JP3926409B2 - Surface plasmon sensor - Google Patents

Description

【０００９】
試料の誘電率ε_s が分かれば、所定の較正曲線等に基づいて試料中の特定物質の濃度が分かるので、結局、上記反射光強度が低下する入射角θ_SPを知ることにより、試料中の特定物質を定量分析することができる。
【００１０】
【発明が解決しようとする課題】
ところで、以上説明したタイプの表面プラズモンセンサーを使用する場合、作業能率を高めるために、複数の試料についての分析を一度にまとめて行ないたいという要求がある。そのために、１つの光源から発生させた光ビームを複数本に分割し、それら複数本の光ビームをプリズムの金属膜形成面に同時入射させてマルチチャンネル化することが考えられる。
【００１１】
しかし、そのようにした場合は各チャンネルの光量を十分に確保できず、光検出信号のＳ／Ｎが低下し、分析精度が悪くなってしまうため、チャンネル数を余り多く設定できない場合がある。
【００１２】
本発明は上記の事情に鑑みてなされたものであり、多数の試料についての分析を一度にまとめて行なうことができ、そして各チャンネルに対するビーム光量を十分に確保して、高い分析精度を得ることができる表面プラズモンセンサーを提供することを目的とするものである。
【００１３】
【課題を解決するための手段】
本発明による表面プラズモンセンサーは、前述したようなプリズムと、金属膜と、光ビームを発生させる光源と、光学系と、光検出手段とを備えてなる表面プラズモンセンサーにおいて、光源として複数の発光部を備えた半導体レーザーアレイを用い、そこから発せられた複数本の光ビームを利用して複数チャンネルについての分析を同時に、あるいはほぼ同時に行なえるようにしたものである。
【００１４】
すなわち本発明による第１の表面プラズモンセンサーは、より具体的には、
プリズムと、
このプリズムの一面に形成されて、試料に接触させられる金属膜と、
複数の発光部を有し、各発光部からそれぞれ光ビームを発する半導体レーザーアレイと、
この半導体レーザーアレイから発せられた複数本の光ビームを上記プリズムに通し、該プリズムと金属膜との界面に対して、各光ビームの中で種々の入射角が得られるように入射させる光学系と、
上記界面で全反射した各光ビームの強度を、上記種々の入射角毎に検出可能な光検出手段とを備えてなるものである。
【００１５】
そして、本発明による上記第１の表面プラズモンセンサーにおいて、さらに詳しくは、
半導体レーザーアレイが、その複数の発光部から同時に光ビームを発するように駆動され、
上記光学系が、前記複数の発光部から発せられた光ビームを前記界面に対する入射面内のみで集光するシリンドリカルレンズと、前記光ビームの各々をそのビーム軸を含んで前記入射面と直交する面内のみで平行光化して該界面の互いに別の位置に導くシリンドリカルレンズとからなる入射側光学系、および、前記界面で全反射した前記光ビームを前記入射面内のみで平行光化するシリンドリカルレンズと、該光ビームの各々をそのビーム軸を含んで前記入射面と直交する面内のみで集光するシリンドリカルレンズとからなる出射側光学系を有して、プリズムと金属膜との界面で全反射した複数の光ビームを互いに別の位置に集光するように構成され、
光検出手段として、集光された複数の光ビームをそれぞれ別個に受光する、各光ビーム毎に専用の受光素子列が、光ビームの並び方向に複数並設されてなるものが用いられる。
【００１７】
【発明の効果】
本発明の表面プラズモンセンサーにおいては、半導体レーザーアレイから発せられた複数本の光ビームを利用できるので、多数の試料についての分析を一度にまとめて同時に、あるいはほぼ同時に行なうことができる。
【００１８】
そして各チャンネルにおいて使用される光ビームは、本来１本の光ビームを複数本に分割したようなものではなく、半導体レーザーアレイの複数の発光部から各々発せられたものであるから、それぞれの光量を十分に確保して、高い分析精度を得ることができる。
【００１９】
なお、本発明による第１の表面プラズモンセンサーにおいては、半導体レーザーアレイから発せられる複数本の光ビームを並列的に使用して、複数チャンネルについての分析を同時に行なうことができる。
【００２０】
一方、本発明による第２の表面プラズモンセンサーにおいては、複数チャンネルについての分析を全く同時に行なうことはできないが、光検出手段として、複数の光ビームに対して共通の受光部を有する簡単な構成のものが用いられるから、この表面プラズモンセンサーは比較的低コストで作製可能となる。
【００２１】
【発明の実施の形態】
以下、図面を参照して本発明の実施の形態を詳細に説明する。図１および図２はそれぞれ、本発明の１つの実施形態である表面プラズモンセンサーの平面形状、側面形状を示すものである。
【００２２】
