A small-sized optical endoscope

Abstract

The present invention discloses a small-sized optical endoscope, which includes a sleeve, and a lens group is embedded in the sleeve; the lens group includes a first lens, a second lens, a third lens, a fourth lens and a fifth lens arranged in sequence along the optical path; the diameters of the first lens, the second lens, the third lens, the fourth lens and the fifth lens are all not greater than 1 mm; a first interval is provided between the first lens and the second lens, a second interval is provided between the second lens and the third lens, a third interval is provided between the third lens and the fourth lens, and a fourth interval is provided between the fourth lens and the fifth lens. The structure of the present invention is simple, the diameter of the final finished endoscope is small, the applicability is high, the resistance to various adverse environments is high, and the service life is long; the imaging is clearer, the distortion rate is low, which is more beneficial to medical applications and industrial applications.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and particularly to a small-sized optical endoscope. Background Art

[0002] An endoscope is a detection instrument integrating traditional optics, ergonomics, precision machinery, modern electronics, mathematics, software, etc.; it has structures such as an image sensor, an optical lens, a light source illumination, and a mechanical device. Endoscopes play an indispensable role in medical diagnosis and industrial inspection. For example, endoscopic examination is the main diagnostic method for digestive tract diseases and respiratory diseases, and is also an important part of the latest minimally invasive surgery; the internal flaw detection and non-destructive testing of industrial endoscopes are widely used in automobiles, aeroengines, pipelines, mechanical parts, etc., and can achieve non-destructive testing without disassembling or damaging the assembly and without stopping the operation of the equipment.

[0003] Currently, endoscopes on the market are gradually developing towards miniaturization. However, too small a size will make the lens processing of the endoscope difficult or even impossible. Existing optical cold processing can achieve lenses smaller than 2 mm, while when the lens size is less than 1 mm, there are difficulties in processing or even impossible to process. In Chinese invention patent CN112107278A, an endoscope with a lens diameter less than 1 mm is designed by means of plastic aspherical injection molding. However, plastic endoscopes cannot withstand high temperatures, are restricted in medical and industrial use, have a short service life, and low imaging clarity. To solve the above problems and achieve miniaturization of the endoscope size and simple processing, based on the current level of optical cold processing, the present invention designs an endoscope structure with a size less than 1 mm and easy to process, which is more convenient to be applied to smaller apertures, has clearer imaging, and a longer service life. Summary of the Invention

[0004] The purpose of the present invention is to provide a small-sized optical endoscope to solve the problems existing in the above-mentioned prior art.

[0005] To achieve the above purpose, the present invention provides the following solution: The present invention provides a small-sized optical endoscope, including a sleeve, and a lens group is embedded in the sleeve;

[0006] The lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged in the optical path in sequence; the diameters of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all not greater than 1 mm;

[0007] A first interval is provided between the first lens and the second lens, a second interval is provided between the second lens and the third lens, a third interval is provided between the third lens and the fourth lens, and a fourth interval is provided between the fourth lens and the fifth lens.

[0008] Preferably, the first lens and the fifth lens are plano-concave lenses, and the second lens, the third lens, and the fourth lens are plano-convex lenses.

[0009] Preferably, for the first lens, f1 = -0.6 mm to -0.7 mm, R1 = ∞ mm,

[0010] R2 = 0.5 mm to 0.6 mm, N d = 1.8 - 1.85, V d = 46 - 47, D1 = 0.30 mm to 0.35 mm,

[0011] L1 = 0.05 mm to 0.1 mm;

[0012] wherein, f1 represents the focal length of the first lens; R1 represents the front curvature radius of the lens; R2 represents the rear surface curvature radius of the lens; N d represents the refractive index of the lens material with respect to d light; V d represents the Abbe number of the lens material with respect to d light; D1 represents the thickness of the first lens, and L1 represents the air gap of the first lens.

[0013] Preferably, for the second lens, f2 = 1.6 mm to 1.65 mm, R1 = 1.3 mm to 1.4 mm, R2 = ∞ mm, N d = 1.8 - 1.85, V d = 22 - 23, D2 = 0.5 mm to 0.6 mm, L2 = 0.02 mm to 0.04 mm;

[0014] wherein, f2 represents the focal length of the second lens; R1 represents the front curvature radius of the lens; R2 represents the rear surface curvature radius of the lens; N d represents the refractive index of the lens material with respect to d light; V d represents the Abbe number of the lens material with respect to d light; D2 represents the thickness of the second lens, and L2 represents the air gap of the second lens.

