High magnification line scan imaging system and imaging apparatus

Abstract

The application relates to the technical field of optical systems, and provides a high-magnification line scanning imaging system and an imaging device, which solve the problem of small depth of field of an existing high-magnification line scanning imaging system, and comprise object surface one and object surface two, a first lens group arranged in sequence from the object side to the image side along the optical axis, the optical power of the first lens group being positive; a diaphragm; a second lens group, the optical power of the second lens group being negative, and a light splitting prism; the object surface one is imaged on the image surface one after sequentially passing through the first lens group, the diaphragm, the second lens group and the light splitting prism and being subjected to defocusing treatment; and the object surface two is imaged on the image surface two after sequentially passing through the first lens group, the diaphragm, the second lens group and the light splitting prism and being subjected to defocusing treatment. The application can expand the depth of field without assembling other devices, reasonably distribute the optical power, better balance the aberration, realize high magnification and high resolution, and guarantee clear imaging in a large range.

Description

Technical Field

[0001] This invention relates to the field of optical system technology, and in particular to a high-magnification linear scanning imaging system and imaging device. Background Technology

[0002] In recent years, with the vigorous development of the electronics and semiconductor industries, the application of machine vision technology in related equipment has also flourished. Furthermore, with the improvement and advancement of industrial manufacturing technology and processing techniques, inspection requirements are constantly increasing, leading to a strong momentum in high-precision inspection and the emergence of high-magnification telecentric and high-magnification line scanners.

[0003] However, existing high-magnification line scan imaging systems suffer from a common problem: due to their shallow depth of field, lens testing and equipment debugging are extremely cumbersome, sometimes even unusable. To address this issue, the industry typically employs autofocus; however, this increases costs and places excessively high demands on algorithm accuracy and equipment. Summary of the Invention

[0004] The purpose of this invention is to provide a high-magnification line scan imaging system that addresses the problem of shallow depth of field in existing high-magnification line scan imaging systems.

[0005] Another object of the present invention is to provide a high-magnification line scanning imaging device, including the high-magnification line scanning imaging system provided above.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: On one hand, a high-magnification linear scanning imaging system is provided, comprising an object plane one and an object plane two, and components arranged sequentially from the object side to the image side along the optical axis:

[0007] A first lens group, wherein the optical power of the first lens group is positive;

[0008] Aperture;

[0009] A second lens group, wherein the optical power of the second lens group is negative; and

[0010] Beam splitter;

[0011] The object plane one is imaged onto image plane one after passing through the first lens group, the aperture stop, the second lens group and the beam splitter in sequence and being defocused. The object plane two is imaged onto image plane two after passing through the first lens group, the aperture stop, the second lens group and the beam splitter in sequence and being defocused.

[0012] Optionally, the first image plane and the second image plane are perpendicular to each other.

[0013] Optionally, the object plane two can move horizontally along the optical axis, and the image plane two can move vertically along a direction perpendicular to the optical axis, with the horizontal movement of the object plane two and the vertical movement of the image plane two being synchronized.

[0014] Optionally, the first lens group includes at least four lens groups, and the four lens groups include at least two lens groups with positive optical power and one lens group with negative optical power.

[0015] Optionally, the first lens group includes a first lens group, a second lens group, a third lens group, and a fourth lens group arranged sequentially from the object side to the image side along the optical axis. The first lens group is a positive lens, the second lens group has positive optical power, the third lens group is a negative lens, and the fourth lens group has positive optical power. The second lens group includes a fifth lens group, a sixth lens group, a seventh lens group, and an eighth lens group arranged sequentially from the object side to the image side along the optical axis. The fifth lens group has negative optical power, the sixth lens group has negative optical power, the seventh lens group has positive optical power, and the eighth lens group has positive optical power.

[0016] Optionally, the first lens group is a cemented doublet positive lens, the second lens group is a cemented doublet or a single lens with positive optical power, the third lens group is a cemented doublet negative lens, the fourth lens group is a single lens with positive optical power, the fifth lens group is a single lens with negative optical power, the sixth lens group is a cemented doublet with negative optical power, the seventh lens group is a cemented doublet or a single lens with positive optical power, and the eighth lens group is a cemented doublet or a single lens with positive optical power.

[0017] Optionally, the focal length values ​​of the first lens group and the second lens group satisfy the following condition:

[0018] 3.2≤|f2 / f1|≤4.6;

[0019] Where f1 is the focal length of the first lens group and f2 is the focal length of the second lens group.

