Line scanning camera lens

Abstract

The utility model provides a line scanning camera lens comprising a lens group, an aperture diaphragm, a lens barrel and an adjusting assembly, the lens group sequentially comprises a first lens to a fourth lens from the object side to the image side of the line scanning camera lens, the aperture diaphragm is located at the image side of the third lens, and the image side end of the aperture diaphragm is provided with a step part; the object side face of the fourth lens and the outer ring face of the fourth lens abut against the step part. The lens group and the aperture diaphragm are both accommodated in the lens cone; at least one part of the adjusting assembly can penetrate through the lens barrel to abut against the aperture diaphragm, so that the aperture diaphragm drives the fourth lens to adjust the position. The problems that in the prior art, the scanning object distance and the scanning width of a line scanning camera lens are short, and imaging eccentricity is serious are solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to machine vision technical field, specifically, relate to a line scan camera lens. BACKGROUND

[0002] At present, the machine vision, AI artificial intelligence field develops rapidly, and the application of line scan camera lens is more and more widely, and the line scan camera lens as one branch field, the work scene of thousands of differences, the requirement of imaging measurement analysis and judgment is also various, so more and more requirements are put forward to line scan camera lens.In the application of existing line scan camera lens, the error of processing and forming, installation error or the slight displacement between optical components can cause the imaging surface of adjacent line scan camera lens to appear eccentric, cause the imaging surface to be misaligned, the inaccuracy of overlap or the incompleteness of imaging surface boundary, seriously affect the accuracy and efficiency of scanning.At the same time, the line scan camera lens usually adopts columnar lens, is suitable for close-range scanning, and the object distance is usually not more than 20mm.When the occasion of more distant object distance scanning is needed, the line scan camera lens with columnar lens at this time cannot meet the requirements.In addition, the line scan camera lens can obtain imaging at a long distance, but cannot be made into an integrated compact structure, and if a long scanning width is needed, on-site debugging and installation are needed to splice imaging, and the maintenance requirement is high.

[0003] That is to say, the line scan camera lens in the prior art has the problems of short scanning object distance and scanning width and serious imaging eccentricity. CONTENT OF THE UTILITY MODEL

[0004] The utility model discloses a line scan camera lens to solve the problem of short scanning object distance and scanning width and serious imaging eccentricity of the line scan camera lens in the prior art.

[0005] In order to realize the above-mentioned purpose, the utility model provides a line scan camera lens, which comprises: a lens group, from the object side to the image side of the line scan camera lens, the lens group sequentially comprises a first lens to a fourth lens, the first lens has positive focal power, the object side surface of the first lens is a convex surface, the image side surface of the first lens is a plane, the second lens has positive focal power, the object side surface of the second lens is a convex surface, the image side surface of the second lens is a plane, the third lens has negative focal power, the object side surface of the third lens and the image side surface of the third lens are both concave surfaces, the fourth lens has positive focal power, the object side surface of the fourth lens is a plane, and the image side surface of the fourth lens is a convex surface;An aperture stop, the aperture stop is located on the image side of the third lens, the image side end of the aperture stop has a step portion, and the object side surface of the fourth lens and the outer ring surface of the fourth lens are all in abutment with the step portion;A lens barrel, the lens group and the aperture stop are all accommodated in the lens barrel;An adjusting assembly, at least a part of the adjusting assembly can pass through the lens barrel and push the aperture stop, so that the aperture stop drives the fourth lens to adjust the position.

[0006] Further, the focal length f1 of the first lens and the focal length f of the line scan camera lens satisfy: 0.85<|f1| / f<1.05.

[0007] Further, the focal length f2 of the second lens and the focal length f of the line scan camera lens satisfy: 0.3<|f2| / f<0.55.

[0008] Further, the focal length f3 of the third lens and the focal length f of the line scan camera lens satisfy: 0.15<|f3| / f<0.25.

[0009] Further, the focal length f4 of the fourth lens and the focal length f of the line scan camera lens satisfy: 0.5<|f4| / f<0.7.

[0010] Further, the total optical length TTL of the line scan camera lens and the object distance L of the line scan camera lens satisfy: 1.0≤TTL / L≤1.2.

[0011] Further, the aperture stop is spaced apart from the inner wall surface of the lens barrel, the outer annular surface of the aperture stop has a bearing portion and an adjusting portion, the bearing portion bears against the lens group, the adjusting portion is correspondingly arranged with the adjusting assembly, and the adjusting portion is concave to the optical axis of the line scan camera lens relative to the bearing portion.

[0012] Further, the adjusting portion has an adjusting groove and two connecting surfaces, the adjusting groove is connected with the bearing portion through the connecting surfaces, and at least a part of the adjusting assembly can extend into the adjusting groove to push the aperture stop.

[0013] Further, the lens barrel has at least one top screw adjusting hole penetrating the wall thickness of the lens barrel, the top screw adjusting hole is arranged towards the aperture stop, the adjusting assembly includes a top screw adjusting piece, the top screw adjusting hole and the top screw adjusting piece are one-to-one correspondingly arranged, and the top screw adjusting piece can extend into the adjusting groove to push the aperture stop.

[0014] Further, the projection of the top screw adjusting hole on the groove bottom surface of the adjusting groove is located within the outer periphery of the groove bottom surface of the adjusting groove.

[0015] Further, the lens barrel is provided with at least two top screw adjusting holes, and the connecting line of the two top screw adjusting holes is perpendicular to the optical axis of the line scan camera lens and perpendicular to the scanning direction of the line scan camera lens.

[0016] Further, from the object side to the image side of the line scan camera lens, the inner annular surface of the aperture stop extends towards the direction close to the optical axis of the line scan camera lens.

