Endoscope objective lens

Abstract

The application provides an endoscope objective lens, and relates to the technical field of medical devices, which comprises, from the object side to the image side, a first spherical lens with negative optical power, a second spherical lens with positive optical power, a third spherical lens with negative optical power, a fourth spherical lens with positive optical power, a fifth spherical lens with positive optical power, a filter and a protective glass; the incident surface of the first spherical lens towards the object side comprises a plurality of different coating areas, the coating areas have different filter films, and the field angles of the plurality of coating areas are different. Through the shape, optical power and related parameter settings of each spherical lens, the endoscope objective lens has the advantages of a large field angle, miniaturization and a large depth of field, and through the partition coating, the transmittance curve and the reflectivity curve caused by the change of the incident field angle are reduced, the light of the cut-off laser band is blocked, the anti-laser effect of the coating is ensured, and under the condition of no laser, the color deviation during the imaging of the large field angle is eliminated, and the image quality is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, in particular to an endoscope objective. BACKGROUND

[0002] In the medical field, an endoscope as an examination and treatment device can help doctors effectively determine the lesion area and lesion degree in the body cavity. With the development and progress of science and technology, the requirements for endoscopes are becoming higher and higher, such as the need for endoscopes to have a larger field of view angle or higher optical resolution, so as to be able to observe the lesion area more carefully and accurately, so as to determine the benignity and malignancy of the lesion.

[0003] In addition, laser technology also plays an important role in the diagnosis and treatment of endoscopes. Laser treatment of endoscopes is an advanced medical method combining endoscope technology and laser technology, and is widely used in the diagnosis and treatment of various diseases. Laser treatment of endoscopes uses the high energy and precise focusing characteristics of laser, and directly transmits laser to the lesion site through the endoscope to achieve precise treatment of the lesion tissue.

[0004] The existing endoscope objective system has technical challenges in realizing large field of view angle, miniaturization and large depth of field. For example, an ultra-large field of view angle has important application value for endoscopic clinical observation, especially for observing the side folds of the intestinal wall. However, the existing technology is difficult to ensure high definition while realizing an ultra-large field of view angle. When the endoscope is combined with laser for treatment, the laser (wavelength 980nm or wavelength 1064nm, etc.) incident to the camera element will cause the endoscope image to produce a halo, affecting the image quality. SUMMARY

[0005] The purpose of the embodiments of the present application is to provide an endoscope objective with the functions of large field of view angle, large depth of field and high quality image.

[0006] In one aspect of the embodiments of the present application, an endoscope objective is provided, comprising: a first spherical lens with negative focal power, a second spherical lens with positive focal power, a third spherical lens with negative focal power, a fourth spherical lens with positive focal power, a fifth spherical lens with positive focal power, a filter and a protective glass arranged in order from the object side to the image side; the incident surface of the first spherical lens towards the object side comprises a plurality of different coating areas, the coating areas have different filter films, and the field of view angles of the plurality of coating areas are different.

[0007] Optionally, the number of coating areas is three, and the field of view angles of the three coating areas are 0-85°, 85°-130° and ≥130° respectively.

[0008] Optionally, a diaphragm is further arranged between the second spherical lens and the third spherical lens, and the diaphragm is symmetrical along the optical axis direction.

[0009] Optionally, the refractive index of the first spherical lens is 1.7 < Nd1 < 1.9, and the Abbe number is 70 < Vd1 < 80.

[0010] The refractive index of the second spherical lens is 1.8 < Nd2 < 2.0, and the Abbe number is 30 < Vd2 < 40.

[0011] The refractive index of the third spherical lens is 1.8 < Nd3 < 2.0, and the Abbe number is 20 < Vd3 < 30.

[0012] The refractive index of the fourth spherical lens is 1.4 < Nd4 < 1.6, and the Abbe number is 60 < Vd4 < 85.

[0013] The refractive index of the fifth spherical lens is 1.8 < Nd5 < 2.0, and the Abbe number is 10 < Vd5 < 25.

