A capsule endoscope lens

Abstract

The present invention provides a capsule endoscope lens, which sequentially includes a hemispherical cover (SP) with negative optical power, a first lens (L1) with negative optical power, a second lens (L2) with positive optical power, a diaphragm, a third lens (L3) with positive optical power, and a chip protection glass from the object side to the image side. The first lens (L1) and the second lens (L2) form a first lens group (E1); the lens has 4 lenses with optical power; the lens satisfies the following conditional formulas: R1 - R2 = Dr1r2 (1) -0.2 < R5 / R3 < 0 (2) -3.0 < f1 / f < -2.0 (3) 1.0 < f3 / f < 1.5 (4) where R1 is the curvature radius of the object side surface of the hemispherical cover, R2 is the curvature radius of the image side surface of the hemispherical cover, Dr1r2 is the axial distance from the object side surface of the hemispherical cover to the image side surface of the hemispherical cover, R3 is the curvature radius of the object side surface of the first lens, R5 is the curvature radius of the object side surface of the second lens, f1, f3, and f are the effective focal lengths of the first lens group (E1), the third lens (L3), and the entire optical system of the capsule endoscope lens, respectively; the above lens is beneficial to ensuring a large field of view angle while improving the illumination of the imaging picture, and has a small volume.

Description

Technical Field

[0001] The present invention includes a capsule endoscope lens.

Background Art

[0002] With the progress of technology, the endoscopic detection technology has also developed rapidly. The capsule endoscope overcomes the defects of the traditional insertion endoscope, such as poor tolerance and inapplicability to critically ill and elderly or weak patients. It is a safe, convenient and painless endoscopic detection method, especially suitable for the examination of digestive tract related diseases. However, most of the current capsule endoscopes also have problems such as large distortion, dark imaging picture, low resolution and large volume.

Summary of the Invention

[0003] The present invention provides a capsule endoscope lens with a smaller volume and a higher imaging illuminance. The hemispherical cover of the capsule endoscope lens has a smaller spherical radius, which can have a smaller volume while ensuring a larger field of view angle. At the same time, the relative aperture of the lens is smaller, which is beneficial to increasing the imaging illuminance.

[0004] The present invention is achieved through the following technical solutions:

[0005] A capsule endoscope lens, characterized in that it sequentially includes a hemispherical cover (SP) with a negative optical power, a first lens (L1) with a negative optical power, a second lens (L2) with a positive optical power, a diaphragm, a third lens (L3) with a positive optical power, and a chip protection glass from the object side to the image side. The first lens (L1) and the second lens (L2) form a first lens group (E1); the object side surface of the hemispherical cover is convex, and the image side surface is concave, and both of the above two surfaces are spherical surfaces; the number of lenses with optical power in this lens is 4; this lens satisfies the following conditional formulas:

[0006] R1 - R2 = Dr1r2 (1)

[0007] -0.2 < R5 / R3 < 0 (2)

[0008] -3.0 < f1 / f < -2.0 (3)

[0009] 1.0 < f3 / f < 1.5 (4)

[0010] Wherein, R1 is the curvature radius of the object side surface of the hemispherical cover, R2 is the curvature radius of the image side surface of the hemispherical cover, Dr1r2 is the axial distance from the object side surface of the hemispherical cover to the image side surface of the hemispherical cover, R3 is the curvature radius of the object side surface of the first lens, R5 is the curvature radius of the object side surface of the second lens, and f1, f3 and f are respectively the effective focal lengths of the first lens group (E1), the third lens (L3) and the entire optical system of this capsule endoscope lens.

[0011] The hemispherical cover (SP) of this lens has a negative focal power, with its object side being convex and its image side being concave; the first lens (L1) has a negative focal power, with its object side being concave and its image side being concave; the second lens (L2) has a positive focal power, with its object side being convex and its image side being concave; the third lens (L3) has a positive focal power, with its object side being convex and its image side being convex; at least three of the optical system of the entire capsule endoscope lens are plastic aspherical lenses.

[0012] To collect as much light as possible with a large field of view angle, the hemispherical cover is designed to have a negative focal power and a relatively large aperture; the centers of curvature of the object side S1 and the image side S2 of the hemispherical cover are located at the same point, which is beneficial to reducing the distortion caused by the hemispherical cover.

[0013] The aperture stop is located between the second lens L2 and the third lens L3, which is beneficial to increasing the field of view angle of this optical system. For the optical system that meets the requirements of formula (2), it is beneficial to increase the field of view angle of this optical system. The image side of the first lens is concave, and the object side of the second lens is convex, which is beneficial to reducing the total length of the optical system.

