Optical lens with short moving group stroke and method for determining cam profile curve

Abstract

The invention provides an optical lens with a short moving group stroke, and the optical lens comprises a front fixed group, the front fixed group comprises a first lens, the first surface is a convex spherical surface, and the second surface is a concave aspheric surface; the movable group sequentially comprises a zooming group and a compensation group along the light incidence direction, and the focusing group is arranged on one side of the compensation group; the zoom group comprises a second lens, the first surface is a plane, and the second surface is a concave aspheric surface; the compensation group comprises a third lens and a fourth lens, the first surfaces are convex aspheric surfaces, and the second surfaces are concave spherical surfaces; the focusing group comprises a fifth lens close to the fourth lens side and a sixth lens far away from the fourth lens side of the fifth lens, the first surface of the fifth lens is a concave spherical surface, the second surface of the fifth lens is a convex aspheric surface, the first surface of the sixth lens is a concave spherical surface, and the second surface of the sixth lens is a convex aspheric surface; the driving assembly is at least used for driving the second lens, the third lens and the fourth lens to move along the optical axis along the corresponding motion paths. The optical lens can realize high-quality imaging in a short moving group stroke.

Description

Technical Field

[0001] The present application relates to the technical field of optical systems, and in particular to an optical lens with a short moving group stroke and a method for determining a cam profile curve. Background Art

[0002] With the continuous development of science and technology, optical lenses are increasingly used in various fields, such as photography, monitoring, medical treatment, etc. However, existing optical lenses often have problems such as large size, low imaging quality, and inflexible zoom and focus performance.

[0003] In some specific application scenarios, an optical lens with a short travel is needed to meet the requirements of miniaturization and high performance of the equipment. At the same time, traditional optical lenses may have problems such as large aberration changes and poor imaging stability during zooming and focusing, which affects the imaging quality. Summary of the invention

[0004] In view of the above defects or deficiencies in the prior art, the present application aims to provide a method for determining an optical lens and a cam profile curve of a short moving group stroke;

[0005] In a first aspect, the present application proposes an optical lens with a short moving group stroke, comprising:

[0006] A front fixed group, the front fixed group includes a first lens, the first surface of the first lens is a convex spherical surface, and the second surface is a concave aspherical surface;

[0007] A moving group, wherein the moving group includes a zoom group and a compensation group in sequence along the incident direction of the light;

[0008] A focusing group, the focusing group being arranged on a side of the compensation group away from the zoom group;

[0009] The zoom group includes a second lens, the first surface of the second lens is a plane, and the second surface is a concave aspherical surface;

[0010] The compensation group includes a third lens close to the second lens side and a fourth lens away from the second lens side of the third lens, wherein the first surfaces of the third lens and the fourth lens are both convex aspherical surfaces, and the second surfaces are both concave spherical surfaces;

[0011] The focusing group includes a fifth lens close to the fourth lens side, and a sixth lens away from the fourth lens side of the fifth lens, the first surface of the fifth lens is a concave spherical surface, and the second surface is a convex aspherical surface, the first surface of the sixth lens is a concave spherical surface, and the second surface is a convex aspherical surface; the second lens, the third lens, and the fourth lens have a movement path corresponding to the magnification of the compensation group;

[0012] a first driving assembly, the first driving assembly being at least used to drive the second lens, the third lens, and the fourth lens to move along the optical axis along corresponding motion paths;

[0013] a second driving assembly, the second driving assembly being used to drive the focusing group to move so as to compensate for the phase difference in an environment higher than or lower than normal temperature;

[0014] The first surface is a lens surface where light enters, and the second surface is a lens surface where light exits.

[0015] According to the technical solution provided in the embodiment of the present application, each lens has a lens seat; the first driving assembly includes a motor, the output end of the motor is connected to a cam, the extension direction of the cam is the same as the extension direction of the optical axis, the profile of the cam includes at least a first curve, a second curve and a third curve connected in sequence end to end, the first curve corresponds to the movement path of the second lens, the second curve corresponds to the movement path of the third lens, and the third curve corresponds to the movement path of the fourth lens.

