JP3151036B2 - Method and apparatus for detecting submicron particles - Google Patents
Method and apparatus for detecting submicron particlesInfo
- Publication number
- JP3151036B2 JP3151036B2 JP05641892A JP5641892A JP3151036B2 JP 3151036 B2 JP3151036 B2 JP 3151036B2 JP 05641892 A JP05641892 A JP 05641892A JP 5641892 A JP5641892 A JP 5641892A JP 3151036 B2 JP3151036 B2 JP 3151036B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- fluid
- fine particles
- particles
- light beam
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000002245 particle Substances 0.000 title claims description 43
- 238000000034 method Methods 0.000 title claims description 19
- 239000010419 fine particle Substances 0.000 claims description 48
- 230000003287 optical effect Effects 0.000 claims description 26
- 239000012530 fluid Substances 0.000 claims description 25
- 238000001514 detection method Methods 0.000 claims description 24
- 230000001427 coherent effect Effects 0.000 claims description 14
- 239000004065 semiconductor Substances 0.000 claims description 5
- 238000011088 calibration curve Methods 0.000 claims 1
- 230000000694 effects Effects 0.000 claims 1
- 239000007788 liquid Substances 0.000 description 12
- 238000012360 testing method Methods 0.000 description 9
- 238000010586 diagram Methods 0.000 description 6
- 238000011161 development Methods 0.000 description 5
- 238000000790 scattering method Methods 0.000 description 5
- 238000007689 inspection Methods 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 230000035945 sensitivity Effects 0.000 description 4
- 230000000903 blocking effect Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 230000001678 irradiating effect Effects 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 238000000149 argon plasma sintering Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910021642 ultra pure water Inorganic materials 0.000 description 2
- 239000012498 ultrapure water Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000011859 microparticle Substances 0.000 description 1
- 239000012085 test solution Substances 0.000 description 1
Description
【０００１】[0001]
【産業上の利用分野】本発明は、公知の検出原理とは全
く異なる原理で流体中の微粒子を検出する方法と、この
方法を実施するための装置に関するものであり、特に純
水および超純水中に不溶解物として存在する不純物微粒
子を極めて容易に且つ高感度で検出する方法と装置に関
するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting fine particles in a fluid based on a principle completely different from the known detection principle, and an apparatus for performing the method. The present invention relates to a method and an apparatus for extremely easily and highly sensitively detecting impurity fine particles existing as insoluble substances in water.
【０００２】[0002]
【従来の技術】流体中の微粒子の検出方法として一般に
用いられている従来の方法は基本的に以下の原理に基づ
いている： (1) 光源として連続な平行光線を使用し、この平行光線
の光軸上を通過した微粒子の影によって透過光が減光さ
れる現象を利用した光遮断方式 (2) メンブレンフィルタを用いて被検液を濾過し、メン
ブレンフィルタ上に捕捉された微粒子を走査型電子顕微
鏡で観測する方式 (3) レーザービームなどの集束光を被検液に照射し、被
検液中の微粒子に当たって生ずる散乱光を集光レンズで
集光し、集光した光を光電子増倍管（フォトマル）等を
用いて電気信号に変換して検出する散乱方式 (4) 被検液に光を照射して被検液中に存在する微粒子に
よって生じる画像をスクリーン上に配置したフォトトラ
ンジスタアレイで検出し、検出信号をコンピュータ処理
する画像形成法。 上記の方式の他に超音波散乱法等の検査／測定方法も提
案されている。2. Description of the Related Art A conventional method generally used for detecting fine particles in a fluid is basically based on the following principle: (1) A continuous parallel light beam is used as a light source, and Light blocking method utilizing the phenomenon that transmitted light is dimmed by the shadow of fine particles passing on the optical axis. (2) The test liquid is filtered using a membrane filter, and the fine particles captured on the membrane filter are scanned. Observation by electron microscope (3) Irradiate the test liquid with a focused light such as a laser beam, collect the scattered light that hits the fine particles in the test liquid with a condenser lens, and photomultiplied the collected light. Scattering method that converts the signal into an electrical signal using a tube (photomultiplier) and detects it. (4) A phototransistor that irradiates the test liquid with light and arranges an image generated by fine particles present in the test liquid on the screen. Detected by the array, The image forming method of computer processing a signal output. In addition to the above methods, inspection / measurement methods such as an ultrasonic scattering method have been proposed.
