MEDICAL ENDOSCOPIC INSTRUMENT

Abstract

A medical endoscopic instrument includes a distal elongated insertion section (1) for minimally invasive insertion into a human or animal body, with at least one LED (5) arranged in a distal end section of the insertion section (1), and a lens system (19) arranged distally of the LED (5) with an optical axis (x). The lens system (19) includes a first lens (29) and a second lens (31) arranged distally of the first lens (29). The second lens (31) has a proximally extending sleeve extension (35). The sleeve extension (35) has a first reference surface for positioning the second lens (31) in relation to the insertion section (1) and a second reference surface (39) for positioning the first lens (29) in relation to the second lens (31).

Claims

1. A medical endoscopic instrument comprising: a distal elongated insertion section for minimally invasive insertion into a human or animal body; a LED arranged in a distal end section of the insertion section; and a lens system arranged distally of the LED, the lens system having an optical axis, wherein the lens system comprises a first lens and a second lens arranged distally of the first lens, and wherein the second lens includes a proximally extending sleeve extension, wherein the sleeve extension includes a first reference surface for positioning the second lens in relation to the insertion section and a second reference surface for positioning the first lens in relation to the second lens.

2. A medical endoscopic instrument according to claim 1, wherein the sleeve extension is configured in a one-piece with the second lens as an integral part of the second lens.

3. A medical endoscopic instrument according to claim 1, wherein the sleeve extension extends longer, by a factor of 2 or more in an axial direction, than an axial thickness of the second lens on the optical axis.

4. A medical endoscopic instrument according to claim 1, wherein the sleeve extension of the second lens at least partially surrounds the first lens.

5. A medical endoscopic instrument according to claim 1, wherein the first lens forms a distally acting abutment which is axially supported against the second reference surface of the sleeve extension of the second lens.

6. A medical endoscopic instrument according to claim 1, wherein the first lens also comprises a proximally extending sleeve extension.

7. A medical endoscopic instrument according to claim 6, wherein the LED is circumferentially surrounded by the sleeve extension of the first lens.

8. A medical endoscopic instrument according to claim 1, wherein the sleeve extension, is produced by removing a core of a blank by means of an ablative process.

9. A medical endoscopic instrument according to claim 1 wherein the sleeve extension is produced by means of an additive process.

10. A medical endoscopic instrument according to claim 1 claims wherein the sleeve extension is produced by a combined additive and ablative process.

11. A medical endoscopic instrument according to claim 1, wherein the first lens is a converging lens and the second lens is a diverging lens.

12. A medical endoscopic instrument according to claim 1, wherein the lens system further comprises a light filter is arranged between the first lens and the second lens.

13. A medical endoscopic instrument according to claim 12, wherein the light filter is circumferentially surrounded by the sleeve extension of the second lens.

14. A medical endoscopic instrument according to claim 12, wherein the light filter is a shortpass filter.

15. A medical endoscopic instrument according to claim 1, wherein the first lens is a plano-convex lens and/or the second lens is a plano-concave lens.

16. A medical endoscopic instrument according to claim 1, wherein the first lens and/or the second lens is/are planar towards the LED.

17. A medical endoscopic instrument according to claim 1, wherein the first lens and/or the second lens is/are a Fresnel lens.

18. A method of producing a lens system, which is suitable for use in a distal end of a medical endoscopic instrument and comprises at least one lens, wherein a sleeve extension of the lens is created by removing a core of a blank by means of an ablative process.

19. A method of producing a lens system, which is suitable for use in a distal end of a medical endoscopic instrument, with at least one lens and a sleeve extension, wherein in a first additive step, quartz glass particles are mixed with a certain quantity of liquid plastic and, by way of stereolithography, are hardened by means of light at desired points, and the core of the blank in the form of material that had remained liquid, is then washed out in a solvent bath in a second ablative step so only a desired, hardened structure is left as a lens with a sleeve extension.

20. A method according to claim 19, wherein plastic still mixed into the desired, hardened structure is removed by heating.

21. A method according to claim 19, wherein through a final sintering process, the desired, hardened structure is heated to such an extent that the glass particles melt and fuse together.

22. A method according to claim 19, wherein, through removal of the core of a blank, the at least one lens can acquire a pot-shaped form which has an optically effective pot base and a mechanically effective circumferential pot wall.

