CN116804800A

CN116804800A - Double telecentric projection optical system with adjustable multiplying power

Info

Publication number: CN116804800A
Application number: CN202310600377.XA
Authority: CN
Inventors: 霍大云; 奚芳芳; 郭宇涵
Original assignee: Xifan Semiconductor Wuxi Co ltd
Current assignee: Xifan Semiconductor Wuxi Co ltd
Priority date: 2023-05-25
Filing date: 2023-05-25
Publication date: 2023-09-26

Abstract

The variable magnification projection optical system is a double telecentric optical path, and comprises a front lens group, an aperture diaphragm and a rear lens group along the optical axis direction, wherein the front lens group comprises the following components sequentially from an object space to an image space: a first lens; a second lens; a third lens; a fourth lens; the rear lens group comprises the following components sequentially from the object side to the image side: a fifth lens; a sixth lens; a seventh lens; an eighth lens; the device also comprises a zoom lens, and magnification adjustment is realized by controlling the zoom lens to move along the optical axis direction. The invention can realize focal length change by utilizing the movement of the single lens on the basis of not increasing the number of optical parts under the condition of keeping good double telecentric projection optical characteristics and good optical imaging quality, thereby being convenient and effective for correcting or adjusting the projection multiplying power of the optical system; all lenses selected by the optical system are spherical, and the optical system does not contain aspheric lenses, so that the difficulty and cost of processing, detecting and assembling are greatly reduced.

Description

Double telecentric projection optical system with adjustable multiplying power

Technical Field

The invention relates to an optical system applied to a projection photoetching machine, in particular to a double telecentric projection system with adjustable multiplying power.

Background

In recent years, projection lithography has been widely used in various fields such as circuit fabrication, machine vision, and semiconductors. With the development of photolithography, the minimum line width of Integrated Circuits (ICs) is becoming smaller and smaller in the production process of circuit substrates, and the requirements for projection lenses are increasing.

Because the lens manufacturing process has processing errors, and the substrates manufactured by different devices have fine size differences, when the circuit substrate scanning and the multilayer substrate positioning process are performed, the projection magnification of the optical system needs to be corrected or adjusted according to the actual change of the graph or the magnification so as to ensure the accuracy of the magnification.

The double telecentric lens can well meet the requirements of the photoetching projection lens, and because the object space optical path and the image space optical path are double telecentric optical paths, even if the object plane and the image plane deviate from the focal plane, the heights of the object and the image in the direction vertical to the optical axis are unchanged, so that the magnification is hardly changed.

The currently published double telecentric lens with adjustable magnification has a large number of lenses forming an optical system, and two or more lenses need to be moved simultaneously to complete magnification adjustment, for example, CN102645749a (publication date is 2012, 08 and 22 days), and the magnification is adjusted by moving a group of symmetrical lenses, so that the requirements on mechanical structure design and lens processing cost are high.

Therefore, how to provide an optical system which can maintain good double telecentric projection optical characteristics and good optical imaging quality and can conveniently and effectively correct or adjust projection magnification is an important technical subject in the industry.

Disclosure of Invention

The invention aims to provide a double telecentric projection optical system with adjustable multiplying power, which is convenient for correcting or adjusting the projection multiplying power of the optical system when the multiplying power of a projection objective lens drifts.

An adjustable multiplying power double telecentric projection optical system adopts a double telecentric structure, and the principal rays of an object space and an image space are parallel to an optical axis, and comprises a front lens group, an aperture diaphragm and a rear lens group which are sequentially arranged from the object space to the image space; the front lens group consists of a first positive focal power lens group; the aperture diaphragm is positioned on the confocal plane of the front lens group and the rear lens group; the rear lens group is composed of a second positive focal power lens group, and the position relation of the corresponding lens in the rear lens group is moved to form a variable power lens to adjust the multiplying power of the optical system.

As a further improvement of the above technical scheme:

the current lens group and the rear lens group include 8 lenses, the front lens group is composed of a first lens, a second lens, a third lens and a fourth lens, and the rear lens group is composed of a fifth lens, a sixth lens, a seventh lens and an eighth lens.

The first lens, the second lens, the fourth lens, the fifth lens, the seventh lens and the eighth lens are convex lenses, the third lens and the sixth lens are concave lenses, and the seventh lens can form a variable-magnification lens by moving in the rear lens group, so that the magnification of the optical system is adjusted.

The third lens and the sixth lens are biconcave lenses.

The working wavelength of an objective lens system formed by the front lens group, the aperture diaphragm and the rear lens group is near ultraviolet band;

the first lens, the second lens, the fourth lens, the fifth lens, the seventh lens and the eighth lens adopt crown glass or light crown glass, and the material characteristics of the first lens, the second lens, the fourth lens, the fifth lens, the seventh lens and the eighth lens meet the following conditions:

1.43<Nd<1.65

55.00<Vd<85.00

wherein Nd is the refractive index of the lens first, second, fourth, fifth, seventh, and eighth lenses; vd is its corresponding dispersion coefficient;

the third lens and the sixth lens adopt flint glass or light flint glass, and the material characteristics of the third lens and the sixth lens meet the following conditions:

1.53<Nd<1.64

35.00<Vd<46.00

wherein Nd is refractive indices of the third lens and the sixth lens; vd is its corresponding dispersion coefficient.

All lens surfaces of the optical system are spherical or planar.

The working distance between the object space and the image space of the optical system is larger than 100mm.

