Optical device

Abstract

The invention relates to an optical device (1), in particular for transmission of ultraviolet light, preferably with high power densities, comprising: a fiber bundle (2) containing a plurality of fibers (3) and a connection end (4) for coupling the device (1) to a light source (5), in particular a laser source, wherein the connection end (4) comprises a receiving means (6) for enclosing, fixing and / or holding the fiber bundle (2) in the region of the connection end (4), wherein the receiving means (6) is adhered in a first adhering region (10) to the fiber bundle (2) in a first end area (11) of the receiving means (6) over which the fiber bundle (2) extends.

Description

[0001] Optical device

[0002] This invention relates an optical device comprising a fiber bundle and a connection end which is connectable to a light source.

[0003] A fiber optic bundle is an assembly of multiple optical fibers. Multiple fiber bundles are used to separate or combine beams. The fibers in the bundle are usually held together at one end and can be separated into multiple branches at the other end. A fiber bundle provides significantly more light throughout than a single fiber in a patchcord.

[0004] It is possible to combine up to several thousand fibers in a fiber bundle.

[0005] Fiber bundles have many applications, such as material processing, UV curing, photolithography, UV spectroscopy, sensor technology, analytics, UV illumination, and Raman spectroscopy.

[0006] Optical fiber bundles are in particular the best choice for applications requiring light collection or delivery over large areas, such as illumination or spectrometry, where a single fiber's limited core size cannot capture sufficient light. Bundles support multi-point light delivery or sensing, allowing for simultaneous access to multiple locations ("Y-shaped bundle" or bifurcated bundle). They handle high-power or large beam sizes by distributing light across multiple fibers, minimizing damage risk.

[0007] Additionally, bundles are versatile in custom geometries, enabling configurations like circular-to-linear light transformation, which is impossible with a single fiber. The fiber bundles known in the prior art can differ from one another in the way the fibers are fixed at the bundle end (in-coupling or out-coupling end). Each bundle type has its own set of advantages and disadvantages, impacting transmission efficiency, power handling limits, acceptable beam aperture, and bundle cross section shape.

[0008] The most common examples of fiber bundle configurations are bifurcated, straight and fan-out fiber bundles. A bifurcated bundle has two fibers side by side at the common end and splits into two legs at the other end. A straight fiber bundle has one input and one output. In this configuration, bundles can have a variety of ge-ometries with linear, hexagonal, circular, array, etc. Fan-out bundles can be thought of as a common junction split from two to many legs.

[0009] The main difference between fan-out and furcation bundles is that any number of fibers in each leg can be placed. This makes all the difference for reflection, fluorescence, backscatter or Raman measurements where it is needed to illuminate and collect independently.

[0010] All prior art optical fiber bundles lack support for light transmission in the UV wavelength range. Ordinary optical fiber material is susceptible to "photo-darkening" or "solarization," an effect caused by UV radiation degrading the quartz glass material of the optical fiber core and cladding. This affects the light transmission efficiency, making the optical fiber not practically useful for certain UV wavelengths.

[0011] Photo-darkening in optical fibers is the gradual increase in optical attenuation when the fiber is exposed to UV light. This effect occurs due to the creation of color centers - defects in the silica matrix caused by UV photon interactions - that absorb light in specific wavelength ranges. This reduces the fiber's ability to transmit light, particularly in the UV and visible regions, degrading performance in applications like UV laser delivery or spectroscopy. The severity of photo-darkening depends on factors such as fiber composition, dopants (e.g. germanium), and the intensity and wavelength of the UV exposure.

[0012] However, there is a solution for single optical fibers: when hydrogen molecules are loaded into the optical fiber core and / or the cladding, the photo-darkening is drastically reduced and the useful transmission efficiency is maintained despite ongoing UV irradiation. In theory, the presence of hydrogen closes chemical bounds in the SiC>2 structure which have been damaged by UV radiation.

[0013] Nevertheless, hydrogen is highly diffusive and will not remain inside the optical fiber material. A coating must be applied to trap the hydrogen inside the optical fiber. The established approach is to apply a thin carbon coating to fiber core and / or the cladding of the optical fiber to prevent the hydrogen from escaping.

[0014] Unfortunately, the formation of an optical fiber bundle from carbon-coated, hydrogen-loaded optical fibers in conventional manners fails. Glued bundles which consist of glued fibers of the fiber bundle are limited in total transmission and glue de-grades under UV irradiation, limiting the lifetime of the assembly. Further, fibers fused together cannot be used to form a bundle because the fusing destroys the carbon coating, allowing hydrogen molecules to escape or requiring re-coating. Fusing also alters the optical fiber's chemical structure, as experiments have shown, leading to strong absorption of the bundle in the relevant wavelength range.

[0015] Further, another disadvantage of the prior art, independently of the lack of transferability of UV light, is that the attachment of the fibers at the fiber end, which can also be referred to as the connection end and is used for coupling to the light source, is comparatively elaborate and, in particular, requires a large-area, cohesive connection between the fibers, which must extend over the entire area of the connection end, in order to ensure sufficient strength. Welding, also called fusing, and gluing are known as material-locking connections, but both methods have disadvantages. In particular, gluing the fibers to each other over a large area is not resistant to ageing and is expensive to produce. Welded and / or fused fibers, on the other hand, place restrictions on the materials of the fibers and also lead to damage to the fibers.

[0016] The object of the present invention is to provide a device which avoids or at least reduces the disadvantages of the prior art.

[0017] This object has been solved by the invention or embodiments thereof as defined in the claims and as described herein below.

[0018] It has been found that the invention or embodiments thereof have a number of additional advantages which will be clear to the skilled person from the following description.

[0019] The present invention relates to an optical device according to claim 1.

[0020] The inventive optical device is in particular used for transmission of ultraviolet light, preferably with high power densities.

[0021] Therefore, the optical device is in particular used for transmission of ultraviolet light, preferably with high power densities. The optical device comprises a fiber bundle containing a plurality of fibers and a connection end for coupling the device to alight source, in particular a laser source. Other light sources can be a deuterium lamp or a Xenon excimer lamp.

[0022] According to the invention, the connection end comprises a receiving means for enclosing, fixing and / or holding the fiber bundle in the region of the connection end, wherein the receiving means is adhered in a first adhering region to the fiber bundle in a first end area of the receiving means over which the fiber bundle extends.

[0023] The receiving means in particular enables, that the fibers are held in position by the receiving means, which can be designed as a quartz glass capillary tube of suitable inner diameter.

[0024] This is advantageous for avoiding the problems associated with the prior art for fiber attachment. The adhesive bond in the first adhering region is particularly advantageous for UV radiation transmission, because, preferably, the first adhering region extends only over a partial area of the receiving means and, in particular, in that section facing away from the light source. In this way, the type of attachment according to the invention improves aging stability, since the adhesive is particularly little exposed to the radiation.

[0025] In the same way, production can also be improved. In particular, the production can be made more cost-effective by the simple attachment.

[0026] Restrictions that may result from the need to glue the fibers over the entire surface or from the need to weld the fibers can be avoided.

[0027] Consequently, the flexibility of the optical device can be increased.

[0028] In particular, in the first adhering region the fibers and / or at least some and / or multiple fibers of the fiber bundle are adhered to the receiving means.

[0029] The first end of the receiving means is the end that is in particular not directly facing the light source. The end of the receiving means that is directly facing the light source, which may include an end face and / or front side, can be referred to as the other end of the receiving means. The fibers of the fiber bundle preferably do not protrude and / or extend beyond the other end of the receiving means.In addition, the gluing at the first end of the receiving means can ensure that the adhesive is not directly exposed to the UV radiation, but can be protected from the UV radiation by the spacing over the length of the receiving means.

[0030] In this context, it is understood that the adhesive for the first adhering region preferably does not extend over the entire length of the receiving means, or at least the area of the receiving means that includes the other end of the receiving means and / or extends over at least 50%, preferably at least 70%, of the length of the receiving means and, in addition, in particular, may also include at least part or all of a central part of the receiving means, has in particular no adhesive and / or is in particular adhesive-free.

[0031] In particular, the adhesive for the first adhering region is provided, preferably only, in the area of the first end of the receiving means, which may extend over a maximum of 30%, or more preferably a maximum of 20%, of the length of the receiving means.

[0032] Thus, the adhesive, which can also be called "glue", for the first adhering region is preferably applied, in particular only, at the end of the receiving means, namely the first end, to fix it with respect to the fibers and in particular to fix the fibers among each other. In this way the adhesive is preferably not subjected to UV radiation at the fiber bundle input. More preferably, a high viscosity adhesive can be used, which can avoid the filling of the empty space between the fibers by capillary forces.

[0033] Preferably, the receiving means comprises as material glass, preferably quartz glass, copper, steel and / or a copper-nickel-zinc alloy and / or consists of glass, preferably quartz glass, copper, steel, ceramic and / or zirconium oxide and / or a copper-nickel-zinc. The receiving means is preferably made of glass, preferably quartz glass. The material of the receiving means can make it possible to prevent damage to the means through the transmission of UV light in the fibers. Furthermore, the receiving means is preferably also exposed to the light source with an end face and thus can come into direct contact with the UV light. In addition, the aforementioned materials are advantageous because they in particular do not interact, or do not interact significantly, with the material of the fibers, particularly when UV light is transmitted, so that the attachment of the fiber bundle in the receiving means can be ensured even when the optical device is in use.Moreover, the first adhering region extends preferably only over less then 50%, preferably less then 30%, more preferably less then 20%, of the length of the receiving means. This means, as already mentioned, that preferably only a part of the receiving means is covered and / or in contact with the adhesive. Therefore, the fixation of the fiber bundle is in particular not destroyed by the UV radiation.

[0034] In a further preferred embodiment, the fibers outside the first adhering region and inside the receiving means are non-adhesive and / or adhesive-free and / or are unconnected to one another in a materially cohesive manner, preferably only fixed by means of the receiving means. It is understood that this does not preclude, in particular, that fibers within the first adhering region and within the receiving means may well come into contact with adhesive. The aforementioned adhesive-free fixing can be used to fix the fiber bundle via the receiving means, with a small amount of space between individual fibers if necessary. In particular, the fibers in the fiber bundle are tightly packed within the receiving means, thus enabling a high fill factor. Damage to the connection of the fibers by UV radiation can therefore be avoided, which in particular enables a long-lasting design.

[0035] According to a further preferred embodiment of the invention it is provided that in the first adhering region the outermost fibers of the fiber bundle are adhered to the receiving means. Preferably, the inner fibers surrounded by the outermost fibers are free of adhesive in the first adhering region or all fibers are adhered together in the first adhering region. The connection of the fibers with the adhesive of the first adhering region can thus be designed depending on the selected attachment.

[0036] At least the outer layers of the fibers of the fiber bundle are preferably bonded with the adhesive, whereby the entire fiber bundle can be attached to the receiving means.

[0037] Depending on the size of the fiber bundle and / or individual specific application requirements, it then makes in particular sense to connect some or all of the fibers with the adhesive. Due to the dense arrangement of the fibers among each other, however, it is particularly sufficient and preferred to adhere only the outer and / or outermost fibers of the fiber bundle to the receiving means using adhesive.The outer and / or outermost fibers are understood to be, in particular, the outermost fibers that face the receiving means directly, as well as, if necessary, some of the fibers arranged below them.

[0038] In any case, the outer and / or outermost fibers, as seen from the center of the fiber bundle, extend from the outer surface of the fiber bundle preferably a maximum of 30%, more preferably a maximum of 20%, as seen in cross-section and based on the radius to the center of the fiber bundle. In this context, it is understood that the fiber bundle is not circular, but that the radius refers in particular to an approximated circular shape of the fiber bundle.

[0039] Particularly preferred, a second adhering region, in particular outside the receiving means, is provided in which the fibers, in particular all fibers, are adhered together. The second adhering region can serve to fix the fibers to one another.

[0040] If necessary, the second adhering region can overlap with the first adhering region or be arranged separately and / or at a distance from it.

[0041] In particular, the second adhering region is outside the receiving means and in particular behind the first end area of the receiving means.

[0042] The second adhering region can serve to fix the fibers, whereas the primary object of the first adhering region is to attach the receiving means to the fiber bundle.

[0043] Due to the arrangement of the second adhering region behind the first adhering region, as seen from the other end of the receiving means, which faces the light source, and / or in the direction of the radiation that passes through the optical device, the second adhering region is also preferably protected from the radiation of the UV radiation and can therefore be designed to be resistant to aging.

