Optical attachment component for an endomicroscope and endomicroscope

Abstract

An optical attachment component (15) for an endomicroscope (1) is provided. This comprises - an optical axis (OA) folded at least once; - an imaging optic (19) comprising at least two lenses (33A, 33B, 35A, 35B, 37A, 37B, 43A, 43B, 45A, 45B, 47A, 47B) which comprises an object-side optic end (38, 48) to be directed towards an object to be observed, and - a deflection element (21) arranged at the object-side optical end (38, 48), which has an object-side deflection element end (21A) facing away from the object-side optical end (38, 48) and with which the optical axis (OA) is folded at an angle from the angular range greater than 0 degrees and a maximum of 90 degrees. A transparent closure element (25) with an object-side closure surface (25A) facing away from the deflection element is arranged downstream of the object-side deflection element end (21A). The imaging optics (19) have an object-side focal point located on the side of the transparent closure element (25) facing away from the deflection element, outside the attachment component (15), at a maximum of 650 µm in front of the object-side closure surface (25A). In addition, an endomicroscope with such an attachment component is provided.

Description

[0001] The present invention relates to an optical attachment component for an endomicroscope. The invention also relates to an endomicroscope, in particular an endomicroscope in which image acquisition is performed using an optical fiber with a vibrating distal fiber end.

[0002] In some surgical fields, such as neurosurgery and ophthalmic surgery, endomicroscopes are used for minimally invasive visualization of a site. These can usually display the site with a resolution of 10 µm or better, which enables the examination of the fine tissue structure, i.e. the cellular makeup of the tissue. For this purpose, one or more thin optical fibers with core diameters in the range of 10 micrometers or less can be used for imaging. These fibers are used to scan the site in the longitudinal direction of the optical fiber and / or perpendicular to the longitudinal direction of the optical fiber. The light absorbed by the optical fiber is then transmitted to a detector, which detects the amount of light as an image point for each scanned object point.Based on the detected pixels and the respective location of the oscillating optical fiber where the pixel was acquired, a two-dimensional image is then compiled. If a scan is also performed in the longitudinal direction, a three-dimensional image can also be generated. The total diameter of the optical fibers used is often less than 500 micrometers and sometimes less than 250 micrometers.

[0003] For scanning transverse to the longitudinal direction of the optical fiber, the distal end of the fiber is oscillated, allowing image information to be acquired from different locations within the site during one oscillation period. For scanning in the longitudinal direction, confocal systems or optical coherence tomography (OCT) can be used. What all of these systems have in common is that they can be implemented with a tubular section that can be inserted into the body and has a diameter of only a few millimeters. Typical diameters of the tubular sections of endomicroscopes are 1 to 5 mm.

[0004] Examples of endomicroscopes are described in DE 10 2020 105 696 A1, DE 10 2021 109 825 A1, or JP 2014145941 A.

[0005] To visualize the tissue in situ, it is advantageous if the distal end of the section that can be inserted into the body can be placed on the tissue to be visualized, especially if a scan is also to be performed in the longitudinal direction. This is because the longitudinal scanning range of confocal systems and optical coherence tomography systems is very limited, and one wants to see as far into the tissue as possible from the tissue surface. However, if the canal wall is to be visualized in narrow channels or the endomicroscope is to be inserted into cavities through narrow channels, it can be difficult to meet these requirements, as the narrow channels allow no or only very slight tilting of the tubular section of the endomicroscope that can be inserted into the body.Therefore, there is a need for a system that can be used to equip or retrofit an endomicroscope for visualization of the canal wall in narrow canals or the cavity wall.

[0006] While it is known, for example, from DE 10 2020 129 529 B3 to provide a deflection prism in an endoscope that enables an oblique line of sight, and endoscopes that enable a lateral viewing direction are also known from US 2023 / 0 404 370 A1 and DE 10 2011 089 157 A1, optical fibers are not used in the endoscopes of DE 102020 129 529 B3 and US 2023 / 0 404 370 A1, the light reflected by the tissue is guided from the distal end of the endoscope by means of a relay optics to a camera arranged at the proximal end of the endoscope, which ultimately captures an image of the tissue. The endoscope of DE 10 2011 089 157 A1 has an image sensor at the distal end of the endoscope. In such devices, imaging is performed with a greater distance between the distal end of the tubular section that can be inserted into the body and the tissue than is the case with the endomicroscopes described.Furthermore, imaging with a conventional endoscope does not occur at a resolution that allows for the examination of fine tissue structure. The systems known from DE 10 2020 129 529 B3, DE 10 2011 089 157 A1, and US 2023 / 0 404 370 A1 for enabling an oblique line of sight cannot therefore be readily used in an endomicroscope.

[0007] The use of attachment components for endoscopes is known from DE 43 01 466 C1 and DE 602 09 942 T2.

[0008] It is a first object of the present invention to provide an optical component with which an endomicroscope can be equipped or retrofitted with a view to visualizing the canal wall in narrow channels.

[0009] A second object of the present invention is to provide an endomicroscope that enables visualization of the canal wall in narrow channels.

[0010] The first object is achieved by an optical attachment component according to claim 1, the second object by an endomicroscope according to claim 12.

[0011] An optical attachment component according to the invention for an endomicroscope comprises an optical axis folded at least once, preferably exactly once, and an imaging optic comprising at least two lenses, which comprises an object-side optic end facing an object to be observed and is preferably arranged in an unfolded section of the optical axis. Furthermore, it comprises a deflection element arranged at the object-side optic end, for example a deflection prism or a deflection mirror, which has an object-side deflection element end facing away from the optic end and with which the optical axis is folded at an angle from the angular range greater than 0 degrees and a maximum of 90 degrees. A transparent closure element, for example a closure glass, with an object-side closure surface facing away from the deflection element is arranged downstream of the object-side deflection element end on the object side.The imaging optics has an object-side focal point which is located on the side of the end element facing away from the deflection element outside the attachment component at a maximum of 650 µm, preferably at a maximum of 400 µm and ideally in the range between 0 µm and 200 µm in front of the object-side end surface.

