Imaging module of optical endoscope, optical endoscope and optical endoscope system

Abstract

The invention provides an imaging module of an optical endoscope, the optical endoscope and an optical endoscope system.The imaging module of the optical endoscope comprises first glass, an imaging lens set, a first optical filter, a target optical element and a first photosensitive element which are arranged from the object side to the image side along the optical axis, and the first optical filter comprises second glass and a filter film; the image surface of the first glass is plated with an antireflection film; the first glass and the first optical filter are obliquely arranged relative to the optical axis; the inclination directions of the first optical filter and the first glass are opposite; light rays entering the imaging module from the object side comprise first light rays and second light rays, and the first light rays are imaged on the imaging surface of the target photosensitive element after passing through the first glass, the imaging lens group, the first optical filter and the target optical element; and the second light passes through the first glass and the imaging lens group, then irradiates the first optical filter, is reflected by the first optical filter and the first glass at least once, and then irradiates the area outside the imaging surface of the target photosensitive element.

Description

Technical Field

[0001] This application relates to the field of optical endoscope imaging technology, and in particular to an imaging module, an optical endoscope, and an optical endoscope system. Background Technology

[0002] An optical endoscope is a medical device that uses optical imaging technology to observe internal tissues or cavities of the human body. It is widely used in minimally invasive surgery, diagnosis, and treatment. The imaging module of an optical endoscope is typically used to transmit the detected image to a detector for imaging, and is commonly used in modern minimally invasive surgery as well as in gastrointestinal examinations and treatments.

[0003] To enable precise diagnosis of lesions, existing optical endoscopes typically employ dual-path imaging, allowing for the capture of light at different wavelengths. This facilitates better identification of lesions by doctors and improves diagnostic efficiency.

[0004] In the imaging module of optical endoscopes in related technologies, when light passes through the imaging lens group and forms an image on the photosensitive element, stray light and ghost images will appear on the imaging surface, resulting in poor imaging of the imaging module. Summary of the Invention

[0005] The embodiments of this application provide an imaging module for an optical endoscope, an optical endoscope, and an optical endoscope system to solve the problem of stray light and ghosting in the imaging surface of the imaging module of an optical endoscope in the related art when the photosensitive element is used.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0007] In a first aspect, embodiments of this application provide an imaging module for an optical endoscope, comprising a first glass, an imaging lens group, a first filter, a target optical element, and a target photosensitive element arranged along an optical axis from the object side to the image side. The first filter includes a second glass and a filter film, the filter film being disposed on at least one of the object plane and the image plane of the second glass; the image plane of the first glass is coated with an anti-reflection film; the first glass is inclined relative to the optical axis, and the acute angle formed between the first glass and the optical axis is a first included angle; the first filter is inclined relative to the optical axis, and the first filter and the optical axis are arranged in a manner that is perpendicular to each other. The acute angle formed between the axes is the second included angle, and the tilt direction of the first filter is opposite to that of the first glass. The light rays entering the imaging module from the object side include a first light ray and a second light ray. The first light ray passes through the first glass, the imaging lens group, the first filter, and the target optical element, and forms an image on the imaging surface of the target photosensitive element. The second light ray passes through the first glass and the imaging lens group, illuminates the first filter, and after being reflected at least once by the first filter and the first glass, illuminates the area outside the imaging surface of the target photosensitive element.

[0008] In some implementations, the optical axis includes a straight first optical axis from the first glass to the first filter; the target photosensitive element includes a first photosensitive element not located on the first optical axis, the target optical element includes a reflective surface for transmitting light to the imaging surface of the first photosensitive element; the intersection of the extension line of the reflective surface and the extension line of the first filter is located on a different side of the first optical axis from the first photosensitive element.

[0009] In some implementations, the target photosensitive element further includes a second photosensitive element located on the first optical axis. The target optical element is used to transmit a portion of the first light rays to the imaging surface of the first photosensitive element and to transmit a portion of the first light rays to the imaging surface of the second photosensitive element.

[0010] In some implementations, the acute angle formed between the first glass and the first optical axis is the first included angle, and the acute angle formed between the first filter and the first optical axis is the second included angle, wherein the first included angle is smaller than the second included angle.

[0011] In some implementations, the first included angle is less than or equal to 80°, and the second included angle is less than or equal to 85°.

[0012] In some implementations, the first ray accounts for at least 70% of the total amount of light entering the imaging module from the object side.

[0013] In some implementations, the imaging lens group includes a plurality of lenses, at least one of the object plane and the image plane of the lenses being coated with the antireflective coating.

[0014] In some implementations, the imaging lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged along the first optical axis from the object side to the image side, wherein the optical power of the first lens is positive.

[0015] In some implementations, the seventh lens is a meniscus lens, and both the object plane and the image plane of the seventh lens bulge towards the object side at the first optical axis.

[0016] In some implementations, the fourth lens and the fifth lens form a cemented lens.

[0017] In some implementations, the second lens has a positive optical power, the third lens has a negative optical power, the fourth lens has a negative optical power, the fifth lens has a negative optical power, and the sixth lens has a positive optical power; and / or, the cemented lens has a negative optical power.

[0018] In some implementations, an aperture stop is also included, which is located on the object side of the first glass; the imaging lens group as a whole can move along the first optical axis to achieve focusing; the focal length of the imaging lens group is 26mm-29mm, and the distance between the first glass and the first filter in the direction parallel to the first optical axis is 34mm-37mm.

[0019] In some implementations, the orthographic projection of the first glass on the first plane lies within the orthographic projection of the imaging lens group on the first plane, and the first plane is a plane perpendicular to the first optical axis; and / or, the orthographic projection of the first filter on the first plane lies within the orthographic projection of the imaging lens group on the first plane, and the first plane is a plane perpendicular to the first optical axis.

[0020] In some implementations, the aperture of the imaging module is 10mm-12mm.