The optical system satisfies the following relation:

Relation 1: -0.65 < F3/F4 < -0.3;

relation 2: -0.65 < F3/Fo < 0;

relation 3: -0.18 < F6/F7 < -0.1;

relation 4: -0.08 < F6/Fi < -0.04;

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; fi is the combined focal length of the rear lens group.

The optical system satisfies the following relation:

relation 5: R9/R10 is more than 0 and less than 0.45;

relation 6: -2.5 < R14/T14 < -1.26;

wherein R9 is the curvature radius of the object side of the fifth lens; r10 is the radius of curvature of the fifth lens image side; r14 is the radius of curvature of the seventh lens image side; t14 is the clear aperture on the seventh lens image side.

The optical system satisfies the following relation:

relation 7: t1 is more than 30.2 and less than 39.5;

relation 8: t16 is more than 64.5 and less than 70.5;

wherein T1 is the clear aperture of the first lens object side; t16 is the clear aperture on the eighth lens image side.

Compared with the prior art, the invention has the following advantages:

the invention can realize focal length change by utilizing the movement of the single lens on the basis of not increasing the number of optical parts under the condition of keeping good double telecentric projection optical characteristics and good optical imaging quality, thereby being convenient and effective for correcting or adjusting the projection multiplying power of the optical system; all lenses selected by the optical system are spherical, and the optical system does not contain aspheric lenses, so that the difficulty and cost of processing, detecting and assembling are greatly reduced.

1. The projection optical system provided by the invention has the advantages that the lens group consists of 8 lenses, and the aspherical lenses are not introduced, so that not only can each aberration be well corrected, but also the cost of processing, testing and assembling the lens is reduced.

2. The object space working distance and the image space working distance of the projection optical system are both larger than 100mm, and enough allowance is left for the mechanical design of a workbench part of the projection lithography system.

3. When the projection optical system is used for adjusting the multiplying power, the projection multiplying power of the optical system can be conveniently and effectively corrected or adjusted by moving one zoom lens under the conditions of keeping good double telecentric projection optical characteristics and good optical imaging quality.

Drawings

FIG. 1 is a schematic diagram showing a structure of a projection optical system according to a first embodiment of the present invention;

fig. 2a is a schematic view showing a distortion percentage of the projection magnification of the projection optical system in fig. 1 at the zoom position 1.

Fig. 2b is a schematic view showing a distortion percentage of the projection magnification of the projection optical system in fig. 1 at the zoom position 2.

Fig. 3a is a schematic view showing wave aberration of the projection optical system of fig. 1 when the projection magnification is at the zoom position 1.

Fig. 3b is a schematic view showing wave aberration of the projection optical system in fig. 1 when the projection magnification is at the zoom position 2.

FIG. 4 is a schematic diagram illustrating a projection optical system according to a second embodiment of the present invention;

fig. 5a is a schematic view showing a distortion percentage of the projection magnification of the projection optical system in fig. 4 at the zoom position 1.

Fig. 5b is a schematic view showing the distortion percentage of the projection magnification of the projection optical system in fig. 4 at the zoom position 2.

Fig. 6a is a schematic view showing wave aberration of the projection optical system of fig. 4 when the projection magnification is at the zoom position 1.

Fig. 6b is a schematic view showing wave aberration of the projection magnification of the projection optical system in fig. 4 at the zoom position 2.

FIG. 7 is a schematic diagram showing a projection optical system according to a third embodiment of the present invention;

fig. 8a is a schematic view showing a distortion percentage of the projection magnification of the projection optical system in fig. 7 at the zoom position 1.

Fig. 8b is a schematic view showing the distortion percentage of the projection magnification of the projection optical system in fig. 7 at the zoom position 2.

Fig. 9a is a schematic view showing wave aberration of the projection optical system of fig. 7 when the projection magnification is at the zoom position 1.

Fig. 9b is a schematic view showing wave aberration of the projection optical system in fig. 7 when the projection magnification is at the zoom position 2.

FIG. 10 is a schematic diagram showing a projection optical system according to a fourth embodiment of the present invention;

Fig. 11a is a schematic view showing a distortion percentage of the projection magnification of the projection optical system in fig. 10 at the zoom position 1.

Fig. 11b is a schematic view showing the distortion percentage of the projection magnification of the projection optical system in fig. 10 at the zoom position 2.

Fig. 12a is a schematic view showing wave aberration of the projection optical system of fig. 10 when the projection magnification is at the zoom position 1.

Fig. 12b is a schematic view showing wave aberration of the projection optical system of fig. 10 at the zoom position 2.

FIG. 13 is a schematic diagram showing a projection optical system according to a fifth embodiment of the present invention;

fig. 14a is a schematic view showing a distortion percentage of the projection magnification of the projection optical system in fig. 13 at the zoom position 1.

Fig. 14b is a schematic view showing the distortion percentage of the projection magnification of the projection optical system in fig. 13 at the zoom position 2.

Fig. 15a is a schematic view showing wave aberration of the projection optical system of fig. 13 when the projection magnification is at the zoom position 1.

Fig. 15b is a schematic view showing wave aberration of the projection optical system of fig. 13 when the projection magnification is at the zoom position 2.

Wherein: 1. a front lens group; 2. an aperture stop; 3. a rear lens group; l1, a first lens; l2, a second lens; l3, a third lens; l4, a fourth lens; l5, a fifth lens; l6, sixth lens; l7, seventh lens; l8, eighth lens; r9, radius of curvature of the fifth lens object side; r10, radius of curvature of the fifth lens image side; r14, radius of curvature of the seventh lens image side.

