Illumination system comprising an optical waveguide having a diffuser element and method for producing and / or constructing a diffuser substrate at least

Abstract

The invention relates to an illumination system comprising a laser light source and an optical waveguide connectable and / or associated with the laser light source, and comprising a diffuser element at a distal end of the optical waveguide having a longitudinal axis extending into the diffuser element perpendicular to a coupling surface of the optical waveguide, the diffuser element emits light laterally of the longitudinal axis over its effective length, the diffuser element comprising a diffuser base comprising scattering elements aligned along the longitudinal axis of the diffuser base substantially parallel to the longitudinal axis or arranged at an angle to the longitudinal axis, and means for homogenizing the emission intensity along the longitudinal axis of the diffuser base body are arranged at the distal end of the diffuser base body and / or at least partially or over several sections thereof around a transition region between the optical waveguide and the diffuser base body and / or the diffuser base body itself, the illumination system exhibits an intensity profile of lateral emission in its operational state with a deviation of at most + / -50% from the average lateral emission intensity.

Description

This application is a divisional application of Chinese patent application 201880063614.0. Technical Field

[0001] The invention relates to an irradiation system, in particular for a medical and / or diagnostic system, and to a method for producing a diffuser matrix, in particular for an irradiation system, and also to a method for at least partially or segmentally constructing a diffuser matrix, in particular for adjusting the intensity distribution of lateral emission. Background Art

[0002] Such irradiation systems are increasingly used in the medical field. The main application areas can currently be classified as: Photodynamic therapy (PDT) for tumor treatment; ·Energetic intravenous laser therapy (EVLT) for the treatment of varicose veins; Laser-induced interstitial thermal therapy (LITT); and Other applications, for example in the fields of dentistry, ophthalmology and dermatology.

[0003] Photodynamic therapy (PDT) is a minimally invasive therapy option for various cancers. PDT is a procedure that combines light with a substance that can be activated by light to treat tumors and other tissue changes (such as angiogenesis). At the beginning of treatment, the patient receives an intravenous injection of a photosensitive substance (called a photosensitizer), which accumulates in or on cancer cells. These natural photosubstances gather in tumor cells and produce strong sensitivity to light there. For this reason, multiple needles (usually up to 8) are used to pierce the tumor tissue during PDT treatment, and an optical waveguide with a diffuser element is introduced into each of them. The diffuser element needs to be spatially distributed as well as possible on the tumor tissue. A laser (e.g., a green light of 532nm or a red light of 690nm wavelength) with a wavelength in the visible spectrum is injected into the diffuser element via an optical waveguide so that the tumor tissue is irradiated from the inside as evenly as possible, thereby generating aggressive oxygen free radicals in these cells, which selectively destroy tumor cells. Compared with diseased cells, healthy cells are not affected by this chemical reaction. The exact mechanism of action is described inter alia in "Photodynamic Therapy of Cancer" (Cancer Medicine, 2003).

[0004] A distinction is made here between cylindrical diffusers with a typical effective length of 10 to 50 mm, spot diffusers which produce a forward luminous cone, and point diffusers which exhibit radial light emission. In the case of cylindrical diffusers, it is particularly important that the lateral emission of the diffuser element is as uniform as possible over its length in its operating state. This should be the case both in the axial direction and in the radial direction, i.e. in the axial direction, the emission intensity is uniform at all points along each line from the proximal end to the distal end in the direction of the longitudinal axis within the scope of the uniformity requirements, while in the radial direction, the emission intensity is also uniform at all points along each circumferential line along the longitudinal axis within the scope of the uniformity requirements, so that these diffusers essentially act as Lambertian radiators.

[0005] At the same time, a high scattering efficiency must be achieved to ensure the lowest possible heat input into the tissue. Typical uniformity requirements for lateral emission specify a maximum deviation from the mean intensity of ±10% to 20%, while forward emission (especially from the distal end) should avoid more than 10%, typically more than 5%, of the injected light. The laser output power for PDT applications is typically less than 5W of continuous power, so that the maximum power emitted per centimeter of diffuser length is between 100mW and 1000mW, typically between 200mW and 500mW. Currently, this allows the use of plastic-based diffuser implementations.

[0006] An existing example is a diffuser element made of thin silicone cylinders in which scattering particles in the form of titanium dioxide nanoparticles are embedded. Document DE 10129029 A1 describes a flexible device for thermally removing biological tissue by laser radiation via an optical waveguide, the distal end of which is surrounded by a sheath, which is transparent to the laser radiation and protrudes beyond the fiber end and is filled in its volume in front of the fiber end with a silicone matrix in which scattering particles are embedded, wherein non-scattering particles with a diameter of a few nanometers, preferably made of silicon dioxide, are mixed into a plastic matrix, preferably made of silicone, in a concentration range of preferably 1% to 10%, and wherein the distal end of the sheath is sealed by an end piece that is transparent or opaque to the laser radiation.

[0007] However, diffusers with sufficient emission uniformity are very complex and expensive to manufacture. Agglomerates of scattering particles often form emission spots with significantly higher intensity than the average.

[0008] Such optical waveguides with diffuser elements are usually used only once and are discarded after each treatment. Therefore, there is also a certain cost pressure on the manufacturing costs. Therefore, reusable solutions are increasingly considered. Such solutions must therefore allow refurbishment in accordance with relevant known standards, i.e. they must be disinfectable and / or sterilizable. The preparation processes that should be mentioned here include, in particular, cleaning and disinfection processes using strongly alkaline solutions and sterilization by high pressure sterilization at temperatures of up to 135° C. and a typical steam pressure of about 3 bar. Typically, dozens to hundreds of such treatment cycles are then used. This means that high requirements are placed on heat resistance, chemical resistance and hydrolysis resistance. Therefore, optical waveguide and diffuser embodiments made of glass or fused quartz fibers are particularly suitable for this situation.

[0009] In EVLT, the attending physician inserts a catheter into the relevant vein via a small puncture site, which serves as a guide for the intravenous laser. The inner wall of the blood vessel is then heated by targeted lateral emission of laser energy with the aid of a diffuser, causing the vein to collapse and be sealed. In this way, pathological backflow of venous blood is prevented. As a result, the vein hardens, degenerates and is broken down by the body. Currently, emitting elements known as annular or dual annular fire systems are generally used for this purpose. The laser is radially emitted to the tissue surrounding the vein in the form of a relatively clearly defined annular or dual annular light, and at the same time, in order to perform uniform treatment, an optical waveguide with an emitting element is often manually pulled through the vein segment to be treated at a steady rate, which complicates the application because it may cause further cell damage in several locations in the event of non-compliance or excessive residence time.

[0010] Such cylindrical diffusers used in PDT applications will bring advantages here. However, EVLT treatment requires significantly higher laser output powers. For example, in the NIR range, i.e. at wavelengths between about 800nm ​​and 1480nm, the laser power is typically between 10 and 50W, which is currently provided using diode lasers (e.g., 810nm, 940nm or 1480nm) or Nd:YAG lasers (1064nm). At the same time, longer wavelengths of about 2μm have also been established for EVLT treatment. In this case, for example, Tm:YAG lasers (1.9μm) and Ho:YAG lasers (2.1μm) are used. Due to the absorption properties of tissues, lower laser output powers of <10W are generally required at these wavelengths. However, the use of optical waveguides made of fused quartz has been mandatory here, in particular for supplying lasers.

[0011] The uniformity requirements of diffusers that can be used for EVLT in lateral emission are lower compared to PDT applications, and the maximum deviation from the mean intensity can be ±30% to ±50%.

[0012] LITT is a minimally invasive procedure for local tumor destruction. The tumor is punctured under visualization (e.g. ultrasonography / MRI), one (or more) laser fibers are introduced into the tumor focus, and sclerosis is induced in the tumor focus by thermal energy. In this case, in particular Nd:YAG lasers (1064 nm) and diffuser tip applicators are used. The laser output power is approximately 5 to 8 W (see in particular "Laserinduzierte Interstitielle Thermotherapie (LITT) bei malignenTumoren" and KBV 01 / 2002).

[0013] Further diffuser embodiments are known from the documents mentioned below and can be divided into four categories: volume scattering diffusers, fibers with applied scattering particles, diffusers produced by laser processing, and diffusers formed from side-emitting fibers.

[0014] Volume scattering diffusers are disclosed, for example, in document EP 3184885 A1, which describes a diffuser at the end of an optical waveguide made of fused silica, and in order to produce the diffuser, a scattering substance is applied to the fiber distal end of the optical waveguide and solidified to form the diffuser. Applying the scattering substance comprises the following steps: (a) providing SiO2 grains containing amorphous SiO2 particles and consisting of at least 90 wt% SiO2; (b) providing a hollow body made of glass, the hollow body having a cavity wall surrounding a cavity, the cavity being open to the outside; (c) providing a crystal bed of SiO2 grains in the cavity, and introducing the fiber end into the cavity so that at least a portion of the fiber end protrudes into the crystal bed; (d) hot compressing the crystal bed to form a porous sintered mass consisting of at least 90 wt% SiO2, the porous sintered mass being at least partially surrounded by a glass sheath. The disadvantage of such a method is that such a volume scattering implementation implies a strong exponential drop in intensity. Furthermore, porous materials are not preferred in medical technology applications with regard to their processability.

[0015] U.S. Patent No. 6,810,184B2 describes a method in which nanoporous silica coated optical fibers are used to fabricate fibers with integrally formed diffuse tips and diffuse tips that can be fused to other fibers. The disclosed diffusers can be fabricated as cylindrical shapes where light diffuses along its length, spherical shapes where light radiates outward in a spherical pattern, or custom shapes to illuminate irregular surfaces or volumes. Gradient and step refractive properties can also be achieved.

[0016] Documents EP 2 062 077 A4, US 2009 / 0204111 A1 and DE 10 2015 119 875 A1 disclose diffusers which are produced by introducing structures into fibers or applying structures to fibers using a laser.

[0017] Documents EP 2062077 A4 and WO 2008 / 024397 A2 disclose a diffuser for outputting high power density light energy to a treatment site at the distal end of at least one optical fiber, wherein the diffuser comprises a predetermined length section of the distal end of at least one optical fiber and a scattering center located in the predetermined length section at the distal end of the optical fiber, the scattering center causing a portion of the input light energy to be radially emitted to the treatment site. It is contemplated that the scattering center is located in the predetermined length of the fiber core, or in or near the interface between the fiber core and the cladding in the predetermined length. The scattering center is a defect in the fiber core, such as a nanocrack or nanovoid that produces a local refractive index difference in the core or in or near the interface between the core and the cladding. The scattering center may be a scattering particle contained in the core or in the cladding of the core. Besides the fact that their complex introduction is difficult to control (e.g. in terms of the distribution and / or size of the above-mentioned nanocracks or nanovoids), the nanocracks or nanovoids may also have a negative impact on the fragility of the component. In addition, in all approaches, it has to be expected that the desired uniformity of the lateral emission will not be achieved, either due to the exponential decay of the lateral emission in the case of a sufficiently uniform design or due to inhomogeneous distribution.

[0018] Document US2009 / 0204111 A1 describes a laser delivery system comprising an optical fiber having: (i) a core and a cladding covering at least a portion of the core, wherein the cladding has a lower refractive index than the core; and (ii) a non-featured portion and a feature portion, wherein the feature portion has a feature that forces light to be radially coupled out of the feature portion and provides a desired radial light output pattern. It is contemplated that the feature is selected from the group consisting of threads, radial cuts, axial cuts, and combinations thereof.

[0019] DE 102015119875 A1 discloses an optical waveguide comprising: an optical waveguide core; a region in the optical waveguide in which micro-modifications are arranged, wherein the micro-modifications are arranged in an ordered manner. A method for introducing micro-modifications into an optical waveguide comprises the following steps: (a) adhering the optical waveguide in a holder, the optical waveguide and / or the holder being mounted in a movably manner; (b) focusing high-energy radiation onto a focal position, which focal position is positionable inside the optical waveguide, the radiation being generated by a radiation source in pulsed operation, and a focusing device for focusing the high-energy radiation being mounted in a movably manner; and (c) moving the focal position through the optical waveguide, wherein the movement of the focal position inside the optical waveguide is selected in a manner dependent on the repetition rate.

