Optical waveguide apparatus for image transmission to an imaging device, and method for producing and for regenerating the optical waveguide apparatus

Abstract

The invention relates to an optical waveguide apparatus (1) for image transmission (2) to an imaging device, the optical waveguide apparatus comprising a glass fibre bundle (5), which is designed for image transmission (2) and is connected to two connection pieces (6), each of which is arranged at an end of the glass fibre bundle (5), and comprising waveguide cladding (7), which surrounds the glass fibre bundle (5) and extends between the connection pieces (6), wherein a heat-conducting device (8) has at least one heat conductor (9) which is provided for heating the glass fibre bundle (5) along the length thereof to a predetermined treatment temperature such that radiation-induced material defects in the glass fibre bundle (5) can be reduced by the heating to the treatment temperature. The invention also relates to a method for producing the optical waveguide apparatus (1) and to a method for regenerating the optical waveguide apparatus (1).

Description

[0001] Image guide device for image transmission to an image recording device and method for producing and regenerating the image guide device

[0002] The invention relates to an image guide device configured for image transmission, for example, from a reaction chamber to an image recording device, a method for manufacturing the image guide device, and a method for regenerating the image guide device to reduce radiation-induced defects. Applications of the invention include, for example, monitoring the combustion chamber of a fusion reactor, a nuclear fission reactor, or a neutron source, in medical technology, particularly radiology, or in the operation of MRI or X-ray devices.

[0003] It is well known that image guides are used to transmit images from environments with high radiation levels, which could cause damage or even destruction to unprotected electronic components. The image guide, made, for example, from flexible optical fibers, transmits the image captured by an unprotected objective lens at one end of the image guide in a room with harmful radiation to a camera located at the other end of the image guide. The camera can be housed in a radiation-protected environment, such as a cabinet. An example of image transmission from a tokamak reactor is described by B. Chektybayev et al. in "Rev. Sci. Instrum." 86, 053505 (2015).

[0004] Since the image guide is largely exposed to radiation without protection, interaction with high-energy photons, electrons, or neutrons can create defects in the structure of the image guide material. These defects cause, for example, discoloration and / or darkening of the originally transparent material of the optical fibers, significantly reducing light transmission through the image guide. CP Chrobak et al. describe in "Rev. Sci. Instrum." 83, 10E514 (2012) that by heating the optical fibers to a temperature of a few hundred degrees Celsius, the formation of radiation-induced defects can be at least partially reversed (regeneration of the image guide). To effectively restore the original light transmission of the defect-free or nearly defect-free material, it is important that the heating of the optical fibers is as uniform as possible across the entire length of the fibers.At the same time, this prevents material stress caused by temperature gradients, which could cause the optical fibers to become brittle and break, resulting in irreversible pixel loss in the image transmission. Due to these requirements, the heating of the optical fibers has so far been carried out in a vacuum furnace, which is designed specifically to heat the optical fibers as evenly as possible. The problem with this is that the entire image guide must be removed from its original location, typically in an ultra-high vacuum, which can only be flooded (e.g. ventilated) with great effort, and installed in the vacuum furnace. Since disassembly requires flooding the system in which the image guide is installed, regeneration of the image guide can only rarely be achieved.Depending on the location of the image guide, the conversion may require considerable effort or may even be impossible for human operators due to residual radiation, for example from activated metallic materials.

[0005] The object of the invention is to provide an improved image guide device, an improved method for manufacturing the image guide device, and an improved method for regenerating the image guide device, which avoid the disadvantages of conventional techniques. In particular, the image guide device should allow regeneration with reduced effort, shortened regeneration intervals, greater speed, and / or lower costs.

[0006] This problem is solved by the subject matter of the independent claims. Advantageous further developments are specified in the dependent claims and the description.

[0007] According to a first general aspect of the invention, the above object is achieved by an image guide device configured for image transmission to an image recording device. Preferably, the image guide device can be configured for image transmission from a reaction chamber to the image recording device. The reaction chamber can generally be a chamber, preferably an enclosed chamber, in which ionizing radiation occurs. Alternatively or additionally, ionizing radiation can occur along the length of the glass fiber bundle. The image guide device comprises a glass fiber bundle (fiber optics) configured for image transmission and connected to two connectors, each arranged at one end of the glass fiber bundle, and a conductor jacket enclosing the glass fiber bundle and extending between the connectors.For attachment to or in the reaction chamber on the one hand, and to the image recording device on the other hand, at least one of the connecting pieces can be equipped with a coupling component, such as at least one flange and / or at least one insulating element. Furthermore, the image guide device comprises a heating conductor device with at least one heating conductor (jacket heating conductor) designed to heat the glass fiber bundle along its length, preferably continuously along its entire length, to a predetermined treatment temperature such that radiation-induced material defects in the glass fiber bundle can be reduced by heating to the treatment temperature.

[0008] An image transmission from a reaction chamber to an image recording device means that an image of a scene in the reaction chamber is transmitted to an image recording device which is arranged outside the reaction chamber and, in particular, is not in direct contact with the reaction chamber. Therefore, the glass fiber bundle can be connected by means of the connecting pieces on one side to a lens device (optics) in the reaction chamber and on the other side to the image recording device, such as a camera or an image sensor. The individual fibers of the glass fiber bundle are connected at their ends to the connecting pieces in a strictly ordered manner so that the relative orientation of the fibers, i.e. of the pixels in the transmitted image, does not change. Pixels that are arranged next to one another on the lens device are also arranged next to one another on the image recording device.

[0009] The reaction chamber is preferably an enclosed chamber, for example, in whose interior images are to be taken. This could be, for example, the plasma combustion chamber of a fusion generator or a particle accelerator, or an operating room of such systems. These examples of reaction chambers have in common that, during operation, they sometimes generate significant amounts of ionizing radiation in their surroundings, which could damage or even destroy the image recording device. Due to the image transmission from the reaction chamber, the image recording device does not need to be located in or in the immediate vicinity of the reaction chamber and can, for example, be surrounded by a protective housing.

[0010] The fiber optic bundle is enclosed by the conductor sheath, which can consist of a flexible hose or a rigid, preferably deformable, tube. This protects the fibers of the fiber optic bundle from external influences such as contamination or mechanical stress. Furthermore, a fastening device can be attached to the conductor sheath to secure the image guide device at the installation site without stressing the fibers of the fiber optic bundle. However, ionizing radiation in the vicinity of the reaction chamber can penetrate the conductor sheath to the fiber optic bundle, causing material defects in the lattice structure of the fiber optic bundle, which lead to a deterioration in light transmission. These material defects are reversed by heating the fiber optic bundle.

[0011] The fiber optic bundle comprises a large number of glass fibers, whereby, depending on the design, several adjacent fibers can be combined to form fiber strands. The starting points of the individual fibers or fiber strands at one end of the fiber optic bundle are assigned to the end points of the respective fiber or fiber strand at the other end of the fiber optic bundle. In this way, the relative orientation of the image points is maintained during image transmission. A fiber optic bundle can consist of, for example, at least 10, at least 100, or at least 1,000, or up to several million individual fibers or fiber strands. The typical thickness of the fibers is in a range between 30 pm and 100 pm.

