TW202001325A - Four-piece infrared single wavelength lens system - Google Patents

Abstract

A four-piece infrared single wavelength lens system includes, in order from the object side to the image side: a stop, a first lens element with a refractive power having an object-side surface being convex near an optical axis, a second lens element with a positive refractive power, a third lens element with a positive refractive power having an object-side surface being concave near the optical axis and an image-side surface being convex near the optical axis, and a fourth lens element with a negative refractive power having an object-side surface being convex near the optical axis and an image-side surface being concave near the optical axis, such arrangements can provide a four-piece infrared single wavelength lens system which has a wide field of view, large stop, short length and less distortion.

Description

Four piece infrared single wavelength lens group

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

Today's digital imaging technology is constantly innovating and changing, especially digital carriers such as digital cameras and mobile phones are moving towards miniaturization, so that photosensitive elements such as CCD or CMOS are also required to be more compact. In addition to the application of infrared focusing lenses, In the field of photography, in recent years, it has also been widely used in the field of infrared reception and sensing of game consoles. In order to make the range of the game consoles to sense users wider, most of the lens sets that receive infrared wavelengths at present have a larger angle of view. The wide-angle lens group is the mainstream.

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

In addition, the infrared lens receiving and sensing lens sets dedicated to game consoles use plastic lenses in pursuit of low cost. First, the poor transparency of the material is one of the key factors affecting the depth detection accuracy of the game console. 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 accurate focus detection cannot be achieved. As mentioned above, the current infrared wavelength receiving lens group cannot meet the two major technical issues of accurate 3D game depth distance sensing.

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

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

The reason is that, in order to achieve the foregoing objective, a four-piece infrared single-wavelength lens group provided by the present invention includes, in order from the object side to the image side, an aperture; a first lens with refractive power, and its object-side surface Near the optical axis is a convex surface, at least one of its object-side surface and image-side surface is aspheric; a second lens with positive refractive power, at least one of its object-side surface and image-side surface is aspheric; a third The lens has a positive refractive power, its object side surface is concave near the optical axis, its image side surface is convex near the optical axis, and at least one of its object side surface and image side surface is aspheric; and a fourth lens, It has negative refractive power, its object-side surface is convex near the optical axis, its image-side surface is concave near the optical axis, and at least one of its object-side surface and image-side surface is aspherical.

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: -45 <f1/f2 <10. In this way, the configuration of the refractive power of the first lens and the second lens is more suitable, which can help to obtain a wide angle of view (field angle) and reduce the excessive increase of the system aberration.

Preferably, the focal length of the second lens is f2, and the focal length of the third lens is f3, and the following condition is satisfied: 0.3 <f2/f3 <18. In this way, the peripheral resolution and illuminance of the system can be improved.

Preferably, the focal length of the third lens is f3, and the focal length of the fourth lens is f4, and the following conditions are satisfied: -1.7 <f3/f4 <-0.1. In this way, the system's bending force configuration can be effectively balanced, which helps to reduce sensitivity and improve manufacturing yield.

Preferably, wherein the focal length of the first lens is f1, the focal length of the third lens is f3, and the following conditions are satisfied: -55 <f1/f3 <10. In this way, the positive refractive power of the first lens is effectively distributed to reduce the sensitivity of the four-piece infrared single-wavelength lens group.

Preferably, the focal length of the first lens is f1, and the focal length of the fourth lens is f4, and the following conditions are satisfied: -1.6 <f1/f4 <20. In this way, the positive refractive power of the first lens is effectively distributed to reduce the sensitivity of the four-piece infrared single-wavelength lens group.

Preferably, the focal length of the second lens is f2, and the focal length of the fourth lens is f4, and the following conditions are satisfied: -17 <f2/f4 <-0.1. In this way, the positive refractive power distribution of the system is more appropriate, which is helpful to correct the system aberration to improve the imaging quality of the system.

Preferably, wherein the focal length of the first lens is f1, the combined focal length of the second lens and the third lens is f23, and the following conditions are satisfied: -80 <f1/f23 <15. In this way, when f1/f23 satisfies the above conditions, the four-piece infrared single-wavelength lens group can achieve a wide angle of view (angle of view) while significantly improving its resolution capability.

Preferably, the combined focal length of the first lens and the second lens is f12, and the focal length of the third lens is f3, and the following conditions are satisfied: 0.05 <f12/f3 <1.8. In this way, it is advantageous to obtain a wide angle of view (field angle) and effectively correct curvature of field.

