JPH05215664A - Method and device for detecting submicron particle - Google Patents
Method and device for detecting submicron particleInfo
- Publication number
- JPH05215664A JPH05215664A JP4056418A JP5641892A JPH05215664A JP H05215664 A JPH05215664 A JP H05215664A JP 4056418 A JP4056418 A JP 4056418A JP 5641892 A JP5641892 A JP 5641892A JP H05215664 A JPH05215664 A JP H05215664A
- Authority
- JP
- Japan
- Prior art keywords
- fine particles
- light
- fluid
- light beam
- light source
- 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.)
- Granted
Links
- 239000002245 particle Substances 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims abstract description 23
- 239000010419 fine particle Substances 0.000 claims abstract description 54
- 230000003287 optical effect Effects 0.000 claims abstract description 27
- 239000012530 fluid Substances 0.000 claims abstract description 26
- 230000001427 coherent effect Effects 0.000 claims abstract description 14
- 238000001514 detection method Methods 0.000 claims description 29
- 239000004065 semiconductor Substances 0.000 claims description 6
- 229910021642 ultra pure water Inorganic materials 0.000 abstract description 7
- 239000012498 ultrapure water Substances 0.000 abstract description 7
- 239000012535 impurity Substances 0.000 abstract description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 4
- 239000007788 liquid Substances 0.000 description 9
- 238000010586 diagram Methods 0.000 description 7
- 238000011161 development Methods 0.000 description 5
- 238000000790 scattering method Methods 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 238000007689 inspection Methods 0.000 description 4
- 230000001678 irradiating effect Effects 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
- 239000012085 test solution Substances 0.000 description 4
- 230000000903 blocking effect Effects 0.000 description 3
- 238000002474 experimental method Methods 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
- 239000012528 membrane Substances 0.000 description 2
- 230000010355 oscillation Effects 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
- 230000001131 transforming effect Effects 0.000 description 1
Landscapes
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
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 by a principle completely different from a known detection principle and an apparatus for carrying out this method, and particularly to pure water and ultrapure water. The present invention relates to a method and an apparatus for extremely easily and highly sensitively detecting fine particles of impurities existing as insoluble matter 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 The conventional method generally used for detecting fine particles in a fluid is basically based on the following principles: (1) A continuous parallel light beam is used as a light source and A light blocking method that utilizes the phenomenon that transmitted light is dimmed by the shadow of fine particles that have passed along the optical axis. (2) The test liquid is filtered using a membrane filter, and the fine particles captured on the membrane filter are scanned. Method of observing with electron microscope (3) Irradiate the test liquid with focused light such as a laser beam, collect the scattered light generated by hitting the fine particles in the test liquid with a condenser lens, and photon multiply the collected light. Scattering method that detects by converting to an electric signal using a tube (photomul) (4) Phototransistor in which an image generated by irradiating the test solution with light is generated on the screen Detected in the array, The image forming method of computer processing a signal output. In addition to the above method, an inspection / measurement method such as an ultrasonic scattering method has 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 fine particles cannot be detected by the light blocking method. Further, although the method (2) of observing with a scanning electron microscope is a simple method, there is a big problem that the inspection takes more than half a day and cannot be easily used on site. The scattering method (3) can detect fine particles up to 0.07 μm at present by using an argon laser having a short wavelength. Therefore, the mainstream of the development of the present particle inspection / measurement apparatus is toward the improvement of this scattering method. Japanese Laid-Open Patent Publication No. 3-39635 discloses that scattered light is received by two light receivers, and only scattered light received by both light receivers at the same time is counted to obtain a particle size contained in ultrapure water or ultrapure water. Is 0.07
It is described that it is possible to accurately measure the number and particle size distribution of fine particles having a size of μm or less. However, this scattering method requires a large laser with a large output and a high-sensitivity photodetector such as a photomultiplier tube, which makes the detection system 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 particles with the optical axis. However, since this alignment operation is performed by eye measurement, careful adjustment is required to make the measurement reproducibly and accurately. Japanese Unexamined Patent Publication (Kokai) No. 62-803 discloses a device 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, the Fourier transform optical system converts the diffracted / scattered light generated by the fine particles in the sample liquid when the 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 Fourier transforming with a lens and detecting the obtained Fraunhofer diffraction image. In this patent, the diameter of the laser beam is enlarged to form a thick parallel beam, which is then applied to the flow of the sample liquid, and the obtained diffracted / scattered light is Fourier-transformed.
