A miniature depth-of-field extended lens

Abstract

The present invention discloses a miniature depth of field extension lens, which belongs to the field of miniature imaging technology, and includes two or more lens assemblies arranged in sequence from the object side to the image side and a bonding layer, wherein the lens assembly includes a lens and a glass substrate, wherein the surface of the lens is aspherical, and the glass substrate is used to assemble the lens; adjacent lens assemblies are connected by the bonding layer, and the bonding layer is used to limit the spacing between the lens assemblies. The present invention connects two or more lens assemblies by a bonding layer, and the spacing between the lenses can be limited by the bonding layer. The lens can achieve the expansion of the depth of field by combining the surface of the lens itself and its combination. On this basis, the lens is no longer supported by a lens barrel, and the volume and weight of the lens can be reduced, thereby reducing the manufacturing cost.

Description

Technical Field

[0001] The present invention relates to the field of miniature imaging technology, and in particular to a miniature imaging system applied to medical treatment, specifically a miniature depth-of-field extended lens. Background Art

[0002] As medical technology is changing with each passing day, endoscopy technology is becoming increasingly important as an important tool in the field of medical diagnosis and treatment. Endoscopy greatly enhances doctors' ability to accurately observe and evaluate patients' internal organs by providing them with high-definition, real-time in vivo images. In particular, endoscopy has become an indispensable diagnostic tool in the diagnosis of gastrointestinal diseases. However, despite the significant progress made in endoscopy technology, doctors still face many challenges in actual application.

[0003] The natural peristalsis and tremor of the gastrointestinal tract is a major problem during endoscopic examinations. These involuntary movements not only cause blur and jitter in the images captured by the endoscope, but also make it difficult for doctors to focus on the lesion area stably for a long time, which seriously affects the accuracy of diagnosis and the effectiveness of treatment. This effect is particularly significant when it is necessary to carefully observe tiny lesions or perform delicate operations.

[0004] To solve this problem, the industry has been continuously exploring and innovating endoscope technology. Among them, improving the image quality and stability of the endoscope is the key. By improving the design of the optical system and expanding the depth of field of the endoscope, the impact of small changes in gastrointestinal movements on image clarity can be reduced to a certain extent. Such a design can reduce the number of times doctors need to frequently adjust the focus during endoscopic examinations, improve inspection efficiency, and also provide more reliable technical support for the early detection of potential lesions.

[0005] However, in the process of achieving depth of field expansion, the traditional multi-group lens matching method has encountered bottlenecks such as large size and high cost. The traditional multi-group lens needs to be installed and fixed with a lens barrel, which not only increases the size and weight of the lens, but also increases the manufacturing cost, limiting the further popularization and application of endoscope technology. Summary of the invention

[0006] The purpose of the present invention is to provide a miniature depth-of-field extended lens to solve the problems existing in the above-mentioned prior art. Two or more groups of lens assemblies are connected by a bonding layer. The bonding layer can be used to limit the spacing between the lenses. Combined with the surface shape of the lens itself and its combination, the lens can achieve an extended depth of field. On this basis, the lens is no longer supported by a lens barrel, which can reduce the size and weight of the lens and reduce the manufacturing cost.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] The present invention provides a miniature depth-of-field extended lens, comprising two or more groups of lens components sequentially arranged from the object side to the image side and a bonding layer, wherein the lens components comprise lenses and a glass substrate, the surface of the lenses is aspherical, and the glass substrate is used for assembling the lenses; adjacent lens components are connected via the bonding layer, and the bonding layer is used for limiting the spacing between the lens components.

[0009] In one embodiment, a first lens, a second lens, a third lens, a fourth lens and a fifth lens are sequentially arranged from the object side surface to the image side surface; a side of the first lens close to the object side surface is mounted on a first glass substrate, a side of the second lens close to the image side surface is mounted on a second glass substrate, a side of the third lens close to the object side surface is mounted on a third glass substrate, a side of the fourth lens close to the image side surface is mounted on a fourth glass substrate, and a side of the fifth lens close to the object side surface is mounted on a fifth glass substrate.

