WO1995003623A1 - Photomultiplier gain control method - Google Patents

Photomultiplier gain control method Download PDF

Info

Publication number
WO1995003623A1
WO1995003623A1 PCT/FR1994/000901 FR9400901W WO9503623A1 WO 1995003623 A1 WO1995003623 A1 WO 1995003623A1 FR 9400901 W FR9400901 W FR 9400901W WO 9503623 A1 WO9503623 A1 WO 9503623A1
Authority
WO
WIPO (PCT)
Prior art keywords
dynodes
polarized
transformer
tube
photomultiplier
Prior art date
Application number
PCT/FR1994/000901
Other languages
French (fr)
Inventor
Bernard Toullec
Jean-Pierre Pommeret
Original Assignee
Thomson-Csf
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Thomson-Csf filed Critical Thomson-Csf
Priority to AU72667/94A priority Critical patent/AU7266794A/en
Publication of WO1995003623A1 publication Critical patent/WO1995003623A1/en

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
    • H01J43/04—Electron multipliers
    • H01J43/30—Circuit arrangements not adapted to a particular application of the tube and not otherwise provided for

Definitions

  • the present invention relates to methods which make it possible to control the gain of photomultiplier tubes in order in particular to be able to detect an optical signal having a very large variation in intensity in a very short time.
  • the laser signals generally used come mainly from pulsed lasers emitting intense pulses of very short duration. These pulses are reflected or backscattered to an optical receiver and the intensity of the return signals varies greatly from a large value corresponding to direct reflection on the air / water interface to a very low value corresponding to backscattering limited to the maximum depth reached.
  • the dynamics of this optical signal can exceed 100 dB in less than 150 nanoseconds.
  • the tut. photomultiplier generally used in practice to detect these light pulses can be polarized either so as not to be dazzled by the brightness of the reflection on the air / water surface (low gain), or to detect the very weak signal corresponding to the limit range of the laser pulse (strong gain). If it is polarized not to be dazzled, it will not be able to detect the weakest signals, and if it is polarized to detect these it will be dazzled by the reflection on the surface.
  • Another known technique for varying the gain of the photomultiplier tube consists in connecting the odd and even dynodes respectively to two networks of polarization resistors and adding an offset voltage of a few tens of volts (30 for example) relative to the voltage operating minimum, to reduce the gain of the tube.
  • an offset voltage of a few tens of volts (30 for example) relative to the voltage operating minimum.
  • the invention provides a method of controlling the gain of a photomultiplier tube to obtain a linear response over a very large dynamic range for a very short time and without significantly varying the transit time of the electrons inside. of this tube, characterized in that some of the intermediate dynodes d3 - d7 of the tube 1 are polarized by means of a transformer 25 with very wide passband and weakly damped; this transformer being itself supplied by a substantially linear current ramp and the other dynodes being polarized by a known resistive network 9 - 18.
  • FIG. 1 there is shown a schematic section of a photomultiplier tube 1 comprising a pnotocatode 2 intended to receive the light signals to emit in response an electron flow. These electrons are focused by a focusing grid 3 towards a set 4 of dynodes d1 to d12. As is well known, each electron that strikes a dynode causes the emission of several secondary electrons which are directed to the next dynode, where this multiplier effect is reproduced, and so on. The flow of electrons thus multiplied leaving the dynode darnode d12 arrives on an anode 5 causing in the output connection of this anode a relatively intense current having regard to the few electrons emitted by photocatode 2.
  • This output connection of the anode is connected to ground via a resistor 6, of 1 k ⁇ for example.
  • This mass corresponds to the positive pole of a high voltage source, 2000 volts for example, the negative pole of which is connected to the photocathode 2 via a resistor 7, of 4.7 M ⁇ for example.
  • the current flowing in the resistor 6 causes a voltage drop across its terminals and this voltage drop is applied to an output connector 8 on which the electrical signal corresponding to the light signal arriving on the photocatode 2 is collected.
  • the assembly is designed to operate at microwave frequency and this output is coaxial.
  • the different dynodes must be polarized by a set of voltages staggered between the voltage of the anode and that of the photocatode. These voltages are conventionally obtained by a bias network conforming to the manufacturer's specifications and supplied by the high voltage source.
  • a set of resistors 9 to 18 is used, connected in series between the ground and the negative pole of the high voltage source. These resistances for example have 220 k, ⁇ 200 k ⁇ , 130 k ⁇ , 120 k as respective values
  • capacitors 19 to 24 having respectively as values for example
  • this polarization of the dynodes using this resistance network only concerns the dynodes d1, d2, d4, and d7 to d12.
  • the dynodes d3, d5 and d6, as well as in part the dynodes d4 and d7, are polarized separately by means of a transformer 25 described below.
  • This transformer which is very wide band and weakly damped, includes a primary winding 26 and 2 secondary windings 27 and
  • the two output terminals of the first secondary winding 27 are connected respectively to the dynodes d3 and d4. It is recalled that the dynode d4 is itself connected to the polarization network.
  • the two terminals of the second secondary winding 28 are connected respectively to the dynodes d5 and d7; the d7 dynode being itself connected to the polarization network. These two terminals are also connected together by two resistors 29 and 30, of values equal to 68 kohms for example, connected in series to form a bridge whose central point is connected to the dynode d6.
  • these windings are shunted by capacitors 31 and 32, of value 47 pF for example, and by diodes 33 and 34, of type 11 DF 04 by example.
  • the primary winding 26 is supplied by a bias voltage, of +80 volts for example, filtered by a resistor 35, of 10 ⁇ for example, and two capacitors 36 and 37, of 22 microfarads and 0.1 microfarad for example, connected to ground.
  • the other end of this primary winding is connected to the drain of a field effect transistor 38, of the IRF 530 type for example, the source of which is connected to ground.
  • This primary winding is also shunted by a freewheeling diode 39, of the type 11 DF 04 for example.
  • the control signals of the transistor 38 are applied to its gate from an input 40, of the coaxial type for example.
  • This grid is also connected to ground by a resistor 41, of 200 ohms for example.
  • the control voltage applied to the input 40 varies the conductance of the transistor 38 which, taking into account the values of the elements and the voltages, is used in its variable resistance zone.
  • This control voltage is in the form of a voltage ramp varying from 0 V to 6 V during the period provided for the variation of the gain desired for the photomultiplier 1, that is to say the period of time provided for detect the corresponding light signal in the example described in the backscattering of the laser flash.
  • this assembly makes it possible to measure light signals of very high dynamics, greater than 90dB for example, over very short durations, 50 ns for example. It is perfectly suited in particular to the detection of lumin ⁇ ux echoes coming from the backscattering of a laser pulse sent on a liquid surface, for example the surface of the sea, to probe the liquid mass which extends under this surface. and detect objects submerged on the seabed.

