Schmidt lens with a column lens and a measuring device

Abstract

The application provides a Sham lens with a cylindrical lens and a measuring device. The Sham lens comprises a filter, a first lens with positive focal length, a first cemented lens group with negative focal length, a diaphragm, a second cemented lens group with positive focal length, a sixth lens with positive focal length, a seventh lens with positive focal length, and a protective glass, and the seventh lens is a cylindrical lens. The focal length f of the Sham lens and the focal length of each lens satisfy the following relationships: 55 < f7 / f < 65; 0.9 < f6 / f < 1.1; 1.1 < fu2 / f < 1.3; -0.8 < fu1 / f < -0.7; and 0.75 < f1 / f < 0.9. f7 is the focal length of the seventh lens, f6 is the focal length of the sixth lens, fu2 is the focal length of the second cemented lens group, fu1 is the focal length of the first cemented lens group, and f1 is the focal length of the first lens. The application compensates for the influence of the protective glass on the imaging quality by using the cylindrical lens, makes the design closer to the actual optical path, and improves the resolution of the Sham lens.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of machine vision lens, in particular to a Shema lens with a cylindrical lens and a measuring device. BACKGROUND

[0002] 3D line laser measurement technology transmits a linear laser beam to the surface of a measured object, and uses an industrial camera to collect a laser image modulated by the surface topography of the object. After a series of image processing, the height information of the surface of the measured object can be extracted. In the image acquisition process, the lens needs to shoot an inclined target. However, due to the limitation of the depth of field, it is difficult for a general lens to achieve clear imaging of a large range of inclined object surface. At this time, a Shema lens needs to be designed based on Shema's law.

[0003] In practical applications, the image plane is the plane where the pixels of the image sensor of the industrial camera are located. Before the photosensitive pixels of a Charge Coupled Device (CCD) or a Complementary Metal-Oxide-Semiconductor (CMOS), there is a flat protective glass. The thickness of the glass is generally about 0.8 mm. In the imaging light path of the Shema lens, the image plane is no longer perpendicular to the optical axis, and there is a certain angle between the protective glass and the optical axis. The inclined flat glass inevitably introduces astigmatism aberration in the imaging light path, affecting the imaging quality of the system.

[0004] Chinese patent CN 115718361 A provides an optical system, a camera and a vehicle. The optical system is used for a vehicle camera. The optical system includes a cylindrical lens, a lens group and a filter in sequence along the direction of light beam propagation. The surface shape of the cylindrical lens is a biconical Zernike surface shape. This patent considers the curvature radius and the inclination angle of the windshield. By introducing a cylindrical lens, the optical path difference caused by the windshield is effectively compensated. The best focal planes of the meridional plane and the sagittal plane in the field of view range are optimized within the acceptable plane range. Chinese patent CN 111580245 A designs a high-resolution Shema lens. Seven spherical lenses are used to meet the condition of TTG / IH≦13, and the imaging of an inclined target is realized. TTG is the distance from the front surface of the first spherical lens to the image plane, and IH is the diagonal half image height of the rectangular detector. The high-resolution Shema lens has the advantages of high resolution and small structure.

[0005] However, the Shema lens designed in the prior art does not consider the influence of the protective glass in front of the sensor on the imaging light beam in the inclined light path, which will result in the imaging quality of the actual lens being much lower than the designed value, thereby affecting the precision level of the entire measurement system. SUMMARY

[0006] The present application provides a Sharm lens with a cylindrical lens and a measuring device, which can at least solve one of the above technical problems.

[0007] To achieve the above object, the present application provides the following technical scheme:

[0008] A Sharm lens with a cylindrical lens, from the object plane to the image plane along the optical axis direction, is composed of a first lens with positive focal power, a first cemented lens group with negative focal power, a second cemented lens group with positive focal power, a sixth lens with positive focal power, a seventh lens with positive focal power, and the seventh lens is a cylindrical lens, and a protective glass.

[0009] Wherein, the Sharm lens focal length f and the seventh lens focal length f7 satisfy: 55<f7 / f<65;

[0010] The Sharm lens focal length f and the sixth lens focal length f6 satisfy: 0.9<f6 / f<1.1;

[0011] The second cemented lens group focal length fu2 and the Sharm lens focal length f satisfy: 1.1<fu2 / f<1.3;

[0012] The first cemented lens group focal length fu1 and the Sharm lens focal length f satisfy: -0.8<fu1 / f<-0.7;

[0013] The Sharm lens focal length f and the first lens focal length f1 satisfy: 0.75<f1 / f<0.9.