Preferably, the combined focal length of the first lens and the second lens is f12, and the focal length of the fourth lens is f4, and the following conditions are satisfied: -1 <f12/f4 <-0.05. In this way, it is advantageous to obtain a wide angle of view (field angle) and effectively correct curvature of field.

Preferably, the combined focal length of the first lens and the second lens is f12, and the combined focal length of the third lens and the fourth lens is f34, and the following conditions are satisfied: -0.15 <f12/f34 <1.4. In this way, it is advantageous to obtain a wide angle of view (field angle) and effectively correct curvature of field.

Preferably, wherein the focal length of the second lens is f2, the combined focal length of the third lens and the fourth lens is f34, and the following conditions are satisfied: -0.4 <f2/f34 <2.7. In this way, it is advantageous to obtain a wide angle of view (field angle) and effectively correct curvature of field.

Preferably, the combined focal length of the second lens and the third lens is f23, and the focal length of the fourth lens is f4, and the following conditions are satisfied: -1.0 <f23/f4 <-0.05. In this way, it is advantageous to obtain a wide angle of view (field angle) and effectively correct curvature of field.

Preferably, 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 satisfied: -75 <f1/f234 <15. In this way, it is advantageous to obtain a wide angle of view (field angle) and effectively correct curvature of field.

Preferably, the combined focal length of the first lens, the second lens and the third lens is f123, and the focal length of the fourth lens is f4, and the following conditions are satisfied: -0.7 <f123/f4 <-0.05. In this way, it is advantageous to obtain a wide angle of view (field angle) and effectively correct curvature of field.

Preferably, the refractive index of the fourth lens is N4, the dispersion coefficient of the fourth lens is V4, and the following conditions are satisfied: 1.61 <N4; V4 <25. In this way, the transmittance of the whole four-piece infrared single-wavelength lens group is favorable, and the absorption rate of the infrared single-wavelength lens group is reduced.

Preferably, the aperture value of the four-piece infrared single-wavelength lens group is Fno, and satisfies the following condition: 1.2 <Fno, whereby the imaging surface can have sufficient and appropriate illuminance.

Preferably, wherein the overall focal length of the four-piece infrared single-wavelength lens group is f, the distance from the object-side surface of the first lens to the imaging surface on the optical axis is TL, and the following conditions are satisfied: 0.5 <f/TL ＜ 0.9. In this way, it is beneficial to maintain the miniaturization and long focus of the four-piece infrared single-wavelength lens group to be mounted on thin and light electronic products.

With regard to the techniques, means and other effects adopted by the present invention to achieve the above-mentioned objectives, six preferred and feasible embodiments are described in detail below with reference to the drawings.

<First embodiment>

Please refer to FIGS. 1A and 1B, wherein FIG. 1A is a schematic diagram of a four-piece infrared single-wavelength lens assembly according to a first embodiment of the present invention, and FIG. 1B is a four-piece infrared of the first embodiment in order from left to right. Single-wavelength lens group image plane curve and distortion curve. As can be seen from FIG. 1A, the four-piece infrared single-wavelength 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 in order from the object side to the image side. The fourth lens 140, the infrared filtering filter 170, and the imaging surface 180, wherein the refractive lens in the four-piece infrared single-wavelength lens group is four. The aperture 100 is disposed before the first lens 110.

The first lens 110 has a positive refractive power and is made of plastic material. 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 aspherical.

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

The third lens 130 has a positive refractive power and is made of plastic. The object-side surface 131 is concave near the optical axis 190, the image-side surface 132 is convex 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 negative refractive power and is made of plastic material. The object-side surface 141 is convex near the optical axis 190, the image-side surface 142 is concave near the optical axis 190, and the object-side surface 141 and the image side The surfaces 142 are all aspherical, and at least one of the object-side surface 141 and the image-side surface 142 has at least one inflection point.

The infrared filter 170 is made of glass, which is disposed between the fourth lens 140 and the imaging surface 180 and does not affect the focal length of the four-piece infrared single-wavelength lens group.

The curve equation of the aspheric surface of each lens is expressed as follows:

Where z is the position value along the optical axis 190 at the height h with the surface vertex as a reference; 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 of the lens surface from the optical axis 190, k is the conic constant, and A, B, C, D, E, F, G,... … Is a high-order aspheric coefficient.

