Image-side telecentric lens and optical device for wide spectrum imaging
By designing a wide spectrum imaging square telecentric lens of eleven spherical glass lenses, the problem of difficulty in achieving full focus and thermal defocusing in high and low temperature environments in the existing technology is solved, and the imaging effect of high resolution and clarity is achieved.
Patent Information
- Application Number
- CN202420812961.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-18
- Publication Date
- 2025-04-11
- Estimated Expiration
- 2034-04-18
AI Technical Summary
Existing wide spectrum imaging lenses are difficult to achieve a full focus design under wide spectrum conditions, and are prone to thermal defocusing in high and low temperature environments, resulting in blurred images and low imaging resolution.
A wide spectrum imaging square telecentric lens was designed, using eleven spherical glass lenses. Through reasonable power distribution and glued lens design, chromatic aberration and thermal defocusing are reduced, so that the telecentricity of each band is less than 0.5 degrees.
The uniform focus of all bands under wide spectral conditions is achieved, reducing chromatic aberration and thermal defocusing, improving imaging resolution and image clarity, and able to output high-definition images at ambient temperatures of -40°C to 80°C.
Smart Images
Figure CN222748774U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of wide-spectrum imaging lenses, in particular to an image-side telecentric lens and optical equipment for wide-spectrum imaging. Background Art
[0002] For conventional lenses, under the conditions of wide-spectrum imaging, the optimal focal positions corresponding to each band vary greatly, making it difficult to achieve parfocal design. In addition, thermal defocusing usually occurs in high and low temperature environments, which can easily cause the image to become blurred. In order to correct high-level chromatic aberration, wide-spectrum imaging lenses mostly use aspherical glass lenses or multiple ultra-low dispersion glass lenses, which are generally expensive. Conventional telecentric lenses usually find it difficult to maintain consistent telecentricity in each band. Due to the existence of chromatic aberration, the imaging resolution of wide-spectrum imaging lenses is generally not high. Utility Model Content
[0003] In view of this, an object of the present invention is to provide an image-space telecentric lens for wide-spectrum imaging, which can solve at least one technical problem mentioned in the background technology.
[0004] According to one aspect of the utility model, there is provided an image-side telecentric lens for wide spectrum imaging, comprising: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, an aperture, a seventh lens, an eighth lens, a ninth lens, a tenth lens, and an eleventh lens in order from the object side to the image side along the optical axis.
[0005] The first lens has a negative refractive power, a flat object side surface, and a concave image side surface;
[0006] The second lens has a negative refractive power, a concave object side surface, and a concave image side surface;
[0007] The third lens has positive refractive power, an object side surface is convex, and an image side surface is convex;
[0008] The fourth lens has positive refractive power, an object side surface is convex, and an image side surface is convex;
[0009] The fifth lens has positive refractive power, and its object side surface is convex; its image side surface is convex;
[0010] The sixth lens has negative refractive power, and its object side surface is concave, and its image side surface is concave;
[0011] The seventh lens has positive refractive power, an object side surface is convex, and an image side surface is convex;
[0012] The eighth lens has negative refractive power, and its object side surface is concave and its image side surface is concave;
[0013] The ninth lens has positive refractive power, an object side surface is convex, and an image side surface is convex;
[0014] The tenth lens has negative refractive power, the object side surface is convex, and the image side surface is concave;
[0015] The eleventh lens has positive refractive power, an object side surface is convex, and an image side surface is convex.
[0016] In the above technical solutions, the system adopts spherical glass lens design, which not only meets the use requirements of wide spectrum imaging, but also reduces the manufacturing cost. The lens meets the image telecentric design requirements, and the telecentricity of each band is less than 0.5 degrees.
[0017] In some embodiments, the lens satisfies the following relationship:
[0018] f 1 <0
[0019] 1.4 <nd 1 <1.6
[0020] 69<Vd 1 <71
[0021] In the formula, f 1 is the focal length of the first lens; nd 1 is the refractive index of the first lens; Vd 1 is the Abbe number of the first lens.
[0022] In the above technical solution, the above setting is not only conducive to reducing chromatic aberration, but also conducive to reducing the front port diameter of the system.