図示されるようにこの表面プラズモンセンサーは、半円柱形のプリズム10と、このプリズム10の一面（図２中の下面）に形成されて、試料11に接触させられる例えば金、銀等からなる金属膜12と、一例として５個の発光部（ストライプ）14ａを有してそれらから各々光ビーム13を発生させる半導体レーザーアレイ14と、上記光ビーム13をプリズム10に通し、該プリズム10と金属膜12との界面10ａに対して、１本の光ビーム13毎に種々の入射角が得られるように入射させる光学系15と、上記界面10ａで全反射した光ビーム13の強度を検出する光検出手段16とを備えている。
【００２３】
光学系15は、半導体レーザーアレイ14の各発光部14ａから発散光状態で出射した光ビーム13をプリズム10の長軸に垂直な面内のみで集光する入射側シリンドリカルレンズ22、24と、この光ビーム13を平面視状態で平行光化する入射側シリンドリカルレンズ23と、全反射して上記面内で発散光状態となった光ビーム13を平行光化する出射側シリンドリカルレンズ25と、この光ビーム13を平面視状態で集光する出射側シリンドリカルレンズ26とから構成されている。なおシリンドリカルレンズ26による５本の光ビーム13の集光位置は、互いに異なるものとされている。
【００２４】
各光ビーム13は、入射側シリンドリカルレンズ22および24の作用により上述のように集光されて集束するので、図２に最小入射角θ_１ と最大入射角θ_２ とを例示するように、界面10ａに対して種々の入射角θで入射する成分を含むことになる。なおこの入射角θは、全反射角以上の角度とされる。そこで、各光ビーム13は界面10ａで全反射し、この反射した光ビーム13には、種々の反射角で反射する成分が含まれることになる。
【００２５】
一方光検出手段16としては、種々の反射角で反射した全部の光ビーム13を受光できる方向、つまり図２の矢印Ａ方向に多数の受光素子が並設されるとともに、このような受光素子列が図１の矢印Ｂ方向に５本並設されてなる、例えばＣＣＤエリアセンサ等が用いられている。この光検出手段16は、上記５本の受光素子列がそれぞれ、シリンドリカルレンズ26による５本の光ビーム13の集光位置と整合するように配置されている。
【００２６】
そこで、該光検出手段16の各受光素子列毎に出力される光検出信号Ｓ₁ 、Ｓ₂ 、Ｓ₃ 、Ｓ₄ 、Ｓ₅ は、５本の光ビーム13の強度を個別に示すものとなる。また１組の光検出信号Ｓm （ｍ＝１、２、３、４、５）における各受光素子毎の光検出信号は、上記種々の反射角毎に（つまり、種々の入射角毎に）光ビーム13の強度を示すものとなる。
【００２７】
以下、上記構成の表面プラズモンセンサーによる試料分析について説明する。金属膜12は複数（一例として５個）設けられており、各金属膜12に対してそれぞれ別個の試料11を接触させておくことができる。複数の金属膜12は、全て同じものが用いられても、あるいは互いに別のものが用いられてもよい。
【００２８】
試料分析に際しては、入射側シリンドリカルレンズ22および24の作用で前述のように集束する５本の光ビーム13が、それぞれ金属膜12に向けて同時に照射される。この金属膜12とプリズム10との界面10ａで全反射した光ビーム13は、光検出手段16によって検出される。
【００２９】
前述の通り、光検出手段16の各受光素子列毎に出力される光検出信号Ｓm は、全反射した光ビーム13の強度Ｉを入射角θ毎に示すものとなる。そしてこの反射光強度Ｉと入射角θとの関係は、概ね図３に示すようなものとなる。
【００３０】
ここで、ある特定の入射角θ_SPで入射した光は、金属膜12と試料11との界面に表面プラズモンを励起させるので、この光については反射光強度Ｉが鋭く低下する。光検出手段16の各受光素子毎に出力される光検出信号Ｓを用いれば上記入射角θ_SPが分かり、このθ_SPの値に基づいて試料11中の特定物質を定量分析することができる。その理由は、先に詳しく説明した通りである。
【００３１】
そして、５つの金属膜12に向けてそれぞれ光ビーム13が照射されるので、光検出手段16の各受光素子列毎に光検出信号Ｓ₁ 、Ｓ₂ 、Ｓ₃ 、Ｓ₄ 、Ｓ₅ が出力され、各金属膜12に接触している５個の試料11の分析が同時になされ得る。このようにして、本装置によれば、複数の試料11についての分析を短い時間間隔で一度にまとめて行なえるようになる。
【００３２】
また、各チャンネルにおいて使用される光ビーム13は、本来１本の光ビームを複数本に分割したようなものではなく、半導体レーザーアレイ14の複数の発光部14ａから各々発せられたものであるから、それぞれの光量を十分に確保して、高い分析精度を得ることができる。
【００３３】
なお半導体レーザーアレイ14は、その複数の発光部14ａから時間間隔を置いて順次光ビーム13を発するように駆動されてもよい。その場合は、前記界面10ａで全反射した複数の光ビーム13を互いに共通の位置に集光するように光学系を形成すれば、光検出手段16として、集光された複数の光ビーム13に対して共通の受光部を有する比較的簡単な構成のものを用いることができる。
【図面の簡単な説明】
【図１】本発明の一実施形態である表面プラズモンセンサーの平面図
【図２】上記表面プラズモンセンサーの側面図
【図３】表面プラズモンセンサーにおける光ビーム入射角と光検出手段の出力との概略関係を示すグラフ
【符号の説明】
10 プリズム
