Zoom infrared optical lens and focusing and assembling method of optical lens

Abstract

The invention provides an infrared zoom optical lens and a focusing and assembling method of the optical lens. The infrared zoom optical lens sequentially comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens from an object side to an image side along an optical axis, the second lens has negative focal power; the third lens has positive focal power; the fourth lens has positive focal power; wherein the first lens can move along the direction of the optical axis to enable the zoom infrared optical lens to focus, the second lens can move along the direction of the optical axis to enable the zoom infrared optical lens to zoom, and the position of the third lens in the direction of the optical axis is fixed. The fourth lens is movable in the optical axis direction to compensate for the second lens or the position of the fourth lens in the optical axis direction is fixed.

Description

Technical Field

[0001] This application relates to the field of optical elements, and more particularly, to a zoom infrared optical lens and a focusing and assembling method for an optical lens. Background Art

[0002] In recent years, infrared lenses have been widely used in various fields such as security, industry, power, vehicle-mounted, and consumer. Traditional fixed-focus infrared optical lenses can no longer meet the market demand, and zoom (also known as variable magnification) infrared optical lenses have emerged as the times require. Zoom infrared optical lenses can meet the working requirements of searching for targets with a large field of view and resolving targets with a small field of view. Therefore, zoom infrared optical lenses have relatively high requirements for parfocality (for example, the ability of a zoom infrared optical lens to clearly image at different magnifications). For example, when a rear-group lens is used for focusing in an infrared zoom infrared optical lens, due to the existence of processing errors, the back focal shift amounts of the infrared zoom infrared optical lens in each focal length segment are different, resulting in poor parfocality of the infrared zoom infrared optical lens.

[0003] However, existing zoom infrared optical lenses have many problems, such as high cost, large volume, and poor parfocality. Therefore, it is particularly important to develop a zoom infrared optical lens with low cost, light miniaturization, and excellent parfocality. Summary of the Invention

[0004] In a first aspect, this application provides a zoom infrared optical lens, which sequentially includes, along the optical axis from the object side to the image side: a first lens with positive optical power; a second lens with negative optical power; a third lens with positive optical power; and a fourth lens with positive optical power; wherein, the first lens is movable along the optical axis direction to focus the zoom infrared optical lens, the second lens is movable along the optical axis direction to vary the magnification of the zoom infrared optical lens, the position of the third lens is fixed in the optical axis direction, and the fourth lens is movable along the optical axis direction to compensate for the second lens or the position of the fourth lens is fixed in the optical axis direction.

[0005] In some embodiments, the effective focal length ft of the zoom infrared optical lens in the long focal state, the refractive index n of the central wavelength of the first lens, the f-number FNO of the zoom infrared optical lens, and the curvature radius R1 of the object side surface of the first lens satisfy: 0.33 < ft×(n - 1) / (FNO×R1) < 3.0.

[0006] In some embodiments, the effective focal length f1 of the first lens and the effective focal length ft of the zoom infrared optical lens in the long focal state satisfy: 1.0 < |f1 / ft| < 1.7.

[0007] In some embodiments, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens, the effective focal length f4 of the fourth lens, and the effective focal length ft of the zoom infrared optical lens in the telephoto state satisfy: 0.22 < |f2 / ft| < 0.5; 0.4 < |f3 / ft| < 2.3; and 0.35 < |f4 / ft| < 0.95.

[0008] In some embodiments, the effective focal length f2 of the second lens and the effective focal length f1 of the first lens satisfy: 0.16 < |f2 / f1| < 0.34.

[0009] In some embodiments, the distance BFL on the optical axis from the image side of the fourth lens to the imaging surface of the zoom infrared optical lens and the effective focal length ft of the zoom infrared optical lens in the telephoto state satisfy: 0.3 < |BFL / ft| < 0.6.

[0010] In some embodiments, the distance TTL on the optical axis from the object side of the first lens to the imaging surface of the zoom infrared optical lens and the effective focal length ft of the zoom infrared optical lens in the telephoto state satisfy: 1.1 < TTL / ft < 2.62.

[0011] In some embodiments, at least one of the object side of the first lens, the image side of the second lens, and the object side of the fourth lens is a spherical surface; at least one of the image side of the first lens, the object side of the second lens, the object side and the image side of the third lens, and the image side of the fourth lens is an aspherical surface.

[0012] In some embodiments, the first lens, the second lens, the third lens, and the fourth lens are all made of germanium glass.

[0013] In some embodiments, the movable distance L1 of the second lens in the optical axis direction and the distance TTL on the optical axis from the object side of the first lens to the imaging surface of the zoom infrared optical lens satisfy: |L1 / TTL| ≤ 0.3.

[0014] In some embodiments, the movable distance L1 of the second lens in the optical axis direction is 10 - 35 mm, and the movable distance L2 of the first lens in the optical axis direction is 7 - 10 mm.

[0015] In some embodiments, the effective focal length ft of the zoom infrared optical lens in the telephoto state and the effective focal length fd of the zoom infrared optical lens in the short - focal state satisfy: 1.5 ≤ ft / fd ≤ 4.

[0016] In some embodiments, the object side of the first lens is convex, the image side is concave; the object side of the second lens is concave, the image side is concave; and the object side of the third lens is convex.

[0017] In some embodiments, during the zooming process of the zoom infrared optical lens from the short - focal state to the long - focal state, the second lens moves from the object side to the image side along the optical axis direction, and the fourth lens moves from the image side to the object side along the optical axis direction.

[0018] In some embodiments, during the zooming process of the zoom infrared optical lens from the short - focal state to the long - focal state, the second lens moves from the object side to the image side along the optical axis direction, and the position of the fourth lens is fixed on the optical axis.

[0019] In some embodiments, the zoom infrared optical barrel further includes a barrel assembly, and the barrel assembly includes: a first barrel for accommodating the first lens; a second barrel sleeved inside the first barrel; and a zoom barrel sleeved inside the second barrel for accommodating the second lens; wherein, the first barrel is movable relative to the second barrel along the optical axis direction, and the zoom barrel is movable relative to the second barrel along the optical axis direction.

[0020] In some embodiments, the first barrel is slidably connected to the second barrel, and the zoom barrel is slidably connected to the second barrel.

[0021] In some embodiments, the barrel assembly further includes: a focusing ring sleeved outside the first barrel, and a first spiral guiding groove is provided on its inner side; wherein, the first barrel is provided with a first linear groove, and a first guiding member is provided on the outside of the second barrel. The first guiding member passes through the first linear groove and slides in the first spiral guiding groove, so that the first barrel is movable relative to the second barrel along the optical axis direction.

[0022] In some embodiments, the focusing ring is implemented as a manual focusing ring.

[0023] In some embodiments, the barrel assembly further includes: a first connecting ring sleeved inside the first barrel, and having a first flange at one end thereof; wherein, the first flange is connected to the end of the first barrel close to the second barrel and contacts the inner side of the focusing ring.

[0024] In some embodiments, sealing rings are provided between the focusing ring and the first barrel, between the focusing ring and the first flange, and between the first connecting ring and the second barrel.

[0025] In some embodiments, the first flange has a connecting hole extending along the optical axis direction. The first flange is connected to the end of the first barrel close to the second barrel through a connecting member, and the connecting hole is filled with sealing glue.

[0026] In some embodiments, the lens barrel assembly further includes: a third lens barrel sleeved between the second lens barrel and the zoom lens barrel; a zoom ring sleeved between the second lens barrel and the third lens barrel, wherein the second lens barrel and the third lens barrel are connected at the end close to the first lens barrel; wherein, the zoom ring is provided with a second spiral guide groove, the third lens barrel is provided with a second linear groove, and a second guide member is provided on the outer side of the zoom lens barrel, and the second guide member slides in the second spiral guide groove through the second linear groove, so that the zoom lens barrel is movable relative to the second lens barrel along the optical axis direction.

[0027] In some embodiments, the zoom ring is implemented as a manual zoom ring.

[0028] In some embodiments, the lens barrel assembly further includes: a fixed lens barrel sleeved inside the third lens barrel for accommodating a third lens; wherein, the fixed lens barrel and the third lens barrel are of an integral structure or are detachably connected to the third lens barrel.

[0029] In some embodiments, the lens barrel assembly further includes: a compensating lens barrel sleeved inside the third lens barrel for accommodating a fourth lens; wherein, the zoom ring is further provided with a third spiral guide groove, the third lens barrel is further provided with a third linear groove, and a third guide member is provided on the outer side of the compensating lens barrel, and the third guide member slides in the third spiral guide groove through the third linear groove, so that the compensating lens barrel is movable relative to the second lens barrel along the optical axis direction; wherein, the second spiral guide groove and the third spiral guide groove are spaced apart in the optical axis direction, and the second linear groove and the third linear groove are spaced apart in the optical axis direction.

[0030] In some embodiments, in the optical axis direction, the zoom lens barrel and the compensating lens barrel are located on both sides of the fixed lens barrel.

