ENDOSCOPE

Abstract

An endoscope may have a shaft having a distal end portion and a proximal end portion. The endoscope may also have a first objective arranged at the distal end portion and a first optical axis. The endoscope may also have a second objective arranged at the distal end portion and a second optical axis. The endoscope may also have a lens system disposed within the shaft between the distal end portion and the proximal end portion, the lens system having an optical axis. The first objective and the second objective may be both optically coupled to the same lens system such that first parallel rays from the first objective and second parallel rays from the second objective are input into the lens system. The lens system may be an optical relay system may have at least one relay group or a tube lens group.

Claims

1-16. (canceled)

17. An endoscope, comprising: a shaft having a distal end portion and a proximal end portion, a first objective arranged at the distal end portion and having a first direction of view, and a first optical axis, the first objective being set up to generate an object image in infinity, a second objective arranged at the distal end portion and having a second direction of view, and a second optical axis, the second objective being set up to generate an object image in infinity, and a lens system disposed within the shaft between the distal end portion and the proximal end portion, the lens system having an optical axis, wherein the first objective and the second objective are both optically coupled to the same lens system such that first parallel rays from the first objective and second parallel rays from the second objective are input into the lens system, wherein the lens system is an optical relay system comprising at least one relay group or a tube lens group.

18. The endoscope according to claim 17, wherein a distance between the first objective and the lens system differs from a distance between the second objective and the lens system.

19. The endoscope according to claim 17, wherein the first direction of view differs from the second direction of view, wherein the first optical axis and the second optical axis are parallel to each other.

20. The endoscope according to claim 17, wherein all optical components of the first and second objectives are fixed relatively to the shaft.

21. The endoscope according to claim 17, wherein the first direction of view, the second direction of view and the optical axis of the lens system are tilted relative to each other and do not lie in the same plane.

22. The endoscope according to claim 17, wherein chief rays coming from different object points and output from the objectives are not parallel to each other and/or are not parallel to the optical axis of the lens system.

23. The edndoscope according to claim 17, wherein the first optical axis is parallel to the first direction of view and/or wherein the second optical axis is not parallel to the second direction of view.

24. The endoscope according to claim 17, wherein the magnification of the relay system is −1 or 1 and/or the magnification of the at least one relay group is −1 or 1.

25. The endoscope according to claim 17, wherein the relay system is afocal and/or the at least one relay group is afocal.

26. The endoscope according to claim 17, wherein the relay system is configured to generate first and second intermediate images from the first and second rays, respectively, wherein the first and second intermediate images are generated within the at least one relay group and at least partially overlay, including concentrically overlay.

27. The endoscope according to claim 17, wherein the first and second rays are coupled out of the relay system at the proximal end portion, wherein the first and second rays are spatially separated from each other at the proximal end portion.

28. The endoscope according to claim 17, wherein the at least one relay group comprises an input lens group, an output lens group, a cavity defined between the input lens group and the output lens group, and a field lens disposed in the cavity.

29. The endoscope according to claim 28, wherein first and second intermediate images are generated within the relay group between the field lens and the output lens group such that the first and second intermediate images have a size, which is smaller than a maximum diameter of all lenses of the relay group.

30. The endoscope according to claim 29, wherein the relay system comprises a plurality of relay groups that are arranged in series, wherein each relay group is configured to generate first and second intermediate images within the respective relay group, wherein all intermediate images generated in the relay system have the same paraxial size.

31. The endoscope according to claim 17, wherein the at least one relay group is axial symmetric around a symmetry axis, which is perpendicular to the optical axis of the relay system, wherein the symmetry axis is disposed in the center of the relay group.

32. The endoscope according to claim 17, further comprising an image sensor arranged at the distal end portion of the shaft, wherein the tube lens group is arranged between the first and second objectives and the image sensor, the tube lens group projecting a first final image and/or a second final image onto the image sensor.

Description

[0059] Various objects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description of embodiments, when read in light of the accompanying drawings.

