TWI674435B - Three-piece infrared single wavelength lens system - Google Patents

Abstract

The invention is a three-piece infrared single-wavelength lens group, which includes, in order, from the object side to the image side: a first lens having a negative refractive power, the object side surface is convex near the optical axis, and the image side surface is near light The axis is concave, at least one of the object-side surface and the image-side surface is aspherical; an aperture; a second lens with positive refractive power, and its image-side surface is convex near the optical axis, and its object-side surface and image At least one surface of the side surface is aspherical; and a third lens having a refractive power, the object side surface of which is near the optical axis is convex, the image side surface of which is near the optical axis is concave, and the object side surface and the image side surface are at least One surface is aspherical. According to this, it has the effects of increasing the picture angle, large aperture, short lens length, and small distortion.

Description

Three-piece infrared single-wavelength lens group

The invention relates to a lens group, in particular to a miniaturized three-piece infrared single-wavelength lens group applied to electronic products.

Today's digital imaging technology is constantly innovating and changing. Especially in digital cameras such as digital cameras and mobile phones, miniaturization is developing, and photosensitive elements such as CCD or CMOS are also required to be miniaturized. In the application of infrared focusing lenses, in addition to the application In the field of photography, in recent years, it has also been widely used in the field of infrared receiving and sensing of game consoles. In order to make the range of users of the game console more broad, the current lens groups that receive infrared wavelengths are mostly larger in angle. The wide-angle lens group is mainstream.

Among them, the applicant also previously proposed a number of lens sets related to infrared wavelength reception. However, the current game consoles are mainly 3D games that are more three-dimensional, realistic and realistic. Therefore, the current or applicant's previous lens groups are based on The 2D plane game detection is an appeal, so that it cannot meet the depth sensing effect that 3D games focus on.

Moreover, the infrared receiving and sensing lens group dedicated to game consoles uses plastic lenses for the pursuit of low cost. One of the key factors that affects the lack of precision in depth detection of game consoles is the poor material transmission. The ambient temperature is too hot or too cold, so that the focal length of the lens group changes to prevent accurate focus detection. As mentioned above, the current infrared lens group cannot meet the two major technical issues of accurate sensing of depth distances in 3D games.

In view of this, how to provide an accurate depth distance detection and reception, and prevent the focal length change of the lens group from affecting the depth detection effect, has become a technical bottleneck that the infrared wavelength receiving lens group is currently desperate to overcome.

The purpose of the present invention is to provide a three-piece infrared single-wavelength lens group, in particular to a three-piece infrared single-wavelength lens group with improved picture angle, large aperture, short lens length, and small distortion.

In order to achieve the foregoing object, a three-piece infrared single-wavelength lens group according to the present invention includes, in order from the object side to the image side: a first lens having a negative refractive power, and an object side surface near the optical axis is A convex surface, the image side surface of which is near the optical axis is concave, at least one of its object side surface and the image side surface is aspherical; an aperture; a second lens, which has a positive refractive power, and its image side surface is near the optical axis. A convex surface, at least one of the object-side surface and the image-side surface of which is aspherical; and a third lens having a refractive power, the object-side surface of which is near the optical axis is convex, and the image-side surface of which is near the optical axis is concave, which At least one of the object-side surface and the image-side surface is an aspheric surface.

Preferably, the overall focal length of the three-piece infrared single-wavelength lens group is f, the combined focal length of the first lens and the second lens is f12, and the following conditions are satisfied: 0.5 <f / f12 <1.1. Therefore, the three-piece infrared single-wavelength lens group can achieve a balance between shortening the total optical length and correcting aberrations.

Preferably, the overall focal length of the three-piece infrared single-wavelength lens group is f, and the combined focal length of the second lens and the third lens is f23, and the following conditions are satisfied: 0.8 <f / f23 <1.6. Therefore, the three-piece infrared single-wavelength lens group can achieve a balance between shortening the total optical length and correcting aberrations.

Preferably, the focal length of the first lens is f1 and the focal length of the second lens is f2, and the following conditions are satisfied: -19 <f1 / f2 <-1.4. Thereby, the refractive power of the first lens and the second lens can be appropriately distributed, so that the aberration of the three-piece infrared single-wavelength lens group is not excessive.

Preferably, the focal length of the second lens is f2, and the focal length of the third lens is f3, and the following conditions are satisfied: -0.04 <f2 / f3 <0.26. This effectively shortens the overall optical length.

Preferably, the focal length of the first lens is f1, and the focal length of the third lens is f3, and the following conditions are satisfied: -1.5 <f1 / f3 <0.07. This will help reduce system sensitivity and aberrations.

Preferably, the focal length of the first lens is f1, and the combined focal length of the second lens and the third lens is f23, and the following conditions are satisfied: -23 <f1 / f23 <-1.9. As a result, the resolution of the three-piece infrared single-wavelength lens group is significantly improved.

Preferably, a composite focal length of the first lens and the second lens is f12, a focal length of the third lens is f3, and the following conditions are satisfied: -0.05 <f12 / f3 <0.37. As a result, the resolution of the three-piece infrared single-wavelength lens group is significantly improved.

Preferably, the curvature radius of the object-side surface of the first lens is R1, the curvature radius of the image-side surface of the first lens is R2, and the following conditions are satisfied: 0.9 <R1 / R2 <5.3. This provides a good viewing angle and reduces the high-order aberrations generated by the three-piece infrared single-wavelength lens group.

Preferably, the curvature radius of the object-side surface of the second lens is R3, and the curvature radius of the image-side surface of the second lens is R4, and the following conditions are satisfied: -27 <R3 / R4 <27. Thereby, the astigmatism of the three-piece infrared single-wavelength lens group can be reduced.

Preferably, the curvature radius of the object-side surface of the third lens is R5, and the curvature radius of the image-side surface of the third lens is R6, and the following conditions are satisfied: 0.7 <R5 / R6 <1.5. Thereby, the curvature configuration of the surface of the third lens is effectively balanced to achieve a balance between the field angle and the total length.

Preferably, the thickness of the first lens on the optical axis is CT1, and the thickness of the second lens on the optical axis is CT2, and the following conditions are satisfied: 0.5 <CT1 / CT2 <1.1. Thereby, the thicknesses of the first lens and the second lens are made appropriate, which contributes to the homogeneity and moldability of the lens during manufacture.

Preferably, the thickness of the second lens on the optical axis is CT2, and the thickness of the third lens on the optical axis is CT3, and the following conditions are satisfied: 0.9 <CT2 / CT3 <2.4. Thereby, the thicknesses of the second lens and the third lens are made appropriate, which contributes to the homogeneity and moldability of the lens during production.