[0014] The above-mentioned capsule endoscope lens is characterized in that:

[0015] 0.1 < f / TTL < 0.3 (5)

[0016] Wherein, f is the effective focal length of this optical system, and TTL is the distance from the object side of the first lens of this optical system to the imaging surface on the optical axis.

[0017] The capsule endoscope optical system that meets formula (5) can ensure a shorter working distance, a larger depth of field, and a larger field of view angle of the lens, and has a higher resolution both in the long-distance and short-distance scenes.

[0018] The above-mentioned capsule endoscope optical system is characterized in that:

[0019] 1.0 < f3 / f < 1.5 (6)

[0020] Wherein, f3 is the effective focal length of the third lens (L3), and f is the effective focal length of this optical system.

[0021] The third lens (L3) is located behind the aperture stop. The capsule endoscope optical system that meets formula (6) is beneficial to reducing the total length of the optical system and at the same time ensuring small optical aberrations.

[0022] The above-mentioned capsule endoscope optical system is characterized in that:

[0023] -3.0 < f1 / f < -2.0 (7)

[0024] Among them, f1 is the effective focal length of the first lens group (E1), and f is the effective focal length of the optical system.

[0025] The first lens group (E1) is located in front of the aperture. The capsule endoscope optical system that satisfies formula (7) is conducive to the relatively gentle entry of large-angle incident light into the subsequent optical system, is conducive to reducing optical aberration, and at the same time ensures a relatively short total length of the optical system, meeting the requirements of miniaturization.

[0026] The above-mentioned capsule endoscope optical system is characterized in that:

[0027] 0 < Dr3r6 / TTL < 0.5 (8)

[0028] 1.0 < Dr3r6 / f < 2.5 (9)

[0029] Among them, Dr3r6 is the on-axis distance from the object side S3 of the first lens (L1) of the optical system to the image side S6 of the second lens, TTL is the on-axis distance from the object side of the first lens of the optical system to the imaging surface; f is the effective focal length of the optical system.

[0030] The capsule endoscope optical system that satisfies formula (8) can ensure a relatively short total length of the optical system and a relatively large field of view angle;

[0031] The capsule endoscope optical system that satisfies formula (9) has a relatively large field of view angle, and at the same time is conducive to improving distortion and the field area.

[0032] The above-mentioned capsule endoscope optical system is characterized in that:

[0033] 1.5 < Dr9i / f < 1.9 (10)

[0034] Among them, Dr9i is the on-axis distance from the image side of the third lens (L3) to the imaging surface; f is the effective focal length of the optical system.

[0035] The capsule endoscope optical system that satisfies formula (10) can ensure relatively small aberration and at the same time ensure a relatively large field of view angle.

Description of the Drawings

[0036] Figure 1 is a cross-sectional view of the overall structure of the capsule endoscope optical system.

[0037] Figure 2 is the aberration curve diagram of the capsule endoscope optical system.

[0038] Figure 3 is the distortion diagram of the capsule endoscope optical system.

[0039] Figure 4 is the spot diagram of the capsule endoscope optical system.

Detailed Embodiments

[0040] The following provides a detailed description of the specific embodiments of the present invention.

[0041] As Figure 1 shown, the capsule endoscope optical system of this embodiment sequentially includes a hemispherical cover (SP) with a negative optical power, a first lens (L1) with a negative optical power, a second lens (L2) with a positive optical power, a diaphragm, a third lens (L3) with a positive optical power, and a chip protection glass from the object side to the image side. The first lens (L1) and the second lens (L2) form a first lens group (E1); the side of the hemispherical cover close to the object is convex, and the side close to the image is concave, and both of the above two surfaces are spherical surfaces; the number of lenses with optical power in this lens is 4; this lens satisfies the following conditional formulas:

[0042] R1 - R2 = Dr1r2 (1)

[0043] -0.2 < R5 / R3 < 0 (2)

[0044] -3.0 < f1 / f < -2.0 (3)

[0045] 1.0 < f3 / f < 1.5 (4)

[0046] Among them, R1 is the curvature radius of the object side surface of the hemispherical cover, R2 is the curvature radius of the image side surface of the hemispherical cover, Dr1r2 is the axial distance from the object side surface of the hemispherical cover to the image side surface of the hemispherical cover, R3 is the curvature radius of the object side surface of the first lens, R5 is the curvature radius of the object side surface of the second lens, and f1, f3, and f are respectively the effective focal lengths of the first lens group (E1), the third lens (L3), and the entire optical system of this capsule endoscope lens.

