JP3980457B2

JP3980457B2 - Scattered light measurement device

Info

Publication number: JP3980457B2
Application number: JP2002273845A
Authority: JP
Inventors: 三直関和; 和典筒井; 且廣森沢; 尚司藤本; 篤豊島
Original assignee: Otsuka Electronics Co Ltd
Current assignee: Otsuka Electronics Co Ltd
Priority date: 2002-09-19
Filing date: 2002-09-19
Publication date: 2007-09-26
Anticipated expiration: 2022-09-19
Also published as: JP2004109011A

Description

【０００１】
【発明の属する技術分野】
本発明は、溶液に光を照射し、散乱体積内から散乱される光を検出することにより散乱光測定を行う散乱光測定装置に関するものである。
【０００２】
【従来の技術】
散乱光測定装置は、流体中に存在する粒子の動き（ブラウン運動）による散乱光の経時変化を測定する装置である。
従来の散乱光測定装置では、溶液の入った直方体のセルに対してレンズで絞ったレーザ光を照射し、その散乱光をフォトマルチプライヤ等の受光素子で測定していた。
【０００３】
溶液の濃度が濃い場合、粒子に当たって散乱された光がまた他の粒子に当たって測定されるという多重散乱の問題が起こる。
濃厚溶液では、この多重散乱の影響を避けることが、正確な測定のために重要である。
そのために、測定する散乱角度を１８０度近くに設定することが有効である。そこで従来では、照射光を集光する集光レンズと、散乱光を集める対物レンズとを同じレンズで共用する構成の光学系を採用している。
【０００４】
【特許文献１】
特開平11-51843号公報
【０００５】
【発明が解決しようとする課題】
この場合、測定する散乱角度をできるだけ大きくする（限りなく１８０度に近くする）ためには、集光レンズの焦点距離を長くするか、投光軸と受光軸との間隔を小さくすることが重要である。
集光レンズの焦点距離を長くすると焦点の像が大きくなる（散乱ビーム径が大きくなる）ので、投光軸と受光軸との間隔を小さくすることが好ましい。
【０００６】
このためには、光源の光を平行光束にして集光レンズに入れる投光レンズと、同じ集光レンズで集められた試料溶液からの散乱光を受光器に照射する受光レンズとを近づける必要があるが、投光レンズと受光レンズとを近づけるには、投光レンズと受光レンズとの口径の制限がある。
投光レンズの口径を小さくすると光源の光量が不足するし、受光レンズの口径を小さくすると検出する散乱光の検出感度が不足してしまう。
【０００７】
そこで、本発明は、散乱ビーム径を大きくせず、散乱光量を低下させることなく、投光軸と受光軸との間隔を小さくして、できるだけ大きな散乱角度を確保することができる散乱光測定装置を実現することを目的とする。
【０００８】
【課題を解決するための手段及び発明の効果】
本発明の散乱光測定装置は、光源と、試料溶液を収容する容器と、光源の光を平行光束にする投光レンズと、当該平行光束を集めて試料溶液に照射する集光レンズと、同じ集光レンズで集められた試料溶液からの散乱光を受光器に入射させる受光レンズと、受光器とを備え、両面が平行平面状の光軸調整板を、投光レンズと集光レンズとの間の投光軸上、又は受光レンズと集光レンズとの間の受光軸上の平行光束の部分に傾けて設置したものである（請求項１）。
【０００９】
前記の構成によれば、光軸調整板を投光レンズと受光レンズとの間の平行光束の部分に、傾けて設置したことにより、平行光束同士の間隔を、平行関係を保ったまま近づけることができる。したがって、投光光量、受光光量を減らさないで散乱角を１８０度に近づけることができる。
前記光軸調整板は、投光軸上及び受光軸上の両方に設置することもできる（請求項２）。
【００１０】
【発明の実施の形態】
