Focal length adjusting mechanism and optical imaging system

Abstract

The utility model discloses a focal length adjusting mechanism and an optical imaging system.The focal length adjusting mechanism comprises a fixing assembly, a fastening assembly and an adjusting lead screw, the fixing assembly comprises a first fixing piece and a second fixing piece which are matched with each other, one of the first fixing piece and the second fixing piece is connected with an objective lens, and the other one is connected with a lens base; the first fixing piece and the second fixing piece are detachably connected through a fastening assembly. Wherein the first fixing part is provided with a first mounting hole, the adjusting lead screw is in running fit with the first mounting hole, and the objective lens can apply load to one of the first fixing part and the second fixing part through the adjusting lead screw, so that the adjusting lead screw and the second fixing part are kept in abutting contact. According to the embodiment of the invention, the adjusting lead screw is rotated by one circle, the first fixing piece axially moves along the adjusting lead screw, the moving distance is the single screw pitch of the adjusting lead screw, the focal length adjusting precision is remarkably improved, and the imaging precision of the optical imaging system is further improved.

Description

Technical Field

[0001] The present application belongs to the field of optical imaging technology, and in particular relates to a focal length adjustment mechanism and an optical imaging system. Background Art

[0002] Optical imaging systems are widely used in various high-precision inspection fields, such as semiconductor processing. Among them, the focusing accuracy of the imaging system directly affects the inspection accuracy of the optical system.

[0003] In related technologies, optical microscopes achieve focal length adjustment by rotating the inner and outer lens barrels relative to each other, or by adjusting the distance between the objective lens and the sample using a slide or other device. However, the accuracy of these focusing mechanisms still needs to be further improved. Utility Model Content

[0004] The embodiments of the present application provide a focal length adjustment mechanism and an optical imaging system to achieve fine adjustment of the distance between an objective lens and a lens mount.

[0005] In the first aspect, an embodiment of the present application provides a focus adjustment mechanism for adjusting the focal length of a lens assembly, the lens assembly includes an objective lens and a lens mount, the focus adjustment mechanism includes a fixing assembly, a fastening assembly and an adjusting screw, the fixing assembly includes a first fixing member and a second fixing member that cooperate with each other, one of the first fixing member and the second fixing member is used to connect with the objective lens, and the other is used to connect with the lens mount, the first fixing member is provided with a first mounting hole along the optical axis; the first fixing member and the second fixing member are detachably connected through the fastening assembly; the adjusting screw is rotatably matched with the first mounting hole, and the objective lens can apply a load to the other through the adjusting screw and one of the first fixing member and the second fixing member to keep the adjusting screw in abutment contact with the second fixing member, so that by rotating the adjusting screw, the first fixing member is moved axially along the adjusting screw, driving the first fixing member and the second fixing member to move relative to each other to adjust the relative position of the objective lens and the lens mount.

[0006] In some embodiments, the adjusting screw is provided with a curved surface structure, which is located at one end of the adjusting screw abutting against the second fixing member. When the adjusting screw is rotated, the curved surface structure makes point contact with the second fixing member.

[0007] In some embodiments, the first fixing member is provided with a guide block, and the second fixing member is provided with a guide groove extending along the optical axis, so as to allow the guide block to slide in the guide groove, thereby guiding the movement direction of the first fixing member relative to the second fixing member.

[0008] In some embodiments, the focal length adjustment mechanism further includes a pre-tightening screw, the guide block is provided with a second mounting hole, and the pre-tightening screw passes through the guide slot and is connected to the second mounting hole.

[0009] In some embodiments, the guide block extends along the optical axis or a plurality of guide blocks are provided along the optical axis.

[0010] In some embodiments, the first fixing member includes a first connecting portion extending along the optical axis and a second connecting portion perpendicular to the optical axis. The first mounting hole is opened in the second connecting portion, and the first connecting portion and the second fixing member are detachably connected through a fastening assembly.

[0011] In some embodiments, the second fixing member includes a third connecting portion extending along the optical axis, the third connecting portion is arranged opposite to the first connecting portion and is detachably connected through a fastening assembly, and the adjusting screw is in abutment contact with the end of the third connecting portion.

