Achromatic fluorescence laparoscope optical system

Abstract

The invention discloses an achromatic fluorescence laparoscope optical system, which consists of an endoscope group and an eyepiece. The endoscope group consists of an objective lens with positive optical power and a rod lens group with positive optical power. The objective lens consists of a first objective lens group and a second objective lens group. The second objective lens group includes a first cemented lens and a second cemented lens. The system has the advantages that by reasonably arranging the optical power distribution of the lens, the use requirements can be met, and it is ensured that the endoscope group can adjust the visible light and fluorescence states at any time when in use without additional debugging, and a margin is reserved for the rod lens group of subsequent image transfer; at the same time, by reasonably arranging the optical power distribution of the lens and the design of the cemented lens, and appropriately controlling the length of the objective lens, the light can be smoothly propagated in the objective lens, the sensitivity of the lens can be reduced, the direction of the light beam can be adjusted, the chromatic aberration caused by the visible light and fluorescence bands can be suppressed, the aberration can be corrected, and the imaging quality can be improved.

Description

Technical Field

[0001] The invention relates to a laparoscope optical system, in particular to an achromatic fluorescence laparoscope optical system. Background Art

[0002] In the field of medical equipment, endoscopes can penetrate into narrow areas inside the human body for doctors to observe lesions. Among them, laparoscopes have longer and harder tubes and can be used to treat diseases in the abdominal cavity and inside the abdominal cavity. The wound is small and the patient recovers quickly. Laparoscopes usually consist of three parts: objective lens, rod lens and eyepiece. The objective lens is aimed at the surgical site, and the main imaging rays are parallel to each other. It has the characteristics of image telecentricity, which is convenient for subsequent imaging; the rod lens and the object image are double telecentric, and the image formed by the objective lens is rotated multiple times with the same magnification. It is usually a combination of multiple sets of identical rod lenses to extend the working length of the laparoscope; the eyepiece object side re-images the image transmitted by the rod lens, and cooperates with the optical adapter to provide the final close-up image.

[0003] With the development of related medical technologies, such as the clinical application of fluorescence imaging technology or photodynamic therapy, more requirements are put forward for the use band of endoscopes. Fluorescence imaging technology uses specific fluorescent probes to mark target molecules, that is, to stain the diseased cells, so that the boundary between the diseased tissue and the healthy tissue is more obvious, and then a fluorescent endoscope is used to detect the fluorescent molecules; photodynamic therapy injects photosensitizers into the patient's veins, guides the laser to the lesion site with the help of a fluorescent endoscope or optical fiber, excites the photosensitizer to emit fluorescence for positioning, and uses in vitro laser irradiation to excite oxygen molecules to produce active singlet oxygen to destroy the diseased cells, so as to achieve the purpose of treatment and avoid the large wounds caused by surgery. In summary, the fluorescence endoscope not only has the real image recognition function of the surface of human tissues of conventional white light endoscopes, so that doctors can judge the condition based on professional knowledge and experience, but also has the fluorescence imaging function of the tissues below the surface, which improves the visibility of the lesion area, plays a key role in accurate positioning during surgery and reducing surgical risks, and is widely used in clinical surgery.

[0004] The current fluorescent laparoscope has the following characteristics in use:

[0005] 1) The use band of white light laparoscope is 400~700nm, and the fluorescence laparoscope adds the near-infrared band of 800~900nm on this basis, and its spectral range becomes larger, and the chromatic aberration problem is more obvious. The Chinese invention patent with announcement number CN111657823B provides an endoscope adapter optical system, which balances the chromatic aberration caused by the wide spectral range of 400nm~1000nm through two groups of double-cemented lenses with negative optical focal length, and sets a single lens with positive optical focal length between the two groups of lenses to meet the imaging requirements. It has good imaging quality, simple structure and small size; but as an adapter, that is, an eyepiece with an imaging detector at the image plane end, its image plane size is limited by the imaging detector. Therefore, when the optical system is set in reverse on the side of the objective end, there is a problem of small field of view and failure to meet the use requirements.

[0006] 2) In order to observe the lesion area more comprehensively, the laparoscope usually has a larger field of view. The closer the field of view is to the edge, the image magnification changes, which causes distortion. At the same time, the rod mirror of the traditional laparoscope is a relay mirror group, which is composed of multiple groups of 1:1 symmetrical image transfer systems with the same optical structure. The front and back are used in conjunction with the objective lens and the eyepiece respectively. If there is a slight error in the mechanical coordination between the two, it will cause various large aberrations, affecting the observation effect. The US patent number US11520135B2 provides a rigid tube endoscope optical system, which corrects the image tilt by controlling the eccentricity of several lenses in front of the objective lens, suppresses coma and chromatic aberration, improves the image clarity, and sets a double cemented lens in the rod mirror to cooperate with the imaging; but the design of the fluorescence band and the viewing angle is not considered.

[0007] 3) In order to better adapt to the application scenarios, some endoscopes are equipped with multiple viewing prisms to deflect light and obtain images in multiple directions. The Chinese invention patent application with publication number CN116763233A provides an endoscope optical system with multiple viewing angles, which realizes the steering of light beams by superimposing multiple prisms and uses aspherical surfaces to reduce distortion; however, the use of fluorescence bands and chromatic aberration issues are not considered. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide an achromatic fluorescence laparoscope optical system which can have relatively small optical aberration in a large spectral range including the fluorescence band.