[0012] Using the imaging optics of the attachment component, a real image, also called an aerial image, can be generated at the end of the attachment component facing away from the object being observed. This image depicts a section of the object located very close to the end element. If this attachment component is then placed at the distal end of an endomicroscope, the endomicroscope can capture the ideal image of the object rather than the actual object. Using the attachment component, it is thus possible to image the wall of a narrow observation channel using an endomicroscope. Since the aerial image has a certain depth of field, it is also possible to perform a depth scan of the wall of a narrow observation channel using the endomicroscope and the attachment component.

[0013] To achieve high lateral resolution with the imaging optics, a certain size of the object-side numerical aperture NA is advantageous. In an advantageous embodiment of the invention, the imaging optics therefore have an object-side numerical aperture NA of at least 0.15, preferably of at least 0.20. On the other hand, since the depth of field decreases with increasing object-side numerical aperture, it is advantageous, at least when a depth scan is to be performed, for the imaging optics to have a numerical aperture of at most 0.3, preferably at most 0.25. If no depth scan is to be performed, higher object-side numerical apertures can also be used.

[0014] The imaging optics can be characterized by two principal planes and a system focal length, i.e., the distance between the object-side and image-side focal points from the object-side or image-side principal plane. The distance between the principal planes in the attachment component according to the invention then corresponds to a maximum of twice the system focal length. In particular, the distance can correspond to at least one times the system focal length and a maximum of twice the focal length. With imaging optics configured in this way, images with an image scale of 1, so-called 1:1 images, can be advantageously realized. The system focal length is advantageously in the range between 3.0 and 8.0 mm, in particular between 5.0 and 6.5 mm. The smaller the system focal length, the more compact the imaging optics. On the other hand, shorter system focal lengths require more strongly curved lens surfaces, which makes the correction of imaging errors more difficult.

[0015] To make the optical attachment compact while still being able to largely correct aberrations in the optical design, it is advantageous for the imaging optics to comprise at least four and a maximum of eight lenses. In particular, very good aberration correction can be achieved with six lenses.

[0016] Chromatic aberrations in imaging optics can be avoided, for example, by using cemented elements in which suitable glass materials are combined. It is therefore advantageous if two or three lenses of the imaging optics are combined into cemented elements in the optical attachment component. It is particularly advantageous if each cemented element comprises at least one lens that is identical to at least one lens of at least one other cemented element. This allows the number of lens shapes required for the optical attachment component to be kept to a minimum, which helps reduce production costs.

[0017] The diameter of the lenses of the imaging optics can be in the range between 1.0 and 5.0 mm, in particular in the range between 1.0 and 4.0 mm, preferably in the range between 1.5 and 3.5 mm. Such diameters are, on the one hand, small enough to provide an optical attachment component whose diameter does not exceed the diameter of the tubular sections of endomicroscopes, and, on the other hand, large enough to avoid excessive curvature of the lens surfaces required for imaging.

[0018] In the optical attachment component according to the invention, the imaging optics and the deflection element are preferably inserted into a sleeve, wherein the transparent end element is arranged in a peripheral wall of the sleeve. This makes it possible to create a smooth surface. In particular, the sleeve can have a diameter that corresponds to the diameter of the tubular section of an endomicroscope or only minimally exceeds this. If the sleeve has a diameter that slightly exceeds the diameter of the tubular section of the endomicroscope, the sleeve can have a section protruding beyond the imaging optics, the dimensions of which are adapted to the distal end of the tubular section of an endomicroscope such that the sleeve, with its section protruding beyond the imaging optics, can be plugged onto the distal end of the endomicroscope.In this way, an easily formed and removable connection can be created between the tubular section of the endomicroscope and the optical attachment component without any additional tools. However, in this case, the diameter of the sleeve exceeds the diameter of the tubular section of the endomicroscope by the wall thickness of the protruding end of the sleeve. If, however, the diameter of the sleeve is to correspond to the diameter of the tubular section of an endomicroscope, the optical attachment component can be glued to the tubular section of the endomicroscope in the area of ​​the sleeve.

[0019] An endomicroscope according to the invention has a resolution of 10 µm or better, in particular 5 µm or better and preferably 3 µm or better, e.g. 1 µm or better or 0.7 µm or better, and comprises a tubular section for insertion into a channel in the body. An optical attachment component according to the invention is arranged at the distal end of the tubular section. The optical attachment component can in particular be plugged onto the distal end or glued to the distal end. The endomicroscope according to the invention enables visualization of the channel wall of narrow channels, as has been explained with reference to the optical attachment component according to the invention.The optical attachment component is advantageously arranged at the distal end of the tubular section such that an image generated by the imaging optics is located at a location that is typically a maximum of 650 µm, preferably a maximum of 400 µm, and ideally in the range between 0 µm and 200 µm in front of the distal end of the tubular section. In this way, the real image generated by the imaging optics of the attachment component is located at a location where the surface of the tissue would be if the endomicroscope were used without the attachment component to visualize the floor of the canal.

[0020] To design the imaging optics, the distance F of an image-side focal point from an image-side principal plane or the distance F of an object-side focal point from an object-side principal plane is determined using the equation F = rs / sin(α) based on a given half-aperture angle α and a maximum permitted radius rs of a beam of rays passing through the imaging optics. With the determined system focal length F, the maximum permitted radius of a beam of rays passing through the imaging optics, a given distance between the principal planes, a given number of lenses and a given number of refracting surfaces, the thicknesses, the radii of curvature and the glass types of the lens system are then optimized with a view to achieving the system focal length and the distance between the principal planes.

[0021] Further features, properties and advantages of the invention will become apparent from the following description of embodiments with reference to the accompanying figures. Fig. 1 shows an endomicroscope in a schematic representation. Fig. 2 shows a first variant for an attachment component with an imaging optics for the endomicroscope made of Fig. 1. Fig. 3 shows a second variant for an attachment component with an imaging optics for the endomicroscope from Fig. 1. Fig. 4 shows a first variant for the imaging optics as it can be used in an attachment component. Fig. 5 shows the main planes and the system focal length of the imaging optics from Fig. 4. Fig. 6 shows a second variant for the imaging optics, as it can be used in an attachment component. Fig. 7 shows the main planes and the system focal length of the imaging optics from Fig. 6. Fig. Figure 8 shows a third variant for the imaging optics, as it can be used in an attachment component. Fig. 9 shows different variants for a transparent end element as it can be used in an attachment component.