Preferably, the thickness of the first lens on the optical axis is CT1, and the thickness of the third lens on the optical axis is CT3, and the following conditions are satisfied: 0.6 <CT1 / CT3 <1.8. Thereby, the thicknesses of the first lens and the third lens are made appropriate, which contributes to the homogeneity and moldability of the lens during manufacture.

Preferably, the overall focal length of the three-piece infrared single-wavelength lens group is f, and the distance from the object side surface to the imaging surface of the first lens on the optical axis is TL, and satisfies the following conditions: 0.3 <f / TL <0.6. This can help maintain the miniaturization and long focus of the three-piece infrared single-wavelength lens group for mounting on thin and light electronic products.

Regarding the technology, means, and other effects adopted by the present invention to achieve the foregoing objectives, seven preferred feasible embodiments are described in detail below with reference to the drawings.

<First Embodiment>

Please refer to FIG. 1A and FIG. 1B, wherein FIG. 1A shows a schematic diagram of a three-piece infrared single-wavelength lens group according to the first embodiment of the present invention, and FIG. 1B is the three-piece infrared of the first embodiment in order from left to right. Single-wavelength lens group image plane curve and distortion aberration curve. It can be seen from FIG. 1A that the three-piece infrared single-wavelength lens group includes an aperture 100 and an optical group. The optical group sequentially includes a first lens 110, a second lens 120, a third lens 130, The infrared cut-off filter 170 and the imaging surface 180 are three lenses (110, 120, 130) with refractive power in the three-piece infrared single-wavelength lens group. The aperture 100 is disposed between the first lens 110 and the second lens 120.

The first lens 110 has a negative refractive power and is made of plastic. The object-side surface 111 is convex near the optical axis 190, the image-side surface 112 is concave near the optical axis 190, and the object-side surface 111 and the image side The surfaces 112 are all aspheric.

The second lens 120 has a positive refractive power and is made of plastic. The object-side surface 121 thereof is concave near the optical axis 190, the image-side surface 122 thereof is convex near the optical axis 190, and the object-side surface 121 and the image side The surfaces 122 are all aspheric.

The third lens 130 has a positive refractive power and is made of plastic. Its object-side surface 131 is convex near the optical axis 190, its image-side surface 132 is concave near the optical axis 190, and the object-side surface 131 and the image side The surface 132 is an aspheric surface, and at least one surface of the object-side surface 131 and the image-side surface 132 has at least one inflection point.

The infrared filtering filter 170 is made of glass and is disposed between the third lens 130 and the imaging surface 180 without affecting the focal length of the three-piece infrared single-wavelength lens group.

The aspheric curve equations of the above lenses are expressed as follows:

Where z is the position value with the surface apex as the reference at the height h along the direction of the optical axis 190; c is the curvature of the lens surface near the optical axis 190, and is the inverse of the radius of curvature (R) (c = 1 / R) , R is the radius of curvature of the lens surface near the optical axis 190, h is the vertical distance of the lens surface from the optical axis 190, k is the conic constant, and A, B, C, D, E, F, G, ... … Is the higher-order aspheric coefficient.

In the three-piece infrared single-wavelength lens group of the first embodiment, the focal length of the three-piece infrared single-wavelength lens group is f, and the aperture value (f-number) of the three-piece infrared single-wavelength lens group is Fno. The maximum field of view (picture angle) in the infrared single-wavelength lens group is FOV, and the values are as follows: f = 1.46 (mm); Fno = 2.0; and FOV = 77.99 (degrees).

In the three-piece infrared single-wavelength lens group of the first embodiment, the overall focal length of the three-piece infrared single-wavelength lens group is f, the combined focal distance of the first lens 110 and the second lens 120 is f12, and the following conditions are satisfied: : F / f12 = 0.76.

In the three-piece infrared single-wavelength lens group of the first embodiment, the overall focal length of the three-piece infrared single-wavelength lens group is f, and the combined focal distance of the second lens 120 and the third lens 130 is f23, and satisfies the following conditions : F / f23 = 1.29.

In the three-piece infrared single-wavelength lens group of the first embodiment, the focal length of the first lens 110 is f1, and the focal length of the second lens 120 is f2, and the following conditions are satisfied: f1 / f2 = -2.18.

In the three-piece infrared single-wavelength lens group of the first embodiment, the focal length of the second lens 120 is f2, and the focal length of the third lens 130 is f3, and the following conditions are satisfied: f2 / f3 = 0.11.

In the three-piece infrared single-wavelength lens group of the first embodiment, the focal length of the first lens 110 is f1, and the focal length of the third lens 130 is f3, and the following conditions are satisfied: f1 / f3 = -0.23.

In the three-piece infrared single-wavelength lens group of the first embodiment, the focal length of the first lens 110 is f1, and the combined focal length of the second lens 120 and the third lens 130 is f23, and satisfies the following conditions: f1 / f23 = -2.73.

In the three-piece infrared single-wavelength lens group of the first embodiment, the combined focal length of the first lens 110 and the second lens 120 is f12, and the focal length of the third lens 130 is f3, and the following conditions are satisfied: f12 / f3 = 0.14.

In the three-piece infrared single-wavelength lens group of the first embodiment, the overall focal length of the three-piece infrared single-wavelength lens group is f, and the object-side surface 111 to the imaging surface 180 of the first lens 110 are on the optical axis 190. The distance is TL and the following conditions are satisfied: f / TL = 0.39.

In the three-piece infrared single-wavelength lens group of the first embodiment, the curvature radius of the object-side surface 111 of the first lens 110 is R1, and the curvature radius of the image-side surface 112 of the first lens 110 is R2, and the following conditions are satisfied: R1 / R2 = 2.53.

In the three-piece infrared single-wavelength lens group of the first embodiment, the curvature radius of the object-side surface 121 of the second lens 120 is R3, and the curvature radius of the image-side surface 122 of the second lens 120 is R4, and the following conditions are satisfied: R3 / R4 = 21.37.

In the three-piece infrared single-wavelength lens group of the first embodiment, the curvature radius of the object-side surface 131 of the third lens 130 is R5, and the curvature radius of the image-side surface 132 of the third lens 130 is R6, and the following conditions are satisfied: R5 / R6 = 0.99.

In the three-piece infrared single-wavelength lens group of the first embodiment, the thickness of the first lens 110 on the optical axis 190 is CT1, and the thickness of the second lens 120 on the optical axis 190 is CT2, and the following conditions are satisfied: CT1 / CT2 = 0.84.

In the three-piece infrared single-wavelength lens group of the first embodiment, the thickness of the second lens 120 on the optical axis 190 is CT2, and the thickness of the third lens 130 on the optical axis 190 is CT3, and the following conditions are satisfied: CT2 / CT3 = 1.40.

