WO2021175387A1

WO2021175387A1 - Medical endoscopic instrument

Info

Publication number: WO2021175387A1
Application number: PCT/DE2021/200029
Authority: WO
Inventors: Bernd Claus Weber; Moritz TEWES
Original assignee: Richard Wolf Gmbh
Priority date: 2020-03-03
Filing date: 2021-03-02
Publication date: 2021-09-10
Also published as: DE102020202687A1

Abstract

The invention relates to a medical endoscopic instrument having a distal elongated insertion portion (1) for minimally invasive insertion in a human or animal body, the insertion portion (1) comprising at least one LED, the LED (5) having a first illumination spectrum suitable for a fluorescence endoscopy, characterized in that a converging lens (29), a light filter (23) and a diverging lens (31) are arranged distal from the LED (5), the converging lens (29) being arranged between the LED (5) and the light filter (23), and the light filter (23) being arranged between the converging lens (29) and the diverging lens (31).

Description

Medical endoscopic instrument

description

[01] The present disclosure relates to a medical endoscopic instrument with a distal elongated insertion section for minimally invasive insertion into a human or animal body. It is known to use endoscopes to make video recordings of the interior of a human or animal body for purposes of medical diagnosis and / or therapy. It is customary to illuminate the inside of the body with a light source and to take an image using an image sensor, for example a CCD (charge-coupled device) or CMOS (complementary metal-oxide-semiconductor) sensor. Since the spectral sensitivity of such an image sensor generally differs from that of a human eye, a correction filter is usually set in the prior art in the image path in front of the image sensor in order to generate a natural color impression of the recorded image. The image sensors that are typically used are usually more sensitive than the eye, particularly in the red and infrared wavelength range, so that the correction filters used attenuate particularly strongly in this wavelength range. The disadvantage here, however, is that, because of the correction filter, significant portions of the light output that are coupled into the inside of the body and converted into heat there are not used for the image recording of the image sensor.

[03] WO 95/17845 proposes a dichroic correction filter for better use or saving of the coupled light output not to be placed in the image path in front of the CCD sensor, but to be arranged in front of an external light source or in a light fleece system of the endoscope. So it is Lieh † that the CCD sensor is not supposed to pick up, not even coupled into the body †. This protects the tissue against the coupling of unnecessary light output and the heat generated in the tissue as a result.

[04] The endoscopic video system known from WO 95/17845, however, is not suitable for being used either for white-light endoscopy or for fluorescence endoscopy. In contrast to white-light endoscopy, fluorescence endoscopy, which is used, for example, for the detection and localization of pre- and early malignant tissue, does not depend on a natural, true-color display of the tissue, but on fluorescence excitation, mi † which can distinguish pathological tissue from healthy tissue. The pathological tissue excited by means of light radiation itself or a bacterial accumulation indicating pathological tissue can fluoresce specifically and thus be localized in a recognizable manner in relation to the surrounding healthy tissue. Fluorescence endoscopy can, for example, be carried out as part of a photodynamic diagnosis (PDD) and / or photodynamic therapy (PDT) using a photosensitizer or marker substance that selectively accumulates in pathological tissue †. Alternatively, if necessary, endogenous fluorescence (autofluorescence) of the pathological tissue can be made visible without the use of a photosensitizer or marker substance †.

[05] DE 10 2018 202 243 A1 describes a medical endoscopic instrument that can be used either for fluorescence endoscopy or for white light endoscopy and at the same time protects the tissue against the coupling of unusable light power † by it is the coupled light output for the respective Purpose better use †. A light filter is used in front of the whitish LED.

[06] However, it is problematic that the light spectrum of the blue † LED intended for fluorescence endoscopy, for example, still has relatively high proportions in a wavelength range of 440 to 470 nm †, which the relatively weak fluorescence signal of the photosensitizer resp. Noise of marker material. A long-pass filter arranged in front of the image sensor, for example with a spectral edge at approx. 470 nm, would improve the signal-to-noise ratio for fluorescence endoscopy in blue light operation, but in white light operation it would undesirably produce blue and violet light components up to approx Block 470 nm in the visible light spectrum, which leads to color distortion †. A short-pass filter in front of the blue † LED with a spectral edge at approx. 440 nm makes more sense in principle, but at the same time reduces the amount of light emerging from the illumination path, which must be as high as possible for effective fluorescence excitation .

It is therefore an object of the present disclosure to provide a medical endoscopic instrument that provides the highest possible light yield with the highest possible signal-to-noise ratio for fluorescence endoscopy † and at the same time avoids color distortions in white light operation †.

