JPH065888A - Photodetector and failure monitoring system for electric equipment using the photodetector - Google Patents
Photodetector and failure monitoring system for electric equipment using the photodetectorInfo
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- JPH065888A JPH065888A JP4163050A JP16305092A JPH065888A JP H065888 A JPH065888 A JP H065888A JP 4163050 A JP4163050 A JP 4163050A JP 16305092 A JP16305092 A JP 16305092A JP H065888 A JPH065888 A JP H065888A
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- light
- photodetector
- receiving element
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- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
- Light Receiving Elements (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
- Testing Relating To Insulation (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は光検出装置及びそれを用
いた電気機器の故障監視装置に係り、特に、微弱光を検
出する光検出装置及びそれを用いた電気機器の故障監視
装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photodetector and a failure monitor for electric equipment using the same, and more particularly to a photodetector for detecting weak light and a failure monitor for electric equipment using the same.
【０００２】近年、電力変電設備は電力の安定供給のた
め、その増設が進んでいる。一方、安全性の面からは、
故障が発生した場合の復旧時間を短縮するため、故障に
対する故障監視装置が発達している。In recent years, the expansion of electric power substation equipment has been advanced in order to stably supply electric power. On the other hand, in terms of safety,
In order to shorten the recovery time when a failure occurs, a failure monitoring device for the failure has been developed.
【０００３】例えば、絶縁性のガス等を絶縁媒体として
封入した変圧器や開閉装置等の高電圧電気機器では故障
が発生する前駆現象として、異常部分から微弱な部分放
電が発生する。また、さらに、異常な状態が進行すると
高電圧導体と接地導体との間で絶縁破壊が生じ、閃絡現
象が発生する。予備診断システムではこの微弱な部分放
電や閃絡現象等による発光を検出することにより故障の
予備診断を行っている。For example, a weak partial discharge occurs from an abnormal portion as a precursor phenomenon in which a failure occurs in a high voltage electric device such as a transformer or a switchgear in which an insulating gas or the like is enclosed as an insulating medium. Further, when an abnormal state progresses, insulation breakdown occurs between the high voltage conductor and the ground conductor, and a flashover phenomenon occurs. In the preliminary diagnosis system, the preliminary diagnosis of the failure is performed by detecting the light emission due to the weak partial discharge and the flashover phenomenon.
【０００４】従って、このような故障監視装置では微弱
な放電光を検出する必要があるため、微弱な光を雑音等
の影響なく検出できる光検出装置が必要とされている。Therefore, since such a failure monitoring device needs to detect weak discharge light, there is a need for a photodetector capable of detecting weak light without the influence of noise or the like.
【０００５】[0005]
【従来の技術】図４は従来の電気機器の故障監視装置の
ブロック構成図を示す。同図中、１は電気機器を示す。
電気機器１は遮光容器１ａ内に電気機器本体１ｂを収納
してなる。遮光容器１ａ内には電気機器本体１ｂを包囲
するようにコアに入射光を蛍光変換する蛍光物質を含有
する蛍光ファイバ２が配設されている。2. Description of the Related Art FIG. 4 shows a block diagram of a conventional failure monitoring apparatus for electric equipment. In the figure, 1 indicates an electric device.
The electric device 1 comprises an electric device body 1b housed in a light shielding container 1a. In the light-shielding container 1a, a fluorescent fiber 2 containing a fluorescent substance that converts the incident light into fluorescent light is arranged in a core so as to surround the electric device body 1b.
【０００６】蛍光ファイバ２の一端は貫通端子３を介し
て遮光容器１ａ外に引き出され、導光ファイバ４により
光検出装置となる光電気変換部５に接続される。光電気
変換部５は定電圧ＶC により逆バイアスされたアバラン
シェ・フォト・ダイオードＤ 1 のアノードを抵抗Ｒ1 と
共に反転増幅器を構成するオペアンプ５ａの反転入力端
子に接続してなる。One end of the fluorescent fiber 2 is connected to the through terminal 3
The light-guiding fiber 4
It is connected to a photoelectric conversion unit 5 that serves as a photodetector. Photoelectric
The conversion unit 5 has a constant voltage VCReverse-biased by Avalan
Ché Photo Diode D 1R of the anode of1When
Inverting input terminal of operational amplifier 5a, which together constitute an inverting amplifier
Connected to the child.
