Zoom endoscope optical system

Abstract

A zoom endoscope optical system comprises, in order from the object side to the image side along the optical axis, a front fixed lens group, a zoom lens group and a compensation lens group, the front fixed lens group comprises a first lens, a second lens and a third lens, the zoom lens group is adjustable in position and comprises a fourth lens and a fifth lens, the compensation lens group is adjustable in position and comprises a sixth lens, a seventh lens, an eighth lens and a ninth lens, the ninth lens is an aspheric lens, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are spherical lenses, compared with the prior art, the eight spherical lenses and the one aspheric lens are arranged, thereby reducing the length of the optical system, shortening the lens diameter, simultaneously assisting in correcting the imaging quality, and the aspheric lens guarantees the edge precision and improves the imaging effect of detecting the tiny defects in the pipeline.

Description

Technical Field

[0001] This utility model relates to the field of endoscope technology, and specifically to a zoom endoscope optical system. Background Technology

[0002] Industrial pipeline endoscopes penetrate deep into the pipeline through a front-end optical probe, using high-definition imaging technology (such as CMOS sensors with more than 1 million pixels) to capture images of the inner wall, and combine LED or xenon lamp light sources to solve the problem of imaging in dark environments, and transmit the images to an external display in real time.

[0003] In the field of pipeline inspection, the demand for high-quality zoom endoscopes in industrial inspection scenarios is increasing. Traditional endoscopes often have some limitations, such as limited focal length range, unsatisfactory field of view, decreased image quality during zooming, and lens size and structure that are not suitable for complex operating environments.

[0004] Chinese Patent Application No. 202211235555.5 discloses a zoom optical system, an endoscope objective, and an endoscope. The disclosed zoom optical system includes: a first lens group with negative optical power, comprising a first lens with negative optical power and a second lens with positive optical power, wherein the image-side surface of the first lens is concave and the object-side surface of the second lens is convex; the second lens group with positive optical power includes a cemented third lens and a fourth lens, wherein the optical powers of the third lens and the fourth lens are opposite; the third lens group with negative optical power includes a fifth lens, a sixth lens, and a seventh lens, wherein the fifth lens and the sixth lens are cemented together, wherein the optical powers of the fifth lens and the sixth lens are opposite, and the seventh lens has negative optical power, wherein the object-side surface of the fifth lens is convex and the object-side surface of the seventh lens is concave; the second lens group is movable along the optical axis between the first lens group and the third lens group. Chinese Patent Application No. 201810596241.5 discloses a zoom adapter optical system, a zoom adapter, and an endoscope system. The disclosed optical system includes, from the object side to the image side, a focusing lens group, a fixed lens group, a zoom lens group, and a compensation lens group. The focusing lens group performs focusing processing according to the object distance to obtain a clear image; the fixed lens group maintains a constant position during the focusing and zooming processes; the zoom lens group is used to move linearly along the optical axis to change the image magnification; and the compensation lens group moves non-linearly along the optical axis to compensate for the focal position movement under different magnifications.

[0005] The prior art disclosed above has multiple lens groups. The focal length is adjusted by moving the second lens group between the first and third lens groups. However, the optical system in the prior art is relatively long and has a large lens diameter, resulting in poor imaging effect for detecting tiny defects inside the pipe. Utility Model Content

[0006] The present invention aims to overcome the defects in the prior art and provide a zoom endoscopic optical system with a high zoom ratio, small aperture, and high imaging quality for detecting minute defects.

[0007] To achieve the above-mentioned utility model objectives, the present utility model adopts the following technical solution: a zoom endoscopic optical system, comprising, in sequence along the optical axis from the object side to the image side: a front fixed lens group, a zoom lens group, and a compensation lens group; the front fixed lens group includes a first lens, a second lens, and a third lens; the zoom lens group is position-adjustable and includes a fourth lens and a fifth lens; the compensation lens group is position-adjustable and includes a sixth lens, a seventh lens, an eighth lens, and a ninth lens; the ninth lens is an aspherical lens, and the first, second, third, fourth, fifth, sixth, seventh, and eighth lenses are all spherical lenses.

