DE1961368A1 - Electron tubes for recording very rapid light changes - Google Patents

Description

Dipl.-lng. Egon Prince Dr. Gertrud Hauser Dipl.-lng. Gottfried Leiser Patent attorneys Telegrams ι Labyrinth MOndia

Phone: 83 15 10 PMtadwdtkonk »MOndien 117078

8000 some 60,

Ernsbergerstrasse 19

1969

1961363

Our reference: T 803

THOMSON-CSP 101, Boulevard Murat, Paris l6e / France

Electron tube for recording

very rapid light changes (addendum to patent (patent application P 19 08 132 · .4))

The invention relates to an electron tube for recording very rapid changes in light. It aims in particular to improve the spatial Dissolution in such a tube.

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It

009836/1785

1961363

It is briefly recalled that these tubes are attached to their one end a photocathode receiving the light flux in the form of a narrow rectangular band and on the other end have a luminescent screen. Those of the photocathode under the action of the light current emitted electrons are accelerated to the screen by a deflection system in which they are in a Direction parallel to the short sides of the photocathode are bent. The voltage at the terminals of the deflection system changes over time in such a way that the deflection to which the electrons are subjected is from depends on the time at which they have approached the deflection system and that the image of the photocathode on the screen along an axis perpendicular to its longer side, which is generally called the time axis is being pulled apart *

Attention is generally directed to achieving good temporal resolution.

This result can generally be achieved by maximal acceleration of the electrons after exiting the Achieve photocathode (see, for example, the German patent application P 19 08 132.4 of the applicant from February 19, 1969).

In addition to the temporal resolution mentioned, the spatial resolution also plays a role in the quality of the recording of the image, that is, the resolution in the direction of the larger dimension of the image. About this goodness To improve one must remove the image distortion in this

direction 009836/1785

Reduce direction to a minimum, whereby these distortions are particularly annoying in the case, for example, that by suitable means a dispersion of the spectrum of the incident beam along this dimension has caused.

The invention relates to this spatial resolution.

In order to improve this resolution, according to the invention ™ suggested the electron beam emitted by the photocathode on its trajectory to the screen to converge. An electron lens centered on the point of convergence of the beam generates a punctiform image of a point of the photocathode on the screen.

The invention provides a tube for recording rapid changes in light with a luminescent screen at one end and a narrow rectangular band of photoemission material at the other end, the axis of which is perpendicular to the screen, and i with electrodes for accelerating the from the band under the action of the incident light bundle emitted electron bundle towards the screen and electrodes for impressing a time-variable deflection parallel to the shorter side of the band on the electron bundle, these electrodes being arranged between the band and the screen, characterized in that the photoemission band is applied to the dome of a sphere whose center point is on the axis between the spherical cap

and 009836/1785

and the screen is arranged that optoelectronic devices for generating the convergence of the electron beam are provided in a constriction point around the center of the sphere and that one around the axis rotationally symmetrical electronic converging lens is provided, the center of which corresponds to the center of the sphere coincides.

The invention is explained in more detail, for example, with the aid of the figures. Show it

Figure 1 is a schematic oblique view of the main components of a tube according to the invention,

Figures 2 and 3 axial sections of the arrangement shown in Figure 1 each along planes parallel to the larger Side or to the smaller side of the photocathode, and

Figures 4 and 5 show other embodiments of the invention.

In these figures, corresponding parts are denoted by the same reference numerals. With 1 the carrier is the Photocathode, with 10 the incident light beam, with 2 a luminescent screen, with 3 an accelerating electrode, with 4 and 4 'a pair of deflection plates and with 5 denotes an electron lens.

The support of the photocathode consists of a spherical cap made of transparent material with the axis XX ¹ . On the inner surface of this dome, the concave side of which aim

umbrella 009836/1785

Has screen 2, a narrow rectangular band 6 of emitting material is applied with the sides a and b which extend symmetrically on both sides of the axis XX '. This tape is named after a well-known Method applied by first making the inner surface of the dome opaque through a conductive layer 7 is made, leaving a band with the dimensions of the photocathode to be produced free, and by then applying the photoemissive material to the surface of that tape.