[08] According to the present disclosure, a medical endoscopic instrument with a distal elongated insertion section †† for minimally invasive insertion into a human or animal body †, the insertion section having at least one LED †, the LED have a light spectrum suitable for fluorescence endoscopy †. A converging lens, a light filter and a scattering lens are arranged distal from the LED †, where- with the converging lens between the LED and the light filter and the light filter between the converging lens and the diffusing lens.

[09] The arrangement of the “collecting lens-light filter-scattering lens” on the distal side of the LED increases the light bulge considerably, with the light filter ensuring a good signal-to-noise ratio for fluorescence endoscopy. The “collecting lens-light filter-scattering lens” arrangement distal side of the LED is so efficient because the collecting lens first collects the Lieh † emitted by the LED in the form of a Lambert radiator † and focuses it towards the light filter so that the angle of incidence on the Light filter is as small as possible. With an increasing angle of incidence, for example in the case of a short-pass filter, the transmission spectrum can shift significantly towards the short-wave range. This is the case, for example, when the short-pass filter is a dichroic filter, that is to say an optical filter based on thin interference layers. The light yield can therefore decrease sharply with the angle of incidence. Since the converging lens minimizes the angle of incidence †, the light output is increased accordingly †. In order to achieve not only a spot, but a flat illumination of the tissue, † the diffuser lens arranged in the illumination path behind the light filter widen the light † from † ri †† cone again.

[10] Mi † "Luminous spectrum" here is an intensity distribution 7 (2) of the light as a function of the wavelength l 0be of light †. The mean intensity in a wavelength range between a wavelength li and a wavelength l2 is defined here as / =

Mi † "transmission spectrum" is a distribution of the percentage light transmittance † T (l) as a function of the wavelength l 0be of light †. The mean transmission or permeability in a wavelength range between a wavelength li and a wavelength length l2 is defined here † as T = If the functions 7 (2) and / or G (71) cannot be locally integrated for certain wavelengths or spectral lines in the first and / or second wavelength range, then such wavelengths or spectral lines are Ignore averaging. The luminous spectrum of the LED suitable for fluorescence endoscopy can, for example, have a relatively sharp peak at 405 nm to 410 nm with a half value width of approx. 20 nm. The LED would then be a blue light LED. A second light spectrum of a second LED, suitable for example for white light endoscopy, can correspond to a typical light spectrum of a white light LED between 410 nm and 710 nm. A second LED suitable for white light operation can be arranged in the insertion section parallel to the first LED suitable for fluorescence operation. Alternatively, a second LED can be arranged in the proximal area of the medical endoscopic instrument or outside the instrument instead of in the insertion section, in which case the white light † emitted by this second LED is preferably transmitted into the distal area via a fiber or a fiber bundle. In the following, the LED suitable for fluorescence operation will also be referred to as “first LED” if there is no second LED suitable for white light operation in the exemplary embodiment or if it is not arranged in the insertion section.

[1 1] The first LED, but preferably also the second LED, is arranged as a light source in the insertion section in order to generate light “in situ” in the body, so that no external light source or light guide system is required. Fluorescence endoscopy can be operated with the first LED and white light endoscopy with the second LED. It is preferably possible to switch between fluorescence mode with the first LED and white light mode with the second LED †. An image sensor, for example a CCD sensor or CMOS sensor, can accordingly be used and required for fluorescence endoscopy and white light endoscopy no correction filter in the form of a short-pass filter in the image path, which considerably reduced the amount of light that can be used for imaging in white light mode. With the instrument disclosed herein, fluorescence endoscopy can be performed as part of a PDD and / or PDT. However, preferred embodiments of the instrument can primarily be designed for the PDD if, for example, the first LED has a short-wave, blue first luminous spectrum in order to efficiently excite fluorescence.

[12] Optionally, the first LED, the second LED and an image sensor can be arranged on a common wall of the insertion section. This is preferably a distal end face of the insertion section, the first LED, the second LED and the image sensor being aligned distally in the longitudinal direction of the insertion section †, the second LED having a second luminous spectrum suitable for white light endoscopy †. In this embodiment in particular, the lateral installation space for placing the first LED, the second LED and the image sensor on the end face is very limited †. There are possibly only recesses with a diameter of 1 mm or less per LED or image sensor available in the wall of the insertion section. In extreme cases, the available diameter can even be as little as 0.5 mm.