[0021] In some implementations, the target optical element is a beam splitter prism, which includes two right-angle prisms whose inclined surfaces are joined to form a reflective surface; or, the target optical element is a reflective sheet, with the side of the reflective sheet closest to the object being the reflective surface, and the reflective sheet, the first optical axis, and the second optical axis intersecting each other.

[0022] In some implementations, a second filter is also included, which is located between the target optical element and the first photosensitive element, and the filtering band of the second filter is different from that of the filter film.

[0023] Secondly, embodiments of this application also provide an optical endoscope, including the imaging module described in the first aspect above.

[0024] Thirdly, embodiments of this application also provide an optical endoscope system, including a light source host, an image processing device, and the optical endoscope described in the second aspect above.

[0025] The beneficial effects of the imaging module provided in this application embodiment are as follows: By setting a first glass inclined relative to the optical axis on the object side of the imaging lens group, and coating an anti-reflection film on the image surface of the first glass, the first glass can not only protect the imaging lens group but also improve its transmittance. Furthermore, it can form a reflective surface on the first glass. When light rays from the image side to the object side, such as stray light, irradiate the first glass, the first glass can reflect the light rays from the image side to the object side, which is beneficial for directing the stray light to areas outside the imaging surface of the target photosensitive element. When the first ray in the light rays from the object side to the image side, i.e., the imaging ray, passes sequentially along the optical axis through the first glass, the imaging lens group, the first filter, and the target optical element, it forms an image on the imaging surface of the target photosensitive element. This achieves clear imaging on the imaging surface of the target photosensitive element. Simultaneously, both the first glass and the first filter are inclined relative to the first optical axis, and the first filter and the first... The tilt directions of the two glass elements are opposite, meaning that the first filter and the first glass are in a figure-eight or inverted figure-eight shape relative to the optical axis. Thus, when the second light ray, i.e., the non-imaging light ray, shines on the first filter after passing through the first glass and the imaging lens group, the second light ray can be reflected between the first filter and the first glass. By reasonably adjusting the first angle and the second angle between the first glass and the first filter relative to the optical axis, the second light ray, such as stray light, is deflected after being reflected by the first filter and the first glass, thereby reflecting the second light ray to an area outside the imaging surface of the target photosensitive element. In other words, it reduces the imaging of stray light on the target photosensitive element and reduces the impact of the second light ray on the imaging quality of the target photosensitive element. When the second light ray is stray light or other non-imaging light, it reduces the probability of stray light and ghost images appearing on the imaging surface of the target photosensitive element, thereby indirectly improving the imaging quality of the imaging module. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application 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 application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1This is a schematic diagram of the structure of an optical endoscope including one optical path in some embodiments of this application;

[0028] Figure 2 This is a schematic diagram of the structure of an optical endoscope including one optical path in some other embodiments of this application;

[0029] Figure 3 This is a schematic diagram of the imaging module of an optical endoscope including two optical paths in some embodiments of this application;

[0030] Figure 4 This is a schematic diagram of the imaging module of an optical endoscope including two optical paths in some other embodiments of this application;

[0031] Figure 5 for Figure 2 MFT diagram of the imaging module of the optical endoscope in the image;

[0032] Figure 6 for Figure 2 Field curvature diagram of the imaging module of the optical endoscope in the image;

[0033] Figure 7 for Figure 2 The distortion diagram of the imaging module of the optical endoscope.

[0034] The following are the labeling elements in the figure:

[0035] First lens L1; Second lens L2; ​​Third lens L3; Fourth lens L4; Fifth lens L5; Sixth lens L6; Seventh lens L7; Aperture STO; First glass L11; First filter L12; Target optical element S1; Reflective surface S10; Right angle prism S11; Second filter S2; First photosensitive element M1; Second photosensitive element M2; First protective film L21; Second protective film L22. Detailed Implementation

[0036] For ease of understanding, the English abbreviations and related technical terms used in the embodiments of this application will be explained and described below.

[0037] Focal power is equal to the difference between the convergence of the image-side beam and the convergence of the object-side beam; it characterizes the ability of an optical lens to deflect light.

[0038] A lens or lens group with positive optical power, having a positive focal length, and having the effect of converging light.

[0039] A lens or lens group with negative optical power has a negative focal length and has the effect of diverging light.

[0040] Focal length, also known as focal length, is a measure of how well light converges or diverges in an optical lens. It refers to the perpendicular distance from the optical center of a lens or lens group to the focal plane when a distant object is focused into a clear image. For prime lenses, the position of their optical center remains constant; for telephoto lenses, changes in the optical center result in changes in the focal length.

[0041] The effective focal length (EFL) of a lens refers to the distance from the center of the lens to the focal point.

[0042] The combined focal length is the combination of the focal lengths of the individual lenses in a lens group.

[0043] The object plane is defined by the lens; the side where the object is located is called the object side, and the surface of the lens closest to the object side is called the object plane.

[0044] The image plane is the side of the lens from which the image of the object is located. The surface of the lens closest to the image side is called the image plane.

[0045] An aperture stop is a device used to control the amount of light passing through the lens and entering the sensor inside the camera body; it is usually located inside the lens.

[0046] The imaging plane is located on the image side of all lenses in an optical lens, and is the surface on which light rays pass through each lens in the optical lens in sequence to form an image.

[0047] The optical axis is a vertical axis that passes through the center of a lens. The lens optical axis is the axis that passes through the centers of each lens in the lens.

[0048] The focal point is the point where parallel light rays converge after being refracted by a lens or lens group.

[0049] Aberrations: Optical lenses have the properties of an ideal optical system at the optical axis, where near-axis rays emitted from a point on an object intersect the image plane at a point (i.e., the optical axis image point). However, in reality, rays passing through different apertures of the lens rarely intersect perfectly at a single point, but rather deviate from the position of the near-axis image point. These differences are collectively referred to as aberrations.