Detailed Description

The preferred embodiments of the present invention will be described below with reference to the accompanying drawings, it being understood that the preferred embodiments described herein are for illustration and explanation of the present invention only, and are not intended to limit the present invention.

Embodiment one:

the present embodiment provides a projection optical system including a front lens group 1, an aperture stop 2, and a rear lens group 3 in order from an object plane side to an image plane side. The combined back focus of the front lens group 1 and the combined front focus of the rear lens group 3 are overlapped and overlapped with the center of the aperture diaphragm 2 to form a double telecentric optical structure.

As shown in fig. 1, the double telecentric exposure lens includes a front lens group 1, an aperture stop 2, and a rear lens group 3 that are sequentially disposed, the aperture stop 2 being located between the front lens group 1 and the rear lens group 3.

The projection optical system provided by the invention forms a double telecentric optical structure at the object plane and the image plane, and because the light cone central lines of the object space and the image space, namely the principal rays, are parallel to the optical axis, the magnification is ensured not to be changed along with the movement of the object plane and the image plane along the direction of the optical axis. In this way, even if the object plane and the image plane deviate from the focal plane, the heights of the object and the image in the direction perpendicular to the optical axis remain unchanged, so the magnification does not change.

Referring to fig. 1, the projection optical system is composed of a total of 8 lenses of a front lens group 1, an aperture stop 2, and a rear lens group 3 in order from the object plane side. The front lens group 1 has positive power, and the rear lens group 3 has positive power.

The front lens group 1 comprises 4 lenses, and the lens groups are sequentially from an object space to an image space: a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4; the first lens L1 is a biconvex lens having positive optical power; the second lens L2 is a biconvex lens having positive optical power; the third lens L3 is a biconcave lens having negative optical power. The fourth lens element L4 has a positive refractive power, and has a convex object-side surface and a concave image-side surface.

The first lens L1 is a convex lens, has positive focal power, and is mainly used for maintaining an object space telecentric optical path structure and balancing spherical aberration, coma aberration and astigmatism which are commonly generated by the front lens group 1.

The second lens L2 is a convex lens having positive power, and is mainly used for correcting chromatic aberration of upper light, generating spherical aberration, coma aberration and astigmatism opposite to those of the third lens L3 concave lens, and balancing the overall aberration of the optical system.

The third lens L3 is a concave lens, has negative focal power, and has the main function of generating positive spherical aberration and can be used for correcting the negative spherical aberration generated by other convex lenses of the optical system. Meanwhile, the projection optical system of the invention uses a broadband light source to illuminate, and selects glass with high refractive index and low Abbe number, such as light flint glass or flint glass, to form a biconcave lens, so that axial chromatic aberration and vertical chromatic aberration opposite to the direction of the convex lens are generated, and chromatic aberration of the optical system can be corrected.

The fourth lens L4 is a convex lens, has positive focal power, and has the main function of generating less negative spherical aberration, negative coma and distortion, and balancing the overall aberration of the front lens group 1.

The rear lens group 3 includes 4 lenses, and from the object space to the image space, the following are: a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8; the fifth lens L5 is a meniscus lens with positive focal power, the object side surface is a convex surface, and the image side surface is a concave surface; the sixth lens L6 is a biconcave lens and has negative focal power; the seventh lens L7 is a meniscus lens with positive focal power, the object side surface is a concave surface, and the image side surface is a convex surface; the eighth lens is a biconvex lens L8 having positive optical power.

The fifth lens L5 is a convex lens with positive focal power, the sixth lens L6 is a concave lens with negative focal power, the positions of the fifth lens L5 and the sixth lens L6 are close to the aperture stop 2, and the clear apertures of the two lenses are similar in size. After the upper light, the lower light and the main light of the on-axis view field and the edge view field are converged by the diaphragm, the on-axis chromatic aberration and the off-axis chromatic aberration can be corrected simultaneously by the same area of the clear aperture of the fifth lens L5 and the sixth lens L6. And the sixth lens L6 is the only concave lens in the rear lens group 3, and can generate spherical aberration, coma aberration, curvature of field and distortion opposite to the convex lens direction, so as to avoid generating excessive high-order spherical aberration and high-order curvature of field and balance the total aberration of the optical system.

Preferably, the seventh lens L7 is a variable magnification lens group, and since the surface radius of the variable magnification lens is large, the contribution of the introduced aberration is small, and the additional aberration introduced in the position adjustment is negligible. The focal length of the optical system is changed by moving the front and rear positions of the zoom lens group under the condition that the positions of the object plane and the image plane are kept unchanged, and the projection magnification of the optical system can be conveniently and effectively corrected or adjusted under the condition that good double telecentric projection optical characteristics and good optical imaging quality are kept.

The eighth lens L8 is a convex lens, has positive focal power, and can maintain a good image-space telecentric optical path structure.

The internal focal length of the projection optical system in the embodiment of the invention satisfies the following relation:

relation 1: -0.65 < F3/F4 < -0.3; relation 2: -0.65 < F3/Fo < 0; relation 3: -0.18 < F6/F7 < -0.1;

relation 4: -0.08 < F6/Fi < -0.04;

wherein, F3: a focal length of the third lens L3; f4: a focal length of the fourth lens L4; fo: a combined focal length of the front lens group 1; f6: a focal length of the sixth lens L6; f7: a focal length of the seventh lens L7; fi: a combined focal length of the rear lens group 3.