【０００７】導光ファイバ４より出力される光はアバラ
ンシェ・フォト・ダイオードＤ1 の接合部に照射され
る。アバランシェ・フォト・ダイオードＤ1 は入射され
た光に応じて流れる光電流が変化する。このため、オペ
アンプ５ａの反転入力端子に入力される信号レベルが変
化する。オペアンプ５ａは抵抗Ｒ1 と共に反転増幅回路
を構成し、入力された信号レベルを反転増幅して出力す
る。The light output from the light guide fiber 4 is applied to the junction of the avalanche photodiode D 1 . The photocurrent flowing through the avalanche photodiode D 1 changes according to the incident light. Therefore, the signal level input to the inverting input terminal of the operational amplifier 5a changes. The operational amplifier 5a constitutes an inverting amplifier circuit together with the resistor R 1 , and inverts and amplifies the input signal level and outputs it.
【０００８】このように、光電気変換部５では入力光を
反転増幅した電気信号が出力される。光電気変換部５の
出力信号は判定器６に入力される。As described above, the photoelectric conversion section 5 outputs an electric signal obtained by inverting and amplifying the input light. The output signal of the photoelectric conversion unit 5 is input to the determiner 6.
【０００９】判定器６は光電気変換部５の出力信号レベ
ルが一定値以上となると電気機器１内で放電等が生じた
と判定して、判定信号を表示器７に供給する。表示器７
では判定器６からの判定信号に応じて電気機器１に異常
があることを知らせる表示を行なっていた。When the output signal level of the photoelectric conversion unit 5 exceeds a certain value, the judging device 6 judges that a discharge or the like has occurred in the electric device 1, and supplies a judgment signal to the display device 7. Display 7
Then, according to the determination signal from the determination device 6, a display indicating that the electric device 1 is abnormal is displayed.
【００１０】[0010]
【発明が解決しようとする課題】しかるに、従来の光検
出装置では一つのＡＰＤ（アバランシェ・フォト・ダイ
オード）等の受光素子で入力光を検出していたため、そ
の検出信号には熱や逆バイアス変動による暗電流が混入
していた。このため、入力光が微弱な場合、検出信号レ
ベルが暗電流による信号にうもれてしまい、入力光の検
出が行なえない等の問題点があった。However, in the conventional photodetector, the input light is detected by a single light receiving element such as an APD (avalanche photo diode), so that the detection signal thereof includes heat or reverse bias fluctuation. The dark current was mixed in. Therefore, when the input light is weak, the detection signal level is covered by the signal due to the dark current, and there is a problem that the input light cannot be detected.
【００１１】本発明は上記の点に鑑みてなされたもの
で、暗電流による信号を除去することにより微弱光の検
出を可能とした光検出装置及びそれを用いた電気機器の
故障監視装置を提供することを目的とする。The present invention has been made in view of the above points, and provides a photodetector capable of detecting weak light by removing a signal due to a dark current and a failure monitoring device for electric equipment using the photodetector. The purpose is to do.
【００１２】[0012]
【課題を解決するための手段】図１は本発明の原理ブロ
ック図を示す。同図中、８は第１の受光素子、１０は第
２の受光素子、１１は差分検出手段を示す。第１の受光
素子８は入力光ＬINを受光し、入力光ＬINに応じた検出
信号を出力する。FIG. 1 shows a block diagram of the principle of the present invention. In the figure, 8 is a first light receiving element, 10 is a second light receiving element, and 11 is a difference detecting means. The first light receiving element 8 receives the input light L IN, and outputs a detection signal corresponding to the input light L IN.
【００１３】第２の受光素子１０は遮光容器９内に収納
され、暗状態で検出される参照信号を出力する。差分検
出手段１１は検出信号と参照信号との差分を検出する。The second light receiving element 10 is housed in the light shielding container 9 and outputs a reference signal detected in the dark state. The difference detection means 11 detects the difference between the detection signal and the reference signal.
