DE1904331A1 - Device for observing the fluorescent screen of a particle beam device - Google Patents

Description

SIEMENS AKTIENGESEIISCHArT Munich, the

PA 68/3822

Device for observing the fluorescent screen of a particle beam device

It is a device for observing the fluorescent screen an electron microscope by means of a television camera using glass fiber optics known whose The ray entry surface on the microscope side has a fluorescent layer as a fluorescent screen and its beam exit surface an image-converting layer of a television tube wearing.

The invention relates to a device of this type and is characterized in that the image-converting layer forms the photocathode of a SEC-xföwpt tube. Such tubes are known per se. In their use according to the invention, they offer a corpuekularetrahlooptischer in the context of the transmission Pictures have two main advantages. One can be seen in it

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that SEC-xMiiia tubes have a very linear characteristic, below the representation of the dependence of the signal current with constant light irradiation of the entire target area on the Illuminance is understood. Compared to other l'erns, this is better with a "SEC-Z" £ feH & particularly good linearity the characteristic curve enables intensity measurements to be carried out with little error, e.g. of contrast levels in the electron microscopic image.

The other essential advantage of de® SEC ~ «8ä5üti> xj» in the context of the use according to the invention lies in the possibility of Batch operation over longer times. The image represented by a mountain of charges can last longer (in the order of magnitude of an hour) has been saved and integrated, since the type of target, the secondary electrons in this type of tube depending on the incident beam intensity generated, due to its low transverse conductivity, excludes a charge equalization during dark control, It is therefore possible, when using the device according to the invention, to also produce very dark images with a high resolution transferred and evaluated, so that the invention opens up the possibility of sensitive electron microscopic specimens to examine electron microscopically without the risk of their destruction with weak radiation.

Other favorable properties of this type of tube are its good sensitivity and its relatively small dimensions the tube and its affordable price. Also the inertia dear SEC-u & isijexflfc is negligibly small, so that not only, as described above, batch operation can take place over longer times, but also rapidly changing times Transferring operations.

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The glass fiber optics can consist of a single glass fiber layer, which forms the vacuum-tight seal of the electron microscope and / or the SEC-JOGEEBXäii tube; understandably it is in principle also possible to have a common

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Provide vacuum-tight housing for the microscope and what SEC-Töcfctararr and to arrange the glass fiber layer in this as a partition.

In the preferred embodiment of the invention, however, the glass fiber optic contains two glass fiber layers, of which the the first glass fiber layer carrying the fluorescent layer, the vacuum-tight seal of the electron microscope and the ! Photocathode wear the second layer of fiberglass to make the vacuum-tight Forms the end of the SEC-TKECHÖEC tube. This training the Fiber optics offer a number of beneficial operating options. Both of them can be seen during the television broadcast Glass fiber layers with the interposition of an immersion oil let them butt directly against each other. During the times in which no television broadcast is to take place, you can then remove the television camera and take photographs of the image on the fluorescent screen of the electron microscope naoli Create type of contact photography by placing photographic material against the outer surface of the first layer of fiberglass presses. These recordings have a particularly good resolution because of the disruptive scattering that is usually used Can cause glass windows in which the fiberglass layer does not occur. Depending on the format of the photographic material the diameter of the first glass fiber layer may differ from that of the second layer.

You also have the option of contact photography with one another, working with two layers of glass fiber embodiment of the invention, which is characterized in that between the two fiberglass layers at least one electronic

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Image intensifier with one input and one output Glass fiber layer is inserted such that the first glass fiber layer and the input-soitige glass fiber layer as well as the second fiberglass layer and the output side fiberglass layer with the interposition of an immersion oil.

Understandably, several electronic image intensifiers can also be used connected between the two glass fiber layers, it being expedient to also connect them to each other Contact standing inputs and outputs of the other image intensifiers through layers of fiberglass.

llan will see to it that the clashing Glass fiber layers have the same diameter. That does not mean in the case of the use of electronic image intensifiers necessarily that all diameters are the same, since image intensifiers are known in which the amplification is not solely by accelerating the electrons emitted from a photocathode and thus by increasing the energy of the individual electrons is achieved, but with those in addition by reducing the image generated in them relatively in addition to the input image, an increase in the radiance at the location of the image generated in them is caused. Vfie Practical tests have shown that it is advisable to use the fiber optic layer on the output side of the image intensifier half the diameter of the fiber optic layer on the input side, reducing the radiation density at the output side Layer is enlarged by a factor of 4.