23. A method according to claim 22, wherein an inner surface of the pot base can be ablated in a planar manner.

24. A method according to claim 22, wherein an outer surface of the pot base can be ablated in an arched manner.

25. A method according to claim 23, wherein a light filter is attached to the inner surface of the pot base.

26. A method according to claim 19, wherein a sleeve extension of a further lens of the lens system is produced by removing a core of a blank by means of an ablative process.

27. A method according to claim 26, wherein the lenses are arranged coaxially with regard to each other and at least partially in axial direction fastened to each other in an interlocking manner as a pre-assembled lens system, and the pre-assembled lens system is fitted into a distal end of a medical endoscopic instrument.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In the drawings:

[0046] FIG. 1 is a schematic longitudinal sectional view through a distal section of an insertion section according to an example of embodiment of the medical endoscopic instrument disclosed herein;

[0047] FIG. 2a is a schematic longitudinal sectional view to illustrate the principal radiation characteristics of an LED onto a light filter;

[0048] FIG. 2b is a graph showing a transmission spectrum of a light filter as a function of the angle of incidence onto the light filter;

[0049] FIG. 2c is a longitudinal sectional view to illustrate the change in the beam compared to FIG. 2a when a converging lens is positioned between the LED and light filter;

[0050] FIG. 3a, FIG. 3b, and FIG. 3c are schematic longitudinal sectional views of an optical arrangement of LED and light filter with a lens system in accordance with various examples of embodiments of the medical endoscopic instrument disclosed herein; and

[0051] FIG. 3d, FIG. 3e and FIG. 3f are schematic longitudinal sectional views through a distal section of an insertion section according to examples of embodiments of the medical endoscopic instrument disclosed herein.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0052] Referring to the drawings, FIG. 1 shows a distal end section of an insertion section 1 of a medical endoscopic instrument. The insertion section 1 is intended for minimally invasive insertion into a human or animal body in order to be able to illuminate this with light and to make video or image transmission from inside the body possible. To ensure that insertion is minimally invasive, the outer diameter A of the insertion section 1 is as small as possible, and in this example of embodiment is less than 5 mm.

[0053] Arranged next to each other at a distal end face 3 of the insertion section 1 are a first LED 5, a second LED 7 and an image sensor 9, which are distally orientated in a common line of sight x, which in this example of 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 11a,b,c in a face wall 13 of the insertion section 1. The face wall 13 defines an outer surface 15 on the face side 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 which are each flush with the outer surface 15 on the face side 3 of the insertion section 1 and protect against mechanical damage, such as scratches and chemical damage such as through aggressive bodily fluids, cleaning or treatment media and/or oxidation. The protective elements 17a,b,c can also be configured as a common protective glass pane covering the first LED 5, the second LED 7 and the image sensor 9. The protective elements 17a,b,c are permeable for white light, and in this example of embodiment have a refractive index of at least 1.75 as well as a higher breaking strength and hardness than conventional optical glass. The protection elements 17a,b,c can be made of a synthetic monocrystalline crystal. However, the protective elements 17a,b,c are optional here as the proximally arranged optical elements can themselves be sufficiently resistant or can have a correspondingly resistant protective layer on the distal side.

[0054] The first LED 5 has a first luminous spectrum suitable for fluorescence endoscopy that here has a peak between 405 nm and 410 nm with a half value width of 20 nm in the be blue wavelength range. With this blue light of the first LED 5, as part of photodynamic diagnosis (PDD) and/or photodynamic therapy (PDT), a photosensitiser that selectively accumulates on pathological tissue can be made to fluoresce in the red wavelength range. Such fluorescing in the red wavelength ranges can be easily be recorded by the image sensor 9 with no shortpass filter arranged distally upstream. Distally upstream of the image sensor 9 are an objective lens 21 and a longpass filter 23 with a spectral edge at approximately 440 nm. The longpass filter 23 directly blocks shortwave blue light of the first LED 5 that is scattered back by the body, but in white light operation with the second LED 7 allows sufficient blue light portions through for good colour reproduction. However, the first luminous spectrum of the first LED 5 has significant portions above 440 nm, the direct reflection of which on the object to be observed, for example on human tissue, deadens the fluorescence image. As the spectral edge of the longpass filter 23 can be displaced further into the longwave range without impairing colouration in white light operation, a shortpass filter 25 with a spectral edge at approximately 440 nm is arranged upstream of the first LED 5.