The main function of the relation 1 and the relation 2 is to maintain the ratio of the optical powers of the third lens L3 to the fourth lens L4, and to evenly distribute the optical powers of the concave lens and the convex lens in the front lens group 1, so as to avoid the design result that the curvature radius is too small and the incident angle of the upper light is too large, and generate excessive spherical aberration, coma, astigmatism and distortion on a single surface.

The main function of the relation 3 and the relation 4 is to reasonably distribute the focal power ratio of the concave lens in the rear lens group 3, balance the overall distortion and chromatic aberration of the optical system, and control the focal power of the variable magnification lens of the seventh lens L7 so that the focal power of the sixth lens L6 can be shared, and excessive aberration is not introduced to the optical system when the variable magnification lens seventh lens L7 is moved to zoom.

The curvature radius and the clear aperture numerical value of the projection optical system in the embodiment of the invention satisfy the following relation:

relation 5: R9/R10 is more than 0 and less than 0.45; relation 6: -2.5 < R14/T14 < -1.26;

wherein, R9: a radius of curvature of the object side of the fifth lens L5; r10: a curvature radius of the image side of the fifth lens L5; r14: a radius of curvature of the image side of the seventh lens L7; t14: and the clear aperture of the image side of the seventh lens L7.

The main function of relation 5 is to control the power of L5 of the fifth lens closest to the aperture stop 2 so that it does not introduce excessive other aberrations while correcting chromatic aberration.

The main function of the relation 6 is to control the focal power of the variable power lens in the rear lens group 3, and to maintain the absolute value difference between the radius of curvature of the image side of the seventh lens L7 and the radius of curvature of the object side of the eighth lens L8, so that the seventh lens L7 and the eighth lens L8 share the focal power together, thereby reducing the aberration of the single lens.

The internal air space of the projection optical system in the embodiment of the invention satisfies the following relation:

relation 7: t1 is more than 30.2 and less than 39.5; relation 8: t16 is more than 64.5 and less than 70.5;

wherein, T1: a clear aperture on the object side of the first lens L1; t16: and the eighth lens L8 has a clear aperture at the image side.

The main function of relation 7 is to control object distances greater than 100mm while maintaining a good object-side telecentric optical path.

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.

In this way, the spherical aberration, astigmatism, coma, distortion, vertical axis chromatic aberration and axial chromatic aberration of the optical system are automatically corrected to zero, and an object-side image-side double telecentric optical path is formed.

The design parameters of the projection optical system in the embodiment of the invention are shown in table 1, wherein the NA of the object space is 0.06, the height of the field of view of the object space is 11.3mm, the magnification is-2.74986, the working distance of the object space is 103.46mm, the working distance of the image space is 132.76mm, and the conjugate distance of the object image is 500.00mm. For optical processing, optical inspection is convenient and cost-effective, and all optical elements of the present invention are spherical or planar without any aspheric element.

Object space numerical aperture NA	0.06
		Object view field (line view field)	11.3mm
Magnification ratio	-2.74986
		Working distance of object space	103.46mm
Working distance of image space	132.67mm
		Object-image conjugate distance	500.00mm

TABLE 1

Table 2 shows each mirror of the projection optical system of the present embodimentSpecific parameters of the sheet. Wherein the column of the surface number indicates the number corresponding to each surface between the object plane and the image plane; the column "radius of curvature (mm)" gives the radius of curvature of the corresponding sphere or plane of each surface; the column "thickness/pitch (mm)" gives the axial distance between two adjacent surfaces, if the two surfaces belong to the same lens, the value "thickness/pitch" indicates the center thickness of the lens, otherwise the object plane or image plane to lens distance or air spacing of the adjacent lenses; "N _d "a column indicates the refractive index for each lens between the object plane and the image plane; v (V) _d "column indicates the dispersion coefficient of the corresponding lens; the column "clear aperture (mm)" indicates the clear aperture value of the corresponding surface.

Besides the lens, the optical system is provided with a piece of plate protection glass with the thickness of 3mm at the position 0.48mm away from the object plane, and the optical system is not involved in the design of the optical system.

An aperture stop 2 is also provided between the surface 11 and the surface 13, the change in the aperture size of which affects the imaging effect of the projection optical system.

TABLE 2

Table 3 shows the relationship between the projection magnification of the projection optical system of the present embodiment and the displacement amount of the seventh lens L7. As can be seen from table 3, the present invention can adjust the projection magnification of the optical system between-2.74986 and-2.75201 by adjusting the position of the seventh lens L7.

	Zoom position 1	Zoom position 2
			Working distance of object space	103.46	103.46
Working distance of image space	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

TABLE 3 Table 3

Table 4 shows the calculation results of the relation of the symmetrical double telecentric projection optical system of the present embodiment, and from the calculation results, it can be seen that the present invention can effectively satisfy the relation (1) to the relation (9).

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

TABLE 4 Table 4

Fig. 2a is a schematic diagram of the distortion percentage of the projection magnification of the projection objective system at the zoom position 1, and fig. 2b is a schematic diagram of the distortion percentage of the projection magnification of the projection objective system at the zoom position 2, which shows that the relative distortion of the projection system is better than 0.002%, and the variation of the distortion is very small when the projection magnification is enlarged and reduced.