[0022] An exemplary embodiment of an endomicroscope 1 according to the invention is described below with reference to Fig. 1. In the present exemplary embodiment, the endomicroscope 1 comprises a handle 3, from which a tubular section, namely a hollow shaft 5, extends. The shaft 5 has a curved proximal section 7 and a straight distal section 9 adjoining the proximal section 7. The distal section 9 terminates at a distal shaft end 10, at which a cover glass 12 or another transparent element is located, which closes the hollow shaft 5.

[0023] In the present exemplary embodiment, the curved proximal section 7 and the straight distal section 9 of the shaft 5 together have a length of 150 mm. However, the shaft 5 can also have a different length, which can be in the range between 100 mm and 180 mm, and in particular in the range between 130 mm and 170 mm. The outer diameter D of the shaft 5 is 5 mm in the present exemplary embodiment. In other embodiments of the endomicroscope 1, the outer diameter D can also have a different value, which can be in the range between 3.0 mm and 5.0 mm.

[0024] The inner diameter of the shaft 5 is large enough to guide at least one optical fiber 11 to the distal end of the shaft 5. In the present exemplary embodiment, the optical fiber 11 is part of a fiber-optic laser scanning microscope; however, in other embodiments, it can also be part of another fiber-optic imaging device, for example, a fiber-optic confocal microscope or a fiber-optic OCT device. Furthermore, various types of fiber-optic imaging devices can be combined with one another, so that the optical fiber 11 can, for example, be part of a confocal fiber-optic laser scanning microscope. High lateral resolutions can be achieved with such fiber-optic imaging devices. In particular, resolutions of 10 µm or better can be achieved, for example 5 µm or better, 3 µm or better, 1 µm or better, such as 0.7 µm.With such lateral resolutions, the structures of individual cells, such as the cell nucleus, can be identified.

[0025] In the present exemplary embodiment, a scanning device 13 is arranged inside the shaft 5, shortly before the distal shaft end 10. In the present exemplary embodiment, this device comprises piezo actuators that act on the optical fiber 11 shortly before the distal end 11A of the optical fiber in order to cause the distal end of the optical fiber 11 to oscillate. By means of this oscillation, a specific region of an observation object located in front of the cover glass 12 can be scanned with the distal end 11A of the optical fiber 11. The area that can be scanned is 500 × 500 µm in the present exemplary embodiment, but it can also be larger or smaller than 500 × 500 µm. Typical areas that can be scanned are in the range between 300 × 300 µm and 750 × 750 µm.At each scanning location, an image point is acquired using the oscillating optical fiber, and the acquired image points are then combined to form a two-dimensional or three-dimensional image. The latter occurs when an axial scan is performed in addition to the lateral scan using the oscillating fiber, as is possible with a confocal microscope or an OCT.

[0026] With the endomicroscope 1, as shown in Fig. 1, it is only possible to scan an object section that is located in front of the shaft end 10 in the axial direction of the shaft. If the shaft 5 is inserted into a narrow surgical channel that prevents tilting of the shaft 5 in the surgical channel, it is therefore not possible to examine the wall of the surgical channel with the fiber optic imaging device. In order to enable an examination of the channel wall in such narrow surgical channels, an attachment component with an imaging optic and with a deflection element that ensures beam deflection can be attached to the distal shaft end 10. Exemplary embodiments of such an attachment component are described below with reference to Fig. 2 and Fig. 3. Exemplary embodiments of imaging optics of the attachment component are described with reference to Fig. 4 to 7.

[0027] A first exemplary embodiment of the attachment component 15 is shown in Fig. 2. The attachment component 15 comprises a sleeve 16 formed by a peripheral wall 17, in which an imaging optic 19 and a deflection element 21 are accommodated. The peripheral wall of the attachment optic can typically have a thickness in the range of 0.05 mm to 1.5 mm, in particular from 0.1 mm to 1 mm. In the exemplary embodiment shown, the optical axis OA is folded by 90° using the deflection element 21, wherein the optical axis OA* shown as a dashed line indicates the original, unfolded direction. In other words, the imaging beam path is deflected by 90° by the deflection element 21, wherein the deflection angle between the optical axis OA and the original, undeflected optical axis OA* is measured. However, the deflection element 21 does not necessarily have to deflect the beam path by 90°, but it can also be designed in such a way that it deflects the beam path by a deflection angle other than 90°.Any angle greater than 0°, in particular greater than 20°, and furthermore, in particular greater than 45°, and less than 90° is considered. In the exemplary embodiment shown, a deflection prism 21 serves as the deflection element, the exit surface 21A of which forms the object-side end of the deflection element, i.e., the object-side deflection element end. However, instead of a deflection prism 21, a deflection mirror can also be used as the deflection element.

[0028] The peripheral wall 17 forming the sleeve 16 has a transparent closure element 25 at the point toward which the deflection element 21 deflects the imaging beam path. The outer surface 25A of the closure element forms a closure surface of the closure element 25 that is flush with the outer surface of the peripheral wall. In the present exemplary embodiment, the closure element 25 is a closure glass. However, any other element transparent to the wavelengths used can also be used as the closure element 25, for example, a transparent plastic.

[0029] The end 26 of the attachment component 15 at which the deflection element 21 is located is closed by an end wall 27, which represents the object-side end of the attachment component 15. The opposite end 29 of the attachment component 15, however, is open in the present exemplary embodiment. At the open end 29, on the end face of the peripheral wall 17 of the attachment component 15, an adhesive layer 31 is present, with the aid of which the attachment component 15 can be glued to the distal shaft end 10 of the endomicroscope 1. In this way, a connection can be established in which the peripheral wall 17 of the attachment component 15 adjoins the peripheral wall of the distal shaft end 10 flush with the peripheral wall of the distal shaft end 10.