[0060] FIG. 1 shows schematic representations of two endoscopes.

[0061] FIG. 2 schematically illustrates several optical components of an endoscope.

[0062] FIG. 3 schematically illustrates several optical components disposed in a front/distal tip of the endoscope of FIG. 2.

[0063] FIG. 4 schematically illustrates a relay group of one of the endoscopes depicted in FIGS. 1-3.

[0064] FIG. 5 schematically illustrates a part of the endoscope depicted in FIGS. 1-3.

[0065] FIG. 6 schematically illustrates a detail of the endoscope shown in FIGS. 1-3 and further including a shutter.

[0066] FIG. 7 schematically illustrates a front/distal tip of an endoscope.

[0067] FIG. 8 schematically illustrates a conventional endoscope.

[0068] FIG. 9 schematically illustrates a further example of a relay group.

[0069] In the following, recurring and similar features in this and in the subsequent representations are provided with the same reference numerals.

[0070] In FIG. 1 two endoscopes 1, 1′ are schematically illustrated. The endoscopes 1, 1′ comprise an elongated rigid shaft 2 having a distal end portion 3, a proximal end portion 4 and an intermediate portion extending therebetween. The endoscopes 1, 1′ further comprise a first objective 5 and a second objective 6 which are disposed in the distal end portion 3 of the shaft 2.

[0071] The first objective 5 has a first direction of view 7, a first focal plane 25 on the object side coincident with the object plane, and a first optical axis 21. The second objective 6 has a second direction of view 8, a second focal plane 26 on the object side coincident with the object plane, and a second optical axis 22. The first and second objectives 5, 6 are set up to generate an object image in infinity. The objectives 5, 6 are typically disposed inside the shaft 2. The field of view of each objective 5, 6 is indicated in FIG. 1 by a cone accompanying the respective direction of view 7, 8.

[0072] Reference is additionally made to FIG. 3, which shows several optical components disposed in distal end portion 3 of the endoscope, which is sometimes called the front tip 33 of the endoscope 1. It should be mentioned that the optical layout of the objectives 5, 6 shown in FIG. 3 can also be used for the objectives 5, 6 of endoscope 1′.

[0073] The first and second objectives 5, 6 include a plurality of lenses. In the embodinvent depicted, each of the objectives 5, 6 includes an input lens group 27 and an output lens group 28. The input lens groups 27 of the objectives 5, 6 can be of the same design or may each have a different optical design. The output lens groups 28 of the objectives 5, 6 may have the same optical design or differ from each other. The input lens group 27 gathers light coming from the object being observed, while the output lens group 28 faces the lens system 10, 30. In some examples, the input lens group 27 of the objectives 5, 6 has a negative focal length, while the output lens group 28 of the objectives 5, 6 has a positive focal length. The second objective 6 comprises a prism assembly 29 arranged between the input lens group 27 and the output lens group 28. The prism assembly 29 can comprise an arrangement of reflective and/or refractive prisms. By virtue of the first lens group 27 and the prism assembly 29 the second direction of view 8 of the second objective 6 differs from the first direction of view 7 of the first objective 5. In particular, the first direction of view 7 and the second direction of view 8 are not parallel to each other.

[0074] The first optical axis 21 of the first objective 5 is defined by the optical axis of the output lens group 28 thereof. Further, the second optical axis 22 of the second objective 6 is defined by the optical axis of the output lens group 28 thereof. The first and second optical axes 21, 22 may be parallel to each other, but do not overlap each other. Furthermore, the first and second optical axes 21, 22 are parallel to the optical axis of the lens system 10, 30 and the longitudinal axis of the shaft.

[0075] In the depicted embodiment, the optical axis 21 and the first direction of view 7 are parallel to each other. Furthermore, an axial extension the first optical axis 21 coincides with an axial extension of the direction of view 7. According to alternative embodiments, the first direction of view 7 is not parallel to the first optical axis 21. In contrast, the optical axis 22 is not parallel to the second direction of view 8. As follows from the above, the optical axes 21, 22, the directions of view 7, 8 can be varied and adapted to practical needs.

