Infrared endoscope objective optical system suitable for imaging of flowing blood

Abstract

The present invention provides an infrared endoscope objective optical system suitable for imaging flowing blood, characterized in that it comprises a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, arranged sequentially along the optical axis from the object plane to the image plane, wherein the first lens, the second lens, and the fourth lens and the fifth lens are all doublet lenses. By optimizing the lens structure, the present invention achieves a large field of view (up to 65°) and an F-number of 3.3 while ensuring a compact structure and a small number of lenses. The present invention can be well coupled with the subsequent imaging fiber bundle, and all lenses adopt a spherical structure, reducing processing difficulty and cost.

Description

Technical Field

[0001] The invention relates to an infrared endoscope objective optical system suitable for imaging flowing blood, belonging to the technical field of medical equipment. Background Art

[0002] Endoscopic technology, which combines modern optics, precision machinery, and electronic technology, has been widely used since its invention. It not only provides non-destructive testing in industrial production without disassembling or stopping equipment, but also has developed many categories in the medical field, such as oral endoscopes, laparoscopes, and ENT endoscopes, effectively improving the detection rate of lesions and post-operative recovery capabilities.

[0003] Endoscopes are usually placed in a low-scattering, weakly absorbing medium such as air, so using visible light as a light source can achieve excellent imaging effects, but this cannot meet the requirements of use in certain specific solution environments. In the medical field, with the continuous development of interventional surgery technology, people have begun to use near-infrared light as a light source for imaging in blood environments. Because the absorption and scattering coefficients of visible light in such media are large, it is difficult to achieve effective light transmission, and it is impossible to image the target substance. In order to solve this problem, relevant personnel have proposed a new endoscope based on infrared light sources. This endoscope uses infrared lasers in the near-infrared band as the light source of the endoscope, which realizes visualization in the blood environment.

[0004] Currently, the main endoscopes on the market mainly use visible light as the light source, and the related matching optical components such as objective lenses can only support visible light. This results in the lack of available objective lenses for endoscopes using infrared lasers as light sources. The composition of an optical imaging system is inseparable from the objective lens component. Summary of the Invention

[0005] The purpose of the present invention is to provide an objective lens component adapted for an infrared endoscope, which has a compact structure, low cost and operates in the near-infrared band.

[0006] In order to achieve the above-mentioned object, the technical solution of the present invention is to provide an infrared endoscope objective optical system suitable for imaging flowing blood, characterized in that it is composed of a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens, a sixth lens and a seventh lens arranged in sequence along the optical axis from the object plane to the image plane, wherein the first lens and the second lens as well as the fourth lens and the fifth lens are all doublet lenses; the side of the first lens facing the object plane is defined as the first surface, and the side facing the image plane is defined as the second surface, and the side of the second lens facing the object plane is defined as the second surface; the side of the second lens facing the image plane is defined as the third surface; the side of the third lens facing the object plane is defined as the fourth surface, and the side facing the image plane is defined as the fifth surface; the side of the fourth lens facing the object plane is defined as the sixth surface, and the side facing the image plane is defined as the seventh surface, and the side of the fifth lens facing the object plane is defined as the seventh surface; the side of the fifth lens facing the image plane is defined as the eighth surface; the side of the sixth lens facing the object plane is defined as the ninth surface, and the side facing the image plane is defined as the tenth surface; the side of the seventh lens facing the object plane is defined as the eleventh surface, and the side facing the image plane is defined as the twelfth surface, wherein:

[0007] The first lens has an optical power of , and is a plane lens, with both the first surface and the second surface being planes;

[0008] The second lens has a negative optical power, and the third surface is a concave surface with a radius of curvature equal to 1.401 mm;

[0009] The third lens has positive optical power, the fourth surface is a convex surface with a curvature radius of 17.626 mm, and the fifth surface 32 is a convex surface with a curvature radius of -2.376 mm.

[0010] The fourth lens has negative refractive power, the sixth surface is a concave surface with a curvature radius of -1.735 mm, and the seventh surface is a concave surface with a curvature radius of 11.271 mm.

[0011] The fifth lens has positive optical power, and the eighth surface is a convex surface with a radius of curvature equal to -3.384 mm;

[0012] The sixth lens has positive refractive power, the ninth surface is a convex surface with a curvature radius of 8.435 mm, and the tenth surface is a convex surface with a curvature radius of -15.917 mm.