[0031] In some embodiments, the lens barrel assembly further includes: a fixed lens barrel sleeved inside the third lens barrel for accommodating a third lens and a fourth lens; wherein, the fixed lens barrel and the third lens barrel are of an integral structure or are detachably connected to the third lens barrel.

[0032] In some embodiments, at least one of the first spiral guide groove, the second spiral guide groove, and the third spiral guide groove is a spiral cam groove.

[0033] In some embodiments, the lens barrel assembly satisfies at least one of the following conditions: the first guide member is detachably connected to the second lens barrel; the second guide member is detachably connected to the zoom lens barrel; and the third guide member is detachably connected to the compensating lens barrel.

[0034] In some embodiments, at least one of the first guide member, the second guide member, and the third guide member is a guide pin.

[0035] In some embodiments, the lens barrel assembly satisfies at least one of the following conditions: the dimension of the first linear groove in the optical axis direction is smaller than the dimensions of the two ends of the first helical wire groove in the optical axis direction; the dimension of the second linear groove in the optical axis direction is smaller than the dimensions of the two ends of the second helical wire groove in the optical axis direction; and the dimension of the third linear groove in the optical axis direction is smaller than the dimensions of the two ends of the third helical wire groove in the optical axis direction.

[0036] In some embodiments, the lens barrel assembly further includes: a zoom adjustment ring sleeved outside the second lens barrel and connected to the zoom ring at the end away from the first lens barrel.

[0037] In some embodiments, the lens barrel assembly further includes: a second connection ring sleeved outside the third lens barrel and connected to the third lens barrel at the end away from the first lens barrel.

[0038] In some embodiments, the zoom adjustment ring has a second flange on the end face away from the first lens barrel, and the outside of the second connection ring contacts the inside of the second flange; wherein, sealing rings are provided between the second lens barrel and the zoom adjustment ring and between the second flange and the second connection ring.

[0039] In some embodiments, sealing glue is provided between the edge of the object side of the first lens and the first lens barrel.

[0040] In a second aspect, the present application provides a focusing method for an optical lens, wherein the optical lens includes a first lens barrel, the first lens barrel houses at least one focusing lens, a second lens barrel is sleeved inside the first lens barrel, a zoom lens barrel is sleeved inside the second lens barrel, the zoom lens barrel houses at least one zoom lens, and on the optical axis direction, the side of the first lens barrel away from the second lens barrel is the object side; wherein, the focusing method includes: driving the zoom lens barrel to move relative to the second lens barrel along the optical axis direction by the second lens barrel to zoom the optical lens, and driving the focusing lens to move relative to the second lens barrel along the optical axis direction by the first lens barrel to focus the optical lens.

[0041] In a third aspect, the present application provides a focusing method for an optical lens, the assembly method includes: arranging at least one focusing lens in the first lens barrel; sleeving a second lens barrel inside the first lens barrel; and sleeving a zoom lens barrel inside the second lens barrel and arranging at least one zoom lens in the zoom lens barrel; wherein, on the optical axis direction, the side of the first lens barrel away from the second lens barrel is the object side, the first lens barrel is movable relative to the second lens barrel along the optical axis direction, and the zoom lens barrel is movable relative to the second lens barrel along the optical axis direction.

[0042] In some embodiments, the step of sleeving the second lens barrel inside the first lens barrel includes: slidably connecting the first lens barrel and the second lens barrel; wherein, the step of sleeving the zoom lens barrel inside the second lens barrel includes: slidably connecting the zoom lens barrel and the second lens barrel.

[0043] In some embodiments, the step of slidably connecting the first lens barrel and the second lens barrel includes: sleeving a focusing ring outside the first lens barrel and providing a first helical guiding groove inside the focusing ring; providing a first linear groove in the first lens barrel; providing a first guiding member outside the second lens barrel; passing the first guiding member through the first linear groove and sliding the first guiding member in the first helical guiding groove.

[0044] In some embodiments, the step of slidably connecting the zoom lens barrel and the second lens barrel includes: sleeving a third lens barrel between the second lens barrel and the zoom ring; sleeving the zoom ring between the second lens barrel and the third lens barrel, wherein the second lens barrel and the third lens barrel are connected at an end close to the first lens barrel; providing a second helical guiding groove in the zoom ring; providing a second linear groove in the third lens barrel; providing a second guiding member outside the zoom lens barrel; and passing the second guiding member through the second linear groove and sliding the second guiding groove in the second helical guiding groove.

[0045] In some embodiments, the assembling method includes: providing at least one fixed lens in the fixed lens barrel; and sleeving the fixed lens barrel inside the third lens barrel.

[0046] In some embodiments, the fixed lens barrel is integrally formed with the third lens barrel or detachably connected to the third lens barrel.

[0047] In some embodiments, the assembling method further includes: providing at least one compensating lens in the compensating lens barrel; sleeving the compensating lens barrel inside the third lens barrel; providing a third helical guiding groove in the zoom ring; providing a third linear groove in the third lens barrel; providing a third guiding member outside the compensating lens barrel; and passing the third guiding member through the third linear groove and sliding in the third helical guiding groove; wherein the second helical guiding groove and the third helical guiding groove are spaced apart in the optical axis direction, and the second linear groove and the third linear groove are spaced apart in the optical axis direction.

[0048] According to the zoom infrared optical lens provided by the present application, by adopting a four-piece optical structure with a smaller number of lenses, it is beneficial to improve the transmittance, reduce the difficulty of processing and assembly, improve the assembly stability, and effectively reduce the tolerance sensitivity and improve the yield. At the same time, the total length and aperture of the zoom infrared optical lens are relatively small, enabling the structure of the zoom infrared optical lens to be compact, which is conducive to meeting the requirements of low cost and light weight and miniaturization. On the other hand, by using the first lens for focusing, it has better parfocality compared to the traditional focusing method of the rear lens group, and can ensure that the imaging picture is clear and uniform during the zooming process. When the optical lens is in the long focal state, the parfocal distance can reach 10 m. In addition, when the fourth lens is movable along the optical axis direction, the zoom infrared optical lens can achieve continuous zooming from the short focal state to the long focal state and has an f-number of 1.0 to 1.1; when the position of the fourth lens on the optical axis is fixed, the zoom infrared optical lens can achieve magnification switching between the short focal state and the long focal state and has an f-number of 0.88 to 1.0, enabling the zoom infrared optical lens to have a large aperture characteristic, effectively increasing the light transmission and improving the performance of the zoom infrared optical lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Other features, objects, and advantages of the present application will become more apparent by reading the detailed description of the non-limiting embodiments with reference to the following drawings:

[0050] Figures 1A to 1C Schematic diagrams showing the structures of the zoom infrared optical lens according to Embodiment 1 of the present application in the short focal state, medium focal state, and long focal state, respectively;

[0051] Figures 2A to 2E Schematic diagrams showing the MTF curve, spot diagram, field curvature curve, distortion curve, and relative illumination curve of the zoom infrared optical lens according to Embodiment 1 of the present application in the short focal state, respectively;

[0052] Figures 3A to 3E Schematic diagrams showing the MTF curve, spot diagram, field curvature curve, distortion curve, and relative illumination curve of the zoom infrared optical lens according to Embodiment 1 of the present application in the medium focal state, respectively;

[0053] Figures 4A to 4E Schematic diagrams showing the MTF curve, spot diagram, field curvature curve, distortion curve, and relative illumination curve of the zoom infrared optical lens according to Embodiment 1 of the present application in the long focal state, respectively;

[0054] Figures 5A to 5C Schematic diagrams showing the structures of the zoom infrared optical lens according to Embodiment 2 of the present application in the short focal state, medium focal state, and long focal state, respectively;

[0055] Figures 6A to 6ERespectively shown are the MTF curve, spot diagram, field curvature curve, distortion curve, and relative illumination curve of the zoom infrared optical lens according to Embodiment 2 of the present application in the short focal length state;

[0056] Figures 7A to 7E Respectively shown are the MTF curve, spot diagram, field curvature curve, distortion curve, and relative illumination curve of the zoom infrared optical lens according to Embodiment 2 of the present application in the medium focal length state;

[0057] Figures 8A to 8E Respectively shown are the MTF curve, spot diagram, field curvature curve, distortion curve, and relative illumination curve of the zoom infrared optical lens according to Embodiment 2 of the present application in the long focal length state;

[0058] Figure 9A and Figure 9B Respectively shown are the structural diagrams of the zoom infrared optical lens according to Embodiment 3 of the present application in the short focal length state and the long focal length state;

[0059] Figures 10A to 10E Respectively shown are the MTF curve, spot diagram, field curvature curve, distortion curve, and relative illumination curve of the zoom infrared optical lens according to Embodiment 3 of the present application in the short focal length state;

[0060] Figures 11A to 11E Respectively shown are the MTF curve, spot diagram, field curvature curve, distortion curve, and relative illumination curve of the zoom infrared optical lens according to Embodiment 3 of the present application in the medium long focal length state;

[0061] Figure 12 Is a structural diagram of a zoom infrared optical lens including a lens barrel assembly according to an exemplary embodiment of the present application;

[0062] Figure 13 Is Figure 12 A structural diagram showing the first lens barrel and the second lens barrel in an unconnected state in the lens barrel assembly;

