Abstract: By using the initial control voltage or the subsequent control voltage corresponding to the type of the aperture to be set in an input scanning head, the maximum output current of a photomultiplier of an image reproducing system is regulated.

Abstract: A detector for use in optical measuring instruments such as a double-beam spectrophotometer, comprising a photoelectric element having a photosensitive surface and a beam mixer disposed adjacent the photosensitive surface for causing each of two alternate light beams to be projected evenly and uniformly onto the photosensitive surface of the photoelectric element thereby to eliminate errors which would otherwise be caused in the result of measurement due to local difference in sensitivity of the photosensitive surface of the photoelectric element. The beam mixer comprises a symmetrical pair of light diffusing plates so arranged as to form a roof-shaped configuration and a tublar body having one end opening closed by the pair of light diffusing plates and the opposite end opening closed by the photosensitive surface of the photoelectric element.

Abstract: Gain hysteresis exhibited by the photomultiplier detector of a single beam spectrophotometer is reduced by illuminating the detector and applying dynode voltage thereto during the normal "off" or "idle" interval of the spectrophotometer.

Abstract: Gain hysteresis exhibited by the photomultiplier detector of a single beam spectrophotometer is reduced by illuminating the detector and applying dynode voltage thereto during the normal "off" or "idle" interval of the spectrophotometer.

Abstract: A photomultiplier detector protection system and method utilizing a negative feedback loop to maintain the photomultiplier detector output below a predetermined output. The feedback loop comprises a comparator responsive to the photomultiplier detector output and also responsive to a predetermined limit signal. The comparator output is applied to a summing amplifier which also receives a voltage adjust signal. The output of the summing amplifier controls the output of a power supply which is in turn applied to the photomultiplier detector.

Abstract: A series regulated power supply arrangement for an image intensifier tube, comprises an oscillator circuit, a high voltage multiplier and an automatic brightness control (ABC) circuit. The ABC circuit includes a series regulator for producing a variable voltage to be supplied to the microchannel plate of the image intensifier tube. The series regulator comprises a junction power transistor having a load resistor connected to its collector. The junction of the collector and the load resistor is connected to one output terminal and the other end of the resistor is connected to a fixed, high voltage line derived from the oscillator circuit which is the second output terminal. A feedback amplifier is connected to the base of the transistor and one input of the amplifier is coupled to a tap of a potential divider coupled between one output terminal (CPI) and ground.

Abstract: An improvement for a photomultiplier tube having its cathode, dynodes and ode spaced apart within an envelope increases the tube's linear dynamic range capability. A constant and stable collection potential is maintained between the anode and the dynode nearest the anode. In one form a zener diode voltage source and serially connected resistor are used or a fixed voltage is appropriately connected separate and distinct from the dynode potential connected across the other dynodes and the cathode. Thusly modified, a light flux range of approximately eight orders of magnitude can be accommodated by the improved photomultiplier tube circuitry.

Abstract: An improved photomultiplier tube comprises an evacuated envelope having a faceplate extending across one end thereof. A photoemissive cathode is disposed on the interior surface of the faceplate. A support electrode having a centrally located aperture therethrough is spaced from the faceplate. An electron multiplier assembly is attached to the support electrode. A focusing assembly is disposed about the centrally located aperture in the support electrode on a side of the support electrode opposite the electron multiplier assembly. The focusing electrode assembly comprises an insulating member having a generally tubular body with an interior surface and an exterior surface and having a proximal end and a distal end. A top-cap, having a substantially U-shaped cross-section including a flat central base and two mutually parallel projections at the ends of the base, is attached to the distal end of the insulating member.

Abstract: Output current hysteresis exhibited by a multiple-dynode photomultiplier detector is reduced by inactivating one or more of the dynodes by shorting to the detector anode, and operating the detector with the reduced number of active dynodes while retaining the anode as the output current supply terminal.

Abstract: Microchannel plates having increased gain and significantly improved aging characteristics are provided by forming a thin film of a cesium compound on the channel walls. In an exemplary embodiment, a surface film of cesium hydroxide is applied to the interior wall surfaces of an MCP by saturating the plate with a solution of the compound, then allowing the solvent to evaporate. The cesium hydroxide residue on the walls subsequently is converted to cesium oxide by a high temperature bake.