[0012] The at least one heating conductor extends along the length of the glass fiber bundle and advantageously allows for uniform heating of the glass fiber bundle. The heating conductor device therefore advantageously fulfills the function of the uniformly heating vacuum furnace used in the prior art for regenerating the glass fiber bundle. This allows the regeneration of the glass fiber bundle to be carried out directly at the location where the image guide device is used. A difficult and time-consuming conversion to the vacuum furnace can be dispensed with. The heating conductor preferably comprises a resistance heating conductor that can be coupled to a power supply. The power supply is preferably designed to be controllable. In this way, the reliability of adjusting the temperature of the heating conductor device can be improved.

[0013] The at least one heating conductor preferably comprises a conductive core encased in an electrically insulating material. The conductive core, which is made, for example, of constants, produces heat through its intrinsic electrical resistance, while the insulating jacket ensures that current flow from the heating conductor to electrically conductive materials in the surrounding area is prevented. A metal jacket can be provided on the outside of the electrically insulating material as an outer protective covering for the heating conductor. Alternatively, the heating conductor can comprise the conductive core without the insulation provided by the electrically insulating material if the heating conductor is arranged in an electrically insulated manner in the image guide device by other measures.

[0014] A further particular advantage of the image guide device is that the regeneration of the fiber optic bundle can be carried out more frequently and over shorter intervals than is the case with conventional technology, without substantially impairing the application of the image guide device. If the conventional regeneration method is used, in which the image guide must be removed from its place of use and installed in a furnace, there is little practical option other than to leave the image guide in place as long as it can be used effectively. The conversion to the furnace only takes place when the transmission of the image guide has already been reduced so much that further use is no longer acceptable, or when a general longer maintenance phase of the reaction chamber is pending. However, CP Chrobak et al. in "Rev. Sei. Instrum." 83, 10E514 (2012), it has been shown that it is advantageous to heat glass fiber bundles more frequently and for shorter periods of time, since in this way the occurrence of irreversible radiation damage in the glass fiber bundle can be avoided. This advantage can be better exploited with the image guide device according to the invention.

[0015] According to a second general aspect of the invention, the above-mentioned object is achieved by a method for manufacturing the image guide device according to the first general aspect or one of its embodiments. In the method according to the invention, the glass fiber bundle and the conductor sheath for receiving the glass fiber bundle are first provided. Subsequently, the glass fiber bundle is positioned inside the conductor sheath, and the two connecting pieces are provided for connection to the glass fiber bundle. Thereafter, the at least one heating conductor is positioned along the length of the conductor sheath. Finally, the connecting pieces are each connected to one of the two ends of the glass fiber bundle and the corresponding end of the conductor sheath.

[0016] An important advantage of the method according to the invention is that it allows the heating conductor to be aligned along the fiber optic bundle in such a way that a particularly uniform heat distribution along the fiber optic bundle can be achieved by the heating conductor. By positioning the fiber optic bundle inside the conductor sheath before positioning the heating conductor, it can be ensured that the heating conductor does not damage the fibers of the fiber optic bundle.

[0017] According to a third general aspect of the invention, the above-mentioned object is achieved by a method for regenerating the image guide device according to the first general aspect or one of its embodiments, in which the glass fiber bundle with the heating conductor device is heated to the treatment temperature in such a way that radiation-induced material defects in the glass fiber bundle are reduced by heating to the treatment temperature. Preferably, heating to the treatment temperature takes place in the range of 100°C to 300°C, in particular between 200°C and 250°C. Alternatively, a higher treatment temperature can be set, with the maximum treatment temperature being selected depending on the thermal tolerance of the components used, in particular the adhesive used to hold the fibers together.In particular, the treatment temperature is selected such that at the treatment temperature, outgassing from components of the image guide device, in particular the adhesive, is excluded or reduced to a negligible level.

[0018] Advantageously, the regeneration process according to the invention allows radiation-induced defects in the lattice structure of the glass fiber bundle to be reduced or even completely reversed. The temperature range chosen in practice for regenerating the glass fiber bundle depends in particular on the material composition of the glass fibers. Furthermore, the temperature range can be selected depending on the type of ionizing radiation that caused the defects in the lattice structure. For example, a Schott IG-163 glass fiber bundle exposed to high-energy neutrons and gamma radiation from nuclear decay can be regenerated at a temperature of 200 °C. The preferred temperature can be determined, for example, through simple tests or reference values ​​from the specialist literature.

[0019] According to a preferred embodiment of the invention, the at least one heating conductor runs along the outside of the conductor sheath and is in thermal contact with the conductor sheath, wherein the at least one heating conductor extends along the length of the conductor sheath, in particular the entire length of the conductor sheath. In this way, the heating conductor itself does not come into contact with the glass fiber bundle. Mechanical damage to the individual fibers caused by the heating conductor can advantageously be ruled out. Instead, the heating conductor transfers heat to the conductor sheath, inside which the glass fiber bundle is located. The heating conductor preferably extends continuously over the entire length of the conductor sheath. This improves the uniformity of the heat distribution inside the conductor sheath.The glass fiber bundle is located in an environment with a uniform temperature over its entire length, so that no temperature gradient develops along the length of the glass fiber bundle. Furthermore, this prevents individual fibers from overheating and thus being damaged by direct contact with the heating conductor. According to an alternative preferred embodiment of the invention, the at least one heating conductor is arranged together with the glass fiber bundle inside the conductor sheath and extends over the length of the conductor sheath, particularly preferably over the entire length of the conductor sheath. The advantage of this embodiment is that the heat from the heating conductor can be transferred directly to the glass fiber bundle without delay due to the additional mass of the conductor sheath.This design is therefore particularly suitable for applications where the temperature, and in particular the temporal temperature profile of the fiber optic bundle, must be controlled with great precision. This can be advantageous, for example, in the development and testing of fiber optic materials. Furthermore, the influence of the conductor sheath on the heat distribution inside the conductor sheath can be reduced. The material and geometric shape of the conductor sheath have only a minor influence on the heat distribution inside, allowing the shape of the conductor sheath to be better adapted to the external conditions.

[0020] In this embodiment, in particular during assembly of the heating conductor device, care is preferably taken to ensure that the fibers of the glass fiber bundle are not damaged and that the heating conductor is not excessively pressed against the fibers when the conductor sheath with the glass fiber bundle and the conductor sheath is moved or bent.

[0021] According to a further alternative embodiment of the invention, the at least one heating conductor can be embedded in the conductor sheath and extend along the length of the conductor sheath, in particular the entire length of the conductor sheath. This variant of the invention can have advantages with regard to the positioning and electrical insulation of the at least one heating conductor.