[0030] The end 29, with which the attachment component 15 is glued to the distal shaft end 10 of the endomicroscope 1, can, in alternative embodiments of the attachment component 15, be closed with a closure element such as a cover glass or another transparent element. If the sleeve end 29 is closed with a cover glass or the like, this cover glass can be glued to the cover glass 12 of the distal shaft end 10 of the endomicroscope 1 using a suitable optical kit, thus creating a large-area adhesive bond. The dimensions and properties of the adhesive bond are advantageously already taken into account in the design, and in particular in the optical design, of the attachment component 15.Alternatively or additionally, during the bonding of the attachment component to the endomicroscope, light can be emitted from the endomicroscope and projected through the attachment component onto a screen or detector to allow or ensure correct or advantageous alignment of the components. In addition, the data from the projection of the light emitted by the endomicroscope can also be used to calibrate the endomicroscope or the system comprising the endomicroscope and attachment component.

[0031] A second exemplary embodiment of the attachment component 15 is shown in Fig. 3. The second exemplary embodiment of the attachment component 15 according to the invention differs from that shown in Fig. 2 only in the design of the deflection element 21 and in the design of its end 29 facing the shaft end 10 of the endomicroscope 1. Elements of the second exemplary embodiment which do not differ from elements of the Fig. 2 shown first exemplary embodiment, are shown in Fig. 3 with the same reference numerals as in Fig. 2 and will not be explained again to avoid repetition.

[0032] In the second exemplary embodiment, a deflecting mirror 21' is used as the deflecting element 21' instead of a deflecting prism 21. In contrast to a deflecting prism, a deflecting mirror 21' has no glass path to be traversed and therefore no exit surface. Therefore, within the scope of the present disclosure, an imaginary plane 22 is regarded as the object-side deflecting element end, which extends from the edge portion 22 of the deflecting mirror 21' closest to the peripheral wall 17, perpendicular to the optical axis OA of the beam reflected by the deflecting mirror 21'. However, in the second exemplary embodiment, as in the first exemplary embodiment, a deflecting prism 21 can also be used instead of the deflecting mirror 21'.

[0033] The end 29 of the attachment component 15 facing the shaft end 10 of the endomicroscope 1 is open in the present exemplary embodiment and has a section 23 protruding beyond the imaging optics 19, in which the inner diameter of the peripheral wall 17 essentially corresponds to the outer diameter of the distal shaft end 10 of the endomicroscope 1. This allows the shaft end 10 of the endomicroscope 1 to be inserted into the protruding section 23, so that a connection, in particular a plug-in connection, can be established between the shaft end 10 of the endomicroscope 1 and the attachment component 15. A plug-in connection is advantageous because neither mechanical nor chemical aids are required to establish the connection, and the connection can also be easily released again.

[0034] In the Fig. 3, the peripheral wall 17 has, in its section 23 projecting beyond the imaging optics 19, an outer diameter that is larger than the rest of the peripheral wall in order to create a receptacle for the distal end 10 of the endomicroscope 1. This creates a shoulder between the section 23 and the rest of the attachment component 15, as shown in Fig. 3. If such a step is to be avoided, the outer diameter can also be larger outside the section 23 projecting beyond the imaging optics 19 than the outer diameter of the distal end 10 of the endomicroscope 1. Fig. However, in the paragraph shown in Figure 3, the enlargement of the outer diameter can be limited to a minimum necessary section of the attachment component 15.

[0035] Alternatively or additionally, the Fig. 3, the shaft end 29 with the enlarged outer diameter extends at least partially further in the direction of the curved proximal section 7, in particular up to the end of the straight distal section 9, of the shaft 5 of the endomicroscope 1 (cf. Fig. 1). This makes it possible to ensure that the attachment component 15 is not completely located in a channel or cavity, even when the attachment component 15 is inserted with its object-side end into a channel or cavity, but at least partially protrudes from this channel or cavity. If the endomicroscope 1 and the attachment component 15 are not permanently connected, the attachment component 15 can be moved relative to the endomicroscope 1. For example, if the attachment component and the endomicroscope 1 are connected to one another in such a way that rotation of the attachment component 15 relative to the endomicroscope 1 is still possible, the orientation of the deflection element 21, 21' or the transparent end element 25 and thus the direction of observation relative to the endomicroscope 1 can be changed without having to rotate the endomicroscope 1 itself.For this purpose, it may be sufficient for a person to grasp and rotate a shaft end that is extended in this way and protrudes from the channel or cavity. Alternatively, a movement perpendicular to the direction of rotation or the unlocking of a locking mechanism may first be required to enable rotation of the attachment component 15 relative to the endomicroscope 1. In addition, the current direction of observation, i.e. the orientation of the deflection element 21, 21' or the transparent end element 25 relative to the endomicroscope 1, can be visualized or determined by a marking, in particular on the extended shaft end. Alternatively or additionally, there are markings on the attachment component 15 and / or the endomicroscope 1, by means of which the penetration depth of the attachment component 15 or the endomicroscope 1 can be visualized or determined.Alternatively or additionally, a marking is also present at the entrance to the channel or cavity, which also allows the current observation direction relative to the object being observed to be visualized or determined. Alternatively or additionally, the observation direction and / or the penetration depth of the attachment component 15 or the endoscope 1 relative to the object, and thus the location currently being observed with the endomicroscope 1, can also be visualized or determined by a tracking method or by an image analysis of an image of the surgical site that at least partially includes the endomicroscope 1.

[0036] Alternatively or additionally, the outer diameter of the attachment component 15, at least at the object-side end, can also be smaller than the outer diameter of the shaft 9 of the endomicroscope 1. This makes it possible to examine very narrow channels into which the actual endomicroscope 1 cannot be inserted.

[0037] Alternatively or additionally, the outer diameter of the attachment component 15 can be enlarged at least partially in the region of the imaging optics, for example, to the same extent as section 23. As a result, the imaging optics 19 can also have an enlarged diameter with a corresponding thickness of the peripheral wall 17.