[0014] Optionally, the endoscope objective lens satisfies: 0.9 < |f / f1| < 1.0, 0.4 < |f / f2| < 0.5, 0.2 < |f / f3| < 0.3, 0.5 < |f / f4| < 0.6, and 0.7 < |f / f5| < 0.8; f is the effective focal length of the endoscope objective lens, f1 is the focal length of the first spherical lens, f2 is the focal length of the second spherical lens, f3 is the focal length of the third spherical lens, f4 is the focal length of the fourth spherical lens, and f5 is the focal length of the fifth spherical lens.

[0015] Optionally, the fourth spherical lens and the fifth spherical lens are cemented, the image side surface of the fourth spherical lens is a convex surface, the object side surface of the fifth spherical lens is a concave surface, and the fourth spherical lens and the fifth spherical lens are cemented through the convex surface and the concave surface.

[0016] Optionally, the endoscope objective lens satisfies: 2 < |f2 / f1| < 2.2, 0 < |f3 / f45| < 0.2, 0.1 < f / (f1+f2+f3+f4+f5) < 0.3, and 0 < f / (f1+f2+f45) < 0.1; f45 is the combined focal length of the fourth spherical lens and the fifth spherical lens.

[0017] Optionally, the endoscope objective lens satisfies: |D2 / R2| ≤ 1.8; wherein D2 represents the aperture of the exit surface of the first spherical lens, and R2 represents the curvature radius of the exit surface of the first spherical lens.

[0018] Optionally, the endoscope objective lens satisfies: 2.5≤TTL / (d1+d2+d3)≤4; wherein, d1 represents the thickness of the first spherical lens, d2 represents the thickness of the second spherical lens, d3 represents the thickness of the third spherical lens, and TTL represents the total length of the endoscope objective lens.

[0019] Optionally, the effective focal length f of the endoscope objective lens is 0.8-1.0 mm, the ratio of the effective focal length to the entrance pupil diameter FNO is ≤6, the total length TTL of the endoscope objective lens is ≤6.0, and the maximum optical aperture of the endoscope objective lens is ≤2.2.

[0020] The endoscope objective lens provided by the embodiment of the present application comprises, sequentially arranged from the object side to the image side, a first spherical lens with negative optical power, a second spherical lens with positive optical power, a third spherical lens with negative optical power, a fourth spherical lens with positive optical power, a fifth spherical lens with positive optical power, a filter, and a protective glass; the entrance surface of the first spherical lens towards the object side comprises a plurality of different coating areas, the coating areas have different filter films, and the field angles of the plurality of coating areas are different.

[0021] By reasonably controlling the shapes, optical powers, and related parameter relationships of the spherical lenses, the endoscope objective lens of the present application can well correct chromatic aberration, astigmatism, coma, and field curvature, so that the endoscope objective lens has the advantages of large field angle, miniaturization, and large depth of field, to meet the demand of the medical field for high-performance endoscope objective lenses. The plurality of coating areas with different field angles are arranged on the entrance surface of the first spherical lens, so that the partition coating is realized, the transmittance curve and the reflectivity curve caused by the change of the incident field angle are reduced, the light of the laser wavelength band is cut off, the anti-laser effect of the coating is ensured, and the color deviation during the imaging of the large field angle is eliminated, and the image quality is improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0023] Figure 1 is a structural schematic diagram of the endoscope objective lens provided by the embodiment;

[0024] Figure 2 is a coating area distribution diagram of the entrance surface of the first spherical lens of the endoscope objective lens provided by the embodiment;

[0025] Figure 3is a MTF curve diagram of the endoscope objective provided in the embodiment under visible light;

[0026] Figure 4 is an axial chromatic aberration diagram of the endoscope objective provided in the embodiment under visible light;

[0027] Figure 5 is an axial chromatic aberration curve diagram of the endoscope objective provided in the embodiment under visible light.

[0028] Figure legend: 1-first spherical lens; 1a-first coating area; 1b-second coating area; 1c-third coating area; 2-second spherical lens; 3-third spherical lens; 4-fourth spherical lens; 5-fifth spherical lens; 6-protective glass; 7-diaphragm. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.