[0022] In a further preferred embodiment, the heating conductor device comprises a plurality of heating conductors, in particular two heating conductors, which extend along the length of the conductor sheath, in particular the entire length of the conductor sheath. The heating conductors are particularly preferably arranged on different, in particular opposite, sides of the glass fiber bundle. The heating conductors can, for example, be arranged opposite one another. Just one heating conductor, which preferably extends along the entire length of the conductor sheath, ensures a uniform temperature of the glass fiber bundle in the longitudinal direction and also in the circumferential direction of the glass fiber bundle. By providing two heating conductors in this embodiment, it can be contributed to further improving the uniformity of the heat distribution in the circumferential direction of the glass fiber bundle and / or increasing the reliability, e.g. due to a mechanical defect.

[0023] Advantageously, the two heating conductors can be arranged electrically connected in series and can be coupled to a power supply via two heating conductor connections at a common end of the glass fiber bundle, preferably the end facing the image recording device. In other words, the two heating conductors can be arranged electrically connected in series, wherein a first heating conductor extends from a first heating conductor connection at a first end of the glass fiber bundle to the second end of the glass fiber bundle and is connected at the second end of the glass fiber bundle directly or via a further heating conductor to the second heating conductor, which extends from the second end of the glass fiber bundle to a second heating conductor connection at the first end of the glass fiber bundle, wherein the heating conductor connections can be coupled to a common power supply.This embodiment of the invention has the advantage that the heating conductor connections are arranged together at the same end of the fiber optic bundle. Therefore, the connection to the power supply is only required at one end of the fiber optic bundle. Furthermore, especially when using heating conductors that are not separately electrically insulated, additional mutual electrical insulation of the heating conductors can be dispensed with due to the separate arrangement of the heating conductors on different sides of the fiber optic bundle. As an alternative to the aforementioned series connection, the two heating conductors can be electrically connected in parallel and connected to a power supply via two heating conductor connections.

[0024] In embodiments with a plurality of heating conductors, an even number of heating conductors can preferably be provided, wherein particularly preferably two of the heating conductors are electrically connected in series and equipped with the heating conductor connections at the same end of the glass fiber bundle and in particular all heating conductor connections are arranged at the same end of the glass fiber bundle.

[0025] The heating conductor device preferably has an additional heating conductor (connection heating conductor) on at least one of the connection pieces, which at least partially surrounds the connection piece and is in thermal contact with the connection piece. In this way, in addition to the conductor sheath, the connection piece is also brought to a uniform temperature, preferably to the same temperature as the conductor sheath. The individual heating conductors of the heating conductor device can be operated separately (adjustable and / or controllable) and / or can each be coupled to a separately assigned power supply. Additionally or alternatively, several heating conductors can be combined into groups that can be controlled jointly and / or operated via a common power supply.This avoids temperature gradients in the fiber optic bundle near the connector, allowing for the most efficient recovery of the fiber optic bundle's transmission properties. Furthermore, temperature-induced material stress in the fiber optic material, particularly near the connectors, can be avoided, resulting in embrittlement of the fiber optic material and potentially fractures of individual fibers.

[0026] If the two heating conductors are arranged electrically connected in series and the additional heating conductor is provided, according to a further advantageous embodiment of the invention, the two heating conductors can be electrically connected in series via the additional heating conductor. In this case, a first heating conductor extends from the first heating conductor terminal to the second end of the fiber optic bundle, where the first heating conductor is connected to the additional heating conductor, and the additional heating conductor is connected in series to the second heating conductor, which extends from the second end of the fiber optic bundle to the second heating conductor terminal.

[0027] Alternatively, particularly if the two heating conductors are arranged electrically connected in series and the additional heating conductor is provided, the two heating conductors can be directly connected in series and coupled to a power supply, and the additional heating conductor can be coupled to a further power supply. In this case, the temperatures at the respective image conductor ends and along the fiber optic bundle can be adjusted independently. Advantageously, this allows a uniform temperature to be set throughout the entire length of the fiber optic bundle, preventing uneven heating, which could, for example, lead to the loosening or burning of an adhesive or a locally inadequate bake-out temperature (undertemperature).

[0028] According to an advantageous embodiment, a method for producing an image guide device further comprises the step of positioning at least one further heating conductor such that it at least partially surrounds at least one of the connecting pieces and is in thermal contact with the connecting piece. For this purpose, the heating conductor can be shaped to fit the connecting piece before positioning, e.g., by bending the heating conductor around a mandrel that is adapted to the shape of the connecting piece. Preferably, a heating conductor material with elasticity is used. In order to bend the heating conductor into a shape that corresponds to the contour of the connecting piece, the mandrel used will usually have a slightly different shape than the connecting piece, so that when the heating conductor is removed from the mandrel, the somewhat elastic heating conductor springs into the correct shape.

[0029] The conductor sheath particularly preferably has a thermal conductivity of a metallic material. The thermal conductivity of metals is typically greater than

[0030] 15 W / (mK); for certain materials, it can be as high as several hundred W / (mK). The thermal conductivity of most non-metals is significantly lower. Due to the high thermal conductivity of the conductor sheath material, the heat from the heating conductor can be advantageously transferred to the fiber optic bundle with minimal delay. Furthermore, the conductor sheath itself is quickly brought to a uniform temperature, thus avoiding temperature gradients inside the conductor sheath.

[0031] According to a further embodiment, the image guide device further comprises at least one enveloping tube that evenly covers the conductor sheath and the at least one heating conductor laterally, in particular completely envelops them, and is designed to distribute heat from the at least one heating conductor to the conductor sheath. Preferably, the at least one enveloping tube has a thermal conductivity of a metallic material and / or is elastic. The at least one enveloping tube encloses the conductor sheath and contributes to a further improvement in even heat distribution. The at least one enveloping tube can be pulled partially or completely over the connecting pieces, so that a potentially uneven temperature gradient can be prevented, in particular at the transition points to the connecting pieces.

[0032] A single sheathing tube can be provided, making the construction of this embodiment of the image guide device relatively simple. Alternatively, multiple sheathing tubes, e.g., flexible tubes made of wire mesh, in particular copper, can be provided, arranged one above the other in a radial direction. Multiple sheathing tubes can be arranged one above the other directly adjacent to one another, or they can be separated from one another by intermediate layers. The single sheathing tube or one sheathing tube from the multiple sheathing tubes can be arranged between the at least one heating conductor and the conductor sheath, thereby advantageously increasing the heat-conducting surface to the conductor sheath.

[0033] If the heating conductor is arranged along the length of the glass fiber bundle on the outside of the conductor sheath, the sheath can press the heating conductor against the conductor sheath, thus improving constant thermal contact between the heating conductor and the conductor sheath. For this purpose, it is particularly advantageous if the sheath is made of an elastic material. If the sheath is also made of a material with the thermal conductivity of a metal, the sheath can help to transfer the heat from the heating conductor to the conductor sheath as evenly as possible. The sheath particularly preferably comprises a metal braid, for example, a hose made of a copper braid.