以下、本発明の実施の形態を、添付図面を参照しながら詳細に説明する。
図１(a)は本発明の実施形態にかかる散乱光測定装置を示す平面図、図１(b)は側面図である。
光源２の光は、アパーチャ３を通過し、投光レンズ４によって平行光束にされる。当該平行光束は、集光レンズ５で集められてセル中の試料溶液Ｓに照射される。た試料溶液Ｓからの散乱光は、集光レンズ５で集められ、受光レンズ６、アパーチャ７を通して受光器８によって検出される。
【００１１】
前記光源２は、白色光源とモノクロメータの組み合わせで構成してもよく、レーザ発振装置などで構成してもよい。前記受光器８は、ＣＣＤなどの半導体素子で構成されたものでもよく、光電子増倍管などでもよい。
試料溶液Ｓは、セルに収容されているが、図では、セル壁の一部をなす、光透過窓９のみを描いている。
この実施形態では、平行な平面により両面が構成された光軸調整板Ｔ，Ｊを、投光軸上の投光レンズ４と集光レンズ５との間、及び受光軸上の集光レンズ５と受光レンズ６との間に設置している。
【００１２】
光軸調整板Ｔ，Ｊの材質は、光を透過させるものなら何でもよく、ガラス、セラミック、合成樹脂などを用いることができる。ただし、屈折率は、空気の屈折率とは異なるものでなければならない。
ここで、図２を用いて試料溶液Ｓ中の散乱部分の説明をする。投光軸に沿って照射された光は、散乱体積（図４の斜線部分）から散乱され、その一部が受光軸に沿って射出し、測定される。
【００１３】
投光ビームの径と、受光ビームの径とが重なる部分の長さを重なり長Ｌ、重なる部分の直径を散乱ビーム径Ｄで示している。また、投光軸と受光軸とがなす角度を散乱角φで示している。
図１に戻り、光軸調整板Ｔ，Ｊと、光軸とのなす角度は、固定されていてもよく、可変であってもよい。この傾き角度をα1と書く。
傾ける場合の回転軸の方向は、図１のＹ軸の方向とする。また、傾ける方向は、光軸調整板Ｔ，Ｊの屈折率が空気の屈折率よりも高い場合は、図１に示したように、光軸調整板Ｔと光軸調整板Ｊとが、互いに試料溶液Ｓ中の焦点位置を向く方向にする。
【００１４】
傾き角度α1を変化させる場合、可変方法はどんな方法を用いてもよいが、例えば、図３に示すように、光軸調整板Ｔ，Ｊを一軸回りに回転可能に取り付けて、プーリ１１、ベルト１２を介してモータ１３で回転駆動する方法があげられる。
光軸調整板と、入射光軸とのなす角度α1を０°からずらすと出射光軸が移動する原理を、図４を用いて説明する。光軸調整板の屈折率をｎ、厚さをｔとする。
【００１５】
図４に示すように、光軸調整板の入射面２１に立てられた法線と入射光軸Ａ１との傾き角をα1とする。入射光は、光軸調整板の入射面２１で屈折する。その屈折角をα2で表している。屈折された光は、光軸調整板の出射面２２でさらに屈折する。その屈折角はα1となる。光軸調整板の入射面２１上の入射点と、出射面２２上の出射点との位置ずれを、光軸に垂直に測定すると、Δｄとなる。Δｄは、幾何光学的考察から、
Δｄ＝ｔsin（α1−α2）／cosα2
＝ｔ sinα1［１− cosα1／√(n²- sin²α1)］
で表される。このように、光軸の位置ずれΔｄは、光軸調整板と入射光軸との傾き角α1の関数で表される。
【００１６】
したがって、光軸調整板を傾けることにより、光軸をずらすことができる。
投光軸上の光軸調整板Ｔを、投光軸が受光軸に近づくように傾け、受光軸上の光軸調整板Ｊを、受光軸が投光軸に近づくように傾けると、投光軸、受光軸間の間隔ｄ（図１参照）は、
ｄ―２Δｄ
となる。
【００１７】
このように光軸調整板Ｔ，Ｊを設置して投光軸、受光軸間の間隔ｄを狭くすることができるので、投光レンズ４、受光レンズ６はそのままで、散乱角φを１８０度に近づけることができる。
なお、図１の実施形態では、光軸調整板Ｔ，Ｊを、投光軸上の投光レンズ４と集光レンズ５との間、及び受光軸上の集光レンズ５と受光レンズ６との間にそれぞれ設置しているが、光軸調整板Ｔだけ、又は光軸調整板Ｊだけを設置してもよい。この場合は、投光軸、受光軸間の間隔ｄは、
ｄ―Δｄ
となる。
【００１８】
【実施例】
図１に示した光学系で、光軸調整板Ｔ，Ｊを設置しない場合と設置した場合とをシミュレーションしてみた。
【００１９】
【表１】