[0023] In some embodiments, the lens satisfies the following relationship:
[0024] 1.8 <nd 11 <1.9
[0025] 39<Vd 11 <41
[0026] Where, nd 11 is the refractive index of the eleventh lens; Vd 1 is the Abbe number of the eleventh lens.
[0027] In the above technical solution, the above setting is conducive to reducing telecentricity, meeting the image-side telecentricity design requirements, and achieving that the telecentricity of each band is less than 0.5 degrees.
[0028] The lens satisfies the following relationship:
[0029] dn 5 / Dt<0
[0030] In the formula, dn 5 is the refractive index temperature coefficient of the fifth lens.
[0031] In the above technical solution, the above setting is conducive to reducing the thermal defocus of the system and ensuring normal imaging of the system in high and low temperature environments. The thermal defocus generated is reduced, the image clarity is improved, and high-definition images can be output at an ambient temperature of -40°C to 80°C.
[0032] In some embodiments, the lens satisfies the following relationship:
[0033] dn 9 / Dt<0
[0034] In the formula, dn 9 is the refractive index temperature coefficient of the ninth lens
[0035] In the above technical solution, the above setting is conducive to reducing the thermal defocus of the system and ensuring normal imaging of the system in high and low temperature environments. The thermal defocus generated is reduced, the image clarity is improved, and high-definition images can be output at an ambient temperature of -40°C to 80°C.
[0036] In some embodiments, the second lens and the third lens are glued together to form a first glued lens; and the first glued lens satisfies the following relationship:
[0037] |Vd 正 -Vd 负 |>32
[0038] Where Vd 正 is the Abbe number of the positive lens, Vd 负 is the Abbe number of the negative lens.
[0039] In the above technical solution, the above setting is of great help in correcting chromatic aberration and greatly reduces the dispersion focus shift.
[0040] In some embodiments, the fifth lens and the sixth lens are cemented to form a second cemented lens; and the second cemented lens satisfies the following relationship:
[0041] |Vd 正 -Vd 负 |>32
[0042] Where Vd 正 is the Abbe number of the positive lens, Vd 负 is the Abbe number of the negative lens.
[0043] In the above technical solution, the above setting is of great help in correcting chromatic aberration and greatly reduces the dispersion focus shift.
[0044] In some embodiments, the eighth lens and the ninth lens are cemented to form a third cemented lens; and the third cemented lens satisfies the following relationship:
[0045] |Vd 正 -Vd 负 |>32
[0046] Where Vd 正 is the Abbe number of the positive lens, Vd 负 is the Abbe number of the negative lens.
[0047] In the above technical solution, the above setting is of great help in correcting chromatic aberration and greatly reduces the dispersion focus shift.
[0048] According to another aspect of the utility model, an optical device is provided, comprising the above-mentioned image-space telecentric lens for wide-spectrum imaging.
[0049] In the above technical solutions, the system adopts spherical glass lens design, which not only meets the use requirements of wide spectrum imaging, but also reduces the manufacturing cost. The lens meets the image telecentric design requirements, and the telecentricity of each band is less than 0.5 degrees. BRIEF DESCRIPTION OF THE DRAWINGS
[0050] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0051] Figure 1 It is a structural schematic diagram of one embodiment of the image-side telecentric lens for wide spectrum imaging of the utility model;
[0052] Figure 2 This is an MTF curve diagram of one embodiment of the image-side telecentric lens for wide spectrum imaging of the utility model;
[0053] Figure 3 This is a schematic diagram of polychromatic light focus shift of one embodiment of the image-side telecentric lens for wide spectrum imaging of the utility model;
[0054] Figure 4 It is a lens CRA schematic diagram of one embodiment of the image-side telecentric lens for wide spectrum imaging of the utility model. DETAILED DESCRIPTION
[0055] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is particularly noted that the following embodiments are only used to illustrate the present invention, but do not limit the scope of the present invention. Similarly, the following embodiments are only partial embodiments of the present invention rather than all embodiments. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0056] The utility model provides an image-space telecentric lens for wide-spectrum imaging, which can solve at least one technical problem mentioned in the background technology.