[0044] The fibers of the fiber bundle can thus be held together by the receiving means in the area of the connection end in the other end area facing the light source, whereby in the area outside of the receiving means, the fibers can be held together by the second adhering region. In this area, however, the adhesive of the second adhering region is only slightly and / or or not exposed to harmful influences, such as radiation, which ensures a long-lasting use of the optical device.In a further preferred embodiment, the first adhering region the adhesive wraps around at least the outermost fibers and extends over at least 10%, preferably at least 20%, more preferably between 20% and 50%, of the cross section of the fiber bundle in the spaces between the fibers, in particular starting from the outermost fibers, preferably with the inner region of the fiber bundle remaining free of adhesive. The above direction and percentages refer in particular to the cross section and preferably in relation to the radius - thus, in particular at least 10%, preferably at least 20%, more preferably between 20% and 50%, of the cross section of the fiber bundle are covered with adhesive starting from the outer surface or the outer sheath of the fiber bundle in the direction of the center of the fiber bundle. In this context, it is understood that the fiber bundle is, in particular, not circular in shape, but that the radius refers, in particular, to an approximated circular shape of the fiber bundle.

[0045] The attachment of the fibers to one another can preferably be taken over by the second adhering region, so that the first adhering region can extend only over part of the fiber bundle and thus, on the one hand, the fill factor of the fibers in the receiving means can be improved, which leads to improved transmission and, furthermore, the bonding in the first end area can be significantly simplified, since it does not necessarily have to be ensured that the adhesive penetrates into the spaces over the entire fiber bundle.

[0046] Preferably, in the second adhering region the adhesive extends at least substantially throughout the entire cross-section of the fiber bundle in the free spaces between the fibers. This advantageously can enable all the fibers to be securely attached to one another, in particular before they are introduced into the receiving means, which has the particular advantage during the production of the fibers that prefixing can be achieved even before introduction into the receiving means, in particular by providing and / or producing the second adhering region before the first adhering region. After that, the fiber bundle can be introduced into the receiving means, which is then much easier because the fibers have already been prefixed. After the fibers have been introduced into the receiving means, the first adhering region can then be produced and / or provided.

[0047] As mentioned above, in a further preferred embodiment of the invention, the first adhering region and the second adhering region are spaced apart from each other and / or overlap each other and / or form only one combined and / or general adheringregion. The arrangement of the adhering regions can be customized depending on different manufacturing processes and / or customer specifications.

[0048] Preferably, the first adhering region has a length of at least 1 mm, preferably between 1 to 30 mm, more preferably 10 mm + / - 30%. In particular, the length of the first adhesive region mentioned above proved to be sufficiently long for a secure fixation and, at the same time, sufficiently short for the least possible contact with the UV radiation. This is therefore particularly optimal when considering both aspects and resulted in a secure and sufficient fixation of the receiving means to the fiber bundle.

[0049] According to a further preferred embodiment, the second adhering region has a length of at least 0.5 mm, preferably between 1 to 20 mm, more preferably between 5 to 10 mm. The aforementioned length can, in particular, enable secure attachment of the fibers to one another and at the same time also ensure a high flexibility of the optical device. In addition, this length can ensure that the second adhering region extends only in sections over the length of the connection end and / or the optical device.

[0050] The adhesive used for the first adhering region and / or second adhering region can be designed to ensure a good fixation of the receiving means. Preferably, the adhesive used in the first adhering region and / or second adhering region is a two component adhesive, preferably epoxy, in particular a high-viscosity adhesive, more preferably having a high temperature resistance. An adhesive of this kind can penetrate into the free spaces between the fibers, and / or at least into some free spaces between some fibers, and thus enable the fibers that are in contact with the adhesive to be fixed to each other and to the receiving means. At the same time, easy application and thus an optimized production process can be ensured.

[0051] In particular, the degradation temperature of the adhesive is over 200 °C, preferably over 300°C, more preferably 400 °C to 450°C. Consequently, a particularly high temperature resistance can be achieved that meets the requirements of a wide range of industrial applications.

[0052] More preferably, the Shore D hardness of the hardened adhesive is between 50 to 100, preferably 80 + / - 20%. As a result, the adhesive can contribute to the stabilityof the fiber bundle in the cured state, but at the same time it should not get in the way of the flexible properties of the fiber bundle.

[0053] According to a further preferred embodiment of the present invention, the fiber comprises a hydrogen and / or deuterium loaded fiber core and a hydrogen-impermeable and / or deuterium-impermeable and / or hydrogen-diffusion-inhibiting and / or deuterium-diffusion-inhibiting coating enclosing, preferably indirectly, the fiber core.

[0054] No fiber bundles are known in the prior art that can transmit UV radiation with a high power density and / or in a wavelength range between 160 nm and 290 nm over the long term. The afore-mentioned preferred embodiment of the invention remedies this situation.

[0055] It is understood that between the coating and the fiber core, in particular in the case of an indirect arrangement of the coating on the fiber core and / or in the case of an indirect enclosing of the fiber core by the coating, at least one further layer may be arranged, which may also preferably surround and / or enclose the fiber core. This further layer may be an at least single-layer cladding, which will be discussed in more detail below.

[0056] Enclosing the fiber core by means of the coating and / or the cladding can be understood to mean surrounding, enveloping, etc. In particular, the coating and / or the cladding preferably completely surrounds the outer lateral surface of the fiber core. However, the enclosing of the fiber core by the coating and / or the cladding is preferably also to be understood such that the outer end faces of the fiber core, which are arranged on the one hand at the light source and on the other hand at the other end face, may be free, in particular may not be and / or may only partially be enclosed by the coating and / or the cladding. The light from the light source is coupled into the fiber core in particular when the connection end of the optical device is coupled to the light source and the light source emits the light. In this context, it is understood that the fiber core and the fiber itself can be elongated and that the cladding region of the fiber core also arises in particular in the longitudinal direction. Consequently, the cladding and / or the coating can also run in the longitudinal direction of the fiber core.Various light sources may be provided, in particular light sources in the UV range, especially with a wavelength between 160 nm and 290 nm. UV-C light and / or UV-B light are particularly preferred. Laser, but also excimer lasers, fluorescent lamps, quartz lamps, mercury vapour lamps, UV light-emitting diodes, UV cold cathode tubes, etc. can be used as light sources.

[0057] Preferably, the optical device can comprise the light source, but does not necessarily have to comprise the light source. The optical device can thus in particular be coupled with its connection end to the light source which can be (but not has to be) a part of the optical device.

[0058] The preferred hydrogen loading of at least the fiber core is to be understood in particular such that, in the sense of the invention, this can also include isotopes of hydrogen. Consequently, the coating is preferably also diffusion inhibiting and / or impermeable to that hydrogen and / or isotope of hydrogen with which the fiber core is loaded. If the fiber core is preferably loaded with hydrogen, then the coating is preferably hydron-impermeable and / or hydrogen-diffusion-inhibiting. If, on the other hand, the fiber core is alternatively or additionally in particular loaded with deuterium, then the coating is preferably deuterium-impermeable and / or deuterium-diffusion-inhibiting.

[0059] In any case, the coating is preferably designed in such a way that the hydrogen and / or the isotope of hydrogen with which the fiber core is loaded cannot escape through the fiber core, at least not in the essential. The end faces of the fiber core can, but do not have to be coated with the coating.

[0060] Furthermore, the impermeable and / or diffusion-inhibiting with respect to hydrogen and / or deuterium is preferably to be understood in particular such that this applies to ambient conditions and / or laboratory environments in which the light radiation is used and / or the optical device is actually used.

[0061] The loading of the fiber core with hydrogen and / or with isotopes of hydrogen is preferably carried out under high pressure and at high temperature. Under these conditions, the coating can also be permeable to hydrogen and / or the respective isotope of hydrogen. Preferably, the fiber core is also loaded via the coating and / or the coating is already applied to the fiber when the fiber is loaded with hydrogen and / or its isotope. This is still understood to mean a hydrogen diffusion inhibiting ora hydrogen impermeable coating or a deuterium diffusion inhibiting and / or a deuterium impermeable coating, because this refers to the actual environmental conditions during use and when the optical device is used, the hydrogen and / or an isotope of hydrogen should at least essentially not escape from the fiber core.

[0062] Thus, under high-temperature and high-pressure conditions the hydrogen can penetrate the barrier and will preferably diffuse into the fiber core, preferably a quartz glass portion. Under ambient conditions the coating which can be designed as a barrier for the hydrogen and / or deuterium preferably cannot be penetrated, and hydrogen is trapped inside the fiber core, preferably the quartz glass portion, wherein the barrier and / or coating is in particular a carbon coating. Furthermore, in the course of the experiments carried out to achieve the invention, it was found that losses by diffusion of hydrogen and / or deuterium through at least one front side of the fiber, in particular both front sides of the fiber, which is and / or are preferably not coated with the cladding and / or the coating, namely preferably the fiber end face(s), are in particular practically negligible.

[0063] Preferably, the loading hydrogen molecules into the fiber core and preferably cladding can enable that the photo-darkening is preferably drastically reduced, and useful transmission efficiency is maintained despite on-going UV irradiation. The presence of hydrogen and / or hydrogen isotopes closes preferably chemical bounds in the structure of the fiber which have been damaged by UV radiation before. However, hydrogen is highly diffusive and will not remain inside fiber core without the inventive coating. Hence, a coating leads to the advantage that the hydrogen can be trapped inside the fiber and / or the fiber core.

[0064] The coating can be a carbon coating, which is a preferred embodiment. Other materials for the coating are also possible which will be outlined in the following. In particular, a thin carbon coating can be applied onto the fiber, preferably the quartz glass structure of the fiber, to create the coating, preferably to prevent the hydrogen from escaping.

[0065] As outlined before, the formation of an optical fiber bundle from carbon-coated, hydrogen-loaded optical fibers in conventional manners fails. Glued bundles are limited in total transmission generally and (polymer) glue degrades under UV irradiation, which limits the lifetime of the assembly. Fusing fibers to a form a bundle destroys the carbon coating which implies that hydrogen molecules can escape or re-coating is due. Fusing additionally alters the chemical structure of the optical fiber, as experiments showed, and leads to strong absorption of the bundle in the relevant wavelength range. All these disadvantages can preferably avoided with the inventive optical device.

[0066] According to the preferred embodiment of the invention, the optical device can comprise coated with the coating, preferably carbon-coated, hydrogen-loaded and / or deuterium-loaded fibers, which can also be called optical fibers, which can be stacked together to form an optical fiber bundle, as will be described in the following.

[0067] Preferably, the coating remains on the segments of the fibers which is in the receiving means, preferably to keep the hydrogen trapped.

[0068] Further, it has not been known in the prior art that fibers which are coated with the coating and hydrogen-enriched fibers are assembled in the receiving means preferably without using fusing of the fibers or without fusing the receiving means to the fibers.

[0069] This aforementioned preferred design of the fiber enables that the disadvantages of the prior art can be avoided and a transmission for UV light can be enabled in a way that has not been known yet.

[0070] In a further preferred embodiment, a cladding is provided for enclosing, preferably directly, the fiber core. The cladding can be designed as a single-layer and / or multilayer. Alternatively or additionally, the cladding layer arranged directly on the fiber core is referred to as the first cladding. Further, the cladding is in particular arranged between the coating and the fiber core, so that, preferably, the coating is on top of the cladding. If the cladding is designed as a multi-layer cladding, preferably all layers of the cladding and further optional layers can be arranged between the fiber core and the coating, as already has been described.

[0071] Preferably, the cladding, preferably at least the first cladding, is loaded with hydrogen and / or deuterium. The loading of the cladding with hydrogen and / or an isotope of hydrogen can be reached by loading the fiber core with hydrogen. Loading the cladding with hydrogen can further improve the fibers' ability to transmit UV light, thus contributing to a more efficient optical device.Another preferred embodiment of the invention provides that the coating comprises as material carbon, aluminum, chromium, nickel, silver, lead, gold, graphite, nitride, oxynitride, silicon oxynitride and / or quartz glass. Particular preference is given to the fact that the cladding can have quartz glass, wherein the material of the cladding can differ from the material of the fiber core by a different refractive index, which will be discussed separately. In particular, the fiber core and the cladding can comprise quartz glass, where at least one can be doped as needed to achieve the refractive index difference. However, other materials can also be used for the cladding. The aforementioned materials ensure that the radiation that is guided through the fiber core in the operating state also remains within the fiber core and does not escape at an unwanted point.

[0072] With a further preferred embodiment, it is envisaged that the hydrogen and / or deuterium concentration is in the fiber core and / or in the cladding in a range between (0,01 *1018to 100*1018) mol / cm3, preferably between (0,1 *1018to 10*1018) mol / cm3, more preferably between (1*1018to 10*1018) mol / cm3. The aforementioned loading quantities of hydrogen are particularly suitable for the transmission of UV light through the fiber bundle, which was determined in particular during the experiments carried out to achieve the invention. The aforementioned loading can ensure UV light transmission through the individual fibers of the fiber bundle, particularly in the long term.