[0016] According to the technical solution provided in the embodiment of the present application, the optical material of the first lens is silicon crystal glass, the radius of the first surface is 50mm-60mm, the radius of the second surface is 100mm-110mm, the light apertures are φ55mm-φ57mm and φ51mm-φ53mm respectively, and the thickness is 7mm-8mm.

[0017] According to the technical solution provided in the embodiment of the present application, the optical material of the second lens is germanium glass, the first surface is a plane, the radius of the second surface is 15mm-25mm, the light-clearing apertures are φ14mm-φ16mm and φ13.5mm-φ15.5mm respectively, and the thickness is 1.4mm-2.5mm.

[0018] According to the technical solution provided in the embodiment of the present application, the optical material of the third lens is silicon crystal glass, the first surface is an aspheric base diffraction surface, the radius of the first surface is 15mm-17mm, the radius of the rear surface is 45mm-55mm, the light aperture is φ15mm-φ17mm and φ14mm-φ16mm respectively, and the thickness is 4mm-5mm.

[0019] According to the technical solution provided in the embodiment of the present application, the optical material of the fourth lens is zinc selenide, the radius of the first surface is 20mm-30mm, the radius of the second surface is 465mm-485mm, the clear apertures are φ11.5mm-φ13.5mm and φ10mm-φ12mm respectively, and the thickness is 3mm-4mm.

[0020] According to the technical solution provided in the embodiment of the present application, the optical material of the fifth lens is zinc sulfide, the radius of the first surface is 5mm-7mm, the radius of the second surface is 7mm-9mm, the clear apertures are φ4mm-φ5mm and φ7mm-φ9mm respectively, and the thickness is 4mm-5mm.

[0021] According to the technical solution provided in the embodiment of the present application, the optical material of the sixth lens is silicon crystal glass, the radius of the first surface is 20mm-30mm, the second surface is aspherical, the radius of the rear surface is 10mm-20mm, the light aperture is φ9mm~φ11mm and φ10mm-φ12mm respectively, and the thickness is 4mm-5mm.

[0022] According to the technical solution provided in the embodiment of the present application, the distance between the first lens and the second lens is 22mm-27.5mm; the distance between the second lens and the third lens is 0.8mm-12mm; the distance between the third lens and the fourth lens is 1mm-12mm; the distance between the fourth lens and the fifth lens is 2mm-8mm; the distance between the fifth lens and the sixth lens is 2.42mm; the distance between the sixth lens and the detector window is 3mm-3.5mm.

[0023] In a second aspect, the present application proposes a method for determining a cam profile curve, which is used to determine the profile curve of a cam in an optical lens with a short moving group stroke as described above; the method comprises the following steps:

[0024] Determining a profile curve equation of the cam, wherein the profile curve equation is used to characterize the relationship between the geometric parameters of the cam and the displacement of the compensation group; the geometric parameters at least include a rotation angle;

[0025] With the goal of correcting the secondary spectrum, reducing the total length of the system and achieving light, small, large zoom ratio continuous zoom, the target optimization index is determined, and the target optimization index at least includes minimizing the secondary spectrum deviation, minimizing the total length of the system, and maximizing the zoom ratio;

[0026] The multi-objective optimization strategy is adopted to optimize the profile curve of the cam to obtain the profile curve of the cam.

[0027] According to the technical solution provided in the embodiment of the present application, the optical lens has an operating band of 3.7 μm-4.8 μm, an F number of 4, a total length of 70 mm, and a focal length with continuous magnification between 45 mm and 215 mm.

[0028] In summary, the present application proposes an optical lens with a short moving group stroke, comprising a front fixed group, the front fixed group comprising a first lens, the first surface of the first lens is a convex spherical surface, and the second surface is a concave aspherical surface; a moving group, the moving group comprises a zoom group and a compensation group in sequence along the incident direction of light, and the compensation group has a focusing group away from the zoom group; the zoom group comprises a second lens, the first surface of the second lens is a plane, and the second surface is a concave aspherical surface; the compensation group comprises a third lens close to the second lens side, and a fourth lens away from the second lens side, the first surfaces of the third lens and the fourth lens are both convex aspherical surfaces, and the second lens is a concave aspherical surface. The surfaces are all concave spherical surfaces; the focusing group includes a fifth lens close to the fourth lens side and a sixth lens away from the fourth lens side of the fifth lens, the first surface of the fifth lens is a concave spherical surface, and the second surface is a convex aspherical surface, the first surface of the sixth lens is a concave spherical surface, and the second surface is a convex aspherical surface; the second lens, the third lens, and the fourth lens have corresponding movement paths; the driving component is at least used to drive the second lens, the third lens, and the fourth lens to move along the optical axis along a movement path corresponding to the magnification of the compensation group; wherein the first surface is the lens surface where the light enters, and the second surface is the lens surface where the light exits.