[0008] In a preferred embodiment of this utility model, both the zoom lens group and the compensation lens group can move linearly along the optical axis, and a distance is formed between the front fixed lens group and the zoom lens group, and between the zoom lens group and the compensation lens group, to allow the zoom lens group and the compensation lens group to move.

[0009] In a preferred embodiment of this utility model, the first lens, the second lens, and the third lens are closely fitted together; the fourth lens and the fifth lens are closely fitted together; the sixth lens, the seventh lens, and the eighth lens are closely fitted together; and a gap is formed between the ninth lens and the eighth lens.

[0010] In a preferred embodiment of the present invention, the object-side surface of the first lens is concave and the image-side surface is convex; the object-side surface of the second lens is planar and the image-side surface is convex; and the object-side surface of the third lens is convex and the image-side surface is concave.

[0011] In a preferred embodiment of this utility model, the third lens includes a first sub-lens and a second sub-lens, wherein the object-side surfaces of the first sub-lens and the image-side surfaces of the second sub-lens are both convex and concave.

[0012] In a preferred embodiment of this utility model, the object-side surface of the fourth lens is flat and the image-side surface is concave, while the object-side surface of the fifth lens is convex and the image-side surface is concave.

[0013] In a preferred embodiment of this utility model, the object-side surface of the sixth lens is flat and the image-side surface is convex; the object-side surface of the seventh lens is convex and the image-side surface is concave; the object-side surface of the eighth lens is convex and the image-side surface is concave; and the object-side surface of the ninth lens is concave and the image-side surface is convex.

[0014] In a preferred embodiment of this utility model, the sixth lens includes a third lens and a fourth lens. The object-side surface of the third lens is flat, and the image-side surface is concave. Both the object-side surface and the image-side surface of the fourth lens are convex.

[0015] In a preferred embodiment of this utility model, the seventh lens includes a fifth lens, a sixth lens, and a seventh lens. The object-side surface of the fifth lens is convex, and the image-side surface is flat. The object-side surface of the sixth lens is flat, and the image-side surface is concave. The object-side surface of the seventh lens is convex, and the image-side surface is concave.

[0016] As a preferred embodiment of this utility model, the ninth lens includes an eighth lens and a ninth lens, wherein the object-side surfaces of the eighth lens and the ninth lens are both concave, and the image-side surfaces are both convex.

[0017] Compared with the prior art, the beneficial effects of this utility model are:

[0018] The optical system is equipped with a fixed front lens group, a zoom lens group, and a compensation lens group arranged along the optical axis from the object side to the image side. Both the zoom lens group and the compensation lens group can be moved to adjust the focal length. The ninth lens at the imaging end is an aspherical lens, while the other lenses are spherical lenses. By using eight spherical lenses and one aspherical lens, the length of the optical system is reduced, the lens diameter is shortened, and the imaging quality is corrected. The use of an aspherical lens ensures edge accuracy and improves the imaging effect for detecting minute defects inside the pipe. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of this utility model;

[0020] Figure 2 This is a cross-sectional view of the present invention;

[0021] Figure 3 This is a schematic diagram of the structure at the maximum focal length of the optical system;

[0022] Figure 4 This is a multi-field diffraction transfer function diagram of an optical system at its maximum focal length;

[0023] Figure 5 This is a schematic diagram of the structure of an optical system at its normal focal length;

[0024] Figure 6 This is a multi-field diffraction transfer function diagram of an optical system at a normal focal length;

[0025] Figure 7 This is a schematic diagram of the structure of the optical system at its minimum focal length;

[0026] Figure 8This is a multi-field diffraction transfer function diagram of an optical system at its minimum focal length;

[0027] Figure 9 This is a field curvature analysis diagram of the optical system;

[0028] Figure 10 This is a distortion analysis diagram of an optical system;

[0029] Figure 11 This is a field-of-view analysis diagram of the optical system.