Abstract: An electron multiplier, including an excitation means and collector, disposed in a high vacuum chamber and adapted to be coupled at its input to a charged particle analyzer is coupled through the vacuum chamber wall by a plurality of electrical feedthrough devices such that the excitation means is coupled to a high voltage power supply disposed outside the high vacuum chamber and the collector is coupled simultaneously through a capacitance coupling means and a resistance coupling means, both disposed within the high vacuum chamber, to an amplifier-discriminator and floating operational amplifier, respectively, both disposed outside the high vacuum chamber. The impedance offered by the capacitance coupling means is substantially lower than that offered by the resistance coupling to 10 nanosecond current pulses originating from single electron events.

Abstract: Scanning apparatus is disclosed for use in computerized axial tomography systems. The apparatus includes an assembly rotatable about an axis extending along a central opening defined therein, and means for positioning the body portion to be examined within the central opening so that the axis of assembly rotation is perpendicular to a plane passing through the bodily structures to be examined. A source of penetrating radiation is mounted on the assembly toward one side thereof and provides radiation in the form of a fan beam. Detector means for the radiation are positioned on the assembly opposite the source, enabling detection of radiation which traverses laterally and is not absorbed in the thin body section in which the aforementioned plane resides. Means are provided for rotating the assembly so that the fan beam impinges upon said body portion at a plurality of incident directions.

Abstract: In a spectrophotometer including a photomultiplier tube and an operational amplifier responsive to the current from the photomultiplier tube for generating a DC voltage proportional to light intensity, a method and means for simultaneously compensating for the dark current of the photomultiplier tube and the offset of the operational amplifier so that the output voltage of the operational amplifier is zero volts under dark conditions.

Abstract: In a spectrophotometer including a photomultiplier tube responsive to light for producing an analog current proportional to the intensity thereof, an analog-to-digital converter, a signal path from the photomultiplier tube to the analog-to-digital converter, the analog-to-digital converter producing a digital signal as a function of the analog current, and computer means responsive to the digital signal for generating a signal for compensating for the dark current of the photomultiplier tube, there is disclosed a method and means for reducing the dark current correction error by temporarily increasing the gain of the signal path during calculation of the value of the compensating signal.

Abstract: A depth mapping system is carried from an aircraft flying above the water. pulsed laser directs a pulse at a predetermined water area and a multi-apertured photomultiplier tube receives backscattered or reflected radiation signals from both the air-water interface and a submerged surface. A signal comparator simultaneously compares each of the reflected radiation signals against the air-water interface radiation signal and drives a CRT display which illustrates the depth of the reflecting surface over the predetermined area.

Abstract: An electron multiplier device comprises two superposed microchannel plates. At their common interface, the angle of the axis of the channels of the plates is on the order of from 25.degree. to 30.degree. so as to increase the number of optical reflections in the channels. The more reflections, the lower the optical feedback from the output of the multiplier. At least one of the plates comprises curved channels. The curvature of the channels is such that at the entrance and the exit of the multiplier the axis enclose a small angle of at the most 10.degree. with the normals to the faces of the plates.

Abstract: An original document reading apparatus has a photocathode on which an image of an original document is focused. An array of secondary electron multipliers are arranged for multiplying the photoelectrons emitted from the photocathode. A plurality of anodes face the secondary electron multipliers, and capacitors are connected between the respective anodes and ground. A common load resistor is connected to the respective anodes through series circuits each including two electronic switch arrays. A scanning circuit is used for opening and closing the series connected switches to sequentially connect the common load resistor to the anodes to scan them. An amplifier circuit is used for amplifying the output which is generated in the common load resistor.

Abstract: An electron multiplier which is formed by at least two microchannel plates which are arranged one above the other and which operate in the saturation mode.The second microchannel plate produces an output charge for each incident electron which depends on the electrical field in the vicinity of the input surface of said second plate. By suitable geometrical structure in the plate or by shaping the potential applied thereto, an electrical field is produced which varies from point to point on its input surface. The charge output thus contains information regarding the location of the incident electron.

Abstract: A power supply for a microchannel image tube. Microchannel plate voltage is controlled, to adjust tube gain, as an inverse function of screen current in an intermediate illumination range. In addition, the photocathode plate voltage is controlled as a function of screen current in a second illumination range. The said second illumination range including higher illumination values than said first range and the lowest illumination value in said second range is at least equal to the minimum illumination value in said first range.