[0020] Optionally, the imaging system has at least four positive lenses, the refractive index of which satisfies the Abbe number of the following condition:

[0021] 1.43≤nd≤1.59;

[0022] 68.0≤vd≤95;

[0023] Wherein, nd is the refractive index of the positive lens, and vd is the Abbe number of the positive lens.

[0024] Alternatively, the following condition must be satisfied:

[0025] 0.6 ≤ H / F ≤ 0.71;

[0026] 0.14≤NA≤0.21;

[0027] Where H is the holoimage height of the optical system, F is the focal length of the optical system, and NA is the numerical aperture of the system.

[0028] On the other hand, this application also provides a high-magnification line scan imaging device, which includes the high-magnification line scan imaging system provided in the first aspect.

[0029] The beneficial effects of this invention are as follows: The high-magnification line-scan imaging system provided by this invention includes an object plane one and an object plane two, and, arranged sequentially along the optical axis from the object side to the image side: a first lens group with positive optical power, an aperture stop, a second lens group with negative optical power, and a beam splitter. By forming dual focal points through the two object planes and the beam splitter, and by optimizing the defocus of image plane one and image plane two, the depth of field can be expanded without the need for additional equipment. Through the cooperation of the first lens group with positive optical power, the aperture stop, and the second lens group with negative optical power, the optical power is rationally allocated, thereby better balancing aberrations and achieving high magnification and high resolution, ensuring clear imaging over a large range. The high-magnification line-scan imaging device provided by this invention adopts the high-magnification line-scan imaging system provided in the first aspect, expanding the depth of field without the need for additional equipment and ensuring clear imaging over a large range, thus matching technologies in fields such as machine vision. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the high-magnification linear scanning imaging system provided in Embodiment 1 of the present invention;

[0032] Figure 2 The diagram shows the modulation transfer function (MTF) of the high-magnification linear scanning imaging system provided in Embodiment 1 of the present invention.

[0033] Figure 3 The distortion diagram is provided by the high-magnification linear scanning imaging system in Embodiment 1 of the present invention.

[0034] Figure 4 This is a defocus image of the high-magnification linear scanning imaging system provided in Embodiment 1 of the present invention;

[0035] Figure 5 This is a relative illumination diagram of the high-magnification linear scanning imaging system provided in Embodiment 1 of the present invention;

[0036] Figure 6 This is a schematic diagram of the high-magnification linear scanning imaging system provided in Embodiment 2 of the present invention;

[0037] Figure 7 The MTF diagram of the high-magnification linear scanning imaging system provided in Embodiment 2 of the present invention;

[0038] Figure 8 This is a distortion diagram of the high-magnification linear scanning imaging system provided in Embodiment 2 of the present invention;

[0039] Figure 9 This is a defocus image of the high-magnification linear scanning imaging system provided in Embodiment 2 of the present invention;

[0040] Figure 10 This is a relative illumination diagram of the high-magnification line scan imaging system provided in Embodiment 2 of the present invention.

[0041] The following are the labeling elements in the figure:

[0042] Object plane 1 W1; Object plane 2 W2; First lens group G1; Second lens group G2; Beam splitter G3; Aperture stop S; Image plane 1 X1; Image plane 2 X2; First lens group J01; Second lens group J02; Third lens group J03; Fourth lens group J04; Fifth lens group J05; Sixth lens group J06; Seventh lens group J07; Eighth lens group J08; Ninth lens group J09. Detailed Implementation

[0043] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0044] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0046] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0047] Autofocus works by utilizing the principle of light reflection from an object. The reflected light is received by the camera's CCD sensor, processed by a computer, and then drives the motorized focusing mechanism to achieve the desired focus. Because existing high-magnification line-scan imaging systems typically have a shallow depth of field, autofocus is often used to address this issue. However, using autofocus increases costs and places excessively high demands on algorithm accuracy and equipment.

[0048] Therefore, this application provides a high-magnification line scan imaging system and imaging device, which utilizes dual-plane and defocus optimization processing to enable the imaging system to achieve high magnification, high resolution and high definition imaging at low cost.

[0049] Please refer to Figure 1 This application provides a high-magnification linear scanning imaging system, including an object plane W1 and an object plane W2, and objects arranged sequentially from the object side to the image side along the optical axis:

[0050] The first lens group G1 has a positive optical power.