[0014] Further, the first cemented lens group is composed of a second lens and a third lens by cementing process; wherein the second lens has positive focal power; the third lens has negative focal power.

[0015] Further, the second cemented lens group is composed of a fourth lens and a fifth lens by cementing process; wherein the fourth lens has negative focal power; the fifth lens has positive focal power.

[0016] Further, it further includes: the total optical length TTL of the Sharm lens with a cylindrical lens and the focal length f satisfy: 1.4<TTL / f<1.8.

[0017] Further, it further includes: the distance t67 from the center of the rear surface of the sixth lens to the center of the front surface of the seventh lens and the distance t78 from the center of the rear surface of the seventh lens to the center of the front surface of the protective glass satisfy: 0.8<t67 / t78<1.2.

[0018] Further, it further includes: the total optical length TTL of the Sharm lens with a cylindrical lens and the distance t68 from the center of the rear surface of the sixth lens to the center of the front surface of the protective glass satisfy: 3<TTL / t68<3.3.

[0019] Further, the seventh lens is a plano-convex structure; the sixth lens is a biconvex structure; the fifth lens is a biconvex structure; the fourth lens is a biconcave structure; the third lens is a meniscus structure; the second lens is a meniscus structure; and the first lens is a meniscus structure.

[0020] Further, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are all spherical mirrors.

[0021] Further, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are all spherical mirrors.

[0022] In another aspect, the application further provides a measuring device for 3D line laser measurement, comprising the above-mentioned Schlieren lens with a cylindrical lens.

[0023] The application has the following advantages:

[0024] In the design stage, the application adds a front protective glass to the imaging model structure, introduces a cylindrical lens to compensate for the aberration caused by the tilted protective glass, and improves the resolution of the Schlieren lens.

[0025] The application sets optical elements such as a filter, a first lens, a first cemented lens group, a diaphragm, a second cemented lens group, a sixth lens, a seventh lens and a protective glass in sequence from an object plane to an image plane, and reasonably configures the lens shape and optical power combination between the lenses, so that the finally formed Schlieren lens can meet the actual application requirements. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a structure schematic diagram of the Schlieren lens in embodiment 1 of the application;

[0027] Figure 2 is an MTF curve diagram of the Schlieren lens in embodiment 1 of the application;

[0028] Figure 3 is a structure schematic diagram of the Schlieren lens in embodiment 2 of the application;

[0029] Figure 4 is an MTF curve diagram of the Schlieren lens in embodiment 2 of the application;

[0030] Figure 5 is a structure schematic diagram of the Schlieren lens in embodiment 3 of the application;

[0031] Figure 6 is an MTF curve diagram of the Schlieren lens in embodiment 3 of the application. DETAILED DESCRIPTION

[0032] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application.

[0033] As shown in Figure 1 The present application provides a Schmidt lens with a cylindrical lens, which is composed of a filter G0, a first lens G1, a first cemented lens group u1, an aperture S1, a second cemented lens group u2, a sixth lens G6, a seventh lens G7 and a protective glass G8 in sequence along the optical axis from the object plane to the image plane. The first cemented lens group u1 is composed of a second lens G2 and a third lens G3 by a cementing process; the second cemented lens group u2 is composed of a fourth lens G4 and a fifth lens G5 by a cementing process.

[0034] The first lens G1 is a meniscus spherical lens with positive focal power;

[0035] The second lens G2 is a meniscus spherical lens with positive focal power;

[0036] The third lens G3 is a meniscus spherical lens with negative focal power;

[0037] The second lens G2 and the third lens G3 are composed of the first cemented lens group u1 by a cementing process, and the first cemented lens group u1 has negative focal power;

[0038] The fourth lens G4 is a biconcave spherical lens with negative focal power;

[0039] The fifth lens G5 is a biconvex spherical lens with positive focal power;

[0040] The fourth lens G4 and the fifth lens G5 are composed of the second cemented lens group u2 by a cementing process, and the second cemented lens group u2 has positive focal power;

[0041] The sixth lens G6 is a biconvex spherical lens with positive focal power;

[0042] The seventh lens G7 is a plano-convex cylindrical lens with positive focal power.