[0029] Compared with the prior art, the beneficial effect of the present application is that the present application controls the magnification of the compensation group to change its magnification quickly, thereby realizing a fast change in the distance between the compensation group and the zoom group, reducing the stroke of the moving group, making the overall structure of the optical lens more compact, which is conducive to the miniaturization of the device. In some application scenarios with high space requirements, such as portable devices, miniature cameras, etc., the optical lens with a short moving group stroke can better meet the design requirements, reduce the mechanical movement distance of the lens during zooming and focusing, and improve the response speed and stability of the lens. At the same time, the first lens of the front fixed group adopts a convex spherical surface and a concave aspherical surface design, which can effectively correct spherical aberration and coma and improve the imaging quality. The first surface of the second lens of the zoom group is a plane, and the second surface is a concave aspherical surface, which helps to control the propagation path of light and realize the zoom function. The first surfaces of the third lens and the fourth lens of the compensation group are both convex aspherical surfaces, and the second surfaces are both concave spherical surfaces, which can compensate for the aberration during the zooming process and ensure the stability of the imaging. The special surface design of the fifth lens and the sixth lens of the focusing group makes the focusing more precise and improves the clarity of the imaging. Therefore, the optical lens can achieve high-quality imaging within a short motion group stroke. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic structural diagram of an optical lens with a short moving group stroke provided in an embodiment of the present application;

[0031] Figure 2 A schematic diagram of an optical lens with a short moving group stroke provided in an embodiment of the present application during zooming;

[0032] Figure 3 A schematic diagram of a first curve, a second curve and a third curve of a cam provided in an embodiment of the present application;

[0033] Figure 4 A flowchart of the steps of a method for determining a cam profile curve provided in an embodiment of the present application;

[0034] Figure 5 The transfer function curve of the optical system at +20°C when the optical lens provided in the embodiment of the present application is at short focal length (f=45mm);

[0035] Figure 6 The transfer function curve of the optical system at +20°C when the optical lens provided in the embodiment of the present application is at mid-focus (f=125mm);

[0036] Figure 7 The transfer function curve of the optical system at +20°C when the optical lens provided in the embodiment of the present application is at a telephoto position (f=215mm);

[0037] Figure 8 The transfer function curve of the optical system at +60°C when the optical lens provided in the embodiment of the present application is at short focal length (f=45mm);

[0038] Fig. 9 The transfer function curve of the optical system at +60°C when the optical lens provided in the embodiment of the present application is at mid-focus (f=125mm);

[0039] Fig.10 The transfer function curve of the optical system at +60°C when the optical lens provided in the embodiment of the present application is at a telephoto position (f=215mm);

[0040] Fig.11 The transfer function curve of the optical system at -40°C when the optical lens provided in the embodiment of the present application is at short focal length (f=45mm);

[0041] Fig.12 The transfer function curve of the optical system at -40°C when the optical lens provided in the embodiment of the present application is at mid-focus (f=125mm);

[0042] Fig.13 The transfer function curve of the optical system at -40°C when the optical lens provided in the embodiment of the present application is at a telephoto position (f=215mm);

[0043] Fig.14 A relative distortion curve diagram of the optical system when the optical lens provided in the embodiment of the present application is at a short focal length (f=45mm);

[0044] Fig.15A relative distortion curve diagram of the optical system when the optical lens provided in the embodiment of the present application is at mid-focus (f=125mm);

[0045] Fig.16 This is a relative distortion curve diagram of the optical system when the optical lens provided in an embodiment of the present application is at a telephoto focus (f=215mm).