【０００３】光遮断方式(1) を用いた微粒子検出方法の
検出限界は１μｍといわれており、サブミクロンの微粒
子を光遮断方式で検出することはできない。また、走査
型電子顕微鏡で観測する方法(2) は簡便な方法ではある
が、検査に半日以上かかり、現場で簡単に使うことがで
きないという大きな問題がある。散乱方式(3) は波長の
短いアルゴンレーザー等を用いることによって、現在で
は0.07μｍまでの微粒子を検出することができるように
なっている。従って、現在の微粒子検査・測定装置の開
発の主流はこの散乱方式の改良に向かっている。特開平
３-39635号公報には、散乱光を２つの受光器で受け、両
者の受光器で同時に受けた散乱光のみをカウントするこ
とによって、超純水、超々純水中に含まれる粒径が0.07
μｍ以下の微粒子の微粒子の個数と粒度分布を正確に測
定できると記載されている。しかし、この散乱方式では
出力の大きな大型のレーザーが必要であり、しかも、光
電子増倍管のような高感度な光検出器を必要とするた
め、検出システムが大型且つ高価なものとなる。また、
この散乱方式の微粒子検査・測定装置では微粒子を含む
流体の流れの軸線と光軸とを正確にアラインメントさせ
る必要がある。しかし、このアラインメント操作は目測
で行われるため、測定を再現性良く正確に行うには慎重
な調整が必要になる。特開昭62-803号公報にはこのアラ
インメントを自動化する装置が記載されている。The detection limit of the fine particle detection method using the light blocking method (1) is said to be 1 μm, and submicron particles cannot be detected by the light blocking method. The method of observation with a scanning electron microscope (2) is a simple method, but has a major problem that the inspection takes more than half a day and cannot be easily used on site. In the scattering method (3), by using an argon laser or the like having a short wavelength, it is now possible to detect fine particles up to 0.07 μm. Therefore, the mainstream of the development of the present fine particle inspection / measurement apparatus is toward improvement of the scattering method. Japanese Patent Application Laid-Open No. 3-39635 discloses that the scattered light is received by two light receivers and only the scattered light received by both light receivers at the same time is counted. Is 0.07
It is described that the number and the particle size distribution of the fine particles having a size of not more than μm can be accurately measured. However, this scattering method requires a large-sized laser having a large output and a high-sensitivity photodetector such as a photomultiplier tube, so that the detection system becomes large and expensive. Also,
In this scattering type particle inspection / measurement apparatus, it is necessary to accurately align the axis of the flow of the fluid containing the particles with the optical axis. However, since this alignment operation is performed by eye measurement, careful adjustment is required to perform the measurement with good reproducibility and accuracy. JP-A-62-803 describes an apparatus for automating this alignment.
【０００４】画像形成法(4) の一例は特開昭63-19535号
公報に記載されている。この特許では、試料液の流れに
対して垂直にレーザ光を照射したときに試料液中の微粒
子によって生じる回折・散乱光をフーリエ変換光学系、
具体的にはレンズでフーリエ変換し、得られたフラウン
ホーファー(Fraunhofer)回折像を検出することによって
液中の微粒子の評価装置が記載されている。この特許で
はレーザ光の径を拡大して太い平行光線とした後に試料
液の流れに照射し、得られた回折・散乱光をフーリエ変
換している。An example of the image forming method (4) is described in JP-A-63-19535. In this patent, a Fourier transform optical system converts diffraction and scattered light generated by fine particles in a sample liquid when laser light is irradiated perpendicularly to the flow of the sample liquid,
Specifically, there is described an apparatus for evaluating fine particles in a liquid by performing a Fourier transform with a lens and detecting an obtained Fraunhofer diffraction image. In this patent, the diameter of a laser beam is enlarged to form a thick parallel light beam, and then irradiated onto the flow of the sample liquid, and the obtained diffracted / scattered light is subjected to Fourier transform.
【０００５】[0005]
【発明が解決しようとする課題】本発明の目的は、流
体、特に純水、超純水中に不溶解物として存在するサブ
ミクロンの不純物微粒子を安価な装置で極めて容易且つ
高精度に検出する方法を提供することにある。本発明の
検出原理は公知の検出原理とは全く異なる原理に基づく
が、この検出原理の理論的解明は現在のところ完全には
できない。SUMMARY OF THE INVENTION An object of the present invention is to detect submicron impurity fine particles present as an insoluble substance in a fluid, in particular, pure water or ultrapure water, very easily and with high accuracy using an inexpensive apparatus. It is to provide a method. Although the detection principle of the present invention is based on a completely different principle from known detection principles, a theoretical elucidation of this detection principle cannot be completely completed at present.