[0051] Aperture S;

[0052] The second lens group G2 has a negative optical power; and

[0053] Spectrometer G3;

[0054] The object plane is the plane on which the object lies, and it is the starting point for all light rays. The image plane is the plane on which the image is formed, and it is the ending point for all light rays. Object plane one W1 passes through the first lens group G1, the aperture stop S, the second lens group G2, and the beam splitter G3 in sequence, and after defocusing, it is imaged onto image plane one X1. Object plane two W2 passes through the first lens group G1, the aperture stop S, the second lens group G2, and the beam splitter G3 in sequence, and after defocusing, it is imaged onto image plane two X2.

[0055] The imaging system is a line scan lens. Light enters from the object side, first passes through the first lens group G1, and then passes through the aperture S and enters the second lens group G2. After passing through the second lens group G2 and exiting, it finally passes through the beam splitter G3 to form two imaging surfaces, namely image surface one X1 and image surface two X2.

[0056] The high-magnification line scan imaging system provided in this application forms dual focal points through dual object planes and a beam splitter prism, and performs defocus optimization processing on image plane 1 (X1) and image plane 2 (X2). It can expand the depth of field without the need for additional equipment. Through the cooperation of a first lens group with positive optical power, an aperture stop, and a second lens group with negative optical power, the optical power is reasonably allocated, thereby better balancing aberrations and achieving high magnification and high resolution, ensuring clear imaging over a large range.

[0057] In this embodiment, image plane X1 and image plane X2 are perpendicular to each other, and the perpendicular image plane X1 and image plane X2 do not interfere with each other.

[0058] In this embodiment, the object plane W2 can move horizontally along the optical axis, and the image plane X2 can move vertically along a direction perpendicular to the optical axis. The horizontal movement of the object plane and the vertical movement of the image plane are synchronized. While the object plane W2 moves vertically, the image plane X2 moves in a relative, mapping manner according to the movement of the object plane W2, achieving multi-object distance depth-of-field expansion. This is suitable for measuring products with a certain height difference, improving the applicability of the system.

[0059] In this embodiment, the first lens group G1 includes four lens groups, and the four lens groups include a positive lens, two positive power lens groups and a negative lens.

[0060] In other embodiments of this application, the first lens group G1 includes five lens groups, including a positive lens, three positive power lens groups and one negative power lens group.

[0061] In other embodiments of this application, the number of lens groups in the first lens group G1 may also be six, seven, etc. This application does not limit the number and type of lens groups, as long as it can ensure that the first lens group G1 includes at least two lens groups with positive optical power and one lens group with negative optical power.

[0062] In this embodiment, the first lens group G1 includes a first lens group J01, a second lens group J02, a third lens group J03, and a fourth lens group J04 arranged sequentially from the object side to the image side along the optical axis. The first lens group J01 is a positive lens used to reduce the aperture and decrease the principal ray angle. The second lens group J02 is a positive power lens group used to further reduce the principal ray angle. The second lens group J02 is responsible for sharing a portion of the optical power of the first lens group J01 to prevent the surface shape of the first lens group J01 from being too exaggerated and to avoid generating higher-order aberrations. The third lens group J03 is a negative lens used to balance the aberrations of the preceding lens groups. The fourth lens group J04 is a positive power lens group used for aberration correction.

[0063] In this embodiment, the second lens group G2 includes a fifth lens group J05, a sixth lens group J06, a seventh lens group J07, and an eighth lens group J08 arranged sequentially from the object side to the image side along the optical axis. The fifth lens group J05 is a negative optical power lens group, the sixth lens group J06 is a negative optical power lens group, and the fifth lens group J05 and the sixth lens group J06 are used to expand the field of view. The seventh lens group J07 is a positive optical power lens group, the eighth lens group J08 is a positive optical power lens group, and the seventh lens group J07 and the eighth lens group J08 are used to balance aberrations.

[0064] In some embodiments of this application, the focal length values ​​of the first lens group G1 and the second lens group G2 satisfy the following condition:

[0065] 3.2≤|f2 / f1|≤4.6;

[0066] Where f1 is the focal length of the first lens group G1 and f2 is the focal length of the second lens group G2. A larger f1 has a larger aperture, which is beneficial for the lens to have a larger aperture, thereby achieving higher resolution. However, the f1 focal length cannot be too large, otherwise there will be aberration imbalance problems.