[0017] Further, the line scan camera lens further comprises a special-shaped stop, the special-shaped stop is arranged between the first lens and the second lens, and the inner diameter of at least a part of the special-shaped stop is gradually expanded.

[0018] Furthermore, the inner ring surface of the irregular aperture is symmetrically arranged with respect to the optical axis of the line scan camera lens. The inner ring surface of the irregular aperture includes two oppositely arranged expansion sections and two oppositely arranged transition sections. The two ends of the transition sections are respectively connected to the two expansion sections, and the arrangement direction of the two transition sections is parallel to the scanning direction of the line scan camera lens.

[0019] Furthermore, the transition section is an arc surface, with the center of the arc surface and the optical axis set on the same side of the transition section. The minimum light transmission radius R1 of the aperture stop and the radius R2 of the arc surface satisfy the following condition: R2 = 1.2 × R1.

[0020] Furthermore, the minimum light-transmitting radius R1 of the aperture stop and the shortest distance D between the two expansion sections satisfy the following condition: D = 0.72 × R1.

[0021] Furthermore, the minimum light-transmitting radius R1 of the aperture stop and the length B of the transition section along the scanning direction satisfy the following condition: B = 4.8 × R1.

[0022] According to the technical solution of this utility model, the line scan camera lens includes a lens group, an aperture stop, a lens barrel, and an adjustment assembly. From the object side to the image side of the line scan camera lens, the lens group sequentially includes a first lens to a fourth lens. The first lens has positive optical power, its object side is convex, and its image side is flat. The second lens has positive optical power, its object side is convex, and its image side is flat. The third lens has negative optical power, and both its object side and image side are concave. The fourth lens has positive optical power, its object side is flat, and its image side is convex. The aperture stop is located on the image side of the third lens, and its image side end has a stepped portion. The object side and outer ring surface of the fourth lens both abut against the stepped portion. The lens group and the aperture stop are both housed within the lens barrel. At least a portion of the adjustment assembly can pass through the lens barrel and push against the aperture stop, so that the aperture stop drives the fourth lens to adjust its position.

[0023] The line scan camera lens of this application includes a lens group and an aperture stop within its barrel. Lenses one through four are arranged sequentially from the object side to the image side. The first and second lenses both have positive optical power. The object side of the first lens is convex, and its image side is flat. Similarly, the object side and image side of the second lens are also convex, facilitating initial light convergence. The third lens has negative optical power. Both its object and image sides are concave, correcting aberrations in the lens group, especially chromatic aberration and spherical aberration, ensuring accurate focusing of light of different wavelengths on the imaging plane. The fourth lens has positive optical power. Its object side is flat, and its image side is convex, further aiding in light convergence while maintaining image sharpness. In other words, the combination of positive and negative optical power lenses ensures effective light convergence after passing through the lens group, while controlling aberrations, achieving high-definition and high-resolution imaging. The selection and combination of the aforementioned lenses facilitates clear imaging at long object distances in line scan cameras, enhancing their long-distance scanning capabilities. Furthermore, all optical elements are housed within the lens barrel, achieving a compact and integrated structure to accommodate scanning widths of any distance.

[0024] In this application, the aperture stop is located on the image side of the third lens, and the image side end of the aperture stop has a stepped portion. At least a portion of the object side surface and the outer ring surface of the fourth lens rest on the stepped portion. That is, the stepped portion encloses at least a portion of the object side surface and at least a portion of the outer ring surface of the fourth lens, improving the positioning accuracy of the aperture stop and the fourth lens. Outside the fourth lens, at least a portion of the adjustment assembly contacts the aperture stop through the lens tube, which can push the aperture stop, thereby adjusting the position of the fourth lens. This corrects the imaging misalignment of adjacent line scan camera lenses, compensates for optical misalignment caused by manufacturing errors or installation deviations, ensures the continuity and consistency of imaging in the scanning direction, avoids imaging misalignment or ghosting, and improves the accuracy and efficiency of scanning. Attached Figure Description

[0025] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an undue limitation of the present invention. In the drawings:

[0026] Figure 1 A schematic diagram of the structure of a line scan camera lens according to an optional embodiment of the present invention is shown;

[0027] Figure 2 It shows Figure 1 Optical path layout diagram of the center-line scan camera lens after linear array arrangement along the scanning direction;

[0028] Figure 3 It shows Figure 1 Axial view of the centerline scanning camera lens array arranged along the scanning direction;

[0029] Figure 4 It shows Figure 1 A schematic diagram of the parameters of the irregular aperture of a center-scan camera lens;

[0030] Figure 5 It shows Figure 1 The brightness waveform of the image from the center-scan camera lens;

[0031] Figure 6 It shows Figure 1 A schematic diagram of the image after compensation for the offset of the centerline scanning camera lens;

[0032] Figure 7 The MTF curve of the line scan camera lens of Embodiment 1 of this utility model is shown;

[0033] Figure 8 The optical distortion curve of the line scan camera lens of Embodiment 1 of this utility model is shown;

[0034] Figure 9 The MTF curve of the line scan camera lens of Embodiment 2 of this utility model is shown;

[0035] Figure 10 The optical distortion curve of the line scan camera lens of Embodiment 2 of this utility model is shown;

[0036] Figure 11 The image brightness waveform of a line scan camera lens without an irregular aperture is shown in the prior art.

[0037] Figure 12 This diagram illustrates the imaging process in a prior art line scan camera lens when the lens is not compensated for eccentricity.