Abstract

Methods for linear photomultiplier gain control over a large dynamic range are disclosed. The central dynodes (d3 - d7) of the photomultiplier (1) are powered via a very wide pass-band, low-damping transformer (25) which is in turn powered by a voltage ramp from a bias circuit (35-41) with a field-effect transistor (38) used in the variable resistance region thereof, whereby linear detection of light echoes from laser flash backscattering in a marine environment may be achieved.

Description

PROCEDE DE COMMANDE DU GAIN D'UN TUBE PHOTOMULTIPLICATEUR METHOD FOR CONTROLLING THE GAIN OF A PHOTOMULTIPLIER TUBE
La présente invention concerne les procédés qui permettent de commander le gain des tubes photomultiplicateurs afin notamment de pouvoir détecter un signal optique présentant une très grande variation d'intensité en un temps très bref.The present invention relates to methods which make it possible to control the gain of photomultiplier tubes in order in particular to be able to detect an optical signal having a very large variation in intensity in a very short time.
En dépit des progrès des détecteurs à l'état solide, les tubes photomultiplicateurs sont toujours utilisés pour détecter des signaux lumineux de faible intensité et/ou présentant des variations rapides dans le temps. C'est en particulier le cas pour les signaux optiques issus de la rétrodiffusion des signaux lasers émis vers la surface de la mer pour repérer les objets divers situés à l'intérieur de la masse marine. Compte tenu de l'absorption importante de l'eau, les signaux lasers généralement utilisés proviennent surtout de lasers puisés émettant des impulsions intenses de durée très courte. Ces impulsions sont réfléchies ou retrodiffusees vers un récepteur optique et l'intensité des signaux en retour varie fortement depuis une valeur importante correspondant à la réflexion directe sur l'interface air/eau jusqu'à une valeur très faible correspondant à la rétrodiffusion limite à la profondeur maximale atteinte. Dans la pratique, et en fonction des différents paramètres comprenant en particulier la turbidite de l'eau, la dynamique de ce signal optique peut excéder 100 dB en moins de 150 nanosecondes. Le tut. photomultiplicateur généralement utilisé dans la pratique pour détecter ces impulsions lumineuses peut être polarisé soit pour ne pas être ébloui par l'éclat de la réflexion sur la surface air/eau (gain faible), soit pour détecter le très faible signal correspondant à la portée limite de l'impulsion laser (gain fort). S'il est polarisé pour ne pas être ébloui, il ne pourra pas détecter les signaux les plus faibles, et s'il est polarisé pour détecter ceux-ci il sera ébloui par la réflexion en surface. Il est donc nécessaire si on veut utiliser un seul tube pour obtenir la détection sur toute la portée du faisceau laser de faire varier le gain du tube pendant la durée de réception de l'impulsion de préférence sur une dynamique approchant le plus possible celle de l'impulsion réfléchie. Les tubes photomultiplicateurs modernes sont justement conçus pour que l'on puisse modifier leur gain par commutation de tension sur une ou plusieurs grilles spécialisées. L'utilisation de ces grilles ne permet toutefois d'obtenir une dynamique que de l'ordre de 20 dB, ce qui est relativement faible. En outre, cette technique de modification de gain du tube entraîne une variation du temps de transit des électrons à l'intérieur du tube, ce qui est rédhibitoire dans certaines applications où l'on est amené à mesurer une différence de temps entre deux signaux, notamment celle citée plus haut. Une autre technique connue pour faire varier le gain du tube photomultiplicateur consiste à relier les dynodes impaires et paires respectivement à deux réseaux de résistances de polarisation et à ajouter une tension de décalage de quelques dizaines de volts (30 par exemple) par rapport à la tension minimale de fonctionnement, pour réduire le gain du tube. En appliquant des impulsions de -30 volts sur le réseau de dynodes paires par l'intermédiaire d'un ensemble de condensateurs, on peut alors commuter le gain d'une valeur minimale à la valeur nominale pour laquelle est prévue le tube. Toutefois cette technique entraîne un temps de réaction à la commutation qui peut dépasser la centaine de microsecondes, en raison de la forte valeur d'impédance du réseau de polarisation ainsi que la forte tension d'alimentation utilisée. Ce temps de réaction est tout à fait prohibitif pour les applications vues plus haut.Despite the progress of solid state detectors, photomultiplier