Optical system, optical lens and electronic device

Abstract

This application belongs to the field of optics, specifically disclosing an optical system, an optical lens, and an electronic device. The optical system comprises, along the optical axis from the object plane to the image plane, a front fixed lens group, a front movable lens group, and a rear fixed lens group. The front fixed lens group includes: a first lens with negative optical power, both the object-side and image-side surfaces being concave; a second lens with negative optical power, the object-side surface being concave and the image-side surface being convex. The front movable lens group includes: a third lens with positive optical power, both the object-side and image-side surfaces being convex. The rear fixed lens group includes: a fourth lens with positive optical power, both the object-side and image-side surfaces being convex; and a fifth lens with positive optical power, the object-side surface being convex and the image-side surface being concave. This application enables an internal focusing optical system where the main body of the optical lens remains stationary, and only one lens group within it is adjusted to achieve preset working distance correction and aberration suppression.

Description

Technical Field

[0001] This application belongs to the field of optics, and more specifically, relates to an optical system, an optical lens, and an electronic device. Background Technology

[0002] In high-end applications such as laser multidimensional lithography and high-precision imaging and inspection with specific small field of view, stringent requirements are placed on the focusing accuracy, working distance adaptability, and aberration control capabilities of optical systems. Current optical lens technology still faces numerous limitations in lens design for specific wavelengths and close object distances. On the one hand, even lenses optimized for the visible and near-infrared bands are susceptible to chromatic aberration when focusing on the dominant wavelength of a specific wavelength within that band. This is especially true during glass correction, where different wavelength components of light struggle to achieve effective confocalization, leading to decreased focusing quality and blurred images, directly impacting the line accuracy of laser lithography and the accuracy of high-precision inspection. On the other hand, existing close-focusing lenses often employ multi-lens linkage focusing or long-stroke zoom focusing structures. These not only struggle to maintain a relatively stable focal length within a certain working distance range, causing image plane shifts and image quality fluctuations, but also complicate the lens structure, increase its size, and raise manufacturing and assembly difficulties.

[0003] Furthermore, while existing internal focusing lenses can simplify the structure and reduce overall lens movement to some extent, they still cannot be optimally adapted to meet the requirements of glass correction within a certain thickness range at close working distances and the constraints of high NA characteristics. More importantly, traditional objectives with correction rings require simultaneous movement of the objective body and the correction lens group during glass thickness correction. This is not only complex to operate and difficult to calibrate, but also prone to positioning deviations due to dual movement, resulting in decreased imaging accuracy and insufficient focusing stability. Existing internal focusing technology also struggles to achieve the core requirement of "fixing the lens body and adjusting only one lens group" through single-lens focusing, failing to simultaneously meet the dual goals of glass correction within a certain thickness range, high NA focusing, and precise focusing. If the focusing travel is too large during glass correction, it will further exacerbate aberrations and distortions; if the travel is too small, clear focusing cannot be achieved across the entire working distance range, making it difficult to meet the core requirements of miniaturization, high precision, and high stability of optical systems in scenarios such as laser lithography and high-precision inspection. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this application is to provide an optical system, an optical lens and an electronic device, which aims to solve the drawbacks of the traditional objective lens with correction ring "dual movement of objective lens and correction lens group", as well as the problems of insufficient focusing accuracy, obvious aberrations and complex structure in the prior art.

[0005] To achieve the above objectives, this application provides an optical system in which, along the optical axis, from the object plane to the image plane, a front fixed lens group, a front movable lens group movable along the optical axis, and a rear fixed lens group are arranged sequentially. The aforementioned front fixed lens group includes: The first lens with negative optical power has concave surfaces on both the object side and the image side near the optical axis; The second lens with negative optical power has an object-side surface that is concave near the optical axis and an image-side surface that is convex near the optical axis. The aforementioned forward-moving lens group includes: The third lens has positive optical power, and both the object-side and image-side surfaces are convex near the optical axis. The aforementioned rear fixed lens group includes: The fourth lens has positive optical power, and both the object-side and image-side surfaces are convex near the optical axis. The fifth lens has positive optical power, with the object side being convex near the optical axis and the image side being concave near the optical axis.