[0010] In one embodiment, the first lens has a negative refractive power, and its object side surface is a plane, and its image side surface is a concave surface; the second lens has a positive refractive power, and its object side surface is a convex surface, and its image side surface is a plane; the third lens has no refractive power, and its object side surface and image side surface are both planes; the fourth lens has a positive refractive power, and its object side surface is a convex surface, and its image side surface is a plane; the fifth lens has a positive refractive power, and its object side surface is a plane, and its image side surface is a convex surface.

[0011] In one embodiment, an aperture stop is further included, and the aperture stop is disposed between the third glass substrate and the third lens; and / or a beam splitter prism is disposed on the image side of the fifth lens.

[0012] In one embodiment, the following conditions are met:

[0013] -1.1 <f1 / f<-0.9;

[0014] 1.25 <f2 / f<1.4;

[0015] 1.40 <f4 / f<1.5;

[0016] 5.75 <f5 / f<5.9;

[0017] Among them, f1, f2, f4, f5 and f are the focal lengths of the first lens, the second lens, the fourth lens, the fifth lens and the lens respectively.

[0018] In one embodiment, the following conditions are met:

[0019] 0.85mm≤f≤0.95mm;

[0020] 3.7mm≤TTL≤4.5mm;

[0021] 0.16≤f / TTL≤0.27;

[0022] Wherein, f is the focal length of the lens, and TTL is the total optical length of the lens.

[0023] In one embodiment, the following conditions are met:

[0024] 0.55 <Imeg / f<0.7;

[0025] 0.25 <Imeg / TTL<0.35;

[0026] Wherein, Imeg is the maximum half image height, TTL is the total optical length of the lens, and f is the focal length of the lens.

[0027] In one embodiment, the following conditions are met:

[0028] 4≤F#≤6;

[0029] 55°<FOV<65°;

[0030] Wherein, F# is the F number of the lens, and FOV is the field of view of the lens.

[0031] In one embodiment, the aspheric sag height and aspheric aperture of the first lens, the second lens, the fourth lens, and the fifth lens satisfy the aspect ratio condition, and the aspect ratio condition is as follows:

[0032] ;

[0033] Q<0.24;

[0034] Among them, Q is the aspect ratio, h is the aspheric surface height, and D is the aspheric surface aperture.

[0035] In one embodiment, the first glass substrate, the second glass substrate, the third glass substrate, the fourth glass substrate and the fifth glass substrate have a substrate thickness range of:

[0036] 0.25<d<0.5mm;

[0037] Where d is the substrate thickness.

[0038] Compared with the prior art, the present invention has achieved the following technical effects:

[0039] The present invention connects two or more groups of lens assemblies through a bonding layer, and the bonding layer can be used to limit the distance between the lenses. Combined with the surface shape of the lens itself and its combination, the lens can achieve an extended depth of field. On this basis, the lens is no longer supported by a lens barrel, which can reduce the size and weight of the lens and reduce the manufacturing cost.

[0040] Other technical solutions included in the present invention can also achieve the following technical effects:

[0041] The present invention adopts a structural design of five groups of lenses + a beam splitter prism. By optimizing the main parameters of the lens such as resolution, depth of field and field angle, and matching some special optical elements, the depth of field of the lens is expanded while improving the image clarity within the effective depth of field range. At the same time, the present invention adopts a more precise glue embossing and bonding manufacturing process, which greatly reduces the cost while ensuring the imaging quality.

