A near-infrared optical imaging lens

Abstract

The application discloses a near-infrared optical imaging lens, characterized in that the near-infrared optical imaging lens comprises, in sequence from an object side to an image side, a first lens, the first lens being a meniscus lens with positive refractive power; a second lens, the second lens being a meniscus lens with positive refractive power; a third lens, the third lens being a double-concave lens with negative refractive power; a diaphragm; a fourth lens, the fourth lens being a double-convex lens with positive refractive power; a fifth lens, the fifth lens being a double-convex lens with positive refractive power; a sixth lens, the sixth lens being a double-convex lens with positive refractive power; and a seventh lens, the seventh lens being a double-concave lens with negative refractive power; the working waveband of the near-infrared optical imaging lens is 900nm-1700nm, and the focal length of the near-infrared optical imaging lens is 45mm. Through the design of the lenses, the transverse aberrations are offset from each other, a large working distance is obtained, and the imaging quality is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical design, in particular to a near-infrared optical imaging lens. BACKGROUND

[0002] When observing the activities of living biological tissues, biological tissues have better penetration effect in the working waveband of 900nm-1700nm than visible light, so that the technology of combining fluorescent dyes, nano biological probes and genetic modification can be used to observe the activities of living small animals, such as body fluid circulation, drug transportation and tumor tissue diffusion.

[0003] When the light beam passes through the optical system, different wavelengths of light will produce dispersion phenomenon, because the refractive index of the optical imaging lens is different for different wavelengths, which leads to different sizes of images at different wavelengths, seriously affecting the imaging quality. SUMMARY

[0004] The purpose of the present application is to provide a near-infrared optical imaging lens which can solve at least one of the above technical problems. The specific scheme is as follows:

[0005] According to the specific embodiment of the present application, a near-infrared optical imaging lens is disclosed, comprising, arranged in order from the object side to the image side:

[0006] The first lens is a meniscus lens with positive focal power;

[0007] The second lens is a meniscus lens with positive focal power;

[0008] The third lens is a double-concave lens with negative focal power; the stop;

[0009] The fourth lens is a double-convex lens with positive focal power;

[0010] The fifth lens is a double-convex lens with positive focal power;

[0011] The sixth lens is a double-convex lens with positive focal power;

[0012] The seventh lens is a double-concave lens with negative focal power;

[0013] The working waveband of the near-infrared optical imaging lens is 900nm-1700nm.

[0014] Preferably, the air gap between the stop and the third lens is 3.3mm; the air gap between the stop and the fourth lens is 1.0mm.

[0015] Preferably, the material of the second lens, the fourth lens and the sixth lens is fluorite crown glass with low dispersion; the material of the third lens and the fifth lens is heavy flint glass.

[0016] Preferably, the brand of the fluorite crown glass is H-FK61B; the brand of the heavy flint glass is H-ZF13.

[0017] Preferably, the first lens is fluorite crown glass with the brand of H-FK61B; the focal length of the first lens and the focal length of the near-infrared optical imaging lens satisfy: 3.1 < f1 / f < 4.

[0018] Preferably, the focal length of the second lens and the focal length of the near-infrared optical imaging lens satisfy: 0.4 < f2 / f < 1.1;

[0019] the focal length of the third lens and the focal length of the near-infrared optical imaging lens satisfy: -1.8 < f3 / f < -0.8;

[0020] the focal length of the fourth lens and the focal length of the near-infrared optical imaging lens satisfy: 0.4 < f4 / f < 1;

[0021] the focal length of the fifth lens and the focal length of the near-infrared optical imaging lens satisfy: 0.6 < f5 / f < 1.5;

[0022] the focal length of the sixth lens and the focal length of the near-infrared optical imaging lens satisfy: 0.6 < f6 / f < 1.4;

[0023] the focal length of the seventh lens and the focal length of the near-infrared optical imaging lens satisfy: -0.7 < f7 / f < -0.2.

[0024] Preferably, the air interval of the second lens and the first lens is: 2.4mm;

[0025] the air interval of the third lens and the second lens is: 3.6mm;

[0026] the air interval of the fifth lens and the fourth lens is: 1.7mm;

[0027] the air interval of the sixth lens and the fifth lens is: 1.0mm.

[0028] Preferably, the material of the seventh lens is fused quartz, the thickness of the seventh lens is 4.5mm, and the interval with the sixth lens is 3.2mm.

[0029] Preferably, along the outgoing direction of the seventh lens, a flat glass is further included.

