Illumination system including light guide body having diffuser element

Abstract

To provide an illumination system with improved homogeneity and scattering efficiency.SOLUTION: An illumination system 1 includes at least one light source 10, preferably a laser light source, and a light guide body 30. The light guide body 30 is connectable to and / or can support at least one light source 10 at a proximal end part. The illumination system 1 has a diffuser element 40 having a longitudinal axis line at a distal end part of the light guide body 30. The longitudinal axis line extends into or inside the diffuser element 40 vertically to an incidence plane of the light guide body 30. The diffuser element 40 radiates light sideways to the longitudinal axis line across an effective length of the diffuser element 40 in an active state. The diffuser element 40 has at least one diffuser base body. The diffuser base body includes a matrix having at least one scattering element. The matrix is encircled by a rigid coating part on a peripheral surface of at least the diffuser base body.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates, inter alia, to a lighting system for a medical-technical treatment and / or diagnostic system, to a method for manufacturing a diffuser substrate having a rigid coating, especially for a lighting system, and to a method for at least partially or sectionally structuring a diffuser substrate in order to adapt the intensity profile of the lateral radiation. The lighting system includes a light guide and a diffuser element having a rigid coating.

Background Art

[0002] Such lighting systems are being increasingly used in the medical environment. Currently, they can be classified into the following main applications: · Photodynamic therapy (PDT) or photoimmunotherapy (PIT) for tumor treatment · Endovascular laser treatment (EVLT) for the treatment of aneurysms · Laser-induced interstitial thermotherapy (LITT), · Other applications, especially in the fields of dentistry, ophthalmology and dermatology and can be classified as such.

[0003] Photodynamic therapy (PDT) is a minimally invasive treatment method for various cancerous diseases. PDT is understood as a method of treating tumors and other tissue changes (e.g., angiogenesis) using light in combination with photoactivatable substances. At the start of the procedure, a photosensitive substance, a so-called photosensitizer, is injected into the patient's venous bloodstream, and these photosensitizers accumulate inside or on the cancer cells. These natural photosubstances concentrate in the tumor cells, where they cause strong photosensitivity. For this reason, during the PDT procedure, multiple cannulas (typically up to eight) are inserted into the tumor tissue, and one light guide with a diffuser element is inserted into each of these cannulas, and it is necessary to position the diffuser element so that it is distributed as spatially as possible throughout the tumor tissue. In essence, laser light with a wavelength in the visible spectrum, such as green light with a wavelength of 532 nm or red light with a wavelength of 690 nm, is incident into the diffuser element via the light guide so that the tumor tissue is illuminated as uniformly as possible from the inside. During this process, invasive oxygen radicals are formed within these cells, and these oxygen radicals selectively destroy tumor cells. In contrast to diseased cells, healthy cells remain unaffected by this chemical reaction. The detailed mechanism of action is described, in particular, in “Photodynamic Therapy of Cancer,” Cancer Medicine, 2003.

[0004] In contrast, in photoimmunotherapy (PIT), an immune response is triggered on or within cancer cells by a appropriately modified photosensitizer, and this immune response, when irradiated with light, leads to the death of cancer cells.

[0005] Here, cylindrical diffusers with a typical effective length of 10-50 mm, spot diffusers that form a forward-directed illumination cone, and spotlights that emit light radially are distinguished.

[0006] In the case of a cylindrical diffuser, it is important that the lateral radiation from the diffuser element is as homogeneous as possible, especially over the length of the diffuser element, during operation. This applies both axially and radially; that is, the radiation intensity is the same within the homogeneity requirement at all points along each line from the proximal end to the distal end in the longitudinal axis, and similarly, the radiation intensity is the same within the homogeneity requirement at all points along each peripheral line along the longitudinal axis. Therefore, this diffuser acts approximately as a Lambertian radiator.

[0007] At the same time, high scattering efficiency must be achieved to ensure that the heat input to the tissue is kept to a minimum. Typical homogeneity requirements for lateral radiation are a maximum deviation of ±10-20% from the average intensity, and forward-directed radiation from the distal end in particular should be avoided, which is more than 10% of the incident light, typically up to 5%. Typical laser power is less than 5W continuous power for PDT applications, so a maximum of 100mW-1000mW, typically 200mW-500mW, is emitted per centimeter of diffuser length. This has made the use of plastic-based diffuser approaches possible today.

[0008] European Patent Publication No. 2062077, U.S. Patent Publication No. 2009 / 0204111, and German Patent Publication No. 102015119875 describe diffusers having fibers.

[0009] European Patent Application Publication No. 2062077 or International Publication No. 2008 / 024397 describes, among other things, a diffuser for outputting high-power-density optical energy to a treatment site at the distal end of at least one optical fiber. A diffuser is proposed comprising a predetermined length section at the distal end of the optical fiber and scattering centers located in this predetermined length section, wherein a portion of the input optical energy is output radially to the treatment site. The scattering centers may be scattering particles contained in the core or the coating of the core. These scattering centers may adversely affect the fragility of the component, in addition to introducing, for example, the distribution and / or dimensions of the nanocracks or nanocavities described above, which are difficult to control and require effort. Furthermore, it should be considered that it is impossible to achieve the required homogeneity of lateral radiation due to the exponential decrease in lateral radiation or heterogeneous distribution.

[0010] In this case, a cylindrical diffuser, such as those used in PDT applications, would be advantageous. However, EVLT treatment requires significantly higher laser power. Therefore, the laser power is typically between 10 and 50 W in the NIR wavelength range, i.e., between approximately 800 nm and 1480 nm, and such laser power is currently provided by diode lasers (e.g., 810 nm, 940 nm, or 1480 nm) or Nd:YAG lasers (1064 nm).

[0011] In the meantime, relatively long wavelengths of approximately 2 μm have also been established for EVLT treatment. In this case, for example, Tm:YAG lasers (1.9 μm) and Ho:YAG lasers (2.1 μm) are used. Based on the absorption characteristics of the tissue, relatively low laser power is required at these wavelengths, typically less than <10 W. However, here, a quartz glass light guide is inevitably used, in particular, to supply the laser light.

[0012] The homogeneity requirements for lateral radiation of diffusers that can be used for EVLT are not as high as those for PDT applications, and the deviation from the average intensity can be as low as ±30% to ±50%.

[0013] LITT is a minimally invasive technique used for localized tumor destruction. In this procedure, the tumor is punctured under imaging control (e.g., sonography / MRT), and one (or more) laser fibers are inserted into the neoplastic lesion, which is then destroyed by thermal energy. In particular, Nd:YAG lasers (1064 nm), semiconductor lasers (980 nm), and diffuser tip applicators are used. The laser power is approximately 5-8 W (see, in particular, “Laserinduzierte Interstitielle Thermotherapie (LITT) bei malignen Tumoren”, German Medical Association (BAEK) and German Federal Health Insurance Association (KBV) 01 / 2002).

[0014] The applicant’s International Publication No. 2019 / 063799 describes an illumination system having a light guide and a diffuser element, and a method for manufacturing and / or structuring a diffuser substrate at least partially or segmentally, which already enables the requirement of high homogeneity for lateral radiation of the diffuser.

[0015] The diffuser substrate described above includes a light guide and means for homogenizing the radiant intensity along the longitudinal axis of the diffuser substrate. It is possible to achieve a lateral radiation intensity distribution that deviates by a maximum of ±50%, preferably a maximum of ±30%, and in many cases preferably a maximum of ±5%, from the average lateral radiation intensity.

[0016] As measurements in numerous cylindrical diffusers configured or manufactured in this manner demonstrate, this already achieves good homogeneity and high efficiency values ​​in radiant properties, as required for the applications described at the beginning.

[0017] However, it has also been found that backscattering effects can occur, particularly at certain power levels of laser radiation or light.

[0018] Therefore, for example, light may return to the photoguide and even reach the laser light source. In this case, undesirable light emission may occur within the photoguide. Furthermore, the laser light source may become unstable depending on the intensity of the backscattered light, which may, in some cases, cause the laser light source to be blocked.

[0019] Furthermore, back reflection can cause localized hot spots, which can lead to undesirable temperature increases in the lighting system. This is undesirable in certain applications and could negatively impact the treatment.

[0020] Therefore, the object of the present invention is to minimize the aforementioned drawbacks and to further improve, or at least achieve, high homogeneity and efficiency. [Overview of the project] [Means for solving the problem]

[0021] The problem of the present invention has already been solved by the subject matter of the independent claims, and advantageous forms of development can be seen from the dependent claims and further disclosures in the specification and drawings.

[0022] For this purpose, a lighting system for medical technology treatment and / or diagnostic systems, The lighting system includes at least one light source, in particular a laser light source, and a light guide, the light guide being connectable to and / or connected to at least one light source at its proximal end. The lighting system has a diffuser element with a longitudinal axis at the distal end of the light guide, and the longitudinal axis extends into the diffuser element perpendicular to the incident surface of the light guide. In the operating state, the diffuser element emits light laterally with respect to the longitudinal axis over the effective length of the diffuser element. The diffuser element has at least one diffuser substrate, and at least one diffuser substrate includes a matrix having at least one scattering element, and the matrix is at least partially or intermittently surrounded by a rigid coating on the peripheral surface of the diffuser substrate. The rigid coating is formed of a structure composed of a plurality of parts or a multi-layer structure, and includes at least two coating tubes or layers, preferably at least three coating tubes or layers. An illumination system is proposed.

[0023] The light source can be a laser light source, a semiconductor-based light source, a light-emitting diode (LED), especially a laser diode (LD), or can also include a laser.

[0024] Therefore, in a preferred embodiment of the present invention, the diffuser substrate is at least partially or intermittently or preferably completely surrounded by a rigid coating on the peripheral surface of the diffuser substrate, or can be surrounded, and this rigid coating can be a sequence of a plurality of coating tubes in a preferred embodiment of the present invention. The plurality of coating tubes can each have different optical properties.

[0025] However, the rigid coating can also include a multi-layer structure or a structure composed of a plurality of elements or parts, that is, it can also include at least one layer that can be attached on or between the coating tubes. Therefore, the rigid coating can include two coating tubes. Additionally, the rigid coating can include one layer and / or further coating tubes, or other combinations of coating tubes and / or layers, especially at least three coating tubes, preferably three overlapping coating tubes.

[0026] The lighting system according to the present invention may further feature at least one of the following features, namely, The scattering element is characterized in that at least one scattering element is oriented along the longitudinal axis of the diffuser substrate substantially parallel to the longitudinal axis, or positioned at a predetermined angle to the longitudinal axis. The diffuser substrate is characterized by having means for homogenizing the radiant intensity along the longitudinal axis of the diffuser substrate, provided at the distal end of the diffuser substrate and / or in the transition region between the light guide and the diffuser substrate and / or on the diffuser substrate, so as to surround the diffuser substrate at least partially or segmentally. The diffuser substrate is characterized in that it has a reflector surface at its distal end, and the reflector surface is capable of at least partially back-reflecting the light passing through the diffuser substrate during operation, and / or The lighting system is characterized by having a lateral radiation intensity distribution that deviates by up to ±50%, preferably up to ±30%, and in many cases preferably up to ±5%, from the average lateral radiation intensity when in operation. At least one of these can be further characterized.