[0076] As can be seen from FIG. 7, which shows a front tip 33 of exemplary endoscopes 1, 1′, the second direction of view 8 is tilted with respect to the optical axis 9 of the lens system 10, 30 and the longitudinal axis of the shaft 2. Consequently, the first direction of view 7, the second direction of view 8 and the optical axis 9 do not lie in the same plane. In a further example, the first direction of view 7 and the second direction of view 8 are tilted with respect to the optical axis 9 of the lens system 10, 30 and the longitudinal axis of the shaft 2.

[0077] In alternative embodiments (not shown), the first direction of view and the second direction of view are parallel to each other. This may be particularly useful for stereoscopic endoscopes.

[0078] Optionally, the first direction of view 7 forms a plane with the first optical axis 21 of the first objective 5, which is parallel and not coincident with a plane formed by the second direction of view 8 and the second optical axis 22 of the second objective 6. The first optical axis 21 and the second optical axis 22 may each form a plane with the optical axis 9 of the lens system 10, 30 (i.e. relay system 10 or tube group 30), wherein these planes are usually not perpendicular to the planes mentioned above.

[0079] The optical components of the first and second objectives 5, 6 are fixed relatively to one other and to the shaft 2. Thus, the objectives 5, 6 do not include any moving or rotating parts.

[0080] Even though the endoscopes 1, 1′ shown comprise two objectives 5, 6, it should be mentioned that the endoscopes 1, 1′ may also comprise more than two objectives.

[0081] The endoscopes 1, 1′ further include a lens system 10, 30 disposed within the shaft 2 between the distal end portion 3 and the proximal end portion 4, the lens system 10, 30 having an optical axis 9. The optical axis 9 is parallel to the longitudinal axis of the shaft 2 and optionally coincides with the longitudinal axis of the shaft 2. Both objectives 5, 6 share the same lens system 10, 30 and are optically coupled thereto. The optical axes 21, 22 are parallel to the optical axis 9 and decentered with respect to the optical axis 9.

[0082] Both objectives 5, 6 form images at a plane in infinity, therefore the object to be observed is at a plane coincident with the object side focus plane 25, 26, which means for all rays p1, p2, p3, p4, p5, p6 coming from a specific point in the object plane (focus plane 25, 26) the marginal rays are parallel to the corresponding chief ray. Light rays coming from the objectives 5, 6 are directly input in the lens system 10, 30. In particular, since the focal planes 25, 26 are coincident with the corresponding object planes, the objectives 5, 6 generate first and second rays, where the marginal rays are parallel to the chief ray, respectively, that are directly input into the lens system 10, 30.

[0083] The space between the objectives 5, 6 and the lens system 10, 30 defines an infinity space 20, as the image distance of both objectives 5, 6 is set to infinity. The term infinity space 20 refers to the production of a flux of light rays, where the marinal rays are parallel to their corresponding chief rays after passing through the respective objectives 5, 6. For instance, in FIG. 3, groups of light rays p1, p2, p3, p4, p5, p6 coming from respective object points are indicated. For each group of rays p1, p2, p3, p4, p5, p6 coming from a respective object point the marginal rays are parallel to the corresponding chief ray at the image side of the objectives 5, 6, i.e. in the infinity space 20.

[0084] The infinity space 20 allows a variable distance between the objectives 5, 6 and the lens system 10, 30. This may improve freedom of design of the optical components of the endoscopes 1, 1′, especially of the objectives 5, 6. This can be very helpful since the space in the distal end portion 3 of the shaft is typically constricted. For example, according to FIGS. 1, 2, 3, 5 and 7, a distance d1 between the first objective 5 and the lens system 10, 30 differs from a distance d2 between the second objective 6 and the lens system 10, 30. As the lenses usually have an exit surface with an arced shape, the distances d1, d2 may refer to the smallest distance between the objectives 5, 6 and the lens system 10, 30, respectively.