[0038] Alternatively or additionally, the peripheral wall 17 of the auxiliary optics 15 can also have a reduced thickness, which also allows an increased diameter for the imaging optics 19 to be achieved. The peripheral wall 17 of the auxiliary optics can typically have a thickness in the range of 0.05 mm to 1.5 mm, in particular a thickness in the range of 0.1 mm to 1 mm.

[0039] A first exemplary embodiment of an imaging optics 19, as can be used in the attachment component 15, is described below with reference to the Fig. 4 and Fig. 5 described. Fig. 4 shows the lenses of the imaging optics 19 as well as the deflection element 21 and the transparent end element 25. The deflection element 21 is in Fig. 4 schematically shown as a cuboid, but in reality typically designed as a deflection prism, whose glass path corresponds to the path through the cuboid. Fig. 5 shows the principal planes and the system focal length of the lens system from Fig. 4. In the exemplary embodiment, the imaging optics are located entirely in an unfolded section of the optical axis OA, as in Fig. 2 or Fig. 3 shown.

[0040] The imaging optics 19 of the first exemplary embodiment comprises three rod lenses 33, 35, 37, also called cylindrical lenses, which are each composed as a cemented element of a concave-convex cylindrical lens 33A, 35A, 37A and a biconvex lens 33B, 35B, 37B. The end of the cemented member 37 facing the deflection element 21 represents the object-side optical end 38 of the imaging optics 19. The cemented members 33 and 37 are constructed identically, ie their concave-convex cylindrical lenses 33A, 37A and their biconvex lenses 33B, 37B are identical, but the two outer cemented members 33, 37 are arranged in opposite orientations, ie their biconvex lenses 33B, 37B form the mutually facing ends of the two rod lenses 33, 37.The biconvex lens 35B of the central cemented element 35 is also identical to the biconvex lenses 33B, 37B of the two outer cemented elements 33, 37 and is oriented like the biconvex lens 33B of the cemented element 33 furthest from the deflection element 21. The concave-convex rod lens 35A of the middle cemented element 35, however, differs from the concave-convex rod lenses 33A, 37A of the two outer cemented elements 33, 37.

[0041] In the present exemplary embodiment, the biconvex lenses 33B, 35B, 37B each have a thickness of 1.90 mm and a convex lens surface with a radius of curvature of 4.94 mm and a convex lens surface with a curvature of 3.21 mm. The concave-convex rod lenses 33A, 37A of the two outermost cemented elements 33, 37 are identical and each have a thickness of 4.60 mm and a convex lens surface with a radius of curvature of 4.94 mm and a concave lens surface with a radius of curvature of 3.21 mm. The concave-convex curved rod lens 35A of the middle cemented element 35A differs from the concave-convex rod lenses 33A, 37A of the two outermost cemented elements 33, 37. It has a thickness of 6.45 mm and a convex curved lens surface with a radius of curvature of 6.98 mm and a concave curved lens surface with a radius of curvature of 4.94 mm.

[0042] The distance between the cemented elements is 0.20 mm each, and the radius of all lenses is 1.50 mm each. The distance between the cemented element 37 closest to the deflecting element 21 and the deflecting element 21 is 0.50 mm, and the glass path through the deflecting element 21 is 1.50 mm. The distance between the exit surface 21A of the deflecting element 21 and the closure element is 0.20 mm. The thickness of the closure element 25 is 0.50 mm. In the present exemplary embodiment, the image-side focal point of the imaging optics 19 lies 0.10 mm in front of the outer surface 25A forming the object-side end of the closure element 25. The object-side focal plane is shown here as at least slightly curved, since the imaging optics images the curved object-side focal plane onto the non-curved image-side focal plane.Acquisition of straight object-side planes can be achieved using axial scans or depth scans, such as those possible with a confocal microscope or an OCT. Alternatively, the imaging optics can be designed to image a non-curved object-side focal plane onto the non-curved image-side focal plane.

[0043] The biconvex lenses 33B, 35B, and 37B are each made of N-BAK4 glass (Schott), while the concave-convex rod lenses 33A, 35A, and 37A are made of N-SF1 glass (Schott). The deflection element 21, designed as a deflection prism, and the closure element 25, designed as a cover glass, are each made of N-BK7 glass (Schott).

[0044] The imaging properties of the Fig. 4 shown exemplary embodiment for the imaging optics 19 can be specified by two main planes H, H' as well as the system focal length F, which represents the distance of the image-side focal point FP from the image-side main plane H or the distance of the object-side focal point FP' from the object-side main plane H' (see Fig. 5). In the present exemplary embodiment, the system focal length is 5.00 mm, and the distance between the two principal planes H, H' is twice the system focal length, i.e., 10.00 mm. The system is a so-called 4F system, which results in a 1:1 image, i.e., an image with a magnification of 1. The image field size is approximately 500 × 500 µm.

[0045] A second exemplary embodiment of an imaging optics 19, as can be used in the attachment component 15, is described below with reference to the Fig. 6 and Fig. 7 described. Fig. 6 shows the lenses of the imaging optics 19 as well as the deflection element 21 and the transparent end element 25. The deflection element 21 is in Fig. 6 as in Fig. 4 is schematically shown as a cuboid, but in reality it is designed as a deflection prism whose glass path corresponds to the path through the cuboid. Fig. 7 shows the principal planes H, H' and the system focal length F of the lens system from Fig. 6. The deflecting element 21 and the cover glass 25 do not differ from the deflecting element 21 and the cover glass 25 of the first exemplary embodiment for the imaging optics 19. As in the first exemplary embodiment, the imaging optics is located entirely in an unfolded section of the optical axis OA.