In the four-piece infrared single-wavelength lens group of the first embodiment, the focal length of the four-piece infrared single-wavelength lens group is f, and the aperture value (f-number) of the four-piece infrared single-wavelength lens group is Fno, and the four-piece type The maximum field angle (drawing angle) in the infrared single-wavelength lens group is FOV, and its values are as follows: f = 2.08 (mm); Fno = 1.11; and FOV = 75.3 (degrees).

In the four-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 = 1.95.

In the four-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 = 2.00.

In the four-piece infrared single-wavelength lens group of the first embodiment, the focal length of the third lens 130 is f3, and the focal length of the fourth lens 140 is f4, and the following conditions are satisfied: f3/f4 = -0.49.

In the four-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 = 3.89.

In the four-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 fourth lens 140 is f4, and the following conditions are satisfied: f1/f4 = -1.91.

In the four-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 fourth lens 140 is f4, and the following conditions are satisfied: f2/f4 = -0.98.

In the four-piece infrared single-wavelength lens group of the first embodiment, the focal length of the first lens 110 is f1, the combined focal length of the second lens 120 and the third lens 130 is f23, and the following conditions are satisfied: f1/f23 = 4.93.

In the four-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 = 1.41.

In the four-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 fourth lens 140 is f4, and the following conditions are satisfied: f12/f4 = -0.69.

In the four-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 combined focal length of the third lens 130 and the fourth lens 140 is f34, and satisfies the following Condition: f12/f34 = 0.91.

In the four-piece infrared single-wavelength lens group of the first embodiment, the focal length of the first lens 110 is f2, the combined focal length of the third lens 130 and the fourth lens 140 is f34, and the following conditions are satisfied: f2/f34 = 1.29.

In the four-piece infrared single-wavelength lens group of the first embodiment, the combined focal length of the second lens 120 and the third lens 130 is f23, and the focal length of the fourth lens 140 is f4, and the following conditions are satisfied: f23/f4 = -0.39.

In the four-piece infrared single-wavelength lens group of the first embodiment, the focal length of the first lens 110 is f1, the combined focal length of the second lens 120, the third lens 130, and the fourth lens 140 is f234, and meets the following conditions : F1/f234 = 4.13.

In the four-piece infrared single-wavelength 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 focal length of the fourth lens 140 is f4, and the following conditions are satisfied : F123/f4 = -0.38.

In the four-piece infrared single-wavelength lens group of the first embodiment, the overall focal length of the four-piece infrared single-wavelength lens group is f, and the object-side surface 111 of the first lens 110 to the imaging surface 180 on the optical axis 190 The distance is TL and meets the following conditions: f/TL = 0.69.

Refer to Table 1 and Table 2 below.

Table 1 is the detailed structural data of the first embodiment of FIG. 1A, in which the units of radius of curvature, thickness and focal length are mm, and the surface 0-13 sequentially represents the surface from the object side to the image side. Table 2 is aspheric data in the first embodiment, where k represents the conical coefficient in the aspheric curve equation, and A, B, C, D, E, F, G, H... are high-order aspheric coefficients. In addition, the tables in the following embodiments correspond to the schematic diagrams and aberration curves of the embodiments. The definitions of the data in the tables are the same as those in Table 1 and Table 2 of the first embodiment, and are not repeated here.

<Second embodiment>

Please refer to FIGS. 2A and 2B, wherein FIG. 2A shows a schematic diagram of a four-piece infrared single-wavelength lens assembly according to a second embodiment of the present invention, and FIG. 2B is a four-piece infrared of the second embodiment in order from left to right. Single-wavelength lens group image plane curve and distortion curve. As can be seen from FIG. 2A, the four-piece infrared single-wavelength 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 in order from the object side to the image side. The fourth lens 240, the infrared filtering filter 270, and the imaging surface 280, wherein the refractive lens in the four-piece infrared single-wavelength lens group is four. The aperture 200 is disposed before the first lens 210.

The first lens 210 has a negative refractive power and is made of plastic material. 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 aspherical.

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

The third lens 230 has positive refractive power and is made of plastic material. The object side surface 231 is concave near the optical axis 290, the image side surface 232 is convex 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 negative refractive power and is made of plastic. The object-side surface 241 is convex near the optical axis 290, the image-side surface 242 is concave near the optical axis 290, and the object-side surface 241 and the image side The surfaces 242 are all aspherical, and at least one of the object-side surface 241 and the image-side surface 242 has at least one inflection point.