[0073] According to a further preferred embodiment of the present invention, the receiving means is preferably designed as a tube, in particular a cylindrical tube. The design as a tube, which is preferably open at its end faces and in particular has a closed outer sheath, allows the fiber bundle to extend with its fibers over the first end of the receiving means and to be contacted by the light source at the other end, which may face the light source, whereby the radiation from the light source can be coupled into the fibers.

[0074] The outer sheath of the receiving means stabilizes the fiber bundle and allows secure fixing of the fiber bundle, also at the other end, and in particular means that adhesive does not have to be used at the other end. The cylindrical tubular I tube shape is particularly preferred. Depending on the design of the fibers, however, other geometric designs of the cross-section of the receiving means are also possible if required.In particular, the receiving means has an inner diameter that exceeds the outer diameter of the fiber bundle, preferably by at least 0.1%, more preferably between 0.1% and 10%. Accordingly, the inner diameter of the receiving means in particular is adapted to the outer diameter of that area of the fiber bundle that is to be arranged in the receiving means. Preferably, the receiving means has a diameter that is at least essentially constant, in particular over the length of the receiving means. The adapted inner diameter of the receiving means therefore makes it in particular possible for the fiber bundle to be fixed in the receiving means, preferably at least essentially without play, whereby a form fit can lead to the fixing of the fiber bundle.

[0075] However, the inner diameter is preferably slightly larger than the outer diameter of the fiber bundle, which can be explained by the receiving means being slipped over the fiber bundle during the manufacture of the optical device.

[0076] In a further preferred embodiment it is provided that in the other end area of the receiving means which is opposite the first end area and which faces the light source and / or which is intended to be coupled to the light source the receiving means is unglued and / or unfused to the fiber bundle. As mentioned earlier, this has the advantage that, on the one hand, the coating is preferably not damaged, which would inevitably be the case with fusing, and, on the other hand, no adhesive would in particular be damaged by the UV radiation at the other end of the receiving means. This way, a safe long-term use of the optical device can be made possible.

[0077] In particular, the fiber bundle is friction-locked and / or form-locked in the receiving means. By designing the interior to accommodate the fiber bundle, the fiber bundle can be tightly encased, whereby the fiber bundle can be securely fixed in the receiving means. In particular, at least some of the fibers preferably come into direct contact with the inner wall of the receiving means, and the fact that the fibers in the fiber bundle are densely packed can enable the fiber bundle to be held in the receiving means.

[0078] Preferably, the receiving means has a wall thickness of at least 0.1 mm, preferably between 0.1 to 10 mm, more preferably between 0.5 mm to 2 mm. The aforementioned wall thickness can provide a secure mechanical stability for the fiber bundle and is also durable when subjected to stress.Moreover, the receiving means can have a length of at least 10 mm, preferably 10 mm to 300 mm, more preferably 20 mm to 100 mm. The aforementioned length of the receiving means can ensure that, in particular, adequate fixing of the fiber bundle can be achieved. On the other hand, it was found in the experiments carried out during the development of the invention that this length also offers the decisive advantage that the adhesive preferably provided for the first adhering region and / or second adhering region is not significantly exposed to UV radiation at the other end of the receiving means. Accordingly, a sufficient safety distance can be achieved.

[0079] In a further preferred embodiment, at least one fiber, in particular a plurality of fibers, preferably all fibers, are set back at the other end area from the front side of the receiving means. Alternatively or additionally, it can be provided that at least one fiber, in particular a plurality of fibers, preferably all fibers, are arranged at least substantially flush with said front side. This arrangement can enable the fibers to be exposed to particularly little mechanical stress when coupled to the light source and to be particularly protected from mechanical stress by the receiving means. In particular, it may be provided that some fibers terminate flush with the front side of the receiving means at the other end area and that other fibers are set back from the front side of the receiving means at that other end area facing the light source, and / or do not project beyond this front side. In this way, it can be ensured that the fibers can be used in the long term.

[0080] Particularly preferred, the fibers comprise outside the receiving means an outer jacket, in particular enclosing the fiber core, the cladding and the coating. Preferably, the jacket has been removed from those portions of the fibers that are to be placed in the receiving means. More preferably, the jacket comprises as material plastic, in particular polyimide.

[0081] If necessary, an overall outer jacket which can be called protective sheath can also be arranged around all fibers of the fiber bundle, whereby the fibers can be further protected.

[0082] In any case, the outer jacket of the fibers protects the coating and, if necessary, the cladding from external influences and / or mechanical stresses.Preferably, the segment of fibers which sits inside the receiving means have their outer jacket removed to improve the fill factor, which can lead to a better transmission.

[0083] More preferably, the outer jacket surrounds, in particular completely, the outer sheath of the fibers, preferably the coating, wherein the outer jacket can further be removed at the front sides of the fibers to enable the coupling in and out of the radiation.

[0084] Behind the receiving means, the outer jacket can remain on the fibers as means of mechanical protection, as already has been explained.

[0085] Another preferred embodiment of the invention is that it is envisaged that the outer jacket is also removed in a further portion of the fibers which extend over the front side of the first end area of the receiving means. Preferably, this further portion of the fibers is arranged in the first adhering region.

[0086] The fact that the area freed of the outer jacket preferably extends over the front side of the first end of the receiving means can, on the one hand, considerably simplify the production, which is particularly due to the fact that the fibers of the receiving means do not have to be precisely positioned to within a few millimeters with regard to the arrangement of the portions of the fibers in the receiving means from which the outer jacket has been removed and which are located within the receiving means.

[0087] Consequently, the insertion of the fiber bundle into the receiving means is simplified.

[0088] Furthermore, it can be ensured that in the receiving means, preferably only a few or no fibers are coated with the outer jacket, which improves the fill factor in the receiving means and consequently the transmission of the radiation.

[0089] Moreover, removal of the outer jacket can also be simplified because a certain tolerance of the length of the removed area can be allowed.

[0090] In addition, not all fibers with their outer jacket removed must be the same. Preferably, the portions of the fibers in the receiving means are stripped of their outerjacket and extend beyond the end face and / or front side of the first end of the receiving means with a further portion of which the outer jacket has been removed -this overhang and / or the length of this further portion may differ for different fibers.

[0091] In particular, this further portion of the fibers that is removed from the outer jacket is arranged in the first adhering region, more preferably wherein the first adhering region covers the further portion of multiple fibers, preferably all fibers, being free of the outer jacket and, preferably, a part of multiple fibers, preferably all fibers, having the outer jacket.

[0092] Consequently, the further portion can be protected by the first adhering region against mechanical stresses as well as against further external influences. Accordingly, the protection of the outer jacket can, at least in part, be completely assumed by the first adhering region.

[0093] Further, the transition to the outer jacket can also be arranged in the first adhering region, so that multiple fibers, preferably all fibers, that are coated with the outer jacket preferably project over the first adhering region. This is also preferable from a manufacturing point of view.

[0094] More preferably, multiple fibers, preferably all fibers, in the second adhering region are covered with the outer jacket and / or at least one part of at least one fiber, preferably multiple fibers, in particular all fibers, in the second adhering region has the outer jacket removed. This arrangement can improve the manufacturing step with regard to the removal of the outer jacket. Even if too much outer jacket is removed from some fibers, the area that has been removed can be additionally covered by the second adhering region if necessary. In this way, the production process can be simplified even further. The second adhering region can thus also serve to protect the fibers.

[0095] According to a further preferred embodiment it is provided that the device comprises a light source emitting light in a wavelength range of 160 nm to 300 nm. In particular, the light source may be selected from the following group: Nd:YAG laser emitting a ultraviolet light having a wavelength of (212 + / - 1) nm and / or 266 nm, a light source, preferably a Xenon lamp, in particular a Xe2 excimer lamp, emitting light in a wavelength of 172 nm and / or 175 nm, a light source 5, preferably a deuterium lamp, emitting light in a wavelength of 214 nm , a laser source, preferably aArgon fluoride laser (ArF laser), emitting light in wavelength of 193 nm and their combinations.

[0096] The light source may be a laser, but does not have to be. In particular, the light source is designed so that it can be coupled to the connection end of the optical device. In this embodiment, the light source is part of the optical device. In further embodiments, however, the optical device can also be designed to be coupled only to one of the aforementioned light sources. The individual light sources are suitable for different industrial applications and therefore have different advantages that arise from the respective field of application. It is particularly preferred that the optical device can be coupled to several or all of these light sources, thus enabling flexibility of use.

[0097] Furthermore, as already mentioned in the introduction to the state of the art, the optical device can have different designs. In the sense of the present invention, the optical device and / or the fiber bundle can be designed as a “Y-shaped bundle” and / or bifurcated bundle. However, the further designs for the fiber bundle and / or the optical device as a straight fiber bundle and / or a fan-out fiber bundle and / or and a furcation bundle are also possible in the sense of the present invention.

[0098] In particular, the fiber bundle of the optical device is not limited to a specific design, but the design of the fiber bundle can be flexibly adapted depending on the purpose of use.

[0099] The number of fibers in the fiber bundle can also be selected depending on the application. In particular, the fiber bundle comprises between 5 and 2000 fibers, preferably between 10 and 1000 fibers.

[0100] The individual fibers can have the same length or different lengths.

[0101] Furthermore, the fibers can differ from one another or at least be essentially identical in construction. It is particularly preferred that the fibers are of the same design in order to achieve an at least substantially homogeneous distribution of the fibers in the fiber bundle.

[0102] In a further preferred embodiment, the fiber core has an inner diameter of 30 pm to 1500 pm, preferably of 60 pm to 1000 pm. A fiber core inner diameter in the aboverange is particularly preferred for good transmission of the radiation. In particular, a fiber has an at least substantially constant inner diameter over its length. In particular, the fibers all have at least substantially the same inner diameter, preferably with deviations of up to 50%, more preferably up to 30%, in order to achieve in particular a good fill factor in the receiving means.

[0103] Preferably, the cladding and / or the first cladding has a layer thickness of at least 1 % of the inner diameter of the fiber core, preferably between 3 % to 20 % of the inner diameter of the fiber core, more preferably between 5 % to 10 % of the inner diameter of the fiber core. The wall thickness and / or layer thickness of the cladding can thus be selected depending on the size of the diameter of the fiber core and can thus be optimally adapted to different fiber cores. In tests carried out during the development of the invention, it was shown that the aforementioned relative values for the layer thickness of the cladding enable a reliable transmission of the radiation in the fiber core which can be trapped inside the fiber core due to the cladding, preferably the first cladding.

[0104] According to a further preferred embodiment of the present invention, the coating has a layer thickness of 1 to 200 pm, preferably of 10 to 50 pm, more preferably 20 pm + / - 20%. A layer thickness for the coating in the aforementioned range provides reliable protection for the hydrogen- and / or deuterium-loaded inner part of the fiber, namely at least the fiber core and, if necessary, the cladding.

[0105] Furthermore, the fiber bundle can have a maximum length and / or extension of at least 0.2 m, preferably between 0.2 m to 500 m, more preferably between 0.5 m to 100 m. It is understood that the maximum length of the fiber bundle refers to the maximum length of at least one strand of the fiber bundle. As stated above, the fiber bundle can have various configurations. These can lead to the fact that individual strands of the fiber bundle can also have a shorter length if the application of the optical device should require this. In any case, the fiber bundle can be elongated and ensure transmission of the UV light over a length of several meters, preferably up to 100 m.

[0106] Particularly preferred, the fibers inside the receiving means are arranged in the cross section at least substantially in a hexagon structure and / or at least substantially in a honeycomb structure in the fiber bundle. This arrangement of the fibers in particular allows a dense packing of the fibers in the receiving means and thus aparticularly good transmission of the radiation in the fibers. The aforementioned arrangement has also proven to be advantageous for manufacturing reasons, in order to be able to insert the fiber bundle into the receiving means as easily as possible. In addition, a secure and long-term bond of the fibers can be achieved in this way.

[0107] Preferably, the fibers in the area of the connection end and / or in the receiving means are aligned at least essentially parallel to one another. In this way, in particular, the fill factor in the receiving means can be improved, which can lead to improved transmission of the radiation. Furthermore, the introduction of the fiber bundle into the receiving means can be simplified. Also, damage to the fibers during their manufacture can be avoided.

[0108] In a further preferred embodiment of the present invention, the fibers have a circular, elliptical, D-shape, triangular, hexagonal and / or rectangular cross-section. An at least essentially circular cross-section of the fibers is particularly preferred, so that the fibers as a whole may be particularly preferably cylindrical. However, other cross-sectional shapes are equally possible and may prove to be particularly advantageous for special industrial applications.