【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 matter in a fluid, particularly pure water or ultrapure water, with an inexpensive device, very easily and highly accurately. To provide a method. The detection principle of the present invention is based on a principle completely different from the known detection principle, but the 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 focuses a light beam from a coherent light source, causes a stream of fluid containing particulates to pass near the focal point of the focused light beam, and diffracts by the particulates in the fluid. The diffracted light thus detected is detected by a photodetector placed on the optical path of the light beam on the side opposite to the light source of the light beam with respect to the flow of fluid containing fine particles and converted into an electrical signal. The present invention provides a method for detecting submicron particles, which is characterized by counting the number of fine particles. The invention further provides a device for implementing the above detection method. The detection device of the present invention includes a coherent light source, an optical system that collects light from the coherent light source, a flow of a fluid that is disposed near the focal point of the light beam that is collected by the optical system, and that contains fine particles inside. The cell through which the light passes, the photodetector placed 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 the number of fine particles in the fluid from the electric signal from this photodetector. It can be configured with an electric circuit for measuring. The light beam from the coherent light source can be collected by a lens. The cell can be made of any material such as glass, but the part through which the light bee must pass 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。The present invention detects submicron particles in a fluid by utilizing diffractive development of transmitted light which is caused by focusing coherent light and irradiating the focused light to submicron particles in the fluid. It is based on the surprising finding that That is, the idea of irradiating submicron particles in a fluid with illumination light of parallel rays and subjecting transmitted light to Fourier transform to perform image processing is described in the above-mentioned JP-A-63-1.
It was known as described in 9535 publication, etc.,
The fact that fine particles can be detected by irradiating focused light and using transmitted light as it is has not been 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。As already mentioned, the detection principle of the invention cannot be completely explained theoretically, but at present it is explained as follows: fine particles in a collimated beam are shown in FIG. Fraunhofer diffraction development as shown in FIG. This Fraunhofer diffraction development is a physical phenomenon often used in particle size distribution analyzers. This "diffraction"
Is a phenomenon that is defined as "a general term for various phenomena that cannot be explained by the straightness of light", and is explained by the Huygens-Fresnel principle in which light is considered as a wave. However, the Fraunhofer diffraction phenomenon appears only when the radius of the fine particles is larger than the wavelength of light, and is treated as scattering when the radius of the fine particles is equal to or smaller than the wavelength of light. This is because when the radius of the fine particles becomes about the wavelength of light, it becomes as if the fine particles act as a point light source to cause scattering, and the diffraction angle becomes large, so that interference cannot occur with parallel beams. ..
【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 also considered to be one of light scattering, and this light scattering is generally rigorously solved from Maxwell's electromagnetic equation.
Explain by scattering theory. However, since the Mie scattering theory is complicated to handle, an approximation is generally used from the relationship between the particle radius r and the incident wavelength λ (when r <λ, Rayleigh
(Rayleigh) scattering, Mie scattering when r is close to λ, r>
Fraunhofer scattering for λ). According to the conventional Fraunhofer diffraction theory using parallel light, the spread angle Δθ due to diffraction when the light shield is fine particles is the diameter D of the fine particles.
= 2r, Δθ = 1.22λ / D. Accordingly, the smaller the diameter of the light-shielding particles, the larger the diffraction spread angle Δθ, and when D = 0.78λ, the spread angle becomes just 90 degrees. Normally, this divergence angle is considered to be the detection limit in the diffraction type particle detector, so the particle size that can be detected is 0 when the incident wavelength is λ = 0.67 μm.
This means 52 μm. In fact, experimentally, it is not easy to obtain a diffraction pattern with a particle size smaller than the wavelength.