【０００６】[0006]
【課題を解決するための手段】本発明は、コヒーレント
光源からの光ビームを集光し、微粒子を含む流体の流れ
を集束された光ビームの焦点の近くを通過させ、流体中
の微粒子によって回折された回折光を微粒子を含む流体
の流れに対して光ビームの光源とは反対側の光ビームの
光路上に配置した光検出器によって検出して電気信号に
変換し、この電気信号から流体中の微粒子の個数を計測
することを特徴とするサブミクロン粒子の検出方法を提
供する。本発明は、さらに、上記検出方法を実施する装
置を提供する。本発明の検出装置はコヒーレント光源
と、このコヒーレント光源からの光を集光する光学系
と、この光学系で集光された光ビームの焦点の近傍に配
置され且つ内部を微粒子を含む流体の流れが通過するセ
ルと、光ビームの光路上で且つセルに対して光ビームの
光源とは反対側に配置された光検出器と、この光検出器
からの電気信号から流体中の微粒子の個数を計測する電
気回路とによって構成することができる。コヒーレント
光源からの光ビームの集光はレンズで行うことができ
る。セルはガラス等に任意の材料で作ることができる
が、光ビーが通過する部分は透明でなければならない。
コヒーレント光源としては半導体レーザを用いることが
でき、光検出器はフォトダイオードにすることができ
る。SUMMARY OF THE INVENTION The present invention condenses a light beam from a coherent light source, passes a flow of fluid containing particulates near the focal point of the focused light beam, and diffracts the fluid by particulates in the fluid. The diffracted light is detected by a photodetector arranged on the optical path of the light beam opposite to the light source of the light beam with respect to the flow of the fluid containing the fine particles, and is converted into an electric signal. And a method for detecting submicron particles, characterized by measuring the number of fine particles. The present invention further provides an apparatus for performing the above detection method. The detection device according to the present invention includes a coherent light source, an optical system for condensing light from the coherent light source, and a flow of a fluid that is disposed near a focal point of the light beam condensed by the optical system and contains particles inside. , A photodetector disposed on the optical path of the light beam and on the opposite side of the cell from the light source of the light beam, and determining the number of fine particles in the fluid from the electric signal from the photodetector. It can be constituted by an electric circuit to be measured. The light beam from the coherent light source can be focused by a lens. The cell can be made of any material, such as glass, but the area through which the light beam passes must be transparent.
A semiconductor laser can be used as the coherent light source, and the photodetector can be a photodiode.
【０００７】[0007]
【作用】本発明は、コヒーレント光を集束し、集束光を
流体中のサブミクロン粒子に照射することによって起き
る透過光の回折現像を利用することによって、流体中の
サブミクロンの微粒子を検出することができるという驚
くべき発見に基づいている。すなわち、流体中のサブミ
クロン粒子に平行光線の照明光を照射し、透過光をフー
リエ変換して画像処理するという思想は上記特開昭63-1
9535号公報等に記載されているように知られていたが、
集束光を照射し、透過光のそのまま用いることによって
微粒子が検出できるという事実は全く知られていなかっ
た。According to the present invention, submicron particles in a fluid are detected by focusing coherent light and utilizing diffraction development of transmitted light caused by irradiating the focused light to the submicron particles in the fluid. Is based on the surprising discovery that you can do it. That is, the idea of irradiating submicron particles in a fluid with parallel rays of illumination light and performing image processing by performing Fourier transform on the transmitted light is described in the above-mentioned JP-A-63-1.
It was known as described in 9535 publication, etc.,
The fact that the microparticles can be detected by irradiating the focused light and using the transmitted light as it was was not known at all.