[0030] In the description of the present application, it should be noted that the positions or location relationships indicated by the terms "inner", "outer" and the like are based on the positions or location relationships shown in the drawings, or the positions or location relationships in which the products of the present application are usually placed, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements must have a particular position, be constructed and operated in a particular position, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only used for differentiation and description, and cannot be understood as indicating or implying relative importance.

[0031] It should also be noted that, unless otherwise explicitly specified and limited, the terms "provided", "connected" should be understood broadly, for example, it can be fixedly connected, or detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0032] When the endoscope is used in combination with a laser, the laser incident to the camera element will cause the endoscope image to produce a halo; and in order to prevent such halo of the endoscope image, it is necessary to add a filter film on the optical system, and the function of the filter film is to cut off the wavelength range of the laser that produces the halo.

[0033] However, endoscopes generally require a large field of view, especially gastroscopes; in the case of using a reflective filter film, as the incident field of view angle increases, the working wavelength of the filter film will move to the short-wave direction. This is because the change of the incident field of view angle causes the change of the optical path of light in the film, thereby affecting the interference condition of the film, so that the spectral characteristics at the originally designed specific wavelength are deviated.

[0034] Moreover, the change of the incident field of view angle will change the transmittance curve and the reflectance curve. Generally, when the incident field of view angle increases, the transition zone between the cutoff point and the high transmittance point of the filter film will be widened or narrowed, and the transmittance and the cutoff depth (OD value) will be reduced accordingly; the increase of the incident field of view angle will cause the reflectance of the wavelength range requiring high reflectance to decrease.

[0035] Therefore, with reference to Figure 1 The endoscope objective lens provided by the embodiments of the present application comprises: a first spherical lens 1 with negative focal power, a second spherical lens 2 with positive focal power, a third spherical lens 3 with negative focal power, a fourth spherical lens 4 with positive focal power, a fifth spherical lens 5 with positive focal power, a filter film (not shown in the figure) and a protective glass 6 arranged in sequence from the object side to the image side; the incident surface of the first spherical lens 1 towards the object side comprises a plurality of different film-coated areas, the film-coated areas have different filter films, the different filter films can be obtained by coating film layers with different thicknesses and different materials, and the field angles of the plurality of film-coated areas are different, wherein the field angle is the incident field of view angle.

[0036] The first spherical lens 1, the second spherical lens 2, the third spherical lens 3, the fourth spherical lens 4, the fifth spherical lens 5, the filter film and the protective glass 6 are arranged in sequence along the optical axis, and the incident light passes through the above-mentioned elements in sequence.

[0037] Moreover, the incident surface of the first spherical lens 1 of the present application is divided into a plurality of different film-coated areas, Figure 2 In the example of the present application, the incident surface of the first spherical lens 1 is divided into three film-coated areas, the field of view angle of the first film-coated area 1a is 0-85°, the field of view angle of the second film-coated area 1b is 85°-130°, and the field of view angle of the third film-coated area 1c is ≥130°.

[0038] Of course, the number of film-coated areas can also be set to other numbers according to the situation, and the field of view angle of each film-coated area is not limited to the above-mentioned field of view angle, and can be selected according to actual needs, which will not be described here.

[0039] The application controls the shape, optical power and related parameter relationship of each spherical lens, so that the endoscope objective lens of the application can correct chromatic aberration, astigmatism, coma, and field curvature well, so that the endoscope objective lens has the advantages of large field angle, miniaturization and large depth of field, to meet the demand of the medical field for high-performance endoscope objective lens.

[0040] In addition, the application sets a plurality of coated areas with different field angles on the incident surface of the first spherical lens 1, each coated area has a different filter film, which can reduce the change of transmittance curve and reflectance curve caused by the change of incident field angle, and further cut off the light of the laser waveband, to ensure the anti-laser effect of the coating; and under the working condition without laser, the color deviation during imaging of large field angle is eliminated, and the image quality is improved.

