Adjustable magnification double telecentric projection optical system

Abstract

The variable magnification projection optical system of this invention is a dual telecentric optical path, comprising a front lens group, an aperture stop, and a rear lens group along its optical axis. The front lens group includes, from object side to image side, a first lens, a second lens, a third lens, and a fourth lens. The rear lens group includes, from object side to image side, a fifth lens, a sixth lens, a seventh lens, and an eighth lens. It also includes a zoom lens, whose magnification is adjusted by controlling its movement along the optical axis. This invention maintains good dual telecentric projection optical characteristics and good optical imaging quality, and achieves focal length changes by moving a single lens without increasing the number of optical components. This allows for convenient and effective correction or adjustment of the projection magnification of the optical system. All lenses used in the optical system are spherical, excluding aspherical lenses, significantly reducing the difficulty and cost of processing, testing, and calibration.

Description

Technical Field

[0001] This invention relates to an optical system for use in projection lithography machines, and more particularly to an adjustable magnification dual telecentric projection system. Background Technology

[0002] In recent years, projection lithography technology has been widely used in various fields such as circuit manufacturing, machine vision, and semiconductors. With the development of lithography technology, the minimum linewidth of integrated circuits (ICs) in the circuit board production process is getting smaller and smaller, and the requirements for projection lenses are also constantly increasing.

[0003] Because the lens manufacturing process has processing errors, and substrates manufactured by different equipment will also have slight dimensional differences, when performing circuit board scanning and multilayer substrate positioning, it is necessary to correct or adjust the projection magnification of the optical system according to the actual changes in the pattern or magnification to ensure the accuracy of the magnification.

[0004] Dual telecentric lenses can well meet the requirements of photolithography projection lenses. Since both the object-side and image-side optical paths are dual telecentric optical paths, even if the object plane and image plane deviate from the focal plane, the height of the object and image in the direction perpendicular to the optical axis remains unchanged, so the magnification will hardly change.

[0005] Currently, the adjustable magnification dual telecentric lenses that have been announced have a large number of lenses constituting the optical system, and require the simultaneous movement of two or more lenses to complete the magnification adjustment. For example, CN102645749A (published on August 22, 2012) contains 12 lenses, and the magnification is adjusted by moving a set of symmetrical lenses. This places high demands on the mechanical structure design and lens manufacturing costs.

[0006] Therefore, how to provide an optical system that can maintain good telecentric projection optical characteristics and good optical imaging quality, while also being able to conveniently and effectively correct or adjust the projection magnification, is an important technical issue in the industry. Summary of the Invention

[0007] The purpose of this invention is to provide an adjustable magnification dual telecentric projection optical system, so as to facilitate the correction or adjustment of the projection magnification of the optical system when the magnification of the projection lens drifts.

[0008] An adjustable magnification dual telecentric projection optical system employs a dual telecentric structure, with the principal rays on the object and image sides parallel to the optical axis. It includes a front lens group, an aperture stop, and a rear lens group arranged sequentially from the object to the image side. The front lens group consists of a first positive power lens group. The aperture stop is located on the confocal surface of the front and rear lens groups. The rear lens group consists of a second positive power lens group, and adjusting the positional relationship of the corresponding lenses in the rear lens group constitutes a zoom lens, thereby adjusting the magnification of the optical system.

[0009] As a further improvement to the above technical solution:

[0010] The front and rear lens groups consist of eight lenses. The front lens group is composed of the first, second, third, and fourth lenses, while the rear lens group is composed of the fifth, sixth, seventh, and eighth lenses.

[0011] The first, second, fourth, fifth, seventh, and eighth lenses are convex lenses, while the third and sixth lenses are concave lenses. Furthermore, moving the seventh lens in the rear lens group can form a zoom lens, thereby adjusting the magnification of the optical system.

[0012] The third and sixth lenses are biconcave lenses.

[0013] The objective lens system, consisting of the front lens group, aperture stop, and rear lens group, operates in the near-ultraviolet band.

[0014] The first, second, fourth, fifth, seventh, and eighth lenses are made of crown glass or light crown glass, and their material properties meet the following requirements:

[0015] 1.43 <Nd<1.65

[0016] 55.00 <Vd<85.00

[0017] Where Nd is the refractive index of the first, second, fourth, fifth, seventh, and eighth lenses; and Vd is their corresponding dispersion coefficient.

[0018] The third and sixth lenses are made of flint glass or lightweight flint glass, and their material properties meet the following requirements:

[0019] 1.53 <Nd<1.64

[0020] 35.00 <Vd<46.00

[0021] Where Nd is the refractive index of the third and sixth lenses; Vd is their corresponding dispersion coefficient.

[0022] All lens surfaces in the optical system are either spherical or planar.

[0023] The working distance between the object side and the image side of the optical system is greater than 100mm.

[0024] The optical system satisfies the following relationship:

[0025] Relationship 1: -0.65 < F3 / F4 < -0.3;

[0026] Relationship 2: -0.65 < F3 / Fo < 0;

[0027] Relationship 3: -0.18 < F6 / F7 < -0.1;

[0028] Relationship 4: -0.08 < F6 / Fi < -0.04;

[0029] Wherein, F3 is the focal length of the third lens; F4 is the focal length of the fourth lens; Fo is the combined focal length of the front lens group; F6 is the focal length of the sixth lens; F7 is the focal length of the seventh lens; and Fi is the combined focal length of the rear lens group.

[0030] The optical system satisfies the following relationship:

[0031] Relationship 5: 0 < R9 / R10 < 0.45;

[0032] Relationship 6: -2.5 < R14 / T14 < -1.26;

[0033] Wherein, R9 is the radius of curvature on the object side of the fifth lens; R10 is the radius of curvature on the image side of the fifth lens; R14 is the radius of curvature on the image side of the seventh lens; and T14 is the aperture on the image side of the seventh lens.

[0034] The optical system satisfies the following relationship:

[0035] Relationship 7: 30.2 < T1 < 39.5;

[0036] Relationship 8: 64.5 < T16 < 70.5;

[0037] Wherein, T1 is the light-transmitting aperture on the object side of the first lens; T16 is the light-transmitting aperture on the image side of the eighth lens.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] This invention can achieve focal length changes by moving a single lens without increasing the number of optical components, while maintaining good telecentric projection optical characteristics and good optical imaging quality. This allows for convenient and effective correction or adjustment of the projection magnification of the optical system. All lenses used in the optical system are spherical and do not include aspherical lenses, which greatly reduces the difficulty and cost of processing, testing and calibration.

[0040] 1. The projection optical system of the present invention has a lens group consisting of 8 lenses. Without the introduction of aspherical lenses, it can effectively correct various aberrations and reduce the cost of lens processing, testing and calibration.

[0041] 2. The object-side working distance and image-side working distance of the projection optical system of the present invention are both greater than 100mm, which leaves sufficient margin for the mechanical design of the stage part of the projection lithography system.

[0042] 3. When adjusting the magnification, the projection optical system of the present invention can conveniently and effectively correct or adjust the projection magnification of the optical system by moving a zoom lens while maintaining good dual telecentric projection optical characteristics and good optical imaging quality. Attached Figure Description

[0043] Figure 1 The diagram shown is a schematic representation of the projection optical system in a specific embodiment of the present invention.

[0044] Figure 2a As shown Figure 1 A schematic diagram showing the percentage distortion of the projection magnification of the projection optical system at zoom position 1.

[0045] Figure 2b As shown Figure 1 A schematic diagram showing the percentage distortion of the projection magnification of the projection optical system at zoom position 2.

[0046] Figure 3a As shown Figure 1 A schematic diagram of wavefront aberration in a projection optical system at zoom position 1 with a projection magnification of 1.

[0047] Figure 3b As shown Figure 1 A schematic diagram of wavefront aberration in a central projection optical system at zoom position 2.

[0048] Figure 4 The diagram shown is a schematic representation of the projection optical system in a specific embodiment two of the present invention.

[0049] Figure 5a As shown Figure 4 A schematic diagram showing the percentage distortion of the projection magnification of the projection optical system at zoom position 1.

[0050] Figure 5b As shown Figure 4 A schematic diagram showing the percentage distortion of the projection magnification of the projection optical system at zoom position 2.

[0051] Figure 6a As shown Figure 4 A schematic diagram of wavefront aberration in a projection optical system at zoom position 1 with a projection magnification of 1.

[0052] Figure 6b As shown Figure 4 A schematic diagram of wavefront aberration in a central projection optical system at zoom position 2.

[0053] Figure 7 The diagram shown is a schematic representation of the projection optical system in a specific embodiment three of the present invention.

[0054] Figure 8a As shown Figure 7 A schematic diagram showing the percentage distortion of the projection magnification of the projection optical system at zoom position 1.

[0055] Figure 8b As shown Figure 7 A schematic diagram showing the percentage distortion of the projection magnification of the projection optical system at zoom position 2.

[0056] Figure 9a As shown Figure 7 A schematic diagram of wavefront aberration in a projection optical system at zoom position 1 with a projection magnification of 1.

[0057] Figure 9b As shown Figure 7 A schematic diagram of wavefront aberration in a central projection optical system at zoom position 2.