[0020] Document DE 10 2012 208 810 A1 of the applicant discloses a side-emitting glass element comprising a plurality of light-guiding elements made of glass with a refractive index of n1 and inseparably connected to one another at their outer circumferential surfaces, and at least one scattering element inseparably connected to the outer circumferential surface of at least one light-guiding element, so that when light is guided in the glass element, a portion of this light is emitted laterally from the glass element, wherein the individual light-guiding elements are not individually enclosed by a covering glass having a refractive index different from n1, and wherein phase boundaries exist between the light-guiding elements. This document also discloses a method for producing such a side-emitting glass element, comprising the following method steps: (i) providing a plurality of optical fiber rods made of glass with a refractive index of n1; (ii) arranging at least one scattering rod made of glass including scattering centers between or within the plurality of optical fiber rods, such that the axes of the optical fiber rods and at least one scattering rod extend at least substantially parallel to each other to obtain a preform; (iii) heating the preform; (iv) drawing the preform to form the side-emitting glass element, such that the outer circumferential surfaces of the optical fiber rods are inseparably bonded to each other and to at least one scattering rod. The method described therein is particularly useful for decorative illumination purposes, for which it is particularly desirable to achieve a radially directed emission effect.

[0021] The object of the present invention is therefore to provide a cost-effective solution for manufacturing and using and reusable diffusers, in particular for cylindrical diffusers and associated illumination systems. Furthermore, on the one hand, they should meet the above-mentioned lateral emission uniformity requirements based on the average intensity of the lateral emission and should generally exhibit a Lambertian emission behavior, in particular for PDT applications, and on the other hand, they should meet the requirements of compatibility with high power densities, in particular in EVLT applications. The method described in DE 10 2012 208 810 A1 represents a basic technology that should be advantageously optimized with regard to providing such diffusers. Summary of the invention

[0022] The objects of the invention are achieved by the independent claims 1 and 27 and advantageous embodiments will be apparent from the dependent claims and the further disclosure of the description and the drawings.

[0023] For this purpose, an illumination system is disclosed, in particular an illumination system for a medical and / or diagnostic system, the illumination system comprising at least one laser light source and an optical waveguide which can be connected to and / or associated with the at least one laser light source at its proximal end, and comprising a diffuser element at the distal end of the optical waveguide, the diffuser element having a longitudinal axis extending perpendicularly from a coupling surface of the optical waveguide into the diffuser element; wherein the diffuser element in its operating state emits light laterally over its active length in a longitudinal axis direction; wherein the diffuser element comprises at least one diffuser matrix, and the diffuser matrix contains at least one scattering element, wherein preferably , the at least one scattering element is arranged along the longitudinal axis of the diffuser substrate substantially parallel to the longitudinal axis or is arranged at a certain angle to the longitudinal axis of the diffuser substrate; and wherein a component for homogenizing the emission intensity along the longitudinal axis of the diffuser substrate is arranged at the distal end of the diffuser substrate and / or at least partially or over several sections thereof around the transition region between the optical waveguide and the diffuser substrate and / or the diffuser substrate itself; wherein the illumination system exhibits, in its operating state, an intensity distribution of lateral emission that deviates from the average lateral emission intensity by no more than ±50%, preferably by no more than ±30%, and most preferably by no more than ±5%.

[0024] In the context of the present invention, lateral emission refers to emission having a directional component emanating from the longitudinal axis of the diffuser substrate and extending in a radial direction. Lateral emission intensity refers to the intensity of this emission.

[0025] Furthermore, this object can advantageously be achieved by arranging at least one scattering element along the entire longitudinal axis of the diffuser substrate substantially parallel to said longitudinal axis, the scattering element having a uniform cross-sectional shape or, in the case of a tapering of the diffuser substrate, at an angle to the longitudinal axis. The at least one scattering element can also advantageously be tubular and can in particular be arranged coaxially with the longitudinal axis.

[0026] The plurality of scattering elements may be arranged around the longitudinal axis of the diffuser substrate in a specific predeterminable geometric arrangement, preferably in a regular pattern, most preferably in a circular pattern around the longitudinal axis. Thus, preferably, the plurality of scattering elements arranged at an angle intersect at a vanishing point outside the diffuser substrate.

[0027] Means and / or measures for homogenizing the lateral emission along the longitudinal axis are preferably arranged at the distal end of the diffuser base and / or in a transition region between the optical waveguide and the diffuser base, which at least partially or sectionally and / or substantially completely enclose the diffuser base.

[0028] By way of example, such components include a sleeve, a cover, a cap and / or a layer at the distal end of the diffuser, thereby preventing emission from the distal end forwards and thereby reflecting it back and thus making it available again in the scattering process in the diffuser matrix, and on the other hand, thereby avoiding stray light effects and / or light reflections at the distal end of the diffuser matrix.

[0029] The same applies to the transition region between the optical waveguide and the diffuser base. Stray light effects and / or light reflections may also occur here, which can be suppressed by appropriately effective elements, such as sleeves and / or layers at this location.

[0030] The optical waveguide may include a single fiber, such as a single mode or multimode optical fiber, including a core having a core diameter and a cladding, or may include a fiber bundle having a fiber bundle diameter.

[0031] This makes it possible to provide a reproducible and also cost-optimized diffuser element which in its operating state exhibits a homogeneous emission for medical use as mentioned in the introduction.

[0032] According to a preferred embodiment variant, it is contemplated that the scattering elements in the diffuser matrix are arranged in a pattern uniformly distributed radially around the longitudinal axis of the diffuser matrix, while the core region around the longitudinal axis has no or significantly reduced number of scattering elements per unit area compared to the number of scattering elements per unit area outside the core region, so that the scattering elements are mainly arranged outside this core region in the matrix. This ensures that the injected light, which is usually injected with a small NA (<0.3, usually about 0.2), is not immediately scattered on the scattering elements. On the other hand, the core region with almost no scattering elements allows sufficient light to propagate to the far end of the diffuser matrix without being scattered. This allows, on the one hand, to reduce the intensity near the injection site (the near end of the diffuser matrix) and, on the other hand, to increase the intensity near the far end of the diffuser matrix.

[0033] According to another preferred embodiment variant, it is contemplated that the diffuser matrix comprises a matrix having different refractive indices n1 and n1' relative to its cross-sectional area, in particular between the core region and the peripheral region of the matrix in which the scattering elements are embedded. This allows, for example, to influence the numerical aperture NA within the core region with the matrix refractive index n1 and outside the core region of the matrix with the refractive index n1'. Furthermore, the propagation of light in the diffuser matrix and thus the excitation of the scattering centers can be adjusted to the desired emission characteristics over the length of the diffuser. Furthermore, any desired cross-sectional geometry of the core region with the refractive index n1 can be realized during production, i.e. for example essentially circular, but also polygonal or star-shaped.

[0034] If the diameter of the diffuser matrix in which the scattering elements are embedded is equal to or larger than the core diameter or fiber bundle diameter of the optical waveguide, the homogenization of the lateral emission intensity can be promoted.

[0035] It has been found to be particularly advantageous if the ratio between the core diameter of the optical waveguide or the fiber bundle diameter and the diameter of the precursor is ≤1.0 to 0.7, most preferably ≤1.0 to 0.8.

[0036] A core diameter or fiber bundle diameter which is only slightly smaller than the matrix diameter allows the intensity peak at the injection site (transition region from the optical waveguide to the diffuser matrix) to be reduced.

[0037] In contrast, a core diameter or fiber bundle diameter that is significantly smaller than the diameter of the parent diffuser matrix (ie, ratio < 0.8) may result in reduced intensity at the injection site, which may also be advantageous for certain requirements.

[0038] Furthermore, it has been found that a particularly robust mechanical connection or bond between the optical waveguide and the diffuser matrix can be achieved, for example by adhesive bonding, if the ratio is between 1 and 0.9.

[0039] Ideally, the diffuser element has a reflector surface at the distal end of the diffuser substrate, i.e. in the form of a directional reflective surface (e.g. a metallic reflective surface with a metal coating comprising, in particular, Al, Ag, Au) or a diffuse reflective surface (e.g. a substrate comprising a white paint layer that reflects light that has passed through the diffuser substrate back). This allows at least partially compensating or correcting the usually exponential decay in the intensity of the light emitted laterally along the diffuser substrate. Thus, the amount of light that can be provided at a constant scattering rate can be varied or adjustable at least sectionally, so that the lateral emission can be homogenized.

[0040] Short polished metal wire segments with a length of approximately 0.5 to 2 mm and made, for example, of aluminum or gold, which are in direct contact with the diffuser substrate and form a heat sink, have proven to be particularly effective reflectors, especially also for avoiding hot spots. Hot spots are local increases in light intensity which, for example, if absorbed at interfaces, can lead to undesirable local temperature increases.

[0041] Furthermore, sputter-deposited or vapor-deposited dielectric reflective layers have been found to be particularly advantageous on the distal end of the diffuser substrate; they can consist of multiple layers and can be matched in terms of reflectivity to the wavelength of the light used, meaning that they can have a maximum at the wavelength to which they are matched. On the one hand, this achieves an ideal back reflection of the light injected during the operating state and, on the other hand, avoids hot spots.

[0042] Alternatively, it is also conceivable to implement the reflector by means of a silver layer with back passivation, which has a good broadband reflectivity. Such a layer is particularly robust and is able to suppress interfering reflections that can lead to local excessive intensities and hot spots. In this way, in particular, very broadband reflectors can be implemented, which have very good reflection properties both in the visible spectral range (VIS) and in the IR / MIR range (for example between 1 μm and 2.5 μm wavelength). Back passivation prevents oxidation of the silver layer.

[0043] If the reflector surface is concave or convex, this allows light propagating almost parallel to the longitudinal axis to be at least partially reflected back at a steeper angle relative to the longitudinal axis and thus scattered more frequently at the scattering element, so that the output efficiency of the lateral emission increases towards the far end of the diffuser element, which means that the distribution of the emission intensity is more uniform.

[0044] The reflector surface may also be a hollow body or may be in the form of a cover or cap which is closed at one end and has a reflective surface facing the cavity or transparent body. These may be cylindrical caps, for example made of plastic, glass or fused quartz, which may be arranged adjacent to the distal end of the diffuser substrate and may be designed to be directionally reflective and / or diffusely reflective at least on several sections of at least one of its surfaces, for example by having a mirror coating or being provided with a white paint layer. The mirror coating may be implemented as a reflective film or a reflective coating, for example a vapor deposited coating.

[0045] Also advantageous is a metal cap, which thereby encloses a cavity adjacent to the distal end of the diffuser substrate. The cavity formed in this manner can also be filled with a liquid, solid or solidified material, which allows, for example, to adjust the refractive index and / or to couple the cap to the distal end. It can also be expected that the cap directly terminates the distal end without defining the cavity. Particularly advantageously, such a cap surrounds the diffuser substrate at least partially in the radial direction or on several sections of the diffuser substrate, for example, on a length of 0.5 to 2 mm. Such elements allow, on the one hand, to avoid stray reflections, and on the other hand, if there is a cavity, the numerical aperture of the radiation reflected back into the diffuser substrate can be adjusted according to the length of the cavity or the transparent body. Therefore, the reflector surface is concave or convex and / or in the form of a body and / or a cover, which is directly adjacent to the diffuser substrate or spaced apart from it so as to define a cavity between the reflector surface and the distal end of the reflector (in the form of a hollow body closed at one end).

[0046] Furthermore, the metal cap offers the advantage that it can be used as an X-ray marker, for example. This allows the exact location of the diffuser element in the patient's tissue to be visualized by X-ray-based imaging during intervention or treatment. Depending on the imaging technique applied, a properly designed cap may have at least a similar effect.