[0041] In addition, a diaphragm 7 is arranged in the middle of the endoscope objective lens, the diaphragm 7 is symmetrical left and right along the optical axis direction, which is beneficial to correct the off-axis aberration of the endoscope objective lens, and the diaphragm 7 is located between the second spherical lens 2 and the third spherical lens 3. Figure 1

[0042] For the specific parameters of each spherical lens, see the following settings;

[0043] The refractive index of the first spherical lens 1 is 1.7 < Nd1 < 1.9, and the Abbe number is 70 < Vd1 < 80;

[0044] The refractive index of the second spherical lens 2 is 1.8 < Nd2 < 2.0, and the Abbe number is 30 < Vd2 < 40;

[0045] The refractive index of the third spherical lens 3 is 1.8 < Nd3 < 2.0, and the Abbe number is 20 < Vd3 < 30;

[0046] The refractive index of the fourth spherical lens 4 is 1.4 < Nd4 < 1.6, and the Abbe number is 60 < Vd4 < 85;

[0047] The refractive index of the fifth spherical lens 5 is 1.8 < Nd5 < 2.0, and the Abbe number is 10 < Vd5 < 25.

[0048] The endoscope objective lens satisfies: 0.9 < |f / f1| < 1.0, 0.4 < |f / f2| < 0.5, 0.2 < |f / f3| < 0.3, 0.5 < |f / f4| < 0.6, and 0.7 < |f / f5| < 0.8; f is the effective focal length of the endoscope objective lens, f1 is the focal length of the first spherical lens 1, f2 is the focal length of the second spherical lens 2, f3 is the focal length of the third spherical lens 3, f4 is the focal length of the fourth spherical lens 4, and f5 is the focal length of the fifth spherical lens 5.

[0049] ​Further, the fourth spherical lens 4 and the fifth spherical lens 5 are cemented, the image side surface of the fourth spherical lens 4 is a convex surface, the object side surface of the fifth spherical lens 5 is a concave surface, and the fourth spherical lens 4 and the fifth spherical lens 5 are cemented through the convex surface and the concave surface.

[0050] The endoscope objective lens also satisfies: 2<|f2 / f1|<2.2, 0<|f3 / f45|<0.2, 0.1< f / (f1+f2+f3+f4+f5)<0.3, 0< f / (f1+f2+f45)<0.1; f45 is the combined focal length of the fourth spherical lens 4 and the fifth spherical lens 5.

[0051] The endoscope objective lens also satisfies: |D2 / R2|≤1.8; wherein D2 represents the aperture of the exit surface of the first spherical lens 1, and R2 represents the curvature radius of the exit surface of the first spherical lens 1.

[0052] The endoscope objective lens also satisfies: 2.5≤TTL / (d1+d2+d3)≤4;

[0053] Wherein d1 represents the thickness of the first spherical lens 1, d2 represents the thickness of the second spherical lens 2, d3 represents the thickness of the third spherical lens 3, and TTL represents the total length of the endoscope objective lens.

[0054] In the embodiment of the present application, the effective focal length f of the endoscope objective lens is 0.8-1.0 mm, the ratio of the effective focal length to the entrance pupil diameter FNO≤6, TTL≤6.0, and the maximum optical aperture≤2.2.

[0055] Through the above setting, the endoscope objective lens provided by the embodiment of the present application has a full field angle of the optical system≥170°, and the designed depth of field range is 3 mm-100 mm.

[0056] The following table 1 lists the parameters of each element:

[0057] Table 1

[0058]

[0059] Figure 3 The MTF curve diagram of the endoscope objective lens under visible light is shown in FIG. 6. Figure 3 As can be seen from FIG. 6, the full field MTF value of the endoscope objective lens is greater than 0.1 when the spatial frequency is 220 l p / mm, the imaging quality is excellent, and the resolution of the lens is high.