[0009] The technical solution adopted by the present invention to solve the above technical problems is: an achromatic fluorescence laparoscope optical system, which is composed of an endoscope group and an eyepiece, wherein the endoscope group is composed of an objective lens with positive optical power and a rod lens group with positive optical power, and the focal length of the endoscope group in the visible light band is f _e The focal length of the endoscope assembly in the fluorescence band is f _fluThe focal length of the objective lens in the visible light band is f 1_e , the focal length of the eyepiece in the visible light band is f 3_e , satisfying the relationship: 3≤|f 3_e / f 1_e |≤7,0.99≤f _e / f _flu ≤1.01,0.99≤|f _e / f 1_e |≤1.01, the length of the objective lens is t1, satisfying the relationship: 30mm<t1<40mm, the objective lens is composed of a first objective lens group and a second objective lens group, and in the visible light band, the focal length of the first objective lens group is f 100_e , the focal length of the second objective lens group is f 200_e , satisfying the relationship: 0.3≤f 100_e / f 200_e ≤0.9, the second objective lens group includes a first cemented lens and a second cemented lens, the first cemented lens is composed of a third lens and a fourth lens, the second cemented lens is composed of a fifth lens and a sixth lens, and the curvature radius of the cemented surface of the first cemented lens is R 胶合1 The radius of curvature of the bonding surface of the second bonding lens is R 胶合2 , the distance between the two bonding surfaces is D, satisfying the relationship: 0.1mm -1 ≤|D / R 胶合1 / R 胶合2 |≤0.5mm -1 .

[0010] Compared with the prior art, the advantage of the present invention is that by reasonably arranging the optical focal length distribution of the lens, it can meet the use requirements, ensure that the endoscope group can adjust the visible light and fluorescence states at any time during use, without additional debugging, and leave a margin for the subsequent image transfer rod lens group; at the same time, by reasonably arranging the optical focal length distribution of the lens and the design of the cemented lens, and properly controlling the length of the objective lens, the light can be propagated smoothly in the objective lens, the sensitivity of the lens is reduced, the direction of the light beam can be adjusted, the chromatic aberration caused by the visible light and fluorescence bands can be suppressed, the aberration can be corrected, and the imaging quality can be improved.

[0011] Preferably, the second objective lens group further includes a first aspheric lens with both the object side and the image side being aspheric, and the first aspheric lens is arranged on the object side of the first cemented lens. This structure can control the direction of light in different fields of view at a high light height, suppress distortion, and improve imaging quality.

[0012] Preferably, the first objective lens group is composed of a protective glass, a first lens, a viewing prism and a second lens, and the dispersion coefficients of the third lens, the fourth lens, the fifth lens and the sixth lens are Vd3, Vd4, Vd5 and Vd6 respectively, satisfying the relationship: 45≤|Vd3-Vd4|≤65, 60≤|Vd5-Vd6|≤80. By selecting specific materials, the chromatic aberration can be suppressed by not exceeding the lower limit of the relationship, and the chromatic aberration can be prevented from being overcorrected by not exceeding the upper limit.

[0013] Preferably, the first lens is an aspheric lens with negative focal power, a convex object side surface and a concave image side surface, and the second lens has positive focal power, a flat object side surface and a convex image side surface. In this structure, the first lens collects and diverges object-side light to ensure sufficient field of view for observation. The aspheric design allows the light from the edge of the field of view to pass more smoothly, reducing the sensitivity and aberration of the lens, while the second lens can appropriately suppress the divergence angle of the light, correct the aberration caused by the first lens, and improve the imaging quality.

[0014] Preferably, the protective glass material is sapphire. The protective glass material is sapphire, which can isolate the human body environment and the laparoscope without affecting its optical properties, and can adapt to the sterilization or disinfection environment.

[0015] Preferably, the viewing prism is composed of a first prism, a second prism and a third prism which are arranged in sequence from the object side to the image side and glued to each other. According to the light beam path, the object side surface of the first prism is the light beam incident surface, the upper surface of the first prism glued to the second prism is the transmission surface, the surface of the second prism glued to the third prism is the primary reflection surface, the lower surface of the first prism glued to the second prism is the secondary reflection surface, and the image side surface of the second prism is the light beam exit surface.

[0016] Preferably, the rod lens group is composed of three imaging rod lenses with the same optical structure, and the focal length of the imaging rod lenses in the visible light band is f 2_e , satisfying the relationship: 0<|1 / f 2_e |≤0.005mm -1 The imaging rod lens is composed of two symmetrically arranged rod lens units, the rod lens unit close to the object side is composed of a seventh lens, an eighth lens, a ninth lens and a tenth lens, and the dispersion coefficients of the seventh lens, the eighth lens, the ninth lens and the tenth lens are Vd7, Vd8, Vd9 and Vd 10 , satisfying the relationship: 20≤|Vd7-Vd8|≤25, 30≤|Vd8-Vd9|≤35, 40≤|Vd9-Vd 10|≤45. The focal length of the imaging rod lens is controlled to be close to infinity, and the double telecentricity of the object and image is realized, so that the lens and the eyepiece can be better connected. By selecting materials, the direction of light beams in different bands can be controlled, chromatic aberration can be suppressed, and excessive chromatic aberration correction can be prevented.

[0017] Preferably, the seventh lens has a positive optical power, the eighth lens is a double concave lens with negative optical power, the ninth lens has a positive optical power, the tenth lens has a negative optical power, the object side surface is convex, and the image side surface is concave.

[0018] Preferably, the seventh lens has a positive optical power, the eighth lens is a double flat rod lens without optical power, the ninth lens has a positive optical power, the tenth lens has a negative optical power, the object side is convex, and the image side is concave.