【００２０】
各レンズ４〜６のパラメータを適当に設定して、ある光学系Ａを構成した。散乱角φ、散乱ビーム径Ｄ、重なり長Ｌは、表１に掲げたように、それぞれ172.6度，12.3μｍ，170μｍであった。
屈折率１.５、厚さ３ｍｍの光軸調整板Ｔを、傾斜角α1＝30度で投光軸上に設置し、屈折率１.５、厚さ３ｍｍの光軸調整板Ｊ、傾斜角α1＝−30度で受光軸上に設置したところ、散乱角φは、表１に掲げたように、2.9度増加して175.5度になり、散乱ビーム径Ｄは変わらず、重なり長Ｌは396μｍ増加して566μｍとなった。
【００２１】
希薄な溶液を想定すれば、散乱光量は、散乱体積に比例する。散乱体積は、３.３倍になるので、散乱光量も３．３倍になる。
したがって、散乱ビーム径Ｄはそのままで、散乱角φを１８０度に近づけることができ、かつ、より明るい散乱光を測定できる。
【００２２】
【表２】

【００２３】
各レンズ４〜６のパラメータを適当に設定して、他の光学系Ｂを構成した。散乱角φ、散乱ビーム径Ｄ、重なり長Ｌは、表２に掲げたように、それぞれ173.9度，14.7μｍ，240μｍであった。
屈折率１.５、厚さ４ｍｍの光軸調整板Ｔを、傾斜角α1＝30度で投光軸上に設置し、屈折率１.５、厚さ４ｍｍの光軸調整板Ｊ、傾斜角α1＝−30度で受光軸上に設置したところ、散乱角φは、表１に掲げたように、3.2度増加して177.1度になり、散乱ビーム径Ｄは変わらず、重なり長Ｌは4376μｍ増加して4619μｍとなった。
【００２４】
散乱光量は18.5倍になった。
したがって、散乱ビーム径Ｄはそのままで、散乱角φを１８０度に近づけることができ、かつ、より明るい散乱光を測定できる。
【００２５】
【発明の効果】
以上のように本発明によれば、投光レンズや受光レンズの口径や焦点距離、集光レンズの焦点距離は特に変えなくても、光軸調整板を平行光束の部分に傾けた状態で設置するだけで、散乱角φを１８０度に近づけることができる。この結果、投受光の重なり長を長くすることができ、散乱光量を多くできる。したがって、散乱光量の少ない希薄溶液から、散乱光量の多い濃厚溶液まで、正確に散乱光の測定を行える、という優れた効果が得られる。
【図面の簡単な説明】
【図１】 (a)は本発明の実施形態にかかる散乱光測定装置を示す平面図、(b)は側面図である。
【図２】試料溶液Ｓ中の散乱部分の重なり長Ｌ、散乱ビーム径Ｄ、散乱角φを示す説明図である。
【図３】光軸調整板を回転させる方法を例示した斜視図である。
【図４】光軸調整板を傾けて光軸を移動させる原理を説明するための光路図である。
【符号の説明】
２光源
３アパーチャ
４投光レンズ
５集光レンズ
６受光レンズ
７アパーチャ
８受光器
９光透過窓
１１プーリ
１２ベルト
１３モータ
２１入射面
２２出射面
Ｄ散乱ビーム径
Ｌ重なり長
Ｓ試料溶液
Ｔ，Ｊ光軸調整板
φ 散乱角[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a scattered light measurement apparatus that measures scattered light by irradiating a solution with light and detecting light scattered from within a scattering volume.
[0002]
[Prior art]
The scattered light measurement device is a device that measures the change with time of scattered light due to the movement of particles (Brownian motion) existing in a fluid.
In a conventional scattered light measurement apparatus, a rectangular cell containing a solution is irradiated with laser light focused by a lens, and the scattered light is measured by a light receiving element such as a photomultiplier.
[0003]
When the concentration of the solution is high, the problem of multiple scattering occurs where light scattered upon the particles is also measured against other particles.
In concentrated solutions, avoiding this multiple scattering effect is important for accurate measurements.
Therefore, it is effective to set the scattering angle to be measured to be close to 180 degrees. Therefore, conventionally, an optical system having a configuration in which a condensing lens that collects irradiation light and an objective lens that collects scattered light are shared by the same lens is employed.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-51843
[Problems to be solved by the invention]
In this case, in order to increase the scattering angle to be measured as much as possible (as close to 180 degrees as possible), it is important to increase the focal length of the condenser lens or to reduce the distance between the light projecting axis and the light receiving axis. It is.
If the focal length of the condensing lens is increased, the focal image becomes larger (the scattered beam diameter becomes larger), so it is preferable to reduce the distance between the light projecting axis and the light receiving axis.
[0006]
For this purpose, it is necessary to bring the light projection lens that converts the light from the light source into a condensing lens into a condensing lens and the light receiving lens that irradiates the light receiver with scattered light from the sample solution collected by the same condensing lens. However, in order to bring the light projecting lens and the light receiving lens closer, there is a limitation on the aperture diameter of the light projecting lens and the light receiving lens.
If the aperture of the light projecting lens is reduced, the light amount of the light source is insufficient, and if the aperture of the light receiving lens is reduced, the detection sensitivity of the scattered light to be detected is insufficient.