[0046] The text annotations in the figure represent:

[0047] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Detector. DETAILED DESCRIPTION

[0048] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0049] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0050] Example 1

[0051] As mentioned in the background technology, in order to solve the problems in the prior art, this application proposes an optical lens with a short moving group stroke, please refer to Figure 1 As shown, including:

[0052] The front fixed group includes a first lens 1, the first surface of the first lens 1 is a convex spherical surface, and the second surface is a concave aspherical surface (it should be noted that the first lens 1 is a convex spherical surface, and the second surface is a concave aspherical surface). Figure 1 The first surface of the first lens 1 looks like a spherical surface because its radius is large, but in fact the second surface is a concave aspherical surface);

[0053] A moving group, wherein the moving group includes a zoom group and a compensation group in sequence along the incident direction of the light;

[0054] A focusing group, the focusing group being arranged on a side of the compensation group away from the zoom group;

[0055] The zoom group includes a second lens 2, wherein the first surface of the second lens 2 is a plane and the second surface is a concave aspherical surface;

[0056] The compensation group includes a third lens 3 close to the second lens 2 and a fourth lens 4 far from the second lens 2, wherein the first surfaces of the third lens 3 and the fourth lens 4 are both convex aspherical surfaces, and the second surfaces are both concave spherical surfaces;

[0057] The focusing group includes a fifth lens 5 close to the fourth lens 4 and a sixth lens 6 far from the fourth lens 4, the first surface of the fifth lens 5 is a concave spherical surface, the second surface is a convex aspherical surface, the first surface of the sixth lens 6 is a concave spherical surface, and the second surface is a convex aspherical surface; the second lens 2, the third lens 3, and the fourth lens 4 have a movement path corresponding to the magnification of the compensation group;

[0058] A first driving component, the first driving component is at least used to drive the second lens 2, the third lens 3, and the fourth lens 4 to move along the optical axis along corresponding motion paths;

[0059] The second driving component is used to drive the focusing group to move so as to compensate for the phase difference in an environment higher than or lower than normal temperature; specifically, the phase difference is compensated to improve the imaging quality and make the image clearer. In a normal temperature environment, the second driving component does not move, that is, the focusing group does not move.

[0060] The first surface is a lens surface where light enters, and the second surface is a lens surface where light exits.

[0061] Specifically, in the direction of the optical axis in which the medium-wave infrared radiation of the scene in the target area passes, the following are arranged in sequence from the object side to the image side: a front fixed group with positive optical power, a plano-concave lens with negative optical power as a magnification group, two sequentially distributed meniscus lenses with positive optical power as a compensation group, and a rear fixed group composed of two sequentially distributed meniscus lenses with positive optical power, to project the medium-wave infrared radiation in the field of view onto the focal plane to achieve imaging of the target.

[0062] The present invention controls the magnification of the compensation group to change the magnification quickly, thereby realizing a fast change in the distance between the compensation group and the variable magnification group, thereby reducing the stroke of the moving group. However, the short stroke of the moving group will increase the cam curve rise angle. Under the premise of ensuring the machinability of the cam, the stroke of the variable magnification group and the compensation group is shortened. During the design process, the aperture of the lens of the variable magnification group and the compensation group is controlled, thereby reducing the size of the zoom cam, the lens seat of the variable magnification group, and the lens seat of the compensation group, and realizing a lightweight and miniaturized design of a continuous zoom optical lens. Finally, the optical lens of the present invention can realize a continuous zoom of 45mm-215mm within a total length of 70mm.

[0063] In a preferred embodiment, each lens has a lens mount; the first driving assembly includes a motor, an output end of the motor is connected to a cam, an extension direction of the cam is the same as an extension direction of the optical axis, a profile of the cam includes at least a first curve, a second curve and a third curve connected in sequence end to end, the first curve corresponds to the movement path of the second lens 2, the second curve corresponds to the movement path of the third lens 3, and the third curve corresponds to the movement path of the fourth lens 4.

[0064] In a preferred embodiment, the optical material of the first lens 1 is silicon crystal glass, the radius of the first surface is 50mm-60mm, the radius of the second surface is 100mm-110mm, the light apertures are φ55mm-φ57mm and φ51mm-φ53mm respectively, and the thickness is 7mm-8mm.

