TWI751805B - Large field of view imaging objective lens - Google Patents

Abstract

The invention provides an imaging objective lens with a large field of view, which sequentially includes a first lens group with positive refractive power, a diaphragm, a second lens group with positive refractive power, a third lens group with negative refractive power and The fourth lens group with positive refractive power. Among them, the total length of the objective lens is ≤850mm, which is suitable for the wide spectrum of 450-650nm, the magnification is -10x, the numerical aperture of the object side is NA≤0.3, and the diameter of the field of view of the object side is 8.4mm. Compared with the existing imaging lens, the imaging objective lens provided by the present invention has a longer working distance and a larger field of view under the same image quality requirements close to the diffraction limit, can meet the space requirements of the system, and can effectively realize a large aperture. , Large magnification, aberration correction of bi-telecentric system.

Description

Wide Field Imaging Objectives

The invention relates to the technical field of imaging, in particular to a large field of view imaging objective lens.

With the development of industrial technology, in the fields of biology, genetics, medical treatment, industry, etc., the requirements for detection accuracy, detection speed, and detection size are constantly increasing, so the requirements for automatic optical inspection (AIO) equipment and imaging objective lenses are also increasing. The higher it is, especially the imaging objective lens that can meet the requirements of large workpiece, large field of view, and no distortion precision detection, both in terms of design and manufacture, are very difficult.

The purpose of the present invention is to provide an imaging objective lens with a large field of view, so as to realize aberration correction of a large aperture, large magnification, and a double telecentric system.

The invention provides an imaging objective lens with a large field of view, comprising: a first lens group with positive refractive power, a diaphragm, a second lens group with positive refractive power, and a third lens group with negative refractive power are sequentially arranged along the incident direction of the light beam A lens group and a fourth lens group with positive refractive power; wherein, the first lens group, the second lens group, the third lens group and the fourth lens group satisfy the following relationship: 0.2＜|f1/f2|＜1; 3<|f2/f3|<9; 0.1＜|f3/f4|＜0.5; 0.1＜|f1/f4|＜1; Wherein, f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, f3 is the focal length of the third lens group, and f4 is the focal length of the fourth lens group.

Preferably, the first lens group is composed of at least three lenses, including three positive lenses; The second lens group is composed of at least five lenses, including two doublet lens groups and a positive lens; The third lens group is composed of at least two lenses, including two negative lenses; The fourth lens group is composed of at least two lenses, including two positive lenses; Among them, except for the two doublet lens groups, the remaining eight lenses are spherical single lenses.

Preferably, the first lens group, the second lens group, the third lens group and the fourth lens group satisfy the following relationship: 0.5＜|f1/f2|＜1; 3<|f2/f3|<4.5; 0.1＜|f3/f4|＜0.5; 0.1<|f1/f4|<1.

Preferably, the first lens group is composed of three lenses, which are followed by a meniscus positive lens, a biconvex positive lens and a meniscus positive lens along the incident direction of the light beam; The second lens group is composed of five lenses, and along the incident direction of the light beam are sequentially a doublet lens group composed of a meniscus negative lens and a biconvex positive lens, a doublet lens group composed of a biconvex positive lens and a meniscus negative lens, and biconvex positive lens; The third lens group is composed of two lenses, which are followed by a meniscus negative lens and a meniscus negative lens along the incident direction of the light beam; The fourth lens group is composed of two lenses, which are followed by a meniscus positive lens and a biconvex lens along the incident direction of the light beam.

Preferably, the object-side field curvature of the large-field imaging objective lens is less than 0.35 μm, and the distortion is less than 0.03%.

Preferably, the first lens group, the second lens group, the third lens group and the fourth lens group satisfy the following relationship: 0.2＜|f1/f2|＜1; 4<|f2/f3|<9; 0.1＜|f3/f4|＜0.5; 0.1<|f1/f4|<0.5.