[0013] The seventh lens has positive refractive power, the eleventh surface is a convex surface with a curvature radius equal to 3.798 mm, and the twelfth surface is a concave surface with a curvature radius equal to 13.831 mm.

[0014] Preferably, the focal length of the second lens is -2.881 mm; the focal length of the third lens is 2.682 mm; the focal length of the fourth lens is -2.735 mm; the focal length of the fifth lens is 4.516 mm; the focal length of the sixth lens is 9.360 mm; and the focal length of the seventh lens is 10.330 mm.

[0015] Preferably, the refractive index of the first lens is 1.448, and the center thickness is 0.500 mm; the refractive index of the second lens is 1.489, and the center thickness is 0.292 mm; the refractive index of the third lens is 1.87, and the center thickness is 4.402 mm; the refractive index of the fourth lens is 1.543, and the center thickness is 0.778 mm; the refractive index of the fifth lens is 1.605, and the center thickness is 1.607 mm; the refractive index of the sixth lens is 1.605, and the center thickness is 1.296 mm; and the refractive index of the seventh lens is 1.489, and the center thickness is 1.296 mm.

[0016] Preferably, the center thickness of the first lens is 0.500 mm; the center thickness of the second lens is 0.292 mm; the center thickness of the third lens is 4.402 mm; the center thickness of the fourth lens is 0.778 mm; the center thickness of the fifth lens is 1.607 mm; the center thickness of the sixth lens is 1.296 mm; and the center thickness of the seventh lens is 1.296 mm.

[0017] Preferably, the aperture of the aperture is less than 1 mm.

[0018] Preferably, the aperture size of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are all smaller than 5 mm, and the optical tube length is smaller than 25 mm.

[0019] Preferably, the operating wavelength band of the infrared endoscope objective optical system is 0.8-2.0 microns.

[0020] By optimizing the lens structure, the present invention achieves a large field of view (up to 65°) and an F-number of 3.3 while maintaining a compact structure and a small number of lenses. This also allows for excellent coupling with the subsequent imaging fiber bundle, and all lenses utilize a spherical structure, reducing manufacturing difficulty and cost.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] 1. Targeting the specialized working requirements of infrared endoscopes for blood flow, this paper designs and optimizes an adaptive objective optical system. Through ZEMAX simulation and based on imaging indicators that fully support near-infrared lasers in the near-infrared band, this system not only achieves effective coupling with subsequent imaging fiber bundles, but also maintains strict control over system size, resulting in a compact structure.

[0023] 2. The present invention designs an infrared endoscope objective optical system suitable for imaging blood flow, in which all lenses adopt a spherical design, which reduces the difficulty and cost of processing and is conducive to large-scale promotion and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram of an infrared endoscope objective optical system suitable for imaging flowing blood according to the present invention;

[0025] Figure 2 : is a simulation diagram of the MTF optical transfer function curve of the objective lens in an embodiment of the present invention;

[0026] Figure 3 : is a simulated diagram of the diffuse spots of the objective lens in an embodiment of the present invention;

[0027] Figure 4 This is a simulation diagram of the diffraction circle energy of the objective lens in an embodiment of the present invention.

[0028] In the figure: A is the object plane, B is the image plane, 1 is the first lens, 2 is the second lens, 3 is the third lens, 4 is the aperture, 5 is the fourth lens, 6 is the fifth lens, 7 is the sixth lens, 8 is the seventh lens, 11 is the first surface, 12 is the second surface, 21 is the third surface, 31 is the fourth surface, 32 is the fifth surface, 51 is the sixth surface, 52 is the seventh surface, 61 is the eighth surface, 71 is the ninth surface, 72 is the tenth surface, 81 is the eleventh surface, and 82 is the twelfth surface. DETAILED DESCRIPTION

[0029] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0030] The infrared endoscope objective optical system provided by the present invention has a structure as follows Figure 1 As shown, it consists of a first lens 1, a second lens 2, a third lens 3, an aperture 4, a fourth lens 5, a fifth lens 6, a sixth lens 7 and a seventh lens 8 which are arranged in sequence along the optical axis from the object plane A to the image plane B.