[13] The light filter can optionally be a short-pass filter. For example, the short-pass filter can have a spectral edge at approx. 440 nm in order to allow shorter wavelengths with a mean transmission of over 90% to pass and to block higher wavelengths with a mean transmission of less than 10% in fluorescence mode. A long-pass filter in the image path distal from the image sensor can be designed in such a way that its spectral edge is also around 440 nm †, so that medium and long-wave components of the blue light component in white light operation are also included be allowed through to ensure good color reproduction in Weißlichtbe operation.

[14] Optionally, the converging lens can be a plano-convex lens and / or the diverging lens can be a plano-concave lens, the respective flat surface pointing in the proximal direction. This is particularly useful in order to minimize the axial length of the “collecting lens-light filter-scattering lens” arrangement and its axial distance from the LED over a large area and not only selectively, in order to capture as many LED beams as possible in the first and / or second lens . In order to reduce an undesirable keyhole effect that affects the efficiency of fluorescence endoscopy †, the LED should be arranged as far distally † as possible and the surface of the first lens facing the LED should be over a large area and not just at a minimal distance from the lens Have LED. The more compact the "collecting lens-light filter-scattering lens" arrangement and the shorter its axial distance to the LED or the larger its area with minimum distance to the LED, the further distal the LED can be and the greater the proportion of Light rays emitted by the LED, which reach the entrance surface of the first lens and are refracted by this towards the optical axis and can thus also reach the light filter and the second lens in order to minimize an undesired keyhole effect †.

[15] Optionally, the converging lens and / or the diverging lens can be a Fresnel lens. The axial length of the “converging lens-light filter-scattering lens” arrangement is thus further shortened †, since the axial “thickness” of the converging lens or diverging lens is reduced.

[16] Optionally, the converging lens and / or the diverging lens can have a fluid extension extending proximally. This is particularly advantageous in order, on the one hand, to reduce the installation costs of the “converging lens-light filter-scattering lens” arrangement and, on the other hand, to ensure an exact and stable alignment with respect to the optical axis. Afford. Since the dimensions of the individual components of the “collecting lens-light filter-scattering lens” arrangement in the lateral direction and especially in the axial direction are very small, the exact alignment and fixation of the components with respect to the optical axis can be a very demanding manual process if a sufficient quality in alignment and fixation is to be achieved. The fl ous extension facilitates the alignment with respect to the optical axis and the fixation enormously, which considerably reduces the installation costs of the “converging lens-light filter-scattering lens” arrangement. Namely, the extension of the sleeve can cover reference surfaces on the outside, which in the instrument only allow an unambiguous alignment with respect to the insfrumenfenachse. The sleeve extension can, for example, be inserted precisely into an inside diameter of a receptacle in the instrument. External soapy reference surfaces on the extension of the sleeve, for example in the form of an external soapy cylinder block surface, can be glued very easily and stably in a receptacle in the instrument. In particular, this is very stable and durable. In addition, a tight connection can be created in this way, so that no fluids can penetrate proximally past the “collecting lens-light filter-scattering lens” arrangement and into the instrument. The respective sleeve extension of the converging lens and / or the diffusing lens does not have to be closed all the way around in the circumferential direction or be a closed cylinder jacket surface, but can have circumferentially distributed lateral reference surfaces that allow a clear alignment and fixation with respect to the instrument axis. If the respective collar extension of the converging lens and / or the diverging lens is not a circumferentially closed reference surface in the form of a cylindrical surface ha †, but rather n> 3 circumferentially distributed lateral reference surfaces, these are preferably n-fold rotationally symmetrical with respect to the optical axis †.

[17] Optionally, the canal extension of the first lens and / or the canal extension of the second lens can be mounted on its receptacle in the instrument facing lateral surface be provided with a radially circumferential or only sequentially executed recess. To match this, ie arranged at a corresponding and defined height, the receptacle in the instrument on its inner soap can have a bulge, for example in the form of a rasp nose, in a radially circumferential or sequential manner. As a result, the two components can rust or interlock with one another. This has the advantage that the receptacle in the instrument and the divergent lens with its sleeve extension are axially in a defined position to one another and that the receptacle in the instrument and the divergent lens with its sleeve extension form a form fit, which makes them even stronger and connect more securely †. As an alternative or in addition to this, conversely, the radial bulge can be located on one of the sleeve extensions and the complementary radial recess can be located on the receptacle in the instrument. This allows a defined axial positioning of the corresponding lens with its sleeve extension opposite the receptacle in the instrument and also ensures a form fit. If the flexibility of the sleeve extension and / or receptacle is not great enough for a latching process, then the sleeve extension and receptacle can each be provided with a radial indentation in a coordinated axial position and the latching and the desired form fit with an additional flexible one O-ring (for example made of silicone) can be achieved †, which fills the space between the extension of the sleeve and the receptacle at the level of the recess †. On the basis of its flexibility, the O-ring can then ensure the necessary flexibility during installation or before it snaps into place. A circumferential seal can also be supported by such an O-ring †.

