Search

EP-4528355-B1 - BIOLOGICAL IMAGING SYSTEM AND OPTICAL DETECTION APPARATUS

EP4528355B1EP 4528355 B1EP4528355 B1EP 4528355B1EP-4528355-B1

Inventors

  • JIANG, Liyang
  • WENG, Xianjie

Dates

Publication Date
20260506
Application Date
20231129

Claims (10)

  1. An optical inspection device, namely an endoscope, comprising a biological body imaging system (10, 10a, 10b), the biological body imaging system (10, 10a, 10b) comprising: a first lens set (11) with a positive focal power, a second lens set (12) with a positive focal power, a third lens set (13) with a positive focal power, and a fourth lens set (14) with a positive focal power that are sequentially arranged from an object side along a same optical axis (A); wherein the first lens set (11) comprises a second lens (112) with a plane facing the object side and a convex surface facing an image side, and a third lens (113) with a convex surface facing the object side and a convex surface facing the image side, the second lens set (12) comprises a fourth lens (121), having a negative focal power, with a convex surface facing the object side and a concave surface facing the image side, and a fifth lens (122) with a convex surface facing the object side and a convex surface facing the image side that fit with each other, the third lens set (13) comprises a sixth lens (131) with a convex surface facing the object side and a concave surface facing the image side, and the fourth lens set (14) comprises a seventh lens (141), having a negative focal power, with a concave surface facing the object side and a convex surface facing the image side and an eighth lens (142), having a positive focal power, with a convex surface facing the object side and a concave surface facing the image side; wherein there are seven lens having a focal power, a combined focal length f 1 of the first lens set (11) and a conjugate distance T satisfy 0.15 ≤ f 1 T ≤ 0.18 , a combined focal length f 4 of the fourth lens set (14) and the combined focal length f 1 of the first lens set (11) satisfy 1.8 ≤ f 4 f 1 ≤ 2.2 , and a focal length f 41 of the seventh lens (141) and a focal length f 42 of the eighth lens (142) satisfy − 1 ≤ f 42 f 41 ≤ − 0.8 .
  2. The optical inspection device according to claim 1, wherein the first lens set (11) further comprises a first lens (111) disposed on an object side of the second lens (112) along the same optical axis (A) and having a plane facing the object side.
  3. The optical inspection device according to claim 2, wherein the first lens (111) fits with the second lens (112), and surfaces of the first lens (111) on the object side and the image side both form planes.
  4. The optical inspection device according to claim 1, wherein a curvature radius r 4 corresponding to the surface of the third lens (113) facing the object side, an operating distance H of the biological body imaging system (10, 10a, 10b), and an air gap H 1 between the second lens (112) and the third lens (113) satisfy 4.75 ≤ r 4 H + H 1 ≤ 15.9 ; wherein the operating distance H refers to a distance corresponding to a gap between a central position of the surface of the second lens (112) facing the object side and a biological body, and the air gap H 1 refers to a distance corresponding to a gap between a central position of the second lens (112) and a central position of the third lens (113).
  5. The optical inspection device according to claim 1, wherein the combined focal length f 1 of the first lens set (11) and a combined focal length f 2 of the second lens set (12) satisfy 7 ≤ f 2 f 1 ≤ 11.5 .
  6. The optical inspection device according to claim 1, wherein a combined focal length f 2 of the second lens set (12) and a combined focal length f 3 of the third lens set (13) satisfy 2.2 ≤ f 2 f 3 ≤ 4.5 .
  7. The optical inspection device according to claim 1, wherein a curvature radius r 3 corresponding to the surface of the second lens (112) facing the image side and a focal length f 12 of the second lens (112) satisfy − 0.91 ≤ r 3 f 12 ≤ − 0.81 .
  8. The optical inspection device according to claim 1, wherein a curvature radius r 9 corresponding to the surface of the sixth lens (131) facing the object side and a combined focal length f 3 of the third lens set (13) satisfy 0.15 ≤ r 9 f 3 ≤ 0.35 .
  9. The optical inspection device according to claim 1, wherein a curvature radius r 12 corresponding to the surface of the seventh lens (141) facing the image side and a curvature radius r 13 corresponding to the surface of the eighth lens (142) facing the object side satisfy − 0.7 ≤ r 12 r 13 ≤ − 0.5 .
  10. The optical inspection device according to claim 1, wherein a central thickness D 9 of the sixth lens (131) and the conjugate distance T satisfy 0.13 ≤ D 9 T .

