OPTICAL SYSTEM OF A STEREO VIDEO ENDOSCOPE

Description

[0001] The invention relates to an optical system of a stereo video endoscope with a lateral viewing direction, comprising a laterally viewing distal optical assembly and a proximal optical assembly, wherein the distal optical assembly comprises an entrance lens, a deflection unit designed as a prism unit and an exit lens successively on a common optical axis in a direction of light incidence, and wherein the proximal optical assembly comprises a left and a right lens system channel, wherein the lens system channels are of a similar construction and arranged parallel to each other and each has its own optical axis.

[0002] Furthermore, the invention relates to a stereo video endoscope with a lateral, in particular fixed, viewing direction and to the use of a lens for an optical system of a stereo video endoscope.

[0003] Video endoscopes, in which light entering at the distal tip of an endoscope shaft is directed by an optical system onto one or more image sensors, are known in various designs. There are endoscopes with a straight-ahead view (a so-called 0° viewing direction), endoscopes with a (fixed) lateral viewing direction, and endoscopes with an adjustable viewing direction (also known as V-DOV endoscopes).

[0004] Furthermore, stereo video endoscopes are known that are designed to record a stereoscopic image pair and / or two stereoscopic video channels. With such instruments, it is possible to generate a 3D image of an object located distal to the end of the endoscope shaft in an examination or operating room.

[0005] Stereo video endoscopes with a lateral viewing direction are endoscopes that look sideways and have a fixed viewing angle that differs from a straight-ahead view. Such endoscopes often include a prism arrangement consisting of several prisms that reflect the light rays entering the optical system from the object space at an angle to the longitudinal axis of the endoscope shaft twice and deflect them laterally in the direction of the endoscope shaft. An example of such an endoscope is known from DE 10 2014 206 513 A1 of Olympus Winter & Ibe GmbH, Hamburg.

[0006] A deflecting prism array of such a stereo video endoscope typically comprises two or three prisms. The prisms are cemented together at their common interfaces. In such a deflecting prism array, the reflection of the incident light beams occurs at two reflective interfaces of a second or third prism, which are inclined both to the optical axis of the entrance lens and to the longitudinal axis of the endoscope shaft. The second or third prism of the deflecting prism array is located downstream of a first or second prism, which is positioned downstream of the entrance lens. The inclined reflective interface of the second or third prism, where the second reflection occurs, partially shares an interface with the front prism, through which the incident light rays first pass.

[0007] The entrance lens of the optical system of such a stereo video endoscope defines the optical axis of the system. The optical system includes apertures or menisci that define the field of view or the opening angles of the optics. Light beams entering the optical system within the field of view are focused onto one or more image sensors. Light beams entering the optical system from outside the field of view or through multiple reflections create so-called "ghost images" or "flares."

[0008] A well-known prism group capable of producing such ghost images comprises a first prism and a second prism cemented together. The first prism has an entrance face and an exit face, with the entrance face inclined relative to the exit face. The exit face of the first prism is directly adjacent to a second entrance face of the second prism. For example, the first and second prisms are cemented together at these two sides. The second prism further comprises a reflection face and a second exit face. Light entering the prism group from the image field passes through the entrance face of the first prism and exits at its exit face. The light then passes directly through the second entrance face into the second prism, is reflected at the reflection face within the second prism, and exits at the exit face.

[0009] US 5,689,365 discloses a stereo video endoscope in which a distal optical assembly is provided with a lateral viewing direction.

[0010] Furthermore, US patent 2009 / 0296235 A1 describes an optical system for endoscopes that is arranged distally within the endoscope. Additionally, US patent 2016 / 0370580 A1 discloses a method for manufacturing an optical element in which ink containing a light-blocking material is applied to the surface of an optical body using an inkjet printing process.

[0011] Furthermore, US 2017 / 0235121 A1 reveals an endoscope lens system that has a thin diameter.

[0012] Based on this state of the art, the object of the invention is to prevent the formation of ghost images in a stereo video endoscope in a simple manner.