[0057] Embodiment 1
[0058] See also Figure 1 , an image-side telecentric lens for wide spectrum imaging, comprising: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, an aperture ST, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, and an eleventh lens L11 in order from the object side OBJ to the image side IMA along the optical axis. The first lens L1 has a negative refractive power, the object side surface is a plane, and the image side surface is a concave surface; the second lens L2 has a negative refractive power, the object side surface is a concave surface, and the image side surface is a concave surface; the third lens L3 has a positive refractive power, the object side surface is a convex surface, and the image side surface is a convex surface; the fourth lens L4 has a positive refractive power, the object side surface is a convex surface, and the image side surface is a convex surface; the fifth lens L5 has a positive refractive power, the object side surface is a convex surface; the image side surface is a convex surface; the sixth lens L6 has a negative refractive power, the object side surface is a convex surface, and the image side surface is a convex surface. The seventh lens L7 has positive refractive power, the object side is convex, and the image side is convex; the eighth lens L8 has negative refractive power, the object side is concave, and the image side is concave; the ninth lens L9 has positive refractive power, the object side is convex, and the image side is convex; the tenth lens L10 has negative refractive power, the object side is convex, and the image side is concave; the eleventh lens L11 has positive refractive power, the object side is convex, and the image side is convex. The lens uses eleven spherical lenses in total, realizing an image-side telecentric lens with a focal length of 20mm, a working band of 400nm-1000nm, and a maximum target size of up to 15mm. The system's closest working object distance is 0.5m, and the size of the back focus can be changed through the adjustment ring at the rear end of the structure to achieve focusing at different object distances. The system's overall dimensions are φ30mm*55.2mm, and the maximum aperture is φ19.8mm. The maximum chief ray angle of the system is less than 0.5 degrees, the absolute value of optical distortion is less than 3%, and the relative illumination is greater than 85%.
[0059] The specific optical parameters of the lens are shown in the following table:
[0060] Surface number surface Radius of curvature Thickness interval Material Refractive Index Abbe number focal length 1 First lens endless 1.60 Glass 1.50 70.00 -25.70 2 12.40 5.17 3 Second lens -26.90 2.00 Glass 1.85 24.00 -12.10 4 The third lens 16.40 7.70 Glass 1.90 40.00 14.30 5 -39.20 1.34 6 The fourth lens 28.50 5.20 Glass 1.90 21.00 24.90 7 -93.50 3.50 8 Fifth lens 12.30 4.80 Glass 1.60 68.00 15.90 9 The sixth lens -33.40 1.60 Glass 1.70 30.00 -10.90 10 10.10 1.50 11 Aperture endless 2.60 12 Seventh lens 83.50 3.45 Glass 1.62 63.00 24.00 13 -17.50 3.00 14 The eighth lens -9.70 1.40 Glass 1.60 36.00 -9.90 15 The ninth lens 16.50 5.60 Glass 1.60 68.00 15.00 16 -16.50 5.50 17 Tenth lens 51.40 1.50 Glass 1.60 46.00 -73.70 18 22.20 1.50 19 Eleventh lens 34.20 5.00 Glass 1.90 40.00 20.40 20 -34.20 6.00 21 Image plane endless
[0061] In this embodiment, Figure 2 is the MTF diagram of the lens, Figure 3 is the dispersion focus shift map of the lens, Figure 4 is the CRA diagram of the lens; Figure 2-4 It can be seen that the contrast of the whole field of view is greater than 0.3 at 70lp / mm, the dispersion focus shift is less than 33um, and the maximum chief ray angle is less than 0.5 degrees. It can be seen that the lens of this embodiment has good imaging quality.
[0062] The systems of this embodiment all adopt spherical glass lens design, which not only meets the use requirements of wide-spectrum imaging, but also reduces manufacturing costs. This embodiment meets the image-side telecentric design requirements, and the telecentricity of each band is less than 0.5 degrees. This embodiment adopts a reasonable optical focal length distribution to reduce the dispersion focus shift. This embodiment meets the imaging resolution requirements and makes the imaging quality from the center to the edge more uniform. This embodiment adopts an optical athermal design, which can output high-definition images at an ambient temperature of -40°C to 80°C.