[0055] The second LED 7 has luminous spectrum suitable for white light endoscopy, which here has a peak in a first wavelength range of 400 nm to 500 nm and in a second wavelength range of 550 nm to 700 nm decreases with increasing wavelength. The first LED 5 can have the same luminous spectrum as the second LED 7 if the fluorescence stimulation required for the envisaged fluorescence endoscopy can be brought about with it. In this case, the first LED 5 and the second LED 7 can be of the same type.

[0056] In this example of embodiment, the second LED 7 is arranged offset distally with regard to the first LED 5. This is because a lens system 19 is arranged in front of the first LED 5 and behind the protective element 17a. The lens system 19 comprises a shortpass filter 25 with a spectral edge at approximately 440 nm. On average, in accordance with the transmission spectrum 27 (see FIG. 2b, where T indicates the transmission in percent), in a longwave wavelength range above the spectral edge, the light of the first LED 5 is transmitted less than in a shortwave wavelength range below the spectral edge. However, as seen in FIG. 2b, the length of the spectral edge of the shortpass filter 25 depends on the angle of incidence q (see FIG. 2a). As the first LED 5 emits lights like a Lambertian radiator and therefore large portions of light would reach the shortpass filter 25 at a high angle of incidence q and these portions of light would only be able to pass the shortpass filter 25 with very high losses, the lens system 19 comprises a first lens 29 in the form of a converging lens which is arranged between the first LED 5 and the shortpass filter 25. As can be seen in FIG. 2c, the converging lens 29 reduces the mean angle of incidence q significantly so that consequently the light output for the fluorescence light is significantly increased.

[0057] Due to the proximally set back position of the first LED 5 in comparison with the second LED 7, an unwanted keyhole effect is countered in that the lens system 19 comprises a second lens 31 in the form of a diverging lens, which is arranged distally of the shortpass filter 25. As shown in FIG. 3a, through this the illuminated spatial angle can be increased. In FIG. 3b it is clear that the light output can in the first instance be increased in that the converging lens 29 is configured as a plano-convex lens which is placed in the beam path in such a way that its planar surface faces the LED 5 and also the distance between the planar surface and LED 5 is minimal, wherein preferably an air gap remains between the two components in order to maintain a sufficiently high refractive index. This makes it possible that even those light rays that leave the LED 5 at a large angle compared to the surface normal, reach the converging lens 29 and are refracted by the latter onto the optical axis. As a result, the light rays can pass through the light filter 25 and the diverging lens 31 and thus reach the object to be illuminated, e.g. the tissue to be examined. The procedure with the plano-convex lens described above, also has the advantage that in comparison with the procedure shown in FIG. 3a, the light rays hit the converging lens 29 at smaller angles in relation to the normal and, accordingly, the so-called Fresnel losses are smaller, through which the light output can be increased further. As shown in FIG. 3c, the axial length of the particularly strongly curved converging lens 29 can be shortened if it is configured as a Fresnel lens. Even though not shown, the diverging lens 31 can also be configured more thinly as a Fresnel lens.

[0058] FIG. 3d shows the lens system 19 distally of the first LED 5 in the distal end of the insertion section 1. However, the exact alignment, fitting and fixation of the lens system 19 shown in FIG. 3d in the distal end of an insertion section 1 can be very laborious, imprecise and unstable due to the small axial length of the individual components and, in particular, because of the small heights of the respective surfaces that act as interfaces to the recess 11a.

[0059] FIGS. 3e and 3f show particularly advantageous forms of embodiment of the lens system 19 in which both the converging lens 29 comprises a sleeve extension 33 and the diverging lens 31 a sleeve extension 35. The sleeve extensions 33, 35 are thus an integral component of the respective lens 29, 31 configured in one piece. The sleeve extensions 33, 35 are preferably produced by removing a core of a blank by means of an ablative process, for example selective laser etching (SLE). Alternatively, the sleeve extensions 33, 35 with the appurtenant actual lenses 29, 31 can also be produced by additive processes or by combined additive and ablative processes. The sleeve extensions 33, 35 form an outer reference surface with the aid of which the respective lens 29, 31 can be positioned and fixed in the distal end of an insertion section 1 in a much quicker, more stable, simple and precise manner. The sleeve extension 33, 35 extends longer by a factor of 2 or more in the axial direction than the axial thickness of the respective lens on the optical axis.

