Medical endoscope optical imaging system

Abstract

The application relates to a medical endoscope optical imaging system, which comprises, in sequence from the object side to the image side along the optical axis, an aperture diaphragm, a first lens, a second lens, a third lens, a fourth lens and an infrared filter; the total focal length of the optical imaging system is EFL; the total length of the optical imaging system is TTL; the maximum effective half aperture of the first lens, the second lens, the third lens and the fourth lens is MSD; the focal length of the first lens is f1; the image height of the optical imaging system is IMH; the f1, the TTL, the EFL, the MSD and the IMH satisfy the following relationships: 0.52 < f1 / EFL < 0.61; 1.7 < TTL / EFL < 1.9; 0.7 < MSD / IMH < 0.78. The above scheme can realize the purposes of miniaturization design and large depth of field while having high pixels.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, in particular to a medical endoscope optical imaging system. BACKGROUND

[0002] A medical endoscope is a kind of medical device which can enter the human body cavity through natural orifice or surgical incision to achieve the purpose of observation. With the development of microelectronic technology and process, the medical endoscope is constantly achieving high pixelization to obtain high-resolution images. On the other hand, since the scope of the medical endoscope needs to be inserted into the human body cavity for observation, it is required that the medical endoscope should have the characteristics of miniaturization and large depth of field in addition to clear imaging. SUMMARY

[0003] In order to solve the above problems, the purpose of the present application is to provide an endoscope optical imaging system which can achieve the purposes of miniaturization design and large depth of field while having high pixels.

[0004] A medical endoscope optical imaging system, comprising an aperture stop, a first lens, a second lens, a third lens, a fourth lens and an infrared filter which are sequentially arranged along the optical axis from the object side to the image side;

[0005] The first lens is a positive lens, and the side facing the image side is convex. The first lens has at least one aspheric surface;

[0006] The second lens is a double-concave negative lens. The second lens has at least one aspheric surface;

[0007] The third lens is a positive lens, and the side facing the object side is concave, and the side facing the image side is convex. The third lens has at least one aspheric surface;

[0008] The fourth lens is a negative lens, and the side facing the image side is concave. The fourth lens has at least one aspheric surface;

[0009] Wherein, the total focal length of the optical imaging system is EFL; the total length of the optical imaging system is TTL; the maximum effective half aperture of the first lens, the second lens, the third lens and the fourth lens is MSD; the focal length of the first lens is f1; the image height of the optical imaging system is IMH; the f1, TTL, EFL, MSD and IMH satisfy the following relationships: 0.52 < f1 / EFL < 0.61; 1.7 < TTL / EFL < 1.9; 0.7 < MSD / IMH < 0.78.

[0010] As preferred, the medical endoscope optical imaging system further comprises a front protective cover and a chip protective cover, the front protective cover is located at the first lens object side, a chip set composed of the first lens, the second lens, the third lens, the fourth lens and the infrared filter is connected with the control chip, the chip protective cover is connected with the control chip, and the aperture diaphragm is located between the front protective cover and the first lens.

[0011] As preferred, the front protective cover and the chip protective cover are made of glass.

[0012] As preferred, the total length TTL of the optical imaging system is the distance from the front protective cover to the image plane.

[0013] As preferred, the materials of the first lens, the second lens, the third lens and the fourth lens are plastic lenses.

[0014] The present application can realize large target surface, large depth of field, realize high-resolution imaging in a wider range, and has good picture uniformity and color consistency, and can better restore the characteristics of the scene. Moreover, the optical imaging system has the characteristics of miniaturization, and can greatly reduce the pain of patients during medical endoscope treatment. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is the optical system structure diagram of embodiment 1 of the present application;

[0016] Figure 2 is the relative luminance curve diagram of embodiment 1 of the present application;

[0017] Figure 3 is the distortion curve diagram of embodiment 1 of the present application;

[0018] Figure 4 is the light fan curve diagram of embodiment 1 of the present application;

[0019] Figure 5 is the MTF curve diagram of embodiment 1 of the present application;

[0020] Figure 6 is the optical system structure diagram of embodiment 2 of the present application;