[0038] The above figures include the following reference numerals:

[0039] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Aperture stop; 51. Support part; 52. Adjustment part; 53. Adjustment groove; 54. Connecting surface; 6. Set screw adjustment hole; 7. Irregular aperture stop; 71. Diameter expansion section; 72. Transition section; 8. Object surface; 9. Linear array chip; 10. Lens barrel. Detailed Implementation

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0042] In this utility model, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not used to limit this utility model.

[0043] The main objective of this invention is to provide a line scan camera lens to solve the problems of short scanning distance and scanning width, and severe image eccentricity in existing line scan camera lenses.

[0044] like Figures 1 to 10 As shown, the line scan camera lens includes a lens group, an aperture stop 5, a lens barrel 10, and an adjustment assembly. From the object side to the image side of the line scan camera lens, the lens group sequentially includes a first lens 1 to a fourth lens 4. The first lens 1 has positive optical power, its object side is convex, and its image side is flat. The second lens 2 has positive optical power, its object side is convex, and its image side is flat. The third lens 3 has negative optical power, and both its object side and image side are concave. The fourth lens 4 has... It has positive optical power. The object side of the fourth lens is flat, and the image side of the fourth lens is convex. The aperture stop 5 is located on the image side of the third lens 3. The image side end of the aperture stop 5 has a stepped portion. The object side of the fourth lens and the outer ring surface of the fourth lens are both supported by the stepped portion. The stepped portion covers at least a part of the object side of the fourth lens and the outer ring surface of the fourth lens. The lens group and the aperture stop 5 are both housed in the lens barrel 10. At least a part of the adjustment component can pass through the lens barrel 10 to push the aperture stop 5, so that the aperture stop 5 drives the fourth lens 4 to adjust its position.

[0045] The lens barrel 10 of the line scan camera lens of this application includes a lens group and an aperture stop 5. Lenses 1 to 4 are arranged sequentially from the object side to the image side. Lens 1 and 2 both have positive optical power. The object side of the first lens is convex, and its image side is flat. Similarly, the object side and image side of the second lens are also convex and flat, which helps in the initial convergence of light. Lens 3 has negative optical power. Both its object side and image side are concave, which corrects aberrations in the lens group, especially chromatic aberration and spherical aberration, ensuring accurate focusing of light of different wavelengths on the imaging plane. Lens 4 has positive optical power. Its object side is flat, and its image side is convex, which helps the line scan camera lens further converge light while maintaining image sharpness. In other words, the combination of positive and negative optical power lenses ensures that light is effectively converged after passing through the lens group, while controlling aberrations, achieving high-definition and high-resolution imaging. The selection and combination of the aforementioned lenses facilitates clear imaging at long object distances in line scan cameras, enhancing their long-distance scanning capabilities. Furthermore, all optical elements are housed within the lens barrel, achieving a compact and integrated structure to accommodate scanning widths of any distance.

[0046] In this application, the aperture stop 5 is located on the image side of the third lens 3. The image side end of the aperture stop 5 has a stepped portion. At least a portion of the object side surface and the outer ring surface of the fourth lens rest on the stepped portion. That is, the stepped portion encloses at least a portion of the object side surface and at least a portion of the outer ring surface of the fourth lens, improving the positioning accuracy of the aperture stop 5 and the fourth lens 4. Outside the fourth lens 4, at least a portion of the adjustment assembly contacts the aperture stop 5 through the lens tube 10, which can push the aperture stop 5, thereby adjusting the position of the fourth lens 4. This corrects the imaging misalignment of adjacent line scan camera lenses, compensating for optical misalignment caused by manufacturing errors or installation deviations, ensuring the continuity and consistency of imaging in the scanning direction, avoiding imaging misalignment or ghosting, and improving scanning accuracy and efficiency. Figures 1 to 10As shown, the focal length f1 of the first lens and the focal length f of the line scan camera lens satisfy the condition: 0.85 < |f1| / f < 1.05. If |f1| / f is too small, the radius of curvature of the object side of the first lens is small, and the angle of the first lens 1 is too large under the condition of a fixed lens outer diameter, which is not conducive to lens production and will increase the astigmatism of the first lens 1, thus affecting the image sharpness. If |f1| / f is too large, the field of view of the line scan camera lens will be significantly reduced. At this time, it is necessary to increase the outer diameter of the lens to ensure the field of view, which will make the size of the line scan camera lens too large, which is not conducive to the linear array arrangement of the line scan camera lens. By controlling the range of |f1| / f between 0.85 and 1.05, the focal length of the first lens can be controlled to be close to the focal length of the line scan camera lens, which helps to achieve initial control of light and provides a good foundation for subsequent lens aberration correction and further light convergence. The first lens 1 serves as the initial lens through which light enters the line scan camera lens. The focal length ratio between the first lens 1 and the line scan camera lens not only affects the initial convergence state of the light but also directly influences the path of the light and the position of the focal point. Controlling |f1| / f can effectively control aberrations such as spherical aberration, coma, or distortion in the line scan camera lens, preventing a decrease in the imaging quality of the line scan camera lens when the object distance changes, improving the stability of the line scan camera lens, and ensuring high-quality imaging over a longer object distance.

[0047] Preferably, the line scan camera lens can image on a high-pixel line array chip 9.

[0048] like Figures 1 to 3 As shown, the focal length f2 of the second lens and the focal length f of the line scan camera lens satisfy the condition: 0.3 < |f2| / f < 0.55. If |f2| / f is too large, it will increase the higher-order aberrations of the line scan camera lens and reduce image quality. If |f2| / f is too small, the distortion of the line scan camera lens will be large and difficult to correct. By controlling |f2| / f within the range of 0.3 to 0.55, the light can be controlled to enter the subsequent lens at a suitable angle after passing through the second lens 2. This helps to improve the resolution of the line scan camera lens when using the line scan chip 9, thereby improving the image sharpness and contrast.