[0015] Preferably, f3 = 0.6 mm to 0.70 mm, R1 = ∞ mm, R2 = -0.7 mm to -0.6 mm, N d = 1.85 - 1.9, V d = 40.5 - 41, D3 = 0.5 mm to 0.6 mm, L3 = 0.05 mm to 0.1 mm;

[0016] wherein, f3 represents the focal length of the third lens; R1 represents the front curvature radius of the lens; R2 represents the rear surface curvature radius of the lens; N d represents the refractive index of the lens material with respect to d light; V drepresents the Abbe number of the lens material with respect to d light; D3 represents the thickness of the third lens, and L3 represents the air gap of the third lens.

[0017] Preferably, for the fourth lens, f4 = 1.1 mm - 1.2 mm, R1 = ∞ mm, R2 = -1.5 mm - -1 mm, N d = 1.9 - 1.95, V d = 32 - 32.5, D4 = 0.5 mm - 0.55 mm, L4 = 0.02 mm - 0.03 mm;

[0018] wherein, f4 represents the focal length of the fourth lens; R1 represents the front curvature radius of the lens; R2 represents the curvature radius of the rear surface of the lens; N d represents the refractive index of the lens material with respect to d light; V d represents the Abbe number of the lens material with respect to d light; D4 represents the thickness of the fourth lens, and L4 represents the air gap of the fourth lens.

[0019] Preferably, for the fifth lens, f5 = -0.85 mm - -0.8 mm, R1 = -0.8 mm - -0.75 mm, R2 = ∞ mm, N d = 1.95 - 1.98, V d = 17.9 - 18, D5 = 0.5 mm - 0.55 mm, L5 = 0.3 mm - 0.35 mm;

[0020] wherein, f5 represents the focal length of the fifth lens; R1 represents the front curvature radius of the lens; R2 represents the curvature radius of the rear surface of the lens; N d represents the refractive index of the lens material with respect to d light; V d represents the Abbe number of the lens material with respect to d light; D5 represents the thickness of the fifth lens, and L5 represents the air gap of the fifth lens.

[0021] Preferably, the thickness of the first gap is 0.08 mm - 0.09 mm; the thickness of the second gap is 0.01 mm - 0.03 mm; the thickness of the third gap is 0.05 mm - 0.06 mm, and the thickness of the fourth gap is 0.02 mm - 0.03 mm.

[0022] Preferably, the curved surfaces of the plano - concave lens and the plano - convex lens are spherical or aspherical.

[0023] Preferably, the material of the sleeve is a non - toxic flexible material.

[0024] The present invention discloses the following technical effects: The present invention provides a small-sized optical endoscope. The lens assembly of the endoscope is composed of a plurality of plano-convex lenses and a plurality of plano-concave lenses, and the diameter of each lens is less than 1 mm, reducing the diameter of the endoscope, enabling it to be applied to a wider range of fields and improving its applicability; The endoscope is composed of a combination of a plurality of plano-convex lenses and a plurality of plano-concave lenses, with different focal lengths and air intervals. When combined with each other, when light is refracted by the endoscope, the refracted light of the previous lens is corrected, reducing the distortion rate of the light after multiple refractions, making the final image more consistent with reality, and making it easier to observe the situation of objects in small apertures. The structure of the present invention is simple, the diameter of the final finished endoscope is small, the applicability is high, the resistance to various adverse environments is high, and the service life is long; The imaging is clearer, the distortion rate is low, which is more beneficial to medical applications and industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 It is a three-dimensional view of the small-sized optical endoscope of the present invention;

[0027] Figure 2 It is a schematic structural view of the small-sized optical endoscope of the present invention;

[0028] Figure 3 It is a three-dimensional view of the first lens of the present invention;

[0029] Figure 4 It is a schematic structural view of the first lens of the present invention;

[0030] Figure 5 It is a three-dimensional view of the second lens of the present invention;

[0031] Figure 6 It is a schematic structural view of the second lens of the present invention;