[0050] Field curvature, also known as "image field curvature," occurs when a lens exhibits field curvature. The intersection of the entire beam does not coincide with the ideal image point. Although a clear image point can be obtained at each specific point, the entire image plane is a curved surface.

[0051] Distortion, also known as image distortion, refers to the degree of distortion in the image formed by an optical lens relative to the object itself. Distortion is caused by the spherical aberration of the aperture. The height of the intersection point between the principal ray and the Gaussian image plane after passing through the optical lens in different fields of view is not equal to the ideal image height; the difference between the two is the distortion.

[0052] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0053] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more, unless otherwise explicitly specified.

[0054] An optical endoscope is a medical device that uses optical imaging technology to observe internal tissues or cavities of the human body. It is widely used in minimally invasive surgery, diagnosis, and treatment. The imaging module of an optical endoscope is typically used to transmit the detected image to a detector for imaging, and is commonly used in modern minimally invasive surgery as well as in gastrointestinal examinations and treatments.

[0055] To enable precise diagnosis of lesions, existing optical endoscopes typically employ dual-path imaging, allowing for the capture of light at different wavelengths. This facilitates better identification of lesions by doctors and improves diagnostic efficiency.

[0056] The light sources for the aforementioned fluorescence imaging typically use broadband light sources (such as mercury lamps or LEDs) or lasers of specific wavelengths to excite fluorophores. In optical endoscopes that can achieve visible light and fluorescence imaging, the light source usually used is a laser of a specific wavelength to excite fluorophores.

[0057] In related technologies, imaging modules typically use lasers of this wavelength as the light source for the imaging module in optical endoscopes. To improve brightness, anti-reflective coatings are usually applied to the surfaces of the lenses and protective glass in the imaging lens group. However, while this increases the brightness of the light on the imaging surface of the photosensitive element in the imaging module, some non-imaging light, such as stray light, enters the optical path and forms an image on the imaging surface of the photosensitive element due to reflections between the lenses and protective glass or between the lenses. As a result, when the light passes through the imaging lens group and forms an image on the photosensitive element, the imaging surface will have stray light and ghosting, leading to poor imaging of the imaging module.

[0058] To address the aforementioned problems, embodiments of this application provide an imaging module for an optical endoscope, an optical endoscope, and an optical endoscope system. The imaging module can be single-path; that is, in some embodiments, the imaging module includes an optical path consisting of a first optical axis, a second optical axis, and a first photosensitive element M1. A first light ray is sequentially transmitted along the first optical axis to the target optical element S1, and then along the second optical axis to the first photosensitive element M1, forming an image on the imaging surface of the first photosensitive element M1. Figure 1 As shown. Alternatively, in some other embodiments, the imaging module includes an optical path consisting of a first optical axis and a second photosensitive element M2. The first light ray is transmitted sequentially along the direction of the first optical axis to the target optical element S1, and then, after passing through the target optical element S1, forms an image on the imaging surface of the second photosensitive element M2, as shown. Figure 2 As shown.

[0059] The imaging module can also be dual-path, that is, including but not limited to two mutually perpendicular optical paths. The structure of the imaging module is as follows: Figure 3 and Figure 4 In other words, the first ray can be split into a first sub-optical path and a second sub-optical path after passing through the target optical element S1. The first sub-optical path may include, but is not limited to, a path parallel to the first optical axis. The optical axis of the first sub-optical path is parallel to the first optical axis. The first ray forms an image on the imaging surface of the second photosensitive element M2. The optical path is as follows: Figure 2 As shown. The optical axis of the second sub-optical path includes a portion parallel to the first optical axis and a portion parallel to the second optical axis. The first ray forms an image on the imaging surface of the first photosensitive element M1, and the optical path is as follows. Figure 1 As shown. The imaging module of this optical endoscope can perform imaging in both visible and fluorescence bands, but is not limited to this. In other words, the imaging module of this optical endoscope can produce clear images in the range of 400nm to 900nm.

[0060] The imaging module described above works as follows: light reflected from the subject passes through an optical lens to generate an optical image, which is then projected onto the imaging surface of a photosensitive element. This photosensitive element converts the optical image into an electrical signal, i.e., an analog image signal, and transmits it to a processor. The photosensitive element (also called an image sensor) is a semiconductor chip containing hundreds of thousands to millions of photodiodes on its surface. When illuminated by light, these photodiodes generate electrical charges. The photosensitive element can be a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) device. A CCD is made of a highly sensitive semiconductor material that converts light into electrical charges. A charge-coupled device consists of many photosensitive units, typically measured in megapixels. When the surface of the photosensitive element is illuminated by light, each photosensitive unit reflects a charge onto the component. The signals generated by all the photosensitive units are added together to form a complete image. The target photosensitive element refers to a specific photosensitive element used for imaging. In the embodiments of this application, the target photosensitive element may include only the first photosensitive element M1, or the target photosensitive element may include only the second photosensitive element M2; or the target photosensitive element may include the first photosensitive element M1 and the second photosensitive element M2.

[0061] The imaging module mainly utilizes the refraction principle of the lenses in the imaging lens group to form an image. That is, the light from the scene passes through the imaging lens group to form a clear image on the focal plane, and the image of the scene is recorded by the photosensitive element located on the focal plane.

[0062] The aforementioned imaging module can be used in electronic devices with camera and image capture capabilities, such as optical endoscopes. Of course, besides optical endoscopes with imaging capabilities, these electronic devices can also be other electronic devices with imaging capabilities. The following explanation uses the application of the imaging module in an optical endoscope as an example, but it is not limited to this application.