Description

This application claims priority to Chinese Patent Application No. 20231227358.3, filed with the China National Intellectual Property Administration on September 22, 2023 and entitled "BIOLOGICAL BODY IMAGING SYSTEM AND OPTICAL INSPECTION DEVICE". FIELD OF TECHNOLOGY The present invention relates to the field of optical technologies, and in particular to, a biological body imaging system and an optical inspection device. BACKGROUND An endoscope is a device that examines or treats tissues in the human body using a head probe and optical lenses based on the operation principles of optical imaging and probe technology. With a light source and lenses introduced into body cavities or tissues, microscopic structures or pathological tissues inside the body can be observed. The optical imaging principle of the endoscope means that light of a light source behind the human body enters into the body, and is reflected by an inner wall of an endoscope head and then guided by optical fibers to observation equipment. The optical lens of the endoscope focuses the light, thereby forming an enlarged image for the doctor's observation. Therefore, the quality of the optical imaging directly affects the use effect of the endoscope. The optical imaging of the endoscope mainly relies on the optical system arranged therein. The optical system is formed by an object lens, a lens set, and an eyepiece arranged sequentially from the front end at which a biological tissue is located to the rear end. The object lens is used to collect information of the biological tissue for imaging, the lens set is used to transmit the image, and the eyepiece is used to enlarge the image for clinical observation by the doctor. The foundation of optical imaging is the biological tissue information collected by the object lens. Therefore, the collection of biological tissue information is an indispensable and crucial part. The quality of the object lens imaging effect depends on many factors, such as the basic imaging performance and imaging aberrations of the object lens. How to ensure the imaging effect of the object lens is a problem to be resolved urgently. In addition, even though the object lens produces a relatively clear image based on the collected biological tissue information, when the lens sets transmit the image, the optical loss due to long-distance transmission in the endoscope is likely to lower the image quality. In view of this, it is necessary to improve the endoscope in the prior art, so as to resolve the foregoing problem. SUMMARY An objective of the present invention is to resolve the problem of poor imaging effect of the object lens in the prior art and the problem of optical loss of the image during long-distance transmission. To achieve the foregoing objective, according to a first aspect, the present invention provides a biological body imaging system, including: a first lens set with a positive focal power, a second lens set with a positive focal power, a third lens set with a positive focal power, and a fourth lens set with a positive focal power that are sequentially arranged from an object side along a same optical axis. The first lens set includes a second lens with a plane facing the object side, the second lens set includes a fourth lens with a convex surface facing the object side and a fifth lens with a convex surface facing an image side that fit with each other, the third lens set includes a sixth lens with a convex surface facing the object side and a concave surface facing the image side, and the fourth lens set includes a seventh lens with a concave surface facing the object side and a convex surface facing the image side and an eighth lens with a convex surface facing the object side and a concave surface facing the image side. A combined focal length f1 of the first lens set and a conjugate distance T satisfy 0.15≤f1T≤0.18 , a combined focal length f4 of the fourth lens set and the combined focal length f1 of the first lens set satisfy 1.8≤f4f1≤2.2, and a focal length f41 of the seventh lens and a focal length f42 of the eighth lens satisfy −1≤f42f41≤−0.8. As further improvement of the present invention, the first lens set further includes a third lens disposed on an image side of the second lens along the same optical axis; and a surface of the third lens facing the image side forms a convex surface. As further improvement of the present invention, a surface of the third lens facing the object side forms a convex surface or a plane. As further improvement of the present invention, the first lens set further includes a first lens disposed on an object side of the second lens along the same optical axis and having a plane facing the object side. As further improvement of the present invention, the first lens fits with the second lens, and surfaces of the first lens on the object side and the image side both form planes. As further improvement of the present invention, if the surface of the third lens facing the ob