[0006] It should be noted that the forward-moving lens group can move along the optical axis to achieve focusing of the optical system.

[0007] As a further preferred embodiment, a beam combiner prism is also included between the front moving lens group and the rear fixed lens group along the optical axis; The aforementioned beam combiner prism is used to combine a first-band beam incident along the optical axis from the object plane and a second-band beam incident perpendicular to the optical axis, and to emit the combined beam along the optical axis out onto the image plane.

[0008] It is understood that the aforementioned first-band beam can be used to act on a target object on the image side of the optical system. The target object can be an object to be laser-lithographically etched, an object to be imaged with high precision, or an object to be inspected. The aforementioned second-band beam can be used to assist in illuminating the target object. Here, auxiliary illumination is not an essential means, that is, the beam combining prism is not the core of this invention, and will not be specifically explained below.

[0009] As a further preferred embodiment, when the aforementioned beam-combining prism is not provided in the optical system, during the focusing process, the air gap D1 between the front fixed lens group and the front moving lens group varies within the range of 1.149mm≤D1≤5.703mm, and the air gap D2 between the front moving lens group and the rear fixed lens group varies within the range of 18.293mm≤D2≤22.847mm.

[0010] As a further preferred embodiment, when the above-mentioned beam-combining prism is provided in the optical system, during the focusing process, the air gap D1 between the front fixed lens group and the front moving lens group varies within the range of 1.203mm≤D1≤5.993mm, and the air gap D3 between the front moving lens group and the beam-combining prism varies within the range of 1.503mm≤D3≤6.293mm.

[0011] As a further preferred embodiment, when the above-mentioned beam-combining prism is provided in the optical system, the air gap between the first lens and the second lens is 2mm-4mm, the air gap between the beam-combining prism and the rear fixed lens group is 2mm-3mm, and the air gap between the fourth lens and the fifth lens is 0.3mm-1.3mm.

[0012] As a further preferred embodiment, the radius of curvature R1 of the object side of the first lens satisfies -15mm≤R1≤-5mm, and the radius of curvature R2 of the image side satisfies 20mm≤R2≤30mm. The radius of curvature R3 of the object side of the second lens satisfies -12mm≤R3≤-2mm, and the radius of curvature R4 of the image side satisfies -50mm≤R4≤-40mm. The radius of curvature R5 of the object side of the third lens satisfies 5mm≤R5≤15mm, and the radius of curvature R6 of the image side satisfies -15mm≤R6≤-5mm. The radius of curvature R7 of the object side of the fourth lens satisfies 5mm≤R7≤15mm, and the radius of curvature R8 of the image side satisfies -30mm≤R8≤-20mm. The radius of curvature R9 of the object side of the fifth lens satisfies 2mm≤R9≤8mm, and the radius of curvature R10 of the image side satisfies 5mm≤R10≤10mm.

[0013] As a further preferred embodiment, both the object-side surface and the image-side surface of the third lens are aspherical. And / or the object-side surface and image-side surface of the fourth and fifth lenses are both aspherical; And / or the object-side surface and image-side surface of the first lens and the second lens are both spherical.

[0014] As a further preferred embodiment, when the above-mentioned beam-combining prism is provided in the optical system, the beam-combining prism includes two cemented right-angle prisms; the light-transmitting surface of the beam-combining prism is a high-transmittance anti-reflection coated surface, the cemented surface is a beam-splitting coated surface, and the non-light-transmitting surface is a frosted surface.

[0015] As a further preferred embodiment, the beam-splitting coating has high transmittance for the first band beam and high reflectivity for the second band beam.

[0016] As a further preferred embodiment, the dispersion coefficients of the first lens, the second lens, and the fifth lens are all less than 50, and the dispersion coefficients of the third lens and the fourth lens are both greater than 75.

[0017] As a further preferred embodiment, the material of the first lens is D-ZLAF85A; the material of the second lens is D-ZLAF52LA; the material of the third lens is D-FK61; the material of the fourth lens is D-FK61; and the material of the fifth lens is D-ZLAF67.

[0018] When the above-mentioned beam combiner prism is set in the optical system, the material of the beam combiner prism is H-K9L.

