An infrared endoscope transfer lens optical component

Abstract

The present invention belongs to the technical field of endoscopes, and specifically is an infrared endoscope transfer lens optical component. The transfer lens optical component of the present invention includes: an object plane, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and an imaging plane; wherein the first lens, the fifth lens, and the sixth lens all have negative optical focal lengths, and the second lens, the third lens, and the fourth lens all have positive optical focal lengths; the second lens and the second lens are combined into a double-cemented lens, and the fourth lens and the fifth lens are combined into a double-cemented lens; the system adopts an object-side telecentric structure design, and through reasonable matching and structural optimization, the transfer lens efficiently transmits the light derived from the front-end optical fiber to the subsequent coupled CCD. When the system works in the near-infrared band, it can ensure that the MTF value is greater than 0.65 at the limit resolution of 16.7lp / mm, and the relative illumination of the full field of view is greater than 65%; all lens surfaces adopt a spherical structure, with a compact structure, small size, and low processing cost.

Description

Technical Field

[0001] The invention belongs to the technical field of endoscopes, and in particular relates to an infrared endoscope switching lens optical component. Background Art

[0002] In recent years, endoscopes are not only used for medical diagnosis, but also widely used in automobile and shipbuilding, mechanical electronics, electric power metallurgy, petrochemical industry, civil engineering and construction and other industrial sectors. Currently, the products put on the market mainly include three types of products: rigid endoscopes, fiber optic endoscopes, and electronic video endoscopes. Among them, fiber optic endoscopes are widely used due to the good flexibility and environmental adaptability of the fiber bundle.

[0003] A typical fiber optic image bundle endoscope is mainly composed of a front objective lens, a fiber optic image bundle, an eyepiece / adapter lens, a detector, etc. In the medical field, endoscopes are increasingly used in clinical surgery. Especially in some special environments, such as observations in the blood, common visible light endoscopes cause serious distortion and deformation of visible light imaging due to the strong absorption and scattering effects of blood on the visible light band, and there are problems such as poor relative illumination. However, the absorption and scattering of infrared light information by blood is relatively weak, so it is of great significance to study and improve infrared endoscopes for observation during surgery. In most cases, CCD is used for image acquisition, and the design of the adapter lens plays an important role in ensuring the final image quality. However, the design of infrared lenses has problems such as large size and high cost. Summary of the invention

[0004] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, an object of the present invention is to provide an infrared endoscope transfer lens optical component with small size, low cost and good performance.

[0005] The infrared endoscope transfer lens optical assembly provided by the present invention has a structure as shown in Figure 1 As shown in the figure, the system adopts an object-side telecentric structure. Through the optimization of the lens structure, it achieves high telecentricity while ensuring a compact structure and a small number of lenses. It can couple well with the front-end optical fiber image transmission bundle and efficiently transmit light to the subsequent CCD. In addition, all lenses adopt a spherical structure, which greatly reduces the difficulty of processing and saves processing costs.

[0006] The infrared endoscope switching lens optical assembly provided by the present invention comprises an object plane 1, a first lens 2, a second lens 3, a third lens 4, a fourth lens 5, a fifth lens 6, a sixth lens 7, and an imaging plane 8; all the lenses are coaxial; wherein the first lens 2, the fifth lens 6, and the sixth lens 7 all have negative optical focal lengths, and the second lens 3, the third lens 4, and the fourth lens 5 all have positive optical focal lengths; the first lens 2 comprises a first surface 21 facing the object plane and a second surface 22 facing the image plane; the second lens 3 comprises a third surface 31 facing the object plane and a fourth surface 32 facing the image plane; the third lens 4 comprises a fourth surface 32 facing the object plane and a fifth surface 41 facing the image plane; the fourth lens 5 comprises a sixth surface 51 facing the object plane and a seventh surface 52 facing the image plane; the fifth lens 6 comprises a seventh surface 52 facing the object plane and an eighth surface 61 facing the image plane; the sixth lens 7 comprises a ninth surface 71 facing the object plane and a tenth surface 72 facing the image plane; the front end of the switching lens optical assembly is coupled with an optical fiber image transmission bundle, and the rear end is matched with a subsequent CCD.