[0012] In some embodiments, the fastening assembly includes a plurality of fastening screws, the second fixing member is provided with a plurality of third mounting holes, and the first fixing member is provided with a plurality of screw holes. Each fastening screw passes through a third mounting hole and is screwed into one of the screw holes, thereby fastening the second fixing member to the first fixing member. Each third mounting hole is an elongated hole with its length along the optical axis, allowing the fastening screw to move along the length of the third mounting hole.

[0013] In some embodiments, the adjusting screw is threadedly connected to the first fixing member, and the focal length adjustment mechanism further includes a locking nut, which is screwed onto the adjusting screw and abuts against the first fixing member to fix the adjusting screw and the first fixing member relative to each other.

[0014] In a second aspect, an embodiment of the present application provides an optical imaging system, comprising a lens assembly and a focal length adjustment mechanism provided in any of the aforementioned embodiments, wherein the lens assembly comprises an objective lens and a lens mount, wherein the lens mount is fixed relative to the sample to be measured; the objective lens and the lens mount are connected via a focal length adjustment mechanism.

[0015] The focal length adjustment mechanism of the embodiment of the present application is connected to the objective lens and the lens holder respectively through the first fixing member and the second fixing member, and drives the first fixing member and the second fixing member to slide relative to each other along the optical axis direction by the adjusting screw, thereby achieving focal length adjustment between the objective lens and the lens holder. Wherein, the adjusting screw is connected to the first fixing member through the first mounting hole and abuts against the second fixing member. When the adjusting screw is rotated one circle, the first fixing member moves axially along the adjusting screw, and the moving distance is the single pitch of the adjusting screw, which significantly improves the focal length adjustment accuracy, thereby improving the imaging accuracy and use stability of the optical imaging system. The embodiment of the present application reduces the radial space occupied by the focal length adjustment mechanism and the internal shear force, thereby meeting the focusing requirements of large-mass objective lenses and narrow spaces. At the same time, the operation of rotating the adjusting screw is simple and convenient, and it also helps to improve the detection efficiency, reduce the manufacturing cost and maintenance cost of the focal length adjustment mechanism, and has better economic benefits compared with the sliding table focusing assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0017] Figure 1 This is a schematic structural diagram of an optical imaging system according to some embodiments of the present application;

[0018] Figure 2 for Figure 1 A schematic structural diagram of the optical imaging system from another perspective;

[0019] Figure 3 This is a schematic structural diagram of a focus adjustment mechanism in some embodiments of the present application;

[0020] Figure 4 for Figure 3 A schematic structural diagram of the first fixing member in the focal length adjustment mechanism shown;

[0021] Figure 5 for Figure 3 A schematic diagram of the structure of the adjusting screw in the focal length adjustment mechanism shown;

[0022] Figure 6 for Figure 3 Schematic diagram of the structure of the second fixing member in the focal length adjustment mechanism shown.

[0023] The accompanying drawings in the specific implementation manner are as follows:

[0024] 100, objective lens; 200, lens mount; 300, focus adjustment mechanism;

[0025] 311, first fixing member; 3111, first connecting portion; 3112, second connecting portion; 3113, first mounting hole;

[0026] 312, second fixing member; 3121, third connecting portion; 3122, fourth connecting portion;

[0027] 321, fastening screw; 322, third mounting hole; 323, screw hole;

[0028] 331, adjusting screw; 3311, curved surface structure; 332, locking nut;

[0029] 341. Guide block; 3411. Second mounting hole; 342. Guide groove; 343. Pre-tightening member;

[0030] Optical axis direction Z. DETAILED DESCRIPTION

[0031] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0033] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0034] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0035] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0036] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0037] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0038] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0039] Optical imaging systems, due to their non-contact and high-resolution characteristics, are widely used in various high-precision inspection fields, such as semiconductor processing. The focusing accuracy of optical imaging systems has a direct impact on their image quality and, ultimately, inspection accuracy.

[0040] In the related art, there are many ways to focus the optical imaging system: First, the extension and retraction of the objective lens is achieved directly through the relative rotation between the internal and external threaded lens barrels. However, there is a gap between the internal and external threads, which makes it difficult to meet the optical focusing scenarios with high precision requirements; second, a mature one-dimensional linear slide is used to connect the objective lens and the lens mount, but the load and torque load requirements of the slide are strict. An overloaded objective lens will affect the adjustment accuracy and even the function of the slide. At the same time, the slide occupies a large radial space and is not suitable for some compact devices; third, a gear screw mechanism is used to achieve a larger adjustment range, but there are still problems with low stepping accuracy and strict pressure load requirements on the gear teeth. It is not suitable for high-precision, large-mass optical imaging equipment.