[0019] Preferably, the magnification of the eyepiece is β 3, the entrance pupil position is ENP, the entrance pupil diameter is END, the object side aperture angle is NA2, the object side principal ray incident angle of the eyepiece is CRA2, the exit pupil position of the rod lens group is EXP, the exit pupil diameter is EXD, the image side aperture angle is NA1, and the object side principal ray incident angle of the rod lens group is CRA1, satisfying the relationship: 0.99≤ENP / EXP≤1.01, 0.99≤END / EXD≤1.01; 0°≤|NA2-NA1|≤0.5°; 0°≤|CRA2-CRA1|≤0.5°, 0.95≤ β 3≤1.15. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of an achromatic fluorescence laparoscope optical system according to an embodiment of the present invention;

[0021] Figure 2 It is a schematic structural diagram of a viewing prism composed of three optical elements in an embodiment of the present invention;

[0022] Figure 3 is a schematic diagram of one structure of the first objective lens group in an embodiment of the present invention;

[0023] Figure 4 Schematic diagram of an optical system of an objective lens and an imaging rod lens in Example 1 of an embodiment of the present invention;

[0024] Figure 5 This is a transfer function curve diagram of Example 1 in the visible light band in an embodiment of the present invention;

[0025] Figure 6 This is a transfer function curve diagram of Example 1 in the fluorescence band in an embodiment of the present invention;

[0026] Figure 7is a vertical axis chromatic aberration diagram of Example 1 in an embodiment of the present invention;

[0027] Figure 8 is a field curvature diagram of Example 1 in an embodiment of the present invention;

[0028] Fig. 9 is a distortion diagram of Example 1 in an embodiment of the present invention;

[0029] Fig.10 Schematic diagram of an optical system of an objective lens and an imaging rod lens in Example 2 of an embodiment of the present invention;

[0030] Fig.11 This is a transfer function curve diagram of Example 2 in the visible light band in an embodiment of the present invention;

[0031] Fig.12 This is a transfer function curve diagram of Example 2 in the fluorescence band in the embodiment of the present invention;

[0032] Fig.13 is a vertical axis chromatic aberration diagram of Example 2 in an embodiment of the present invention;

[0033] Fig.14 is a field curvature diagram of Example 2 in an embodiment of the present invention;

[0034] Fig.15 is a distortion diagram of Example 2 in an embodiment of the present invention;

[0035] Fig.16 Schematic diagram of an optical system of an objective lens and an imaging rod lens in Example 3 of an embodiment of the present invention;

[0036] Fig.17 This is a transfer function curve diagram of Example 3 in the visible light band in an embodiment of the present invention;

[0037] Fig.18 This is a transfer function curve diagram of Example 3 in the fluorescence band in the embodiment of the present invention;

[0038] Fig.19 : is a vertical axis chromatic aberration diagram of Example 3 in an embodiment of the present invention;

[0039] Fig. 20 This is a field curvature diagram of Example 3 in an embodiment of the present invention;

[0040] Fig.21 : is a distortion diagram of Example 3 in an embodiment of the present invention;

[0041] Fig. 22 Schematic diagram of an optical system of an objective lens and an imaging rod lens in Example 4 of an embodiment of the present invention;

[0042] Fig.23 This is a transfer function curve diagram of Example 4 in the visible light band in an embodiment of the present invention;

[0043] Fig.24 This is a transfer function curve diagram of Example 4 in the fluorescence band in the embodiment of the present invention;

[0044] Fig.25 is a vertical axis chromatic aberration diagram of Example 4 in an embodiment of the present invention;

[0045] Fig.26 is a field curvature diagram of Example 4 in an embodiment of the present invention;

[0046] Fig. 27 4 is a distortion diagram of Example 4 in an embodiment of the present invention;

[0047] Fig.28 Schematic diagram of an optical system of an objective lens and an imaging rod lens in Example 5 of an embodiment of the present invention;

[0048] Fig.29 This is a transfer function curve diagram of Example 5 in the visible light band according to an embodiment of the present invention;

[0049] Fig.30 This is a transfer function curve diagram of Example 5 in the fluorescence band in the embodiment of the present invention;

[0050] Fig.31 is a vertical axis chromatic aberration diagram of Example 5 in an embodiment of the present invention;

[0051] Fig.32 is a field curvature diagram of Example 5 in an embodiment of the present invention;

[0052] Fig.33 1 is a distortion diagram of Example 5 in an embodiment of the present invention;

[0053] Fig.34 Schematic diagram of an optical system of an objective lens and an imaging rod lens in Example 6 of an embodiment of the present invention;

[0054] Fig.35 This is a transfer function curve diagram of Example 6 in the visible light band in an embodiment of the present invention;

[0055] Fig.36 This is a transfer function curve diagram of Example 6 in the fluorescence band in the embodiment of the present invention;

[0056] Fig.37 is a vertical axis chromatic aberration diagram of Example 6 in an embodiment of the present invention;

[0057] Fig.38 is a field curvature diagram of Example 6 in an embodiment of the present invention;

[0058] Fig.39 This is a distortion diagram of Example 6 in the embodiment of the present invention.

[0059] Description of reference numerals:

[0060] 1. Objective lens; 100, first objective lens group; G1, protective glass; L1, first lens; G2, viewing prism; G201, first prism; G202, second prism; G203, third prism; L2, second lens; 200, second objective lens group; L3, third lens; L4, fourth lens; L5, fifth lens; L6, sixth lens; L11, first aspheric lens;

[0061] 2, rod lens group; 300, rod lens unit; L7, seventh lens; L8, eighth lens; L9, ninth lens; L10, tenth lens;

[0062] 3. Eyepiece;

[0063] S1, light beam incident surface; S2, transmission surface; S3, primary reflection surface; S4, secondary reflection surface; S5, light beam exit surface. DETAILED DESCRIPTION

[0064] The following is a detailed description of the embodiments of the present invention in conjunction with the accompanying drawings. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention. Example

[0065] In the drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of explanation, and the drawings are only embodiments and are not drawn strictly to scale.

