20 Collimator lens 21 beam expander 22 Focusing lens 30, 30A, 30B oscillation wavelength stabilization means 31 λ / 2 plate 32 beam splitter 33 Reflective grating 34 partially reflective grating 35 collimator lens 40, 40A, 40B oscillation wavelength stabilization means 41 Narrow transmission band-pass filter 42 Condenser lens 43 mirror 44 Condensing lens 45 half mirror 46,47 Collimator lens 50, 50A, 50B, 50C oscillation wavelength stabilization means 51 beam splitter 52 mirror 53, 55, 59 Condenser lens 54 Reflective Fiber Grating 56 First Fiber 57 Second fiber 58 partially reflective fiber grating 60 prism 61 Refractive index matching liquid 62 Dielectric block 62a Interface between dielectric block and metal film

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-167443 (JP, A) JP-A-4-151546 (JP, A) JP-A-6-347848 (JP, A) JP-A-6- 75261 (JP, A) JP-A-4-196188 (JP, A) JP-A-3-169089 (JP, A) JP-A-9-97940 (JP, A) JP-A-8-505951 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 21/00-21/01 G01N 21/17-21/61 G01N 21/62-21/74 Practical file (PATOLIS) Patent file (PATOLIS) JISST file (JOIS) WPI (DIALOG)

Claims (19)

(57) [Claims] 1. A dielectric block, a metal film formed on one surface of the dielectric block and brought into contact with a sample, a light source for generating a light beam, and introducing the light beam into the dielectric block, Total reflection conditions are established at the interface between the dielectric block and the metal film, and
An optical system that makes incident light such that various incident angles including surface plasmon generation conditions are obtained, and a light detection unit that can detect the intensity of the light beam totally reflected at the interface at various incident angles are provided. In this surface plasmon sensor, a laser provided with an oscillation wavelength stabilizing means incorporating a wavelength selecting means is used as the light source. 2. The laser is a semiconductor laser, the oscillation wavelength stabilizing means feeds back a part of the laser beam emitted from the semiconductor laser to the semiconductor laser, and the fed-back laser beam. 2. The surface plasmon sensor according to claim 1, wherein the surface plasmon sensor comprises: 3. The surface plasmon sensor according to claim 2, wherein the wavelength selecting means is a bulk grating. 4. An optical system for performing the feedback,
An optical branching unit arranged in the optical path of the laser beam from the semiconductor laser to the dielectric block and branching a part of the laser beam, and the laser beam branched by the optical branching unit follows an optical path in the opposite direction. 4. The surface plasmon sensor according to claim 3, wherein the surface plasmon sensor is composed of a reflection type grating that reflects light to the surface, and the reflection type grating also serves as the wavelength selecting means. 5. An optical system for performing the feedback and the wavelength selection means are arranged in a light path of a laser beam from the semiconductor laser toward the dielectric block and are partially reflective gratings for reflecting a part of the laser beam. The surface plasmon sensor according to claim 3, which is configured. 6. The optical system for performing the feedback and the wavelength selecting means are constituted by a reflection type grating that reflects backward emission light emitted in a direction opposite to a laser beam traveling from the semiconductor laser toward the dielectric block. The surface plasmon sensor according to claim 3, wherein 7. The surface plasmon sensor according to claim 2, wherein the wavelength selecting means is composed of a narrow transmission bandpass filter. 8. An optical system for performing the feedback,
An optical branching unit arranged in the optical path of the laser beam from the semiconductor laser to the dielectric block and branching a part of the laser beam, and the laser beam branched by the optical branching unit follows an optical path in the opposite direction. 8. The surface plasmon sensor according to claim 7, wherein the surface plasmon sensor comprises a mirror for reflecting light in a narrow range, and the narrow transmission bandpass filter is arranged in an optical path of a laser beam between the mirror and the semiconductor laser. 9. An optical system for performing the feedback,
The semiconductor laser includes a half mirror arranged in the optical path of the laser beam toward the dielectric block to reflect a part of the laser beam, and the narrow path is provided in the optical path of the laser beam between the half mirror and the semiconductor laser. The surface plasmon sensor according to claim 7, further comprising a transmission band-pass filter. 10. An optical system for performing the feedback is composed of a mirror for reflecting backward emission light emitted from the semiconductor laser in a direction opposite to a laser beam directed to the dielectric block, and the mirror and the semiconductor laser. 8. The surface plasmon sensor according to claim 7, wherein the narrow transmission bandpass filter is arranged in the optical path of the laser beam between them. 11. The wavelength selecting means is an optical fiber in which a plurality of refractive index changing portions are formed in a core at equal intervals, and comprises a fiber grating for reflecting and diffracting the laser beam. The surface plasmon sensor described. 12. An optical system for performing the feedback is arranged in an optical path of a laser beam from the semiconductor laser toward the dielectric block, and an optical branching unit for branching a part of the laser beam, and the optical branching unit are provided. The surface plasmon sensor according to claim 11, wherein the surface plasmon sensor comprises a fiber grating that reflects the branched laser beam so as to follow an optical path in the opposite direction, and the fiber grating also serves as the wavelength selecting means. 13. A partially reflective fiber grating, wherein the optical system for performing the feedback and the wavelength selecting means are arranged in an optical path of a laser beam from the semiconductor laser toward the dielectric block and reflect a part of the laser beam. The surface plasmon sensor according to claim 11, which is configured by: 14. The optical system for performing the feedback and the wavelength selecting means are configured by a fiber grating that reflects backward emitted light emitted in a direction opposite to a laser beam traveling from the semiconductor laser toward the dielectric block. The surface plasmon sensor according to claim 11, wherein 15. A DFB (distributed feedback) laser is used as the laser provided with the oscillation wavelength stabilizing means.
The surface plasmon sensor described. 16. The surface plasmon sensor according to claim 1, wherein a DBR (distributed Bragg reflector) laser is used as the laser provided with the oscillation wavelength stabilizing means. 17. The surface plasmon sensor according to claim 1, wherein the oscillation wavelength stabilizing means is means for electrically controlling the oscillation wavelength of the laser. 18. The method according to claim 1, wherein the dielectric block is formed in a prism shape.
7. The surface plasmon sensor according to claim 1. 19. The dielectric block is integrated with a prism having a refractive index equal to that of the dielectric block through a refractive index matching liquid having a refractive index equal to that of the dielectric block, and the light beam passes through the prism to cause the dielectric beam to pass through the prism. 2. It is introduced on one side of the body block, characterized in that
7. The surface plasmon sensor according to claim 1.