Preferably, the first lens group is composed of three lenses, which are followed by a positive meniscus lens, a positive meniscus lens and a positive meniscus lens along the incident direction of the light beam; The second lens group is composed of six lenses, and along the incident direction of the light beam is a doublet lens group composed of a double concave negative lens and a double convex positive lens, a meniscus negative lens, a double convex positive lens, and a double convex positive lens and a double lens. A doublet lens group consisting of a concave negative lens; The third lens group is composed of two lenses, which are followed by a double concave negative lens and a meniscus negative lens along the incident direction of the light beam; The fourth lens group is composed of two lenses, which are followed by a meniscus positive lens and a biconvex positive lens along the incident direction of the light beam.

Preferably, the object-side field curvature of the large-field imaging objective lens is less than 0.75 μm, and the distortion is less than 0.2%.

Preferably, the total length of the large field of view imaging objective lens is less than or equal to 850mm, the numerical aperture of the object side is less than or equal to 0.3, and the magnification is -10x.

Preferably, the object-side working distance of the large-field imaging objective lens is greater than 40 mm, and the diameter of the object-side field of view is 8.4 mm.

Preferably, at least two positive lenses in the first lens group are made of flint glass material; The negative lenses in the two doublet lens groups in the second lens group are all made of flint glass material, and the positive lenses in the two doublet lens groups in the second lens group are all made of crown glass material ; At least one negative lens in the third lens group is made of flint glass material; At least one positive lens in the fourth lens group is made of flint glass material.

Preferably, an illumination beam splitter prism is arranged between the first lens group and the diaphragm, and a detector beam splitter prism is arranged between the fourth lens group and the image plane.

Preferably, the first lens group, the second lens group, the third lens group and the fourth lens group are symmetrically arranged with the diaphragm as the center, forming an object-side and image-side bi-telecentric optical path.

Preferably, the large field of view imaging objective lens is suitable for the spectrum of 450 nm-650 nm.

Compared with the existing imaging lens, under the same image quality requirements close to the diffraction limit, the large field of view imaging objective lens provided by the present invention has a longer working distance and a larger field of view range, can meet the space requirements of the system, and can effectively Realize aberration correction of large aperture, large magnification, and bi-telecentric system.

The following describes the large field of view imaging objective lens of the present invention in further detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description and accompanying drawings, however, it should be noted that the concept of the technical solution of the present invention can be implemented in many different forms, and is not limited to the specific embodiments set forth herein. . The accompanying drawings are all in a very simplified form and in an inaccurate scale, and are only used to facilitate and clearly assist the purpose of explaining the embodiments of the present invention.

The terms "first," "second," and the like, in the specification and claims are used to distinguish between similar elements, and are not necessarily used to describe a particular order or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances, eg, to enable the embodiments of the invention described herein to operate in other sequences than described or illustrated herein. Similarly, if a method described herein includes a series of steps, the order of the steps presented herein is not necessarily the only order in which the steps may be performed, and some of the steps described may be omitted and/or some not described herein Additional steps can be added to this method. If the components in a certain drawing are the same as the components in other drawings, although these components can be easily identified in all the drawings, in order to make the description of the drawings clearer, this specification will not refer to all the same components. Numbers are attached to each figure.

The invention provides an imaging objective lens with a large field of view, comprising: a first lens group with positive refractive power, an illumination beam splitting prism, a diaphragm, a second lens group with positive refractive power and a negative refractive power are sequentially arranged along the incident direction of the light beam The third lens group with high refractive power, the fourth lens group with positive refractive power, and the detector beam splitter prism, wherein the first lens group, the second lens group, the third lens group and the fourth lens group satisfy the following relationship: 0.2＜|f1/f2|＜1 3＜|f2/f3|＜9 0.1＜|f3/f4|＜0.5 0.1＜|f1/f4|＜1 Wherein, f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, f3 is the focal length of the third lens group, and f4 is the focal length of the fourth lens group.

In the present invention, the first lens group, the second lens group, the third lens group and the fourth lens group are symmetrically arranged with the diaphragm as the center, forming an object-side and image-side double telecentric optical path. The first lens group is composed of at least three lenses, including three positive lenses; the second lens group is composed of at least five lenses, including two doublet lens groups and one positive lens; the The third lens group is composed of at least five lenses, including three negative lenses; the fourth lens group is composed of at least five lenses, including two positive lenses. Among them, except for the two doublet lens groups, the remaining eight lenses are spherical single lenses.