[0030] Reference numerals: Front fixed lens group 1, first lens 101, second lens 102, third lens 103, first sub-lens 1031, second sub-lens 1032, zoom lens group 2, fourth lens 201, fifth lens 202, compensation lens group 3, sixth lens 301, third sub-lens 3011, fourth sub-lens 3012, seventh lens 302, fifth sub-lens 3021, sixth sub-lens 3022, seventh sub-lens 3023, eighth lens 303, ninth lens 304, eighth sub-lens 3041, ninth sub-lens 3042. Detailed Implementation

[0031] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0032] like Figures 1-11 As shown, a zoom endoscopic optical system comprises, in sequence along the optical axis from the object side to the image side: a front fixed lens group 1, a zoom lens group 2, and a compensation lens group 3. The front fixed lens group 1 includes a first lens 101, a second lens 102, and a third lens 103. The zoom lens group 2 is position-adjustable and includes a fourth lens 201 and a fifth lens 202. The compensation lens group 3 is position-adjustable and includes a sixth lens 301, a seventh lens 302, an eighth lens 303, and a ninth lens 304. The ninth lens 304 is an aspherical lens, while the first lens 101, the second lens 102, the third lens 103, the fourth lens 201, the fifth lens 202, the sixth lens 301, the seventh lens 302, and the eighth lens 303 are all spherical lenses.

[0033] Furthermore, the front fixed lens group 1 is fixedly set, while the positions of the zoom lens group 2 and the compensation lens group 3 are adjustable. During pipeline inspection, zooming is achieved by adjusting the positions of the zoom lens group 2 and the compensation lens group 3. The front fixed lens group 1, the zoom lens group 2, and the compensation lens group 3 each contain multiple lenses. The first lens 101 to the ninth lens 304 are arranged sequentially along the optical axis from the object side to the image side. Under the action of the front fixed lens group 1, the zoom lens group 2, and the compensation lens group 3, a 20x zoom of the optical system is achieved. The ninth lens 304 at the imaging end is set as an aspherical lens, while the first lens 101 to the eighth lens 303 are all spherical lenses. With the action of eight spherical lenses and one aspherical lens, the length of the optical system is reduced, the lens diameter is shortened, and the imaging quality is corrected. The use of an aspherical lens ensures edge accuracy and improves the imaging effect for detecting minute defects inside the pipeline.

[0034] Both the zoom lens group 2 and the compensation lens group 3 can move linearly along the optical axis. Spacing is formed between the front fixed lens group 1 and the zoom lens group 2, and between the zoom lens group 2 and the compensation lens group 3, to allow the zoom lens group 2 and the compensation lens group 3 to move. Furthermore, the zoom lens group 2 and the compensation lens group 3 move linearly along the optical axis. By adjusting the position of the zoom lens group 2 and the compensation lens group 3, the optical system can have different focal length states. The spacing set between the front fixed lens group 1 and the zoom lens group 2, and between the zoom lens group 2 and the compensation lens group 3, provides space for the zoom lens group 2 and the compensation lens group 3 to move.

[0035] When both zoom lens group 2 and compensation lens group 3 move towards the front fixed lens group 1 along the optical axis, the optical system is at its maximum focal length, and the image size is the largest. When zoom lens group 2 moves towards the front fixed lens group 1 along the optical axis, and compensation lens group 3 moves away from the front fixed lens group 1 along the optical axis, the optical system is at its minimum focal length, and the image size is the smallest. When zoom lens group 2 and compensation lens group 3 are in the middle of the above two states, the optical system is at its normal focal length, and the image size is normal, which is the middle size.

[0036] The first lens 101, the second lens 102, and the third lens 103 are tightly fitted together; the fourth lens 201 and the fifth lens 202 are tightly fitted together; the sixth lens 301, the seventh lens 302, and the eighth lens 303 are tightly fitted together; and a gap is formed between the ninth lens 304 and the eighth lens 303. Furthermore, there are no gaps between the first lens 101, the second lens 102, and the third lens 103; between the fourth lens 201 and the fifth lens 202; and between the sixth lens 301, the seventh lens 302, and the eighth lens 303, thus ensuring the imaging effect. The gap set between the ninth lens 304 and the eighth lens 303 ensures the focusing effect of the ninth lens 304.