tubes are still used to detect light signals of low intensity and / or with rapid variations over time. This is in particular the case for the optical signals resulting from the backscattering of the laser signals emitted towards the surface of the sea to locate the various objects located inside the marine mass. Given the significant absorption of water, the laser signals generally used come mainly from pulsed lasers emitting intense pulses of very short duration. These pulses are reflected or backscattered to an optical receiver and the intensity of the return signals varies greatly from a large value corresponding to direct reflection on the air / water interface to a very low value corresponding to backscattering limited to the maximum depth reached. In practice, and depending on the various parameters including in particular the turbidity of the water, the dynamics of this optical signal can exceed 100 dB in less than 150 nanoseconds. The tut. photomultiplier generally used in practice to detect these light pulses can be polarized either so as not to be dazzled by the brightness of the reflection on the air / water surface (low gain), or to detect the very weak signal corresponding to the limit range of the laser pulse (strong gain). If it is polarized not to be dazzled, it will not be able to detect the weakest signals, and if it is polarized to detect these it will be dazzled by the reflection on the surface. It is therefore necessary if we want to use a single tube to obtain detection over the entire range of the laser beam to vary the gain of the tube during the duration of reception of the pulse preferably on a dynamic approaching as close as possible to that of the reflected pulse. Modern photomultiplier tubes are precisely designed so that their gain can be modified by voltage switching on one or more specialized grids. The use of these grids, however, makes it possible to obtain a dynamic range only of the order of 20 dB, which is relatively low. In addition, this technique of modifying the gain of the tube leads to a variation in the transit time of the electrons inside the tube, which is unacceptable in certain applications where it is necessary to measure a time difference between two signals, in particular that quoted above. Another known technique for varying the gain of the photomultiplier tube consists in connecting the odd and even dynodes respectively to two networks of polarization resistors and adding an offset voltage of a few tens of volts (30 for example) relative to the voltage operating minimum, to reduce the gain of the tube. By applying pulses of -30 volts to the network of even dynodes via a set of capacitors, one can then switch the gain from a minimum value to the nominal value for which the tube is intended. However, this technique results in a switching reaction time which can exceed one hundred microseconds, due to the high impedance value of the bias network as well as the high supply voltage used. This reaction time is completely prohibitive for the applications seen above.
On a également envisagé d'autres techniques dérivées de ces deux techniques principales, mais elle concernent toutes une commutation de gain d'une valeur minimale à la valeur nominale avec un temps de commmutation supérieur à la ms.Other techniques derived from these two main techniques have also been considered, but they all relate to gain switching from a minimum value to the nominal value with a switching time greater than ms.
Pour pallier ces inconvénients, l'invention propose un procédé de commande du gain d'un tube photomultiplicateur pour obtenir une réponse linéaire sur une dynamique très importante pendant une durée très courte et sans faire varier sensiblement le temps de transit des électrons à l'intérieur de ce tube, caractérisé en ce que l'on polarise certaines des dynodes intermédiaires d3 - d7 du tube 1 par l'intermédiaire d'un transformateur 25 à très large bande passante et faiblement amorti ; ce transformateur étant lui- même alimenté par une rampe de courant sensiblement linéaire et les autres dynodes étant polarisées par un réseau résistif 9 - 18 connu. D'autres particularités et avantages de l'invention apparaîtront clairement dans la description suivante, présentée à titre d'exemple non limitatif en regard de la figure unique annexée qui représente une vue schématique d'un tube photomultiplicateur et des circuits de polarisation qui lui sont associés pour mettre en oeuvre le procédé selon l'invention.To overcome these drawbacks, the invention provides a method