[0049] like Figures 1 to 3 As shown, the focal length f3 of the third lens and the focal length f of the line scan camera lens satisfy the condition: 0.15 < |f3| / f < 0.25. By controlling |f3| / f within the range of 0.15 to 0.25, the light entering the third lens 3 can be reasonably diverged. This also effectively corrects aberrations such as chromatic aberration and spherical aberration introduced by the first lens 1 and the second lens 2, ensuring that light of different wavelengths can be accurately focused on the imaging surface, improving image sharpness and resolution, and avoiding image distortion or blurring caused by improper focal length of the third lens 3.

[0050] like Figures 1 to 3 As shown, the focal length f4 of the fourth lens and the focal length f of the line scan camera lens satisfy the condition: 0.5 < |f4| / f < 0.7. If |f4| / f is too small, the line scan camera lens will be overly sensitive to optical offset, which is not conducive to offset compensation adjustment. By controlling |f4| / f within the range of 0.5 to 0.7, it can act as the last lens to significantly converge light, further optimizing the image resolution and making the image sharper and more detailed. At the same time, setting the focal length of the fourth lens 4 appropriately helps to improve the depth of field of the line scan camera lens, ensuring the sharpness of the image plane under long-distance working conditions. In addition, by precisely controlling the ratio of the focal length of the fourth lens 4 to the focal length of the line scan camera lens, the compactness of the line scan camera lens can be achieved while ensuring image quality, making more effective use of space and reducing the size of the line scan camera lens.

[0051] like Figure 2 As shown, the optical total length (TTL) and object distance (L) of a line scan camera lens must satisfy the following condition: 1.0 ≤ TTL / L ≤ 1.2. If the TTL / L value is too small, clear imaging by the line scan camera lens cannot be guaranteed. If the TTL / L value is too large, the optical total length of the line scan camera lens will be excessively compressed, reducing its imaging performance. By limiting the range of TTL / L, the line scan camera lens can achieve imaging capture with a wider scanning width while maintaining its long-distance imaging capability. Furthermore, a reasonable TTL / L range allows for a relatively compact structure in the line scan camera lens, facilitating precise imaging scanning in confined spaces, making it easier to adapt to various layouts, and improving the convenience of installation, use, and maintenance.

[0052] like Figure 1 As shown, the aperture stop 5 is spaced apart from the inner wall surface of the lens barrel 10. The outer ring surface of the aperture stop 5 has a support portion 51 and an adjustment portion 52. The support portion 51 supports the lens group, and the adjustment portion 52 is correspondingly arranged with the adjustment assembly. The adjustment portion 52 is concave towards the optical axis of the line scan camera lens relative to the support portion 51. In other words, the aperture stop 5 has an outer ring surface, which is further divided into the support portion 51 and the adjustment portion 52. The adjustment portion 52 is recessed and located away from the adjustment assembly, providing sufficient adjustment space for the adjustment assembly. The support portion 51 is spaced apart from the inner wall surface of the lens barrel 10, not in close contact, leaving space for the aperture stop 5 to move, thereby achieving eccentricity compensation.

[0053] like Figure 1As shown, the adjustment part 52 has an adjustment groove 53 and two connecting surfaces 54. The adjustment groove 53 is connected to the support part 51 through the connecting surfaces 54. At least a part of the adjustment component can extend into the adjustment groove 53 to push against the aperture stop 5. Along the optical axis, both ends of the adjustment groove 53 are connected to a connecting surface 54, that is, the two connecting surfaces 54 are used to connect the adjustment groove 53 and the support part 51, so that the adjustment part 52 divides the support part 51 into two parts. The adjustment part 52 is in the middle position and is correspondingly set with the adjustment component, so that at least a part of the adjustment component can fully extend into the adjustment groove 53 to push against the aperture stop 5, which improves the structural stability of the line scan camera lens in adjusting the eccentricity and avoids deformation of the line scan camera lens under force.

[0054] like Figures 1 to 3 As shown, the lens barrel 10 has at least one set screw adjustment hole 6 that extends through the wall thickness of the lens barrel 10. The set screw adjustment hole 6 is positioned towards the aperture stop 5. The adjustment assembly includes a set screw adjustment member, and the set screw adjustment hole 6 and the set screw adjustment member are arranged in a one-to-one correspondence. The set screw adjustment member can extend into the adjustment groove 53 to push against the aperture stop 5. The lens barrel 10 has at least one set screw adjustment hole 6, which extends through the wall thickness of the lens barrel 10 from the outside to the inside and is positioned towards the aperture stop 5. Each set screw adjustment hole 6 can be provided with a set screw adjustment member. Adjusting the set screw adjustment member to extend into the adjustment groove 53 and push against it can drive the aperture stop 5 to move as a whole, thereby causing the fourth lens 4, which is surrounded by the aperture stop 5, to move. This ensures the continuity and consistency of the image in the scanning direction, avoids image misalignment or ghosting, and improves the accuracy and efficiency of scanning. Meanwhile, the set screw adjustment hole 6 is located on the lens barrel 10 and does not directly contact the fourth lens 4. This effectively avoids interference with the light path caused by the operator during the adjustment process, reducing negative impacts on the optical performance of the line scan camera lens and preventing additional aberrations or reduced image quality. Furthermore, the set screw adjustment hole 6 simplifies the on-site commissioning process. Even in complex industrial environments, there is no need to disassemble the line scan camera lens or use complex optical adjustment equipment; fine-tuning of the line scan camera lens can be achieved solely through the set screw adjustment device. This reduces the difficulty of installation, commissioning, and use when multiple line scan camera lenses are simultaneously performing line scans, effectively lowering maintenance costs.