【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 the fine particles are placed near the focal point of the focused light beam focused by the condenser lens, the diffraction angle becomes sufficiently small even for the fine particles having a particle size smaller than the wavelength of light, which is easy to achieve. I found that it can be detected. Based on this finding, it will be possible to easily detect submicron particles with a completely new method that has never existed before. The detection method of the present invention is an inexpensive laser (light source) with a small output.
This is a very important advantage in the industry that submicron particles can be easily detected in the field with high sensitivity and high accuracy by combining with and an inexpensive photodiode (detector). When the detection principle of the present invention is used, the particle size, which was difficult in the past, was 0.1 μm.
A diffraction image can be obtained even with m particles. The method of the present invention can of course 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。The present invention will be described below 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 fine particle detection device comprises a laser (1) which is a coherent light source, a focusing system for producing focused light from coherent light, preferably an optical lens (2), and fine particles arranged near the focal point of this focusing lens. An optical cell (3) through which the fluid containing the liquid passes, and a condenser lens (2) for this optical cell
A photodetector, for example a photodiode or a photodiode array (4), which is arranged on the optical path on the side opposite to, and an electrical device for converting the light intensity signal or diffraction image detected by this photodetector into an electrical signal. And a circuit (not shown). These components are very cheaply available on 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 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. The experiments conducted by the inventors up to the present time have confirmed that the detection principle of the present invention can be applied to a semiconductor laser having an output of 1 mW or less, specifically 0.2 mW. The focal length of the condensing system and the optical lens (2) is selected according to the size of the particles to be detected. For example, when detecting fine particles with a particle size of 0.2 μm, f = 10 mm
Lenses with focal lengths of Optical cell
In (3), at least the light receiving surface and the transmitting surface for the focused light must be transparent. Since this optical cell does not need to worry about stray light, it can have a simple structure, but a means for preventing turbulence from occurring 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. Also, 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, the center of the optical cell. It is preferable to provide position adjusting means for this. Since the role of the photodetector (4) is to detect the diffracted image hidden in the transmitted light, it does not require much sensitivity. In principle, a single photodiode can be used, but it is preferable to use a photodiode array. 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。On the right side of FIG. 3, a focused light diffraction image (light intensity distribution) obtained by a photodetector of a particle detection device using the principle of the present invention is conceptually shown. In an actual device, in order to improve the SN ratio of the photodetector (4), the signals of each element of the photodiode array are superposed in multiple stages by using a differential amplifier, and when fine particles do not pass, that is, When the electric signal in the state where the light uniformly hits each element of the diode array is set to 0, and the change of the light quantity appears in any one of the elements by the focused light diffraction image, the characteristics (number, size, etc.) of the particle It is preferable to generate a corresponding electric signal. 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 this differential amplifier circuit outputs exactly the same output signal from the four elements, that is, the output signal e of the differential amplifier circuit is 0 when uniform light is applied to each element.
It is set so that Therefore, when only the light amount 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。EXAMPLES Examples in which fine particles are actually detected by 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 0.5 mW) Focal length of condensing lens: 10 mm Test solution: Ultrapure water Flow rate of test solution: 100 mm / sec Diameter of fine particles mixed in test solution: 0.208 μm Photodetector: Photo Diode array (32
Element) Signal processing circuit: Combination of the differential amplifier circuit shown in FIG. 4 (experimental operation) FIG. 5 shows changes in the number of particles detected when the concentration of the fine particles was changed from 1 to 3 times under the above conditions. From this experiment, it was demonstrated that 0.208 μm fine particles can be detected by the method of the present invention. Example 2 The experimental conditions of Example 1 were repeated, but the diameter of the fine particles mixed in the test liquid was 0.1 μm. FIG. 6 shows the result when the same operation as in Example 1 was performed. From this experiment, it was demonstrated that the method of the present invention can also 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 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 diagram showing the relationship between the concentration of fine particles and the detected number 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 detections obtained in Example 2 using the method for detecting fine particles of the present invention.