[0063] Figure 1 A structural diagram of the imaging module of an optical endoscope, including only the optical path, is shown. Figure 1 As shown, the imaging module of this optical endoscope includes: a first glass L11 arranged along the optical axis from the object side to the image side, an imaging lens group, a first filter L12, a target optical element S1, and a target photosensitive element. The straight portion of the optical axis from the first glass L11 to the first filter L12 is called the first optical axis. Figure 1The vertical dotted line in the middle), that is, the optical axis includes the first optical axis, the target photosensitive element may only include the first photosensitive element M1, the first photosensitive element M1 is not located on the first optical axis, the first filter L12 includes a second glass and a filter film (not shown in the figure), the filter film is disposed on at least one of the object plane and the image plane of the second glass; the image plane of the first glass L11 is coated with an anti-reflection film; the first glass L11 is inclined relative to the first optical axis, and the acute angle formed between the first glass L11 and the first optical axis is the first included angle; the first filter L12 is inclined relative to the first optical axis, and the acute angle formed between the first filter L12 and the first optical axis is the second included angle, the inclination direction of the first filter L12 is opposite to that of the first glass L11, that is, the first A glass L11 and a first filter L12 are arranged in a figure-eight or inverted figure-eight shape relative to the optical axis. The light rays entering the imaging module from the object side include a first light ray and a second light ray. The first light ray passes through the first glass L11, the imaging lens group, the first filter L12 and the target optical element S1, and forms an image on the imaging surface of the target photosensitive element. The second light ray passes through the first glass L11 and the imaging lens group, illuminates the first filter L12, and is reflected at least once by the first filter L12 and the first glass L11. That is, after illuminating the first filter L12, it is reflected by the first filter L12 and then illuminates the first glass L11. After being reflected by the first glass L11, it illuminates the area outside the imaging surface of the target photosensitive element.

[0064] The imaging lens group in the aforementioned imaging module is used for imaging, and this imaging lens group includes multiple lenses. In this embodiment, the imaging lens group may include, but is not limited to, seven lenses. The structure of this imaging lens group is detailed in the following description.

[0065] The image plane of the first glass L11 is coated with an anti-reflective film. That is, only the image plane of the first glass L11 is coated with an anti-reflective film, and the object plane of the first glass is not treated. In this way, the first glass L11 can protect the imaging lens group while also forming a reflective surface, so that the first glass L11 can reflect light from the image side to the object side.

[0066] The aforementioned first filter L12, by employing a structure where the filter is disposed on the second glass, not only improves the strength of the first filter L12 but also facilitates its assembly and position adjustment. Furthermore, the filtering band of the first filter L12 can be changed by altering the filter film with minimal modification. Simultaneously, the first filter L12 serves as another reflective surface. In this embodiment, the number of filter films can be one, i.e., a filter is disposed only on the object plane or image plane of the second glass; alternatively, the number of filter films can be two, i.e., filters are disposed on both the object plane and image plane of the second glass. No specific limitation is made here.

[0067] The first glass L11 is tilted relative to the first optical axis, and the first filter L12 is tilted relative to the first optical axis. The tilt direction of the first filter L12 is opposite to that of the first glass L11. In this way, when the second light shines on the first filter L12, it helps to reduce the number of reflections of the second light from the area outside the imaging surface of the target photosensitive element between the first filter L12 and the first glass L11. This reduces the probability of the second light entering the imaging surface of the target photosensitive element, thereby indirectly improving the imaging quality on the imaging surface of the target photosensitive element.

[0068] The aforementioned first ray typically refers to the ray that illuminates the imaging surface of the target photosensitive element for imaging out of the total amount of light entering the imaging module from the object side. This portion of the ray typically includes at least 70% of the total amount of light entering the imaging module from the object side, thereby ensuring clear imaging on the imaging surface of the target photosensitive element.

[0069] The second ray refers to the ray that illuminates the area outside the imaging surface of the target photosensitive element out of the total amount of light entering the imaging module from the object side. This second ray can refer to the stray light, which is less than 30% of the total amount of light entering the imaging module from the object side (excluding the 70%), or it can refer to the stray light within the first ray. Typically, stray light accounts for 1% or even less than 1% of the total amount of light entering the imaging module from the object side. That is, in related technologies, this stray light is the portion that produces ghost points or ghost images in the imaging surface. This portion of stray light typically accounts for 0.8%, ... 0.6%, 0.5%, ... 0.1%, 0.08%, ... 0.05%, ... of the total amount of light entering the imaging module from the object side.

[0070] A first glass L11, tilted relative to the first optical axis, is disposed on the object side of the imaging lens group. An anti-reflective coating is applied only to the image surface of the first glass L11. This allows the first glass L11 to protect the imaging lens group while simultaneously improving its transmittance. Furthermore, it forms a reflective surface, allowing light from the image side to the object side, such as stray light, to reflect off the first glass L11, thus facilitating the removal of stray light from the image surface of the target photosensitive element. When the first ray of light from the object side to the image side, i.e., the imaging ray, passes sequentially along the first optical axis through the first glass L11, the first filter L12 of the imaging lens group, and the target optical element S1, it forms an image on the image surface of the target imaging element, i.e., the first photosensitive element M1. This ensures a clear image on the image surface of the target photosensitive element, achieving clear imaging on the target photosensitive element's image surface. Simultaneously, both the first glass L11 and the first filter L12 are tilted relative to the first optical axis. The first filter L12 and the first glass L11 are tilted in opposite directions. That is, the first filter L12 and the first glass L11 are in a figure-eight or inverted figure-eight shape. In this way, when the second light ray, i.e. the non-imaging light ray, shines on the first filter L12 after passing through the first glass L11 and the imaging lens group along the first optical axis, the second light ray can be reflected by the first filter L12 and the first glass L11. By reasonably adjusting the first angle and the second angle between the first glass L11 and the first filter L12 relative to the first optical axis, the second light ray, such as stray light, is deflected after being reflected by the first filter L12 and the first glass L11, thereby reflecting the second light ray to an area outside the imaging surface of the target photosensitive element. In other words, the entry of stray light into the optical path and its imaging on the target photosensitive element is reduced, the influence of the second light ray on the imaging surface of the target photosensitive element is reduced, and the probability of ghost points and ghost images appearing on the imaging surface of the target photosensitive element is reduced, thereby indirectly improving the imaging quality of the imaging module of the optical endoscope.