Fig. 3a is a schematic wave aberration diagram of the projection magnification of the projection objective system at the zoom position 1, and fig. 3b is a schematic wave aberration diagram of the projection magnification of the projection objective system at the zoom position 2, which shows that the projection system has better image quality, the wave aberration is better than ±0.05λ, and the variation of the wave aberration is extremely small and is within ±0.001 λ when the projection magnification is enlarged and reduced.

Embodiment two:

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

As shown in fig. 4, which is a preferred second embodiment of the present invention, the double telecentric exposure lens includes a front lens group 1, an aperture stop 2, and a rear lens group 3 disposed in this order, the aperture stop 2 being located between the front lens group 1 and the rear lens group 3.

As shown in fig. 4, the projection optical system is composed of a total of 8 lenses of the front lens group 1, the aperture stop 2, and the rear lens group 3 in order from the object plane side. The front lens group 1 has positive power, and the rear lens group 3 has positive power.

The rear lens group 3 includes 4 lenses, and from the object space to the image space, the following are: a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8; the fifth lens L5 is a meniscus lens with positive focal power, the object side surface is a convex surface, and the image side surface is a concave surface; the sixth lens L6 is a biconcave lens and has negative focal power; the seventh lens L7 is a biconvex lens having positive optical power; the eighth lens is a biconvex lens L8 having positive optical power.

The fifth lens L5 is a convex lens with positive focal power, the sixth lens L6 is a concave lens with negative focal power, the positions of the fifth lens L5 and the sixth lens L6 are close to the aperture stop 2, and the clear apertures of the two lenses are similar in size. After the upper light, the lower light and the main light of the on-axis view field and the edge view field are converged by the diaphragm, the same area of the clear aperture of the fifth lens L5 and the sixth lens L6 can be passed through, and the on-axis chromatic aberration and the off-axis chromatic aberration can be corrected at the same time. And the sixth lens L6 is the only concave lens in the rear lens group 3, and can generate spherical aberration, coma aberration, curvature of field and distortion opposite to the convex lens direction, so as to avoid generating excessive high-order spherical aberration and high-order curvature of field and balance the total aberration of the optical system.

relation 1: -0.65 < F3/F4 < -0.3; relation 2: -0.65 < F3/Fo < 0;

relation 3: -0.18 < F6/F7 < -0.1; relation 4: -0.08 < F6/Fi < -0.04;

relation 5: R9/R10 is more than 0 and less than 0.45;

relation 6: -2.5 < R14/T14 < -1.26;

The internal air space of the projection optical system in the embodiment of the invention satisfies the following relation: :

The design parameters of the projection optical system in the embodiment of the invention are shown in table 5, the NA of the object space is 0.06, the height of the field of view of the object space is 11.3mm, the magnification is-2.74986, the working distance of the object space is 110.30mm, the working distance of the image space is 110.28mm, and the conjugate distance of the object image is 498.36mm. For optical processing, optical inspection is convenient and cost-effective, and all optical elements of the present invention are spherical or planar without any aspheric element.

Object space numerical aperture NA	0.06
		Object view field (line view field)	11.3mm
Magnification ratio	-2.74986
		Working distance of object space	111.30mm
Working distance of image space	110.28mm
		Object-image conjugate distance	498.36mm

TABLE 5

Table 6 gives specific parameters of each lens of the projection optical system of the present embodiment. Wherein the column of the surface number indicates the number corresponding to each surface between the object plane and the image plane; the column "radius of curvature (mm)" gives the radius of curvature of the corresponding sphere or plane of each surface; the column "thickness/pitch (mm)" gives the axial distance between two adjacent surfaces, if the two surfaces belong to the same lens, the value "thickness/pitch" indicates the center thickness of the lens, otherwise the object plane or image plane to lens distance or air spacing of the adjacent lenses; "N _d "a column indicates the refractive index for each lens between the object plane and the image plane; v (V) _d "column indicates the dispersion coefficient of the corresponding lens; the column "clear aperture (mm)" indicates the clear aperture value of the corresponding surface. Besides the lens, the optical system is provided with a piece of plate protection glass with the thickness of 3mm at the position 0.48mm away from the object plane, and the optical system is not involved in the design of the optical system.

Surface serial number	Radius of curvature (mm)	Thickness/spacing (mm)	N _d	V _d	Clear aperture (mm)
						Object plane		0
1	Infinite number of cases	0.48			22.60
						2	Infinite number of cases	3.00	1.49	65.81	22.66
3	Infinite number of cases	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 plane	Infinite number of cases	-0.07			62.21

TABLE 6

Table 7 shows the relationship between the projection magnification of the projection optical system of the present embodiment and the displacement amount of the seventh lens L7. As can be seen from table 7, the present invention can adjust the projection magnification of the optical system between-2.74986 and-2.75201 by adjusting the position of the seventh lens L7.

TABLE 7

Table 8 shows the calculation results of the relation of the symmetrical double telecentric projection optical system of the present embodiment, and from the calculation results, it can be seen that the present invention can effectively satisfy the relation (1) to the relation (9).

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

TABLE 8

Fig. 5a is a schematic diagram of the distortion percentage of the projection magnification of the projection objective system at the zoom position 1, and fig. 5b is a schematic diagram of the distortion percentage of the projection magnification of the projection objective system at the zoom position 2, which shows that the relative distortion of the projection system is better than 0.002%, and the variation of the distortion is very small when the projection magnification is enlarged and reduced.