[0019] As a further preferred embodiment, the center thickness of the first lens is in the range of 5mm-7mm; the center thickness of the second lens is 1mm-3mm; the center thickness of the third lens is 4mm-6mm; the center thickness of the fourth lens is 4mm-6mm; and the center thickness of the fifth lens is 2mm-4mm. And / or when the above-mentioned beam combiner prism is provided in the optical system, the size range of the beam combiner prism is A. 3 mm 3 The value of A ranges from 13mm to 17mm.

[0020] Secondly, this application also provides an optical lens, which includes an aperture stop and an optical system further preferably described in any of the first aspects; the aperture stop is disposed at the front of the optical system. The front aperture stop can intercept stray light rays deviating from the main optical path in the initial stage of the light beam entering the system, reduce multiple reflections of stray light inside the system, and reduce the interference of stray light on imaging.

[0021] Thirdly, this application also provides an electronic device including a housing and the optical lens described in the second aspect, the optical lens being disposed within the housing. By incorporating the optical lens provided in this application into the electronic device, the electronic device can possess continuous internal focusing functionality.

[0022] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages: This application provides an optical system, an optical lens, and an electronic device. The optical system employs an internal focusing variable working distance design and consists of multiple lens groups, including a front fixed lens group, a front movable lens group, and a rear fixed lens group. The front fixed lens group uses a material with high Abbe number and low dispersion characteristics, providing light shaping and beam expansion effects to accommodate changes in light height during focusing on glass of varying thicknesses.

[0023] This application provides an optical system, an optical lens, and an electronic device, wherein the front movable lens group is a key component for realizing the internal focusing function. By employing a movable lens design, the material and curvature design of the movable lens group are optimized so that it can effectively correct differences in light propagation caused by changes in working distance when moving within a small range, while maintaining a small range of focal length changes.

[0024] This application provides an optical system, an optical lens, and an electronic device, with a beam-combining prism serving as a key component in subsequent illumination or servo beam-combining modules. The servo optical path can be expanded and shaped before being connected to the main optical path, adding closed-loop control to the laser etching process or stable imaging of the optical system, enabling the optical system to be stably operated on the required plane; the illumination optical path can also be beam-combined with the main optical path to achieve clear imaging requirements.

[0025] This application provides an optical system, an optical lens, and an electronic device. The fixed rear lens is responsible for accurately focusing the light, adjusted by the moving lens group, onto the desired recording or imaging plane. Its material and curvature design take into account the light propagation characteristics caused by a certain range of glass thickness variations, further correcting the main aberrations that may affect the system, such as spherical aberration and astigmatism, to ensure accurate focusing throughout the entire working distance. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the optical system structure without a beam-combining prism provided in the embodiments of this application; Figure 2 This is a schematic diagram of the optical system structure corresponding to the first working distance when a beam-combining prism is provided in the embodiments of this application; Figure 3 This is a schematic diagram of the optical system structure corresponding to the second working distance when a beam-combining prism is provided in the embodiments of this application; Figure 4 This is a schematic diagram of the optical system structure corresponding to the third working distance when a beam-combining prism is provided in the embodiments of this application; Figure 5 This is provided by the embodiments of this application. Figure 2 A schematic diagram of the transfer function curve of the corresponding optical system; Figure 6 This is provided by the embodiments of this application. Figure 3 A schematic diagram of the transfer function curve of the corresponding optical system; Figure 7 This is provided by the embodiments of this application. Figure 4 A schematic diagram of the transfer function curve of the corresponding optical system; Figure 8 This is provided by the embodiments of this application. Figure 2 Schematic diagram of field curvature aberration of the corresponding optical system; Figure 9 This is provided by the embodiments of this application. Figure 3Schematic diagram of field curvature aberration of the corresponding optical system; Figure 10 This is provided by the embodiments of this application. Figure 4 Schematic diagram of field curvature aberration of the corresponding optical system; Figure 11 This is provided by the embodiments of this application. Figure 2 Schematic diagram of the corresponding optical system wavefront; Figure 12 This is provided by the embodiments of this application. Figure 3 Schematic diagram of the corresponding optical system wavefront; Figure 13 This is provided by the embodiments of this application. Figure 4 Schematic diagram of the corresponding optical system wavefront; Figure 14 This is a schematic diagram of the optical lens structure provided in an embodiment of this application; Figure 15 This is a schematic diagram of the electronic device structure provided in the embodiments of this application.