of controlling the gain of a photomultiplier tube to obtain a linear response over a very large dynamic range for a very short time and without significantly varying the transit time of the electrons inside. of this tube, characterized in that some of the intermediate dynodes d3 - d7 of the tube 1 are polarized by means of a transformer 25 with very wide passband and weakly damped; this transformer being itself supplied by a substantially linear current ramp and the other dynodes being polarized by a known resistive network 9 - 18. Other features and advantages of the invention will appear clearly in the following description, presented by way of nonlimiting example with reference to the single appended figure which represents a schematic view of a photomultiplier tube and the bias circuits which are attached to it. associated to implement the method according to the invention.
Sur la figure 1 on a représenté une coupe schématique d'un tube photomultiplicateur 1 comportant une pnotocatode 2 destinée à recevoir les signaux lumineux pour émettre en réponse un flux d'électrons. Ces électrons sont focalisés par une grille de focalisation 3 vers un ensemble 4 de dynodes d1 à d12. De manière bien connue, chaque électron qui frappe une dynode vient provoquer l'émission de plusieurs électrons secondaires qui sont dirigés vers la dynode suivante, où cet effet multiplicateur se reproduit, et ainsi de suite. Le flux d'électrons ainsi multipliés sortant de la iarnière dynode d12 arrive sur une anode 5 en provoquant dans la connexion de sortie de cette anode un courant relativement intense eu égard aux quelques électrons émis par la photocatode 2. Cette connexion de sortie de l'anode est reliée à la masse par intermédiaire d'une résistance 6, de 1 kΩ par exemple. Cette masse correspond au pôle positif d'une source de haute tension, 2000 volts par exemple, dont le pôle négatif est relié à la photocathode 2 par l'intermédiaire d'une résistance 7, de 4,7 MΩ par exemple. Le courant qui circule dans la résistance 6 provoque une chute de tension aux bornes de celle-ci et cette chute de tension est appliquée à un connecteur de sortie 8 sur lequel on recueille le signal électrique correspondant au signal lumineux arrivant sur la photocatode 2. Pour pouvoir détecter des signaux lumineux de durée très courte, correspondant donc à des impulsions électriques très courtes sur la sortie 7, l'ensemble est prévu pour fonctionner en hyperfréquence et cette sortie est coaxiale.In Figure 1 there is shown a schematic section of a photomultiplier tube 1 comprising a pnotocatode 2 intended to receive the light signals to emit in response an electron flow. These electrons are focused by a focusing grid 3 towards a set 4 of dynodes d1 to d12. As is well known, each electron that strikes a dynode causes the emission of several secondary electrons which are directed to the next dynode, where this multiplier effect is reproduced, and so on. The flow of electrons thus multiplied leaving the dynode darnode d12 arrives on an anode 5 causing in the output connection of this anode a relatively intense current having regard to the few electrons emitted by photocatode 2. This output connection of the anode is connected to ground via a resistor 6, of 1 kΩ for example. This mass corresponds to the positive pole of a high voltage source, 2000 volts for example, the negative pole of which is connected to the photocathode 2 via a resistor 7, of 4.7 MΩ for example. The current flowing in the resistor 6 causes a voltage drop across its terminals and this voltage drop is applied to an output connector 8 on which the electrical signal corresponding to the light signal arriving on the photocatode 2 is collected. being able to detect light signals of very short duration, therefore corresponding to very short electrical pulses on output 7, the assembly is designed to operate at microwave frequency and this output is coaxial.
Pour obtenir l'effet d'amplification électronique souhaité, les différentes dynodes doivent être polarisées par un jeu de tensions échelonnées entre la tension de l'anode et celle de la photocatode. Ces tensions sont obtenues de manière classique par un réseau de polarisation conforme aux spécifications du fabricant et alimenté par la source de haute tension. Dans cet exemple, correspondant à un tube Philips du type XP2233, on utilise un ensemble de ré stances 9 à 18 reliées en série entre la masse et le pôle n> atif de la source de haute tension. Ces résistances ont par exemple comme valeurs respectives 220 k,Ω 200 kΩ, 130 kΩ, 120 kTo obtain the desired electronic amplification effect, the different dynodes must be polarized by a set of voltages staggered between the voltage of the anode and that of the photocatode. These voltages are conventionally obtained by a bias network conforming to the manufacturer's specifications and supplied by the high voltage source. In this example, corresponding to a Philips tube of the XP2233 type, a set of resistors 9 to 18 is used, connected in series between the ground and the negative pole of the high voltage source. These resistances for example have 220 k, Ω 200 kΩ, 130 kΩ, 120 k as respective values