Fig. 6a is a schematic wave aberration diagram of the projection magnification of the projection objective system at the zoom position 1, and fig. 6b is a schematic wave aberration diagram of the projection magnification of the projection objective system at the zoom position 2, which shows that the projection system has better image quality, the wave aberration is better than ±0.03λ, and the variation of the wave aberration is extremely small and is within ±0.003 λ when the projection magnification is enlarged and reduced.

Embodiment III:

As shown in fig. 7, which is a preferred third embodiment of the present invention, the double telecentric exposure lens includes a front lens group 1, an aperture stop 2, and a rear lens group 3 disposed in this order, the aperture stop 2 being located between the front lens group 1 and the rear lens group 3.

As shown in fig. 7, the projection optical system is composed of a total of 8 lenses of the front lens group 1, the aperture stop 2, and the rear lens group 3 in order from the object plane side. The front lens group 1 has positive power, and the rear lens group 3 has positive power.

relation 1: -0.65 < F3/F4 < -0.3; relation 2: -0.65 < F3/Fo < 0;

relation 3: -0.18 < F6/F7 < -0.1; relation 4: -0.08 < F6/Fi < -0.04;

The design parameters of the projection optical system in the embodiment of the invention are shown in table 9, the NA of the object space is 0.06, the height of the field of view of the object space is 11.3mm, the magnification is-2.74985, the working distance of the object space is 113.24mm, the working distance of the image space is 110.10mm, and the conjugate distance of the object image is 498.72mm. For optical processing, optical inspection is convenient and cost-effective, and all optical elements of the present invention are spherical or planar without any aspheric element.

Object space numerical aperture NA	0.06
		Object view field (line view field)	11.3mm
Magnification ratio	-2.74985
		Working distance of object space	113.24mm
Working distance of image space	110.10mm
		Object-image conjugate distance	498.72mm

TABLE 9

Table 10 shows specific parameters of each lens of the projection optical system of the present embodiment. Wherein the column of the surface number indicates the number corresponding to each surface between the object plane and the image plane; the column "radius of curvature (mm)" gives the radius of curvature of the corresponding sphere or plane of each surface; the column "thickness/pitch (mm)" gives the axial distance between two adjacent surfaces, if the two surfaces belong to the same lens, the value "thickness/pitch" indicates the center thickness of the lens, otherwise the object plane or image plane to lens distance or air spacing of the adjacent lenses; "N _d "a column indicates the refractive index for each lens between the object plane and the image plane; v (V) _d "column indicates the dispersion coefficient of the corresponding lens; the column "clear aperture (mm)" indicates the clear aperture value of the corresponding surface. Besides the lens, the optical system is provided with a piece of plate protection glass with the thickness of 3mm at the position 0.48mm away from the object plane, and the optical system is not involved in the design of the optical system.

Table 10

Table 11 shows the relationship between the projection magnification of the projection optical system of the present embodiment and the displacement amount of the seventh lens (L7). As can be seen from table 11, the present invention can adjust the projection magnification of the optical system between-2.74985 and-2.75200 by adjusting the position of the seventh lens L7.

	Zoom position 1	Zoom position 2
			Working distance of object space	113.24	113.24
Working distance of image space	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

TABLE 11

Table 12 shows the calculation results of the relation of the symmetrical double telecentric projection optical system of the present embodiment, and from the calculation results, it can be seen that the present invention can effectively satisfy the relation (1) to the relation (9).

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

Table 12

Fig. 8a is a schematic diagram of the distortion percentage of the projection magnification of the projection objective system at the zoom position 1, and fig. 8b is a schematic diagram of the distortion percentage of the projection magnification of the projection objective system at the zoom position 2, which shows that the relative distortion of the projection system is better than 0.002%, and the variation of the distortion is very small when the projection magnification is enlarged and reduced.

Fig. 9a is a schematic wave aberration diagram of the projection magnification of the projection objective system at the zoom position 1, and fig. 9b is a schematic wave aberration diagram of the projection magnification of the projection objective system at the zoom position 2, which shows that the projection system has better image quality, the wave aberration is better than ±0.02λ, and the variation of the wave aberration is extremely small and is within ±0.003 λ when the projection magnification is enlarged and reduced.

Embodiment four:

As shown in fig. 10, which is a preferred fourth embodiment of the present invention, the double telecentric exposure lens includes a front lens group 1, an aperture stop 2, and a rear lens group 3 disposed in this order, the aperture stop 2 being located between the front lens group 1 and the rear lens group 3.

Referring to fig. 10, the projection optical system is composed of a total of 8 lenses of a front lens group 1, an aperture stop 2, and a rear lens group 3 in order from the object plane side. The front lens group 1 has positive power, and the rear lens group 3 has positive power.

The rear lens group 3 includes 4 lenses, and from the object space to the image space, the following are: a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8; the fifth lens L5 is a meniscus lens with positive focal power, the object side surface is a convex surface, and the image side surface is a concave surface; the sixth lens L6 is a biconcave lens and has negative focal power; the seventh lens L7 is a meniscus lens with positive focal power, the object side surface is a concave surface, and the image side surface is a convex surface; the eighth lens L8 is a biconvex lens having positive optical power.

relation 1: -0.65 < F3/F4 < -0.3; relation 2: -0.65 < F3/Fo < 0;

relation 3: -0.18 < F6/F7 < -0.1;

relation 4: -0.08 < F6/Fi < -0.04;

The design parameters of the projection optical system in the embodiment of the invention are shown in table 13, wherein the NA of the object space is 0.04, the height of the field of view of the object space is 11.3mm, the magnification is-2.75005, the working distance of the object space is 102.13mm, the working distance of the image space is 159.30mm, and the conjugate distance of the object image is 499.70mm. For optical processing, optical inspection is convenient and cost-effective, and all optical elements of the present invention are spherical or planar without any aspheric element.