Optical materials can generally be divided into two categories according to the refractive index and Abbe number: Class A flint glass material: high refractive index material with low Abbe number, that is, the refractive index is greater than 1.52 and the Abbe number is less than 60; Class B crown brand Glass material: low refractive index material with high Abbe number, that is, the refractive index is less than 1.52 and the Abbe number is greater than 60. Specifically in the present invention, at least two positive lenses in the first lens group are made of flint glass material; the negative lenses in the two doublet lens groups in the second lens group are all made of flint glass material, and the The positive lenses in the two doublet lens groups in the second lens group are all made of crown glass material; at least one negative lens in the third lens group is made of flint glass material; at least one positive lens in the fourth lens group is made of The lens is made of flint glass material. The second lens group of the present invention adopts two achromatic cemented lens groups composed of crown glass with positive refractive power and flint glass with negative refractive power, which can effectively correct the chromatic aberration caused by the wide spectrum.

In the present invention, the first lens group, the second lens group, the third lens group and the fourth lens group are symmetrically arranged with the diaphragm as the center, forming an object-side and image-side double telecentric optical path. The diaphragm is arranged between the first lens group and the second lens group, and the illumination beam splitting prism is between the first lens group and the diaphragm, and the effective aperture of the imaging objective can be adjusted by adjusting the size of the diaphragm, that is, by adjusting Aperture to adjust the focal ratio (F/#) of the objective lens to adapt to different relevant lighting or non-related lighting application scenarios.

Example 1

FIG. 1 is an optical structure diagram of a large field of view imaging objective lens provided by the present embodiment. Referring to FIG. 1, the large field of view imaging objective lens provided by the present invention includes: along the incident direction of the light beam (from the object plane Object to the image plane IMA) in order A first lens group G1 with positive refractive power, an illumination beam splitting prism L1, a diaphragm STOP, a second lens group G2 with positive refractive power, a third lens group G3 with negative refractive power, a The fourth lens group G4 and the detector beam splitting prism L2; wherein, the first lens group G1, the second lens group G2, the third lens group G3 and the fourth lens group G4 satisfy the following relationship: 0.5＜|f1/f2|＜1; 3<|f2/f3|<4.5; 0.1＜|f3/f4|＜0.5; 0.1＜|f1/f4|＜1; Wherein, f1 is the focal length of the first lens group G1, f2 is the focal length of the second lens group G2, f3 is the focal length of the third lens group G3, and f4 is the focal length of the fourth lens group G4.

The first lens group G1 consists of three lenses, which are followed by a positive meniscus lens 1, a biconvex positive lens 2 and a positive meniscus lens 3 along the incident direction of the light beam; the second lens group G2 consists of five lenses Formed, along the incident direction of the light beam, it is followed by a doublet lens group composed of a meniscus negative lens 4 and a biconvex positive lens 5, a doublet lens group composed of a biconvex positive lens 6 and a meniscus negative lens 7, and a biconvex positive lens 8; The third lens group G3 is composed of two lenses, which are followed by a negative meniscus lens 9 and a negative meniscus lens 10 along the incident direction of the light beam; the fourth lens group G4 is composed of two lenses, which are followed by a negative meniscus lens along the incident direction of the light beam. Meniscus positive lens 11 and biconvex positive lens 12 .

At least two positive lenses in the first lens group G1 are made of flint glass material, such as one meniscus positive lens and one biconvex positive lens or two meniscus positive lenses are made of flint glass material; the second The negative lenses in the two doublet lens groups in the lens group G2 are all made of flint glass materials, and the positive lenses in the two doublet lens groups in the second lens group G2 are all made of crown glass materials. Two achromatic cemented lens groups, both composed of crown glass with positive refractive power and flint glass with negative refractive power, can effectively correct chromatic aberration caused by wide spectrum; at least one meniscus negative in the third lens group G3 The lens is made of flint glass material; at least one of the meniscus positive lens and the biconvex lens in the fourth lens group is made of flint glass material.