[0031] The first lens 1 and the second lens 2 are doublets, and the fourth lens 5 and the fifth lens 6 are doublets, which reduce system aberrations and improve imaging quality. The side of the first lens 1 facing the object plane is defined as the first surface 11, and the side facing the image plane is defined as the second surface 12. The side of the second lens 2 facing the object plane is defined as the second surface 12, and the side of the second lens 2 facing the image plane is defined as the third surface 21. The side of the third lens 3 facing the object plane is defined as the fourth surface 31, and the side facing the image plane is defined as the fifth surface 32. The side of the fourth lens 5 facing the object plane is defined as the sixth surface 51, and the side facing the image plane is defined as the seventh surface 52. The side of the fifth lens 6 facing the object plane is defined as the seventh surface 52, and the side of the fifth lens 6 facing the image plane is defined as the eighth surface 61. The side of the sixth lens 7 facing the object plane is defined as the ninth surface 71, and the side facing the image plane is defined as the tenth surface 72. The side of the seventh lens 8 facing the object plane is defined as the eleventh surface 81, and the side facing the image plane is defined as the twelfth surface 82.

[0032] The first lens 1 has a power of 0 and is a planar lens. Its first surface 11 and second surface 12 are both planar. The first lens 1 is made of SILICA with a refractive index of 1.448. The center thickness of the first lens 1 is 0.500 mm.

[0033] The second lens 2 has negative optical power and a focal length of -2.881 mm. Its third surface 21 is concave with a radius of curvature of 1.401 mm. The material used for the second lens 2 is N-PK52A with a refractive index of 1.489. The center thickness of the second lens 2 is 0.292 mm.

[0034] The third lens element 3 has positive optical power and a focal length of 2.682 mm. Its fourth surface 31 is convex with a radius of curvature of 17.626 mm, and its fifth surface 32 is convex with a radius of curvature of -2.376 mm. The third lens element 3 is made of SF66 with a refractive index of 1.876. The center thickness of the third lens element 3 is 4.402 mm.

[0035] The fourth lens element 5 has negative optical power and a focal length of -2.735 mm. Its sixth surface 51 is concave with a radius of curvature of -1.735 mm, and its seventh surface 52 is concave with a radius of curvature of 11.271 mm. The fourth lens element 5 is made of N-KZFS2 with a refractive index of 1.543. The center thickness of the fourth lens element 5 is 0.778 mm.

[0036] The fifth lens 6 has positive optical power and a focal length of 4.516 mm. Its eighth surface 61 is convex with a radius of curvature of -3.384 mm. The fifth lens 6 is made of N-PSK53A with a refractive index of 1.605. The center thickness of the fifth lens 6 is 1.607 mm.

[0037] The sixth lens element 7 has positive optical power and a focal length of 9.360 mm. Its ninth surface 71 is convex with a radius of curvature of 8.435 mm, and its tenth surface 72 is convex with a radius of curvature of -15.917 mm. The sixth lens element 7 is made of N-PSK53A with a refractive index of 1.605. The center thickness of the sixth lens element 7 is 1.296 mm.

[0038] The seventh lens element 8 has positive optical power and a focal length of 10.330 mm. Its eleventh surface 81 is convex with a radius of curvature of 3.798 mm, and its twelfth surface 82 is concave with a radius of curvature of 13.831 mm. The material of the seventh lens element 8 is N-PK52A with a refractive index of 1.489. The center thickness of the seventh lens element 8 is 1.296 mm.

[0039] The aperture of the aperture 4 is less than 1 mm.

[0040] The objective optical system operates in the 0.8-2.0 micron wavelength range, providing wide spectral coverage. To ensure a compact and compact structure, the apertures of the first lens 1, second lens 2, third lens 3, fourth lens 5, fifth lens 6, sixth lens 7, and seventh lens 8 are all less than 5 mm, and the optical tube length is less than 25 mm. When the object plane A is 5.000 mm from the first surface 11, the image plane B is located 1.371 mm behind the twelfth surface 82, and the image plane covers a diameter of 3 mm.

[0041] To simulate the liquid environment of the infrared endoscope to which the objective lens is adapted, the distance between object plane A and first surface 11 is set at 5 mm in this embodiment, and seawater with a refractive index of 1.329 is filled in between as a medium. The subsequent imaging fiber bundle is composed of 10,000 optical fibers with a diameter of 27.5 μm arranged in a hexagonal spiral.

