Thomson-csf

Thomson Tubes Electroniques

Thales Electron Devices S.a.

Thales

Paul De Groot

Gerard Vieux

Yves Henry

Claude Weisbuch

Henri Rougeot

Bernard Munier

Francois Chareyre

Yves Beauvais

Guy Moiroud

Philippe Pradere

Andreas Koch

Francis Diaz

Daniel Boisson

Claude Weibuch

Bernard Munter

Gilbert-Rene Colomb

Garard Vieux

Michel Codron

The invention involves a radiological image detection system capable of cooperating with a scanning X-ray generator designed to produce X-ray radiation scanning a surface to be imaged. The scanning X-ray radiation irradiates, portion after portion, the surface to be imaged. The X-ray radiation from a portion carries a radiological image of the portion. The detection system comprises an image sensor which is stationary with respect to the scanning and which is dimensioned so as to be able to acquire an image of the surface to be imaged by the X-ray radiation from the portion. In addition, it comprises a device for limiting, at a given time, the acquisition of the image sensor to that of the image of the portion irradiated at that time.

Radiological image detection system for a scanning X-ray generator

The invention relates to the correction of distortion in an image intensifier comprising a primary screen intended for receiving first radiation and a secondary screen that emits second radiation that depends on the first radiation. The image intensifier furthermore includes means for projecting, onto the primary screen, a location test pattern produced using third radiation, and the secondary screen emits an image that depends on the location test pattern.

Distortion correction of an image intensifier

A radiological image detection system capable of cooperating with a scanning X-ray generator designed to produce X-ray radiation scanning a surface to be imaged. The scanning X-ray radiation irradiates, portion after portion, the surface to be imaged. The X-ray radiation from a portion carries a radiological image of the portion. The detection system includes an image sensor that is stationary with respect to the scanning and dimensioned to acquire an image of the entire surface to be imaged by the X-ray radiation from the portions. In addition, the detection system includes a mechanism to limit, at a given time, the acquisition of the image sensor to that of the image of the portion irradiated at that given time, the limitation mechanism being in synchronism with the scanning and in geometrical correspondence with the irradiated portion.

Radiological image sensing system for a scanning x-ray generator

To reduce phenomena of distortion in an image intensifier tube, it is planned to provide its input with a permanent test pattern. The image of the test pattern is then read in real time and a deduction is made therefrom of the correction to be made to an image transmitted and converted by this intensifier tube. To create a permanent test pattern, references are made on the intensifier tube, on its input window. As a variant, the references are produced by an auxiliary laser source that illuminates the cathode of the tube by the rear.

Device with an alteration means for the conversion of an image

Device for generating images by luminescence effect

Disclosed is a improvement in the fabrication of a scintillator, notably for the input screen of an X-ray image intensifier tube. According to the disclosure, the substrate on which a layer of scintillating material such as cesium iodide deposited in is made to grow is subjected to a treatment resulting in the formation of an alveolate structure or surface state, the consequence of which is the formation of thinner needles. The reduction of the mean diameter of the needles results in a improvement of the resolution of the device.

Method for the fabrication of a scintillator and scintillator obtained

The disclosure relates to image intensifier tubes of the proximity focusing type, wherein it especially concerns the positioning of a primary screen with respect to a slab of microchannels. An image intensifier tube comprises a sealed chamber containing a primary screen and a slab of microchannels. The slab of microchannels is fixed to the body of the chamber. According to one characteristic, the primary screen is fixed to the slab, from which it is kept at a distance by means of at least one insulating shim. The result thereof is greater precision and greater uniformity of the spacing between the primary screen and the slab of microchannels.

Proximity focusing image intensifier tube with spacer shims

An X-ray image intensifier tube includes a scintillator screen for converting ionizing radiation into light radiation or near-visible radiation, a microchannel array for achieving electron multiplication, and a photoelectrode positioned directly on an input face of the microchannel array. The input face of the microchannel array is coated with an electrically conductive layer which directly contacts the photocathode. The present design eliminates strict spacing requirements between the photocathode and the microchannel array and allows the photocathode and the microchannel array to operate at a single potential rather than requiring separate potentials. The requirement of a separate support for the scintillator screen is also obviated since the scintillator screen is formed on the input face of the microchannel array.