[0027] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 is the first lens, 2 is the second lens, 3 is the third lens, 4 is the beam combiner prism, 5 is the fourth lens, 6 is the fifth lens, 7 is glass; 10 is the optical system, 20 is the aperture stop; 100 is the optical lens, 200 is the housing. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0029] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0030] Furthermore, throughout this specification, references to "an embodiment"; "an embodiment," "an example," or similar language indicate that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of this application. Therefore, the appearance of the phrase "in one embodiment;" throughout this specification, and similar language, may, but not necessarily, refer to the same embodiment.

[0031] Figure 1This is a schematic diagram of the optical system without a beam-combining prism provided in the embodiments of this application; as shown... Figure 1 As shown, along the optical axis, the optical system is provided with a front fixed lens group, a front movable lens group, and a rear fixed lens group in sequence from the object plane to the image plane. The front fixed lens group includes: The first lens 1, which has negative optical power, has concave surfaces on both the object side and the image side near the optical axis; The second lens 2, which has negative optical power, has an object-side surface that is concave near the optical axis and an image-side surface that is convex near the optical axis. The forward-moving lens group includes: The third lens 3, which has positive optical power, has convex surfaces on both the object side and the image side near the optical axis; The rear fixed lens group includes: The fourth lens 5 has positive optical power, and both the object side and the image side are convex near the optical axis; The fifth lens 6, which has positive optical power, has a convex surface on the object side near the optical axis and a concave surface on the image side near the optical axis.

[0032] In one embodiment, the air gap between the first lens 1 and the second lens 2 is 2mm-4mm, and the air gap between the fourth lens 5 and the fifth lens 6 is 0.3mm-1.3mm.

[0033] In one embodiment, the radius of curvature R1 of the object side of the first lens 1 satisfies -15mm≤R1≤-5mm, and the radius of curvature R2 of the image side satisfies 20mm≤R2≤30mm. The radius of curvature R3 of the object side of the second lens 2 satisfies -12mm≤R3≤-2mm, and the radius of curvature R4 of the image side satisfies -50mm≤R4≤-40mm; The radius of curvature R5 of the object side of the third lens 3 satisfies 5mm≤R5≤15mm, and the radius of curvature R6 of the image side satisfies -15mm≤R6≤-5mm. The radius of curvature R7 of the object side of the fourth lens 5 satisfies 5mm≤R7≤15mm, and the radius of curvature R8 of the image side satisfies -30mm≤R8≤-20mm. The radius of curvature R9 of the object side of the fifth lens 6 satisfies 2mm≤R9≤8mm, and the radius of curvature R10 of the image side satisfies 5mm≤R10≤10mm.

[0034] In one embodiment, the object-side surface and image-side surface of the third lens 3, the fourth lens 5 and / or the fifth lens 6 are both aspherical; the object-side surface and image-side surface of the first lens 1 and the second lens 2 are both spherical.

[0035] In one embodiment, the dispersion coefficients of the first lens 1, the second lens 2, and the fifth lens 6 are all less than 50, and the dispersion coefficients of the third lens 3 and the fourth lens 5 are all greater than 75.

[0036] In one embodiment, the material of the first lens 1 is D-ZLAF85A; the material of the second lens 2 is D-ZLAF52LA; the material of the third lens 3 is D-FK61; the material of the fourth lens is D-FK61; and the material of the fifth lens is D-ZLAF67.

[0037] In one embodiment, the center thickness of the first lens ranges from 5mm to 7mm; the center thickness of the second lens ranges from 1mm to 3mm; the center thickness of the third lens ranges from 4mm to 6mm; the center thickness of the fourth lens ranges from 4mm to 6mm; and the center thickness of the fifth lens ranges from 2mm to 4mm.