[0034] In a further embodiment of the invention, the steps of providing a sheathing tube which has a thermal conductivity of a metallic material and is elastic are provided, and the conductor sheath, the glass fiber bundle and the at least one heating conductor which is provided for heating the glass fiber bundle are covered with the sheathing tube, so that the sheathing tube laterally evenly covers, in particular completely envelops, the conductor sheath and the at least one heating conductor for distributing heat from the at least one heating conductor to the conductor sheath and the at least one heating conductor.

[0035] In a particularly preferred variant in which the method comprises covering the conductor sheath, the glass fiber bundle, and the at least one heating conductor with the sheathing tube, the method can further comprise the step of stretching the sheathing tube onto an auxiliary tube having an inner diameter that is larger than the outer diameter of the composite comprising the conductor sheath, the glass fiber bundle, and the at least one heating conductor. The conductor sheath, together with the glass fiber bundle and the at least one heating conductor, can then be positioned in the auxiliary tube. Finally, the auxiliary tube is withdrawn from the conductor sheath, together with the glass fiber bundle and the at least one heating conductor, while the sheathing tube remains on the conductor sheath, the glass fiber bundle, and the at least one heating conductor.

[0036] Advantageously, these additional process steps simplify the correct positioning of the sleeve on the heating conductor and the conductor sheath, and ensure that no components of the image guide device are undesirably displaced by the application of the sleeve. Furthermore, it is easier to cover a smooth auxiliary pipe with the sleeve than the uneven conductor sheath with the connectors and heating conductor. The sleeve could catch on the edges of the connectors, in particular, and possibly even be damaged, which could reduce the heat transfer provided by the sleeve.

[0037] Since the sheath is preferably elastic, it can be pulled over an auxiliary tube whose outer diameter is larger than the outer diameter of the conductor sheath with the heating conductor and the connectors. The sheath could, for example, be a hose made of a copper braid, the diameter of which can be increased by compressing the hose. During compression, the sheath is pushed together longitudinally. This slightly rotates the orientation of the copper fibers, shortening the length of the sheath but increasing its diameter.

[0038] The remaining components of the image guide device can then be pushed into the tube without obstruction and positioned so that one end of the sleeve is approximately where it will remain in its final position. This end is held in place, and the auxiliary tube is removed. This end of the sleeve remains in the specified position of the conductor sheath or connector. The remaining sleeve wraps evenly over the conductor sheath, the heating element, and the fiber optic bundle, without snagging on any edges and thus risking damage.

[0039] According to a further preferred embodiment, the image guide device further comprises at least one temperature sensor configured to detect the temperature of the image guide device. In particular, the temperature sensor can be configured to detect the temperature of the conductor sheath. The detected temperature can be used to adjust the heating conductor device to the desired temperature by means of a control system. This can be done manually by a human user or automatically by a controller.

[0040] For example, the power supply for the heating elements can include a control unit configured to receive temperature data from the temperature sensor and regulate the temperature of the heating elements using a proportional-integral-derivative (PID) loop. Alternatively, the control or regulation can also be performed by a software module.

[0041] Preferably, the heating conductor device is configured to heat the glass fiber bundle to the treatment temperature in the range of 100 °C and 300 °C, in particular 200 °C and 250 °C, which correspond to the regeneration temperatures of typical glass fiber bundles.

[0042] The method for producing the image guide device can accordingly, according to one embodiment, further comprise the step of attaching at least one temperature sensor configured to detect the temperature of the image guide device. In variants in which the image guide device comprises a sheathing tube, a temperature sensor can preferably be positioned between the conductor jacket and the sheathing tube. In a further embodiment, the image guide device further comprises an additional heating device with a temperature-controlled working gas configured to heat at least one ambient component of the image guide device. This embodiment is preferably provided when the image guide device is operated at ambient pressure, i.e., not in a vacuum.For example, the auxiliary heating device can be used to heat the working gas, such as nitrogen, to a temperature close to the temperature of the conductor sheath. This gas can be used to heat components and parts in the vicinity of the image guide device, especially when these components interact with the image guide device.

[0043] For example, the working gas can be used to heat the optics to which the image guide device is connected on the reaction chamber side. In many cases, the fiber optic bundle is joined to the connectors by means of an adhesive bond. When the image guide device heats up, these adhesive bonds can potentially outgas. These gases could condense on the optics and thus cause contamination or clouding of the optics. Heating the optics to a temperature close to the image guide temperature can prevent or at least reduce this condensation. Alternatively or additionally, the flowing working gas can be used to keep unwanted adhesive vapors away from light-transmitting surfaces in the beam path, particularly from the entrance / exit window of the fiber optic bundle and / or the optics. The heated working gas can absorb the gases from the adhesive bond and be extracted by a pumping device.

[0044] The method for regenerating the image guide device can accordingly, according to one embodiment of the invention, further comprise the steps of heating the working gas with the additional heating device to a temperature in the range of 100°C and 400°C, in particular of 200°C and 300°C, and of tempering, in particular flowing, at least one environmental component of the image guide device with the heated working gas.

[0045] In a further embodiment, the image guide device can be equipped with at least one transparent plate, preferably made of glass, in particular quartz glass, which is arranged on the reaction chamber side adjacent to the input / output window of the glass fiber bundle and / or the optics in such a way that the input / output window and / or the optics are protected from fogging during the annealing process. Alternatively or additionally, at least one transparent plate, preferably made of glass, in particular quartz glass, can be arranged on the image recording device side adjacent to the input / output window of the glass fiber bundle in such a way that the image recording device is protected from fogging during the annealing process. A further advantage of the transparent plate(s) is that the degree of contamination during the annealing process can be directly detected by observing the plate surface, e.g. by means of an optical measurement.

[0046] The at least one transparent plate can be fixedly arranged in the beam path. Alternatively, the at least one transparent plate can preferably be arranged movably and can be adjusted by at least one drive between a position outside the beam path of the image transmission and a position in the beam path (e.g., a transparent glass shutter). Even if the drive fails, it is advantageously still possible to transmit images through the plate.

[0047] According to further variants of the invention, the at least one transparent plate can be equipped with a plate heating device, e.g., a resistance heater, and can be heatable and / or have a heat-conducting coupling with the respective heated end of the image guide device, in particular the glass fiber bundle. The heat-conducting coupling can, for example, comprise a metallic bridge between an optionally provided metallic frame of the at least one transparent plate and the respective heated end of the image guide device. Advantageously, this allows the at least one transparent plate to be heated and cleaned of interfering deposits, e.g., during regeneration of the image guide device.

[0048] According to another preferred embodiment, the method may further comprise the step of attaching at least one retaining clip to the image guide device, wherein the at least one retaining clip is made of an electrically and thermally insulating material at its contact points with the image guide device. In a further step, the at least one retaining clip is attached to at least one surrounding component of the heating conductor device.

