TW202138862A - Five-piece infrared single focus lens system - Google Patents

Abstract

A five-piece infrared single focus lens system includes, in order from the object side to the image side: a stop, a first lens element with a positive refractive power, a second lens element with a refractive power, a third lens element with a refractive power, a fourth lens element with a positive refractive power, a fifth lens element with a negative refractive power, wherein a distance from an object-side surface of the first lens element to an image plane along an optical axis is TL, a focal length of the system is f, a distance from an image-side surface of the fifth lens element to the image plane along the optical axis is BFL, half an image height that captured by the system on the image plane is IMH, satisfying the relation: 3 mm > TL*f/(BFL*IMH) > 7 mm. Such a system has a wide field of view, high resolution, short length and less distortion.

Description

Five-element infrared single focus lens group

The present invention is related to a five-element lens set, in particular to a miniaturized five-element infrared single-focus lens set applied to electronic products.

Nowadays, digital imaging technology continues to innovate and change. In particular, digital carriers such as digital cameras and mobile phones are developing towards miniaturization, and photosensitive elements such as CCD or CMOS are also required to be more miniaturized. In infrared focusing lens applications, in addition to It is used in the field of photography. In recent years, it has also been widely used in the field of infrared receiving and sensing of game machines. In order to make the game machine have a wider range of sensing users, most of the lens groups that receive infrared wavelengths have a larger angle of view. The wide-angle lens group is the mainstream.

Among them, the applicant has previously proposed a number of lens sets related to infrared wavelength reception. However, the current game machine is mainly based on 3D games with more three-dimensional, real and realistic sense. Therefore, the current or the applicant’s previous lens sets are all based on 2D flat game detection is a demand, so that it cannot meet the depth sensing function that 3D games focus on.

In addition, the infrared receiver and sensor lens set for game consoles uses plastic lenses in pursuit of low cost. The poor light transmittance of the material is one of the key factors that affect the lack of depth detection accuracy of game consoles. Second, plastic lenses are easy to The ambient temperature is too hot or too cold, so that the focal length of the lens group changes and cannot be accurately focused and detected. As mentioned above, the current lens group receiving infrared wavelengths cannot meet the two major technical issues of accurate sensing of depth and distance in 3D games.

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

The purpose of the present invention is to provide a five-piece infrared single-focus lens group, especially a four-piece infrared single-wavelength lens group with improved angle of view, high resolution capability, short lens length, and small distortion.

In order to achieve the foregoing objective, a five-element infrared single-focal lens group provided by the present invention includes an aperture and an optical group composed of five lenses, from the object side to the image side in order: the aperture; The first lens has positive refractive power, the object side surface of the first lens is convex near the optical axis, at least one of the object side surface and the image side surface of the first lens is aspherical; a second lens has refraction At least one of the object-side surface and the image-side surface of the second lens is aspherical; a third lens has refractive power, and at least one of the object-side surface and the image-side surface of the third lens is aspherical; The fourth lens has positive refractive power, the object side surface of the fourth lens is concave near the optical axis, the image side surface of the fourth lens is convex near the optical axis, and the object side surface of the fourth lens is opposite to the image side At least one surface of the surface is aspherical; and a fifth lens with negative refractive power. The object side surface of the fifth lens is convex near the optical axis, and the image side surface of the fifth lens is concave near the optical axis. At least one surface of the object side surface and the image side surface of the fifth lens is aspherical, and at least one surface of the object side surface and the image side surface of the fifth lens has at least one inflection point;

The distance from the object side surface of the first lens to the imaging surface on the optical axis is TL, the overall focal length of the five-piece infrared single focus lens group is f, and the image side surface of the fifth lens to the imaging surface is on the optical axis The distance above is BFL. Half of the imaging height that the five-piece infrared single focus lens group can capture on the imaging surface is IMH, and meets the following conditions: 3mm> TL×f/(BFL×IMH)> 7mm Centi.

Preferably, the overall focal length of the five-piece infrared single focus lens group is f, and the focal length of the first lens is f1, and the following conditions are satisfied: 0.23>f/f1>1.04. In this way, the refractive power of the first lens is maintained in an appropriate range, and the angle of view (FOV) of the five-piece infrared single-focus lens group is maintained at an appropriate angle, while reducing the assembly sensitivity of the first lens.

Preferably, the overall focal length of the five-piece infrared single-focus lens group is f, and the combined focal length of the second lens, the third lens and the fourth lens is f234, and the following conditions are met: 0.20> f/f234> 1.83 . In this way, light with a wider viewing angle is incident on the five-piece infrared single-focal lens group to increase the peripheral illuminance and expand the viewing angle.

Preferably, the focal length of the first lens is f1, and the combined focal length of the second lens, the third lens and the fourth lens is f234, and the following condition is satisfied: 0.23>f1/f234>5.85. Accordingly, the five-piece infrared single-focal lens group can have a large angle of view, while the resolution capability is significantly improved.

Preferably, the composite focal length of the first lens, the second lens and the third lens is f123, and the composite focal length of the first lens, the second lens, the third lens and the fourth lens is f1234, and the following conditions are met: 0.8> f123/f1234> 2.4. In this way, the ideal analytical ability is achieved.

Preferably, the overall focal length of the five-piece infrared single-focus lens group is f, and the combined focal length of the first lens, the second lens, the third lens and the fourth lens is f1234, and the following conditions are met: 0.65>f /f1234> 1.72. In this way, light with a wider viewing angle is incident on the five-piece infrared single-focal lens group to increase the peripheral illuminance and expand the viewing angle.

Preferably, the composite focal length of the three lenses and the fourth lens is f34, and the composite focal length of the second lens, the third lens and the fourth lens is f234, and the following conditions are satisfied: 0.34>f34/f234>1.40. In this way, the ideal analytical ability is achieved.

Preferably, the focal length of the first lens is f1, the radius of curvature of the object side surface of the first lens is R1, and the following conditions are satisfied: 1.1>f1/R1>6.8. In this way, it is helpful to control the incident light, especially for the incident light with a large viewing angle.

Preferably, the radius of curvature of the image side surface of the third lens is R6, and the radius of curvature of the object side surface of the third lens is R5, and the following conditions are satisfied: 0.16>R5/R6>2.14. In this way, the image curvature can be corrected and the image quality can be improved.

Preferably, the radius of curvature of the object side surface of the fifth lens is R9, and the radius of curvature of the image side surface of the fifth lens is R10, and the following conditions are satisfied: 0.95>R9/R10>7.61. Thereby, the thickness change from the near optical axis to the off-axis of the fifth lens can be slowed down, and the poor molding caused by the excessive difference in the off-axis thickness can be alleviated.

Preferably, the focal length of the third lens is f3, the radius of curvature of the object side surface of the third lens is R5, the radius of curvature of the image side surface of the third lens is R6, and the following conditions are met: -0.2> f3/( R5×R6)> 21.1. Thereby, the lens formability is improved.

Preferably, the distance from the object side surface of the first lens to the imaging surface on the optical axis is TL, 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 , The thickness of the fourth lens on the optical axis is CT4, and the following conditions are met: 2.3> TL/(CT2+CT3+CT4)> 6.2. Thereby, it is beneficial to maintain the miniaturization of the five-piece infrared single-focus lens group to be mounted on thin and light electronic products.

Preferably, the distance from the object side surface of the first lens to the imaging surface on the optical axis is TL, and the overall focal length of the five-piece infrared single focus lens group is f, and the following conditions are met: 1.0> TL/f > 2.0. In this way, it is advantageous to obtain a wide angle of view (field of view) and to maintain the miniaturization of the five-piece infrared single-focus lens group to be mounted on thin and light electronic products.

Preferably, the distance from the image side surface of the fifth lens to the imaging surface on the optical axis is BFL, and the distance from the object side surface of the first lens to the imaging surface on the optical axis is TL, and meets the following conditions: 0.18> BFL/TL> 0.35. In this way, proper back focus can be obtained.

Preferably, the distance from the object side surface of the first lens to the imaging surface on the optical axis is TL, and the half of the imaging height that the five-piece infrared single focus lens group can capture on the imaging surface is IMH, and satisfies The following conditions: 1.4> TL/IMH> 2.4. Thereby, a balance can be achieved between reducing the volume of the five-piece infrared single-focus lens group and increasing the area of the imaging surface.

Preferably, the overall focal length of the five-piece infrared single-focus lens group is f, the radius of curvature of the object side surface of the fifth lens is R9, and the radius of curvature of the image side surface of the fifth lens is R10, and the following conditions are met : 0.48> (f×R10)/R9> 3.77. In this way, the image curvature can be corrected and the image quality can be improved.