The accelerating electrode 3 comprises two mutually as well as to the larger side b of the emissive band parallel plates 3 'and 3 "· According to a feature of the invention, forming these plates on the side of the cathode 1 in two rounded portions 8, 8 ^1, which ^is concentric with the intersection circles of the dome 1 with the planes of these plates. It follows that the equipotential surfaces in the area between the dome 1 and the plates 3 ^! 'ind 3 ", which are as close to the dome 1 as it is to them with respect to the photocathode 6 applied acceleration voltage and are sufficiently close to each other so that they closely frame the same, have by and large the shape of spheres concentric to the spherical cap and that the plug path of the electrons emitted by the light from the photocathode 6 to the center C converge the ball to which the spherical cap 1 belongs, as shown schematically in the section of FIG. 2 for the two outermost plug tracks ΐ u nd T ^{1 is} shown.

As

009836/1785

As is known in the art of electron guns, it is not a question of precise focusing at point C ₃ but a constriction of the beam cross-section, which reaches a minimum value in the plane lying at point C perpendicular to axis XX '. In the plane perpendicular to the axis XX 'at point C, the electron trajectories of the bundle cross in the interior of an area whose dimensions are different from zero, which surrounds point C and is known as the constriction point or bundle knot. An electron lens 5 which is rotationally symmetrical about the axis XX 'is arranged around this constriction point. This lens produces a point image I on the screen from a point A of the photocathode. The hatched areas in FIGS. 2 and 3 show the electron beam which converges after the transverse deflection by the plates 4, 4 'to generate the image I of the point A.

The two plates 3 'and 3 "are fixed with a metal disc 13 connected, which is perpendicular to the axis XX 'and an opening 14 for the passage of the electron beam having. This disk limits the field of the plates 3 'and 3 "to the lens 5. The one opening is used in the same way 16 containing disk 15, which is kept at the same potential as the cylinder 5, as a shield between the lens 5 and the baffles 4, 4 '.

In another embodiment of the invention, the two plates 3 'and 3 "are through over their entire circumference a closed metal band connected, as in Figure 4

shown 009836/1785

shown. The accelerating electrode 3 then has the shape of a box, the side surfaces of which are f ^, fp, f ^, and fj, the surface opposite to the photocathode being fj. a slot 6 'and the opposite surface f. has a circular hole lh for the passage of the electron beam, which is centered on the axis of the photocathode 1.

The various electrodes are brought to a positive direct voltage potential with respect to the photocathode 6 by the voltage source S, the electrodes being connected to the voltage source in the manner shown in FIG which is also placed between the plates 4 and 4 ¹ via capacitors C. and Cp.

In a preferred embodiment of the invention (FIG 5) is a block of optical fibers 11 in the path of the incident bundle 10 in front of the photocathode carrier 1 and a block of optical fibers 12 at the exit of the tube opposite the image area behind the screen 2 to the |

Coupling of the same to the following stages (for example image intensifier or storage tube).

claims 009836/1785

Claims (5)

Claims (\ j Electron tube for recording rapid changes in light from an incident beam, which has a luminescent screen at one end and a narrow rectangular band of photoemission material at the other end, the axis of symmetry of which is perpendicular to the screen, and electrodes between the band and the screen to accelerate the the band under the action of the incident light beam emitted electron beam towards the screen and electrodes for impressing a time-varying deflection on the electron beam parallel to the shorter side of the band, characterized in that the photoemission band is applied to the dome of a sphere, the center of which is on the Axis is arranged between the dome and the screen, that opto-electronic devices for generating the convergence of the electron beam are provided in a constriction point around the center of the sphere and that one electronically symmetrical about the axis e converging lens is provided, the center of which coincides with the center of the sphere. 2. Electron tube according to claim 1, characterized in that the electronic-optical devices are characterized indicate that the acceleration electrode Which 009836/1785 1981368 which is closest to the photocathode, on the side of the dome for the electron beam to pass through has an opening which, in two planes, is parallel to the plane containing a major side of the belt is limited by two arcs, each concentric to the sectional arcs of the two levels with the Are calotte. 3. Electron tube according to claim 2, characterized in that the acceleration electrode lying closest to the dome consists of two flat plates which lie in the two parallel planes mentioned, wherein the two plates are brought to the same potential with respect to the tape. ¹ J. Electron tube according to one of Claims 1 to 3> characterized in that an arrangement of optical fibers is inserted into the path of the incident light beam in front of the photoemission band. 5. Electron tube according to one of claims 1 to 3 »thereby characterized in that at the exit of the tube after the luminescent screen an arrangement of optical fibers attached 1st. 009836/1785 Iff Empty soap