[0063] Figure 14 Is Figure 12 A perspective view showing the components in the lens barrel assembly in an unconnected state;

[0064] Figure 15 Is Figure 12 A plan view showing the components in the lens barrel assembly in an unconnected state;

[0065] Figure 16 Is Figure 12 A structural diagram showing the focusing ring in the lens barrel assembly;

[0066] Figure 17 Is Figure 12Schematic structural diagram of the zoom ring in the lens barrel assembly shown;

[0067] Figure 18 is Figure 12 Schematic distribution diagram of the sealing ring and sealing glue in the lens barrel assembly shown;

[0068] Figure 19 Schematic structural diagram of a zoom infrared optical lens including a lens barrel assembly according to another exemplary embodiment of the present application;

[0069] Figure 20 is Figure 19 Schematic structural diagram of the first lens barrel and the second lens barrel in the lens barrel assembly shown in an unconnected state; and

[0070] Figure 21 is Figure 19 Schematic structural diagram of the zoom ring in the lens barrel assembly shown. Detailed implementation manners

[0071] To better understand the present application, more detailed descriptions will be made for various aspects of the present application with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of the exemplary embodiments of the present application and do not limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0072] It should be noted that in this specification, the expressions such as first, second, third, etc. are only used to distinguish one feature from another feature and do not represent any limitation on the features. Therefore, without departing from the teachings of the present application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0073] In the drawings, for the sake of clarity, the thickness, dimensions and shapes of the lenses have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are only examples and are not drawn to an exact scale.

[0074] In this document, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object to be photographed is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

[0075] It should also be understood that the terms "comprise", "comprising", "have", "including" and / or "containing", when used in this specification, denote the presence of the stated features, elements and / or components, but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of listed features rather than an individual element in the list. In addition, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application". Also, the term "exemplary" is intended to refer to an example or illustration.

[0076] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms (such as those defined in a common dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0077] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The following embodiments only represent several implementation manners of the present application, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present application. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can be made, and these all belong to the protection scope of the present application. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0078] As used in this application, "zoom" or "magnification change" refers to changing the focal length of an optical lens, that is, changing the field of view angle of the optical lens. For example, the change in focal length (i.e., field of view angle) is achieved by moving a zoom lens group along the optical axis. As used in this application, "focus adjustment", also known as "focusing" or "focus", refers to adjusting the sharpness of the image formed by an optical lens. For example, by changing the distance between the focus lens group and the imaging surface, the purpose of obtaining a clear image is achieved.

[0079] The features, principles and other aspects of the present application will be described in detail below.

[0080] The zoom infrared optical lens according to an exemplary embodiment of the present application may include four lenses having optical power, that is, a first lens, a second lens, a third lens and a fourth lens. These four lenses are arranged in sequence along the optical axis from the object side to the image side. A spatial interval may be provided between any two adjacent lenses among the first lens to the fourth lens.

[0081] In an exemplary embodiment, the first lens may have a positive optical power and may serve as a focusing group; the second lens may have a negative optical power and may serve as a zooming group; the third lens may have a positive optical power and may serve as a fixed group; the fourth lens may have a positive optical power and may serve as a compensating group or a fixed group.

[0082] In an exemplary embodiment, the first lens may be movable along the optical axis to focus the zoom infrared optical lens; the second lens may be movable along the optical axis to zoom the zoom infrared optical lens; the position of the third lens is fixed on the optical axis; the fourth lens may be movable along the optical axis to compensate for the second lens, so that the zoom infrared optical lens continuously zooms from the short focal state to the long focal state, or the position of the fourth lens is fixed on the optical axis, so that the zoom infrared optical lens realizes magnification switching between the short focal state and the long focal state.

[0083] According to the zoom infrared optical lens provided by the present application, by adopting a four-piece optical structure with a small number of lenses, it is beneficial to improve the transmittance, reduce the difficulty of processing and assembly, improve the assembly stability, and can also effectively reduce the tolerance sensitivity and improve the yield. At the same time, the total length and aperture of the zoom infrared optical lens are small, which can make the structure of the zoom infrared optical lens compact and is beneficial to meeting the requirements of low cost and light miniaturization. On the other hand, using the first lens for focusing has better parfocality compared with the traditional focusing method of the rear group lens, and can ensure that the imaging picture is clear and uniform during the zooming process. When the optical lens is in the long focal state, the parfocal distance can reach 10 m. In addition, when the fourth lens is movable along the optical axis, the zoom infrared optical lens can continuously zoom from the short focal state to the long focal state and has an f-number of 1.0 to 1.1; when the position of the fourth lens is fixed on the optical axis, the zoom infrared optical lens can perform magnification switching between the short focal state and the long focal state and has an f-number of 0.88 to 1.0, so that the zoom infrared optical lens has the characteristic of a large aperture, effectively improves the light passing amount, and improves the performance of the zoom infrared optical lens.

[0084] In an exemplary embodiment, during the zooming process of the zoom infrared optical lens from the short focal state to the long focal state, the second lens moves along the optical axis from the object side to the image side, and the fourth lens moves along the optical axis from the image side to the object side.

[0085] In an exemplary embodiment, during the zooming process of the zoom infrared optical lens from the short focal state to the long focal state, the second lens moves along the optical axis from the object side to the image side, and the position of the fourth lens is fixed on the optical axis.

[0086] In an exemplary embodiment, the object side surface of the first lens is convex and the image side surface is concave, that is, the first lens is a meniscus lens convex toward the object side; the object side surface of the second lens is concave and the image side surface is concave, that is, the second lens is a biconcave lens; the object side surface of the third lens is convex.

[0087] In an exemplary embodiment, the zoom infrared optical lens can satisfy 0.33 < ft×(n - 1) / (FNO×R1) < 3, where ft is the effective focal length of the zoom infrared optical lens in the telephoto state, n is the refractive index of the center wavelength of the first lens, FNO is the f-number of the zoom infrared optical lens, and R1 is the radius of curvature of the object side surface of the first lens.

[0088] In an exemplary embodiment, the zoom infrared optical lens can satisfy 1 < |f1 / ft| < 1.7. Where f1 is the effective focal length of the first lens and ft is the effective focal length of the zoom infrared optical lens in the telephoto state.

[0089] In an exemplary embodiment, the zoom infrared optical lens can satisfy 0.22 < |f2 / ft| < 0.5, 0.4 < |f3 / ft| < 2.3, and 0.35 < |f4 / ft| < 0.95. Where f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, and ft is the effective focal length of the zoom infrared optical lens in the telephoto state.

[0090] In an exemplary embodiment, the zoom infrared optical lens can satisfy 0.16 < |f2 / f1| < 0.34. Where f2 is the effective focal length of the second lens and f1 is the effective focal length of the first lens.

[0091] In an exemplary embodiment, the zoom infrared optical lens can satisfy 0.3 < |BFL / ft| < 0.6. Where BFL is the distance on the optical axis from the image side surface of the fourth lens to the imaging surface of the zoom infrared optical lens, and ft is the effective focal length of the zoom infrared optical lens in the telephoto state.

[0092] In an exemplary embodiment, the zoom infrared optical lens can satisfy 1.1 < TTL / ft < 2.62. Where TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface of the zoom infrared optical lens, and ft is the effective focal length of the zoom infrared optical lens in the telephoto state.

[0093] In an exemplary embodiment, the movable distance L1 of the second lens in the optical axis direction and the distance TTL on the optical axis from the object side surface of the first lens to the imaging surface of the zoom infrared optical lens satisfy: |L1 / TTL| ≤ 0.3.

[0094] In an exemplary embodiment, the movable distance L1 of the second lens along the optical axis direction is 10 - 35 mm, and the movable distance L2 of the first lens along the optical axis direction is 7 - 10 mm.

[0095] In an exemplary embodiment, the zoom infrared optical lens can satisfy 1.5 ≤ ft / fd ≤ 4, where ft is the effective focal length of the zoom infrared optical lens in the long focal state, and fd is the effective focal length of the zoom infrared optical lens in the short focal state.

[0096] In an exemplary embodiment, at least one of the object side surface of the first lens, the image side surface of the second lens, and the object side surface of the fourth lens is a spherical surface type; at least one of the image side surface of the first lens, the object side surface of the second lens, the object side surface and the image side surface of the third lens, and the image side surface of the fourth lens is an aspherical surface type. For example, the aspherical surface type is an even-order aspherical surface type. Using both spherical and aspherical surface types can avoid the diffraction effect problem caused by the diffraction surface and is beneficial to reducing the processing difficulty.

[0097] In an exemplary embodiment, the first lens, the second lens, the third lens, and the fourth lens are all made of germanium glass.

[0098] Although the structure and characteristics of the zoom infrared optical lens are described above by way of example, those skilled in the art should understand that without departing from the technical solution claimed in the present application, the number of lenses constituting the zoom infrared optical lens can be changed to obtain the various results and advantages described in this specification. For example, although four lenses are described as an example in the embodiment, the zoom infrared optical lens is not limited to including four lenses. If necessary, the zoom infrared optical lens may further include other numbers of lenses.

