CN104730697B

CN104730697B - Wide-visual-field and high-resolution projection lens

Info

Publication number: CN104730697B
Application number: CN201510185293.XA
Authority: CN
Inventors: 刘鹏
Original assignee: Zhangjiagang Zhong He Robotization Science And Technology Ltd
Current assignee: Zhangjiagang Zhong He Robotization Science And Technology Ltd
Priority date: 2015-04-17
Filing date: 2015-04-17
Publication date: 2017-05-17
Anticipated expiration: 2035-04-17
Also published as: CN104730697A

Abstract

The invention discloses a wide-visual-field and high-resolution projection lens. The projection objective lens sequentially comprises a first lens group, a second lens group and a third lens group from an object side to an image side. A diaphragm is disposed between the first lens group and the third lens group. The second lens group at least comprises two air lenses satisfying |(r21-r22)/(r21+r22)|＜0.6, |(Vd21-Vd22)|＞28 and |(nd21-nd22)|＞0.09, wherein the curvature radius, dispersion coefficient and d line refraction index of lens surfaces on two sides of the air lenses are respectively r21, r22, Vd21, Vd22, nd21 and nd22. The second lens group further at least comprises two positive lenses satisfying dn/dt＜0 under room temperature, wherein n is refraction index, and t is temperature. The image side is provided with a concave spherical surface facing the object side, and the concave spherical surface satisfies alpha in＜NA/beta, and 0.8＜Lpout/Rim＜1.2.

Description

Wide-field-of-view high-resolution projection objective

Technical Field

The invention relates to a projection objective, in particular to a wide-field high-resolution projection objective for high-precision large-field optical detection, which is applied to the research and detection of high-resolution large fields of view in the fields of biology, heredity, medical treatment, medicines and the like.

Background

The projection objective lens is applied to the development of research and detection technologies of biology, heredity, medical treatment, medicines and the like, and the requirement of high-precision large-view-field optical detection is increasingly enhanced. Meanwhile, the design and manufacture of the projection objective with the wide spectrum, high resolution and large field-of-view performance of 3 are very difficult, and few cases exist at present.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a wide-field-of-view high-resolution projection objective lens, which realizes that various aberrations such as spherical aberration, coma aberration, astigmatism, axial chromatic aberration, magnification chromatic aberration and the like of the projection objective lens are well corrected, particularly, the two-stage spectrum of the axial chromatic aberration is well corrected, the difficulty and the cost of processing, testing and installing and correcting a lens can be reduced, and meanwhile, the wide-field-of-view high-resolution projection objective lens has a good image space telecentric projection objective lens effect and provides good conditions for later image taking.

The invention is realized by adopting the following technical scheme: a wide-field-of-view high-resolution projection objective lens comprises a first lens group, a second lens group and a third lens group in sequence from an object side to an image side;

in the second lens group, the relation: vd is (nd-1)/(nF-nC), and the number of positive lenses with nd being less than 1.65 and Vd being more than 62 is at least two, and the number of negative lenses with nd being more than 1.50 and Vd being less than 55 is at least one; vd is a dispersion coefficient and a constant for reflecting the dispersion degree of the optical material, nF is an F-line refractive index with the wavelength of 486nm, nd is a d-line refractive index with the wavelength of 587nm, and nC is a C-line refractive index with the wavelength of 656 nm;

the first lens group, the second lens group and the third lens group satisfy the relation: 0.3< f1/fa <2.8, 0.25< f2/fa <2.5, 0.25< -f3/fa < 5.5; wherein f1 is the combined focal length of the first lens group, f2 is the combined focal length of the second lens group, f3 is the combined focal length of the third lens group, fa is the combined focal length of the whole projection objective lens;

wherein, a diaphragm is arranged between the first lens group and the third lens group;

in the second lens group, at least two air lenses satisfy the following relation: l (r21-r22)/(r21+ r22) | <0.6, | (Vd21-Vd22) | > 28, | (nd21-nd22) | > 0.09; wherein r21 and r22 are respectively the curvature radius of the lens surface at two sides of the air lens, Vd21 and Vd22 are respectively the dispersion coefficient of the lens at two sides of the air lens, and nd21 and nd22 are respectively the d-line refractive index of the lens at two sides of the air lens;

and the second lens group at least comprises two positive lenses which satisfy the following conditions at room temperature: dn/dt < 0; wherein n is the refractive index, t is the temperature, and dn/dt is the temperature coefficient of the refractive index of the optical material changing with the temperature;

the image side has a concave spherical surface facing the object side, and satisfies: α in < NA/β, 0.8< Lpout/Rim < 1.2; wherein α in is an incident angle of a chief ray of the projection objective on the image side, NA is an object numerical aperture of the projection objective, β is a magnification of the projection objective, and takes a positive value, Lpout is an image exit pupil distance of the projection objective, and a curvature radius of a Rim image surface concave spherical surface.

As a further improvement of the above, in the third lens group, a pair of first concave surfaces facing each other is included, and at least one negative lens is included between the pair of first concave surfaces facing each other, and the negative lens includes a second concave surface facing the object side; the third lens group also satisfies the relation: at least one positive lens and one negative lens satisfy ndp > ndn, and at least one positive lens and one negative lens satisfy Vdp < Vdn; ndp is the d-line refractive index of the corresponding positive lens in the third lens group, ndn is the d-line refractive index of the corresponding negative lens in the third lens group, Vdp is the abbe number of the corresponding positive lens in the third lens group, and Vdn is the abbe number of the corresponding negative lens in the third lens group.