[0032] Figure 7 It is a three-dimensional view of the third lens of the present invention;

[0033] Figure 8 It is a schematic structural view of the third lens of the present invention;

[0034] Figure 9 It is a three-dimensional view of the fourth lens of the present invention;

[0035] Figure 10 It is a schematic structural view of the fourth lens of the present invention;

[0036] Figure 11 This is the three-dimensional view of the fifth lens of the present invention;

[0037] Figure 12 This is the structural schematic diagram of the fifth lens of the present invention;

[0038] Among them, 1. Sleeve; 2. First lens; 3. Second lens; 4. Third lens; 5. Fourth lens; 6. Fifth lens; 7. First interval; 8. Second interval; 9. Third interval; 10. Fourth interval. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0041] Refer to Figures 1-12 , the present invention provides a small-sized endoscope, including a sleeve 1, and a lens group is embedded in the sleeve 1;

[0042] The lens group includes a first lens 2, a second lens 3, a third lens 4, a fourth lens 5, and a fifth lens 6 arranged in sequence according to the optical path; the diameters of the first lens 2, the second lens 3, the third lens 4, the fourth lens 5, and the fifth lens 6 are all not greater than 1 mm;

[0043] A first interval 7 is provided between the first lens 2 and the second lens 3, a second interval 8 is provided between the second lens 3 and the third lens 4, a third interval 9 is provided between the third lens 4 and the fourth lens 5, and a fourth interval 10 is provided between the fourth lens 5 and the fifth lens 6.

[0044] The first lens 2, the second lens 3, the third lens 4, the fourth lens 5, and the fifth lens 6 are snap-connected in the inner cavity of the sleeve 1 according to the set order and position intervals.

[0045] The present invention provides a small-sized optical endoscope. The lens assembly of the endoscope is composed of a plurality of plano-convex lenses and a plurality of plano-concave lenses, and the diameter of each lens is less than 1 mm, which reduces the diameter of the endoscope, enables it to be applied to a wider range of fields, and improves the applicability. The endoscope is composed of a combination of a plurality of plano-convex lenses and a plurality of plano-concave lenses, with different focal lengths and air spacings. When light is refracted through the endoscope, the refracted light of the previous lens is corrected, reducing the distortion rate of the light after multiple refractions, making the final image more consistent with reality, and facilitating the observation of the situation of objects in small apertures.

[0046] In a further optimized solution, the first lens 2 and the fifth lens 6 are plano-concave lenses, and the second lens 3, the third lens 4, and the fourth lens 5 are plano-convex lenses. A plano-concave lens is a lens with two asymmetric surfaces, one spherical and one flat, with a thinner middle thickness than the two sides, having a negative focal length. When light enters from the flat end and exits from the concave surface, the light will diverge, and it is used to diverge a parallel beam of light. A plano-convex lens is a lens with one convex surface and one flat surface, with a greater middle thickness than the two sides. When light enters from the flat surface, the light converges on the convex side. In the present invention, the first lens 2 and the fifth lens 6 are plano-concave lenses, and the second lens 3, the third lens 4, and the fourth lens 5 are plano-convex lenses. When installed, the concave surface of the first lens 2 faces the second lens 3, the convex surface of the second lens 3 faces the first lens 2, the flat surface of the third lens 4 faces the second lens 3, the flat surface of the fourth lens 5 faces the third lens 4, and the concave surface of the fifth lens 6 faces the fourth lens 5. When in use, the imaging light emitted by the light source of the endoscope (not shown in the figure) enters from the flat surface of the first lens 2, diverges after passing through the first lens 2, and then sequentially passes through the second lens 3, the third lens 4, and the fourth lens 5 to form a highly convergent beam, reducing the consumption during the light conduction process. Then, it passes through the fifth lens 6 to complete the imaging. The first lens 2 is a negative lens with a large optical power to converge the optical path of a large field of view. The second lens 3 and the third lens 4 are designed with two adjacent flat surfaces to facilitate the placement of the aperture stop. This arrangement not only increases the intensity of light conduction and reduces the consumption during the light conduction process but also does not affect the imaging of light and does not distort the image seen by the present invention. At the same time, since imaging is performed in the visible light band, the refractive indices of glass corresponding to different bands of light are different, resulting in the separation of the image points formed by different colors of light after passing through the lens. A single object point becomes multiple colored image points after imaging, causing a decrease in the resolution of the later imaging and distortion of the picture, which is seriously inconsistent with the actual object. However, the cooperation of the materials and refractive indices of the multiple lenses of the present invention can re-converge the diverging beam, making the images of different bands of light form at one point and not causing imaging distortion due to light scattering.