In the three-piece infrared single-wavelength lens group of the first embodiment, the thickness of the first lens 110 on the optical axis 190 is CT1, and the thickness of the third lens 130 on the optical axis 190 is CT3, and the following conditions are satisfied: CT1 / CT3 = 1.17.

Refer to Tables 1 and 2 below for further cooperation.

Table 1  First embodiment f ( Focal length) = 1.46 mm (mm), Fno (aperture value) = 2.0, FOV (picture angle) = 77.99 deg. (Degrees)  Surface  Curvature radius  Thickness  Material  Refractive index  Dispersion coefficient  Focal length  0  Subject  Infinite  400  1  Infinite  0  2  First lens  2.471  (ASP)  0.627  Plastic  1.64  22.46  -3.10  3  0.977  (ASP)  0.265  4  Aperture  Infinite  0.175  5  Second lens  -18.292  (ASP)  0.748  Plastic  1.64  22.46  1.42  6  -0.856  (ASP)  0.089  7  Third lens  1.347  (ASP)  0.535  Plastic  1.64  22.46  13.54  8  1.360  (ASP)  0.532  9  Infrared filter  Infinite  0.300  Glass  1.517  64.17  10  Infinite  0.487  11  Imaging surface  Infinite  -

Table 2  Aspheric coefficient  Plane  2  3  5  6  7  8  K:  -1.0327E + 01  3.0863E + 00  1.0000E + 02  -5.8755E + 00  -3.1425E + 00  5.0181E-01  A:  3.1022E-01  9.6810E-01  1.2756E-02  -1.3466E + 00  -6.3764E-02  1.9540E-01  B:  -3.1197E-02  -1.5244E + 00  1.1466E + 00  2.6519E + 00  -2.3095E-01  -9.8564E-01  C:  -7.6936E-01  1.5958E + 01  -1.3834E + 01  -5.7362E + 00  7.8978E-01  1.4447E + 00  D:  3.6174E + 00  7.9098E + 00  9.0565E + 01  7.7256E + 00  -8.0977E-01  -1.2454E + 00  E:  -7.0575E + 00  2.7563E + 02  -2.6962E + 02  1.7481E + 00  -2.0375E + 00  2.2039E-02  F  6.7217E + 00  -4.2786E + 03  4.0275E + 02  -2.6779E + 01  5.0798E + 00  8.3253E-01  G  -2.4889E + 00  2.1456E + 04  -2.5241E + 02  3.3857E + 01  -2.9953E + 00  -4.7259E-01

Table 1 is the detailed structural data of the first embodiment of FIG. 1A, where the units of the radius of curvature, thickness, and focal length are mm, and the surfaces 0-11 sequentially indicate the surface from the object side to the image side. Table 2 is the aspherical data in the first embodiment, where k represents the cone coefficient in the aspheric curve equation, and A, B, C, D, E, F, G, ... are high-order aspheric coefficients. In addition, the tables of the following embodiments are schematic diagrams and aberration curves corresponding to the embodiments. The definitions of the data in the tables are the same as the definitions of Tables 1 and 2 of the first embodiment, and will not be repeated here.

<Second Embodiment>

Please refer to FIG. 2A and FIG. 2B. FIG. 2A shows a schematic diagram of a three-piece infrared single-wavelength lens group according to a second embodiment of the present invention. FIG. Single-wavelength lens group image plane curve and distortion aberration curve. As can be seen from FIG. 2A, the three-piece infrared single-wavelength lens group includes an aperture 200 and an optical group, and the optical group sequentially includes a first lens 210, a second lens 220, a third lens 230, The infrared filtering filter 270 and the imaging surface 280, among which three lenses with refractive power in the three-piece infrared single-wavelength lens group are (210, 220, 230). The aperture 200 is disposed between the first lens 210 and the second lens 220.

The first lens 210 has a negative refractive power and is made of plastic. The object-side surface 211 is convex near the optical axis 290, the image-side surface 212 is concave near the optical axis 290, and the object-side surface 211 and the image side The surfaces 212 are all aspheric.

The second lens 220 has a positive refractive power and is made of plastic. The object-side surface 221 of the second lens 220 is concave near the optical axis 290, and its image-side surface 222 is convex near the optical axis 290. The surfaces 222 are all aspheric.

The third lens 230 has a positive refractive power and is made of plastic. The object-side surface 231 of the third lens 230 is convex near the optical axis 290. The image-side surface 232 of the third lens 230 is concave near the optical axis 290. The surfaces 232 are all aspheric, and at least one surface of the object-side surface 231 and the image-side surface 232 has at least one inflection point.

The infrared filter 270 is made of glass and is disposed between the third lens 230 and the imaging surface 280 without affecting the focal length of the three-piece infrared single-wavelength lens group.

Refer to Table 3 and Table 4 below for further cooperation.

table 3  Second embodiment f ( Focal length) = 1.49 mm (mm), Fno (aperture value) = 2.0, FOV (painting angle) = 77.91 deg. (Degrees)  Surface  Curvature radius  Thickness  Material  Refractive index  Dispersion coefficient  Focal length  0  Subject  Infinite  400  1  Infinite  0  2  First lens  3.812  (ASP)  0.594  Plastic  1.64  22.46  -2.79  3  1.116  (ASP)  0.280  4  Aperture  Infinite  0.121  5  Second lens  -14.118  (ASP)  0.751  Plastic  1.54  56  1.59  6  -0.815  (ASP)  0.030  7  Third lens  1.079  (ASP)  0.554  Plastic  1.54  56  7.89  8  1.191  (ASP)  0.571  9  Infrared filter  Infinite  0.300  Glass  1.517  64.17  10  Infinite  0.554  11  Imaging surface  Infinite  -

Table 4  Aspheric coefficient  Plane  2  3  5  6  7  8  K:  6.1294E-01  4.1054E + 00  -8.5037E + 01  -5.7819E + 00  -1.7078E + 00  3.0868E-01  A:  2.9587E-01  9.8160E-01  2.8199E-01  -1.4358E + 00  -5.0194E-02  3.3745E-01  B:  -8.5807E-02  3.8457E-01  1.1145E + 00  2.6237E + 00  -2.4864E-01  -1.2885E + 00  C:  -7.7507E-01  1.0655E + 01  -1.4238E + 01  -5.4432E + 00  5.7364E-01  1.4215E + 00  D:  3.7345E + 00  6.2729E + 00  9.0630E + 01  7.7065E + 00  -7.9521E-01  -1.1033E + 00  E:  -7.1555E + 00  4.3767E + 02  -2.7077E + 02  3.2756E-01  -1.8521E + 00  -3.2038E-02  F  6.5121E + 00  -4.6057E + 03  3.9975E + 02  -2.8291E + 01  4.9918E + 00  8.4759E-01  G  -2.3272E + 00  1.7582E + 04  -2.4111E + 02  4.3738E + 01  -3.1894E + 00  -5.1100E-01

In the second embodiment, the aspherical curve equation is expressed as the first embodiment. In addition, the definitions of the parameters in the following table are the same as those in the first embodiment, and will not be repeated here.