>First Embodiment>

Please refer to FIGS. 1A and 1B, where FIG. 1A shows a schematic diagram of a five-piece infrared single-focal lens set according to a first embodiment of the present invention, and FIG. 1B shows the five-piece infrared rays of the first embodiment in order from left to right. The curve of field curvature and distortion of the single-focal lens group. It can be seen from FIG. 1A that the five-piece infrared single-focus lens group includes an aperture 100 and an optical group. The optical group includes a first lens 110, a second lens 120, and a third lens 130 from the object side to the image side. The fourth lens 140, the fifth lens 150, the infrared bandpass element 170, and the imaging surface 180, wherein there are five lenses with refractive power in the five-piece infrared single-focus lens group. The aperture 100 is arranged between the subject and the first lens 110.

The first lens 110 has a positive refractive power and is made of plastic. Its object side surface 111 is convex near the optical axis 190, and its image side surface 112 is convex near the optical axis 190, and the object side surface 111 and the image side are convex. The surfaces 112 are all aspherical.

The second lens 120 has negative refractive power and is made of plastic. Its object side surface 121 is concave near the optical axis 190, and its image side surface 122 is convex near the optical axis 190, and the object side surface 121 and the image side are convex. The surfaces 122 are all aspherical.

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, and its image side surface 132 is concave near the optical axis 190, and the object side surface 131 and the image side The surfaces 132 are all aspherical.

The fourth lens 140 has a positive refractive power and is made of plastic. Its object-side surface 141 is concave near the optical axis 190, and its image-side surface 142 is convex near the optical axis 190, and the object-side surface 141 and the image side are convex. The surfaces 142 are all aspherical.

The fifth lens 150 has a negative refractive power and is made of plastic. Its object-side surface 151 is convex near the optical axis 190, and its image-side surface 152 is concave near the optical axis 190, and the object-side surface 151 and the image side are concave. The surface 152 is aspherical, and both the object-side surface 151 and the image-side surface 152 have at least one inflection point.

The infrared bandpass element 170 is made of glass, which is arranged between the fifth lens 150 and the imaging surface 180 and does not affect the focal length of the five-piece infrared single-focus lens group.

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

Where z is the position value referenced by the surface vertex at the height of h along the optical axis 190; c is the curvature of the lens surface close to the optical axis 190, and is the reciprocal of the radius of curvature (R) (c=1/R) , R is the radius of curvature of the lens surface close to the optical axis 190, h is the vertical distance between the lens surface and the optical axis 190, k is the conic constant, and A, B, C, D, E, F, G... Is the high-order aspheric coefficient.

In the five-element infrared single focus lens group of the first embodiment, the focal length of the five-element infrared single focus lens group is f, the f-number of the five-element infrared single focus lens group is Fno, and the five-element infrared single focus lens group is Fno. The maximum angle of view (angle of view) in the infrared single focus lens group is FOV, and its values are as follows: f=3.29 (mm); Fno=1.35; and FOV=79.5 (degrees).

In the five-piece infrared single focus lens group of the first embodiment, the distance from the object side surface 111 of the first lens 110 to the imaging surface 180 on the optical axis 190 is TL, and the entire five-piece infrared single focus lens group The focal length is f, the distance from the image side surface 152 of the fifth lens 150 to the imaging surface 180 on the optical axis 190 is BFL, and half of the imaging height that the five-piece infrared single focus lens group can capture on the imaging surface 180 is IMH, and meet the following conditions: TL×f/(BFL×IMH) = 4.18 mm.

In the five-piece infrared single-focus lens group of the first embodiment, the overall focal length of the five-piece infrared single-focus lens group is f, and the focal length of the first lens 110 is f1, and the following conditions are met: f/f1 = 0.65 .

In the five-piece infrared single focus lens group of the first embodiment, the overall focal length of the five-piece infrared single focus lens group is f, and the combined focal length of the second lens 120, the third lens 130 and the fourth lens 140 is f234 , And meet the following conditions: f/f234 = 0.44.

In the five-piece infrared single-focus 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, the third lens 130 and the fourth lens 140 is f234, and the following conditions are met : F1/f234 = 0.68.

In the five-piece infrared single-focus lens group of the first embodiment, the combined focal length of the first lens 110, the second lens 120, and the third lens 130 is f123, and the first lens 110, the second lens 120, and the third lens The combined focal length of 130 and the fourth lens 140 is f1234, and meets the following conditions: f123/f1234=1.36.

In the five-piece infrared single focus lens group of the first embodiment, the overall focal length of the five-piece infrared single focus lens group is f, the first lens 110, the second lens 120, the third lens 130, and the fourth lens 140 The composite focal length of is f1234, and meets the following conditions: f/f1234 = 0.82.

In the five-piece infrared single focus lens group of the first embodiment, the combined focal length of the third lens 130 and the fourth lens 140 is f34, and the combined focal length of the second lens 120, the third lens 130 and the fourth lens 140 is f234, and meet the following conditions: f34/f234 = 0.79.

In the five-piece infrared single-focus lens group of the first embodiment, the focal length of the first lens 110 is f1, and the radius of curvature of the object side surface 111 of the first lens 110 is R1, and the following conditions are met: f1/R1 = 1.41 .

In the five-piece infrared single-focal 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 meets the following conditions: R5/R6 = 0.63.

In the five-piece infrared single-focus lens group of the first embodiment, the radius of curvature of the fifth lens 150 on the object side surface 151 is R9, and the radius of curvature of the fifth lens 150 on the image side surface 152 is R10, and meet the following conditions: R9/R10 = 1.24.

In the five-piece infrared single focus lens group of the first embodiment, the focal length of the third lens 130 is f3, the curvature radius of the object side surface 131 of the third lens 130 is R5, and the curvature of the image side surface 132 of the third lens 130 The radius is R6 and meets the following conditions: f3/(R5×R6)=0.48.

In the five-piece infrared single focus lens group of the first embodiment, the distance from the object side surface 111 of the first lens 110 to the imaging surface 180 on the optical axis 190 is TL, and the distance between the second lens 120 on the optical axis 190 The thickness is CT2, the thickness of the third lens 130 on the optical axis 190 is CT3, the thickness of the fourth lens 140 on the optical axis 190 is CT4, and the following conditions are met: TL/(CT2+CT3+CT4)=3.63 .

In the five-piece infrared single focus lens group of the first embodiment, the distance from the object side surface 111 of the first lens 110 to the imaging surface 180 on the optical axis 190 is TL, and the entire five-piece infrared single focus lens group The focal length is f, and the following conditions are met: TL/f = 1.62.

In the five-piece infrared single-focal lens group of the first embodiment, the distance on the optical axis 190 from the image side surface 152 of the fifth lens 150 to the imaging surface 180 is BFL, and the object side surface 111 to the first lens 110 The distance between the imaging surface 180 and the optical axis 190 is TL, and the following condition is satisfied: BFL/TL=0.29.

In the five-piece infrared single focus lens group of the first embodiment, the distance from the object side surface 111 of the first lens 110 to the imaging surface 180 on the optical axis 190 is TL, and the five-piece infrared single focus lens group is Half of the imaging height that can be captured by the surface 180 is IMH, and the following conditions are met: TL/IMH = 1.96.

In the five-piece infrared single-focus lens group of the first embodiment, the overall focal length of the five-piece infrared single-focus lens group is f, the radius of curvature of the object side surface 151 of the fifth lens 150 is R9, and the fifth lens 150 has an image The radius of curvature of the side surface 152 is R10 and satisfies the following condition: (f×R10)/R9=2.66.

Refer to Table 1 and Table 2 below for cooperation.

Table 1 The first embodiment f( Focal length) = 3.29 mm (mm), Fno (aperture value) = 1.35, FOV (angle of view) = 79.5 deg. (degrees) surface To Radius of curvature thickness Material Refractive index Dispersion coefficient focal length 0 Subject unlimited 450.000 To To To To 1 Test surface unlimited 0.106 To To To To 2 aperture unlimited -0.106 To To To To 3 First lens 3.618 (ASP) 0.747 plastic 1.64 22.5 5.09 4 To -22.950 (ASP) 0.552 To 　 　 　 5 Second lens -2.373 (ASP) 0.300 plastic 1.54 55.9 -17.89 6 To -3.292 (ASP) 0.063 To 　 　 　 7 Third lens 5.394 (ASP) 0.395 plastic 1.64 22.5 22.16 8 To 8.622 (ASP) 0.320 To 　 　 　 9 Fourth lens -3.008 (ASP) 0.774 plastic 1.64 22.5 7.28 10 To -1.984 (ASP) 0.040 To 　 　 　 11 Fifth lens 1.254 (ASP) 0.600 plastic 1.64 22.5 -194.18 12 To 1.013 (ASP) 0.956 To To To To 13 Infrared filter Filter unlimited 0.210 grass 1.52 64.2 To 14 To unlimited 0.380 To To To To 15 Imaging surface unlimited unlimited To To To To