[0055] like Figures 1 to 3 As shown, the projection of the set screw adjustment hole 6 onto the bottom surface of the adjustment groove 53 is located within the outer periphery of the bottom surface of the adjustment groove 53. Setting the set screw adjustment hole 6 within the outer periphery of the bottom surface of the adjustment groove 53 not only ensures sufficient adjustment space between the adjustment part 52 and the lens barrel 10, preventing accidental contact with the support part 51 and affecting the axial alignment of the line scan camera lens, but also ensures a more uniform thrust on the aperture stop 5 when adjusting the set screw adjustment component, thereby achieving more precise fine-tuning. This effectively reduces the problem of incomplete fine-tuning and improves the accuracy and stability of fine-tuning.

[0056] It should be noted that line scan camera lenses can be arranged in a line array, with the line array extending in the scanning direction of the line scan camera lenses to obtain a wider scan width. Of course, line scan camera lenses can also use other scanning directions, in which case the line scan camera lenses are arranged according to the corresponding scanning direction.

[0057] like Figures 1 to 3 As shown, the lens barrel 10 is provided with at least two set screw adjustment holes 6. The line connecting the two set screw adjustment holes 6 is perpendicular to the optical axis of the line scan camera lens and perpendicular to the scanning direction of the line scan camera lens. The lens barrel 10 has at least two set screw adjustment holes 6, which are centrally symmetrically distributed with the optical axis as the central axis, and the line connecting the set screw adjustment holes 6 is perpendicular to both the optical axis and the scanning direction. Adjusting the position of the aperture stop 5 along the line connecting the two set screw adjustment holes 6 can slightly move the fourth lens 4 in that direction, achieving optical eccentricity compensation of the line scan camera lens in that direction. This prevents misalignment when taking images in that direction and facilitates bidirectional adjustment of the position of the fourth lens 4 in that direction.

[0058] It should be noted that, as Figure 12 As shown, without adjusting aperture stop 5, the eccentricity of the imaging planes of adjacent line scan camera lenses is quite severe. This can be corrected by adjusting the set screw adjustment hole 6, as... Figure 6 As shown, the eccentricity of the imaging surfaces of adjacent line scan camera lenses is compensated, and no misalignment occurs between adjacent imaging surfaces when taking images along the line connecting the two set screw adjustment holes 6, resulting in a more uniform imaging surface.

[0059] like Figures 1 to 3 As shown, from the object side to the image side of the line scan camera lens, the inner ring of aperture stop 5 extends towards the optical axis of the line scan camera lens. Aperture stop 5 is located between the third lens 3 and the fourth lens 4. The inner ring of aperture stop 5 extends towards the optical axis of the line scan camera lens, meaning the inner diameter of aperture stop 5 gradually decreases from the object side to the image side of the line scan camera lens. This effectively controls the amount of light passing through the fourth lens 4, ensuring that the light after passing through the first three lenses is focused by the aperture before entering the fourth lens 4. This achieves imaging requirements for different depths of field and resolutions, reduces stray light and halos, and improves image contrast and sharpness, thus enabling more precise management and control of light. Furthermore, since the image side end of aperture stop 5 supports and drives the fourth lens 4 to move synchronously, the image side end of aperture stop 5 is thicker. This not only improves the stability of the fourth lens 4 but also enhances the accuracy of the fourth lens 4 as it moves with aperture stop 5.

[0060] like Figures 1 to 4As shown, the line scan camera lens also includes an irregularly shaped aperture 7, which is positioned between the first lens 1 and the second lens 2. At least a portion of the inner diameter of the irregularly shaped aperture 7 is progressively widening. The irregularly shaped aperture 7 is positioned on the image side of the first lens 1, between the first lens 1 and the second lens 2. This means that the irregularly shaped aperture 7 directly participates in the initial beam adjustment after the light passes through the first lens 1, limiting and optimizing the light path after the light is focused by the first lens 1 and before further processing by the second lens 2. Unlike a conventional circular aperture, the irregularly shaped aperture 7 has a progressively widening inner diameter, meaning its inner diameter gradually increases in a certain direction. This progressively widening inner diameter design of the irregularly shaped aperture 7 can adjust the distribution of light at different field of view angles, reduce edge light loss, improve the uniformity of center and edge light, and enhance the uniform illumination and image quality of the image.

[0061] like Figures 1 to 4 As shown, the inner ring surface of the irregular aperture 7 is symmetrically arranged with respect to the optical axis of the line scan camera lens. The inner ring surface of the irregular aperture 7 includes two oppositely arranged expansion sections 71 and two oppositely arranged transition sections 72. The two ends of the transition sections 72 are connected to the two expansion sections 71, and the orientation of the two transition sections 72 is parallel to the scanning direction of the line scan camera lens. The inner ring surface of the irregular aperture 7 is symmetrically arranged with the optical axis as the axis of symmetry. The two transition sections 72 are arranged opposite each other on both sides of the optical axis along the scanning direction, while the two expansion sections 71 are distributed perpendicular to the scanning direction on both sides of the optical axis. The two ends of the expansion sections 71 are connected to the transition sections 72 on both sides of the optical axis. In other words, the two expansion sections 71 and the two transition sections 72 form a closed inner ring surface with a smooth transition. The specific shape of the inner ring surface of the irregular aperture 7 ensures that the light received by the line scan chip 9 is more uniformly distributed during the scanning process of the line scan camera lens. The transition sections 72, distributed along the scanning direction on both sides of the optical axis, allow more light to pass through, while the smooth transition of the diameter-expanding section 71 helps to uniformly diffuse the light, effectively preventing brightness attenuation at the edges of the imaging surface, avoiding significant fluctuations in imaging brightness, and improving the reliability of the scanning results. The two transition sections 72 are arranged parallel to each other along the scanning direction of the line scan camera lens, improving brightness uniformity along the scanning direction while preventing overexposure at other locations. This helps maintain the consistency of the optical performance of the line scan camera lens during scanning and reduces the need for correction steps in subsequent imaging processing. Image quality is guaranteed whether scanning is fast or the scan width is adjusted.