As a further improvement of the above, in the first lens group: at least one positive lens and one negative lens satisfy: ndp > ndn; at least one positive lens and one negative lens satisfy: vdp is less than Vdn; ndp is the d-line refractive index of the corresponding positive lens element in the first lens group, ndn is the d-line refractive index of the corresponding negative lens element in the first lens group, Vdp is the abbe number of the corresponding positive lens element in the first lens group, and Vdn is the abbe number of the corresponding negative lens element in the first lens group.

As a further improvement of the above solution, 4< β <18,

as a further improvement of the above scheme, all the lens surfaces of the first lens group, the second lens group and the third lens group are spherical surfaces and do not contain aspheric surfaces, and the second lens group and the third lens group are composed of single lenses which do not contain cemented surfaces.

As a further improvement of the above solution, the total number of lenses of the wide-field high-resolution projection objective lies between 12 and 28.

As a further improvement of the above scheme, the second lens group includes at least two lenses having negative optical power, and at least one of the lenses is a biconcave lens; and at least three lenses with positive focal power, wherein at least two lenses are double convex lenses.

As a further improvement of the above scheme, the third lens group includes at least two lenses having negative optical power; at least two lenses with positive optical power are also included and at least one crescent lens is included.

As a further improvement of the above solution, the first lens group includes, in order from the object side to the image side, a first lens element, a second lens element, a third lens element, and a fourth lens element, wherein the third lens element has negative refractive power, and both the second lens element and the fourth lens element have positive refractive power.

As a further improvement of the above solution, the aperture size of the diaphragm can be adjusted.

The invention has the advantages that: 1, 3 characteristics of wide spectrum, high resolution and large visual field are provided, and few cases exist at present; 2, the lens has good image space telecentric projection objective effect and provides good conditions for later image taking; 3, the maximum optical caliber of the projection objective is only about 60 percent of the caliber of the image space full field of view, thereby greatly reducing the manufacturing cost and difficulty of the projection objective. The maximum optical aperture of the common image space telecentric projection objective is more than 100 percent of the aperture of the image space full field, so the manufacturing cost is high and the manufacturing difficulty is high; 4, the lens has small caliber and does not contain an aspheric lens, thereby greatly reducing the difficulty and cost of processing, detection and installation and correction.

Drawings

Fig. 1 is a schematic structural diagram of a wide-field high-resolution projection objective lens provided in embodiment 1 of the present invention.

Fig. 2 is a schematic structural view of an air lens.

Fig. 3 is a graph of the axial chromatic aberration at the 0.7 aperture of the wide-field high-resolution projection objective of fig. 1.

FIG. 4 is a graph of MTF of the wide-field high-resolution projection objective of FIG. 1 in the wavelength range of 480-730 nm.

Fig. 5 is a schematic structural diagram of a wide-field high-resolution projection objective lens provided in embodiment 2 of the present invention.

Fig. 6 is a plot of the axial chromatic aberration at the 0.7 aperture of the wide-field high-resolution projection objective of fig. 5.

FIG. 7 is a graph of MTF of the wide-field high-resolution projection objective of FIG. 5 in the wavelength range of 480-730 nm.

Fig. 8 is a schematic structural diagram of a wide-field high-resolution projection objective lens provided in embodiment 3 of the present invention.

Fig. 9 is a plot of the axial chromatic aberration at the 0.7 aperture of the wide-field high-resolution projection objective of fig. 8.

FIG. 10 is a graph of MTF of the wide-field high-resolution projection objective of FIG. 8 in the wavelength range of 480-730 nm.

Fig. 11 is a schematic structural diagram of a wide-field high-resolution projection objective lens provided in embodiment 4 of the present invention.

Fig. 12 is a plot of the axial chromatic aberration at the 0.7 aperture of the wide-field high-resolution projection objective of fig. 4.

FIG. 13 is a graph of the MTF of the wide-field high-resolution projection objective of FIG. 4 in the wavelength range of 480-730 nm.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

Please refer to fig. 1, which is a schematic structural diagram of a wide-field high-resolution projection objective lens according to embodiment 1 of the present invention. The wide-field high-resolution projection objective lens comprises a first lens group G1, an equivalent parallel PLATE PLATE, a second lens group G2 and a third lens group G3 in sequence from an object side P1 to an image side P2. The second lens group G2 is provided with a diaphragm AS, the opening size of the diaphragm AS can be adjusted, and a diaphragm with an adjustable opening size can be adopted. The equivalent parallel PLATE platate is located between the object side P1 and the image side P2.