Table 2 Aspheric coefficient flat 3 4 5 6 7 K: -3.8761E+00 9.9551E+01 8.8893E-01 -6.7121E+00 -2.2335E+01 A: -1.5197E-02 -4.1595E-02 3.6398E-04 1.1728E-02 8.9454E-03 B: -4.7709E-03 -6.6425E-03 1.1317E-02 -1.7693E-03 -1.3477E-02 C: -9.8558E-04 -4.5394E-04 4.3976E-04 -1.1705E-03 2.0673E-03 D: -2.6413E-03 -2.2804E-04 5.2030E-04 -3.1205E-04 6.1771E-05 E: 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 F: 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 G: 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 flat 8 9 10 11 12 K: -9.9500E+01 -4.1269E+01 -1.0494E+00 -3.0829E+00 -2.4186E+00 A: -5.0679E-03 6.2255E-03 3.2038E-02 -2.5709E-02 -3.7516E-02 B: 1.4011E-03 8.0648E-03 -1.1180E-03 -2.5726E-03 5.0305E-03 C: -3.5895E-05 -6.6531E-04 2.6787E-04 -7.0564E-05 -5.6904E-04 D: 8.4071E-05 -4.0444E-05 2.6713E-04 8.7546E-05 1.6245E-05 E: 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 F: 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 G: 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

Table 1 shows the detailed structure data of the first embodiment in FIG. 1A. The units of the radius of curvature, thickness and focal length are mm, and the surface 0-15 indicates the surface from the object side to the image side in sequence, and also includes the test surface ( Namely surface 1). Table 2 is the aspheric surface data in the first embodiment, where k represents the conical surface coefficient in the aspheric curve equation, and A, B, C, D, E, F, G... are high-order aspheric surface coefficients. In addition, the following example tables correspond to the schematic diagrams and field curvature and distortion tolerance curves of the respective examples. The definitions of the data in the tables are the same as those in Table 1 and Table 2 of the first embodiment. Add more details.

>Second Embodiment>

Please refer to FIGS. 2A and 2B, where FIG. 2A shows a schematic diagram of a five-piece infrared single-focal lens group according to a second embodiment of the present invention, and FIG. 2B shows the five-piece infrared rays of the second embodiment in order from left to right. The curve of field curvature and distortion of the single-focal lens group. It can be seen from FIG. 2A that the five-piece infrared single-focus lens group includes an aperture 200 and an optical group. The optical group includes a first lens 210, a second lens 220, and a third lens 230 from the object side to the image side. The fourth lens 240, the fifth lens 250, and the infrared bandpass element 280, wherein there are five lenses with refractive power in the five-piece infrared single-focus lens group. The aperture 200 is arranged between the subject and the first lens 210.

The first lens 210 has a positive refractive power and is made of plastic material. Its object side surface 211 is convex near the optical axis 290, and its image side surface 212 is convex near the optical axis 290, and the object side surface 211 and the image side are convex. The surfaces 212 are all aspherical.

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

The third lens 230 has positive refractive power and is made of plastic material. Its object side surface 231 is convex near the optical axis 290, and its image side surface 232 is concave near the optical axis 290, and the object side surface 231 and the image side The surfaces 232 are all aspherical.

The fourth lens 240 has a positive refractive power and is made of plastic. Its object-side surface 241 is concave near the optical axis 290, and its image-side surface 242 is convex near the optical axis 290, and the object-side surface 241 and the image side are convex. The surfaces 242 are all aspherical.

The fifth lens 250 has negative refractive power and is made of plastic. Its object side surface 251 is convex near the optical axis 290, and its image side surface 252 is concave near the optical axis 290, and the object side surface 251 and the image side The surface 252 is both aspherical, and both the object side surface 251 and the image side surface 252 have at least one inflection point.

The infrared bandpass element 270 is made of glass, which is arranged between the fifth lens 250 and the imaging surface 280 and does not affect the focal length of the five-piece infrared single focus lens group.

Refer to Table 3 and Table 4 below for cooperation.

table 3 Second embodiment f( Focal length) = 3.47 mm (mm), Fno (aperture value) = 1.36, FOV (angle of view) = 78.1 deg. (degrees) surface To Radius of curvature thickness Material Refractive index Dispersion coefficient focal length 0 Subject unlimited 450.000 To To To To 1 Test surface unlimited 0.144 To To To To 2 aperture unlimited -0.144 To To To To 3 First lens 3.344 (ASP) 0.797 plastic 1.64 22.5 5.21 4 To -89.950 (ASP) 0.392 To 　 　 　 5 Second lens -7.117 (ASP) 0.300 plastic 1.54 55.9 -6.61 6 To 7.148 (ASP) 0.132 To 　 　 　 7 Third lens 2.473 (ASP) 0.459 plastic 1.64 22.5 4.95 8 To 11.721 (ASP) 0.436 To 　 　 　 9 Fourth lens -1.600 (ASP) 0.690 plastic 1.64 22.5 5.44 10 To -1.266 (ASP) 0.038 To 　 　 　 11 Fifth lens 2.690 (ASP) 0.989 plastic 1.64 22.5 -7.02 12 To 1.429 (ASP) 0.701 To To To To 13 Infrared filter Filter unlimited 0.210 grass 1.52 64.2 To 14 To unlimited 0.380 To To To To 15 Imaging surface unlimited unlimited To To To To

Table 4 Aspheric coefficient flat 3 4 5 6 7 K: -1.7465E+00 -9.9501E+01 1.1679E+01 -7.6471E+01 -1.1555E+01 A: -6.7407E-03 -2.5394E-02 -8.2647E-03 -4.3564E-02 1.4775E-02 B: -4.7366E-03 -1.9742E-02 -2.0024E-02 9.0299E-03 -2.3293E-02 C: -4.2646E-03 3.4795E-03 2.8658E-03 1.1171E-03 -6.7035E-04 D: -1.3777E-05 1.5008E-04 1.7261E-03 -1.7722E-03 -4.8026E-04 E: 9.7057E-04 -6.1968E-04 -3.8529E-04 -3.9714E-04 2.7142E-04 F: -6.9357E-04 1.3432E-04 -1.6099E-04 1.2285E-04 7.1364E-05 G: -1.2788E-05 -2.8350E-05 6.5207E-05 1.5911E-05 -1.1845E-05 flat 8 9 10 11 12 K: 3.6508E+01 -5.7097E+00 -1.8237E+00 -4.5120E+00 -5.3238E+00 A: 2.0413E-02 -2.1186E-02 1.7336E-02 -4.0658E-02 -1.9822E-02 B: -1.6035E-02 1.7193E-02 -1.2961E-02 4.9800E-03 2.5845E-03 C: -4.5752E-03 1.0231E-03 3.5999E-03 -9.6493E-04 -4.0534E-04 D: 1.3842E-03 -6.0333E-04 8.6793E-04 -2.3153E-05 2.5221E-05 E: 2.3322E-04 -8.8291E-06 4.2165E-05 2.0459E-05 -3.0343E-07 F: -9.1903E-05 6.9207E-07 -2.0160E-06 9.2609E-06 8.1478E-08 G: 4.5138E-06 -1.8379E-07 -7.6019E-06 -1.5527E-06 -1.6667E-08

In the second embodiment, the curve equation of the aspheric surface is expressed as in 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.

In conjunction with Table 3 and Table 4, the following data can be calculated:

Second embodiment f[mm] 3.47 R5/R6 0.21 Fno 1.36 R9/R10 1.88 FOV[deg.] 78.1 f3/(R5×R6) 0.17 f/f1 0.67 TL/(CT2+CT3+CT4) 3.81 f/f234 0.78 TL/f 1.59 f1/f234 1.17 BFL/TL 0.23 f123/f1234 1.29 TL/IMH 1.96 f/f1234 1.03 (f×R10)/R9 1.84 f34/f234 0.71 TL×f/(BFL×IMH)[mm] 5.26 f1/R1 1.56 To To

>Third Embodiment>

Please refer to FIGS. 3A and 3B, where FIG. 3A shows a schematic diagram of a five-piece infrared single-focal lens group according to a third embodiment of the present invention, and FIG. 3B shows the five-piece infrared rays of the third embodiment in order from left to right. The curve of field curvature and distortion of the single-focal lens group. It can be seen from FIG. 3A that the five-piece infrared single-focus lens group includes an aperture 300 and an optical group. The optical group includes a first lens 310, a second lens 320, a third lens 330, and an optical group from the object side to the image side. The fourth lens 340, the fifth lens 350, the infrared bandpass element 370, and the imaging surface 380, wherein there are five lenses with refractive power in the five-piece infrared single-focus lens group. The aperture 300 is arranged between the subject and the first lens 310.

The first lens 310 has positive refractive power and is made of plastic. Its object side surface 311 is convex near the optical axis 390, and its image side surface 312 is concave near the optical axis 390. The object side surface 311 and the image side The surfaces 312 are all aspherical.

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

The third lens 330 has positive refractive power and is made of plastic. Its object side surface 331 is convex near the optical axis 390, and its image side surface 332 is concave near the optical axis 390. The object side surface 331 and the image side The surfaces 332 are all aspherical.

The fourth lens 340 has positive refractive power and is made of plastic. Its object-side surface 341 is concave near the optical axis 390, and its image-side surface 342 is convex near the optical axis 390. The object-side surface 341 and the image side are convex. The surfaces 342 are all aspherical.