[0007] Furthermore, the focal length f1 of the first lens 2 is -14.388 mm, and the F number is -3.4631; the focal length f2 of the second lens 3 is -4.1374 mm, and the F number is -0.8957; the focal length f3 of the third lens 4 is 2.8073 mm, and the F number is 0.61345; the focal length f4 of the fourth lens 5 is -3.9673 mm, and the F number is -0.9330; the focal length f5 of the fifth lens 6 is 2.6718 mm, and the F number is 0.6941; the focal length f6 of the sixth lens 7 is -19.507 mm, and the F number is -6.1232.

[0008] Furthermore, the refractive index n and Abbe number v of the first lens 2 are 1.6404 and 59.7499 respectively; the refractive index n and Abbe number v of the second lens 3 are 1.9228 and 20.8797 respectively; the refractive index n and Abbe number v of the third lens 4 are 1.8806 and 41.0097 respectively; the refractive index n and Abbe number v of the fourth lens 5 are 1.9228 and 20.8797 respectively; the refractive index n and Abbe number v of the fifth lens 6 are 1.8502 and 32.1701 respectively; the refractive index n and Abbe number v of the sixth lens 7 are 1.8059 and 34.2421 respectively.

[0009] Furthermore, the operating band of the transfer lens optical component is 1.2-1.8 μm, the effective focal length is 4.3-4.5 mm, the maximum system aperture is 4.6-4.8 mm, the total system length is 18.5-19.5 mm, and the object plane size is 3-3.5 mm.

[0010] The front end of the transfer lens optical component is coupled with the optical fiber image transmission bundle, and the rear end is matched with the subsequent CCD; the CCD resolution is 320×256, the single pixel size is 30μm, and the diagonal size is 12.3mm.

[0011] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0012] (1) The present invention designs an infrared endoscope transfer lens optical component, which adopts an object-side telecentric structure, couples the transfer lens and the front-end optical fiber bundle, and efficiently transmits light to the subsequent CCD sensor for image acquisition;

[0013] (2) The present invention optimizes the structure and spatial spacing of the first to sixth lenses, so that the system can work in the 1.2-1.8μm near-infrared band, and can ensure that the MTF value is greater than 0.65 at the limit resolution of 16.7lp / mm, and the relative illumination of the full field of view is greater than 65%. The maximum system aperture is only 4.6074mm, and all lens surfaces adopt a spherical structure, which greatly reduces the processing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural diagram of the infrared endoscope transfer lens optical component of the present invention.

[0015] Figure 2 It is an imaging diagram of the infrared endoscope transfer lens optical component of the present invention.

[0016] Figure 3 It is the MTF transfer function curve in the embodiment of the present invention.

[0017] Figure 4 FIG. 2 is a diagram illustrating the diffuse spots in an embodiment of the present invention.

[0018] Figure 5 It is a diagram of relative illumination in an embodiment of the present invention.

[0019] In the figure, the numbers are: 1 is the object plane, 2 is the first lens, 3 is the second lens, 4 is the third lens, 5 is the fourth lens, 6 is the fifth lens, 7 is the sixth lens, 8 is the imaging plane, 21 is the first surface, 22 is the second surface, 31 is the third surface, 32 is the fourth surface, 41 is the fifth surface, 51 is the sixth surface, 52 is the seventh surface, 61 is the eighth surface, 71 is the ninth surface, and 72 is the tenth surface. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto. Example

[0021] like Figure 1 As shown, an infrared endoscope transfer lens optical assembly includes an object plane 1, a first lens 2, a second lens 3, a third lens 4, a fourth lens 5, a fifth lens 6, a sixth lens 7, and an imaging plane 8; the first lens 2, the fifth lens 6, and the sixth lens 7 all have negative optical focal lengths, and the second lens 3, the third lens 4, and the fourth lens 5 all have positive optical focal lengths; the first lens 2 includes a first surface 21 facing the object plane and a second surface 22 facing the image plane; the second lens 3 includes a third surface 31 facing the object plane and a fourth surface 32 facing the image plane; the third lens 4 includes a fourth surface 32 facing the object plane and a fifth surface 41 facing the image plane; the fourth lens 5 includes a sixth surface 51 facing the object plane and a seventh surface 52 facing the image plane; the fifth lens 6 includes a seventh surface 52 facing the object plane and an eighth surface 61 facing the image plane; the sixth lens 7 includes a ninth surface 71 facing the object plane and a tenth surface 72 facing the image plane.