[0066] In the present application, the focal length of the lens and the lens group is described based on the wavelength band used, and the subscripts e and flu are used to represent 546nm (visible light band) and 835nm (fluorescence band). In the physical parameter table of the specific embodiment, the refractive index and dispersion coefficient values ​​of the material are described based on the d-line, and the wavelength of the d-line is 587.56nm.

[0067] In the figure captions, the diffraction limit indicates the theoretical maximum value of the optical system, and T and S indicate the meridian and sagittal directions, respectively. Since the diffraction limit values ​​in the two directions are the same, they are combined into the diffraction limit-TS; 0°-T indicates the meridian direction of the central field of view, 0°-S indicates the sagittal direction of the central field of view, 40°-T indicates the meridian direction of the edge field of view, and 40°-S indicates the sagittal direction of the edge field of view.

[0068] In an exemplary embodiment, the aspheric lens used to improve the imaging quality of the lens and reduce distortion has a surface shape that satisfies the following equation:

[0069] .

[0070] Wherein, y represents the radial coordinate value of the lens perpendicular to the optical axis, Z(y) is the vector height of the aspheric lens from the aspheric vertex when it is at a height of y along the optical axis, c=1 / R, R represents the central curvature radius of the corresponding aspheric lens surface, k represents the cone coefficient, and parameters A, B, and C are the 2nd, 4th, and 6th order coefficients of the high-order aspheric polynomial, respectively.

[0071] An achromatic fluorescence laparoscope optical system, such as Figure 1 As shown, from the object side to the image side, there are an objective lens 1 with positive optical power, a rod lens group 2 with positive optical power, and an eyepiece 3 with positive optical power. The objective lens 1 and the rod lens group 2 form an endoscope group, and the primary imaging surface I is between the objective lens 1 and the rod lens group 2, and the secondary imaging surface II is between the rod lens group 2 and the eyepiece 3. In the present application, the image quality evaluation indicators such as transfer function, field curvature, and distortion of each embodiment are obtained on the secondary imaging surface II.

[0072] The focal length f of objective lens 1 in the visible light band _1_e The focal length f of the eyepiece 3 in the visible light band _3_e Satisfies the following relationship: 3≤|f _3_e / f _1_e |≤7, and the optical power distribution between the objective lens 1 and the eyepiece 3 can be controlled according to the relationship, so as to control the field of view angle and focal length of the laparoscope optical system and meet the use requirements.

[0073] The focal length f of the endoscope group consisting of objective lens 1 and rod lens group 2 in the visible light band _e and the focal length f in the fluorescence band _flu Satisfies the following relationship: 0.99≤f _e / f _flu ≤1.01, ensuring that the laparoscope can be adjusted to switch between visible light and fluorescence at any time during use without additional debugging.

[0074] In the visible light band, the focal length f of the endoscope group is _e and the focal length f of objective lens 1 _１_e Satisfies the relationship: 0.99≤|f _e / f _１_e |≤1.01, controlling the focal length of the objective lens 1 to be close to the focal length of the endoscope group can enable the objective lens 1 to image the scene and leave a margin for the subsequent image transfer of the rod lens group 2.

[0075] The objective lens 1 is composed of a first objective lens group 100 and a second objective lens group 200 from the object side to the image side. The first objective lens group 100 collects the light beam from the object side and diverges it to the image side for subsequent processing. The second objective lens group 200 receives the light beam transmitted from the first objective lens group 100 and completes the first imaging after correcting the aberration.

[0076] In the visible light band, the focal length f of the first objective lens group 100 is100_e and the focal length f of the second objective lens group 200 200_e Satisfy the relationship: 0.3≤f 100_e / f 200_e ≤0.9, the length of objective lens 1 is t1, satisfying the relationship: 30mm<t1<40mm, controlling the optical focal length of the two objective lens groups, limiting the speed at which the first objective lens group 100 collects light by controlling the lower limit of t1, and properly controlling the length of objective lens 1, and ensuring that the second objective lens group 200 has enough space to adjust the direction of the light beam and correct the aberration by controlling the upper limit of t1, so that the light propagates smoothly in objective lens 1 and reduces the sensitivity of the lens.

[0077] The first objective lens group 100 includes, from the object side to the image side, a protective glass G1 , a first lens L1 , a viewing prism G2 , and a second lens L2 .

[0078] The material of protective glass G1 is sapphire, which has the characteristics of high hardness, corrosion resistance, high temperature resistance, stable chemical properties, and high transmittance. As the first lens of the laparoscope, it can isolate the human body environment and the laparoscope without affecting its optical properties, and adapt to sterilization or disinfection environments.

[0079] The first lens L1 has negative optical power, a convex surface on the object side and a concave surface on the image side. Both surfaces are aspherical. It is used to collect object light and diverge it to ensure sufficient observation field of view. The aspherical design enables the light from the edge of the field to pass more smoothly, reducing lens sensitivity and aberrations.

[0080] The second lens L2 has positive optical power, a flat object side and a convex image side, which can appropriately suppress the light divergence angle, correct the aberration caused by the first lens L1, and improve the imaging quality.

[0081] The second objective lens group 200 includes two doublet lenses. The first doublet lens close to the object side is composed of a third lens L3 and a fourth lens L4, and the second doublet lens close to the image side is composed of a fifth lens L5 and a sixth lens L6.

[0082] The dispersion coefficients of the third lens L3, the fourth lens L4, the fifth lens L5 and the sixth lens L6 are Vd3, Vd4, Vd5 and Vd6 respectively. Appropriate materials are selected to satisfy the relationship: 45≤|Vd3-Vd4|≤65, 60≤|Vd5-Vd6|≤80. The chromatic aberration can be suppressed by controlling the lower limit, and the excessive correction of chromatic aberration can be prevented by controlling the upper limit.