[0038] In one embodiment, targeting Figure 1 In the optical system shown, during focusing, the air gap D1 between the front fixed lens group and the front moving lens group varies within the range of 1.149mm≤D1≤5.703mm, and the air gap D2 between the front moving lens group and the rear fixed lens group varies within the range of 18.293mm≤D2≤22.847mm.

[0039] In a specific application scenario, the aforementioned optical system typically has a target object (such as glass of a certain thickness) positioned on its image side. This target object can be positioned starting from the minimum working distance. The minimum working distance refers to the closest distance the target object can be to the optical system. Furthermore, when... Figure 1 When the optical system shown operates on glass with a thickness of 0mm-2mm, the minimum working distance can be 0.6mm.

[0040] For example, by adjusting the position of the third lens 3 along the optical axis in the optical system, while keeping the position of the optical system unchanged, focusing correction function of glass with a thickness of 0mm-2mm can be achieved by focusing only through a single lens group. This effectively controls the optical system to focus at high quality to different working distances and effectively solves aberration problems.

[0041] When focusing on different glass thicknesses, the focusing interval of the above optical system can be varied as shown in Table 1: Table 1. Changes in focal distance of the optical system without a beam-combining prism. Figure 2 This is a schematic diagram of the optical system corresponding to the first working distance when a beam-combining prism is provided in an embodiment of this application; as shown... Figure 2As shown, between the front moving lens group and the rear fixed lens group, there is also a beam combining prism 4; the beam combining prism 4 is used to combine the first band beam incident from the object plane along the optical axis and the second band beam incident perpendicular to the optical axis, and to emit the combined beam out along the optical axis to the image plane.

[0042] In one embodiment, the beam combiner prism 4 includes two cemented right-angle prisms, that is, it is composed of two cemented right-angle prisms; the light-transmitting surface of the beam combiner prism 4 is a high-transmittance anti-reflection coated surface, the cemented surface is a beam-splitting coated surface, and the non-light-transmitting surface is a frosted surface.

[0043] In one embodiment, the beam-splitting coating has high transmittance for the first band of light beam and high reflectivity for the second band of light beam.

[0044] Furthermore, the first band beam can be a near-infrared band beam, and the second band beam can be visible light.

[0045] The aforementioned near-infrared beam can be applied to the target object on the image side of the optical system, and can be used for laser multidimensional lithography, high-precision imaging and detection of the target object in a specific small field of view.

[0046] The aforementioned visible light is used to assist in illuminating the target object during near-infrared beam operations.

[0047] In one embodiment, the size range of the beam-combining prism 4 is A. 3 mm 3 The value of A ranges from 13mm to 17mm.

[0048] In one embodiment, the air gap between the beam-combining prism 4 and the rear fixed lens group is 2mm-3mm.

[0049] In one embodiment, the material of the combining prism 4 is H-K9L.

[0050] Understandably, after the aforementioned optical system is packaged into an optical lens, the focusing mechanism inside the lens barrel can consist of a high-precision miniature guide rail and a drive unit. The guide rail uses highly stable materials and processing techniques to ensure dimensional stability under temperature changes and long-term use, thus ensuring the precise axial and radial position of the lens during movement. The drive unit can precisely control the movement of the forward-moving lens group with extremely small displacements, meeting the micro-displacement requirements of applications such as multi-dimensional engraving, small-field-of-view high-precision imaging, and detection in laser systems.

[0051] The above Figure 1 and Figure 2The provided optical system and related parameters enable internal focusing. Combined with an aperture stop, it functions as an optical lens suitable for a main wavelength of 1030nm and a working distance ranging from 0.6mm to 2.6mm. The focal length (NA) is greater than 0.7 (NA is approximately equal to D / 2f, where D represents the aperture diameter and f represents the focal length). While maintaining the lens position, single-lens focusing achieves 0mm-2mm glass correction, effectively addressing aberrations and improving focusing quality to meet the application requirements of laser multidimensional lithography, high-precision imaging and inspection in specific small fields of view.

[0052] Among them, the above Figure 1 and Figure 2 The optical system parameters shown are: numerical aperture NA: 0.7; focal length f: 1.5mm-1.7mm; dominant wavelength: 1030nm, which can be corrected by internal focusing to achieve different thicknesses of glass from 0mm to 2mm; total optical length: 50mm (see the total thickness from the aperture stop to lens 6 in Table 2).