[0047] In a preferred embodiment, the diffuser element comprises a junction area between the proximal end of the diffuser substrate and the distal end of the optical waveguide, which junction area is produced by gluing, bonding or pressing to form a positive fit and / or material bonding and connects at least the diameter of the diffuser substrate with the core diameter or fiber bundle diameter of the optical waveguide.

[0048] In order to match possibly different thermal expansion coefficients, it is advantageous to additionally provide an intermediate medium in the junction area between the proximal end of the diffuser substrate and the distal end of the optical waveguide. This can be, for example, a transition glass or a solder glass. On the other hand, this can also be a transparent, permanently elastic adhesive. Furthermore, optical elements can be arranged in the junction area, or the junction area can be designed to define optical elements, for example, for modifying the guidance of the light beam and / or the guiding of the light by geometric adjustment or refractive index matching.

[0049] In order to increase the mechanical stability, in particular of the joint between the diffuser element and the optical waveguide, it is advantageous if the joint area is covered by a covering material, for example a sleeve or a tube. The sleeve or tube can be made of plastic, glass, ceramic or a metal or alloy, for example nickel silver, titanium or stainless steel, so that it is at least partially transparent, translucent and / or opaque and / or reflective at least in sections thereof. In one case, this can be a thin-walled glass sleeve, which particularly enhances the mechanical stability. Furthermore, a metal sleeve has the advantage that it can also be used as an X-ray marker, which allows, for example, to visualize the exact position of the diffuser element in the patient's tissue during an intervention or during a treatment. According to a variant, it is contemplated that the sleeve is defined by a rigid tube segment, for example by Glass or fused silica, and / or defined by a flexible tubing, such as a silicone tube. If the tube segments and / or the tubing also contain scattering centers, this allows the above-mentioned homogenization of the emission characteristics to be further improved.

[0050] A particularly preferred embodiment variant of the diffuser element provides that the diffuser base with a reflector surface at the distal end as described above or a variant thereof and with a junction zone comprising a sleeve or a variant thereof as described above is provided with a transparent and / or translucent, dyed or colorless sheath which encloses the diffuser base at least partially or in sections. On the one hand, mechanical protection can be achieved in this way. On the other hand, by suitable selection of materials, in particular if they contain scattering centers, the emission characteristics can be further optimized with regard to the homogeneity of the lateral emission intensity. This allows, for example, to promote Lambertian light emission.

[0051] In a preferred embodiment variant, the sheath is at least partially made of one or more thin-walled heat shrink tubes. On the one hand, such heat shrink tubes can cause additional diffuse scattering effects, thereby promoting Lambertian emission. On the other hand, mechanical protection can be achieved in this way and possible fragmentation in the event of damage to the diffuser can be prevented. For example, thin-walled heat shrink tubes made of white dyed PET with a wall thickness of about 5 to 15 μm have been proven to be suitable for this purpose. In order to suppress reflections, thin-walled black or colored heat shrink tubes can also be provided in parts. The color can be selected so that the applied wavelength is particularly well absorbed. In addition, such heat shrink tubes are embodied as biocompatible.

[0052] In order to compensate, minimize or prevent any irregularities on the surface of the sheath or diffuser substrate, such as dirt, particles, roughness, etc., which may lead to undesirable uneven emission in operation, an immersion liquid can advantageously be applied or introduced between the diffuser substrate and the sheath.

[0053] The diffuser matrix can be essentially composed of a matrix made of transparent plastic, glass, fused quartz or glass ceramic, and the scattering elements embedded therein can be composed of, for example, porous or colored or, for example, white dyed plastic in the case of a matrix made of plastic, pores, particles, porous or colored or, for example, white dyed or containing inhomogeneities of glass or glass ceramic elements and microcrystals contained therein in the case of a glass matrix, pores, porous fused quartz or ceramic or polycrystalline particles in the case of a matrix made of fused quartz, or pores, particles, porous or colored or, for example, white or containing inhomogeneities of glass or glass ceramic elements and microcrystals contained therein in the case of a transparent glass ceramic matrix. Moreover, the combinations of scattering elements mentioned as examples can advantageously be included in the corresponding matrix. In the case of a glass or glass ceramic matrix embodiment, the inhomogeneities of the glass or glass ceramic that can define the scattering elements include, for example, phase separation, segregation and / or particle merging, seeding, and / or microcrystals. The concentration of the scattering elements in the scattering region should be 10 ppm to 1000 ppm, and preferably 20 ppm to 100 ppm. Here, the concentration values ​​in ppm refer to the ratio of the mass fraction of the scattering particles relative to the components of the corresponding material (in particular plastic, glass matrix or fused silica matrix) in which the scattering particles are embedded. The diameter of the corresponding scattering elements defined thereby (i.e. pores, particles, porous or colored or, for example, white-dyed or inhomogeneous glass or glass ceramic elements, and the microcrystals contained therein) is preferably 10 nm to 1000 nm, most preferably from 100 nm to 800 nm.

[0054] For example, plastic-based embodiments of diffuser substrates made of PMMA, PET or PC plastic rods can already be implemented at low processing temperatures during their production or shaping. However, diffuser substrates produced in this way exhibit a rather low thermal resistance and are therefore more suitable for applications with low laser powers. In addition, they are only suitable for applications in the visible spectral range (VIS), since plastics generally exhibit high absorption in the NIR and IR ranges.

[0055] Glass-based embodiments are much more robust in this respect and, most importantly, thermally stable, so that greater laser output powers can be applied. Suitable components considered for the production of the diffuser matrix include, for example, glass rods made of N-BK7, optical boron crown glasses of the applicant, borosilicate glasses, or lead-free or heavy metal-free glasses (such as high-quality optical glass fibers for dental rods such as for endoscopes or for curing dental fillings). The latter can meet future RoHS requirements. Such glasses are described in DE 10 2012 100 233 A1 and DE 10 2013 208 838 B4 of the applicant.

[0056] From the range of lead-free tin silicate glass or alkali metal zinc silicate glass, examples of such glasses for optical fiber rods and diffuser matrix precursors have the following compositions (expressed in weight percent as oxides): from arrive <![CDATA[B2O3]]> 0 24 <![CDATA[SiO2]]> 23 62.1 <![CDATA[Al2O3]]> 0 10 <![CDATA[Li2O]]> 0 10 <![CDATA[Na2O]]> 0 18.5 <![CDATA[K2O]]> 0 25.7 BaO 0 57.8 ZnO 0 40 <![CDATA[La2O3]]> 0 25 <![CDATA[ZrO2]]> 0 10 <![CDATA[HfO2]]> 0 14.2 <![CDATA[SnO2]]> >0 2 MgO 0 8 CaO 0 8 SrO 0 24.4 <![CDATA[Ta2O5]]> 0 22 <![CDATA[Y2O3]]> 0 11.9 <![CDATA[Rb2O]]> 0 15 <![CDATA[Cs2O]]> 0 21 <![CDATA[GeO2]]> 0 7.5 F 0 2 <![CDATA[ΣR2O]]> 5 20 ΣMgO,CaO,SrO,ZnO 20 42

[0057] The cladding tube that can be arranged around the optical fiber rod to subsequently form a cladding and / or as a sheath of a preform is preferably made from one of the following groups 1 to 4, containing the following components (expressed in weight percentage as oxides): Group 1 Group 2 Group 3 Group 4 <![CDATA[SiO2]]> 70-78 63-75 75-85 62-70 <![CDATA[Al2O3]]> 5-10 1-7 1-5 1-10 <![CDATA[B2O3]]> 5-14 0-3 10-14 >15 <![CDATA[Li2O]]> 0-2 0–1 0–3 0-2 <![CDATA[Na2O]]> 0-10 8-20 2-8 0-10 <![CDATA[K2O]]> 0-10 0-6 0-1 0-10 MgO 0-1 0-5 0 0-5 CaO 0-2 1-9 0 0-5 SrO 0-1 0 0 0-5 BaO 0-4 0-5 0 0-5 F 0-1 0-1 0 0-1 Cl 0-1 0-1 0 0-1 <![CDATA[Fe2O3]]> 0-2 0-2 0-2 0-2

[0058] In principle, it is also possible to use radiopaque glass or corresponding transparent glass ceramics for the diffuser matrix or for the embedded scattering elements and / or for the cladding tube. This has the advantage that the diffuser matrix can be visualized in its entirety, at least partially or in sections in the X-ray image, so that the position of the diffuser in the patient can be determined.

[0059] For applications with wavelengths between 0.8 μm and about 2.2 μm, such as the EVLT applications mentioned in the introduction, special IR transparent glasses can also be used, such as the glass designated N-PK52a, a phosphate crown glass or IRG7, a lead silicate glass of the applicant.

[0060] Methods based on fused silica can particularly address applications in the UV and / or IR range up to a wavelength of about 2.5 μm, if the fused silica has particularly few OH groups. Another advantage that may be mentioned here is the extremely high heat resistance and extremely low intrinsic absorption of fused silica, which in particular allow higher laser output powers of up to 50 W in applications. In addition to scattering elements made of porous fused silica, scattering elements made of or comprising ceramic pigments such as titanium dioxide, zirconium oxide or aluminum oxide can also be used. Diffuser matrices based on fused silica can be bonded particularly well to optical waveguides made of fused silica fibers, which consist of a core and a cladding, which have slightly different refractive indices. The cladding can also be made of organic materials, such as fluoroplastics, PMMA or polyimide. However, the manufacturing process of the diffuser matrix requires significantly higher drawing temperatures than for glass-based methods.

[0061] Glass-ceramic-based embodiments for the diffuser substrate and / or scattering element can be made of, for example, transparent aluminosilicate high quartz solid solution glass-ceramics for fireplace panels or cooking countertops, which have extremely strong thermal shock resistance and show high spectral transmittance down to about 2.5 μm. Suitable scattering elements include, for example, keatite glass-ceramics, which can be made from high quartz solid solution glass-ceramics by a suitable heat treatment process. In addition, cordierite glass-ceramics or magnesium aluminum silicate glass-ceramics are suitable as diffuser substrates and / or scattering elements.

[0062] When the diffuser matrix is ​​made of an optical fiber rod made of a borosilicate glass rod, a tin silicate glass rod or an alkali metal zinc silicate glass rod and the scattering element is made of a white glass rod (which is enclosed by a cladding tube made of borosilicate glass, tin silicate glass or alkali metal zinc silicate glass to form a preform), a particularly preferred diffuser matrix can be obtained in terms of its manufacturing process.

[0063] In a refinement of the invention, both the diffuser substrate and the cladding tube can be made of the same type of glass. The refractive index of the cladding tube is preferably not greater than the refractive index of the parent glass, and most preferably, the two refractive indices are equal. This promotes the emission of light scattered in the diffuser.

[0064] This allows a cost-effective process for manufacturing diffusers that can be obtained in almost any length and with uniform emission intensity. In addition, such diffusers can also be adapted to specific applications in terms of other geometric parameters (such as diameter) and can be used as semi-finished products, which can then be cut to length and optionally post-processed for specific applications.

[0065] In order to make the intensity distribution or uniformity of the radiation emitted laterally over the length of the diffuser element or diffuser base in the operating state conform to a predetermined tolerance band, it may be necessary to make the diffuser base from a plurality of preform parts drawn to the diameter of the diffuser base during the drawing process, and the diffuser base can be composed of a plurality of parts, and the parts can be made of different preforms, which contain different numbers and arrangements of scattering elements. The diffuser parts can be combined by bonding or gluing using a refractive index matching adhesive to form the diffuser base, and in one embodiment the scattering effect is advantageously lowest in the first diffuser part into which the light is injected. Then, in the individual downstream diffuser parts in the direction of light propagation in the diffuser base, the scattering effect is enhanced. In this way, it is possible to keep the intensity of the lateral emission consistent within the tolerance band in the operating state.