【０００８】既に述べたように、本発明の検出原理は理
論的には完全には説明できないが、現在のところ、以下
のように説明されている：すなわち、平行ビーム中の微
粒子は、図２に示すように、フラウンホーファー回折現
像を示す。このフラウンホーファー回折現像は粒度分布
計などでよく用いられる物理現象である。この「回折」
は「光の直進性によって説明できない諸現象の総称」と
定義される現象で、光を波として考えたホイヘンスーフ
レネルの原理によって説明される。しかし、フラウンホ
ーファー回折現象は微粒子の半径が光の波長より大きい
ときにしか現れず、微粒子の半径が光の波長以下のとき
は散乱として扱われる。これは、微粒子の半径が光の波
長程度になると、あたかも微粒子が点光源になって散乱
を起こしているかのようになって、回折角が大きくな
り、平行ビームでは干渉を起こし得なくなるためであ
る。[0008] As already mentioned, the detection principle of the present invention cannot be completely explained in theory, but at present it is explained as follows: As shown in the figure, Fraunhofer diffraction development is shown. The Fraunhofer diffraction development is a physical phenomenon often used in a particle size distribution meter or the like. This "diffraction"
Is a phenomenon defined as "a general term for phenomena that cannot be explained by the straightness of light", and is explained by Huygens-Fresnel's principle, which considered light as waves. However, the Fraunhofer diffraction phenomenon appears only when the radius of the particle is larger than the wavelength of light, and when the radius of the particle is smaller than the wavelength of light, it is treated as scattering. This is because, when the radius of the fine particles is about the wavelength of light, it is as if the fine particles are scattered as a point light source, the diffraction angle increases, and no interference can occur with a parallel beam. .
【０００９】より理論的にいうと、回折現象も光散乱の
一つであると考えられており、この光散乱は一般にはマ
クスウェルの電磁方程式から厳密に解かれたミー(Mie)
散乱理論で説明さる。しかし、ミー散乱理論は取扱が複
雑なため一般には粒子半径ｒと入射波長λとの関係か
ら、近似が用いられている (ｒ＜λの場合にはレイリー
(Rayleigh)散乱、ｒがλに近い場合にはミー散乱、ｒ＞
λの場合にはフラウンホーファー散乱) 。従来の平行光
によるフラウンホーファー回折理論では、遮光体が微粒
子のときの回折による広がり角Δθは、微粒子の直径Ｄ
＝２ｒとすると、Δθ＝1.22λ／Ｄで表される。従っ
て、遮光する微粒子の直径が小さくなればなる程、回折
の広がり角Δθが大きくなり、Ｄ＝0.78λのときに広が
り角がちょうど90度になる。通常は、この広がり角が回
折方式の微粒子検出装置での検出限界と考えられるの
で、入射波長λ＝0.67μｍとすると検出可能な粒径は0.
52μｍということになる。事実、実験的にも波長以下の
粒径の回折像は容易には得られない。More theoretically, the diffraction phenomenon is considered to be one of light scattering, and this light scattering is generally strictly solved from Maxwell's electromagnetic equation by Mie.
Explained in scattering theory. However, since the Mie scattering theory is complicated to handle, an approximation is generally used based on the relationship between the particle radius r and the incident wavelength λ (when r <λ, Rayleigh is used).
(Rayleigh) scattering, Mie scattering when r is close to λ, r>
In the case of λ, Fraunhofer scattering). In the conventional Fraunhofer diffraction theory using parallel light, the spread angle Δθ due to diffraction when the light shielding body is a fine particle is determined by the diameter D of the fine particle.
= 2r, Δθ = 1.22λ / D. Therefore, the smaller the diameter of the light-shielding fine particles, the larger the divergence angle Δθ of diffraction becomes, and when D = 0.78λ, the divergence angle becomes just 90 degrees. Normally, this divergence angle is considered to be the detection limit in a diffraction type particle detector, so that if the incident wavelength λ is 0.67 μm, the detectable particle size is 0.
It means 52 μm. In fact, a diffraction image having a particle size smaller than the wavelength cannot be easily obtained experimentally.
【００１０】驚くことに、本発明者達は、集光レンズで
集束した集束光ビームの焦点近くに微粒子を置くと、粒
径が光の波長より小さい微粒子でも回折角が十分に小さ
くなり、容易に検出できるということを見い出した。こ
の発見に基づくと、今までにはない全く新しい方法でサ
ブミクロン粒子を簡単に検出することが可能になる。本
発明の検出方法は出力が小さな安価なレーザー（光源）
と安価なフォトダイオード（検出器）との組合せで、高
感度かつ高精度にサブミクロン粒子を現場で簡単に検出
できるという工業上極めて重要な利点がある。本発明の
検出原理を用いると、従来は困難であった粒径が 0.1μ
ｍの粒子でも回折像を得ることができる。本発明方法
は、当然ながら、粒径が 0.1μｍ以上の微粒子の場合に
も優れた感度で微粒子を検出することができる。Surprisingly, the present inventors have found that when a particle is placed near the focal point of a focused light beam focused by a condenser lens, even if the particle has a particle diameter smaller than the wavelength of light, the diffraction angle becomes sufficiently small, and the diffraction angle becomes small. It was found that it could be detected. Based on this discovery, submicron particles can be easily detected in an entirely new way. The detection method of the present invention is an inexpensive laser (light source) having a small output.