[0046] In the second exemplary embodiment, the imaging optics 19 also comprises three rod lenses 43, 45, 47, also called cylindrical lenses, each designed as a cemented element. The end of the cemented element 47 facing the deflecting element 21 represents the object-side optical end 48 of the imaging optics 19. The two cemented elements 45, 47 closest to the deflecting element 21 are each composed of a concave-convex cylindrical lens 45A, 47A and a biconvex lens 45B, 47B and are oriented such that their biconvex lenses 45B, 47B form the mutually facing ends of the two cemented elements 45, 47. The cemented element 43 furthest from the deflecting element 21, on the other hand, is constructed from a biconvex cylindrical lens 43A and a concave-convex lens 43B. Furthermore, the diameter of the cemented element 43 furthest from the deflecting element 21 is smaller than the diameters of the other two cemented elements 45, 47, which both have the same diameter.In contrast to the first exemplary embodiment for the imaging optics 19, in the second exemplary embodiment for the imaging optics 19 all lenses are different.

[0047] The biconvex cylindrical lens 43A of the first cemented member 43 has a thickness of 2.80 mm. The radii of curvature of the cylindrical lens 43A are 7.27 mm and 1.10 mm, respectively. The concave-convex lens 43B of the first cemented member 43 has a thickness of 1.00 mm and curvature rates of 1.10 mm and 2.52 mm, respectively. The concave-convex cylindrical lens 45A of the second cemented member 45 has a thickness of 3.50 mm and radii of curvature of 8.55 mm and 3.00 mm. The biconvex lens 45B of this cemented member 45 has a thickness of 1.10 mm and radii of curvature of 3.00 mm and 2.73 mm. The biconvex lens 47B of the third cemented element 47 has a thickness of 1.30 mm and radii of curvature of 3.00 mm and 2.24 mm. The concave-convex cylindrical lens 47A of the third cemented element 47 has a thickness of 3.50 mm and radii of curvature of 2.24 mm and 3.66 mm. The distance between the cemented elements 43 and 45 and the distance between the cemented elements 45 and 47 are each 0.10 mm.The distance between the cemented element 47 and the deflecting element 21 is also 0.10 mm. The distance between the exit surface 21A of the deflecting element 21 and the cover glass 25 is 0.20 mm. As in the first exemplary embodiment for the imaging optics 19, the image-side focal point of the imaging optics 19 lies 0.10 mm in front of the outer surface 25A forming the object-side end of the cover element 25.

[0048] The biconvex lenses 43A, 45B, and 47B are each made of N-BAK4 glass (Schott), while the concave-convex rod lenses 43B, 45A, and 47A are made of N-SF1 glass (Schott). The deflection element 21, designed as a deflection prism, and the closure element 25, designed as a cover glass, are each made of N-BK7 glass (Schott).

[0049] The imaging properties of the Fig. 6 shown exemplary embodiment for the imaging optics 19 can be specified by two main planes H, H' and a system focal length F, which represents the distance of the image-side focal point FP from the image-side main plane H or the distance of the object-side focal point FP' from the object-side main plane H' (see Fig. 7). In the present exemplary embodiment, the system focal length F is 5.00 mm, as in the previous exemplary embodiment. However, the distance between the two main planes H, H' is 6.00 mm, which is smaller than in the previous exemplary embodiment. Although the imaging optics 19 of the present exemplary embodiment also produces a 1:1 image with an image field of approximately 500 × 500 µm, it is not a 4F system.

[0050] A third exemplary embodiment of an imaging optics 19, as can be used in the attachment component 15, is described below with reference to the Fig. 8 described. Fig. 8 shows the lenses of the imaging optics 19 as well as the deflection element 21 and the transparent end element 25. The deflection element 21 is in Fig. 8 is schematically depicted as a triangle or half-cube prism. The deflecting element 21 and the cover glass 25 do not differ from the deflecting element 21 and the cover glass 25 of the first exemplary embodiment for the imaging optics 19. As in the first and second exemplary embodiments, the imaging optics are located entirely within an unfolded section of the optical axis OA.

[0051] In the third exemplary embodiment, the imaging optics 19 also comprises three rod lenses 53, 55, 57, also called cylindrical lenses, each of which is designed as a cemented element. The end of the cemented element 57 facing the deflecting element 21 represents the object-side optical end 58 of the imaging optics 19. The two cemented elements 55, 57 closest to the deflecting element 21 are each composed of a concave-convex cylindrical lens 55A, 57A and a biconvex lens 55B, 57B and are oriented such that their biconvex lenses 55B, 57B form the mutually facing ends of the two cemented elements 55, 57. The cemented element 53 furthest from the deflecting element 21, on the other hand, is constructed from a biconvex cylindrical lens 53A and a concave-convex lens 53B. Furthermore, the diameter of the cemented element 53 furthest from the deflecting element 21 is smaller than the diameters of the other two cemented elements 55, 57, which both have the same diameter.In contrast to the first exemplary embodiment for the imaging optics 19, all lenses in the third exemplary embodiment for the imaging optics 19 are also different.

[0052] The biconvex cylindrical lens 53A of the first cemented member 53 has a thickness of 1.80 mm. The radii of curvature of the cylindrical lens 53A are 6.4 mm and 1.10 mm, respectively. The concave-convex lens 53B of the first cemented member 53 has a thickness of 1.00 mm and curvature rates of 1.10 mm and 2.33 mm, respectively. The concave-convex cylindrical lens 55A of the second cemented member 55 has a thickness of 5.00 mm and radii of curvature of 6.40 mm and 2.00 mm. The biconvex lens 55B of this cemented member 55 has a thickness of 1.40 mm and radii of curvature of 2.00 mm and 2.81 mm. The biconvex lens 57B of the third cemented element 57 has a thickness of 1.40 mm and radii of curvature of 3.00 mm and 1.92 mm. The concave-convex cylindrical lens 57A of the third cemented element 57 has a thickness of 1.60 mm and radii of curvature of 1.92 mm and 3.23 mm. The deflection element 21, designed as a half-cube prism, has an edge length of 2 mm, and the end element has a thickness of 0.5 mm.The distance between the cemented elements 53 and 55, as well as the distance between the cemented elements 55 and 57, is 0.10 mm each. The distance between the cemented element 57 and the deflection element 21 is also 0.10 mm. The distance between the exit surface 21A of the deflection element 21 and the cover glass 25 is 0.70 mm. As in the first exemplary embodiment for the imaging optics 19, the image-side focal point of the imaging optics 19 lies 0.10 mm in front of the outer surface 25A forming the object-side end of the cover element 25.