[0066] If, after the drawing process, parts of the diffuser matrix are subjected to a heat treatment, in particular a gradient heat treatment, at least partial compensation of the usually exponential decay in intensity can further be achieved. Such a gradient heat treatment makes it possible to subsequently influence the scattering element along its extension length in the diffuser matrix with respect to the scattering effect of the diffuser matrix. For example, segregation processes in white glass rods used as scattering elements can be altered by such a gradient heat treatment. In the case of scattering elements based on glass ceramics, it is possible to influence the crystal formation and crystal growth as well as the grain size and distribution thereof along the longitudinal axis of the diffuser matrix.

[0067] In order to reduce unwanted scattering, stray light effects and / or light reflections in particular in the transition region from the light guide to the diffuser substrate or at the distal end of the diffuser substrate, it can further be expected that, according to a further preferred embodiment variant, the scattering element exhibits a reduced scattering effect at the proximal end close to the coupling surface of the diffuser substrate and / or at the distal end in the immediate vicinity of the reflector surface compared to the scattering effect along the diffuser substrate. This can be achieved, for example, by additional exposure to heat during the bonding of the proximal end of the diffuser substrate to the light guide. For example, local segregations (for example, phase separation, devitrification) present in the white glass rod used as scattering element can be at least partially modified (for example, reduced or even reversed) in this way. The latter (reversal) will reduce the scattering effect in this region. Moreover, the distal end of the diffuser substrate can be heated and can thereby be reformed, for example, into a convex shape and / or at least a rounded shape. In addition, the devitrification that causes the scattering can also be at least partially changed and, for example, can even be undone. In this case, a reduction in the undesirable scattering that manifests itself as a hot spot in this region can also be achieved by this additional heat treatment process.

[0068] If the diffuser substrate is drawn at least partially or in sections into a conical shape during the drawing process by varying the drawing rate, the drawing temperature and / or the drawing force (e.g. so that after the cutting process a diffuser substrate is obtained which tapers at least partially or in sections), it is possible to achieve an additional at least partial compensation of the intensity drop of the light emitted laterally in the operating state. For example, a conically tapered diffuser substrate is obtained which, due to the taper, leads to an angular expansion of the light beam, so that the light propagates a greater distance and thus causes a stronger scattering in the longitudinal direction of the diffuser substrate. The scattering elements, which were originally arranged parallel to the longitudinal axis when the preform was produced, no longer extend parallel to the longitudinal axis of the diffuser substrate within the range of the taper, but at an angle thereto, so that they ideally intersect at a common vanishing point.

[0069] Furthermore, further subsequent processes can advantageously take place in which the intensity distribution of the lateral emission of the diffuser base body and / or the diffuser element can be corrected or adjusted.

[0070] These include in particular processes which, on the one hand, allow at least locally to modify the properties of the material in the volume and / or on its surface, such as the refractive index and / or its composition (e.g. in the form of colloidal segregation and / or nucleation and / or crystallization) and / or, on the other hand, allow to remove material or to modify the material deposition in almost any geometry and arrangement. These include, for example, laser processing techniques which allow, for example, by using short pulses or CO2 lasers, to introduce modifications of the refractive index or to create structures in the volume, for example in cavities and / or on surfaces.

[0071] In addition, printing processes can be used to apply or produce structures, for example grid patterns on the surface of the diffuser substrate and / or the diffuser element, for example using printable organic or ceramic inks containing suitable pigments, or using glass flux-based inks, optionally with corresponding subsequent heat treatment. Photolithographic techniques and processing steps are also feasible, such as those used, for example, for volume or surface structuring of photosensitive or photostructurable glasses and glass ceramics. In addition, the diffuser substrate and / or the diffuser element can also be subjected to wet or dry chemical etching on their surface, optionally if necessary, and in this case, photolithographic processing steps can also be used. Mechanical and / or abrasive processes (such as grinding, lapping or sandblasting) can also be used for structuring, in particular for roughening the surface of the diffuser substrate and / or the diffuser element.

[0072] The exemplary techniques or processes presented can also be used in combination.Thus, a diffuser element and / or a diffuser matrix which can be produced in such a way can have a structure at least partially or in sections in its volume and / or on its surface.

[0073] According to another advantageous embodiment variant, it is contemplated that the diffuser substrate has a coating which contains scattering particles at least partially and / or in sections and / or that the diffuser substrate has an additional sheathing made of tinted glass or tinted plastic at least partially and / or in sections. Boron nitride (BN) coatings are examples of such coatings which additionally promote Lambertian emission characteristics and in particular reduce forward emission in the direction of light injection. Other coatings of this type can be made of, for example, titanium oxide, calcium carbonate or zirconium oxide.

[0074] The additional jacket can be embodied, for example, as a white glass tube which contains the scattering element in its glass matrix.

[0075] For example, a colored glass tube can be provided as an additional sheath in the junction area near the joint between diffuser substrate and optical waveguide or near the intermediate medium, and its coloring and strength can be selected so that in particular the used light wavelengths are suppressed or even blocked.

[0076] This can be used to suppress unwanted reflections and thus unwanted side emissions. For example, a suitable sheath made of plastic contains dyed silicone or PTFE tubing. In another variant, it is contemplated that a dyed glass rod is bonded to the diffuser substrate or its cladding tube (which absorbs wavelengths of light), in particular in order to suppress forward emissions at the far end of the diffuser. Similar dip coatings made of silicone or a suitable plastic can also be used advantageously.

[0077] A significant challenge lies in the manufacture of a diffuser matrix according to the invention having an illumination distribution suitable for the intended use, in particular the uniformity of the lateral emission intensity in the operating state.The method for producing a diffuser matrix according to the invention is therefore also an advantageous further aspect of the invention.

[0078] A method for producing a diffuser substrate, in particular for an illumination system as described above, is specified, the diffuser substrate comprising at least one scattering element, wherein the at least one scattering element is preferably arranged along a longitudinal axis of the diffuser substrate substantially parallel to the longitudinal axis or arranged at an angle to the longitudinal axis of the diffuser substrate, the method comprising the following method steps: - providing a plurality of optical fiber rods made of glass having a refractive index n1 and / or n1'; - arranging a plurality of optical fiber rods having a refractive index n1 and / or n1′ and at least one scattering rod made of glass or glass ceramic and comprising scattering centers so that the longitudinal axes of the optical fiber rods and the at least one scattering rod extend at least substantially parallel to each other to obtain a preform; - heating the preform; - Drawing a preform to form a diffuser matrix, so that the outer circumferential surfaces of the optical fiber rods are inseparably bonded to each other and to at least one scattering rod to form a shape fit, in particular fused to each other, so as to form a matrix of the diffuser matrix, the diffuser matrix containing at least one scattering element formed by at least one drawn scattering rod embedded therein and / or adjacent to it.

[0079] Thus, a plurality of optical fiber rods made of glass with a refractive index of n1 or n1' are provided. Depending on the irradiation distribution to be achieved, at least one or more scattering rods made of glass or glass ceramic and containing the above-mentioned scattering centers are provided in the required number and arranged adjacent to or between the optical fiber rods, thereby forming an arrangement of optical fiber rods and scattering rods, wherein the longitudinal axes of the optical fiber rods and the scattering rods are advantageously arranged substantially parallel to each other. The scattering rods can be distributed in the arrangement according to a pattern depending on the desired irradiation distribution. This arrangement is fixed by suitable components and thus forms a preform.

[0080] In a subsequent method step, the preform is heated and drawn to form a side-emitting glass element, so that the optical fiber rod and at least one scattering rod are inseparable from each other at their outer circumferential surface. Temperature control during drawing is such that a phase boundary is maintained between the optical waveguide elements. This can be achieved in particular by keeping the drawing temperature below the melting temperature of the glass of the optical fiber rod, so that they are sintered together (in particular at the sintering temperature). According to the invention, complete fusion of the optical fiber rod is avoided. The preferred shape fit of the optical fiber rod and (if necessary) the scattering element can also be achieved by temperature control. The glass element obtained in this way can directly define the diffuser matrix. However, in particular, the diffuser matrix and / or its parts can also be obtained by cutting to a certain size, for example cutting to the length of the produced glass element. The matrix of the diffuser matrix is ​​defined by the drawn optical fiber rods joined together in a rigid fit, and at least one scattering element containing scattering centers is embedded therein, and at least one scattering element has been formed from the drawn scattering rods also by shape fit, basically according to its arrangement in the preform.

[0081] In an advantageous embodiment, as described above, the fiber rods are not completely fused together, nor are the diffuser rods completely fused to at least one of the fiber rods. Therefore, a phase boundary may also exist between the diffuser rods and the fiber rods, and thus will be maintained in the diffuser element of the matrix and diffuser matrix thus formed. This embodiment can be achieved when the softening temperature of the glass of the fiber rods is equal to or lower than the softening temperature of the diffuser rods.

[0082] An equally advantageous embodiment foresees that the optical fiber rods are not completely fused together and that a phase boundary exists between them, but that at least one scattering element is fused to at least one optical fiber rod. This can be achieved by selecting the softening temperature of the glass of the scattering rod to be lower than the softening temperature of the glass of the optical fiber rod. It has proven to be advantageous to reduce the softening temperature of the glass of the scattering rod by at most 50 K, in particular by at most 30 K.

[0083] When drawn, the fiber rod becomes the parent and the scattering rod becomes the scattering element of the glass element. Thus, the fiber rod consists of glass with a refractive index of n1 and is not individually enclosed by a cladding glass with a refractive index of n2.

[0084] The member for fixing the preform arrangement containing the optical fiber rods and the scattering rods can be, for example, a clamp, which is subsequently removed. However, preferably, a cladding tube consisting of a glass with a refractive index of n2 is used. In this embodiment, the arrangement of the optical fiber rods and the scattering rods is combined inside the cladding tube. The cladding tube is most preferably closed at one end. The cladding tube seals the above-mentioned preform at least around the outer circumference of the preform. During heating and drawing, the cladding tube softens and engages on the arrangement of the optical fiber rods and the scattering rods, thereby forming a cladding around the glass element. The product obtained by heating and drawing can also be cut and / or further processed to obtain a diffuser matrix.

[0085] By varying the rate, temperature and / or force parameters during the drawing process of the preform, a conical diffuser substrate can be obtained which tapers at least partially or over several sections thereof, optionally after cutting to size. At least within the conical region, the scattering elements no longer extend parallel to the longitudinal axis of the diffuser substrate, but at an angle thereto.

[0086] Furthermore, advantageously, a method is proposed for at least partially or segmentally configuring a diffuser substrate comprising at least one scattering element, in particular for adjusting the intensity distribution of its lateral emission, wherein the at least one scattering element is preferably arranged along a longitudinal axis of the diffuser substrate substantially parallel to the longitudinal axis or arranged at an angle to the longitudinal axis of the diffuser substrate and / or the diffuser element; A diffuser substrate having a reflector surface and a joining region is at least partially or over sections thereof enclosed by a transparent or translucent sheath to form a diffuser element; wherein the jacket is preferably defined by rigid pipe segments and / or by flexible pipe elements, wherein the pipe segments and / or pipe elements preferably contain scattering centers which at least locally modify the properties and / or composition at their volume and / or surface and / or form structures of virtually any desired geometry and arrangement therein and / or thereon by material removal or material deposition techniques, the techniques comprising - laser processing techniques, in particular using short pulses or CO2 lasers, which preferably introduce modifications of the refractive index and / or composition or form structures in said volume and / or at said surface; - printing techniques for coating or producing, in particular, grid structures using printable organic or ceramic inks containing suitable pigments or using inks based on glass fluxes; - Wet chemical or dry chemical etching techniques; - Photolithography process; - abrasive mechanical processing techniques; or A combination of these techniques.

[0087] A preferred application of the irradiation system as described above in its various implementation variants is its use in photodynamic therapy (PDT), for example for tumor treatment, for intravenous laser therapy (EVLT) (for example for varicose vein treatment), for laser-induced interstitial thermal therapy (LITT), or in the fields of dentistry, ophthalmology and dermatology, as described in the introduction. In the field of dentistry, applications in wound or periodontal treatment should be mentioned in particular. In addition, there are applications in brain research, where individual areas of the brain can be stimulated by light in order to treat disease symptoms.