[0062] It should be noted that the aperture stop 5 has a minimum light transmission radius R1, which can be adjusted according to the actual application of the line scan camera lens.

[0063] like Figures 1 to 4As shown, the transition section 72 is an arc surface, with the center of the arc surface and the optical axis located on the same side of the transition section 72. The minimum light-transmitting radius R1 of the aperture stop 5 and the radius R2 of the arc surface satisfy the following relationship: R2 = 1.2 × R1. That is to say, the light is shaped by the arc surface when passing through the aperture stop 5. The minimum light-transmitting radius R1 of the aperture stop determines the narrowest part through which the light passes, while the radius R2 of the arc surface further optimizes the way the light passes through the edge of the irregular aperture stop 7. By setting the radius R2 of the arc surface to 1.2 times the minimum light-transmitting radius R1 of the aperture stop 5, it is ensured that more light can pass through in the edge area, reducing scattering and loss at the edge of the beam, thereby improving the brightness uniformity and edge sharpness of the image.

[0064] like Figures 1 to 4 As shown, the minimum light-transmitting radius R1 of the aperture stop and the shortest distance D between the two expansion sections 71 satisfy the condition: D = 0.72 × R1. By defining the relationship D = 0.72 × R1, the light-transmitting distance perpendicular to the scanning direction of the shortest distance D can be controlled, thereby controlling the shape of the area through which light passes within the aperture stop 5. This ensures a more uniform beam distribution in the center and edge areas, meeting the high requirements of line scan camera lenses for light uniformity and avoiding inconsistent brightness on the imaging surface.

[0065] like Figures 1 to 4 As shown, the minimum light-transmitting radius R1 of the aperture stop and the length B of the transition section 72 along the scanning direction satisfy the following relationship: B = 4.8 × R1. The minimum light-transmitting radius R1 of the aperture stop determines the maximum aperture value of the line scan camera lens, thus affecting the depth of field and resolution of the line scan camera lens. By defining the relationship B = 4.8 × R1, it is possible to avoid excessively large light-transmitting apertures of the irregular aperture stop 7 and excessively small light-transmitting apertures of the aperture stop 5, which would cause a large amount of light to be cut off by the aperture stop 5. This ensures that when matching the linear array chip 9, light can effectively pass through each field of view to prevent vignetting, maintaining the high resolution and sufficient depth of field of the line scan camera lens. It can also effectively reduce stray light and halo phenomena caused by the edge effect of the aperture stop 5 due to excessive differences in light-transmitting apertures, significantly improving the contrast and sharpness of the image. It can also control the distribution of light more uniformly when entering the fourth lens 4, reducing brightness differences in the image and improving the overall uniformity and quality of the image.

[0066] It should be noted that, as Figure 11 As shown, the horizontal axis represents the linear array coordinates of the line scan camera lens, and the vertical axis represents the brightness of the imaging surface. Without the irregular aperture 7, the brightness waveforms of the red, green, and blue wavelengths of the imaging surface are peak-shaped, resulting in significant inconsistencies in brightness in the acquired image. The irregular aperture 7 needs to be matched and optimized with the aperture stop 5 and the brightness waveform. By setting the irregular aperture 7 and adjusting R1, R2, D, and B, as shown... Figure 5As shown, the brightness waveform of the imaging surface is flat, and the uniformity of the imaging brightness is good.

[0067] Optionally, by adjusting the aperture stop 5 and the irregular aperture stop 7, the aperture (F# number) can be set between 6 and 15 to adapt to different depth of field and resolution requirements.

[0068] Preferably, such as Figures 1 to 10 As shown, this application provides several optical performance parameters of a line scan camera lens according to an optional embodiment. The total optical length (TTL) of the line scan camera lens is less than or equal to 70 mm, the object distance (L) is 62 mm, and the corresponding magnification of the object plane (8) is -0.8x. At this time, the half field of view (α) of the line scan camera lens is 4.7°. The imaging overlap (Q) of adjacent line scan camera lenses arranged in a linear array at an object distance of 62 mm is 0.6 mm, and the change in object height corresponding to a 0.5 mm change in object distance is less than or equal to 0.4%, ensuring that the image of the linear array chip 9 is not lost when a 3 mm change in object distance occurs. After aberration balance optimization, the MTF value of the line scan camera lens is still greater than 30% at 70 lp / mm, which has high clarity and can be adapted to linear array chips 9 with a maximum DPI of 3600. In addition, the optical distortion of the line scan camera lens is less than 0.1%, so that the image is not distorted or deformed.