Ω, 100 kΩ, 82 kΩ, 356 kΩ, 136 kΩ, 68 kΩ et 390 kΩ .Ω, 100 kΩ, 82 kΩ, 356 kΩ, 136 kΩ, 68 kΩ and 390 kΩ.
En outre, pour agir comme réservoir d'énergie, on connecte aux bornes des résistances 9 à 14, selon le schéma représenté sur la figure, des condensateurs 19 à 24 ayant respectivement comme valeurs par exempleIn addition, to act as an energy reservoir, one connects across the resistors 9 to 14, according to the diagram shown in the figure, capacitors 19 to 24 having respectively as values for example
4,7 nF, 3,3 nF, 1 nF, 10 nF, 3,3 nF et 1 ,1 nF.4.7 nF, 3.3 nF, 1 nF, 10 nF, 3.3 nF and 1.1 nF.
Selon l'invention cette polarisation des dynodes à l'aide de ce réseau de résistances ne concerne que les dynodes d1 , d2, d4, et d7 à d12.According to the invention, this polarization of the dynodes using this resistance network only concerns the dynodes d1, d2, d4, and d7 to d12.
Les dynodes d3, d5 et d6, ainsi qu'en partie les dynodes d4 et d7, sont polarisées séparément par l'intermédiaire d'un transformateur 25 décrit ci- dessous.The dynodes d3, d5 and d6, as well as in part the dynodes d4 and d7, are polarized separately by means of a transformer 25 described below.
Ce transformateur, qui est à très large bande et faiblement amorti, comprend un enroulement primaire 26 et 2 enroulements secondaires 27 etThis transformer, which is very wide band and weakly damped, includes a primary winding 26 and 2 secondary windings 27 and
28. Les deux bornes de sortie du premier enroulement secondaire 27 sont reliées respectivement aux dynodes d3 et d4. On rappelle que la dynode d4 est elle-même reliée au réseau de polarisation.28. The two output terminals of the first secondary winding 27 are connected respectively to the dynodes d3 and d4. It is recalled that the dynode d4 is itself connected to the polarization network.
Les deux bornes du deuxième enroulement secondaire 28 sont reliées respectivement aux dynodes d5 et d7 ; la dynode d7 étant elle-même reliée au réseau de polarisation. Ces deux bornes sont en outre reliées entre elles par deux résistances 29 et 30, de valeurs égales à 68 kohms par exemple, reliées en séries pour former un pont dont le point central est relié à la dynode d6.The two terminals of the second secondary winding 28 are connected respectively to the dynodes d5 and d7; the d7 dynode being itself connected to the polarization network. These two terminals are also connected together by two resistors 29 and 30, of values equal to 68 kohms for example, connected in series to form a bridge whose central point is connected to the dynode d6.
Pour filtrer les tensions ainsi appliquées à ces dynodes par les enroulements secondaires et éviter les surtensions, ces enroulements sont shuntés par des condensateurs 31 et 32, de valeur 47 pF par exemple, et par des diodes 33 et 34, du type 11 DF 04 par exemple.To filter the voltages thus applied to these dynodes by the secondary windings and avoid overvoltages, these windings are shunted by capacitors 31 and 32, of value 47 pF for example, and by diodes 33 and 34, of type 11 DF 04 by example.
L'enroulement primaire 26 est alimenté par une tension de polarisation, de +80 volts par exemple, filtrée par une résistance 35, de 10 Ω par exemple, et deux condensateurs 36 et 37, de 22 microfarads et 0,1 microfarad par exemple, reliés à la masse. L'autre extrémité de cet enroulement primaire est relié au drain d'un transistor à effet de champ 38, du type IRF 530 par exemple, dont la source est reliée à la masse. Cet enroulement primaire est en outre shunté par une diode de roue libre 39, du type 11 DF 04 par exemple. Les signaux de commande du transistor 38 sont appliqués sur sa grille depuis une entrée 40, du type coaxial par exemple. Cette grille est également reliée à la masse par une résistance 41 , de 200 ohms par exemple. La tension de commande appliquée sur l'entrée 40 vient faire varier la conductance du transistor 38 qui, compte tenu des valeurs des