[0085] As can be seen from FIG. 3, chief rays coming from different object points and output from the objectives 5, 6 are parallel neither to each other nor to the optical axis 9 of the lens system 10, 30.

[0086] In accordance with the endoscope tip 33 shown in FIG. 7, to use the available space of the two objectives 5, 6 in the endoscope tip 33 more efficiently, the two objectives 5, 6 can be arranged such that the optical axes 21, 22 of the two objectives 5, 6 define a plane, wherein at least one direction of view 7, 8 does not lie in this plane. Further, the optical axes 21, 22 of the two objectives 5, 6 and the optical axis 9 of the lens system 10, 30 do not need to be in the same plane.

[0087] In the following, reference is made to the endoscope 1 of FIG. 1, parts of which are shown in FIGS. 2-7.

[0088] The endoscope 1 comprises a relay system 10 in order to extend the optical pathway of the endoscope 1 within the shaft 2. The first objective 5 and the second objective 6 are optically coupled to the relay system 10 such that the rays output from the objectives 5, 6 are directly input into the relay system 10, i.e. there are no optical components disposed between the objectives 5, 6 and the relay system 10.

[0089] The relay system 10 is afocal and has a magnification of −1. The relay system 10 includes a plurality of relay groups 11 that are arranged in series. Each relay group 11 has the same optical layout. For instance, each relay group 11 has a magnification of −1. The total number of relay groups 11 is uneven. Each of the relay groups 11 may comprise an input lens group 12, a field lens 13 and an output lens group 14. The field lens 13 may be a positive-powered lens (e.g. singlet) or group of lenses (e.g. doublet). Typically the input lens group 12 and/or the output lens group 14 are doublets each having a positive focal length and being arranged close to a pupil plane. The lenses of the relay system 10 are selected such that the first and second intermediate images are generated from the first and second rays coming out of the first objective 5 and the second objective 6, respectively, wherein the intermediate images are generated at an intermediate image plane 15 inside the relay groups 11.

[0090] The field lens 13 is placed within each relay group 12 of the relay system 10 close to the intermediate image 15 to solve the vignetting issue without telecentric design. This field lens 13 projects the pupil from the front part into the rear part of the relay group 11. The design of this relay system 10 furthermore allows a lens design without rod lenses in contrast to conventional endoscopic relay system (see FIG. 8), where rod lenses are uses to get larger apertures through the relay system. The advantage of this relay design having a field lens 13 and without rod lenses is a reduced weight and a reduced risk of broken lenses.

[0091] Inside the relay system 10, the chief rays coming from different object points are not parallel to each other and also not parallel to the optical axis 9 of the relay system 10.

[0092] The images of both objectives 5, 6 are concentrically overlaid in the intermediate image plane 15 of each relay group 11 of the relay system 10, while the pupils of both objectives 5, 6 are spaced from each other and decentered in the pupil plane 16 of the relay system 10. The size of the intermediate images at the intermediate image plane 15 and the size of the pupil plane 16 are smaller than the overall diameter of the lenses of the relay system 1. By blocking the pupil plane 16 in front of an input lens group 12 or an output lens group 14 of any relay group 11 of the relay system 10 partly e.g. with a mask on a rotatable disk, a shifting mask or a shutter 18, one can switch between the images of the two objectives 5 and 6. Alternatively, the shutter 18 may be also disposed between the two objectives, 5,6 and the relay system 10 (not shown).