[0067] In some embodiments of this application, the imaging system has at least four positive lenses, the refractive index of which satisfies the Abbe number as follows:

[0068] 1.43≤nd≤1.59;

[0069] 68.0≤vd≤95;

[0070] Where nd is the refractive index of the positive lens and vd is the Abbe number of the positive lens. By limiting the refractive index and Abbe number of the positive lens and making extensive use of low-dispersion materials, it is possible to better correct the convergence differences of light of different wavelengths.

[0071] In some embodiments of this application, the following condition is satisfied:

[0072] 0.6 ≤ H / F ≤ 0.71;

[0073] 0.14≤NA≤0.21;

[0074] Where H is the full image height of the optical system, F is the focal length of the optical system, and NA is the numerical aperture of the system. By limiting the range of values ​​for H / F and NA, the optical performance of this system can be better guaranteed.

[0075] Example 1

[0076] like Figure 1 As shown, the first lens group G1 includes four lens groups. The first lens group J01 is formed by cementing a biconvex lens and a crescent lens together. The second lens group J02 is a plano-convex single lens with its convex surface facing the first lens group J01. The third lens group J03 is formed by cementing a biconvex lens and a crescent lens together. The fourth lens group J04 is a crescent single lens with its convex surface facing the aperture stop S. The second lens group G2 includes four lens groups. The fifth lens group J05 is a biconcave single lens or a plano-concave single lens. The sixth lens group J06 is formed by cementing a plano-concave lens and a plano-convex lens together, with the negative lens in front and the positive lens behind. The seventh lens group J07 is a plano-convex single lens, and the eighth lens group J08 is a biconvex single lens.

[0077] Example 2

[0078] like Figure 6 As shown, the first lens group G1 includes four lens groups. The first lens group J01 is formed by cementing a biconvex lens and a crescent lens together. The second lens group J02 is formed by cementing a biconvex lens and a plano-concave lens together, with the plane facing the aperture stop S. The third lens group J03 is formed by cementing a biconvex lens and a biconcave lens together. The fourth lens group J04 is a plano-convex single lens, with the convex surface facing the aperture stop S. The second lens group G2 includes five lens groups. The fifth lens group J05 is a biconcave single lens or a plano-concave single lens. The sixth lens group J06 is formed by cementing a plano-concave lens and a plano-convex lens together, with the negative lens in front and the positive lens behind. The seventh lens group J07 is a plano-convex single lens. The eighth lens group J08 is a plano-convex single lens. The ninth lens group J09 is a crescent lens.

[0079] It should be noted that the second lens group J02, the seventh lens group J07, and the eighth lens group J08 can be either cemented doublets or single lenses.

[0080] Tables 1 and 2 provide the specific parameter values ​​for each lens in the high-magnification linear scanning imaging systems of Embodiments 1 and 2 of this application, respectively. Among them, "surface number" is the number of each surface arranged sequentially from the object side to the image side, "R value" is the radius of the sphere corresponding to each sphere, and "thickness / spacing" is the axial distance between two adjacent surfaces. If the two surfaces belong to the same lens, it represents the thickness of the lens; otherwise, it represents the distance from the object / image surface to the lens or the spacing between adjacent lenses.

[0081] Table 1 shows the lens parameters of the high-magnification linear scanning imaging system in Example 1.

[0082] Face number Surface type R value Thickness / Spacing Refractive index Abbe number Sur1 Standard 147.439 12.076 1.437001 95.1004 Sur2 Standard -35.428 2 1.582672 46.6064 Sur3 Standard -122.311 2.879 Sur4 Standard 125.504 4.376 1.656914 51.1566 Sur5 Standard Infinity 0.15 Sur6 Standard 61.762 12.466 1.437001 95.1004 Sur7 Standard -52.185 2 1.620047 36.3479 Sur8 Standard 138.083 2.363 Sur9 Standard -899.81 8.099 1.805189 25.4773 Sur10 Standard -69.77 23.679 STOP1 Standard Infinity 6.812 Sur12 Standard -45.731 2 1.569702 49.4482 Sur13 Standard 53.304 8.218 Sur14 Standard -23.735 7.968 1.59349 67.3266 Sur15 Standard Infinity 8.569 1.437001 95.1004 Sur16 Standard -38.312 0.151 Sur17 Standard -183.562 7.504 1.437001 95.1004 Sur18 Standard -43.326 0.167 Sur19 Standard 116.751 7.706 1.437001 95.1004 Sur20 Standard -159.417 10 Sur21 Standard Infinity 80 1.516797 64.2124 Image Standard Infinity 467.98

[0083] Table 2 shows the lens parameters of the high-magnification linear scanning imaging system in Example 2.