Abstract: Minature video-type display comprised of an otherwise normal microchannel ate (MCP) image intensifier wafer tube which uses, instead of the normal input faceplate having a uniform photocathode, a video-driven one-dimensional electroluminescent array on the output surface thereof and an orthogonal one-dimensional photocathode array mounted on the inner surface thereof. The fiber optic faceplate contains vacuum feed-throughs for the cathode array elements.

Abstract: Gating apparatus for a static crossed field photomultiplier utilizes a gating electrode which is mounted in a position between the cathode and the rail electrode. The gating electrode is pulsed thus causing the cathode current to be either multiplied or diverted so as to modulate the current by shifting the cathode beam into and out of the dynode area where secondary amplification occurs.

Abstract: A device for detecting optical energy signals in an optical path is provi by combining a layer of photoemissive material overlying the optical path and a grounded first electrode positioned in electrical contact with the layer of photoemissive material; a second electrode is positioned in spaced, preferably parallel relationship from the first grounded electrode and a source of dc potential is connected across the electrodes. Upon the transmission of optical energy signals along the optical path, commensurate electrical signals are produced across a load resistance which is connected between the second electrode and the high potential side of the dc potential source. Alternatively the concept may be embodied in a photomultiplier responsive to signals in an optical path. In this embodiment a plurality of dynodes are positioned between the first and second electrodes, spaced at gradually increased distances from the layer of photoemissive material.

Abstract: An electron discharge tube comprising a plenum having therein a photocathode, an anode, a plurality of spaced apart dynodes, each having an input aperture and an output aperture, the dynodes arranged so as to concatenate electron emissions from the photocathode to the anode, and a conductive mesh overlying each input aperture, is improved by providing non-uniform openings in the mesh whereby relatively greater electrostatic shielding is provided for the dynode surface proximate to the output aperture of a preceding dynode.

Abstract: A metal layer deposited on a wafer opposite to the photocathode is brought to a potential which is at least equal to that of the photocathode. The wafer layer and screen layer form conductors for a biplanar wave-propagation line element having a characteristic impedance equal to that of an external propagation line. The shutter tube is provided with matched means for connecting the line element to the external line, a voltage signal being applied to the line element so that the screen layer is brought progressively to a higher potential than that of the wafer layer.

Abstract: 1. An electron multiplier comprising wall means of secondary electron emissive material defining a spiral passage, means for providing a current flow through said wall means to supply electrons for secondary emission, a resistance means provided in said wall means and connected in parallel across a portion of the spiral passage defined by said wall means to provide more uniform current multiplication along said passage length.

Abstract: A photo multiplier tube is connected through a wave shaping and coupling cuit to an evaluation circuit; to provide for simple evaluation, for example, in an integrator, the coupling and wave shaping circuit includes an amplifier and a limiter, preferably a Zener diode connected through suitable coupling resistors to the integrator. Switches are provided to close the circuit from the photomultiplier tube (PMT) to the integrator, connected with a photon emission event trigger circuit so that, under non-event producing conditions, the integrator is disconnected from the PMT to prevent evaluating and possibly indicating spurious dark current noise pulses.

Abstract: A photon-counting detector array utilizes a one-dimensional multiple element anode array is in proximity focus to the last plate of the microchannel array for collecting the electrons generated therein. A specific embodiment has 64 anode elements. A detector system is provided with separate charge amplifiers, and level discriminators for each anode element. The discriminator outputs can be serially read out to a digital computer. Alternatively or additionally, the discriminator outputs are accumulated in counters, and display electronics are provided which can include digital-to-analog converters for forming a display representative of the counts accumulated in each counter, and the total count accumulated in all the counters.

Abstract: A dynode assembly having a given length and a field electrode assembly having the same given length are disposed in a vacuum envelope. The dynode assembly is in a first plane parallel to and spaced from the longitudinal axis of the envelope and the field electrode assembly is disposed in a second plane parallel to and spaced from the axis in a direction opposite to the spacing of the dynode assembly. The dynode assembly receives on its input end input electrons produced by an input signal which may be either electrical or optical. The field electrode assembly is shifted along the axis with respect to the dynode assembly such that the output end of the field electrode assembly extends beyond the output end of the dynode assembly such that lines of equal potential between the two assemblies form an angle .theta. with the first and second planes.