[0058] Figure 10 The diagram shown is a schematic representation of the projection optical system in a specific embodiment four of the present invention.

[0059] Figure 11a As shown Figure 10 A schematic diagram showing the percentage distortion of the projection magnification of the projection optical system at zoom position 1.

[0060] Figure 11b As shown Figure 10 A schematic diagram showing the percentage distortion of the projection magnification of the projection optical system at zoom position 2.

[0061] Figure 12a As shown Figure 10 A schematic diagram of wavefront aberration in a projection optical system at zoom position 1 with a projection magnification of 1.

[0062] Figure 12b As shown Figure 10 A schematic diagram of wavefront aberration in a central projection optical system at zoom position 2.

[0063] Figure 13 The diagram shown is a schematic representation of the projection optical system in a specific embodiment five of the present invention.

[0064] Figure 14a As shown Figure 13 A schematic diagram showing the percentage distortion of the projection magnification of the projection optical system at zoom position 1.

[0065] Figure 14b As shown Figure 13 A schematic diagram showing the percentage distortion of the projection magnification of the projection optical system at zoom position 2.

[0066] Figure 15a As shown Figure 13 A schematic diagram of wavefront aberration in a projection optical system at zoom position 1 with a projection magnification of 1.

[0067] Figure 15b As shown Figure 13 A schematic diagram of wavefront aberration in a central projection optical system at zoom position 2.

[0068] Wherein: 1. Front lens group; 2. Aperture stop; 3. Rear lens group; L1, First lens; L2, Second lens; L3, Third lens; L4, Fourth lens; L5, Fifth lens; L6, Sixth lens; L7, Seventh lens; L8, Eighth lens; R9, Radius of curvature on the object side of the fifth lens; R10, Radius of curvature on the image side of the fifth lens; R14, Radius of curvature on the image side of the seventh lens. Detailed Implementation

[0069] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0070] Example 1:

[0071] This embodiment provides a projection optical system, which sequentially includes a front lens group 1, an aperture stop 2, and a rear lens group 3 from the object plane side to the image plane side. The combined rear focal point of the front lens group 1 and the combined front focal point of the rear lens group 3 coincide with the center of the aperture stop 2, forming a double telecentric optical structure.

[0072] like Figure 1 As shown, the dual telecentric exposure lens includes a front lens group 1, an aperture stop 2, and a rear lens group 3 arranged in sequence, with the aperture stop 2 located between the front lens group 1 and the rear lens group 3.

[0073] The projection optical system provided by this invention forms a double telecentric optical structure at the object plane and the image plane. Because the central lines of the light cones in the object space and image space, i.e., the principal rays, are parallel to the optical axis, the magnification is guaranteed not to change as the object plane and image plane move along the optical axis. Thus, even if the object plane and image plane deviate from the focal plane, the height of the object and image in the direction perpendicular to the optical axis remains unchanged, so the magnification will not change.

[0074] See Figure 1 As shown, the projection optical system consists of eight lenses in sequence from the object plane side: a front lens group 1, an aperture stop 2, and a rear lens group 3. The front lens group 1 has positive optical power, and the rear lens group 3 has positive optical power.

[0075] The front lens group 1 comprises four lenses, arranged from object side to image side as follows: first lens L1, second lens L2, third lens L3, and fourth lens L4. The first lens L1 is a biconvex lens with positive optical power; the second lens L2 is a biconvex lens with positive optical power; the third lens L3 is a biconcave lens with negative optical power; and the fourth lens L4 is a meniscus lens with positive optical power, its object side being convex and its image side being concave.

[0076] The first lens L1 is a convex lens with positive optical power. Its main function is to maintain the object-side telecentric optical path structure, while balancing the spherical aberration, coma, and astigmatism generated by the front lens group 1.

[0077] The second lens L2 is a convex lens with positive optical power. Its main function is to correct the chromatic aberration of the upper light rays and to produce spherical aberration, coma, and astigmatism that are opposite to those of the third lens L3 (concave lens), thus balancing the overall aberrations of the optical system.

[0078] The third lens, L3, is a concave lens with negative optical power. Its main function is to generate positive spherical aberration, which can be used to correct the negative spherical aberration generated by other convex lenses in the optical system. Simultaneously, since the projection optical system of this invention uses broadband illumination, high-refractive-index and low-Abbe-number glass, such as flint glass or light flint glass, is selected to form a double concave lens, generating axial and transverse chromatic aberration opposite to those of the convex lenses, which can correct the chromatic aberration of the optical system.

[0079] The fourth lens, L4, is a convex lens with positive optical power. Its main function is to generate less negative spherical aberration, negative coma, and distortion, thus balancing the overall aberrations of the front lens group 1.

[0080] The rear lens group 3 includes four lenses, arranged from the object side to the image side as follows: fifth lens L5, sixth lens L6, seventh lens L7, and eighth lens L8; the fifth lens L5 is a meniscus lens with positive optical power, its object side is convex, and its image side is concave; the sixth lens L6 is a biconcave lens with negative optical power; the seventh lens L7 is a meniscus lens with positive optical power, its object side is concave, and its image side is convex; the eighth lens L8 is a biconvex lens with positive optical power.

[0081] The fifth lens, L5, is a convex lens with positive optical power, while the sixth lens, L6, is a concave lens with negative optical power. Lenses L5 and L6 are positioned close to aperture stop 2, and their aperture sizes are similar. The upper and lower rays from the on-axis and peripheral fields of view, along with the principal ray, converge at the aperture stop and pass through the same area of ​​the apertures of lenses L5 and L6, simultaneously correcting both on-axis and off-axis chromatic aberration. Furthermore, lens L6 is the only concave lens in the rear lens group 3, producing spherical aberration, coma, field curvature, and distortion in the opposite direction to those of the convex lenses. This helps to avoid excessive high-order spherical aberration and field curvature, balancing the overall aberrations of the optical system.

[0082] Preferably, the seventh lens L7 is a zoom lens group. Since the surface radius of the zoom lens is large, its contribution to aberrations is small, and the additional aberrations introduced during position adjustment can be ignored. While keeping the object plane and image plane positions unchanged, the focal length of the optical system can be changed by moving the zoom lens group forward and backward. This allows for convenient and effective correction or adjustment of the projection magnification of the optical system while maintaining good telecentric projection optical characteristics and good optical imaging quality.

[0083] The eighth lens, L8, is a convex lens with positive optical power, which can maintain a good image-side telecentric optical path structure.

[0084] The internal focal length of the projection optical system in this embodiment of the invention satisfies the following relationship:

[0085] Relation 1: -0.65 < F3 / F4 < -0.3; Relation 2: -0.65 < F3 / Fo < 0; Relation 3: -0.18 < F6 / F7 < -0.1;

[0086] Relationship 4: -0.08 < F6 / Fi < -0.04;

[0087] Wherein, F3: focal length of the third lens L3; F4: focal length of the fourth lens L4; Fo: combined focal length of the front lens group 1; F6: focal length of the sixth lens L6; F7: focal length of the seventh lens L7; Fi: combined focal length of the rear lens group 3.

[0088] The main function of Equations 1 and 2 is to maintain the ratio of optical power of the third lens L3 to the fourth lens L4, and to evenly distribute the optical power of the concave and convex lenses in the front lens group 1. This avoids design results with too small a radius of curvature and too large an incident angle of the upper light rays, which would produce too much spherical aberration, coma, astigmatism and distortion on a single surface.

[0089] The main functions of Equations 3 and 4 are to rationally allocate the optical power ratio of the concave lenses in the rear lens group 3, balance the overall distortion and chromatic aberration of the optical system, control the optical power of the seventh lens L7 zoom lens so that it can share the optical power of the sixth lens L6, and not introduce too many aberrations into the optical system when the seventh lens L7 zooms.

[0090] The radius of curvature and aperture of the projection optical system in this embodiment of the invention satisfy the following relationship:

[0091] Relation 5: 0 < R9 / R10 < 0.45; Relation 6: -2.5 < R14 / T14 < -1.26;

[0092] Wherein, R9: the radius of curvature on the object side of the fifth lens L5; R10: the radius of curvature on the image side of the fifth lens L5; R14: the radius of curvature on the image side of the seventh lens L7; T14: the aperture on the image side of the seventh lens L7.

[0093] The main function of relation 5 is to control the optical power of the fifth lens L5, which is closest to the aperture stop 2, so that it can correct chromatic aberration without introducing too many other aberrations.

[0094] The main function of relation 6 is to control the optical power of the zoom lens in the rear lens group 3, maintain the absolute value difference between the curvature radius of curvature of the seventh lens L7 on the image side and the curvature radius of curvature of the eighth lens L8 on the object side, so that the seventh lens L7 and the eighth lens L8 share the optical power and reduce the aberration of a single lens.

[0095] The air gap inside the projection optical system in this embodiment of the invention satisfies the following relationship:

[0096] Relationship 7: 30.2 < T1 < 39.5; Relationship 8: 64.5 < T16 < 70.5;

[0097] Wherein, T1: the light-transmitting aperture on the object side of the first lens L1; T16: the light-transmitting aperture on the image side of the eighth lens L8.