[0007]
Accordingly, the present invention provides a scattered light measuring apparatus that can ensure a large scattering angle by reducing the distance between the light projecting axis and the light receiving axis without increasing the scattered beam diameter and reducing the amount of scattered light. It aims at realizing.
[0008]
[Means for Solving the Problems and Effects of the Invention]
The scattered light measurement apparatus of the present invention is the same as a light source, a container for storing a sample solution, a light projecting lens that converts the light from the light source into a parallel light beam, and a condenser lens that collects the parallel light beam and irradiates the sample solution. A light receiving lens for allowing scattered light from the sample solution collected by the light collecting lens to enter the light receiver, and a light receiver, and an optical axis adjusting plate having parallel planes on both sides are provided between the light projecting lens and the light collecting lens. The light beam is installed at a tilted position on the light projecting axis between them or on the portion of the parallel light beam on the light receiving axis between the light receiving lens and the condenser lens.
[0009]
According to the above configuration, the optical axis adjusting plate is installed at an angle to the portion of the parallel light beam between the light projecting lens and the light receiving lens so that the distance between the parallel light beams is reduced while maintaining the parallel relationship. Can do. Therefore, the scattering angle can be brought close to 180 degrees without reducing the light projection amount and the light reception amount.
The optical axis adjusting plate can be installed on both the light projecting axis and the light receiving axis.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 (a) is a plan view showing a scattered light measurement apparatus according to an embodiment of the present invention, and FIG. 1 (b) is a side view.
The light from the light source 2 passes through the aperture 3 and is converted into a parallel light flux by the light projecting lens 4. The parallel light flux is collected by the condenser lens 5 and irradiated onto the sample solution S in the cell. The scattered light from the sample solution S is collected by the condenser lens 5 and detected by the light receiver 8 through the light receiving lens 6 and the aperture 7.
[0011]
The light source 2 may be a combination of a white light source and a monochromator, or a laser oscillation device. The light receiver 8 may be composed of a semiconductor element such as a CCD, or may be a photomultiplier tube.
Although the sample solution S is accommodated in the cell, only the light transmission window 9 forming a part of the cell wall is illustrated in the figure.
In this embodiment, the optical axis adjusting plates T and J having both surfaces constituted by parallel planes are arranged between the light projecting lens 4 and the light collecting lens 5 on the light projecting axis and the light collecting lens 5 on the light receiving axis. And the light receiving lens 6.
[0012]
The material of the optical axis adjusting plates T and J may be anything as long as it transmits light, and glass, ceramic, synthetic resin, or the like can be used. However, the refractive index must be different from the refractive index of air.
Here, the scattering portion in the sample solution S will be described with reference to FIG. The light irradiated along the light projecting axis is scattered from the scattering volume (the hatched portion in FIG. 4), and a part of the light is emitted along the light receiving axis and measured.
[0013]