[0083] The cemented surface S of the third lens L3 and the fourth lens L4 胶合1 The radius of curvature is R 胶合1 , the cemented surface S of the fifth lens L5 and the sixth lens L6 胶合2 The radius of curvature is R 胶合2, the distance between the two bonding surfaces is D, satisfying the relationship: 0.1mm -1 ≤|D / R 胶合1 / R 胶合2 |≤0.5mm -1 By controlling the lower limit, we can ensure that the light is converged onto the imaging surface, while by controlling the upper limit, the light can be propagated smoothly, the generation of aberrations can be suppressed, and the sensitivity of the lens can be reduced.

[0084] The second objective lens group 200 may further include a first aspheric lens L11 whose object side surface and image side surface are both aspheric. The first aspheric lens L11 is located on the object side of the first double cemented lens, and can control the direction of light in different fields of view at a high light height, suppress distortion, and improve imaging quality.

[0085] In the first objective lens group 100, the viewing prism G2 may be an optical component that only allows light to pass through, and at this time, the angle between the incident surface and the exit surface of the light is 0°.

[0086] like Figure 2 As shown, the viewing prism G2 can also be a viewing prism composed of three optical elements, which is composed of a first prism G201, a second prism G202 and a third prism G203 arranged in sequence from the object side to the image side and glued to each other. According to the beam path, the object side surface of the first prism G201 is the beam incident surface S1, the upper surface where the first prism G201 and the second prism G202 are glued is the transmission surface S2, the surface where the second prism G202 and the third prism G203 are glued is the primary reflection surface S3, the lower surface where the first prism G201 and the second prism G202 are glued is the secondary reflection surface S4, and the image side surface of the second prism G202 is the beam exit surface S5. One structure of the first objective lens group 100 is as follows: Figure 3 As shown, the object side of the second prism G202 is glued to the first lens L1 to play the role of light transmission and support.

[0087] When the angle between the beam incident surface S1 and the beam exit surface S5 is 30°, a viewing angle of 30° can be achieved; when the angle between the beam incident surface S1 and the beam exit surface S5 is 45°, a viewing angle of 45° can be achieved, completing a more comprehensive observation.

[0088] The rod lens group 2 is composed of three imaging rod lenses with the same optical structure. Each imaging rod lens is composed of two symmetrically arranged rod lens units 300, forming a one-to-one symmetrical image transfer system.

[0089] The focal length of the imaging rod lens in the visible light band is f 2_e , satisfying the relationship: 0<|1 / f 2_e |≤0.005mm -1, control the upper limit, make the focal length of the imaging rod lens close to infinity, that is, make the focal length of the rod lens group 2 close to infinity, realize the double telecentricity of the object and image, and better connect with the objective lens 1 and the eyepiece 3.

[0090] The rod mirror unit 300 close to the object side is composed of a seventh lens L7, an eighth lens L8, a ninth lens L9 and a tenth lens L10. The seventh lens L7 has positive refractive power and serves as a first lens to collect the front light beam.

[0091] When the eighth lens L8 is a double concave lens, the optical power is negative, and it can cooperate with the seventh lens L7 to properly control the direction of light for subsequent imaging; when the eighth lens L8 is a double flat rod lens, it has no optical power and only serves to extend the optical path.

[0092] The ninth lens L9 has positive refractive power.

[0093] The tenth lens L10 has negative optical power, a concave object-side surface, and a convex image-side surface.

[0094] The dispersion coefficients of the seventh lens L7, the eighth lens L8, the ninth lens L9 and the tenth lens L10 are Vd7, Vd8, Vd9 and Vd 10 , satisfying the relationship: 20≤|Vd7-Vd8|≤25, 30≤|Vd8-Vd9|≤35, 40≤|Vd9-Vd 10 |≤45. By controlling the lower limit, the direction of light beams in different bands can be guided to suppress chromatic aberration, and by controlling the upper limit, excessive chromatic aberration correction can be prevented.

[0095] The seventh lens L7, the eighth lens L8, the ninth lens L9 and the tenth lens L10 can be glued together in sequence to reduce the number of interfaces between the lenses and the air and reduce the light energy loss of the light beam on the lens surface. At the same time, the four-cemented lens can improve the alignment accuracy when assembling the lens barrel and reduce the manufacturing cost.

[0096] The seventh lens L7 and the eighth lens L8 may form a doublet lens, and the ninth lens L9 and the tenth lens L10 may form a doublet lens, and the optical path may be appropriately extended by an air layer between the two doublet lenses, and the difficulty of assembling the doublet lenses may be reduced.

[0097] The imaging of the objective lens 1 on the primary imaging surface still has aberrations such as field curvature, distortion and chromatic aberration. The aberrations can be corrected again through the secondary imaging of the rod lens group 2 to obtain a higher quality imaging result on the secondary imaging surface.

[0098] The optical power of the eyepiece 3 is positive, and it works in the visible light and fluorescence bands like the objective lens 1 and the rod lens group 2.

[0099] The eyepiece 3 and the rod lens group 2 must meet the pupil matching principle: the entrance pupil position ENP of the eyepiece 3 coincides with the exit pupil position EXP of the rod lens group 2: 0.99≤ENP / EXP≤1.01, the entrance pupil diameter END of the eyepiece 3 is the same as the exit pupil diameter EXD of the rod lens group 2: 0.99≤END / EXD≤1.01; in addition, the relevant angles of the eyepiece 3 and the rod lens group 2 must also meet the relevant conditions: the object side aperture angle NA2 of the eyepiece 3 and the image side aperture angle NA1 of the rod lens group 2 satisfy the relationship: 0°≤|NA2-NA1|≤0.5°, the object side chief ray incident angle CRA2 of the eyepiece 3 and the object side chief ray incident angle CRA1 of the rod lens group 2 satisfy the relationship: 0°≤|CRA2-CRA1|≤0.5°, the magnification of the eyepiece 3 β 3Satisfy the relationship: 0.95≤ β 3≤1.15. By limiting the above relationship, the eyepiece 3 can be well connected with the rod lens group 2 on the object side, achieving the effects of high imaging resolution and high relative illumination.