[0098] The main function of relation 7 is to control the object distance to be greater than 100mm while maintaining a good object-side telecentric optical path.

[0099] The main function of relation 8 is to control the image distance to be greater than 100mm while maintaining a good image-side telecentric optical path.

[0100] In this way, the spherical aberration, astigmatism, coma, distortion, transverse chromatic aberration, and axial chromatic aberration of the optical system are automatically corrected to zero, and a dual telecentric optical path is formed between the object and image sides.

[0101] The design parameters of the projection optical system in this embodiment are shown in Table 1: object-side NA is 0.06, object-side field of view height is 11.3 mm, magnification is -2.74986, object-side working distance is 103.46 mm, image-side working distance is 132.76 mm, and object-image conjugate distance is 500.00 mm. For ease of optical processing and inspection, and to reduce costs, all optical elements in this invention are spherical or planar, with no aspherical elements.

[0102] Numerical aperture (NA) 0.06 Object-side field of view (line field of view) 11.3mm Magnification -2.74986 Working distance of objects 103.46mm Image working distance 132.67mm Object-image conjugate distance 500.00mm

[0103] Table 1

[0104] Table 2 provides the specific parameters of each lens in the projection optical system of this embodiment. The "Surface Number" column indicates the number of each surface from the object plane to the image plane; the "Radius of Curvature (mm)" column gives the radius of curvature of the corresponding sphere or plane for each surface; the "Thickness / Spacing (mm)" column gives the axial distance between two adjacent surfaces. If the two surfaces belong to the same lens, the value of "Thickness / Spacing" represents the center thickness of the lens; otherwise, it represents the distance from the object plane or image plane to the lens or the air gap between adjacent lenses; "N" represents the distance between adjacent surfaces. d "One column indicates the refractive index of each lens between the object plane and the image plane; "V d The column "Dispersion coefficient" indicates the dispersion coefficient of the corresponding lens; the column "Aperture (mm)" indicates the aperture value of the corresponding surface.

[0105] Apart from the lens, this optical system has a 3mm thick flat protective glass at a distance of 0.48mm from the object surface, which is not involved in the optical system design.

[0106] An aperture stop 2 is also provided between surface 11 and surface 13. Changes in its aperture size will affect the imaging effect of the projection optical system.

[0107]

[0108]

[0109] Table 2

[0110] Table 3 shows the relationship between the projection magnification of the projection optical system in this embodiment and the displacement of the seventh lens L7. As can be seen from Table 3, the projection magnification of the optical system can be adjusted between -2.74986 and -2.75201 by adjusting the position of the seventh lens L7.

[0111] Zoom position 1 Zoom position 2 Working distance of objects 103.46 103.46 Image working distance 132.67 132.49 Object-image conjugate distance 500.00 500.29 Spacing 16 113.88 113.89 Spacing 18 2.75 3.21 L7 displacement 0 -0.011 Projection magnification 2.74986 2.75201

[0112] Table 3

[0113] Table 4 shows the calculation results of the relational formulas of the symmetrical dual telecentric projection optical system in this embodiment. It can be seen from the calculation results that the present invention can effectively satisfy relational formulas (1) to (9).

[0114] Relation 1 F3 / F4 = -0.376 Relation 2 F3 / Fo = -0.498 Relation 3 F6 / F7 = -0.107 Relation 4 F6 / Fi = -0.062 Relation 5 R9 / R10 = 0.338 Relation 6 R14 / T14= -1.409 Relation 7 T1＝ 34.939 Relation 8 T16＝ 67.995

[0115] Table 4

[0116] Figure 2a This is a schematic diagram showing the percentage distortion of the projection magnification of the projection lens system at zoom position 1. Figure 2b This diagram illustrates the percentage distortion of the projection lens system at zoom position 2, showing that the relative distortion of the projection system is better than 0.002%, and the change in distortion is minimal when the projection magnification is increased or decreased.

[0117] Figure 3a This is a schematic diagram of wavefront aberration of the projection lens system at zoom position 1. Figure 3b The diagram shows the wavefront aberration of the projection lens system at zoom position 2, indicating that the projection system has good image quality and the wavefront aberration is better than ±0.05λ. When the projection magnification is increased or decreased, the change in wavefront aberration is very small, within ±0.001λ.

[0118] Example 2:

[0119] The preferred embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0120] like Figure 4 As shown, this is a preferred second embodiment of the present invention. The dual telecentric exposure lens includes a front lens group 1, an aperture stop 2, and a rear lens group 3 arranged sequentially, with the aperture stop 2 located between the front lens group 1 and the rear lens group 3.

[0121] The projection optical system provided by this invention forms a double telecentric optical structure at the object plane and the image plane. Because the central lines of the light cones in the object space and image space, i.e., the principal rays, are parallel to the optical axis, the magnification is guaranteed not to change as the object plane and image plane move along the optical axis. Thus, even if the object plane and image plane deviate from the focal plane, the height of the object and image in the direction perpendicular to the optical axis remains unchanged, so the magnification will not change.

[0122] See Figure 4 As shown, the projection optical system consists of eight lenses in sequence from the object plane side: a front lens group 1, an aperture stop 2, and a rear lens group 3. The front lens group 1 has positive optical power, and the rear lens group 3 has positive optical power.

[0123] The front lens group 1 comprises four lenses, arranged from object side to image side as follows: first lens L1, second lens L2, third lens L3, and fourth lens L4. The first lens L1 is a biconvex lens with positive optical power; the second lens L2 is a biconvex lens with positive optical power; the third lens L3 is a biconcave lens with negative optical power; and the fourth lens L4 is a meniscus lens with positive optical power, its object side being convex and its image side being concave.

[0124] The first lens L1 is a convex lens with positive optical power. Its main function is to maintain the object-side telecentric optical path structure, while balancing the spherical aberration, coma, and astigmatism generated by the front lens group 1.

[0125] The second lens L2 is a convex lens with positive optical power. Its main function is to correct the chromatic aberration of the upper light rays and to produce spherical aberration, coma, and astigmatism that are opposite to those of the third lens L3 (concave lens), thus balancing the overall aberrations of the optical system.

[0126] The third lens, L3, is a concave lens with negative optical power. Its main function is to generate positive spherical aberration, which can be used to correct the negative spherical aberration generated by other convex lenses in the optical system. Simultaneously, since the projection optical system of this invention uses broadband illumination, high-refractive-index and low-Abbe-number glass, such as flint glass or light flint glass, is selected to form a double concave lens, generating axial and transverse chromatic aberration opposite to those of the convex lenses, which can correct the chromatic aberration of the optical system.

[0127] The fourth lens, L4, is a convex lens with positive optical power. Its main function is to generate less negative spherical aberration, negative coma, and distortion, thus balancing the overall aberrations of the front lens group 1.

[0128] The rear lens group 3 includes four lenses, arranged from the object side to the image side as follows: fifth lens L5, sixth lens L6, seventh lens L7, and eighth lens L8; the fifth lens L5 is a meniscus lens with positive optical power, its object side is convex, and its image side is concave; the sixth lens L6 is a biconcave lens with negative optical power; the seventh lens L7 is a biconvex lens with positive optical power; and the eighth lens is a biconvex lens L8 with positive optical power.

[0129] The fifth lens, L5, is a convex lens with positive optical power, while the sixth lens, L6, is a concave lens with negative optical power. Lenses L5 and L6 are positioned close to aperture stop 2, and their aperture sizes are similar. The upper and lower rays from the on-axis and peripheral fields of view, along with the principal ray, converge at the aperture stop and pass through the same area of ​​the apertures of both lenses, simultaneously correcting on-axis and off-axis chromatic aberration. Furthermore, as the only concave lens in the rear lens group 3, lens L6 produces spherical aberration, coma, field curvature, and distortion in the opposite direction to those of the convex lenses. This helps to avoid excessive high-order spherical aberration and field curvature, balancing the overall aberrations of the optical system.

[0130] Preferably, the seventh lens L7 is a zoom lens group. Since the surface radius of the zoom lens is large, its contribution to aberrations is small, and the additional aberrations introduced during position adjustment can be ignored. While keeping the object plane and image plane positions unchanged, the focal length of the optical system can be changed by moving the zoom lens group forward and backward. This allows for convenient and effective correction or adjustment of the projection magnification of the optical system while maintaining good telecentric projection optical characteristics and good optical imaging quality.

[0131] The eighth lens, L8, is a convex lens with positive optical power, which can maintain a good image-side telecentric optical path structure.

[0132] The internal focal length of the projection optical system in this embodiment of the invention satisfies the following relationship:

[0133] Relationship 1: -0.65 < F3 / F4 < -0.3; Relationship 2: -0.65 < F3 / Fo < 0;

[0134] Relationship 3: -0.18 < F6 / F7 < -0.1; Relationship 4: -0.08 < F6 / Fi < -0.04;

[0135] Wherein, F3: focal length of the third lens L3; F4: focal length of the fourth lens L4; Fo: combined focal length of the front lens group 1; F6: focal length of the sixth lens L6; F7: focal length of the seventh lens L7; Fi: combined focal length of the rear lens group 3.