éléments et des tensions, est utilisée dans sa zone de résistance variable. Cette tension de commande se présente sous la forme d'une rampe de tension variant de 0 V à 6 V pendant la durée prévue pour la variation du gain souhaité pour le photomultiplicateur 1 , c'est-à-dire la période de temps prévue pour détecter le signal lumineux correspondant dans l'exemple décrit à la rétrodiffusion du flash laser.The primary winding 26 is supplied by a bias voltage, of +80 volts for example, filtered by a resistor 35, of 10 Ω for example, and two capacitors 36 and 37, of 22 microfarads and 0.1 microfarad for example, connected to ground. The other end of this primary winding is connected to the drain of a field effect transistor 38, of the IRF 530 type for example, the source of which is connected to ground. This primary winding is also shunted by a freewheeling diode 39, of the type 11 DF 04 for example. The control signals of the transistor 38 are applied to its gate from an input 40, of the coaxial type for example. This grid is also connected to ground by a resistor 41, of 200 ohms for example. The control voltage applied to the input 40 varies the conductance of the transistor 38 which, taking into account the values of the elements and the voltages, is used in its variable resistance zone. This control voltage is in the form of a voltage ramp varying from 0 V to 6 V during the period provided for the variation of the gain desired for the photomultiplier 1, that is to say the period of time provided for detect the corresponding light signal in the example described in the backscattering of the laser flash.
Dans ces conditions, sous l'effet de cette rampe de tension la résistance du transistor 38 diminue linéairement et provoque une variation de courant dans le primaire 26 du transformateur 25, ce qui amène des variations de tension sur les enroulements secondaires 27 et 28, qui sont transmises aux dynodes d3 à d7. Les modifie :ions de différence de potentiel au niveau de ces dynodes par rapport à la répartition normalement obtenue par le réseau de polarisation introduisent des variations de gain locales qui permettent de faire varier de manière continue le gain du tube photomultiplicateur depuis une valeur minimale jusqu'à la valeur nominale. Cette variation peut atteindre une valeur supérieure à 90 dB sur une durée qui peut descendre à une valeur aussi petite que 50 ns. En outre cette variation de gain n'entraîne pas de variation notable du temps de transit des électrons dans le tube photomultiplicateur et permet donc de respecter l'échelle des temps du signal lumineux reçu et de procéder à des mesures correctes de durées.Under these conditions, under the effect of this voltage ramp, the resistance of the transistor 38 decreases linearly and causes a variation of current in the primary 26 of the transformer 25, which brings variations in voltage on the secondary windings 27 and 28, which are transmitted to dynodes d3 to d7. Modify them: potential difference ions at these dynodes compared to the distribution normally obtained by the polarization network introduce local gain variations which make it possible to continuously vary the gain of the photomultiplier tube from a minimum value up to at face value. This variation can reach a value greater than 90 dB over a period which can drop to a value as small as 50 ns. In addition, this variation in gain does not cause any notable variation in the transit time of the electrons in the photomultiplier tube and therefore makes it possible to respect the time scale of the light signal received and to carry out correct duration measurements.
En résumé ce montage permet parfaitement de mesurer des signaux lumineux de très grande dynamique, supérieure à 90dB par exemple, sur des durées très courtes, 50 ns par exemple. Il est parfaitement adapté en particulier à la détection des échos lumin≈ux provenant de la rétrodiffusion d'une impulsion laser envoyée sur un .urface liquide, par exemple la surface de la mer, pour sonder la masse liquide qui s'étend sous cette surface et détecter les objets immergés sur les fonds marins. In summary, this assembly makes it possible to measure light signals of very high dynamics, greater than 90dB for example, over very short durations, 50 ns for example. It is perfectly suited in particular to the detection of lumin≈ux echoes coming from the backscattering of a laser pulse sent on a liquid surface, for example the surface of the sea, to probe the liquid mass which extends under this surface. and detect objects submerged on the seabed.