[0065] In a preferred embodiment, the optical material of the second lens 2 is germanium glass, the first surface is a plane, the radius of the second surface is 15mm-25mm, the apertures are φ14mm-φ16mm and φ13.5mm-φ15.5mm respectively, and the thickness is 1.4mm-2.5mm.

[0066] In a preferred embodiment, the optical material of the third lens 3 is silicon crystal glass, the first surface is an aspheric base diffraction surface, the radius of the first surface is 15mm-17mm, the radius of the rear surface is 45mm-55mm, the light aperture is φ15mm-φ17mm and φ14mm-φ16mm respectively, and the thickness is 4mm-5mm.

[0067] In a preferred embodiment, the optical material of the fourth lens 4 is zinc selenide, the radius of the first surface is 20mm-30mm, the radius of the second surface is 465mm-485mm, the light apertures are φ11.5mm-φ13.5mm and φ10mm-φ12mm respectively, and the thickness is 3mm-4mm.

[0068] In a preferred embodiment, the optical material of the fifth lens 5 is zinc sulfide, the radius of the first surface is 5mm-7mm, the radius of the second surface is 7mm-9mm, the light apertures are φ4mm-φ5mm and φ7mm-φ9mm respectively, and the thickness is 4mm-5mm.

[0069] In a preferred embodiment, the optical material of the sixth lens 6 is silicon crystal glass, the radius of the first surface is 20mm-30mm, the second surface is aspherical, the radius of the rear surface is 10mm-20mm, the light aperture is φ9mm~φ11mm and φ10mm-φ12mm respectively, and the thickness is 4mm-5mm.

[0070] In a preferred embodiment, the distance between the first lens 1 and the second lens 2 is 22mm-27.5mm; the distance between the second lens 2 and the third lens 3 is 0.8mm-12mm; the distance between the third lens 3 and the fourth lens 4 is 1mm-12mm; the distance between the fourth lens 4 and the fifth lens 5 is 2mm-8mm; the distance between the fifth lens 5 and the sixth lens 6 is 2.42mm; the distance between the sixth lens 6 and the detector 7 window is 3mm-3.5mm.

[0071] In a preferred embodiment, the optical lens has an operating wavelength range of 3.7 μm-4.8 μm, an F number of 4, and a total length of 70 mm. Please refer to Figure 2 As shown, the focal length can be continuously changed from 45mm to 215mm.

[0072] Furthermore, the maximum distortion of the entire field of view of the optical lens during the entire zooming process is less than 2.9%, the optical lens weighs 39.3 grams, the image plane position remains stationary during the entire zooming process, and clear imaging at a fixed F number can be achieved.

[0073] The fitting of the cam curve is based on the conditions of ensuring the stability of the image plane and excellent image quality. In this design, the zoom group and the compensation group move in a curve with a certain step length driven by the cam. By optimizing the zoom group cam curve, the rise angles of the three-action group curves are all less than 40°, and the image change rate is smooth during the entire zoom process, and the visual effect is more comfortable.

[0074] The fitting of the cam curve is based on the conditions of ensuring the stability of the image plane and good image quality. Five focal length positions are selected in the design to optimize the system. The cam curve of each moving group is optimized through the macro program of CODE V. Figure 3 The cam curve of each moving group is smooth without inflection points. The ordinate in the figure represents the interval value of each moving group moving in the direction of the optical axis at different focal lengths, and the abscissa represents the number of points. From bottom to top, the curves are the second lens 2 of the zoom group, the third lens 3 of the compensation group, and the fourth lens 4 of the compensation group. It can be seen from the figure that each cam curve is smooth, and the cam curve equation can be obtained by fitting the obtained data, and the cam is machined according to the cam curve equation.

[0075] Figure 5 , Figure 6 and Figure 7This is the optical transfer function curve of the best embodiment produced by Code V optical design software. The design input wavelength is 3.7μm, 4.25μm and 4.8μm, the half image height is 0, 1.23, 3.08, 4.31 and 6.15, and the F number is 4. Since the image quality of the positive image plane and the negative image plane is the same, only the positive image height is used for input. The horizontal axis in the figure represents the spatial frequency, and the vertical axis represents the optical transfer function value. Further, Figure 8-Figure 16 It can also be seen that the optical lens proposed in this application meets the performance requirements.