Abstract: A detector array and method are disclosed in which plural sets of electrode elements are provided with each set comprising a plurality of linear extending parallel electrodes. The sets of electrode elements are disposed at an angle (preferably orthogonal) with respect to one another so that the individual elements intersect and overlap individual elements of the other sets. Electrical insulation is provided between the overlapping elements. The thus configured detector array is exposed to a source of charged particles which in accordance with one embodiment comprise electrons derived from a microchannel array plate exposed to photons. Amplifier and discriminator means are provided for each individual electrode element. Detection means is provided to sense pulses on individual electrode elements in the sets, with coincidence of pulses on individual intersecting electrode elements being indicative of charged particle impact at the intersection of the elements.

Abstract: A detachable high-speed optoelectronic sampling head for use with an electron multiplier includes a housing having an evacuated chamber with a pair of transparent windows. Light to be detected is directed to the first window to a photoemissive strip spaced from a ground plane. The photoemissive strip comprises a microstrip, and the housing has high frequency feedthrough means for applying sampling potentials between said photoemissive strip and ground plane. A phosphor layer is provided on the other window in the chamber, and photoelectrons emitted from the photoemissive strip are directed through the ground plane to the phosphor layer.

Abstract: The specification discloses a voltage supply system particularly adapted for use as an automatic brightness control for an image intensifier tube. The system includes a power oscillator for applying a constant A.C. voltage to a first multiplier which generates at least one constant D.C. voltage for application to the screen of the image intensifier tube. A regulator circuit includes a low power oscillator which generates a control A.C. signal and which further includes circuitry responsive to the screen current of the image intensifier tube for varying the amplitude of the control A.C. signal. The frequency of the control A.C. signal is substantially greater than the frequency of the constant A.C. voltage. A bilateral attenuator receives the constant A.C. voltage and is operable in response to the control A.C. signal for varying the amplitude of the constant A.C. voltage. A second multiplier is connected to the output of the attenuator for generating a variable D.C.

Abstract: A picture element array image intensifier tube display device and system providing image analysis and processing schemes for an image in either direct or remote view. The picture element array comprises an array of electrically isolated parallel photocathode stripes that are adjacent and orthogonal to a microchannel plate input electrode array of electrically isolated parallel metallic stripes which have differential bias voltages selectively switched thereacross in some selective scan mode wherein said bias voltages are varied according to image analysis and processing schemes in a feedback circuit.

Abstract: A picture element array image intensifier tube display device and system providing image analysis and processing schemes for an image in either direct or remote view. The picture element array comprises two in-line microchannel plate (MCP) electron multipliers having an array of electrically isolated parallel output electrode stripes on a first MCP that are adjacent and orthogonal to a second MCP input electrode array of electrically isolated parallel metallic stripes. The input and output electrode array stripes have differential bias voltages selectively switched thereacross in some selective scan mode wherein said bias voltages are varied according to image analysis and processing schemes in a feedback circuit.

Abstract: A glass electron-multiplying microchannel plate of lead-containing glass is mounted within a supporting rim of another glass. The plate is connected to the rim with a relatively low melting temperature solder glass and the rim is slotted at a number of points about its periphery. The slots extend completely through the rim and partially into the connecting solder glass to protect against fracturing of the assembly during treatment thereof in reducing atmospheres.

Abstract: A circuit device for electron multipliers, especially photomultiplier tub in which the amplification is varied by switching the number of active dynodes. Sensitivity ranges from diode-mode up to a multiplier with full number of dynodes. The signal is taken from the last active dynode, and from the cathode in diode-mode. Any switchable dynode is provided with its own load resistor inserted between the relevant dynode and a dynode voltage divider. An amplifier connected to the last active dynode and to the dynode voltage divider provides a feedback that compensates for voltage drops at the next lower dynodes due to the finite impedance of the dynode voltage divider. The circuit device features fast signal risetime, high linearity and wide dynamic signal range together with high DC-current capability and clean transient response. Applications are transient-spectrophotometers where high signal-to-noise ratios are needed, accurate pulse-height-analysis, etc. The device may be constructed as a self-contained unit.