[18] Optionally, the sleeve extension can extend by a factor of 2 or more longer in the axial direction than the axial thickness of the respective lens on the optical axis. In particular, a factor of 5 or more can be advantageous here. The longer the sleeve extension extends in the axial direction †, the more firmly and precisely the "collecting lens-light filter-scattering lens "arrangement in the instrument. The sleeve extension can even extend a factor of 2 or more longer in the axial direction than the diameter of the respective Sam mell lens or divergent lens. An upper limit for the axial length of the respective sleeve shape † may represent the structural integrity and fragility of the respective component if it is made very long †. In addition, the axial length is limited in terms of manufacturing technology †.

[19] Optionally, the sleeve extension can be a one-piece, integral part of the converging lens or the diverging lens. In other words, the converging lens or the diffusing lens form a “pot” open proximally, whose distal “bottom” is optically effective and whose outer wall is mechanically effective for alignment, fixation and lateral sealing. This saves a separate mount †, into which the components of the “converging lens-light filter-scattering lens” arrangement would have to be fitted.

[20] Optionally, the light filter can be surrounded on the circumference by the sleeve extension of the diffusing lens. The light filter can thus be arranged as close as possible to a preferably proximal planar side of the optically effective part of the scattering lens in order to minimize losses.

[21] Optionally, the first LED can be surrounded on the circumference by the sleeve extension of the converging lens. The LED can thus be arranged as close as possible to a preferably proximal planar side of the optically effective part of the converging lens in order to minimize losses.

[22] Optionally, the converging lens can form a distal stop against which a proximal end of the sleeve extension of the diffusing lens is supported †. The stop is advantageous in order to achieve an exact axial positioning and fixation of the components of the “collecting lens-light filter-scattering lens” arrangement with respect to one another. [23] Optionally, the sleeve extension of the diverging lens can at least partially encompass the converging lens. The sleeve extension of the converging lens preferably forms a distally acting stop against which a proximal end of the sleeve extension of the dispersing lens is supported †. A first distal section of the sleeve extension of the converging lens preferably has a smaller outer diameter than a second proximal section of the converging lens. The outer diameter of the first distal section of the sleeve extension of the converging lens preferably fits into the inner diameter of the sleeve extension of the divergent lens. The outer diameter of the second distal section of the sleeve extension of the converging lens preferably corresponds to the outer diameter of the sleeve extension of the divergent lens. The distal de stop of the converging lens is preferably formed by a continuous paragraph between the first and second portion of the Hül senfortsatzes of the converging lens.

[24] Optionally, the sleeve extension of the collecting lens and / or the diverging lens can be produced by removing a blank core by means of an abrasive method, such as, for example, selective laser-induced etching (SLE). For example, components made of sapphire and glass can be manufactured using an SLE process. The raw core can be removed with an accuracy of 1 micrometer using a microscanner and a precise axis system. The resulting surfaces can have an average roughness depth R _z of less than 1 micrometer.

[25] Optionally, the sleeve extension of the converging lens and / or the diverging lens can be produced by a combined additive and ablative process. For example, in a first step, nanoparticles of high-purity quartz glass can be mixed with a small amount of liquid plastic and cured by light using stereolithography at certain points. The remaining liquid material is then in one second step washed out in a solvent bath so that only the desired, hardened structure remains. The plastic still mixed into this glass structure can then be removed by heating. In a final sintering process, the glass can be heated † to such an extent that the glass particles fuse together.

[26] Optionally, the sleeve extension of the converging lens and / or the diverging lens can be produced by a purely additive process. The glass can be applied in layers using an oven that functions as a melting and extrusion unit. A plasma torch can be used to smooth the surfaces.

[27] Optionally, the second LED can be offset from the first LED † in the distal direction † in the insertion section ††. Since the “converging lens-light filter-scattering lens” arrangement is arranged distal to the first LED, the second LED can be arranged further distal to the end face of the insertion section of the instrument, which reduces a keyhole effect in white light mode and illuminates it Enlarged solid angle in white light mode.

[28] Optionally, the second LED can be placed in the proximal area of the medical endoscopic instrument or outside of it instead of in the insertion section, with the light emitted by this second LED then being fed into the insertion section via a fiber or a fiber bundle. † is transmitted.