[0042] The present invention significantly improves the overall quality and efficiency of endoscopic examinations while helping doctors diagnose conditions more accurately, providing patients with a more comfortable and safer treatment experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 Schematic diagram of a micro depth-of-field extended lens in an embodiment of the present invention;

[0045] Figure 2 The software simulation optical path diagram of embodiment 1 of the present invention;

[0046] Figure 3a and Figure 3b They are respectively the diffraction MTF of Example 1 of the present invention at object distances of 1 mm and 6 mm in the visible light band;

[0047] Figure 4a and Figure 4b They are respectively the point array spot diagrams of Example 1 of the present invention at object distances of 1 mm and 6 mm in the visible light band;

[0048] Figure 5a and Figure 5b They are respectively field curvature & distortion diagrams of Example 1 of the present invention when the object distances are 1 mm and 6 mm in the visible light band;

[0049] Figure 6 The software simulation optical path diagram of embodiment 2 of the present invention;

[0050] Figure 7a and Figure 7b They are respectively the diffraction MTF of Example 2 of the present invention at object distances of 3 mm and 100 mm in the visible light band;

[0051] Figure 8a and Figure 8b They are respectively the point array spot diagrams of Example 2 of the present invention at object distances of 3 mm and 100 mm in the visible light band;

[0052] Figure 9a and Figure 9b They are respectively field curvature & distortion diagrams of Example 2 of the present invention when the object distances are 3 mm and 100 mm in the visible light band;

[0053] Among them, 1. first glass substrate; 2. second glass substrate; 3. third glass substrate; 4. fourth glass substrate; 5. fifth glass substrate; 6. first lens; 7. second lens; 8. third lens; 9. fourth lens; 10. fifth lens; 11. dichroic prism; 12. first image plane; 13. second image plane; 14. first bonding layer; 15. second bonding layer; 16. aperture stop. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] The purpose of the present invention is to provide a miniature depth-of-field extended lens to solve the problems existing in the prior art. Two or more groups of lens assemblies are connected through a bonding layer. The bonding layer can be used to limit the spacing between lenses. Combined with the surface shape of the lens itself and its combination, the lens can achieve an extended depth of field. On this basis, the lens is no longer supported by a lens barrel, which can reduce the size and weight of the lens and reduce the manufacturing cost.

[0056] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0057] The object side surface mentioned in the present invention is located in the accompanying drawing ( Figure 1 , Figure 2 and Figure 6 ) is shown on the left side, and the image side is located in the figure ( Figure 1 , Figure 2 and Figure 6 ) is shown on the right side of the status.

[0058] like Figure 1 to Figure 9b As shown, the present invention provides a miniature depth of field extension lens, including two or more groups of lens assemblies arranged in sequence from the object side to the image side and a bonding layer. For example, five groups of lens assemblies are arranged, each group of lens assemblies includes a lens and a glass substrate, and the lenses and glass substrates of different lens assemblies have different parameters. The surface of the lens is aspherical, and the glass substrate is used to assemble the lens. The lens and the glass substrate can be snapped or bonded. Through the combination of multiple groups of lenses and glass substrates, the entire lens can have the effect of extending the depth of field. The combined lens assemblies are bonded to each other or have a spacing. Adjacent lens assemblies are connected by a bonding layer. The bonding layer can use bonding glue and a gasket that does not affect the light path. The spacing between the lens assemblies is limited by the bonding layer, and multiple lens assemblies are connected to form an integral lens. In addition, in order to achieve the effect of lens shading, black glue can be set on the radial outer surface of the lens.

[0059] Each lens of the present invention is made by nanoimprinting technology, and the manufacturing process is imprinting-bonding-cutting, that is, after multiple lenses are uniformly manufactured in the same layout, they are bonded to the layout of other glass substrates and lens layouts, and the spacing between each glass substrate / bonding layer is ensured during bonding. Cutting is performed after bonding to complete the production of the lens. At this time, the completed lens retains the spacing between the lenses to ensure that the transmission of the light path meets the design requirements. The present invention connects two or more groups of lens assemblies through a bonding layer, and the bonding layer can be used to limit the spacing between the lenses. The lens itself is combined with its own surface shape and combination to enable the lens to achieve an expansion of the depth of field. On this basis, the lens is no longer supported by a lens barrel, which can reduce the volume and weight of the lens and reduce the manufacturing cost.