[0136] The main function of Equations 1 and 2 is to maintain the ratio of optical power of the third lens L3 to the fourth lens L4, and to evenly distribute the optical power of the concave and convex lenses in the front lens group 1. This avoids design results with too small a radius of curvature and too large an incident angle of the upper light rays, which would produce too much spherical aberration, coma, astigmatism and distortion on a single surface.

[0137] The main functions of Equations 3 and 4 are to rationally allocate the optical power ratio of the concave lenses in the rear lens group 3, balance the overall distortion and chromatic aberration of the optical system, control the optical power of the seventh lens L7 zoom lens so that it can share the optical power of the sixth lens L6, and not introduce too many aberrations into the optical system when the seventh lens L7 zooms.

[0138] The radius of curvature and aperture of the projection optical system in this embodiment of the invention satisfy the following relationship:

[0139] Relationship 5: 0 < R9 / R10 < 0.45;

[0140] Relationship 6: -2.5 < R14 / T14 < -1.26;

[0141] Wherein, R9: the radius of curvature on the object side of the fifth lens L5; R10: the radius of curvature on the image side of the fifth lens L5; R14: the radius of curvature on the image side of the seventh lens L7; T14: the aperture on the image side of the seventh lens L7.

[0142] The main function of relation 5 is to control the optical power of the fifth lens L5, which is closest to the aperture stop 2, so that it can correct chromatic aberration without introducing too many other aberrations.

[0143] The main function of relation 6 is to control the optical power of the zoom lens in the rear lens group 3, maintain the absolute value difference between the curvature radius of curvature of the seventh lens L7 on the image side and the curvature radius of curvature of the eighth lens L8 on the object side, so that the seventh lens L7 and the eighth lens L8 share the optical power and reduce the aberration of a single lens.

[0144] The air gap inside the projection optical system in this embodiment of the invention satisfies the following relationship:

[0145] Relationship 7: 30.2 < T1 < 39.5; Relationship 8: 64.5 < T16 < 70.5;

[0146] Wherein, T1: the light-transmitting aperture on the object side of the first lens L1; T16: the light-transmitting aperture on the image side of the eighth lens L8.

[0147] The main function of relation 7 is to control the object distance to be greater than 100mm while maintaining a good object-side telecentric optical path.

[0148] The main function of relation 8 is to control the image distance to be greater than 100mm while maintaining a good image-side telecentric optical path.

[0149] In this way, the spherical aberration, astigmatism, coma, distortion, transverse chromatic aberration, and axial chromatic aberration of the optical system are automatically corrected to zero, and a dual telecentric optical path is formed between the object and image sides.

[0150] The design parameters of the projection optical system in this embodiment are shown in Table 5: object-side NA is 0.06, object-side field of view height is 11.3 mm, magnification is -2.74986, object-side working distance is 110.30 mm, image-side working distance is 110.28 mm, and object-image conjugate distance is 498.36 mm. For ease of optical processing and inspection, and to reduce costs, all optical elements in this invention are spherical or planar, with no aspherical elements.

[0151] Numerical aperture (NA) 0.06 Object-side field of view (line field of view) 11.3mm Magnification -2.74986 Working distance of objects 111.30mm Image working distance 110.28mm Object-image conjugate distance 498.36mm

[0152] Table 5

[0153] Table 6 provides the specific parameters of each lens in the projection optical system of this embodiment. The "Surface Number" column indicates the number of each surface from the object plane to the image plane; the "Radius of Curvature (mm)" column gives the radius of curvature of the corresponding sphere or plane for each surface; the "Thickness / Spacing (mm)" column gives the axial distance between two adjacent surfaces. If the two surfaces belong to the same lens, the value of "Thickness / Spacing" represents the center thickness of the lens; otherwise, it represents the distance from the object plane or image plane to the lens or the air gap between adjacent lenses; "N" represents the distance between adjacent surfaces. d "One column indicates the refractive index of each lens between the object plane and the image plane; "V d The column "Dispersion coefficient" indicates the dispersion coefficient of the corresponding lens; the column "Aperture (mm)" indicates the aperture value of the corresponding surface. In addition to the lens, this optical system has a 3mm thick flat protective glass at a distance of 0.48mm from the object surface, which is not involved in the optical system design.

[0154] An aperture stop 2 is also provided between surface 11 and surface 13. Changes in its aperture size will affect the imaging effect of the projection optical system.

[0155] Surface serial number Radius of curvature (mm) Thickness / Spacing (mm) <![CDATA[N d ]]> <![CDATA[V d ]]> Light aperture (mm) surface 0 1 unlimited 0.48 22.60 2 unlimited 3.00 1.49 65.81 22.66 3 unlimited 109.82 22.89 4 138.93 6.00 1.52 64.21 36.02 5 -252.46 1.00 35.96 6 72.67 8.00 1.52 64.21 35.59 7 -64.45 3.02 34.78 8 -57.02 3.00 1.58 40.92 32.57 9 93.33 31.56 31.35 10 63.95 5.00 1.52 64.21 28.60 11 2020.78 53.20 27.86 Aperture stop 2 1.00 10.70 13 28.74 8.00 1.52 64.21 10.98 14 83.47 16.44 10.88 15 -29.09 3.00 1.58 40.92 11.63 16 45.60 101.34 12.37 17 2829.73 11.00 1.52 64.21 60.70 18 -152.41 14.22 62.96 19 148.97 9.00 1.52 64.21 68.01 20 -1050.08 110.28 67.95 Image unlimited -0.07 62.21

[0156] Table 6

[0157] Table 7 shows the relationship between the projection magnification of the projection optical system in this embodiment and the displacement of the seventh lens L7. As can be seen from Table 7, the projection magnification of the optical system can be adjusted between -2.74986 and -2.75201 by adjusting the position of the seventh lens L7.

[0158]

[0159]

[0160] Table 7

[0161] Table 8 shows the calculation results of the relational formulas of the symmetrical dual telecentric projection optical system in this embodiment. It can be seen from the calculation results that the present invention can effectively satisfy relational formulas (1) to (9).

[0162] Relation 1 F3 / F4 = -0.465 Relation 2 F3 / Fo = -0.354 Relation 3 F6 / F7 = -0.106 Relation 4 F6 / Fi = -0.070 Relation 5 R9 / R10 = 0.032 Relation 6 R14 / T14= -2.421 Relation 7 T1＝ 36.020 Relation 8 T16＝ 67.952

[0163] Table 8

[0164] Figure 5a This is a schematic diagram showing the percentage distortion of the projection magnification of the projection lens system at zoom position 1. Figure 5bThis diagram illustrates the percentage distortion of the projection lens system at zoom position 2, showing that the relative distortion of the projection system is better than 0.002%, and the change in distortion is minimal when the projection magnification is increased or decreased.

[0165] Figure 6a This is a schematic diagram of wavefront aberration of the projection lens system at zoom position 1. Figure 6b The diagram shows the wavefront aberration of the projection lens system at zoom position 2, indicating that the projection system has good image quality and the wavefront aberration is better than ±0.03λ. When the projection magnification is increased or decreased, the change in wavefront aberration is very small, within ±0.003λ.

[0166] Example 3:

[0167] The preferred embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0168] like Figure 7 As shown, this is a preferred third embodiment of the present invention. The dual telecentric exposure lens includes a front lens group 1, an aperture stop 2, and a rear lens group 3 arranged sequentially, with the aperture stop 2 located between the front lens group 1 and the rear lens group 3.

[0169] The projection optical system provided by this invention forms a double telecentric optical structure at the object plane and the image plane. Because the central lines of the light cones in the object space and image space, i.e., the principal rays, are parallel to the optical axis, the magnification is guaranteed not to change as the object plane and image plane move along the optical axis. Thus, even if the object plane and image plane deviate from the focal plane, the height of the object and image in the direction perpendicular to the optical axis remains unchanged, so the magnification will not change.

[0170] See Figure 7 As shown, the projection optical system consists of eight lenses in sequence from the object plane side: a front lens group 1, an aperture stop 2, and a rear lens group 3. The front lens group 1 has positive optical power, and the rear lens group 3 has positive optical power.

[0171] The front lens group 1 comprises four lenses, arranged from object side to image side as follows: first lens L1, second lens L2, third lens L3, and fourth lens L4. The first lens L1 is a biconvex lens with positive optical power; the second lens L2 is a biconvex lens with positive optical power; the third lens L3 is a biconcave lens with negative optical power; and the fourth lens L4 is a meniscus lens with positive optical power, its object side being convex and its image side being concave.

[0172] The first lens L1 is a convex lens with positive optical power. Its main function is to maintain the object-side telecentric optical path structure, while balancing the spherical aberration, coma, and astigmatism generated by the front lens group 1.

[0173] The second lens L2 is a convex lens with positive optical power. Its main function is to correct the chromatic aberration of the upper light rays and to produce spherical aberration, coma, and astigmatism that are opposite to those of the third lens L3 (concave lens), thus balancing the overall aberrations of the optical system.