TABLE 13

Table 14 shows specific parameters of each lens of the projection optical system of the present embodiment. Wherein the column of the surface number indicates the number corresponding to each surface between the object plane and the image plane; the column "radius of curvature (mm)" gives the radius of curvature of the corresponding sphere or plane of each surface; the column "thickness/pitch (mm)" gives the axial distance between two adjacent surfaces, if the two surfaces belong to the same lens, the value "thickness/pitch" indicates the center thickness of the lens, otherwise the object plane or image plane to lens distance or air spacing of the adjacent lenses; "N _d "a column indicates the refractive index for each lens between the object plane and the image plane; v (V) _d "column indicates the dispersion coefficient of the corresponding lens; the column "clear aperture (mm)" indicates the clear aperture value of the corresponding surface. Besides the lens, the optical system is provided with a piece of plate protection glass with the thickness of 3mm at the position 0.48mm away from the object plane, and the optical system is not involved in the design of the optical system.

TABLE 14

Table 15 shows the relationship between the projection magnification of the projection optical system of the present embodiment and the displacement amount of the seventh lens L7. As can be seen from table 7, the present invention can adjust the projection magnification of the optical system between-2.75005 and-2.75221 by adjusting the position of the seventh lens L7.

	Zoom position 1	Zoom position 2
			Working distance of object space	102.13	102.13
Working distance of image space	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

TABLE 15

Table 16 shows the calculation results of the relation of the symmetrical double telecentric projection optical system of the present embodiment, and from the calculation results, it can be seen that the present invention can effectively satisfy the relation (1) to the relation (9).

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

Table 16

Fig. 11a is a schematic view of the distortion percentage of the projection magnification of the projection objective system at the zoom position 1, and fig. 11b is a schematic view of the distortion percentage of the projection magnification of the projection objective system at the zoom position 2, which shows that the relative distortion of the projection system is better than 0.002%, and the variation of the distortion is very small when the projection magnification is enlarged and reduced.

Fig. 12a is a schematic wave aberration diagram of the projection magnification of the projection objective system at the zoom position 1, and fig. 12b is a schematic wave aberration diagram of the projection magnification of the projection objective system at the zoom position 2, which shows that the projection system has better image quality, the wave aberration is better than ±0.03λ, and the variation of the wave aberration is extremely small and is within ±0.003 λ when the projection magnification is enlarged and reduced.

Fifth embodiment:

As shown in fig. 13, which is a preferred fifth embodiment of the present invention, the double telecentric exposure lens includes a front lens group 1, an aperture stop 2, and a rear lens group 3 disposed in this order, the aperture stop 2 being located between the front lens group 1 and the rear lens group 3.

Referring to fig. 13, the projection optical system is composed of a total of 8 lenses of a front lens group 1, an aperture stop 2, and a rear lens group 3 in order from the object plane side. The front lens group 1 has positive power, and the rear lens group 3 has positive power.

The front lens group 1 comprises 4 lenses, and the lens groups are sequentially from an object space to an image space: a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4; the first lens L1 is a biconvex lens having positive optical power; the second lens L2 is a meniscus lens and has positive focal power, the object side surface of the second lens L2 is a convex surface, and the image side surface of the second lens L2 is a concave surface; the third lens L3 is a biconcave lens having negative optical power. The fourth lens element L4 has a positive refractive power, and has a convex object-side surface and a concave image-side surface.

relation 1: -0.65 < F3/F4 < -0.3; relation 2: -0.65 < F3/Fo < 0;

relation 3: -0.18 < F6/F7 < -0.1; relation 4: -0.08 < F6/Fi < -0.04;

The design parameters of the projection optical system in the embodiment of the invention are shown in table 17, wherein the NA of the object space is 0.07, the height of the field of view of the object space is 11.3mm, the magnification is-2.75005, the working distance of the object space is 112.84mm, the working distance of the image space is 109.72mm, and the conjugate distance of the object image is 496.69mm. For optical processing, optical inspection is convenient and cost-effective, and all optical elements of the present invention are spherical or planar without any aspheric element.

Object space numerical aperture NA	0.07
		Object view field (line view field)	11.3mm
Magnification ratio	-2.75003
		Working distance of object space	112.84mm
Working distance of image space	109.72mm
		Object-image conjugate distance	496.69mm

TABLE 17

Table 18 shows specific parameters of each lens of the projection optical system of the present embodiment. Wherein the column of the surface number indicates the number corresponding to each surface between the object plane and the image plane; the column "radius of curvature (mm)" gives the radius of curvature of the corresponding sphere or plane of each surface; the column "thickness/spacing (mm)" gives the axial distance between two adjacent surfaces, and if the two surfaces belong to the same lens, the "thickness/spacing" is a table of values Showing the center thickness of the lens, otherwise representing the object plane or image plane to lens distance or air spacing of adjacent lenses; "N _d "a column indicates the refractive index for each lens between the object plane and the image plane; v (V) _d "column indicates the dispersion coefficient of the corresponding lens; the column "clear aperture (mm)" indicates the clear aperture value of the corresponding surface.