[0043] The Schmidt lens focal length f and the seventh lens focal length f7 satisfy: 55<f7 / f<65;

[0044] The Schmidt lens focal length f and the sixth lens focal length f6 satisfy: 0.9<f6 / f<1.1;

[0045] The second cemented lens group focal length fu2 and the Schmidt lens focal length f satisfy: 1.1<fu2 / f<1.3;

[0046] The focal length fu1 of the first cemented lens group and the focal length f of the Schahm lens satisfy: -0.8 <fu1 / f<-0.7;

[0047] The focal length f of the Schahm lens and the focal length f1 of the first lens satisfy: 0.75 <f1 / f<0.9。

[0048] Among them, the total track length (TTL) of the Sham lens with cylindrical lenses satisfies the following relationship with the focal length f: 1.4 <TTL / f<1.8。

[0049] The distances t67 from the center of the rear surface of the sixth lens to the center of the front surface of the seventh lens and t78 from the center of the rear surface of the seventh lens to the center of the front surface of the protective glass satisfy: 0.8 <t67 / t78<1.2。

[0050] Among them, the total optical length TTL of the Sham lens with cylindrical lens and the distance t68 from the center of the rear surface of the sixth lens to the center of the front surface of the protective glass satisfy: 3 <TTL / t68<3.3。

[0051] Wherein, the angle α between the object plane and the optical axis, and the angle β between the image plane and the optical axis, satisfy: tan(α) / tan(β)=|m|; where m is the center magnification of the Sham lens. Example 1

[0052] like Figure 1 As shown in the diagram, this embodiment presents a schematic diagram of a SAM lens with a cylindrical lens. Along the optical axis from the object plane to the image plane, the SAM lens consists of a filter G0, a first lens G1, a first cemented lens group u1, an aperture stop S1, a second cemented lens group u2, a sixth lens G6, a seventh lens G7, and a protective glass G8. The first cemented lens group u1 is formed by cementing the second lens G2 and the third lens G3 together; the second cemented lens group u2 is formed by cementing the fourth lens G4 and the fifth lens G5 together.

[0053] Among them, the first lens G1 is a meniscus spherical lens with positive optical power;

[0054] The second lens G2 is a meniscus spherical lens with positive optical power;

[0055] The third lens G3 is a meniscus spherical lens with negative optical power;

[0056] The second lens G2 and the third lens G3 are bonded together to form a first cemented lens group u1, which has negative optical power.

[0057] The fourth lens, G4, is a biconcave spherical lens with negative optical power.

[0058] The fifth lens G5 is a double-convex spherical lens with positive refractive power;

[0059] The fourth lens G4 and the fifth lens G5 form a second cemented lens group u2 by a cementing process; the second cemented lens group u2 has positive refractive power;

[0060] The sixth lens G6 is a double-convex spherical lens with positive refractive power;

[0061] The seventh lens G7 is a plano-convex cylindrical lens with positive refractive power.

[0062] The relevant parameters of each lens of the Schmidt lens in Embodiment 1 are shown in Table 1. According to the result parameters in Table 1, a Schmidt lens with a working wavelength of 405 nm and a focal length of 47.5 mm can be realized, which has an image-side F number of 4, a working distance of 100 mm, and an image plane linear field of view of 19 mm x 9.8 mm.

[0063] In this embodiment, the angle α between the object plane and the optical axis is 33°, the angle β between the image plane and the optical axis is 59.6°, and the central magnification m is -0.381; wherein tan(α) / tan(β)=tan(33°) / tan(59.6°)=0.381 is equal to |m|=0.381, that is, the angle relationship between the object plane, the image plane and the optical axis is satisfied, and clear imaging of the entire inclined plane can be realized.

[0064] In this embodiment, the focal length of the Schmidt lens f is 47.5 mm, the focal length of the first lens f1 is 41.5 mm, the focal length of the first cemented lens group fu1 is -36 mm, the focal length of the second cemented lens group fu2 is 54.7 mm, the focal length of the sixth lens f6 is 45.8 mm, and the focal length of the seventh lens f7 is 2828 mm. The total optical length TTL is 78.4 mm, the distance t67 from the center of the rear surface of the sixth lens to the center of the front surface of the seventh lens is 10.935 mm, the distance t78 from the center of the rear surface of the seventh lens to the center of the front surface of the protective glass is 12.977 mm, and the distance t68 from the center of the rear surface of the sixth lens to the center of the front surface of the protective glass is 25.854 mm.