[0047] Furthermore, the first lens 2, the second lens 3, the third lens 4, the fourth lens 5, and the fifth lens 6 preferably use high refractive index materials. When the optical power is fixed, the radius of curvature is as large as possible to avoid the lens approaching a hemisphere, which increases the processing difficulty.

[0048] For a further optimized solution, f1 of the first lens 2 is -0.6 mm to -0.7 mm, R1 = ∞ mm, R2 = 0.5 mm to 0.6 mm, N d = 1.8 to 1.85, V d = 46 to 47, D1 = 0.30 mm to 0.35 mm, L1 = 0.05 mm to 0.1 mm;

[0049] Among them, f1 represents the focal length of the first lens 2; R1 represents the radius of curvature of the front surface of the lens; R2 represents the radius of curvature of the rear surface of the lens; N d represents the refractive index of the lens material with respect to the d light; V d represents the Abbe number of the lens material with respect to the d light; D1 represents the thickness of the first lens 2, and L1 represents the air gap of the first lens 2.

[0050] Furthermore, the parameters of the first lens 2 are preferably f1 = -0.65 mm, R1 = ∞ mm, R2 = 0.53 mm, N d = 1.82, V d = 46.6, D1 = 0.31 mm, L1 = 0.08 mm.

[0051] For a further optimized solution, f2 of the second lens 3 is 1.6 mm to 1.65 mm, R1 = 1.3 mm to 1.4 mm, R2 = ∞ mm, N d = 1.8 to 1.85, V d = 20 to 23, D2 = 0.5 mm to 0.6 mm, L2 = 0.02 mm to 0.04 mm;

[0052] Among them, f2 represents the focal length of the second lens 3; R1 represents the radius of curvature of the front surface of the lens; R2 represents the radius of curvature of the rear surface of the lens; N d represents the refractive index of the lens material with respect to the d light; V d represents the Abbe number of the lens material with respect to the d light; D2 represents the thickness of the second lens 3, and L2 represents the air gap of the second lens 3.

[0053] Furthermore, the parameters of the second lens 3 are preferably f2 = 1.63 mm, R1 = 1.3 mm, R2 = ∞ mm, N d = 1.81, V d = 2.7, D2 = 0.55 mm, L2 = 0.02 mm.

[0054] For a further optimized solution, for the third lens 4, f3 = 0.6 mm - 0.70 mm, R1 = ∞ mm, R2 = -0.7 mm - -0.6 mm, N d = 1.85 - 1.9, V d = 40.5 - 41, D3 = 0.5 mm - 0.6 mm, L3 = 0.05 mm - 0.1 mm;

[0055] Among them, f3 represents the focal length of the third lens 4; R1 represents the front curvature radius of the lens; R2 represents the curvature radius of the rear surface of the lens; N d represents the refractive index of the lens material with respect to d light; V d represents the Abbe number of the lens material with respect to d light; D3 represents the thickness of the third lens 4, and L3 represents the air gap of the third lens 4.

[0056] Furthermore, the parameters of the third lens 4 are preferably f3 = 0.69 mm, R1 = ∞ mm, R2 = -0.61 mm, N d = 1.88, V d = 40.9, D3 = 0.6 mm, L3 = 0.05 mm.

[0057] For a further optimized solution, for the fourth lens 5, f4 = 1.1 mm - 1.2 mm, R1 = ∞ mm, R2 = -1.5 mm - -1 mm, N d = 1.9 - 1.95, V d = 32 - 32.5, D4 = 0.5 mm - 0.5 mm, L4 = 0.02 mm - 0.03 mm;

[0058] Among them, f4 represents the focal length of the fourth lens 5; R1 represents the front curvature radius of the lens; R2 represents the curvature radius of the rear surface of the lens; N d represents the refractive index of the lens material with respect to d light; V d represents the Abbe number of the lens material with respect to d light; D4 represents the thickness of the fourth lens 5, and L4 represents the air gap of the fourth lens 5.