[0100] At the same time, since the aberration of the optical system is mainly corrected in the objective lens 1 and the rod lens group 2, the aberration correction function of the eyepiece 3 is relatively light, and there is a small field curvature and distortion. The field curvature FC3 of the eyepiece 3 satisfies: 0≤|FC3|≤0.08mm, and the distortion TD3 satisfies: 0≤|TD3|≤0.8%.

[0101] Based on the above description, an example of an imaging rod lens for the objective lens 1 and the rod lens group 2 will be described in detail below in conjunction with the accompanying drawings.

[0102] Example 1:

[0103] like Figure 4 As shown, the objective lens 1 is arranged in sequence from the object side to the image side with a protective glass G1, a first lens L1, a viewing prism G2, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5 and a sixth lens L6, and the object side surface and the image side surface of the first lens L1 are both aspherical surfaces.

[0104] Among them, the third lens L3 is a biconvex lens, the fourth lens L4 is a meniscus lens, and the two constitute a first double cemented lens; the fifth lens L5 is a biconvex lens, the sixth lens L6 is a meniscus lens, and the two constitute a second double cemented lens.

[0105] like Figure 4 As shown, the imaging rod lens sequentially arranges the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the tenth lens L10, the ninth lens L9, the eighth lens L8 and the seventh lens L7 from the object side to the image side, wherein the seventh lens L7, the eighth lens L8, the ninth lens L9 and the tenth lens L10 are sequentially cemented to form a four-cemented lens group.

[0106] Some physical and optical parameters of this example are shown in Table 1.

[0107] Table 1

[0108]

[0109] The aspheric surface parameters of this example are shown in Table 2. Except for those listed in the table, the remaining high-order coefficients are zero.

[0110] Table 2

[0111]

[0112] The transfer function curves of this example are as follows Figure 5 and Figure 6 As shown, vertical axis chromatic aberration is Figure 7 As shown, the field curvature is Figure 8 As shown, the distortion is Fig. 9 shown.

[0113] Figure 5 It shows that in this example, at the visible light band and 120lp / mm, the MTF value of the center field of view is greater than 0.5, and the MTF value of the edge field of view is greater than 0.4, which has the characteristics of higher resolution.

[0114] Figure 6 It shows that in this example, at the fluorescence band and 120lp / mm, the MTF value of the center field of view is about 0.3, and the MTF value of the edge field of view is greater than 0.25, which has the characteristics of higher resolution.

[0115] Figure 7 The vertical axis chromatic aberration of this example is shown to be small, less than 1um.

[0116] Figure 8 It shows that the sagittal field curvature of this example in the visible light and fluorescence bands is small, about 0.04mm.

[0117] Fig. 9 It shows that the distortion of this example in the visible light and fluorescence bands is relatively small, at around 7%.

[0118] Example 2:

[0119] like Fig.10 As shown, this example is based on Example 1, and mainly changes the surface shapes of the third lens L3 and the fourth lens L4 and the combination of the imaging rod lenses, so that the path of the light between the cemented lenses is smoother.

[0120] Among them, the third lens L3 is a biconcave lens, the fourth lens L4 is a biconvex lens, and the two form a double cemented lens group; the seventh lens L7 and the eighth lens L8 form a double cemented lens group, and the ninth lens L9 and the tenth lens L10 form a double cemented lens group.

[0121] Some physical optical parameters of this example are shown in Table 3.

[0122] Table 3

[0123]

[0124] The aspheric surface parameters of this example are shown in Table 4. Except for those listed in the table, the remaining high-order coefficients are zero.

[0125] Table 4

[0126]

[0127] The transfer function curves of this example are as follows Fig.11 and Fig.12 As shown, vertical axis chromatic aberration is Fig.13 As shown, the field curvature is Fig.14 As shown, the distortion is Fig.15 shown.

[0128] Fig.11 It shows that in this example, at 120lp / mm in the visible light band, the MTF value of the center field of view is greater than 0.5, and the MTF value of the edge field of view is greater than 0.4, which has the characteristics of higher resolution.

[0129] Fig.12 It shows that in this example, at the fluorescence band and 120lp / mm, the MTF value of the center field of view is about 0.3, and the MTF value of the edge field of view is greater than 0.2, which has the characteristics of higher resolution.

[0130] Fig.13 The vertical axis chromatic aberration of this example is shown to be small, less than 2um.

[0131] Fig.14 It shows that the sagittal field curvature of this example in the visible light and fluorescence bands is small, about 0.06mm.

[0132] Fig.15 It shows that the distortion of this example in the visible light and fluorescence bands is relatively small, at around 6.9%.

[0133] Example 3:

[0134] like Fig.16 As shown, this example is based on Example 1, and mainly changes the surface shape of the double cemented lens in the objective lens 1, so that the path of the light between the cemented lenses is smoother.

[0135] Among them, the third lens L3 is a meniscus lens, the fourth lens L4 is a biconvex lens, and the two constitute a first double cemented lens; the fifth lens L5 is a biconcave lens, and the sixth lens L6 is a biconvex lens, and the two constitute a second double cemented lens.

[0136] Some physical and optical parameters of this example are shown in Table 5.

[0137] Table 5

[0138]

[0139] The aspheric surface parameters of this example are shown in Table 6. Except for those listed in the table, the remaining high-order coefficients are zero.