[0022] Furthermore, the focal length f1 of the first lens 2 is -14.388 mm, and the F number is -3.4631; the focal length f2 of the second lens 3 is -4.1374 mm, and the F number is -0.8957; the focal length f3 of the third lens 4 is 2.8073 mm, and the F number is 0.61345; the focal length f4 of the fourth lens 5 is -3.9673 mm, and the F number is -0.9330; the focal length f5 of the fifth lens 6 is 2.6718 mm, and the F number is 0.6941; the focal length f6 of the sixth lens 7 is -19.507 mm, and the F number is -6.1232.

[0023] Furthermore, the refractive index n and Abbe number v of the first lens 2 are 1.6404 and 59.7499 respectively; the refractive index n and Abbe number v of the second lens 3 are 1.9228 and 20.8797 respectively; the refractive index n and Abbe number v of the third lens 4 are 1.8806 and 41.0097 respectively; the refractive index n and Abbe number v of the fourth lens 5 are 1.9228 and 20.8797 respectively; the refractive index n and Abbe number v of the fifth lens 6 are 1.8502 and 32.1701 respectively; the refractive index n and Abbe number v of the sixth lens 7 are 1.8059 and 34.2421 respectively.

[0024] Further, the first surface 21 is a concave spherical surface with a curvature radius of -3.6710mm; the second surface 22 is a concave spherical surface with a curvature radius of -6.8705mm, and the center thickness of the first lens 2 is 0.9722mm; the third surface 31 is a convex spherical surface with a curvature radius of 14.6938mm, the fourth surface 32 is a convex spherical surface with a curvature radius of 2.8815mm, and the center thickness of the second lens 3 is 0.5234mm; the fifth surface 41 is a concave spherical surface with a curvature radius of -9.7719mm; the center thickness of the third lens 4 is 1.830 6mm; the sixth surface 51 is a convex spherical surface with a curvature radius of 5.0196mm, the seventh surface 52 is a convex spherical surface with a curvature radius of 2.0296mm, and the center thickness of the fourth lens 5 is 0.5667mm; the eighth surface 61 is a convex spherical surface with a curvature radius of 20.7063mm, and the center thickness of the fifth lens 6 is 1.4138mm; the ninth surface 71 is a convex spherical surface with a curvature radius of 2.5488mm, the tenth surface 72 is a convex spherical surface with a curvature radius of 1.7710mm, and the center thickness of the sixth lens 7 is 1.0976mm.

[0025] Furthermore, the center distance between the object plane 1 and the first surface 21 is 5.8 mm, the center distance between the second surface 22 and the third surface 31 is 0.2153 mm, the center distance between the fifth surface 41 and the sixth surface 51 is 0.327 mm, the center distance between the eighth surface 61 and the ninth surface 71 is 0.2145 mm, and the center distance between the tenth surface 72 and the imaging plane 8 is 13.1239 mm.

[0026] Further, the net aperture of the first lens 2 is 2.0719 mm, the net aperture of the second lens 3 is 2.3037 mm, the net aperture of the third lens 4 is 2.2823, the net aperture of the fourth lens 5 is 2.1253 mm, the net aperture of the fifth lens 6 is 1.9252 mm, and the net aperture of the sixth lens 7 is 1.5989 mm; further, the aperture of the transfer lens coincides with the tenth surface 72.

[0027] Furthermore, the operating band of the adapter lens optical component is 1.2-1.8μm, the effective focal length is 4.37mm, the maximum system aperture is 4.6074mm, the total system length is 18.65mm, and the object plane size is 3mm; the front end of the adapter lens optical component is coupled with the fiber optic image transmission bundle, and the rear end is matched with the subsequent CCD; the CCD resolution is 320×256, the single pixel size is 30μm, and the diagonal size is 12.3mm.

[0028] Furthermore, if Figure 2As shown in the figure, the transfer lens adopts an object-space telecentric structure design with a telecentricity of up to 0.0562.