The fifth lens 350 has a negative refractive power and is made of plastic. Its object side surface 351 is convex near the optical axis 390, and its image side surface 352 is concave near the optical axis 390, and the object side surface 351 and the image side are concave. The surface 352 is aspherical, and both the object side surface 351 and the image side surface 352 have at least one inflection point.

The infrared bandpass element 370 is made of glass, which is arranged between the fifth lens 350 and the imaging surface 380 and does not affect the focal length of the five-piece infrared single focus lens group.

Refer to Table 5 and Table 6 below for cooperation.

table 5 The third embodiment f( Focal length) = 3.46 mm (mm), Fno (aperture value) = 1.30, FOV (angle of view) = 77.9 deg. (degrees) surface To Radius of curvature thickness Material Refractive index Dispersion coefficient focal length 0 Subject unlimited 450.000 To To To To 1 Test surface unlimited 0.116 To To To To 2 aperture unlimited -0.116 To To To To 3 First lens 3.676 (ASP) 0.846 plastic 1.64 22.5 7.82 4 To 13.772 (ASP) 0.379 To 　 　 　 5 Second lens -3.138 (ASP) 0.300 plastic 1.54 55.9 24.40 6 To -2.615 (ASP) 0.040 To 　 　 　 7 Third lens 1.761 (ASP) 0.328 plastic 1.64 22.5 24.04 8 To 1.854 (ASP) 0.688 To 　 　 　 9 Fourth lens -2.886 (ASP) 0.826 plastic 1.64 22.5 5.13 10 To -1.680 (ASP) 0.040 To 　 　 　 11 Fifth lens 2.040 (ASP) 0.766 plastic 1.64 22.5 -8.74 12 To 1.270 (ASP) 0.752 To To To To 13 Infrared filter Filter unlimited 0.210 grass 1.52 64.2 To 14 To unlimited 0.380 To To To To 15 Imaging surface unlimited unlimited To To To To

Table 6 Aspheric coefficient flat 3 4 5 6 7 K: -1.4240E+00 -9.9499E+01 5.3707E-01 -4.3323E+00 -3.2533E+00 A: -1.8097E-02 -4.2836E-02 5.0404E-02 3.6531E-02 1.8632E-02 B: -5.4399E-03 -9.9806E-03 -1.5116E-02 6.2514E-03 -1.8238E-02 C: 1.2890E-03 1.9557E-03 -1.5192E-03 -4.0923E-03 1.6746E-03 D: -1.8227E-03 -4.8997E-04 1.2752E-03 -1.2320E-03 2.9950E-04 E: 1.4636E-04 1.4959E-04 -6.4117E-05 3.3171E-04 -4.4488E-05 F: 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 G: 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 flat 8 9 10 11 12 K: -1.2151E+00 -2.1078E+01 -1.0553E+00 -6.3619E+00 -3.9987E+00 A: -1.2684E-02 1.4735E-02 4.1367E-02 -3.6844E-02 -3.2096E-02 B: -9.4976E-03 -2.1684E-03 -1.0876E-02 -1.2108E-03 5.1812E-03 C: 1.9926E-04 -1.7790E-04 3.7298E-04 1.0451E-03 -6.9256E-04 D: 4.6107E-04 4.5506E-04 8.1017E-04 -5.3296E-05 5.9663E-05 E: -6.4508E-05 -6.3438E-05 -4.0239E-05 -2.1562E-05 -4.1971E-06 F: 0.0000E+00 0.0000E+00 0.0000E+00 3.1795E-06 1.1058E-07 G: 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

In the third embodiment, the curve equation of the aspheric surface is expressed as in 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.

In conjunction with Table 5 and Table 6, the following data can be calculated:

The third embodiment f[mm] 3.46 R5/R6 0.95 Fno 1.30 R9/R10 1.61 FOV[deg.] 77.9 f3/(R5×R6) 7.36 f/f1 0.44 TL/(CT2+CT3+CT4) 3.82 f/f234 0.85 TL/f 1.60 f1/f234 1.91 BFL/TL 0.24 f123/f1234 1.41 TL/IMH 1.98 f/f1234 1.00 (f×R10)/R9 2.16 f34/f234 1.17 TL×f/(BFL×IMH)[mm] 5.12 f1/R1 2.13 To To

>Fourth Embodiment>

Please refer to FIGS. 4A and 4B, in which FIG. 4A shows a schematic diagram of a five-piece infrared monofocal lens set according to a fourth embodiment of the present invention, and FIG. 4B shows the five-piece infrared rays of the fourth embodiment in order from left to right. The curve of field curvature and distortion of the single-focal lens group. It can be seen from FIG. 4A that the five-piece infrared single-focus lens group includes an aperture 400 and an optical group. The optical group includes a first lens 410, a second lens 420, a third lens 430, and an optical group from the object side to the image side. The fourth lens 440, the fifth lens 450, the infrared bandpass element 470, and the imaging surface 480, wherein there are five lenses with refractive power in the five-piece infrared single-focus lens group. The aperture 400 is arranged between the subject and the first lens 410.

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

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

The third lens 430 has positive refractive power and is made of plastic. Its object-side surface 431 is convex near the optical axis 490, and its image-side surface 432 is concave near the optical axis 490. The object-side surface 431 and the image side are concave. The surfaces 432 are all aspherical.

The fourth lens 440 has positive refractive power and is made of plastic. Its object side surface 441 is concave near the optical axis 490, and its image side surface 442 is convex near the optical axis 490. The object side surface 441 and the image side are convex. The surfaces 442 are all aspherical.

The fifth lens 450 has a negative refractive power and is made of plastic. Its object-side surface 451 is convex near the optical axis 490, and its image-side surface 452 is concave near the optical axis 490. The object-side surface 451 and the image side are concave. The surface 452 is aspherical, and both the object side surface 451 and the image side surface 452 have at least one inflection point.

The infrared band-pass element 470 is made of glass, which is arranged between the fifth lens 450 and the imaging surface 480 and does not affect the focal length of the five-piece infrared single-focus lens group.

Refer to Table 7 and Table 8 below for cooperation.

Table 7 Fourth embodiment f( Focal length) = 3.49 mm (mm), Fno (aperture value) = 1.35, FOV (angle of view) = 78.4 deg. (degrees) surface To Radius of curvature thickness Material Refractive index Dispersion coefficient focal length 0 Subject unlimited 450.000 To To To To 1 Test surface unlimited 0.089 To To To To 2 aperture unlimited -0.089 To To To To 3 First lens 3.456 (ASP) 0.606 plastic 1.64 22.5 6.65 4 To 19.775 (ASP) 0.280 To 　 　 　 5 Second lens -2.487 (ASP) 0.300 plastic 1.54 55.9 -4.30 6 To 32.323 (ASP) 0.078 To 　 　 　 7 Third lens 1.455 (ASP) 0.782 plastic 1.64 22.5 3.25 8 To 4.124 (ASP) 0.684 To 　 　 　 9 Fourth lens -2.700 (ASP) 0.794 plastic 1.64 22.5 3.93 10 To -1.426 (ASP) 0.040 To 　 　 　 11 Fifth lens 2.459 (ASP) 0.735 plastic 1.64 22.5 -4.89 12 To 1.204 (ASP) 0.672 To To To To 13 Infrared filter Filter unlimited 0.210 grass 1.52 64.2 To 14 To unlimited 0.380 To To To To 15 Imaging surface unlimited unlimited To To To To

Table 8 Aspheric coefficient flat 3 4 5 6 7 K: -1.1239E+00 9.9506E+01 -3.5173E+01 -9.9500E+01 -7.7532E+00 A: -1.4759E-02 5.9384E-03 6.3925E-02 -5.8314E-02 2.1041E-02 B: -1.2541E-02 -4.2497E-02 -4.6611E-02 3.1146E-02 -2.6895E-02 C: -4.9242E-03 -2.2053E-03 1.1951E-02 1.4341E-03 3.1877E-03 D: 1.2745E-03 7.6266E-03 3.9823E-03 -3.2308E-03 3.0040E-04 E: -4.0121E-04 -1.5935E-03 -1.6057E-03 2.4851E-04 6.7923E-05 F: 4.5063E-06 -7.5708E-05 -1.1810E-04 1.4683E-06 1.4415E-06 G: 0.0000E+00 0.0000E+00 3.6751E-05 2.5941E-06 -2.9725E-06 flat 8 9 10 11 12 K: 3.5896E+00 -1.6152E+01 -1.4429E+00 -1.1819E+01 -4.5489E+00 A: 3.5519E-02 -1.2497E-04 3.6938E-02 -5.1645E-02 -4.5730E-02 B: -3.9759E-02 4.1040E-04 -1.9383E-02 -9.4339E-04 1.2199E-02 C: 7.6366E-03 4.8138E-03 4.4105E-03 5.1677E-03 -2.3520E-03 D: 1.9126E-04 -8.6029E-04 1.3812E-03 -1.6746E-03 2.4918E-04 E: -6.7900E-04 -2.7486E-04 -3.0715E-04 4.3698E-05 -1.9154E-05 F: 8.6173E-05 -2.6200E-05 -5.6341E-05 6.0251E-05 1.6367E-06 G: 9.4520E-06 2.0682E-05 1.4115E-05 -6.9068E-06 -8.9653E-08