[0013] This problem is solved by an optical system of a stereo video endoscope with a lateral viewing direction, comprising an aperture, a laterally viewing distal optical assembly, and a proximal optical assembly, wherein the distal optical assembly comprises an entrance lens, a deflection unit designed as a prism unit, and an exit lens successively on a common optical axis in one direction of light incidence, and wherein the proximal optical assembly comprises a left and a right lens system channel, wherein the lens system channels are of identical construction and arranged parallel to each other and each has its own optical axis, which is further developed by the fact that the exit lens is formed with an opaque coating in the middle region of the exit lens on its light-entry side facing the deflection unit, wherein the exit lens is arranged behind the aperture in the direction of light incidence.

[0014] The invention is based on the idea that the exit lens of the distal optical assembly, which is preferably arranged on the prism unit of the distal optical assembly, is provided with a coating, whereby no light passes through the exit lens in the central area and the formation of ghost images in the lens system channels is minimized or prevented.

[0015] The exit lens is preferably designed as a prism lens, wherein the light rays for the left and right optical channels are transmitted between the area of ​​the transparent coating on the exit lens and the outer edge of the exit lens. No light rays are transmitted in the central area of ​​the exit lens, where the coating(s) are applied. Due to the coating(s), the exit lens has an annular or ring-like optical transmission area.

[0016] In a further development of the optical system, it is provided that the coating on the exit lens on its light entry side facing the deflection unit is formed with a light-impermeable coating in a circular or circular shape.

[0017] Preferably, the exit lens is formed with an opaque coating in the central area of ​​the exit lens on its light exit side facing away from the deflection unit.

[0018] According to a further development, it is provided that the coating on the exit lens on its light entry side facing away from the deflection unit is formed with a light-impermeable coating in a circular or circular shape.

[0019] Preferably, the exit lens for the left lens system channel and the right lens system channel of the proximal optical assembly is transparent, wherein in particular the optical transmission area of ​​the exit lens is formed in a ring-like or annular shape outside the coating(s).

[0020] Furthermore, it is preferred that the side of the exit lens facing away from the deflection unit is convex.

[0021] Preferably, the exit lens is designed as a concave-convex lens.

[0022] Furthermore, in the optical system, it is preferred that the coating on the exit lens on its light-entry side facing the deflection unit is designed as an antireflective coating and / or that the coating on the exit lens on its light-entry side facing away from the deflection unit is designed as an antireflective coating. The antireflective coating is intended to reduce or prevent the formation of flares or ghost images.

[0023] Furthermore, it is preferred that the opaque coating or the anti-reflective coating is designed as a chrome coating.

[0024] Furthermore, the problem is solved by a stereo video endoscope with a fixed, preferably lateral, viewing direction and an optical system as described above. The optical system comprises one or more of the aforementioned embodiments.

[0025] Furthermore, the problem is solved by using a lens for an optical system of a stereo video endoscope with a fixed viewing direction, wherein the optical system is designed according to the aforementioned embodiments, wherein the lens is designed as an exit lens of a distal optical assembly and is designed with an opaque coating in the central region of the exit lens on its light entry side facing a deflection unit of the distal optical assembly.

[0026] Further features of the invention will become apparent from the description of embodiments according to the invention, together with the claims and the accompanying drawings. Embodiments according to the invention may fulfill individual features or a combination of several features.

[0027] The invention is described below, without limiting the general concept, with reference to exemplary embodiments and the drawings, whereby for all details of the invention not explained in detail in the text, explicit reference is made to the drawings. The drawings show: Fig. 1 schematically a stereo video endoscope in a simplified perspective view, Fig. 2 an optical system of a stereo video endoscope according to the prior art in a simplified schematic sectional view, Fig. 3a schematically a cross-section through an exit lens according to the invention of a distal optical assembly of the stereo video endoscope and Fig. 3b schematically a view of the exit lens of the distal optical assembly.

[0028] In the drawings, identical or similar elements and / or parts are provided with the same reference numbers, so that a re-presentation is omitted.