[0076] Table 1 shows the imaging quality of the low-cost, lightweight, large zoom ratio, and continuous zoom optical lens at different focal lengths. It can be seen that the imaging quality of the optical system is excellent from the center field of view to the edge field of view within the focal length range of 45mm-215mm. In summary, the invention achieves the design requirements of a low-cost, lightweight, large zoom ratio, and continuous zoom optical lens.

[0077] Table 1 Imaging quality of low-cost, lightweight, large-zoom continuous zoom optical lens

[0078] focal length 45mm 125mm 215mm Relative field of view theory theory theory 0 0.323 0.332 0.271 0.3 0.295 0.299 0.241 0.5 0.251 0.251 0.186 0.7 0.198 0.201 0.142 1 0.136 0.145 0.117

[0079] Example 2

[0080] Based on Example 1, this example proposes a method for determining a cam profile curve, which is used to determine the profile curve of the cam in the optical lens with a short moving group stroke as described above; please refer to Figure 4 As shown, the following steps are included:

[0081] S1. Determine a profile curve equation of a cam, wherein the profile curve equation is used to characterize the relationship between geometric parameters of the cam and the displacement of the compensation group; the geometric parameters at least include a rotation angle;

[0082] The relationship between the displacement of the compensation group and the magnification is further analyzed, and the function expression of the magnification with respect to the geometric parameters of the cam is established. Combined with the optical design software, the performance of the optical system under different cam geometric parameters is simulated, including the correction of the secondary spectrum, the imaging quality, the total length of the system, etc. The influence of the magnification on the correction of the secondary spectrum and the trade-off relationship between the magnification and the total length of the system are determined.

[0083] S2, with the goal of correcting the secondary spectrum, reducing the total length of the system and achieving light, small, large zoom ratio continuous zoom, determining target optimization indicators, wherein the target optimization indicators at least include minimizing the secondary spectrum deviation, minimizing the total length of the system, and maximizing the zoom ratio;

[0084] Specifically, an optimization algorithm such as a genetic algorithm, a simulated annealing algorithm, etc. is used, and during the optimization process, the geometric parameters of the cam are continuously adjusted to meet the requirements of the optimization target.

[0085] S3. A multi-objective optimization strategy is used to optimize the profile curve of the cam to obtain the profile curve of the cam.

[0086] A multi-objective optimization strategy is adopted. Optionally, a weighted summation, Pareto optimization and other methods can be used to balance and optimize multiple objectives to obtain a cam profile curve with a good comprehensive effect of minimizing the secondary spectral deviation, minimizing the total length of the system, and maximizing the zoom ratio.

[0087] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and its core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. An optical lens with a short moving group stroke, characterized in that: include: A front fixed group, the front fixed group comprising a first lens (1), the first surface of the first lens (1) being a convex spherical surface, and the second surface being a concave aspherical surface; A moving group, wherein the moving group includes a zoom group and a compensation group in sequence along the incident direction of the light; A focusing group, the focusing group being arranged on a side of the compensation group away from the zoom group; The zoom group comprises a second lens (2), the first surface of the second lens (2) is a plane, and the second surface is a concave aspherical surface; The compensation group comprises a third lens (3) close to the second lens (2), and a fourth lens (4) on the third lens (3) away from the second lens (2), wherein the first surfaces of the third lens (3) and the fourth lens (4) are both convex aspheric surfaces, and the second surfaces are both concave spherical surfaces; The focusing group comprises a fifth lens (5) close to the fourth lens (4) and a sixth lens (6) on the side of the fifth lens (5) away from the fourth lens (4); the first surface of the fifth lens (5) is a concave spherical surface and the second surface is a convex aspherical surface; the first surface of the sixth lens (6) is a concave spherical surface and the second surface is a convex aspherical surface; the second lens (2), the third lens (3) and the fourth lens (4) have a movement path corresponding to the magnification of the compensation group; A first driving assembly, the first driving assembly being used at least to drive the second lens (2), the third lens (3), and the fourth lens (4) to move along the optical axis along corresponding motion paths; a second driving assembly, the second driving assembly being used to drive the focusing group to move so as to compensate for the phase difference in an environment higher than or lower than normal temperature; The first surface is the lens surface where light enters, and the second surface is the lens surface where light exits.