[0053] The biconvex lenses 53A, 55B, and 57B are each made of N-BAK4 glass (Schott), while the concave-convex rod lenses 53B, 55A, and 57A are made of N-SF1 glass (Schott). The deflection element 21, designed as a deflection prism, and the closure element 25, designed as a cover glass, are each made of N-BK7 glass (Schott).

[0054] Exemplary embodiments of how the transparent closure element 25 can be designed with respect to the peripheral wall 17 are shown in the Fig. 9A to 9H are shown schematically.

[0055] In the Fig. Figures 9A to 9H show the front component schematically in cross-section, omitting all elements except the peripheral wall 17 and the end element 25. This sketchy representation also implies that the dimensions of the peripheral wall 17 and the end element 25, as well as their relationships to one another, are not limited to the dimensions shown.

[0056] In particular, the extension of the terminating element 25 perpendicular to the optical axis can be adjusted to the numerical aperture used, the size of the area to be scanned, and the distance of the area to be scanned from the outer boundary 25A' of the terminating element 25. Alternatively and additionally, the curvatures of the inner boundary 25B' and / or outer boundary 25A' can be adapted to the desired imaging properties or taken into account when designing the imaging optics. For the sake of clarity, only the Fig. 9A, the outer boundary 25A' and the inner boundary 25B' of the closure element 25 are provided with reference numerals for the Fig. However, the designation applies accordingly to 9B to 9H.

[0057] In Fig. 9A to 9C, the attachment component with the peripheral wall 17 is shown in cross section, wherein the closure element 25 is adapted to the shape of the peripheral wall 17 in such a way that at least partially the outer boundary 25A' has the same curvature as the peripheral wall 17. In the Fig. In the embodiment shown in Figure 9A, the end element 25 also has the same thickness as the peripheral wall 17 and additionally also the same curvature at the inner boundary 25B'. This achieves a flush finish and a uniform shape. The variants in the Fig. 9B and Fig. 9C show different embodiments in which the end element 25 has different thicknesses. While in Fig. 9B the end element 25 also has a curvature at the inner boundary which differs from the curvature of the peripheral wall 17, is shown in Fig. 9C the inner boundary is shown straight, ie without curvature.

[0058] Alternatively, the outer boundary 25A' of the end element 25 can also protrude at least partially from the outer boundary of the peripheral wall 17, as for example in Fig. 9D, or be offset inwards.

[0059] Further variants are in the Fig. 9E to 9G, where the outer and inner boundaries 25A', 25B' have no curvature, so that the optical image is only minimally affected. While in the Fig. 9E the end element has a rectangular shape in cross-section, the end element has in the Fig. 9F and Fig. 9G has a trapezoidal shape in cross-section. Due to the trapezoidal shape, the required amount of transparent material can be reduced according to the propagation of the optical rays. While in Fig. 9F the end element protrudes slightly from the facing component in relation to the actual curvature of the peripheral wall, it is in Fig. 9G slightly inward. This ensures that the closure element causes only minimal resistance, even in narrow channels, especially when the attachment component moves, and does not come into contact with the tissue in such a way that it could cause injury or damage to the tissue. Fig. 9H shows a further variant in which the inner boundary 25B' is straight and the outer boundary 25A' is curved.

[0060] The shape of the closure element can generally be designed as a cuboid, so that both the inner and outer boundaries are rectangular; as a circular cylinder, so that both the inner and outer boundaries are circular; as an elliptical cylinder, so that both the inner and outer boundaries are elliptical; or as a mixture of the aforementioned shapes. The shape of the closure element can also be designed according to any lens shape.

[0061] To design imaging optics 19 for the attachment component 15, the distance of the image-side focal point FP and the object-side focal point FP' from the respective principal plane H, H', i.e., the system focal length F, can be determined from the desired numerical aperture and the maximum permissible radius of the beam, which in turn results from the maximum lens radius or half the maximum lens diameter. In the present exemplary embodiment, the maximum lens diameter is 3.0 mm. Of this, at most the innermost 80 to 90% should be used for the beam path, which in the present exemplary embodiments results in a maximum radius of the beam of rs = 1.30 mm. With a numerical aperture of NA = 0.25, the half aperture angle α of the beam emanating from a focal point is approximately 14.5°, which, according to the equation F = rs / sin(α), leads to a system focal length of approximately 5.00 mm.With the system focal length, the distance between the main planes and the maximum lens diameter as boundary conditions, the thicknesses, the radii of curvature and the types of glass of the lens system of the imaging optics 19 can be optimized for a given number of lenses and a given number of refracting surfaces in such a way that the system with reference to . Fig. 4 or that with reference to Fig. 6 is created. The number of refractive surfaces is not predetermined by the number of lenses when individual lenses are combined to form cemented elements. For example, a cemented element made up of two lenses has three refractive surfaces, whereas the individual lenses would have four refractive surfaces together.

[0062] Lens systems with imaging properties such as the lens systems of the with reference to the Fig. 4 to 8 shown exemplary embodiments, can also be used with other lens systems than those shown in the Fig. 4, Fig. 6 and Fig.8 can be realized. For example, no cemented elements need to be used, but only individual lenses or a combination of cemented elements and individual lenses can be used. Furthermore, the lens configuration does not need to consist of three cemented elements with a total of six lenses. Instead, fewer or more cemented elements can be present, whereby the cemented elements do not necessarily all have to consist of two lenses. In principle, it is possible, for example, for one or more of the cemented elements to consist of three lenses or even more lenses. Overall, it is advantageous if the lens system of the imaging optics 19 has between four and eight lenses, whereby the lens system can be constructed from individual lenses, from cemented elements, or from a combination of individual lenses and cemented elements.In principle, a larger number of lenses allows for the use of lenses with smaller radii of curvature and / or allows for better correction of aberrations. However, with the number of lenses used, the complexity and manufacturing effort of the attachment component also increases, so a number of lenses between four and eight represents a good compromise between image quality on the one hand and the complexity and manufacturing effort of the lens system on the other.

