Endoscope and optical system thereof

Abstract

The utility model discloses an endoscope and optical system thereof, through setting up multiple nanometer protrusions with array arrangement on the first surface of optical system bare outside endoscope, to make the first surface have stronger lyophobicity, can reduce the adhesion of body fluid or irrigation liquid etc. in endoscope use, simultaneously, through setting up the diameter of nanometer protrusion as less than the minimum working wavelength of the optical system, can make the transmittance of the first lens to the light located in the working wavelength range not less than 70%. Thus, the optical system of the utility model has good lyophobicity and light transmission, can avoid the reduction of endoscope imaging quality due to the water and blood adhesion of optical lens. Compared with the existing film coating liquid adhesion prevention mode, can avoid the problem of easy film layer peeling, has better stability and reliability.

Description

Technical Field

[0001] This utility model relates to the field of endoscopes, and in particular to an endoscope and its optical system. Background Technology

[0002] During use, the environment of an endoscope is not a purely gaseous environment; it comes into contact with bodily fluids, including blood, tissue fluid, saliva, or gastric juice. These fluids can easily adhere to the surface of the endoscope tip. When they adhere to the surface of the camera window or illumination window located on the tip, they can cause blurred images or abnormal illumination.

[0003] In existing technologies, the tip of an endoscope is rinsed during use, but the rinsing fluid, mixed with bodily fluids, still adheres to the tip surface. To address this, a coating can be applied to the imaging window and / or illumination window to alter their hydrophilicity and reduce adhesion. However, endoscopes undergo multiple sterilization and disinfection processes during use, and with each iteration, the surface coating may peel off, making it difficult to effectively solve the problem of fluid adhesion. Utility Model Content

[0004] The purpose of this invention is to provide an optical system for an endoscope, wherein the lens surface exposed on the outside of the endoscope is hydrophobic, which reduces the possibility of liquid adhering to the lens surface during endoscope use and thus affecting illumination or imaging, and avoids the problem of film peeling that is common with existing coating methods. This invention also provides an endoscope.

[0005] To achieve the above objectives, this utility model provides the following technical solution:

[0006] An optical system for an endoscope includes a first lens having a first surface exposed to the exterior of the endoscope. The first surface has a plurality of nanoprotrusions arranged in an array, each nanoprotrusion having a diameter smaller than the minimum operating wavelength of the optical system, such that the first surface is hydrophobic and the first lens has a transmittance of not less than 70% for light within the operating wavelength range of the optical system.

[0007] Optionally, the first surface is a plane.

[0008] Optionally, the optical system is a camera system, the first surface is the object-side surface of the first lens, and the image-side surface of the first lens is a plane or a concave surface;

[0009] or,

[0010] The optical system is an illumination system, the first surface is the light-emitting surface of the first lens, and the light-incident surface of the first lens is either a plane or a convex surface.

[0011] Optionally, the duty cycle of the plurality of nanoprotrusions on the first surface is greater than or equal to 10% and less than or equal to 20%.

[0012] Optionally, the nanoprotrusion includes an upper part and a lower part connected together, the lower part being fixed to the first surface, the upper part being connected to the end of the lower part away from the first surface, and the upper part being wider than the lower part.

[0013] Optionally, the height of the nanoprotrusion is greater than or equal to 150 nm and less than or equal to 300 nm.

[0014] Optionally, both the upper and lower parts are columnar structures, and the average diameter of the upper and lower parts is greater than or equal to 80 nm and less than or equal to 120 nm.

[0015] Optionally, the first lens includes a substrate, the lower part is fixed to the substrate, the difference between the refractive index of the upper part and the refractive index of the lower part is less than or equal to 0.1, the difference between the refractive index of the upper part and the refractive index of the substrate is less than or equal to 0.1, and the difference between the refractive index of the lower part and the refractive index of the substrate is less than or equal to 0.1.

[0016] Optionally, the extinction coefficients of the substrate, the upper part, and the lower part are all 0 within the operating wavelength range.

[0017] An endoscope comprising the optical system of an endoscope as described in any of the preceding claims.