[0088] Another application of the illumination system as described above in its various implementation variants is its use in photodynamic therapy (PDT) for tumor treatment, wherein at least one optical waveguide with a diffuser element captures light emitted from other diffuser elements to forward the light via the optical waveguide to a detector for spectral analysis. In this case, in addition to a plurality of light-emitting diffuser-optical waveguides, light-capturing diffuser-optical waveguides are also applied to the patient, and the response to the PDT treatment can be evaluated based on the spectral difference between the injected light and the captured light (see Finlay et al., Proc. SPIE Int. Soc. Opt. Eng. 2014, June 14; 5315: pp. 132-142).

[0089] Furthermore, applications in the industrial sector are also advantageous, for example for the inspection of hard-to-reach places, for example on or in machines, where uniform illumination is particularly important, or in spectroscopy applications, or in biochemistry, where light stimulates biochemical in vitro reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] The invention will now be explained in more detail by means of exemplary embodiments illustrated in the accompanying drawings, in which:

[0091] Figure 1 Schematically illustrates an illumination system including an optical waveguide and a diffuser element in a PDT application;

[0092] Figure 2 is a schematic cross-sectional view of a diffuser element;

[0093] Figures 3a to 3d Different exemplary embodiments of the arrangement of scattering elements in a diffuser matrix are shown;

[0094] Figure 4a and 4b Different exemplary embodiments of scattering elements in a matrix of a diffuser substrate are shown;

[0095] Figures 5a to 5c Different exemplary embodiments of the reflector surface of the diffuser substrate are schematically shown;

[0096] Figures 6a to 6c Different methods of homogenizing the intensity distribution are schematically shown;

[0097] Figure 7 distribution diagrams showing different schematic intensity distributions; and

[0098] Figure 8 is another profile diagram showing the measured intensity distribution;

[0099] Fig. 9 is based on Figure 3a A cross-sectional micrograph of a polished surface of a diffuser substrate;

[0100] Fig.10 is based on Figure 3d A cross-sectional micrograph of the surface of a diffuser substrate prepared only by scoring and breaking;

[0101] Fig.11 shows a cross section through a diffuser matrix 43 having a matrix 43.4 with different refractive indices n1 and n1';

[0102] Fig.12 Shows Figure 2 Detail of a schematic cross-sectional view of a diffuser element. DETAILED DESCRIPTION

[0103] In the following detailed description of the embodiments, the same reference numerals in the drawings refer to the same or equivalent components.

[0104] For better understanding, the following definitions are provided.

[0105] For the purposes of the present disclosure, the term "irradiation system" encompasses light emitting devices, and in particular light emitting devices which are suitable for medical technical purposes and which can be disinfected and / or sterilized at least in sections thereof, in particular when they are intended to come into contact with living tissue.

[0106] The expression "for use in a medical and / or diagnostic system" also covers the presently disclosed illumination system itself as a medical and / or diagnostic system.

[0107] Figure 1 The configuration of an irradiation system 1 according to a preferred embodiment of the present invention is schematically shown. Here, a medical PDT application is explained as an example.

[0108] In the illustrated example, the illumination system 1 comprises a laser light source 10 which, in its operating state, emits light in a specific spectral range. For PDT applications as described in the introduction, the wavelength of the laser emission used matches the previously applied biochemically modified dye (photosensitizer), typically in the visible light range, for example in the green spectral range of 532 nm, or in the red spectral range of, for example, 690 nm.

[0109] The optical waveguide 30 is connected to the laser light source 10 via a connector 20 at its proximal end. Here, the proximal end refers to the end of the optical waveguide 30 where light is injected. The optical waveguide 30 has a diffuser element 40 at its distal end, which is introduced into a tumor tissue 60 formed inside a healthy tissue 50 via a cannula (not shown here). Here, the distal end refers to the other end of the optical waveguide 30, which is generally located at a position far from the proximal end of the optical waveguide 30, and in particular, light is emitted from the other end.

[0110] The laser radiation enters the diffuser element 40 at the diffuser element 40 by light injection 41 and is emitted laterally over the length of the diffuser (light output 42). It is important here that the emission over the length of the diffuser element 40 is as uniform as possible. Intensity peaks should be avoided in particular. The light-induced biochemical reaction, as described in the introduction, ideally induces necrosis of the tumor tissue 60 after the treatment. Usually, a fused silica fiber is used as an optical waveguide 30, and the connector 20 is usually in the form of a coaxial connector known as an SMA connector, in which the fiber is glued into the connector 20. With regard to thermal resistance, a connector 20 with a nickel-silver sleeve can also be advantageous, in which the optical waveguide 30 is accommodated and crimped in a form-fitting manner due to plastic deformation. In addition, in order to obtain higher laser output powers, a connector 20 can also be used in which the fiber end of the optical waveguide 30 is protected by a pyramidal prism, which can be advantageous in the case of incorrect adjustment.

[0111] Figure 2 The configuration of a diffuser element 40 according to a preferred embodiment of the present invention is schematically shown.

[0112] The diffuser element 40 consists of a diffuser matrix 43, which is fixed to the optical waveguide 30 via a bonding area 44. In the above application, the optical waveguide 30 is mainly made of fused silica, comprises a core 31 with a refractive index n1 and a core diameter 31.1 typically between 200 and 600 μm, and a cladding 32 with a refractive index n2 (where n1>n2). Typically, a numerical aperture NA of approximately 0.22 can be achieved in this way. Light injection 41 is achieved via a coupling surface 46 of the diffuser matrix 43.

[0113] In a preferred embodiment, the diffuser substrate 43 having a diameter 43.1 comprises a cladding tube 43.3 and a matrix 43.4 made of a matrix element 43.5 and a scattering element 43.6 embedded therein, or consists of a cladding tube 43.3 and a matrix 43.4 made of a matrix element 43.5, in which the scattering element 43.6 is embedded (not shown here, see Figures 3a to 3d as well as Figure 4a and 4b ). In order to be able to meet the uniformity requirements regarding the lateral emission intensity in the operating state, in one embodiment, the diffuser base 43 includes at least 10 and preferably at least 20 embedded scattering elements 43.6, and preferably no more than 100, because otherwise the assembly of the preform will be too complicated.

[0114] The resulting ratio of the cross-sectional area of ​​the embedded scattering elements 43.6 to the diffuser base 43 is ≤ 0.015, preferably ≤ 0.005, most preferably ≤ 0.002. The scattering elements 43.6 are arranged substantially parallel to the longitudinal axis 43.2 over the entire length of the diffuser base 43.

[0115] In an advantageous embodiment, the diameter of the diffuser matrix 43 is dimensioned to be larger than the core diameter 31.1 or the fiber bundle diameter 31.1 of the optical waveguide 30, so that on the one hand no uncontrolled stray light is injected, for example, into the cladding tube 43.3. On the other hand, the assembly and adjustment of the optical waveguide 30 and the diffuser matrix 43 can be simplified and / or assembly tolerances can be compensated in this way. Thus, the ratio of the core diameter 31.1 or the fiber bundle diameter 31.1 of the optical waveguide 30 to the diameter 43.1 of the diffuser matrix with the embedded scattering elements 43.6 is advantageously ≤1.0, preferably between 1.0 and 0.8. Depending on the desired emission characteristics, a ratio of ≤0.8 can also be provided.

[0116] In the junction area 44 between the proximal end of the diffuser matrix 43 and the distal end of the optical waveguide 30, an optical element can be arranged, which can have a conical shape, for example in the form of a beam forming element, a light guiding element or a fiber optic light cone. This allows geometric adjustment, such as adjustment of diameter differences. Here, the proximal end of the diffuser matrix 43 refers to the end of the diffuser matrix 43 into which the light is injected.

[0117] In order to avoid stray light from the junction area 44 and also for the mechanical stability of the junction area 44, a sleeve 48 made of plastic, glass, metal or ceramic material is provided, which allows light from the optical waveguide 30 to pass in the direction of the longitudinal axis of the optical waveguide 30 and at a specific lateral angle, but blocks light that may enter the proximal end of the diffuser body through the side surface.

[0118] In order to optimize the emission characteristics, a reflector surface 47 is provided at the far end opposite to the near end of the diffuser base 43, which can be a directional reflective reflective component in the form of a metal plate or a thin reflective film (e.g., a carrier film with a vapor-deposited reflective layer or a coating with a reflectivity greater than 95%). A diffuse reflective layer applied, for example, by printing a preferably white paint has proven to be advantageous.

[0119] According to another embodiment variant, it is contemplated that the reflector surface 47 is defined by a short polished line portion made of aluminum or gold, which is in direct contact with the diffuser substrate 43. In addition, this provides a small heat sink, which helps to avoid hot spots. In addition, a sputter-deposited or vapor-deposited dielectric reflective layer consisting of multiple layers and matched in reflectivity to the wavelength of the light used has been found to be particularly advantageous on the far end of the diffuser substrate 43. In the context of the present disclosure, the expression "matched in reflectivity to the wavelength of the light used" indicates that the highest possible reflectivity is achieved at this wavelength by this matching, or even the reflectivity is maximum at the matched wavelength. An example of such a reflective layer is a multilayer system consisting of alternately applied TiO2 and SiO2 layers, which has a reflectivity of >99% in the application wavelength range, for example for red light of (690±10) nanometers. Such a layered system can be adapted to the corresponding application wavelength, i.e. the wavelength matched as above. In this way, on the one hand, an ideal back reflection can be achieved, and on the other hand, hot spots can be avoided. As an alternative or in addition, a silver layer with passivation on the rear side can be provided as reflector surface 47 .

[0120] For further mechanical protection and / or for homogenizing the emission characteristics, a sheath 49 made of a transparent and / or translucent dyed or colorless material (silicone, glass or fused quartz) can be provided, which surrounds the diffuser substrate at least partially or over sections thereof. Additional homogenization can be achieved in particular by translucent materials and / or materials containing scattering centers. For example, a sheath 49 made of silicone, polytetrafluoroethylene (Teflon) or polyether block amide block copolymers (commercially known as ) are suitable. It has been found that a sheath 49 in the form of a thin-walled heat-shrink tubing, for example made of PET, which is applied at least in sections and can include one or more layers, is suitable. In such a way, the light emission 42 according to the Lambertian radiator is further promoted or achieved. Next, the effective length 40.2 of the diffuser element 40 is formed as the distance between the sleeve 48 and the reflector surface 47 and can, for example, extend over the entire length of the diffuser element 40 or over the effective length 40.2 of the diffuser element 40.

[0121] Between the diffuser base 43 and the sheath 49 made of glass or plastic, for example, an immersion layer can be provided between the sheath 49 and the diffuser base 43 to suppress any surface irregularities on the diffuser base 43 that may adversely affect the emission performance, such as dirt, roughness, etc. In view of good applicability, care should be taken to make the refractive index suitable for the glass system, have high transparency and have a sufficiently high viscosity. For example, glycerol or silicone (oil or adhesive) have proven to be suitable for use as an immersion layer.

[0122] In order to avoid interfering reflections, it can additionally be expected that the reflector surface 47 is covered or limited on its circumferential surface by a cover or cap 47.2 surrounding the diffuser substrate 43 over a short length. In this case, the effective length 40.2 corresponds to the distance between the sleeve 48 and this protective cap. If the sleeve 48 or the cap 47.2 is made of metal, a radioactive marking function can be achieved, because the effective length 40.2 or the position of the diffuser element 40 will be visualized in the X-ray image. For PDT applications, the total diameter 40.1 of the diffuser element 40 is usually between 0.8 and 1.2 mm. A diameter 40.1 of slightly less than 1 mm is common. Here, the decisive factor is the diameter of the cannula by which the diffuser element 40 is applied to the patient.