[0071] It should be noted that since the emission wavelength of fluorescence typically falls within the visible light or near-infrared band of 400nm to 900nm, the wavelength of the light source in the embodiments of this application can be, but is not limited to, a laser with a wavelength of 400nm to 900nm. By changing the light source, the imaging module can be used for visible light imaging alone, or it can be used for fluorescence imaging alone.

[0072] like Figure 1 As shown, in some embodiments of an imaging module that includes one path, the optical axis also includes a second optical axis that is linearly oriented from the first filter L12 to the first photosensitive element M1. Figure 1(The horizontal dotted line in the middle) indicates that the first photosensitive element M1 is located on the second optical axis. The target optical element S1 includes a reflective surface S10, which is used to transmit the first light to the imaging surface of the first photosensitive element M1. The intersection of the extension line of the reflective surface S10 and the extension line of the first filter L12 is located on a different side of the first optical axis from the first photosensitive element M1.

[0073] The reflective surface S10 may, but is not limited to, transmit the first light to the first photosensitive element M1 by reflection alone. The intersection of the extension line of the reflective surface S10 and the extension line of the first filter L12 may, but is not limited to, be located on a different side of the first photosensitive element M1 opposite to the first optical axis.

[0074] The second optical axis and the first optical axis mentioned above may be, but are not limited to, perpendicular to each other, and the angle between the reflecting surface S10 and the first optical axis may be, but is not limited to, 45°. The following explanation uses the example of the second optical axis and the first optical axis being perpendicular to each other.

[0075] It should be noted that the aforementioned target optical element S1 can be a reflective sheet, with the side of the reflective sheet closest to the object being the reflecting surface S10, and the angle between the reflective sheet and the first optical axis being 45°. Of course, the target optical element S1 can also include two right-angle prisms S11, with the inclined surfaces of the two right-angle prisms S11 fitting together to form the reflecting surface S10.

[0076] like Figure 1 As shown, in this embodiment, the imaging module further includes a second filter S2, which is located between the target optical element S1 and the first photosensitive element M1. The filtering band of the second filter S2 is different from that of the filter film.

[0077] By employing the above configuration, different combinations of the first filter L12 and the second filter S2 in the optical path can achieve the filtering effect on different wavelengths, thereby meeting the imaging requirements of different scenarios and improving the versatility of the imaging module. In other words, the structure of this imaging module can be used for imaging light of different wavelengths.

[0078] like Figure 1 As shown, in some embodiments, the object surface of the first photosensitive element M1 is further provided with a first protective sheet L21. In this way, the first protective sheet L21 can not only support the first photosensitive element M1, but also effectively protect the first photosensitive element M1, thereby further improving the imaging quality of the imaging surface of the first photosensitive element M1.

[0079] like Figure 2As shown, in some other embodiments of the imaging module that includes one path, the optical axis includes only the first optical axis, and the target photosensitive element may include only the second photosensitive element M2, which is located on the first optical axis. In this way, the first light ray passes sequentially along the first optical axis through the first glass L11, the imaging lens group, the first filter L12, and the target optical element S1, and then forms an image on the imaging surface of the second photosensitive element M2.

[0080] It should be noted that, in this embodiment, the target optical element S1 is used to allow the first light to pass through and form an image on the imaging surface of the second photosensitive element M2. The target optical element S1 may be, but is not limited to, a prism.

[0081] like Figure 2 As shown, in this embodiment, the imaging module also includes an aperture stop STO, which is located on the object side of the first glass L11.

[0082] By setting the aperture stop STO on the object side of the first glass L11, that is, the pupil of the imaging module of the optical endoscope is located on the first surface, and at the same time, it is convenient to connect with the pupil of the exit pupil of the eyepiece in the optical endoscope. This helps to increase the diameter of the entrance pupil, thereby improving the imaging quality.

[0083] like Figure 2 As shown, in this embodiment, the object surface of the second photosensitive element M2 is further provided with a second protective sheet L22. In this way, the second protective sheet L22 can not only support the second photosensitive element M2, but also effectively protect the first photosensitive element M1, thereby further improving the imaging quality of the imaging surface of the first photosensitive element M1.

[0084] In the design of the imaging module, the distance between the first glass L11 and the first filter L12 in the direction parallel to the first optical axis is related to the focal length and aperture of the imaging module. Specifically, in this embodiment, the apertures of the imaging lens group are interrelated and mutually influential. Additionally, there are the angle values ​​of the first included angle between the first glass L11 and the first optical axis, and the angle values ​​of the first included angle between the first filter L12 and the first optical axis.

[0085] In this embodiment, the orthographic projection of the first glass L11 onto the first plane lies within the orthographic projection of the imaging lens group onto the first plane; the orthographic projection of the first filter L12 onto the first plane lies within the orthographic projection of the imaging lens group onto the first plane, and the first plane is a plane perpendicular to the first optical axis. That is to say, in this embodiment, the aperture of the imaging lens group is the largest, that is, the maximum diameter of the imaging lens group on the plane perpendicular to the first optical axis is the largest, which facilitates the assembly and fixation of the imaging module.

[0086] Of course, the orthographic projection of the first glass L11 on the first plane lies within the orthographic projection of the imaging lens group on the first plane, and the orthographic projection of the first filter L12 on the first plane lies outside the orthographic projection of the imaging lens group on the first plane; or, the orthographic projection of the first glass L11 on the first plane lies outside the orthographic projection of the imaging lens group on the first plane, and the orthographic projection of the first filter L12 on the first plane lies within the orthographic projection of the imaging lens group on the first plane. No specific limitations are made here.