[0037] The object-side surface of the first lens 101 is concave, and the image-side surface is convex. The object-side surface of the second lens 102 is planar, and the image-side surface is convex. The object-side surface of the third lens 103 is convex, and the image-side surface is concave. Furthermore, the third lens 103 includes a first sub-lens 1031 and a second sub-lens 1032. Both the object-side surfaces of the first sub-lens 1031 and the second sub-lens 1032 are convex, and their image-side surfaces are concave. The first lens 101 suppresses large field-of-view distortion, its concave object-side surface compresses the incident angle of edge rays, reducing barrel distortion, and its convex image-side surface compensates for central field distortion. The field brightness loss is reduced to meet wide-angle requirements; the second lens 102 controls spherical aberration and field curvature, its object-side plane reduces assembly sensitivity, and the image-side convex surface converges light, correcting the negative astigmatism of the first lens 101, thereby improving center resolution; the third lens 103 eliminates chromatic aberration and thermal drift, wherein the first sub-lens 1031 (convex-concave) uses high-refractive-index glass to converge light, the second sub-lens 1032 (convex-concave) uses low-dispersion material to cancel chromatic aberration, the curvature of the cemented interface is matched, and the blue / red light focus shift is eliminated, thereby reducing chromatic aberration and temperature drift.

[0038] The object side of the fourth lens 201 is flat, and the image side is concave. The object side of the fifth lens 202 is convex, and the image side is concave. Furthermore, the fourth lens 201 makes the image field flat, and its concave image side diverges edge rays, thereby reducing the field curvature. The fifth lens 202 achieves coma correction. The convex-concave combination balances the asymmetry of the oblique beam and achieves symmetry of the edge point spread function.

[0039] The object-side surface of the sixth lens 301 is flat, and the image-side surface is convex. The object-side surface of the seventh lens 302 is convex, and the image-side surface is concave. The object-side surface of the eighth lens 303 is convex, and the image-side surface is concave. The object-side surface of the ninth lens 304 is concave, and the image-side surface is convex. Furthermore, the ninth lens 304 includes the eighth sub-lens 3041 and the ninth sub-lens 3042. The object-side surfaces of both the eighth sub-lens 3041 and the ninth sub-lens 3042 are concave, and the image-side surfaces are both convex. Furthermore, the eighth lens 303 and the ninth lens 304 work together to achieve a symmetrical distribution of optical power. The convex surface of the eighth lens 303 converges light rays, and the concave surface diverges to suppress spherical aberration. The concave surface of the ninth lens 304 expands light rays, and the convex surface achieves final convergence to eliminate astigmatism, thereby reducing wavefront error.

[0040] The sixth lens 301 includes a third lens 3011 and a fourth lens 3012. The object side of the third lens 3011 is flat and the image side is concave. The object side and the image side of the fourth lens 3012 are both convex. The third lens 3011 (flat-concave) achieves a negative optical power design, thereby compressing the total length of the optical path. Its concave image side forms a stray light trap, improving the signal-to-noise ratio. The fourth lens 3012 (biconvex) compensates for the light loss of the front film and ensures the uniformity of edge illumination.

[0041] The seventh lens 302 includes a fifth lens 3021, a sixth lens 3022, and a seventh lens 3023. The object-side surface of the fifth lens 3021 is convex, and the image-side surface is flat. The object-side surface of the sixth lens 3022 is flat, and the image-side surface is concave. The object-side surface of the seventh lens 3023 is convex, and the image-side surface is concave. Furthermore, the convex-flat configuration of the fifth lens 3021 improves the anti-eccentricity tolerance and enhances the assembly eccentricity tolerance. The flat-concave configuration of the sixth lens 3022 eliminates image plane flattening and reduces field curvature distortion. The convex-concave configuration of the seventh lens 3023 achieves higher-order astigmatism correction and improves off-axis resolution.