[0109] Especially preferred, the refractive index of the fiber core is higher than the refractive index of at least the first cladding, preferably the cladding.

[0110] In particular, the difference in a refractive index between core and the cladding can for example be achieved by lowering or increasing the refractive index between the core and the cladding; one may increase the refractive index of one and decrease the refractive index of the other. It may be beneficial in some embodiments to combine more than one core and / or more than one cladding, in arbitrary combinations and sequences. Then each layer may be designed to have an individual chemical composition and resulting refractive index, leading to potentially several different differences in the refractive index between the different neighboring layers. Preferably, the terms "core" and "cladding" can mean one or several core(s) and / or cladding^), respectively.

[0111] The fiber core is preferably coaxially surrounded by the cladding, in particular wherein the outer jacket mechanically protects the core, and prevents, in particular, the fiber from breaking during the use or transport.The fiber can be a waveguide.

[0112] The cladding is in particular intended to prevent the light waves from escaping or being emitted out of the fiber core. Light energy travels in the path of the least optical resistance, in particular known as Fermat's principle.

[0113] Preferably, the fiber core comprises as material fused synthetic silica and / or germanium doped silica.

[0114] Moreover, the cladding and / or the first cladding comprises as material fluorine doped silica and / or fused synthetic silica.

[0115] Further, the material, preferably the exact material composition of the fiber core, in particular the fused silica material of the core, can differ from the material, preferably the fused silica material of the cladding, preferably to ensure the different refractive indices.

[0116] The material of the cladding and / or of the fiber core can be doped, in particular to ensure the different refractive indices. In particular, the cladding can be doped with fluorine. The fiber core can, alternatively or additionally, be doped with germanium. Preferably, the cladding is doped with fluorine, wherein the fiber core is not doped. The doping can enable that the cladding, preferably at least the first cladding, has a smaller refractive index than the core so that the light propagation behavior on the border surface to the fiber core is characterized in that the light is reflected (back) in the fiber core.

[0117] The preferred material, namely fused silica, of the cladding and the fiber core can exhibit fairly good optical transmission over wavelengths that are to be transmitted according to the invention. Furthermore, silica is also relatively chemically inert. In particular, it is non-hygroscopic (it does not absorb water). As already mentioned, silica glass can be doped with various materials, wherein one purpose of doping, in particular of the core, is to rise the refractive index (e.g. with germanium dioxide (GeCh)) and another purpose of doping, in particular of the cladding, is to lower it (e.g. with silicon tetrafluoride (SiFzi)).In a further preferred embodiment of the present invention, the fiber ends of the fiber bundle at the connection end are covered with protection caps, in particular for protecting them from the environment. The protection caps can be permeable to UV radiation and in this way protect the outer ends (fiber ends) of the fiber core, but at least essentially do not prevent the radiation from being coupled into the fiber core.

[0118] In particular, the connection end comprises at least one outer plug for connecting the fiber bundle to the light source. The fiber bundle can be arranged in the plug. Further, the plug can comprise as material metal. Alternatively or additionally, the front side of the plug facing the light source is open.

[0119] The outer plug can also enable easy coupling of the connection end to the light source and protect both the receiving means and the fiber bundle from mechanical stresses and / or external influences. Different light sources can also require different outer plugs, so that the outer plug can preferably be designed to match the area of the light source that is intended for coupling.

[0120] Consequently, the optical device can have different outer plugs for different light sources and / or applications as required. The outer plug can be a plug that can be inserted into a corresponding plug opening of the light source.

[0121] The outer plug can designed to achieve a SMA connector and / or FC / PC connector for coupling the optical device to the light source.

[0122] Inside the plug, the fiber bundle is arranged and preferably extends over the outer plug.

[0123] Moreover, the receiving means is preferably arranged completely inside the outer plug.

[0124] The outer plug can form the optical device as a fiber cable and / or, through the outer plug, the optical device can have a fiber cable that includes the outer plug, the fiber bundle and the receiving means. The fiber cable can thus be easily connected to light source.If necessary, the outer plug can also have a thread for coupling to the light source and / or can be connected to the light source in a form-fitting and / or frictional manner using a corresponding means.

[0125] Furthermore, it is clear that in the aforementioned intervals and ranges all interim intervals and individual values are comprised and must be considered as essential for the invention, even if these interim intervals and individual values are not specifically provided.

[0126] Further features, advantages, and application possibilities of the present invention are provided in the following description of exemplary embodiments shown in the drawing and the drawing itself. All described and / or illustrated features form, by themselves or in any combination, the object of the present invention, regardless of their summary in the claims and their dependencies.

[0127] Preferred embodiments of the device according to the present invention are shown in the enclosed drawing, wherein:

[0128] Figure 1 shows a first embodiment of an inventive optical device;

[0129] Figure 2 shows the front view of the optical device shown in Fig. 1 in the area of the connection end;

[0130] Figure 3 shows the rear view of the optical device shown in Fig. 1 at the end opposite the connection end;

[0131] Figure 4A shows a schematic representation of the connection end of the optical device according to a further embodiment of the present invention;

[0132] Figure 4B shows a schematic sectional view in the area of a second adhering region according to the invention;

[0133] Figure 4C shows a schematic sectional view in the area of a first adhering region according to the invention;

[0134] Figure 5 shows a schematic cross-section of the fiber according to the invention;Figure 6 shows a schematic representation of a first end of the receiving means according to the invention, with a fiber bundle arranged in the receiving means;

[0135] Figure 7 shows a further schematic representation of a further embodiment according to the invention of the optical area in the area of the connection end;

[0136] Figure 8 shows in detail an adhering region as shown in Fig. 7 and the area around the first end of the receiving means from Fig. 7;

[0137] Figure 9 shows another embodiment of an outer plug of another inventive embodiment of the optical device;

[0138] Figure 10 shows a further inventive embodiment of the optical device;

[0139] Figure 11A shows a first illustration of measurement results of the embodiment example;

[0140] Figure 11 B shows a further illustration of further measurement results of the embodiment example;

[0141] Figure 12A shows a further illustration of further measurement results of the embodiment example;

[0142] Figure 12B shows a further illustration of further measurement results of the embodiment example;

[0143] Figure 13 shows a further illustration of further measurement results of the embodiment example;

[0144] Figure 14A shows a further illustration of further measurement results of the embodiment example;

[0145] Figure 14B shows a further illustration of further measurement results of the embodiment example;Figure 15 shows a further illustration of further measurement results of the embodiment example;

[0146] Figure 16 shows a further illustration of further measurement results of the embodiment example;

[0147] Figure 17A shows a further illustration of further measurement results of the embodiment example;

[0148] Figure 17B shows a further illustration of further measurement results of the embodiment example;

[0149] Figure 18 shows a further illustration of further measurement results of the embodiment example; and

[0150] Figure 19 shows a further illustration of further measurement results of the embodiment example.

[0151] In the figures, which are only schematic and sometimes not to scale, the same reference signs are used for the same or similar parts and components, corresponding or separable properties and advantages being achieved even if these are not repeatedly described.

[0152] Fig. 1 shows an optical device 1 which can be coupled to a light source 5, as for example shown schematically in Fig. 4.

[0153] In particular, the optical device 1 is used for transmission of ultraviolet light, preferably with high power densities.

[0154] Fig. 2 shows the front view of the optical device 1 shown in Fig. 1, wherein Fig. 3 shows the rear view of the optical device 1 shown in Fig. 1. Fig. 2 shows that a fiber bundle 2 which contains a plurality of fibers 3.The total number of fibers 3 in the fiber bundle 2 can vary for different applications and / or different optical devices 1. In particular, the number of fibers 3 can be between 10 and 1000.

[0155] The fiber bundle 2 can be designed as a straight fiber bundle 2, which is shown schematically in Fig. 1.

[0156] In addition, the fiber bundle 2 can also be designed as a fan-out fiber bundle 2, which is shown schematically in Fig. 10.

[0157] Not shown in detail is that the fiber bundle 2 can also be designed as a bifurcated fiber bundle 2 in further embodiments.

[0158] Fig. 1 shows, that the optical device 1 comprises a connection end 4 for coupling the optical device 1 to a light source 5 which is schematically shown in Fig. 4, wherein Fig. 4A shows the connection end 4 in more detail for a further embodiment of the optical device 1.

[0159] The light source 5 can be a part of the optical device 1, which can also be called only "device 1", but does not have to be.

[0160] Preferably, the light source 5 is a laser source.

[0161] The optical device 1 can be coupled to the light source 5 via a plug connection.

[0162] The optical device 1 can be coupled to the light source 5 via a plug connection. Various connections can therefore be realized on the optical device 1 as required, which enable the coupling to the light source 5. A connection can be formed by an outer plug 24 of the connection end 4, which can be designed in particular according to a plug connection on the light source 5. Figures 1, 9 and 10 show various connections, in particular outer plugs 24, of the connection end 4, which can be designed in particular in dependence on the light source 5. If necessary, the outer plug 24 has a winding or further coupling means, which has a form-fitting and / or frictional connection, which is preferably non-destructively detachable, to a corresponding connection means on the light source 5.Fig. 2 shows that the connection end 4 comprises a receiving means 6 for enclosing, fixing and / or holding the fiber bundle 2 in the region of the connection end 4. The enclosing of the fiber bundle 2 through the receiving means 6 is shown in more detail for different embodiment in the Fig. 4A as well as in the Fig. 9.

[0163] Fig. 4A shows that the fiber bundle 2 in particular can be positioned in a stable and preferably play-free manner in the receiving means 6. Preferably, the inner diameter of the receiving means 6 is adapted to the outer diameter of the fiber bundle 2 in the receiving means 6. This is particularly clearly shown in Fig. 2, which visualizes that the fibers 3 are tightly packed in the receiving means 6 and held in the receiving means 6 by directly abutting against one another, at least the outer fibers 3 can thereby partially strike against the inner wall of the receiving means 6, which is also shown in Fig. 2, whereby a secure, form-fitting fixation of the fibers 3 in the receiving means 6 is preferably achieved.

[0164] Fig. 4A shows that the receiving means 6 is adhered in a first adhering region 10 to the fiber bundle 2 in a first end area 11 of the receiving means 6 over which the fiber bundle 2 extends.

[0165] The receiving means 6 shown in Fig. 2 comprises as material glass, preferably quartz glass.

[0166] In other embodiments, the receiving means 6 comprises as material copper, steel and / or a copper-nickel-zinc alloy.

[0167] Further, the receiving means 6 can also consist of glass, preferably quartz glass, copper, steel, ceramic and / or zirconium oxide and / or a copper-nickel-zinc.

[0168] Fig. 4A and Fig. 8 show for different embodiments that the receiving means 6 can be further connected to the fiber bundle 2 by adhering. Thus, in the Fig. 4A and 8 the receiving means 6 is adhered in the first adhering region 10 to the fiber bundle 2 in a first end area 11, which has the first end and / or front side 24 of the receiving means 6, of the receiving means 6 over which the fiber bundle 2 extends. This first end area 11 is opposite the other end area 14 of the receiving means 6 which faces the light source 5.Fig. 8 shows that in the first adhering region 10 the fibers 3 or at least some fibers 3 of the fiber bundle 2 are adhered to the receiving means 6.

[0169] The first adhering region 10 can partially cover an area of the first end area 11, at least the outside of the first end area 11, of the receiving means 6 and in particular a further outside area of the fiber bundle 2 that is adjacent to the first end area 11 , which is shown schematically in Figures 4A and 8.

[0170] The first adhering region 10 thus contributes to the further fixing of the fibers 3 in the receiving means 6, which may additionally be fixed by way of the first adhering region 10 to the receiving means 6. In particular, the first adhering region 10 prevents slipping of the fiber bundle 2 and / or of the fibers 3 in the receiving means 6, even when external forces act on the fiber bundle 2, in particular tensile forces.

[0171] The length and design of the first adhering region 10 may depend on how the fiber bundle 2 is to be attached.

[0172] Fig. 4A as well as Fig 8 show for different embodiment, that there may also be several adhesive sections for adhering the fiber bundle 2 - namely the first adhering region 10 and the second adhering region 12.

[0173] Fig. 4A also shows that there is no adhesive and / or no adhesive area in the other end area 14, which encompasses and / or comprises the front side 16 of the receiving means 6 and which can face the light source 5 in the state of use. Consequently, the adhesive 13 can be protected from the UV radiation by arrangement at the opposite first end area 11, in particular over the distance through the receiving means 6 and, further preferably, by arrangement at least partially, preferably completely, in the outer plug 23.