[0174] The third lens, L3, is a concave lens with negative optical power. Its main function is to generate positive spherical aberration, which can be used to correct the negative spherical aberration generated by other convex lenses in the optical system. Simultaneously, since the projection optical system of this invention uses broadband illumination, high-refractive-index and low-Abbe-number glass, such as flint glass or light flint glass, is selected to form a double concave lens, generating axial and transverse chromatic aberration opposite to those of the convex lenses, which can correct the chromatic aberration of the optical system.

[0175] The fourth lens, L4, is a convex lens with positive optical power. Its main function is to generate less negative spherical aberration, negative coma, and distortion, thus balancing the overall aberrations of the front lens group 1.

[0176] The rear lens group 3 includes four lenses, arranged from the object side to the image side as follows: fifth lens L5, sixth lens L6, seventh lens L7, and eighth lens L8; the fifth lens L5 is a meniscus lens with positive optical power, its object side is convex, and its image side is concave; the sixth lens L6 is a biconcave lens with negative optical power; the seventh lens L7 is a biconvex lens with positive optical power; and the eighth lens is a biconvex lens L8 with positive optical power.

[0177] The fifth lens, L5, is a convex lens with positive optical power, while the sixth lens, L6, is a concave lens with negative optical power. Lenses L5 and L6 are positioned close to aperture stop 2, and their aperture sizes are similar. The upper and lower rays from the on-axis and peripheral fields of view, along with the principal ray, converge at the aperture stop and pass through the same area of ​​the apertures of both lenses, simultaneously correcting on-axis and off-axis chromatic aberration. Furthermore, as the only concave lens in the rear lens group 3, lens L6 produces spherical aberration, coma, field curvature, and distortion in the opposite direction to those of the convex lenses. This helps to avoid excessive high-order spherical aberration and field curvature, balancing the overall aberrations of the optical system.

[0178] Preferably, the seventh lens L7 is a zoom lens group. Since the surface radius of the zoom lens is large, its contribution to aberrations is small, and the additional aberrations introduced during position adjustment can be ignored. While keeping the object plane and image plane positions unchanged, the focal length of the optical system can be changed by moving the zoom lens group forward and backward. This allows for convenient and effective correction or adjustment of the projection magnification of the optical system while maintaining good telecentric projection optical characteristics and good optical imaging quality.

[0179] The eighth lens, L8, is a convex lens with positive optical power, which can maintain a good image-side telecentric optical path structure.

[0180] The internal focal length of the projection optical system in this embodiment of the invention satisfies the following relationship:

[0181] Relationship 1: -0.65 < F3 / F4 < -0.3; Relationship 2: -0.65 < F3 / Fo < 0;

[0182] Relationship 3: -0.18 < F6 / F7 < -0.1; Relationship 4: -0.08 < F6 / Fi < -0.04;

[0183] Wherein, F3: focal length of the third lens L3; F4: focal length of the fourth lens L4; Fo: combined focal length of the front lens group 1; F6: focal length of the sixth lens L6; F7: focal length of the seventh lens L7; Fi: combined focal length of the rear lens group 3.

[0184] The main function of Equations 1 and 2 is to maintain the ratio of optical power of the third lens L3 to the fourth lens L4, and to evenly distribute the optical power of the concave and convex lenses in the front lens group 1. This avoids design results with too small a radius of curvature and too large an incident angle of the upper light rays, which would produce too much spherical aberration, coma, astigmatism and distortion on a single surface.

[0185] The main functions of Equations 3 and 4 are to rationally allocate the optical power ratio of the concave lenses in the rear lens group 3, balance the overall distortion and chromatic aberration of the optical system, control the optical power of the seventh lens L7 zoom lens so that it can share the optical power of the sixth lens L6, and not introduce too many aberrations into the optical system when the seventh lens L7 zooms.

[0186] The radius of curvature and aperture of the projection optical system in this embodiment of the invention satisfy the following relationship:

[0187] Relation 5: 0 < R9 / R10 < 0.45; Relation 6: -2.5 < R14 / T14 < -1.26;

[0188] Wherein, R9: the radius of curvature on the object side of the fifth lens L5; R10: the radius of curvature on the image side of the fifth lens L5; R14: the radius of curvature on the image side of the seventh lens L7; T14: the aperture on the image side of the seventh lens L7.

[0189] The main function of relation 5 is to control the optical power of the fifth lens L5, which is closest to the aperture stop 2, so that it can correct chromatic aberration without introducing too many other aberrations.

[0190] The main function of relation 6 is to control the optical power of the zoom lens in the rear lens group 3, maintain the absolute value difference between the curvature radius of curvature of the seventh lens L7 on the image side and the curvature radius of curvature of the eighth lens L8 on the object side, so that the seventh lens L7 and the eighth lens L8 share the optical power and reduce the aberration of a single lens.

[0191] The air gap inside the projection optical system in this embodiment of the invention satisfies the following relationship:

[0192] Relationship 7: 30.2 < T1 < 39.5; Relationship 8: 64.5 < T16 < 70.5;

[0193] Wherein, T1: the light-transmitting aperture on the object side of the first lens L1; T16: the light-transmitting aperture on the image side of the eighth lens L8.

[0194] The main function of relation 7 is to control the object distance to be greater than 100mm while maintaining a good object-side telecentric optical path.

[0195] The main function of relation 8 is to control the image distance to be greater than 100mm while maintaining a good image-side telecentric optical path.

[0196] In this way, the spherical aberration, astigmatism, coma, distortion, transverse chromatic aberration, and axial chromatic aberration of the optical system are automatically corrected to zero, and a dual telecentric optical path is formed between the object and image sides.

[0197] The design parameters of the projection optical system in this embodiment are shown in Table 9: object-side NA is 0.06, object-side field of view height is 11.3 mm, magnification is -2.74985, object-side working distance is 113.24 mm, image-side working distance is 110.10 mm, and object-image conjugate distance is 498.72 mm. For ease of optical processing and inspection, and to reduce costs, all optical elements in this invention are spherical or planar, with no aspherical elements.

[0198] Numerical aperture (NA) 0.06 Object-side field of view (line field of view) 11.3mm Magnification -2.74985 Working distance of objects 113.24mm Image working distance 110.10mm Object-image conjugate distance 498.72mm

[0199] Table 9

[0200] Table 10 provides the specific parameters of each lens in the projection optical system of this embodiment. The "Surface Number" column indicates the number of each surface from the object plane to the image plane; the "Radius of Curvature (mm)" column gives the radius of curvature of the corresponding sphere or plane for each surface; the "Thickness / Spacing (mm)" column gives the axial distance between two adjacent surfaces. If the two surfaces belong to the same lens, the value of "Thickness / Spacing" represents the center thickness of the lens; otherwise, it represents the distance from the object plane or image plane to the lens or the air gap between adjacent lenses; "N" represents the distance between adjacent surfaces. d "One column indicates the refractive index of each lens between the object plane and the image plane; "V d The column "Dispersion coefficient" indicates the dispersion coefficient of the corresponding lens; the column "Aperture (mm)" indicates the aperture value of the corresponding surface. In addition to the lens, this optical system has a 3mm thick flat protective glass at a distance of 0.48mm from the object surface, which is not involved in the optical system design.

[0201] An aperture stop 2 is also provided between surface 11 and surface 13. Changes in its aperture size will affect the imaging effect of the projection optical system.

[0202]

[0203]

[0204] Table 10

[0205] Table 11 shows the relationship between the projection magnification of the projection optical system in this embodiment and the displacement of the seventh lens (L7). As can be seen from Table 11, the projection magnification of the optical system can be adjusted between -2.74985 and -2.75200 by adjusting the position of the seventh lens L7.

[0206] Zoom position 1 Zoom position 2 Working distance of objects 113.24 113.24 Image working distance 110.10 110.05 Object-image conjugate distance 498.72 498.67 Spacing 16 72.51 72.31 Spacing 18 46.80 47.00 L7 displacement 0 0.202 Projection magnification 2.74985 2.75200

[0207] Table 11

[0208] Table 12 shows the calculation results of the relational formulas of the symmetrical dual telecentric projection optical system in this embodiment. It can be seen from the calculation results that the present invention can effectively satisfy relational formulas (1) to (9).

[0209] Relation 1 F3 / F4 = -0.412 Relation 2 F3 / Fo = -0.282 Relation 3 F6 / F7 = -0.150 Relation 4 F6 / Fi = -0.063 Relation 5 R9 / R10 = 0.075 Relation 6 R14 / T14= -1.806 Relation 7 T1＝ 36.122 Relation 8 T16＝ 67.514

[0210] Table 12

[0211] Figure 8a This is a schematic diagram showing the percentage distortion of the projection magnification of the projection lens system at zoom position 1. Figure 8b This diagram illustrates the percentage distortion of the projection lens system at zoom position 2, showing that the relative distortion of the projection system is better than 0.002%, and the change in distortion is minimal when the projection magnification is increased or decreased.

[0212] Figure 9a This is a schematic diagram of wavefront aberration of the projection lens system at zoom position 1. Figure 9b The diagram shows the wavefront aberration of the projection lens system at zoom position 2, indicating that the projection system has good image quality and the wavefront aberration is better than ±0.02λ. When the projection magnification is increased or decreased, the change in wavefront aberration is very small, within ±0.003λ.