[0093] FIG. 9 shows an alternative embodiment of a relay group 41 having a symmetric design, which can be used instead of relay group 11 or in addition to relay group 11. Thus, in some embodiments the relay system 10 may comprise a plurality of relay groups 41 that are arranged in series. Optionally, the relay system 10 may comprise at least one relay group 11 and at least one relay group 41 that are arranged in series. When more than one relay group 41 is envisaged in the relay system 10, each relay group 41 of the relay system 10 may have the same symmetric optical layout. The total number of relay groups 41 comprised in the relay system 10 may be uneven. Similar to relay group 11, the relay group 41 may comprise an input lens group 42 and an output lens group 42. Preferably, the relay group 41 has a magnification of −1 or 1 and is afocal. Between the input lens group 42 and the output lens group two lenses 46, 48 may be disposed, which may be field lenses. The lenses 46, 48 may be identical with respect to their optical properties, however, the lens 48 is rotated by 180 degrees with respect to the optical axis 9. The relay group 41 is axial symmetric around a symmetry axis 45, which is perpendicular to the optical axis 9 of the relay system 10. As shown in FIG. 9, the symmetry axis 45 may be disposed between lenses 46, 48, preferably at the center of the relay group 41. In the embodiment shown, the symmetry axis 45 does not coincide with a lens or lens group. In other embodiments, the symmetry axis coincides with a lens or lens group, which have a symmetric design. In this case, the material of the lens or lens group should be selected to have a high degree of purity.

[0094] In the embodiment of FIG. 9, only two lenses 46, 48 are arranged between the input lens group 42 and the output lens group 44. In some embodiments, there may be even more lenses disposed in the cavity of the relay group 41 as long as the relay group 41 has a magnification of −1, and is both afocal and axial symmetric around the symmetry axis 45. The symmetric design of the relay group 41 allows to reduce the amount of different lens types within the endoscope, which may result in less complexity in the production and reduced costs. Typically, the lenses 46, 48 are singlets, have a positive focal length, a relatively low refraction index and are close to an intermediate image. Typically the lenses groups 42, 44 are doublets each with a positive focal length and being arranged close to a pupil plane. Preferably, the lens groups and lenses 42, 44, 46, 48 of the relay group 41 are selected and arranged such that the first and second intermediate images are generated from the first and second rays 23, 24 at an intermediate image plane inside the relay group 41, wherein the intermediate image plane substantially coincides with the symmetry axis 45.

[0095] The relay system 10 (including the relay groups 11 and/or relay groups 41) may be configured such that the first rays 23 and the second rays 24 are coupled out of the relay system 10 at the proximal end portion 4. In particular, the first rays 23 and the second rays 24 may be spatially separated from each other at the proximal end portion 4. Furthermore, the first and second rays output from the first and second objectives 5, 6, wherein the marginal rays are parallel to the corresponding chief rays and coupled out of the relay system 10 have still marginal rays, which are parallel to the corresponding chief rays.

[0096] Table 1 below summarizes an exemplary set of lens data of the endoscope 1 having relay groups 11. It is noted that the prism assembly 29 of the second objective 6 is not incorporated in this table. However, a person skilled in the art is able to model the prism assembly 29 of the second objective 6.

[0097] As usual, the optical glasses used are designated by a numerical glass code. In Table 1, a ten-digit code is used. The first six digits correspond to the refractive index in terms of (n.sub.d−1)×10.sup.6. The 4 decimals correspond to the Abbe number in terms of v.sub.d×10.sup.2. E.g. for n.sub.d=1.5168, v.sub.d=64.17 the glass code is 516800.6417.