[29] Optionally, in a plane perpendicular to the viewing direction, an image sensor can have essentially the same distance to the first LED as to the second LED, and preferably be arranged between the first LED and the second LED. As a result, a user can easily switch between white light endoscopy and fluorescence endoscopy, oh ne that the lighting angle and / or the lighting intensity or the shadow cast in the image change significantly. It is true that different distances could be compensated for by different firing of the first LED and the second LED, but this would be energetically less efficient. The image sensor is preferably arranged centrally on the end face. The first and second LED can be offset laterally † from this with the smallest possible and the same lateral distance on the front side. Alternatively, instead of in the insertion section, the second LED can also be placed in the proximal area of the medical endoscopic instrument or outside it, in which case the energy emitted by this second LED is transmitted into the insertion section via a fiber or a fiber bundle will.

[30] Optionally, the “converging lens-light filter-scattering lens” arrangement and the first LED can be arranged in a recess in a wall of the insertion section, the wall defining an outer surface and the spacing of a light shield of the first LED from the outer surface is at most two thirds of the diameter of the recess. The outer surface can preferably be an end surface of the insertion section. The recess in which the first LED sits † causes † a certain "tunnel vision" or keyhole effect †, since the first LED is located proximally opposite the outer surface † because of the upstream “converging lens-light filter-scattering lens” arrangement.

[31] Optionally, at least one bluish † permeable protection † can be arranged † distal to the control lens †, the axial thickness of the protective element being thinner than the axial thickness of the light filter. The at least one protective strap † can be a protective glass that is as thin as possible, Schu † zkuns † s † off and / or a silicon dioxide layer † applied to the distal side of the diffuser lens. The protective strap † can Protect the diffuser lens against mechanical damage such as scratches and chemical damage such as from aggressive body fluids, cleaning or processing media and / or oxidation.

[32] Optionally, the second lens, which is preferably designed as a divergent lens, can be made of a hard or scratch-resistant and chemically resistant material, for example sapphire. The protective strap † can then be dispensed with. This can further reduce the keyhole effect.

[33] Optionally, a plurality of n> 2 first LEDs and / or a plurality of m> 2 second LEDs in a plane perpendicular to the optical axis can be arranged in n-numbers or m-numbers rotationally symmetrically with respect to a line of sight of the image sensor in the insertion section. be nice. This reduces unwanted shadows both for white light endoscopy and for fluorescence endoscopy. An equal number of first LEDs and second LEDs, that is to say n = m, can be provided, which are arranged in a circle around the image sensor in such a way that first LEDs and second LEDs alternate around the circle. If the first LEDs are used as relatively weak blue LEDs for fluorescence endoscopy, it can, however, be advantageous, for example, to provide more first LEDs than second white LEDs, that is to say m> n.

[34] The disclosure is explained in more detail below using an exemplary embodiment shown in the drawings. Show it:

1 shows a schematic longitudinal section through a distal section of an insertion section according to an exemplary embodiment of the medical endoscopic instrument disclosed herein; 2a shows a schematic longitudinal section to illustrate the basic emission characteristics of an LED on a light filter;

2b shows a transmission spectrum of a light filter as a function of the angle of incidence on the light filter;

FIG. 2c shows a schematic longitudinal section to illustrate the change in the beam path compared to FIG. 2a when a converging lens is positioned between the LED and the light filter; FIG. and

3a-c schematic longitudinal sections of an optical arrangement of LED and light filter with lens systems according to various embodiments of the medical endoscopic instru ment disclosed herein; and

3d-f schematic longitudinal sections through a distal section of an insertion section according to various exemplary embodiments of the medical endoscopic instrument disclosed herein.

[35] FIG. 1 shows a distal end section of an insertion section 1 of a medical endoscopic instrument. The insertion section 1 is intended to be introduced into a human or animal body in a minimally invasive manner, in order to be able to illuminate or irradiate it with † Lieh † and to enable video or image transmission from inside the body . In order to make the insertion minimally invasive, an outer diameter A of the insertion section 1 is as small as possible and in this exemplary embodiment is less than 5 mm.