In this embodiment, the first lens group, the second lens group, the third lens group, and the fourth lens group are symmetrically arranged with the diaphragm as the center, forming an object-side and image-side double telecentric optical path. The chief ray of each field of view on the object side is incident on the front surface of the first lens (positive meniscus lens 1) approximately parallel to the optical axis. On the object side, the chief ray of each field of view on the object plane is parallel to the light The axis is incident on the first lens (positive meniscus lens 1), and the angle between the chief ray and the optical axis is less than 5mrad; on the image side, the chief ray of each field of view point is approximately parallel to the optical axis and is imaged on the image plane (IMA) , the angle between it and the optical axis is less than 17.4mrad, that is, the object side and the image side have small telecentricity.

In the large field of view imaging objective lens provided in this embodiment, the working distance on the object side is greater than 40 mm, which can meet the working distance requirements of other components in the application scene of the objective lens. The total length of the objective lens is less than or equal to 850mm, the magnification is -10x, the numerical aperture NA on the object side is less than or equal to 0.3, and the diameter of the field of view on the object side is 8.4mm, under the same image quality requirements close to the diffraction limit, in the microscope imaging lens It can achieve a longer working distance and a larger field of view to meet the space requirements of the system, and can effectively achieve aberration correction for large aperture, large magnification, and bi-telecentric systems.

Specifically, Table 1 shows the specific design values of the imaging objective provided in this embodiment, where the radius column represents the curvature radius of the lens, a positive radius represents that the center of curvature of the lens is on the right side of the surface, and a negative radius represents that the center of curvature of the lens is on the surface On the left, Infinity means this surface is flat. In the table, OBJ represents the object surface, STOP represents the aperture diaphragm, IMA represents the image surface, and the surface number counts the surface from the incident end of the light. The filling gas between each lens is air. The value in the material column means that the lens is a virtual material, the value represents the refractive index and Abbe number, "air" represents the air space between the lens and the lens, and the filling gas is air. The thickness/spacing column in the table represents the air gap or lens thickness, and the lens thickness or the separation between two lenses refers to the on-axis distance from one surface to the next surface, and all dimensions are in millimeters (mm). Table 1 surface serial number type Radius(mm) Thickness/Interval(mm) Material OBJ Sphere Infinity 49.23 air 1 Sphere -125.95 9.5 846.237 2 Sphere -68.85 3.2 air 3 Sphere 550.2 9 717.295 4 Sphere -165.3 3. air 5 Sphere 205.67 9.35 744.449 6 Sphere 650.5 8 air 7 Sphere Infinity 45 516.642 8 Sphere Infinity 12.5 air STOP Sphere Infinity 12.3 air 10 Sphere 281.3 8.1 846.237 11 Sphere 39.86 9.64 496.816 12 Sphere -83.71 2.8 air 13 Sphere 79.15 10.2 496.816 14 Sphere -45.53 10.45 672.321 15 Sphere 596 7.5 air 16 Sphere 68.95 10.78 487.704 17 Sphere -68.95 22.12 air 18 Sphere -535 9.5 672.231 19 Sphere 38.74 9 air 20 Sphere -28.5 10.63 623.581 twenty one Sphere 360.7 24.8 air twenty two Sphere -63.3 11.56 846.237 twenty three Sphere -47.23 101.2 air twenty four Sphere 419 15.8 744.449 25 Sphere -276.8 267.42 air 26 Sphere Infinity 20 516.642 27 Sphere Infinity 121.2 air IMA Sphere Infinity 0 air

The specific parameters of the above lenses can be adjusted and optimized according to the size of the numerical aperture in actual operation to meet the requirements of different system parameters. Specifically, based on the current embodiment, if the working distance is small, the objective lens can meet the design requirements of a larger field of view and a larger aperture, and the total length of the objective lens can be reduced; if the field of view is reduced, a larger aperture and higher resolution can be satisfied. If the aperture is reduced, it can meet the design requirements of a higher field of view. That is, the optical structure of the imaging objective lens provided in this embodiment can adapt to the application requirements of various parameters.