[0213] Example 4:

[0214] The preferred embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0215] like Figure 10As shown, this is a preferred fourth embodiment of the present invention. The dual telecentric exposure lens includes a front lens group 1, an aperture stop 2, and a rear lens group 3 arranged sequentially, with the aperture stop 2 located between the front lens group 1 and the rear lens group 3.

[0216] The projection optical system provided by this invention forms a double telecentric optical structure at the object plane and the image plane. Because the central lines of the light cones in the object space and image space, i.e., the principal rays, are parallel to the optical axis, the magnification is guaranteed not to change as the object plane and image plane move along the optical axis. Thus, even if the object plane and image plane deviate from the focal plane, the height of the object and image in the direction perpendicular to the optical axis remains unchanged, so the magnification will not change.

[0217] See Figure 10 As shown, the projection optical system consists of eight lenses in sequence from the object plane side: a front lens group 1, an aperture stop 2, and a rear lens group 3. The front lens group 1 has positive optical power, and the rear lens group 3 has positive optical power.

[0218] The front lens group 1 comprises four lenses, arranged from object side to image side as follows: first lens L1, second lens L2, third lens L3, and fourth lens L4. The first lens L1 is a biconvex lens with positive optical power; the second lens L2 is a biconvex lens with positive optical power; the third lens L3 is a biconcave lens with negative optical power; and the fourth lens L4 is a meniscus lens with positive optical power, its object side being convex and its image side being concave.

[0219] The first lens L1 is a convex lens with positive optical power. Its main function is to maintain the object-side telecentric optical path structure, while balancing the spherical aberration, coma, and astigmatism generated by the front lens group 1.

[0220] The second lens L2 is a convex lens with positive optical power. Its main function is to correct the chromatic aberration of the upper light rays and to produce spherical aberration, coma, and astigmatism that are opposite to those of the third lens L3 (concave lens), thus balancing the overall aberrations of the optical system.

[0221] The third lens, L3, is a concave lens with negative optical power. Its main function is to generate positive spherical aberration, which can be used to correct the negative spherical aberration generated by other convex lenses in the optical system. Simultaneously, since the projection optical system of this invention uses broadband illumination, high-refractive-index and low-Abbe-number glass, such as flint glass or light flint glass, is selected to form a double concave lens, generating axial and transverse chromatic aberration opposite to those of the convex lenses, which can correct the chromatic aberration of the optical system.

[0222] The fourth lens, L4, is a convex lens with positive optical power. Its main function is to generate less negative spherical aberration, negative coma, and distortion, thus balancing the overall aberrations of the front lens group 1.

[0223] The rear lens group 3 includes four lenses, arranged from the object side to the image side as follows: fifth lens L5, sixth lens L6, seventh lens L7, and eighth lens L8. The fifth lens L5 is a meniscus lens with positive optical power, its object side is convex, and its image side is concave. The sixth lens L6 is a biconcave lens with negative optical power. The seventh lens L7 is a meniscus lens with positive optical power, its object side is concave, and its image side is convex. The eighth lens L8 is a biconvex lens with positive optical power.

[0224] The fifth lens, L5, is a convex lens with positive optical power, while the sixth lens, L6, is a concave lens with negative optical power. Lenses L5 and L6 are positioned close to aperture stop 2, and their aperture sizes are similar. The upper and lower rays from the on-axis and peripheral fields of view, along with the principal ray, converge at the aperture stop and pass through the same area of ​​the apertures of both lenses, simultaneously correcting on-axis and off-axis chromatic aberration. Furthermore, as the only concave lens in the rear lens group 3, lens L6 produces spherical aberration, coma, field curvature, and distortion in the opposite direction to those of the convex lenses. This helps to avoid excessive high-order spherical aberration and field curvature, balancing the overall aberrations of the optical system.

[0225] Preferably, the seventh lens L7 is a zoom lens group. Since the surface radius of the zoom lens is large, its contribution to aberrations is small, and the additional aberrations introduced during position adjustment can be ignored. While keeping the object plane and image plane positions unchanged, the focal length of the optical system can be changed by moving the zoom lens group forward and backward. This allows for convenient and effective correction or adjustment of the projection magnification of the optical system while maintaining good telecentric projection optical characteristics and good optical imaging quality.

[0226] The eighth lens, L8, is a convex lens with positive optical power, which can maintain a good image-side telecentric optical path structure.

[0227] The internal focal length of the projection optical system in this embodiment of the invention satisfies the following relationship:

[0228] Relationship 1: -0.65 < F3 / F4 < -0.3; Relationship 2: -0.65 < F3 / Fo < 0;

[0229] Relationship 3: -0.18 < F6 / F7 < -0.1;

[0230] Relationship 4: -0.08 < F6 / Fi < -0.04;

[0231] Wherein, F3: focal length of the third lens L3; F4: focal length of the fourth lens L4; Fo: combined focal length of the front lens group 1; F6: focal length of the sixth lens L6; F7: focal length of the seventh lens L7; Fi: combined focal length of the rear lens group 3.

[0232] The main function of Equations 1 and 2 is to maintain the ratio of optical power of the third lens L3 to the fourth lens L4, and to evenly distribute the optical power of the concave and convex lenses in the front lens group 1. This avoids design results with too small a radius of curvature and too large an incident angle of the upper light rays, which would produce too much spherical aberration, coma, astigmatism and distortion on a single surface.

[0233] The main functions of Equations 3 and 4 are to rationally allocate the optical power ratio of the concave lenses in the rear lens group 3, balance the overall distortion and chromatic aberration of the optical system, control the optical power of the seventh lens L7 zoom lens so that it can share the optical power of the sixth lens L6, and not introduce too many aberrations into the optical system when the seventh lens L7 zooms.

[0234] The radius of curvature and aperture of the projection optical system in this embodiment of the invention satisfy the following relationship:

[0235] Relation 5: 0 < R9 / R10 < 0.45; Relation 6: -2.5 < R14 / T14 < -1.26;

[0236] Wherein, R9: the radius of curvature on the object side of the fifth lens L5; R10: the radius of curvature on the image side of the fifth lens L5; R14: the radius of curvature on the image side of the seventh lens L7; T14: the aperture on the image side of the seventh lens L7.

[0237] The main function of relation 5 is to control the optical power of the fifth lens L5, which is closest to the aperture stop 2, so that it can correct chromatic aberration without introducing too many other aberrations.

[0238] The main function of relation 6 is to control the optical power of the zoom lens in the rear lens group 3, maintain the absolute value difference between the curvature radius of curvature of the seventh lens L7 on the image side and the curvature radius of curvature of the eighth lens L8 on the object side, so that the seventh lens L7 and the eighth lens L8 share the optical power and reduce the aberration of a single lens.

[0239] The air gap inside the projection optical system in this embodiment of the invention satisfies the following relationship:

[0240] Relationship 7: 30.2 < T1 < 39.5; Relationship 8: 64.5 < T16 < 70.5;

[0241] Wherein, T1: the light-transmitting aperture on the object side of the first lens L1; T16: the light-transmitting aperture on the image side of the eighth lens L8.

[0242] The main function of relation 7 is to control the object distance to be greater than 100mm while maintaining a good object-side telecentric optical path.

[0243] The main function of relation 8 is to control the image distance to be greater than 100mm while maintaining a good image-side telecentric optical path.

[0244] In this way, the spherical aberration, astigmatism, coma, distortion, transverse chromatic aberration, and axial chromatic aberration of the optical system are automatically corrected to zero, and a dual telecentric optical path is formed between the object and image sides.

[0245] The design parameters of the projection optical system in this embodiment are shown in Table 13: object-side NA is 0.04, object-side field of view height is 11.3 mm, magnification is -2.75005, object-side working distance is 102.13 mm, image-side working distance is 159.30 mm, and object-image conjugate distance is 499.70 mm. For ease of optical processing and inspection, and to reduce costs, all optical elements in this invention are spherical or planar, with no aspherical elements.

[0246]

[0247]

[0248] Table 13

[0249] Table 14 provides the specific parameters of each lens in the projection optical system of this embodiment. The "Surface Number" column indicates the number of each surface from the object plane to the image plane; the "Radius of Curvature (mm)" column gives the radius of curvature of the corresponding sphere or plane for each surface; the "Thickness / Spacing (mm)" column gives the axial distance between two adjacent surfaces. If the two surfaces belong to the same lens, the value of "Thickness / Spacing" represents the center thickness of the lens; otherwise, it represents the distance from the object plane or image plane to the lens or the air gap between adjacent lenses; "N" represents the distance between adjacent surfaces. d "One column indicates the refractive index of each lens between the object plane and the image plane; "V d The column "Dispersion coefficient" indicates the dispersion coefficient of the corresponding lens; the column "Aperture (mm)" indicates the aperture value of the corresponding surface. In addition to the lens, this optical system has a 3mm thick flat protective glass at a distance of 0.48mm from the object surface, which is not involved in the optical system design.

