Electron tube for the detection, memorizing and selection of light images

Claim 1

A method to store a sequence of images arriving at a fast rate, to then select one of these images, with a view to analysis, and to eliminate the other images, said method comprising the steps of: focusing the light images at the input of an image converting electron tube; converting the light images into electronic images in the form of packets of electrons moving in the vacuum within the tube; giving these packets of electrons, by the application of a low-amplitude, accelerating electrical field, a known speed of motion which is very low as compared with the speed of light; making the packets of electrons undergo a to-and-fro trip in the tube; creating, in a section of the tube, by means of a selection electrode, an electrical field controlled by a selection logic signal, said field having either a first value for which the electrons are pushed back by the electrode towards the interior of the tube, or a second value for which the electrons can go through the electrode, the selection logic signal being produced in synchronism with the arrival of a packet of electrons to be selected in the vicinity of the selection electrode, the instant of arrival being related to the speed of motion of the packets of electrons, and the selection being made during the return trip of the selected packet; and finally, producing, at the output of the tube, an electronic image by means of packets of electrons selected by the logic signal, and eliminating the non-selected packets of electrons.

Claim 2

A method to store a sequence of images arriving at a fast rate, to then select one of these images, with a view to analysis, and to eliminate the other images, said method comprising the steps of: focusing the light images at the input of an image converting electron tube; converting the light images into electronic images in the form of packets of electrons moving in the vacuum within the tube; giving these packets of electrons, by the application of a low-amplitude, accelerating electrical field, a known speed of motion which is very low as compared with the speed of light; making the packets of electrons undergo a to-and-fro trip in the tube; creating, in a section of the tube, by means of a selection electrode, an electrical field controlled by a selection logic signal, said field having either a first value for which the electrons are pushed back by the electrode towards the interior of the tube, or a second value for which the electrons can go through the electrode, the selection logic signal being produced in synchronism with the arrival of a packet of electrons to be selected in the vicinity of the selection electrode, the instant of arrival being related to the speed of motion of the packets of electrons, and the selection being made during the return trip of the selected packet; and finally, producing, at the output of the tube, an electronic image by means of packets of electrons selected by the logic signal, and eliminating the non-selected packets of electrons.

Claim 6

A method according to one of the claims 1 to 4, wherein the selection electrode is placed in a zone such that the transit time taken by the electrons to perform a to-and-fro trip from the photocathode to the selection grid is substantially the same for different energy levels of emission of the electrons when starting from the photocathode, in the range of probable emission energy levels of the photocathode.

Claim 7

A device for the temporary storage of light images and for the selection of one image among the stored images, said device comprising an electron tube including: an input section enabling the conversion of a light image into an electronic image in the form of packets of electrons; a storage section wherein the electrical fields are such that the electrons move at very low speeds as compared with the speed of light; a selection electrode taken to a potential that is capable of assuming one value or another under the control of a selection logic signal, one of the potential values enabling the electrons that come towards the electrode to be pushed back and the other potential value enabling the electrons to pass through the selection electrode; a means for the removal of the non-selected packets of electrons; an output section with a means to reconstitute an electron image from a selected packet of electrons; the selection logic signal being applied with a very precise temporal shift with respect to the instant of input of an image to be selected, the shift corresponding to the transit time of the packet of electrons from the input section to the storage section and, in the storage section, up to the vicinity of the selection electrode; and the selection electrode being placed on the input section side of the tube to enable the selection of a packet of electrons on its return trip.

Claim 8

A device for the temporary storage of light images and for the selection of one image among the stored images, said device comprising an electron tube including: an input section enabling the conversion of a light image into an electronic image in the form of packets of electrons; a storage section wherein the electrical fields are such that the electrons move at very low speeds as compared with the speed of light; a selection electrode taken to a potential that is capable of assuming one value or another under the control of a selection logic signal, one of the potential values enabling the electrons that come towards the electrode to be pushed back and the other potential value enabling the electrons to pass through the selection electrode; a means for the removal of the non-selected packets of electrons; an output section with a means to reconstitute an electron image from a selected packet of electrons; the selection logic signal being applied with a very precise temporal shift with respect to the instant of input of an image to be selected, the shift corresponding to the transit time of the packet of electrons from the input section to the storage section and, in the storage section, up to the vicinity of the selection electrode; and the selection electrode being placed on the input section side of the tube to enable the selection of a packet of electrons on its return trip.

Claim 11

A device according to one of the claims 7 and 8, comprising means to carry the selection grid either to a potential equal to that prevailing in the gliding zone or to a potential which is more negative than that of the photocathode, and means to reduce the decelerating field in the deceleration zone when a selected packet of electrons again crosses this zone after a to-and-fro trip in the tube, the reduction of the field being sufficient to permit the movement of the packet of electrons up to the output section of the tube.