With Table 3 and Table 4, the following data can be calculated:

 Second embodiment  f [mm]  1.49  f12 / f3  0.29  Fno  2.0  f / TL  0.40  FOV [deg.]  77.91  R1 / R2  3.42  f / f12  0.65  R3 / R4  17.33  f / f23  1.28  R5 / R6  0.91  f1 / f2  -1.76  CT1 / CT2  0.79  f2 / f3  0.20  CT2 / CT3  1.36  f1 / f3  -0.35  CT1 / CT3  1.07  f1 / f23  -2.40

<Third Embodiment>

Please refer to FIG. 3A and FIG. 3B, wherein FIG. 3A is a schematic diagram of a three-piece infrared single-wavelength lens group according to a third embodiment of the present invention, and FIG. Single-wavelength lens group image plane curve and distortion aberration curve. As can be seen from FIG. 3A, the three-piece infrared single-wavelength lens group includes an aperture 300 and an optical group, and the optical group sequentially includes a first lens 310, a second lens 320, a third lens 330, The infrared filtering filter 370 and the imaging surface 380, wherein three lenses (310, 320, 330) with refractive power in the three-piece infrared single-wavelength lens group. The aperture 300 is disposed between the first lens 310 and the second lens 320.

The first lens 310 has a negative refractive power and is made of plastic. The object-side surface 311 is convex near the optical axis 390, the image-side surface 312 is concave near the optical axis 390, and the object-side surface 311 and the image side The surfaces 312 are all aspheric.

The second lens 320 has a positive refractive power and is made of plastic. The object-side surface 321 is concave at the near optical axis 390, the image-side surface 322 is convex at the near-optical axis 390, and the object-side surface 321 and the image side The surfaces 322 are all aspheric.

The third lens 330 has a positive refractive power and is made of plastic. The object-side surface 331 is convex near the optical axis 390, the image-side surface 332 is concave near the optical axis 390, and the object-side surface 331 and the image side The surfaces 332 are all aspherical surfaces, and at least one surface of the object-side surface 331 and the image-side surface 332 has at least one inflection point.

The infrared filter 370 is made of glass and is disposed between the third lens 330 and the imaging surface 380 without affecting the focal length of the three-piece infrared single-wavelength lens group.

Refer to Table 5 and Table 6 below for further cooperation.

table 5  Third embodiment f ( Focal length) = 1.49 mm (mm), Fno (aperture value) = 2.0, FOV (angle of view) = 77.90 deg. (Degrees)  Surface  Curvature radius  Thickness  Material  Refractive index  Dispersion coefficient  Focal length  0  Subject  Infinite  400  1  Infinite  0  2  First lens  4.705  (ASP)  0.602  Plastic  1.54  56  -2.98  3  1.137  (ASP)  0.271  4  Aperture  Infinite  0.133  5  Second lens  -16.856  (ASP)  0.750  Plastic  1.54  56  1.59  6  -0.822  (ASP)  0.063  7  Third lens  1.087  (ASP)  0.549  Plastic  1.54  56  8.86  8  1.162  (ASP)  0.570  9  Infrared filter  Infinite  0.300  Glass  1.517  64.17  10  Infinite  0.525  11  Imaging surface  Infinite  -

Table 6  Aspheric coefficient  Plane  2  3  5  6  7  8  K:  3.8604E + 00  3.2101E + 00  -1.0001E + 02  -6.1038E + 00  -1.5996E + 00  2.6418E-01  A:  3.0709E-01  1.0878E + 00  2.0179E-01  -1.4445E + 00  -6.1041E-02  2.9361E-01  B:  -1.1443E-01  9.3265E-01  1.2597E + 00  2.6941E + 00  -2.9449E-01  -1.2264E + 00  C:  -7.5850E-01  1.5572E + 01  -1.3966E + 01  -5.5142E + 00  6.8511E-01  1.3989E + 00  D:  3.7253E + 00  -2.1114E + 01  9.0065E + 01  7.5212E + 00  -7.4286E-01  -1.1461E + 00  E:  -7.1213E + 00  3.5686E + 02  -2.7158E + 02  7.7397E-01  -2.0586E + 00  -2.2590E-02  F  6.4293E + 00  -3.5542E + 03  3.9946E + 02  -2.7494E + 01  4.9270E + 00  9.4774E-01  G  -2.2747E + 00  1.6967E + 04  -2.3662E + 02  4.1759E + 01  -2.9126E + 00  -5.9429E-01

In the third embodiment, the aspherical curve equation is expressed as the first embodiment. In addition, the definitions of the parameters in the following table are the same as those in the first embodiment, and will not be repeated here.

With Table 5 and Table 6, the following data can be calculated:

 Third embodiment  f [mm]  1.49  f12 / f3  0.25  Fno  2.0  f / TL  0.40  FOV [deg.]  77.90  R1 / R2  4.14  f / f12  0.68  R3 / R4  20.50  f / f23  1.25  R5 / R6  0.94  f1 / f2  -1.87  CT1 / CT2  0.80  f2 / f3  0.18  CT2 / CT3  1.37  f1 / f3  -0.34  CT1 / CT3  1.10  f1 / f23  -2.51

<Fourth embodiment>

Please refer to FIG. 4A and FIG. 4B, wherein FIG. 4A shows a schematic diagram of a three-piece infrared single-wavelength lens group according to a fourth embodiment of the present invention, and FIG. 4B is a three-piece infrared of the fourth embodiment in order from left to right Single-wavelength lens group image plane curve and distortion aberration curve. As can be seen from FIG. 4A, the three-piece infrared single-wavelength lens group includes an aperture 400 and an optical group, and the optical group sequentially includes a first lens 410, a second lens 420, a third lens 430, The infrared filtering filter 470 and the imaging surface 480, among which three lenses (410, 420, 430) with refractive power in the three-piece infrared single-wavelength lens group. The aperture 400 is disposed between the first lens 410 and the second lens 420.

The first lens 410 has a negative refractive power and is made of plastic. The object-side surface 411 is convex near the optical axis 490, and its image-side surface 412 is concave near the optical axis 490. The surfaces 412 are all aspherical.

The second lens 420 has a positive refractive power and is made of plastic. The object-side surface 421 is concave at a position near the optical axis 490, the image-side surface 422 is convex at a position near the optical axis 490, and the object-side surface 421 and the image side The surfaces 422 are all aspherical.