[0029] Furthermore, if Figure 3 As shown, the MTF value of the adapter lens in the embodiment at the cutoff frequency of 16.7lp / mm in the whole field of view is greater than 0.65, and the overall aberration optimization effect is good.

[0030] Furthermore, if Figure 4 As shown, the root mean square size of the diffuse spot of light received by the objective optical system at the imaging plane in the embodiment is about 9.267 μm, and the size of a subsequent matched CCD single pixel is 30 μm, which is more than enough to meet the imaging requirements.

[0031] Furthermore, if Figure 5 As shown, the relative illumination of the light received by the objective optical system in the embodiment at the imaging surface is above 65%, which is much better than the relative illumination characteristics of common endoscope structures, and well ensures the uniformity of imaging.

[0032] Furthermore, the main function of the transfer lens is to transmit the light of the front-end coupled optical fiber image bundle to the subsequent CCD for image acquisition. The working band of the transfer lens optical component is 1.2-1.8μm, the field of view angle is 28.95°, the effective focal length is 4.37mm, the maximum system aperture is 4.6074mm, the total system length is 18.65mm, and the object plane size is 3mm; the numerical aperture of the optical fiber image bundle is 0.22, the CCD resolution is 320×256, the single pixel size is 30μm, and the diagonal size is 12.3mm.

[0033] The above embodiment is only one implementation of the present invention, but the implementation 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 equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. An infrared endoscope transfer lens optical assembly, characterized in that: The invention comprises an object plane (1), a first lens (2), a second lens (3), a third lens (4), a fourth lens (5), a fifth lens (6), a sixth lens (7), and an imaging plane (8); all lenses are coaxial and adopt a spherical structure. By optimizing the lens structure, a high telecentricity is achieved while ensuring a compact structure and a small number of lenses; wherein the first lens (2), the fifth lens (6), and the sixth lens (7) all have negative focal powers, and the second lens (3), the third lens (4), and the fourth lens (5) all have positive focal powers; the first lens (2) comprises a first surface (21) facing the object plane and a second surface (22) facing the image plane; the second lens (2) comprises a first surface (21) facing the object plane and a second surface (22) facing the image plane; The mirror (3) comprises a third surface (31) facing the object plane and a fourth surface (32) facing the image plane; the third lens (4) comprises a fourth surface (32) facing the object plane and a fifth surface (41) facing the image plane; the fourth lens (5) comprises a sixth surface (51) facing the object plane and a seventh surface (52) facing the image plane; the fifth lens (6) comprises a seventh surface (52) facing the object plane and an eighth surface (61) facing the image plane; the sixth lens (7) comprises a ninth surface (71) facing the object plane and a tenth surface (72) facing the image plane; the front end of the transfer lens optical assembly is coupled with an optical fiber image transmission bundle, and the rear end is matched with a subsequent CCD; The focal length f1 of the first lens (2) is -14.388 mm, and the F number is -3.4631; the focal length f2 of the second lens (3) is -4.1374 mm, and the F number is -0.8957; the focal length f3 of the third lens (4) is 2.8073 mm, and the F number is 0.61345; the focal length f4 of the fourth lens (5) is -3.9673 mm, and the F number is -0.9330; the focal length f5 of the fifth lens (6) is 2.6718 mm, and the F number is 0.6941; the focal length f6 of the sixth lens (7) is -19.507 mm, and the F number is -6.1232; The refractive index n and the Abbe number v of the first lens (2) are 1.6404 and 59.7499 respectively; the refractive index n and the Abbe number v of the second lens (3) are 1.9228 and 20.8797 respectively; the refractive index n and the Abbe number v of the third lens (4) are 1.8806 and 41.0097 respectively; the refractive index n and the Abbe number v of the fourth lens (5) are 1.9228 and 20.8797 respectively; the refractive index n and the Abbe number v of the fifth lens (6) are 1.8502 and 32.1701 respectively; the refractive index n and the Abbe number v of the sixth lens (7) are 1.8059 and 34.2421 respectively.

2. The infrared endoscope transfer lens optical assembly according to claim 1, characterized in that: The working band is 1.2-1.8μm, the effective focal length is 4.3-4.5mm, the maximum system aperture is 4.6-4.8mm, the total system length is 18.5-19.5mm, and the object plane size is 3-3.5mm.

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