FIG. 2 is a graph of the transfer function of the imaging objective lens provided in the present embodiment. The transfer function (MTF) is used to evaluate the efficiency of the transfer of graphs with different spatial frequencies to the image plane through the optical system, wherein the transfer function (MTF) graph is The abscissa is the spatial frequency (Spatial Frequency), the unit is line pairs/mm (cycles/mm), and the ordinate is the modulation function (Modulation). As shown in FIG. 2 , the MTF of the imaging objective lens of this embodiment is close to the diffraction limit.

3 is a schematic diagram of the field curvature and distortion of the imaging objective lens of the present embodiment, the left side is a schematic diagram of the field curvature, the abscissa represents the amount of deviation of the image points from the focal plane in different fields of view, the ordinate is the height of the field of view on the object side, and the dotted line indicates that the image points are at The size of the field curvature on the sagittal plane, the solid line represents the size of the field curvature of the image point on the meridian plane; the right side is the distortion diagram, the abscissa represents the distortion percentage, and the ordinate is the height of the object-side field of view. It can be seen from FIG. 3 that the object-side field curvature of the optical imaging objective lens of this embodiment is less than 0.35 μm, and the distortion is less than 0.03%.

In addition, the resolution of the imaging objective lens provided in this embodiment is: when the line width (CD) is equal to 1.2 μm, MTF>0.48, the depth of field is: 53+/-5 μm@CD1.2 μm, MTF>0.2.

Embodiment 2

FIG. 4 is an optical structure diagram of a large field of view imaging objective lens provided in this embodiment. Referring to FIG. 4 , the present invention provides a large field of view imaging objective lens, including: along the incident direction of the light beam (from the object plane Object to the image plane IMA) The first lens group G1 with positive refractive power, the illumination beam splitting prism L1, the diaphragm STOP, the second lens group G2 with positive refractive power, the third lens group G3 with negative refractive power, and the positive refractive power are sequentially arranged. The fourth lens group G4 and the detector beam splitting prism L2; wherein, the first lens group G1, the second lens group G2, the third lens group G3 and the fourth lens group G4 satisfy the following relationship: 0.2＜|f1/f2|＜1; 4<|f2/f3|<9; 0.1＜|f3/f4|＜0.5; 0.1＜|f1/f4|＜0.5; Wherein, f1 is the focal length of the first lens group G1, f2 is the focal length of the second lens group G2, f3 is the focal length of the third lens group G3, and f4 is the focal length of the fourth lens group G4.

The first lens group G1 is composed of three lenses, which are followed by a positive meniscus lens 13, a positive meniscus lens 14 and a positive meniscus lens 15 along the incident direction of the light beam; the second lens group G2 is composed of six lenses Composition, along the incident direction of the light beam are followed by a double cemented lens group composed of a double concave negative lens 16 and a double convex positive lens 17, a meniscus negative lens 18, a double convex positive lens 19 and a double convex positive lens 20 and a double concave negative lens 21. The third lens group G3 is composed of two lenses, which are followed by a double concave negative lens 22 and a meniscus negative lens 23 along the incident direction of the light beam; the fourth lens group G4 is composed of two lenses, A meniscus positive lens 24 and a biconvex lens 25 are arranged in sequence along the incident direction of the light beam.

The at least two meniscus positive lenses in the first lens group G1 are made of flint glass material; the negative lenses in the two doublet lens groups in the second lens group G2 are all made of flint glass material, and the The positive lenses in the two doublet lens groups in the second lens group G2 are both made of crown glass material, using two achromatic cemented lenses each consisting of crown glass with positive power and flint glass with negative power. The lens group can effectively correct the chromatic aberration caused by the wide spectrum; at least one of the double concave negative lens 22 and the meniscus negative lens 23 in the third lens group G3 is made of flint glass material; the fourth lens group is curved At least one of the moon positive lens and the biconvex lens is made of flint glass material.