[0030] The air interval of the flat glass and the seventh lens is 12.8mm;

[0031] The material of the flat glass is fused quartz, and the thickness is 0.85mm.

[0032] Preferably, the focal length of the near-infrared optical imaging lens is 45mm, the optical distortion is less than 0.1%, and the MTF is greater than 0.6@34lp / mm.

[0033] Compared with the prior art, the above scheme of the embodiment of the present application has at least the following beneficial effects:

[0034] The present application designs each lens to make the transverse aberration offset each other while obtaining a larger working distance. The imaging quality of the near-infrared optical imaging lens in the 900nm-1700nm wide band range is further improved, the optical distortion is less than 0.1%, and the MTF is greater than 0.6@34lp / mm. BRIEF DESCRIPTION OF DRAWINGS

[0035] The drawings incorporated into the specification and forming part of the specification, show embodiments consistent with the present application, and together with the specification, serve to explain the principles of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained from these drawings without creative labor for those skilled in the art. In the drawings:

[0036] Figure 1 A structure schematic diagram of a near-infrared optical imaging lens provided by the embodiment of the present application;

[0037] Figure 2 The MTF curve of the 900nm-1200nmn band provided by the embodiment of the present application;

[0038] Figure 3 The optical point array diagram provided by the embodiment of the present application;

[0039] Figure 4 The optical field curvature-distortion curve diagram provided by the embodiment of the present application.

[0040] Reference signs:

[0041] L1, first lens; S1, object side surface of the first lens; S2, image side surface of the first lens;

[0042] L2, second lens; S3, object side surface of the second lens; S4, image side surface of the second lens;

[0043] L3, third lens; S5, object side surface of the third lens; S6, image side surface of the third lens; S7, diaphragm;

[0044] L4, fourth lens; S8, object side surface of the fourth lens; S9, image side surface of the fourth lens;

[0045] L5, fifth lens; S10, object side surface of the fifth lens; S11, image side surface of the fifth lens;

[0046] L6, sixth lens; S12, object side surface of the sixth lens; S13, image side surface of the sixth lens;

[0047] L7, seventh lens; S14, object side surface of the seventh lens; S15, image side surface of the seventh lens;

[0048] L8, protective glass; S16, entrance surface of the protective glass; S17, exit surface of the protective glass;

[0049] S18, detection surface. DETAILED DESCRIPTION

[0050] In order to make the purposes, technical solutions and advantages of the present disclosure clearer, further specific description will be made to the present disclosure of a near-infrared optical imaging lens with reference to the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present disclosure, but not all the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present disclosure.

[0051] It should be noted that all the technical and scientific terms used in the present application have the same meaning as generally understood by those skilled in the art to which the present application belongs, unless otherwise specified.

[0052] It should also be noted that the terms "comprise", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the products or devices comprising a series of elements not only include those elements, but also include other elements not explicitly listed or inherent to such products or devices. Without more limitations, the element defined by the statement "comprises one" does not exclude the presence of another identical element in the product or device comprising the element.

[0053] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shape of the spherical or aspherical surface shown in the drawings is shown by way of example. That is, the shape of the spherical or aspherical surface is not limited to the shape of the spherical or aspherical surface shown in the drawings. The drawings are merely examples and are not strictly drawn to scale.

[0054] The embodiments of the present disclosure will be described below with reference to the accompanying drawings. Figures 1-4 Alternative embodiments of the present disclosure will be described in detail.

[0055] In the embodiment, the surface of each lens close to the surface of the detection plane is the image side surface of the lens, and the surface of each lens close to the object side is the object side surface of the lens. If the object side surface of the lens is away from the detection plane, the object side surface of the lens is a convex surface; otherwise, the object side surface is a concave surface. If the image side surface of the lens is away from the detection plane, the image side surface of the lens is a concave surface; otherwise, the image side surface is a convex surface.

[0056] As shown in the specific embodiment of the present application, the present application provides a near-infrared optical imaging lens, which comprises, in order from the object side to the image side, a first lens L1, a second lens L2, a third lens L3, a diaphragm S7, a fourth lens L4, a fifth lens L5, a sixth lens L6 and a seventh lens L7. Figure 1

[0057] Among them, the first lens L1 is a meniscus lens with positive refractive power; the second lens L2 is a meniscus lens with positive refractive power; the third lens L3 is a double-concave lens with negative refractive power; the fourth lens L4 is a double-convex lens with positive refractive power; the fifth lens L5 is a double-convex lens with positive refractive power; the sixth lens L6 is a double-convex lens with positive refractive power; and the seventh lens L7 is a double-concave lens with negative refractive power.