[0042] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention; therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0043] Although this document frequently uses reference numerals from the figures, such as front fixed lens group 1, first lens 101, second lens 102, third lens 103, first sub-lens 1031, second sub-lens 1032, zoom lens group 2, fourth lens 201, fifth lens 202, compensation lens group 3, sixth lens 301, third sub-lens 3011, fourth sub-lens 3012, seventh lens 302, fifth sub-lens 3021, sixth sub-lens 3022, seventh sub-lens 3023, eighth lens 303, ninth lens 304, eighth sub-lens 3041, and ninth sub-lens 3042, the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of this utility model; interpreting them as any additional limitation would contradict the spirit of this utility model.

Claims

1. A zoom endoscopic optical system, characterized in that, Along the optical axis from the object side to the image side, the following components are arranged in sequence: a front fixed lens group (1), a zoom lens group (2), and a compensation lens group (3). The front fixed lens group (1) includes a first lens (101), a second lens (102), and a third lens (103). The zoom lens group (2) is adjustable in position and includes a fourth lens (201) and a fifth lens (202). The compensation lens group (3) is adjustable in position and includes a sixth lens (301), a seventh lens (302), an eighth lens (303), and a ninth lens (304). The ninth lens (304) is an aspherical lens, and the first lens (101), the second lens (102), the third lens (103), the fourth lens (201), the fifth lens (202), the sixth lens (301), the seventh lens (302), and the eighth lens (303) are all spherical lenses.

2. The zoom endoscopic optical system according to claim 1, characterized in that, Both the zoom lens group (2) and the compensation lens group (3) can move linearly along the optical axis. A distance is formed between the front fixed lens group (1) and the zoom lens group (2), and between the zoom lens group (2) and the compensation lens group (3) to allow the zoom lens group (2) and the compensation lens group (3) to move.

3. The zoom endoscopic optical system according to claim 1, characterized in that, The first lens (101), the second lens (102) and the third lens (103) are closely fitted together, the fourth lens (201) and the fifth lens (202) are closely fitted together, the sixth lens (301), the seventh lens (302) and the eighth lens (303) are closely fitted together, and a gap is formed between the ninth lens (304) and the eighth lens (303).

4. The zoom endoscopic optical system according to claim 1, characterized in that, The object side of the first lens (101) is concave and the image side is convex; the object side of the second lens (102) is flat and the image side is convex; and the object side of the third lens (103) is convex and the image side is concave.

5. A zoom endoscopic optical system according to claim 4, characterized in that, The third lens (103) includes a first lens (1031) and a second lens (1032). The object-side surfaces of the first lens (1031) and the second lens (1032) are both convex, and the image-side surfaces are both concave.

6. The zoom endoscopic optical system according to claim 1, characterized in that, The fourth lens (201) has a flat object side and a concave image side, while the fifth lens (202) has a convex object side and a concave image side.

7. The zoom endoscopic optical system according to claim 1, characterized in that, The object side of the sixth lens (301) is flat and the image side is convex; the object side of the seventh lens (302) is convex and the image side is concave; the object side of the eighth lens (303) is convex and the image side is concave; and the object side of the ninth lens (304) is concave and the image side is convex.

8. A zoom endoscopic optical system according to claim 7, characterized in that, The sixth lens (301) includes a third lens (3011) and a fourth lens (3012). The object side of the third lens (3011) is flat and the image side is concave. Both the object side and the image side of the fourth lens (3012) are convex.

9. A zoom endoscopic optical system according to claim 7, characterized in that, The seventh lens (302) includes a fifth lens (3021), a sixth lens (3022), and a seventh lens (3023). The object-side surface of the fifth lens (3021) is convex, and the image-side surface is flat. The object-side surface of the sixth lens (3022) is flat, and the image-side surface is concave. The object-side surface of the seventh lens (3023) is convex, and the image-side surface is concave.

10. A zoom endoscopic optical system according to claim 7, characterized in that, The ninth lens (304) includes an eighth lens (3041) and a ninth lens (3042). The object-side surfaces of the eighth lens (3041) and the ninth lens (3042) are both concave, and the image-side surfaces are both convex.

Images