【００１４】[0014]
【作用】第１の受光素子により入力光に応じた検出信号
を検出する。第２の受光素子は遮光容器内に収納されて
いて暗状態での信号を参照信号として出力する。このと
き、第１の受光素子で検出した光電流には暗電流が混合
されている。The first light receiving element detects the detection signal corresponding to the input light. The second light receiving element is housed in a light shielding container and outputs a signal in a dark state as a reference signal. At this time, the dark current is mixed with the photocurrent detected by the first light receiving element.
【００１５】従って、差分検出手段により第１の受光素
子で検出した光電流に応じた検出信号と第２の受光素子
で検出した暗状態での参照信号との差分を取ることによ
り暗状態で発生する信号分が除去され、入力光に応じた
信号のみを検出できる。Therefore, the difference detection means takes the difference between the detection signal corresponding to the photocurrent detected by the first light receiving element and the reference signal in the dark state detected by the second light receiving element, and is generated in the dark state. The signal component corresponding to the input light is removed, and only the signal corresponding to the input light can be detected.
【００１６】[0016]
【実施例】図２は本発明の一実施例の構成図を示す。同
図中、１２は電気機器を示す。電気機器１２は遮光容器
１２ａ内に電気機器本体１２ｂを収納してなる。遮光容
器１２ａ内には蛍光ファイバ１３が電気機器本体１２ｂ
を取り巻くように配設されている。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 2 is a block diagram of an embodiment of the present invention. In the figure, 12 indicates an electric device. The electric device 12 includes an electric device body 12b housed in a light shielding container 12a. In the light-shielding container 12a, the fluorescent fiber 13 is provided in the electric device body 12b
Are arranged so as to surround.
【００１７】蛍光ファイバ１３は軸中心に透明体（例え
ば、ポリカーボネートや石英ガラス等）よりなり、光を
当てると蛍光を発する発光物質を含有したコアを有し、
このコアの外径側にやはり透明体よりなるクラッドを形
成してなる。コアの屈折率はクラッドのそれより大きく
なるようにそれぞれの材料組成が選ばれている。The fluorescent fiber 13 is made of a transparent material (for example, polycarbonate or quartz glass) at the center of its axis and has a core containing a luminescent substance which emits fluorescence when exposed to light.
A clad made of a transparent material is also formed on the outer diameter side of the core. Each material composition is selected so that the refractive index of the core is larger than that of the clad.
【００１８】このため、蛍光ファイバ１３は光や放射線
が入射すると、発光物質が発光する。蛍光ファイバ１３
内で発光した光は蛍光ファイバ１３の端部に伝達され
る。Therefore, when the light or radiation enters the fluorescent fiber 13, the light emitting substance emits light. Fluorescent fiber 13
The light emitted inside is transmitted to the end of the fluorescent fiber 13.
【００１９】蛍光ファイバ１３の一端は貫通端子１４を
介して遮光容器１２ａ外部に引き出された導光ファイバ
１５の一端に接続される。導光ファイバ１５の他端は光
検出装置となる光／電気変換器１６に接続される。光／
電気変換器１６は第１の受光素子となるアバランシェ・
フォト・ダイオード（以下、フォトダイオード）Ｄ2，
第２の受光素子となるアバランシェ・フォト・ダイオー
ド（以下、フォトダイオード）Ｄ3 ，抵抗Ｒ2 ，Ｒ3 と
共に差動増幅器を構成するオペアンプ１５ａより構成さ
れる。One end of the fluorescent fiber 13 is connected to one end of a light guide fiber 15 drawn out of the light shielding container 12a via a through terminal 14. The other end of the light guide fiber 15 is connected to an optical / electrical converter 16 which serves as a photodetector. light/
The electrical converter 16 is an avalanche
Photodiode (hereinafter, photodiode) D 2 ,
It is composed of an avalanche photo diode (to be referred to as a photo diode hereinafter) D 3 , which is a second light receiving element, and an operational amplifier 15a which constitutes a differential amplifier together with resistors R 2 and R 3 .