[0099] The following further describes a specific embodiment of the optical system of the zoom infrared optical lens applicable to the above embodiment with reference to the drawings.

[0100] Example 1

[0101] The following refers to Figures 1A to 4E Describe the zoom infrared optical lens according to Embodiment 1 of the present application. Figures 1A to 1C The structural schematic diagrams of the zoom infrared optical lens according to Embodiment 1 of the present application in the short focal state, the medium focal state, and the long focal state are respectively shown.

[0102] As Figures 1A to 1C shown, the zoom infrared optical lens sequentially includes, from the object side to the image side along the optical axis direction: a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, and a detector E5.

[0103] The first lens E1 has a positive optical power, with its object side S1 being convex and its image side S2 being concave; the second lens E2 has a negative optical power, with its object side S3 being concave and its image side S4 being concave; the third lens E3 has a positive optical power, with its object side S5 being convex and its image side S6 being concave; the fourth lens E4 has a positive optical power, with its object side S7 being convex and its image side S8 being convex; the protective window of the detector E5 has an object side S9 and an image side S10; the light from the object sequentially passes through the surfaces S1 to S10 and finally forms an image on the imaging surface integrated in the detector E5. For example, a diaphragm (not shown) can be disposed on the object side S5 of the third lens E3 to improve the light transmittance and the uniformity of the imaging picture. For example, the detector E5 can be a non-cooled long-wave infrared detector with a resolution of 640×512 and a pixel size of 12μm×12μm.

[0104] The zoom infrared optical lens starts from Figure 1A the short focal state shown, via Figure 1B the middle focal state shown, and moves towards Figure 1C the long focal state shown. During the zooming process, the second lens E2 moves along the optical axis from the object side towards the image side, the position of the third lens E3 on the optical axis is fixed, and the fourth lens E4 first moves along the optical axis from the image side towards the object side and then from the object side towards the image side. For example, during the above zooming process, the distance between the second lens E2 and the third lens E3 on the optical axis gradually decreases, the distance between the first lens E1 and the second lens E2 on the optical axis gradually increases, and the distance between the third lens E3 and the fourth lens E4 on the optical axis first decreases and then increases.

[0105] Table 1 shows the basic parameters of the zoom infrared optical lens in Embodiment 1, where the units of the radius of curvature, thickness / distance, and aperture are all millimeters (mm).

[0106] Surface number Surface type Radius of curvature Thickness / distance Material Aperture S1 Spherical surface 70.866 5.5 Germanium 56 S2 Aspherical surface 114.321 5.2～29.4 54.2 S3 Aspherical surface -90.853 2 Germanium 27 S4 Spherical surface 91.167 4.1～28.3 27 S5 Aspherical surface 35.923 2.5 Germanium 18 S6 Aspherical surface 40.468 9.8～11.2 16.6 S7 Spherical surface 78.653 3.5 Germanium 27 S8 Aspherical surface -105.062 16.7～18.2 27 S9 Plane Infinity 0.7 Germanium S10 Plane Infinity 1 Imaging surface Plane Infinity

[0107] Table 1

[0108] In Embodiment 1, the distance TTL from the object side S1 of the first lens E1 to the imaging surface of the zoom infrared optical lens on the optical axis is 86 mm. The maximum optical aperture of the zoom infrared optical lens is 58 mm. The movable distance L1 of the second lens E2 along the optical axis is 25 mm, and the movable distance L2 of the first lens E1 along the optical axis is 9 mm. The zoom infrared optical lens is a continuous zoom lens, the range of its effective focal length f is 9 mm to 35 mm, the zoom ratio of the zoom infrared optical lens is 3.8, and the horizontal field of view angle of the zoom infrared optical lens is 11.8° to 73°.

[0109] In this embodiment, the image side surface S2 of the first lens, the object side surface S3 of the second lens, the object side surface S5 and the image side surface S6 of the third lens, and the image side surface S8 of the fourth lens are all aspherical surfaces (for example, even-order aspherical surfaces). The aspherical surface profiles can be defined by, but not limited to, the following aspherical formula:

[0110]

[0111] Where Z(Y) is the sagitta, the distance from the vertex of the aspherical surface along the optical axis at the position with a height of Y; R is the paraxial curvature radius of the aspherical surface; K is the conic coefficient; A, B, C, and D are the correction coefficients of the 4th, 6th, 8th, and 10th orders of the aspherical surface, respectively. Table 2 below gives the conic coefficient K and the high-order term coefficients A, B, C, and D that can be used for the aspherical mirror surfaces S2, S3, S5, S6, and S8 in this embodiment.

[0112] Surface number K A B C D S2 0 -2.8572E-008 -3.25110E-011 5.6932E-014 -1.53370E-017 S3 0 5.96464E-006 -2.43850E-008 1.3564E-010 -3.37820E-013 S5 0 -5.03692E-005 -9.04523E-007 0 0 S6 0 -2.5330E-005 -6.2230E-006 4.53940E-009 -8.78320E-012 S8 0 3.52610E-006 3.67480E-008 -5.24040E-011 1.83360E-014

[0113] Table 2

[0114] Figures 2A to 2E Respectively show the MTF curve, the diagram of the spot diagram, the field curvature curve, the distortion curve, and the relative illumination curve of the zoom infrared optical lens according to Embodiment 1 of the present application in the short focal length state (for example, the short focal length is 9 mm). Figures 3A to 3E Respectively show the MTF curve, the diagram of the spot diagram, the field curvature curve, the distortion curve, and the relative illumination curve of the zoom infrared optical lens according to Embodiment 1 of the present application in the medium focal length state (for example, the medium focal length is 22 mm). Figures 4A to 4E Respectively show the MTF curve, the diagram of the spot diagram, the field curvature curve, the distortion curve, and the relative illumination curve of the zoom infrared optical lens according to Embodiment 1 of the present application in the long focal length state (for example, the long focal length is 35 mm). Among them, the MTF curve represents the curve of the modulation function value of the zoom infrared optical lens changing with the spatial frequency, the spot diagram represents the light intensity distribution of the diffraction image formed by the point light source after passing through the zoom infrared optical lens at different cross-sections in front of and behind the imaging plane, the field curvature curve represents the deviation of the focusing points of light rays with different wavelengths after passing through the zoom infrared optical lens, the distortion curve represents the distortion magnitude values corresponding to different field angles, and the relative illumination curve represents the relative illumination values corresponding to different field angles. According to Figures 2A to 4E It can be seen that the zoom infrared optical lens given in Embodiment 1 can achieve good imaging quality.

[0115] Example 2

[0116] The following refers to Figures 5A to 8EDescribe the zoom infrared optical lens according to Embodiment 2 of the present application. In this embodiment and the following embodiments, for the sake of brevity, some descriptions similar to those in Embodiment 1 will be omitted. Figures 5A to 5C Schematic structural diagrams of the zoom infrared optical lens according to Embodiment 2 of the present application in the short-focus state, the medium-focus state, and the long-focus state are respectively shown.

[0117] As Figures 5A to 5C shown, the zoom infrared optical lens sequentially includes, from the object side to the image side along the optical axis: a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, and a detector E5.

[0118] The first lens E1 has a positive optical power, its object side surface S1 is convex, and its image side surface S2 is concave; the second lens E2 has a negative optical power, its object side surface S3 is concave, and its image side surface S4 is concave; the third lens E3 has a positive optical power, its object side surface S5 is convex, and its image side surface S6 is concave; the fourth lens E4 has a positive optical power, its object side surface S7 is convex, and its image side surface S8 is concave; the protective window of the detector E5 has an object side surface S9 and an image side surface S10; the light from the object sequentially passes through the surfaces S1 to S10 and finally forms an image on the imaging surface integrated in the detector E5. For example, a diaphragm (not shown) can be disposed on the object side surface S5 of the third lens E3 to improve the light transmittance and the uniformity of the imaging picture. For example, the detector E5 can be an uncooled long-wave infrared detector with a resolution of 640×512 and a pixel size of 12μm×12μm.

[0119] The zoom infrared optical lens moves from Figure 5A the short-focus state shown, via Figure 5B the medium-focus state shown, to Figure 5C the long-focus state shown during the zooming process. During this process, the second lens E2 moves along the optical axis from the object side to the image side, the position of the third lens E3 on the optical axis is fixed, and the fourth lens E4 moves along the optical axis from the image side to the object side. For example, during the above zooming process, the distance between the second lens E2 and the third lens E3 on the optical axis gradually decreases, the distance between the first lens E1 and the second lens E2 on the optical axis gradually increases, and the distance between the third lens E3 and the fourth lens E4 on the optical axis gradually decreases.

[0120] In Embodiment 2, the distance BFL from the image side surface S8 of the fourth lens E4 to the imaging surface of the zoom infrared optical lens on the optical axis is 26.5mm. The zoom infrared optical lens is a continuous zoom lens, the range of its effective focal length f is 15mm to 50mm, the zoom ratio of the zoom infrared optical lens is 3.4. The f-number FNO of the zoom infrared optical lens is 1.0 to 1.1. The horizontal field of view angle of the zoom infrared optical lens is 5° to 42°. The working wavelength of the zoom infrared optical lens is 8μm to 12μm.