The first lens group G1 may include, in order from the object side P1 to the image side P2, a first lens element L1, a second lens element L2, a third lens element L3 and a fourth lens element L4. The second lens group G2 can include at least two lenses with negative focal power, and at least one of the lenses is a biconcave lens; at least three lenses having positive optical power and at least two of which are double convex lenses may also be included. In this embodiment, the second lens group G2 includes, in order from the object side P1 to the image side P2, a fifth lens element L5, a sixth lens element L6, a seventh lens element L7, an eighth lens element L8, a ninth lens element L9, a tenth lens element L10, and an eleventh lens element L11. The third lens group G3 can include at least two lenses with negative power; at least two lenses having positive optical power may also be included and at least one crescent-shaped lens. In this embodiment, the third lens group G3 includes, in order from the object side P1 to the image side P2, a twelfth lens L12, a thirteenth lens L13, a fourteenth lens L14, a fifteenth lens L15, a sixteenth lens L16, and a seventeenth lens L17.

The first lens L1, the third lens L3, the sixth lens L6, the ninth lens L9, the thirteenth lens L13, the fourteenth lens L14 and the fifteenth lens L15 all have negative focal power. The second lens L2, the fourth lens L4, the fifth lens L5, the seventh lens L7, the eighth lens L8, the tenth lens L10, the eleventh lens L11, the twelfth lens L12, the sixteenth lens L16, and the seventeenth lens L17 each have positive optical power.

In the present embodiment, the element parameters of the first to seventeenth lenses L1 to L17 are shown in table 1.

TABLE 1 projection Objective parameters

The first lens group G1, the second lens group G2 and the third lens group G3 satisfy the following relations: 0.3< f1/fa <2.8, 0.25< f2/fa <2.5, 0.25< -f3/fa < 5.5. Wherein f1 is the combined focal length of the first lens group G1, f2 is the combined focal length of the second lens group G2, f3 is the combined focal length of the third lens group G3, and fa is the combined focal length of the entire projection objective lens. The lens structure can reasonably correct various aberrations such as spherical aberration, coma aberration, astigmatism, field curvature and distortion, axial chromatic aberration, magnification chromatic aberration and the like of the projection objective. In this embodiment, f1/fa is 0.211, f2/fa is 0.282, and f3/fa is 0.150.

In the first lens group G1, at least one positive lens and one negative lens satisfy: ndp > ndn, and at least one positive lens and one negative lens satisfy: vdp is less than Vdn. Where ndp is the d-line refractive index of the positive lens, ndn is the d-line refractive index of the negative lens, Vdp is the abbe number of the positive lens, and Vdn is the abbe number of the negative lens. The primary function of the first lens group G1 is to correct the primary and high spherical aberration of the projection objective, balance the secondary spectral chromatic aberration of the axial chromatic aberration of the projection objective, and assist in balancing the chromatic aberration of magnification of the projection objective.

In the second lens group G2, the relation: vd ═ (nd-1)/(nF-nC); at least two positive lenses with nd less than 1.65 and Vd more than 62; ③ nd is more than 1.50 and Vd is less than 55; at least two air lenses satisfy the relation: l (r21-r22)/(r21+ r22) | <0.6, | (Vd21-Vd22) | > 28, | (nd21-nd22) | > 0.09; the second lens group (G2) at least contains two positive lenses which satisfy the following conditions at room temperature: dn/dt <0. Vd is a dispersion coefficient and a constant for reflecting the dispersion degree of the optical material, nF is an F-line refractive index with the wavelength of 486nm, nd is a d-line refractive index with the wavelength of 587nm, and nC is a C-line refractive index with the wavelength of 656 nm; r21 and r22 are the curvature radius of the lens surface on both sides of the air lens, Vd21 and Vd22 are the dispersion coefficient of the lens on both sides of the air lens, nd21 and nd22 are the d-line refractive index of the lens on both sides of the air lens, n is the refractive index, t is the temperature, and dn/dt is the refractive index temperature coefficient of the optical material, which changes with the temperature.

Regarding the air lens, in a lens group constituting the lens, an air space (air space) L sandwiched by two adjacent glass lenses can be regarded as a lens having a refractive index of 1.0, and an air space designed based on such consideration can be regarded as an air lens, such as the air lens L shown in fig. 2. Since the front-rear refractive index relationship of the air lens L is opposite to that of the adjacent glass lenses Lx and Ly, the convex surface has a concave lens effect, and the concave surface has a convex lens effect. Referring to fig. 1 again, in the present embodiment, there are the lens groups L6 and L7, the lens groups L8 and L9, and the lens groups L9 and L10 in the second lens group L2, which satisfy the fourteenth item: an air lens of | (r21-r22)/(r21+ r22) | <0.6, | (Vd21-Vd22) | > 28, | (nd21-nd22) | > 0.09. The calculated values of the relation | (r21-r22)/(r21+ r22) | satisfy the relation | (r21-r22)/(r21+ r22) | <0.6 as calculated values of the relation | (r21-r22)/(r21+ r22) |, respectively, 0.211, 0.282 and 0.150. The main function is to correct the primary and high-grade spherical aberration and coma aberration of the projection objective, and simultaneously correct the axial chromatic aberration of the projection objective and effectively reduce the secondary spectral chromatic aberration; the Petzval is effectively reduced and the field curvature of the projection objective can be well corrected.

The fifth row of the second lens group L2 is: the second lens group G2 at least comprises two positive lenses satisfying the following conditions at room temperature: dn/dt <0. Different from the dn/dt & gt 0 characteristic of a common optical glass material, when the positive lens satisfies the condition that the dn/dt & lt 0, the positive lens and the other common optical glass lens have the characteristics of refractive index temperature coefficients which are opposite to each other and offset with each other, so that the thermal stability of the projection objective can be improved, and the image surface position and the imaging quality of the projection objective are kept stable when the environmental temperature changes.