[0065] The respective relationships are:

[0066] f1 / f = 41.5 / 47.5 = 0.874

[0067] fu1 / f = -36 / 47.5 = -0.758

[0068] fu2 / f = 54.7 / 47.5 = 1.152

[0069] f6 / f = 45.8 / 47.5 = 0.964

[0070] f7 / f = 2828 / 47.5 = 59.537

[0071] TTL / f = 78.4 / 47.5 = 1.651

[0072] t67 / t78 = 10.935 / 12.977 = 0.843

[0073] TTL / t68 = 78.4 / 25.854 = 3.032

[0074] It can be seen that the above results satisfy the following relationships, respectively:

[0075] 0.75 < f1 / f < 0.9

[0076] -0.8 < fu1 / f < -0.7

[0077] 1.1 < fu2 / f < 1.3

[0078] 0.9 < f6 / f < 1.1

[0079] 55 < f7 / f < 65

[0080] 1.4 < TTL / f < 1.8

[0081] 0.8 < t67 / t78 < 1.2

[0082] 3 < TTL / t68 < 3.3

[0083] Figure 2 A modulation transfer function (MTF) curve of the embodiment 1 is shown, which represents the lens imaging modulation degree of different spatial frequencies under each field of view, the horizontal axis represents the spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. It can be seen from the figure that the MTF value of the embodiment is better than 150 lp / mm in the full field of view resolution, and has good imaging quality.

[0084] Table 1

[0085] Embodiment 2

[0086] As Figure 3 shown, the embodiment proposes a structure schematic diagram of a Schmidt lens with a column lens, which includes, along the optical axis from the object plane to the image plane, in sequence: a filter G0, a first lens G1, a second lens G2, a third lens G3, a diaphragm S1, a fourth lens G4, a fifth lens G5, a sixth lens G6, a seventh lens G7, and a protective glass G8.

[0087] The first lens G1 is a meniscus structure spherical lens, which has a positive focal power;

[0088] The second lens G2 is a meniscus spherical lens with positive refractive power;

[0089] The third lens G3 is a meniscus spherical lens with negative refractive power;

[0090] The second lens G2 and the third lens G3 form a first cemented lens group u1 by a cementing process, and the first cemented lens group u1 has negative refractive power;

[0091] The fourth lens G4 is a biconcave spherical lens with negative refractive power;

[0092] The fifth lens G5 is a biconvex spherical lens with positive refractive power;

[0093] The fourth lens G4 and the fifth lens G5 form a second cemented lens group u2 by a cementing process, and the second cemented lens group u2 has positive refractive power;

[0094] The sixth lens G6 is a biconvex spherical lens with positive refractive power;

[0095] The seventh lens G7 is a plano-convex cylindrical lens with positive refractive power.

[0096] The related parameters of each lens of the Schmidt lens in Embodiment 2 are shown in Table 2. According to the result parameters in Table 2, a Schmidt lens with a working wavelength of 405 nm and a focal length f of 48 mm can be realized, and the image side F number is 4, the working distance is 100 mm, and the size of the image plane line field of view is 19 mm x 9.8 mm.

[0097] As shown in Table 2, the angle α between the object plane and the optical axis is 32°, the angle β between the image plane and the optical axis is 58.4°, and the central magnification m is -0.384. tan(α) / tan(β)=tan(32°) / tan(58.4°)=0.384 is equal to |m|=0.384, that is, the angle relationship between the object plane, the image plane and the optical axis is satisfied, and clear imaging of the entire inclined plane can be realized.

[0098] In this embodiment, the focal length f of the Schmidt lens is 48 mm, the focal length f1 of the first lens is 42.1 mm, the focal length fu1 of the first cemented lens group is -37.7 mm, the focal length fu2 of the second cemented lens group is 59.7 mm, the focal length f6 of the sixth lens is 43.5 mm, and the focal length f7 of the seventh lens is 2923.8 mm. The total optical length TTL is 79.6 mm, the distance t67 from the center of the rear surface of the sixth lens to the center of the front surface of the seventh lens is 10.935 mm, the distance t78 from the center of the rear surface of the seventh lens to the center of the front surface of the protective glass is 12.936 mm, and the distance t68 from the center of the rear surface of the sixth lens to the center of the front surface of the protective glass is 25.87 mm.