Claims

REVENDICATIONS
1. Procédé de commande du gain d'un tube photomultiplicateur pour obtenir une réponse linéaire sur une dynamique très importante pendant une durée très courte et sans faire varier sensiblement le temps de transit des électrons à l'intérieur de ce tube, caractérisé en ce que l'on polarise certaines des dynodes intermédiaires (d3 - d7) du tube (1) par l'intermédiaire d'un transformateur (25) à très large bande passante et faiblement amorti; ce transformateur étant lui-même alimenté par une rampe de courant sensiblement linéaire et les autres dynodes étant polarisées par un réseau résistif (9 - 18) connu.1. Method for controlling the gain of a photomultiplier tube to obtain a linear response over a very large dynamic range for a very short period of time and without significantly varying the transit time of the electrons inside this tube, characterized in that some of the intermediate dynodes (d3 - d7) of the tube (1) are polarized by means of a transformer (25) with very wide passband and weakly damped; this transformer itself being supplied by a substantially linear current ramp and the other dynodes being polarized by a known resistive network (9 - 18).
2. Procédé selon la revendication 1 , caractérisé en ce que l'on utilise un transformateur comportant un enroulement primaire (26) alimenté par la rampe de courant et deux enroulements secondaires (27, 28) destinés à polariser séparément deux groupes de dynodes intermédiaires.2. Method according to claim 1, characterized in that a transformer is used comprising a primary winding (26) supplied by the current ramp and two secondary windings (27, 28) intended to separately polarize two groups of intermediate dynodes.
3. Procédé selon la revendication 2, caractérisé en ce que le tube photomultiplicateur comporte 12 dynodes repérées respectivement d1 à d12, réparties entre une photocathode (2) et une anode (8) avec la dynode d1 située du côté de la photocathode, et que l'on polarise avec le premier enroulement secondaire (27) les dynodes d3 et d4 et avec le deuxième enroulement secondaire (28) les dynodes d5 à d7.3. Method according to claim 2, characterized in that the photomultiplier tube comprises 12 dynodes marked respectively d1 to d12, distributed between a photocathode (2) and an anode (8) with the dynode d1 located on the photocathode side, and that the dynodes d3 and d4 are polarized with the first secondary winding (27) and with the second secondary winding (28) the dynodes d5 to d7.
4. Procédé selon la revendication 3, caractérisé en ce que l'on relie en outre les dynodes d4 et d7 au réseau résistif (9-18) et que l'on polarise la dynode d6 par un pont résistif (23, 30) relié aux bornes du deuxième enroulement secondaire (28).4. Method according to claim 3, characterized in that the dynodes d4 and d7 are further connected to the resistive network (9-18) and that the dynode d6 is polarized by a resistive bridge (23, 30) connected across the second secondary winding (28).
5. Procédé selon l'une quelconque des revendications 1 à 4, caractérisé en ce que l'on alimente le transformateur par un transistor à effet de champ (38) utilisé dans sa zone de variation de résistance. 5. Method according to any one of claims 1 to 4, characterized in that the transformer is supplied by a field effect transistor (38) used in its resistance variation zone.
PCT/FR1994/000901 1993-07-23 1994-07-19 Photomultiplier gain control method WO1995003623A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU72667/94A AU7266794A (en) 1993-07-23 1994-07-19 Photomultiplier gain control method

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR93/09104 1993-07-23
FR9309104A FR2708141B1 (en) 1993-07-23 1993-07-23 Method for controlling the gain of a photomultiplier tube.