[0121] Table 3 shows the basic parameters of the zoom infrared optical lens of Embodiment 2, where the units of the radius of curvature, thickness / distance, and aperture are all millimeters (mm). Table 4 shows the conic coefficient K and the high-order term coefficients A, B, C, and D of each aspherical mirror surface that can be used in Embodiment 2, where each aspherical surface type can be defined by the formula (1) given in the above Embodiment 1.

[0122]

[0123]

[0124] Table 3

[0125] Surface number K A B C D S2 0 -4.03530E-008 5.971920E-011 -9.92610E-014 0 S3 0 1.92357E-006 -1.50750E-008 1.18960E-010 -3.21960E-013 S5 0 -1.36820E-006 2.25040E-008 0 0 S6 0 1.0014E-006 3.63830E-008 S8 0 1.8070E-006 -4.68650E-009 2.53870E-011 -3.04270E-014

[0126] Table 4

[0127] Figures 6A to 6E respectively show the MTF curve, spot diagram, field curvature curve, distortion curve, and relative illumination curve of the zoom infrared optical lens according to Embodiment 2 of the present application in the short focal length state (for example, the short focal length is 15 mm). Figures 7A to 7E respectively show the MTF curve, spot diagram, field curvature curve, distortion curve, and relative illumination curve of the zoom infrared optical lens according to Embodiment 2 of the present application in the medium focal length state (for example, the medium focal length is 33 mm). Figures 8A to 8E respectively show the MTF curve, spot diagram, field curvature curve, distortion curve, and relative illumination curve of the zoom infrared optical lens according to Embodiment 2 of the present application in the long focal length state (for example, the long focal length is 50 mm). Among them, the MTF curve represents the curve of the modulation function value of the zoom infrared optical lens changing with the spatial frequency, the spot diagram represents the light intensity distribution of the diffraction image formed by the point light source after passing through the zoom infrared optical lens on different cross-sections before and after the imaging plane, the field curvature curve represents the deviation of the focusing points of light rays of different wavelengths after passing through the zoom infrared optical lens, the distortion curve represents the distortion magnitude values corresponding to different field angles, and the relative illumination curve represents the relative illumination values corresponding to different field angles. According to Figures 6A to 8E It can be known that the MTF curve of the zoom infrared optical lens given in Embodiment 2 is close to the diffraction limit in the short focal length state, medium focal length state, and long focal length state, and the relative illumination value is greater than 95%. Therefore, the zoom infrared optical lens given in Embodiment 2 can achieve good imaging quality.

[0128] Example 3

[0129] The following refers to Figures 9A to 11E Describe the zoom infrared optical lens according to Embodiment 3 of the present application. Figure 9A and Figure 9BSchematic structural diagrams of a zoom infrared optical lens according to Embodiment 3 of the present application are respectively shown in the short - focus state and the long - focus state.

[0130] As Figure 9A and Figure 9B shown, the zoom infrared optical lens sequentially includes, from the object side to the image side along the optical axis: a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, and a detector E5.

[0131] The first lens E1 has a positive optical power, its object side surface S1 is convex, and its image side surface S2 is concave; the second lens E2 has a negative optical power, its object side surface S3 is concave, and its image side surface S4 is concave; the third lens E3 has a positive optical power, its object side surface S5 is convex, and its image side surface S6 is convex; the fourth lens E4 has a positive optical power, its object side surface S7 is flat, and its image side surface S8 is convex; the protective window of the detector E5 has an object side surface S9 and an image side surface S10; light from an object sequentially passes through each surface S1 to S10 and finally forms an image on the imaging surface integrated in the detector. For example, when the zoom infrared optical lens is in the long - focus state, a diaphragm (not shown) can be arranged on the object side surface of the first lens E1 to improve the light transmittance and reduce the external dimensions of the zoom infrared optical lens; when the zoom infrared optical lens is in the short - focus state, the diaphragm (not shown) can be arranged on the object side surface S5 or the image side surface S6 of the third lens E3. For example, the detector E5 can be an uncooled long - wave infrared detector with a resolution of 640×512 and a pixel size of 12μm×12μm.

[0132] During the zooming process of the zoom infrared optical lens from Figure 9A the short - focus state shown to Figure 9B the long - focus state shown, the second lens E2 moves from the object side to the image side along the optical axis, and the positions of the third lens E3 and the fourth lens E4 on the optical axis are fixed. For example, during the above - mentioned zooming process, the distance between the second lens E2 and the third lens E3 on the optical axis gradually decreases, the distance between the first lens E1 and the second lens E2 on the optical axis gradually increases, and the distance between the third lens E3 and the fourth lens E4 on the optical axis remains unchanged.

[0133] In Embodiment 3, the distance BFL from the image side surface S8 of the fourth lens E4 to the imaging surface of the zoom infrared optical lens on the optical axis is 16.59 mm. The zoom infrared optical lens is a dual - field - of - view lens with an effective focal length f of two focal lengths of 19 mm / 38 mm, and the zoom ratio of the zoom infrared optical lens is 2. The f - number FNO of the zoom infrared optical lens is 0.81 - 1.0. The horizontal field of view angle of the zoom infrared optical lens is 9.1° - 31.5°. The working wavelength of the zoom infrared optical lens is 8μm - 12μm.

[0134] Table 5 shows the basic parameters of the zoom infrared optical lens of Embodiment 3. Among them, the units of the radius of curvature, thickness / distance, and aperture are all millimeters (mm). Table 6 shows the conic coefficient K and the high-order term coefficients A, B, C, and D of each aspherical mirror surface that can be used in Embodiment 3. Among them, each aspherical surface type can be defined by the formula (1) given in the above Embodiment 1.

[0135] Surface number Surface type Radius of curvature Thickness / distance Material Aperture S1 Spherical surface 37.356 4 Germanium 40 S2 Aspherical surface 48.523 7.2～16.8 36 S3 Aspherical surface -85.924 1.5 Germanium 28 S4 Spherical surface 76.128 4.3～13.9 28 S5 Spherical surface 142.658 3.4 Germanium 34 S6 Aspherical surface -105.958 12.8 34 S7 Spherical surface Infinity 2.9 Germanium 34 S8 Spherical surface -97.158 15.63 34 S9 Plane Infinity 0.7 Germanium S10 Plane Infinity 0.3 Imaging surface Plane Infinity -

[0136] Table 5

[0137] Surface number K A B C D S2 0 -2.85430E-007 -3.78440E-010 6.228600E-014 -6.64250E-016 S3 0 -3.08350E-007 1.71940E-008 -5.99160E-011 1.882700E-013 S6 0 3.55320E-006 1.37810E-009 -3.48650E-012 6.72280E-015

[0138] Table 6

[0139] Figures 10A to 10E respectively show the MTF curve, the schematic diagram of the spot diagram, the field curvature curve, the distortion curve, and the relative illumination curve of the zoom infrared optical lens according to Embodiment 3 of the present application in the short focal length state (for example, the short focal length is 19 mm). Figures 11A to 11E respectively show the MTF curve, the schematic diagram of the spot diagram, the field curvature curve, the distortion curve, and the relative illumination curve of the zoom infrared optical lens according to Embodiment 3 of the present application in the long focal length state (for example, the long focal length is 38 mm). Among them, the MTF curve represents the curve of the modulation function value of the zoom infrared optical lens changing with the spatial frequency, the spot diagram represents the light intensity distribution of the diffraction image formed by the point light source after passing through the zoom infrared optical lens on different cross-sections before and after the imaging plane, the field curvature curve represents the deviation of the focusing points of light rays of different wavelengths after passing through the zoom infrared optical lens, the distortion curve represents the distortion magnitude values corresponding to different field angles of view, and the relative illumination curve represents the relative illumination values corresponding to different field angles of view. According to Figures 10A to 11E It can be known that the MTF curve of the zoom infrared optical lens given in Embodiment 3 is close to the diffraction limit in the short focal length state and the long focal length state, and the relative illumination value is greater than 95%. Therefore, the zoom infrared optical lens given in Embodiment 3 can achieve good imaging quality.

[0140] In summary, Embodiments 1 to 3 respectively satisfy the relationships shown in Table 7.

[0141] Conditional expression Example 1 Example 2 Example 3 ft×(n - 1) / (FNO×R1) 0.346 0.97 2.79 |f1 / ft| 1.62 1.59 1.13 |f2 / ft| 0.45 0.32 0.35 |f3 / ft| 2.14 0.56 0.54 |f4 / ft| 0.43 0.56 0.85 |f2 / f1| 0.28 0.20 0.31 |BFL / ft| 0.48 0.53 0.44 TTL / ft 2.46 1.72 1.63 |L1 / TTL| 0.29 0.25 0.16 ft / fd 3.89 3.4 2

[0142] Table 7

[0143] Next, a specific embodiment of the lens barrel assembly of the zoom infrared optical lens applicable to the above embodiments will be further described with reference to the accompanying drawings.