The third lens 430 has a negative refractive power and is made of plastic. Its object-side surface 431 is convex near the optical axis 490, its image-side surface 432 is concave near the optical axis 490, and the object-side surface 431 and the image side The surfaces 432 are all aspheric, and at least one surface of the object-side surface 431 and the image-side surface 432 has at least one inflection point.

The infrared filter 470 is made of glass and is disposed between the third lens 430 and the imaging surface 480 without affecting the focal length of the three-piece infrared single-wavelength lens group.

Refer to Table 7 and Table 8 below for further cooperation.

Table 7  Fourth embodiment f ( Focal length) = 1.48 mm (mm), Fno (aperture value) = 2.0, FOV (picture angle) = 77.92 deg. (Degrees)  Surface  Curvature radius  Thickness  Material  Refractive index  Dispersion coefficient  Focal length  0  Subject  Infinite  400  1  Infinite  0  2  First lens  1.956  (ASP)  0.491  Plastic  1.64  22.46  -3.90  3  0.977  (ASP)  0.272  4  Aperture  Infinite  0.162  5  Second lens  -7.733  (ASP)  0.688  Plastic  1.64  22.46  1.31  6  -0.763  (ASP)  0.031  7  Third lens  1.269  (ASP)  0.407  Plastic  1.64  22.46  -78.93  8  1.085  (ASP)  0.556  9  Infrared filter  Infinite  0.300  Glass  1.517  64.17  10  Infinite  0.506  11  Imaging surface  Infinite  -

Table 8  Aspheric coefficient  Plane  2  3  5  6  7  8  K:  -2.2390E + 00  4.1672E + 00  7.2309E + 01  -4.7502E + 00  -1.9112E + 00  1.4270E-01  A:  3.5786E-01  7.9903E-01  5.1762E-02  -1.3765E + 00  -7.1093E-02  8.8149E-02  B:  5.5728E-02  1.2861E + 00  1.5493E + 00  2.7087E + 00  -3.5407E-01  -1.1246E + 00  C:  -5.7846E-01  3.3499E + 00  -1.3171E + 01  -5.7142E + 00  6.9128E-01  1.4349E + 00  D:  3.6046E + 00  4.7493E + 00  8.8838E + 01  7.4603E + 00  -8.1157E-01  -1.1405E + 00  E:  -7.2812E + 00  3.9678E + 02  -2.7472E + 02  1.1838E + 00  -1.7842E + 00  1.6324E-02  F  6.6380E + 00  -4.4874E + 03  4.0815E + 02  -2.5526E + 01  5.4012E + 00  6.2446E-01  G  -1.3242E + 00  2.3249E + 04  -2.4394E + 02  4.2597E + 01  -3.9130E + 00  -3.9325E-01

In the fourth embodiment, the curve equation of the aspherical surface is expressed as the first embodiment. In addition, the definitions of the parameters in the following table are the same as those in the first embodiment, and will not be repeated here.

With Table 7 and Table 8, the following data can be calculated:

 Fourth embodiment  f [mm]  1.48  f12 / f3  -0.02  Fno  2.0  f / TL  0.43  FOV [deg.]  77.92  R1 / R2  2.00  f / f12  0.89  R3 / R4  10.14  f / f23  1.27  R5 / R6  1.17  f1 / f2  -2.97  CT1 / CT2  0.71  f2 / f3  -0.02  CT2 / CT3  1.69  f1 / f3  0.05  CT1 / CT3  1.21  f1 / f23  -3.34

<Fifth Embodiment>

Please refer to FIGS. 5A and 5B. FIG. 5A is a schematic diagram of a three-piece infrared single-wavelength lens group according to a fifth embodiment of the present invention. FIG. 5B is a three-piece infrared of the fifth embodiment in order from left to right. Single-wavelength lens group image plane curve and distortion aberration curve. It can be seen from FIG. 5A that the three-piece infrared single-wavelength lens group includes an aperture 500 and an optical group, and the optical group sequentially includes a first lens 510, a second lens 520, a third lens 530, The infrared filtering filter 570 and the imaging surface 580, among which three lenses (510, 520, 530) with refractive power in the three-piece infrared single-wavelength lens group. The aperture 500 is disposed between the first lens 510 and the second lens 520.

The first lens 510 has a negative refractive power and is made of plastic. The object-side surface 511 is convex near the optical axis 590, and the image-side surface 512 is concave near the optical axis 590. The surfaces 512 are all aspheric.

The second lens 520 has a positive refractive power and is made of plastic. The object-side surface 521 thereof is concave near the optical axis 590, and its image-side surface 522 is convex near the optical axis 590. The surfaces 522 are all aspherical.

The third lens 530 has a positive refractive power and is made of plastic. Its object-side surface 531 is convex near the optical axis 590, its image-side surface 532 is concave near the optical axis 590, and the object-side surface 531 and the image side The surfaces 532 are all aspheric, and at least one of the object-side surface 531 and the image-side surface 532 has at least one inflection point.

The infrared filter 570 is made of glass and is disposed between the third lens 530 and the imaging surface 580 without affecting the focal length of the three-piece infrared single-wavelength lens group.

Refer to Table 9 and Table 10 below for further cooperation.

Table 9  Fifth Embodiment f ( Focal length) = 1.54 mm (mm), Fno (aperture value) = 2.0, FOV (painting angle) = 74.94 deg. (Degrees)  Surface  Curvature radius  Thickness  Material  Refractive index  Dispersion coefficient  Focal length  0  Subject  Infinite  400  1  Infinite  0  2  First lens  2.202  (ASP)  0.590  Plastic  1.64  22.46  -3.90  3  1.035  (ASP)  0.313  4  Aperture  Infinite  0.160  5  Second lens  -10.566  (ASP)  0.701  Plastic  1.64  22.46  1.49  6  -0.869  (ASP)  0.068  7  Third lens  1.322  (ASP)  0.501  Plastic  1.64  22.46  17.49  8  1.287  (ASP)  0.557  9  Infrared filter  Infinite  0.300  Glass  1.517  64.17  10  Infinite  0.512  11  Imaging surface  Infinite  -

Table 10  Aspheric coefficient  Plane  2  3  5  6  7  8  K:  -7.8009E + 00  4.0019E + 00  8.2382E + 01  -6.3430E + 00  -2.5821E + 00  3.6935E-01  A:  3.2392E-01  9.2476E-01  4.3206E-02  -1.3338E + 00  -5.4925E-02  1.7484E-01  B:  -4.7520E-03  -2.2725E + 00  1.5276E + 00  2.7900E + 00  -2.3750E-01  -1.0033E + 00  C:  -7.4350E-01  1.6052E + 01  -1.3402E + 01  -5.6303E + 00  7.9650E-01  1.4545E + 00  D:  3.6126E + 00  2.0368E + 01  8.9465E + 01  7.5649E + 00  -7.8032E-01  -1.2230E + 00  E:  -7.0746E + 00  2.4563E + 02  -2.7315E + 02  1.5984E + 00  -2.0042E + 00  3.1563E-02  F  6.7177E + 00  -4.8788E + 03  4.0098E + 02  -2.5663E + 01  5.1399E + 00  8.3926E-01  G  -2.4136E + 00  1.9148E + 04  -2.3677E + 02  3.8274E + 01  -3.1164E + 00  -5.2049E-01

In the fifth embodiment, the aspherical curve equation is expressed as the first embodiment. In addition, the definitions of the parameters in the following table are the same as those in the first embodiment, and will not be repeated here.