In combination with a low-cost photodiode (detector), there is an extremely important industrial advantage that submicron particles can be easily detected on site with high sensitivity and high accuracy. Using the detection principle of the present invention, the particle size was
Even with particles of m, a diffraction image can be obtained. The method of the present invention can naturally detect fine particles with excellent sensitivity even in the case of fine particles having a particle size of 0.1 μm or more.
【００１１】以下、本発明を添付の図面を用いて説明す
る。図１は本発明の原理を用いた微粒子検出装置の概念
図である。この微粒子検出装置は、コヒーレント光源と
なるレーザー(1) と、コヒーレント光から集束光を作る
ための集光系、好ましくは光学レンズ(2) と、この集光
レンズの焦点近傍に配置された微粒子を含む流体が通る
光学セル(3) と、この光学セルに対して集光レンズ(2)
とは反対側の光路上に配置された光検出器、例えばフォ
トダイオードまたはフォトダイオードアレイ(4) と、こ
の光検出器で検出された光強度信号または回折像を電気
信号に変換するための電気回路（図示せず）とによって
構成することができる。これらの構成要素は市場から極
めて安価に入手し得るものである。Hereinafter, the present invention will be described with reference to the accompanying drawings. FIG. 1 is a conceptual diagram of a particle detection device using the principle of the present invention. This particle detection device includes a laser (1) serving as a coherent light source, a light-collecting system for producing focused light from the coherent light, preferably an optical lens (2), and particles disposed near the focal point of the light-collecting lens. Optical cell (3) through which a fluid containing
A photodetector, for example, a photodiode or a photodiode array (4) disposed on the optical path opposite to the optical path, and an electric signal for converting a light intensity signal or a diffraction image detected by the photodetector into an electric signal. And a circuit (not shown). These components are available at very low cost from the market.
【００１２】コヒーレント光源はレーザ発振器(1) とコ
リメータレンズ（図３参照）とで構成することができ
る。レーザー発振器(1) としては任意のものを用いるこ
とができるが、発振波長が短ければ短いほど検出感度は
向上する。本発明の検出方法の特徴は発振出力の小さい
レーザー発振器、例えば半導体レーザーを用いることが
できる点にある。本発明者達が行った現在までの実験で
は出力が１ｍＷ以下、具体的には 0.2ｍＷの半導体レー
ザーでも本発明の検出原理を用いることができるという
ことを確認している。集光系と光学レンズ(2) の焦点距
離は検出したい微粒子の大きさによって選択する。例え
ば粒径が 0.2μｍの微粒子を検出する場合にはｆ＝10mm
の焦点距離のレンズを用いることができる。光学セル
(3) は、少なくとも集束光の受光面および透過面を透明
にする必要がある。この光学セルは迷光を心配する必要
がないので、単純な構造にすることができるが、微粒子
を含んだ被検流体の流れに乱流が発生しないようにする
手段、例えば層流板を光学セル内に設けておくのが好ま
しい。また、実際の装置では、レーザー(1) から出て集
束された集束光が光学セル(3) の所定の位置、例えば光
学セルの中心に集光されるように光学レンズ(2) を配置
するための位置調節手段を設けるのが好ましい。光検出
器(4) の役目は透過光に隠れている回折像を検出するこ
とにあるので、感度はそれほど必要としない。原理的に
は単一のフォトダイオードを用いることができるが、フ
ォトダイオードアレイを用いるのが好ましい。このフォ
トダイオードアレイは被検出粒子を含む流れの方向に対
しては垂直に配置し且つ光軸に対しても垂直に配置する
のが好ましい。The coherent light source can be composed of a laser oscillator (1) and a collimator lens (see FIG. 3). Any type of laser oscillator (1) can be used, but the shorter the oscillation wavelength, the higher the detection sensitivity. A feature of the detection method of the present invention is that a laser oscillator having a small oscillation output, for example, a semiconductor laser can be used. Experiments conducted by the present inventors to date have confirmed that the detection principle of the present invention can be used even with a semiconductor laser having an output of 1 mW or less, specifically, 0.2 mW. The focal length of the focusing system and the optical lens (2) is selected according to the size of the fine particles to be detected. For example, when detecting fine particles having a particle size of 0.2 μm, f = 10 mm
Can be used. Optical cell
In (3), at least the light receiving surface and the transmitting surface of the focused light need to be transparent. Since this optical cell does not need to worry about stray light, it can have a simple structure.However, a means for preventing turbulence in the flow of the test fluid containing fine particles, such as a laminar flow plate, is used as the optical cell. It is preferable to provide it inside. In an actual device, the optical lens (2) is arranged so that the focused light emitted from the laser (1) is focused at a predetermined position of the optical cell (3), for example, at the center of the optical cell. Is preferably provided. Since the role of the photodetector (4) is to detect a diffraction image hidden by transmitted light, less sensitivity is required. Although a single photodiode can be used in principle, a photodiode array is preferably used. This photodiode array is preferably arranged perpendicular to the direction of the flow containing the particles to be detected and also perpendicular to the optical axis.