As already stated, a major advantage is the use a SEG- ^ SUk-tube with an electron microscope ' in the possibility of batch operation over longer periods of time

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look. It can therefore be useful for television broadcasting very dark images for the scanning electron beam of the SEC-Mttxwni-Röhrc a dark control known per se, for example, from the technology of electron beam oscilloscopes to be provided when actuated or automatically in accordingly The time units measured by the image brightness use the scanning electron beam to scan the beam once on the target the agitator releases saved image.

The figure shows an embodiment of the invention. Of the electron microscope, only the final image tube 1 or the space for receiving a disk cartridge is shown. The end of the microscope is formed by the first glass fiber layer 2, which is inserted in a vacuum-tight manner into the end wall 3 and is connected to the table 4 of the microscope in a vacuum-tight manner. This first glass fiber layer 2 carries on its microscope-side surface the fluorescent layer 5 »which forms the actual fluorescent screen of the electron microscope and is covered with the reflective layer 6, which reflects the visible light emanating from the fluorescent layer 5 when irradiated in the direction of the second glass fiber layer 7, which reflects the Entrance of the SEC -iHfRg tube 8 forms. It can be seen that the two glass fiber layers 2 and 7 are inserted into the electronic image intensifier 9, which has the glass fiber layer 10 on the input side and the glass fiber layer on the output side. The glass fiber layers 2 and 10 as well as 7 and 11 have the same diameter and are composed of immersion oil with thin layers 12 and 13 in between.

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The fiberglass layer 7 carries the photocathode H of the tube 8, while the input gas-side fiberglass layer 10 the Photocathode 15 of the image intensifier 9 carries. The from the photocathode 15 under the influence of the fluorescent layer 5

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Outgoing light radiation emitted electrons indicated by arrows are accelerated in the image intensifier 9 and directed onto the fluorescent screen 16 of the amplifier, the diameter of which in this example is smaller than that the photocathode 15 is.

The image intensified in this way passes through the transmission of the two glass fiber layers 11 and 7 to the photocathode 14 of the SEC-ISHAT * 8, so that this emits electrons. These electrons are accelerated, hit the target 17, which consists, for example, of KG1, and there trigger secondary electrons. The target 17 is placed on cathode potential by means of the scanning electrons EistxauI 18 v / elt; However, since the secondary electrons are dissipated via a resistor 19, the target is positively charged, so that the electron-optically obtained and amplified image is converted into a positive charge mountain on the target *

As soon as the scanning electron beam 18 irradiates the observed tunnel of the target again, the missing electrons are supplied so that a discharge to cathode potential takes place. This discharge process appears at the resistor 19 as a voltage pulse which is fed to the amplifier tube 21 via the capacitor 20 as an image signal.

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The sensitivity a »SEC-X ** xun, i.e. the number of triggered secondary electrons, allows the transmission of dark electron microscopic images.

In the multi-part arrangement shown in the figures; the parts can be connected to one another by flanges, preferably using resilient intermediate layers; it is

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also possible, the entire arrangement resiliently against the first To press glass fiber layer 2.

The invention extends to combinations of in various claims contained features.

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6 claims

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Claims (6)

tr «Schuta claims 1. Device for observing the fluorescent screen of a Corpuscular beam device, in particular an electron microscope, by means of a television camera using a glass fiber optic whose device-side beam entry surface has a fluorescent layer as a fluorescent screen and the beam exit surface of which carries an image-transforming layer of a television pickup tube, characterized in that that the image-converting layer forms the photocathode of a SEG camera tube. 2. Apparatus according to claim 1, characterized that the glass fiber optics contain two glass fiber layers, of which the fluorescent layer The first glass fiber layer supporting the vacuum-tight seal of the device and the second glass fiber layer supporting the photocathode forms the vacuum-tight seal of the SEC camera tube. 3. Apparatus according to claim 2, characterized in that the two glass fiber layers below Intermediate insertion of an immersion oil directly abut one another. 4. Apparatus according to claim 2, characterized in that between the two glass fiber layers at least one electronic image intensifier with an input-side and an output-side glass fiber layer of this type is inserted that the first fiberglass layer and the input-side fiberglass layer and the second fiberglass layer and the glass fiber layer on the output side butt against one another with the interposition of an inert oil. ΡΛ 9/715/5 -9- 009810/116 » SAO QKfGfNAi. 5. Device according to one of claims 2 to 4, characterized in that the jev / eils abut one another Glass fiber layers have the same diameter. 6. Device nnch one of claims 1 to 5, characterized marked that for television broadcast very dark images for the scanning electron beam of the SEC camera tube a known dark control is provided that when actuated or automatically in time intervals measured according to the image brightness releases the scanning electron beam for one-time scanning of the image stored on the target of the tube. ΡΛ 9/715/5 009810/116 » ι ^ ⁰ -. Blank page