[0060] In one embodiment, a first lens 6, a second lens 7, a third lens 8, a fourth lens 9, and a fifth lens 10 are sequentially arranged from the object side to the image side; the side of the first lens 6 close to the object side is mounted on the first glass substrate 1, the side of the second lens 7 close to the image side is mounted on the second glass substrate 2, the side of the third lens 8 close to the object side is mounted on the third glass substrate 3, the side of the fourth lens 9 close to the image side is mounted on the fourth glass substrate 4, and the side of the fifth lens 10 close to the object side is mounted on the fifth glass substrate 5. The second glass substrate 2 and the third glass substrate 3 are connected by a first bonding layer 14, the fourth glass substrate 4 and the fifth glass substrate 5 are connected by a second bonding layer 15, and the arrangement positions of the remaining bonding layers are arranged on the outer diameter side of the concave / convex surface of each lens. Figure 1 , Figure 2 and Figure 6 Only the optical path is shown in the figure, and the specific bonding layer position is not shown. It should be noted that the spacing between the lenses in the figure should be retained after the bonding layers are set.

[0061] In one embodiment, the first lens 6 has a negative refractive power, and its object side surface is a plane, and its image side surface is a concave surface; the second lens 7 has a positive refractive power, and its object side surface is a convex surface, and its image side surface is a plane; the third lens 8 has no refractive power, and its object side surface and image side surface are both planes; the fourth lens 9 has a positive refractive power, and its object side surface is a convex surface, and its image side surface is a plane; the fifth lens 10 has a positive refractive power, and its object side surface is a plane, and its image side surface is a convex surface.

[0062] In one embodiment, an aperture stop 16 is further included, and the aperture stop 16 is disposed between the third glass substrate 3 and the third lens 8 .

[0063] In one embodiment, a beam splitter prism 11 is disposed on the image side of the fifth lens 10, and the beam splitter prism 11 has a first image plane 12 in the axial direction of the lens and a second image plane 13 in the radial direction of the lens. The present invention adopts a structural design of five groups of lenses + a beam splitter prism 11, and by optimizing the main parameters of the lens such as resolution, depth of field and field angle, and then matching optical elements such as the beam splitter prism 11, the depth of field of the lens is expanded while improving the image clarity within the effective depth of field range; at the same time, the present invention adopts a more precise glue stamping bonding manufacturing process, which greatly reduces the cost while ensuring the imaging quality.

[0064] In one embodiment, the following conditions are met:

[0065] -1.1 <f1 / f<-0.9;

[0066] 1.25 <f2 / f<1.4;

[0067] 1.40 <f4 / f<1.5;

[0068] 5.75 <f5 / f<5.9;

[0069] Among them, f1, f2, f4, f5 and f are the focal lengths of the first lens 6, the second lens 7, the fourth lens 9, the fifth lens 10 and the lens, respectively.

[0070] In one embodiment, the following conditions are met:

[0071] 0.85mm≤f≤0.95mm;

[0072] 3.7mm≤TTL≤4.5mm;

[0073] 0.16≤f / TTL≤0.27;

[0074] Wherein, f is the focal length of the lens, and TTL is the total optical length of the lens, that is, the distance from the object side of the first lens 6 to the first image plane 12 in the axial direction.

[0075] In one embodiment, the following conditions are met:

[0076] 0.55 <Imeg / f<0.7;

[0077] 0.25 <Imeg / TTL<0.35;

[0078] Among them, Imeg is the maximum half image height, TTL is the total optical length of the lens, that is, the distance from the object side of the first lens 6 to the first image plane 12 in the axial direction, and f is the focal length of the lens. The lens of the present invention that meets the above conditions ensures that its optical system has a sufficiently large image height to match the high-resolution photosensitive chip used.

[0079] In one embodiment, the following conditions are met:

[0080] 4≤F#≤6;

[0081] 55°<FOV<65°;

[0082] Wherein, F# is the F number of the lens, and FOV is the field of view of the lens. The lens of the present invention that meets the above parameters has a wide-angle feature.