【００１３】図３の右側には本発明の原理を用いた微粒
子検出装置の光検出器で得られる集束光回折像（光強度
分布）が概念的に示してある。実際の装置では、光検出
器(4) のＳＮ比を良くするために、フォトダイオードア
レイの各素子の信号を差動増幅器を用いて多段に重ね合
わせて、微粒子が通過しない時、すなわち、フォトダイ
オードアレイの各素子に光が一様に当たっている状態で
の電気信号を０とし、集束光回折回折像によっていずれ
かの素子に光量の変化が現われた時に、粒子の特性
（数、寸法等）に応じた電気信号が発生するようにする
のが好ましい。図４は４つの素子を有するフォトダイオ
ードアレイを用いた光検出器の場合の信号処理回路の一
例を示している。フォトダイオードアレイの各素子から
の出力信号ａ〜ｄを図４に示す差動増幅器回路に接続す
る。この差動増幅器回路の各抵抗は、４つの素子から全
く同じ出力信号が出ている状態、つまり一様な光が各素
子に当たっている時に差動増幅器回路の出力信号ｅが０
となるように設定しておく。従って、いずれか一つの素
子の光量のみが変化した時、例えば、ａの出力信号が変
化した時に差動増幅器回路の出力信号ｅは変化する。The right side of FIG. 3 conceptually shows a focused light diffraction image (light intensity distribution) obtained by a photodetector of a fine particle detecting apparatus using the principle of the present invention. In an actual device, in order to improve the S / N ratio of the photodetector (4), the signals of the respective elements of the photodiode array are superposed in multiple stages using a differential amplifier, and when the fine particles do not pass through, When the electric signal in a state where light is uniformly applied to each element of the diode array is set to 0 and a change in the amount of light appears in any of the elements by the focused light diffraction image, the characteristics (number, size, etc.) of the particles are changed. Preferably, a corresponding electrical signal is generated. FIG. 4 shows an example of a signal processing circuit in the case of a photodetector using a photodiode array having four elements. Output signals a to d from the respective elements of the photodiode array are connected to the differential amplifier circuit shown in FIG. Each resistor of the differential amplifier circuit is in a state where exactly the same output signal is output from the four elements, that is, the output signal e of the differential amplifier circuit becomes 0 when uniform light is applied to each element.
It is set so that Therefore, when only the light quantity of any one element changes, for example, when the output signal of a changes, the output signal e of the differential amplifier circuit changes.
【００１４】[0014]
【実施例】以下、本発明の原理を用いて実際に微粒子を
検出した実施例を説明する。実施例１ 図１に示す原理を用い、下記実験条件と実験操作で微粒
子を検出した。 (実験条件) レーザー ： 半導体レーザー（波長 670n
m、出力 0.5ｍＷ） 集光レンズの焦点距離： 10 mm 被検液 ： 超純水 被検液の流速 ： 100 mm／秒 被検液に混入させた微粒子の直径： 0.208μｍ 光検出器 ： フォトダイオードアレイ（32
素子） 信号処理回路 ： 図４に示す差動増幅器回路の
組合せ (実験操作)上記条件で、微粒子の濃度を１倍〜３倍まで
変えた場合の検出個数の変化を図５に示す。この実験か
ら、本発明方法で 0.208μｍの微粒子が検出できること
が実証された。実施例２ 実施例１の実験条件を繰り返したが、被検液に混入させ
る微粒子の直径を 0.1μｍにした。実施例１と同じ操作
を行った場合の結果を図６に示す。この実験から、本発
明方法では 0.1μｍの微粒子も検出できることが実証さ
れた。An embodiment in which fine particles are actually detected using the principle of the present invention will be described below. Example 1 Using the principle shown in FIG. 1, fine particles were detected under the following experimental conditions and experimental operations. (Experimental conditions) Laser: Semiconductor laser (wavelength 670n
m, output 0.5mW) Condensing lens focal length: 10mm Test liquid: ultrapure water Test liquid flow rate: 100mm / sec Diameter of fine particles mixed into test liquid: 0.208μm Photodetector: photo Diode array (32
Element) Signal processing circuit: Combination of differential amplifier circuits shown in FIG. 4 (Experimental operation) FIG. 5 shows a change in the number of detected particles when the concentration of fine particles is changed from 1 to 3 times under the above conditions. This experiment demonstrated that the method of the present invention can detect fine particles of 0.208 μm. Example 2 The experimental conditions of Example 1 were repeated, except that the diameter of the fine particles mixed into the test solution was 0.1 μm. FIG. 6 shows the result when the same operation as in Example 1 was performed. This experiment demonstrated that the method of the present invention can detect fine particles of 0.1 μm.