In the third lens group G3, the first pair of concave surfaces facing each other includes at least one negative lens therebetween, and the negative lens includes the second concave surface facing the object side P1. The third lens group G3 also satisfies the relation: at least one positive lens and one negative lens satisfy ndp > ndn, and at least one positive lens and one negative lens satisfy Vdp < Vdn. The main function of the third lens group G3 is to balance the primary and high astigmatism of the projection objective and to help reduce the secondary spectral chromatic aberration of the axial chromatic aberration and to balance the chromatic aberration of magnification of the projection objective. In this embodiment, a pair of concave surfaces facing each other is present between the thirteenth lens L13 and the fifteenth lens L15, that is, the curved surface of the thirteenth lens L13 facing the fifteenth lens L15 is a concave surface, and the curved surface of the fifteenth lens L15 facing the thirteenth lens L13 is a concave surface. Between the pair of mutually facing concave surfaces one, there is a fourteenth lens L14 being a negative lens, the fourteenth lens L14 having a concave surface two facing the object side P1, i.e., the curved surface of the fourteenth lens L14 facing the object side P1 is also concave.

In order to eliminate internal stress, thermal stress and aging of the optical lenses and adverse effects on optical imaging caused by the internal stress, thermal stress and aging, and maintain stability of the projection objective, all lens surfaces in the first lens group G1, the second lens group G2 and the third lens group G3 are spherical and do not contain aspheric surfaces, and the second lens group G2 and the third lens group G3 are composed of single lenses which do not contain cemented surfaces. In addition, the non-spherical lens is not included, so that the difficulty and cost of processing, detection and installation and correction can be greatly reduced.

In order to obtain a good image-space telecentric projection objective effect and provide good conditions for later image capturing, the image side P2 has a concave spherical surface facing the object side P1, and satisfies: α in < NA/β, 0.8< Lpout/Rim < 1.2; where α in is an incident angle of a chief ray of the projection objective on the image side P2, NA is an object-side numerical aperture of the projection objective, β is a magnification of the projection objective, Lpout is an image-side exit pupil distance of the projection objective, and a curvature radius of a Rim image surface concave spherical surface.

In the present embodiment, the parameter values of the projection objective lens are: β ═ 10; NA is 0.35; hy ═ 21.2; spectral range: 470-750 nm. Wherein beta is projection magnification, 4< beta < 18; NA is the number of the opening on the object side; hy is maximal height.

An equivalent parallel flat plate is disposed between first lens group G1 and third lens group G3 (in this embodiment, the equivalent parallel flat plate is disposed between first lens group G1 and second lens group G2), and the equivalent parallel flat plate satisfies: tpl > 0.6 Dop. The equivalent parallel plate is a light splitting device with partial transmission and partial reflection, and the main function of the equivalent parallel plate is to realize various coaxial epi-illumination by utilizing the light splitting functions of partial transmission and partial reflection of the equivalent parallel plate.

For a reasonable cost control and optimum cost performance of the wide-field high-resolution projection objective, the total number of lenses of the wide-field high-resolution projection objective is between 12 and 28.

In summary, in the present embodiment, the three groups of lenses adopting such a lens structure finally ensure and realize good correction of various aberrations such as spherical aberration, coma aberration, astigmatism, curvature of field and distortion, axial chromatic aberration and magnification chromatic aberration of the projection objective, and at the same time, the maximum optical aperture of the lens can be effectively controlled, and the difficulty and cost of processing, testing and assembling the lens can be reduced.

In the wide-field high-resolution projection objective of the present embodiment, the axial chromatic aberration of the wide-field high-resolution projection objective is shown in fig. 3, which effectively corrects the axial chromatic aberration within a broad band range, covering the wavelength range of 480-730 nm. As can be seen from the figure, the present invention can effectively achieve high imaging quality. The MTF of the transfer function of the projection objective of the wide-field high-resolution projection objective in the wavelength range of 480-730nm is shown in FIG. 4. The results of the wave aberration wfe (rms) analysis of the professional optical design software show that: the wave aberration wfe (rms) at each wavelength was not more than 1/14 at the wavelength, as shown in table 2.

TABLE 2 wave aberration at each wavelength

Wavelength (nm)	Name (R)	Wave aberration (RMS)
			486.13	F line	1/14λ
546.07	e line	1/19λ
			587.56	d line	1/21λ
656.27	C line	1/19λ
			706.52	r line	1/16λ
730	---	1/15λ
			480-730	Range of wavelengths	1/15λ

Example 2

Please refer to fig. 5, which is a schematic structural diagram of a wide-field high-resolution projection objective lens according to embodiment 2 of the present invention. The wide-field high-resolution projection objective lens comprises a first lens group G1, a second lens group G2 and a third lens group G3 in sequence from an object side P1 to an image side P2. The second lens group G2 is provided with a diaphragm AS, the opening size of the diaphragm AS can be adjusted, and a diaphragm with an adjustable opening size can be adopted.