[0029] Fig. 1Figure 1 shows a simplified perspective view of a known endoscope 2 with a proximal handle 4 and a rigid endoscope shaft 6. A viewing window 10 is located at a distal tip 8 of the endoscope shaft 6. A distal section 12 of the endoscope shaft 6 adjoins this. A [missing information - likely a specific feature or component] is located in the distal section 12. Fig. 1 An optical system, not visible, is arranged to image an examination or surgical area located in front of the distal tip 8 of the endoscope 2 onto image sensors, which are also not shown. A rotary knob 14 extends distally from the handle 4, allowing the optical system located inside the endoscope shaft 6 to be rotated azimuthally.

[0030] Fig. 2Figure 1 shows a simplified schematic sectional view of an optical system, such as that known from DE 10 2013 215 422 A1 of Olympus Winter & Ibe GmbH, Hamburg. The optical system comprises a sideways-looking distal optical assembly 16, which is arranged behind the entrance window 10. For example, the optical system shown is located in the distal section 12 of the Fig. 1 The stereo video endoscope 2 shown. In addition to the distal optical assembly 16, the optical system includes a proximal optical assembly 18. This can be rotated, for example, by turning the rotary knob 14 in the endoscope shaft 6.

[0031] The distal optical assembly 16 comprises an entrance lens 20, which is designed, for example, as a raised negative meniscus. It has a convex outer surface 22 and a concave inner surface 24. Light entering from the left through the viewing window 10 passes through the entrance lens 20 and enters a deflection unit 26 designed as a prism unit. This unit comprises two prisms with a partially mirrored or mirrored interface. The light incident obliquely from the side is deflected by the deflection unit 26 in the direction of a longitudinal axis of the endoscope shaft 6. The deflection unit 26 comprises a first partially mirrored prism 28, which includes the partially mirrored interface 26b. Furthermore, the deflection unit 26 comprises another partially mirrored prism 30, which is not shown in detail, and which includes the mirrored interface 26a.

[0032] Furthermore, the distal optical assembly 16 comprises an exit lens 32, which is arranged behind an aperture 34 in the direction of light incidence.

[0033] Light enters the exit lens 32 from the deflection unit 26. The exit lens 32 is exemplary in its design as a hollow positive meniscus lens. It has a concave entrance surface 36a and a convex exit surface 36b. The radius of curvature of the concave entrance surface 36a is larger than the radius of curvature of the convex exit surface 36b.

[0034] After traveling a short distance, the light exiting the exit lens 32 reaches the proximal optical assembly 18. This assembly comprises a left lens system channel 38L and a right lens system channel 38R. The two lens system channels 38L and 38R are identical in design and arranged parallel to each other. The left optical channel has a left optical axis LoA, and the right optical channel has a right optical axis RoA. The optical axes LoA and RoA are oriented at least approximately parallel to each other. Each of the two lens system channels 38L and 38R comprises a rod lens 40L and 40R, into which the light from the exit lens 32 of the distal optical assembly 16 first enters. An achromatic lens group 42L and 42R is attached to each of the left and right rod lenses 40L and 40R, respectively, in the direction of light incidence. The achromatic lens groups 42L and 42R are each configured as triplets. From these, the light is directed onto the left and right lenses, respectively.The right image sensor 44L, 44R is steered so that the examination or operating space lying in front of the distal tip 8 of the endoscope shaft 6 is stereoscopically imaged.

[0035] Further details on the structure of the in Fig. 2 The optical system shown can be found in the aforementioned DE 10 2013 215 422 A1. Figs. 3a and 3b are a cross-sectional view ( Fig. 3a ) and a front view ( Fig. 3b ) an exit lens 32 of the distal optical unit 16 (cf. Fig. 2 ) according to an embodiment of the invention, shown schematically. The exit lens 32 is designed as a concave-convex lens with a concave entrance surface 36a and a convex exit surface 36b.