[0250] An aperture stop 2 is also provided between surface 11 and surface 13. Changes in its aperture size will affect the imaging effect of the projection optical system.

[0251]

[0252]

[0253] Table 14

[0254] Table 15 shows the relationship between the projection magnification of the projection optical system in this embodiment and the displacement of the seventh lens L7. As can be seen from Table 7, the projection magnification of the optical system can be adjusted between -2.75005 and -2.75221 by adjusting the position of the seventh lens L7.

[0255] Zoom position 1 Zoom position 2 Working distance of objects 102.13 102.13 Image working distance 159.30 159.19 Object-image conjugate distance 499.70 500.09 Spacing 16 113.90 113.89 Spacing 18 2.70 3.21 L7 displacement 0 0.005 Projection magnification 2.75005 2.75221

[0256] Table 15

[0257] Table 16 shows the calculation results of the relational formulas of the symmetrical dual telecentric projection optical system in this embodiment. It can be seen from the calculation results that the present invention can effectively satisfy relational formulas (1) to (9).

[0258] Relation 1 F3 / F4 = -0.613 Relation 2 F3 / Fo = -0.649 Relation 3 F6 / F7 = -0.089 Relation 4 F6 / Fi = -0.064 Relation 5 R9 / R10 = 0.413 Relation 6 R14 / T14= -1.367 Relation 7 T1＝ 30.669 Relation 8 T16＝ 67.006

[0259] Table 16

[0260] Figure 11a This is a schematic diagram showing the percentage distortion of the projection magnification of the projection lens system at zoom position 1. Figure 11b This diagram illustrates the percentage distortion of the projection lens system at zoom position 2, showing that the relative distortion of the projection system is better than 0.002%, and the change in distortion is minimal when the projection magnification is increased or decreased.

[0261] Figure 12a This is a schematic diagram of wavefront aberration of the projection lens system at zoom position 1. Figure 12b The diagram shows the wavefront aberration of the projection lens system at zoom position 2, indicating that the projection system has good image quality and the wavefront aberration is better than ±0.03λ. When the projection magnification is increased or decreased, the change in wavefront aberration is very small, within ±0.003λ.

[0262] Example 5:

[0263] The preferred embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0264] like Figure 13 As shown, this is a preferred fifth embodiment of the present invention. The dual telecentric exposure lens includes a front lens group 1, an aperture stop 2, and a rear lens group 3 arranged sequentially, with the aperture stop 2 located between the front lens group 1 and the rear lens group 3.

[0265] The projection optical system provided by this invention forms a double telecentric optical structure at the object plane and the image plane. Because the central lines of the light cones in the object space and image space, i.e., the principal rays, are parallel to the optical axis, the magnification is guaranteed not to change as the object plane and image plane move along the optical axis. Thus, even if the object plane and image plane deviate from the focal plane, the height of the object and image in the direction perpendicular to the optical axis remains unchanged, so the magnification will not change.

[0266] See Figure 13 As shown, the projection optical system consists of eight lenses in sequence from the object plane side: a front lens group 1, an aperture stop 2, and a rear lens group 3. The front lens group 1 has positive optical power, and the rear lens group 3 has positive optical power.

[0267] The front lens group 1 comprises four lenses, arranged from object side to image side as follows: first lens L1, second lens L2, third lens L3, and fourth lens L4. The first lens L1 is a biconvex lens with positive optical power; the second lens L2 is a meniscus lens with positive optical power, its object side being convex and its image side being concave; the third lens L3 is a biconcave lens with negative optical power; and the fourth lens L4 is a meniscus lens with positive optical power, its object side being convex and its image side being concave.

[0268] The first lens L1 is a convex lens with positive optical power. Its main function is to maintain the object-side telecentric optical path structure, while balancing the spherical aberration, coma, and astigmatism generated by the front lens group 1.

[0269] The second lens L2 is a convex lens with positive optical power. Its main function is to correct the chromatic aberration of the upper light rays and to produce spherical aberration, coma, and astigmatism that are opposite to those of the third lens L3 (concave lens), thus balancing the overall aberrations of the optical system.

[0270] The third lens, L3, is a concave lens with negative optical power. Its main function is to generate positive spherical aberration, which can be used to correct the negative spherical aberration generated by other convex lenses in the optical system. Simultaneously, since the projection optical system of this invention uses broadband illumination, high-refractive-index and low-Abbe-number glass, such as flint glass or light flint glass, is selected to form a double concave lens, generating axial and transverse chromatic aberration opposite to those of the convex lenses, which can correct the chromatic aberration of the optical system.

[0271] The fourth lens, L4, is a convex lens with positive optical power. Its main function is to generate less negative spherical aberration, negative coma, and distortion, thus balancing the overall aberrations of the front lens group 1.

[0272] The rear lens group 3 includes four lenses, arranged from the object side to the image side as follows: fifth lens L5, sixth lens L6, seventh lens L7, and eighth lens L8; the fifth lens L5 is a meniscus lens with positive optical power, its object side is convex, and its image side is concave; the sixth lens L6 is a biconcave lens with negative optical power; the seventh lens L7 is a biconvex lens with positive optical power; and the eighth lens is a biconvex lens L8 with positive optical power.

[0273] The fifth lens, L5, is a convex lens with positive optical power, while the sixth lens, L6, is a concave lens with negative optical power. Lenses L5 and L6 are positioned close to aperture stop 2, and their aperture sizes are similar. The upper and lower rays from the on-axis and peripheral fields of view, along with the principal ray, converge at the aperture stop and pass through the same area of ​​the apertures of both lenses, simultaneously correcting on-axis and off-axis chromatic aberration. Furthermore, as the only concave lens in the rear lens group 3, lens L6 produces spherical aberration, coma, field curvature, and distortion in the opposite direction to those of the convex lenses. This helps to avoid excessive high-order spherical aberration and field curvature, balancing the overall aberrations of the optical system.

[0274] Preferably, the seventh lens L7 is a zoom lens group. Since the surface radius of the zoom lens is large, its contribution to aberrations is small, and the additional aberrations introduced during position adjustment can be ignored. While keeping the object plane and image plane positions unchanged, the focal length of the optical system can be changed by moving the zoom lens group forward and backward. This allows for convenient and effective correction or adjustment of the projection magnification of the optical system while maintaining good telecentric projection optical characteristics and good optical imaging quality.

[0275] The eighth lens, L8, is a convex lens with positive optical power, which can maintain a good image-side telecentric optical path structure.

[0276] The internal focal length of the projection optical system in this embodiment of the invention satisfies the following relationship:

[0277] Relationship 1: -0.65 < F3 / F4 < -0.3; Relationship 2: -0.65 < F3 / Fo < 0;

[0278] Relationship 3: -0.18 < F6 / F7 < -0.1; Relationship 4: -0.08 < F6 / Fi < -0.04;

[0279] Wherein, F3: focal length of the third lens L3; F4: focal length of the fourth lens L4; Fo: combined focal length of the front lens group 1; F6: focal length of the sixth lens L6; F7: focal length of the seventh lens L7; Fi: combined focal length of the rear lens group 3.

[0280] The main function of Equations 1 and 2 is to maintain the ratio of optical power of the third lens L3 to the fourth lens L4, and to evenly distribute the optical power of the concave and convex lenses in the front lens group 1. This avoids design results with too small a radius of curvature and too large an incident angle of the upper light rays, which would produce too much spherical aberration, coma, astigmatism and distortion on a single surface.

[0281] The main functions of Equations 3 and 4 are to rationally allocate the optical power ratio of the concave lenses in the rear lens group 3, balance the overall distortion and chromatic aberration of the optical system, control the optical power of the seventh lens L7 zoom lens so that it can share the optical power of the sixth lens L6, and not introduce too many aberrations into the optical system when the seventh lens L7 zooms.

[0282] The radius of curvature and aperture of the projection optical system in this embodiment of the invention satisfy the following relationship:

[0283] Relation 5: 0 < R9 / R10 < 0.45; Relation 6: -2.5 < R14 / T14 < -1.26;

[0284] Wherein, R9: the radius of curvature on the object side of the fifth lens L5; R10: the radius of curvature on the image side of the fifth lens L5; R14: the radius of curvature on the image side of the seventh lens L7; T14: the aperture on the image side of the seventh lens L7.

[0285] The main function of relation 5 is to control the optical power of the fifth lens L5, which is closest to the aperture stop 2, so that it can correct chromatic aberration without introducing too many other aberrations.

[0286] The main function of relation 6 is to control the optical power of the zoom lens in the rear lens group 3, maintain the absolute value difference between the curvature radius of curvature of the seventh lens L7 on the image side and the curvature radius of curvature of the eighth lens L8 on the object side, so that the seventh lens L7 and the eighth lens L8 share the optical power and reduce the aberration of a single lens.

[0287] The air gap inside the projection optical system in this embodiment of the invention satisfies the following relationship:

[0288] Relationship 7: 30.2 < T1 < 39.5; Relationship 8: 64.5 < T16 < 70.5;

[0289] Wherein, T1: the light-transmitting aperture on the object side of the first lens L1; T16: the light-transmitting aperture on the image side of the eighth lens L8.