[0027] In this invention, the average lateral radiation intensity refers to the average value of the lateral radiation intensity measured over the length of the diffuser substrate.

[0028] Within the scope of this disclosure, lateral radiation is understood to be radiation having a directional component that extends radially from the longitudinal axis of the diffuser substrate. Lateral radiation intensity is understood to be the intensity of this radiation.

[0029] Back-reflected light is understood to be radiation reflected back into the diffuser substrate by the reflector surface at the distal end of the diffuser substrate, and in this case, the light can also be guided through a rigid cladding or cladding tube.

[0030] At least one scattering element can be positioned substantially parallel to the longitudinal axis of a diffuser substrate having a uniform cross-section, or, if the diffuser substrate is tapered, at a predetermined angle to the longitudinal axis. At least one scattering element can be positioned advantageously tubularly, and in particular coaxially with respect to the longitudinal axis.

[0031] Scattering regions can also be considered, centered on the longitudinal axis of the diffuser substrate, and particularly along the longitudinal axis. In one embodiment, the scattering region is spirally arranged around the longitudinal axis of the diffuser substrate. Embodiments in which the scattering elements or scattering regions are arranged at a constant inclination around the longitudinal axis of the diffuser substrate have proven particularly advantageous. In this case, the scattering region can exist in the form of a helical spiral around the longitudinal axis of the diffuser substrate. Individual scattering regions can be formed by one or more scattering elements. One embodiment intends that the scattering region is formed by a single scattering element in the form of a spiral or vortex. Such arrangement of scattering elements or scattering regions within the substrate has the advantage that scattering interactions with axially parallel light components or with light components extending at a small angle to the diffuser axis are increased, thereby improving scattering efficiency. Furthermore, this can optimize the homogeneity of radiation.

[0032] Multiple scattering elements can be arranged in a predetermined, configurable geometric arrangement centered on the longitudinal axis of the diffuser substrate, preferably in a regular structure centered on the longitudinal axis of the diffuser substrate, and particularly preferably in a circular arrangement. Therefore, multiple scattering elements arranged at a predetermined angle preferably converge at a vanishing point outside the diffuser substrate.

[0033] Preferably, means and / or measures for homogenizing lateral radiation along the longitudinal axis are provided at the distal end of the diffuser substrate and / or in the transition region between the light guide and the diffuser substrate, and these means and / or measures surround the diffuser substrate at least partially or segmentally and / or substantially completely.

[0034] For example, these means include sleeves, covers, caps and / or layers at the distal end of the diffuser, which block forward-directed radiation from the distal end or cause this radiation to be reflected backward, thereby providing a scattering process in the diffuser substrate, while on the other hand, scattering effects and / or light reflection at the distal end of the diffuser substrate are avoided.

[0035] The same applies to the transition region between the light guide and the diffuser substrate. Here too, scattering and / or light reflection can occur, and these scattering and / or light reflection can be reduced by appropriately acting elements in this area, such as sleeves and / or layers.

[0036] The light guide may include a single fiber having a core with a core diameter and a cladding, such as a monomode or multimode optical fiber, or it may include a fiber bundle having a fiber bundle diameter.

[0037] This makes it possible to provide a diffuser element that is reproducible, cost-optimized, and uniformly radiates under operating conditions for medical treatment, as mentioned at the beginning.

[0038] In a preferred variant, the scattering elements within the diffuser substrate are arranged to be uniformly distributed radially around the longitudinal axis of the diffuser substrate, and the core zone centered on the longitudinal axis has no scattering elements or has a significantly reduced number of scattering elements per unit area compared to the number of scattering elements per unit area outside the core zone, and therefore the scattering elements are mainly located outside this core zone in the matrix.

[0039] This makes it possible to achieve a situation where incident light with a very small NA (<0.3, typically around 0.2) is not immediately scattered by the scattering element. On the other hand, it is possible to guide sufficient light without scattering through the core zone, which has almost no scattering element, to the distal end of the diffuser substrate. This makes it possible to reduce the intensity near the point of incidence (the proximal end of the diffuser substrate) on the one hand, and increase the intensity near the distal end of the diffuser substrate on the other hand.

[0040] In a further preferred modification, the diffuser substrate may have a matrix with respect to the cross-section of the diffuser substrate, particularly between the core zone and the edge region of the matrix where the scattering elements are mixed. This allows, for example, the numerical aperture NA to be affected within the core zone having matrix refractive index n1 and outside the core zone of the matrix having refractive index n1'.

[0041] This further allows the propagation of light within the diffuser substrate, and consequently the excitation of scattering centers, to be adapted to the required radiative characteristics over the length of the diffuser. Furthermore, during the manufacturing process, any cross-sectional geometry of the core zone having refractive index n1 can be realized, i.e., any cross-sectional geometry ranging from substantially circular to polygonal or star-shaped.

[0042] If the diameter of the diffuser substrate in which the scattering elements are embedded is equal to or greater than the core diameter or fiber bundle diameter of the light guide, it can help to homogenize the intensity of the lateral radiation.

[0043] It has been found that the ratio between the core diameter or fiber bundle diameter of the light guide and the matrix diameter is particularly preferable when it is ≤1.0 to 0.7, and especially preferably ≤1.0 to 0.8.

[0044] In this case, by making the core diameter or fiber bundle diameter slightly smaller than the matrix diameter, the intensity peak at the incident site (the transition region between the light guide and the diffuser substrate) can be reduced.

[0045] In contrast, if the core diameter or fiber bundle diameter is made significantly smaller than the diameter of the diffuser substrate matrix, i.e., a ratio of <0.8, it is possible to reduce the intensity at the point of incidence, and such a reduction in intensity may be advantageous for certain requirements.

[0046] Furthermore, it has been found that when this ratio is between 1 and 0.9, a particularly robust mechanical coupling or connection can be achieved between the light guide and the diffuser substrate, for example, by splicing. In a preferred embodiment, the diffuser element has a connection zone between the proximal end of the diffuser substrate and the distal end of the light guide, which is manufactured by shape bonding and / or material bonding using bonding, splicing, or pressurization, and connects at least the diameter of the diffuser substrate to the core diameter or fiber bundle diameter of the light guide.

[0047] To accommodate the varying coefficients of thermal expansion, it would be advantageous to provide an additional intermediate medium in the connection zone between the proximal end of the diffuser substrate and the distal end of the light guide. This intermediate medium may be, for example, an intermediate glass or solder glass. Alternatively, this intermediate medium may be a transparent, sustained-elastic adhesive. Furthermore, optical elements can be placed within the connection zone, or the connection zone can be configured as an optical element, for example, to correct beam guidance and / or light deflection by geometrically matching the refractive values.

[0048] The diffuser substrate may consist substantially of a matrix made of transparent plastic, glass, quartz glass, or glass ceramic, and the scattering elements mixed within this matrix may, for example, in the case of a plastic matrix, consist of porous, colored, or, for example, white-colored plastic; in the case of a glass matrix, consist of glass or glass ceramic elements containing pores, particles, porous, colored, or, for example, white-colored, or heterogeneity, and crystals contained therein; in the case of a quartz matrix, consist of pores, porous quartz glass, or ceramic or polycrystalline particles; or in the case of a transparent glass ceramic matrix, consist of glass or glass ceramic elements containing pores, particles, porous, colored, or, for example, white-colored, or heterogeneity, and crystals contained therein.

[0049] In this case, advantageously, the exemplary combinations of scattering elements can also be provided within each matrix. In the case of glass matrix or glass-ceramic matrix solutions, the glass or glass-ceramic heterogeneity that can form scattering elements includes, for example, phase separation, segregation and / or particle inclusion, nuclei and / or crystallites.

[0050] In this case, the concentration of scattering elements within the scattering region should be 10 ppm to 1000 ppm, preferably 20 ppm to 100 ppm. In this case, the concentration expression in ppm relates to the ratio of scattering particles to the mass ratio of the components of each material, particularly the plastic, glass matrix, or quartz matrix in which the scattering particles are mixed. In this case, each formed scattering element, meaning, for example, a glass element or glass ceramic element containing pores, particles, porous, or colored, or for example, colored white, or heterogeneity, and the crystals contained therein, preferably has a diameter of 10 nm to 1000 nm, particularly preferably 100 nm to 800 nm.

[0051] For example, plastic-based solutions for diffuser substrates consisting of plastic rods made of PMMA, PET, or PC are already feasible even at low process temperatures during manufacturing or deformation. However, diffuser substrates constructed in this way have correspondingly lower heat resistance and are therefore more suitable for applications with low laser power. Furthermore, such diffuser substrates are only suitable for applications in the visible spectral region (VIS) because plastics inherently exhibit high absorptivity in the NIR or IR regions.

[0052] The glass-based approach is significantly more robust and, in particular, thermally stable, allowing for the application of relatively high laser power. As elements for constituting the diffuser substrate, for example, N-BK7 type glass rods, the applicant's optical boron crown glass rods, borosilicate glass rods, or lead-free or heavy metal-free rods have been considered, such elements being used, in particular, as core glass for optically high-quality glass fibers for endoscopes or dental rods for hardening dental fillings. The latter allows for compliance with future RoHS directives. Such glass is described in the applicant's German Patent Application Publication No. 102012100233 and DE102013208838B4, the entire scope of which is incorporated herein by reference.

[0053] Examples of such glasses from the region of lead-free tin silicate glass or alkali zinc silicate glass for light guide rods or for the matrix of diffuser substrates contain the following components (listed in wt% based on oxides): [Table 1]

[0054] The cladding is selected from one of the following groups 1 to 4, each containing, for example, the following components (indicated in wt% based on oxides): [Table 2]

[0055] Here, if the rigid cladding has a multilayer structure or, in particular, has at least two cladding tubes, this makes it possible to achieve, in particular, that scattered, guided, and reflected or back-reflected light components also contribute as specified to the lateral radiation along the diffuser length.

[0056] This is particularly effective in structures having at least two cladding tubes, in which case the inner first cladding tube is preferably formed from transparent borosilicate glass, and the subsequent second cladding tube is formed from translucent scattering glass, in which scattering centers can be incorporated. These scattering centers may be particles, phase boundaries, or segregations.

[0057] The second cladding tube may include white glass in a particularly preferred embodiment. The white glass may contain a white pigment to produce a white color impression.