From the object side P1 to the image side P2, the first lens group G1 may include, in order, a first lens element L1, a second lens element L2, a third lens element L3, and a fourth lens element L4; the second lens group G2 may include, in order, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, and an eleventh lens L11; the third lens group G3 may include a twelfth lens element L12, a thirteenth lens element L13, a fourteenth lens element L14, a fifteenth lens element L15, and a sixteenth lens element L16 in this order.

The third lens L3, the sixth lens (L6), the ninth lens L9, the twelfth lens L12 and the thirteenth lens L13 all have negative focal power. The second lens L2, the fourth lens L4, the fifth lens L5, the seventh lens L7, the eighth lens L8, the tenth lens L10, the eleventh lens L11, the fifteenth lens L15, and the sixteenth lens L16 all have positive refractive power.

In the present embodiment, the element parameters of the first to sixteenth lenses L1 to L16 are shown in table 3.

TABLE 3 projection Objective parameters

The first lens group G1, the second lens group G2 and the third lens group G3 satisfy the following relations: 0.3< f1/fa <2.8, 0.25< f2/fa <2.5, 0.25< -f3/fa < 5.5. Wherein f1 is the combined focal length of the first lens group G1, f2 is the combined focal length of the second lens group G2, f3 is the combined focal length of the third lens group G3, and fa is the combined focal length of the entire projection objective lens. The lens structure can reasonably correct various aberrations such as spherical aberration, coma aberration, astigmatism, field curvature and distortion, axial chromatic aberration, magnification chromatic aberration and the like of the projection objective. In this embodiment, f1 is 238.02, f2 is 198.01, f3 is-450.5, fa is 219.8, f1/fa is 0.82, f2/fa is 0.92, and f3/fa is 1.68.

In the second lens group G2, the relation: vd ═ (nd-1)/(nF-nC); at least two positive lenses with nd less than 1.65 and Vd more than 62; ③ nd is more than 1.50 and Vd is less than 55; at least two air lenses satisfy the relation: l (r21-r22)/(r21+ r22) | <0.6, | (Vd21-Vd22) | > 28, | (nd21-nd22) | > 0.09; the second lens group (G2) at least contains two positive lenses which satisfy the following conditions at room temperature: dn/dt <0. Wherein Vd is a dispersion coefficient and a constant representing the dispersion degree of the optical material, nF is the F-line refractive index of 486nm wavelength, nd is the d-line refractive index of 587nm wavelength,

nC is the refractive index of C line with the wavelength of 656 nm;

r21 and r22 are the radii of curvature of the lens surfaces on both sides of the air lens,

vd21 and Vd22 are respectively the dispersion coefficients of the lenses at both sides of the air lens,

nd21 and nd22 are d-line refractive indexes of the lenses on both sides of the air lens, n is a refractive index, t is temperature, and dn/dt is a temperature coefficient of refractive index of the optical material varying with temperature.

In the present embodiment, the fourth condition is satisfied in all of the positions between lenses L6 and L7, between lenses L8 and L9, and between lenses L9 and L10 of second lens group L2: an air lens of | (r21-r22)/(r21+ r22) | <0.6, | (Vd21-Vd22) | > 28, | (nd21-nd22) | > 0.09. The calculated values of the relation | (r21-r22)/(r21+ r22) | are 0.203, 0.035 and 0.184 respectively, and the relation | (r21-r22)/(r21+ r22) | <0.6 is satisfied. The main function is to correct the primary and high-grade spherical aberration and coma aberration of the projection objective, and simultaneously correct the axial chromatic aberration of the projection objective and effectively reduce the secondary spectral chromatic aberration; the Petzval is effectively reduced and the field curvature of the projection objective can be well corrected.

In the third lens group G3, the first pair of concave surfaces facing each other includes at least one negative lens therebetween, and the negative lens includes the second concave surface facing the object side P1. The third lens group G3 also satisfies the relation: at least one positive lens and one negative lens satisfy ndp > ndn, and at least one positive lens and one negative lens satisfy Vdp < Vdn. The main function of the third lens group G3 is to balance the primary and high astigmatism of the projection objective and to help reduce the secondary spectral chromatic aberration of the axial chromatic aberration and to balance the chromatic aberration of magnification of the projection objective. In the present embodiment, a pair of concave surfaces facing each other exist between the twelfth lens L12 and the fourteenth lens L14, that is, the curved surface of the twelfth lens L12 facing the fourteenth lens L14 is a concave surface, and the curved surface of the fourteenth lens L14 facing the twelfth lens L12 is a concave surface. Between the pair of mutually facing concave surfaces one, there is a thirteenth lens L13 being a negative lens, the thirteenth lens L13 having a concave surface two facing the object side P1, i.e., the curved surface of the thirteenth lens L13 facing the object side P1 is also concave.

In the wide-field high-resolution projection objective of the present embodiment, the axial chromatic aberration of the wide-field high-resolution projection objective is shown in fig. 6, which effectively corrects the axial chromatic aberration within a broad band range, covering the wavelength range of 480-730 nm. As can be seen from the figure, the present invention can effectively achieve high imaging quality. The MTF plot of the transfer function of the projection objective of the wide-field high-resolution projection objective in the wavelength range of 480-730nm is shown in FIG. 7. The results of the wave aberration wfe (rms) analysis of the professional optical design software show that: the wave aberrations WFE (RMS) in the wavelength range of 480-730nm are all below 1/15 of the wavelength, as shown in Table 4.