[0290] The main function of relation 7 is to control the object distance to be greater than 100mm while maintaining a good object-side telecentric optical path.

[0291] The main function of relation 8 is to control the image distance to be greater than 100mm while maintaining a good image-side telecentric optical path.

[0292] In this way, the spherical aberration, astigmatism, coma, distortion, transverse chromatic aberration, and axial chromatic aberration of the optical system are automatically corrected to zero, and a dual telecentric optical path is formed between the object and image sides.

[0293] The design parameters of the projection optical system in this embodiment are shown in Table 17: object-side NA is 0.07, object-side field of view height is 11.3 mm, magnification is -2.75005, object-side working distance is 112.84 mm, image-side working distance is 109.72 mm, and object-image conjugate distance is 496.69 mm. For ease of optical processing and inspection, and to reduce costs, all optical elements in this invention are spherical or planar, with no aspherical elements.

[0294] Numerical aperture (NA) 0.07 Object-side field of view (line field of view) 11.3mm Magnification -2.75003 Working distance of objects 112.84mm Image working distance 109.72mm Object-image conjugate distance 496.69mm

[0295] Table 17

[0296] Table 18 provides the specific parameters of each lens in the projection optical system of this embodiment. The "Surface Number" column indicates the number of each surface from the object plane to the image plane; the "Radius of Curvature (mm)" column gives the radius of curvature of the corresponding sphere or plane for each surface; the "Thickness / Spacing (mm)" column gives the axial distance between two adjacent surfaces. If the two surfaces belong to the same lens, the value of "Thickness / Spacing" represents the center thickness of the lens; otherwise, it represents the distance from the object plane or image plane to the lens or the air gap between adjacent lenses; "N" represents the distance between adjacent surfaces. d "One column indicates the refractive index of each lens between the object plane and the image plane; "V d The column "Dispersion coefficient" indicates the dispersion coefficient of the corresponding lens; the column "Aperture (mm)" indicates the aperture value of the corresponding surface.

[0297] Apart from the lens, this optical system has a 3mm thick flat protective glass at a distance of 0.48mm from the object surface, which is not involved in the optical system design.

[0298] An aperture stop 2 is also provided between surface 11 and surface 13. Changes in its aperture size will affect the imaging effect of the projection optical system.

[0299]

[0300] Table 18

[0301] Table 19 shows the relationship between the projection magnification of the projection optical system in this embodiment and the displacement of the seventh lens L7. As can be seen from Table 7, the projection magnification of the optical system can be adjusted between -2.75003 and -2.75214 by adjusting the position of the seventh lens L7.

[0302] Zoom position 1 Zoom position 2 Working distance of objects 112.84 112.84 Image working distance 109.72 109.63 Object-image conjugate distance 496.69 496.60 Spacing 16 85.24 84.93 Spacing 18 25.11 25.41 L7 displacement 0 0.304 Projection magnification 2.75003 2.75214

[0303] Table 19

[0304] Table 20 shows the calculation results of the relational formulas of the symmetrical dual telecentric projection optical system in this embodiment. It can be seen from the calculation results that the present invention can effectively satisfy relational formulas (1) to (9).

[0305] Relation 1 F3 / F4 = -0.553 Relation 2 F3 / Fo = -0.100 Relation 3 F6 / F7 = -0.135 Relation 4 F6 / Fi = -0.047 Relation 5 R9 / R10 = 0.094 Relation 6 R14 / T14= -2.098 Relation 7 T1＝ 38.490 Relation 8 T16＝ 68.091

[0306] Table 20

[0307] Figure 14a This is a schematic diagram showing the percentage distortion of the projection magnification of the projection lens system at zoom position 1. Figure 14b This diagram illustrates the percentage distortion of the projection lens system at zoom position 2, showing that the relative distortion of the projection system is better than 0.002%, and the change in distortion is minimal when the projection magnification is increased or decreased.

[0308] Figure 15a This is a schematic diagram of wavefront aberration of the projection lens system at zoom position 1. Figure 15b The diagram shows the wavefront aberration of the projection lens system at zoom position 2, indicating that the projection system has good image quality and the wavefront aberration is better than ±0.03λ. When the projection magnification is increased or decreased, the change in wavefront aberration is very small, within ±0.003λ.

[0309] In summary, the beneficial effects of the present invention are as follows:

[0310] 1. The projection optical system of the present invention has a lens group consisting of 8 lenses. Without the introduction of aspherical lenses, it can effectively correct various aberrations and reduce the cost of lens processing, testing and calibration.

[0311] 2. The object-side working distance and image-side working distance of the projection optical system of the present invention are both greater than 100mm, which leaves sufficient margin for the mechanical design of the stage part of the projection lithography system.

[0312] 3. When adjusting the magnification, the projection optical system of the present invention can conveniently and effectively correct or adjust the projection magnification of the optical system by moving a zoom lens while maintaining good dual telecentric projection optical characteristics and good optical imaging quality.

[0313] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An adjustable magnification dual telecentric projection optical system, employing a dual telecentric structure, wherein the principal rays on the object side and image side are parallel to the optical axis, characterized in that: The front lens group (1), aperture stop (2), and rear lens group (3) are arranged sequentially from the object side to the image side. The front lens group (1) consists of a first positive power lens group; The aperture stop (2) is located on the confocal surface of the front lens group (1) and the rear lens group (3); The rear lens group (3) is composed of the second positive optical power lens group, and the positional relationship of the corresponding lenses in the rear lens group (3) is moved to form a variable magnification lens to adjust the magnification of the optical system; The front lens group (1) and the rear lens group (3) consist of 8 lenses. The front lens group (1) consists of the first lens (L1), the second lens (L2), the third lens (L3) and the fourth lens (L4). The rear lens group (3) consists of the fifth lens (L5), the sixth lens (L6), the seventh lens (L7) and the eighth lens (L8). The optical system satisfies the following relationship: Relationship 1: -0.65 < F3 / F4 < -0.3; Relationship 2: -0.65 < F3 / Fo < 0; Relationship 3: -0.18 < F6 / F7 < -0.1; Relationship 4: -0.08 < F6 / Fi < -0.04; Wherein, F3 is the focal length of the third lens (L3); F4 is the focal length of the fourth lens (L4); Fo is the combined focal length of the front lens group (1); F6 is the focal length of the sixth lens (L6); F7 is the focal length of the seventh lens (L7); and Fi is the combined focal length of the rear lens group (3).

2. The adjustable magnification dual telecentric projection optical system according to claim 1, characterized in that: The first lens (L1), the second lens (L2), the fourth lens (L4), the fifth lens (L5), the seventh lens (L7), and the eighth lens (L8) are convex lenses, the third lens (L3) and the sixth lens (L6) are concave lenses, and the seventh lens (L7) in the rear lens group (3) can be moved to form a zoom lens to adjust the magnification of the optical system.

3. The adjustable magnification dual telecentric projection optical system according to claim 2, characterized in that: The third lens (L3) and the sixth lens (L6) are biconcave lenses.

4. The adjustable magnification dual telecentric projection optical system according to claim 1, characterized in that: The objective lens system consisting of the front lens group (1), aperture stop (2) and rear lens group (3) operates in the near-ultraviolet band. The first lens (L1), the second lens (L2), the fourth lens (L4), the fifth lens (L5), the seventh lens (L7), and the eighth lens (L8) are made of crown glass or light crown glass, and their material properties meet the following requirements: 1.43<N d <1.65 55.00<V d <85.00 Where, N d V represents the refractive index of the first lens (L1), second lens (L2), fourth lens (L4), fifth lens (L5), seventh lens (L7), and eighth lens (L8); d Its corresponding dispersion coefficient; The third lens (L3) and the sixth lens (L6) are made of flint glass or light flint glass, and their material properties meet the following requirements: 1.53<N d <1.64 35.00<V d <46.00 Where, N d V represents the refractive index of the third lens (L3) and the sixth lens (L6); d It is its corresponding dispersion coefficient.

5. The adjustable magnification dual telecentric projection optical system according to claim 1, characterized in that, All lens surfaces in the optical system are either spherical or planar.

6. The adjustable magnification dual telecentric projection optical system according to claim 1, characterized in that, The working distance between the object side and the image side of the optical system is greater than 100mm.

7. The adjustable magnification dual telecentric projection optical system according to claim 1, characterized in that, The optical system satisfies the following relationship: Relationship 5: 0 < R9 / R10 < 0.45; Relationship 6: -2.5 < R14 / T14 < -1.26; Wherein, R9 is the radius of curvature on the object side of the fifth lens (L5); R10 is the radius of curvature on the image side of the fifth lens (L5); R14 is the radius of curvature on the image side of the seventh lens (L7); and T14 is the aperture on the image side of the seventh lens (L7).

8. The adjustable magnification dual telecentric projection optical system according to claim 1, characterized in that, The optical system satisfies the following relationship: Relationship 7: 30.2 < T1 < 39.5; Relationship 8: 64.5 < T16 < 70.5; Wherein, T1 is the light-transmitting aperture on the object side of the first lens (L1); T16 is the light-transmitting aperture on the image side of the eighth lens (L8).

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