[0060] The light filter 25, which is arranged as close as possible to the planar proximal side of the diverging lens 35, is circumferentially surrounded by the sleeve extension 35 of the diverging lens 31. The converging lens 29 also projects with its curved distal side into the sleeve extension 35 of the diverging lens 31. The first LED 5 is in turn, circumferentially surrounded by the sleeve extension 33 of the converging lens 29. The converging lens 29 forms a distally acting abutment 37 against which a proximal end 39 of the sleeve extension 35 of the diverging lens 31 is supported. Through this, the lenses 29, 31 are aligned precisely coaxially with regard to the optical axis and can be easily, rapidly and securely fitted.

[0061] Shown in FIG. 3f is a form of embodiment in which the sleeve extension 35 of the diverging lens 31 at least partially surrounds the converging lens 29 and preferably also a distal section 41 of the sleeve extension 33 of the converging lens 29. Here, the abutment 37 is arranged further to proximal than the planar side of the converging lens 29. The first distal section 41 of the sleeve extension 33 of the converging lens 29 has a smaller outer diameter than a second proximal section 43 of the sleeve extension 33 of the converging 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 diverging lens 31. The outer diameter of the second distal section 43 of the sleeve extension 33 of the converging lens 29 approximately corresponds to the outer diameter of the sleeve extension 35 of the diverging lens 31. The distally acting abutment 37 of the converging lens is preferably formed by a circumferential ledge between the first 41 and the second section 43 of the sleeve extension 33 of the converging lens 29. The form of embodiment of the “converging lens-light filter-diverging lens” arrangement shown in FIG. 3f has the advantage that the components of the “converging lens-light filter-diverging lens” arrangement have relatively large reference surfaces in relation to one another which allow the components to be simply, precisely and stably fixed to each other. As a result of this, the “converging lens-light filter-diverging lens” arrangement can be fitted as a stable pre-assembled unit into a distal end of an insertion section 1 in a rapid, precise and stable manner.

[0062] The numbered references to the components or directions of movement as “first”, “second”, “third” etc. are purely arbitrary in order to distinguish between the components or directions of movement and can be selected in any other way. No order of importance is therefore associated with this. Designating a component or technical feature as “first” should therefore not be misunderstood to the effect that there must be a second component or technical feature of this type. Moreover, any process stages can, unless explicitly explained otherwise or absolutely necessary, be carried out in any sequence and/or partially or fully overlapping in time.

[0063] Equivalent forms of embodiment of the parameters, components or functions described herein that in the light of this description appear evident to a person skilled in the art, are covered as if they are explicitly described herein. Accordingly. the protective scope of the claims should cover such equivalent forms of embodiment. “Can” features designated as optional, advantageous, preferably, desired or similar should be understood as optional and not as limiting the scope of protection

[0064] The described forms of embodiment should be understood as illustrative examples and do not represent an exhaustive list of possible forms of embodiment. Every feature disclosed in relation to a form of embodiment can be used alone or in combination with one or more other features, regardless of in which form of embodiment the respective features have been described. Whereas at least one example of embodiment is described and shown herein, derivations and alternative forms of embodiment that appear evident to a person skilled in the art on the basis of this description, are covered by the protective scope of this disclosure. Otherwise, neither should the term “comprise” exclude other features of process steps, nor should “one” rule out a plurality. While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

LIST OF REFERENCE NUMBERS

[0065] 1 Insertion section [0066] 3 End face [0067] 5 First LED [0068] 7 Second LED [0069] 9 Image sensor [0070] 11a,b,c Recess [0071] 13 Face wall [0072] 15 Outer surface [0073] 17a,b,c Protective element [0074] 19 Lens system [0075] 21 Objective lens [0076] 23 Longpass filter [0077] 25 Shortpass filter [0078] 27 Transmission spectrum of the shortpass filter [0079] 29 Converging lens [0080] 31 Diverging lens [0081] 33 Sleeve extension of the converging lens [0082] 35 Sleeve extension of the diverging lens [0083] 37 Abutment [0084] 39 Proximal end of the sleeve extension of the diverging lens [0085] 41 Distal first section of the sleeve extension der converging lens [0086] 43 Distal second section of the sleeve extension der converging lens