[0144] Figure 12 is a schematic structural diagram of a zoom infrared optical lens 100 including a lens barrel assembly 110 according to an exemplary embodiment of the present application. Figure 13 isFigure 12 Schematic structural diagram showing the first lens barrel 111 and the second lens barrel 112 of the lens barrel assembly 110 in an unconnected state. Figure 14 is Figure 12 Perspective view showing the components of the lens barrel assembly 110 in an unconnected state. Figure 15 is Figure 12 Plan view showing the components of the lens barrel assembly 110 in an unconnected state. Figure 16 is Figure 12 Schematic structural diagram showing the focusing ring 114 of the lens barrel assembly 110. Figure 17 is Figure 12 Schematic structural diagram showing the zoom ring 118 of the lens barrel assembly 110. Figure 18 is Figure 12 Schematic distribution diagram showing the sealing rings 101 - 105 and the sealing glue 106 - 107 in the lens barrel assembly 110. Among them, Figures 12 to 18 The shown lens barrel assembly 110 can be applicable to the optical systems of the above-described Embodiment 1 and Embodiment 2.

[0145] As Figures 12 to 18 shown, the lens barrel assembly 110 includes a first lens barrel 111, a second lens barrel 112, and a zoom lens barrel 113. The first lens barrel 111 is used to accommodate the first lens 131. The second lens barrel 112 is sleeved inside the first lens barrel 111. The zoom lens barrel 113 is sleeved inside the second lens barrel 112 and is used for the second lens 132. Among them, in the optical axis direction, the side of the first lens barrel 111 away from the second lens barrel 112 is the object side. The first lens barrel 111 is movable relative to the second lens barrel 112 in the optical axis direction, and the zoom lens barrel 113 is movable relative to the second lens barrel 112 in the optical axis direction.

[0146] In some embodiments, the first lens barrel 111, the second lens barrel 112, and the zoom lens barrel 113 can be coaxially arranged. The first lens barrel 111 and the second lens barrel 112 partially overlap in the optical axis direction. The non-overlapping part of the first lens barrel 111 and the second lens barrel 112 in the optical axis direction can be used to accommodate the first lens 131. For example, the first lens barrel 111 and the second lens barrel 112 are slidably connected so that the first lens barrel 111 is movable relative to the second lens barrel 112 in the optical axis direction. The zoom lens barrel 113 and the second lens barrel 112 are slidably connected so that the zoom lens barrel 113 is movable relative to the second lens barrel 112 in the optical axis direction.

[0147] In the prior art, a fixed setting method for the front lens group is usually adopted. This method requires meeting the position accuracy requirements of the front lens group during the processing, resulting in inconsistent axial positions of the front lens groups in different optical lenses and a large tolerance, thus affecting the parfocality of the lens. On the other hand, in order to meet the position accuracy requirements of the fixed setting method of the front lens group, a method of reserving a margin for the mounting surface of the front lens group is generally adopted, that is, by setting shims with different thicknesses (for example, mylar sheets) to ensure the position accuracy requirements of the front lens group. Therefore, each optical lens needs to be installed and tried many times, the work is complex and cumbersome, and repeated debugging is likely to damage the components.

[0148] According to the lens barrel assembly 110 provided by this embodiment, during use, the zoom lens barrel 113 drives the second lens 132 to move along the optical axis direction relative to the second lens barrel 112 for zooming, and the first lens barrel 111 drives the first lens 131 to move along the optical axis direction relative to the second lens barrel 112 for focusing. By using the first lens barrel 111 close to the object side to drive the first lens 131 for focusing, compared with the traditional focusing method of the rear lens group, the parfocality can be improved, and it is ensured that the imaging picture is clear and uniform during the zooming process. For example, the lens barrel assembly 110 provided by this embodiment can be used, and according to the actual imaging effect of the optical lens adapted to it, the focusing lens 131 is first moved to a suitable position, and then zooming is achieved by moving the zoom lens 132, so as to ensure that the target object is clearly imaged during the entire zooming process. When the optical lens is in the telephoto state, the parfocal distance can reach 10 m.

[0149] In some embodiments, the lens barrel assembly 110 may further include a focusing ring 114. The focusing ring 114 is sleeved outside the first lens barrel 111, and a first spiral guiding groove 1141 is provided on its inner side (refer to Figure 16 ). The first lens barrel 111 is provided with a first linear groove 1111, and a first guiding member 115 is provided outside the second lens barrel 112. The first guiding member 115 passes through the first linear groove 1111 and slides in the first spiral guiding groove 1141 (refer to Figure 16 ), so that the first lens barrel 111 can move relative to the second lens barrel 112 along the optical axis direction. It should be noted that Figure 12 the shown position relationship of the first guiding member 115 with the first lens barrel 111 and the focusing ring 114 is only schematic, Figure 12 and the first spiral guiding groove 1141 is omitted from showing. The setting position of the first spiral guiding groove 1141 on the focusing ring 114 can be referred to Figure 16For example, when the second lens barrel 112 is fixed and the focusing ring 114 is rotated, the first guiding member 115 is restricted by the first spiral guiding groove 1141 and the first linear groove 1111, so that the first lens barrel 111 moves linearly along the optical axis direction. In this embodiment, the first lens barrel 111 only moves linearly, which can avoid the deviation or inclination of the first lens 131 accommodated in the first lens barrel 111 caused by rotational movement, and is beneficial to improving the imaging quality of focusing.

[0150] In some embodiments, the first spiral guiding groove 1141 can be a spiral cam groove. The design freedom of the guiding track curve of the spiral cam groove is more flexible, and can meet various linear motion requirements of the first lens barrel 111 (for example, linear linear motion, non-linear linear motion, folding linear motion, etc.).

[0151] In some embodiments, the first guiding member 115 is detachably connected to the second lens barrel 112. For example, the first guiding member 115 and the second lens barrel 112 can be connected by threads. Specifically, the first guiding member 115 can be a guide pin. In this embodiment, the detachable connection between the first guiding member 115 and the second lens barrel 112 is beneficial to reducing the assembly difficulty of the lens barrel assembly 110.

[0152] In some embodiments, the dimension of the first linear groove 1111 in the optical axis direction is smaller than the dimensions of the two ends of the first spiral guiding groove 1141 in the optical axis direction. In other words, when the first guiding member 115 moves to the end of the first linear groove 1111, there is still a movable space between the first guiding member 115 and the end of the first spiral guiding groove 1141. In this embodiment, the first lens barrel 111 is limited by the first linear groove 1111. Since the first linear groove 1111 has a lower processing difficulty than the first spiral guiding groove 1141, the processing difficulty can be reduced and the limiting accuracy can be improved.

[0153] In some embodiments, as Figure 16 shown, the outer side surface of the focusing ring 114 can be provided with a plurality of protrusions parallel to the optical axis direction. When the focusing ring 114 is manually rotated, the plurality of protrusions are beneficial to increasing the friction force, so as to facilitate manual focusing. In the prior art, the electric focusing method is usually adopted. The present application creatively proposes manual focusing, thereby increasing the flexibility of the focusing operation and saving the manufacturing cost. As another option, the outer side surface of the focusing ring 114 can be provided with a transmission mechanism (not shown). The focusing ring 114 can be connected to a power source (not shown) through the transmission mechanism to achieve electric focusing. Among them, electric focusing is beneficial to improving the focusing accuracy. Optionally, the transmission structure can include a gear rack. The power source can include a motor.

[0154] In some embodiments, the lens barrel assembly 110 may further include a first connecting ring 116. The first connecting ring 116 may be sleeved inside the first lens barrel 111 and have a first flange 1161 at one end thereof. For example, the first flange 1161 may radially extend in a direction away from the optical axis at one end of the first connecting ring body 1162. The first flange 1161 may be connected to the end of the first lens barrel 111 close to the second lens barrel 112, and the outer side surface of the first flange 1161 may contact the inner side surface of the focusing ring 114. Optionally, the first flange 1161 may have a connecting hole extending in the optical axis direction, and the first flange 1161 may be connected to the end of the first lens barrel 111 close to the second lens barrel 112 through a connecting member (e.g., a screw). In this embodiment, the first connecting ring 116 may be used to limit the movement of the focusing ring 114 in the optical axis direction to ensure that the first lens barrel 111 can smoothly move in the optical axis direction when the focusing ring 114 is rotated.

[0155] In some embodiments, as Figure 18 shown, a sealing ring 101 may be provided between the focusing ring 114 and the first lens barrel 111, a sealing ring 102 may be provided between the focusing ring 114 and the first flange 1161, and a sealing ring 103 may be provided between the first connecting ring 116 and the second lens barrel 112. For example, an annular groove for accommodating the sealing ring 101 may be provided in the portion of the first lens barrel 111 in contact with the focusing ring 114, and the sealing ring 101 may be located in the annular groove and contact the focusing ring 114. The sealing rings 102 and 103 may adopt a setting manner similar to that of the sealing ring 101, and details thereof are not described herein again. In this embodiment, the sealing rings 101-103 may ensure that during the movement of the first lens barrel 111 relative to the second lens barrel 112 in the optical axis direction, each guiding component (e.g., the first spiral guiding groove 1141, the first linear groove 1111, and the first guiding member 115) is in a sealed space, thereby effectively preventing dust and impurities from contacting the guiding components and affecting the guiding functions of the guiding components. Optionally, the connecting hole of the first flange 1161 may be filled with a sealing glue 106 to further improve the sealing effect.