[0123] The diffuser matrix 43 is joined to the optical waveguide 30 in a joining region 44, for example by a bonding process or gluing process using a highly transparent, refractive index matching adhesive. During bonding, the optical waveguide 30 and the diffuser matrix 43 are softened or melted using a corona discharge and / or a laser (usually a CO2 laser) and brought together. Depending on the materials used for the diffuser matrix 43 and for the optical waveguide 30, it may be necessary to use an intermediate medium 45 to match their thermal expansion coefficients. For example, in the case of glass-fused silica welding, the intermediate medium 45 can be a solder or transition glass, or can be an optical adhesive or putty. Mechanical pressing in the form of a sleeve is also conceivable and is advantageously implemented, in which case only the transition is filled with an optical putty to avoid reflection losses. Optical elements can also be integrated or connected to be arranged in the joining region 44 between the proximal end of the diffuser matrix 43 and the distal end of the optical waveguide 30.

[0124] Figures 3a to 3d Different exemplary embodiments of the arrangement of at least one scattering element 43.6 in a diffuser matrix 43 are shown. In each case, the diffuser matrix 43 comprises a cladding tube 43.3 and a mother body 43.4, the scattering element 43.6 being arranged in a preferred manner parallel to the longitudinal axis 43.2 over the entire length of the diffuser matrix 43 (see Figure 2 ) are embedded in the matrix 43.4. The axial extent of individual scattering elements may be smaller than the total length of the diffuser matrix 43.

[0125] Figure 3a An arrangement is shown in which a plurality of scattering elements 43.6 are randomly arranged, more or less evenly distributed over the diameter 43.1 of the diffuser substrate 43, ie a plurality of scattering elements 43.6 are arranged around the longitudinal axis. The scattering elements are preferably arranged in a regular pattern around the longitudinal axis.

[0126] Figure 3b An arrangement is shown in which the individual scattering elements 43 . 6 in particular form an annular array, ie a plurality of scattering elements are provided which are preferably arranged in a circle around the longitudinal axis.

[0127] As Figure 3b Alternative, Figure 3c An arrangement is shown in which only one scattering element 43.6 in the form of a tube segment is embedded in the matrix 43.4, that is, at least one scattering element 43.6 is arranged tubularly around and in particular coaxially to the longitudinal axis. Such an arrangement has the advantage that the production of the preform of the diffuser base 43 is particularly cost-effective and reproducible, since the production process can be greatly simplified in this case.

[0128] In principle, other geometries are also conceivable and can be advantageously implemented for the arrangement of the at least one scattering element 43 . 6 and / or the plurality of scattering elements 43 . 6 , for example hexagonal, square, triangular geometries.

[0129] Figure 3d An arrangement is shown in which the scattering centers 43.6 are more or less evenly distributed in the matrix 43.4, but not in the core region 43.7 around the longitudinal axis 43.2 of the diffuser matrix 43, which means that the number of scattering elements 43.6 per unit area of ​​the cross-sectional area of ​​the diffuser matrix 43 is greater outside the core region 43.7 along the longitudinal axis than inside the core region 43.7.

[0130] The advantage of this arrangement is that laser light, which usually has only a small numerical aperture (NA, typically <0.3), when injected into the diffuser matrix 43 will initially be hardly scattered by the scattering elements 43.6 in the peripheral region surrounding the core region 43.7, and when individual rays reach the scattering elements 43.6 in the peripheral region, they will be scattered only within a short distance from the coupling surface 46 (see Figure 2 ) This allows a reduction in the intensity of the light emitted laterally directly downstream of the coupling surface 46 and thus a homogenization of the intensity distribution along the diffuser.

[0131] In the case where the concentration of scattering elements is constant along the longitudinal axis of the diffuser substrate, the intensity distribution generally exhibits an exponential decay, where I (l) =I0*e-l / k . An advantageous value for k has been found to be one in which k corresponds approximately to the length of the diffuser substrate (40 mm in the specific example). This results in an approximately 1 / e attenuation of the emission intensity emitted laterally along the diffuser substrate in the operating state, which can be corrected by other measures so that the above-mentioned uniformity requirements can be met, in particular for PDT applications. In a preferred exemplary embodiment, with 21 scattering elements each having a diameter of 0.3 mm as starting material for the preform and a matrix diameter of approximately 600 μm (preform initial geometry with a diameter of 34 mm), a k value of 42 mm was determined.

[0132] Figure 4a and 4b Two exemplary embodiments of the structure of a matrix 43 . 4 in a diffuser matrix 43 are schematically shown in a cross section perpendicular to the longitudinal axis of the diffuser matrix 43 .

[0133] Figure 4a An example of a scattering element 43.6 is shown, the matrix of which is embedded in the preform as thin rods between the matrix elements 43.5 in the form of individual rods. In the illustrated example, the scattering element 43.6 fills the gaps (knuckles) of three individual rods as matrix elements 43.5. In the illustrated example, individual glass rods with a diameter of 2 mm are used as matrix elements 43.5 for producing the preform. The scattering element is made of white glass rods with a thickness of 0.3 mm. After the hot drawing process, i.e. after having been drawn to the diameter 43.1 of the diffuser matrix 43, the scattering element 43.6 will have been bonded by welding and will have a triangular cross section, in particular a hyperbolic triangular cross section.

[0134] An embodiment of the scattering element 43.6 in the form of a white glass rod or white glass tube contemplates that scattering centers are defined therein by scattering particles having a scattering particle concentration in the scattering region of 10 ppm to 1000 ppm and preferably 20 ppm to 100 ppm.

[0135] The emission efficiency from the scattering region, ie from the volume of white glass of a scattering rod or a white glass tube, depends not only on the scattering properties of the scattering particles as intrinsic parameters but also on the concentration of the scattering particles in the scattering region itself.

[0136] The concentration value in ppm refers to the ratio of the mass fraction of the scattering particles relative to the white glass component in which the scattering particles are embedded.

[0137] If inhomogeneous regions of white glass are used as scattering centers, there is an alternative embodiment in which the inhomogeneous regions are preferably defined by phase separation and / or segregation of glass components of the glass in which they are embedded.

[0138] The diameter of the scattering centers defined by the inhomogeneous regions is preferably from 10 nm to 1000 nm, most preferably from 100 nm to 800 nm.

[0139] These scattering centers are most preferably spherical. For non-spherical scattering centers, the diameter refers to its largest dimension.

[0140] The glass referred to here as white glass, in which the inhomogeneous regions are embedded as scattering centers, can preferably consist of a silicate glass containing As and Pb. In this case, the scattering centers preferably have a higher Pb and / or As content than the surrounding glass matrix.

[0141] Alternatively, the glass or white glass in which the inhomogeneous regions are embedded as scattering centers may be composed of a fluorine-containing Ca-Zn silicate glass. In this case, the scattering centers preferably have an increased fluorine content compared to the surrounding glass matrix.

[0142] Figure 4b An alternative arrangement is shown in which the diameter of the scattering element 43.6 matrix has the same or smaller dimensions than the diameter of the matrix element 43.5 in the form of the individual rods. Here, before the drawing process, in the corresponding assembled preform, for example, the diameter for the scattering element 43.6 and the matrix element 43.5 in the form of white glass rods is generally in the range of 0.5 mm to 1 mm. After the hot drawing process, that is to say after drawing to the diameter 43.1 of the diffuser base 43, the scattering element 43.6 will have been bonded by welding and will have a hexagonal cross section, for example, in particular a hyperbolic hexagonal cross section.

[0143] The arrangement of the scattering rods in the voids of the preform allows obtaining a greater number of scatterers and therefore a better uniformity for a given fiber rod size and a given cross-sectional portion. After the drawing process, the parent element 43.5 in the form of the diffuser matrix 43 and the scattering elements 43.6 can have a circular, hexagonal, square or triangular cross section, in particular in its hyperbolic variant.

[0144] like Figure 5a and 5b As shown in FIG. , in order to make the intensity distribution uniform, it is contemplated that the reflective surface 47 is formed into a concave shape ( Figure 5a ) or convex ( Figure 5b ). In this way it can be achieved that rays propagating almost parallel to the longitudinal axis 43.2 will be reflected back at a steeper angle relative to the longitudinal axis 43.2 and thus be scattered more frequently at the scattering element 43.6 so that the emission efficiency increases at the distal end of the diffuser element 40.

[0145] The reflector surface 47 at the distal end of the diffuser substrate 43 may also be in the form of a hollow and / or transparent body 47.1 with a cover 47.2 reflecting into the cavity and / or transparent body, such as Figure 5c The cover 47.2 can preferably be in the form of a coating and / or cap with directional or diffuse reflection, which can also directly adjoin the diffuser substrate 43 instead of the cavity and in both cases can radially enclose it at least partially at a short distance at the far end or over several sections on its circumference.

[0146] Therefore, the reflector surface 47 is in the form of a concave or convex reflector surface 47 and / or a reflector surface 47 directly adjacent to the diffuser substrate 43 or defining a cavity (as a body 47.1) between the reflector surface 47 and the distal end of the diffuser substrate 43 and / or in the form of a cover 47.2 in the form of a hollow body closed at one end.

[0147] In order to achieve a further homogenization allowing for an intensity distribution that is as constant as possible along the diffuser, further processing steps can be employed, such as Figures 6a to 6c It is schematically shown in FIG.

[0148] For example, depending on the materials used and the material properties of the scattering elements 43.6 and the matrix 43.4 surrounding them, a continuously varying scattering effect can be achieved, for example, by a gradient heat treatment with a varying temperature load over the length of the diffuser. This allows, for example, to adjust an initially rather low scattering effect directly downstream of the coupling surface 46 and a rather high scattering effect at the other end of the diffuser matrix 43, that is, near the reflector surface 47. Figure 6a This option is schematically illustrated. This allows obtaining a diffuser matrix comprising scattering elements with scattering centers having a scattering center density per unit volume, the scattering center density being different at the proximal end and at the distal end of the diffuser matrix, preferably the scattering center density being greater at the distal end than at the proximal end; most preferably the scattering center density having a gradient.

[0149] Figure 6bA "cascade" method is shown, in which diffuser parts manufactured in a different manner, each characterized by a different arrangement and / or density of scattering elements 43.6 in a matrix 43.4, have been assembled part by part by part by bonding or gluing using a refractive index matching adhesive, to form a diffuser matrix, so that the scattering effect of the first diffuser part, in which the light injection 41 will take place, is designed to be the lowest. By appropriately selecting this part, the scattering effect is then enhanced in the diffuser matrix 43 in the individual diffuser parts in the light propagation direction. In this way, the uniformity of the light emitted in the operating state can be consistently maintained both in the axial direction and in the radial direction within the tolerance band of the stepped emission intensity. Therefore, the diffuser matrix 43 can be formed by a plurality of parts of different diffuser matrices.

[0150] Figure 6c Another possibility of obtaining an intensity distribution that is as constant as possible along the diffuser is shown. The diffuser rod drawn from the preform is formed to taper in several sections by changing the drawing parameters (such as rate, temperature and / or force), followed by cutting and processing at the end. In this way, a conically tapered diffuser base 43 is obtained, which diffuser base 43 causes an angular expansion of the light due to the taper, so that the light propagates a greater distance and therefore produces a stronger scattering in the longitudinal direction of the diffuser base 43. In this case, the scattering elements are still arranged uniformly, ideally extending towards a common vanishing point. Therefore, the diffuser base 43 can be formed to be conical at least partially or in several sections thereof, wherein at least one scattering element 43.6 extends along the longitudinal axis 43.2 of the diffuser base 43 substantially at a certain angle relative to the longitudinal axis.

[0151] The exponential decay in intensity from the proximal end to the distal end of the diffuser substrate 43 that must normally be expected can be at least partially compensated by the above examples and / or combinations.

[0152] Furthermore, as already mentioned above, further subsequent processes are conceivable and can advantageously be implemented which allow the intensity distribution of the lateral emission of the diffuser base body 43 and / or the diffuser element 40 to be corrected or adjusted by structuring the volume and / or its surface.