[0060] Figure 4 The sagittal chromatic aberration diagram of the endoscope objective lens under visible light is shown in FIG. 7. Figure 5 The sagittal chromatic aberration curve diagram of the endoscope objective lens under visible light is shown in FIG. 8. Figure 5It can be seen that the color aberration of the vertical axis is less than 1 um, the color aberration is small, and the image color restoration is high.

[0061] The above only is the embodiment of the present application, and does not limit the protection scope of the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An endoscope objective, characterized in that, It consists of: a first spherical lens with negative optical power, a second spherical lens with positive optical power, a third spherical lens with negative optical power, a fourth spherical lens with positive optical power, a fifth spherical lens with positive optical power, a filter, and a protective glass, arranged sequentially from the object side to the image side; the incident surface of the first spherical lens facing the object side includes multiple different coated areas, each coated area having a different filter film, and the field of view of the multiple coated areas being different; The fourth spherical lens and the fifth spherical lens are cemented together. The image-side surface of the fourth spherical lens is convex, and the object-side surface of the fifth spherical lens is concave. The fourth spherical lens and the fifth spherical lens are cemented together through the convex surface and the concave surface. The endoscope objective lens satisfies: 2 < |f2 / f1| < 2.2, 0 < |f3 / f45| < 0.2, 0.1 < f / (f1+f2+f3+f4+f5) < 0.3, 0 < f / (f1+f2+f45) < 0.1; f45 is the combined focal length of the fourth and fifth spherical lenses; The endoscope objective lens satisfies: 2.5≤TTL / (d1+d2+d3)≤4; where d1 represents the thickness of the first spherical lens, d2 represents the thickness of the second spherical lens, d3 represents the thickness of the third spherical lens, and TTL represents the total length of the endoscope objective lens.

2. The endoscope objective according to claim 1, characterized in that, The number of coating areas is three, and the field of view of the three coating areas are 0-85°, 85°-130°, and ≥130°, respectively.

3. The endoscope objective according to claim 1, characterized in that, An aperture stop is also provided between the second spherical lens and the third spherical lens, and the aperture stop is symmetrical along the optical axis.

4. The endoscope objective according to any one of claims 1 to 3, characterized in that, The refractive index of the first spherical lens is 1.7 < Nd1 < 1.9, and the Abbe number is 70 < Vd1 < 80. The refractive index of the second spherical lens is 1.8 < Nd2 < 2.0, and the Abbe number is 30 < Vd2 < 40. The refractive index of the third spherical lens is 1.8 < Nd3 < 2.0, and the Abbe number is 20 < Vd3 < 30. The refractive index of the fourth spherical lens is 1.4 < Nd4 < 1.6, and the Abbe number is 60 < Vd4 < 85. The refractive index of the fifth spherical lens is 1.8 < Nd5 < 2.0, and the Abbe number is 10 < Vd5 < 25.

5. The endoscope objective according to any one of claims 1 to 3, characterized in that, The endoscope objective lens satisfies the following conditions: 0.9 < |f / f1| < 1.0, 0.4 < |f / f2| < 0.5, 0.2 < |f / f3| < 0.3, 0.5 < |f / f4| < 0.6, 0.7 < |f / f5| < 0.8; f is the effective focal length of the endoscope objective lens, f1 is the focal length of the first spherical lens, f2 is the focal length of the second spherical lens, f3 is the focal length of the third spherical lens, f4 is the focal length of the fourth spherical lens, and f5 is the focal length of the fifth spherical lens.

6. The endoscope objective according to any one of claims 1 to 3, characterized in that, The endoscope objective lens satisfies: |D2 / R2|≤1.8; where D2 represents the aperture of the exit surface of the first spherical lens, and R2 represents the radius of curvature of the exit surface of the first spherical lens.

7. The endoscope objective according to any one of claims 1 to 3, characterized in that, The effective focal length f of the endoscope objective is 0.8 to 1.0 mm, the ratio of the effective focal length to the entrance pupil diameter FNO ≤ 6, the total length TTL of the endoscope objective ≤ 6.0, and the maximum optical aperture of the endoscope objective ≤ 2.2.

Images