X-ray image intensifier tube having a photocathode and a scintillator

An input screen scintillator for an X-ray image intensifier tube. The tube includes light conductive cesium iodide needles formed on an electrically conductive substrate. Each needle is entirely coated with a material such as a metal or a semiconductor which reflects the light travelling within the needle toward the inside of the needle. This coating can enhance the efficiency and resolution of the image intensifier tube.

Input screen scintillator for an X-ray image intensifier tube and

The invention concerns an input screen scintillator for an X-ray image intensifier tube. This tube comprises light-conductive cesium iodide needles formed on an electrically conductive substrate. According to the invention, each needle is entirely coated with a material such as a metal or a semiconductor which reflects the light travelling within the needles and allows an identical potential level in the coating material as in the substrate towards the inside of said needles. The coating can enhance the efficiency and resolution of image intensifier tubes. The invention has applications in the field of X-ray imagery.

The invention concerns a manufacturing process of a photocathode for an image intensifier tube. According to this process, the photocathode is made within the tube by depositing a photoelectric material on a conductive substrate by vacuum evaporation. During this operation, the optical transparency of the deposit is checked by illumination of this deposit by a light source. According to the invention, this light source is located within the tube and is protected from the vapors of the photoelectric material. In the prior art, this light source was located outside the tube and the illumination of the deposit was not sufficient. The invention has applications in the field of image intensifier tubes.

Manufacturing process of a photocathode for an image intensifier tube

Disclosed is a method for the fabrication of an X-ray image intensifier tube. Before being introduced into the X-ray image intensifier, one of all the electrodes are entirely or partially covered with a layer of an orgainc polymer which is an electronic conductor of electricity and which has the property of reacting chemically with the alkaline metals deposited on the electrodes. Thus, the spurious illumination of the observation screen, due to the alkaline metals deposited on the electrodes during the preparation of the photocathode, is eliminated.

Method for the fabrication of an improved X-ray image intensifier tube,

A photocathode having internal amplification includes a first electrode adapted for receiving a first voltage, and for transmitting received photons. An absorption layer is disposed adjacent the first electrode and comprises a P-type semiconductor material having a forbidden band of sufficiently small width to cause photons received through said first electrode to be converted into electron-hole pairs. At least one ionization-induced electron multiplication layer is disposed adjacent the absorption layer. Each such multiplication layer comprises two layers of N-type semiconductor material having respectively two different compositions at an interface therebetween. The two different compositions at the interface cause the multiplication layer, when biased, to accelerate the electrons received from the absorption layer to a degree greater than the acceleration provided to the holes received from the absorption layer. A second electrode is disposed adjacent the multiplication layer and receives a second voltage to cause the photocathode to be biased. In addition, the second electrode transmits the accelerated electrons received from the multiplication layer. An emission layer is disposed adjacent the second electrode and comprises a material which produces negative electron affinity to cause the accelerated electrons received from the second electrode to be emitted into a vacuum.

Photocathode having internal amplification

A photocathode having a low dark current comprises a first layer consisting of P.sup.+ type semiconductor material which is transparent to all wavelengths of the light to be detected, a second layer consisting of P.sup.+ type semiconductor in which the forbidden band is of sufficiently small width to convert the photons of the light to be detected into electron-hole pairs, at least one intercalary layer located within the second layer and consisting of P-type or N-type semiconductor material for creating a potential barrier with respect to the second layer, the thickness of said intercalary layer being of sufficiently low value to permit the passage of electrons by tunnel effect with high probability but of sufficiently high value to stop the greater part of a hole current, a metallic electrode for biasing the photocathode in order to accelerate the electrons of the electron-hole pairs created within the second layer by the light, a last layer for reducing the energy-gap potential with respect to the second layer in order to emit into the vacuum the electrons which have thus been accelerated.

Photocathode having a low dark current

In one example of construction, a high-performance photocathode has the following structure:

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St. Ismier, France

Paul De Groot