With Table 9 and Table 10, the following data can be calculated:

 Fifth Embodiment  f [mm]  1.54  f12 / f3  0.11  Fno  2.0  f / TL  0.42  FOV [deg.]  74.94  R1 / R2  2.13  f / f12  0.78  R3 / R4  12.15  f / f23  1.28  R5 / R6  1.03  f1 / f2  -2.63  CT1 / CT2  0.84  f2 / f3  0.08  CT2 / CT3  1.40  f1 / f3  -0.22  CT1 / CT3  1.18  f1 / f23  -3.24

<Sixth embodiment>

Please refer to FIG. 6A and FIG. 6B. FIG. 6A shows a schematic diagram of a three-piece infrared single-wavelength lens group according to a sixth embodiment of the present invention. FIG. Single-wavelength lens group image plane curve and distortion aberration curve. It can be seen from FIG. 6A that the three-piece infrared single-wavelength lens group includes an aperture 600 and an optical group, and the optical group sequentially includes a first lens 610, a second lens 620, a third lens 630, The infrared filtering filter 670 and the imaging surface 680, among which three lenses with refractive power in the three-piece infrared single-wavelength lens group are (610, 620, 630). The aperture 600 is disposed between the first lens 610 and the second lens 620.

The first lens 610 has a negative refractive power and is made of plastic. An object-side surface 611 of the first lens 610 is convex near the optical axis 690, an image-side surface 612 of the first lens 610 is concave near the optical axis 690, and the object-side surface 611 and the image side The surfaces 612 are all aspherical.

The second lens 620 has a positive refractive power and is made of plastic. An object-side surface 621 of the second lens 620 is concave near the optical axis 690, an image-side surface 622 of the second lens 620 is convex near the optical axis 690, and the object-side surface 621 and the image side The surfaces 622 are all aspherical.

The third lens 630 has a positive refractive power and is made of plastic. The object-side surface 631 is convex near the optical axis 690, the image-side surface 632 is concave near the optical axis 690, and the object-side surface 631 and the image side The surfaces 632 are all aspheric, and at least one surface of the object-side surface 631 and the image-side surface 632 has at least one inflection point.

The infrared filter 670 is made of glass and is disposed between the third lens 630 and the imaging surface 680 without affecting the focal length of the three-piece infrared single-wavelength lens group.

Refer to Table 11 and Table 12 for further cooperation.

Table 11  Sixth embodiment f ( Focal length) = 1.57 mm (mm), Fno (aperture value) = 2.1, FOV (painting angle) = 74.88 deg. (Degrees)  Surface  Curvature radius  Thickness  Material  Refractive index  Dispersion coefficient  Focal length  0  Subject  Infinite  Infinite  1  Infinite  0  2  First lens  2.500  (ASP)  0.433  Plastic  1.54  56  -26.05  3  1.988  (ASP)  0.159  4  Aperture  Infinite  0.160  5  Second lens  -1.834  (ASP)  0.701  Plastic  1.63  23.9  1.75  6  -0.775  (ASP)  0.249  7  Third lens  1.407  (ASP)  0.570  Plastic  1.54  56  22.37  8  1.375  (ASP)  0.503  9  Infrared filter  Infinite  0.300  Glass  1.517  64.17  10  Infinite  0.326  11  Imaging surface  Infinite  -

Table 12  Aspheric coefficient  Plane  2  3  5  6  7  8  K:  5.2732E + 00  2.0909E + 01  -9.5305E-01  -5.6895E + 00  -2.4514E + 00  -7.6091E-02  A:  3.3414E-01  8.4239E-01  -7.7180E-02  -1.4036E + 00  2.0463E-03  7.0750E-02  B:  2.7099E-01  -7.1657E-01  1.1784E + 00  2.7424E + 00  -9.5297E-02  -2.4395E-01  C:  -2.4011E + 00  4.4395E + 01  -9.3653E + 00  -5.9797E + 00  -1.1786E-01  -4.2916E-02  D:  1.0078E + 01  -2.3174E + 02  6.3816E + 01  5.0229E + 00  -8.2333E-03  1.1159E-01  E:  -3.5750E + 00  1.3698E + 02  -2.8006E + 02  2.7918E-01  7.3641E-02  1.7417E-02  F  -3.8559E + 01  1.0939E + 03  8.6338E + 02  -2.1985E + 00  7.8696E-02  -8.2864E-02  G  5.4058E + 01  9.4539E + 03  -1.2923E + 03  -2.9416E + 00  -2.0725E-01  3.1924E-02

In the sixth embodiment, the curve equation of the aspherical surface is expressed as the first embodiment. In addition, the definitions of the parameters in the following table are the same as those in the first embodiment, and will not be repeated here.

With Table 11 and Table 12, the following data can be calculated:

 Sixth embodiment  f [mm]  1.57  f12 / f3  0.09  Fno  2.1  f / TL  0.46  FOV [deg.]  74.88  R1 / R2  1.26  f / f12  0.81  R3 / R4  2.36  f / f23  1.10  R5 / R6  1.02  f1 / f2  -14.86  CT1 / CT2  0.62  f2 / f3  0.08  CT2 / CT3  1.23  f1 / f3  -1.16  CT1 / CT3  0.76  f1 / f23  -18.15

<Seventh Embodiment>

Please refer to FIG. 7A and FIG. 7B. FIG. 7A shows a schematic diagram of a three-piece infrared single-wavelength lens group according to a seventh embodiment of the present invention. FIG. Single-wavelength lens group image plane curve and distortion aberration curve. As can be seen from FIG. 7A, the three-piece infrared single-wavelength lens group includes an aperture 700 and an optical group, and the optical group sequentially includes a first lens 710, a second lens 720, a third lens 730, The infrared filtering filter 770 and the imaging surface 780. Among the three-piece infrared single-wavelength lens group, three lenses (710, 720, 730) have refractive power. The aperture 700 is disposed between the first lens 710 and the second lens 720.