[0083] In one embodiment, the aspheric sag height and aspheric aperture of the first lens 6, the second lens 7, the fourth lens 9 and the fifth lens 10 satisfy the aspect ratio condition, and the aspect ratio condition is as follows:

[0084] ;

[0085] Q<0.24;

[0086] Among them, Q is the aspect ratio, h is the aspheric surface height, that is, the depth or height of the aspheric surface, and D is the aspheric surface diameter. The above aspect ratio ensures the feasibility of process processing and lays the foundation for the yield of the finished product.

[0087] In one embodiment, the thickness of the first glass substrate 1, the second glass substrate 2, the third glass substrate 3, the fourth glass substrate 4 and the fifth glass substrate 5 ranges from:

[0088] 0.25<d<0.5mm;

[0089] Where d is the substrate thickness.

[0090] The present invention provides specific application embodiments as follows:

[0091] Embodiment 1:

[0092] The main design parameters of this embodiment refer to Table 1-1, the lens parameters refer to Table 1-2, and the aspheric high-order coefficients refer to Table 1-3.

[0093] Table 1-1 Main design parameters

[0094]

[0095] Table 1-2 Lens parameters

[0096]

[0097] The calculation equation for the aspheric surface shape is as follows:

[0098] ;

[0099] in, is the curvature, R is the radius of curvature, h is the overall thickness of the lens, K is the cone coefficient, A4, A6, A8, A10 are the fourth, sixth, eighth, and tenth aspheric high-order coefficients respectively.

[0100] Table 1-3 Aspheric high-order coefficients

[0101]

[0102] In the first embodiment of the present invention, the object distance is 1 mm to 6 mm, and the optical simulation results of the lens are as follows: Figure 2 As shown in Figure 1, the lens can be used as a magnifying endoscope, and its magnification can reach up to 0.53×. The MTF curve of the lens in the visible light band is shown in Figure 1. Figure 3a and Figure 3b As shown by Figure 3a and Figure 3b It can be seen that at object distances of 1mm and 6mm, its MTF can reach 0.2 at 145lp / mm, which is close to the diffraction limit. Figure 4a and Figure 4b is the spot diagram of the lens at object distances of 1mm and 6mm. Figure 4a and Figure 4b The RMS radius is very small and the GEO radius is less than 10um, which shows that the optical system has a good ability to converge light. Figure 5a and Figure 5b The field curvature & distortion diagram for the lens at the specified object distance is given by Figure 5a and Figure 5b It can be seen that at object distances of 1mm and 6mm, the field curvatures of the optical system in the sagittal and meridional directions are both less than 0.1mm, and the distortion is less than 6.5%. It can be seen that the image deformation of the optical system is small, ensuring excellent imaging results.

[0103] Embodiment 2:

[0104] The main design parameters of this embodiment refer to Table 2-1, the lens parameters refer to Table 2-2, and the aspheric high-order coefficients refer to Table 2-3.

[0105] Table 2-1 Main design parameters

[0106]

[0107] Table 2-2 Lens parameters

[0108]

[0109] Table 2-3 Aspheric high-order coefficients

[0110]

[0111] The optical simulation results of the lens in the second embodiment of the present invention are as follows: Figure 6 The MTF curve of the lens in the visible light band is shown as follows Figure 7a and Figure 7b ,from Figure 7a and Figure 7b It can be seen that at object distances of 3mm and 100mm, when the spatial frequency reaches 1 / 2 Nyquist frequency of the matched chip, 145lp / mm, the MTF is greater than 0.2, indicating that the lens has a high resolution and ensures good imaging quality; Figure 8a and Figure 8b As shown in FIG. 1 , the spot diagram provided by this embodiment shows that at object distances of 3 mm and 100 mm, the RMS radius of the spot diagram is very small and the GEO radius is less than 10 μm, indicating that the optical system has a good imaging effect. The field curvature and distortion of the optical system are shown in FIG. Figure 9a and Figure 9b As shown, it can be seen that at object distances of 3mm and 100mm, the field curvature in the meridian and sagittal directions is small, and the distortion is less than 6.5%, ensuring excellent imaging results of the system.