【００２０】フォトダイオードＤ2 及びフォトダイオー
ドＤ3 のカソードは定電圧ＶC が印加され、逆バイアス
状態とされる。A constant voltage V C is applied to the cathodes of the photodiode D 2 and the photodiode D 3 to bring them into a reverse bias state.
【００２１】また、フォトダイオードＤ2 のアノードは
オペアンプ１６ａの反転入力端子に接続され、フォトダ
イオードＤ3 のアノードはオペアンプ１６ａの非反転入
力端子に接続される。The anode of the photodiode D 2 is connected to the inverting input terminal of the operational amplifier 16a, and the anode of the photodiode D 3 is connected to the non-inverting input terminal of the operational amplifier 16a.
【００２２】オペアンプ１６ａの出力端子は判定器１７
の入力端子に接続される。判定器１７は入力信号レベル
に応じて故障の判定を行なう。判定器１７の出力端子は
表示器１８に接続されていて、表示器１８に判定結果を
供給する。表示器１８は判定器１７からの判定結果を表
示する。The output terminal of the operational amplifier 16a is a decision unit 17
Connected to the input terminal of. The determiner 17 determines a failure according to the input signal level. The output terminal of the determiner 17 is connected to the display 18, and supplies the determination result to the display 18. The display 18 displays the determination result from the determiner 17.
【００２３】また、フォトダイオードＤ2 の接合部には
導光ファイバ１５の他端が結合していて、フォトダイオ
ードＤ2 に蛍光ファイバ１３で蛍光変換された光を照射
する。フォトダイオードＤ2 は照射された光Ｌ1 に応じ
てインピーダンスが変化し、オペアンプ１６ａの反転入
力端子に供給する信号レベルを変化させる。The other end of the light guide fiber 15 is coupled to the junction of the photodiode D 2 so that the photodiode D 2 is irradiated with the light converted by the fluorescent fiber 13. The impedance of the photodiode D 2 changes according to the applied light L 1 , and the signal level supplied to the inverting input terminal of the operational amplifier 16a changes.
【００２４】フォトダイオードＤ3 は遮光容器１６ｂ内
に収納されていて、暗状態に保持される。このため、フ
ォトダイオードＤ3 からは熱や逆バイアス電圧ＶC の変
動に応じた暗電流が出力される。従って、オペアンプ１
６ａの非反転入力端子には暗電流に応じた信号が入力さ
れる。The photodiode D 3 is housed in the light shielding container 16b and kept in the dark state. Therefore, the photodiode D 3 outputs a dark current depending on heat and fluctuations in the reverse bias voltage V C. Therefore, operational amplifier 1
A signal corresponding to the dark current is input to the non-inverting input terminal of 6a.
【００２５】このため、オペアンプ１６ａの出力はフォ
トダイオードＤ3 より供給される暗電流に応じた信号よ
りフォトダイオードＤ2 より供給される入射光Ｌに応じ
た光電流とフォトダイオードＤ2 で発生する暗電流との
和の信号を減じた信号となる。Therefore, the output of the operational amplifier 16a is generated in the photo diode D 2 and the photo current corresponding to the incident light L supplied from the photo diode D 2 from the signal corresponding to the dark current supplied from the photo diode D 3. It is a signal obtained by subtracting the signal of the sum of the dark current.
【００２６】従って、暗電流の信号分は除去され、光電
流に応じた信号だけが出力されることになる。このよう
に入力光Ｌに応じた信号だけを取り出すことができるた
め、暗電流によりうずもれてしまうような微弱な光電流
しか得られない微弱な光をも確実に検出することができ
る。Therefore, the dark current signal component is removed, and only the signal corresponding to the photocurrent is output. Since only the signal corresponding to the input light L can be taken out in this manner, it is possible to reliably detect even weak light, which can only obtain a weak photocurrent that is missed by a dark current.
【００２７】従って、電気機器内での放電等による発光
を確実に検出でき、電気機器の状態を確実に知り得る。Therefore, the light emission due to the discharge or the like in the electric equipment can be surely detected, and the state of the electric equipment can be surely known.