In this embodiment, the first lens group, the second lens group, the third lens group, and the fourth lens group are symmetrically arranged with the diaphragm as the center, forming an object-side and image-side double telecentric optical path. The chief ray of each field of view on the object side is incident on the front surface of the first lens (positive meniscus lens 1) approximately parallel to the optical axis. On the object side, the chief ray of each field of view on the object plane is parallel to the light The axis is incident on the first lens (positive meniscus lens 13), and the angle between the chief ray and the optical axis is less than 8mrad; on the image side, the chief ray of each field of view point is approximately parallel to the optical axis and is imaged on the image plane (IMA) , the angle between it and the optical axis is less than 17.4mrad, that is, the object side and the image side have small telecentricity.

In the large field of view imaging objective lens provided in this embodiment, the working distance on the object side is greater than 40 mm, which can meet the working distance requirements of other components in the application scene of the objective lens. The total length of the objective lens is less than or equal to 840mm, the magnification is -10x, the numerical aperture NA on the object side is less than or equal to 0.3, and the diameter of the field of view on the object side is 8.4mm, under the same image quality requirements close to the diffraction limit, in the microscope imaging lens It can achieve a longer working distance and a larger field of view to meet the space requirements of the system, and can effectively achieve aberration correction for large aperture, large magnification, and bi-telecentric systems.

Specifically, Table 2 shows the specific design values of the imaging objective provided in this embodiment, where the radius column represents the curvature radius of the lens, a positive radius represents that the center of curvature of the lens is on the right side of the surface, and a negative radius represents that the center of curvature of the lens is on the surface On the left, Infinity means this surface is flat. In the table, OBJ represents the object surface, STOP represents the aperture diaphragm, IMA represents the image surface, and the surface number counts the surface from the incident end of the light. The filling gas between each lens is air. The value in the material column means that the lens is a virtual material, the value represents the refractive index and Abbe number, "air" represents the air space between the lens and the lens, and the filling gas is air. The thickness/spacing column in the table represents the air gap or lens thickness, and the lens thickness or the separation between two lenses refers to the on-axis distance from one surface to the next surface, and all dimensions are in millimeters (mm). Table 2 surface serial number type Radius(mm) Thickness/Interval(mm) Material OBJ Sphere Infinity 47.5 air 1 Sphere -69.609 8.5 946.179 2 Sphere -72 2.5 air 3 Sphere -832 9.5 784.257 4 Sphere -79.9 3 air 5 Sphere 101.1 9.5 784.257 6 Sphere 299.4 8 air 7 Sphere Infinity 45 516.642 8 Sphere Infinity 8.5 air STOP Sphere Infinity 15.36 air 10 Sphere -133.11 8.1 923.189 11 Sphere 91.24 15 618.634 12 Sphere -105.2 5 air 13 Sphere 382 9.37 743.492 14 Sphere 148.5 7.12 air 15 Sphere 96.29 16.6 607.566 16 Sphere -153.5 15 air 17 Sphere 85.1 14.38 572.575 18 Sphere -102.32 17.9 923.189 19 Sphere 210.5 44.8 air 20 Sphere -85.22 18 696.555 twenty one Sphere 142.89 23.6 air twenty two Sphere -39.504 19.92 564.608 twenty three Sphere -766 33.6 air twenty four Sphere -174.2 20.8 805.254 25 Sphere -98.76 6 air 26 Sphere 499 twenty one 749.349 27 Sphere -307.6 257.9 air 30 Sphere Infinity 20 516.642 31 Sphere Infinity 99.46 air IMA Sphere Infinity 0 air

The specific parameters of the above lenses can be adjusted and optimized according to the size of the numerical aperture in actual operation to meet the requirements of different system parameters. Specifically, based on the current embodiment, if the working distance is small, the objective lens can meet the design requirements of a larger field of view and a larger aperture, and the total length of the objective lens can be reduced; if the field of view is reduced, a larger aperture and higher resolution can be satisfied. If the aperture is reduced, it can meet the design requirements of a higher field of view. That is, the optical structure of the imaging objective lens provided in this embodiment can adapt to the application requirements of various parameters.