[0063] The present invention has been described in detail using exemplary embodiments for illustrative purposes. However, as already explained in the context of the exemplary embodiments, deviations from the exemplary embodiments are also possible. Therefore, the invention is not intended to be limited by the exemplary embodiments, but only by the appended claims. List of reference symbols 1 endomicroscope 3 Handle 5 shaft 7 proximal section 9 distal section 10 distal shaft end 11 optical fiber 11A distal end 12 end glass 13 Scanning device 15 Attachment component 16 sleeve 17 Perimeter wall 19 imaging optics 21 Deflection element 21A Exit surface 23 preceding section 25 transparent end element 25A outer surface 25A' outer boundary 25B' inner boundary 27 Front wall 29 End 31 Adhesive layer 33 cemented joints 35 cemented joints 37 cemented joints 33A concave-convex cylindrical lens 35A concave-convex cylindrical lens 37A concave-convex cylindrical lens 33B biconvex lens 35B biconvex lens 37B biconvex lens 38 object-side optics end 43 cemented joints 45 cemented joints 47 cemented joints 45A concave-convex cylindrical lens 47A concave-convex cylindrical lens 43A biconvex cylindrical lens 45B biconvex lens 47B biconvex lens 43B concave-convex lens 48 object-side optics end 53 cemented joints 55 cemented joints 57 cemented joints 55A concave-convex cylindrical lens 57A concave-convex cylindrical lens 53A biconvex cylindrical lens 55B biconvex lens 57B biconvex lens 53B concave-convex lens 58 object-side optics end F system focal length FP, FP' focus point H, H' main level OA, OA* optical axis rs radius of the beam α half opening angle

Claims

[1] Optical attachment component (15) for an endomicroscope (1) with - an optical axis (OA) folded at least once; - an imaging optic (19) comprising at least two lenses (33A, 33B, 35A, 35B, 37A, 37B, 43A, 43B, 45A, 45B, 47A, 47B, 53A, 53B, 55A, 55B, 57A, 57B), which comprises an object-side optic end (38, 48, 58) to be directed towards an object to be observed, - a deflection element (21, 21') arranged at the object-side optical end (38, 48, 58), which has an object-side deflection element end (21A, 22) facing away from the object-side optical end (38, 48, 58) and with which the optical axis (OA) is folded at an angle from the angular range greater than 0 degrees and a maximum of 90 degrees, characterized by , that - a transparent end element (25) with an object-side end surface (25A) facing away from the deflection element (21, 21') is arranged downstream of the object-side deflection element end (21A, 22) and - the imaging optics (19) has an object-side focal point which is located on the side of the transparent end element (25) facing away from the deflection element (21, 21') outside the attachment component (15) at a maximum of 650 µm in front of the object-side end surface (25A). [2] Optical attachment component (15) according to claim 1, characterized by that the imaging optics (19) has an object-side numerical aperture of at least 0.

15. [3] Optical attachment component (15) according to claim 1 or claim 2, characterized by that the imaging optics (19) has an object-side numerical aperture of at most 0.

3. [4] Optical attachment component (15) according to one of claims 1 to 3, characterized by that the imaging optics (19) are characterized by two main planes (H, H') and a system focal length (F), wherein the distance between the main planes (H, H') corresponds at most to twice the system focal length (F). [5] Optical attachment component (15) according to claim 4, characterized by that the system focal length (F) is in the range between 3.0 and 8.0 mm. [6] Optical attachment component (15) according to one of claims 1 to 5, characterized by that the imaging optics (19) comprises at least four and a maximum of eight lenses (33A, 33B, 35A, 35B, 37A, 37B, 43A, 43B, 45A, 45B, 47A, 47B, 53A, 53B, 55A, 55B, 57A, 57B). [7] Optical attachment component (15) according to one of claims 1 to 6, characterized by that two or three lenses (33A, 33B, 35A, 35B, 37A, 37B, 43A, 43B, 45A, 45B, 47A, 47B, 53A, 53B, 55A, 55B, 57A, 57B) of the imaging optics (19) are combined to form cemented elements (33, 35, 37, 43, 45, 47, 53, 55, 57). [8] Optical attachment component (15) according to claim 7, characterized bythat each cemented member (33, 35, 37) comprises at least one lens (33A, 33B, 35B, 37A, 37B) which is identical to at least one lens (33A, 33B, 35B, 37A, 37B) of at least one other cemented member (33, 35, 37). [9] Optical attachment component (15) according to one of claims 1 to 8, characterized by that the diameter of the lenses (33A, 33B, 35A, 35B, 37A, 37B, 43A, 43B, 45A, 45B, 47A, 47B, 53A, 53B, 55A, 55B, 57A, 57B) of the imaging optics (19) is in the range between 1.0 and 5.0 mm. [10] Optical attachment component (15) according to one of claims 1 to 9, characterized by a sleeve (16) into which the imaging optics (19) and the deflection element (21, 21') are inserted, wherein the transparent closure element (25) is arranged in a peripheral wall (17) of the sleeve (16). [11] Optical attachment component (15) according to claim 10, characterized bythat the sleeve (16) has a section (23) projecting beyond the imaging optics (19) and whose dimensions are adapted to the distal end (10) of an endomicroscope (1) in such a way that the sleeve (16) can be plugged onto the distal end (10) of the endomicroscope (1) with its section (23) projecting beyond the imaging optics (19). [12] Endomicroscope (1) with a resolution of 10 µm or better, comprising a tubular portion (5) for insertion into a channel in the body, characterized by a distal end (10) of the tubular portion (5) on which an optical attachment component (15) according to one of claims 1 to 11 is arranged. [13] Endomicroscope (1) according to claim 12, characterized bythat the optical attachment component (15) is arranged at the distal end (10) of the tubular section (5) in such a way that an image generated by the imaging optics (19) is located at a location which is at most 650 µm in front of the distal end (10) of the tubular section (5).

Images