[0018] The optical system of the endoscope provided in this embodiment of the invention features an array of nanoprotrusions on its first surface exposed outside the endoscope. This array provides strong hydrophobicity to the first surface, reducing the adhesion of bodily fluids or rinsing fluids during endoscope use. Simultaneously, by setting the diameter of the nanoprotrusions to be smaller than the minimum operating wavelength of the optical system, the transmittance of the first lens for light within the operating wavelength range is ensured to be no less than 70%, thus maintaining excellent light transmittance. Therefore, the optical system provided in this embodiment of the invention exhibits good hydrophobicity and light transmittance, preventing the endoscope's imaging quality from being reduced due to water or blood contamination of the optical lens. Compared to existing anti-liquid coating methods, it avoids the problem of film peeling and offers better stability and reliability. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A schematic diagram of the optical system of an endoscope provided in an embodiment of the present invention;

[0021] Figure 2 A schematic diagram of the optical system of an endoscope provided in another embodiment of the present invention;

[0022] Figure 3 A model diagram of droplet wetting on an absolutely smooth surface;

[0023] Figure 4-1 This is a diagram of a droplet wetting model on a rough surface described by the Wenzel model.

[0024] Figure 4-2 This is a diagram of a droplet wetting model on a rough surface described by the Cassie model.

[0025] Figure 5 This is a schematic diagram of the structure of multiple nanoprotrusions on the first surface of the optical system of an endoscope according to an embodiment of the present invention.

[0026] The reference numerals in the accompanying drawings include:

[0027] 100-Endoscope, 101-First lens, 102-First surface, 103-Second lens, 104-Nano protrusion, 105-Substrate, 200-Droplet, 201-Surface, 202-Rough surface. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.

[0029] This embodiment provides an optical system for an endoscope, the optical system including a first lens, the first lens having a first surface for being exposed to the outside of the endoscope, the first surface having a plurality of nanoprotrusions arranged in an array, any one of the plurality of nanoprotrusions having a diameter smaller than the minimum operating wavelength of the optical system, so that the first surface is hydrophobic and the first lens has a transmittance of not less than 70% for light within the operating wavelength range of the optical system.

[0030] The optical system of the endoscope in this embodiment features an array of nanoprotrusions on its first surface exposed outside the endoscope. This arrangement gives the first surface strong hydrophobicity, reducing the adhesion of bodily fluids or rinsing fluids during endoscope use. Simultaneously, by setting the diameter of the nanoprotrusions to be smaller than the minimum operating wavelength of the optical system, the transmittance of the first lens for light within the operating wavelength range is ensured to be no less than 70%, thus maintaining excellent light transmittance. Therefore, the optical system of this embodiment exhibits good hydrophobicity and light transmittance, preventing the endoscope's imaging quality from being reduced due to water or blood contamination of the optical lens. Compared to existing anti-liquid coating methods, it avoids the problem of film peeling and offers better stability and reliability.

[0031] The optical system of the endoscope in this embodiment can be an imaging system of the endoscope, and the first surface is the object-side surface of the first lens. Alternatively, the optical system of the endoscope in this embodiment can also be an illumination system of the endoscope, and the first surface is the light-emitting surface of the first lens.

[0032] In some embodiments, the first surface is planar to facilitate the formation of multiple nanoprotrusions arranged in an array on the first surface.

[0033] In some embodiments, the optical system is a camera system, the first surface is the object-side surface of the first lens, and the image-side surface of the first lens is a plane. Object-side light rays do not change their propagation direction when passing through the first lens, and do not converge or diverge. In this embodiment, the first lens can be used as a protective lens for the camera system, disposed on the object side of a conventional imaging lens group. This way, the original imaging optical path of the endoscope camera system is not altered, and the surface of the camera system exposed outside the endoscope is hydrophobic. For example, see [reference needed]. Figure 1 , Figure 1 This is a schematic diagram of the optical system of an endoscope according to one embodiment. The optical system of the endoscope is a camera system, such as... Figure 1As shown, the optical system of the endoscope 100 includes a first lens 101 and a second lens 103. The first surface (i.e., its object-side surface) 102 of the first lens 101 is exposed outside the endoscope 100. The first surface 102 is planar, and the image-side surface of the first lens 101 is also planar. Nanoscale protrusions are provided on the first surface 102. The first lens 101 can serve as a camera window for an imaging system.