[0058] The white glass cladding may, according to a preferred embodiment, be or may include a translucent silicate white glass. This translucent silicate white glass can have an extreme scattering effect. This translucent silicate white glass may be, for example, an As-Pb-containing silicate glass. Such a glass is a silicate glass containing lead (Pb) and arsenic (As). For scattering, heterogeneous regions in the glass can be used as scattering elements, which may have increased lead and / or arsenic content relative to the surrounding glass. Alternatively, of course, scattering elements, such as scattering particles, can also be incorporated and form scattering centers.

[0059] In an equally preferred further embodiment of the present invention, a further third cladding tube is provided for a rigid cladding portion. This third cladding tube may be an outer cladding tube for the rigid cladding portion. In this case, the first and second cladding tubes can be configured as described above.

[0060] According to one embodiment, instead of a second cladding tube made of glass having a high scattering center density, such as white glass, a ring made of a plurality of individual glass rods having a high scattering center density, or a plurality of individual white glass rods, is also used. In this case, these glass rods arranged in a ring are positioned between a first cladding tube located on the inside and a third cladding tube located on the outside. In the drawing process, these glass rods melt together to form a homogeneous scattering layer. With the ring arrangement of the glass rods, this arrangement is formed substantially in a ring or tubular shape.

[0061] Such a configuration of the rigid covering makes it highly advantageous to achieve that only a very small percentage of light is reflected back through the coupling to or into the light guide, or even further back towards the laser light source. In this way, it is highly advantageous to ensure that only a small percentage of the light emitted from the laser light source, preferably less than 10%, and more preferably less than 5%, is reflected back into or re-entered into the supply light guide, or that no light is reflected back into or re-entered into the supply light guide at all.

[0062] It has been found to be preferable that at least two of the cladding tubes of the rigid cladding differ from each other in at least one optical property. In this context, optical properties refer to properties relating to transparency or translucency, for example, in the case of a clear and transparent cladding tube and a translucent cladding tube, there is a corresponding difference in the refractive index and / or material of the cladding tubes.

[0063] Supplementary or alternative, differences in optical properties may also refer to the different transmission behaviors of the corresponding cladding tubes, for example, the transmission behavior of electromagnetic radiation in the spectrum of the wavelength used.

[0064] Supplementary or alternative, differences in optical properties may also mean differences in the refractive index values ​​of the corresponding cladding tubes, for example, differences in refractive index values ​​of approximately 0.05 or approximately 0.1.

[0065] For example, a rigid coating comprising at least three coating tubes, each having different optical properties, can again significantly reduce the risk of undesirable light emission phenomena within or on the light guide, particularly at the ends of the light guide or at the transition to the diffuser body. Furthermore, this can prevent the light source from becoming unstable or even switching off, thereby providing a relatively high level of safety during the procedure. This is especially true for laser light sources.

[0066] Particularly advantageous is the avoidance of localized hot spots or other luminescence phenomena that may occur, for example, at splicing points, i.e., at the transition from the light guide to the diffuser substrate, particularly due to back reflection from the diffuser toward the light guide or back reflection into the light guide. Consequently, unwanted temperature increases in the lighting system, which could adversely affect the procedure and, in some cases, the operation, can also be eliminated. The risk to the patient and the practitioner is prevented or at least minimized.

[0067] The following describes a particularly suitable embodiment in which the rigid covering includes three covering tubes.

[0068] In this embodiment of the present invention, it has been found to be particularly advantageous that the first cladding tube, which at least partially directly surrounds the matrix, is formed to be substantially clear and transparent, and preferably has a refractive index lower than that of the matrix material. Exemplary glasses or their compositions are listed in the table above relating to clad glasses.

[0069] In this case, this first cladding tube may be, so to speak, an optical cladding of the diffuser substrate, and therefore, the incident light is first guided to the distal end of the diffuser substrate, and only the light scattered by the scattering element is radiated laterally at a large angle with respect to the axis of the diffuser substrate.

[0070] More advantageously, a second cladding is provided that at least partially surrounds the first cladding, and preferably the second cladding is formed to be semi-transparent or scattering. In this case, the second cladding may have a refractive index greater than that of the first cladding.

[0071] This makes it possible to achieve that, if the second cladding is semi-transparent or scatterable and has a refractive index greater than that of the first cladding, the light reflected backward through the first cladding can also be scattered outward as specified.

[0072] Furthermore, due to multiple scattering on or within this second cladding, further homogenization of the emitted light can be achieved. This is particularly related to the angular distribution, thereby achieving approximately Lambertian radiation.

[0073] More advantageously, a third cladding is provided that at least partially surrounds the second cladding, and preferably the third cladding is formed to be substantially clear and transparent.

[0074] By using a third cladding tube that is substantially transparent without any clouding, the structure can be mechanically stabilized, thereby enabling a smooth, closed surface.

[0075] Depending on the configuration of the second cladding, the third cladding can also be considered optional. This is also true if the second cladding is made of white glass or contains white glass, as further mentioned above.

[0076] In one evolution of the present invention, the rigid cladding portion may, supplementarily, include more than three cladding tubes, and the sequence described above can be partially or completely repeated, for example. The additional cladding tubes may, of course, be formed differently.

[0077] In this case, it is particularly advantageous if the matrix having at least one scattering element and the rigid coating portion containing multiple or multiple cladding tubes are configured as a closed composite without any hollow spaces.

[0078] This means that gapless optical coupling is achieved, particularly between the first and second cladding tubes, and preferably between all the cladding tubes. This means that the peripheral walls of the cladding tubes are preferably in direct contact with each other, or that there is no air, such as contained air or bubbles, between the cladding tubes. In other words, the sides of adjacent cladding tubes are in as much overall contact with each other as possible. Otherwise, this could lead to undesirable optical effects, for example, due to abrupt changes in refractive index occurring there.

[0079] As intended in a particularly preferred embodiment of the present invention, when a diffuser element is formed having a matrix, at least one scattering element, and a rigid covering portion including a glass covering tube, a particularly compact and dense diffuser substrate without hollow spaces can be provided. To this end, the covering tubes of the covering can be melted together in a drawing process to form a compact and closed body, as will be further described below.

[0080] In this way, it is possible to ensure that no liquid that could adversely affect the radiant behavior enters the lighting system according to the present invention during use.

[0081] Furthermore, such diffuser substrates are also very mechanically stable. This mechanical stability is achievable when the manufacturing is carried out by a wire drawing method, which will be described in more detail below. In the wire drawing method, the viscosity and thermal expansion coefficient of the cladding material can be selected and adjusted to mutually affect each other, particularly preferably, such that compressive stress is induced when the diffuser substrate is cooled to, for example, room temperature after the melting of the components by the wire drawing process. Advantageously, in this case, the thermal expansion coefficient of the outermost cladding can be selected to be at least slightly higher than that of the cladding adjacent to the innermost cladding.

[0082] At least one of the cladding tubes, for example, a third cladding tube, can be selected as intended depending on the intended application in order to produce a predetermined optical property.

[0083] Therefore, in one evolution of the present invention, for at least one cladding tube, for example, an outer cladding tube, radiopaque glass can be selected. This radiopaque glass has the advantage that the diffuser substrate as a whole becomes at least partially or segmentally identifiable in the X-ray image. This makes it particularly easy to pinpoint the location of the diffuser within the patient's body.

[0084] For example, regarding the wavelength range of 0.8 μm to approximately 2.2 μm used for EVLT applications as mentioned at the beginning, special IR-transmitting glasses can be used, such as the phosphate crown glass known from the applicant as N-PK52a, or the lead silicate glass with approximately 30 wt% PbO, known as IRG7. Such high-Pb-content glasses offer the further advantage of being reasonably conspicuous in X-ray images and usable as X-ray markers.

[0085] The most effective utilization of light incident on the diffuser substrate for lateral radiation can be achieved using a reflecting surface, which forms the end of the diffuser substrate at its distal end and / or surrounds the diffuser substrate at least partially or intermittently on its circumferential surface, directly and / or diffusely reflecting the light backward.

[0086] In this case, a reflector surface formed as a dielectric reflective layer sputtered or deposited on the distal end of the diffuser substrate has been found to be suitable, and this reflector surface consists of multiple layers and is adjusted in relation to the wavelength of light being used in terms of reflectance, and preferably the maximum reflectance at this wavelength can be adjusted by the laminate and the respective thickness of each layer.

[0087] With such layers, it is possible to set the reflectivity from >95% to >99.5% as intended.

[0088] Alternatively or additionally, in further embodiments of the present invention, the reflector may be constructed from a coating that reflects well over a broadband, for example, from a silver layer having a back passivation or protective layer, depending on the configuration. Such a coating is particularly robust and can suppress interfering reflections that could lead to localized excessive increases in intensity or hot spots. This makes it possible to realize a very broadband reflector that has very good reflectivity, particularly in the visible spectral region (VIS), as well as in the IR / MIR region ("IR" = infrared, "MIR" = mid-infrared) between wavelengths of, for example, 1 μm to 2.5 μm. The back passivation prevents oxidation of the silver layer, for example.

[0089] In further variations, a first maximum value of the reflectance for a first wavelength, for example, the wavelength of light being used or the wavelength being used, and at least one further second maximum value of the reflectance for at least one further wavelength can also be provided. In this case, the at least one further wavelength may be advantageously different from the wavelength being used. In this way, further functions can be incorporated very advantageously.

[0090] In this case, at least two maximum values ​​can have reflectances of, in particular, >95%, preferably >99%. In other words, the first maximum value of reflectance can be located at a predetermined wavelength of light from the light source, and at least one further second maximum value of reflectance can be located at a further wavelength, which may be different from the first wavelength of light from the laser light source, and the reflectance of the first maximum value and the reflectance of at least one further maximum value are preferably >95%, preferably >99%. To generate light of further wavelengths, for example, a further light source can be provided, for example, a further LED light source emitting light with a lower output.

[0091] In this specification, the term "wavelength used" refers to the wavelength of electromagnetic radiation intended or selected for a particular treatment, e.g., 690 nm.

[0092] This makes it possible to avoid interfering radiation at the distal end of the diffuser substrate for the treatment wavelength, e.g., 690 nm, and for other wavelengths, e.g., the wavelength of pilot light, e.g., green light, often used for component installation and functional control, e.g., 500 nm to 550 nm.

[0093] In a further embodiment of the present invention, the reflector surface is formed at least partially at an angle of less than 90° with respect to the longitudinal axis of the diffuser substrate, preferably between 85.0° and 89.9°, making it possible to reflect light reflected backward during operation with a larger numerical aperture NA than the light that strikes the reflector surface.

[0094] This makes it possible to better utilize the scattering elements mixed into the diffuser substrate for light emission from the sides, which not only improves efficiency but also improves homogeneity over the length of the diffuser.

[0095] In yet another embodiment, a reflector surface formed in a concave or convex shape may be provided. A flat reflector surface formed simply at an angle to the longitudinal axis of the diffuser base, or a faceted reflector surface having multiple flat surfaces, each at a different angle to the longitudinal axis of the diffuser base, would also be particularly preferred in view of the manufacturing process.