TABLE 4 wave aberration at each wavelength

Wavelength (nm)	Name (R)	Wave aberration (RMS)	Wave aberration (RMS)
				486.13	F line	1/10λ	0.097λ
546.07	e line	1/20λ	0.049λ
				587.56	d line	1/17λ	0.06λ
656.27	C line	1/14λ	0.072λ
				706.52	r line	1/12λ	0.084λ
730	---	1/11λ	0.088λ
				480-730	Range of wavelengths	1/15λ	0.065λ

Example 3

Please refer to fig. 8, which is a schematic structural diagram of a wide-field high-resolution projection objective lens according to embodiment 3 of the present invention. The wide-field high-resolution projection objective lens comprises a first lens group G1, a second lens group G2 and a third lens group G3 in sequence from an object side P1 to an image side P2. The second lens group G2 is provided with a diaphragm AS, the opening size of the diaphragm AS can be adjusted, and a diaphragm with an adjustable opening size can be adopted.

The first lens group G1 may include, in order from the object side P1 to the image side P2, a first lens element L1, a second lens element L2, a third lens element L3 and a fourth lens element L4. The second lens group G2 can include at least two lenses with negative focal power, and at least one of the lenses is a biconcave lens; at least three lenses having positive optical power and at least two of which are double convex lenses may also be included. In this embodiment, the second lens group G2 includes, in order from the object side P1 to the image side P2, a fifth lens element L5, a sixth lens element L6, a seventh lens element L7, an eighth lens element L8, a ninth lens element L9, a tenth lens element L10, and an eleventh lens element L11. The third lens group G3 can include at least two lenses with negative power; at least two lenses having positive optical power may also be included and at least one crescent-shaped lens. In this embodiment, the third lens group G3 includes, in order from the object side P1 to the image side P2, a twelfth lens element L12, a thirteenth lens element L13, a fourteenth lens element L14, a fifteenth lens element L15 and a sixteenth lens element L16.

In the present embodiment, the element parameters of the first to sixteenth lenses L1 to L16 are shown in table 5.

TABLE 5 projection Objective parameters

The first lens group G1, the second lens group G2 and the third lens group G3 satisfy the following relations: 0.3< f1/fa <2.8, 0.25< f2/fa <2.5, 0.25< -f3/fa < 5.5. Wherein f1 is the combined focal length of the first lens group G1, f2 is the combined focal length of the second lens group G2, f3 is the combined focal length of the third lens group G3, and fa is the combined focal length of the entire projection objective lens. The lens structure can reasonably correct various aberrations such as spherical aberration, coma aberration, astigmatism, field curvature and distortion, axial chromatic aberration, magnification chromatic aberration and the like of the projection objective. In this embodiment, f1/fa is 0.82, f2/fa is 0.82, and f3/fa is 2.06.

In the present embodiment, the fourth condition is satisfied in all of the positions between lenses L6 and L7, between lenses L8 and L9, and between lenses L9 and L10 of second lens group L2: an air lens of | (r21-r22)/(r21+ r22) | <0.6, | (Vd21-Vd22) | > 28, | (nd21-nd22) | > 0.09. The calculated values of the relation | (r21-r22)/(r21+ r22) | satisfy the relation | (r21-r22)/(r21+ r22) | <0.6 as calculated values of the relation | (r21-r22)/(r21+ r22) | are 0.247, 0.054 and 0.166, respectively. The main function is to correct the primary and high-grade spherical aberration and coma aberration of the projection objective, and simultaneously correct the axial chromatic aberration of the projection objective and effectively reduce the secondary spectral chromatic aberration; the Petzval is effectively reduced and the field curvature of the projection objective can be well corrected.

In the wide-field high-resolution projection objective of the present embodiment, the axial chromatic aberration of the wide-field high-resolution projection objective is shown in fig. 9, which effectively corrects the axial chromatic aberration within a broad band range, covering the wavelength range of 480-730 nm. As can be seen from the figure, the present invention can effectively achieve high imaging quality. The MTF of the transfer function of the projection objective of the wide-field high-resolution projection objective in the wavelength range of 480-730nm is shown in FIG. 10. The results of the wave aberration wfe (rms) analysis of the professional optical design software show that: the wave aberration wfe (rms) at each wavelength was not more than 1/14 at the wavelength, as shown in table 6.

Table 6 wave aberration at each wavelength.

Wavelength (nm)	Name (R)	Wave aberration (RMS)	Wave aberration (RMS)
				486.13	F line	1/9λ	0.11λ
546.07	e line	1/19λ	0.053λ
				587.56	d line	1/18λ	0.055λ
656.27	C line	1/14λ	0.073λ
				706.52	r line	1/11λ	0.09λ
730	---	1/10λ	0.1λ
				480-730	Range of wavelengths	1/14λ	0.072λ

Example 4

Please refer to fig. 11, which is a schematic structural diagram of a wide-field high-resolution projection objective lens according to embodiment 4 of the present invention. The wide-field high-resolution projection objective lens comprises a first lens group G1, an equivalent parallel PLATE PLATE, a second lens group G2 and a third lens group G3 in sequence from an object side P1 to an image side P2. The second lens group G2 is provided with a diaphragm AS, the opening size of the diaphragm AS can be adjusted, and a diaphragm with an adjustable opening size can be adopted.