[0049] In this way, it can be ensured that the image guide device does not come into contact with environmental components that are not designed for high temperatures. The use of thermally insulating material prevents heat from the heating conductor device from flowing away into the environment via the holding clips. On the one hand, the environment is protected from the high temperatures of the image guide device. On the other hand, this prevents a temperature gradient from developing within the conductor sheath due to heat dissipation at individual points on the image guide device. Furthermore, unwanted or excessive bending of the conductor sheath with the glass fiber bundle and the heating conductor device can be advantageously avoided by the holding clips supporting the image guide device, thus preventing, for example, excessive sagging of the image guide device.

[0050] The use of electrically insulating material can prevent damage to electrical components from spreading to other components. This applies both to the flow of uncontrolled electrical currents from the surroundings of the image guide device to the image guide device and to the flow of uncontrolled current to other components in the vicinity of the image guide device in the event of a short circuit due to an insulation fault in the heating element device.

[0051] Further details and advantages of the invention are described below with reference to the accompanying drawings. The drawings show:

[0052] Figure 1: a perspective view of a preferred embodiment of the image guide device according to the invention;

[0053] Figure 2: a further, partially sectioned perspective view of the image guide device according to an advantageous embodiment of the invention;

[0054] Figure 3: a perspective view of an additional heating conductor for attachment to one of the connecting pieces according to advantageous embodiments of the invention; and

[0055] Figure 4: Sectional views of the image guide device at the place of use according to an advantageous embodiment of the invention.

[0056] Features of preferred embodiments of the image guide device according to the invention are described below with exemplary reference to embodiments equipped with a total of four heating conductors and in which the image guide device is at least partially covered with a sheath made of a copper braid. Furthermore, the exemplary image guide is designed for use in a vacuum environment and therefore includes vacuum-compatible flange connections on both connection pieces. It is emphasized that the application of the invention is not limited to this example, but can also be advantageous in other environments, in particular at atmospheric pressure, and in other configurations. For example, it is not necessary for the image guide device to be vacuum-compatible.Furthermore, the practical implementation of the invention is not limited to the shapes and dimensions of the individual components given as examples. Rather, the image guide device can be modified depending on the specific application of the image guide device. An optical system for image acquisition on the reaction chamber side can be considered part of the image guide device according to the invention or, alternatively, separately as part of the reaction chamber. Furthermore, a window flange on the image acquisition device side can be considered part of the image guide device according to the invention or, alternatively, separately as part of the image acquisition device.

[0057] According to further variants, the image guide device can be connected to other connecting elements on the connecting pieces, and / or the illustrated flange connections can be dispensed with, e.g. if the connecting pieces can be connected directly to their respective location. Furthermore, the image guide device can comprise a sheath made of a different material, or several sheaths can be provided, or a sheath can be dispensed with entirely. Furthermore, the heating conductor device could comprise more or fewer than four heating conductors. For example, an image guide device can have only a single or more than two sheathed heating conductors. The heating conductors could also be directly connected to a power supply and / or operated with a temperature control system. For this purpose, temperature sensors and heating conductors could, for example, be installed in a single unit.

[0058] The embodiments shown in the figures correspond at least in part, so that similar or identical parts are provided with the same reference numerals and for their explanation reference is also made to the description of the other embodiments or figures in order to avoid repetition. Figure 1 shows a schematic perspective view of an embodiment of the image guide device 1 according to the invention. Figure 2 shows a partially sectioned perspective view of an embodiment of the image guide device 1, which essentially corresponds to the embodiment in Figure 1. Figure 3 shows a detail of the arrangement of heating conductors. Figure 4 shows a schematic sectional view of the image guide device 1 at the place of use.

[0059] The image guide device 1 comprises a conductor sheath 7, inside which is located a fiber optic bundle 5. The conductor sheath 7 and the fiber optic bundle 5 are each equipped with a connector 6 at their two ends (see Figures 2, 4). Each connector 6, which is made of stainless steel, for example, couples the ends of the fiber optic bundle 5 to the ends of the conductor sheath 7. The individual fibers of the fiber optic bundle 5 are sorted and firmly enclosed in the connectors 6 so that input / output windows 18 are formed and, during image transmission 2 (shown schematically in Figure 4), the image recorded in a reaction chamber 3 is transmitted to the side of the image recording device 4, such as a camera 30. For this purpose, the individual fibers of the fiber optic bundle 5 are typically inserted into a grid-like holding structure of the respective connector 6 using an adhesive connection.The grid of the holding structure can correspond to the pixels of the image recording device 4.

[0060] The outer diameter of the glass fiber bundle 5 is preferably smaller than the inner diameter of the conductor sheath 7, so that the glass fiber bundle 5 is arranged inside the conductor sheath 7 with some play in the radial direction. This advantageously minimizes mechanical damage to the glass fiber bundle 5. Although in practice the glass fiber bundle 5 typically rests on an inner wall in the conductor sheath 7 under the effect of gravity, uniform heating of the glass fiber bundle 5 is achieved with the heating conductor device. Alternatively, the outer diameter of the glass fiber bundle 5 can be adapted to the inner diameter of the conductor sheath 7, so that the conductor sheath 7 contacts the glass fiber bundle 5 on all sides. This variant of the invention can have an advantage by improving the heat transfer from the heating conductor device to the glass fiber bundle 5.

[0061] The glass fiber bundle 5 comprises, for example, a fiber strand with 1,190,000 fibers, wherein the fibers have a diameter of 10 μm and are made of quartz glass. The total length of the glass fiber bundle 5 is, for example, 2 m, and the glass fiber bundle 5 has a cross-sectional dimension at its ends, e.g., a diameter or side length of the input / output window 18 of the glass fiber bundle 5, of, for example, 7 mm x 17 mm. The individual fibers are connected to the connectors 6 by means of an adhesive. The conductor sheath 7 is a flexible hose, e.g., a spiral hose made of stainless steel with a wall thickness of the hose material of a few tenths of a millimeter, an outer diameter of 29 mm, and an inner diameter of 25 mm.

[0062] The conductor sheath 7 is covered with a sheath 10 (shown in dotted lines in Figure 4). The sheath 10 is preferably made of an elastic material that has the thermal conductivity of a metal, such as a wire mesh (not shown in detail), e.g., copper mesh (manufacturer, e.g., Techflex Germany GmbH). The sheath 10 advantageously improves the uniformity of heat distribution inside the conductor sheath 7, thereby improving efficient regeneration of the glass fiber bundle 5.

[0063] The heating conductor device 8 provided according to the invention has two heating conductors 9 (jacket heating conductors) arranged on the outside of the conductor jacket 7 between the sheathing tube 10 and the conductor jacket 7 (see Figures 2, 4). The heating conductors 9 are located on opposite sides of the conductor jacket 7, e.g., in Figure 2, on a top side and a bottom side, and they can be coupled to associated power supplies (not shown) via heating conductor connections 22. The two heating conductors 9 each extend over the entire length of the conductor jacket 7. Furthermore, several temperature sensors 11 are arranged on the outside of the conductor jacket 7 (see Figures 2, 4).