[0059] Furthermore, the parameters of the fourth lens 5 are preferably f4 = 1.14 mm, R1 = ∞ mm, R2 = -1 mm, N d = 1.95, V d = 32.3, D4 = 0.51 mm, L4 = 0.025 mm.

[0060] For a further optimized solution, for the fifth lens 6, f5 = -0.85 mm - -0.8 mm, R1 = -0.8 mm - -0.75 mm, R2 = ∞ mm, N d = 1.95 - 1.98, V d= 17.9 - 18, D5 = 0.5 mm - 0.5 mm, L5 = 0.03 mm - 0.035 mm;

[0061] Among them, f5 represents the focal length of the fifth lens 6; R1 represents the front curvature radius of the lens; R2 represents the curvature radius of the rear surface of the lens; N d represents the refractive index of the lens material with respect to d light; V d represents the Abbe number of the lens material with respect to d light; D5 represents the thickness of the fifth lens 6, and L5 represents the air gap of the fifth lens 6.

[0062] Furthermore, the parameters of the fifth lens 6 are preferably f5 = -0.82 mm, R1 = -0.79 mm, R2 = ∞ mm, N d = 1.95, V d = 17.9, D5 = 0.52 mm, L5 = 0.311 m.

[0063] Furthermore, the air gap mentioned above for the plano-convex lens refers to the distance from the vertex of the convex surface to the edge of the lens.

[0064] Furthermore, the wavelength of the d light mentioned above is 587.6 nm.

[0065] For a further optimized solution, the thickness of the first gap is 0.08 mm - 0.09 mm; the thickness of the second gap is 0.01 mm - 0.03 mm; the thickness of the third gap is 0.05 mm - 0.06 mm, and the thickness of the fourth gap is 0.02 mm - 0.03 mm. The first gap 7 refers to the space between the two adjacent sides of the first lens 2 and the second lens 3, the second gap 8 refers to the space between the two adjacent sides of the second lens 3 and the third lens 4, the third gap 9 refers to the space between the two adjacent sides of the third lens 4 and the fourth lens 5, and the fourth gap 10 refers to the space between the two adjacent sides of the fourth lens 5 and the fifth lens 6; the first gap 7, the second gap 8, the third gap 9, and the fourth gap 10 are used to position the first lens 2, the second lens 3, the third lens 4, the fourth lens 5, and the fifth lens 6.

[0066] Furthermore, the thickness dimension of the first gap 7 is preferably 0.086 mm, the thickness dimension of the second gap 8 is preferably 0.02 mm, the thickness dimension of the third gap 9 is preferably 0.05 mm, and the thickness dimension of the fourth gap 10 is preferably 0.026 mm.

[0067] For a further optimized solution, the curved surfaces of the plano-concave lens and the plano-convex lens are spherical and aspherical.

[0068] For a further optimized solution, the material of the sleeve 1 is a non-toxic flexible material. The non-toxic flexible material can prevent breakage caused by excessive stiffness during use and also prevent poisoning of the users; at the same time, it also needs to have the properties of acid resistance, alkali resistance and corrosion resistance in the use environment.

[0069] Usage method:

[0070] Prepare the first lens 2, the second lens 3, the third lens 4, the fourth lens 5 and the fifth lens 6 according to the parameters, and then install the first lens 2, the second lens 3, the third lens 4, the fourth lens 5 and the fifth lens 6 in the sleeve 1 in sequence according to the parameters provided above to complete the installation.

[0071] Fix and connect the installed sleeve 1 with the light source of the endoscope and connect them. Turn on the light source. The light emitted by the light source is reflected after irradiating the object, diverges on the plane of the first lens 2. After divergence by the first lens 2, it then passes through the second lens 3, the third lens 4 and the fourth lens 5 in sequence to form a highly concentrated beam, irradiates on the fifth lens 6 and then diverges, and finally exits from the plane of the fifth lens 6 and finally forms an image on the receiving terminal (not shown in the figure).