[0174] The adhesive 13 is shown in more detail in the Fig. 4B and 4C for the adhering regions 10, 12. In this regard, Fig. 4B shows in a schematic cross-sectional view the distribution of the adhesive 13 between the free spaces of the fiber bundle 2 in the second adhering region 12, which arise between the fibers 3. In contrast, Fig. 4C shows in a schematic cross-sectional view the distribution of the adhesive 13 in the area of the first adhering region 10. As will be explained in more detail below, the adhesive 13 in the area of the first adhering region 10 does not cover all the free spaces in the fiber bundle 2, but rather serves in particular to bond the outermostfibers 3, in particular the outermost layers of the fibers 3 of the fiber bundle 2, to receiving means. In Fig. 4C, the receiving means 6 is not shown, so the cross-section is just behind the other front side 25 of the receiving means 6, which can also be covered by the first adhering region 10, as shown schematically in Fig. 4A. For reasons of schematic representation, the structure of the fiber 3 is not shown in more detail in Figs. 4B and 4C. The fibers 3 can be formed according to the previously and in the following described embodiments.

[0175] The first end area 11 and the other end area 14 may extend over a portion of the length 16 of the receiving means 6, in particular from the respective front side (which can also be called end face) 16, 24 by at least 5%, preferably between 5% and 20%, of the length 15 of the receiving means 6.

[0176] As shown in Fig. 8, the first adhering region 10 extends only over less then 20% of the length 16 of the receiving means 6. Preferably at least over a part of the first end area 11 of the receiving means 6. The second adhering region 12 is in particular arranged outside the receiving means 6, preferably behind the first adhering region 10 - in view of the direction of propagation of the radiation through the optical device 1, as shown schematically in Fig. 4A.

[0177] Fig. 4A shows that fibers 3 outside the first adhering region 10 and inside the receiving means 6 are non-adhesive and / or adhesive-free and / or are unconnected to one another in a materially cohesive manner, preferably only fixed by means of the receiving means 6.

[0178] The first adhering region 10 can have a length of at least 1 mm, preferably between 1 mm to 30 mm.

[0179] Further, the adhesive 13 used in the first adhering region 10 and in the second adhering region 12 is a two component adhesive, preferably epoxy, in particular a high-viscosity adhesive, more preferably having a high temperature resistance, in particular with a degradation temperature of the adhesive 13 over 200 °C, preferably 400 °C to 450°C. The Shore D hardness of the hardened adhesive can be between 50 to 100, preferably 80 + / - 20%.

[0180] Fig. 4A shows that in the first adhering region 10 at least the outermost fibers 3 of the fiber bundle 2 are adhered to the receiving means 6. Fig. 4C shows that theoutermost fibers 3 in the first adhering region 10 are covered with the adhesive 13 and thus glued and / or adhered together.

[0181] Fig. 4C shows that the inner fibers 3 surrounded by the outermost fibers 3 in the first adhering region 10 are free of glue and / or adhesive 13.

[0182] It is not shown that in further embodiments all fibers 3 are adhered together in the first adhering region 10.

[0183] Fig. 4B shows that the second adhering region 12, in particular outside the receiving means 6, is provided in which the fibers 3, in particular all fibers 3, are adhered together.

[0184] Fig. 4C shows further that in the first adhering region 10 the adhesive 13 wraps around at least the outermost fibers 3 and extends over at least 10%, preferably between 20% and 50%, of the cross section of the fiber bundle 2 in the spaces between the fibers 3, namely starting from the outermost fibers 3. Moreover, the inner region of the fiber bundle 2 remains free of adhesive 13.

[0185] Fig 4B shows that in the second adhering region 12 the adhesive 13 extends at least substantially throughout the entire cross-section of the fiber bundle 2 in the free spaces between the fibers 3.

[0186] Fig. 4A shows that the first adhering region 10 and the second adhering region 12 are spaced apart from each other.

[0187] Fig. 8 shows for a further embodiment that the first adhering region 10 and the second adhering region 12 overlap each other and form only one combined and / or general adhering region.

[0188] The second adhering region 12 has a length of at least 0.5 mm, preferably between 5 to 10 mm.

[0189] The fibers 3 of the embodiments can have a special design, in particular to be able to transmit light in the UV wavelength range. In particular, light and / or radiation that can be provided by the light source 5 with a wavelength between 160 nm and 300 nm. In order to transport UV radiation in this range, special demands are placed onthe fibers 3. According to a preferred embodiment of the invention, the fiber 3 comprises a hydrogen and / or deuterium loaded fiber core 7 and a hydrogen-impermeable and / or deuterium-impermeable and / or hydrogen-diffusion-inhibiting and / or deuterium-diffusion-inhibiting coating 8 enclosing, preferably indirectly, the fiber core 7.

[0190] It is understood that the impermeability of the coating 8 relates in particular to the ambient conditions in which the optical device 1 is used, in particular to a temperature range of up to 200°C maximum, more preferably up to 250°C maximum, still more preferably up to 300°C maximum. At temperatures below preferably 100°C, more preferably below 150°C, even more preferably below 200°C, the impermeable and / or diffusion inhibiting design and / or formation of the coating 8 with respect to hydrogen and / or deuterium can be enabled.

[0191] Fig. 5 shows a schematic cross-section of the structure of a fiber 3. The coating 8 is designed in particular to prevent hydrogen and / or deuterium from escaping from the fiber core 7. To ensure this, the coating 8 can in particular surround the mantle area and / or sheath region of the fiber core 7, as shown in Fig. 5.

[0192] The outer end faces, and / or at least one outer end face, of the fiber core 7 may not be coated with the coating 8.

[0193] The coating 8 has the effect that the hydrogen can remain in the fiber core 7, and this is where the diffusion inhibition and / or impermeable formation comes into play. Losses via the optionally open end faces of the fibers 3 are negligible. The coating 8 is provided in particular all around the mantle and / or sheath area of the fiber core 7.

[0194] Fig. 5 also shows that, if required, at least one further layer can be arranged between the fiber core 7 and the coating 8. In the example shown in Fig. 5, this is the single-layer cladding 9.

[0195] In further embodiments, the cladding 9 can also be designed as a multilayer structure and, in particular, can be arranged on the outer mantle surface, which can also be called sheath surface, of the fiber core 7 and is covered by the coating 8. Even when a cladding 9 is arranged on the fiber core 7, the coating 8 at least indirectly surrounds and / or encloses the fiber core 7, as described above.The cladding 9 also preferably does not surround the end faces of the fiber core 7, so that radiation can be coupled into and out of the fiber core 7.

[0196] In further embodiments, loading of the fiber core 7 with hydrogen is in particular also understood to mean loading with an isotope of hydrogen, in particular deuterium. Accordingly, a hydron-impermeable design is understood to mean, in particular, loading of the fiber core 7 with an isotope of hydrogen, wherein the coating 8 is also impermeable to that isotope. The same applies, by extension, to the hydron-diffusion-inhibiting design of the fiber core 7.

[0197] Consequently, fiber core 7 is preferably hydrogen-impermeable and / or hydrogen-diffusion-inhibiting when fiber core 7 is loaded with hydrogen.

[0198] In the same way, in further embodiments, coating 9 can be deuterium-impermeable and / or deuterium-diffusion-inhibiting when fiber core 7 is loaded with deuterium.

[0199] The fiber core 7 can be loaded with hydrogen and deuterium as needed, in which case the coating 8 is impermeable and / or diffusion-inhibiting for hydrogen and deuterium in particular.

[0200] It is understood that other layers of the fiber 3, such as the cladding 9, can also be loaded with hydrogen and / or deuterium.

[0201] Inside the receiving means 6, the fibers 3 in particular are at least essentially parallel to one another, as shown schematically in Fig. 6.

[0202] To protect the fiber bundle 2, an outer protective sheath can be arranged outside the receiving means 6 around the fibers 3, which can be regarded as part of the fiber bundle 2 and is shown schematically in Fig. 1, but also in Fig. 9. This protective sheath can also be seen in Fig. 3, wherein it in particular surrounds the fibers 3.

[0203] As already explained, Fig. 5 shows that a cladding 9 is provided for enclosing, preferably directly, the fiber core 7.

[0204] Fig. 5 shows that the cladding 9 is a single-layer. In further embodiments which are not shown in more detail, the cladding 9 can be designed as a multi-layer.It is not shown that the cladding layer arranged directly on the fiber core 7 is referred to as the first cladding.

[0205] However, Fig. 5 shows that the cladding 9 is arranged between the coating 8 and the fiber core 7, so that, preferably, the coating 8 is on top of the cladding 7.

[0206] Furthermore, the cladding shown in Fig. 5 is also loaded with hydrogen and / or deuterium - like the fiber core 7. Therefore, both the cladding 9 and the fiber core 7 can be loaded with hydrogen, which can improve transmission.

[0207] In the embodiment shown in the figures, the coating 8 comprises as material carbon and / or is designed as a carbon-coating 8.

[0208] In further embodiments, which are not shown in detail, the coating 8 comprises as material aluminum, chromium, nickel, silver, lead, gold, graphite, nitride, oxynitride, silicon oxynitride and / or quartz glass.

[0209] The hydrogen and / or deuterium concentration in the fiber core 7 and / or in the cladding 9 is in a range between (0,01 *1018to 100*1018) mol / cm3, preferably between (1*1018to 10*1018) mol / cm3.

[0210] Fig. 7 shows that the receiving means 6 is designed as a tube, in particular a cylindrical tube. In this case, the front side 17 of the receiving means 6 facing the light source 5 can be open, as shown schematically in Fig. 7. In addition, the other front side 25 opposite this front side 17 can also be open, as shown in Figs. 7 and 8. The outer casing (which can also be called mantle and / or sheath) of the receiving means 6 can be closed. Accordingly, the receiving means 6 can be a hollow body that is open at its front sides 17, 25 and is also elongated. In addition, the design of the receiving means 6 can be provided as a hollow cylinder, which is shown in Fig.

[0211] 7.

[0212] Fig. 10 as well as Fig. 2 show for different embodiments that the receiving means 6 has an inner diameter that exceeds the outer diameter of the fiber bundle 2 between 0.1% and 10%.Fig. 4A shows further that the other end area 14 of the receiving means 6 which is opposite the first end area 11 and which faces the light source 5 and / or which is intended to be coupled to the light source 5 the receiving means 6 is unglued and / or unfused to the fiber bundle 2.

[0213] In particular, the fiber bundle 2 is friction-locked and / or form-locked in the receiving means 6 which is shown schematically in Fig. 6.

[0214] The dimensions shown in Fig. 5 are purely schematic and serve only to visualize the layers of the fiber 3. Further, the dimension shown for the receiving means 6 in Fig. 4A are also schematically. The following can be said about the sizes and size ratios of the layers of the fiber 3 as well as about the sizes of the receiving means 6, wherein the features given below are optional and can be combined with each other as required:

[0215] - The receiving means 6 has a wall thickness between 0.1 to 10 mm, more preferably between 0.5 mm to 2 mm.

[0216] - The receiving means 6 has a length 16 of at least 10 mm, preferably 10 mm to 300 mm, more preferably 20 mm to 100 mm.

[0217] - The fiber core 7 has an inner diameter of 30 pm to 1500 pm, preferably of 60 pm to 1000 pm.

[0218] - The cladding 9 has a layer thickness 21 of at least 1 % of the inner diameter 20 of the fiber core 7, preferably between 5 % to 10 % of the inner diameter 20 of the fiber core 7.

[0219] - The coating 8 has a layer thickness 22 of 1 to 200 pm, preferably of 10 to 50 pm, more preferably 20 pm + / - 20%.

[0220] Fig. 4A shows that at least one fiber 3, in particular a plurality of fibers 3, preferably all fibers 3, are arranged at least substantially flush with the front side 17 of the receiving means 6 which faces in the state of use the light source 5.

[0221] It is not shown, that in further preferred embodiments at least one fiber 3, in particular a plurality of fibers 3, preferably all fibers 3, are set back at the other end area 14 from the front side 17 of the receiving means 6.

[0222] In addition, some of the fibers 3 can be aligned and / or arranged flush with the front side 17 and, if necessary, another part of the fibers 3 can be set back from the frontside 17. This can result from the manufacture of the optical device 1 and the optionally provided different lengths of the fibers 3 in the receiving means 6.

[0223] Fig. 5 as well as Fig. 7 and 8 show that the fibers 3 comprise outside the receiving means 6 an outer jacket 18, in particular enclosing the fiber core 7, the cladding 9 and the coating 8. Further, Fig. 8 shows that the outer jacket 18 has been removed from those portions of the fibers 3 that are to be placed in the receiving means 6.