[0047] The above capsule endoscope optical system has a larger field of view angle, a higher imaging illuminance, and a smaller volume, and at the same time has better imaging resolution for both near and far scenes.

[0048] Figures 2 - 4 are some optical parameters of an embodiment of this capsule endoscope optical system. In the lens data table of this embodiment, the units of radius and thickness are mm, the reference wavelengths of the aberration curve graphs are 656nm, 587nm, and 486nm, and S (solid line) and T (dashed line) in the distortion graph respectively represent the sagittal image plane and the meridional image plane.

[0049] Figure 1 is a cross-sectional view of the overall structure of this capsule endoscope optical system, Figure 2 is the aberration curve graph of this capsule endoscope optical system, Figure 3 is the distortion graph of this capsule endoscope optical system, Figure 4It is the spot diagram of the capsule endoscope optical system.

[0050] The following table is the lens data sheet of the embodiment

[0051] Table 1 is the lens data sheet of the endoscope optical system

[0052] Serial number Surface type Radius Thickness Refractive index Dispersion coefficient Object surface Spherical surface Infinitv 9.0000 1 Spherical surface 5.9 0.7 1.59 30 2 Spherical surface 5.2 4.533 3 Aspherical surface -7.6554 0.4288 1.53 56 4 Aspherical surface 0.4877 0.1670 5 Aspherical surface 0.8650 0.8674 1.63 24 6 Aspherical surface 2.8504 0.2278 Diaphragm surface Spherical surface Infinity 0.0200 8 Aspherical surface 4.6866 0.5721 1.54 56 9 Aspherical surface -0.5052 0.6607 10 Spherical surface Infinitv 0.4 1.52 64 11 Spherical surface Infinitv 0.3234 Image surface Spherical surface Infinitv 0

[0053] Table 1

[0054] Table 2 is the ratio range of the aspherical sag height to the radius R of the first lens L1 and the second lens L2

[0055]

[0056] Table 2

[0057] Table 3 is the ratio range of the aspherical sag height to the radius R of the third lens L3

[0058]

[0059]

[0060] Table 3.

Claims

1. A capsule endoscope lens, characterized in that, it sequentially includes a hemispherical cover (SP) with negative optical power, a first lens (L1) with negative optical power, a second lens (L2) with positive optical power, a diaphragm, a third lens (L3) with positive optical power, and a chip protection glass from the object side to the image side. The first lens group (E1) is composed of the first lens (L1) and the second lens (L2); the side of the hemispherical cover close to the object is convex, and the side close to the image is concave, and both of the above two surfaces are spherical surfaces; the lens has 4 lens elements with optical power; the lens satisfies the following conditional formulas: R1 - R2 = Dr1r2 (1) -0.2 < R5 / R3 < 0 (2) -3.0 < f1 / f < -2.0 (3) 1.0 < f3 / f < 1.5 (4) wherein, R1 is the curvature radius of the object side surface of the hemispherical cover, R2 is the curvature radius of the image side surface of the hemispherical cover, Dr1r2 is the axial distance from the object side surface of the hemispherical cover to the image side surface of the hemispherical cover, R3 is the curvature radius of the object side surface of the first lens, R5 is the curvature radius of the object side surface of the second lens, and f1, f3, and f are respectively the effective focal lengths of the first lens group (E1), the third lens (L3), and the entire optical system of the capsule endoscope lens.

2. The capsule endoscope lens according to claim 1, characterized in that, the object side surface of the first lens (L1) is concave, and the image side surface is concave; the object side surface of the second lens (L2) is convex, and the image side surface is concave; the object side surface of the third lens (L3) is convex, and the image side surface is convex; at least three lenses of the entire optical system of the capsule endoscope lens are plastic aspherical lenses.

3. The capsule endoscope lens according to claim 1 or 2, characterized in that: 0.1 < f / TTL < 0.3 (5) wherein, TTL is the axial distance from the object side surface of the first lens of the optical system to the imaging surface on the optical axis.

4. The capsule endoscope lens according to claim 1 or 2, characterized in that: 0 < Dr3r6 / TTL < 0.5 (6) 1.0 < Dr3r6 / f < 2.5 (7) wherein, Dr3r6 is the axial distance from the object side surface of the first lens (L1) of the optical system to the image side surface of the second lens (L2), and TTL is the axial distance from the object side surface of the first lens of the optical system to the imaging surface on the optical axis.

5. The capsule endoscope lens according to claim 1 or 2, characterized in that: 1.5 < Dr9i / f < 1.9 (8) wherein, Dr9i is the axial distance from the image side surface of the third lens (L3) to the imaging surface.

Images