[0099] The various relationships are:

[0100] f1 / f = 42.1 / 48 = 0.877

[0101] fu1 / f = -37.7 / 48 = -0.785

[0102] fu2 / f = 59.7 / 48 = 1.244

[0103] f6 / f = 43.5 / 48 = 0.906

[0104] f7 / f = 2923.8 / 48 = 60.913

[0105] TTL / f = 79.6 / 48 = 1.658

[0106] t67 / t78 = 10.935 / 12.936 = 0.845

[0107] TTL / t68 = 79.6 / 25.87 = 3.077

[0108] It can be seen that the above results satisfy the following relationships, respectively:

[0109] 0.75 < f1 / f < 0.9

[0110] -0.8 < fu1 / f < -0.7

[0111] 1.1 < fu2 / f < 1.3

[0112] 0.9 < f6 / f < 1.1

[0113] 55 < f7 / f < 65

[0114] 1.4 < TTL / f < 1.8

[0115] 0.8 < t67 / t78 < 1.2

[0116] 3 < TTL / t68 < 3.3

[0117] Figure 4 A modulation transfer function (MTF) curve of Example 2 is shown, which represents the lens imaging modulation degree of different spatial frequencies under each field of view, the horizontal axis represents the spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. It can be seen from the figure that the MTF value of the present embodiment is better than 150 lp / mm in the full field of view resolution, and has good imaging quality.

[0118] Table 2

[0119] Example 3

[0120] AsFigure 5 As shown, the embodiment proposes a structural schematic diagram of a Sharm lens with a columnar lens, which sequentially comprises a filter G0, a first lens G1, a second lens G2, a third lens G3, a diaphragm S1, a fourth lens G4, a fifth lens G5, a sixth lens G6, a seventh lens G7 and a protective glass G8 along an optical axis from an object plane to an image plane.

[0121] The first lens G1 is a meniscus spherical lens with positive refractive power;

[0122] The second lens G2 is a meniscus spherical lens with positive refractive power;

[0123] The third lens G3 is a meniscus spherical lens with negative refractive power;

[0124] The second lens G2 and the third lens G3 form a first cemented lens group u1 by a cementing process, and the first cemented lens group u1 has negative refractive power;

[0125] The fourth lens G4 is a biconcave spherical lens with negative refractive power;

[0126] The fifth lens G5 is a biconvex spherical lens with positive refractive power;

[0127] The fourth lens G4 and the fifth lens G5 form a second cemented lens group u2 by a cementing process, and the second cemented lens group u2 has positive refractive power;

[0128] The sixth lens G6 is a biconvex spherical lens with positive refractive power;

[0129] The seventh lens G7 is a plano-convex cylindrical lens with positive refractive power.

[0130] The related parameters of each lens of the Sharm lens in the embodiment 3 are shown in Table 3. According to the result parameters in Table 3, a Sharm lens with a working wavelength of 405 nm and a focal length f of 48 mm can be realized, which has an image side F number of 4, a working distance of 100 mm, and an image plane line field size of 19 mm x 9.8 mm.

[0131] As shown in Table 3, the angle α between the object plane and the optical axis is 40°, the angle β between the image plane and the optical axis is 64.2°, and the central magnification m is -0.405. In which, tan(α) / tan(β) = tan(40°) / tan(64.2°) = 0.405 is equal to |m| = 0.405, that is, the angle relationship between the object plane, the image plane and the optical axis is satisfied, and clear imaging of the entire inclined plane can be realized.

[0132] In this embodiment, the focal length of the Sham lens is f = 48 mm, the focal length of the first lens is f1 = 38.2 mm, the focal length of the first cemented lens group is fu1 = -35.5 mm, the focal length of the second cemented lens group is fu2 = 53.1 mm, the focal length of the sixth lens is f6 = 48.5 mm, and the focal length of the seventh lens is f7 = 3017.7 mm. The total optical length TTL = 76.8 mm, the distance from the center of the rear surface of the sixth lens to the center of the front surface of the seventh lens t67 = 11.46 mm, the distance from the center of the rear surface of the seventh lens to the center of the front surface of the protective glass t78 = 10.98 mm, and the distance from the center of the rear surface of the sixth lens to the center of the front surface of the protective glass t68 = 24.24 mm.