In the fourth embodiment, the curve equation of the aspheric surface is expressed as in 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] 3.49 R5/R6 0.35 Fno 1.35 R9/R10 2.04 FOV[deg.] 78.4 f3/(R5×R6) 0.54 f/f1 0.52 TL/(CT2+CT3+CT4) 2.96 f/f234 1.01 TL/f 1.59 f1/f234 1.93 BFL/TL 0.23 f123/f1234 1.49 TL/IMH 1.97 f/f1234 1.12 (f×R10)/R9 1.71 f34/f234 0.74 TL×f/(BFL×IMH)[mm] 5.45 f1/R1 1.92 To To

>Fifth Embodiment>

Please refer to FIGS. 5A and 5B, where FIG. 5A shows a schematic diagram of a five-piece infrared monofocal lens set according to a fifth embodiment of the present invention, and FIG. 5B shows the five-piece infrared rays of the fifth embodiment in order from left to right. The curve of field curvature and distortion of the single-focal lens group. It can be seen from FIG. 5A that the five-piece infrared single-focal lens group includes an aperture 500 and an optical group. The optical group includes a first lens 510, a second lens 520, a third lens 530, and an optical group from the object side to the image side. The fourth lens 540, the fifth lens 550, the infrared bandpass element 570, and the imaging surface 580, wherein there are five lenses with refractive power in the five-piece infrared single-focus lens group. The aperture 500 is arranged between the subject and the first lens 510.

The first lens 510 has a positive refractive power and is made of plastic. Its object side surface 511 is convex near the optical axis 590, and its image side surface 512 is convex near the optical axis 590, and the object side surface 511 and the image side are convex. The surfaces 512 are all aspherical.

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

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

The fourth lens 540 has positive refractive power and is made of plastic. Its object-side surface 541 is concave near the optical axis 590, and its image-side surface 542 is convex near the optical axis 590, and the object-side surface 541 and the image side are convex. The surfaces 542 are all aspherical.

The fifth lens 550 has a negative refractive power and is made of plastic. Its object side surface 551 is convex near the optical axis 590, and its image side surface 552 is concave near the optical axis 590, and the object side surface 551 and the image side The surface 552 is aspherical, and both the object side surface 551 and the image side surface 552 have at least one inflection point.

The infrared bandpass element 570 is made of glass, which is arranged between the fifth lens 550 and the imaging surface 580 and does not affect the focal length of the five-piece infrared single-focus lens group.

Refer to Table 9 and Table 10 below for cooperation.

Table 9 Fifth embodiment f( Focal length) = 3.66 mm (mm), Fno (aperture value) = 1.30, FOV (angle of view) = 75.0 deg. (degrees) surface To Radius of curvature thickness Material Refractive index Dispersion coefficient focal length 0 Subject unlimited 700.000 To To To To 1 Test surface unlimited 0.128 To To To To 2 aperture unlimited -0.128 To To To To 3 First lens 3.435 (ASP) 0.780 plastic 1.64 22.5 5.02 4 To -30.513 (ASP) 0.888 To 　 　 　 5 Second lens -1.949 (ASP) 0.270 plastic 1.64 22.5 -3.86 6 To -10.961 (ASP) 0.041 To 　 　 　 7 Third lens 2.182 (ASP) 0.408 plastic 1.64 22.5 4.37 8 To 10.348 (ASP) 0.385 To 　 　 　 9 Fourth lens -3.527 (ASP) 0.636 plastic 1.64 22.5 6.62 10 To -2.030 (ASP) 0.041 To 　 　 　 11 Fifth lens 1.313 (ASP) 0.526 plastic 1.64 22.5 -23.13 12 To 1.018 (ASP) 1.014 To To To To 13 Infrared filter Filter unlimited 0.210 grass 1.52 64.2 To 14 To unlimited 0.380 To To To To 15 Imaging surface unlimited unlimited To To To To

Table 10 Aspheric coefficient flat 3 4 5 6 7 K: 8.4779E-04 -9.9112E+01 3.3908E-02 1.6316E+01 -8.7450E+00 A: -1.5679E-02 -2.7941E-02 2.0204E-02 -9.0216E-02 3.8575E-02 B: -5.8485E-03 -7.7659E-03 -5.8210E-03 2.7082E-02 -2.4350E-02 C: 3.7184E-04 4.4708E-04 1.3353E-02 3.7442E-03 -8.2405E-04 D: -3.2729E-03 -5.1717E-04 -1.2878E-03 -1.3640E-03 -1.7710E-04 E: 1.5527E-03 2.9663E-04 -9.6091E-04 -5.9090E-04 -2.4528E-04 F: -4.1439E-04 -9.3835E-05 2.1050E-04 1.3279E-04 1.1403E-04 G: 0.0000E+00 0.0000E+00 1.0418E-06 1.7223E-06 1.4614E-06 flat 8 9 10 11 12 K: 2.6517E+01 -3.9969E+01 -6.6225E+00 -9.0237E-01 -2.1223E+00 A: 7.4348E-02 4.8168E-03 -2.2674E-02 -1.2422E-01 -7.0341E-02 B: -3.8327E-02 -2.0925E-02 -1.8906E-03 3.7485E-03 8.5127E-03 C: -1.6492E-03 5.7335E-03 -3.1068E-03 2.6824E-03 -2.3237E-04 D: 1.6071E-03 3.7364E-04 1.9240E-03 -2.6873E-04 -1.0381E-04 E: -1.0220E-04 -1.9752E-05 7.2868E-06 -6.3197E-06 1.6529E-05 F: 4.8976E-06 -3.1431E-05 -4.5783E-05 1.1857E-06 -5.5989E-07 G: -5.4597E-07 -2.6351E-06 8.7747E-08 -7.2273E-09 -2.4047E-08

In the fifth embodiment, the aspherical curve equation is expressed as in 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] 3.66 R5/R6 0.21 Fno 1.30 R9/R10 1.29 FOV[deg.] 75.0 f3/(R5×R6) 0.19 f/f1 0.73 TL/(CT2+CT3+CT4) 4.24 f/f234 0.52 TL/f 1.52 f1/f234 0.72 BFL/TL 0.29 f123/f1234 1.41 TL/IMH 1.98 f/f1234 0.91 (f×R10)/R9 2.84 f34/f234 0.44 TL×f/(BFL×IMH)[mm] 4.52 f1/R1 1.46 To To

>Sixth Embodiment>

Please refer to FIGS. 6A and 6B, in which FIG. 6A shows a schematic diagram of a five-piece infrared single-focal lens set according to a sixth embodiment of the present invention, and FIG. 6B shows the five-piece infrared rays of the sixth embodiment in order from left to right. The curve of field curvature and distortion of the single-focal lens group. It can be seen from FIG. 6A that the five-piece infrared single-focal lens group includes an aperture 600 and an optical group. The optical group includes a first lens 610, a second lens 620, and a third lens 630, from the object side to the image side. The fourth lens 640, the fifth lens 650, the infrared bandpass element 670, and the imaging surface 680, wherein there are five lenses with refractive power in the five-piece infrared single-focus lens group. The aperture 600 is arranged between the subject and the first lens 610.

The first lens 610 has positive refractive power and is made of plastic. Its object side surface 611 is convex near the optical axis 690, and its image side surface 612 is concave near the optical axis 690, and the object side surface 611 and the image side are concave. The surfaces 612 are all aspherical.

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

The third lens 630 has a negative refractive power and is made of plastic. Its object-side surface 631 is convex near the optical axis 690, and its image-side surface 632 is concave near the optical axis 690. The object-side surface 631 and the image side The surfaces 632 are all aspherical.

The fourth lens 640 has positive refractive power and is made of plastic. Its object-side surface 641 is concave near the optical axis 690, and its image-side surface 642 is convex near the optical axis 690, and the object-side surface 641 and the image side are convex. The surfaces 642 are all aspherical.

The fifth lens 650 has negative refractive power and is made of plastic. Its object-side surface 651 is convex near the optical axis 690, and its image-side surface 652 is concave near the optical axis 690. The object-side surface 651 and the image side The surface 652 is both aspherical, and both the object side surface 651 and the image side surface 652 have at least one inflection point.

The infrared bandpass element 670 is made of glass, which is arranged between the fifth lens 650 and the imaging surface 680 and does not affect the focal length of the five-piece infrared single focus lens group.

Refer to Table 11 and Table 12 below for cooperation.