[0140] Table 6

[0141]

[0142] The transfer function curves of this example are as follows Fig.17 and Fig.18 As shown, vertical axis chromatic aberration is Fig.19 As shown, the field curvature is Fig. 20 As shown, the distortion is Fig.21 shown.

[0143] Fig.17 It shows that in this example, at 120lp / mm in the visible light band, the MTF value of the center field of view is greater than 0.5, and the MTF value of the edge field of view is about 0.4, which has the characteristics of higher resolution.

[0144] Fig.18 It is shown that in this example, at the fluorescence band and 120lp / mm, the MTF value of the center field of view is about 0.3, and the MTF value of the edge field of view is about 0.3, which is improved compared with Example 1 and has the characteristics of higher resolution.

[0145] Fig.19 The vertical axis chromatic aberration of this example is shown to be small, less than 2um.

[0146] Fig. 20 It shows that the sagittal field curvature of this example in the visible light and fluorescence bands is about 0.09mm.

[0147] Fig.21 It shows that the distortion of this example in the visible light and fluorescence bands is around 7%.

[0148] Example 4:

[0149] like Fig. 22 As shown, this example is based on Example 1, and mainly adds an eleventh lens L11 on the object side of the first double cemented lens. Both surfaces of this lens are aspherical, which is used to adjust the direction of light in different fields of view, suppress aberrations, and improve imaging quality.

[0150] Some physical and optical parameters of this example are shown in Table 7.

[0151] Table 7

[0152]

[0153] The aspheric surface parameters of this example are shown in Table 8. Except for those listed in the table, the remaining high-order coefficients are zero.

[0154] Table 8

[0155]

[0156] The transfer function curves of this example are as follows Fig.23 and Fig.24 As shown, vertical axis chromatic aberration is Fig.25 As shown, the field curvature is Fig.26 As shown, the distortion is Fig. 27 shown.

[0157] Fig.23 It shows that in this example, at the visible light band and 120lp / mm, the MTF value of the center field of view is greater than 0.5, and the MTF value of the edge field of view is greater than 0.4, which has the characteristics of higher resolution.

[0158] Fig.24 It is shown that in this example, at the fluorescence band and 120lp / mm, the MTF value of the central field of view is about 0.3, and the MTF value of the edge field of view is about 0.3, which is improved compared with Example 1 and has the characteristics of higher resolution.

[0159] Fig.25 The vertical axis chromatic aberration of this example is shown to be small, less than 1.5um.

[0160] Fig.26 It shows that the sagittal field curvature of this example in the visible light and fluorescence bands is about 0.09mm.

[0161] Fig. 27 It shows that the distortion of this example in the visible light and fluorescence bands is around 7%.

[0162] Example 5:

[0163] like Fig.28 As shown, this example is based on Example 2, and mainly adds an eleventh lens L11 on the object side of the first double cemented lens. Both surfaces of this lens are aspherical, which is used to adjust the direction of light in different fields of view, suppress aberrations, and improve imaging quality.

[0164] Some physical and optical parameters of this example are shown in Table 9.

[0165] Table 9

[0166]

[0167] The aspheric surface parameters of this example are shown in Table 10. Except for those listed in the table, the remaining high-order coefficients are zero.

[0168] Table 10

[0169]

[0170] The transfer function curves of this example are as follows Fig.29 and Fig.30 As shown, vertical axis chromatic aberration is Fig.31 As shown, the field curvature is Fig.32 As shown, the distortion is Fig.33 shown.

[0171] Fig.29 It shows that in this example, at 120lp / mm in the visible light band, the MTF value of the center field of view is greater than 0.5, and the MTF value of the edge field of view is greater than 0.45, which has the characteristics of higher resolution.

[0172] Fig.30 It shows that in this example, at the fluorescence band and 120lp / mm, the MTF value of the center field of view is about 0.3, and the MTF value of the edge field of view is greater than 0.25, which has the characteristics of higher resolution.

[0173] Fig.31 It shows that the vertical axis chromatic aberration of this example is smaller than that of Example 2, less than 1um.

[0174] Fig.32 It shows that the sagittal field curvature of this example in the visible light and fluorescence bands is small, about 0.04mm.

[0175] Fig.33 It shows that the distortion of this example in the visible light and fluorescence bands is relatively small, at around 6.9%.

[0176] Example 6:

[0177] like Fig.34 As shown, this example is based on Example 3, and mainly adds an eleventh lens L11 on the object side of the first double cemented lens. Both surfaces of this lens are aspherical, which is used to adjust the direction of light in different fields of view, suppress aberrations, and improve imaging quality.

[0178] Some physical and optical parameters of this example are shown in Table 11.

[0179] Table 11

[0180]

[0181] The aspheric surface parameters of this example are shown in Table 12. Except for those listed in the table, the remaining high-order coefficients are zero.

[0182] Table 12

[0183]

[0184] The transfer function curves of this example are as follows Fig.35 and Fig.36 As shown, vertical axis chromatic aberration is Fig.37 As shown, the field curvature is Fig.38 As shown, the distortion is Fig.39 shown.

[0185] Fig.35 It is shown that in the visible light band and at 120lp / mm, the MTF value of the center field of view of this example is greater than 0.5, and the MTF value of the edge field of view is about 0.5, which is improved compared with Example 3 and has the characteristics of higher resolution.

[0186] Fig.36 It shows that in this example, at the fluorescence band and 120lp / mm, the MTF value of the central field of view is greater than 0.3, and the MTF value of the edge field of view is greater than 0.25, which has the characteristics of higher resolution.

[0187] Fig.37 It shows that the vertical axis chromatic aberration of this example is smaller than that of Example 3, less than 1.5um.