[0063] The systems of this embodiment all adopt spherical glass lens design, which not only meets the use requirements of wide-spectrum imaging, but also reduces manufacturing costs. This embodiment meets the image-side telecentric design requirements, and the telecentricity of each band is less than 0.5 degrees. This embodiment adopts a reasonable optical focal length distribution to reduce the dispersion focus shift. This embodiment meets the imaging resolution requirements and makes the imaging quality from the center to the edge more uniform. This embodiment adopts an optical athermal design, which can output high-definition images at an ambient temperature of -40°C to 80°C.
[0064] The above descriptions are only some embodiments of the present invention, and do not limit the protection scope of the present invention. Any equivalent device or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present invention.
Claims
1. An image-space telecentric lens for wide spectrum imaging, characterized in that: The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the aperture, the seventh lens, the eighth lens, the ninth lens, the tenth lens and the eleventh lens are arranged in order from the object side to the image side along the optical axis; and the above lenses are all spherical glass lenses; The first lens has a negative refractive power, a flat object side surface, and a concave image side surface; The second lens has a negative refractive power, a concave object side surface, and a concave image side surface; The third lens has positive refractive power, an object side surface is convex, and an image side surface is convex; The fourth lens has positive refractive power, an object side surface is convex, and an image side surface is convex; The fifth lens has positive refractive power, and its object side surface is convex; its image side surface is convex; The sixth lens has negative refractive power, and its object side surface is concave, and its image side surface is concave; The seventh lens has positive refractive power, an object side surface is convex, and an image side surface is convex; The eighth lens has negative refractive power, and its object side surface is concave and its image side surface is concave; The ninth lens has positive refractive power, an object side surface is convex, and an image side surface is convex; The tenth lens has negative refractive power, the object side surface is convex, and the image side surface is concave; The eleventh lens has positive refractive power, an object side surface is convex, and an image side surface is convex.
2. The image-space telecentric lens for wide spectrum imaging according to claim 1, characterized in that: The lens satisfies the following relationship: f1＜0 1.4 <nd1<1.6 69<Vd1<71 Wherein, f1 is the focal length of the first lens; nd1 is the refractive index of the first lens; Vd1 is the Abbe number of the first lens.
3. The image-space telecentric lens for wide spectrum imaging according to claim 1, characterized in that: The lens satisfies the following relationship: 1.8<nd 11 <1.9 39<CEO 11 <41 Where, nd 11 is the refractive index of the eleventh lens; Vd1 is the Abbe number of the eleventh lens.
4. The image-space telecentric lens for wide spectrum imaging according to claim 1, characterized in that: The lens satisfies the following relationship: dn5 / Dt<0 Wherein, dn5 is the refractive index temperature coefficient of the fifth lens.
5. The image-space telecentric lens for wide spectrum imaging according to claim 1, characterized in that: The lens satisfies the following relationship: dn9 / Dt<0 Wherein, dn9 is the refractive index temperature coefficient of the ninth lens.
6. The image-space telecentric lens for wide spectrum imaging according to claim 1, characterized in that: The second lens and the third lens are glued together to form a first glued lens; and the first glued lens satisfies the following relationship: |Vd 正 -Vd 负 |>32 Where Vd 正 is the Abbe number of the positive lens, Vd 负 is the Abbe number of the negative lens.
7. The image-space telecentric lens for wide spectrum imaging according to claim 1, characterized in that: The fifth lens and the sixth lens are glued together to form a second glued lens; and the second glued lens satisfies the following relationship: |Vd 正 -Vd 负 |>32 Where Vd 正 is the Abbe number of the positive lens, Vd 负 is the Abbe number of the negative lens.
8. The image-space telecentric lens for wide spectrum imaging according to claim 1, characterized in that: The eighth lens and the ninth lens are cemented together to form a third cemented lens; and the third cemented lens satisfies the following relationship: |Vd 正 -Vd 负 |>32 Where Vd 正 is the Abbe number of the positive lens, Vd 负 is the Abbe number of the negative lens.
9. An optical device, characterized in that: An image-space telecentric lens for wide-spectrum imaging comprising the method described in any one of claims 1 to 8.