Table 11 Sixth embodiment f( Focal length) = 3.52 mm (mm), Fno (aperture value) = 1.50, FOV (angle of view) = 75.9 deg. (degrees) surface To Radius of curvature thickness Material Refractive index Dispersion coefficient focal length 0 Subject unlimited 700.000 To To To To 1 Test surface unlimited 0.215 To To To To 2 aperture unlimited -0.215 To To To To 3 First lens 2.091 (ASP) 0.481 plastic 1.64 22.5 11.84 4 To 2.666 (ASP) 0.214 To 　 　 　 5 Second lens 2.109 (ASP) 0.423 plastic 1.64 22.5 7.43 6 To 3.586 (ASP) 0.517 To 　 　 　 7 Third lens 21.827 (ASP) 0.257 plastic 1.64 22.5 -45.46 8 To 12.254 (ASP) 0.411 To 　 　 　 9 Fourth lens -6.925 (ASP) 0.818 plastic 1.64 22.5 2.42 10 To -1.290 (ASP) 0.039 To 　 　 　 11 Fifth lens 2.526 (ASP) 0.513 plastic 1.64 22.5 -2.64 12 To 0.917 (ASP) 0.550 To To To To 13 Infrared filter Filter unlimited 0.300 grass 1.52 64.2 To 14 To unlimited 0.438 To To To To 15 Imaging surface unlimited unlimited To To To To

Table 12 Aspheric coefficient flat 3 4 5 6 7 K: -9.1814E-01 -2.2353E+00 -2.1588E+00 4.8624E+00 -9.9500E+01 A: -1.0277E-02 -6.8189E-02 -4.1620E-02 -3.2643E-02 -9.3839E-02 B: 8.7351E-04 2.1407E-02 1.0436E-02 -1.2333E-02 -4.0670E-02 C: 6.8434E-03 -5.7646E-02 -7.4457E-02 -5.1399E-02 5.0771E-02 D: -3.6604E-02 6.1410E-02 8.3619E-02 4.9673E-02 -4.3345E-02 E: 4.8303E-02 -4.0761E-02 -6.4360E-02 -3.1681E-02 3.0565E-02 F: -3.1225E-02 1.1865E-02 2.7334E-02 1.0075E-02 -9.8422E-03 G: 7.3613E-03 -5.4318E-04 -4.1815E-03 -1.0913E-03 1.3794E-03 flat 8 9 10 11 12 K: 8.0975E+01 -7.9731E+01 -1.2575E+00 -3.9217E+01 -5.3979E+00 A: -8.1372E-02 2.0949E-02 1.7246E-01 -7.3843E-03 -4.3302E-02 B: -1.4411E-02 -1.1331E-02 -1.0141E-01 -4.6312E-02 4.4479E-03 C: -3.0850E-02 -3.5462E-02 6.2355E-03 2.0721E-02 1.0898E-03 D: 4.8789E-02 1.2047E-02 2.7648E-02 -2.1322E-03 -6.9796E-04 E: -2.3933E-02 3.2829E-03 -2.1207E-02 -4.3114E-04 1.5414E-04 F: 5.6552E-03 -4.6328E-03 6.8417E-03 1.1231E-04 -1.5519E-05 G: 0.0000E+00 1.2606E-03 -8.0552E-04 -7.0619E-06 5.7065E-07

In the sixth embodiment, the curve equation of the aspheric surface is expressed as in 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] 3.52 R5/R6 1.78 Fno 1.50 R9/R10 2.75 FOV[deg.] 75.9 f3/(R5×R6) -0.17 f/f1 0.30 TL/(CT2+CT3+CT4) 3.31 f/f234 1.45 TL/f 1.41 f1/f234 4.87 BFL/TL 0.26 f123/f1234 1.99 TL/IMH 1.76 f/f1234 1.36 (f×R10)/R9 1.28 f34/f234 1.03 TL×f/(BFL×IMH)[mm] 4.81 f1/R1 5.66 To To

>Seventh embodiment>

Please refer to FIGS. 7A and 7B, in which FIG. 7A shows a schematic diagram of a five-piece infrared monofocal lens set according to a seventh embodiment of the present invention, and FIG. 7B shows the five-piece infrared rays of the seventh embodiment in order from left to right. The curve of field curvature and distortion of the single-focal lens group. It can be seen from FIG. 7A that the five-piece infrared single-focal lens group includes an aperture 700 and an optical group. The optical group includes a first lens 710, a second lens 720, a third lens 730, and an optical group from the object side to the image side. The fourth lens 740, the fifth lens 750, the infrared bandpass element 770, and the imaging surface 780, wherein there are five lenses with refractive power in the five-piece infrared single-focus lens group. The aperture 700 is arranged between the subject and the first lens 710.

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

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

The third lens 730 has positive refractive power and is made of plastic. Its object side surface 731 is convex near the optical axis 790, and its image side surface 732 is concave near the optical axis 790. The object side surface 731 and the image side are concave. The surfaces 732 are all aspherical.

The fourth lens 740 has positive refractive power and is made of plastic. Its object-side surface 741 is concave near the optical axis 790, and its image-side surface 742 is convex near the optical axis 790. The object-side surface 741 and the image side are convex. The surfaces 742 are all aspherical.

The fifth lens 750 has negative refractive power and is made of plastic. Its object-side surface 751 is convex near the optical axis 790, and its image-side surface 752 is concave near the optical axis 790. The object-side surface 751 and the image side are concave. The surface 752 is aspherical, and both the object-side surface 751 and the image-side surface 752 have at least one inflection point.

The infrared band-pass element 770 is made of glass, which is arranged between the fifth lens 750 and the imaging surface 780 and does not affect the focal length of the five-piece infrared single-focus lens group.

Refer to Table 13 and Table 14 below for cooperation.

Table 13 Seventh embodiment f( Focal length) = 3.84 mm (mm), Fno (aperture value) = 1.60, FOV (angle of view) = 72.2 deg. (degrees) surface To Radius of curvature thickness Material Refractive index Dispersion coefficient focal length 0 Subject unlimited 700.000 To To To To 1 Test surface unlimited 0.332 To To To To 2 aperture unlimited -0.332 To To To To 3 First lens 2.064 (ASP) 0.523 plastic 1.64 22.5 7.99 4 To 3.189 (ASP) 0.366 To 　 　 　 5 Second lens 1.451 (ASP) 0.281 plastic 1.64 22.5 15.32 6 To 1.586 (ASP) 0.629 To 　 　 　 7 Third lens 4.123 (ASP) 0.264 plastic 1.64 22.5 129.77 8 To 4.239 (ASP) 0.384 To 　 　 　 9 Fourth lens -40.490 (ASP) 0.839 plastic 1.64 22.5 2.43 10 To -1.469 (ASP) 0.040 To 　 　 　 11 Fifth lens 7.636 (ASP) 0.526 plastic 1.64 22.5 -2.38 12 To 1.205 (ASP) 0.532 To To To To 13 Infrared filter Filter unlimited 0.300 grass 1.52 64.2 To 14 To unlimited 0.380 To To To To 15 Imaging surface unlimited unlimited To To To To

Table 14 Aspheric coefficient flat 3 4 5 6 7 K: -3.2384E-01 5.8723E-01 -1.3752E+00 -1.8407E+00 -7.3426E+00 A: -6.5771E-03 -5.1724E-02 -2.3280E-02 3.6860E-02 -6.1454E-02 B: 6.3127E-03 -5.5157E-03 1.7216E-02 -5.9313E-02 -6.7092E-02 C: -1.5074E-02 2.2325E-02 -1.5310E-01 1.2215E-02 1.3871E-01 D: 1.4754E-02 -3.8367E-02 2.0101E-01 -5.1693E-02 -1.3520E-01 E: -1.2415E-02 3.0065E-02 -1.5128E-01 6.5125E-02 6.1664E-02 F: 5.6757E-03 -1.3478E-02 5.8913E-02 -3.3808E-02 -1.1555E-02 G: -1.2667E-03 2.5587E-03 -8.5937E-03 6.4760E-03 -5.0950E-05 flat 8 9 10 11 12 K: 7.7040E-01 -9.9500E+01 -3.6530E+00 -8.9330E+00 -7.0089E+00 A: -8.2900E-02 7.4215E-02 1.6583E-01 -1.5361E-01 -1.1209E-01 B: 4.7789E-03 -7.0569E-02 -2.5867E-01 1.0250E-02 4.1727E-02 C: -3.6811E-02 9.1412E-02 2.5817E-01 2.6850E-02 -1.3295E-02 D: 4.4129E-02 -1.2868E-01 -1.4090E-01 -1.0665E-02 2.5672E-03 E: -2.8914E-02 1.0037E-01 4.0717E-02 1.8101E-03 -2.4394E-04 F: 7.3425E-03 -4.1643E-02 -5.9083E-03 -1.4916E-04 9.1791E-06 G: 1.3304E-04 6.7006E-03 3.3965E-04 4.8848E-06 -3.4468E-08

In the seventh embodiment, the curve equation of the aspheric surface is expressed as in 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.

