Optical imaging structure of line scanning lens
By designing an optical imaging structure of a linear scan lens, including front lens, aperture and rear lens, the problems of large target lenses with large distortion and uneven illumination are solved, and the optical imaging effect with high resolution and high relative illumination is achieved.
Patent Information
- Application Number
- CN202422178052.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-05
- Publication Date
- 2025-06-27
- Estimated Expiration
- 2034-09-05
AI Technical Summary
The existing large target lenses have distortion problems, low illuminance uniformity, and dark surroundings of the lens, which cannot meet the needs of use.
An optical imaging structure for linear scanning lenses is designed, including front group lenses, apertures and rear group lenses arranged in sequence along the direction of light incident. By selecting glass with different dispersion coefficients and reasonably distribute the optical power, the thickness and air gap distance of each lens are achieved, while reducing distortion and improving resolution and relative illumination are achieved.
It realizes the reduction of distortion under large target surface conditions, improves resolution and relative illuminance, and has good illumination uniformity, effectively solving the problem of darker surroundings of the lens in the prior art.
Smart Images
Figure CN223038241U_ABST
Abstract
Description
Technical Field:
[0001] The utility model belongs to the technical field of lenses, and particularly relates to an optical imaging structure of a line-scanning lens. Background Art:
[0002] In the existing research on optical lenses, most large-format lenses have distortion problems, and the illuminance uniformity of some lenses is low, with the periphery of the lens being darker, unable to meet the usage requirements. Content of the Utility Model:
[0003] The utility model makes improvements to the above problems existing in the prior art, that is, the technical problem to be solved by the utility model is to provide an optical imaging structure of a line-scanning lens.
[0004] To achieve the above object, the technical solution adopted by the utility model is: an optical imaging structure of a line-scanning lens, which includes a front group of lenses, a diaphragm, and a rear group of lenses arranged in sequence along the light incident direction. The front group of lenses includes a positive meniscus lens with positive optical power, a biconvex lens I with positive optical power, and a biconcave lens I with positive optical power arranged in sequence from the object plane to the image plane along the light incident direction; the rear group of lenses includes a biconcave lens II with negative optical power, a biconvex lens II with negative optical power, and a biconvex lens III with positive optical power arranged in sequence from the object plane to the image plane along the light incident direction; the biconvex lens I and the biconcave lens I form a cemented lens group I, and the biconcave lens II and the biconvex lens II form a cemented lens group II.
[0005] Further, both the cemented lens group I and the cemented lens group II are glass doublets; the positive meniscus lens and the biconvex lens III are both glass spherical lenses.
[0006] Further, the air gap L1 between the positive meniscus lens and the biconvex lens I with positive optical power satisfies: 6 < L1 < 8; the air gap L2 between the biconcave lens I and the diaphragm satisfies: 1 < L2 < 4; the air gap L3 between the diaphragm and the biconcave lens II satisfies: 13 < L3 < 16; the air gap L4 between the biconvex lens II and the biconvex lens III satisfies: 2 < L4 < 5.
[0007] Further, the focal length Fa of the front group of lenses and the focal length F of the lens satisfy the following relationship: 1.0 < Fa / F < 1.4; the focal length Fb of the rear group of lenses and the focal length F of the lens satisfy the following relationship: 0.9 < Fb / F < 1.2.
[0008] Further, the focal length F1 of the cemented lens group I and the focal length F2 of the cemented lens group II satisfy the following relationship: 1 < F1 / F2 < 1.5; the focal length F3 of the positive meniscus lens and the focal length F4 of the biconvex lens III satisfy the following relationship: 1.2 < F3 / F4 < 1.5.
[0009] Furthermore, the focal length F of the lens and the back focal length BFL satisfy the following relationship: 1.5 < F / BFL < 2.0.
[0010] Furthermore, the sum of the central thicknesses of the positive meniscus lens and the biconvex lens III on the optical axis is ∑CT, and the maximum distance between the object side surface of the positive meniscus lens and the image side surface of the biconvex lens III is TTL, and the following relational expression is satisfied: 0.1 < ∑CT / TTL < 0.5.