[0224] Fig. 8 shows that the outer jacket 18 is also removed in a further portion 19 of the fibers which extend over the front side 26 of the first end area 11 of the receiving means 6, in particular wherein this further portion 19 of the fibers 3 is arranged in the first adhering region 10 - as shown in Fig. 8 as well as in further embodiment shown in Fig. 4A.

[0225] The jacket 18 comprises as material plastic, in particular polyimide. This jacket 18 can be provided additionally to an optional provided protective sheath for enclosing the fiber 3. The protective sheath can also enclose the outer jackets 18 of the fibers 3 which are arranged in the protective sheath.

[0226] Fig. 4A shows schematically that the first adhering region 10 covers the further portion 19 of multiple fibers 3, preferably all fibers 3, being free of the outer jacket 18. It is not shown that in further embodiments in the first adhering region 10 a part of multiple fibers 3, preferably all fibers 3, have the outer jacket 18.

[0227] Further, Fig. 4A shows that some fibers 3, preferably all fibers 3, in the second adhering region 12 are covered with the outer jacket 18.

[0228] It is not shown that in other embodiments at least one part of at least one fiber 3, preferably multiple fibers 3, in particular all fibers 3, in the second adhering region 12 has the outer jacket 18 removed.

[0229] As already explained, device 1 comprises a light source 5 emitting light in a wavelength range of 160 nm to 300 nm. In other embodiments, the light source 5 can be: a Nd:YAG laser emitting a ultraviolet light having a wavelength of (212 + / - 1) nm and / or 266 nm, a light source 5, preferably a Xenon lamp, in particular a Xe2 excimer lamp, emitting light in a wavelength of 172 nm and / or 175 nm, a light source 5, preferably a deuterium lamp, emitting light in a wavelength of 214 nm and / or alaser source, preferably a Argon fluoride laser (ArF laser), emitting light in wavelength of 193 nm.

[0230] Fig. 1 shows the length 23 of the fiber bundle 2 with a schematic interruption that is visually represented by two dividing lines. This length 23 can have a maximum length 23 and / or extension of at least 0.2 m, preferably between 0.2 m to 500 m, more preferably between 0.5 m to 100 m.

[0231] Fig. 2 shows that the fibers 3 inside the receiving means 6 are arranged in the cross section at least substantially in a hexagon structure and / or at least substantially in a honeycomb structure in the fiber bundle 2.

[0232] Fig. 8 shows schematically that the fibers 3 in the area of the connection end 4 and / or in the receiving means 6 are aligned at least essentially parallel to one another.

[0233] Further, Fig. 2 shows that the fibers 3 have a at least substantially circular crosssection.

[0234] In further embodiments, the fiber 3 can have an elliptical, D-shape, triangular, hexagonal and / or rectangular cross-section.

[0235] To keep the radiation inside the fiber 7, the refractive index of the fiber core 7 is higher than the refractive index of the cladding 9.

[0236] Further, the fiber core 7 comprises as material fused synthetic silica. The cladding 9 can comprise as material fluorine doped silica.

[0237] In a further embodiment, the fiber core 7 can comprise as material germanium doped silica, wherein the cladding 9 comprises as material and / or fused synthetic silica.

[0238] It is now shown that the fiber ends of the fiber bundle 2 at the connection end 4 are covered with protection caps, in particular for protecting them from the environment.As already described with regard to the Fig. 1, 9 and 10, the connection end 4 comprises at least one outer plug 24 for connecting the fiber bundle 2 to the light source 5. Fig. 2 shows that the fiber bundle 2 is arranged in the plug 24.

[0239] It is not shown that the plug 24 comprises as material metal.

[0240] Nevertheless, the Fig. 2 and 10 show for different embodiment that the front side of the plug 24 facing the light source 5 is open, preferably so that the fiber cores 7 of the fibers 3 can be contacted by the radiation emitted by the light source 5.

[0241] Furthermore, the present invention relates to a method, which is described in the following aspects. In particular, with regard to the method according to the invention, reference may be made to the above-mentioned statements on the optical device 1, which may apply equally to the method given below. The method is intended for the manufacture of an optical device 1, in particular according to one of the above-mentioned embodiments. The aspects relating to the method are given below, with aspect 1 in particular describing the method in an independent manner, whereas aspects 2 to 7 depend on aspect 1 and reflect preferred embodiments of the method:

[0242] 1. Method for producing an optical device (1), in particular for transmission of ultraviolet light, preferably with high power densities, in particular according to one of the claims 1 to 38, wherein the method comprises at least the following steps, preferably in the following order, in particular wherein further optional method steps can be carried out before, after and / or between the following method steps:

[0243] A) Providing a fiber bundle (2) containing a plurality of fibers (3) and of a receiving means (6), preferably each fiber (3) comprises a fiber core (7) and a cladding (9) surrounding and / or enclosing the fiber core (7);

[0244] B) Introducing a first part of the fiber bundle (2) into the receiving means (6) to form a connection end (4) of the device (1) being connectable to a light source (5) so that the receiving means (6) encloses, fixes and / or holds the first part of the fiber bundle (2);

[0245] C) Adhering the receiving means (6) in a first adhering region (10) to the fiber bundle (2) in a first end area (11) of the receiving means (6) over which the fiber bundle (2) extends, in particular wherein first adhering region (10) extends only over less then 50%, preferably less then 30%, more preferablyless then 20%, of the length (16) of the receiving means (6), wherein, preferably, the fibers (3) outside the first adhering region (10) and inside the receiving means (6) are non-adhesive and / or adhesive-free and / or are unconnected to one another in a materially cohesive manner, preferably only fixed by means of the receiving means (6).

[0246] 2. Method according to aspect 1, wherein in the first adhering region (10) the outermost fibers (3) of the fiber bundle (2) are adhered to the receiving means (6), in particular wherein the inner fibers (3) surrounded by the outermost fibers (3) are free of adhesive in the first adhering region (10) or in particular wherein all fibers (3) are adhered together in the first adhering region (10).

[0247] 3. Method according to aspect 1 or 2, wherein before adhering the fiber bundle (2) to the receiving means (6) in the first adhering region (10) the fibers (3), in particular all fibers (3), are adhered together in a second adhering region (12), in particular outside the receiving means (6).

[0248] 4. Method according to one of the aspects 1 to 3, wherein a hydrogen-impermeable and / or deuterium-impermeable and / or hydrogen-diffusion-inhibiting and / or deuterium-diffusion-inhibiting coating (8) is applied on the cladding (9) of the fibers (3).

[0249] 5. Method according to one of the aspects 1 to 4, wherein multiple fibers (3), in particular all fibers (3), are loaded in their fiber core (7) and / or their cladding (9) with hydrogen and / or deuterium, in particular wherein the loading of the fibers (3) with hydrogen and / or deuterium is carried out through the coating (8).

[0250] 6. Method according to one of the aspects 1 to 5, wherein an outer jacket (18) is applied to the fibers (3), in particular wherein the outer jacket (18) encloses the fiber core (7), the cladding (9) and the coating (8).

[0251] 7. Method according to one of the aspects 1 to 6, wherein before introducing the fiber bundle (2) into the receiving means (6) the outer jacket (18) is removed, in particular stripped off and / or etched, from those portions of the fibers (3) that are to be placed in the receiving means (6), in particular wherein the outer jacket (18) is also removed in a further portion (19) of the fibers (3) which extend over the frontside (25) of the first end area (11) of the receiving means (6), wherein, preferably, this further portion (19) of the fibers (3) is arranged in the first adhering region (10).Embodiment Example

[0252] In the following, an embodiment example according to the invention is described in which the inventive optical device (in the following also called SFB (stacked fiber bundle) or the inventive idea is in the following also called SFB technology) is compared to other optical devices known in the prior art used for UV light transmission, wherein the devices known in the prior art are described as well.

[0253] It should be noted that the optical device described below is designed according to a preferred embodiment of the following invention, which is not described below as preferred but as present. However, it is understood that the following descriptions are only a preferred embodiment of the invention in which the fibers are charged with hydrogen and / or deuterium, as previously described as particularly preferred. Furthermore, it is understood that the receiving means is glued and / or adhered to the fiber bundle at least within the first adhering region, as per the invention, although this is not discussed in detail below. However, this is assumed to be present in the version of the optical device described below.

[0254] The present invention enables an innovative technology to treat the end of the fiber bundle to create the inventive optical device, which can also be named "Stacked Fiber Bundle (SFB)", which enables the efficient transmission of laser light in the deep UV range with minimal losses. Light delivery from a source to a destination can be achieved in several ways using fiber bundles. In the prior art a clad fused bundle (CFB) technology is known, which allows high power (up to 6 kW) to be transmitted with low loss over a wide spectral range, while allowing the bundle ends to be shaped (the ends can be the same or different) into virtually any 2D shape. However, certain applications require the transmission of shorter wavelengths, particularly in the deep UV spectrum (Nd:YAG IV and V harmonics), where existing bundle end technologies have limitations - mainly degraded performance over time and lower transmission.

[0255] A stacked fiber bundle and / or the inventive optical device uses carbon-coated, hydrogen-loaded fibers, known for their solarization resistance, formed to provide high transmission and durability when exposed to deep UV light over long periods of time. SFB technology could be used in a number of applications that require transmission of light in the deep UV spectral regions. These applications can be found in medicine, quality control, UV curing, process analysis, etc.Fibers and fiber bundles are unique passive optical components that transmit light from point A to point B. Depending on the spectral range used in the application, various fiber types can be used to efficiently transmit light. More and more applications such as analytical instrumentation, medical, semiconductor, quality control, etc. require working in the UV and deep UV spectral regions.

[0256] One of the drawbacks of using silica optical fibers in the deep UV spectral region is the solarization effect, where UV radiation creates defects in the silica materials which then start to absorb UV radiation. One of the main defects created during the solarization process is an E' center with maximum absorption centered at 214 nm and a non-bridging oxygen hole (NBOH) center with absorption centered at 264 nm. The attenuation value depends on the number of defects created during the solarization process, and the number of defects created depends on the UV irradiance and irradiation time. More intense radiation produces more defects. Therefore, the induced attenuation level strongly depends on the UV radiation source which is used to work with the fiber. The longer the irradiation time, the more defects are created and the higher the induced attenuation level. This effect makes it difficult to use silica fibers in the deep UV spectral range in the prior art.

[0257] It is known that solarization effects can be suppressed if the fused silica fiber is enriched (loaded) with hydrogen. Hydrogen in a SiCh structure reacts with UV induced defects. During the reaction, defects are removed and additional OH-(hydroxyl) groups are introduced into the silica. Therefore, reduced UV radiation induces attenuation.

[0258] For many applications, customers require products with a larger active area. This can be achieved in two ways: by increasing the fiber diameter or by creating a fiber bundle. Increasing the fiber diameter is not good because the larger fiber diameter means that the fiber becomes stiffer and is not flexible enough, making its use in practical applications difficult. Fiber bundle technologies make it possible to increase the size of the active area while keeping the product flexible. There are several types of fiber bundles that differ by the technologies used to treat the end of the bundle:

[0259] - Glued bundle

[0260] - Hexagon Fused Bundle (HFB)

[0261] - Clad Fused Bundle (CFB)- Monolithic Fused Bundle (MFB)

[0262] Each of these technologies has its advantages and disadvantages. One of the main differences between glued and fused fiber bundle end treatment technologies is related to packing density (fill factor). For glued fiber bundles, the fill factor is less than for fused bundles.

[0263] In the following, a new bundle end treatment technology according to the invention (stacked fiber bundle (SFB) and / or the inventive optical device) will be introduced. SFB exploits the advantages of hydrogen loaded fibers - low induced attenuation (solarization) level under intense UV irradiation. The 266 nm laser (Nd:YAG IV harmonic) induced attenuation value for fused and stacked fiber bundles will be compared. The transmission values before and after a 24 h solarization experiment for fabricated SFB are shown. The advantages of SFB will be discussed.

[0264] Fig. 11A and 11 B show the attenuation and recovery spectra for a typical deep UV fiber in Fig. 11A and a typical hydrogen loaded deep UV fiber in Fig. 11 B using a deuterium lamp (fiber length - 2 m). In general, UV radiation induced attenuation can be experimentally measured using UV light sources, such as deuterium lamps, and detection systems like a spectrometer. A fiber (and bundle) is exposed to UV radiation and the transmitted light is detected by a spectrometer at different times. After that, the UV included attenuation can be calculated using the formula:

[0265] a(A,t) = 10 * logF0SS^'1=0) / FOSS^t)

[0266] where a(A,t) - induced attenuation level, FOSS(A, t = o) - fiber optic spectrometer signal at the beginning of measurement and FOSS(A,t) - fiber optic spectrometer signal at any moment of measurement series. For induced attenuation measurements, a specialized deep UV fiber (NA - 0.22) was chosen for the experiments, with core 178 pm and outer quartz diameter 200 pm with polyimide jacket.