[0036] According to the invention, a circular coating 46 is formed in the central region on the convex exit surface 36b, such that no light is transmitted from the coating 46 in the central region. In particular, the coating is formed as a circular area on the convex exit surface. Preferably, the coating 46 is formed as a chromium coating. Reference symbol list

[0037] 2 Stereo video endoscope 4 Handle 6 Endoscope shaft 8 Distal tip 10 Viewing window 12 Distal section 14 Rotary knob 16 Distal optical assembly 18 Proximal optical assembly 20 Entrance lens 22 Outer surface 24 Inner surface 26 Deflection unit 26a, 26b Interface 28 Partially mirrored prism 30 Additional partially mirrored prism 32 Exit lens 34 Aperture 36a Concave entrance surface 36b Convex exit surface 38L Left lens system channel 38R Right lens system channel 40L, 40R Bar lens 42L, 42R Chromatic lens group 44L, 44R Image sensor 46 Coating Left optical axis, Right optical axis

Claims

1. An optical system of a stereo-video endoscope (2) with a sideways viewing direction, comprising a sideways-viewing distal optical assembly (16) and a proximal optical assembly (18), wherein the distal optical assembly (16) comprises an inlet lens (20), a deflecting unit (26) designed as a prism unit, and an outlet lens (32) on a common optical axis one after the other in the direction of light incidence, and the proximal optical assembly (18) comprises a left and a right lens system channel (38L, 38R), wherein the lens system channels (38L, 38R) are identically designed and are arranged parallel to each other, and each lens system channel has its own optical axis (LoA, RoA), characterized in that the outlet lens (32) is formed with a light-impermeable coating (46) on the light inlet side (36a) facing the deflecting unit (26) in the central region of the outlet lens (32), wherein the outlet lens (32) is arranged behind a diaphragm (34) in the direction of light incidence.

2. The optical system according to claim 1, characterized in that the coating (46) on the outlet lens (32) is formed in the form of a circle or in the manner of a circle on its light inlet side (36a) facing the deflection unit (26) with a light-impermeable coating (46).

3. The optical system according to claim 1 or 2, characterized in that characterized in that the outlet lens (32) is formed with a light-impermeable coating (46) on the light outlet side (36b) facing away from the deflecting unit (26) in the central region of the outlet lens (32).

4. The optical system according to claim 3, characterized in that the coating (46) on the outlet lens (32) is formed in the form of a circle or in the manner of a circle on its light inlet side (36b) facing away from the deflection unit (26) with a light-impermeable coating (46).

5. The optical system according to any of the claims 1 to 4, characterized in that the outlet lens (32) for the left lens system channel (38L) and the right lens system channel (38R) of the proximal optical assembly (18) is permeable to light.

6. The optical system according to any one of claims 1 to 5, characterized in that the side of the outlet lens (32) facing away from the deflecting unit (26) is convex.

7. The optical system according to any one of claims 1 to 6, characterized in that the outlet lens (32) is formed as a concave-convex lens.

8. The optical system according to any one of claims 1 to 7, characterized in that the coating (46) on the outlet lens (32) is formed as an anti-reflex coating (46) on its light inlet side (36a) facing the deflection unit (26) and / or in that the coating (46) on the outlet lens (32) is formed as an anti-reflex coating (46) on its light inlet side (36b) facing away from the deflection unit (26).

9. The optical system according to claim 8, characterized in that the anti-reflex coating (46) is formed as a chromium coating (46).

10. A stereo-video endoscope (2) having a fixed viewing direction having an optical system (20) according to any one of claims 1 to 9.

11. Use of a lens (32) for an optical system (20) of a stereo-video endoscope (2) having a fixed viewing direction according to any one of claims 1 to 9, wherein the lens (32) is formed as an outlet lens (32) of a distal optical assembly (16) and is formed with a light-impermeable coating (46) on the light inlet side (36a) facing a deflecting unit (26) of the distal optical assembly (16) and / or with a light-impermeable coating (46) on the light outlet side (36b) facing away from a deflecting unit (26) of the distal optical assembly (16) in the central region of the outlet lens (32).