TABLE-US-00001 TABLE 1 lens data of the endoscope 1 having objective 5 and the relay system 10. Surface Radius Thickness glass code Non-Centered data Object infinity 110.000 1 −5.176 0.301 640002.6021 2 11.465 0.301 517602.6350 3 13.743 9.085 4 infinity 0.301 753671.3750 5 6.879 0.701 693495.5081 6 −9.502 3.000 7 infinity 0.000 Decenter Y = +/−1.6 8 30.976 2.000 692109.5454 9 −13.225 2.000 749502.3495 10 −137.099 34.732 11 6.231 1.500 516800.6417 12 10.689 35.305 13 −133.873 0.750 740769.2779 14 35.448 1.300 716998.4796 15 −36.146 0.439 16 43.892 1.300 585990.6105 17 −199.945 3.000 18 30.976 2.000 692109.5454 19 −13.225 2.000 749502.3495 20 −137.099 34.732 21 6.231 1.500 516800.6417 22 10.689 35.305 23 −133.873 0.750 740769.2779 24 35.448 1.300 716998.4796 25 −36.146 0.439 26 43.892 1.300 585990.6105 27 −199.945 3.000 28 30.976 2.000 692109.5454 29 −13.225 2.000 749502.3495 30 −137.099 34.732 31 6.231 1.500 516800.6417 32 10.689 35.305 33 −133.873 0.750 740769.2779 34 35.448 1.300 716998.4796 35 −36.146 0.439 36 43.892 1.300 585990.6105 37 −199.945 3.000 38 30.976 2.000 692109.5454 39 −13.225 2.000 749502.3495 40 −137.099 34.732 41 6.231 1.500 516800.6417 42 10.689 5.860 43 −19.079 0.995 755199.2751 44 5.221 2.830 639999.6008 45 −7.624 0.075 46 4.719 2.000 750840.2769 47 22.341 0.000

[0098] The endoscope 1′ differs from the endoscope 1 in that a tube lens group 30 is disposed after the first and second objectives 5, 6 instead of the relay system 10.

[0099] The endoscope 1′ comprises an image sensor 31 at the distal portion of the shaft 2 and on the image side of the objectives 5, 6. The tube lens group 30 is arranged between the objectives 5, 6 and the image sensor 31. The tube lens group 30 is configured to project a first final image and/or a second final image onto the image sensor 31. To this end, the image sensor 31 may be disposed in the focal plane of the tube lens group 30. The tube lens group 30 has a positive focal length and may comprise solely one lens or a plurality of lenses.

[0100] A shutter 32 may be disposed between the objectives 5, 6 and the tube lens group 30. The shutter 32 can be used to switch between images from the first and second objectives 5, 6, thus allowing different directions of view 7, 8. If the first and second objectives 5, 6 have the same direction of view (not shown), the shutter 32 may switch between left and right creating a 3D image (stereoscopic image) using just one image sensor 31. By partially blocking the pupil plane of the objectives a user can switch between the images of the two objectives.

REFERENCE NUMERALS

[0101] 1 endoscope

[0102] 1′ endoscope

[0103] 2 shaft

[0104] 3 distal end portion

[0105] 4 proximal end portion

[0106] 5 first objective

[0107] 6 second objective

[0108] 7 first direction of view

[0109] 8 second direction of view

[0110] 9 optical axis

[0111] 10 relay system

[0112] 11 relay group

[0113] 12 input lens group

[0114] 13 field lens

[0115] 14 output lens group

[0116] 15 intermediate image plane

[0117] 16 pupil plane

[0118] 17 cavity

[0119] 18 shutter

[0120] 19 eye piece

[0121] 20 infinity space

[0122] 21 first optical axis

[0123] 22 second optical axis

[0124] 23 first rays

[0125] 24 second rays

[0126] 25 first focal plane

[0127] 26 second focal plane

[0128] 27 input lens group

[0129] 28 output lens group

[0130] 29 prism assembly

[0131] 30 tube lens group

[0132] 31 image sensor

[0133] 32 shutter

[0134] 33 front tip

[0135] 41 relay group

[0136] 42 input lens group

[0137] 44 output lens group

[0138] 45 symmetry axis

[0139] 46 field lens

[0140] 48 field lens

[0141] 51 endoscope

[0142] 52 objective

[0143] 53 relay system

[0144] 54 eye piece

[0145] 55 intermediate images

[0146] 56 object

[0147] d1 distance

[0148] d2 distance

[0149] p1 light rays

[0150] p2 light rays

[0151] p3 light rays

[0152] p4 light rays

[0153] p5 light rays

[0154] p6 light rays