[0069] Example 1

[0070] In this embodiment, a first lens 1, an irregular aperture 7, a second lens 2, a third lens 3, an aperture stop 5, and a fourth lens 4 are sequentially arranged from the object side to the image side of the line scan camera lens. The parameters of the line scan camera lens in Embodiment 1 are shown in Table 1, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0071] Table 1

[0072] Surface name Surface type Curvature radius Thickness Refractive index Dispersion coefficient Object plane 62.000 Object side of first lens Spherical 21.974 3.480 1.59 61.2 Image side of first lens Spherical Infinite 3.520 Object side of second lens Spherical 9.933 3.890 1.64 60.2 Image side of second lens Spherical Infinite 1.294 Object side of third lens Spherical -54.711 1.000 1.81 33.3 Image side of third lens Spherical 6.713 10.895 Object side of fourth lens Spherical Infinite 3.520 1.49 70.4 Image side of fourth lens Spherical -11.507 42.286

[0073] In this embodiment, f = 37.16 mm, f1 = 37.3 mm, f2 = 15.52 mm, f3 = -7.36 mm, f4 = 23.6 mm, object distance L = 62 mm, |f1| / f = 1.0, |f2| / f = 0.42, |f3| / f = 0.198, and |f4| / f = 0.635, all of which are within the aforementioned range.

[0074] In this embodiment, the MTF curve is as follows: Figure 7 As shown, the horizontal axis represents the spatial frequency per line pair per millimeter (lp / mm), and the vertical axis represents the MTF value. From... Figure 7As can be seen, this embodiment exhibits good contrast within a spatial frequency range of 70 lp / mm, and its overall resolution is high, which also means that the imaging clarity on the linear array chip 9 is high, the overall MTF decreases smoothly, and the high-frequency and low-frequency components can be effectively balanced.

[0075] In this embodiment, the optical distortion curve is as follows: Figure 8 As shown, under full field of view conditions, the maximum distortion in this embodiment is only 0.08%, the distortion correction is good, and the imaging is basically free of distortion and deformation.

[0076] Example 2

[0077] In this embodiment, a first lens, an irregular aperture, a second lens, a third lens, an aperture stop, and a fourth lens are sequentially arranged from the object side to the image side of the line scan camera lens. The parameters of the line scan camera lens in Embodiment 2 are shown in Table 2, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0078] Table 2

[0079] Surface name Surface type Curvature radius Thickness Refractive index Dispersion coefficient Object plane 68.200 Object side of first lens Spherical 24.600 3.30 1.59 61.2 Image side of first lens Spherical Infinite 3.60 Object side of second lens Spherical 10.910 4.30 1.64 60.2 Image side of second lens Spherical Infinite 1.38 Object side of third lens Spherical -60.300 0.900 1.81 33.3 Image side of third lens Spherical 7.60 11.000 Object side of fourth lens Spherical Infinite 3.87 1.49 70.4 Image side of fourth lens Spherical -13.000 48.17

[0080] In this embodiment, f = 39.7 mm, f1 = 41.76 mm, f2 = 17.07 mm, f3 = -8.327 mm, f4 = 26.667 mm, object distance L = 68.2 mm, |f1| / f = 1.05, |f2| / f = 0.43, |f3| / f = 0.21, and |f4| / f = 0.67, all of which are within the aforementioned range.

[0081] In this embodiment, the MTF curve is as follows: Figure 9 As shown, the horizontal axis represents the spatial frequency per line pair per millimeter (lp / mm), and the vertical axis represents the MTF value. From... Figure 9 As can be seen, this embodiment exhibits good contrast within a spatial frequency range of 70 lp / mm, and its overall resolution is high, which also means that the imaging clarity on the linear array chip 9 is high, the overall MTF decreases smoothly, and the high-frequency and low-frequency components can be effectively balanced.

[0082] In this embodiment, the optical distortion curve is as follows: Figure 10 As shown, under full field of view conditions, the maximum distortion in this embodiment is only -0.02%, the distortion correction is good, and the imaging is basically free of distortion and deformation.

[0083] As can be seen from the above description, the embodiments of this utility model achieve the following technical effects:

[0084] 1. The lens barrel 10 of the line scan camera lens of this application includes a lens group and an aperture stop 5. Lenses 1 to 4 are arranged sequentially from the object side to the image side. Lens 1 and 2 both have positive optical power. The object side of the first lens is convex, and its image side is flat. Similarly, the object side and image side of the second lens are also convex and flat, which helps in the initial convergence of light. Lens 3 has negative optical power. Both its object side and image side are concave, which corrects aberrations in the lens group, especially chromatic aberration and spherical aberration, ensuring accurate focusing of light of different wavelengths on the imaging surface. Lens 4 has positive optical power. Its object side is flat, and its image side is convex, which helps the line scan camera lens further converge light while maintaining image sharpness.

[0085] 2. The combination of positive and negative power lenses ensures that light is effectively converged after passing through the lens group, while controlling aberrations to achieve high-definition and high-resolution imaging. The selection and combination of these lenses facilitates clear imaging at long object distances in line scan cameras, improving their long-distance scanning capabilities. Furthermore, all optical elements are housed within the lens barrel, achieving a compact and integrated structure to meet scanning width requirements.

[0086] 3. In this application, the aperture stop 5 is located on the image side of the third lens 3. The image side end of the aperture stop 5 has a stepped portion. At least a portion of the object side surface and the outer ring surface of the fourth lens rest on the stepped portion. That is, the stepped portion encloses at least a portion of the object side surface and at least a portion of the outer ring surface of the fourth lens, improving the positioning accuracy of the aperture stop 5 and the fourth lens 4. Outside the fourth lens 4, at least a portion of the adjustment component contacts the aperture stop 5 through the lens tube 10, which can push the aperture stop 5, thereby driving the fourth lens 4 to adjust its position. This corrects the imaging eccentricity of adjacent line scan camera lenses, compensates for optical eccentricity problems caused by manufacturing errors or installation deviations, ensures the continuity and consistency of imaging in the scanning direction, avoids imaging misalignment or ghosting, and improves the accuracy and efficiency of scanning. Obviously, the embodiments described above are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.