[0156] In some embodiments, the lens barrel assembly 110 may further include a third lens barrel 117 and a zoom ring 118. The third lens barrel 117 may be sleeved between the second lens barrel 112 and the zoom lens barrel 113. The zoom ring 118 may be sleeved between the second lens barrel 112 and the third lens barrel 117. In other words, the zoom lens barrel 113, the third lens barrel 117, the zoom ring 118, and the second lens barrel 112 are arranged in sequence from inside to outside. Optionally, in the optical axis direction, the size of the second lens barrel 112 is smaller than the size of the zoom ring 118, and further smaller than the size of the third lens barrel 117. Optionally, in the optical axis direction, the size of the zoom lens barrel 113 is smaller than the size of the third lens barrel 117. Optionally, the radial size of the zoom ring 118 may vary in a stepped manner. As another option, the radial size of the zoom ring 118 is the same everywhere.

[0157] In some embodiments, the second lens barrel 112 and the third lens barrel 117 are connected at the end close to the first lens barrel 111. For example, the second lens barrel 112 and the third lens barrel 117 may be connected by screws. The zoom ring 118 may be provided with a second spiral guide groove 1181 (refer to Figure 17 ). The third lens barrel 117 may be provided with a second linear groove 1171, and a second guide member 119 may be provided on the outer side of the zoom lens barrel 113. The second guide member 119 may pass through the second linear groove 1171 and slide in the second spiral guide groove 1181, so that the zoom lens barrel 113 can move along the optical axis direction relative to the second lens barrel 112 (or the third lens barrel 117 connected to the second lens barrel 112). For example, when the second lens barrel 112 (or the third lens barrel 117 connected to the second lens barrel 112) is fixed, when the zoom ring 118 is rotated, the second guide member 119 is restricted by the second spiral guide groove 1181 and the second linear groove 1171, so that the zoom lens barrel 113 moves in a straight line along the optical axis direction, and drives the second lens 132 to move along the optical axis direction relative to the second lens barrel 112 (or the third lens barrel 117 connected to the second lens barrel 112) to perform zooming.

[0158] In some embodiments, the lens barrel assembly 110 may further include a fixed lens barrel 120. The fixed lens barrel 120 may be sleeved inside the third lens barrel 117 for accommodating the third lens 133. Optionally, the fixed lens barrel 120 and the third lens barrel 117 may be an integral structure. As another option, the fixed lens barrel 120 may be detachably connected to the third lens barrel 117 by means such as fitting, threading, snap-fastening, etc. Among them, when the fixed lens barrel 120 and the third lens barrel 117 are detachably connected, the assembly flexibility of the components inside the third lens barrel 117 (such as the zoom lens barrel 113, the fixed lens barrel 120, and the compensation lens barrel 121) can be improved.

[0159] In some embodiments, the lens barrel assembly 110 further includes a compensation lens barrel 121. The compensation lens barrel 121 can be sleeved inside the third lens barrel 117 for accommodating the fourth lens 134. Optionally, in the optical axis direction, the zoom lens barrel 113 and the compensation lens barrel 121 are located on both sides of the fixed lens barrel 120. The zoom ring 118 is also provided with a third helical guiding groove 1182 (refer to Figure 17 ), and the third lens barrel 117 is also provided with a third linear groove 1172. A third guiding member 122 is provided on the outer side of the compensation lens barrel 121. Among them, as shown in Figure 17 , the second helical guiding groove 1181 and the third helical guiding groove 1182 are spaced apart in the optical axis direction. As shown in Figure 12 , the second linear groove 1171 and the third linear groove 1172 are spaced apart in the optical axis direction. The third guiding member 122 can slide in the third helical guiding groove 1182 through the third linear groove 1172, so that the compensation lens barrel 121 can move along the optical axis relative to the second lens barrel 112 (or the third lens barrel 117 connected to the second lens barrel 112). At the same time, as described above, the second guiding member 119 can also slide in the second helical guiding groove 1181 through the second linear groove 1171, so that the zoom lens barrel 113 and the compensation lens barrel 121 can move synchronously along the optical axis relative to the second lens barrel 112 (or the third lens barrel 117 connected to the second lens barrel 112). In other words, the zoom lens barrel 113 and the compensation lens barrel 121 can achieve linkage. For example, when the second lens barrel 112 (or the third lens barrel 117 connected to the second lens barrel 112) is fixed, when the zoom ring 118 is rotated, the second guiding member 119 is restricted by the second helical guiding groove 1181 and the second linear groove 1171, and at the same time, the third guiding member 122 is restricted by the third helical guiding groove 1182 and the third linear groove 1172, so that the zoom lens barrel 113 and the compensation lens barrel 121 both perform linear motion along the optical axis. Thus, in the process of driving the second lens 132 to move along the optical axis relative to the second lens barrel 112 (or the third lens barrel 117 connected to the second lens barrel 112) for zooming, the compensation lens barrel 121 drives the fourth lens 134 to move along the optical axis relative to the second lens barrel 112 (or the third lens barrel 117 connected to the second lens barrel 112), thereby realizing the continuous zoom function. For example, the zoom lens barrel 113 and the compensation lens barrel 121 can be made to move towards or away from each other along the optical axis by setting the helix directions and / or guiding track curves of the second helical guiding groove 1181 and the third helical guiding groove 1182.

[0160] In some embodiments, similar to the first helical guiding groove 1141, the second helical guiding groove 1181 and / or the third helical guiding groove 1182 may be helical cam grooves. In addition, the second guiding member 119 is detachably connected to the zoom lens barrel 113 and / or the third guiding member 122 is detachably connected to the compensating lens barrel 121 to reduce the assembly difficulty of the lens barrel assembly 110. For example, the second guiding member 119 and the third guiding member 122 are guide pins.

[0161] In some embodiments, the dimension of the second linear groove 1171 in the optical axis direction may be smaller than the dimensions of the two ends of the second helical guiding groove 1181 in the optical axis direction. In other words, when the second guiding member 119 moves to the end of the second linear groove 1171, there is still a movable space between the second guiding member 119 and the end of the second helical guiding groove 1181. Similarly, the dimension of the third linear groove 1172 in the optical axis direction may be smaller than the dimensions of the two ends of the third helical guiding groove 1182 in the optical axis direction. In other words, when the third guiding member 122 moves to the end of the third linear groove 1172, there is still a movable space between the third guiding member 122 and the end of the third helical guiding groove 1182. In this embodiment, by limiting the movement through the second linear groove 1171 and the third linear groove 1172, the processing difficulty can be reduced and the limiting accuracy can be improved.

[0162] In some embodiments, the lens barrel assembly 110 may further include a zoom adjustment ring 123. The zoom adjustment ring 123 may be sleeved outside the second lens barrel 112 and connected to the zoom ring 118 at the end of the zoom ring 118 away from the first lens barrel 111. Optionally, a plurality of protrusions parallel to the optical axis direction may be provided on the outer surface of the zoom adjustment ring 123 to facilitate manual zooming. As another option, a transmission mechanism (not shown) may be provided on the outer surface of the zoom adjustment ring 123. The zoom adjustment ring 123 may be connected to a power source (not shown) through the transmission mechanism to achieve electric zooming, which is beneficial to improving the zooming accuracy. Optionally, the transmission structure may include a gear rack. The power source may include a motor.

[0163] In some embodiments, the lens barrel assembly 110 may further include a second connection ring 124. The second connection ring 124 is sleeved outside the third lens barrel 117 and connected to the third lens barrel 117 at the end of the third lens barrel 117 away from the first lens barrel 111. Exemplarily, the zoom adjustment ring 123 may have a second flange 1231 on the end face away from the first lens barrel 111. For example, the zoom adjustment ring 123 may include a zoom adjustment ring body 1232 and the second flange 1231. The zoom adjustment ring body 1232 is an open annular structure with both ends radially extending along the direction towards the optical axis. The second flange 1231 may be an annular protrusion structure. The outer side of the second connection ring 124 may be in contact with the inner side of the second flange 1231. For example, the second connection ring 124 may also be in contact with the end face of the third lens barrel 117 facing away from the first lens barrel 111.

[0164] In some embodiments, as Figure 18 shown, a sealing ring 104 may be provided between the second lens barrel 112 and the zoom adjustment ring 123. A sealing ring 105 may be provided between the second flange 1231 and the second connecting ring 124. For example, an annular groove for accommodating the sealing ring 104 is provided at a portion of the second lens barrel 112 that contacts the zoom adjustment ring 123. The sealing ring 104 is located in the annular groove and contacts the zoom adjustment ring 123. The sealing ring 105 may be arranged in a similar manner to the sealing ring 104, and details thereof are not described herein again. In this embodiment, the sealing rings 104-105 can ensure that during the rotation of the zoom ring 118, each guiding component (for example, the second helical guiding groove 1181, the third helical guiding groove 1182, the second linear groove 1171, and the third linear groove 1172) is in a sealed space, effectively preventing dust and impurities from entering each guiding component and affecting the guiding function of each guiding component.