[0087] It should be noted that the imaging lens group structure is the same regardless of whether the imaging module in this application embodiment includes only one or two channels. During the design of the imaging module, the imaging lens group can be moved as a whole along the first optical axis to achieve focusing. This ensures that the overall focal length of the imaging module does not change during focusing, thus maintaining the field of view during imaging, which improves image quality. Furthermore, the imaging lens group can be fixed together during installation, improving focusing efficiency and simplifying the installation and driving structure of the imaging module, thereby reducing costs.

[0088] The structure of the imaging lens group will be described in detail below.

[0089] like Figure 2 As shown, the imaging lens group includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7 arranged along the first optical axis from the object side to the image side. The optical power of the first lens L1 is positive.

[0090] By designing the optical power of the first lens L1 to be positive, the first lens L1 plays the role of bending light rays, reducing the height of light rays and the aperture of the imaging lens group, which is conducive to miniaturizing the aperture of the imaging module.

[0091] It should be noted that all lenses in the aforementioned imaging lens group have anti-reflective coatings on their surfaces, which improves the overall transmittance of the imaging lens group and thus enhances the transmittance of imaging light. Furthermore, the number of lenses in the aforementioned imaging module can be 7, 5, 6, 8, 9, 10, etc., depending on actual needs.

[0092] In the design of the imaging module, the angle value of the first included angle between the first glass L11 and the first optical axis and the angle value of the second included angle between the first filter L12 and the first optical axis are determined.

[0093] In the design of the imaging module, the first and second included angles are also related to and influence each other with the distance between the first glass L11 and the first filter L12 in the direction parallel to the first optical axis, as well as the focal length and aperture of the imaging module. In this embodiment, the first included angle is smaller than the second included angle. This helps to reduce the number of reflections of the first light ray between the first glass L11 and the first filter L12, thereby further reducing the probability of the second light ray entering the optical path. After multiple experiments, it was found that when the first included angle is less than or equal to 80° and the second included angle is less than or equal to 85°, the imaging module achieves high imaging quality without ghosting or ghosting points.

[0094] As an optional embodiment of this application, based on Embodiment 1, the structure of the imaging module is as follows: Figure 2 As shown, the parameter values ​​of each lens and other component in this imaging module can be found in Table 1.

[0095] Table 1

[0096] Surface name radius of curvature / mm Thickness / mm Page 1 STO Infinity 5 Page 2 L11 Infinity 1 Page 3 Infinity 2.5 Page 4 L1 12.4 2.7 Page 5 -53.8 0.14 Page 6 L2 14.33 1.7 Page 7 18 0.7 8 L3 -80.6 2 9 7.6 2.65 10 L4 -7.7 1.4 Page 11 L5 15.6 3.46 12 -9.66 0.13 Page 13 L6 22.4 3.4 Page 14 -22.5 0.14 15 L7 31 3.5 Page 16 31 9 Page 17 L12 Infinity 1.2 18 Infinity 1.25 19 S1 Infinity 10 20 Infinity 2.77 Page 21 L22 Infinity 0.9 22 Infinity 0.53 Page 23 M2 Infinity

[0097] like Figure 2 In this embodiment, the optical power of the second lens L2 is positive, the optical power of the third lens L3 is negative, the optical power of the fourth lens L4 is negative, the optical power of the fifth lens L5 is negative, the optical power of the sixth lens L6 is positive, and the optical power of the seventh lens L7 is positive.

[0098] The aforementioned fourth lens L4 and fifth lens L5 may be, but are not limited to, cemented lenses, and the optical power of the cemented lens may be, but is not limited to, negative optical power.

[0099] By rationally allocating the optical power of the seven lenses, aberrations can be balanced. Furthermore, this arrangement allows the imaging lens group to form a symmetrical structure similar to a double Gaussian lens. In this embodiment, the shape of the seventh lens L7 is also crucial. Specifically, the seventh lens L7 is a meniscus lens, with both its object and image planes bulging towards the object side at the first optical axis. This causes light to diverge when it strikes the image plane of the seventh lens L7 from the image side, reducing stray light entering the first optical axis and thus minimizing the reduction in image quality on the target sensor's imaging surface, indirectly improving the overall image quality.

[0100] In this embodiment, the seventh lens L7 may be, but is not limited to, a positive meniscus lens, and the optical power of the seventh lens L7 is close to infinity.

[0101] The aforementioned positive meniscus lens can be used as a weak converging lens to fine-tune the convergence state of the light beam in the optical path. It can be combined with a cemented lens with negative optical power in the imaging lens group to adjust the beam diameter. The seventh lens, L7, can correct field curvature and astigmatism, thereby improving image quality.

[0102] By employing a positive meniscus lens for the seventh lens L7, the combination of the seventh lens L7 with the fourth lens L4 and the fifth lens L5 in the imaging lens group forms a cemented lens with negative optical power. This not only reduces the focal length but also increases the numerical aperture (NA) of the imaging module without introducing significant spherical aberration. Furthermore, in the symmetrical structure of this application's double Gaussian lens, the seventh lens L7 with its positive meniscus can simultaneously control field curvature and spherical aberration.

[0103] The positive and negative values ​​of the optical power of each lens in the imaging lens group in this embodiment are shown in Table 2.

[0104] Table 2

[0105] lens L1 L2 L3 L4 L5 L6 L7 Optical power - + + - - + +

[0106] It should be noted that the "+" and "-" in Table 1 represent the positive and negative optical power of each lens in the optical lens of Example 1. "+" indicates that the lens has positive optical power; "-" indicates that the lens has negative optical power.

[0107] The positive and negative values ​​of the optical power of each lens in the imaging lens group in this embodiment are shown in Table 3.