FIG. 5 is a graph of the transfer function of the imaging objective lens provided in this embodiment, and FIG. 6 is a schematic diagram of field curvature and distortion of the imaging objective lens in this embodiment. As shown in FIG. 5 , the MTF of the imaging objective lens of this embodiment is already close to the diffraction limit. It can be seen from FIG. 3 that the object-side field curvature of the optical imaging objective lens of this embodiment is less than 0.75 μm, and the distortion is less than 0.2%.

In addition, the resolution of the imaging objective lens provided in this embodiment is: when the line width (CD) is equal to 1.2 μm, MTF>0.48, the depth of field is: +/-4.5 μm@CD1.2 μm, MTF>0.2.

To sum up, the large field of view imaging objective lens provided in the present invention adopts a double telecentric optical structure composed of positive, positive, negative and positive lens groups, the total length of the objective lens is ≤850mm, and is suitable for a wide spectrum of 450-650nm, and the magnification is -10x, the numerical aperture of the object side is NA≤0.3, and the diameter of the object side field of view is 8.4mm. Compared with the existing imaging lens, under the same image quality requirement close to the diffraction limit, the imaging objective lens provided by the present invention has a longer working distance and a larger field of view, can meet the space requirements of the system, and can effectively realize a large aperture. , Large magnification, aberration correction of bi-telecentric system.

It should be noted that each embodiment in this specification is described in a related manner, and the same and similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. . In particular, for the structural embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and reference may be made to the partial descriptions of the method embodiments for related parts.

The above description is only a description of the preferred embodiments of the present invention, and does not limit the scope of the present invention. Any changes and modifications made by those with ordinary knowledge in the technical field of the present invention according to the above disclosure belong to the protection scope of the patent application. .

1,13,14,15: Meniscus Positive Lens 2,5,6,8,12,17,19,20: Double convex positive lens 3, 11, 24: Meniscus Positive Lens 4,7,9,10,18,23: Meniscus Negative Lens 16, 21, 22: Double concave negative lens 25: Double convex lens G1: The first lens group G2: Second lens group G3: Third lens group G4: Fourth lens group L1: Illumination Beamsplitter Prism L2: Detector beam splitter prism STOP: stop Object: object surface IMA: like face

1 is an optical structure diagram of a large field of view imaging objective lens provided in Embodiment 1 of the present invention; 2 is a graph of the transfer function of the large field of view imaging objective lens provided in Embodiment 1 of the present invention; 3 is a schematic diagram of field curvature and distortion of a large-field imaging objective lens provided in Embodiment 1 of the present invention; 4 is an optical structure diagram of a large field of view imaging objective lens provided in Embodiment 2 of the present invention; 5 is a graph of the transfer function of the large field of view imaging objective lens provided in Embodiment 2 of the present invention; and FIG. 6 is a schematic diagram of field curvature and distortion of a large field of view imaging objective lens provided in Embodiment 2 of the present invention.

1: Meniscus Positive Lens

2,5,6,8,12: Double convex positive lens

3,11: Meniscus Positive Lens

4,7,9,10: Meniscus Negative Lens

G1: The first lens group

G2: Second lens group

G3: Third lens group

G4: Fourth lens group

L1: Illumination Beamsplitter Prism

L2: Detector beam splitter prism

STOP: stop

Object: object surface

IMA: like face

Claims (14)