[0034] In some embodiments, the optical system is a camera system, the first surface is the object-side surface of a first lens, and the image-side surface of the first lens is concave. If the first surface (i.e., the object-side surface) of the first lens is planar and the image-side surface of the first lens is concave, then the first lens has negative optical power, enabling the camera system to collect large-angle incident light. For example, see [reference needed]. Figure 2 , Figure 2 This is a schematic diagram of the optical system of an endoscope provided in another embodiment. The optical system of the endoscope is a camera system, such as... Figure 2 As shown, the optical system of the endoscope 100 includes a first lens 101. The first surface (i.e., the object-side surface) 102 of the first lens 101 is exposed outside the endoscope 100. The first surface 102 is planar, and the image-side surface of the first lens 101 is concave. In this embodiment, nano-protrusions can be provided on the object-side surface of the first lens 101, which is closest to the object in the original imaging lens group. This achieves the purpose of making the surface of the imaging system exposed outside the endoscope 100 hydrophobic without introducing a new lens.

[0035] In some embodiments, the optical system is an illumination system, the first surface is the light-emitting surface of the first lens, and the light-incident surface of the first lens is planar. Since both the light-incident surface and the first surface (i.e., the light-emitting surface) of the first lens are planar, the propagation direction of the illumination light does not change when it passes through the first lens, and the illumination light does not converge or diverge when it passes through the first lens. In this embodiment, a first lens can be added to the light-emitting side of the original illumination system, without changing the original optical path of the endoscope illumination system, and achieving the purpose of making the surface of the illumination system exposed outside the endoscope hydrophobic. The first lens can serve as the illumination window of the illumination system.

[0036] In some embodiments, the optical system is an illumination system, the first surface is the light-emitting surface of the first lens, and the light-incident surface of the first lens is a convex surface. The first lens can converge and then diverge the illumination light, which helps to improve the divergence angle of the light. In this embodiment, nano-protrusions can be provided on the light-emitting surface of the first lens located on the light-emitting side of the original illumination system. This allows the surface of the illumination system exposed outside the endoscope to be hydrophobic without introducing a new lens.

[0037] The first surface 102 of the first lens 101 can be flush with the distal surface of the endoscope 100, as can be seen from... Figure 2As shown. Alternatively, the first surface 102 of the first lens 101 may also protrude slightly beyond the distal surface of the endoscope 100, as shown in the reference. Figure 1 As shown.

[0038] The first surface 102 of the first lens 101 is provided with an array of nanoprotrusions, which makes the first surface 102 of the first lens 101 hydrophobic, based on the theory of surface wetting properties. Specifically:

[0039] On a perfectly smooth, flat surface, a liquid exhibits a hemispherical shape, and its wetting behavior on the surface can be described using Young's model, such as... Figure 3 As shown, Figure 3 The diagram shows the droplet wetting model on an absolutely smooth surface, using Young's model. Assuming the static contact angle of droplet 200 at equilibrium on surface 201 is θ, the forces acting on it are related to the interfacial tensions at the solid-gas, solid-liquid, and liquid-gas interfaces, with the relevant expressions as follows:

[0040] (1)

[0041] According to the above formula, the larger θ is, the more likely the droplet 200 is to be round on the solid surface 201, and the smaller the wettability of the surface 201.

[0042] However, in reality, perfectly smooth, flat surfaces do not exist; real surfaces have a certain degree of roughness. The state of a droplet in this case can be described by both the Wenzel model and the Cassie model. (See reference...) Figure 4-1 and Figure 4-2 , Figure 4-1 This is a diagram of a droplet wetting model on a rough surface described by the Wenzel model. Figure 4-2 This is a diagram of a droplet wetting model for a rough surface described by the Cassie model.