[0108] Table 3

[0109] lens L1 L2 L3 L4 L5 L6 L7 unevenness +- ++ -+ -+ +- +- ++

[0110] It should be noted that in Table 3, “++”, “+-”, and “-+” represent the concavity or convexity of the object-side or image-side of each lens at the optical axis. “++” indicates that both the object-side and image-side of the lens are convex towards the object at the optical axis; “+-” indicates that both the object-side and image-side of the lens are convex towards the object at the optical axis, i.e., a double-convex crescent structure; and “-+” indicates that both the object-side and image-side of the lens are concave towards the object at the optical axis, i.e., a double-concave structure. Of course, in addition to those shown in the table, the concavity / convexity conditions also include "∞+", "∞-", "--", "+∞", "-∞", etc. Among them, "∞+" represents that the object side of the lens is flat at the optical axis, and the image side is convex towards the object side at the optical axis; "∞-" represents that the object side of the lens is flat at the optical axis, and the image side is concave towards the object side at the optical axis; "--" represents that both the object side and the image side of the lens are concave towards the object side at the optical axis; "+∞" represents that the object side of the lens is convex towards the object side at the optical axis, and the image side is flat at the optical axis; "-∞" represents that the object side of the lens is concave towards the object side at the optical axis, and the image side is flat at the optical axis.

[0111] After multiple experiments, it was found that in this embodiment, the focal length of the imaging lens group is 26mm-29mm. That is, the focal length of the imaging module is 26mm-29mm. Specifically, the focal length of the imaging lens group can be, but is not limited to, 28mm. When the focal length of the imaging lens group is 28mm, the distance between the first glass L11 and the first filter L12 in the direction parallel to the first optical axis (…). Figure 2 The T in the figure is 34mm-37mm. Based on this, in this embodiment, the aperture of the imaging module is 10mm, 10.1mm, ..., 10.8mm, 10.9mm, 11mm, ..., 11.5mm ..., 12mm.

[0112] Obtained through simulation Figures 5-7 The simulation diagram. Among them, Figure 5 The modulation transfer function (MTF) graph of visible light (from 400nm to 900nm) passing through the imaging module in Embodiment 1 of this application is given, referred to simply as the MTF graph. The MTF graph is a curve reflecting the contrast (color reproduction) reproduction of the optical lens. The horizontal axis of the MTF graph is the distance from the center to the edge, and the vertical axis reflects the quality of contrast, or in other words, the quality of color reproduction. The higher the value of the vertical axis of the MTF graph, the better the color reproduction and the higher the resolution of the optical lens. Figure 6 A field curve diagram of the imaging module in Embodiment 1 of this application is provided. Figure 7 A distortion diagram of the imaging module in Embodiment 1 of this application is provided. The distortion diagram represents the percentage distortion of the optical lens as the field of view changes, where the horizontal axis represents the percentage distortion and the vertical axis represents the normalized field of view height.

[0113] Since the emission wavelength of fluorescence typically falls within the visible or near-infrared band of 400nm to 900nm, the wavelength of the light source in the embodiments of this application can be, but is not limited to, a laser with a wavelength of 400nm to 900nm. By changing the light source, the imaging module can be used for visible light imaging alone, or it can be used for fluorescence imaging alone.

[0114] In summary, the focal length of the aforementioned imaging module is 28mm, and the maximum aperture of the imaging module is 10mm-12mm. When the photosensitive element uses a 1 / 1.8-inch CMOS chip with 4K resolution, the pixel size of this 4K resolution CMOS chip is 2μm, and the corresponding Nyquist frequency is calculated to be 250lp / mm. When imaging at 400nm to 900nm, the entrance pupil diameter of this optical endoscope's imaging module is ≥4.5mm, meeting the 4K resolution requirement. The absolute value of the distortion across the entire field of view of the imaging module is limited to 0.7%.

[0115] Figure 3 and Figure 4 The diagram shows the structure of an imaging module of an optical endoscope with two optical paths, illustrating that the first glass L11 and the first filter L12 are respectively arranged in an outward "V" shape and an inward "V" shape relative to the first optical axis. Figure 3 As shown, the imaging module of the optical endoscope includes: a first glass L11 arranged along the optical axis from the object side to the image side, an imaging lens group, a first filter L12, a target optical element S1, and a target photosensitive element. The optical axis includes a straight first optical axis from the first glass L11 to the first filter L12. Figure 1 The vertical dotted line) and the straight second optical axis from the first filter L12 to the first photosensitive element M1 ( Figure 1 (A horizontal dotted line in the middle), the second optical axis is perpendicular to the first optical axis, the target photosensitive element includes a first photosensitive element M1 and a second photosensitive element M2, the first photosensitive element M1 is located on the second optical axis, and the second photosensitive element M2 is located on the first optical axis; the target optical element S1 is a beam splitter, the target optical element S1 includes two right-angle prisms S11, the inclined surfaces of the two right-angle prisms S11 are attached to form a reflective surface S10, the reflective surface S10 is used to reflect part of the first light and transmit it to the first photosensitive element M1 along the second optical axis, the reflective surface S10 is used to allow part of the first light to pass through and be transmitted to the second photosensitive element M1 along the first optical axis; the intersection of the extension line of the reflective surface S10 and the extension line of the first filter L12 is located on a different side of the first optical axis from the first photosensitive element M1.

[0116] The aforementioned imaging lens group achieves focusing by moving as a whole along the first optical axis. This not only ensures that the focal length of the entire imaging module remains unchanged during focusing, thus maintaining the same field of view during imaging and improving image quality, but also allows the imaging lens group to be fixed together during installation, increasing focusing efficiency and simplifying the installation and drive structure of the imaging module, thereby reducing costs.

[0117] The first photosensitive element M1 is provided with a first protective sheet L21 on its object side, and the second photosensitive element M2 is provided with a second protective sheet L22 on its object side. The second protective sheet L22 may, but is not limited to, have the same structure as the first protective sheet L21.