10ａ プリズムと金属膜との界面
11 試料
12 金属膜
13 光ビーム
14 半導体レーザーアレイ
14ａ 半導体レーザーアレイの発光部
15 光学系
16 光検出手段
22、23 、24 入射側シリンドリカルレンズ
25 、 26 出射側シリンドリカルレンズ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface plasmon sensor that quantitatively analyzes a substance in a sample using generation of surface plasmons, and more particularly to a surface plasmon sensor that can perform analysis on a plurality of samples at a time. .
[0002]
[Prior art]
In the metal, free electrons collectively vibrate to generate a dense wave called a plasma wave. A quantized version of this dense wave generated on the metal surface is called surface plasmon.
[0003]
Conventionally, various surface plasmon sensors that quantitatively analyze a substance in a sample using a phenomenon in which the surface plasmon is excited by a light wave have been proposed. Among them, one that uses a system called a Kretschmann arrangement is particularly well known (see, for example, JP-A-6-167443).
[0004]
A surface plasmon sensor using the above system basically includes a prism, a metal film formed on one surface of the prism and brought into contact with a sample, a light source for generating a light beam, and passing the light beam through the prism. An optical system for making the incident angle so that various incident angles can be obtained with respect to the interface between the prism and the metal film; and a light detecting means capable of detecting the intensity of the light beam totally reflected at the above-mentioned interface at each incident angle. Is provided.
[0005]
In order to obtain various incident angles as described above, a relatively thin light beam may be deflected and incident on the interface, or a component that is incident on the light beam at various angles may be included. 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 is detected by a small photodetector that moves synchronously with the deflection of the light beam, or by an area sensor that extends along the direction of change of the reflection angle. Can be detected. On the other hand, in the latter case, it can be detected by an area sensor extending in a direction in which each light beam reflected at various reflection angles can be received.