[0043] In the Wenzel model, it is assumed that droplet 200 completely fills the rough surface 202. The contact between the liquid and the microscopic unevenness of the solid results in an actual contact area that is much larger than the apparent geometric contact area, thus enhancing the hydrophobic properties of the surface. The contact angle θ1 at this point can be expressed as:

[0044] (2)

[0045] R represents the ratio of the actual contact area to the apparent area, and θ represents the contact angle of the droplet on the flat surface. Under normal circumstances, R>1. When θ<90°, the wettability of the liquid on the rough surface 202 increases with the increase of roughness, indicating that if a surface is hydrophilic (contact angle θ<90° in Young's model), increasing the surface roughness will make the material more hydrophilic.

[0046] In the Cassie model, droplet 200 is considered to exist stably at the solid-liquid-gas three-phase interface, and the contact angle θ2 can be expressed as:

[0047] (3)

[0048] Where f represents the proportion of the droplet in contact with air at the solid-liquid surface, and θ represents the contact angle of the droplet on the flat surface.

[0049] Based on the above model, the basic characteristics of a hydrophobic surface can be summarized as follows: the larger the static contact angle of the droplet 200 on the surface, the smaller the sliding angle, and the better the hydrophobic performance. In the field of materials science, a superhydrophobic surface is defined as a surface where the static contact angle of the liquid is >150° and the sliding angle is <10°. In this optical system, by controlling the shape, size, or duty cycle of the nano-protrusions on the first surface 102 of the first lens 101, the mechanical properties of the surface in contact with the liquid can be changed, so that the static contact angle of the liquid on the first surface 102 of the first lens 101 is >150° and the sliding angle is <10°, thus achieving the purpose of hydrophobicity.

[0050] In some embodiments, the duty cycle of the multiple nanoprotrusions on the first surface 102 is greater than or equal to 10% and less than or equal to 20%. According to the Cassie model, the duty cycle of the nanoprotrusions affects the size of f. According to formula (3), as f increases, the static contact angle of the droplet 200 on the surface decreases, and the hydrophobicity of the lens decreases accordingly. Considering manufacturability, lenses with too low a duty cycle are difficult to manufacture, have large manufacturing tolerances, and are highly unstable. Therefore, the duty cycle of the nanoprotrusions on the first surface 102 of the first lens 101 is 10%-20%, so that the first surface 102 of the first lens 101 has both good hydrophobicity and ensures that the nanoprotrusions are easy to manufacture. For example, the duty cycle of the nanoprotrusions on the first surface 102 of the first lens 101 can be 13±2%.

[0051] In this embodiment, the structure of the nanoprotrusions is not limited. In some embodiments, the nanoprotrusions include a connected upper and lower portion, the lower portion being fixed to the first surface, and the upper portion being connected to the end of the lower portion away from the first surface, the upper portion being wider than the lower portion. This structure can be considered a reentrant structure, which exhibits a "wider at the top and narrower at the bottom" or inwardly curved profile (such as a mushroom head shape). This structure creates concave angles between the nanoprotrusions, which is key to achieving hydrophobic properties on the surface. It can trap large air pockets, thereby providing an upward Laplace force that allows droplets 200 to form a stable Cassie state on the surface.

[0052] In some embodiments, the height of the nanoprotrusions is greater than or equal to 150 nm and less than or equal to 300 nm, preferably 220 ± 10 nm. Within the range of 150 nm to 300 nm, the static contact angle of the droplet 200 gradually increases with increasing nanoprotrusion height, by approximately 10%. From a kinetic perspective, at the nanoscale, when the droplet 200 collides with the surface, it tends to hit the bottom between the nanoprotrusions within a very short time. Higher nanoprotrusions provide the droplet 200 with a longer buffer time to stabilize in the Cassie state. However, above 220 nm, due to limitations in processing technology, the nanoprotrusions may exhibit some degree of collapse, thus affecting the hydrophobic properties. Therefore, 220 nm is a more ideal nanoprotrusion height. Furthermore, according to the antireflection principle, if the optical path difference between the reflected light from the upper and lower surfaces of a material is half the wavelength, the energy of these two reflected beams can cancel each other out, i.e., "antireflection and antireflection". The optical system of an endoscope typically operates within the visible light wavelength range (380nm-780nm). The height of the nanoprotrusions is greater than or equal to 150 nanometers and less than or equal to 300 nanometers, which is close to half of the operating wavelength, thus achieving the effect of reducing reflection and increasing light transmission.