[0053] In a more specific embodiment, the above Figure 2 In the optical system shown, the parameters of each optical element are as shown in Table 2: Table 2 System Optical Component Parameter Table In Table 2, surfaces 2 and 3 represent the object-plane side and image-plane side of the first lens (lens 1), respectively; surfaces 4 and 5 represent the object-plane side and image-plane side of the second lens (lens 2), respectively; surfaces 6 and 7 represent the object-plane side and image-plane side of the third lens (lens 3), respectively; surfaces 8 and 9 can represent the object-plane side and image-plane side of the beam-combining prism (lens 4); surfaces 10 and 11 can represent the object-plane side and image-plane side of the fourth lens (lens 5); and surfaces 12 and 13 can represent the object-plane side and image-plane side of the fifth lens (lens 6). Those skilled in the art will understand that the side of a lens closest to the object plane is generally called the object-plane side, and the side closest to the image plane is called the image-plane side. This application will not further elaborate on these concepts.

[0054] Among them, lens 7 represents the target object, namely glass with a thickness of d.

[0055] The thickness of surface 2 can represent the center thickness of the first lens (lens 1), and the thickness of surface 3 can represent the vertical distance between the side of the first lens (lens 1) near the image plane and the side of the second lens (lens 2) near the object plane. The same applies to surfaces 3-13.

[0056] The beam combiner prism (lens 4) is an integrated optical element for beam splitting and beam combining. When the first band beam is a near-infrared beam and the second band beam is visible light, the core function of the beam combiner prism is to achieve high transmission of the near-infrared laser beam and high deflection of the visible light beam, so that the two beams can be combined and output in the same optical axis and optical path. Its beam combining coaxiality is higher and its installation and adjustment are more convenient.

[0057] Further, referring to Table 2, the material of the first lens (lens 1) is DZLAF85A (refractive index 1.85, dispersion coefficient 40.1); the material of the second lens (lens 2) is DZLAF52LA (refractive index 1.81, dispersion coefficient 41); the material of the third lens (lens 3) is DFK61 (refractive index 1.50, dispersion coefficient 81.6); the material of the beam combiner prism (lens 4) is HK9L (refractive index 1.52, dispersion coefficient 64.2); the material of the fourth lens (lens 5) is DFK61 (refractive index 1.50, dispersion coefficient 81.6); and the material of the fifth lens (lens 6) is DZLAF67 (refractive index 1.88, dispersion coefficient 37.2).

[0058] It should be noted that, referring to Table 2, the object-side and image-side surfaces of the third, fourth, and fifth lenses are all aspherical. In a specific embodiment, the aspherical coefficients of this optical system are shown in Table 3: Table 3 Aspherical Coefficients of Optical Systems Furthermore, the focal interval variation of this optical system is shown in Table 4: Table 4. Focusing Interval Variation of Optical System with Beam-Splitter Prism Figure 3 This is a schematic diagram of the optical system corresponding to the second working distance when a beam-combining prism is provided in an embodiment of this application; optionally, the second working distance is 1.6 mm.

[0059] Figure 4 This is a schematic diagram of the optical system corresponding to the third working distance when a beam-combining prism is provided in the embodiments of this application; optionally, the third working distance is 2.6 mm.

[0060] As can be seen from the first to the third working distances mentioned above, the working distance range of the optical system covers at least 0.6mm-2.6mm.

[0061] Figures 5 to 7 They are respectively Figures 2 to 4The diagram shows the modulation transfer function (MTF) curve of the corresponding optical system. The MTF curve represents the overall resolution of the optical system and describes the magnitude of the optical transfer function (OTF).

[0062] This optical system operates in the near-infrared band. See [link / reference] Figures 5 to 7 It can be seen that after balancing the performance and aberrations at different working distances, the MTF approaches the diffraction limit, giving the system high resolution characteristics.