[0153] Figure 7 A diagram 100 showing different schematic distributions 103 , 104 , 105 of the laterally emitted radiation intensity 101 as a function of the distance 102 from the coupling surface in an operating state is shown.

[0154] A first curve 103 shows a typical exponential decay of the intensity 101 (eg due to the solution of a differential equation for a scattering behavior that is uniform over length, ie has a constant ratio of injected to scattered radiation over a certain length segment).

[0155] By attaching the reflector surface 47 to the distal end of the diffuser substrate 43 (see Figure 2 ), part of the radiation can be reflected back and then provide an additional contribution to the scattering (particularly in the area in front of the reflector surface 47). In mathematical terms, this means the addition of two exponential functions, which corresponds to the second curve 104, also Figure 8 In the description.

[0156] Figure 8 The third curve 105 shown in FIG. 1 represents the intensity distribution for another optimized embodiment of the diffuser substrate 43. By geometrically arranging the scattering elements 43.6 (for example, in particular in combination with Figure 3d As described above, the distribution of the intensity 101 near the coupling surface 46, i.e. at the proximal end of the diffuser substrate 43, can be adjusted to be flat, or even initially rise within or into the range of the intensity tolerance 106, so that overall a relatively small intensity variation or a good uniformity of the lateral emission of the incident light within the range of the intensity tolerance 106 can be achieved substantially over the effective length 40.2 of the diffuser element 40.

[0157] However, intensity peaks 107 may occur in particular at or near the coupling surface 46 and also at or near the reflector surface 47, which may be shielded or minimized, for example, by construction measures such as a sleeve 48 or a cap or cover 47.2, as already described in conjunction with and with reference to Figure 2 and 5c described.

[0158] Figure 8 is another profile 100 showing four measured profiles of the intensity 101 of the laterally emitted radiation in the operating state as a function of the distance 102 from the coupling surface. In each case, a diffuser matrix 43 having a diameter of approximately 600 μm was injected using an optical waveguide 30 having a core diameter 31.1 of approximately 360 μm. Here, the intensity 101 is determined and plotted as a gray value intensity of, for example, a CCD camera.

[0159] Specifically, monochromatic light with a wavelength of 685 nm is used for Figure 8 A Nikon 1V1 camera was used as the camera, and in each case this camera outputted only the red channel.

[0160] like Fig.12As shown, a measurement is performed along a straight line 109 extending parallel to the longitudinal axis 43.2 of the diffuser base 43 at the location of the light exit, in particular at the location of the scattered light. In this measurement, the imaging optical system achieves a measured local resolution of 400 pixels per cm in the direction of this straight line 109. An objective lens with a focal length of 30 mm is used for the imaging optical system, which is operated at an aperture of 5.6 in each case.

[0161] In physical terms, the intensity or intensity distribution disclosed herein and specified in the claims corresponds to brightness, also called luminance, as long as it is measured using an optical system that captures a fixed solid angle, which is implemented at a fixed focal length of 30 mm using an aperture of 5.6.

[0162] Figure 8 The distribution shown is the result of the brightness distribution along line 109 for this measurement.

[0163] However, since a relative value between the average lateral emission intensity of the illumination system and the percentage deviation relative to this average lateral emission intensity is specified for the purposes of the present disclosure, if the intensity, brightness or luminance of a point is measured along the measured straight line 109, the same percentage deviation is obtained for this specified value.

[0164] The average lateral emission intensity is based on the average of all measured values ​​along the straight line 109. However, measurement points located at the beginning and end of the measured segment and where a sharp drop in intensity is observed are not included in the determination of this average. Specifically, for a measurement segment having a length of approximately 40 mm along the straight line 109, the values ​​from the first and last 2 mm are not included in the average.

[0165] Based on a moving average of such deviations, the illumination system in its operating state exhibits a lateral emission intensity distribution deviation of at most ±50%, preferably not more than ±30%, and most preferably not more than ±5%, as will be described in more detail below.

[0166] Here, the moving average refers to the average of ten measurement pixels adjacent to each other on the straight line 109 .

[0167] Since this average is an arithmetic average, ten adjacent pixels may be averaged for each pixel, and these ten pixels may be laterally shifted by one pixel for the next laterally adjacent measurement pixel to be arithmetic averaged again.

[0168] In the illustrated example, the diffuser base 43 has a length of approximately 40 mm. Figure 3dIn the arrangement, 21 scattering elements 43.6 are arranged in the diffuser matrix 43, and in the preform, these scattering elements 43.6 are provided as 0.3 mm thick white glass rods, while the matrix 43.5 is provided as a 2 mm thick optical fiber rod, which is similar to Figure 4a The arrangement shown in .

[0169] For clarity, the curves are shown as moving averages and, in the case of curve 103, the original data are overlaid as an example.

[0170] Curve 103 shows the Figure 3a and Fig. 9 Arrangement of the scattering elements, intensity distribution in the absence of reflector surface 47.

[0171] Curve 104 shows the Figure 3a and Fig. 9 Intensity distribution of a diffuser matrix with a reflector surface 47 in the form of a glued reflective film. When neglecting the steeply rising initial section and the falling end section and thus neglecting any optionally present intensity peaks, an intensity variation of less than ±20% of the mean value is obtained without any additional measurements.

[0172] Curve 108 shows the Figure 3a and Fig. 9 Intensity distribution of a diffuser substrate with a reflector surface 47 in the form of a diffusely reflecting white coating. When the steeply rising initial section and the falling end section and thus any optionally present intensity peaks are neglected, an intensity variation of less than ±10% of the mean value is obtained without any further measurements.

[0173] Curve 105 shows the Figure 3a and Fig.10 The intensity distribution of the diffuser matrix has a reflector surface 47 in the form of a diffusely reflecting white coating. In addition, according to Figure 3d The effect of the arrangement is obvious.

[0174] Fig.11A cross section through a diffuser matrix 43 is schematically shown, wherein the diffuser matrix 43 has a matrix 43.4 with respect to its cross-sectional area, which has different refractive indices n1 and n1' between a core region 43.7 of the matrix and a peripheral region in which the scattering elements 43.6 are embedded. This allows selectively influencing the numerical aperture NA in the core region 43.7 with the matrix refractive index n1 and in the peripheral region of the matrix with the refractive index n1' and thus selectively adapting the propagation of light in the diffuser matrix 43 and thus the excitation of the scattering centers 43.6 along the length of the diffuser matrix 43 to the desired emission characteristics. Furthermore, any desired cross-sectional geometry of the core region 43.7 with the refractive index n1 can be realized during the manufacturing process, that is to say as Fig.11 The substantially circular shape shown or the polygonal or star-shaped shape. For example, a matrix element 43.5 formed by a glass rod with a refractive index n1=1.625 can be used in the core region 43.7, and a matrix element 43.5 formed by a glass rod with a refractive index n1'=1.588 can be used in the peripheral region to implement different numerical apertures in the core region 43.5 and the peripheral region, and in this example, the refractive index n2 of the cladding tube 43.3 is equal to 1.49. In the example, the NA of the core region 43.7 is 0.35, and the NA of the peripheral region is 0.55. This allows the propagation of light to be influenced in a targeted manner and thus the excitation of the scattering centers 43.6.

[0175] Typically, at least one scattering element 43.6 is preferably arranged substantially parallel to the longitudinal axis 43.2 of the diffuser substrate 43, at least in the case where it is in the form of a white glass rod or a white glass tube. This means that, for example Fig.12 As shown in FIG. 4 , for example, the longitudinal axis 43.8 of the white glass rod 43.9 encloses an angle 43.10 of less than 1° with the longitudinal axis 43.2 of the diffuser substrate 43.

[0176] If at least one scattering element 43.6 is arranged along the longitudinal axis 43.2 of the diffuser base 43 at an angle 43.10 to the longitudinal axis of the diffuser base 43 (at least when it is in the form of a white glass rod or a white glass tube), this means that the longitudinal axis 43.8 of the white glass rod 43.9 (e.g. Fig.12 2 of the diffuser substrate 43) encloses an angle 43.10 of less than 10°.

[0177] If the white glass tube defines the scattering element 43.6, the same also applies to the longitudinal axis of the white glass tube (not shown in the figures).

[0178] The illumination system of the invention has the advantage that, on the one hand, the diffuser element 40 with the diffuser matrix 43 can be produced cost-effectively and reproducibly, and on the other hand, the emission characteristics of the emission intensity of the lateral emission in the operating state can be homogenized. In the operating state, the illumination system can have an intensity distribution of the lateral emission that deviates from the average lateral emission intensity by no more than ±50%, preferably no more than ±30%, and most preferably no more than ±5%. This allows, in particular, applications in the field of PDT to be addressed. However, these diffuser elements 40 can also be used for applications with higher laser powers, such as EVLT. Reference numerals list 1 Irradiation system 10 Laser light source 20 Connectors 30 Optical waveguide 31 Core 31.1 Core diameter or fiber bundle diameter 32 Cladding 40 Diffuser element 40.1 Diameter 40.2 Effective length 41 Light Injection 42 Light Emission 43 Diffuser substrate 43.1 Diameter 43.2 Longitudinal axis 43.3 Cladding tube 43.4 Mother 43.5 Parent Component 43.6 Scattering Elements 43.7 Core Region 43.8 The longitudinal axis of the scattering element, in particular the longitudinal axis of the white glass rod 43.9 White glass rod 43.10 Angle 44 Junction area 45 Intermediate medium 46 Coupling surface 47 Reflector surface 47.1 Subject 47.2 Reflective cover 48 Sleeve 49 Sheath 50 Organization 60 Tumor tissue 100 Distribution Map 101 Strength 102 Distance from coupling surface 103 Curve 1 104 2nd Curve 105 The 3rd Curve 106 Strength Tolerance 107 Peak Intensity 108 The 4th Curve 109 Straight Line

Claims

1. An illumination system (1), in particular for use in a medical and / or diagnostic system, the illumination system (1) comprising at least one laser light source (10) and an optical waveguide (30) connectable to and / or associated with the at least one laser light source (10) at its proximal end, and comprising a diffuser element (40) at the distal end of the optical waveguide (30), the diffuser element (40) having a longitudinal axis extending perpendicularly to a coupling surface of the optical waveguide into or within the diffuser element (40); wherein the diffuser element in its operating state emits light laterally to the longitudinal axis over its effective length (40.2); The diffuser element (40) comprises at least one diffuser matrix (43), and the diffuser matrix (43) contains at least one scattering element (43.6), wherein the at least one scattering element (43.6) comprises a scattering center and is arranged substantially parallel to the longitudinal axis (43.2) along the entire longitudinal axis of the diffuser matrix (43), wherein the diffuser matrix has a uniform cross-sectional shape or is arranged at a certain angle to the longitudinal axis in the case of a tapered diffuser matrix; and wherein means for homogenizing the emission intensity along the longitudinal axis (43.2) of the diffuser substrate (43) are arranged at the distal end of the diffuser substrate (43) and / or at least partially or over sections thereof around the transition region between the optical waveguide (30) and the diffuser substrate (43) and / or the diffuser substrate (43) itself; wherein The illumination system exhibits, in its operating state, an intensity distribution of lateral emission which deviates from a mean lateral emission intensity by at most ±50%, preferably by no more than ±30%, and most preferably by no more than ±5%; The diffuser substrate (43) comprises a matrix (43.4) made of transparent plastic, glass, fused quartz or transparent glass ceramic or consists of the matrix (43.4); wherein The scattering element (43.6) includes or consists of the following - in the case of plastic matrices, pigmented or dyed plastics; - in the case of a glass matrix, particles or coloured or tinted or containing inhomogeneities of glass or glass ceramics or glass ceramic elements and the crystallites contained therein; - in the case of a fused silica matrix, ceramic or polycrystalline particles; or - in the case of a transparent glass-ceramic matrix, particles or coloured or tinted or containing inhomogeneities of glass or glass-ceramic or glass-ceramic elements and the crystallites contained therein; or - a combination of corresponding scattering elements (43.6), in, The at least one scattering element (43.6) has a triangular cross section, a hexagonal cross section, a hyperbolic triangular cross section or a hyperbolic hexagonal cross section.