[0011] Furthermore, the curvature radii of the object side surface and the image side surface of the biconvex lens III are equal.
[0012] Furthermore, the diaphragm diameter D1 and the target surface diameter D2 satisfy the following relationship: 0.3 < D1 / D2 < 0.8; the total optical length T of the lens and the target surface diameter D2 satisfy the following relationship: 3.5 < T / D2 < 5.5.
[0013] Furthermore, the glass refractive index N1 and the dispersion coefficient V1 of the positive meniscus lens and the glass refractive index N2 and the dispersion coefficient V2 of the biconvex lens III satisfy the following relationships: 1.7 < N1 < N2 < 2.2, V1 ≥ 45, V2 ≥ 25; the glass refractive index N3 and the dispersion coefficient V3 of the biconvex lens I and the glass refractive index N4 and the dispersion coefficient V4 of the biconvex lens II satisfy the following relationships: 1.65 < N3 < N4 < 1.7, V3 ≥ 55, V4 ≥ 50; the glass refractive index N5 and the dispersion coefficient V5 of the biconcave lens I and the glass refractive index N6 and the dispersion coefficient V6 of the biconcave lens II satisfy the following relationships: 1.6 < N5 < N6 < 1.75, V5 ≥ 30, V6 ≥ 25.
[0014] Compared with the prior art, the present utility model has the following effects: The present utility model is reasonably designed. While achieving a large target surface, it can reduce distortion, has high resolution, high relative illuminance, good uniformity, and effectively solves the technical problems of large distortion of the large target surface lens, uneven overall illuminance, and darker periphery of the lens in the prior art. Description of the Drawings:
[0015] Figure 1 is the optical path diagram of the embodiment of the present utility model;
[0016] Figure 2 is the interface form diagram of the MTF curve diagram of the embodiment of the present utility model;
[0017] Figure 3 is the interface form diagram of the field curvature and distortion of the embodiment of the present utility model;
[0018] Figure 4 is the interface form diagram of the relative illuminance of the embodiment of the present utility model.
[0019] In the figure:
[0020] 1 - positive meniscus lens; 2 - biconvex lens I; 3 - biconcave lens I; 4 - aperture stop; 5 - biconcave lens II; 6 - biconvex lens II; 7 - biconvex lens III. Specific embodiments:
[0021] The following further describes the present utility model in detail in conjunction with the accompanying drawings and specific embodiments.
[0022] In the description of the present utility model, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present utility model, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present utility model.
[0023] As Figure 1 shown, an optical imaging structure of a line scan lens of the present utility model is used to solve the technical problems of large distortion of the large target surface lens, uneven overall illuminance, and darker periphery of the lens in the prior art. Specifically: The optical imaging structure of the lens includes a front group of lenses, an aperture stop 4, and a rear group of lenses arranged in sequence along the light incident direction. The aperture stop is located between the front group of lenses and the rear group of lenses; the front group of lenses includes a positive meniscus lens 1 with positive optical power, a biconvex lens I 2 with positive optical power, and a biconcave lens I 3 with positive optical power arranged in sequence from the object surface to the image surface along the light incident direction; the rear group of lenses includes a biconcave lens II 5 with negative optical power, a biconvex lens II 6 with negative optical power, and a biconvex lens III 7 with positive optical power arranged in sequence from the object surface to the image surface along the light incident direction; the biconvex lens I and the biconcave lens I form a cemented lens group I, and the biconcave lens II and the biconvex lens II form a cemented lens group II.
[0024] In this embodiment, both the cemented lens group I and the cemented lens group II are glass doublets; the positive meniscus lens and the biconvex lens III are both glass spherical lenses. Each lens adopts a spherical design, with good process performance, low material cost, and the structure includes two cemented lens groups, which convert larger assembly tolerances into smaller cemented tolerances, improving the assembly yield and reducing the loss cost.