[0096] Despite the measures described above, under certain circumstances, some of the back-reflected light may still be directed towards and / or into the supply light guide through the transparent sleeve, particularly in the region of the transparent sleeve provided as a mechanical reinforcement at the transition between the diffuser substrate and the light guide. This could, on the one hand, cause undesirable illumination of the light guide, or, for example, cause undesirable heating if the light output is relatively high.

[0097] Transparent sleeves can be manufactured from, or may include, plastic, glass, metal, or ceramic materials. Plastics can be selected from a group of thermoplastics such as polycarbonate (PC). Glass offers advantages in terms of mechanical stability based on its modulus of elasticity.

[0098] In particular, localized heating can occur as a result of localized absorption, creating so-called hot spots. Specifically, when light guided through a transparent sleeve strikes the cladding (buffer) on the outside of the light guide, this causes concentrated and significant light reflection, resulting in localized heating.

[0099] Therefore, in a particularly preferred embodiment of the present invention, a translucent or partially absorbing cover is provided in the region between the transparent sleeve and the outer cladding of the light guide.

[0100] This translucent or partially absorbing cover can, advantageously, be formed from a polymer mixed with scattering particles.

[0101] This allows for at least a partial reduction in the light that strikes the outer cladding. Furthermore, while lateral radiation may occur due to multiple reflections within this cover, it is barely perceptible to the eye because it occurs uniformly across the entire length of the cover at a significantly lower power density, and therefore is carried out with significantly reduced attenuation. This avoids hotspots.

[0102] With regard to technical implementation, it has been found that the translucent or partially absorbent cover is advantageous to be a tubular portion, a shrinkable tubular portion, and / or a recoating polymer that can pre-introduce scattering particles as desired.

[0103] Within the framework of the present invention, preferably, methods for manufacturing a diffuser substrate or lighting system according to the present invention that have an illumination profile adapted to the intended use, in particular homogeneity of the intensity of lateral radiation in the operating state.

[0104] A method for manufacturing a diffuser substrate according to the present invention, particularly for a lighting system according to the present invention, comprising at least one scattering element, preferably, the at least one scattering element is oriented substantially parallel to the diffuser substrate along the longitudinal axis of the diffuser substrate, or positioned at a predetermined angle with respect to the longitudinal axis of the diffuser substrate, and the method comprises the following steps: The step of preparing multiple light guide rods made of glass having refractive indices n1 and / or n1', The steps of arranging a plurality of light guide rods having refractive indices n1 and / or n1' and at least one scattering rod made of glass or glass ceramic containing a scattering center, such that the longitudinal axes of the light guide rods and the longitudinal axis of the at least one scattering rod extend substantially parallel to each other, and so that a preform is obtained. • The step of heating the preform, • To obtain a diffuser base, the preform is marked using a marking machine, and if necessary, cut. It has.

[0105] In the diffuser substrate obtained in this manner, the outer surfaces of the light guide rods are irrevocably bonded to each other and to at least one scattering rod by shape bonding. In particular, they melt together, thereby forming a matrix of the diffuser substrate, which has at least one mixed and / or adjacent scattering element formed from at least one delineated scattering rod.

[0106] This provides multiple light guide rods made of glass having a refractive index of n1 or n1'.

[0107] Depending on the illumination profile to be achieved, at least one or more scattering rods made of glass or glass ceramic containing the aforementioned scattering centers are provided in the required number and placed next to or between the light guide rods, thereby resulting in an arrangement of light guide rods and scattering rods such that the longitudinal axes of the light guide rods and the longitudinal axes of the scattering rods are advantageously substantially parallel to each other. The distribution of scattering rods in this arrangement can be carried out according to a pattern corresponding to the desired illumination profile. This arrangement is fixed by appropriate means, thereby forming a preform.

[0108] In a subsequent method step, the preform is heated and drawn so that the light guide rods and at least one scattering rod are inseparably bonded to each other on their respective outer surfaces, thereby forming glass elements that radiate laterally. Temperature control during drawing also ensures that a phase boundary remains present between the light guide elements. This can be achieved, in particular, by keeping the drawing temperature below the melting temperature of the glass of the light guide rods and by sintering these light guide rods together, in particular at the sintering temperature. Complete melting of the light guide rods is avoided according to the present invention. Similarly, temperature control also achieves a preferred shape bond of the light guide rods and, if necessary, a preferred shape bond of the scattering elements.

[0109] The glass elements thus obtained can directly form a diffuser substrate. However, the diffuser substrate and / or sections of the diffuser substrate can also be obtained, for example, by cutting, the fabricated glass elements. In this case, the matrix of the diffuser substrate is formed from a plurality of light guide rods drawn and joined by shape bonding, and within these light guide rods, at least one scattering element having a scattering center formed from a drawn scattering rod is also mixed in by shape bonding, substantially according to its arrangement in the preform.

[0110] In a preferred embodiment, the light guide rods are not completely melted with each other as described above, and the scattering rods are also not completely melted with at least one of the light guide rods. In this case, a phase boundary can also exist between the scattering rods and the light guide rods, and thus remains within the formed matrix and the scattering elements of the diffuser substrate. This embodiment can be achieved by setting the softening temperature of the glass of the light guide rods to be the same as or lower than the softening temperature of the scattering rods.

[0111] Similarly advantageous embodiments involve ensuring that the light guide rods are not completely melted from one another, and that a phase boundary exists between them, but that at least one scattering element is melted on at least one light guide rod. This can be achieved by selecting a softening temperature for the glass of the scattering rods that is lower than that of the glass of the light guide rods. Relatively low softening temperatures of up to 50K for the glass of the scattering rods, and especially relatively low softening temperatures of up to 30K, have been found to be advantageous.

[0112] During the demarcation process, the matrix is ​​demarcated from the light guide rod, and the scattering elements of the glass elements are demarcated from the scattering rod. Therefore, the light guide rod is made of glass having a refractive index n1 and, more specifically, is not covered by cladding glass having a refractive index n2.

[0113] The means for fixing the arrangement of the preform, which consists of a light guide rod and a scattering rod, may be, for example, a clamp, which can be removed again later.

[0114] The matrix thus obtained, having at least one scattering element, is further provided with a rigid covering in a demarcation process. In the sense of the present invention, preferably, a rigid covering is used, which can be formed by a multi-part structure or a multilayer structure. In a preferred embodiment, this rigid covering has at least two, and particularly preferably at least three, covering tubes.

[0115] To manufacture a rigid cladding having two cladding tubes, a matrix having at least one scattering element can be placed inside the first cladding tube. The first cladding tube can then be positioned inside the second cladding tube.

[0116] In detail, this method may include the following steps, namely, - A step of preparing a matrix having at least one scattering element, The step of providing an arrangement in which a matrix having at least one scattering element is located inside a first cladding tube, - A step of positioning the first cladding tube inside the second cladding tube. - To obtain a diffuser base having a rigid covering portion, the arrangement is marked using a marking machine, and if necessary, cut. It can include...

[0117] Furthermore, when drawing the arrangement using the line-drawing equipment, the preform is rotated around its longitudinal axis, thereby forming a spiral arrangement of scattering centers centered on the longitudinal axis.

[0118] To manufacture a rigid cladding having three cladding tubes, a matrix having at least one scattering element can be placed inside the first cladding tube. The first cladding tube can then be positioned inside the second cladding tube, and this second cladding tube can then be positioned inside the third cladding tube.

[0119] Therefore, in detail, this method involves the following steps, namely, - Before marking the layout using the marking equipment, the second cladding tube is positioned inside the third cladding tube. It can further include

[0120] Of course, the order of this assembly can be configured differently, as long as the light guide rod and scattering rod, the first cladding tube, the second cladding tube, or the third cladding tube are also pre-assembled accordingly. This arrangement can then be fed into the drawing process in a drawing facility, where these components can be melted together to form a compact, closed body that can serve as the base for the desired diffuser element.

[0121] In this case, at least one of the cladding tubes can be sealed on one side, which facilitates the arrangement and provision.

[0122] Remarkably, even such pre-assembled arrangements, comprising three cladding tubes, or even more, and a matrix having at least one scattering element inside, can be molded into the desired diffuser element in just one step of a single drawing process. During heating and drawing, these cladding tubes soften and adhere to the components located further inside, thereby forming a triple cladding around the matrix with the scattering element.

[0123] Subsequently, the product obtained by heating and drawing can be divided or cut and / or subjected to appropriate subsequent processing.

[0124] By varying the parameters of velocity, temperature, and / or force in the line drawing process, a diffuser substrate that is at least partially or partially tapered in a conical shape can be obtained, possibly after preparation. In this case, at least in the tapered region, the scattering elements no longer extend parallel to the longitudinal axis of the diffuser substrate, but extend at a predetermined angle to the longitudinal axis.

[0125] The advantageous uses of the lighting systems described in various variations include, for example, use in photodynamic therapy (PDT) or photoimmunotherapy (PIT) for tumor treatment, use in endovascular laser therapy (EVLT) for the treatment of varicose veins, use in laser-guided interstitial hyperthermia (LITT) for the treatment of epilepsy or brain tumors, or use in the fields of dentistry, ophthalmology, and dermatology as mentioned at the beginning. In the field of dentistry, we can specifically mention its use in wound care or periodontal disease treatment. Furthermore, there are applications in brain research, where light can be used to stimulate individual brain regions and thereby treat disease symptoms.

[0126] Further use of the illumination systems described in various variations is intended for use in photodynamic therapy (PDT) for tumor treatment, in which at least one light guide with a diffuser element receives light emitted from other diffuser elements and transmits it via the light guide to a detector for spectroscopic analysis. In this case, the patient is provided with a diffuser light guide that receives light in addition to diffuser light guides that emit different types of light, and the response to the PDT treatment can be estimated based on the spectral difference between the incident light and the received light (see Finlay et al., Proc. SPIE Int. Soc. Opt. Eng. June 14, 2014; 5315: pp. 132-142). Furthermore, this can also be used to perform dosimetry tasks.

[0127] Furthermore, it is advantageous for industrial applications, such as inspection of hard-to-reach areas on or within machinery where homogeneous illumination is particularly important, as well as for spectroscopic applications, and for biochemical applications where light stimulates biochemical in vitro reactions.

[0128] The present invention will be described in more detail below based on the embodiments shown in the drawings. [Brief explanation of the drawing]

[0129] [Figure 1] This is a schematic diagram of a lighting system having a light guide and a diffuser element for PDT applications. [Figure 2] This is a schematic longitudinal cross-section of the diffuser element. [Figure 3] This is a schematic cross-sectional view of a preferred embodiment regarding the arrangement of scattering elements within the diffuser substrate. [Figure 4] This is a graph showing the progression of intensity changes. [Figure 5] This is a schematic diagram of a structure designed to prevent backscattered light from being blocked by the cladding on the outside of the light guide. [Figure 6]Figures a, b, c, and d show various different embodiments regarding the arrangement of scattering elements within the diffuser substrate. [Figure 7] Figures a and b show various examples of scattering elements within the matrix of the diffuser substrate. [Figure 8] Figures a, b, and c are schematic diagrams of various embodiments of the reflector surface of the diffuser substrate. [Figure 9] This is a schematic diagram of a diffuser substrate having a spiral arrangement of scattering centers centered on the longitudinal axis of the diffuser substrate. [Modes for carrying out the invention]

[0130] In the following detailed description of embodiments, the same reference numerals in the accompanying drawings refer to the same or identical components.