[0053] In some embodiments, both the upper and lower portions of the nanoprotrusions have columnar structures; such nanoprotrusions may be referred to as "T"-shaped nanopillars, which are a type of suspended structure, belonging to the category of re-entry structures. Examples can be found in [reference needed]. Figure 5 , Figure 5 This is a schematic diagram of the structure of an endoscope's optical system with multiple nanoprotrusions on its first surface, as shown in the example. Figure 5 As shown, the first lens 101 includes a substrate 105 and nanoprotrusions 104 disposed on the surface of the substrate 105. The substrate 105 forms a lens, and the nanoprotrusions 104 include a columnar upper part and a columnar lower part. In this embodiment, the arrangement of the nanoprotrusions 104 is not limited.

[0054] In some embodiments, the average diameter of the upper and lower portions is greater than or equal to 80 nanometers and less than or equal to 120 nanometers. When the particle size is comparable to or slightly larger than the wavelength of light, it causes more severe scattering. Since the nanoprotrusions 104 in this optical system belong to the subwavelength range, and the average diameter of the T-shaped nanopillars is greater than or equal to 80 nanometers and less than or equal to 120 nanometers, which is smaller than the wavelength of visible light, the scattering of light by the first surface 102 is also relatively small. In other embodiments, the nanoprotrusions can also be reentrant structures of other shapes.

[0055] In some embodiments, the first lens 101 includes a substrate 105, the lower part is fixed to the substrate 105, and the difference between the refractive index of the upper part and the refractive index of the lower part is less than or equal to 0.1. The difference between the refractive index of the upper part and the refractive index of the substrate 105 is less than or equal to 0.1, and the difference between the refractive index of the lower part and the refractive index of the substrate 105 is less than or equal to 0.1. This can reduce the light reflection caused by the nano-protrusions on the first surface 102 of the first lens 101, thereby reducing the influence of the nano-protrusions on the light transmittance of the first lens.

[0056] In some embodiments, the extinction coefficients of both the substrate 105 and the nanoprotrusions 104 are 0 within the operating wavelength range of the optical system. This avoids the loss of transmittance due to light absorption.

[0057] In one specific example, the nanoprotrusions 104 on the first surface of the first lens 101 include a connected columnar upper part and a columnar lower part, forming a "T" shape. The lower part is fixed to the first surface 102 of the first lens 101. The average diameter of the lower and upper parts is 92.7 ± 0.5 nanometers, the relative height of the nanoprotrusions is 220 ± 5 nanometers, and the feature density is 1.94 × 10¹¹ nanoprotrusions / cm². 2 The duty cycle is 13.1%; the extinction coefficients of the substrate 105 and the nanoprotrusions 104 of the first lens 101 are both 0 in the operating wavelength range of the optical system.

[0058] It is understandable that after light passes through a lens, its destination is mainly divided into four parts: transmission, reflection, scattering, and absorption.

[0059] (1) Reflection. Reflection is mainly caused by the abrupt change in refractive index at the material interface. Within the working wavelength range of the optical system, the difference in refractive index between any two of the substrate 105 of the first lens 101, the upper part of the nano-protrusion 104, and the lower part of the nano-protrusion 104 is less than 0.1, which can minimize the resulting light reflection. In addition, according to the anti-reflection principle, if the optical path difference between the light reflected from the upper and lower surfaces of the material is half the wavelength, the energy of the two reflected beams can cancel each other out, i.e., "anti-reflection and anti-reflection". The working wavelength range of the optical system of the endoscope is usually the visible light wavelength range (380nm-780nm). The relative height of the nano-protrusion 104 is 220±5 nanometers, which is close to half of the working wavelength, and can just achieve the effect of anti-reflection and anti-reflection.

[0060] (2) Absorption. The extinction coefficients of the three materials of the substrate 105, the upper part of the nano-protrusion 104 and the lower part of the nano-protrusion 104 of the first lens 101 are all 0 in the working wavelength range. Therefore, the structure will not suffer a loss of transmittance due to light absorption.