【図１】 本発明の原理を用いた微粒子検出装置の概念
図。FIG. 1 is a conceptual diagram of a particle detection device using the principle of the present invention.
【図２】 平行ビーム中に微粒子が存在する場合のフラ
ウンホーファー回折現像を示す図。FIG. 2 is a diagram showing Fraunhofer diffraction development when fine particles are present in a parallel beam.
【図３】 本発明の原理を用いた微粒子検出装置と、そ
の光検出器で得られる集束光回折像（光強度分布）を示
す概念図。FIG. 3 is a conceptual diagram showing a fine particle detection device using the principle of the present invention and a focused light diffraction image (light intensity distribution) obtained by the photodetector.
【図４】 本発明の微粒子検出装置で用いることができ
る差動増幅器の一例を示す回路図。FIG. 4 is a circuit diagram showing an example of a differential amplifier that can be used in the particle detection device of the present invention.
【図５】 本発明の微粒子検出方法を用いた実施例１で
得られた微粒子濃度と検出個数との関係を示す図。FIG. 5 is a graph showing the relationship between the concentration of fine particles and the number of detected particles obtained in Example 1 using the method for detecting fine particles of the present invention.
【図６】 本発明の微粒子検出方法を用いた実施例２で
得られた微粒子濃度と検出個数との関係を示す図。FIG. 6 is a diagram showing the relationship between the concentration of fine particles and the number of detected particles obtained in Example 2 using the fine particle detection method of the present invention.
１ レーザー ２ レンズ ３ 光学セル ４ 光検出器 DESCRIPTION OF SYMBOLS 1 Laser 2 Lens 3 Optical cell 4 Photodetector
フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) G01N 15/00 G01N 15/02 G01N 15/06 G01N 15/14 Continuation of the front page (58) Field surveyed (Int.Cl. 7 , DB name) G01N 15/00 G01N 15/02 G01N 15/06 G01N 15/14
Claims (4)
し、微粒子を含む流体の流れの中で焦点を結ばせ、流体
中で微粒子が光ビーム内で焦点近くを通過する時に強い
回折作用を持つ収束されたコヒーレント光を受けた結果
として光ビーム内に発生する回折光の変化を微粒子を含
む流体の流れに対して光源とは反対側の光ビームの光路
上に配置した光検出器によって、光軸上に遮光板を置か
ずに、直接検出して電気信号に変換し、この電気信号か
ら流体中の微粒子の個数を計測することを特徴とするサ
ブミクロン粒子の検出方法。1. A light beam from a coherent light source is condensed and focused in a flow of a fluid containing fine particles, and has a strong diffraction effect when the fine particles pass close to the focal point in the light beam in the fluid. The change in the diffracted light generated in the light beam as a result of receiving the converged coherent light is detected by a photodetector arranged on the optical path of the light beam on the opposite side to the light source with respect to the flow of the fluid containing fine particles. Place the light shield on the axis
A method for detecting submicron particles, wherein the submicron particles are directly detected and converted into an electric signal, and the number of fine particles in the fluid is measured from the electric signal.