[0072] The structure of the present invention is simple. The final finished endoscope has a small diameter, high applicability, high resistance to various adverse environments and a long service life; the imaging is clearer, the distortion rate is low, which is more beneficial to medical applications and industrial applications.

[0073] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0074] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A small-sized optical endoscope, characterized in that: It includes a sleeve, and a lens group is embedded in the sleeve; The lens group is composed of a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged in the optical path in sequence; the diameters of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all not greater than 1 mm; A first interval is provided between the first lens and the second lens, a second interval is provided between the second lens and the third lens, a third interval is provided between the third lens and the fourth lens, and a fourth interval is provided between the fourth lens and the fifth lens; For the first lens, f1 = -0.6 mm - -0.7 mm, R1 = ∞ mm, R2 = 0.5 mm - 0.6 mm, Nd = 1.8 - 1.85, Vd = 46 - 47, D1 = 0.30 mm - 0.35 mm, L1 = 0.05 mm - 0.1 mm; Wherein, f1 represents the focal length of the first lens; R1 represents the front curvature radius of the lens; R2 represents the curvature radius of the rear surface of the lens; Nd represents the refractive index of the lens material with respect to d light; Vd represents the Abbe number of the lens material with respect to d light; D1 represents the thickness of the first lens, and L1 represents the air interval of the first lens; For the second lens, f2 = 1.6 mm - 1.65 mm, R3 = 1.3 mm - 1.4 mm, R4 = ∞ mm, Nd = 1.8 - 1.85, Vd = 22 - 23, D2 = 0.5 mm - 0.6 mm, L2 = 0.02 mm - 0.04 mm; Wherein, f2 represents the focal length of the second lens; R3 represents the front curvature radius of the lens; R4 represents the curvature radius of the rear surface of the lens; Nd represents the refractive index of the lens material with respect to d light; Vd represents the Abbe number of the lens material with respect to d light; D2 represents the thickness of the second lens, and L2 represents the air interval of the second lens; For the third lens, f3 = 0.6 mm - 0.70 mm, R5 = ∞ mm, R6 = -0.7 mm - -0.6 mm, Nd = 1.85 - 1.9, Vd = 40.5 - 41, D3 = 0.5 mm - 0.6 mm, L3 = 0.05 mm - 0.1 mm; Wherein, f3 represents the focal length of the third lens; R5 represents the front curvature radius of the lens; R6 represents the curvature radius of the rear surface of the lens; Nd represents the refractive index of the lens material with respect to d light; Vd represents the Abbe number of the lens material with respect to d light; D3 represents the thickness of the third lens, and L3 represents the air interval of the third lens; For the fourth lens, f4 = 1.1 mm - 1.2 mm, R7 = ∞ mm, R8 = -1.5 mm - -1 mm, Nd = 1.9 - 1.95, Vd = 32 - 32.5, D4 = 0.5 mm - 0.55 mm, L4 = 0.02 mm - 0.03 mm; Among them, f4 represents the focal length of the fourth lens; R7 represents the front curvature radius of the lens; R8 represents the curvature radius of the rear surface of the lens; Nd represents the refractive index of the lens material with respect to d light; Vd represents the Abbe number of the lens material with respect to d light; D4 represents the thickness of the fourth lens, and L4 represents the air gap of the fourth lens; For the fifth lens, f5 = -0.85 mm to -0.8 mm, R9 = -0.8 mm to -0.75 mm, R10 = ∞ mm, Nd = 1.95 - 1.98, Vd = 17.9 - 18, D5 = 0.5 mm to 0.55 mm, L5 = 0.3 mm to 0.35 mm; Among them, f5 represents the focal length of the fifth lens; R9 represents the front curvature radius of the lens; R10 represents the curvature radius of the rear surface of the lens; Nd represents the refractive index of the lens material with respect to d light; Vd represents the Abbe number of the lens material with respect to d light; D5 represents the thickness of the fifth lens, and L5 represents the air gap of the fifth lens.

2. The small-sized optical endoscope according to claim 1, wherein: The thickness of the first interval is 0.08 mm to 0.09 mm; the thickness of the second interval is 0.01 mm to 0.03 mm; the thickness of the third interval is 0.05 mm to 0.06 mm, and the thickness of the fourth interval is 0.02 mm to 0.03 mm.

Images