[0006]
In the surface plasmon sensor having the above configuration, when a light beam is incident on the metal film at a specific incident angle θ _SP greater than the total reflection angle, an evanescent wave having an electric field distribution is generated in the sample in contact with the metal film, This evanescent wave excites surface plasmons at the interface between the metal film and the sample. 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 light energy is transferred to the surface plasmon, so that it is totally reflected at the interface between the prism and the metal film. The intensity of light decreases sharply.
[0007]
If the wave number of the surface plasmon is known from the incident angle θ _{SP at} which this phenomenon occurs, the dielectric constant of the sample can be obtained. That is, when the wave number of surface plasmon is K _SP , the angular frequency of surface plasmon is ω, c is the speed of light in vacuum, ε _m and ε _s are metal, and the dielectric constant of the sample is as follows.
[0008]
[Expression 1]

[0009]
If the dielectric constant ε _s of the sample is known, the concentration of the specific substance in the sample can be known based on a predetermined calibration curve or the like, so eventually, by knowing the incident angle θ _{SP at} which the reflected light intensity decreases, Specific substances can be quantitatively analyzed.
[0010]
[Problems to be solved by the invention]
By the way, when a surface plasmon sensor of the type described above is used, there is a demand for performing analysis on a plurality of samples at once in order to increase work efficiency. For this purpose, it is conceivable to divide the light beam generated from one light source into a plurality of light beams, and to make the light beams incident simultaneously on the metal film forming surface of the prism to be multi-channeled.
[0011]
However, in such a case, the light quantity of each channel cannot be secured sufficiently, the S / N of the light detection signal is lowered, and the analysis accuracy is deteriorated, so that the number of channels may not be set too much.
[0012]
The present invention has been made in view of the above circumstances, and can analyze a large number of samples all at once, and can secure a sufficient amount of light for each channel to obtain high analysis accuracy. It is an object of the present invention to provide a surface plasmon sensor that can be used.
[0013]
[Means for Solving the Problems]
A surface plasmon sensor according to the present invention is a surface plasmon sensor including a prism, a metal film, a light source that generates a light beam, an optical system, and a light detection unit as described above. And a plurality of light beams emitted from the semiconductor laser array can be used to analyze a plurality of channels simultaneously or substantially simultaneously.
[0014]
That is, the first surface plasmon sensor according to the present invention is more specifically ,
Prism,
A metal film formed on one surface of the prism and brought into contact with the sample;
A semiconductor laser array having a plurality of light emitting portions, each emitting a light beam from each light emitting portion;
An optical system in which a plurality of light beams emitted from the semiconductor laser array are passed through the prism and incident on the interface between the prism and the metal film so that various incident angles can be obtained in each light beam. When,
And a light detecting means capable of detecting the intensity of each light beam totally reflected at the interface for each of the various incident angles.
[0015]
In the first surface plasmon sensor according to the present invention, more specifically,
The semiconductor laser array is driven to emit a light beam simultaneously from the plurality of light emitting portions,
The optical system includes a cylindrical lens that condenses the light beams emitted from the plurality of light emitting units only within the incident surface with respect to the interface, and each of the light beams is orthogonal to the incident surface including its beam axis. An incident-side optical system comprising a cylindrical lens that collimates only in the plane and guides it to different positions on the interface, and a cylindrical that collimates the light beam totally reflected on the interface only in the incident plane An emission side optical system comprising a lens and a cylindrical lens that condenses each of the light beams only in a plane orthogonal to the incident surface including the beam axis, at the interface between the prism and the metal film It is configured to collect a plurality of totally reflected light beams at different positions,
As the light detection means, a plurality of light receiving elements arrayed separately in the light beam alignment direction for receiving each of the collected light beams separately and used for each light beam is used.
[0017]
【The invention's effect】
In the surface plasmon sensor of the present invention, since a plurality of light beams emitted from the semiconductor laser array can be used, analysis of a large number of samples can be performed simultaneously or almost simultaneously.