[0058] The working wavelength range of the near-infrared optical imaging lens is 900nm-1700nm, and the focal length of the near-infrared optical imaging lens is 45mm.

[0059] In the embodiment, the first lens L1, the second lens L2 and the third lens L3 constitute a front lens group with negative refractive power, and the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 constitute a rear lens group with positive refractive power. The reverse telephoto structure formed by the front lens group and the rear lens group makes the near-infrared optical imaging lens have a large back working distance.

[0060] The diaphragm S7 is arranged between the front lens group and the rear lens group, which is used to offset the lateral aberration generated by the relative movement of the front lens group and the rear lens group.

[0061] In the embodiment, the air gap between the diaphragm S7 and the third lens L3 is set to 3.3mm, and the air gap between the diaphragm S7 and the fourth lens L4 is set to 1.0mm.

[0062] In the embodiment, the air gap between the second lens L2 and the first lens L1 is 2.4mm; the air gap between the third lens L3 and the second lens L2 is 3.6mm; the air gap between the fifth lens L5 and the fourth lens L4 is 1.7mm; the air gap between the sixth lens L6 and the fifth lens L5 is 1.0mm; and the air gap between the seventh lens L7 and the sixth lens L6 is 3.2mm.

[0063] ​Further, the central thickness of the first lens is 5.0 mm, the radius of curvature of the object side S1 of the first lens is 34.854 mm, and the radius of curvature of the image side S2 of the first lens is 60.105 mm;

[0064] The central thickness of the second lens is 4.9 mm, the radius of curvature of the object side S3 of the second lens is 17.908 mm, and the radius of curvature of the image side S4 of the second lens is 238.233 mm;

[0065] The central thickness of the third lens is 3.6 mm, the radius of curvature of the object side S5 of the third lens is -49.733 mm, and the radius of curvature of the image side S6 of the third lens is 17.820 mm;

[0066] The central thickness of the fourth lens is 3.8 mm, the radius of curvature of the object side S8 of the fourth lens is 15.510 mm, and the radius of curvature of the image side S9 of the fourth lens is 321.747 mm;

[0067] The central thickness of the fifth lens is 3.5 mm, the radius of curvature of the object side S10 of the fourth lens is 113.166 mm, and the radius of curvature of the image side S11 of the fourth lens is -47.356 mm;

[0068] The central thickness of the sixth lens is 3.5 mm, the radius of curvature of the object side S12 of the sixth lens is 37.502 mm, and the radius of curvature of the image side S13 of the sixth lens is -52.716 mm;

[0069] The central thickness of the seventh lens is 4.5 mm, the radius of curvature of the object side S14 of the fourth lens is -11.945 mm, and the radius of curvature of the image side S15 of the fourth lens is 62.137 mm.

[0070] In the embodiment, the focal length of each lens and the focal length of the near-infrared optical imaging lens satisfy the following relationship:

[0071] The focal length of the first lens L1 and the focal length f of the near-infrared optical imaging lens satisfy: 3.1 < f1 / f < 4;

[0072] The focal length of the second lens L2 and the focal length f of the near-infrared optical imaging lens satisfy: 0.4 < f2 / f < 1.1;

[0073] The focal length of the third lens L3 and the focal length f of the near-infrared optical imaging lens satisfy: -1.8 < f3 / f < -0.8;

[0074] The focal length of the fourth lens L4 and the focal length f of the near-infrared optical imaging lens satisfy: 0.4 < f4 / f < 1;

[0075] The focal length of the fifth lens L5 and the focal length f of the near-infrared optical imaging lens satisfy: 0.6 < f5 / f < 1.5.

[0076] The focal length of the sixth lens L6 and the focal length f of the near-infrared optical imaging lens satisfy: 0.6 < f6 / f < 1.4.

[0077] The focal length of the seventh lens L7 and the focal length f of the near-infrared optical imaging lens satisfy: -0.7 < f7 / f < -0.2.

[0078] Further, in order to reduce the chromatic aberration of the near-infrared optical imaging lens, the materials of the lenses are designed.

[0079] In the embodiment, the materials of the first lens, the second lens, the fourth lens and the sixth lens are fluorite glass with low dispersion, and preferably, the glass brand is H-FK61B.

[0080] The materials of the third lens and the fifth lens are heavy flint glass with high refractive index and high dispersion, and preferably, the glass brand is H-ZF13.