[36] A first LED 5, a second LED 7 and an image sensor 9 are arranged next to one another on a distal end face 3 of the insertion section 1. order †, which are aligned distally in a common viewing direction x, which in this exemplary embodiment corresponds to the longitudinal direction of the insertion section 1 †. The first LED 5, the second LED 7 and the image sensor 9 are each arranged in a recess 1 la, b, c in a front wall 13 of the insertion section 1 †. The end wall 13 defines an outer surface 15 on the end face 3 of the insertion section 1. The first LED 5, the second LED 7 and the image sensor 9 are each arranged behind protective elements 17a, b, c in the form of thin protective glass panes, all of which are aligned with the outer surface 15 on the end face 3 of the insertion section 1 and protect against mechanical damage such as scratches and chemical damage such as from aggressive body fluids, cleaning or treatment media and / or oxidation. The protective elements 17a, b, c can also be configured as a common protective glass pane that overlaps the first LED 5, the second LED 7 and the image sensor 9. The protective elements 17a, b, c are permeable to whitish † and in this exemplary embodiment have a refractive index of at least 1.75 as well as a higher breaking strength and hardness than conventional optical glass. The protective elements 17a, b, c can be formed from a synthetic monocrystalline crystal †. The protective elements 17a, b, c are optional here, however, since the optical elements located proximally can themselves be sufficiently resistant or can have a correspondingly resistant protective layer on the distal side.

[37] The first LED 5 has a first light spectrum suitable for fluorescence endoscopy, which here has a peak between 405 nm and 410 nm with a half width of 20 nm in the blue wavelength range. With this blue light † of the first LED 5, a photosensitizer, which selectively accumulates in pathological tissue †, can fluoresce in the red world as part of a photodynamic diagnosis (PDD) and / or photodynamic therapy (PDT). length range †. Such a fluorescence in the red wavelength range can be well picked up by the image sensor 9, which is not preceded by a short-pass filter. The image sensor 9 is preceded by an objective 21 and a long pass filter 23 with a spectral edge at approximately 440 nm distally. The long-pass filter 23 blocks short-wave blue light from the first LED 5, which is scattered back directly from the body, but allows enough blue light through the second LED 7 for good color reproduction during white light operation. The first luminous spectrum of the first LED 5, however, has significant proportions above 440 nm, the direct reflections of which on the object to be observed, for example on human tissue, make the fluorescence image noisy. Since the spectral edge of the long-pass filter 23 cannot be shifted further into the long-wave without impairing the coloring in white light operation, the first LED 5 is preceded by a short-pass filter 25 with a spectral edge at approx. 440 nm.

[38] The second LED 7 has † a second light spectrum suitable for white light endoscopy, which has a peak in a first wavelength range from 400 nm to 500 nm † and in a second wavelength range from 550 nm to 700 nm with increasing wave length decreasing †. The first LED 5 can have the same light spectrum as the second LED 7, provided that the fluorescence excitation required for the intended fluorescence endoscopy can be brought about. In this case, the first LED 5 and the second LED 7 can be of the same type.

[39] In this exemplary embodiment, the second LED 7 is offset from the first LED 5 in the distal direction. This is due to the fact that the short-pass filter 25 with a spectral edge at approx. 440 nm is arranged in front of the first LED 5 and behind the protective belt † 17a. The Lieh † of the first LED 5 is determined by the short-pass filter 25 in accordance with the transmission spectrum † - rum 27 (see Fig. 2b, where T is the transmission in percent †) in a long-wave wavelength range above the spectral edge less transmitted on average than in a short-wave wavelength range below the spectral edge. However, as can be seen from FIG. 2b, the position of the spectral edge of the short-pass filter 25 depends on the angle of incidence Q (see FIG. 2a). Since the first LED 5 would strike the short-pass filter 25 like a lamberf radiator † and thus large light fan files would hit the short-pass filter 25 at a high angle of incidence Q and these light components could therefore only pass through the short-pass filter 25 with very high losses first LED 5 and the short-pass filter 25 a converging lens 29 switched †. As can be seen in FIG. 2c, the collecting lens 29 significantly reduces the mean angle of incidence Q, so that the light yield for the fluorescent light is significantly increased.

[40] Because of the position of the first LED 5, which is offset proximally towards the rear, in contrast to the second LED 7, an undesirable keyhole effect is countered by the fact that a diffusing lens 31 is connected upstream of the short-pass filter 25 distal towards the short-pass filter 25. As shown in FIG. 3a, the illuminated solid angle can be increased in this way. In Fig. 3b it becomes clear that the luminous yield can be increased primarily by the fact that the converging lens 29 is designed as a planoconvex lens, which is placed in the beam path so that its plane surface points to the LED 5 and also the distance between the plane surface and the LED 5 is minimal, with an air gap † preferably remaining between the two components † in order to maintain a sufficiently high jump in the refractive index. This makes it possible for those light beams which leave the LED 5 at a large angle with respect to the normal to the surface to hit the converging lens 29 and are refracted by it towards the optical axis. As a result, the light rays can pass through the light filter 25 and the scattering lens 31 and thus reach the object to be illuminated, for example the tissue to be examined. The procedure described above The planoconvex lens has the further advantage that, in comparison with the procedure shown in FIG wrestlers are, so the Lichfausbeufe can be increased further. The particularly strongly curved converging lens 29 can, as shown in FIG. 3c, be shortened in its axial length † if it is designed as a Fresnel lens †. Although not shown, the diverging lens 31 can also be made thinner † as a Fresnel lens.