[0025] In this embodiment, the air gap L1 between the positive meniscus lens and the biconvex lens I with positive optical power satisfies: 6 < L1 < 8. Preferably, the air gap between the positive meniscus lens and the biconvex lens I with positive optical power is L1 = 7.610.
[0026] In this embodiment, the air gap L2 between the biconcave lens I and the diaphragm satisfies: 1 < L2 < 4. Preferably, the air gap between the biconcave lens I and the diaphragm is L2 = 2.621.
[0027] In this embodiment, the air gap L3 between the diaphragm and the biconcave lens II satisfies: 13 < L3 < 16. Preferably, the air gap between the diaphragm and the biconcave lens II is L3 = 14.717.
[0028] In this embodiment, the air gap L4 between the biconvex lens II and the biconvex lens III satisfies: 2 < L4 < 5. Preferably, the air gap between the biconvex lens II and the biconvex lens III is L4 = 3.407.
[0029] In this embodiment, the focal length Fa of the front lens group and the focal length F of the lens satisfy the following relationship: 1.0 < Fa / F < 1.4; preferably, Fa / F = 1.195.
[0030] In this embodiment, the focal length Fb of the rear lens group and the focal length F of the lens satisfy the following relationship: 0.9 < Fb / F < 1.2; preferably, Fb / F = 1.034.
[0031] In this embodiment, the focal length F1 of the cemented lens group I and the focal length F2 of the cemented lens group II satisfy the following relationship: 1 < F1 / F2 < 1.5; preferably, F1 / F2 = 1.267.
[0032] In this embodiment, the focal length F3 of the positive meniscus lens and the focal length F4 of the biconvex lens III satisfy the following relationship: 1.2 < F3 / F4 < 1.5; preferably, F3 / F4 = 1.213.
[0033] In this embodiment, the focal length F of the lens and the back focal length BFL satisfy the following relationship: 1.5 < F / BFL < 2.0; preferably, F / BFL = 1.672.
[0034] In this embodiment, the sum of the central thicknesses of the positive meniscus lens and the biconvex lens III on the optical axis is ∑CT, and the maximum distance between the object side of the positive meniscus lens and the image side of the biconvex lens III is TTL, and the following relational expression is satisfied: 0.1 < ∑CT / TTL < 0.5; preferably, ∑CT / TTL = 0.351.
[0035] In this embodiment, the curvature radii of the object side and the image side of the biconvex lens III are equal, and the curvature radius is 155.413.
[0036] In this embodiment, the diaphragm diameter D1 and the target surface diameter D2 satisfy the following relationship: 0.3 < D1 / D2 < 0.8; preferably, D1 / D2 = 0.637.
[0037] In this embodiment, the total optical length T of the lens and the target surface diameter D2 satisfy the following relationship: 3.5 < T / D2 < 5.5. Preferably, T / D2 = 4.247.
[0038] In this embodiment, the working wavelength band of the lens is 589 nm.
[0039] In this embodiment, the glass refractive index N1 and dispersion coefficient V1 of the positive meniscus lens and the glass refractive index N2 and dispersion coefficient V2 of the biconvex lens III satisfy the following relationship: 1.7 < N1 < N2 < 2.2, V1 ≥ 45, V2 ≥ 25. Preferably, N1 = 1.804, N2 = 2.003, V1 = 46.57, V2 = 28.321.
[0040] In this embodiment, the glass refractive index N3 and dispersion coefficient V3 of the biconvex lens I and the glass refractive index N4 and dispersion coefficient V4 of the biconvex lens II satisfy the following relationship: 1.65 < N3 < N4 < 1.7, V3 ≥ 55, V4 ≥ 50. Preferably, N3 = 1.678, N4 = 1.692, V3 = 55.52, V4 = 54.54.
[0041] In this embodiment, the glass refractive index N5 and dispersion coefficient V5 of the biconcave lens I and the glass refractive index N6 and dispersion coefficient V6 of the biconcave lens II satisfy the following relationship: 1.6 < N5 < N6 < 1.75, V5 ≥ 30, V6 ≥ 25. Preferably, N5 = 1.648, N6 = 1.741, V5 = 33.84, V6 = 27.76.