[0064] As an alternative to the embodiment shown, at least one heating conductor 9 extending along the length of the conductor sheath 7 can be arranged inside the conductor sheath 7 between the glass fiber bundle 5 and the conductor sheath 7. In this case, the heat of the heating conductor 9 can be dissipated directly inside the conductor sheath 9, whereby the material of the conductor sheath 7 has a lesser influence on the heat distribution.

[0065] In addition to the two heating conductors 9 extending along the conductor sheath 7, the heating conductor device 8 comprises a further heating conductor 9A (connection heating conductor, see Figures 2, 3) at each of the connecting pieces 6. The further heating conductors 9A each at least partially surround the two connecting pieces 6. The further heating conductors 9A can be coupled to associated power supplies (not shown) via heating conductor connections 22. The further heating conductors 9A, which are preferably adapted to the contour of the connecting pieces 6, advantageously prevent an undesirable temperature gradient in the region of the connecting pieces 6 and improve the regenerative capacity and mechanical durability of the glass fibers.

[0066] The heating conductors 9, 9A are formed as resistance heating elements (manufacturer e.g., ThermoExpert Deutschland GmbH) and can each be connected to a power supply, e.g., a power supply unit (not shown). Accordingly, the illustrated embodiment with four heating conductors 9 has eight heating conductor connections 22. Alternatively, the heating conductors 9, 9A can be partially combined into groups. For example, the two heating conductors 9, which extend along the conductor sheath 7, could be combined into a group and operated jointly with a single power supply (see Figure 3). The two heating conductors 9A at the connection pieces 6 (see, e.g., Figures 2 and 4) can each be operated with one or two separate power supplies. Alternatively, a common power supply with multiple outputs, each of which can be controlled separately, can be provided for all heating conductors 9, 9A.

[0067] As illustrated by the heating conductor device 8 shown alone in Figure 3, two heating conductors 9 can be arranged electrically connected in series and coupled to a power supply (not shown) via two heating conductor terminals 22 at a common end of the fiber optic bundle. The series connection of the heating conductors 9 at the opposite end is achieved via the additional heating conductor 9A.

[0068] The heating conductors 9, 9A each have electrical insulation, preferably made of a mineral insulating material, such as MgO. The heating conductors 9, 9A are held in position on the surface of the conductor sheath 7 by the sheathing tube 10. To ensure close thermal contact with the conductor sheath 7, the heating conductors 9, 9A can be additionally fixed to the conductor sheath 7 or the connecting pieces 6 with fastening elements, e.g., silver wire.

[0069] At the ends of the conductor sheath 7, the image guide device 1 preferably has coupling components to which the connecting pieces 6 are connected (see Figures 1, 2, and 4). The end of the conductor sheath 7 on the side facing a schematically shown camera 30 of the image recording device 4 has several coupling components that comprise a connecting flange 17, e.g., a CF flange, and a window flange 16 of the camera 30 and are detachably connected to one another, e.g., screwed. At the other end, a coupling component on the connecting piece 6 is an optics flange 20, which is configured for connection to an optics system 21 (see Figure 4) in the reaction chamber 3.

[0070] To prevent heat from flowing from the image guide device 1 to the reaction chamber 3 or the image recording device 4, at least one of the coupling components can have an insulating element 19 made of heat-insulating material, e.g., a plastic plate with a through-opening, at the respective end of the associated connecting piece 6. Preferably, the material of the at least one insulating element 19 is also electrically insulating, so that any uncontrolled current flow in the vicinity of the image guide device 1 does not reach the connecting pieces 6. Furthermore, this prevents damage to other surrounding components 14 in the event of a malfunction of a component of the image guide device 1, e.g., a short circuit due to an insulation fault in the heating conductors 9, or damage to the glass fibers from heating the reaction chamber 3, e.g., a vacuum chamber, at high temperatures.

[0071] Figure 4 shows a schematic sectional view of the image guide device 1 at the site of use. For reasons of clarity, Figure 4 is not drawn to scale. On the left side is the reaction chamber 3, from which images are to be recorded and transmitted to the image recording device 4 on the right side. The reaction chamber 3 is, for example, the combustion chamber of a fusion reactor. The reaction chamber 3 and preferably the entire image guide device 1 are located in a region in which an ultra-high vacuum is formed. The ultra-high vacuum region is separated from the environment at a higher pressure, e.g., atmospheric pressure, by a reactor wall device 25, shown schematically and partially. The image guide device 1 can be used to record images of a fusion plasma in the combustion chamber of the fusion reactor and transmit them to the image recording device 4, which is arranged in the environment with the higher pressure.Other possible applications include monitoring the beam properties of a particle accelerator or taking images from environments with unfiltered cosmic radiation (space telescopes, space stations, lunar rover, etc.).

[0072] The fiber optic bundle 5 is connected to a window flange 16 of the image pickup device 4 via the connector 6 and the connecting flange 17. The connecting flange 17 is provided for a pressure-tight connection to the reactor wall device 25. The window flange 16 and the image pickup device 4 are located in the atmospheric pressure environment. On the left side, the fiber optic bundle 5 is connected via the additional connector 6 to the optics flange 20, which in turn is connected to the optics 21 in the reaction chamber 3. The optics flange 20 is positioned in the ultra-high vacuum region with a schematically shown holder 26.The input / output windows 18 of the fiber optic bundle 5 are exposed toward the reaction chamber 3 and the image recording device 4, so that, on the one hand, an image can be coupled into the fiber optic bundle 5 via the input / output window 18 on the reaction chamber 3 side using the optics 21, and, on the other hand, can be coupled out via the input / output window 18 on the image recording device 4 side and recorded by the image recording device 4. In this way, the image transmission 2 takes place from the reaction chamber 3 to the remotely located image recording device 4. The fiber optic bundle 5 is inserted into the two connecting pieces 6 on both sides by means of an adhesive connection.Figure 4 schematically illustrates optionally provided transparent plates 23, 24 (shown in dashed lines), at least one of which is arranged between the input / output window 18 facing the reaction chamber 3 and the optics 21 and / or between the input / output window 18 facing the image recording device 4 and the image recording device 4. Preferably, the plate 23 is integrated into the optics flange 20 and / or the plate 24 is integrated into the window flange 16 and / or the connecting flange 17. The transparent plates 23, 24 are flat plates made of quartz glass. The plates 23, 24 protect the optics 21 and the image recording device 4 from fogging when the glass fiber bundle 5 is heated. The plates 23, 24 are each optionally movable by means of a drive (not shown) in order to move them in the manner of a shutter into or out of the beam path of the optics 21 and / or the image recording device 4.The drives can also be integrated into the optical flange 20 and / or the window and / or connecting flange 16, 17.

[0073] Since the conductor sheath 7 with the glass fiber bundle 5 is deformable, in addition to the coupling components, holding clamps 15, e.g. made of stainless steel, can be provided in the region of the conductor sheath 7 on the image guide device 1 to fix the image guide device 1 (see Figures 1, 2).