2. The illumination system (1) according to claim 1, wherein A plurality of scattering elements (43.6) are provided and arranged around the longitudinal axis of the diffuser element (40), wherein the scattering elements (43.6) are preferably arranged in a regular, most preferably circular, pattern around the longitudinal axis (43.2).

3. The illumination system (1) according to claim 2, wherein Based on the cross-sectional area of ​​the diffuser matrix (43), the number of scattering elements (43.6) per unit area is greater outside the core region (43.7) along the longitudinal axis (43.2) than inside the core region (43.7).

4. The illumination system (1) according to claim 1, wherein The at least one scattering element (43.6) is tubular and is, in particular, arranged coaxially with the longitudinal axis (43.2) of the diffuser base body (43).

5. The illumination system (1) according to any one of the preceding claims, wherein The diffuser matrix (43) comprises a matrix (43.4) which, relative to its cross-sectional area, has different refractive indices n1 and n1', in particular between a core region (43.7) and a peripheral region of the matrix (43.4) in which the at least one scattering element (43.6) is embedded.

6. The illumination system (1) according to any one of the preceding claims, wherein The optical waveguide (30) comprises a single fiber having a core (31) and a cladding (32), wherein the core has a core diameter (31.1); The diameter (43.1) of the diffuser matrix (43) in the region of the coupling surface is greater than or equal to the core diameter (31.1) of the optical waveguide (30) in the region of the coupling surface (46); or The optical waveguide comprises a fiber bundle (31) having a fiber bundle diameter (31.1), wherein the diameter (43.1) of the diffuser matrix (43) in the region of the coupling surface (46) is greater than or equal to the fiber bundle diameter (31.1) of the optical waveguide (30) in the region of the coupling surface, wherein preferably, the ratio of the core diameter (31.1) of the optical waveguide, in particular the fiber bundle diameter (31.1), to the diameter of the diffuser matrix (43) is between ≤1.0 and 0.7, most preferably between ≤1.0 and 0.

8.

7. An illumination system (1) according to any of the preceding claims, wherein at the distal end of the diffuser substrate (43), the diffuser element (40) has a directionally reflective or diffusely reflective reflector surface (47), which terminates the diffuser substrate (43) and / or surrounds its lateral surfaces at least partially or over several sections thereof.

8. The illumination system (1) according to claim 7, wherein the reflector surface (47) is formed by a polished metal wire segment arranged in direct contact with the diffuser substrate (43); and / or wherein the reflector surface (47) is formed by a sputter-deposited or vapor-deposited dielectric reflective layer on the distal end of the diffuser substrate (43), the dielectric reflective layer consisting of multiple layers and matched in reflectivity to the wavelength of the light employed, preferably having a maximum reflectivity at said wavelength; and / or The reflector surface (47) is embodied as a silver layer with rear-side passivation.

9. The illumination system (1) according to any one of the preceding claims, wherein The diffuser element (40) has a reflector surface (47) which has a concave or convex shape and / or is in the form of a body (47.1) and / or a cover (47.2) which is directly adjacent to the diffuser substrate (43) or is spaced apart therefrom so as to define a cavity between the reflector surface (47) and the distal end of the diffuser substrate (43) in the form of a reflective hollow body closed at one end.

10. The illumination system (1) according to any one of the preceding claims, wherein A junction area (44) is provided between the proximal end of the diffuser substrate (43) and the distal end of the optical waveguide (30), and an optical element and / or an intermediate medium (45) is arranged in the junction area (44); Preferably, the joining region (44) is at least partially or in sections thereof covered by a covering material, in particular by a sleeve (48).

11. The illumination system (1) according to any one of the preceding claims, wherein The diffuser substrate (43) with the reflector surface (47) and the junction area (44) is at least partially or in sections thereof enclosed by a transparent or translucent, colorless or dyed sheath (49); wherein the sheath (49) is preferably formed by rigid tube sections and / or flexible tube pieces, wherein the tube sections and / or tube pieces preferably contain scattering centers, wherein, The jacket (49) is preferably at least partially made of one or more thin-walled heat shrink tubings.

12. The illumination system (1) according to any one of the preceding claims, wherein In the case of a glass or glass ceramic matrix embodiment, the inhomogeneities of the glass or glass ceramic defining the scattering element (43.6) include phase separation, segregation and / or particle merging, seed crystals and / or microcrystals.

13. The illumination system (1) according to any one of the preceding claims, wherein The diffuser substrate (43) is made of borosilicate glass, phosphate crown glass, lead silicate glass, tin silicate glass or alkali zinc glass, and the scattering element (43.6) is formed by a white glass rod, enclosed by a cladding tube (43.3) made of borosilicate glass.

14. The illumination system (1) according to any of the preceding claims, wherein the diffuser matrix (43) is made of a plurality of parts consisting of different diffuser matrices (43) according to any of the preceding claims.

15. The illumination system (1) according to any one of the preceding claims, wherein The scattering element comprises scattering centers having a certain scattering center density per unit volume, wherein the scattering center density at the proximal end of the diffuser matrix (43) is different from the scattering center density at the distal end, wherein preferably, the scattering center density is greater at the distal end than at the proximal end, wherein most preferably, the scattering center density has a gradient.

16. The illumination system (1) according to any one of the preceding claims, wherein In the immediate vicinity of the coupling surface (46) of the diffuser substrate (43) and / or in the immediate vicinity of the reflector surface (47), the scattering effect of the scattering element (43.6) is reduced compared to the scattering effect along the diffuser substrate (43).

17. The illumination system (1) according to any one of the preceding claims, wherein The diffuser base (43) has a conical shape at least partially or in sections thereof.

18. The illumination system (1) according to any one of the preceding claims, wherein The diffuser element (40) and / or the diffuser base body (43) are structured at least partially or in sections within their volume and / or on their surface.

19. The illumination system (1) according to any one of the preceding claims, wherein The diffuser matrix (43) has a coating of scattering particles; and / or wherein the diffuser matrix (43) has an additional sheathing made of tinted glass or tinted plastic.

20. The illumination system (1) according to any one of the preceding claims, wherein The diffuser matrix (43) has at least 10, preferably at least 20 embedded scattering elements (43.6), and wherein preferably the resulting ratio of the cross-sectional area of ​​the embedded scattering elements (43.6) to the diffuser matrix (43) is ≤0.015, preferably ≤0.005, most preferably ≤0.

002.

21. A method for producing a diffuser substrate (43), in particular for an illumination system (1) according to any one of claims 1 to 49, the diffuser substrate (43) comprising at least one scattering element (43.6), wherein the at least one scattering element (43.6) is preferably arranged along a longitudinal axis (43.2) of the diffuser substrate (43) substantially parallel to the longitudinal axis (43.2) or arranged at an angle to the longitudinal axis of the diffuser substrate (43), the method comprising the following method steps: - providing a plurality of optical fiber rods made of glass having a refractive index n1 and / or n1'; - arranging the plurality of optical fiber rods having the refractive index n1 and / or n1′ and at least one scattering rod made of glass or glass ceramic and comprising scattering centers so that the longitudinal axes of the optical fiber rods and the at least one scattering rod extend at least substantially parallel to each other to obtain a preform; - heating the preform; - drawing the preform to form a diffuser matrix (43) such that the outer circumferential surfaces of the optical fiber rods are inseparably bonded to each other and to the at least one scattering rod to form a form fit, in particular to fuse with each other, so as to form a matrix (43.4) of the diffuser matrix (43), the diffuser matrix (43) having at least one embedded and / or adjacent scattering element (43.4) formed by the at least one drawn scattering rod, the scattering element (43.4) comprising scattering centers, The diffuser substrate (43) comprises a matrix (43.4) made of transparent plastic, glass, fused quartz or transparent glass ceramic or consists of the matrix (43.4); The scattering element (43.6) includes or consists of the following - in the case of plastic matrices, pigmented or dyed plastics; - in the case of a glass matrix, particles or coloured or tinted or containing inhomogeneities of glass or glass ceramics or glass ceramic elements and the crystallites contained therein; - in the case of a fused silica matrix, ceramic or polycrystalline particles; or - in the case of a transparent glass-ceramic matrix, particles or coloured or tinted or containing inhomogeneities of glass or glass-ceramic or glass-ceramic elements and the crystallites contained therein; or - a combination of corresponding scattering elements (43.6), The at least one scattering element (43.6) has a triangular cross section, a hexagonal cross section, a hyperbolic triangular cross section or a hyperbolic hexagonal cross section.

22. The method according to claim 21, wherein The heating and drawing of the preform are performed at a temperature below the melting temperature of the glass of most of the optical fiber rods; The matrix of the diffuser matrix (43) comprising the at least one embedded scattering element (43.6) comprises phase boundaries between drawn optical fiber rods and / or scattering rods.

23. The method according to any one of claims 21 to 22, wherein The diffuser substrate (43) is formed into a tapered or conical shape at least partially or in several sections thereof by changing the rate, temperature and / or force parameters of the drawing process of the preform, so that within the taper range, the at least one scattering element (43.6) extends at a certain angle relative to the longitudinal axis (43.2) of the diffuser substrate (43).

24. A method for at least partially or segmentally constructing a diffuser substrate (43) comprising at least one scattering element (43.6), in particular for adjusting the intensity distribution of lateral emission, wherein the at least one scattering element (43.6) is arranged along the entire longitudinal axis (43.2) of the diffuser substrate (43) substantially parallel to the longitudinal axis (43.2), wherein the scattering element has a uniform cross-sectional shape, or is arranged at a certain angle to the longitudinal axis in the case of a tapered diffuser substrate, wherein the at least one scattering element (43.6) has a triangular cross-section, a hexagonal cross-section, a hyperbolic triangular cross-section or a hyperbolic hexagonal cross-section; wherein The diffuser substrate (43) having the reflector surface (47) and the joining area (44) is at least partially or over sections thereof enclosed by a transparent or translucent sheath (49) to form the diffuser element (40); wherein the sheath (49) is defined by rigid pipe sections and / or by flexible pipe members, wherein the pipe sections and / or pipe members contain scattering centers which at least locally modify the properties and / or composition within their volume and / or at their surface and / or form structures therein and / or thereon of virtually any desired geometry and arrangement by material removal or material deposition techniques; said techniques comprising - laser processing techniques, in particular using short pulses or CO2 lasers, which preferably introduce modifications of the refractive index and / or composition or form structures in said volume and / or at said surface; - printing techniques for coating or producing, in particular, grid structures using printable organic or ceramic inks containing suitable pigments or using inks based on glass fluxes; - Wet chemical or dry chemical etching techniques; - Photolithography process; - abrasive mechanical processing techniques; or A combination of these technologies; and The diffuser substrate (43) comprises a matrix (43.4) made of transparent plastic, glass, fused quartz or transparent glass ceramic or consists of the matrix (43.4); The scattering element (43.6) includes or consists of the following - in the case of plastic matrices, pigmented or dyed plastics; - in the case of a glass matrix, particles or coloured or tinted or containing inhomogeneities of glass or glass ceramics or glass ceramic elements and the crystallites contained therein; - in the case of a fused silica matrix, ceramic or polycrystalline particles; or - in the case of a transparent glass-ceramic matrix, particles or coloured or tinted or containing inhomogeneities of glass or glass-ceramic or glass-ceramic elements and the crystallites contained therein; or - A combination of corresponding scattering elements (43.6).

25. Use of an irradiation system (1) according to any one of claims 1 to 20 as a component of a device for medical technology.

26. An apparatus, wherein the illumination system (1) according to any one of claims 1 to 20 is used as a component of the apparatus.

27. A device comprising an illumination system (1) according to any one of claims 1 to 20, wherein at least one optical waveguide (30) having a diffuser element (40) captures light emitted from other diffuser elements (40) to forward the light via the optical waveguide (30) to a detector for spectral analysis.

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