[0042] In this embodiment, the lens parameters output by the optical imaging structure are as follows:
[0043] (1) Target surface diameter: 28.672 mm;
[0044] (2) Focal length: 84.77;
[0045] (3) Relative aperture: F2.8;
[0046] (4) Working wavelength: 589 nm;
[0047] (5) Object distance: 538.23;
[0048] (6) Distortion: 0.10%;
[0049] (7) Relative illumination: > 98%;
[0050] (8) Modulation transfer function: greater than 0.5 for 35 line pairs.
[0051] In this embodiment, as shown in Table 1 below, when the working distance is 538.23 mm, the parameters of the lens of the present utility model are given. The numbers from 0 to 12 represent the parameters of each lens surface from the object surface to the image surface.
[0052] Radius of curvature Thickness Material Object surface Infinity 538.23 1 56.081 6.186 H-ZLAF50 2 201.070 7.610 3 31.767 6.686 H-LAK5A 4 -675.365 7.078 H-ZF1 5 21.127 2.621 Diaphragm Infinity 14.717 7 -25.757 4.870 H-ZF50 8 227.336 9.728 H-LAK2A 9 -35.761 3.407 10 155.413 8.159 H-ZLAF92 11 -155.413 50.709 Image surface Infinity -
[0053] Table 1
[0054] As Figure 2 is the interface form diagram of the MTF curve graph of the present utility model. It can be seen that the imaging quality of this line scan lens is clear and uniform, with high resolution. As Figure 3 is the interface form diagram of the field curvature and distortion of the present utility model. It can be seen that this line scan lens has the advantage of low distortion. As Figure 4 is the interface form diagram of the relative illuminance of the present utility model. It can be seen that the relative illuminance of this line scan lens is overall uniform, effectively avoiding the disadvantage that some lenses on the market are darker around the edges.
[0055] The advantages of the present utility model are as follows:
[0056] 1. The present utility model is evolved from a double Gauss structure, and a positive meniscus lens, a double convex lens I, a double concave lens I, a diaphragm, a double concave lens II, a double convex lens II, and a double convex lens III are sequentially arranged along the light incident direction. By selecting glasses with different dispersion coefficients, reasonably distributing the optical power, and the thicknesses of each lens and the air gap distance, while achieving a large target surface, it can reduce distortion, have high resolution, high relative illuminance, and good uniformity;
[0057] 2. Each lens of the present utility model adopts a spherical surface design, with good process performance, low material cost, and the structure contains two cemented lens groups, converting larger assembly tolerances into smaller cemented tolerances, improving the assembly yield rate and reducing the loss cost;
[0058] 3. For the line scan lens of the present utility model, its working distance is <600 mm, the working wavelength is in the range of 440 - 656 nm, the optical distortion is only <0.1%, and the relative illuminance reaches >98%.
[0059] If the present utility model discloses or involves components or structural parts that are fixedly connected to each other, then, unless otherwise stated, the fixed connection can be understood as: a detachable fixed connection (such as using bolts or screws for connection), or it can also be understood as: a non-detachable fixed connection (such as riveting, welding). Of course, the mutual fixed connection can also be replaced by an integral structure (such as being integrally formed by casting process) (except when it is obviously impossible to adopt the integral forming process).
[0060] In addition, unless otherwise stated, the terms used to represent positional relationships or shapes in any of the technical solutions disclosed in the above-mentioned present utility model include states or shapes that are approximate, similar, or close thereto.
[0061] Any component provided by the present utility model can either be assembled from a plurality of individual components or be a single component manufactured by an integral forming process.
[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model and not to limit them; although the present utility model has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that it is still possible to modify the specific implementation manners of the present utility model or perform equivalent replacements for some technical features; without departing from the spirit of the technical solutions of the present utility model, they should all be covered within the scope of the technical solutions claimed by the present utility model.