[0118] In this embodiment, the optical path is divided into a first sub-optical path and a second sub-optical path by two right-angle prisms S11 in the target optical element S1. The optical axis of the first sub-optical path is parallel to the first optical axis, and the first ray can be imaged on the imaging surface of the second photosensitive element M2 along the first sub-optical path. The first sub-optical path is as follows: Figure 2As shown. The optical axis of the second sub-optical path includes a portion parallel to the first optical axis and a path parallel to the second optical axis. The first ray is reflected at the target optical element S1 by the reflecting surface S10 to the second optical axis, thereby forming an image on the imaging surface of the first photosensitive element M1. The second sub-optical path is as follows: Figure 1 As shown. That is to say, will Figure 1 and Figure 2 The optical paths of the two single-path imaging modules shown are combined to form a single-path module. They share the main optical elements, and the main difference lies in the structure of the target optical element S1.

[0119] In this embodiment, the imaging module further includes a second filter S2. The second filter S2 is located between the target optical element S1 and the first photosensitive element M1, and the filtering band of the second filter S2 is different from that of the filter film. Thus, by using different combinations of the first filter L12 and the second filter S2 in the optical path, different wavelengths can be filtered out, thereby meeting the imaging requirements of different scenarios and improving the versatility of the imaging module. In other words, the structure of this imaging module can be used for imaging light of different wavelengths.

[0120] Since the emission wavelength of fluorescence typically falls within the visible or near-infrared band of 400nm to 900nm, the wavelength of the light source in the embodiments of this application can be, but is not limited to, a laser with a wavelength of 400nm to 900nm. By changing the light source, the imaging module can be used for visible light imaging alone, or it can be used for fluorescence imaging alone.

[0121] In this embodiment, the first sub-optical path can be used for visible light imaging, and the second filter S2 on the second sub-optical path is used for fluorescence transmission. Therefore, the second sub-optical path can be used for fluorescence imaging. Alternatively, the second filter S2 can be positioned between the target optical element S1 and the second photosensitive element M2. In this case, the first sub-optical path is also used for fluorescence imaging, and the second sub-optical path is used for visible light imaging.

[0122] It should be noted that in this embodiment, the structure of the first glass L11, the imaging lens group, the first filter L12, the first photosensitive element M1 and the second photosensitive element M2 are the same as those in the above embodiments, and will not be described again here.

[0123] This application also provides an optical endoscope, which includes an imaging module.

[0124] The structure of the imaging module described above is the same as that of the imaging module in any of the above embodiments, and the effects achieved are also the same, so they will not be described again here.

[0125] This application also provides an optical endoscope system, including a light source host, an image processing device, and an optical endoscope. The structure of the optical endoscope in this optical endoscope system and the beneficial effects achieved are the same as those of the optical endoscope in the above embodiments, and will not be described again here.

[0126] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An imaging module for an optical endoscope, characterized in that, include: The first glass, imaging lens group, first filter, target optical element and target photosensitive element are arranged along the optical axis from the object side to the image side. The first filter includes a second glass and a filter film, and the filter film is disposed on at least one of the object plane and the image plane of the second glass. The image plane of the first glass is coated with an anti-reflective film; The first glass is inclined relative to the optical axis, and the acute angle formed between the first glass and the optical axis is the first included angle; The first filter is tilted relative to the optical axis, and the acute angle formed between the first filter and the optical axis is the second included angle. The tilt direction of the first filter is opposite to that of the first glass. The light rays incident on the imaging module from the object side include a first light ray and a second light ray. The first light ray passes through the first glass, the imaging lens group, the first filter and the target optical element, and then forms an image on the imaging surface of the target photosensitive element. The second light rays pass through the first glass and the imaging lens group, then illuminate the first filter, and after being reflected at least once by the first filter and the first glass, illuminate the area outside the imaging surface of the target photosensitive element.

2. The imaging module of the optical endoscope according to claim 1, characterized in that, The optical axis includes a straight first optical axis from the first glass to the first filter; The target photosensitive element includes a first photosensitive element that is not located on the first optical axis. The target optical element includes a reflective surface, which is used to transmit light to the imaging surface of the first photosensitive element. The intersection of the extension line of the reflective surface and the extension line of the first filter is located on a different side of the first optical axis from the first photosensitive element.

3. The imaging module of the optical endoscope according to claim 2, characterized in that, The target photosensitive element further includes a second photosensitive element located on the first optical axis. The target optical element is used to transmit a portion of the first light rays to the imaging surface of the first photosensitive element and to transmit a portion of the first light rays to the imaging surface of the second photosensitive element.

4. The imaging module of the optical endoscope according to claim 2, characterized in that, The acute angle formed between the first glass and the first optical axis is the first included angle, and the acute angle formed between the first filter and the first optical axis is the second included angle. The first included angle is smaller than the second included angle.

5. The imaging module of the optical endoscope according to claim 4, characterized in that, The first included angle is less than or equal to 80°, and the second included angle is less than or equal to 85°.

6. The imaging module of the optical endoscope according to claim 5, characterized in that, The first ray accounts for at least 70% of the total amount of light entering the imaging module from the object side.

7. The imaging module of the optical endoscope according to claim 5, characterized in that, The imaging lens group includes multiple lenses, and at least one of the object plane and image plane of the lenses is coated with the anti-reflection film.

8. The imaging module of the optical endoscope according to claim 7, characterized in that, The imaging lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged along the first optical axis from the object side to the image side, wherein the optical power of the first lens is positive.

9. The imaging module of the optical endoscope according to claim 8, characterized in that, The seventh lens is a meniscus lens, and both the object plane and the image plane of the seventh lens bulge towards the object side at the first optical axis.

10. The imaging module of the optical endoscope according to any one of claims 2-9, characterized in that, It also includes an aperture stop, which is located on the object side of the first glass; The imaging lens group as a whole can move along the first optical axis to achieve focusing; And / or, the focal length of the imaging lens group is 26mm-29mm, and the distance between the first glass and the first filter in the direction parallel to the first optical axis is 34mm-37mm.

11. An optical endoscope, characterized in that, include: The imaging module of the optical endoscope as described in any one of claims 1-10.

12. An optical endoscope system, characterized in that, include: The light source host, the image processing device, and the optical endoscope as described in claim 11.

Images