[0188] Fig.38 It shows that the sagittal field curvature of this example in the visible light and fluorescence bands is small, about 0.04mm.

[0189] Fig.39 It shows that the distortion of this example in the visible light and fluorescence bands is relatively small, at around 7%.

[0190] Based on the above data, the parameter comparison of each example is shown in Table 13, where parameters such as field curvature and distortion represent the image quality of the optical system of the endoscope group consisting of the objective lens 1 and the rod lens group 2.

[0191] Table 13

[0192]

Claims

1. An achromatic fluorescence laparoscope optical system, consisting of an endoscope assembly and an eyepiece with positive optical power, characterized in that The endoscope assembly is composed of an objective lens with positive optical power and a rod lens assembly with positive optical power. The focal length of the endoscope assembly in the visible light band is f _e The focal length of the endoscope assembly in the fluorescence band is f _flu The focal length of the objective lens in the visible light band is f 1_e , the focal length of the eyepiece in the visible light band is f 3_e , satisfying the relationship: 3≤|f 3_e / f 1_e |≤7,0.99≤f _e / f _flu ≤1.01,0.99≤|f _e / f 1_e |≤1.01, the length of the objective lens is t1, satisfying the relationship: 30mm<t1<40mm, the objective lens is composed of a first objective lens group and a second objective lens group, the first objective lens group is composed of a protective glass, a first lens with a negative focal length, a viewing prism and a second lens with a positive focal length, the object side surface of the first lens is a convex surface, and the image side surface is a concave surface, and in the visible light band, the focal length of the first objective lens group is f 100_e , the focal length f of the second objective lens group 200_e , satisfying the relationship: 0.3≤f 100_e / f 200_e ≤0.9, the second objective lens group comprises a first cemented lens and a second cemented lens, the curvature radius of the cemented surface of the first cemented lens is R 胶合1 The radius of curvature of the bonding surface of the second bonding lens is R 胶合2 , the distance between the two bonding surfaces is D, satisfying the relationship: 0.1mm -1 ≤|D / R 胶合1 / R 胶合2 |≤0.5mm -1 The rod mirror group is composed of three imaging rod mirrors with the same optical structure. The focal length of the imaging rod mirror in the visible light band is f 2_e , satisfying the relationship: 0<|1 / f 2_e |≤0.005mm -1 The imaging rod mirror is composed of two symmetrically arranged rod mirror units, and the rod mirror unit close to the object side is composed of a seventh lens, an eighth lens, a ninth lens and a tenth lens. The optical focal power of the seventh lens is positive, the optical focal power of the eighth lens is negative or has no optical focal power, the optical focal power of the ninth lens is positive, and the optical focal power of the tenth lens is negative.

2. The achromatic fluorescence laparoscope optical system according to claim 1, characterized in that The second objective lens group further comprises a first aspheric lens whose object side surface and image side surface are both aspheric surfaces, and the first aspheric lens is arranged on the object side of the first cemented lens.

3. The achromatic fluorescence laparoscope optical system according to claim 1, characterized in that The first cemented lens is composed of a third lens and a fourth lens, the second cemented lens is composed of a fifth lens and a sixth lens, the dispersion coefficients of the third lens, the fourth lens, the fifth lens and the sixth lens are Vd3, Vd4, Vd5 and Vd6 respectively, satisfying the relationship: 45≤|Vd3-Vd4|≤65, 60≤|Vd5-Vd6|≤80.

4. The achromatic fluorescence laparoscope optical system according to claim 1, characterized in that The first lens is an aspherical lens, and the object side surface of the second lens is a plane surface, and the image side surface is a convex surface.

5. The achromatic fluorescence laparoscope optical system according to claim 1, characterized in that The protective glass material is sapphire.

6. The achromatic fluorescence laparoscope optical system according to claim 1, characterized in that The viewing prism is composed of a first prism, a second prism and a third prism which are arranged in sequence from the object side to the image side and glued to each other. According to the light beam path, the object side surface of the first prism is the light beam incident surface, the upper surface of the first prism glued to the second prism is the transmission surface, the surface of the second prism glued to the third prism is the primary reflection surface, the lower surface of the first prism glued to the second prism is the secondary reflection surface, and the image side surface of the second prism is the light beam exit surface.

7. The achromatic fluorescence laparoscope optical system according to claim 1, characterized in that The dispersion coefficients of the seventh lens, the eighth lens, the ninth lens and the tenth lens are Vd7, Vd8, Vd9 and Vd 10 , satisfying the relationship: 20≤|Vd7-Vd8|≤25, 30≤|Vd8-Vd9|≤35, 40≤|Vd9-Vd 10 |≤45.

8. The achromatic fluorescence laparoscope optical system according to claim 1, characterized in that The eighth lens is a double concave lens with negative optical power, and the object side surface of the tenth lens is a concave surface, and the image side surface is a convex surface.

9. The achromatic fluorescence laparoscope optical system according to claim 1, characterized in that The eighth lens is a double flat rod lens with no optical power, and the object side of the tenth lens is convex and the image side is concave.

10. The achromatic fluorescence laparoscope optical system according to claim 1, characterized in that The magnification of the eyepiece is β 3, the entrance pupil position is ENP, the entrance pupil diameter is END, the object side aperture angle is NA2, the object side principal ray incident angle of the eyepiece is CRA2, the exit pupil position of the rod lens group is EXP, the exit pupil diameter is EXD, the image side aperture angle is NA1, and the object side principal ray incident angle of the rod lens group is CRA1, satisfying the relationship: 0.99≤ENP / EXP≤1.01, 0.99≤END / EXD≤1.01; 0°≤|NA2-NA1|≤0.5°; 0°≤|CRA2-CRA1|≤0.5°, 0.95≤ β 3≤1.15.

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