[0063] Figures 8 to 10 They are respectively Figures 2 to 4 Schematic diagram of field curvature aberration of the corresponding optical system; Figures 8 to 10 As shown above, the axial chromatic aberration and astigmatism field curvature are both within ±2μm, and the distortion is within 0.2%, indicating that the aberrations are well corrected, which is beneficial for high-quality imaging.

[0064] Figures 11 to 13 They are respectively Figures 2 to 4 The diagram shows the wavefront of the corresponding optical system. It can be seen that at a working distance of 0.6 mm, the peak-to-valley (PV) error of the optical system is 0.1616λ, and the root mean square (RMS) error is 0.0480λ, where λ represents the wavelength. At a working distance of 1.6 mm, the wavefront PV error is 0.1435λ, and the RMS error is 0.0421λ. At a working distance of 2.6 mm, the wavefront PV error is 0.0715λ, and the RMS error is 0.0147λ.

[0065] Combination Figures 11 to 13 It can be seen that the PV of the wavefront of the optical system provided in this application embodiment is less than 0.25λ and the RMS is less than 0.1λ, the imaging quality is close to the theoretical diffraction limit, and it has good resolution.

[0066] like Figure 14 As shown, this application also provides an optical lens, which includes an aperture stop 20 and the aforementioned... Figures 1 to 4 The optical system 10 is shown. The aperture stop 10 is located at the front of the optical system 20. The front aperture stop can intercept stray light rays that deviate from the main optical path in the initial stage of the light beam entering the system, reduce multiple reflections of stray light inside the system, and reduce the interference of stray light on imaging.

[0067] In one embodiment, the aperture is located 0.2 mm from the front end of the first lens (lens 1).

[0068] Understandably, the aforementioned optical lens also features an additional rear aperture stop. This rear aperture stop's position does not change with the movement of the zoom lens group, eliminating the need for a linkage structure between the aperture stop and the zoom group. This significantly simplifies the mechanical structure of the zoom system, reduces the need for linkage calibration steps during assembly, and lowers manufacturing and assembly errors. Movement of the zoom lens group can easily generate edge reflections and stray light from the inner wall of the lens barrel. The front aperture stop 20 can intercept stray light deviating from the main optical path during the initial stage of the beam entering the system, reducing multiple reflections of stray light within the system, minimizing stray light interference with imaging, and improving image contrast. This is particularly suitable for high-precision focusing scenarios such as a 1030nm main wavelength and high NA, preventing stray light from affecting focusing accuracy.

[0069] This application relates to the field of optical lenses, and more particularly to an internal focusing laser optical system suitable for focusing correction of glass thickness from 0mm to 2mm, with a working distance from 0.6mm to 2.6mm. The system achieves the correction function without changing the relative position of the lens system, and reserves a module for adding servo or illumination within the system. It can be used in fields such as laser multidimensional lithography, specific optical imaging, and high-precision detection.

[0070] In summary, this application develops an internal focusing lens optical system that is compatible with a 1030nm main wavelength, close working distance, and high NA requirements. It can achieve 0mm-2mm glass thickness correction and aberration suppression by simply adjusting one lens group while keeping the lens body stationary. This completely solves the drawbacks of traditional objective lenses with correction rings that require "dual movement of the objective lens and the correction lens group," as well as the problems of insufficient focusing accuracy, significant aberrations, and complex structures in existing technologies.

[0071] See Figure 15 This application also provides an electronic device, which includes the aforementioned optical lens 100 and a housing 200, with the optical lens 100 disposed within the housing 200. By incorporating the optical lens 100 provided in this application into the electronic device, the device can possess continuous internal focusing functionality. This electronic device includes, but is not limited to, micro / nano fabrication systems, microlithography systems, industrial defect detection systems, and high-precision imaging analysis systems.

[0072] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An optical system, characterized in that, Along the optical axis, from the object plane to the image plane, there are sequentially arranged a front fixed lens group, a front movable lens group that can move along the optical axis, and a rear fixed lens group. The front fixed lens group includes: The first lens with negative optical power has concave surfaces on both the object side and the image side near the optical axis; The second lens with negative optical power has an object-side surface that is concave near the optical axis and an image-side surface that is convex near the optical axis. The forward-moving lens group includes: The third lens has positive optical power, and both the object-side and image-side surfaces are convex near the optical axis. The rear fixed lens group includes: The fourth lens has positive optical power, and both the object-side and image-side surfaces are convex near the optical axis. The fifth lens has positive optical power, with the object side being convex near the optical axis and the image side being concave near the optical axis.

