DE2223288A1 - Pyroelectric photolatode for image pickup tubes - Google Patents

Description

P A R [S 8e / Frankro Loh

ijor sign: T 1 183

■ Pyroelectric ^ Phobokafcode stir to take picture

The invention embodied a pyro-electric phobuluibode for: Fei'nfjohbi Ldaufnähmei'öhren, the mib V / ärmesbrahlung, work in particular with infrared radiation.

Such photocathodes are essentially composed of one thin Sohichb an Eöo'llermaterials, then one of Solner I'eripurabur dependent aponbane elekbrinche Poiariüabion having.

At. This kind of phoboca soil is perpendicular to the. ' Area of the photocathode directed component of the electrical polarization for the generation of the image signal unused ♦

Lei / Gl

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Vain on the photokatocle generated radiation reffecting; thereupon a Teinperaturrellof, which as a result of the previously specified Eigonsohaft through an electrical polarization relief is expressed, and consequently by a relief of electrical charges on a surface of the photocathode, the other surface with an electrically conductive coating is covered, because the radiation is permeable and is kept at a fixed potential during operation.

On the facilities Eiir scanning of such Photo! sung; these facilities arise largely aufj dtM.i state of the art and are therefore for the Krfinduη g η i t we se ti 11 i.

En iioL merely remembered that the scanning of this Photocathodes with the help of an electron beam (Lobestrahl ü) takes place, which is the area of the photocathode, on which the respective lacquers appear, ρ unkt v / ei se scan t,

The thermal conductivity of the photocathode plays an essential role Holle for the image resolution obtained: A photo cathode, which have a large thermal conductivity in parallel its area (.; o i ti lohe heat ability), namely does not allow a good resolution to be achieved, because the theriiischo state of each point is a result of it this thermal conductivity is essentially due to the thermal Condition of the neighboring points can be influenced. Would have a high lateral electrical conductivity, albeit to a lesser extent, a similar effect.

In the case of the photocathodes of a known type, for example consist of a triglycine sulfate single crystal (TGS),

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is there ο dissolution because of the thermal conductivity of this Hatcn ^ ial »limited to a few points per millimeter.

The object of the invention is to create a pyroelectric solion photocathode with significantly improved resolution.

]) The photocathode according to the invention consists essentially of Ii above from a mosaic of pyroelectric Klerneuton, which are separated from each other and on a carrier with less lateral thermal conductivity attached bind.

X) j (! I.; E] /. Icmonte are directed in such a way that they have components of the .spontaneous electrical polarization in the direction of their]) icke, which all have the same Hi.ohtun /! ¹ vertical (! Lit fsu the surface of the deceiver have «Em protrudes from itself that these components have as high a value as possible and must be essentially the same.

The invention is illustrated by way of example with reference to the drawing described. Show in it:

I ¹ Ig. 1 is a perspective view of a portion of a photocathode according to the invention;

Fig. 2. a section through the photocathode of Fig. 1 and

Pig. 3 is a sectional view of another embodiment the photocathode according to the invention.

In the drawing, for the sake of clarity, the thicknesses of the various components of the photocathode are not to scale shown.

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Fig. 1 shows a section of a pyroelectric photocathode with elements 1 from a pyroelectric Material arranged on a carrier 4 previously J-coated with an electrically conductive layer has been, which is transparent to the incoming radiation and is covered with a layer 2, which the incoming Radiation, for example infrared radiation, is absorbed. The pyroelectric elements 1 are with With the help of an IQebstoffilms 5 attached to the layer 2. In the case of such pyroelectric photocathodes, the absorbing layer 2 should generate the temperature increase, on which the operation of the photocathode is based, if the material forming the elements 1 is itself for this radiation has an absorption capacity which is insufficient to cause this increase in temperature.

In various known embodiments, this layer is applied to the free surface of the elements 1, if the radiation arrives from this side, or on the surface of the support 4 that is in contact with the layer 3 standing surface is opposite. Naturally can in general all known variants with regard to the position of this layer in the case of the one described here Photocathode can be applied.

Fig. 2 shows a section through the photocathode of Fig. 1 along the line a-a. In the one shown in FIG For example, the right arrow represents the incoming radiation and the left arrow the electron beam.

The division of the photocathode into separate pyroelectric ^ Elements reduces the lateral thermal conductivity and the lateral electrical conductivity, thereby reducing the aforementioned disadvantages can be avoided.

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The photocathodes described can be produced by one of the known methods. For example the procedure for the embodiment shown in Fig. 3 is as follows:

A film 4 of very small thickness (a few microns) made of an insulating material is clamped in a frame, for example a plastic material, prepared with low thermal conductivity. Because it is It is essential that the film 4 has a low thermal conductivity when the disadvantages mentioned above known photocatoden should be avoided.

This slide is on one side with an electric conductive layer 3 coated, which is used for the ankorainemde Radiation is permeable. This layer, for example made of gold., has a thickness of a few

hundred angstroms. On top of this layer is a thin Foil made of a pyroelectric material, for example the aforementioned TGS, with a thickness of about applied twenty microns. This foil is on the gold layer with an adhesive film 5 of one to two microns Thickness glued on, for example an adhesive based on cyanoacrylate methyl, such as the 910 Adhesive from Eastman.

The TGS film is then made according to one of the known Process engraved, for example by chalking the material forming the film with an aqueous solvent, after the sections that must be maintained to form the elements 1 through one of The coating 6, for example made of gold, which cannot be attacked by the solvent in question, has been protected.

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This coating, which is not absolutely necessary for the operation of the photocathode, is for this operation also not disturbing and can be retained on the finished photocathode, as shown in FIG is.

The elements 1 of the Pig embodiment. 3 have the shape of cuboid blocks with a square base of 50 idra sides that are separated by gaps of about ten microns,

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Claims (1)

Claims • f. Pyroelectric photocathode for image pickup tubes that use with the radiation emanating from the objects to be observed work out with a carrier, a layer an electrically conductive material that is transparent to the radiation, and with one on this layer applied pyroelectric material, characterized in that the pyroelectric material in the form of a Mosaic is formed from separate elements. ? .. Pyroelectric photocathode according to claim 1, characterized in that the elements have the shape of rectangular parallelepipeds with a square base of 50 µm on a side and 20 µm thick, which are separated from one another by gaps of the order of about 10 µm. 3. Pyroelectric photocathode according to claim 1 or 2 _S characterized by a radiation absorbing layer. 4. Pyroelectric photocathode according to any one of claims 1 to 3j characterized ,, that the elements on the the surface facing away from the conductive layer are covered with a metallic coating. 209849/0764 Blank page