[0131] For a better understanding, the following definitions shall be used.

[0132] In the sense of this disclosure, the term "lighting system" includes lighting devices, in particular, lighting devices suitable for use for medical technical purposes, and in particular, lighting devices that are at least partially sterilizable and / or sterile when in contact with living tissue.

[0133] The phrase "for medical treatment and / or diagnostic systems" includes using or applying the lighting systems disclosed herein themselves as medical treatment and / or diagnostic systems.

[0134] Figure 1 schematically shows the structure of a lighting system 1 according to a preferred embodiment of the present invention. For example, a medical PDT application is shown here.

[0135] In the illustrated example, the illumination system 1 includes a light source 10, particularly a laser light source, that emits light in a predetermined spectral range when in operation. For PDT applications as described at the beginning, a laser is used that emits wavelengths tuned to match the biochemically modified dye (photosensitizer) administered beforehand, typically wavelengths in the visible region, such as 532 nm in the green spectral range, or, for example, 690 nm in the red spectral range. It should be noted that LED or LD-based light sources can also be used. However, given the achievable power density, laser-based systems are established here.

[0136] The light guide 30 is connected to the light source 10 by a plug 20 at its proximal end. In this specification, the end of the light guide 30 that receives light is referred to as the proximal end. The light guide 30 has a diffuser element 40 at its distal end, which can be inserted into tumor tissue 80 formed within healthy tissue 70 via a cannula (not shown herein). The area of ​​action of the diffuser element ideally corresponds to the area of ​​tumor tissue 80.

[0137] In this specification, the distal end generally refers to the other end of the light guide 30 that is located away from the proximal end of the light guide 30, and in particular from which light is emitted.

[0138] The laser beam reaches the diffuser element 40 via the incident light 41 at the diffuser element 40 and is radiated laterally along the length of the diffuser (light emission 42). In this case, it is important that the radiation is as homogeneous as possible along the length of the diffuser element 40. In particular, intensity peaks should be avoided. Ideally, the tumor tissue 80 will be killed after treatment by the photo-induced biochemical reaction as described at the beginning. Basically, a quartz fiber is used as the light guide 30, and the plug 20 is basically formed as a coaxial connector, a so-called SMA connector, in which the fiber is bonded inside the plug 20. In view of thermal load resistance, a plug 20 having a nickel silver sleeve may also be advantageous, in which case the light guide 30 is fitted, i.e., crimped, into the nickel silver sleeve by shape bonding through plastic deformation. Furthermore, when the laser output is relatively large, a plug 20 in which the fiber end of the light guide 30 is protected by a conical prism can also be used, which would be advantageous in case of misadjustment. As described above, the light guide may include a single fiber, such as a monomode or multimode optical fiber, comprising a core having a core diameter and a cladding, or it may include a fiber bundle having a fiber bundle diameter.

[0139] Figure 2 schematically shows the structure of the diffuser element 40 according to a preferred embodiment of the present invention.

[0140] The diffuser element 40 consists of a diffuser substrate 43 attached to the light guide 30 via a connection zone 44. The light guide 30, in the aforementioned applications, is often made of quartz glass with a core 31 having a refractive index n1 and a core diameter 31.1, usually between 200 and 600 μm, and a cladding 32 having a refractive index n2, where n1 > n2. The numerical aperture NA that can usually be achieved is about 0.22. Light incidence 41 is carried out through the incident surface 46 of the diffuser substrate 43. Typically, the light guide 30 further has an outer cladding 33, which is usually made of, for example, PMMA, PA (e.g., NYLON®) or a fluorinated polymer (e.g., TEFZEL®), and is also called a buffer. This outer cladding 33 is not shown in Figure 2.

[0141] In a preferred embodiment, the diffuser substrate 43 having a diameter of 43.1 includes a rigid covering portion 43.3 and a matrix 43.4 consisting of matrix elements 43.5 into which scattering elements 43.6 are mixed, or consists of a rigid covering portion 43.3 and a matrix 43.4 consisting of matrix elements 43.5 into which scattering elements 43.6 are mixed.

[0142] As mere examples, Figures 6a, 6b, 6c, and 6d show various embodiments of preferred arrangements of scattering elements 43.6 within the diffuser substrate 43. Furthermore, Figures 7a and 7b show various embodiments of scattering elements within the matrix 43.4 of the diffuser substrate 43. These embodiments will be described in more detail below.

[0143] (As shown in Figure 3) According to the present invention, the rigid covering portion 43.3 may consist of or include a plurality of, preferably at least two, coaxially arranged covering tubes or layers 43.3.1, 43.3.2, 43.3.3, each having different optical properties with respect to at least the transparency, refractive index and / or material of the covering tubes.

[0144] To ensure that the homogeneity requirement for the intensity of lateral radiation is met during operation, the diffuser substrate 43 includes 10 to 100 scattering elements 43.6 depending on the operating wavelength and diffuser length. Hereinafter, as a rule of thumb, it can be said that the longer the operating wavelength or the shorter the diffuser length, the more scattering elements 43.6 should be provided.

[0145] The ratio of the cross-sectional area of ​​the mixed scattering element 43.6 to the diffuser substrate 43 is ≤0.015, preferably ≤0.005, and particularly preferably ≤0.002. In this case, the scattering element 43.6 is oriented substantially parallel to the longitudinal axis 43.2 over the entire length of the diffuser substrate 43.

[0146] In an advantageous embodiment, the diameter of the diffuser substrate 43 is designed to be larger than the core diameter 31.1 or fiber bundle diameter 31.1 of the light guide 30, so that, on the one hand, uncontrolled scattered light does not enter, for example, the rigid covering portion 43.3. On the other hand, this facilitates the mounting and adjustment of the light guide 30 and the diffuser substrate 43 and / or compensates for mounting errors. Therefore, the ratio of the core diameter 31.1 or fiber bundle diameter 31.1 of the light guide 30 to the diameter of the diffuser substrate 43.1 with the scattering elements 43.6 mixed in is advantageously ≤1.0, preferably between 1.0 and 0.8. Depending on the desired radiation characteristics, a ratio of ≤0.8 can also be intended.

[0147] An optical element can be placed in the connection zone 44 between the proximal end of the diffuser substrate 43 and the distal end of the light guide 30. This optical element can be formed in a conical shape, for example, as a beam shaping element, a light guide element, or an optical fiber taper. Thus, it is also possible to geometrically adapt, for example, the difference in diameter. In this specification, the proximal end of the diffuser substrate 43 means the end of the diffuser substrate 43 on which light is incident.

[0148] To avoid scattered light from the connection zone 44 and to further mechanically stabilize the connection zone 44, a sleeve 48 made of plastic, glass, metal, or ceramic material is provided according to a preferred embodiment of the present invention, which allows light from the light guide 30 to pass through at a predetermined lateral angle in the direction of the longitudinal axis of the light guide 30, but blocks light that may be incident on the proximal end of the scatterer at the end face side. A sleeve 48 made of borosilicate glass has been found to be particularly effective in avoiding light absorption. Such glass is known, for example, as SCHOTT FIOLAX® 8412 by Schott AG.

[0149] A reflector surface 47 is provided at the distal end of the diffuser substrate 43, opposite to the proximal end, to optimize the radiation characteristics. This reflector surface 47 can be configured to be directionally reflective as a mirror element in the form of a thin metal plate, or as a thin mirror film of a support film on which a mirror layer has been deposited, or a coating having a reflectivity of >95%. For example, a diffusely reflective layer, preferably by applying a white paint, or by printing, has also been found to be advantageous.

[0150] In a further modification, the reflector surface 47 can be manufactured as a polished short section of wire made of aluminum or gold, in direct contact with the diffuser substrate 43. This provides an additional small heat sink that helps to avoid hot spots.

[0151] Furthermore, a dielectric reflective layer sputtered or deposited at the distal end of the diffuser substrate 43 has been found to be particularly advantageous, and this dielectric reflective layer consists of multiple layers and is tuned in terms of reflectivity to the wavelength of light being used. Geometric embodiments of the reflector surface 47 are described further below. In this way, reflectivity of, for example, >95%, preferably >99%, can be achieved.

[0152] The phrase "with respect to reflectance, it is tuned to the wavelength of light being used" means, within the scope of this disclosure, that when tuned, the highest possible reflectance is achieved at that wavelength, or conversely, that the maximum reflectance is located at each tuned wavelength. An example of such a reflective layer is a multilayer laminate consisting of alternating TiO2 and SiO2 layers, for example, having a reflectance of >99%, preferably >99.5%, for red light having, for example, (690±10) nm in the range of wavelengths used.

[0153] Such a laminate can be adapted to the wavelength being used at any given time, that is, it can be adjusted as described above. This allows for the achievement of ideal back reflection on the one hand, and the avoidance of hot spots on the other hand. Alternatively or supplementally, a silver layer with back passivation can be provided as the reflector surface 47. The reflective layer at the distal end can also be protected, for example, with adhesive droplets, in which case these adhesive droplets form a rounded cap when cured.

[0154] In PDT or PIT applications, so-called pilot light is often used, for example, to position the diffuser in vivo, which is distinctly different from the wavelength of use (e.g., 690 nm) in terms of output and, in particular, wavelength. On the one hand, an additional shielding element 60, for example, in the form of a ceramic or metal cylinder or a ceramic or metal sphere, can be provided downstream of the reflector surface 47 in the distal direction, and / or the laminate of the reflector surface 47 can also additionally achieve a high reflectivity of >80%, preferably >95%, and particularly preferably >99% with respect to the wavelength of the pilot light in the green spectral region between 500 nm and 580 nm.

[0155] The metallic shielding element 60 has the further advantage of being identifiable as a so-called X-ray marker or radiation marker in the X-ray image. This also applies to the sleeve 48 or additional sleeve provided in the region of the connection zone 44, provided that they are designed as thin-walled metallic sleeves. Typically, such metallic sleeves are manufactured from one or more materials with high atomic numbers, combinations thereof, or alloys. Examples include tantalum, platinum, iridium, or platinum-iridium alloys.