[0061] (3) Scattering. According to the Mie scattering theory, when the size of a particle is similar to or slightly larger than the wavelength of light, it will cause more severe scattering. Since the nanoprotrusions in this optical system are in the subwavelength range, the average characteristic diameter of the T-shaped nanopillars is about 100 nanometers, which is smaller than the wavelength of visible light, meaning that the scattering is also relatively small.

[0062] Therefore, in this specific example, the first surface of the optical system not only achieves excellent hydrophobicity, preventing the endoscope's imaging quality from being reduced due to water or blood contamination of the optical lens, but also has a more stable surface structure compared to traditional coating technologies, it can also achieve a transmittance of over 95% within the endoscope's operating wavelength range.

[0063] Furthermore, the nano-protrusions on the first surface can be processed to smaller sizes, making them more suitable for imaging or illumination optical paths in small-diameter endoscopes.

[0064] This embodiment also provides an endoscope, including the optical system of the endoscope described in any of the above embodiments.

[0065] The endoscope of this embodiment features an array of nanoprotrusions on its first surface exposed outside the endoscope, giving the surface strong hydrophobicity and reducing the adhesion of bodily fluids or rinsing fluids during use. Simultaneously, by setting the diameter of the nanoprotrusions to be smaller than the minimum operating wavelength of the optical system, the transmittance of the first lens for light within the operating wavelength range is ensured to be no less than 70%. Therefore, the endoscope provided in this embodiment exhibits excellent hydrophobicity and light transmittance, preventing the endoscope's imaging quality from being reduced due to water or blood contamination of the optical lens. Compared to existing anti-liquid coating methods, it avoids the problem of film peeling and offers better stability and reliability.

[0066] The present invention provides a detailed description of an endoscope and its optical system. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of these embodiments are merely for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. An optical system for an endoscope, the optical system comprising a first lens, characterized in that, The first lens has a first surface exposed to the outside of the endoscope, and a plurality of nanoprotrusions are formed on the first surface in an array, any one of which has a diameter smaller than the minimum operating wavelength of the optical system, so that the first surface is hydrophobic and the first lens has a transmittance of not less than 70% for light within the operating wavelength range of the optical system.

2. The optical system of the endoscope according to claim 1, characterized in that, The first surface is a plane.

3. The optical system of the endoscope according to claim 2, characterized in that, The optical system is a camera system, the first surface is the object-side surface of the first lens, and the image-side surface of the first lens is either a plane or a concave surface; or, The optical system is an illumination system, the first surface is the light-emitting surface of the first lens, and the light-incident surface of the first lens is either a plane or a convex surface.

4. The optical system of the endoscope according to claim 1, characterized in that, The duty cycle of the plurality of nanoprotrusions on the first surface is greater than or equal to 10% and less than or equal to 20%.

5. The optical system of the endoscope according to any one of claims 1-4, characterized in that, The nanoprotrusion includes an upper part and a lower part connected together. The lower part is fixed to the first surface, and the upper part is connected to the end of the lower part away from the first surface. The upper part is wider than the lower part.

6. The optical system of the endoscope according to claim 5, characterized in that, The height of the nanoprotrusions is greater than or equal to 150 nm and less than or equal to 300 nm.

7. The optical system of the endoscope according to claim 5, characterized in that, Both the upper and lower parts have columnar structures, and the average diameter of the upper and lower parts is greater than or equal to 80 nm and less than or equal to 120 nm.

8. The optical system of the endoscope according to claim 5, characterized in that, The first lens includes a substrate, the lower part is fixed to the substrate, the difference between the refractive index of the upper part and the refractive index of the lower part is less than or equal to 0.1, the difference between the refractive index of the upper part and the refractive index of the substrate is less than or equal to 0.1, and the difference between the refractive index of the lower part and the refractive index of the substrate is less than or equal to 0.

1.

9. The optical system of the endoscope according to claim 8, characterized in that, The extinction coefficients of the substrate, the upper part, and the lower part are all 0 within the operating wavelength range.

10. An endoscope, characterized in that, The optical system of the endoscope as described in any one of claims 1 to 9.

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