The infrared filter 270 is made of glass, which is disposed between the fourth lens 240 and the imaging surface 280 and does not affect the focal length of the four-piece infrared single-wavelength lens group.

Refer to Table 3 and Table 4 below.

In the second embodiment, the curve equation of the aspherical 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.

Together with Table 3 and Table 4, the following data can be derived:

<Third Embodiment>

Please refer to FIGS. 3A and 3B, wherein FIG. 3A is a schematic diagram of a four-piece infrared single-wavelength lens assembly according to a third embodiment of the present invention, and FIG. 3B is a four-piece infrared of the third embodiment in order from left to right. Single-wavelength lens group image plane curve and distortion curve. As can be seen from FIG. 3A, the four-piece infrared single-wavelength lens group includes an aperture 300 and an optical group. The optical group includes a first lens 310, a second lens 320, and a third lens 330 in order from the object side to the image side. The fourth lens 340, the infrared filtering filter 370, and the imaging surface 380, wherein the refractive power lens in the four-piece infrared single-wavelength lens group is four. The aperture 300 is disposed before the first lens 310.

The first lens 310 has a positive 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 aspherical.

The second lens 320 has a positive refractive power and is made of plastic. The object-side surface 321 is convex near the optical axis 390, the image-side surface 322 is concave 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 a positive refractive power and is made of plastic material. The object-side surface 331 is concave near the optical axis 390, the image-side surface 332 is convex near the optical axis 390, and the object-side surface 331 and the image side The surfaces 332 are all aspherical.

The fourth lens 340 has a negative refractive power and is made of plastic. The object-side surface 341 is convex near the optical axis 390, the image-side surface 342 is concave near the optical axis 390, and the object-side surface 341 and the image side The surfaces 342 are all aspherical, and at least one of the object-side surface 341 and the image-side surface 342 has at least one inflection point.

The infrared filtering filter 370 is made of glass, which is disposed between the fourth lens 340 and the imaging surface 380 and does not affect the focal length of the four-piece infrared single-wavelength lens group.

Refer to Table 5 and Table 6 below.

In the third embodiment, the curve equation of the aspherical 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.

Together with Tables 5 and 6, the following data can be derived:

<Fourth embodiment>

Please refer to FIGS. 4A and 4B, wherein FIG. 4A shows a schematic diagram of a four-piece infrared single-wavelength lens assembly according to a fourth embodiment of the present invention, and FIG. 4B is a four-piece infrared of the fourth embodiment in order from left to right. Single-wavelength lens group image plane curve and distortion curve. As can be seen from FIG. 4A, the four-piece infrared single-wavelength lens group includes an aperture 400 and an optical group. The optical group includes a first lens 410, a second lens 420, and a third lens 430 in order from the object side to the image side. The fourth lens 440, the infrared filtering filter 470, and the imaging surface 480, wherein the refractive lens in the four-piece infrared single-wavelength lens group is four. The aperture 400 is disposed before the first lens 410.

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

The second lens 420 has a positive refractive power and is made of plastic material. The object side surface 421 is concave near the optical axis 490, the image side surface 422 is convex 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 positive refractive power and is made of plastic. The object-side surface 431 is concave near the optical axis 490, the image-side surface 432 is convex near the optical axis 490, and the object-side surface 431 and the image side The surfaces 432 are all aspherical.

The fourth lens 440 has a negative refractive power and is made of plastic material. The object-side surface 441 is convex near the optical axis 490, the image-side surface 442 is concave near the optical axis 490, and the object-side surface 441 and the image side The surfaces 442 are all aspherical, and at least one of the object-side surface 441 and the image-side surface 442 has at least one inflection point.

The infrared filtering filter 470 is made of glass, which is disposed between the fourth lens 440 and the imaging surface 480 and does not affect the focal length of the four-piece infrared single-wavelength lens group.

Refer to Table 7 and Table 8 below.

In the fourth embodiment, the curve equation of the aspherical 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.