[0021] Figure 7 is the relative luminance curve diagram of embodiment 2 of the present application;

[0022] Figure 8 is the distortion curve diagram of embodiment 2 of the present application;

[0023] Figure 9 is the light fan curve diagram of embodiment 2 of the present application;

[0024] Figure 10 is the MTF curve diagram of embodiment 2 of the present application;

[0025] Figure 11 is a structure diagram of an optical system of Embodiment 3 of the present application;

[0026] Figure 12 is a relative luminance curve diagram of Embodiment 3 of the present application;

[0027] Figure 13 is a distortion curve diagram of Embodiment 3 of the present application;

[0028] Figure 14 is a light fan curve diagram of Embodiment 3 of the present application;

[0029] Figure 15 is an MTF curve diagram of Embodiment 3 of the present application;

[0030] Figure 16 is a structure diagram of an optical system of Embodiment 4 of the present application;

[0031] Figure 17 is a relative luminance curve diagram of Embodiment 4 of the present application;

[0032] Figure 18 is a distortion curve diagram of Embodiment 4 of the present application;

[0033] Figure 19 is a light fan curve diagram of Embodiment 4 of the present application;

[0034] Figure 20 is an MTF curve diagram of Embodiment 4 of the present application.

[0035] Reference signs:

[0036] front protective cover 1, aperture stop 2, first lens P1, second lens P2, third lens P3, fourth lens P4, infrared filter IR, chip protective cover 3. DETAILED DESCRIPTION

[0037] Embodiments of the present application are described in detail below.

[0038] The present application provides a medical endoscope optical imaging system, as shown in Figure 1 and Figure 6 which comprises, in order along the optical axis from the object side to the image side, an aperture stop 2, a first lens P1, a second lens P2, a third lens P3, a fourth lens P4 and an infrared filter IR;

[0039] The first lens P1 is a positive lens, and the side facing the image side is convex. The first lens has at least one aspheric surface or more;

[0040] The second lens P2 is a double-concave negative lens. The second lens has at least one aspheric surface or more;

[0041] The third lens P3 is a positive lens, the side facing the object is concave, the side facing the image is convex, and the third lens has at least one aspheric surface;

[0042] The fourth lens P4 is a negative lens, the side facing the image is concave, and the fourth lens has at least one aspheric surface;

[0043] Wherein, the total focal length of the optical imaging system is EFL; the total length of the optical imaging system is TTL; the maximum effective half aperture of the first lens P1, the second lens P2, the third lens P3 and the fourth lens P4 is MSD; the focal length of the first lens is f1; the image height of the optical imaging system is IMH; the f1, TTL, EFL, MSD and IMH satisfy the following relationships: 0.52 < f1 / EFL < 0.61; 1.7 < TTL / EFL < 1.9; 0.7 < MSD / IMH < 0.78.

[0044] The medical endoscope optical imaging system described above adopts four lenses, has small size, and the four lenses all have at least one aspheric surface, so that the endoscope has the characteristics of aspheric lenses and can present clearer imaging. The parameters in the optical imaging system are limited, so that the optical imaging system can realize large target surface and large depth of field, can realize high-resolution imaging in a farther range, and has the characteristics of miniaturization.

[0045] The medical endoscope optical imaging system described above further includes a front protective cover 1 and a chip protective cover 3. The front protective cover 1 is located on the object side of the first lens, and the chip protective cover 3 is located on the image side of the infrared filter. The front protective cover 1 protects the lenses; the lens group composed of the first lens P1, the second lens P2, the third lens P3, the fourth lens P4 and the infrared filter IR is connected with a control chip, the chip protective cover 3 is connected with the control chip and is used for protecting the control chip, and the control chip is a CMOS chip. In the embodiment, the chip protective cover 3 can cover the control chip once to better protect the control chip. The aperture stop is located between the front protective cover and the first lens, and the smaller the aperture of the aperture stop, the larger the depth of field. By setting the appropriate aperture of the aperture stop, the characteristics of large target surface and large depth of field can be realized. In the embodiment, the front protective cover 1 and the chip protective cover 3 are made of glass and have high hardness, so that good protection effect can be provided. The first lens P1, the second lens P2, the third lens P3 and the fourth lens P4 are made of plastic lenses and have the characteristics of low cost, light weight, not easy to break, strong anti-fog property and high light transmission. In the case of setting the front protective cover, the total length TTL of the optical imaging system refers to the distance from the front protective glass to the image plane.