The first lens 710 has a negative refractive power and is made of plastic. The object-side surface 711 is convex at a position near the optical axis 790, the image-side surface 712 is concave at a position near the optical axis 790, and the object-side surface 711 and the image side The surfaces 712 are all aspherical.

The second lens 720 has a positive refractive power and is made of plastic. An object-side surface 721 thereof is concave at a position near the optical axis 790, an image-side surface 722 thereof is convex at a position near the optical axis 790, and the object-side surface 721 and the image side The surfaces 722 are all aspherical.

The third lens 730 has a positive refractive power and is made of plastic. Its object-side surface 731 is convex at the near optical axis 790, its image-side surface 732 is concave at the near-optical axis 790, and the object-side surface 731 and the image side The surface 732 is an aspheric surface, and at least one surface of the object-side surface 731 and the image-side surface 732 has at least one inflection point.

The infrared filter 770 is made of glass and is disposed between the third lens 730 and the imaging surface 780 without affecting the focal length of the three-piece infrared single-wavelength lens group.

Refer to Table 13 and Table 14 below for further cooperation.

Table 13  Seventh embodiment f ( Focal length) = 1.46 mm (mm), Fno (aperture value) = 2.0, FOV (picture angle) = 84.9 deg. (Degrees)  Surface  Curvature radius  Thickness  Material  Refractive index  Dispersion coefficient  Focal length  0  Subject  Infinite  Infinite  1  Infinite  0  2  First lens  2.268  (ASP)  0.604  Plastic  1.54  56  -26.05  3  0.942  (ASP)  0.270  4  Aperture  Infinite  0.138  5  Second lens  17.583  (ASP)  0.782  Plastic  1.63  23.9  1.75  6  -0.817  (ASP)  0.070  7  Third lens  1.391  (ASP)  0.422  Plastic  1.54  56  22.37  8  1.235  (ASP)  0.546  9  Infrared filter  Infinite  0.300  Glass  1.517  64.17  10  Infinite  0.501  11  Imaging surface  Infinite  -

Table 4  Aspheric coefficient  Plane  2  3  5  6  7  8  K:  -9.7413E + 00  3.1682E + 00  1.0001E + 02  -5.3455E + 00  -3.2823E + 00  2.7202E-01  A:  3.1137E-01  8.2309E-01  3.7344E-03  -1.3292E + 00  -6.1724E-02  1.4826E-01  B:  -1.0515E-02  -1.4297E + 00  1.1470E + 00  2.6637E + 00  -3.0264E-01  -1.0266E + 00  C:  -7.6675E-01  1.6638E + 01  -1.3918E + 01  -5.7517E + 00  7.3444E-01  1.4292E + 00  D:  3.6057E + 00  2.6176E + 00  9.0309E + 01  7.6743E + 00  -8.3905E-01  -1.2264E + 00  E:  -7.0811E + 00  2.3399E + 02  -2.7074E + 02  1.6806E + 00  -2.0145E + 00  2.5782E-02  F  6.7095E + 00  -4.7000E + 03  4.0328E + 02  -2.6807E + 01  5.1297E + 00  8.7831E-01  G  -2.4452E + 00  1.9814E + 04  -2.4640E + 02  3.4028E + 01  -2.8834E + 00  -4.9463E-01

In the seventh embodiment, the curve equation of the aspherical surface is expressed as the first embodiment. In addition, the definitions of the parameters in the following table are the same as those in the first embodiment, and will not be repeated here.

With Table 13 and Table 14, the following data can be calculated:

 Seventh embodiment  f [mm]  1.46  f12 / f3  0.003  Fno  2.0  f / TL  0.40  FOV [deg.]  84.90  R1 / R2  2.41  f / f12  0.88  R3 / R4  -21.53  f / f23  1.30  R5 / R6  1.13  f1 / f2  -2.46  CT1 / CT2  0.77  f2 / f3  0.002  CT2 / CT3  1.85  f1 / f3  -0.01  CT1 / CT3  1.43  f1 / f23  -2.79

In the three-piece infrared single-wavelength lens group provided by the present invention, the material of the lens can be plastic or glass. When the material of the lens is plastic, the production cost can be effectively reduced, and when the material of the lens is glass, a three-piece infrared single lens can be added. The degree of freedom in the configuration of the refractive power of the wavelength lens group. In addition, the object-side surface and the image-side surface of the lens in the three-piece infrared single-wavelength lens group can be aspheric, and the aspheric surface can be easily made into a shape other than a spherical surface, and more control variables are obtained to reduce aberrations and further By reducing the number of lenses used, the total length of the three-piece infrared single-wavelength lens group of the present invention can be effectively reduced.

In the three-piece infrared single-wavelength lens group provided by the present invention, in the case of a lens having a refractive power, if the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at the near optical axis. ; If the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at the near optical axis.

The three-piece infrared single-wavelength lens group provided by the present invention can be more applied to the optical system of mobile focusing according to requirements, and has the characteristics of excellent aberration correction and good imaging quality, and can be applied to 3D (three-dimensional) image capture in various aspects. , Electronic cameras such as digital cameras, mobile devices, digital tablets, or car photography.

In summary, the above-mentioned embodiments and drawings are only preferred embodiments of the present invention. When the scope of implementation of the present invention cannot be limited by this, that is, all equal changes and modifications made in accordance with the scope of the patent application of the present invention, It should be within the scope of the invention patent.

100, 200, 300, 400, 500, 600, 700‧‧‧ aperture

110, 210, 310, 410, 510, 610, 710‧‧‧ first lens

111, 211, 311, 411, 511, 611, 711‧‧‧ object-side surface

112, 212, 312, 412, 512, 612, 712‧‧‧ image side surface

120, 220, 320, 420, 520, 620, 720‧‧‧ second lens

121, 221, 321, 421, 521, 621, 721‧‧‧ object-side surface

122, 222, 322, 422, 522, 622, 722‧‧‧ image side surface

130, 230, 330, 430, 530, 630, 730‧‧‧ third lens

131, 231, 331, 431, 531, 631, 731‧‧‧ object-side surface

132, 232, 332, 432, 532, 632, 732‧‧‧ image side surface

170, 270, 370, 470, 570, 670, 770‧‧‧IR filter

180, 280, 380, 480, 580, 680, 780‧‧‧ imaging surface

190, 290, 390, 490, 590, 690, 790‧‧‧ Optical axis

f‧‧‧Three-piece infrared single-wavelength lens group focal length

Aperture value of Fno‧‧‧three-piece infrared single-wavelength lens group

Maximum field of view in FOV‧‧‧three-piece infrared single-wavelength lens group

f1‧‧‧ focal length of the first lens

f2‧‧‧ focal length of the second lens

f3‧‧‧ focal length of the third lens

f12‧‧‧The combined focal length of the first lens and the second lens

f23‧‧‧The combined focal length of the second lens and the third lens

TL‧‧‧The distance from the object-side surface of the first lens to the imaging plane on the optical axis