From the object side P1 to the image side P2, the first lens group G1 may include, in order, a first lens element L1, a second lens element L2, a third lens element L3, and a fourth lens element L4; the second lens group G2 may include, in order, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, and an eleventh lens L11; the third lens group G3 may include a twelfth lens element L12, a thirteenth lens element L13, a fourteenth lens element L14, a fifteenth lens element L15, a sixteenth lens element L16, and a seventeenth lens element L17 in this order.

The first lens L1, the third lens L3, the sixth lens (L6), the ninth lens L9, the thirteenth lens L13, the fourteenth lens L14 and the fifteenth lens L15 all have negative focal power. The second lens L2, the fourth lens L4, the fifth lens L5, the seventh lens L7, the eighth lens L8, the tenth lens L10, the eleventh lens L11, the twelfth lens L12, the sixteenth lens L16, and the seventeenth lens L17 each have positive optical power.

In the present embodiment, the element parameters of the first to seventeenth lenses L1 to L17 are shown in table 7.

TABLE 7 projection Objective parameters

The first lens group G1, the second lens group G2 and the third lens group G3 satisfy the following relations: 0.3< f1/fa <2.8, 0.25< f2/fa <2.5, 0.25< -f3/fa < 5.5. Wherein f1 is the combined focal length of the first lens group G1, f2 is the combined focal length of the second lens group G2, f3 is the combined focal length of the third lens group G3, and fa is the combined focal length of the entire projection objective lens. The lens structure can reasonably correct various aberrations such as spherical aberration, coma aberration, astigmatism, field curvature and distortion, axial chromatic aberration, magnification chromatic aberration and the like of the projection objective. In this embodiment, f1/fa is 1.18, f2/fa is 0.90, and f3/fa is 2.02.

In the present embodiment, the fourth condition is satisfied in all of the positions between lenses L6 and L7, between lenses L8 and L9, and between lenses L9 and L10 of second lens group L2: an air lens of | (r21-r22)/(r21+ r22) | <0.6, | (Vd21-Vd22) | > 28, | (nd21-nd22) | > 0.09. The calculated values of the relation | (r21-r22)/(r21+ r22) | are 0.220, 0.264 and 0.166 respectively, and the relation | (r21-r22)/(r21+ r22) | <0.6 is satisfied. The main function is to correct the primary and high-grade spherical aberration and coma aberration of the projection objective, and simultaneously correct the axial chromatic aberration of the projection objective and effectively reduce the secondary spectral chromatic aberration; the Petzval is effectively reduced and the field curvature of the projection objective can be well corrected.

An equivalent parallel flat plate is disposed between first lens group G1 and third lens group G3 (in this embodiment, the equivalent parallel flat plate is disposed between first lens group G1 and second lens group G2), and the equivalent parallel flat plate satisfies: tpl > 0.6 Dop. The equivalent parallel plate comprises one or more layers of thin films and is a light splitting device with partial transmission and partial reflection, and the main function of the equivalent parallel plate is to realize various coaxial epi-illumination by utilizing the light splitting functions of partial transmission and partial reflection of the equivalent parallel plate.

In the wide-field high-resolution projection objective of the present embodiment, the axial chromatic aberration of the wide-field high-resolution projection objective is shown in fig. 12, which effectively corrects the axial chromatic aberration within a broad band range, covering the wavelength range of 480-730 nm. As can be seen from the figure, the present invention can effectively achieve high imaging quality. The MTF plot of the transfer function of the projection objective of the wide-field high-resolution projection objective in the wavelength range of 480-730nm is shown in FIG. 13. The results of the wave aberration wfe (rms) analysis of the professional optical design software show that: the wave aberration wfe (rms) at each wavelength was not more than 1/14 at the wavelength, as shown in table 8.

Table 8 wave aberration at each wavelength. .

Wavelength (nm)	Name (R)	Wave aberration (RMS)	Wave aberration (RMS)
				486.13	F line	1/13λ	0.078λ
546.07	e line	1/18λ	0.056λ
				587.56	d line	1/18λ	0.055λ
656.27	C line	1/14λ	0.069λ
				706.52	r line	1/12λ	0.084λ
730	---	1/11λ	0.091λ
				480-730	Range of wavelengths	1/14λ	0.071λ

In conclusion, the invention has 3 characteristics of wide spectrum, high resolution and large visual field, and has few precedents at present; the lens has good image space telecentric projection objective effect and provides good conditions for later image taking; the maximum optical caliber of the projection objective is only about 60% of the caliber of the image space full field of view, and the manufacturing cost and the difficulty of the projection objective are greatly reduced. The maximum optical aperture of the common image space telecentric projection objective is more than 100 percent of the aperture of the image space full field, so the manufacturing cost is high and the manufacturing difficulty is high; the lens has small caliber and does not comprise an aspheric lens, so that the difficulty and the cost of processing, detection and assembly and calibration are greatly reduced; the light splitting function of partial transmission and partial reflection of the equivalent parallel flat plate can be utilized to realize various coaxial epi-illumination.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A wide-field high-resolution projection objective comprises, in order from an object side (P1) to an image side (P2), a first lens group (G1), a second lens group (G2), and a third lens group (G3); wherein,