The length of the overlapping portion of the diameter of the light projecting beam and the diameter of the light receiving beam is indicated by an overlap length L, and the diameter of the overlapping portion is indicated by a scattered beam diameter D. Further, the angle formed by the light projecting axis and the light receiving axis is indicated by a scattering angle φ.
Returning to FIG. 1, the angle formed between the optical axis adjusting plates T and J and the optical axis may be fixed or variable. This inclination angle is written as α1.
The direction of the rotation axis when tilting is the direction of the Y axis in FIG. In addition, when the refractive index of the optical axis adjusting plates T and J is higher than the refractive index of air, the optical axis adjusting plate T and the optical axis adjusting plate J are mutually connected as shown in FIG. The direction in the sample solution S is directed to the focal position.
[0014]
When changing the inclination angle α1, any variable method may be used. For example, as shown in FIG. 3, the optical axis adjusting plates T and J are attached so as to be rotatable about one axis, and the pulley 11 and the belt For example, the motor 13 may be rotationally driven via the motor 12.
The principle that the outgoing optical axis moves when the angle α1 formed between the optical axis adjusting plate and the incident optical axis is shifted from 0 ° will be described with reference to FIG. The refractive index of the optical axis adjusting plate is n, and the thickness is t.
[0015]
As shown in FIG. 4, the inclination angle between the normal line standing on the incident surface 21 of the optical axis adjusting plate and the incident optical axis A1 is α1. Incident light is refracted by the incident surface 21 of the optical axis adjusting plate. The refraction angle is represented by α2. The refracted light is further refracted by the exit surface 22 of the optical axis adjusting plate. The refraction angle is α1. When the positional deviation between the incident point on the incident surface 21 of the optical axis adjusting plate and the outgoing point on the outgoing surface 22 is measured perpendicularly to the optical axis, Δd is obtained. Δd is determined from geometrical optical considerations.
Δd = tsin (α1−α2) / cosα2
= T sinα1 [1-cosα1 / √ (n ² -sin ² α1)]
It is represented by Thus, the optical axis positional deviation Δd is expressed as a function of the inclination angle α1 between the optical axis adjusting plate and the incident optical axis.
[0016]
Therefore, the optical axis can be shifted by tilting the optical axis adjusting plate.
When the optical axis adjustment plate T on the light projecting axis is tilted so that the light projecting axis approaches the light receiving axis, and the optical axis adjusting plate J on the light receiving axis is tilted so that the light receiving axis approaches the light projecting axis, The distance d between the shaft and the light receiving shaft (see FIG. 1) is
d-2Δd
It becomes.
[0017]
Since the optical axis adjusting plates T and J are thus installed so that the distance d between the light projecting axis and the light receiving axis can be reduced, the light projecting lens 4 and the light receiving lens 6 are left as they are, and the scattering angle φ is 180 degrees. Can be approached.
In the embodiment of FIG. 1, the optical axis adjusting plates T and J are arranged between the light projecting lens 4 and the light collecting lens 5 on the light projecting axis, and between the light collecting lens 5 and the light receiving lens 6 on the light receiving axis. However, only the optical axis adjustment plate T or only the optical axis adjustment plate J may be installed. In this case, the distance d between the light projecting axis and the light receiving axis is
d-Δd
It becomes.
[0018]
【Example】
In the optical system shown in FIG. 1, the simulation was performed with and without the optical axis adjusting plates T and J being installed.
[0019]
[Table 1]