[0041] In order to solve the problems of the prior art, the embodiments of the present application provide a focal length adjustment mechanism and an optical imaging system.

[0042] See also Figure 1 and Figure 2An embodiment of the present application provides an optical imaging system, which includes a lens assembly and a focus adjustment structure. The lens assembly includes an objective lens 100 and a lens holder 200. The lens holder 200 is fixed relative to the sample. The objective lens 100 and the lens holder 200 are connected by the focus adjustment structure. The objective lens 100 moves closer to or away from the lens holder 200 to achieve focus adjustment of the lens assembly.

[0043] According to certain embodiments of the present application, the optical imaging system is applied to semiconductor inspection equipment, and the semiconductor inspection equipment obtains an image of a semiconductor sample to be tested through the optical imaging system to achieve size measurement or defect detection.

[0044] The focus adjustment mechanism 300 involved in the above-mentioned optical imaging system will be introduced in detail below.

[0045] See also Figures 3 to 6 The embodiment of the present application provides a focus adjustment mechanism 300, which includes a fixing assembly, a fastening assembly, and an adjusting screw 331. The fixing assembly includes a first fixing member 311 and a second fixing member 312 that cooperate with each other. One of the first fixing member 311 and the second fixing member 312 is connected to the objective lens 100, and the other is connected to the lens holder 200. The first fixing member 311 and the second fixing member 312 are detachably connected via the fastening assembly. The first fixing member 311 defines a first mounting hole 3113, and the adjusting screw 331 rotatably engages with the first mounting hole 3113. The objective lens 100 can apply a load to the other through the adjusting screw 331 and one of the first fixing member 311 and the second fixing member 312, so that the adjusting screw 331 and the second fixing member 312 maintain abutting contact.

[0046] When the adjusting screw 331 is rotated and the adjusting screw 331 and the second fixing member 312 are kept in contact, the first fixing member 311 moves along the axial direction of the adjusting screw 331 so that the first fixing member 311 moves relative to the second fixing member 312 in the optical axis direction, thereby adjusting the distance between the objective lens 100 and the lens holder 200.

[0047] Therefore, the first fixing member 311 and the second fixing member 312 are movably connected through the adjusting screw 331, and the rotation stroke of the adjusting screw 331 is linked to the relative sliding stroke between the first fixing member 311 and the second fixing member 312. By rotating the adjusting screw 331, the objective lens 100 and the lens holder 200 are driven to move closer to or away from each other, thereby improving the focal length adjustment accuracy, thereby improving the imaging accuracy of the optical imaging system.

[0048] According to certain embodiments of the present application, the adjusting screw 331 is threadedly connected to the first fixing member 311 , and the focal length adjustment mechanism 300 further includes a locking nut 332 , which is in abutment contact with the first fixing member 311 .

[0049] Therefore, the locking nut 332 is used to achieve circumferential fixation of the adjusting screw 331 to reduce the unexpected rotation of the adjusting screw 331 that affects the focal length and thus reduces the imaging accuracy.

[0050] It is understandable that in other embodiments, the adjusting screw 331 is connected to the first fixing member 311 via a ball screw pair to achieve conversion between the rotational stroke of the adjusting screw 331 and the linear stroke of the fixing component along the optical axis.

[0051] See also Figures 3 to 6 In the embodiment of the present application, the optical axis extends in a vertical direction (e.g., the Z direction in the figure). At this time, the axis direction of the adjusting screw 331 extends in the vertical direction, the objective lens is fixedly connected to the first fixing member 311, and the bottom end of the adjusting screw 331 in the vertical direction abuts against the top end of the second fixing member 312 in the vertical direction. During the rotation of the adjusting screw 331, the weight of the objective lens and the first fixing member 311 is fully applied to the adjusting screw 331 to maintain the abutment between the adjusting screw 331 and the second fixing member 312. The present application is particularly suitable for adjusting the focal length between the objective lens and the lens mount by moving in the vertical direction, which can reduce the shear force borne by the focus adjustment mechanism 300 during use, and maximize the use of large-mass objective lenses.