[0133] Each of the relationships is:

[0134] f1 / f = 38.2 / 48 = 0.796

[0135] fu1 / f = -35.5 / 48 = -0.740

[0136] fu2 / f = 53.1 / 48 = 1.106

[0137] f6 / f = 48.5 / 48 = 1.010

[0138] f7 / f = 3017.7 / 48 = 62.869

[0139] TTL / f = 76.8 / 48 = 1.6

[0140] t67 / t78 = 11.46 / 10.98 = 1.044

[0141] TTL / t68 = 76.8 / 24.24 = 3.168

[0142] It can be seen that the above results respectively satisfy the following relationships:

[0143] 0.75 < f1 / f < 0.9

[0144] -0.8 < fu1 / f < -0.7

[0145] 1.1 < fu2 / f < 1.3

[0146] 0.9 < f6 / f < 1.1

[0147] 55 < f7 / f < 65

[0148] 1.4 < TTL / f < 1.8

[0149] 0.8 < t67 / t78 < 1.2

[0150] 3 < TTL / t68 < 3.3

[0151] Figure 6 A modulation transfer function (MTF) curve of the embodiment 3 is shown, which represents the lens imaging modulation degree of different spatial frequencies under each field of view, the horizontal axis represents the spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. It can be seen from the figure that the MTF value of the embodiment is better than 150 lp / mm in the full field of view resolution, and has good imaging quality.

[0152] Table 3

[0153]

[0154] In summary, the Sharm lens with a cylindrical lens provided by the present application adds the front protective glass of the image plane to the imaging model structure, introduces the cylindrical lens to compensate for the aberration introduced by the inclined protective glass, and improves the resolution of the Sharm lens. And by reasonably matching the lens shape and optical power combination between each lens, the finally formed Sharm lens can meet the demand of practical application.

[0155] On the other hand, the present application also provides a measuring device applied to 3D line laser measurement, which comprises the above-mentioned Sharm lens with a cylindrical lens.

[0156] The technical features of the above embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0157] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A Schmidt lens with a lenticular, characterized in that From the object plane to the image plane along the optical axis direction, the first lens with positive refractive power, the first cemented lens group with negative refractive power, the second cemented lens group with positive refractive power, the sixth lens with positive refractive power, the seventh lens with positive refractive power, and the seventh lens is a cylindrical lens, and a protective glass are composed; Wherein, the Schmidt lens focal length f and the seventh lens focal length f7 satisfy: 55<f7 / f<65; The Schmidt lens focal length f and the sixth lens focal length f6 satisfy: 0.9<f6 / f<1.1; The second cemented lens group focal length fu2 and the Schmidt lens focal length f satisfy: 1.1<fu2 / f<1.3; The first cemented lens group focal length fu1 and the Schmidt lens focal length f satisfy: -0.8<fu1 / f<-0.7; The Schmidt lens focal length f and the first lens focal length f1 satisfy: 0.75<f1 / f<0.

9.

2. The Schlieren lens with a lenslet array according to claim 1, characterized in that, The first cemented lens group is composed of the second lens and the third lens by cementing process; wherein, the second lens has positive refractive power; the third lens has negative refractive power.

3. The Schlieren lens with a lenslet array according to claim 2, characterized in that, The second cemented lens group is composed of the fourth lens and the fifth lens by cementing process; wherein, the fourth lens has negative refractive power; the fifth lens has positive refractive power.

4. The Schlieren lens with a lenslet array according to claim 1, characterized in that, Further comprising: The total optical length TTL of the Schmidt lens with cylindrical lens and the focal length f satisfy: 1.4<TTL / f<1.

8.

5. The Schlieren lens with a lenslet array according to claim 1, characterized in that, Further comprising: The distance t67 from the center of the rear surface of the sixth lens to the center of the front surface of the seventh lens and the distance t78 from the center of the rear surface of the seventh lens to the center of the front surface of the protective glass satisfy: 0.8<t67 / t78<1.

2.

6. The Shammas lens with a post lens according to claim 1, wherein, Further comprising: The total optical length TTL of the Schmidt lens with cylindrical lens and the distance t68 from the center of the rear surface of the sixth lens to the center of the front surface of the protective glass satisfy: 3<TTL / t68<3.

3.

7. The Schwarzschild lens with a lenslet according to claim 3, characterized in that, The seventh lens is a flat convex structure; the sixth lens is a double convex structure; the fifth lens is a double convex structure; the fourth lens is a double concave structure; the third lens is a meniscus structure; the second lens is a meniscus structure; and the first lens is a meniscus structure.

8. The Schlieren lens with a lenslet array according to claim 7, characterized in that, The first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are all spherical mirrors.

9. The Shammas lens with a post lens according to claim 1, wherein, Further comprising: A filter is arranged in front of the first lens; and a diaphragm is arranged between the first cemented lens group and the second cemented lens group.

10. A measuring device for 3D line laser measurement, characterized in that The Schmidt lens with cylindrical lens comprises the Schmidt lens with cylindrical lens according to any one of claims 1 to 9.

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