in the second lens group (G2), the relation: vd is (nd-1)/(nF-nC), and the number of positive lenses with nd being less than 1.65 and Vd being more than 62 is at least two, and the number of negative lenses with nd being more than 1.50 and Vd being less than 55 is at least one; vd is a dispersion coefficient and a constant for reflecting the dispersion degree of the optical material, nF is an F-line refractive index with the wavelength of 486nm, nd is a d-line refractive index with the wavelength of 587nm, and nC is a C-line refractive index with the wavelength of 656 nm;

the first lens group (G1), the second lens group (G2) and the third lens group (G3) satisfy the following relations: 0.3< f1/fa <2.8, 0.25< f2/fa <2.5, 0.25< -f3/fa < 5.5; wherein f1 is the combined focal length of the first lens group (G1), f2 is the combined focal length of the second lens group (G2), f3 is the combined focal length of the third lens group (G3), and fa is the combined focal length of the whole projection objective lens;

the method is characterized in that:

a diaphragm (AS) is arranged between the first lens group (G1) and the third lens group (G3); in the second lens group (G2), at least two air lenses satisfy the relation: l (r21-r22)/(r21+ r22) | <0.6, | (Vd21-Vd22) | > 28, | (nd21-nd22) | > 0.09; wherein r21 and r22 are respectively the curvature radius of the lens surface at two sides of the air lens, Vd21 and Vd22 are respectively the dispersion coefficient of the lens at two sides of the air lens, and nd21 and nd22 are respectively the d-line refractive index of the lens at two sides of the air lens; and the second lens group (G2) at least comprises two positive lenses satisfying the following conditions at room temperature: dn/dt < 0; wherein n is the refractive index, t is the temperature, and dn/dt is the temperature coefficient of the refractive index of the optical material changing with the temperature;

the image side (P2) has a concave spherical surface facing the object side (P1), and satisfies: α in < NA/β, 0.8< Lpout/Rim < 1.2; where α in is an incident angle of a chief ray of the projection objective on the image side (P2), NA is an object-side numerical aperture of the projection objective, β is a magnification of the projection objective, taking a positive value, Lpout is an image-side exit pupil distance of the projection objective, and a curvature radius of a Rim image surface concave spherical surface.

2. The wide-field high-resolution projection objective of claim 1, characterized in that: in the third lens group (G3), a pair of first concave surfaces facing each other is included, and at least one negative lens is included between the pair of first concave surfaces facing each other, and the negative lens includes a second concave surface facing the object side; the third lens group (G3) further satisfies the relation: at least one positive lens and one negative lens satisfy ndp > ndn, and at least one positive lens and one negative lens satisfy Vdp < Vdn; ndp is the d-line refractive index of the corresponding positive lens in the third lens group (G3), ndn is the d-line refractive index of the corresponding negative lens in the third lens group (G3), Vdp is the abbe number of the corresponding positive lens in the third lens group (G3), and Vdn is the abbe number of the corresponding negative lens in the third lens group (G3).

3. The wide-field high-resolution projection objective of claim 1, characterized in that: in the first lens group (G1): at least one positive lens and one negative lens satisfy: ndp > ndn; at least one positive lens and one negative lens satisfy: vdp is less than Vdn; ndp is the d-line refractive index of the corresponding positive lens in the first lens group (G1), ndn is the d-line refractive index of the corresponding negative lens in the first lens group (G1), Vdp is the abbe number of the corresponding positive lens in the first lens group (G1), and Vdn is the abbe number of the corresponding negative lens in the first lens group (G1).

4. The wide-field high-resolution projection objective of claim 1, characterized in that: 4< β < 18.

5. The wide-field high-resolution projection objective of any one of claims 1 to 4, characterized in that: all lens surfaces of the first lens group (G1), the second lens group (G2) and the third lens group (G3) are spherical surfaces and do not contain aspheric surfaces, and the second lens group (G2) and the third lens group (G3) are all single lenses without cemented surfaces.

6. The wide-field high-resolution projection objective of any one of claims 1 to 4, characterized in that: the total number of lenses of the wide-field high-resolution projection objective lies between 12 and 28.

7. The wide-field high-resolution projection objective of any one of claims 1 to 4, characterized in that: the second lens group (G2) comprises at least two lenses with negative focal power, wherein at least one lens is a biconcave lens; and at least three lenses with positive focal power, wherein at least two lenses are double convex lenses.

8. The wide-field high-resolution projection objective of any one of claims 1 to 4, characterized in that: the third lens group (G3) comprises at least two lenses with negative focal power; at least two lenses with positive optical power are also included and at least one crescent lens is included.

9. The wide-field high-resolution projection objective of any one of claims 1 to 4, characterized in that: the first lens group (G1) includes, in order from an object side (P1) to an image side (P2), a first lens (L1), a second lens (L2), a third lens (L3), and a fourth lens (L4), wherein the third lens (L3) has negative optical power, and the second lens (L2) and the fourth lens (L4) both have positive optical power.

10. The wide-field high-resolution projection objective of claim 1, characterized in that: the size of the opening of the diaphragm can be adjusted.