[0267] Fig. 11A and 11 B show typical UV radiation (using deuterium lamp) induced attenuation level for such fiber followed by recovery process when irradiation with deuterium lamp occurs and a fiber is exposed to deep UV radiation for only a short time for measurement. Mainly E' centers at 214 nm can be observed with induced attenuation level of 7 dB / 2m. During irradiation, at some point, the saturation level for induced radiation is reached. When fiber irradiation with UV light is switched off, thefiber undergoes a recovery process - annihilation of the created defect, resulting in decreasing of induced attenuation level, shown in Fig. 12A and 12B. Using a broadband deuterium lamp, E’-centers are primarily formed by absorbing single photons with energies greater than 5.8 eV (wavelengths shorter than 214 nm). UV light with wavelengths above 225 nm do not contribute to the damage process at 214 nm, as demonstrated previously. In particular, Fig. 12A and 12B show the deuterium lamp induced attenuation level during solarization process for a typical deep UV fiber in Fig. 12A and a typical hydrogen loaded deep UV fiber in Fig. 12B. After a 4:30 h solarization process, the recovery process was measured, wherein the fiber tested has a length of 2 m.

[0268] From the literature, it is known that solarization effects can be suppressed if the fused silica fiber is enriched with hydrogen. Hydrogen in the SiCh structure reacts with UV induced defects and prevents them from being present in the SiCh structure. As a result, UV induced attenuation can be observed at a negligible level. Fig.

[0269] 11A and 11 B and Fig. 12A and 12B show the UV induced attenuation pattern for manufactured hydrogen loaded fibers according to the invention. For the hydrogen loaded fused silica fiber (namely an inventive fiber having a fiber core of fused silica), the UV induced attenuation level is more than one order smaller than the regular deep UV fiber, giving huge advantages to customers who intend to work in the deep UV spectral region.

[0270] At the Nd:YAG IV harmonic (266 nm), the laser systems silica fiber solarization effect is a huge drawback because it coincides with the NBOH defect absorption band which is mainly induced by UV radiation. Fig. 13 shows the 266 nm laser induced attenuation spectra for a hydrogen loaded fused silica fiber (namely an inventive fiber having a fiber core of fused silica). For this experiment a Nd:YAG laser IV harmonic (266 nm) is used as the laser source having a pulse energy 8.5 mJ (43.3 mJ / cm2), pulse width 5 ns, beam diameter 5 mm and repetition rate 180 Hz, nearly flat top beam profile was used. Laser energy was measured using energy sensors connected to a 2938-R Advanced Optical Power & Meter. During the 266 nm laser solarization process, every 15 minutes (for the first 3 hours) and then every 30 minutes, the fiber was detached from the laser and attached to a deuterium lamp and spectrometer to measure the deuterium light transmitted through the fiber in order to calculate the induced attenuation level for the fiber.The laser induced attenuation reaches approximately 0.6 dB / m, which is only slightly higher than the deuterium lamp induced attenuation measurements shown in Fig.

[0271] 11A and 11 B. In addition, for a typical deep UV fiber, the 266 nm laser induced attenuation level was measured to be over 20 dB / m (the experimental setup cannot precisely measure the induced attenuation level above 20 dB / m).

[0272] Optical fiber bundles offer several advantages over bare optical fibers, making them suitable for a variety of applications: enhanced durability, improved light transmission, versatility in applications, redundancy and reliability, ease of installation and maintenance, etc. To test fiber bundles made from hydrogen loaded fibers, clad fused bundle (CFB) technology known in the prior art was used to merge the benefits of CFB technology and the spectroscopic properties of hydrogen loaded fibers. Three 0.5 m long CFB bundles were fabricated consisting of 31 hydrogen loaded fibers (outer diameter of the fused silica was 200 pm) with different fusing lengths (25 mm, 15 and 5 mm, respectively). One end of the CFB was fused while the other end was glued for simplicity. The fabricated CFB was subjected to a 4 h solarization process using the aforementioned Nd:YAG IV harmonic laser. Transmitted laser energy was measured with an energy sensor located at the other end of the fiber bundle, in addition laser energy was monitored with an internal energy sensor to ensure laser stability. During the solarization process, every 30 minutes (first the 2 hours) and then every 1 hour, the fiber bundle was detached from the laser and attached to a deuterium lamp and spectrometer to measure the deuterium light transmitted through the fiber in order to calculate the induced attenuation level for the fiber bundle. After the spectra were measured, the bundle was attached to the laser to continue the solarization process.

[0273] The induced attenuation is shown in Fig. 14A and 14B. Thus, Fig. 14A and 14B show the 266 nm laser induced attenuation measurements for CFB with different fusing lengths (5, 15, 25 mm), wherein Fig. 14A shows the induced attenuation spectrum after a 4 h solarization process and wherein Fig. 14B shows induced attenuation level during the solarization process. The CFB induced attenuation spectrum (Fig. 14A) differs significantly compared to the single hydrogen loaded fiber induced attenuation spectrum shown in Fig. 13. Not only does the induced attenuation level increase for the CFB, but the shape of the induced attenuation spectra also changes. The induced attenuation level at 214 nm increases to a level that is comparable to the regular deep UV fiber solarization level, and the additional absorption band at 265 nm (or 247 nm) means that more NBOH (or oxygen deficiencycenter (ODC)) defects are induced in the fiber bundle. Through the process of two-photon absorption, 266 nm laser light can cause degradation in the fiber at wavelengths below 250 nm. This leads not only to the formation of Non-Bridging Oxygen Hole Centres (NBOHC), which have an absorption peak near the laser wavelength, but also to the formation of E'-centres at 214 nm. In addition, the level of UV-induced attenuation is lower for shorter fusion lengths than for longer fusion lengths. However, for CFB with fusion lengths of only 5 mm, the laser induced level is still far from the UV induced level for bare hydrogen loaded fibers. These changes in the induced attenuation spectrum for a fused bundle end compared to a single hydrogen loaded fiber suggest that the fiber fusion process might alter the UV radiation induced attenuation level.

[0274] Fig. 14B shows that the 266 nm laser induced attenuation level had not reached a saturation level even after 4 h of solarization. Comparing this to the typical deep UV fiber and hydrogen loaded deep UV fiber induced attenuation level with solarization time, it can be seen that the CFB solarization curves more closely resemble the typical deep UV induced attenuation curves but not the typical hydrogen loaded deep UV fibers (Fig. 12A and 12B). This shows that the fiber fusion processes strongly affect the defect creation mechanisms in fused silica fibers.

[0275] These results, by comparing fiber bundles with different fusing lengths, suggest that the fused part in a fiber bundle have significant impact on the fiber bundle induced attenuation level which results in losing the benefits of the hydrogen loading process in fibers. In order to confirm that the fusing process is responsible for the degradation of the fiber bundle, single fibers were subjected to the production steps that are done to form a bundle - removing jacket material and by subjecting bare fibers to the fusing process - heat treatment.

[0276] Fig. 15 compares the 266 nm laser induced attenuation spectrum for fused fiber bundles, hydrogen loaded fibers and fibers that have gone through the fusing process. Fibers which went through the fusing process show a three times higher UV induced attenuation level compared to the hydrogen loaded fiber. Thus, Fig. 15 illustrates the 266 nm laser induced attenuation spectra for typical hydrogen loaded deep UV fiber and typical hydrogen loaded deep UV fiber which underwent an etching and fusion process to simulate the CFB manufacturing process. The inset in Fig. 15 shows the 266 nm laser induced attenuation spectra for CFB. In addition, the fibers which went through the fusing process show an additional absorptionband around 265 nm (247 nm) which was not present in the hydrogen loaded fibers but shows up for the fused fiber bundles. This indicates that the fusing processes remove the advantages from the hydrogen loaded fiber, even when the fusion length is short.

[0277] To test the suitability of the CFBs for deep UV applications using a deuterium lamp, a new 0.5 m long CFB was fabricated with a 15 mm fusion length. This CFB was completely solarized using a deuterium lamp. The resulting measurements are shown in Fig. 16. Thus, Fig. 16 shows the deuterium lamp induced attenuation spectra for CFB with 15 mm fusion length. The result is completely different from that observed for the 266 nm laser solarization (Fig. 14A and 14B). For the deuterium lamp, the CFB solarization level is closer to that of the bare fiber solarization level (Fig. 11A). An absorption peak is observed between 265 and 247 nm, indicating that more NBOH and / or ODC defects are induced in the CFB. For shorter wavelengths (less than 230 nm) the healing process can even be observed, but it is very difficult to evaluate as the result is close to the accuracy limit of the instrument.

[0278] Fused hydrogen loaded fiber bundles are not suitable for use with lasers in the deep UV spectral region. The fusing process creates defects which negate the advantages of hydrogen loaded fibers, as described above. Glued fiber bundle input is also not a good option because the commonly used glue absorbs UV radiation and degrades within the irradiation time. Using a pulsed laser results in an ablation process on the fiber bundle surface, where glue evaporates and residue can settle on the fiber tips, reducing overall transmission and potentially damaging the fiber.

[0279] These disadvantages can be avoided with an inventive optical device having a connection end, which can also be called "new bundle end". The connection end allows for the formation of fiber bundle ends without the need for fusing and gluing processes, while retaining the benefits of hydrogen loaded fiber solarization. In this technology, fibers are stacked, formed into a receiving means, in particular capillaries, preferably polished and preferably cleaned to ensure maximum transmission of the fiber bundle.

[0280] The inventive SFB technology was tested using the same laser solarization process as CFB bundles with different fusing lengths. Fig. 17A and 17B show the compression of SFB and CFB with different fusion length (5, 15 and 25 mm) using a 266 nm laser induced attenuation, wherein Fig. 17A shows the induced attenuation spec-trum for SFB (inventive device), insert shows a comparison with three CFB, wherein Fig. 17B shows the induced attenuation level during solarization process for SFB and CFBAs shown in Fig. 17A and 17B, the 266 nm laser-induced attenuation level for an SFB practically coincides with the bare hydrogen fiber-induced attenuation spectra after 266 nm laser irradiation (see Fig. 11A and 11 B). The 266 nm laser induced attenuation level is low and only the absorption band at 214 nm, attributed to E' center, can be observed. This is to be expected because the fiber bundle end contains only fibers that have not been subjected to any thermal or harsh chemical processes that can cause defects in the fused silica. The 266 nm laser-induced attenuation for three fused fiber bundles is shown in the Fig. 17A insert, compared to the new SFB. It is clear that the induced attenuation level in the UV spectral region for SFB is significantly lower than that for a CFB. This allows us to use this type of fiber bundle for laser deep UV applications without considering the decreasing transmission of fiber bundles during operation. SFB is also significantly faster, reaching saturation after only several minutes. To test the long-term stability of SFB, a new 1 m long bundle consisting of several hundred hydrogen-loaded fibers was manufactured. Even after 24 hours of solarization experiments with a 266 nm laser and an energy of ~12 mJ (61.1 mJ / cm2), SFB shows a low induced attenuation level of only around 0.1 dB / m (see Fig. 18). It is clear from these 24-hour measurements that SFB shows a more stable result in terms of transmission compared to the stability of laser and other optical element transmission and reflection. Fig. 18 shows a 266 nm laser induced attenuation level for SFB, wherein it varies by only 0.1 dB / m throughout 24 h solarization experiments and wherein small oscillations are attributed to laser heating system working cycles.

[0281] One of the disadvantages of SFB to be considered is the filling factor at fiber bundle ends which affect the bundle’s overall transmission. Fused bundle technologies allow reaching a high fill factor (nearly 100 %), while SFB might only achieve a maximum of 82 % to 87 % depending how efficiently the fibers are stacked. However, according to the inventive arrangement of the fibers in the receiving means a good fixation can be reached which also can enable the UV light transmission which is not known in the prior art. Another factor which needs to be considered is fiber clad to core diameter ratio (CCDR). Smaller CCDR value would allow increasing the core diameter ratio and transmit more UV radiation. On the other hand, a smaller CCDR value could lead to a thin clad size reaching the thickness at which light could leak out of the fiber.Despite the above factors that reduce SFB throughput, the benefits of avoiding UV-induced solarization are significant. A stacked fiber bundle was made from fiber with CCDR - 1.05 and with an outer fused quartz diameter of 200 pm. The SFB outer diameter was 6.4 mm and the bundle consisted of 882 fibers. SFB transmission was measured before and after a 24-hour solarization process (266 nm laser with pulse energy around 12 mJ (61.1 mJ / cm2)). The measured pre- and postsolarization transmission values were around 71 %, as shown in Fig. 19. Fig. 19 shows the SFB transmission values before and after the solarization process using 266 nm laser. Solarization had no effect on bundle transmission at 266 nm, and the fiber bundle input remained undamaged, which is essential for efficient SFB throughput. This confirms that the SFB manufacturing process allows us to create a clean fiber bundle surface that can withstand high laser energy.