【００２８】なお、本実施例は電気機器の故障監視シス
テムにおいて、光電変換部として本発明の光検出装置を
適用しているが、これに限ることはなく、種々のものに
適用できることは言うまでもない。Although the present embodiment applies the photodetection device of the present invention as a photoelectric conversion unit in a failure monitoring system for electric equipment, it is needless to say that the present invention is not limited to this and can be applied to various devices. .
【００２９】また、受光素子もアバランシェ・フォト・
ダイオードに限ることはなく、暗電流等のノイズの影響
を受ける受光素子に対して適用できる。The light receiving element is also an avalanche photo
The invention is not limited to the diode, but can be applied to a light receiving element affected by noise such as dark current.
【００３０】なお、光／電気変換器１６は図３に示すよ
うにフォトダイオードＤ2 ，Ｄ3 を増幅回路を構成する
オペアンプ１９ａ，１９ｂに接続し、フォトダイオード
Ｄ2，Ｄ3 による光電流及び暗電流を夫々増幅して、差
動増幅器を構成するオペアンプ１６ａに供給する構成と
してもよい。In the opto-electric converter 16, as shown in FIG. 3, the photodiodes D 2 and D 3 are connected to operational amplifiers 19a and 19b constituting an amplifier circuit, and the photocurrent and the photocurrent generated by the photodiodes D 2 and D 3 are The dark current may be amplified and supplied to the operational amplifier 16a forming the differential amplifier.
【００３１】[0031]
【発明の効果】上述の如く、本発明によれば、第１の受
光素子で検出した入力光に応じた検出信号と第２の受光
素子から出力される参照信号との差分を取ることにより
検出信号より暗電流成分を除去することができるため、
入力光が微弱な場合でも暗電流によるノイズを除去し、
入力光に応じた信号を検出できる。As described above, according to the present invention, detection is performed by taking the difference between the detection signal corresponding to the input light detected by the first light receiving element and the reference signal output from the second light receiving element. Since the dark current component can be removed from the signal,
Removes noise due to dark current even when the input light is weak,
A signal corresponding to the input light can be detected.
【００３２】また、このような光検出装置を用いた電気
機器の故障監視装置では微弱な光を確実にとらえること
ができるため、電気機器の故障を早期に確実に知ること
ができる等の特長を有する。In addition, since a fault monitoring device for an electric device using such a photodetector can reliably detect weak light, it has a feature that a failure of the electric device can be surely known at an early stage. Have.
【図１】本発明の原理ブロック図である。FIG. 1 is a principle block diagram of the present invention.
【図２】本発明の一実施例の構成図である。FIG. 2 is a configuration diagram of an embodiment of the present invention.
【図３】本発明の他の実施例の要部の構成図である。FIG. 3 is a configuration diagram of a main part of another embodiment of the present invention.
【図４】従来の一例の構成図である。FIG. 4 is a configuration diagram of a conventional example.
８ 第１の受光素子 ９ 遮光容器 １０ 第２の受光素子 １１ 差分検出手段 8 1st light receiving element 9 light-shielding container 10 2nd light receiving element 11 difference detection means
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.5 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｈ０２Ｈ 5/00 Ｂ 9061−5Ｇ (72)発明者 田中 章 神奈川県川崎市中原区上小田中1015番地 富士通株式会社内─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 5 Identification number Reference number in the agency FI Technical indication location H02H 5/00 B 9061-5G (72) Inventor Akira Tanaka 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Within Fujitsu Limited
Claims (3)
IN）に応じた検出信号を出力する第１の受光素子（８）
と、 遮光容器（９）内に収納され、暗電流に応じた参照信号
を出力する第２の受光素子（１０）と、 前記第１の受光素子（８）から前記検出信号が入力さ
れ、前記第２の受光素子（１０）から前記参照信号が入
力され、前記検出信号と前記参照信号との差分を検出
し、前記検出信号より前記暗電流成分を除去した信号を
得る差分検出手段（１１）とを有することを特徴とする
光検出装置。1. An input light (L IN ) is received and the input light (L IN ) is received.