[0074] The retaining clips 15 are each separated from the conductor sheath 7 by an insulating ring 19. The retaining clips 15 can be attached in the vicinity of the image guide device 1. This prevents the conductor sheath 7 from coming into contact with surrounding components 14 (shown schematically in Figure 4) that are not designed for high thermal loads.

[0075] Furthermore, the retaining clips 15 support the conductor sheath 7 and the heating conductors 9 attached thereto, as well as the glass fiber bundle 5. This advantageously prevents undesired deformation, such as sagging, of the image guide device 1 and its accidental damage. Figures 1 and 2 show two retaining clips 15 near the connectors 6. In practice, more retaining clips 15 and / or retaining clips 15 in other positions may be used. Furthermore, the retaining clips 15 may have a different geometric shape, such as the shape of an elastic gripper.

[0076] Optionally, the image guide device 1 can have an additional heating device 12 that can heat a working gas 13 to a temperature range of 100°C to 400°C (see Figure 4). This heated working gas 13 can be used to heat environmental components 14 that interact with the image guide device 1 and / or components of the image guide device 1 to a predetermined temperature. For example, the adhesive of an adhesive bond between the fiber optic bundle 5 and the connectors 6 could outgas. These gases can precipitate on the environmental components 14, for example, on the optics flange 20 in the reaction chamber 3. The optics flange 20 could become contaminated and might need to be replaced. Depending on the type of reaction chamber 3, such as a particle accelerator, this can involve a considerable amount of work.Heating the ambient components to a temperature that essentially corresponds to the temperature of the conductor sheath 7 can prevent condensation of these gases on the ambient component 14. The working gas, e.g., nitrogen or argon, can absorb the unwanted gases. The additional heating device 12 can be operated in the ultra-high vacuum range, as shown, with a preferably locally acting feed pump (not shown) optionally being provided for removing the working gas with the escaped gas. The additional heating device 12 and optionally the feed pump can also be provided in applications of the invention with operation of the image guide device 1 under atmospheric pressure.

[0077] The image guide device 1 is manufactured by first preparing the glass fiber bundle 5, the conductor sheath 7, and the connectors 6 as separate components, and then positioning the glass fiber bundle 5 inside the conductor sheath 5. The glass fiber bundle 5 and the conductor sheath 5 are connected to one another by securing the connectors 6. The at least one heating conductor 9 is secured along the length of the conductor sheath 7 with fastening elements. Subsequently, the sheathing tube 10 is pulled over the conductor sheath 7 with the at least one heating conductor 9.

[0078] In order to cover the conductor sheath 7 with the sheathing tube 10, an auxiliary tube (not shown) can be used which has a larger diameter than the assembly comprising the conductor sheath 7, connecting pieces 6 (possibly with a socket), heating conductor device 8 and glass fiber bundle 5. The sheathing tube 10 is first pulled over the auxiliary tube. Since the sheathing tube 10 is made of an elastic material and the auxiliary tube has fewer unevennesses than the conductor sheath 7 with the components connected to it, the sheathing tube 10 can be easily pulled over the auxiliary tube. The conductor sheath 7 and the other components are then pushed through the auxiliary tube. One end of the sheathing tube 10 is brought into approximately the position in which it should also be located on the fully assembled image guide device 1.In the next step, this end of the sheath 10 and the conductor sheath 7 are held in place with the other components, and the auxiliary tube is pulled off, leaving the sheath 10 on the conductor sheath 7. The connecting heating conductors 9A are then attached to the connecting pieces 6. The preparation of the connecting heating conductors 9A is shown in Figure 3. To adapt the shape of the connecting heating conductor 9A to the shape of the connecting piece 6, the heating conductor 9A is bent over a suitably shaped mandrel. The resulting turns match the outer contour of the corresponding connecting piece 6. When shaping the mandrel, the elasticity of the heating conductor 9A is taken into account so that the heating conductor 9A springs into the intended shape when removed from the mandrel.

[0079] The image guide device 1, which is preferably intended for use in radiation-exposed environments, is operated as follows. Interaction with ionizing radiation causes defects in the lattice structure of the fibers of the glass fiber bundle 5, resulting in clouding and / or discoloration of the fibers, which are transparent without irradiation. Many of these defects can be healed by heating the fibers to a few hundred degrees Celsius. The image guide device 1 enables the regeneration of the glass fiber bundle 5 to be carried out directly at the site of use, without the need to convert the image guide device 1 into a special furnace.

[0080] For this purpose, the heating conductor device 8 is connected to power supplies when required, i.e. when transmission is restricted and / or at predetermined maintenance intervals, in order to be heated to a temperature in the range of 100 °C and 300 °C, in particular between 200 °C and 250 °C. The regeneration temperature is selected depending on the type of glass in the glass fiber bundle 5, the type of ionizing radiation that caused the material defects, the possible outgassing behavior of any adhesive contained in the image guide device 1, and the temperature at which the irradiation took place. During image transmission 2 between the reaction chamber 3 and the image recording device 4, the image guide device 1 is operated at a temperature below 100 °C, typically at room temperature.

[0081] When electrical current is applied, the heating conductors 9, 9A heat up to the desired temperature. For this purpose, the temperature of the conductor sheath 7 and / or of at least one of the connectors 6 is preferably measured using temperature sensors 11. The temperature sensors 11 are part of a control loop, e.g., a proportional-integral-derivative loop, which is connected to the power supplies. The temperature data from the temperature sensors 11 are used in the control loop as actual values ​​of the controlled variable for controlling the power supply. Heating ends once sufficient transmission through the image guide device 1 has been achieved and / or after a predetermined time interval. The image guide device 1 can then be disconnected from the power supplies and reused for image transmission.Practical tests of the image guide device 1 by the inventors have shown that a radiation-induced reduction and spectral shift in the transmission of the glass fiber bundle 5 could be reversed in a quantitatively similar manner as by conventional annealing in a vacuum furnace. The features of the invention disclosed in the above description, the drawings, and the claims can be important for the realization of the invention in its various forms, both individually and in combination or subcombination.

[0082] List of reference symbols

[0083] 1 image guide device

[0084] 2 Image transmission

[0085] 3 Reaction chamber

[0086] 4 Image recording device

[0087] 5 fiber optic bundles

[0088] 6 connecting piece

[0089] 7 Conductor sheath

[0090] 8 Heating element device

[0091] 9 heating conductors

[0092] 9A heating element

[0093] 10 sheathing tube

[0094] 11 Temperature sensor

[0095] 12 Additional heating device

[0096] 13 Working gas

[0097] 14 Environmental component

[0098] 15 retaining clip

[0099] 16 Window flange

[0100] 17 Connecting flange

[0101] 18 entrance / exit windows

[0102] 19 Insulation ring

[0103] 20 optical flange

[0104] 21 Optics

[0105] 22 Heating element connection

[0106] 23 plate

[0107] 24 plate

[0108] 25 Wall furnishings

[0109] 26 Bracket

[0110] 30 Camera

Claims

Claims 1. Image guide device (1) which is arranged for image transmission (2) to an image recording device (4), comprising - a glass fibre bundle (5) which is arranged for image transmission (2) and is connected to two connectors (6) which are each arranged at one end of the glass fibre bundle (5), and - a conductor sheath (7) which encloses the glass fibre bundle (5) and extends between the connecting pieces (6), characterised by - a heating conductor device (8) with at least one heating conductor (9) which is provided for heating the glass fiber bundle (5) along its length to a predetermined treatment temperature in such a way that radiation-induced material defects in the glass fiber bundle (5) can be reduced by heating to the treatment temperature.