[0018]
The light beam used in each channel is not originally a light beam divided into a plurality of light beams but is emitted from a plurality of light emitting portions of the semiconductor laser array. Can be secured sufficiently and high analysis accuracy can be obtained.
[0019]
In the first surface plasmon sensor according to the present invention, by using a plurality of light beams emitted from the semiconductor laser array in parallel, it is possible to perform analysis of multiple channels simultaneously.
[0020]
On the other hand, in the second surface plasmon sensor according to the present invention, can not be carried out at exactly the same time the analysis of a plurality of channels, as the light detecting means, a simple structure of having a common light-receiving portion for a plurality of light beams Since this is used, the surface plasmon sensor can be manufactured at a relatively low cost.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 and FIG. 2 show a planar shape and a side shape of a surface plasmon sensor which is one embodiment of the present invention, respectively.
[0022]
As shown in the figure, the surface plasmon sensor is formed of a semi-cylindrical prism 10 and a metal made of, for example, gold, silver or the like, which is formed on one surface (the lower surface in FIG. 2) of the prism 10 and brought into contact with the sample 11. A film 12, a semiconductor laser array 14 having, for example, five light emitting portions (stripes) 14a, each of which generates a light beam 13, and the light beam 13 passed through a prism 10, and the prism 10 and a metal film The optical system 15 is incident so that various incident angles are obtained for each of the light beams 13 with respect to the interface 10a with the light 12, and light detection for detecting the intensity of the light beam 13 totally reflected at the interface 10a. Means 16 are provided.
[0023]
The optical system 15 includes incident side cylindrical lenses 22 and 24 that condense the light beam 13 emitted in a divergent light state from each light emitting portion 14a of the semiconductor laser array 14 only in a plane perpendicular to the major axis of the prism 10, and An incident side cylindrical lens 23 that collimates the light beam 13 in a plan view, an exit side cylindrical lens 25 that collimates the light beam 13 that has been totally reflected and diverged in the plane, and this light. It comprises an exit side cylindrical lens 26 that condenses the beam 13 in a plan view. The condensing positions of the five light beams 13 by the cylindrical lens 26 are different from each other.
[0024]
Each light beam 13, so focused is condensed as described above by the action of the incident-side cylindrical lens 22 and 24, to illustrate the minimum incident angle theta ₁ and the maximum incident angle theta ₂ in FIG. 2, the interface The component which injects with respect to 10a with various incident angles (theta) is included. In addition, this incident angle (theta) shall be an angle more than a total reflection angle. Therefore, each light beam 13 is totally reflected at the interface 10a, and the reflected light beam 13 includes components reflected at various reflection angles.
[0025]
On the other hand, as the light detection means 16, a number of light receiving elements are arranged in parallel in the direction in which all the light beams 13 reflected at various reflection angles can be received, that is, in the direction of arrow A in FIG. Are arranged in the direction of arrow B in FIG. 1, for example, a CCD area sensor or the like is used. The light detection means 16 is arranged so that the five light receiving element arrays are aligned with the condensing positions of the five light beams 13 by the cylindrical lens 26, respectively.
[0026]
Therefore, the light detection signals S ₁ , S ₂ , S ₃ , S ₄ and S ₅ output for each light receiving element array of the light detection means 16 individually indicate the intensities of the five light beams 13. Become. The light detection signal for each light receiving element in one set of light detection signals Sm (m = 1, 2, 3, 4, 5) is light for each of the various reflection angles (that is, for each of various incident angles). The intensity of the beam 13 is indicated.
[0027]
Hereinafter, sample analysis by the surface plasmon sensor having the above-described configuration will be described. A plurality of (for example, five) metal films 12 are provided, and a separate sample 11 can be brought into contact with each metal film 12. The plurality of metal films 12 may be the same or may be different from one another.