[0282] The inventive optical device (the stacked fiber bundle (SFB) technology) allows for utilization of the benefits of hydrogen loaded fiber- solarization resistance, allowing use of SFBs for deep UV laser applications, for example using Nd:YAG laser IV and V harmonic (266 and 213 nm).

[0283] Clad fused bundles (CFBs) manufactured from hydrogen loaded fibers are suitable with deuterium lamp, and only a negligible solarization level can be observed.List of Reference Signs:

[0284] 1 optical device

[0285] 2 fiber bundle

[0286] 3 fiber

[0287] 4 connection end

[0288] 5 light source

[0289] 6 receiving means

[0290] 7 fiber core

[0291] 8 coating

[0292] 9 cladding

[0293] 10 first adhering region

[0294] 11 first end area of 6

[0295] 12 second adhering region

[0296] 13 adhesive

[0297] 14 other end area of 6

[0298] 15 wall thickness of 6

[0299] 16 length of 6

[0300] 17 front side of 6

[0301] 18 outer jacket

[0302] 19 further portion of 3

[0303] 20 inner diameter of 7

[0304] 21 layer thickness of 9

[0305] 22 layer thickness of 8

[0306] 23 length of 2

[0307] 24 outer plug of 4

[0308] 25 other front side of 6 at 11

Claims

Claims:

1. Optical device (1), in particular for transmission of ultraviolet light, preferably with high power densities, comprising:a fiber bundle (2) containing a plurality of fibers (3) anda connection end (4) for coupling the device (1) to a light source (5), in particular a laser source, wherein the connection end (4) comprises a receiving means (6) for enclosing, fixing and / or holding the fiber bundle (2) in the region of the connection end (4),wherein the receiving means (6) is adhered in a first adhering region (10) to the fiber bundle (2) in a first end area (11) of the receiving means (6) over which the fiber bundle (2) extends.

2. Optical device of claim 1, wherein the receiving means (6) comprises as material glass, preferably quartz glass, copper, steel and / or a copper-nickel-zinc alloy and / or consists of glass, preferably quartz glass, copper, steel, ceramic and / or zirconium oxide and / or a copper-nickel-zinc.

3. Optical device of claim 1 or 2, wherein first adhering region (10) extends only over less then 50%, preferably less then 30%, more preferably less then 20%, of the length (16) of the receiving means (6), and / orwherein the fibers (3) outside the first adhering region (11) and inside the receiving means (6) are non-adhesive and / or adhesive-free and / or are unconnected to one another in a materially cohesive manner, preferably only fixed by means of the receiving means (6).

4. Optical device as claimed in one or more of the preceding claims, wherein in the first adhering region (10) the outermost fibers (3) of the fiber bundle (2) are adhered to the receiving means (6),in particular wherein the inner fibers (3) surrounded by the outermost fibers (3) are free of adhesive (13) in the first adhering region (10) orin particular wherein all fibers (3) are adhered together in the first adhering region5. Optical device as claimed in one or more of the preceding claims, wherein a second adhering region (12), in particular outside the receiving means (6), is provided in which the fibers (3), in particular all fibers (3), are adhered together.

6. Optical device as claimed in one or more of the preceding claims, wherein in the first adhering region (10) the adhesive (13) wraps around at least the outermost fibers (3) and extends over at least 10%, preferably at least 20%, more preferably between 20% and 50%, of the cross section of the fiber bundle (2) in the spaces between the fibers (3), in particular starting from the outermost fibers (3), preferably with the inner region of the fiber bundle (2) remaining free of adhesive (13).

7. Optical device as claimed in one or more of the preceding claims, wherein in the second adhering region (12) the adhesive (13) extends at least substantially throughout the entire cross-section of the fiber bundle (2) in the free spaces between the fibers (3).

8. Optical device as claimed in one or more of the preceding claims, wherein the first adhering region (10) and the second adhering region (12) are spaced apart from each other and / or overlap each other and / or form only one combined and / or general adhering region.

9. Optical device as claimed in one or more of the preceding claims, wherein the first adhering region (10) has a length of at least 1 mm, preferably between 1 to 30 mm, more preferably 10 mm + / - 30%.

10. Optical device as claimed in one or more of the preceding claims, wherein the second adhering region (12) has a length of at least 0.5 mm, preferably between 1 to 20 mm, more preferably between 5 to 10 mm.

11. Optical device as claimed in one or more of the preceding claims, wherein the adhesive (13) used in the first and / or second adhering region (10, 12) is a two component adhesive, preferably epoxy, in particular a high-viscosity adhesive, more preferably having a high temperature resistance,in particular wherein the degradation temperature of the adhesive (13) is over 200 °C, preferably over 300°C, more preferably 400 °C to 450°C, and / orin particular wherein the Shore D hardness of the hardened adhesive (13) is between 50 to 100, preferably 80 + / - 20%.

12. Optical device as claimed in one or more of the preceding claims, wherein the fiber (3) comprise a hydrogen and / or deuterium loaded fiber core (7) and a hydrogen-impermeable and / or deuterium-impermeable and / or hydrogen-diffusion-inhibiting and / or deuterium-diffusion-inhibiting coating (8) enclosing, preferably indirectly, the fiber core (7).

13. Optical device as claimed in one or more of the preceding claims, wherein a cladding (9) is provided for enclosing, preferably directly, the fiber core (7), in particular wherein the cladding (9) is a single-layer and / or multi-layer and / or in particular wherein the cladding layer arranged directly on the fiber core (7) is referred to as the first cladding and / or in particular wherein the cladding (9) is arranged between the coating (8) and the fiber core (7), so that, preferably, the coating (8) is on top of the cladding (9), and / or in particular wherein the cladding (9), preferably the first cladding, is loaded with hydrogen and / or deuterium.

14. Optical device as claimed in one or more of the preceding claims, wherein the coating (8) comprises as material carbon, aluminum, chromium, nickel, silver, lead, gold, graphite, nitride, oxynitride, silicon oxynitride and / or quartz glass.

15. Optical device as claimed in one or more of the preceding claims, wherein the hydrogen and / or deuterium concentration is in the fiber core (7) and / or in the cladding in a range between (0,01 *1018to 100*1018) mol / cm3, preferably between (0,1*1018to 10*1018) mol / cm3, more preferably between (1*1018to 10*1018) mol / cm3.

16. Optical device as claimed in one or more of the preceding claims, wherein the receiving means (6) is designed as a tube, in particular a cylindrical tube.

17. Optical device as claimed in one or more of the preceding claims, wherein the receiving means (6) has an inner diameter that exceeds the outer diameter of the fiber bundle (2), preferably by at least 0.1%, more preferably between 0.1% and 10%.

18. Optical device as claimed in one or more of the preceding claims, wherein in the other end area (14) of the receiving means (6) which is opposite the first end area (11) and which faces the light source (5) and / or which is intended to be coupled to the light source (5) the receiving means (6) is unglued and / or unfused to the fiber bundle (2).

19. Optical device as claimed in one or more of the preceding claims, wherein the fiber bundle (2) is friction-locked and / or form-locked in the receiving means (6).

20. Optical device as claimed in one or more of the preceding claims, wherein the receiving means (6) has a wall thickness (15) of at least 0.1 mm, preferably between 0.1 to 10 mm, more preferably between 0.5 mm to 2 mm.

21. Optical device as claimed in one or more of the preceding claims, wherein the receiving means (6) has a length (16) of at least 10 mm, preferably 10 mm to 300 mm, more preferably 20 mm to 100 mm.

22. Optical device as claimed in one or more of the preceding claims, wherein at least one fiber (3), in particular a plurality of fibers (3), preferably all fibers (3), are set back at the other end area (14) from the front side (17) of the receiving means (6) and / or wherein at least one fiber (3), in particular a plurality of fibers (3), preferably all fibers (3), are arranged at least substantially flush with said front side (17).

23. Optical device as claimed in one or more of the preceding claims, wherein the fibers (3) comprise outside the receiving means (6) an outer jacket (18), in particular enclosing the fiber core (7), the cladding (9) and the coating (8), wherein the jacket (18) has been removed from those portions of the fibers (3) that are to be placed in the receiving means (6), in particular wherein the jacket (18) comprises as material plastic, in particular polyimide.

24. Optical device as claimed in one or more of the preceding claims, wherein the outer jacket (18) is also removed in a further portion (19) of the fibers (3) which extend over the front side (25) of the first end area (11) of the receiving means (6), in particular wherein this further portion (19) of the fibers (3) is arranged in the first adhering region (10), more preferably wherein the first adhering region (10) covers the further portion (19) of multiple fibers (3), preferably all fibers (3), being free ofthe outer jacket (18) and, preferably, a part of multiple fibers (3), preferably all fibers (3), having the outer jacket (18).

25. Optical device as claimed in one or more of the preceding claims, wherein multiple fibers (3), preferably all fibers (3), in the second adhering region (12) are covered with the outer jacket (18) and / or wherein at least one part of at least one fiber (3), preferably multiple fibers (3), in particular all fibers (3), in the second adhering region (12) has the outer jacket (18) removed.

26. Optical device as claimed in one or more of the preceding claims, wherein the device (1) comprises a light source (5) emitting light in a wavelength range of 160 nm to 300 nm, preferably a Nd:YAG laser emitting a ultraviolet light having a wavelength of (212 + / - 1) nm and / or 266 nm, a light source (5), preferably a Xenon lamp, in particular a Xe2 excimer lamp, emitting light in a wavelength of 172 nm and / or 175 nm, a light source (5), preferably a deuterium lamp, emitting light in a wavelength of 214 nm and / or a laser source, preferably a Argon fluoride laser (ArF laser), emitting light in wavelength of 193 nm.

27. Optical device as claimed in one or more of the preceding claims, wherein the fiber core (7) has an inner diameter (20) of 30 pm to 1500 pm, preferably of 60 pm to 1000 pm.

28. Optical device as claimed in one or more of the preceding claims, wherein the cladding (9) and / or the first cladding has a layer thickness (21 ) of at least 1 % of the inner diameter (20) of the fiber core (7), preferably between 3 % to 20 % of the inner diameter (20) of the fiber core (7), more preferably between 5 % to 10 % of the inner diameter (20) of the fiber core (7).

29. Optical device as claimed in one or more of the preceding claims, wherein the coating (9) has a layer thickness (22) of 1 to 200 pm, preferably of 10 to 50 pm, more preferably 20 pm + / - 20%.

30. Optical device as claimed in one or more of the preceding claims, wherein the fiber bundle (2) has a maximum length (23) and / or extension of at least 0.2 m, preferably between 0.2 m to 500 m, more preferably between 0.5 m to 100 m.

31. Optical device as claimed in one or more of the preceding claims, wherein the fibers (3) inside the receiving means (6) are arranged in the cross section at least substantially in a hexagon structure and / or at least substantially in a honeycomb structure in the fiber bundle (2).

32. Optical device as claimed in one or more of the preceding claims, wherein the fibers (3) in the area of the connection end (4) and / or in the receiving means (6) are aligned at least essentially parallel to one another.

33. Optical device as claimed in one or more of the preceding claims, wherein the fibers (3) have a circular, elliptical, D-shape, triangular, hexagonal and / or rectangular cross-section.

34. Optical device as claimed in one or more of the preceding claims, wherein the refractive index of the fiber core (7) is higher than the refractive index of at least the first cladding, preferably the cladding (9).

35. Optical device as claimed in one or more of the preceding claims, wherein the fiber core (7) comprises as material fused synthetic silica and / or germanium doped silica.

36. Optical device as claimed in one or more of the preceding claims, wherein the cladding (9) and / or the first cladding comprises as material fluorine doped silica and / or fused synthetic silica.

37. Optical device as claimed in one or more of the preceding claims, wherein the fiber ends of the fiber bundle (2) at the connection end (4) are covered with protection caps, in particular for protecting them from the environment.

38. Optical device as claimed in one or more of the preceding claims, wherein the connection end (4) comprises at least one outer plug (24) for connecting the fiber bundle (2) to the light source (5), in particular wherein the fiber bundle (2) is arranged in the plug (24) and / or in particular wherein the plug (24) comprises as material metal and / or in particular wherein the front side of the plug (24) facing the light source (5) is open.

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