[41] Fig. 3d shows † the basic “converging lens-light filter-scattering lens” - arrangement distal from the first LED 5 in the distal end of an insertion section 1. However, the exact alignment, fitting and fixing of the “converging lens shown in FIG -Lichffilfer- scattering lens “arrangement in the distal end of a Einführabschniffs 1 because of the small axial length of the individual components and in particular because of the small fleas of the respective lateral surfaces that act as interfaces to the recess 1 1a, very complex, inaccurate and unstable.

3e and 3f show particularly advantageous embodiments of the “collecting lens-light filter-scattering lens” arrangement, in which the collecting lens 29 has a fluid extension 33 and the divergent lens 31 has a fluid extension 35 †. The fl uid extensions 33, 35 are an integral part of the lens 29, 31, which are each made in one piece. , create †. Alternatively, the fl uid continuations 33, 35 with the associated actual lenses 29, 31 can also be produced by additive processes or by combined additive and abrasive processes. The fl uid continuations 33, 35 form an external reference surface, with the aid of which the respective lens 29, 31 moves much faster, can be positioned and fixed more stable, easier and more accurate in the distal end of an insertion section 1. The sleeve shape 33, 35 extends † by a factor of 2 or more longer in the axial direction than the axial thickness of the respective lens on the optical axis.

The light filter 25, which is arranged as close as possible to the planar proximal side of the scattering lens 31, is surrounded on the circumference by the sleeve extension 35 of the scattering lens 31. The converging lens 29 also protrudes with its curved distal side into the sleeve extension 35 of the diverging lens 31. The first LED 5 is in turn surrounded on the circumference by the sleeve extension 33 of the converging lens 29. The converging lens 29 forms † a stop 37 acting distally, against which a proximal end 39 of the sleeve extension 35 of the scattering lens 31 is supported †. As a result, the lenses 29, 31 are aligned exactly coaxially with one another in relation to the optical axis † and can be fitted easily, quickly and safely.

In Fig. 3f an embodiment is shown in which the sleeve extension 35 of the scattering lens 31 at least partially surrounds the converging lens 29 and preferably also a distal portion 41 of the Hülsenf ortsatzes 33 of the converging lens 29 †. The stop 37 is arranged further proximally than the planar side of the collecting lens 29. The first distal section 41 of the sleeve extension 33 of the collecting lens 29 has a smaller outer diameter than a second proximal section 43 of the sleeve extension 33 of the collecting lens 29. The outer diameter of the first distal section 41 of the sleeve extension 33 of the converging lens 29 fits into the inner diameter of the sleeve extension 35 of the scattering lens 31. The outer diameter of the second distal section 43 of the sleeve extension 33 of the collecting lens 29 corresponds approximately to the outer diameter of the sleeve extension 35 of the diverging lens 31. The distal stop 37 of the collecting lens is preferably provided by a circumferential shoulder between the first 41 and second section 43 of the sleeve extension 33 of the converging lens 29 educated. The embodiment of the “collecting lens-light filter-scattering lens” arrangement shown in FIG. 3f has the advantage that the components of the “collecting lens-light filter-scattering lens” arrangement have relatively large reference surfaces with respect to one another, which allow the components to be fixed in a simple, precise and stable manner allow each other. As a result, the “collecting lens-light filter-scattering lens” arrangement can be fitted quickly, precisely and stably into a distal end of an insertion section 1 as a stable, pre-assembled unit.

[45] The numbered designations of the components or directions of movement as “first”, “second”, “drifts” etc. are chosen here purely arbitrarily to distinguish the components or directions of movement from one another and can be chosen differently as desired. It is not connected with any degree of importance. A designation of a component or technical feature as “first” should not be misunderstood to the effect that there must be a second component or technical feature of this type. In addition, any procedural rules, unless explicitly stated otherwise or absolutely necessary, can be carried out in any order and / or partially or completely overlapping in time. [46] Equivalent embodiments of the parameters, components or functions described herein, which in view of this description appear obvious to a person skilled in the art, are to be included herein as † as if they were explicitly described. Accordingly, the scope of the claims is intended to include such equivalent embodiments. “Can” features designated as optional, advantageous, preferred †, desired or similar are to be understood as optional and not as limiting the scope of protection.