In conjunction with Table 13 and Table 14, the following data can be calculated:

Seventh embodiment f[mm] 3.84 R5/R6 0.97 Fno 1.60 R9/R10 6.34 FOV[deg.] 72.2 f3/(R5×R6) 7.43 f/f1 0.48 TL/(CT2+CT3+CT4) 3.66 f/f234 1.52 TL/f 1.32 f1/f234 3.17 BFL/TL 0.24 f123/f1234 1.87 TL/IMH 1.80 f/f1234 1.43 (f×R10)/R9 0.61 f34/f234 0.98 TL×f/(BFL×IMH)[mm] 5.69 f1/R1 3.87 To To

>Eighth Embodiment>

Please refer to FIGS. 8A and 8B, in which FIG. 8A shows a schematic diagram of a five-piece infrared single-focal lens group according to an eighth embodiment of the present invention, and FIG. 8B shows the five-piece infrared ray according to the eighth embodiment in order from left to right. The curve of field curvature and distortion of the single-focal lens group. It can be seen from FIG. 8A that the five-piece infrared single-focus lens group includes an aperture 800 and an optical group. The optical group includes a first lens 810, a second lens 820, and a third lens 830, from the object side to the image side. The fourth lens 840, the fifth lens 850, the infrared bandpass element 870, and the imaging surface 880, wherein there are five lenses with refractive power in the five-piece infrared single-focus lens group. The aperture 800 is arranged between the subject and the first lens 810.

The first lens 810 has positive refractive power and is made of plastic. Its object-side surface 811 is convex near the optical axis 890, and its image-side surface 812 is concave near the optical axis 890, and the object-side surface 811 and the image side are concave. The surfaces 812 are all aspherical.

The second lens 820 has positive refractive power and is made of plastic. Its object-side surface 821 is concave near the optical axis 890, and its image-side surface 822 is convex near the optical axis 890, and the object-side surface 821 and the image side are convex. The surfaces 822 are all aspherical.

The third lens 830 has positive refractive power and is made of plastic. Its object-side surface 831 is concave near the optical axis 890, and its image-side surface 832 is convex near the optical axis 890, and the object-side surface 831 and the image side are convex. The surfaces 832 are all aspherical.

The fourth lens 840 has positive refractive power and is made of plastic. Its object-side surface 841 is concave near the optical axis 890, and its image-side surface 842 is convex near the optical axis 890, and the object-side surface 841 and the image side are convex. The surfaces 842 are all aspherical.

The fifth lens 850 has negative refractive power and is made of plastic. Its object-side surface 851 is convex near the optical axis 890, and its image-side surface 852 is concave near the optical axis 890, and the object-side surface 851 and the image side are concave. The surface 852 is aspherical, and both the object-side surface 851 and the image-side surface 852 have at least one inflection point.

The infrared bandpass element 870 is made of glass, which is arranged between the fifth lens 850 and the imaging surface 880 and does not affect the focal length of the five-piece infrared single focus lens group.

Refer to Table 15 and Table 16 below for cooperation.

Table 15 Eighth embodiment f( Focal length) = 3.75 mm (mm), Fno (aperture value) = 1.60, FOV (angle of view) = 72.7 deg. (degrees) surface To Radius of curvature thickness Material Refractive index Dispersion coefficient focal length 0 Subject unlimited 700.000 To To To To 1 Test surface unlimited 0.446 To To To To 2 aperture unlimited -0.446 To To To To 3 First lens 1.787 (ASP) 0.567 plastic 1.64 22.5 4.36 4 To 4.613 (ASP) 0.847 To 　 　 　 5 Second lens -8.743 (ASP) 0.231 plastic 1.64 22.5 3013.81 6 To -8.790 (ASP) 0.373 To 　 　 　 7 Third lens -0.990 (ASP) 0.286 plastic 1.64 22.5 17.46 8 To -1.007 (ASP) 0.039 To 　 　 　 9 Fourth lens -47.405 (ASP) 0.462 plastic 1.64 22.5 122.43 10 To -29.308 (ASP) 0.129 To 　 　 　 11 Fifth lens 2.282 (ASP) 0.722 plastic 1.64 22.5 -71.95 12 To 1.908 (ASP) 0.512 To To To To 13 Infrared filter Filter unlimited 0.300 grass 1.52 64.2 To 14 To unlimited 0.541 To To To To 15 Imaging surface unlimited unlimited To To To To

Table 16 Aspheric coefficient flat 3 4 5 6 7 K: -1.1261E+00 -5.7947E+00 5.7819E+01 -8.7500E+00 -5.7068E-01 A: 1.8399E-02 2.5061E-02 -8.7901E-02 -6.9694E-02 1.1371E-01 B: 4.5032E-02 -5.8355E-02 -9.3566E-02 -7.8550E-02 2.2487E-02 C: -6.1750E-02 1.3164E-01 3.3665E-02 -9.5906E-03 -5.2779E-02 D: 6.2480E-02 -1.2732E-01 3.7387E-02 5.3697E-02 4.2102E-02 E: -4.1103E-02 3.1195E-02 -5.7061E-02 -3.4302E-02 2.3338E-03 F: 1.9422E-02 2.3701E-02 -3.6935E-04 -1.2582E-03 4.6538E-03 G: -4.8658E-03 -1.2685E-02 2.3667E-02 1.1469E-02 -4.1702E-03 flat 8 9 10 11 12 K: -1.0614E+00 9.6431E+01 -6.5600E+02 -2.4985E+00 -4.1187E+00 A: 9.2908E-02 1.1514E-01 4.5688E-02 -5.5154E-02 -5.4146E-02 B: -5.3734E-02 -8.2217E-02 -3.6577E-02 -3.4163E-02 7.0780E-04 C: 2.8583E-02 1.7569E-02 1.0280E-02 2.3788E-02 1.6531E-03 D: 1.4540E-03 1.4486E-03 -2.2718E-03 -5.7414E-03 -2.6266E-04 E: 1.3495E-03 -1.3167E-03 1.0180E-04 6.7611E-04 2.6718E-05 F: -2.7847E-04 -4.0327E-04 3.8958E-05 -3.7638E-05 -4.1700E-06 G: -2.6293E-04 1.6209E-04 -2.0166E-06 7.2970E-07 3.0692E-07

In the eighth embodiment, the aspherical curve equation is expressed as in 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.

In conjunction with Table 15 and Table 16, the following data can be calculated:

Eighth embodiment f[mm] 3.75 R5/R6 0.98 Fno 1.60 R9/R10 1.20 FOV[deg.] 72.7 f3/(R5×R6) 17.52 f/f1 0.86 TL/(CT2+CT3+CT4) 5.12 f/f234 0.25 TL/f 1.33 f1/f234 0.29 BFL/TL 0.27 f123/f1234 1.01 TL/IMH 1.78 f/f1234 0.90 (f×R10)/R9 3.14 f34/f234 1.01 TL×f/(BFL×IMH)[mm] 4.93 f1/R1 2.44 To To

In the five-piece infrared single-focus lens group provided by the present invention, the lens material can be plastic or glass. When the lens material is plastic, the production cost can be effectively reduced. In addition, when the lens material is glass, a five-piece infrared lens can be added. The degree of freedom in the configuration of the refractive power of the focal lens group. In addition, the object side surface and the image side surface of the lens in the five-element infrared single focus lens group can be aspherical, and the aspherical surface can be easily made into a shape other than a spherical surface to obtain more control variables to reduce aberrations, and then The number of lenses used is reduced, so the total length of the five-piece infrared single-focus lens set of the present invention can be effectively reduced.

In the five-piece infrared single-focus lens set provided by the present invention, for a lens with 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 five-piece infrared single-focal lens set provided by the present invention can be applied to a mobile focusing optical system 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 many ways. , Digital cameras, mobile devices, digital tablets or car photography and other electronic imaging systems.

100, 200, 300, 400, 500, 600, 700, 800: aperture 110, 210, 310, 410, 510, 610, 710, 810: first lens 111, 211, 311, 411, 511, 611, 711, 811: Object side surface 112, 212, 312, 412, 512, 612, 712, 812: image side surface 120, 220, 320, 420, 520, 620, 720, 820: second lens 121, 221, 321, 421, 521, 621, 721, 821: Object side surface 122, 222, 322, 422, 522, 622, 722, 822: image side surface 130, 230, 330, 430, 530, 630, 730, 830: third lens 131, 231, 331, 431, 531, 631, 731, 831: Object side surface 132, 232, 332, 432, 532, 632, 732, 832: image side surface 140, 240, 340, 440, 540, 640, 740, 840: fourth lens 141, 241, 341, 441, 541, 641, 741, 841: Object side surface 142, 242, 342, 442, 542, 642, 742, 842: image side surface 150, 250, 350, 450, 550, 650, 750, 850: fifth lens 151, 251, 351, 451, 551, 651, 751, 851: Object side surface 152, 252, 352, 452, 552, 652, 752, 852: image side surface 160, 260, 360, 470, 570, 670, 770, 870: infrared bandpass components 180, 280, 380, 480, 580, 680, 780, 880: imaging surface 190, 290, 390, 490, 590, 690, 790, 890: optical axis f: Focal length of five-piece infrared single focus lens group Fno: The aperture value of the five-piece infrared single focus lens group FOV: The largest field of view in the five-piece infrared single focus lens group f1: focal length of the first lens f3: focal length of the third lens f5: the focal length of the fifth lens f234: The combined focal length of the second lens, the third lens and the fourth lens f123: The combined focal length of the first lens, the second lens and the third lens f34: The combined focal length of the third lens and the fourth lens f1234: The combined focal length of the first lens, the second lens, the third lens and the fourth lens R1: The radius of curvature of the object side surface of the first lens R5: The radius of curvature of the object side surface of the third lens R6: The radius of curvature of the image side surface of the third lens R9: The radius of curvature of the object side surface of the fifth lens R10: The radius of curvature of the image side surface of the fifth lens CT2: The thickness of the second lens on the optical axis CT3: The thickness of the third lens on the optical axis CT4: The thickness of the fourth lens on the optical axis TL: The distance from the object side surface of the first lens to the imaging surface on the optical axis IMH: Five-element infrared single-focal lens group can capture half of the imaging height on the imaging surface BFL: The distance from the image side surface of the fifth lens to the imaging surface on the optical axis