[0156] For further mechanical protection and / or for homogenization of radiant properties, a cover 49 made of a transparent and / or translucent colored or colorless material (silicone, glass, or quartz glass) may be provided, which surrounds the diffuser substrate at least partially or intermittently. In particular, additional homogenization can be achieved using a translucent material and / or a material containing scattering centers. Suitable examples include a corresponding body or tube made of silicone, Teflon, or a polyether block amide block copolymer, for example, commercially available as PEBAX®. As the cover 49, a thin-walled heat-shrink tubing, at least intermittently coated, made of, for example, PET, has been demonstrated, which can be constructed in single or multilayer configurations. This further assists or enables the light emission 42 by the Lambert radiator. In that case, the effective length 40.2 of the diffuser element 40 is the distance between the sleeve 48 and the reflector surface 47, and can extend, for example, over the entire length of the diffuser element 40 or over the effective length 40.2 of the diffuser element 40.

[0157] Between the diffuser substrate 43 and the cover 49, which is made of, for example, glass or plastic, a liquid immersion layer can be inserted to suppress surface irregularities on the diffuser substrate 43 that may occur and adversely affect the radiant behavior, such as dirt or surface roughness. In this case, on the one hand, a refractive index suited to the glass system, high transparency, and a sufficiently high viscosity in light of good adhesion should be considered. For example, glycerin or silicone (oil or adhesive) has been found to be suitable as the liquid immersion layer.

[0158] To avoid interference reflection, the reflector surface 47 can be additionally covered by a cover or cap 47.2, or the reflector surface 47 can be formed by a cover or cap 47.2, which encloses the diffuser substrate 43 in a short length laterally around its circumferential surface. In this case, the effective length 40.2 corresponds to the distance between the sleeve 48 and this protective cap. Therefore, if the sleeve 48 or cap 47.2 is made of metal, it can achieve the function of a radiometric marker, thereby making the effective length 40.2 or position of the diffuser element 40 identifiable in the X-ray image. The overall diameter 40.1 of the diffuser element 40 is typically 0.8 to 1.2 mm for PDT applications. Typically, the diameter 40.1 is slightly less than 1 mm. Here, the diameter of the cannula is important, as the diffuser element 40 is administered to the patient through this cannula.

[0159] The diffuser substrate 43 and the light guide 30 are attached within the connection zone 44 by a splicing or bonding process, for example, using a highly transparent adhesive with matched refractive values. During splicing, the light guide 30 and the diffuser substrate 43 are fused or joined together using corona discharge and / or a laser, usually a CO2 laser. Depending on the materials used for the diffuser substrate 43 and the light guide 30, it may be necessary to use an intermediate medium 45 to match their coefficients of thermal expansion. This intermediate medium 45 may be, for example, solder glass, intermediate glass, or an optical adhesive or bonding agent in the case of glass / quartz melting. Mechanical pressurization in the form of a sleeve is also conceivable and advantageous, in which case only the joint is filled with an optical bonding agent to avoid reflection loss. Optical elements located in the connection zone 44 between the proximal end of the diffuser substrate 43 and the distal end of the light guide 30 can also be coupled or connected.

[0160] The diffuser substrate 43 includes a matrix 43.4 in which scattering elements 43.6 are embedded in the matrix 43.4 in a preferred arrangement parallel to the longitudinal axis 43.2, as shown in the embodiment of Figure 2, along the entire length of the diffuser substrate 43. In this case, the axial spread of individual scattering elements may be smaller than the entire length of the diffuser substrate 43. In this case, multiple scattering elements 43.6 can be arranged so as to be more or less statistically uniformly distributed over the diameter 43.1 of the diffuser substrate 43, that is, multiple scattering elements 43.6 are provided arranged around the longitudinal axis, preferably arranged in a regular structure around the longitudinal axis.

[0161] In one embodiment, the diffuser substrate 43 each has a rigid covering portion 43.3 and a matrix 43.4, within which scattering elements 43.6 are embedded in the matrix 43.4 in a preferred arrangement parallel to the longitudinal axis 43.2 along the entire length of the diffuser substrate 43.

[0162] Figure 6a shows an arrangement in which multiple scattering elements 43.6 are arranged so as to be more or less statistically uniformly distributed over the diameter 43.1 of the diffuser substrate 43, that is, multiple scattering elements 43.6 are provided arranged around the longitudinal axis, and preferably these scattering elements are arranged in a regular structure around the longitudinal axis.

[0163] Figure 6b shows an arrangement in which the individual scattering elements 43.6 form a ring-shaped arrangement, that is, a plurality of scattering elements are provided, preferably arranged in a circular pattern around the longitudinal axis.

[0164] (As shown in Figure 6c) In further embodiments, only one scattering element 43.6 in the form of a tube or tubular section is embedded within the matrix 43.4, i.e., at least one scattering element (43.6) is tubular about the longitudinal axis, and in particular coaxial with respect to the longitudinal axis. The advantage of this arrangement is that the preform of the diffuser substrate 43 can be manufactured particularly inexpensively and reproducibly, because in this case the manufacturing process can be significantly simplified.

[0165] Basically, other geometric shapes relating to the arrangement of at least one scattering element 43.6 and / or more scattering elements 43.6 are also conceivable and advantageously feasible, such as hexagons, squares, and triangles.

[0166] Alternatively, (as shown in Figure 6d) the scattering elements 43.6 may be arranged to be more or less evenly distributed within the matrix 43.4, but in this case, one core zone 43.7 can be left open with the longitudinal axis 43.2 of the diffuser substrate 43 as the center, that is, the number of scattering elements 43.6 per unit area of ​​the cross-section of the diffuser substrate 43 outside the core zone 43.7 along the longitudinal axis is greater than the number of scattering elements 43.6 per unit area inside the core zone 43.7.

[0167] This arrangement has the advantage that laser light, which normally has a small numerical aperture (NA, typically <0.3), is first incident on the diffuser substrate 43, then only slightly scattered by the scattering elements 43.6 in the outer region centered on the core zone 43.7, and only after some distance from the incident surface 46 does the individual beam reach the scattering elements 43.6 in the edge region and become strongly scattered. This makes it possible to reduce the intensity of light emitted laterally immediately after the incident surface 46, and consequently achieve homogenization of the intensity transition along the diffuser.

[0168] If the concentration of scattering elements along the longitudinal axis of the diffuser substrate is constant, the intensity transition is I (l) =I0×e -l / k It typically exhibits an exponential decrease. In this case, it has been found that a suitable value for k is when k is approximately equal to the length of the diffuser substrate (40 mm in a specific example). From this, the intensity of radiation radiated laterally in the operating state decreases by about 1 / e along the diffuser substrate, which can be modified by further means to satisfy the homogeneity requirements mentioned above, particularly for PDT applications. In a preferred embodiment, a k value of 42 mm was obtained using 21 scattering elements, each with a diameter of 0.3 mm, as the starting material for the preform, and a matrix diameter of about 600 μm (starting geometry of the preform with a diameter of 34 mm).

[0169] In a particularly preferred embodiment of the present invention, the diffuser substrate 43 further has a rigid covering portion 43.3 which at least partially surrounds the matrix 43.4 on its circumferential surface. In the embodiment shown in Figure 2, the circumferential surface of the matrix 43.4 is completely surrounded by the rigid covering portion 43.3, but at least partial surrounding would already be sufficient.

[0170] The rigid covering portion 43.3 is advantageously formed as a multi-part or multi-layer structure, comprising at least two covering tubes or layers, preferably at least three covering tubes (43.3.1, 43.3.2, 43.3.3) and / or layers.

[0171] In order to homogenize the intensity transition, and also to prevent unwanted light return into the transmission fiber, which could potentially interfere with the control of the light source 10, or even cause the laser light source to switch off or the plug connector to undesirably overheat, the present invention offers further means for increasing the numerical aperture NA of the light 42.1 that is back-reflected at the reflector surface 47.

[0172] This can be advantageously achieved by grinding the distal end face or reflector surface 47 at an angle other than 90° with respect to the longitudinal axis 43.2 of the diffuser base 43, at least partially.

[0173] Figures 8a and 8b schematically show further embodiments of the reflector surface 47. According to this, the reflector surface 47 can be configured to be concave (Figure 8a) or convex (Figure 8b) in order to homogenize the intensity transition. This results in the reflected beam, which extends substantially parallel to the longitudinal axis 43.2, being reflected back at a steep angle with respect to the longitudinal axis 43.2, and consequently being scattered more frequently by the scattering element 43.6, thereby increasing the emission efficiency at the distal end of the diffuser element 40.

[0174] This further significantly reduces the beam component reflected backward, particularly within the light guide 30. A further, particularly inexpensive, means may be to grind the diffuser base 43 at an angle other than 90° with respect to the longitudinal axis 43.2. Faceted grinding, in which each surface forms different angles, primarily other than 90°, with respect to the longitudinal axis 43.2 of the diffuser base 43, would also be equally effective. The angular deviation from 90° is typically less than 5°.

[0175] As schematically shown in Figure 8c, the reflector surface 47 at the distal end of the diffuser substrate 43 may also be formed as a hollow and / or transparent body 47.1, which has a cover 47.2 that reflects into the hollow space and / or transparent body. This cover 47.2 can preferably be formed as a directional reflective or diffuse reflective coating and / or cap. The cover 47.2 may also terminate directly at the diffuser substrate 43 without a hollow space, and in both cases, the diffuser substrate 43 can be radially surrounded at least partially or segmentally on its circumferential surface over a short length at the distal end.

[0176] Therefore, the reflector surface 47 can be formed in a concave or convex shape and / or can be formed as directly continuous with the diffuser base 43, or it can be formed as being spaced apart from the diffuser base 43 while forming a hollow space between the reflector surface 47 and the distal end of the diffuser base 43, i.e., a body 47.1 and / or cover 47.2 as a hollow body with one side closed.

[0177] Figure 9 schematically shows only the filament-shaped scattering elements 43.6 of the diffuser substrate 43 in a helical arrangement centered on the longitudinal axis 43.2 of the diffuser substrate 43. Such a helical structure can be achieved by drawing the arrangement using a line-drawing machine and then rotating the preform around the longitudinal axis of the preform, thereby forming a helical arrangement of scattering centers 43.6 centered on the longitudinal axis 43.2.

[0178] Figure 3 shows a schematic cross-sectional view of a diffuser substrate 43 according to the present invention, having a diameter of 43.1 and a rigid covering portion 43.3 surrounding a matrix 43.4. Here, the rigid covering portion 43.3 surrounding the matrix 43.4 having scattering elements 43.6 is formed from a plurality of coaxial covering tubes 43.3.1, 43.3.2, and 43.3.3, each having different optical properties. In this case, the matrix 43.4 is formed from individual matrix elements 43.5.

[0179] However, in the sense of the present invention, an embodiment having only two cladding tubes 43.3.1 and 43.3.2 arranged coaxially with respect to each other is already possible and conceivable.

[0180] According to a particularly preferred embodiment of the present invention shown in Figure 3, the first cladding tube 43.3.1 surrounding the matrix 43.4 is made of a transparent material in which the refractive index is lower than that of the matrix 43.4. This is also called an optical cladding and ensures that the light incident by the light incident 41 is first guided into the matrix 43.4, thereby enabling it to interact with the scattering element 43.6, which in this case already makes it possible to achieve a high scattering efficiency.