2. The optical lens with short moving group stroke according to claim 1, characterized in that: Each lens has a lens seat; the first driving assembly comprises a motor, the output end of the motor is connected to a cam, the extension direction of the cam is the same as the extension direction of the optical axis, the profile curve of the cam comprises at least a first curve, a second curve and a third curve connected in sequence end to end, the first curve corresponds to the movement path of the second lens (2), the second curve corresponds to the movement path of the third lens (3), and the third curve corresponds to the movement path of the fourth lens (4).

3. The optical lens with short moving group stroke according to claim 1, characterized in that: The optical material of the first lens (1) is silicon crystal glass, the radius of the first surface is 50mm-60mm, the radius of the second surface is 100mm-110mm, the light apertures are φ55mm-φ57mm and φ51mm-φ53mm respectively, and the thickness is 7mm-8mm.

4. The optical lens with short moving group stroke according to claim 1, characterized in that: The optical material of the second lens (2) is germanium glass, the first surface is a plane, the radius of the second surface is 15 mm-25 mm, the light aperture is φ14 mm-φ16 mm and φ13.5 mm-φ15.5 mm respectively, and the thickness is 1.4 mm-2.5 mm.

5. The optical lens with short moving group stroke according to claim 1, characterized in that: The optical material of the third lens (3) is silicon crystal glass, the first surface is an aspherical base diffraction surface, the radius of the first surface is 15mm-17mm, the radius of the rear surface is 45mm-55mm, the apertures are φ15mm-φ17mm and φ14mm-φ16mm respectively, and the thickness is 4mm-5mm.

6. The optical lens with short moving group stroke according to claim 1, characterized in that: The optical material of the fourth lens (4) is zinc selenide, the radius of the first surface is 20mm-30mm, the radius of the second surface is 465mm-485mm, the apertures are φ11.5mm-φ13.5mm and φ10mm-φ12mm respectively, and the thickness is 3mm-4mm.

7. The optical lens with short moving group stroke according to claim 1, characterized in that: The optical material of the fifth lens (5) is zinc sulfide, the radius of the first surface is 5mm-7mm, the radius of the second surface is 7mm-9mm, the light apertures are φ4mm-φ5mm and φ7mm-φ9mm respectively, and the thickness is 4mm-5mm.

8. The optical lens with short moving group stroke according to claim 1, characterized in that: The optical material of the sixth lens (6) is silicon crystal glass, the radius of the first surface is 20mm-30mm, the second surface is aspherical, the radius of the rear surface is 10mm-20mm, the light aperture is φ9mm-φ11mm and φ10mm-φ12mm respectively, and the thickness is 4mm-5mm.

9. The optical lens with short moving group stroke according to claim 1, characterized in that: The distance between the first lens (1) and the second lens (2) is 22 mm-27.5 mm; the distance between the second lens (2) and the third lens (3) is 0.8 mm-12 mm; the distance between the third lens (3) and the fourth lens (4) is 1 mm-12 mm; the distance between the fourth lens (4) and the fifth lens (5) is 2 mm-8 mm; the distance between the fifth lens (5) and the sixth lens (6) is 2.42 mm; and the distance between the sixth lens (6) and the detector (7) window is 3 mm-3.5 mm.

10. A method for determining a cam profile curve, used to determine the profile curve of a cam in an optical lens with a short motion group stroke as claimed in any one of claims 2 to 9; characterized in that: The following steps are involved: Determining a profile curve equation of the cam, wherein the profile curve equation is used to characterize the relationship between the geometric parameters of the cam and the displacement of the compensation group; the geometric parameters at least include a rotation angle; With the goal of correcting the secondary spectrum, reducing the total length of the system and achieving light, small, large zoom ratio continuous zoom, the target optimization index is determined, and the target optimization index at least includes minimizing the secondary spectrum deviation, minimizing the total length of the system, and maximizing the zoom ratio; The multi-objective optimization strategy is adopted to optimize the profile curve of the cam to obtain the profile curve of the cam.

Images