Publications (1)

Publication Number Publication Date
WO1995003623A1 true WO1995003623A1 (en) 1995-02-02

Family

ID=9449572

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FR1994/000901 WO1995003623A1 (en) 1993-07-23 1994-07-19 Photomultiplier gain control method

Country Status (3)

Country Link
AU (1) AU7266794A (en)
FR (1) FR2708141B1 (en)
WO (1) WO1995003623A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7009162B2 (en) * 2002-11-12 2006-03-07 Baker Hughes Incorporated Photomultiplier power supply with primary and secondary transformer windings

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106406406B (en) * 2016-11-04 2017-09-29 绵阳市维博电子有限责任公司 A kind of steady voltage regulator circuit and for voltage-multiplying circuit control and stable circuit

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3557373A (en) * 1967-06-28 1971-01-19 Electro Gmbh & Co Method and circuits for regulating the gain of a photomultiplier for laser-telemetry apparatus
US4820914A (en) * 1988-01-20 1989-04-11 Vigyan Research Associates, Inc. Gain control of photomultiplier tubes used in detecting differential absorption lidar returns
US5051572A (en) * 1990-04-06 1991-09-24 Mcdonnell Douglas Corporation Photomultiplier gating circuit

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3557373A (en) * 1967-06-28 1971-01-19 Electro Gmbh & Co Method and circuits for regulating the gain of a photomultiplier for laser-telemetry apparatus
US4820914A (en) * 1988-01-20 1989-04-11 Vigyan Research Associates, Inc. Gain control of photomultiplier tubes used in detecting differential absorption lidar returns
US5051572A (en) * 1990-04-06 1991-09-24 Mcdonnell Douglas Corporation Photomultiplier gating circuit

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7009162B2 (en) * 2002-11-12 2006-03-07 Baker Hughes Incorporated Photomultiplier power supply with primary and secondary transformer windings

Also Published As

Publication number Publication date
FR2708141B1 (en) 1995-09-01
FR2708141A1 (en) 1995-01-27
AU7266794A (en) 1995-02-20

Similar Documents

Publication Publication Date Title
CN101946189B (en) Optical-electronic distance measuring device
EP2238471B1 (en) 3d active imaging device
JP2002368720A (en) Distance measurement device
FR2559282A1 (en) APPARATUS FOR THE AUTOMATIC CONTROL OF LANTERNS FOR A VEHICLE
FR2502792A1 (en) LASER TELEMETER
EP0016705A1 (en) R.F. stage with automatic gain control and receiver comprising such a circuit
WO2018050897A1 (en) Electronic circuit and time-of-flight sensor comprising such an electronic circuit
EP0234968A1 (en) Method for reading a photosensitive element consisting of a photodiode and a capacitor
WO1995003623A1 (en) Photomultiplier gain control method
FR2505100A1 (en) LASER DEVICE
FR2690577A1 (en) Method and device for compensating phase instabilities of the amplified wave by a microwave tube
FR2667200A1 (en) DEVICE FOR STARTING A HIGH FREQUENCY AND LASER LASER WITH APPLICATION.
WO1996004627A1 (en) Improvements relating to optical smoke detectors
FR2584548A1 (en) DEVICE FOR INCREASING THE DYNAMIC OF AN AMPLIFICATION CIRCUIT, IN PARTICULAR AN MLS RECEIVER ON BOARD
CA2044633A1 (en) Electron gun capable of firing groups of electrons in short duration pulses
FR2946190A1 (en) METHOD FOR DETECTING THE TYPE OF SPARK GENERATED BY A RADIOFREQUENCY IGNITION CANDLE COIL AND CORRESPONDING DEVICE
EP0032335A1 (en) High-power electrical signals generator
EP1966888B1 (en) High power electric pulse generator
EP0156725A1 (en) Optical reader working as a television screen reader and as a bar code reader
FR2668326A1 (en) AUTOMATIC FOCUSING DEVICE AND RELATED METHOD FOR VIDEO CAMERA.
EP1191350B1 (en) Optical sensor with controlled emission
EP0017596A1 (en) Low noise photoreceiver
WO2023275332A1 (en) Pulsed lidar with semiconductor optical amplifier controlled by a modulated signal
BE437879A (en)
FR2635914A1 (en) Method of powering a photomultiplier and power source for implementing this method

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AU CA US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LU MC NL PT SE

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: CA