The first light receiving element (8) that outputs the detection signal according to IN )
A second light receiving element (10) housed in a light shielding container (9) for outputting a reference signal according to a dark current; and the detection signal input from the first light receiving element (8), The reference signal is input from the second light receiving element (10), the difference between the detection signal and the reference signal is detected, and a difference detection means (11) for obtaining a signal obtained by removing the dark current component from the detection signal is obtained. And a photodetector.
路により構成されたことを特徴とする請求項１記載の光
検出装置。2. The photodetector according to claim 1, wherein the difference detecting means (11) is composed of a differential amplifier circuit.
障時に発生する光を検出することにより前記電気機器の
故障を監視する電気機器の故障監視装置において、 前記光の検出に請求項１記載の光検出装置を用いること
を特徴とする電気機器の故障監視装置。3. A failure monitoring device for an electric device for monitoring a failure of the electric device by detecting light generated at the time of a failure from the electric device housed in the light-shielding container, wherein the detection of the light is performed. Failure detection device for electric equipment, characterized by using the above-mentioned photo detection device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4163050A JPH065888A (en) | 1992-06-22 | 1992-06-22 | Photodetector and failure monitoring system for electric equipment using the photodetector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4163050A JPH065888A (en) | 1992-06-22 | 1992-06-22 | Photodetector and failure monitoring system for electric equipment using the photodetector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH065888A true JPH065888A (en) | 1994-01-14 |
Family
ID=15766224
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4163050A Withdrawn JPH065888A (en) | 1992-06-22 | 1992-06-22 | Photodetector and failure monitoring system for electric equipment using the photodetector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH065888A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002229511A (en) * | 2001-02-02 | 2002-08-16 | Tohoku Pioneer Corp | Device for driving organic el display panel and method therefor |
| US8405019B2 (en) | 2008-09-12 | 2013-03-26 | Mitsubishi Electric Corporation | Photon detector |
| JP2016524690A (en) * | 2013-03-15 | 2016-08-18 | セラノス， インコーポレイテッド | Femtowatt non-vacuum tube detector assembly |
| JP2019207946A (en) * | 2018-05-29 | 2019-12-05 | 浜松ホトニクス株式会社 | Light difference detector and inspection device |
-
1992
- 1992-06-22 JP JP4163050A patent/JPH065888A/en not_active Withdrawn
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002229511A (en) * | 2001-02-02 | 2002-08-16 | Tohoku Pioneer Corp | Device for driving organic el display panel and method therefor |
| US8405019B2 (en) | 2008-09-12 | 2013-03-26 | Mitsubishi Electric Corporation | Photon detector |
| JP2016524690A (en) * | 2013-03-15 | 2016-08-18 | セラノス， インコーポレイテッド | Femtowatt non-vacuum tube detector assembly |
| US10014837B2 (en) | 2013-03-15 | 2018-07-03 | Theranos Ip Company, Llc | Femtowatt non-vacuum tube detector assembly |
| US10778167B2 (en) | 2013-03-15 | 2020-09-15 | Labrador Diagnostics Llc | Femtowatt non-vacuum tube detector assembly |
| US11309856B2 (en) | 2013-03-15 | 2022-04-19 | Labrador Diagnostics Llc | Femtowatt non-vacuum tube detector assembly |
| JP2019207946A (en) * | 2018-05-29 | 2019-12-05 | 浜松ホトニクス株式会社 | Light difference detector and inspection device |
| WO2019230147A1 (en) * | 2018-05-29 | 2019-12-05 | 浜松ホトニクス株式会社 | Optical difference detector and inspection device |
| CN112204755A (en) * | 2018-05-29 | 2021-01-08 | 浜松光子学株式会社 | Optical differential detector and inspection device |
| US11243113B2 (en) | 2018-05-29 | 2022-02-08 | Hamamatsu Photonics K.K. | Optical difference detector and inspection device |
| US11733091B2 (en) | 2018-05-29 | 2023-08-22 | Hamamatsu Photonics K.K. | Optical difference detector and inspection device |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Application deemed to be withdrawn because no request for examination was validly filed |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 19990831 |