[0087] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0088] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0089] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A line scan camera lens, characterized in that, include: The lens group, from the object side to the image side of the line scan camera lens, includes a first lens (1) to a fourth lens (4) in sequence. The first lens (1) has positive optical power, the object side of the first lens is convex, and the image side of the first lens is flat. The second lens (2) has positive optical power, the object side of the second lens is convex, and the image side of the second lens is flat. The third lens (3) has negative optical power, and both the object side and the image side of the third lens are concave. The fourth lens (4) has positive optical power, the object side of the fourth lens is flat, and the image side of the fourth lens is convex. An aperture stop (5) is located on the image side of the third lens (3). The image side end of the aperture stop (5) has a stepped portion. The object side of the fourth lens and the outer ring surface of the fourth lens (4) are both in contact with the stepped portion. The lens barrel (10) is housed within the lens barrel (10); An adjustment assembly, at least a portion of which can pass through the lens barrel (10) and push against the aperture stop (5) so that the aperture stop (5) drives the fourth lens (4) to adjust its position.

2. The line scan camera lens according to claim 1, characterized in that, The focal length f1 of the first lens and the focal length f of the line scan camera lens satisfy the following condition: 0.85 < |f1| / f < 1.

05.

3. The line scan camera lens according to claim 1, characterized in that, The focal length f2 of the second lens and the focal length f of the line scan camera lens satisfy the following condition: 0.3 < |f2| / f < 0.

55.

4. The line scan camera lens according to claim 1, characterized in that, The focal length f3 of the third lens and the focal length f of the line scan camera lens satisfy the following condition: 0.15 < |f3| / f < 0.

25.

5. The line scan camera lens according to claim 1, characterized in that, The focal length f4 of the fourth lens and the focal length f of the line scan camera lens satisfy the following condition: 0.5 < |f4| / f < 0.

7.

6. The line scan camera lens according to claim 1, characterized in that, The total optical length TTL of the line scan camera lens and the object distance L of the line scan camera lens satisfy the following condition: 1.0 ≤ TTL / L ≤ 1.

2.

7. The line scan camera lens according to any one of claims 1 to 6, characterized in that, The aperture stop (5) is spaced apart from the inner wall surface of the lens barrel (10). The outer ring surface of the aperture stop (5) has a support part (51) and an adjustment part (52). The support part (51) supports the lens group, and the adjustment part (52) is correspondingly arranged with the adjustment component. The adjustment part (52) is concave to the optical axis of the line scan camera lens relative to the support part (51).

8. The line scan camera lens according to claim 7, characterized in that, The adjustment part (52) has an adjustment groove (53) and two connecting surfaces (54). The adjustment groove (53) is connected to the support part (51) through the connecting surfaces (54). At least a portion of the adjustment component can extend into the adjustment groove (53) to push against the aperture stop (5).

9. The line scan camera lens according to claim 8, characterized in that, The lens barrel (10) has at least one top screw adjustment hole (6) that extends through the wall thickness of the lens barrel (10). The top screw adjustment hole (6) is arranged facing the aperture stop (5). The adjustment assembly includes a top screw adjustment member. The top screw adjustment hole (6) and the top screw adjustment member are arranged in a one-to-one correspondence. The top screw adjustment member can extend into the adjustment groove (53) to push against the aperture stop (5).

10. The line scan camera lens according to claim 9, characterized in that, The projection of the set screw adjustment hole (6) on the bottom surface of the adjustment groove (53) is located within the outer periphery of the bottom surface of the adjustment groove (53).

11. The line scan camera lens according to claim 9, characterized in that, The lens barrel (10) is provided with at least two set screw adjustment holes (6), and the line connecting the two set screw adjustment holes (6) is perpendicular to the optical axis of the line scan camera lens and perpendicular to the scanning direction of the line scan camera lens.

12. The line scan camera lens according to any one of claims 1 to 6, characterized in that, From the object side to the image side of the line scan camera lens, the inner ring of the aperture stop (5) extends in a direction close to the optical axis of the line scan camera lens.

13. The line scan camera lens according to any one of claims 1 to 6, characterized in that, The line scan camera lens also includes an irregular aperture (7), which is disposed between the first lens (1) and the second lens (2), and at least a portion of the irregular aperture (7) has a gradually increasing inner diameter.

14. The line scan camera lens according to claim 13, characterized in that, The inner ring surface of the irregular aperture (7) is symmetrically arranged with respect to the optical axis of the line scan camera lens. The inner ring surface of the irregular aperture (7) includes two oppositely arranged expansion sections (71) and two oppositely arranged transition sections (72). The two ends of the transition section (72) are respectively connected to the two expansion sections (71). The arrangement direction of the two transition sections (72) is parallel to the scanning direction of the line scan camera lens.

15. The line scan camera lens according to claim 14, characterized in that, The transition section (72) is an arc surface, and the center of the arc surface and the optical axis are located on the same side of the transition section (72). The minimum light transmission radius R1 of the aperture stop and the radius R2 of the arc surface satisfy the following condition: R2 = 1.2 × R1.

16. The line scan camera lens according to claim 14, characterized in that, The minimum light-transmitting radius R1 of the aperture stop and the shortest distance D between the two expansion sections (71) satisfy: D = 0.72 × R1.

17. The line scan camera lens according to claim 14, characterized in that, The minimum light-transmitting radius R1 of the aperture stop and the length B of the transition section (72) along the scanning direction satisfy the following condition: B = 4.8 × R1.

Images