Abstract: A vacuum tube photodetector includes a planar photocathode, a parallel high voltage accelerating mesh, and a planar output anode positioned adjacent to and spaced from the mesh. The anode and mesh are connected to the inner and outer concentric conductors of a high frequency coaxial transmission line coupled to a load or output device. The high voltage preacceleration of electrons by the mesh and the small mesh to anode spacing provide a significant reduction of electron transit or pulse rise time compared with known two element biplanar photodiodes. In addition, the vacuum seal between the anode and mesh is positioned adjacent the anode-mesh gap which greatly reduces pulse decay time and undesired reflections. The mesh and anode are at the same potential to eliminate the usual high bias voltage between inner and outer coaxial photocathode and anode electrodes of the biplanar tube, as well as a coaxial coupling capacitor.

Abstract: A direct current power supply circuit for a photomultiplier tube comprises a step-up transformer with a secondary winding connected to rectifier means feeding output terminals. The primary winding in series with a transistor switch is connected across a d.c. supply source and the switch is controlled by pulses from a pulse generator which is switched on to produce pulses and hence to switch current in the primary winding when a control signal opens a gate in a feedback circuit of the pulse generator. The control signal is derived from the photomultiplier circuit and the circuit operates with the gate opening and closing as necessary to obtain the required voltage. The control signal may be derived from across an anode resistor of the photomultiplier tube or across a resistor in series with the dynode resistor chain according to the characteristics required.

Abstract: This invention relates to an improved system for regulating the gain of a photomultiplier tube, and was designed for use with the photomultiplier tubes of a GeMSAEC fast analyzers. It has the following advantages over the prior system: noise is virtually eliminated; sample analysis can begin after 3 to 4 revolutions of the rotor; fluorescent and light scattering solutions can be used as a reference; and the reference solution can be in any cuvette on the rotor.

Abstract: An electromagnetic radiation detector including a collimating window, a cathode member having a photoelectric emissive material surface angularly disposed to said window whereby radiation is impinged thereon at acute angles, an anode, separated from the cathode member by an evacuated space, for collecting photoelectrons emitted from the emissive cathode surface, and a negatively biased, high transmissive grid disposed between the cathode member and anode.

Abstract: The invention relates to a noctoviser comprising an image intensifier tube and a cascade high-voltage generator in which the intensifier tube is connected to the output of the high voltage generator via a parallel connection of a resistor and an avalanche diode.

Abstract: An improved image dissector camera tube system for improving the signal-to-noise ratio in which the aperture plate of the image dissector has a plurality of apertures, the apertures individually biased by an electronic control network to accomplish a Hadamard encoding of the electron image.

Abstract: A single photomultiplier tube having four sensing areas each of which produces its own independent electrical signal that is related to the quantity of sensed matter that impinges on its area.

Abstract: A device for digitalizing oscilloscope traces of fast transient signals is rovided in which a plurality of channel electron multipliers are arranged with their cathodes in a coordinate array in the path of a cathode ray beam such that the trace of the beam thereacross energizes those channel electron multipliers in the path of the oscilloscope trace. These multipliers remain energized until their anodes and associated anode circuits are scanned by a digital indexing device in a predetermined raster, synchronized with the oscilloscope, by which the respective coordinates of the energized multipliers are determined and stored in a memory so that the trace can be reproduced at any given time for subsequent analysis.

Abstract: A means is provided for reducing gain shifts in multiplier tubes due to varying event count rates. It includes means for limiting the number of cascaded, active dynodes of the multiplier tube to a predetermined number with the last of predetermined number of dynodes being the output terminal of the tube. This output is applied to an amplifier to make up for the gain sacrificed by not totally utilizing all available active stages of the tube. Further reduction is obtained by illuminating the predetermined number of dynodes with a light source of such intensity that noise appearing at the output dynode associated with the illumination is negligible.

Abstract: An electronic sampling head comprising a housing having a path for impinging radiation, a photoemissive element positioned across said path, photoelectron ejection means positioned in proximity to said photoemissive element, means for applying ultrashort sampling potential differences between said photoemissive element and said photoelectron ejection means for accelerating photoelectrons emitted by said photoemissive element in response to said incident radiation, and means for detecting said photoelectrons all resulting in the capability of detecting high-speed radiation phenomena with waveform fidelity.

Abstract: A light impact on the photocathode of a photomultiplier is localized by defocusing the beam of emitted photoelectrons, sweeping the surface of the photocathode by means of a localized electric field which is located in the vicinity of the photocathode and by measuring the time which elapses between the instant of commencement of sweeping of the photocathode surface and at least one change of sign of the anode signal.