[0112] Compared with Example 1, Example 2 of the present invention has a substantially identical field angle, but the depth of field of the two embodiments is different. Example 1 is applied to magnifying endoscopes, and Example 2 is applied to medical endoscopes such as gastroenteroscopy. At the same time, both embodiments of the present invention are used with a beam splitter prism 11, which can expand the resolution of near and far views, so that the resolution of mid-range views is basically unaffected, and the performance is optimized within a limited cost. In practical applications, different imaging systems can be selected according to actual needs.

[0113] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A miniature depth-of-field extended lens, characterized in that: include: Two or more groups of lens assemblies are arranged in sequence from the object side to the image side, the lens assembly comprises a lens and a glass substrate, the surface of the lens is aspherical, and the glass substrate is used to assemble the lens; and a bonding layer, through which adjacent lens assemblies are connected, and the bonding layer is used to limit the spacing between the lens assemblies; A first lens, a second lens, a third lens, a fourth lens and a fifth lens are sequentially arranged from the object side to the image side; a side of the first lens close to the object side is mounted on a first glass substrate, a side of the second lens close to the image side is mounted on a second glass substrate, a side of the third lens close to the object side is mounted on a third glass substrate, a side of the fourth lens close to the image side is mounted on a fourth glass substrate, and a side of the fifth lens close to the object side is mounted on a fifth glass substrate; The first lens has a negative refractive power, the second lens has a positive refractive power, the third lens has no refractive power, the fourth lens has a positive refractive power, and the fifth lens has a positive refractive power; a dioptric prism is disposed on the image side of the fifth lens; Wherein, f1, f2, f4, f5 and f are the focal lengths of the first lens, the second lens, the fourth lens, the fifth lens and the lens, respectively, and satisfy the following conditions: -1.1 <f1 / f<-0.9; 1.25 <f2 / f<1.4; 1.40 <f4 / f<1.5; 5.75 <f5 / f<5.9。 2. The micro-lens with extended depth of field according to claim 1, characterized in that: The object side surface of the first lens is a plane and the image side surface is a concave surface; the object side surface of the second lens is a convex surface and the image side surface is a plane; the object side surface and the image side surface of the third lens are both planes; the object side surface of the fourth lens is a convex surface and the image side surface is a plane; the object side surface of the fifth lens is a plane and the image side surface is a convex surface.

3. The micro-lens with extended depth of field according to claim 2, characterized in that: An aperture stop is also included, and the aperture stop is disposed between the third glass substrate and the third lens.

4. The micro-depth-extended-field lens according to claim 2, characterized in that: The following conditions are met: 0.85mm≤f≤0.95mm; 3.7mm≤TTL≤4.5mm; 0.16≤f / TTL≤0.27; Wherein, f is the focal length of the lens, and TTL is the total optical length of the lens.

5. The micro-depth-extended-field lens according to claim 2, characterized in that: The following conditions are met: 0.55 <Imeg / f<0.7; 0.25 <Imeg / TTL<0.35; Wherein, Imeg is the maximum half image height, TTL is the total optical length of the lens, and f is the focal length of the lens.

6. The micro-depth-extended-field lens according to claim 2, characterized in that: The following conditions are met: 4≤F#≤6； 55°<FOV<65°; Wherein, F# is the F number of the lens, and FOV is the field of view of the lens.

7. The micro-lens with extended depth of field according to claim 2, characterized in that: The aspheric sag height and aspheric aperture of the first lens, the second lens, the fourth lens and the fifth lens meet the aspect ratio condition, and the aspect ratio condition is as follows: ； Q＜0.24； Among them, Q is the aspect ratio, h is the aspheric surface height, and D is the aspheric surface aperture.

8. The micro-depth-extended-field lens according to claim 2, characterized in that: The substrate thickness ranges of the first glass substrate, the second glass substrate, the third glass substrate, the fourth glass substrate and the fifth glass substrate are: 0.25<d<0.5mm; Where d is the substrate thickness.

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