[0020]
An optical system A was configured by appropriately setting the parameters of the lenses 4 to 6. As shown in Table 1, the scattering angle φ, scattered beam diameter D, and overlap length L were 172.6 degrees, 12.3 μm, and 170 μm, respectively.
An optical axis adjusting plate T having a refractive index of 1.5 and a thickness of 3 mm is installed on the light projection axis at an inclination angle α1 = 30 degrees, an optical axis adjusting plate J having a refractive index of 1.5 and a thickness of 3 mm, and an inclination angle. When installed on the light receiving axis at α1 = −30 degrees, the scattering angle φ increases to 2.9 degrees to 175.5 degrees as shown in Table 1, the scattered beam diameter D does not change, and the overlap length L is 396 μm. It increased to 566μm.
[0021]
Assuming a dilute solution, the amount of scattered light is proportional to the scattering volume. Since the scattering volume is 3.3 times, the amount of scattered light is also 3.3 times.
Therefore, the scattered beam diameter D remains unchanged, the scattering angle φ can be brought close to 180 degrees, and brighter scattered light can be measured.
[0022]
[Table 2]

[0023]
The other optical system B was configured by appropriately setting the parameters of the lenses 4 to 6. As shown in Table 2, the scattering angle φ, the scattered beam diameter D, and the overlap length L were 173.9 degrees, 14.7 μm, and 240 μm, respectively.
An optical axis adjusting plate T having a refractive index of 1.5 and a thickness of 4 mm is installed on the light projection axis at an inclination angle α1 = 30 degrees, an optical axis adjusting plate J having a refractive index of 1.5 and a thickness of 4 mm, and an inclination angle. When installed on the light receiving axis at α1 = −30 degrees, the scattering angle φ increases by 3.2 degrees to 177.1 degrees as shown in Table 1, the scattered beam diameter D does not change, and the overlap length L is 4376 μm. It increased to 4619μm.
[0024]
The amount of scattered light increased 18.5 times.
Therefore, the scattered beam diameter D remains unchanged, the scattering angle φ can be brought close to 180 degrees, and brighter scattered light can be measured.
[0025]
【The invention's effect】
As described above, according to the present invention, the aperture and focal length of the light projecting lens and the light receiving lens, and the focal length of the condensing lens are not particularly changed, and the optical axis adjusting plate is installed in a state where it is tilted to the parallel light flux portion. By simply doing this, the scattering angle φ can be brought close to 180 degrees. As a result, the overlap length of light projection and reception can be increased, and the amount of scattered light can be increased. Therefore, it is possible to obtain an excellent effect that the scattered light can be accurately measured from a dilute solution having a small amount of scattered light to a concentrated solution having a large amount of scattered light.
[Brief description of the drawings]
FIG. 1A is a plan view showing a scattered light measurement apparatus according to an embodiment of the present invention, and FIG.
FIG. 2 is an explanatory diagram showing an overlap length L, a scattered beam diameter D, and a scattering angle φ of a scattering portion in a sample solution S.
FIG. 3 is a perspective view illustrating a method of rotating an optical axis adjustment plate.
FIG. 4 is an optical path diagram for explaining the principle of moving the optical axis by tilting the optical axis adjusting plate.
[Explanation of symbols]
2 Light source 3 Aperture 4 Projection lens 5 Condensing lens 6 Aperture lens 7 Aperture 8 Light receiver 9 Light transmission window 11 Pulley 12 Belt 13 Motor 21 Entrance surface 22 Exit surface D Scattered beam diameter L Overlapping length S Sample solution T, J Light Axis adjusting plate φ Scattering angle

Claims

光源と、試料溶液を収容する容器と、光源の光を平行光束にする投光レンズと、当該平行光束を集めて試料溶液に照射する集光レンズと、同じ集光レンズで集められた試料溶液からの散乱光を受光器に入射させる受光レンズと、受光器とを備える散乱光測定装置において、
両面が平行平面状の光軸調整板を、投光レンズと集光レンズとの間の投光軸上、又は受光レンズと集光レンズとの間の受光軸上の平行光束の部分に傾けて設置したことを特徴とする散乱光測定装置。Sample solution collected by the same condenser lens, a light source, a container for storing the sample solution, a light projecting lens that converts the light from the light source into a parallel luminous flux, a condenser lens that collects the parallel luminous flux and irradiates the sample solution In a scattered light measurement device comprising a light receiving lens that makes light scattered from the light incident on the light receiver, and a light receiver,
Tilt the optical axis adjustment plate with both parallel planes on the light projecting axis between the light projecting lens and the condensing lens or on the part of the parallel light beam on the light receiving axis between the light receiving lens and the condensing lens. A scattered light measuring device characterized by being installed.

前記光軸調整板を投光軸上及び受光軸上にそれぞれ設置している請求項１記載の散乱光測定装置。The scattered light measuring apparatus according to claim 1, wherein the optical axis adjusting plate is installed on a light projecting axis and a light receiving axis.