[0181] In this embodiment, the second cladding tube 43.3.2 is formed as a scattering, i.e., a translucent tube, by incorporating further scattering elements. This allows so-called cladding modes, which are returned at the reflector surface 47 and incident on the cladding or the first cladding tube 43.3.1, to be emitted from the diffuser substrate 43, which further enhances the radiant intensity of the radiation 42. The second cladding tube 43.3.2 can also be configured as a ring-shaped arrangement of individual strongly scattering white glass rods.

[0182] In this case, the second scattering cladding 43.3.2 must be optically coupled to the first cladding 43.3.1, and the refractive index of the second cladding 43.3.2 must be higher than that of the first cladding 43.3.1. This allows for nearly isotropic radiation to be achieved based on multiple scattering within the second cladding 43.3.2. Furthermore, this achieves additional homogenization.

[0183] The outer third cladding tube 43.3.3 is used, in particular, as a mechanical stabilizer for the second cladding tube 43.3.2, thereby enabling the formation of a compact and robust diffuser substrate 43 by the drawing process. Furthermore, as already described with respect to Figure 2, a cover 49 made of a thin-walled polymer material, which can be configured to be clear without clouding, slightly translucent, and / or color-doped, can surround the diffuser substrate 43 and a portion of the light guide 30.

[0184] In a preferred embodiment, the matrix 43.4 is made of highly transparent optical glass, such as Schott N BK-7 optical glass from Schott AG. The scattering element 43.6 can be made of white glass, for example.

[0185] For the first cladding tube 43.3.1 and the third cladding tube 43.3.3, a highly transparent borosilicate glass named SCHOTT FIOLAX® 8412 from Schott AG has been found to be particularly suitable. This highly transparent borosilicate glass has a transmittance of approximately 92% in the wavelength range of 250 to 2000 nm and is therefore considered highly transparent in the sense of the present invention.

[0186] The second cladding tube 43.3.2 is made of a white glass tube in a preferred embodiment, and when white glass is used for the second cladding tube 43.3.2, it can be configured in the same way as or identically to the scattering element 43.6 in the matrix 43.4.

[0187] This structure has the advantage that all these components can melt together very well, thereby enabling the formation of a compact diffuser substrate 43 that does not contain hollow spaces, for example, in the form of voids or bubbles.

[0188] Typical layer thicknesses for cladding tubes 43.3.1, 43.3.2, and 43.3.3 are in the range of 5 μm to 50 μm, preferably in the range of 7 μm to 40 μm, particularly preferably in the range of about 10 μm to 30 μm, or 10 μm, when the diameter 43.1 of the diffuser substrate 43 is 500 μm.

[0189] Other structures of the rigid covering 43 are also possible and conceivable. Therefore, if further functionality is desired, the rigid covering 43 can, of course, be formed from a combination of covering tubes and / or layers, or from, for example, three or more covering tubes or layers. Thus, it is also possible to provide additional covering tubes, in which case these additional covering tubes surround the third covering tube at least partially.

[0190] A structure having only a first cladding tube 43.3.1 and a second scattering cladding tube 43.3.2 is also conceivable. In the embodiment of the present invention having only two cladding tubes 43.3.1 and 43.3.2, as described above, the first cladding tube 43.3.1 can be formed to be highly transparent, and the second cladding tube 43.3.2 can be formed as a white glass tube. In this case, mechanical stabilization can be guaranteed even with only the second cladding tube 43.3.2.

[0191] Figures 7a and 7b schematically show two further embodiments of the structure of the matrix 43.4 within the diffuser substrate 43, in cross-sectional views perpendicular to the longitudinal axis of the diffuser substrate 43.

[0192] Figure 7a illustrates scattering elements 43.6 interspersed as thin rods between multiple matrix elements 43.5 in the form of single rods within a preform. In the illustrated example, the scattering elements 43.6 fill the intermediate spaces (gaps) between the three single rods that make up the matrix elements 43.5. In the illustrated example, single glass rods with a diameter of 2 mm were used as matrix elements 43.5 to manufacture the preform. The scattering elements are formed from white glass rods with a thickness of 0.3 mm. After the hot drawing process, i.e., after being drawn down to the diameter 43.1 of the diffuser substrate 43, the scattering elements 43.6 are fused or welded and have a triangular, for example, hyperbolic triangular cross-section.

[0193] Figure 7b shows an alternative arrangement in which the diameter of the scattering element 43.6 is equal to or less than the diameter of the matrix element 43.5 formed as a single rod. Here, with respect to the scattering element 43.6 as, for example, a white glass rod, and the matrix element 43.5, the typical diameters in a correspondingly constructed preform before the drawing process are in the range of 0.5 to 1 mm. After the hot drawing process, i.e., after being drawn down to the diameter 43.1 of the diffuser substrate 43, the scattering element 43.6 is fused or welded and has a hexagonal, for example, a hyperbolic hexagonal cross-section.

[0194] By arranging scattering rods in the gaps of the preform, it becomes possible to achieve a greater number of scatterers and, consequently, better homogeneity, given the dimensions and cross-sectional ratio of the light guide rods. After the drawing process, the matrix elements 43.5 and scattering elements 43.6 can have circular, hexagonal, square, or triangular cross-sections, and in particular hyperbolic variations thereof, as the diffuser substrate 43.

[0195] Within the preform, the scattering elements 43.6, embedded as thin rods between multiple matrix elements 43.5 of the single-rod matrix 43.4, fill the intermediate spaces (gaps) between the three single rods that make up the matrix elements 43.5. Typically, single glass rods with a diameter of 2 mm are used as matrix elements 43.5 to manufacture the preform. The scattering elements are formed from white glass rods with a thickness of 0.3 mm. After the hot-drawing process, i.e., after being drawn down to the diameter 43.1 of the diffuser substrate 43, the scattering elements 43.6 are fused or welded and have a triangular, for example, hyperbolic triangular cross-section. Alternative arrangements are also possible in which the diameter of the scattering elements 43.6 is equal to or less than the diameter of the matrix elements 43.5 formed as single rods. Here, with respect to the scattering element 43.6, for example, as a white glass rod, and the matrix element 43.5, the typical diameters in a correspondingly constructed preform before the drawing process are in the range of 0.5 to 1 mm. After the hot drawing process, i.e., after being drawn down to the diameter 43.1 of the diffuser substrate 43, the scattering element 43.6 is fused or welded and has a hexagonal, for example, a hyperbolic hexagonal cross-section.

[0196] By arranging scattering rods in the gaps of the preform, it becomes possible to achieve a greater number of scatterers and, consequently, better homogeneity, given the dimensions and cross-sectional ratio of the light guide rods. After the drawing process, the matrix elements 43.5 and scattering elements 43.6 can have circular, hexagonal, square, or triangular cross-sections, and in particular hyperbolic variations thereof, as the diffuser substrate 43.

[0197] Embodiments of the scattering element 43.6 formed as a white glass rod, or a white glass tube or a scattering cladding tube, are intended to have scattering centers formed inside them by scattering particles, in which case the concentration of scattering particles in the scattering region is 10 ppm to 1000 ppm, preferably 20 ppm to 100 ppm.

[0198] The efficiency of emission from the scattering region, and therefore from the volume of the white glass or white glass tube of the scattering rod, depends not only on the scattering properties of the scattering particles as an intrinsic parameter, but also on the concentration of scattering particles within the scattering region itself.

[0199] In this case, the concentration expressed in ppm refers to the ratio of scattering particles to the mass ratio of the components of the white glass in which the scattering particles are mixed.

[0200] When heterogeneous regions of white glass are used as scattering centers, alternative embodiments are available, in which heterogeneous regions are preferably formed by phase separation and / or segregation of the glass components of the glass in which the heterogeneous regions are mixed.

[0201] The scattering centers formed by the heterogeneous regions preferably have a diameter of 10 nm to 1000 nm, and particularly preferably 100 nm to 800 nm.

[0202] Particularly preferably, these scattering centers are spherical. If the scattering center is not spherical, its maximum extent is understood to be its diameter.

[0203] Glass referred to herein as white glass, which contains heterogeneous regions as scattering centers, may preferably consist of As-containing and Pb-containing silicate glass. In this case, the scattering centers preferably have increased Pb and / or As content relative to the surrounding glass matrix.

[0204] Alternatively, the glass or white glass in which heterogeneous regions are mixed in as scattering centers may be made of fluorine-containing Ca-Zn silicate glass. In this case, the scattering centers preferably have an increased fluorine content relative to the surrounding glass matrix.

[0205] Figure 4 shows the intensity transition 103 measured using a cylindrical diffuser with an effective length of approximately 20 mm as an example, as shown in the transition diagram 100. The intensity 101, measured in units of mW / cm diffuser length and here expressed as "radiant excitation," is shown as dependent on the distance 102 to the incident surface.

[0206] The intensity transition 103 shows a relatively constant transition overall, compared to the typical slight exponential decrease in intensity 101. Such a transition is obtained as a solution to a difference equation for a homogeneous scattering transition over length, i.e., there is a constant ratio between incident radiation and scattered radiation in the longitudinal section.

[0207] By attaching a reflector surface 47 to the distal end of the diffuser substrate 43 (see Figure 2), a portion of the radiation can be reflected back again, and this radiation then provides an additional scattering contribution, particularly in the region in front of the reflector surface 47. Mathematically, this means the addition of two power functions.

[0208] A special structure of the rigid cladding 43.3 having at least two, or even three, cladding tubes, and additional means for expanding the NA of the back-reflected light to increase scattering efficiency, makes it possible to achieve a nearly homogeneous intensity transition with a deviation from the mean of less than ±10% over the effective length 40.2 of the diffuser. Furthermore, the overall efficiency of the desired lateral radiation can be improved to >85%, typically >90%. In this case, the effective length of the diffuser typically corresponds to the length of the diffuser substrate.

[0209] Figure 5 partially shows a structure for avoiding backscattered light in the cladding on the outside of the light guide. This phenomenon can, on the one hand, cause illumination of the light guide 30, but this can still be treated as merely a superficial effect, rather at low power levels.

[0210] However, especially when the laser power is relatively high, for example, higher than 2W, and the proportion of backscattered light is also relatively high, unacceptable heating may occur as a result, particularly in areas where this backreflected light strikes a component that absorbs this light over a small area. Here, in particular, backscattered light 42.1 that is guided towards the laser source through the transparent sleeve 48 and then strikes the outer cladding 33 of the light guide 30 has proven to be disruptive. Here, depending on the laser power or intensity of light emission used, the end face of the outer cladding 33 may be illuminated, which can be quite concentrated and in such cases may result in strong heating.