[0052] It is understood that in other embodiments, the optical axis extends in other directions. For example, the optical axis is arranged at an acute angle to the vertical direction. Still taking the example of the objective lens fixedly connected to the first fixing member 311, the weight of the objective lens and the first fixing member 311 is partially applied to the adjustment screw 331 to maintain the abutment between the adjustment screw 331 and the second fixing member 312, thereby maintaining the relative fixation between the first fixing member 311 and the second fixing member 312.

[0053] Alternatively, in some other embodiments, the optical axis can be deflected and adjusted during use to meet observation requirements at different angles. At this time, although the direction of the optical axis is variable, the axial direction of the adjustment screw 331 is set to be fixed, for example, extending in the vertical direction or extending at an acute angle to the vertical direction.

[0054] See also Figure 4 According to certain embodiments of the present application, the first fixing member 311 includes a first connecting portion 3111 extending along the optical axis direction, the first connecting portion 3111 is detachably connected to the second fixing member 312 through a fastening assembly, and the first connecting portion 3111 is connected to the objective lens 100.

[0055] Optionally, the first fixing member 311 also includes a second connecting portion 3112 perpendicular to the optical axis direction, the first mounting hole 3113 is opened in the second connecting portion 3112, and the second connecting portion 3112 and the second fixing member 312 are arranged along the optical axis direction to reduce the radial space occupied by the focal length adjustment mechanism 300.

[0056] Therefore, the first connecting portion 3111 and the second fixing member 312 are arranged relative to each other, which allows the first fixing member 311 and the second fixing member 312 to slide in the optical axis direction while reducing the radial space occupied by the fixing component, meeting the use scenario of compact internal space of the device.

[0057] See also Figure 6 According to certain embodiments of the present application, the second fixing member 312 includes a third connecting portion 3121 extending along the optical axis direction. The third connecting portion 3121 is arranged opposite to the first connecting portion 3111 and is detachably connected through a fastening assembly. The end of the third connecting portion 3121 is in abutment with the adjusting screw 331.

[0058] Optionally, the second fixing member 312 further includes a fourth connecting portion 3122 perpendicular to the optical axis, and the fourth connecting portion 3122 is connected to the lens base 200 to enhance the connection stability between the second fixing member 312 and the lens base 200. Exemplarily, the fourth connecting portion 3122 is detachably connected to the lens base 200 via a threaded connection.

[0059] Therefore, on the one hand, the radial space occupied by the fixing component is further reduced to meet the use scenario of compact space; on the other hand, the load between the adjusting screw 331 and the second fixing member 312 does not include shear force, meeting the load-bearing requirements of the large-mass objective lens 100.

[0060] It can be understood that in some embodiments, the first fixing member 311 is connected to the lens holder 200, and the second fixing member 312 is connected to the objective lens 100. The weight of the second fixing member 312 and the objective lens 100 is applied to the second connecting portion 3112 through the adjusting screw 331 and forms a shear force on the second fixing member 312, which is suitable for use scenarios where the objective lens 100 has a smaller mass.

[0061] In some embodiments of the present application, the first fixing member 311 is connected to the objective lens 100, the second fixing member 312 is connected to the lens holder 200, and the weight of the first fixing member 311 and the objective lens 100 is applied to the third connecting portion 3121 through the adjusting screw 331 to maintain the abutting contact between the adjusting screw 331 and the second fixing member 312.

[0062] See also Figure 5According to certain embodiments of the present application, the adjusting screw 331 is provided with a curved surface structure 3311, and the curved surface structure 3311 is located at one end where the adjusting screw 331 abuts the second fixing member 312. When the adjusting screw 331 is rotated, the curved surface structure 3311 makes point contact with the second fixing member 312.

[0063] Optionally, the curved surface structure 3311 is relatively fixedly connected to the adjusting screw 331 .

[0064] Optionally, the curved surface structure 3311 is movably connected to the adjusting screw 331. For example, the curved surface structure 3311 is configured in the form of a ball, and the adjusting screw 331 is provided with a groove capable of partially accommodating the ball, the ball can roll in the groove, and the abutment between the adjusting screw 331 and the second fixing member 312 can keep the ball in the groove.

[0065] Therefore, by providing the curved surface structure 3311, the contact area between the adjusting screw 331 and the second fixing member 312 is reduced, and the friction between the curved surface structure 3311 and the second fixing member 312 when the adjusting screw 331 rotates is reduced, making the focal length adjustment process smoother.