[0028]
In the sample analysis, the five light beams 13 focused as described above by the action of the incident side cylindrical lenses 22 and 24 are simultaneously irradiated toward the metal film 12, respectively. The light beam 13 totally reflected at the interface 10 a between the metal film 12 and the prism 10 is detected by the light detection means 16.
[0029]
As described above, the light detection signal Sm output for each light receiving element array of the light detection means 16 indicates the intensity I of the totally reflected light beam 13 for each incident angle θ. The relationship between the reflected light intensity I and the incident angle θ is approximately as shown in FIG.
[0030]
Here, the light incident at a specific incident angle θ _SP excites surface plasmons at the interface between the metal film 12 and the sample 11, so that the reflected light intensity I sharply decreases for this light. By using the light detection signal S output for each light receiving element of the light detection means 16, the incident angle θ _SP can be known, and the specific substance in the sample 11 can be quantitatively analyzed based on the value of θ _SP . The reason is as described in detail above.
[0031]
Since the light beams 13 are irradiated toward the five metal films 12, the light detection signals S ₁ , S ₂ , S ₃ , S ₄ and S ₅ are output for each light receiving element array of the light detecting means 16. The five samples 11 in contact with each metal film 12 can be analyzed simultaneously. In this way, according to the present apparatus, the analysis of the plurality of samples 11 can be performed at a time at a short time interval.
[0032]
In addition, the light beam 13 used in each channel is not originally a light beam divided into a plurality of light beams but is emitted from a plurality of light emitting portions 14a of the semiconductor laser array 14, respectively. It is possible to secure a sufficient amount of each light and obtain high analysis accuracy.
[0033]
The semiconductor laser array 14 may be driven so as to emit the light beam 13 sequentially from the plurality of light emitting portions 14a at time intervals. In that case, if an optical system is formed so that the plurality of light beams 13 totally reflected by the interface 10a are condensed at a common position, the light detection means 16 can be used as a plurality of the collected light beams 13. On the other hand, a relatively simple configuration having a common light receiving portion can be used.
[Brief description of the drawings]
FIG. 1 is a plan view of a surface plasmon sensor according to an embodiment of the present invention. FIG. 2 is a side view of the surface plasmon sensor. FIG. 3 is a schematic view of a light beam incident angle and an output of light detection means in the surface plasmon sensor. Graph showing relationships [Explanation of symbols]
10 Prism
10a Interface between prism and metal film
11 samples
12 Metal film
13 Light beam
14 Semiconductor laser array
14a Light emitting part of semiconductor laser array
15 Optical system
16 Light detection means
22, 23 , 24 Incident side cylindrical lens
25 and 26 exit side cylindrical lens

Claims (1)

Prism,
A metal film formed on one surface of the prism and brought into contact with the sample;
A semiconductor laser array having a plurality of light emitting portions and emitting light beams from the respective light emitting portions in a state of traveling in parallel with each other;
An optical system in which a plurality of light beams emitted from the semiconductor laser array are passed through the prism and incident on the interface between the prism and the metal film so that various incident angles can be obtained in each light beam. When,
A surface plasmon sensor comprising a light detecting means capable of detecting the intensity of each light beam totally reflected at the interface at each of the various incident angles,
The semiconductor laser array is driven to emit a light beam simultaneously from the plurality of light emitting portions,
The optical system condenses the light beam emitted from the plurality of light emitting units only within the incident surface with respect to the interface, and each of the light beams includes its beam axis and is orthogonal to the incident surface. An incident-side optical system including a cylindrical lens that collimates light only in the plane and guides it to different positions on the interface, and a cylindrical beam that collimates the light beam totally reflected on the interface only in the incident surface A plurality of light beams that are totally reflected at the interface, each having an emission side optical system that includes a lens and a cylindrical lens that collects each of the light beams in a plane that includes the beam axis and is orthogonal to the incident surface. Configured to focus the light beams at different positions,
As the light detecting means, a light receiving element array for receiving each of the collected light beams separately, and a plurality of dedicated light receiving element arrays for each light beam arranged in parallel in the light beam alignment direction is used. Surface plasmon sensor characterized by

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