[47] The embodiments described are to be understood as illustrative examples and are not an exhaustive list of possible ones Embodiments represent. Each feature that became apparent in the context of an embodiment can be used alone or in combination with one or more other features, regardless of the embodiment in which the features were described in each case. While at least one embodiment is described and shown herein, modifications and alternative embodiments that appear obvious to a person skilled in the art in view of this description are included within the scope of this disclosure. Furthermore, the term “have” is not intended to exclude additional other features or method steps, nor is “a” or “an” intended to exclude a plurality.

[48] List of reference symbols:

1 insertion section ††

3 face

5 first LED

7 second LED

9 image sensor l, a, b, c recess 13 front wall

15 external surface

17a, b, c Schufzelemen †

21 lens

23 long pass filters

25 short pass filters

27 Transmission spectrum of the Kurpassfilter

29 converging lens

31 diverging lens

33 sleeve extension of the converging lens

35 Hülsenfortsafz of the scattering lens

37 stop

39 proximal end of the hülsenforfsafzes of the scattering lens distal first section of the sheath extension of the converging lens, proximal second section of the sheath extension of the converging lens

Claims

Expectations

1. Medical endoscopic instrument with a distal elongated insertion section (1) for minimally invasive insertion into a human or animal body, the insertion section †† (1) having at least one LED (5) †, the LED (5) a light spectrum suitable for fluorescence endoscopy †, characterized in that a converging lens (29), a light filter (23) and a diverging lens (31) are arranged distally from the LED (5), with the converging lens (29 ) is arranged between the LED (5) and the light filter (23), and the light filter (23) between the converging lens (29) and the diffusing lens (31) is arranged †.

2. Medical endoscopic instrument according to claim 1, wherein the light filter (23) is a short-pass filter.

3. Medical endoscopic instrument according to claim 1 or 2, wherein the converging lens (29) is a plano-convex lens and / or the diverging lens (31) is a plano-concave lens.

4. Medical endoscopic instrument according to one of the preceding claims, wherein the converging lens (29) and / or the diverging lens (31) to the first LED (5) is planar.

5. Medical endoscopic instrument according to one of the preceding claims, wherein the converging lens (29) and / or the diverging lens (31) is a Fresnel lens.

6. Medical endoscopic instrument according to one of the preceding claims, wherein the converging lens (29) and / or the Diffusing lens (31) has a sleeve extension (33, 35) extending proximally †.

7. Medical endoscopic instrument according to claim 6, wherein the sleeve extension (33, 35) extends by a factor of 2 or more longer in the axial direction than the axial thickness of the respective lens (29, 31) on the optical axis.

8. Medical endoscopic instrument according to claim 6 or 7, wherein the sleeve extension (33, 35) is a one-piece, integral part of the converging lens (29) and / or the diverging lens (31).

9. Medical endoscopic instrument according to one of Ansprü che 6 to 8, wherein the light filter (25) is surrounded circumferentially by the sleeve extension (35) of the scattering lens (31).

10. Medical endoscopic instrument according to one of Ansprü che 6 to 9, wherein the LED (5) is surrounded on the circumference by the Hülsenf ortsatz (33) of the converging lens (29).

1 1. Medical endoscopic instrument according to one of claims 6 to 10, the converging lens (29) acting distally forming the stop (37) against which a proximal end (39) of the sleeve extension (35) of the diffusion lens (31) is supported †.

12. Medical endoscopic instrument according to one of Ansprü che 6 to 1 1, wherein the sleeve extension (35) of the scattering lens (31) at least partially engages around the converging lens (29).

13. Medical endoscopic instrument according to one of claims 6 to 12, wherein the sleeve extension (33, 35) of the collecting lens (29) and / or the diverging lens (31) by removing a blank core by means of an abrasive process, such as selective laser etching (SLE) is generated.

14. Medical endoscopic instrument according to one of claims 6 to 12, the sleeve extension (33, 35) of the converging lens (29) and / or the scattering lens (31) being produced by an additive manufacturing process.

15. Medical endoscopic instrument according to one of the preceding claims, wherein the sleeve extension (33, 35) is generated by a combined additive and ablative process.

16. Medical endoscopic instrument according to one of the preceding claims, wherein an image sensor (9) is arranged on a distal end face (13) of the insertion section (1), on which the LED (5) and a second LED (7 ) are arranged †, with the second LED (7) having a second light spectrum suitable for white light endoscopy †.

17. Medical endoscopic instrument according to claim 14, wherein the image sensor (9) in a plane perpendicular to the longitudinal direction (x) of the insertion section (1) is essentially the same distance from the first LED (5) as from the second LED (7) and preferably between the first LED (5) and the second LED (7) †.