2. Image guide device (1) according to claim 1, wherein - the at least one heating conductor (9) runs along the outside of the conductor sheath (7) and is in thermal contact with the conductor sheath (7), wherein the at least one heating conductor (9) extends along the length of the conductor sheath (7), in particular the entire length of the conductor sheath (7).

3. Image guide device (1) according to claim 1, wherein - the at least one heating conductor (9) is arranged together with the glass fiber bundle (5) in the interior of the conductor sheath (7) and extends along the length of the conductor sheath (7), in particular the entire length of the conductor sheath (7).

4. Image guide device (1) according to claim 1, wherein - the at least one heating conductor (9) is embedded in the conductor sheath (7) and extends along the length of the conductor sheath (7), in particular the entire length of the conductor sheath (7).

5. Image guide device (1) according to one of the preceding claims, wherein - the heating conductor device (8) comprises two heating conductors (9) which extend along the length of the conductor sheath (7), in particular the entire length of the conductor sheath (7).

6. Image guide device (1) according to claim 5, wherein - the two heating conductors (9) are arranged on different, in particular opposite, sides of the glass fibre bundle (5).

7. Image guide device (1) according to claim 5 or 6, wherein - the two heating conductors (9) are arranged electrically connected in series and can be coupled to a power supply via two heating conductor connections (22) at a common end of the glass fibre bundle (5).

8. Image guide device (1) according to one of the preceding claims, wherein - the heating conductor device (8) has an additional heating conductor (9A) on at least one of the connecting pieces (6), which at least partially surrounds the connecting piece (6) and is in thermal contact with the connecting piece (6).

9. Image guide device (1) according to claim 8, wherein - the additional heating conductor (9A) can be operated independently of at least one heating conductor (9).

10. Image guide device (1) according to claims 7 and 8, wherein - the two heating conductors (9) are electrically connected in series via the additional heating conductor (9A).

11. Image guide device (1) according to one of the preceding claims, further comprising - at least one sheathing tube (10) which evenly covers the conductor sheath (7) and the at least one heating conductor (9) laterally and is designed to distribute heat from the at least one heating conductor (9) to the conductor sheath (7), wherein the at least one sheathing tube (10) has a thermal conductivity of a metallic material and is deformable.

12. Image guide device (1) according to claim 11, wherein - the at least one sheathing tube (10) comprises a metal braid.

13. Image guide device (1) according to one of the preceding claims, further comprising - at least one temperature sensor (11) which is designed to detect the temperature of the image guide device (1), and / or - an additional heating device (12) with a temperature-controlled working gas (13) which is designed to heat at least one ambient component (14) of the image guide device (1).

14. Image guide device (1) according to one of the preceding claims, wherein - the heating conductor device (8) is designed to heat the glass fiber bundle (5) to the treatment temperature in the range of 100 °C and 300 °C, in particular 200 °C and 250 °C, and / or - the conductor sheath (7) has a thermal conductivity of a metallic material.

15. Image guide device (1) according to one of the preceding claims, further comprising - at least one transparent plate (23) arranged at at least one end of the glass fiber bundle (5) adjacent to an input / output window (18) of the glass fiber bundle (5) and / or an optic (21) such that the input / output window (18) and / or the optic (21) is protected from fogging when the glass fiber bundle (5) is heated.

16. A method for producing the image guide device (1) according to one of the preceding claims, comprising the steps: - providing the glass fiber bundle (5) and the conductor sheath (7) for receiving the glass fiber bundle (5); - positioning the glass fibre bundle (5) inside the conductor sheath (5); - provision of the two connectors (6) for connection to the fiber optic bundle (5); - positioning of the at least one heating conductor (9) along the length of the conductor sheath (7); and - Connecting the connectors (6) to one of the two ends of the fiber optic bundle (5) and the corresponding end of the conductor sheath (7).

17. The method according to claim 16, further comprising the steps - Positioning of at least one additional heating conductor (9) which at least partially surrounds at least one of the connecting pieces (6) and is in thermal contact with the connecting piece (6) stands.

18. The method according to any one of claims 16 or 17, further comprising the steps - providing at least one sheathing tube (10) which has a thermal conductivity of a metallic material and is elastic; and - covering the conductor sheath (7), the glass fiber bundle (5) and the at least one heating conductor (9), which is provided for heating the glass fiber bundle (5), with the at least one sheathing tube (10), so that the at least one sheathing tube (10) is designed for distributing heat from the at least one heating conductor (9) on the conductor sheath (7) and the at least one heating conductor is evenly covered laterally.

19. The method according to any one of claims 16 to 18, further comprising the steps - Attaching at least one temperature sensor (11) which is designed to detect the temperature of the image guide device (1).

20. Method according to one of claims 18 or 19, wherein the covering of the conductor sheath (7), the glass fiber bundle (5) and the at least one heating conductor (9) with the sheathing tube (10) comprises - stretching the sheathing tube (10) on an auxiliary tube with an inner diameter which is larger than the outer diameter of the composite comprising the conductor sheath (7), the glass fibre bundle (5) and the at least one heating conductor (9); - positioning the conductor sheath (7) with the glass fiber bundle (5) and the at least one heating conductor (9) in the auxiliary tube; and - withdrawing the auxiliary tube from the conductor sheath (7) with the glass fiber bundle (5) and the at least one heating conductor (9), while the sheathing tube (10) remains on the conductor sheath (7), the glass fiber bundle (5) and the at least one heating conductor (9).

21. The method according to any one of claims 16 to 20, further comprising the steps - fastening at least one retaining clip (15) to the image guide device (1), wherein the at least one retaining clip (15) is made of an electrically and thermally insulating material at its contact points with the image guide device (1); and - Fastening the at least one retaining clip (15) to at least one surrounding component (14) of the heating conductor device.

22. A method for regenerating the image guide device (1) according to one of claims 1 to 15, comprising the step: - Heating the glass fiber bundle (5) with the heating conductor device (8) to the treatment temperature in such a way that radiation-induced material defects in the glass fiber bundle (5) are reduced by heating to the treatment temperature, preferably to the treatment temperature in the range of 100 °C and 300 °C, in particular of 200 °C and 250 °C.

23. The method of claim 22, further comprising the steps - heating a working gas (13) with the additional heating device (12) to a temperature in the range of 100°C and 400°C, in particular 200°C and 300°C; and - Flowing the heated working gas (13) onto the at least one ambient component (14) of the image guide device (1).

Images