[0211] As an aid, a translucent or partially absorbing cover 50 can be provided, which partially scatters the backscattered light 42.1 from the sleeve, thereby significantly reducing the intensity in the area of ​​incidence onto the cladding 33 outside the light guide. The backscattered light 42.1 can be minimized or distributed over a larger area by partial absorption and / or multiple scattering from the partially absorbing cover 50, thereby i) becoming imperceptible or nearly imperceptible, and ii) significantly reducing the power density for heating.

[0212] Therefore, the partially absorbing cover 50 according to the present invention ideally fills the intermediate space between the sleeve 48 and the outer cladding 33 of the light guide 30, as schematically shown in Figure 5. This partially absorbing cover 50 can be realized as a separate element in the form of a translucent tubular section or heat-shrinkable tubing and / or as a recoating material on which scattering particles are distributed. Since it is necessary to recoat the fiber in the region of the connection zone 44 or up to the beginning of the outer cladding 33 in order to maintain a level of robustness, this level of robustness can be achieved in a single work step. Typical recoating materials consist of acrylate or epoxy materials and are used to retrospectively seal the surface of the light guide 30, thereby improving, in particular, mechanical stability.

[0213] This method is a further supplement to the aforementioned method for avoiding excessive backscatter intensity, and therefore, this method also contributes to optimizing the diffuser system according to the set task. [Explanation of symbols]

[0214] 1. Lighting System 10 light source 20 plugs 30 Light guide 31 cores 31.1 Core diameter or fiber bundle diameter 32 Clad 33 Outer cladding 40 Diffuser Elements 40.1 Diameter 40.2 Effective length 41 Light incidence 42 Light emission 42.1 Backscattered light 43 Diffuser substrate 43.1 diameter 43.2 Longitudinal axis 43.3 Rigid covering 43.3.1 First cladding tube 43.3.2 Second cladding tube 43.3.3 Third cladding tube 43.4 Matrix 43.5 Matrix elements 43.6 Scattering elements 43.7 Core Zone 43.8 The longitudinal axis of the scattering element, in particular the white glass rod 43.9 White glass rod 43.10 Angle 44 connection zones 45 Intermediate medium 46 Entrance plane 47 Reflector surface 47.1 Main Unit 47.2 Reflective cover / cap 48 sleeves 49 Cover 50 partially absorbent covers 60 Blocking elements 70 organization 80 Tumor tissue 100 Transition Line Diagram 101 Strength 102 Distance to the plane of incidence 103 Strength transition

Claims

1. A lighting system (1) especially for a medical-technical treatment and / or diagnostic system, said lighting system (1) comprising at least one light source (10) and a light guide (30), said light guide (30) being connectable and / or connected to said at least one light source (10) at a proximal end, said lighting system (1) having, at a distal end of said light guide (30), a diffuser element (40) having a longitudinal axis, said longitudinal axis extending perpendicular to an incident surface of said light guide (30) into said diffuser element (40), said diffuser element (40) radiating light laterally with respect to said longitudinal axis over an effective length (40.2) of said diffuser element (40) in an operating state, said diffuser element (40) having at least one diffuser substrate (43), said at least one diffuser substrate (43) comprising a matrix (43.4) having at least one scattering element (43.6), said matrix (43.4) being at least partially surrounded at a peripheral surface of said diffuser substrate (43) by a rigid coating (43.3), said rigid coating (43.3) being formed as a multi-part structure or a multi-layer structure, comprising at least two coating tubes or layers, preferably at least three coating tubes (43.3.1... 43.3.3) and / or layers, lighting system (1).

2. Said lighting system (1) further comprising at least one of the following features, namely: the feature that said at least one scattering element (43.6) is oriented substantially parallel to said longitudinal axis (43.2) along said longitudinal axis (43.2) of said diffuser substrate (43), or is arranged at a predetermined angle with respect to said longitudinal axis (43.2), or is arranged in a spiral shape, especially in the form of a spiral having a constant gradient, and / or in a spiral around said longitudinal axis (43.2), Means for homogenizing the radiation intensity along the longitudinal axis (43.2) of the diffuser substrate (43) are provided at the distal end of the diffuser substrate (43) and / or in the transition region between the light guide (30) and the diffuser substrate (43) and / or on the diffuser substrate (43) so as to at least partially or sectionally surround the diffuser substrate (43). The diffuser substrate (43) has a reflector surface (47) at the distal end of the diffuser substrate (43), and the reflector surface (47) can at least partially retroreflect the light passing through the diffuser substrate (43) again. The lighting system has a lateral radiation intensity distribution that deviates from the average lateral radiation intensity in the operating state by up to ±50%, preferably up to ±30%, and often preferably up to ±5%. further comprising at least one of the following: The lighting system (1) according to claim 1.

3. At least two of the coating tubes (43.3.1...43.3.3) are different from each other in at least one optical property. The optical properties preferably include the transparency, refractive index and / or material of the coating tube. The lighting system (1) according to claim 1.

4. The first coating tube (43.3.1) at least sectionally or completely surrounds the matrix (43.4). Preferably, the first coating tube (43.3.1) is formed to be substantially cloud-free and transparent and / or has a refractive index smaller than the refractive index of the material of the matrix (43.4). The lighting system (1) according to claim 1.

5. The second coating tube (43.3.2) at least sectionally or completely surrounds the first coating tube (43.3.1). Preferably, the second coating tube (43.3.2) is formed to be translucent or scattering and / or has a refractive index larger than the refractive index of the first coating tube (43.3.1). The lighting system (1) according to claim 1.

6. The first coating tube (43.3.1) contains transparent borosilicate glass and / or The second coating tube (43.3.2) contains white glass or consists of a ring-shaped arrangement of individual white glass rods. The lighting system (1) according to claim 1.

7. A third coating tube (43.3.3) is provided that at least partially or completely surrounds the second coating tube (43.3.2). Preferably, the third coating tube (43.3.3) is formed to be substantially cloudlessly transparent. The lighting system (1) according to claim 1.

8. At least one coating tube includes X-ray opaque glass. The lighting system (1) according to claim 1.

9. The matrix (43.4) having the at least one scattering element (43.6) and the rigid coating portion are configured as a closed and dense composite having no hollow space or bubbles. The lighting system (1) according to claim 1.

10. The diffuser substrate (43) having the matrix (43.4) and the at least one scattering element (43.6), and / or the coating tubes of the rigid coating portions (43.3, 43.3.1... 43.3.3) are made of glass or contain glass. These components are preferably melted together to form a compact and closed body. The lighting system (1) according to claim 1.

11. The at least one light source (10) includes a laser light source, a semiconductor-based light source, a light-emitting diode (LED), a laser diode (LD), or a laser. The lighting system (1) according to claim 1.

12. A reflector surface (47) is provided at the distal end of the diffuser substrate (43). The reflector surface (47) forms the end of the diffuser substrate (43) and / or at least partially or sectionally surrounds the diffuser substrate on its circumferential surface. During operation, the light is directly and / or diffusely reflected backward. The reflector surface (47) is preferably formed as a dielectric reflective layer sputtered or vapor-deposited on the distal end of the diffuser substrate (43). The lighting system (1) according to claim 1.

13. The reflector surface (47) includes a plurality of layers. The plurality of layers are preferably selected such that the maximum value of the reflectance is located at the wavelength of the light of the at least one light source (10). The lighting system (1) according to claim 12.

14. The maximum value of the reflectance is selected such that the first maximum value of the reflectance is located at the wavelength of use and at least one further second maximum value of the reflectance is located at a further wavelength, wherein the further wavelength is different from the wavelength of use, and the reflectance of the first maximum value and the reflectance of the at least one further maximum value are > 95%, preferably > 99%. The lighting system (1) according to claim 12.

15. The reflector surface (47) forms an angle of less than 90° with respect to the longitudinal axis (43.2) of the diffuser substrate (43), at least in sections, and it is possible to reflect the light (42.1) retroreflected during operation with a numerical aperture NA that is larger than the light incident on the reflector surface (47). The lighting system (1) according to claim 12.

16. In the region of the connection zone (44) between the light guide (30) and the diffuser substrate (43), a transparent sleeve (48) is arranged, preferably comprising glass or plastic. Preferably, a translucent or partially absorbing cover (50) is provided in the region between the sleeve (48) and the outer cladding (33) of the light guide, and the translucent or partially absorbing cover (50) is formed from a polymer mixed with scattering particles. The lighting system (1) according to claim 1.

17. The translucent or partially absorbing cover (50) is a tube part, a shrink tube part and / or a recoating polymer into which the scattering particles can be introduced in advance. The lighting system (1) according to claim 16.

18. A method for manufacturing a diffuser substrate, in particular for a lighting system according to any one of claims 1 to 17, the method comprising: - Refractive index n １ and / or n １ preparing a plurality of light guide rods made of glass having ' - The refractive index n １ and / or n １ a plurality of the light guide rods having ’, and at least one scattering rod made of glass or glass ceramic containing a scattering center, such that the longitudinal axis of the light guide rod and the longitudinal axis of the at least one scattering rod extend substantially parallel to each other, and arranging them so as to obtain a preform - heating the preform; - drawing and optionally cutting the preform in a drawing facility to obtain the diffuser substrate. A method having the above steps.

19. The method further comprises: - providing a matrix having at least one scattering element; - providing an arrangement in which the matrix having the at least one scattering element is arranged inside a first cladding tube; - positioning the first cladding tube inside a second cladding tube. ・To obtain a diffuser substrate having a rigid coating portion, the step of wire-drawing and optionally cutting the arrangement in a wire-drawing facility, further comprising, A method for manufacturing the diffuser substrate according to claim 18.

20. The method is, When wire-drawing the arrangement in a wire-drawing facility, the preform is rotated about the longitudinal axis of the preform, thereby forming a spiral arrangement of the scattering center (43.6) about the longitudinal axis (43.2). It has an additional step of doing so. A method for manufacturing the diffuser substrate according to claim 19.

21. The method is, ・Before wire-drawing the arrangement in a wire-drawing facility, the method further comprises the step of positioning a second coating tube within a third coating tube. A method for manufacturing the diffuser substrate according to claim 20.

22. A method of using the lighting system (1) according to any one of claims 1 to 17, The lighting system (1) as a component of a device for a medical treatment method, especially For photodynamic therapy (PDT) or photoimmunotherapy (PIT) aimed at tumor treatment, For endovascular laser treatment (EVLT) aimed at treating varicose veins, For laser-induced interstitial thermotherapy (LITT), or For use in the fields of dentistry, ophthalmology and dermatology, Used for A method of using the lighting system (1).

23. The lighting system (1) is used as a component of a device for photodynamic therapy (PDT) or photoimmunotherapy (PIT) aimed at tumor treatment, At least one light guide (30), together with a diffuser element (40), receives light emitted from other diffuser elements (40) and transfers it via the light guide (30) to a detector for spectroscopic analysis and / or dose observation. A method of using the lighting system (1) according to any one of claims 1 to 17.

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