Infrared Endoscope Adapter Lens Optical System for Flow Blood Imaging

Abstract

The present invention provides an infrared endoscope transfer lens optical system suitable for imaging of flowing blood, which is used to uniformly magnify the image plane output by the eyepiece optical system and transmit it to the infrared special camera at the rear for imaging, and is characterized in that the infrared endoscope transfer lens optical system is composed of a first lens, a second lens and a third lens arranged in sequence from the object plane to the image plane along the optical axis. The present invention achieves the advantage of small image distortion while ensuring a small number of lenses through the optimization of the lens structure, and can further magnify the image plane output by the front eyepiece and uniformly transmit it to the photosensitive surface of the rear camera, and all lenses adopt a spherical structure, which reduces the difficulty of processing and saves costs.

Description

Technical Field

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

[0002] Since its invention, the endoscope technology that combines modern optics, precision machinery, and electronic technology has been widely used. It not only provides non-destructive testing during industrial production without disassembling or stopping the equipment operation, but also has developed many categories such as oral endoscopes, laparoscopes, and otolaryngology endoscopes in the medical field, effectively improving the detection rate of lesions and the surgical recovery ability.

[0003] Endoscopes are usually placed in a medium with low scattering and weak absorption such as air. Therefore, using visible light as the light source can achieve excellent imaging effects, but this cannot meet the usage requirements 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 the light source for imaging in the blood environment. Because the absorption and scattering coefficients of visible light in such media are relatively large, it is difficult to achieve effective light transmission and thus impossible to image the target substance. To solve this problem, relevant personnel have proposed a new type of endoscope based on an infrared light source. This endoscope uses an infrared laser in the near-infrared band as the light source of the endoscope, achieving visualization in the blood environment.

[0004] Currently, the main endoscopes on the market mainly use visible light as the light source, and related matching optical elements such as adapter lenses can only support visible light. This results in the lack of available adapter lenses for endoscopes using infrared lasers as the light source. The composition of an optical imaging system cannot do without the adapter lens component. Summary of the Invention

[0005] The object of the present invention is to provide an adapter lens suitable for an infrared endoscope, which has a simple structure, is small and compact, has small geometric distortion, and operates in the near-infrared band.

[0006] To achieve the above object, the technical solution of the present invention is to provide an infrared endoscope adapter lens optical system suitable for imaging flowing blood, which is used to uniformly magnify the image plane output by the eyepiece optical system and then transmit it to the infrared dedicated camera at the rear for imaging. The infrared endoscope adapter lens optical system is characterized in that it is composed of a first lens, a second lens, and a third lens sequentially arranged along the optical axis from the object plane to the image plane;

[0007] Define the side of the first lens facing the object surface as the first surface, and the side facing the image surface as the second surface; define the side of the second lens facing the object surface as the third surface, and the side facing the image surface as the fourth surface; define the side of the third lens facing the object surface as the fifth surface, and the side facing the image surface as the sixth surface. Then, the following conditions hold:

[0008] The first surface is a plane with an infinite radius of curvature. The second surface is a convex surface facing the image surface with a radius of curvature equal to -49.930 mm. The third surface is a convex surface facing the object surface with a radius of curvature equal to 53.440 mm. The fourth surface is a convex surface facing the image surface with a radius of curvature equal to -49.000 mm. The fifth surface is a convex surface facing the object surface with a radius of curvature equal to 52.510 mm. The sixth surface is a plane with an infinite radius of curvature.

[0009] Preferably, the first lens has a positive optical power, and its focal length f1 = 99.126 mm; the second lens 2 has a positive optical power, and its focal length f2 = 51.183 mm; the third lens 3 has a positive optical power, and its focal length f3 = 104.248 mm.

[0010] Preferably, the central thickness of the first lens is 2.200 mm; the central thickness of the second lens is 2.600 mm; the central thickness of the third lens is 2.200 mm.

[0011] Preferably, the distance between the second surface and the third surface is 2.363 mm; the distance between the fourth surface and the fifth surface is 0.299 mm.

[0012] Preferably, the clear apertures of the first lens, the second lens, and the third lens are all less than 14 mm.

[0013] Preferably, the first lens, the second lens, and the third lens are all spherical plano-convex lenses made of BK7 material.

[0014] Preferably, the optimal working wavelength band of the eyepiece optical system is 1.25 - 1.35 microns, and the optical tube length is less than 50 mm.

[0015] Through the optimization of the lens structure, the present invention realizes the advantages of small image plane distortion while ensuring a small number of lenses used. It can further magnify and uniformly transmit the image plane output by the front eyepiece to the rear camera photosensitive surface. Moreover, all lenses adopt spherical structures, which reduces the processing difficulty and saves costs.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0017] 1. In view of the special working requirements of the infrared endoscope applicable to flowing blood, the present invention designs and optimizes an objective optical system adapted thereto. Through ZEMAX simulation, based on the imaging indicators of the near-infrared laser that can fully support the near-infrared band, not only the effective coupling of the system with the front imaging fiber bundle is achieved, but also the system size is strictly controlled to make the structure small and compact.

[0018] 2. The infrared endoscope eyepiece optical system applicable to flowing blood imaging designed by the present invention adopts a spherical surface design for all lenses, which reduces the processing difficulty and cost and is conducive to large-scale promotion and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of an infrared endoscope adapter lens applicable to flowing blood imaging of the present invention;

[0020] Figure 2 is a schematic diagram of the application scenario of the adapter lens in the embodiment of the present invention;

[0021] Figure 3 is a simulation diagram of the MTF optical transfer function curve of the adapter lens in the embodiment of the present invention;

[0022] Figure 4 is a simulation diagram of the relative illuminance of the adapter lens in the embodiment of the present invention;

[0023] Figure 5 is a simulation diagram of the distortion of the adapter lens in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following further elaborates the present invention in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it 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 also fall within the scope defined by the appended claims of this application.