Claims
1. An optical imaging structure of a line scan lens, characterized in that: It includes a front lens group, a diaphragm, and a rear lens group arranged in sequence along the light incident direction. The front lens group includes a positive meniscus lens with positive optical power, a double convex lens I with positive optical power, and a double concave lens I with positive optical power arranged in sequence from the object plane to the image plane along the light incident direction; the rear lens group includes a double concave lens II with negative optical power, a double convex lens II with negative optical power, and a double convex lens III with positive optical power arranged in sequence from the object plane to the image plane along the light incident direction; the double convex lens I and the double concave lens I form a cemented lens group I, and the double concave lens II and the double convex lens II form a cemented lens group II.
2. The optical imaging structure of a line scan lens according to claim 1, characterized in that: Both the cemented lens group I and the cemented lens group II are glass doublets; the positive meniscus lens and the double convex lens III are both glass spherical lenses.
3. The optical imaging structure of a line scan lens according to claim 1, characterized in that: The air gap L1 between the positive meniscus lens and the double convex lens I with positive optical power satisfies: 6 < L1 < 8; the air gap L2 between the double concave lens I and the diaphragm satisfies: 1 < L2 < 4; the air gap L3 between the diaphragm and the double concave lens II satisfies: 13 < L3 < 16; the air gap L4 between the double convex lens II and the double convex lens III satisfies: 2 < L4 < 5.
4. The optical imaging structure of a line scan lens according to claim 2, characterized in that: The focal length Fa of the front lens group and the focal length F of the lens satisfy the following relationship: 1.0 < Fa / F < 1.4; the focal length Fb of the rear lens group and the focal length F of the lens satisfy the following relationship: 0.9 < Fb / F < 1.
2.
5. The optical imaging structure of a line scan lens according to claim 2, characterized in that: The focal length F1 of the cemented lens group I and the focal length F2 of the cemented lens group II satisfy the following relationship: 1 < F1 / F2 < 1.5; the focal length F3 of the positive meniscus lens and the focal length F4 of the double convex lens III satisfy the following relationship: 1.2 < F3 / F4 < 1.
5.
6. The optical imaging structure of a line scan lens according to claim 1, characterized in that: The focal length F of the lens and the back focal length BFL satisfy the following relationship: 1.5 < F / BFL < 2.
0.
7. The optical imaging structure of a line scan lens according to claim 1, characterized in that: The sum of the central thicknesses of the positive meniscus lens and the double convex lens III on the optical axis is ∑CT, and the maximum distance between the object side surface of the positive meniscus lens and the image side surface of the double convex lens III is TTL, and they satisfy the following relational expression: 0.1 < ∑CT / TTL < 0.
5.
8. The optical imaging structure of a line scan lens according to claim 1, characterized in that: The curvature radii of the object side surface and the image side surface of the double convex lens III are equal.
9. The optical imaging structure of a line scan lens according to claim 1, characterized in that: The diaphragm diameter D1 and the target surface diameter D2 satisfy the following relationship: 0.3 < D1 / D2 < 0.8; the overall optical length T of the lens and the target surface diameter D2 satisfy the following relationship: 3.5 < T / D2 < 5.
5.
10. The optical imaging structure of a line scan lens according to claim 1, characterized in that: The glass refractive index N1 and dispersion coefficient V1 of the positive meniscus lens and the glass refractive index N2 and dispersion coefficient V2 of the double convex lens III satisfy the following relationships: 1.7 < N1 < N2 < 2.2, V1 ≥ 45, V2 ≥ 25; the glass refractive index N3 and dispersion coefficient V3 of the double convex lens I and the glass refractive index N4 and dispersion coefficient V4 of the double convex lens II satisfy the following relationships: 1.65 < N3 < N4 < 1.7, V3 ≥ 55, V4 ≥ 50; the glass refractive index N5 and dispersion coefficient V5 of the double concave lens I and the glass refractive index N6 and dispersion coefficient V6 of the double concave lens II satisfy the following relationships: 1.6 < N5 < N6 < 1.75, V5 ≥ 30, V6 ≥ 25.