[0046] The technical effects of the above structure are described below in combination with specific embodiments.

[0047] Embodiment 1:

[0048] The specific structure of the medical endoscope optical imaging system of this embodiment is shown in Figure 1 The selection conditions of this embodiment are: 0.52 < f1 / EFL < 0.61, 1.7 < TTL / EFL < 1.9, 0.7 < MSD / IMH < 0.78; the relative luminance curve is shown in Figure 2 , the distortion curve is shown in Figure 3 , the light fan curve is shown in Figure 4 , and the MTF curve is shown in Figure 5 The relationship of each part is shown in the following table:

[0049]

[0050] The surface conic coefficients K and aspheric coefficients of each surface of this embodiment are shown in the following table:

[0051] Surface No. 4 5 6 7 8 9 10 11 R -6.507 -0.626 -4.693 2.354 -5.503 -0.804 5.689 0.596 K 0 0.048 -11.309 2.229 18.138 -7.691 -4.303 -5.271 A4 -0.889 0.376 0.137 0.034 0.067 0.041 -0.056 -0.114 A6 -0.963 -1.676 -0.414 0.264 0.006 0.081 0.003 0.042 A8 -19.488 10.365 0.982 -0.499 0.646 0.047 0.036 -0.007 A10 0 -37.345 -5.734 -1.174 0.179 0.061 0.033 -0.003 A12 0 57.109 7.833 0.418 -2.649 -0.027 -0.040 -2.465E-05

[0052] Embodiment 2:

[0053] The specific structure of the medical endoscope optical imaging system of this embodiment is shown in Figure 6 The selection conditions of this embodiment are: 0.52 < f1 / EFL < 0.61, 1.7 < TTL / EFL < 1.9, 0.7 < MSD / IMH < 0.78; the relative luminance curve is shown in Figure 7 , the distortion curve is shown in Figure 8 , the light fan curve is shown in Figure 9 , and the MTF curve is shown in Figure 10 The relationship of each part is shown in the following table:

[0054]

[0055] The surface conic coefficients K and aspheric coefficients of each surface of this embodiment are shown in the following table:

[0056] Surface No. 4 5 6 7 8 9 10 11 R -12.147 -0.663 -3.757 2.573 -4.625 -1.062 2.941 0.671 K 0 0.088 -63.068 9.665 48.137 -10.295 -0.783 -4.942 A4 -0.941 0.198 0.183 0.080 -0.061 0.034 -0.019 -0.082 A6 -1.322 -1.396 0.261 0.448 -0.140 0.020 0.012 0.030 A8 -16.152 11.940 1.589 -0.613 0.903 0.032 0.011 -0.001 A10 0 -70.227 -23.853 -2.072 1.622 -0.020 0.007 0.001 A12 0 124.836 46.669 0.264 -3.064 0.042 -0.010 -0.002

[0057] Embodiment 3:

[0058] The specific structure of the medical endoscope optical imaging system of this embodiment is shown in Figure 11 The selection conditions of this embodiment are: 0.52 < f1 / EFL < 0.61, 1.7 < TTL / EFL < 1.9, 0.7 < MSD / IMH < 0.78; the relative luminance curve is shown in Figure 12 , the distortion curve is shown in Figure 13 , the light fan curve is shown in Figure 14 , and the MTF curve is shown in Figure 15 The relationship of each part is shown in the following table:

[0059]

[0060] The surface conic coefficients K and aspheric coefficients of this embodiment are shown in the following table:

[0061] Surface No. 4 5 6 7 8 9 10 11 R -40.387 -0.716 -3.612 2.677 -5.656 -0.980 2.976 0.669 K 0 0.224 -122.015 13.733 61.264 -8.712 -0.589 -5.012 A4 -0.848 0.244 0.188 0.116 -0.094 0.029 -0.016 -0.068 A6 -1. 712 -2.277 0.137 0.402 -0.129 0.014 0.013 0.024 A8 -10.495 12.553 0.116 -0.927 0.804 0.045 0.010 -5.588E-04 A10 0 -62.248 -16.606 -3.469 1.476 -2.039E-04 4.710E-03 1.721E-03 A12 0 106.892 37.263 3.077 -4.424 3.507E-02 -7.319E-03 -1.153E-03

[0062] Embodiment 4:

[0063] The specific structure of the medical endoscope optical imaging system of this embodiment is shown in Figure 16 . The selection conditions of this embodiment are: 0.52 < f1 / EFL < 0.61, 1.7 < TTL / EFL < 1.9, 0.7 < MSD / IMH < 0.78; the relative luminance curve is shown in Figure 17 , the distortion curve is shown in Figure 18 , the light fan curve is shown in Figure 19 , and the MTF curve is shown in Figure 20 . The relationship of each part is specifically shown in the following table:

[0064]

[0065] The surface conic coefficients K and aspheric coefficients of this embodiment are shown in the following table:

[0066] Surface No. 4 5 6 7 8 9 10 11 R 2.384 -1.045 -2.262 2.512 -6.318 -0.556 13.103 0.526 K 0 1.199 -48.665 11.701 101.542 -4.453 -92.104 -5.797 A4 -0.449 0.297 0.141 0.163 0.011 -0.229 -0.203 -0.223 A6 -0.351 -1.927 0.490 0.091 0.485 0.387 -0.081 0.068 A8 -2.579 14.020 1.157 0.035 0.229 -0.039 0.111 -0.015 A10 0 -82.653 -15.574 -2.918 -3.074 -0.508 0.060 -6.640E-03 A12 0 208.269 42.012 2.255 3.205 0.309 -0.029 3.569E-03

[0067] In summary, the optical imaging system of the present application can not only realize large target surface and large depth of field, but also realize high resolution imaging in a farther range. At the same time, the picture uniformity and color consistency are good, which can better restore the characteristics of the scene. Moreover, the optical imaging system also has the characteristics of miniaturization, which can greatly reduce the pain of patients during medical endoscope treatment.

[0068] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit it; although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A medical endoscope optical imaging system, characterized by, The aperture diaphragm, the first lens, the second lens, the third lens, the fourth lens and the infrared filter are sequentially arranged along the optical axis from the object side to the image side; The first lens is a positive lens, and the side facing the image side is a convex surface. The first lens has at least one aspheric surface; The second lens is a double-concave negative lens, and the second lens has at least one aspheric surface; The third lens is a positive lens, and the side facing the object side is a concave surface, and the side facing the image side is a convex surface. The third lens has at least one aspheric surface; The fourth lens is a negative lens, and the side facing the image side is a concave surface. The fourth lens has at least one aspheric surface; The total focal length of the optical imaging system is EFL; the total length of the optical imaging system is TTL; the maximum effective half aperture of the first lens, the second lens, the third lens and the fourth lens is MSD; the focal length of the first lens is f1; the image height of the optical imaging system is IMH; the f1, TTL, EFL, MSD and IMH satisfy the following relationships: 0.52 < f1 / EFL < 0.61; 1.7 < TTL / EFL < 1.9; 0.7 < MSD / IMH < 0.

78.

2. The medical endoscope optical imaging system according to claim 1, wherein The front protective cover and the chip protective cover are provided, the front protective cover is located on the object side of the first lens, the chip group composed of the first lens, the second lens, the third lens, the fourth lens and the infrared filter is connected with the control chip, the chip protective cover is connected with the control chip, and the aperture diaphragm is located between the front protective cover and the first lens.

3. The medical endoscope optical imaging system of claim 2, wherein, The front protective cover and the chip protective cover are made of glass.

4. The medical endoscope optical imaging system of claim 2, wherein, The total length of the optical imaging system TTL is the distance from the front protective cover to the image plane.

5. The medical endoscope optical imaging system of claim 1, wherein, The materials of the first lens, the second lens, the third lens and the fourth lens are plastic lenses.

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