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

<Fifth Embodiment>

Please refer to FIGS. 5A and 5B, wherein FIG. 5A is a schematic diagram of a four-piece infrared single-wavelength lens assembly according to a fifth embodiment of the present invention, and FIG. 5B is a four-piece infrared of the fifth embodiment in order from left to right. Single-wavelength lens group image plane curve and distortion curve. As can be seen from FIG. 5A, the four-piece infrared single-wavelength lens group includes an aperture 500 and an optical group. The optical group includes a first lens 510, a second lens 520, and a third lens 530 in order from the object side to the image side. The fourth lens 540, the infrared filtering filter 570, and the imaging surface 580, wherein the refractive lens in the four-piece infrared single-wavelength lens group is four. The aperture 500 is disposed before the first lens 510.

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

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

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

The fourth lens 540 has a negative refractive power and is made of plastic. The object side surface 541 is convex near the optical axis 590, the image side surface 542 is concave near the optical axis 590, and the object side surface 541 and the image side The surfaces 542 are all aspherical, and at least one of the object-side surface 541 and the image-side surface 542 has at least one inflection point.

The infrared filtering filter 570 is made of glass, which is disposed between the fourth lens 540 and the imaging surface 580 and does not affect the focal length of the four-piece infrared single-wavelength lens group.

Refer to Table 9 and Table 10 below.

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.

Together with Tables 9 and 10, the following data can be calculated:

<Sixth Embodiment>

Please refer to FIGS. 6A and 6B, wherein FIG. 6A shows a schematic diagram of a four-piece infrared single-wavelength lens group according to a sixth embodiment of the present invention, and FIG. 6B is a four-piece infrared of the sixth embodiment in order from left to right. Single-wavelength lens group image plane curve and distortion curve. As can be seen from FIG. 6A, the four-piece infrared single-wavelength 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 in order from the object side to the image side. The fourth lens 640, the infrared filtering filter 670, and the imaging surface 680, wherein the refractive lens in the four-piece infrared single-wavelength lens group is four. The aperture 600 is disposed before the first lens 610.

The first lens 610 has a positive refractive power and is made of plastic. The object-side surface 611 is convex near the optical axis 690, the image-side surface 612 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. The object side surface 621 is concave near the optical axis 690, the image side surface 622 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 concave near the optical axis 690, the image-side surface 632 is convex near the optical axis 690, and the object-side surface 631 and the image side The surfaces 632 are all aspherical.

The fourth lens 640 has a negative refractive power and is made of plastic material. The object-side surface 641 is convex near the optical axis 690, the image-side surface 642 is concave near the optical axis 690, and the object-side surface 641 and the image side The surfaces 642 are all aspherical, and at least one of the object-side surface 641 and the image-side surface 642 has at least one inflection point.

The infrared filter 670 is made of glass, which is disposed between the fourth lens 640 and the imaging surface 680 and does not affect the focal length of the four-piece infrared single-wavelength lens group.

Refer to Table 11 and Table 12 below.

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.

Together with Tables 9 and 10, the following data can be calculated:

The four-piece infrared single-wavelength lens set provided by the present invention can be made of plastic or glass. When the lens material is plastic, the production cost can be effectively reduced, and when the lens material is glass, four-piece infrared lenses can be added. The degree of freedom for 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 four-piece infrared single-wavelength lens group can be aspherical, and the aspherical surface can be easily made into a shape other than a spherical surface, and more control variables are obtained to reduce aberrations, and By reducing the number of lenses used, the total length of the four-piece infrared single-wavelength lens group of the present invention can be effectively reduced.

In the four-piece infrared single-wavelength lens group 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 four-piece infrared single-wavelength lens set provided by the present invention can be applied to a mobile focusing optical system according to visual 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 , Digital cameras, mobile devices, digital tablets or car photography and other electronic imaging systems.