[0066] According to certain embodiments of the present application, the focus adjustment mechanism 300 further includes a guide assembly, which includes a guide block 341 and a guide groove 342 extending along the optical axis. The guide block 341 and the guide groove 342 are respectively provided on the first fixing member 311 and the second fixing member 312 .

[0067] Optionally, the guide groove 342 has a groove bottom. When the guide block 341 moves in the guide groove 342, the guide block 341 slides in contact with the groove bottom of the guide groove 342, so that the first fixing member 311 is separated from the second fixing member 312 to reduce the friction area during the relative movement of the first fixing member 311 and the second fixing member 312.

[0068] Optionally, the guide block 341 is provided on the first fixing member 311 , and the guide groove 342 is provided on the second fixing member 312 ; alternatively, the guide block 341 is provided on the second fixing member 312 , and the guide groove 342 is provided on the first fixing member 311 .

[0069] Alternatively, see Figure 4 The guide block 341 extends along the optical axis, that is, the length of the guide block 341 in the optical axis direction is greater than the length of the guide block 341 in the direction perpendicular to the optical axis, so as to reduce the probability of relative rotation between the guide block 341 and the guide groove 342, and enhance the limiting effect of the guide assembly on the moving direction.

[0070] Further optionally, a plurality of guide blocks 341 are provided, and the plurality of guide blocks 341 are arranged along the optical axis direction.

[0071] Therefore, when the first fixing member 311 and the second fixing member 312 move relative to each other, the guide block 341 slides in the guide groove 342 , and the guide groove 342 can limit the movement range of the guide block 341 to guide the relative sliding direction of the first fixing member 311 and the second fixing member 312 .

[0072] According to certain embodiments of the present application, the guide assembly also includes a preloaded member 343, a guide groove 342 is provided through the second fixing member 312, and the guide block 341 is provided with a second mounting hole 3411 for accommodating the preloaded member 343, and the preloaded member 343 passes through the guide groove 342 and is detachably connected to the second mounting hole 3411.

[0073] Optionally, the pre-tightening member 343 is a pre-tightening pin, and the second mounting hole 3411 is a blind hole capable of accommodating the pre-tightening pin.

[0074] Optionally, the pre-tightening member 343 is a pre-tightening screw, and the second mounting hole 3411 is a threaded hole capable of cooperating with the pre-tightening screw.

[0075] Thus, the first fixing member 311 and the second fixing member 312 can be connected via the pre-tightening member 343 to achieve relative fixation in the through direction of the guide groove 342 , which is helpful for subsequent assembly of the fastening component.

[0076] According to certain embodiments of the present application, the fastening assembly includes a fastening screw 321, and the first fixing member 311 and the second fixing member 312 are respectively provided with a screw hole 323 and a third mounting hole 322, and the fastening screw 321 is simultaneously passed through the screw hole 323 and the third mounting hole 322 to achieve relative fixation of the first fixing member 311 and the second fixing member 312.

[0077] Optionally, multiple fastening screws 321 are provided to improve the locking effect between the first fixing member 311 and the second fixing member 312. It can be understood that multiple screw holes 323 are provided in a one-to-one correspondence with the fastening screws 321, and multiple third mounting holes 322 are provided in a one-to-one correspondence with the fastening screws 321.

[0078] Optionally, the screw hole 323 is provided in the first fixing member 311 , and the third mounting hole 322 is opened in the second fixing member 312 .

[0079] Optionally, the screw hole 323 is provided with an internal thread, and the fastening screw 321 directly passes through the third mounting hole 322 and is screwed into the screw hole 323; or, the screw hole 323 is provided as a through hole, and the fastening screw 321 passes through the screw hole 323 and the third mounting hole 322 at the same time and is tightened with the fastening nut to achieve the fixation of the first fixing member 311 and the second fixing member 312.

[0080] Therefore, after the fastening nut and the fastening screw are tightened, a load is applied in the axial direction to make the first fixing member 311 and the second fixing member 312 abut against each other, so that the static friction force between the first fixing member 311 and the second fixing member 312 is at least greater than the gravity of the objective lens 100, thereby making the first fixing member 311 and the second fixing member 312 relatively stationary in the optical axis direction to achieve a fastened connection.

[0081] It can be understood that in some other embodiments, the fastening component is configured as a snap or other form, and the fastening component can apply a load to the first fixing member 311 or the second fixing member 312 in a direction perpendicular to the contact surface to achieve relative fixation of the first fixing member 311 and the second fixing member 312 in the direction of the optical axis.