[0084]

[0085]

[0086] Tables 3 and 4 show the corresponding positional relationships between object distance and image distance in the high-magnification linear scanning imaging systems of Embodiments 1 and 2 of this application, respectively.

[0087] Table 3 shows the corresponding positional relationship between object distance and image distance in the high-magnification linear scanning imaging system of Example 1.

[0088] Object distance Image distance 1 96.489 467.98 2 97.649 445.305 3 95.649 485.747

[0089] Table 4 shows the corresponding positional relationship between object distance and image distance in the high-magnification linear scanning imaging system of Example 2.

[0090] Object distance Image distance 1 94.711 414.758 2 95.411 400.825 3 94.011 429.525

[0091] On the other hand, this application also provides a high-magnification line scan imaging device, which includes the high-magnification line scan imaging system provided in the first aspect. It can expand the depth of field without the need for additional assembly of other equipment, ensuring clear imaging over a large range, thereby matching technologies in fields such as machine vision.

[0092] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-magnification linear scanning imaging system, characterized in that: Including object plane one and object plane two, and the following are arranged sequentially from the object side to the image side along the optical axis: A first lens group, wherein the optical power of the first lens group is positive; Aperture; The second lens group has a negative optical power. as well as Beam splitter; The object plane one is imaged onto the image plane one after passing through the first lens group, the aperture, the second lens group and the beam splitter in sequence and being defocused. The object plane two is imaged onto the image plane two after passing through the first lens group, the aperture, the second lens group and the beam splitter in sequence and being defocused. The focal lengths of the first lens group and the second lens group satisfy the following condition: 3.2 ≤ |f2 / f1| ≤ 4.6; Where f1 is the focal length of the first lens group and f2 is the focal length of the second lens group; The imaging system has at least four positive lenses, and the refractive index and Abbe number of the positive lenses satisfy the following condition: 1.43 ≤ nd ≤ 1.59; 68 ≤ vd ≤ 95; Wherein, nd is the refractive index of the positive lens, and vd is the Abbe number of the positive lens.

2. The high-magnification linear scanning imaging system according to claim 1, characterized in that, Image plane one and image plane two are perpendicular to each other.

3. The high-magnification linear scanning imaging system according to claim 2, characterized in that: The object plane two can move horizontally along the optical axis, and the image plane two can move vertically along the direction perpendicular to the optical axis. The horizontal movement of the object plane two and the vertical movement of the image plane two are synchronized.

4. The high-magnification linear scanning imaging system according to claim 1, characterized in that: The first lens group includes at least four lens groups, and the four lens groups include at least two lens groups with positive optical power and one lens group with negative optical power.

5. The high-magnification linear scanning imaging system according to claim 4, characterized in that: The first lens group includes a first lens group, a second lens group, a third lens group, and a fourth lens group arranged sequentially from the object side to the image side along the optical axis. The first lens group is a positive lens, the second lens group has positive optical power, the third lens group is a negative lens, and the fourth lens group has positive optical power. The second lens group includes a fifth lens group, a sixth lens group, a seventh lens group, and an eighth lens group arranged sequentially from the object side to the image side along the optical axis. The fifth lens group has negative optical power, the sixth lens group has negative optical power, the seventh lens group has positive optical power, and the eighth lens group has positive optical power.

6. The high-magnification linear scanning imaging system according to claim 5, characterized in that: The first lens group is a cemented doublet positive lens, the second lens group is a cemented doublet or a single lens with positive optical power, the third lens group is a cemented doublet negative lens, the fourth lens group is a single lens with positive optical power, the fifth lens group is a single lens with negative optical power, the sixth lens group is a cemented doublet with negative optical power, the seventh lens group is a cemented doublet or a single lens with positive optical power, and the eighth lens group is a cemented doublet or a single lens with positive optical power.

7. The high-magnification linear scanning imaging system according to any one of claims 1-6, characterized in that: The imaging system satisfies the following condition: 0.6 ≤ H / F ≤ 0.71; 0.14 ≤ NA ≤ 0.21; Where H is the holoimage height of the imaging system, F is the focal length of the imaging system, and NA is the numerical aperture of the system.

8. A high-magnification line scan imaging device, characterized in that: Includes the high-magnification line scanning imaging system according to any one of claims 1-7.

Images