[0081] The material of the seventh lens is fused silica.

[0082] In the embodiment, the chromatic aberration of the near-infrared optical imaging lens is further corrected by using two material combinations with large Abbe number difference.

[0083] In the embodiment, the eighth lens L8 is arranged in the light-out direction of the seventh lens L7. The eighth lens L8 is a flat glass, the air gap of the eighth lens L8 and the seventh lens L7 is 12.8mm, the material of the flat glass is fused silica, and the thickness of the flat glass is 0.85mm.

[0084] Table 1 lists the parameters of the lenses in a preferred embodiment of the present application.

[0085] Table 1 Lens parameters

[0086]

[0087] Figures 2-4 The test results of the near-infrared optical imaging lens of the present application in the working wavelength range of 900nm-1700nm.

[0088] The evaluation standard of the image quality of the optical design is the modulation transfer function (MTF) at the Nyquist frequency (34mm / lp). As shown in Figure 2 The image quality in the working distance is uniformly close to the diffraction limit, and the MTF under the typical imaging distance is greater than 0.6.

[0089] AsFigure 3 As shown, the RMS blur radius of each field of view meets the requirements, with most of the energy within a single pixel. Therefore, this near-infrared optical lens exhibits good energy concentration.

[0090] like Figure 4 As shown, the field curvature and distortion of the lens are within the corresponding field of view, with optical distortion less than 0.1%.

[0091] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0092] The above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit it. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A near-infrared optical imaging lens characterized in that, Comprise in turn arranged on the light path from the object side to the image side: The first lens is a meniscus lens with positive refractive power; The second lens is a meniscus lens with positive refractive power; The third lens is a double-concave lens with negative refractive power; The diaphragm; The fourth lens is a lenticular lens with positive refractive power; The fifth lens is a lenticular lens with positive refractive power; The sixth lens is a lenticular lens with positive refractive power; The seventh lens is a double-concave lens with negative refractive power; The working waveband of the near-infrared optical imaging lens is 900nm-1700nm; The focal length of the second lens and the focal length of the near-infrared optical imaging lens satisfy: 0.4 The focal length of the third lens and the focal length of the near-infrared optical imaging lens satisfy: -1.8 The focal length of the fourth lens and the focal length of the near-infrared optical imaging lens satisfy: 0.4 The focal length of the fifth lens and the focal length of the near-infrared optical imaging lens satisfy: 0.6 The focal length of the sixth lens and the focal length of the near-infrared optical imaging lens satisfy: 0.6 The focal length of the seventh lens and the focal length of the near-infrared optical imaging lens satisfy: -0.7 2.The near infrared optical imaging lens according to claim 1, characterized in that, The air gap between the diaphragm and the third lens is 3.3mm; the air gap between the diaphragm and the fourth lens is 1.0mm. 3.The near infrared optical imaging lens according to claim 1, characterized in that, The materials of the second lens, the fourth lens and the sixth lens are fluorite glass with low dispersion; the materials of the third lens and the fifth lens are heavy flint glass.

4. The near infrared optical imaging lens according to claim 3, characterized in that, The brand of the fluorite glass is H-FK61B; the brand of the heavy flint glass is H-ZF13. 5.The near infrared optical imaging lens according to claim 1, characterized in that, The first lens is fluorite glass, the brand is H-FK61B; the focal length of the first lens and the focal length of the near-infrared optical imaging lens satisfy: 3.1 6. The near-infrared optical imaging lens according to claim 1, wherein, The air gap between the second lens and the first lens is: 2.4mm; The air gap between the third lens and the second lens is: 3.6mm; The air gap between the fifth lens and the fourth lens is: 1.7mm; The air gap between the sixth lens and the fifth lens is: 1.0mm.

7. The near infrared optical imaging lens according to claim 1, characterized in that, The material of the seventh lens is fused quartz, the center thickness of the seventh lens is 4.5mm, and the interval with the sixth lens is 3.2mm. 8.The near infrared optical imaging lens according to claim 1, characterized in that, In the outgoing direction of the seventh lens, further comprising: a flat glass; The air gap between the flat glass and the seventh lens is 12.8mm; The material of the flat glass is fused quartz, and the thickness is 0.85mm. 9.The near infrared optical imaging lens according to claim 1, characterized in that, The focal length of the near-infrared optical imaging lens is 45mm, the optical distortion is <0.1%, and the MTF is >0.6@34lp / mm.

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