光源からの光を集光する光学系と、この光学系で集光さ
れた光ビームの焦点が内部にあるように配置され且つそ
の内部を微粒子を含む流体の流れが通過するセルと、光
ビームの光路上で且つセルに対してコヒーレント光源と
は反対側に配置された、流体中の微粒子が光ビーム内で
焦点近くを通過する時に発生する回折光を検出し、電気
信号に変換する光検出器と、この光検出器からの電気信
号から上記セルにおける流体中の微粒子の個数を計測
し、予め作成しておいた上記計測個数と流体中の微粒子
の個数との関係を表す較正曲線を用いて流体中の微粒子
の個数を算出する演算電子回路と、算出した流体中の微
粒子の個数を表示する電気回路とによって構成され、光
軸上には遮光板は置かないことを特徴とするサブミクロ
ン粒子の検出装置。2. A coherent light source, an optical system for condensing light from the coherent light source, and a light beam condensed by the optical system are arranged so that the focal point is inside, and the inside includes fine particles. A cell through which the flow of fluid passes, and diffracted light generated when particles in the fluid pass near the focal point in the light beam, which are arranged on the optical path of the light beam and opposite to the cell with respect to the coherent light source. And a photodetector that detects and converts the number of fine particles in the fluid in the cell from the electric signal from the photodetector. An arithmetic circuit for calculating the number of particles in the fluid using a calibration curve representing the relationship with the number of particles, and an electric circuit for displaying the calculated number of particles in the fluid ,
A submicron particle detection device characterized in that no light-shielding plate is placed on the axis .
光学系がレンズであり、光検出器がフォトダイオードま
たはフォトダイオードアレイである請求項２に記載の検
出装置。3. A light source of a light beam is a semiconductor laser,
The detection device according to claim 2, wherein the optical system is a lens, and the photodetector is a photodiode or a photodiode array.
流体の流れ方向に対して垂直に且つ光軸に対して対を成
す位置に配置されたフォトダイオードアレイであり、こ
のフォトダイオードアレイの各素子の信号を多段に重ね
合わせる差動増幅器をさらに含む請求項３に記載の装
置。4. A photodiode array in which photodiodes constituting a photodetector are arranged in a position perpendicular to the flow direction of a fluid and in a pair with an optical axis, and each element of the photodiode array. 4. The apparatus according to claim 3, further comprising a differential amplifier that superimposes the signals in multiple stages.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP05641892A JP3151036B2 (en) | 1992-02-06 | 1992-02-06 | Method and apparatus for detecting submicron particles |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP05641892A JP3151036B2 (en) | 1992-02-06 | 1992-02-06 | Method and apparatus for detecting submicron particles |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05215664A JPH05215664A (en) | 1993-08-24 |
| JP3151036B2 true JP3151036B2 (en) | 2001-04-03 |
Family
ID=13026566
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP05641892A Expired - Fee Related JP3151036B2 (en) | 1992-02-06 | 1992-02-06 | Method and apparatus for detecting submicron particles |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3151036B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002031594A (en) * | 2000-05-12 | 2002-01-31 | Rion Co Ltd | Light scattering type particle detector |
| JP2009008602A (en) * | 2007-06-29 | 2009-01-15 | Hokuto Denshi Kogyo Kk | Detecting method and device for size of particle in liquid |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08117506A (en) | 1994-10-27 | 1996-05-14 | Mikuni Kikai Kk | Gas-liquid separating apparatus and fine particle monitor provided therewith |
| JP3393817B2 (en) * | 1998-10-16 | 2003-04-07 | 株式会社堀場製作所 | Particle size distribution measuring device |
| JP4445569B2 (en) | 2006-10-19 | 2010-04-07 | 平田機工株式会社 | Filtrated water monitoring device and filtered water monitoring system |
| JP5366726B2 (en) * | 2009-09-14 | 2013-12-11 | 北斗電子工業株式会社 | Method and apparatus for detecting the size of particles in a liquid |
| KR102578808B1 (en) * | 2016-01-21 | 2023-09-15 | 도쿄엘렉트론가부시키가이샤 | Foreign matter detection device and foreign matter detection method |
| TW202200988A (en) | 2020-03-09 | 2022-01-01 | 日商東京威力科創股份有限公司 | Foreign matter detection device, substrate processing device, foreign matter detection method, and storage medium |
| KR20220159403A (en) | 2020-03-27 | 2022-12-02 | 도쿄엘렉트론가부시키가이샤 | Method for confirming operation of foreign material detection device, substrate processing device, and foreign material detection device |
-
1992
- 1992-02-06 JP JP05641892A patent/JP3151036B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002031594A (en) * | 2000-05-12 | 2002-01-31 | Rion Co Ltd | Light scattering type particle detector |
| JP2009008602A (en) * | 2007-06-29 | 2009-01-15 | Hokuto Denshi Kogyo Kk | Detecting method and device for size of particle in liquid |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05215664A (en) | 1993-08-24 |
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