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

100, 200, 300, 400, 500, 600 ‧ ‧ ‧ aperture 110, 210, 310, 410, 510, 610 ‧ ‧ ‧ first lens 111, 211, 311, 411, 511, 611 ‧ ‧ ‧ ‧ object side surface 112 , 212, 312, 412, 512, 612‧‧‧‧image side surface 120, 220, 320, 420, 520, 620‧‧‧ second lens 121, 221, 321, 421, 521, 621‧‧‧ object side surface 122, 222, 322, 422, 522, 622 ‧ ‧‧‧ image side surface 130, 230, 330, 430, 530, 630 ‧ ‧ ‧ third lens 131, 231, 331, 431, 531, 631 ‧ ‧ ‧ object side Surfaces 132, 232, 332, 432, 532, 632 ‧‧‧‧ image side surfaces 140, 240, 340, 440, 540, 640 ‧ ‧‧ fourth lens 141, 241, 341, 441, 541, 641 ‧ ‧ ‧ Side surface 142, 242, 342, 442, 542, 642 ‧‧‧ Image side surface 170, 270, 370, 470, 570, 670 ‧ ‧‧ infrared filter 180, 280, 380, 480, 580, 680 ‧‧‧Imaging plane 190, 290, 390, 490, 590, 690 ‧‧‧ Optical axis f‧‧‧Focus length of four-piece infrared single-wavelength lens group Fno‧‧‧Aperture value of four-piece infrared single-wavelength lens group FOV‧‧‧Maximum field of view in the four-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 f4‧‧‧ Lens focal length f12‧‧‧Combined focal length of first lens and second lens f23‧‧‧Combined focal length of second lens and third lens f34‧‧‧Combined focal length of third lens and fourth lens f123‧‧‧ The combined focal length of the first lens, the second lens and the third lens f234‧‧‧The combined focal length of the second lens, the third lens and the fourth lens TL‧‧‧The distance from the object side surface of the first lens to the imaging surface on the optical axis

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

170‧‧‧Infrared filter

180‧‧‧Imaging surface

190‧‧‧ Optical axis

Claims (18)

A four-piece infrared single-wavelength lens group, which includes, in order from the object side to the image side, an aperture; a first lens with refractive power, a convex surface on the object side surface near the optical axis, and an object side surface and an image side At least one of the surfaces is aspheric; a second lens with positive refractive power, at least one of its object-side surface and image-side surface is aspheric; a third lens with positive refractive power, its object-side surface is near the optical axis At the concave side, the image side surface is near the optical axis is convex, at least one of the object side surface and the image side surface is aspheric; and a fourth lens with negative refractive power, at the object side surface near the optical axis is The convex surface is concave at the image side surface near the optical axis, and at least one of the object side surface and the image side surface is aspherical. The four-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: -45 <f1/f2 <10. The four-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: 0.3 <f2/f3 <18. The four-piece infrared single-wavelength lens group according to claim 1, wherein the focal length of the third lens is f3 and the focal length of the fourth lens is f4, and the following conditions are satisfied: -1.7 <f3/f4 <-0.1. The four-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: -55 <f1/f3 <10. The four-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 fourth lens is f4, and the following conditions are satisfied: -1.6 <f1/f4 <20. The four-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 fourth lens is f4, and the following conditions are satisfied: -17 <f2/f4 <-0.1. The four-piece infrared single-wavelength lens group according to claim 1, wherein the focal length of the first lens is f1, the combined focal length of the second lens and the third lens is f23, and the following conditions are satisfied: -80 <f1/ f23 <15. The four-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, and the focal length of the third lens is f3, and the following conditions are satisfied: 0.05 <f12/f3 ＜ 1.8. The four-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, and the focal length of the fourth lens is f4, and the following conditions are satisfied: -1 <f12/ f4 <-0.05. The four-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, and the combined focal length of the third lens and the fourth lens is f34, and the following conditions are satisfied: -0.15 <f12/f34 <1.4. The four-piece infrared single-wavelength lens group according to claim 1, wherein the focal length of the second lens is f2, the combined focal length of the third lens and the fourth lens is f34, and the following conditions are satisfied: -0.4 <f2/ f34 <2.7. The four-piece infrared single-wavelength lens group according to claim 1, wherein the combined focal length of the second lens and the third lens is f23, and the focal length of the fourth lens is f4, and the following conditions are satisfied: -1.0 <f23/ f4 <-0.05. The four-piece infrared single-wavelength 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 satisfied:- 75 <f1/f234 <15. The four-piece infrared single-wavelength 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 focal length of the fourth lens is f4, and the following conditions are satisfied:- 0.7 <f123/f4 <-0.05. The four-piece infrared single-wavelength lens group according to claim 1, wherein the refractive index of the fourth lens is N4, the dispersion coefficient of the fourth lens is V4, and the following conditions are satisfied: 1.61 <N4; V4 <25. The four-piece infrared single-wavelength lens group according to claim 1, wherein the aperture value of the four-piece infrared single-wavelength lens group is Fno, and the following conditions are satisfied: 1.2 <Fno. The four-piece infrared single-wavelength lens group according to claim 1, wherein the overall focal length of the four-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 meet the following conditions: 0.5 <f/TL <0.9.

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