[0042] like Figure 2 As shown, the MTF of the objective optical system disclosed in this embodiment is greater than 0.7 at the full field angle at a cutoff frequency of 30 lp / mm.

[0043] like Figure 3 As shown, the root mean square size of the diffuse spot of light received by the objective optical system disclosed in this embodiment at the imaging plane is less than 2.9 μm, which is smaller than the diameter of a single optical fiber in the imaging optical fiber bundle used later, 27.5 μm.

[0044] like Figure 4 As shown, the diffraction energy of the objective optical system in the present embodiment in the full field of view is higher than 91% within the radius of 13.75 μm of a single optical fiber, which fully ensures the efficiency of light energy transmission.

[0045] The above embodiment is only one implementation method of the present invention, but the implementation method of the present invention is not limited to the above embodiment. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. An infrared endoscope objective optical system suitable for imaging flowing blood, characterized in that: The optical system is composed of a first lens, a second lens, a third lens, an aperture, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, which are arranged in sequence along the optical axis from the object plane to the image plane, wherein the first lens and the second lens as well as the fourth lens and the fifth lens are all doublet lenses; the side of the first lens facing the object plane is defined as the first surface, and the side facing the image plane is defined as the second surface, and the side of the second lens facing the object plane is defined as the second surface; the side of the second lens facing the image plane is defined as the third surface; the side of the third lens facing the object plane is defined as the fourth surface, and the side facing the image plane is defined as the fifth surface; the side of the fourth lens facing the object plane is defined as the sixth surface, and the side facing the image plane is defined as the seventh surface, and the side of the fifth lens facing the object plane is defined as the seventh surface; the side of the fifth lens facing the image plane is defined as the eighth surface; the side of the sixth lens facing the object plane is defined as the ninth surface, and the side facing the image plane is defined as the tenth surface; the side of the seventh lens facing the object plane is defined as the eleventh surface, and the side facing the image plane is defined as the twelfth surface, wherein: The first lens has a focal power of 0 and is a plane lens, with both the first surface and the second surface being planes; The second lens has a negative optical power, and the third surface is a concave surface with a radius of curvature equal to 1.401 mm; The third lens has positive optical power, the fourth surface is a convex surface with a curvature radius of 17.626 mm, and the fifth surface 32 is a convex surface with a curvature radius of -2.376 mm. The fourth lens has negative refractive power, the sixth surface is a concave surface with a curvature radius of -1.735 mm, and the seventh surface is a concave surface with a curvature radius of 11.271 mm. The fifth lens has positive optical power, and the eighth surface is a convex surface with a radius of curvature equal to -3.384 mm; The sixth lens has positive refractive power, the ninth surface is a convex surface with a curvature radius of 8.435 mm, and the tenth surface is a convex surface with a curvature radius of -15.917 mm. The seventh lens has positive refractive power, the eleventh surface is convex with a radius of curvature equal to 3.798 mm, and the twelfth surface is concave with a radius of curvature equal to 13.831 mm; The focal length of the second lens is -2.881 mm; the focal length of the third lens is 2.682 mm; the focal length of the fourth lens is -2.735 mm; the focal length of the fifth lens is 4.516 mm; the focal length of the sixth lens is 9.360 mm; and the focal length of the seventh lens is 10.330 mm. The refractive index of the first lens is 1.448, and the center thickness is 0.500 mm; the refractive index of the second lens is 1.489, and the center thickness is 0.292 mm; the refractive index of the third lens is 1.87, and the center thickness is 4.402 mm; the refractive index of the fourth lens is 1.543, and the center thickness is 0.778 mm; the refractive index of the fifth lens is 1.605, and the center thickness is 1.607 mm; the refractive index of the sixth lens is 1.605, and the center thickness is 1.296 mm; and the refractive index of the seventh lens is 1.489, and the center thickness is 1.296 mm.

2. The infrared endoscope objective optical system suitable for imaging blood flow according to claim 1, characterized in that: The aperture of the aperture is less than 1 mm.

3. The infrared endoscope objective optical system suitable for imaging blood flow according to claim 1, characterized in that: The aperture sizes of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are all smaller than 5 mm, and the optical tube length is smaller than 25 mm.

4. The infrared endoscope objective optical system suitable for imaging blood flow according to claim 1, characterized in that: The working wavelength range of the infrared endoscope objective optical system is 0.8-2.0 microns.

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