2. The optical system as claimed in claim 1, characterized in that, Along the optical axis, between the front movable lens group and the rear fixed lens group, there is also a beam combining prism; The beam combining prism is used to combine a first-band beam incident along the optical axis from the object plane and a second-band beam incident perpendicular to the optical axis, and to emit the combined beam along the optical axis out onto the image plane.

3. The optical system as described in claim 1, characterized in that, During focusing, the air gap D1 between the front fixed lens group and the front moving lens group varies within the range of 1.149mm ≤ D1 ≤ 5.703mm, and the air gap D2 between the front moving lens group and the rear fixed lens group varies within the range of 18.293mm ≤ D2 ≤ 22.847mm.

4. The optical system as described in claim 2, characterized in that, During focusing, the air gap D1 between the front fixed lens group and the front moving lens group varies within the range of 1.203mm ≤ D1 ≤ 5.993mm, and the air gap D3 between the front moving lens group and the beam combiner prism varies within the range of 1.503mm ≤ D3 ≤ 6.293mm.

5. The optical system as described in claim 2, characterized in that, The air gap between the first and second lenses is 2mm-4mm, the air gap between the beam combiner prism and the rear fixed lens group is 2mm-3mm, and the air gap between the fourth and fifth lenses is 0.3mm-1.3mm; and / or The center thickness of the first lens ranges from 5mm to 7mm; the center thickness of the second lens ranges from 1mm to 3mm; the center thickness of the third lens ranges from 4mm to 6mm; the center thickness of the fourth lens ranges from 4mm to 6mm; and the center thickness of the fifth lens ranges from 2mm to 4mm. And / or the size range of the beam combining prism is A 3 mm 3 The value of A ranges from 13mm to 17mm.

6. The optical system as claimed in claim 1, characterized in that, The radius of curvature R1 of the object side of the first lens satisfies -15mm≤ R1≤-5mm, and the radius of curvature R2 of the image side satisfies 20mm≤ R2≤30mm; The radius of curvature R3 of the object side of the second lens satisfies -12mm≤ R3≤-2mm, and the radius of curvature R4 of the image side satisfies -50mm≤ R4≤-40mm; The radius of curvature R5 of the object side of the third lens satisfies 5mm ≤ R5 ≤ 15mm, and the radius of curvature R6 of the image side satisfies -15mm ≤ R6 ≤ -5mm. The curvature radius R7 of the object side of the fourth lens satisfies 5mm ≤ R7 ≤ 15mm, and the curvature radius R8 of the image side satisfies -30mm ≤ R8 ≤ -20mm. The curvature radius R9 of the object side of the fifth lens satisfies 2mm ≤ R9 ≤ 8mm, and the curvature radius R10 of the image side satisfies 5mm ≤ R10 ≤ 10mm.

7. The optical system as claimed in claim 1, characterized in that, Both the object-side surface and the image-side surface of the third lens are aspherical. And / or the object-side surface and image-side surface of the fourth and fifth lenses are both aspherical; And / or the object-side surface and image-side surface of the first lens and the second lens are both spherical; And / or the beam combiner prism comprises two cemented right-angle prisms; the light-transmitting surface of the beam combiner prism is a high-transmittance anti-reflection coated surface, the cemented surface is a beam-splitting coated surface, and the non-light-transmitting surface is a frosted surface; the beam-splitting coated surface has high transmittance for the first band beam and high reflectivity for the second band beam.

8. The optical system as claimed in claim 1, characterized in that, The dispersion coefficients of the first, second, and fifth lenses are all less than 50, while the dispersion coefficients of the third and fourth lenses are both greater than 75.

9. An optical lens, characterized in that, Includes an aperture and an optical system as described in any one of claims 1 to 8.

10. An electronic device, characterized in that, It includes a housing and an optical lens as described in claim 9, wherein the optical lens is disposed within the housing.

Images