R1‧‧‧ the radius of curvature of the object-side surface of the first lens

R2‧‧‧The curvature radius of the image side surface of the first lens

R3‧‧‧Second lens surface curvature radius

R4‧‧‧The curvature radius of the image side surface of the second lens

R5‧‧‧ third lens object surface curvature radius

R6‧‧‧ third image lens surface curvature radius

CT1‧‧‧thickness of the first lens on the optical axis

CT2‧‧‧thickness of the second lens on the optical axis

CT3‧thickness of the third lens on the optical axis

FIG. 1A is a schematic diagram of a three-piece infrared single-wavelength lens group according to the first embodiment of the present invention. FIG. 1B is a curve diagram of the curvature and distortion of the image plane of the three-piece infrared single-wavelength lens group of the first embodiment in order from left to right. 2A is a schematic diagram of a three-piece infrared single-wavelength lens group according to a second embodiment of the present invention. FIG. 2B is a curve diagram of the curvature and distortion of the image plane of the three-piece infrared single-wavelength lens group of the second embodiment in order from left to right. 3A is a schematic diagram of a three-piece infrared single-wavelength lens group according to a third embodiment of the present invention. 3B is a curve diagram of the curvature and distortion of the image plane of the three-piece infrared single-wavelength lens group of the third embodiment in order from left to right. 4A is a schematic diagram of a three-piece infrared single-wavelength lens group according to a fourth embodiment of the present invention. FIG. 4B is a curve diagram of the curvature and distortion of the image plane of the three-piece infrared single-wavelength lens group of the fourth embodiment in order from left to right. 5A is a schematic diagram of a three-piece infrared single-wavelength lens group according to a fifth embodiment of the present invention. 5B is a curve diagram of the curvature and distortion of the image plane of the three-piece infrared single-wavelength lens group of the fifth embodiment in order from left to right. 6A is a schematic diagram of a three-piece infrared single-wavelength lens group according to a sixth embodiment of the present invention. FIG. 6B is a curve diagram of the curvature and distortion of the image plane of the three-piece infrared single-wavelength lens group of the sixth embodiment in order from left to right. FIG. 7A is a schematic diagram of a three-piece infrared single-wavelength lens group according to a seventh embodiment of the present invention. FIG. 7B is a curve diagram of the curvature and distortion of the image plane of the three-piece infrared single-wavelength lens group of the seventh embodiment in order from left to right.

Claims (15)

A three-piece infrared single-wavelength lens group includes sequentially from the object side to the image side: a first lens having a negative refractive power, the object side surface of which is near the optical axis is convex, and the image side surface of which is near the optical axis is Concave surface, at least one of its object-side surface and image-side surface is aspheric; an aperture; a second lens with positive refractive power, its image-side surface is convex near the optical axis, and its object-side surface and image-side surface are at least One surface is aspheric; and a third lens has a refractive power, and the object-side surface thereof is convex near the optical axis, and the image-side surface thereof is concave near the optical axis, and at least one of the object-side surface and the image-side surface is Aspherical. The three-piece infrared single-wavelength lens group according to claim 1, wherein the overall focal length of the three-piece infrared single-wavelength lens group is f, the combined focal distance of the first lens and the second lens is f12, and the following conditions are satisfied: : 0.5 <f / f12 <1.1. The three-piece infrared single-wavelength lens group according to claim 1, wherein the overall focal length of the three-piece infrared single-wavelength lens group is f, and the combined focal distance of the second lens and the third lens is f23, and satisfies the following conditions : 0.8 <f / f23 <1.6. The three-piece infrared single-wavelength lens group according to claim 1, wherein the focal length of the first lens is f1 and the focal length of the second lens is f2, and the following conditions are satisfied: -19 <f1 / f2 <-1.4. The three-piece infrared single-wavelength lens group according to claim 1, wherein the focal length of the second lens is f2, and the focal length of the third lens is f3, and the following conditions are satisfied: -0.02 <f2 / f3 <0.26. The three-piece infrared single-wavelength lens group according to claim 1, wherein the focal length of the first lens is f1, and the focal length of the third lens is f3, and the following conditions are satisfied: -1.5 <f1 / f3 <0.07. The three-piece infrared single-wavelength lens group according to claim 1, wherein the focal length of the first lens is f1, and the combined focal distance of the second lens and the third lens is f23, and the following conditions are satisfied: -23 <f1 / f23 <-1.9. The three-piece infrared single-wavelength lens group according to claim 1, wherein the combined focal length of the first lens and the second lens is f12, the focal length of the third lens is f3, and the following conditions are satisfied: -0.05 <f12 / f3 <0.37. The three-piece infrared single-wavelength lens group according to claim 1, wherein the curvature radius of the object-side surface of the first lens is R1, the curvature radius of the image-side surface of the first lens is R2, and the following conditions are satisfied: 0.9 < R1 / R2 <5.3. The three-piece infrared single-wavelength lens group according to claim 1, wherein the curvature radius of the object-side surface of the second lens is R3, the curvature radius of the image-side surface of the second lens is R4, and the following conditions are satisfied: -27 <R3 / R4 <27. The three-piece infrared single-wavelength lens group according to claim 1, wherein the curvature radius of the object-side surface of the third lens is R5, and the curvature radius of the image-side surface of the third lens is R6, and satisfies the following conditions: 0.7 < R5 / R6 <1.5. The three-piece infrared single-wavelength lens group according to claim 1, wherein the thickness of the first lens on the optical axis is CT1, and the thickness of the second lens on the optical axis is CT2, and the following conditions are satisfied: 0.5 < CT1 / CT2 <1.1. The three-piece infrared single-wavelength lens group according to claim 1, wherein the thickness of the second lens on the optical axis is CT2, and the thickness of the third lens on the optical axis is CT3, and the following conditions are satisfied: 0.9 < CT2 / CT3 <2.4. The three-piece infrared single-wavelength lens group according to claim 1, wherein the thickness of the first lens on the optical axis is CT1, and the thickness of the third lens on the optical axis is CT3, and the following conditions are satisfied: 0.6 < CT1 / CT3 <1.8. The three-piece infrared single-wavelength lens group according to claim 1, wherein the overall focal length of the three-piece infrared single-wavelength lens group is f, and the distance from the object-side surface of the first lens to the imaging surface on the optical axis is TL and satisfy the following conditions: 0.3 <f / TL <0.6.