１ レーザー ２ レンズ ３ 光学セル ４ 光検出器 1 laser 2 lens 3 optical cell 4 photodetector
Claims (7)
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。1. A light beam from a coherent light source is condensed, a flow of a fluid containing fine particles is passed near the focal point of the focused light beam, and diffracted light diffracted by the fine particles in the fluid is included in the fine particles. To detect the number of fine particles in the fluid by detecting with a photodetector placed on the optical path of the light beam on the side opposite to the light source of the fluid flow and converting it to an electrical signal. And a method for detecting submicron particles.
光検出器がフォトダイオードである請求項１に記載の検
出方法。2. The light source of the light beam is a semiconductor laser,
The detection method according to claim 1, wherein the photodetector is a photodiode.
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さ
れるサブミクロン粒子の検出装置。3. A coherent light source, an optical system for condensing light from this coherent light source, a flow of a fluid which is arranged near the focal point of the light beam condensed by this optical system and which contains fine particles inside. Counts the number of particles in the fluid through the passing cell, the photodetector placed 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 a submicron particle detection device constituted by an electric circuit that operates.
検出装置。4. The detection device according to claim 3, wherein the optical system is a lens.
り、光検出器がフォトダイオードである請求項３または
４に記載の検出装置。5. The detection device according to claim 3, wherein the coherent light source is a semiconductor laser and the photodetector is a photodiode.
に対して垂直に且つ光軸に対して垂直に配置されたフォ
トダイオードアレイである請求項５に記載の検出装置。6. The detection device according to claim 5, wherein the photodiode is a photodiode array arranged perpendicular to the flow direction of the fluid and perpendicular to the optical axis.
素子の信号を多段に重ね合わせる差動増幅器を含む請求
項６に記載の検出装置。7. The detection device according to claim 6, wherein the electric circuit includes a differential amplifier that superimposes signals of respective elements of the photodiode array 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 true JPH05215664A (en) | 1993-08-24 |
| JP3151036B2 JP3151036B2 (en) | 2001-04-03 |
Family
ID=13026566
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| 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 |
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| Country | Link |
|---|---|
| JP (1) | JP3151036B2 (en) |
Cited By (7)
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| EP0716869A2 (en) | 1994-10-27 | 1996-06-19 | Mikuni Kikai Ltd. | Gas-liquid separator and particle monitor provided with the gasliquid separator |
| JP2000121540A (en) * | 1998-10-16 | 2000-04-28 | Horiba Ltd | Apparatus for measuring particle size distribution |
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| EP0716869A2 (en) | 1994-10-27 | 1996-06-19 | Mikuni Kikai Ltd. | Gas-liquid separator and particle monitor provided with the gasliquid separator |
| EP0716869A3 (en) * | 1994-10-27 | 1997-05-28 | Mikuni Kikai Ltd | Gas-liquid separator and particle monitor provided with the gasliquid separator |
| JP2000121540A (en) * | 1998-10-16 | 2000-04-28 | Horiba Ltd | Apparatus for measuring particle size distribution |
| US8142660B2 (en) | 2006-10-19 | 2012-03-27 | Hirata Corporation | Filtrate monitoring device, and filtrate monitoring system |
| JP2011059046A (en) * | 2009-09-14 | 2011-03-24 | Hokuto Denshi Kogyo Kk | Method for detecting size of particles in liquid and liquid pipeline |
| CN108474731A (en) * | 2016-01-21 | 2018-08-31 | 东京毅力科创株式会社 | Detection device for foreign matter and foreign matter detecting method |
| WO2017126360A1 (en) * | 2016-01-21 | 2017-07-27 | 東京エレクトロン株式会社 | Foreign matter detection device and foreign matter detection method |
| JPWO2017126360A1 (en) * | 2016-01-21 | 2018-11-08 | 東京エレクトロン株式会社 | Foreign object detection device and foreign object detection method |
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| KR20220150339A (en) | 2020-03-09 | 2022-11-10 | 도쿄엘렉트론가부시키가이샤 | Foreign material detection apparatus, substrate processing apparatus, foreign material detection method and storage medium |
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