FIG. 1A is a schematic diagram of a five-piece infrared monofocal lens group according to the first embodiment of the present invention. Fig. 1B is a graph showing the curvature of field and the distortion of the five-piece infrared single-focal lens group in the first embodiment, from left to right. 2A is a schematic diagram of a five-piece infrared monofocal lens group according to the second embodiment of the present invention. FIG. 2B is a graph showing the curvature of field and the distortion of the five-piece infrared single-focal lens group in the second embodiment, from left to right. 3A is a schematic diagram of a five-piece infrared monofocal lens group according to the third embodiment of the present invention. FIG. 3B is a graph showing the curvature of field and the distortion of the five-piece infrared single-focal lens group of the third embodiment in order from left to right. 4A is a schematic diagram of a five-piece infrared monofocal lens group according to the fourth embodiment of the present invention. Fig. 4B is a graph showing the curvature of field and the distortion of the five-piece infrared single-focus lens group of the fourth embodiment in order from left to right. 5A is a schematic diagram of a five-piece infrared monofocal lens group according to the fifth embodiment of the present invention. FIG. 5B is a graph showing the curvature of field and the distortion of the five-piece infrared single-focal lens group of the fifth embodiment in order from left to right. 6A is a schematic diagram of a five-piece infrared monofocal lens group according to the sixth embodiment of the present invention. Fig. 6B is a graph showing the curvature of field and the distortion of the five-piece infrared single-focal lens group of the sixth embodiment in sequence from left to right. Fig. 7A is a schematic diagram of a five-piece infrared monofocal lens group according to a seventh embodiment of the present invention. FIG. 7B is a graph showing the curvature of field and the distortion of the five-piece infrared single-focus lens group of the seventh embodiment in order from left to right. FIG. 8A is a schematic diagram of a five-piece infrared monofocal lens group according to the eighth embodiment of the present invention. FIG. 8B is a graph showing the curvature of field and the distortion of the five-piece infrared single-focus lens group of the eighth embodiment in order from left to right.

100: Aperture

110: first lens

111: Object side surface

112: Image side surface

120: second lens

121: Object side surface

122: image side surface

130: third lens

131: Object side surface

132: Image side surface

140: fourth lens

141: Object side surface

142: Image side surface

150: Fifth lens

151: Object side surface

152: image side surface

170: Infrared band pass element

180: imaging surface

190: optical axis

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

IMH: Five-element infrared single-focal lens group can capture half of the imaging height on the imaging surface

BFL: The distance from the image side surface of the fifth lens to the imaging surface on the optical axis

Claims (16)

A five-piece infrared single-focal lens group, including an aperture and an optical group composed of five lenses, from the object side to the image side as follows: The aperture A first lens with positive refractive power, the object side surface of the first lens is convex near the optical axis, and at least one of the object side surface and the image side surface of the first lens is aspherical; A second lens having refractive power, and at least one of the object side surface and the image side surface of the second lens is aspherical; A third lens having refractive power, and at least one of the object side surface and the image side surface of the third lens is aspherical; A fourth lens with positive refractive power. The object side surface of the fourth lens is concave near the optical axis, and the image side surface of the fourth lens is convex near the optical axis. At least one of the side surfaces is aspherical; and A fifth lens with negative refractive power. The object side surface of the fifth lens is convex near the optical axis, and the image side surface of the fifth lens is concave near the optical axis. At least one surface of the side surface is an aspheric surface, and at least one surface of the object side surface and the image side surface of the fifth lens has at least one inflection point; The distance from the object side surface of the first lens to the imaging surface on the optical axis is TL, the overall focal length of the five-piece infrared single focus lens group is f, and the image side surface of the fifth lens to the imaging surface is on the optical axis The distance above is BFL. Half of the imaging height that the five-piece infrared single focus lens group can capture on the imaging surface is IMH, and meets the following conditions: 3mm> TL×f/(BFL×IMH)> 7mm. The five-piece infrared single-focus lens group according to claim 1, wherein the overall focal length of the five-piece infrared single-focus lens group is f, the focal length of the first lens is f1, and the following conditions are met: 0.23> f/ f1> 1.04. The five-piece infrared single focus lens group according to claim 1, wherein the overall focal length of the five-piece infrared single focus lens group is f, and the combined focal length of the second lens, the third lens and the fourth lens is f234, And meet the following conditions: 0.20> f/f234> 1.83. The five-piece infrared single-focus lens group according to claim 1, wherein the focal length of the first lens is f1, the combined focal length of the second lens, the third lens and the fourth lens is f234, and the following conditions are met: 0.23 > f1/f234> 5.85. The five-piece infrared single-focus lens group according to claim 1, wherein the combined focal length of the first lens, the second lens and the third lens is f123, and the first lens, the second lens, the third lens and the fourth lens have a combined focal length of f123. The composite focal length of the lens is f1234 and meets the following conditions: 0.8> f123/f1234> 2.4. The five-piece infrared single-focus lens group according to claim 1, wherein the overall focal length of the five-piece infrared single-focus lens group is f, the combination of the first lens, the second lens, the third lens and the fourth lens The focal length is f1234, and the following conditions are met: 0.65> f/f1234> 1.72. The five-piece infrared single focus lens group according to claim 1, wherein the composite focal length of the three lenses and the fourth lens is f34, and the composite focal length of the second lens, the third lens and the fourth lens is f234, and satisfies The following conditions: 0.34> f34/f234> 1.40. The five-piece infrared single-focus lens group according to claim 1, wherein the focal length of the first lens is f1, the radius of curvature of the object side surface of the first lens is R1, and the following conditions are met: 1.1> f1/R1> 6.8. The five-piece infrared single-focal lens group according to claim 1, wherein the radius of curvature of the image side surface of the third lens is R6, and the radius of curvature of the object side surface of the third lens is R5, and the following conditions are met: 0.16> R5/R6> 2.14. The five-piece infrared single-focal lens group according to claim 1, wherein the radius of curvature of the object side surface of the fifth lens is R9, and the radius of curvature of the image side surface of the fifth lens is R10, and the following conditions are satisfied: 0.95> R9/R10> 7.61. The five-piece infrared single-focus lens group according to claim 1, wherein the focal length of the third lens is f3, the radius of curvature of the object side surface of the third lens is R5, and the radius of curvature of the image side surface of the third lens is R6 , And meet the following conditions: -0.2> f3/(R5×R6)> 21.1. The five-piece infrared single-focus lens group according to claim 1, wherein the distance from the object side surface of the first lens to the imaging surface on the optical axis is TL, and the thickness of the second lens on the optical axis is CT2, The thickness of the third lens on the optical axis is CT3, and the thickness of the fourth lens on the optical axis is CT4, and the following conditions are met: 2.3> TL/(CT2+CT3+CT4)> 6.2. The five-piece infrared single-focus lens group according to claim 1, wherein the distance from the object side surface of the first lens to the imaging surface on the optical axis is TL, and the overall focal length of the five-piece infrared single-focus lens group is f, and meet the following conditions: 1.0> TL/f> 2.0. The five-piece infrared single-focal lens group according to claim 1, wherein the distance from the image side surface of the fifth lens to the imaging surface on the optical axis is BFL, and the object side surface of the first lens to the imaging surface is in the optical axis. The distance on the axis is TL and meets the following conditions: 0.18> BFL/TL> 0.35. The five-piece infrared single-focus lens group according to claim 1, wherein the distance from the object side surface of the first lens to the imaging surface on the optical axis is TL, and the five-piece infrared single-focus lens group can be on the imaging surface. Half of the captured imaging height is IMH, and the following conditions are met: 1.4> TL/IMH> 2.4. The five-piece infrared single focus lens group according to claim 1, wherein the overall focal length of the five-piece infrared single focus lens group is f, the radius of curvature of the object side surface of the fifth lens is R9, and the fifth lens image The radius of curvature of the side surface is R10 and meets the following conditions: 0.48> (f×R10)/R9> 3.77.

Images