[0082] See also Figure 6 According to certain embodiments of the present application, the length direction of the third mounting hole 322 extends along the optical axis, and the fastening screw 321 can slide in the third mounting hole 322 along the optical axis.

[0083] Therefore, on the one hand, the fastening assembly can adapt to the position change after the relative movement of the first fixing member 311 and the second fixing member 312, and still lock the first fixing member 311 and the second fixing member 312; on the other hand, the sliding stroke of the fastening screw 321 in the third mounting hole 322 is consistent with the moving stroke of the first fixing member 311 relative to the second fixing member 312, and the fastening assembly can realize coarse adjustment between the first fixing member 311 and the second fixing member 312.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A focal length adjustment mechanism for adjusting the focal length of a lens assembly, wherein the lens assembly comprises an objective lens and a lens mount, wherein: The focal length adjustment mechanism comprises: A fixing assembly includes a first fixing member and a second fixing member that cooperate with each other, one of the first fixing member and the second fixing member is used to connect to the objective lens, and the other is used to connect to the lens holder, and the first fixing member has a first mounting hole along the optical axis; a fastening assembly, wherein the first fixing member and the second fixing member are detachably connected to each other via the fastening assembly; An adjusting screw is rotatably engaged with the first mounting hole, and the objective lens can apply a load to the other through the adjusting screw and one of the first fixing member and the second fixing member to keep the adjusting screw in abutment contact with the second fixing member, so that by rotating the adjusting screw, the first fixing member is moved axially along the adjusting screw, driving the first fixing member and the second fixing member to move relative to each other to adjust the relative position of the objective lens and the lens mount.

2. The focus adjustment mechanism according to claim 1, wherein: The adjusting screw is provided with a curved surface structure, and the curved surface structure is located at one end of the adjusting screw abutting against the second fixing member. When the adjusting screw is rotated, the curved surface structure makes point contact with the second fixing member.

3. The focus adjustment mechanism according to claim 1, wherein: The first fixing member is provided with a guide block, and the second fixing member is provided with a guide groove extending along the optical axis, so as to allow the guide block to slide in the guide groove, thereby guiding the movement direction of the first fixing member relative to the second fixing member.

4. The focus adjustment mechanism according to claim 3, characterized in that: The focal length adjustment mechanism further includes a pre-tightening screw. The guide block is provided with a second mounting hole. The pre-tightening screw passes through the guide slot and is connected to the second mounting hole.

5. The focus adjustment mechanism according to claim 3, characterized in that: The guide block extends along the optical axis direction or a plurality of guide blocks are provided along the optical axis direction.

6. The focus adjustment mechanism according to claim 1, wherein: The first fixing member includes a first connecting portion extending along the optical axis and a second connecting portion perpendicular to the optical axis. The first mounting hole is opened in the second connecting portion. The first connecting portion and the second fixing member are detachably connected through the fastening assembly.

7. The focus adjustment mechanism according to claim 6, wherein: The second fixing member includes a third connecting portion extending along the optical axis direction. The third connecting portion is arranged opposite to the first connecting portion and is detachably connected through the fastening assembly. The adjusting screw is in abutment contact with an end portion of the third connecting portion.

8. The focus adjustment mechanism according to claim 1, wherein: The fastening assembly includes a plurality of fastening screws, the second fixing member is provided with a plurality of third mounting holes, the first fixing member is provided with a plurality of screw holes, each of the fastening screws passes through one of the third mounting holes and is screwed into one of the screw holes, thereby fastening the second fixing member to the first fixing member; and, Each of the third mounting holes is an elongated hole with a length direction along the optical axis, so as to allow the fastening screw to move along the length direction of the third mounting hole.

9. The focus adjustment mechanism according to claim 1, wherein: The adjusting screw is threadedly connected to the first fixing member. The focal length adjustment mechanism further includes a locking nut. The locking nut is screwed onto the adjusting screw and abuts against the first fixing member to fix the adjusting screw and the first fixing member relative to each other.

10. An optical imaging system, characterized in that: include: The lens assembly includes an objective lens and a lens mount, wherein the lens mount is fixed relative to the sample to be measured; The focus adjustment mechanism according to any one of claims 1 to 9, wherein the objective lens and the lens holder are connected via the focus adjustment mechanism.

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