[0025] The infrared endoscope adapter lens provided by the present invention has a structure as Figure 1 shown, and is composed of a first lens 1, a second lens 2, and a third lens 3 arranged in sequence along the optical axis from the object surface to the image surface. To ensure the overall structure is small, the clear apertures of the first lens 1, the second lens 2, and the third lens 3 are all less than 14 mm. In this embodiment, the clear aperture is 12.70 mm. And to ensure simple processing and reduce costs, the first lens 1, the second lens 2, and the third lens 3 are all spherical plano-convex lenses made of BK7 material.

[0026] In this embodiment, the surface of the first lens 1 facing the object surface is defined as the first surface 11, and the surface facing the image surface is defined as the second surface 12. The surface of the second lens 2 facing the object surface is defined as the third surface 21, and the surface facing the image surface is defined as the fourth surface 22. The surface of the third lens 3 facing the object surface is defined as the fifth surface 31, and the surface facing the image surface is defined as the sixth surface 32. Then:

[0027] The first lens 1 has a positive optical power, and the focal length f1 = 99.126 mm. The first surface 11 is a plane with an infinite radius of curvature; the second surface 12 is convex toward the image surface with a radius of curvature of -49.930 mm. The central thickness of the first lens 1 is 2.200 mm.

[0028] The second lens 2 has a positive optical power, and the focal length f2 = 51.183 mm. The third surface 21 is convex toward the object surface with a radius of curvature of 53.440 mm; the fourth surface 22 is convex toward the image surface with a radius of curvature of -49.000 mm. The central thickness of the second lens 2 is 2.600 mm.

[0029] The third lens 3 has a positive optical power, and the focal length f3 = 104.248 mm. The fifth surface 31 is convex toward the object surface with a radius of curvature of 52.510 mm; the sixth surface 32 is a plane with an infinite radius of curvature. The central thickness of the third lens 3 is 2.200 mm.

[0030] To ensure the overall structure is compact, the distance between the second surface 12 and the third surface 21 is 2.363 mm; the distance between the fourth surface 22 and the fifth surface 31 is 0.299 mm.

[0031] The application environment of the present invention is as Figure 2 shown: At the very front, the imaging fiber bundle A transmits the reflected light of a distant object to the eyepiece optical system B. Then, through an adapter lens C provided by the present invention, the image surface is uniformly magnified and transmitted to the infrared dedicated camera D at the rear for imaging. Among them, the imaging fiber bundle A is a high-definition imaging fiber with a pixel count in the tens of thousands. The eyepiece optical system B can adopt the optical system of an existing infrared endoscope, or can also adopt an infrared endoscope objective optical system for imaging flowing blood applied for by the applicant in another case. The best working band of the eyepiece optical system B is 1.25 - 1.35 microns, and the optical tube length is less than 50 mm. In this embodiment, the optical tube length is 46.69 mm.

[0032] As Figure 3As shown, after optimizing the eyepiece optical system B using the above embodiment, the full-field MTF of the optimized eyepiece optical system B at a cut-off frequency of 30 lp / mm is greater than 0.57, and the relative illumination of the optimized eyepiece optical system B on the image plane is greater than 99%, ensuring the illumination uniformity during imaging. At the same time, the distortion of the optimized eyepiece optical system B on the image plane is less than 1.2%.

[0033] The infrared dedicated camera D is a near-infrared camera with hundreds of thousands of pixels, fully supporting the imaging requirements of the entire near-infrared band.

[0034] The above embodiment is only one implementation mode of the present invention, but the implementation mode of the present invention is not limited by the above embodiment. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. An infrared endoscope adapter lens optical system applicable to flowing blood imaging, which is used to uniformly magnify the image plane output by the eyepiece optical system and then transmit it to the infrared dedicated camera at the rear for imaging. Characterized in that, The infrared endoscope adapter lens optical system is composed of a first lens, a second lens and a third lens arranged in sequence along the optical axis from the object plane to the image plane; Define the side of the first lens facing the object plane as the first surface, and the side facing the image plane as the second surface. Define the side of the second lens facing the object plane as the third surface, and the side facing the image plane as the fourth surface. Define the side of the third lens facing the object plane as the fifth surface, and the side facing the image plane as the sixth surface. Then there are: The first surface is a plane with an infinite radius of curvature. The second surface is convex towards the image plane with a radius of curvature equal to -49.930 mm. The third surface is convex towards the object plane with a radius of curvature equal to 53.440 mm. The fourth surface is convex towards the image plane with a radius of curvature equal to -49.000 mm. The fifth surface is convex towards the object plane with a radius of curvature equal to 52.510 mm. The sixth surface is a plane with an infinite radius of curvature; The first lens has a positive optical power, and the focal length f1 = 99.126 mm; the second lens 2 has a positive optical power, and the focal length f2 = 51.183 mm; the third lens 3 has a positive optical power, and the focal length f3 = 104.248 mm; The central thickness of the first lens is 2.200 mm; the central thickness of the second lens is 2.600 mm; the central thickness of the third lens is 2.200 mm; The clear aperture diameters of the first lens, the second lens and the third lens are all less than 14 mm; The distance between the second surface and the third surface is 2.363 mm; the distance between the fourth surface and the fifth surface is 0.299 mm; Both the first lens and the third lens are spherical plano-convex lenses made of BK7 material.

2. The infrared endoscope adapter lens optical system applicable to flowing blood imaging according to claim 1, Characterized in that, The best working band of the eyepiece optical system is 1.25 - 1.35 microns, and the optical tube length is less than 50 mm.

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