TABLE 18

Table 19 shows the relationship between the projection magnification of the projection optical system of the present embodiment and the displacement amount of the seventh lens L7. As can be seen from table 7, the present invention can adjust the projection magnification of the optical system between-2.75003 and-2.75214 by adjusting the position of the seventh lens L7.

	Zoom position 1	Zoom position 2
			Working distance of object space	112.84	112.84
Work of image sideDistance from each other	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

TABLE 19

Table 20 shows the calculation results of the relation of the symmetrical double telecentric projection optical system of the present embodiment, and from the calculation results, it can be seen that the present invention can effectively satisfy the relation (1) to the relation (9).

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

Table 20

Fig. 14a is a schematic view of the distortion percentage of the projection magnification of the projection objective system at the zoom position 1, and fig. 14b is a schematic view of the distortion percentage of the projection magnification of the projection objective system at the zoom position 2, which shows that the relative distortion of the projection system is better than 0.002%, and the variation of the distortion is very small when the projection magnification is enlarged and reduced.

Fig. 15a is a schematic wave aberration diagram of the projection magnification of the projection objective system at the zoom position 1, and fig. 15b is a schematic wave aberration diagram of the projection magnification of the projection objective system at the zoom position 2, which shows that the projection system has better image quality, the wave aberration is better than ±0.03λ, and the variation of the wave aberration is extremely small and is within ±0.003 λ when the projection magnification is enlarged and reduced.

In summary, the beneficial effects of the invention are as follows:

Finally, it should be noted that: the foregoing description is only a preferred embodiment of the present invention, and the present invention is not limited thereto, but it is to be understood that modifications and equivalents of some of the technical features described in the foregoing embodiments may be made by those skilled in the art, although the present invention has been described in detail with reference to the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An adjustable multiplying power double telecentric projection optical system adopts a double telecentric structure, and the principal rays of an object space and an image space are parallel to an optical axis, and is characterized in that: comprises a front lens group (1), an aperture diaphragm (2) and a rear lens group (3) which are sequentially arranged from an object space to an image space;

the front lens group (1) is composed of a first positive focal power lens group;

the aperture diaphragm (2) is positioned on the confocal plane of the front lens group (1) and the rear lens group (3);

The rear lens group (3) is composed of a second positive focal power lens group, and the position relation of the corresponding lenses in the rear lens group (3) is moved to form a variable power lens to adjust the magnification of the optical system.

2. The adjustable magnification double telecentric projection optical system of claim 1, wherein: the current lens group (1) and the rear lens group (3) comprise 8 lenses, the front lens group (1) is composed of a first lens (L1), a second lens (L2), a third lens (L3) and a fourth lens (L4), and the rear lens group (3) is composed of a fifth lens (L5), a sixth lens (L6), a seventh lens (L7) and an eighth lens (L8).

3. The adjustable magnification double telecentric projection optical system of claim 2, wherein: 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) can form a variable magnification lens by moving in the rear lens group (3) so as to adjust the magnification of the optical system.

4. The adjustable magnification double telecentric projection optical system of claim 3, wherein: the third lens (L3) and the sixth lens (L6) are biconcave lenses.

5. The adjustable magnification double telecentric projection optical system of claim 2, wherein: the working wavelength of an objective lens system formed by the front lens group (1), the aperture diaphragm (2) and the rear lens group (3) is 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) adopt crown glass or light crown glass, and the material characteristics thereof satisfy:

1.43<N _d <1.65

55.00<V _d <85.00

wherein N is _d Refractive indexes of the lens first lens (L1), the second lens (L2), the fourth lens (L4), the fifth lens (L5), the seventh lens (L7) and the eighth lens (L8); v (V) _d For its corresponding dispersion coefficient;

the third lens (L3) and the sixth lens (L6) are made of flint glass or light flint glass, and the material characteristics thereof are as follows:

1.53<N _d <1.64

35.00<V _d <46.00

wherein N is _d Refractive indexes of the third lens (L3) and the sixth lens (L6); v (V) _d For its corresponding dispersion coefficient.

6. The adjustable magnification double telecentric projection optical system of claim 2, wherein all lens surfaces of the optical system are spherical or planar.

7. The adjustable magnification double telecentric projection optical system of claim 2, wherein the object side and image side working distances of the optical system are both greater than 100mm.

8. The adjustable magnification double telecentric projection optical system of claim 2, wherein the optical system satisfies the following relationship:

relation 1: -0.65 < F3/F4 < -0.3;

relation 2: -0.65 < F3/Fo < 0;

relation 3: -0.18 < F6/F7 < -0.1;

relation 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); fi is the combined focal length of the rear lens group (3).

9. The adjustable magnification double telecentric projection optical system of claim 2, wherein the optical system satisfies the following relationship:

relation 5: R9/R10 is more than 0 and less than 0.45;

relation 6: -2.5 < R14/T14 < -1.26;

wherein R9 is the curvature radius of the object side of the fifth lens (L5); r10 is the radius of curvature of the image side of the fifth lens (L5); r14 is the radius of curvature of the image side of the seventh lens (L7); t14 is the clear aperture on the image side of the seventh lens (L7).

10. The adjustable magnification double telecentric projection optical system of claim 2, wherein the optical system satisfies the following relationship:

Relation 7: t1 is more than 30.2 and less than 39.5;

relation 8: t16 is more than 64.5 and less than 70.5;

wherein T1 is the clear aperture of the object side of the first lens (L1); t16 is the clear aperture on the image side of the eighth lens (L8).