A large field of view imaging objective lens, comprising: a first lens group with positive refractive power, a diaphragm, a second lens group with positive refractive power, a A third lens group and a fourth lens group with positive refractive power, wherein the first lens group, the second lens group, the third lens group and the fourth lens group satisfy the following relationship: 0.2<| f1/f2|<1; 3<|f2/f3|<9; 0.1<|f3/f4|<0.5; 0.1<|f1/f4|<1; where, f1 is the focal length of the first lens group, and f2 is the focal length of the second lens group, f3 is the focal length of the third lens group, and f4 is the focal length of the fourth lens group. The large field of view imaging objective according to claim 1, wherein the first lens group is composed of at least three lenses, including three positive lenses; the second lens group is composed of at least five lenses, including two lenses A doublet lens group and a positive lens; the third lens group is composed of at least two lenses, including two negative lenses; the fourth lens group is composed of at least two lenses, including two positive lenses; wherein, the Three positive lenses in the first lens group, one positive lens in the second lens group, two negative lenses in the third lens group, and two positive lenses in the fourth lens group are spherical single lenses. The large field of view imaging objective lens according to claim 2, wherein the first lens group, the The second lens group, the third lens group, and the fourth lens group satisfy the following relationship: 0.5<|f1/f2|<1; 3<|f2/f3|<4.5; 0.1<|f3/f4|<0.5 ; 0.1<|f1/f4|<1. The large field of view imaging objective lens according to claim 3, wherein the first lens group is composed of three lenses, which are a positive meniscus lens, a biconvex positive lens and a positive meniscus lens in sequence along the incident direction of the light beam; the second lens group is composed of three lenses. The lens group is composed of five lenses. Along the incident direction of the light beam, there are a doublet lens group consisting of a meniscus negative lens and a biconvex positive lens, a doublet lens group consisting of a biconvex positive lens and a meniscus negative lens, and a biconvex positive lens. The third lens group is composed of two lenses, which are followed by a meniscus negative lens and a meniscus negative lens along the incident direction of the light beam; the fourth lens group is composed of two lenses, which are followed by a meniscus positive lens and a meniscus negative lens along the light beam incident direction. Biconvex positive lens. The large-field imaging objective lens according to claim 4, wherein the object-side field curvature of the large-field imaging objective lens is less than 0.35 μm, and the distortion is less than 0.03%. The large-field imaging objective lens according to claim 2, wherein the first lens group, the second lens group, the third lens group and the fourth lens group satisfy the following relationship: 0.2<|f1/f2| <1; 4<|f2/f3|<9; 0.1<|f3/f4|<0.5; 0.1<|f1/f4|<0.5. The large field of view imaging objective lens according to claim 6, wherein the first lens group is composed of three lenses, which are a positive meniscus lens, a positive meniscus lens and a positive meniscus lens in sequence along the incident direction of the light beam; the second lens group is composed of three lenses. The lens group is composed of six lenses. Along the incident direction of the light beam, it is composed of a double-condensed lens group consisting of a double-concave negative lens and a double-convex positive lens, a meniscus negative lens, a double-convex positive lens, and a double-convex positive lens and a double-concave negative lens. The third lens group is composed of two lenses, which are followed by a double concave negative lens and a meniscus negative lens along the incident direction of the light beam; the fourth lens group is composed of two lenses, and the order along the incident direction of the light beam is: Meniscus positive lenses and biconvex positive lenses. The large-field imaging objective lens according to claim 6, wherein the object-side field curvature of the large-field imaging objective lens is less than 0.75 μm, and the distortion is less than 0.2%. The large-field imaging objective according to claim 3 or 6, wherein the total length of the large-field imaging objective is less than or equal to 850 mm, the object-side numerical aperture is less than or equal to 0.3, and the magnification is -10x. The large field of view imaging objective according to claim 3 or 6, wherein the object-side working distance of the large-field imaging objective lens is greater than 40 mm, and the diameter of the object-side field of view is 8.4 mm. The large field of view imaging objective lens according to claim 2, wherein at least two positive lenses in the first lens group are made of flint glass material; the negative lenses in the two doublet lens groups in the second lens group are both It is made of flint glass material, and the positive lenses in the two doublet lens groups in the second lens group are all made of crown glass material; At least one negative lens in the third lens group is made of flint glass material; at least one positive lens in the fourth lens group is made of flint glass material. The large field of view imaging objective lens according to claim 1, wherein an illumination beam splitter prism is arranged between the first lens group and the diaphragm, and a detector beam splitter prism is arranged between the fourth lens group and an image plane. The large field of view imaging objective lens according to claim 1, wherein the first lens group, the second lens group, the third lens group and the fourth lens group are symmetrically arranged around the diaphragm to form a Object-side and image-side double telecentric light paths. The large field of view imaging objective lens according to claim 1, wherein the large field of view imaging objective lens is suitable for the spectrum of 450nm-650nm.

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