[0165] In some embodiments, as Figure 18 shown, a sealing glue 107 is provided between the edge of the object side of the first lens 131 and the first lens barrel 111 to improve the sealing performance of the zoom infrared optical lens.

[0166] In this embodiment, as Figure 12 shown, when the zoom adjustment ring 123 is rotated, the zoom adjustment ring 123 drives the zoom ring 118 to rotate, and further drives the zoom lens barrel 113 and the compensation lens barrel 121 to perform a synchronous linear motion along the optical axis relative to the second lens barrel 112 to achieve a continuous zoom function. At the same time, the third lens 133 remains stationary in the optical axis direction. When the focusing ring 114 is rotated, the focusing ring 114 drives the first lens barrel 111 to perform a linear motion along the optical axis relative to the second lens barrel 112 to achieve a focusing function. Compared with the traditional focusing method of the rear group of lenses, the focusing uniformity can be improved, and the imaging picture can be ensured to be clear and uniform during the continuous zoom process.

[0167] Figure 19 FIG. is a schematic structural diagram of a zoom infrared optical lens 200 including a lens barrel assembly 210 according to another exemplary embodiment of the present application. Figure 20 is Figure 19 a schematic structural diagram showing the first lens barrel 211 and the second lens barrel 212 of the lens barrel assembly 210 in an unconnected state. Figure 21 is Figure 19 a schematic structural diagram of the zoom ring 218 in the lens barrel assembly 210. For the purpose of concise description, the same components as in the previous embodiment are not described again herein. Among them, Figures 19 to 21 the shown lens barrel assembly 210 can be applied to the optical system of Embodiment 3 described above.

[0168] In some embodiments, as Figures 19 to 21 shown, in the lens barrel assembly 210, the third lens barrel 217 is sleeved between the second lens barrel 212 and the zoom lens barrel 213. The zoom ring 218 is sleeved between the second lens barrel 212 and the third lens barrel 217. In other words, the zoom lens barrel 213, the third lens barrel 217, the zoom ring 218, and the second lens barrel 212 are arranged in sequence from inside to outside.

[0169] In some embodiments, the second lens barrel 212 and the third lens barrel 217 are connected at the end close to the first lens barrel 211. For example, the second lens barrel 212 and the third lens barrel 217 can be connected by screws. The zoom ring 218 can be provided with a second spiral guide groove 2181 (refer to Figure 21 ). The third lens barrel 217 can be provided with a second linear groove 2171, and a second guide member 219 can be provided on the outer side of the zoom lens barrel 213. The second guide member 219 can pass through the second linear groove 2171 and slide in the second spiral guide groove 2181, so that the zoom lens barrel 213 can move along the optical axis relative to the second lens barrel 212 (or the third lens barrel 217 connected to the second lens barrel 212). For example, when the second lens barrel 212 (or the third lens barrel 217 connected to the second lens barrel 212) is fixed, when the zoom ring 218 is rotated, the second guide member 219 is restricted by the second spiral guide groove 2181 and the second linear groove 2171, so that the zoom lens barrel 213 makes a linear motion along the optical axis and drives the second lens 232 to move along the optical axis relative to the second lens barrel 212 (or the third lens barrel 217 connected to the second lens barrel 212) to perform magnification switching.

[0170] In some embodiments, the fixed lens barrel 220 is sleeved inside the third lens barrel 217 and is used to accommodate the third lens 233 and the fourth lens 234. Optionally, the fixed lens barrel 220 and the third lens barrel 217 can be an integral structure. As another option, the fixed lens barrel 220 can be detachably connected to the third lens barrel 217 by means such as fitting, threading, snap connection, etc. (not shown). Among them, when the fixed lens barrel 220 and the third lens barrel 217 are detachably connected, the assembly flexibility of the components inside the third lens barrel 217 (for example, the zoom lens barrel 213 and the fixed lens barrel 220) can be improved.

[0171] In this embodiment, when the zoom adjustment ring 223 is rotated, the zoom adjustment ring 223 drives the zoom ring 218 to rotate, and further drives the zoom lens barrel 213 to move linearly relative to the second lens barrel 212 along the optical axis direction to perform magnification switching. At the same time, the third lens 133 and the fourth lens 134 remain unchanged in position along the optical axis direction. When the focus adjustment ring 214 is rotated, the focus adjustment ring 214 drives the first lens barrel 211 to move linearly relative to the second lens barrel 212 along the optical axis direction to perform focusing. Compared with the traditional focusing method of the rear group of lenses, the parfocality can be improved, and the imaging picture can be ensured to be clear and uniform during the magnification switching process.

[0172] The above description is only the preferred embodiment of the present application and the explanation of the applied technical principles. Those skilled in the art should understand that the protection scope involved in the present application is not limited to the technical solution formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the concept of the present application. For example, the technical solution formed by mutually replacing the above features with the technical features (but not limited to) disclosed in the present application that have similar functions.

Claims

1. A zoom infrared optical lens, characterized in that, sequentially including from the object side to the image side along the optical axis: a first lens with positive optical power; a second lens with negative optical power; a third lens with positive optical power; and a fourth lens with positive optical power; wherein, the first lens is movable along the optical axis direction to focus the zoom infrared optical lens, the second lens is movable along the optical axis direction to zoom the zoom infrared optical lens, the position of the third lens is fixed in the optical axis direction, and the fourth lens is movable along the optical axis direction to compensate the second lens or the position of the fourth lens is fixed in the optical axis direction.

2. The zoom infrared optical lens according to claim 1, characterized in that, the effective focal length ft of the zoom infrared optical lens in the telephoto state, the refractive index n of the center wavelength of the first lens, the f-number FNO of the zoom infrared optical lens, and the curvature radius R1 of the object side surface of the first lens satisfy: 0.33 < ft×(n - 1) / (FNO×R1) < 3.

0.

3. The zoom infrared optical lens according to claim 1, characterized in that, the effective focal length f1 of the first lens and the effective focal length ft of the zoom infrared optical lens in the telephoto state satisfy: 1.0 < |f1 / ft| < 1.

7.

4. The zoom infrared optical lens according to claim 1, characterized in that, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens, the effective focal length f4 of the fourth lens, and the effective focal length ft of the zoom infrared optical lens in the telephoto state satisfy: 0.22 < |f2 / ft| < 0.5; 0.4 < |f3 / ft| < 2.3; and 0.35 < |f4 / ft| < 0.

95.

5. The zoom infrared optical lens according to claim 1, characterized in that, the effective focal length f2 of the second lens and the effective focal length f1 of the first lens satisfy: 0.16 < |f2 / f1| < 0.

34.

6. The zoom infrared optical lens according to claim 1, characterized in that, the distance BFL on the optical axis from the image side surface of the fourth lens to the imaging surface of the zoom infrared optical lens and the effective focal length ft of the zoom infrared optical lens in the telephoto state satisfy: 0.3 < |BFL / ft| < 0.

6.

7. The zoom infrared optical lens according to claim 1, characterized in that, the distance TTL on the optical axis from the object side surface of the first lens to the imaging surface of the zoom infrared optical lens and the effective focal length ft of the zoom infrared optical lens in the telephoto state satisfy: 1.1 < TTL / ft < 2.

62.

8. The zoom infrared optical lens according to claim 1, characterized in that, at least one of the object side surface of the first lens, the image side surface of the second lens, and the object side surface of the fourth lens is a spherical surface type; At least one of the image side of the first lens, the object side of the second lens, the object side and the image side of the third lens, and the image side of the fourth lens is an aspherical surface type.

9. A focusing method for an optical lens, Characterized in that, The optical lens includes a first lens barrel, the first lens barrel accommodates at least one focusing lens, a second lens barrel is sleeved inside the first lens barrel, a zoom lens barrel is sleeved inside the second lens barrel, the zoom lens barrel accommodates at least one zoom lens, and on the optical axis direction, the side of the first lens barrel away from the second lens barrel is the object side; Wherein, the focusing method includes: Driving the zoom lens barrel to move relative to the second lens barrel along the optical axis direction through the second lens barrel to zoom the optical lens, and driving the focusing lens to move relative to the second lens barrel along the optical axis direction through the first lens barrel to focus the optical lens.

10. An assembling method for a lens barrel assembly, Characterized in that, The assembling method includes: Arranging at least one focusing lens in the first lens barrel; Sleeving a second lens barrel inside the first lens barrel; and Sleeving a zoom lens barrel inside the second lens barrel and arranging at least one zoom lens in the zoom lens barrel; Wherein, on the optical axis direction, the side of the first lens barrel away from the second lens barrel is the object side, the first lens barrel is movable relative to the second lens barrel along the optical axis direction, and the zoom lens barrel is movable relative to the second lens barrel along the optical axis direction.

Images