3m infrared dms optical lens and imaging method thereof

Abstract

The present application relates to a kind of 3M infrared DMS optical lens and its imaging method, the optical system of lens is by the diaphragm, first lens, second lens, third lens and fourth lens sequentially arranged from left to right along the light path of light incidence, the first lens is meniscus convex positive lens, the second lens is meniscus convex positive lens, the third lens is double convex positive lens, the fourth lens is double concave negative lens, first lens is glass aspheric lens, second lens, third lens and fourth lens are plastic aspheric lens.The present application is reasonable in design, the imaging angle of object is greater than 60 degrees, has the imaging definition of 3M, large light aperture, lower tolerance sensitivity and the advantages such as good high-low temperature stability, while, driver can be monitored more comprehensively.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lenses, and particularly relates to a 3M infrared DMS optical lens and an imaging method thereof. BACKGROUND

[0002] According to the definition classification of the Society of Automotive Engineers (SAE) on automatic driving, a driver monitoring system (DMS) plays an indispensable role in L3 (conditional automatic driving) and L4 (highly automatic driving) automatic driving vehicles. Although L3 and L4 automatic driving can complete all driving operations by an unmanned driving system, when the driving scene exceeds the system capacity, a human driver is still required to provide a response or take over the driving right. Therefore, the state of the driver needs to be monitored to determine whether the driving right can be safely returned to the driver from the unmanned driving system. The DMS has thus become a necessary system in L3 and L4 automatic driving vehicles, and has become a high-deterministic and influential technical field in the automatic driving market, which requires high resolving power. In order to meet the optical performance of high resolving power, large aperture and low distortion, the market adopts a full-glass lens structure for design under the limitation of small volume or releases the volume, resulting in high cost or being not conducive to integration, which is not conducive to market promotion. SUMMARY

[0003] The application improves the prior art, and aims to provide a 3M infrared DMS optical lens and an imaging method thereof.

[0004] In order to achieve the above purpose, the technical scheme adopted by the application is as follows: a 3M infrared DMS optical lens, an optical system of the lens is composed of a diaphragm, a first lens, a second lens, a third lens and a fourth lens arranged in sequence from left to right along an incident light path of light rays, the first lens is a meniscus convex positive lens, the second lens is a meniscus convex positive lens, the third lens is a double convex positive lens, and the fourth lens is a double concave negative lens, the first lens is a glass aspherical lens, and the second lens, the third lens and the fourth lens are plastic aspherical lenses.

[0005] Further, the object side of the first lens is a convex surface, and the image side is a concave surface; the object side of the second lens is a convex surface, and the image side is a concave surface; the object side of the third lens is a convex surface, and the image side is a convex surface; and the object side of the fourth lens is a concave surface, and the image side is a concave surface.

[0006] Further, the focal length of the optical system is f, and the focal lengths of the first lens, the second lens, the third lens and the fourth lens are f1, f2, f3 and f4 respectively, wherein f1, f2, f3 and f4 satisfy the following ratios: 1.5

[0007] Further, the first lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; the second lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≤50.0; the third lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; and the fourth lens satisfies the relationship: 1.5≤N d ≤1.8, V d ≥50.0; wherein N d is the refractive index, and V d is the Abbe number.

[0008] Further, the air gap between the first lens and the second lens is 0.5-1.0 mm; the air gap between the second lens and the third lens is 0.0-0.5 mm; and the air gap between the third lens and the fourth lens is 0.0-0.5 mm.

[0009] Further, the aspherical surface curve equation expressions of the first lens, the second lens, the third lens and the fourth lens are as follows:

[0010]

[0011] wherein Z is the sagittal height of the aspherical surface at a height of h along the optical axis from the vertex of the aspherical surface; c is the paraxial curvature of the aspherical surface; k is the conic constant; and α1, α2, α3, α4, α5, α6, α7 and α8 are high-order coefficients.

[0012] Further, the total optical length TTL of the optical system and the focal length f of the optical system satisfy: TTL / f≤1.3.

[0013] Further, the F number of the optical system is ≤2.0; and the image height H of the optical system and the focal length f of the optical system satisfy: H / f≤0.6.

[0014] Further, the diaphragm is located on the object side of the first lens; and the rear side of the fourth lens is provided with an equivalent glass flat plate.

[0015] Another technical solution adopted in this invention is: an imaging method for a 3M infrared DMS optical lens, wherein during imaging: light enters from left to right through the aperture stop, the first lens, the second lens, the third lens, the fourth lens, and the equivalent glass plate, and then forms an image on the imaging surface.

[0016] Compared with the prior art, the present invention has the following advantages: The present invention is reasonably designed, with an imaging angle of more than 60 degrees for objects, and has the advantages of 3M imaging clarity, large light transmission aperture, low tolerance sensitivity and good high and low temperature stability, while enabling more comprehensive monitoring of the driver. Attached image description:

[0017] Figure 1 This is a schematic diagram of the optical structure according to an embodiment of the present invention;

[0018] Figure 2 This is an axial chromatic aberration diagram of the entire working band of this invention.

[0019] Figure 3 This is a cross-axis chromatic aberration diagram of the entire working band of this invention.

[0020] Figure 4 This is a field curvature distortion diagram of the entire working band according to an embodiment of the present invention.

[0021] In the picture:

[0022] STO - Aperture stop; L1 - First lens; L2 - Second lens; L3 - Third lens; L4 - Fourth lens; L5 - Equivalent glass plate; IMA - Imaging surface. Detailed implementation method:

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 1 As shown, this invention discloses a 3M infrared DMS optical lens that, while meeting the requirements of high resolution, large aperture, and low distortion, also satisfies the requirements of small size, low production cost, and 24 / 7 all-weather operation. Specifically, the lens's optical system consists of an aperture stop STO, a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4 arranged sequentially from left to right (from object to image) along the incident light path. The first lens is a meniscus convex positive lens, the second lens is a meniscus convex positive lens, the third lens is a biconvex positive lens, and the fourth lens is a biconcave negative lens. The first lens is a glass aspherical lens, while the second, third, and fourth lenses are all plastic aspherical lenses. Through a reasonable lens combination, the optical system achieves a 3M small size, large aperture, day and night confocal design, and low temperature drift, while also providing good correction for on-axis and off-axis aberrations, resulting in good image quality.Figures 2 to 4 As shown.

[0025] In this embodiment, the object side surface of the first lens is convex, the image side surface is concave; the object side surface of the second lens is convex, the image side surface is concave; the object side surface of the third lens is convex, the image side surface is convex; the object side surface of the fourth lens is concave, the image side surface is concave.

[0026] In this embodiment, the focal length of the optical system is f, and the focal lengths of the first lens, the second lens, the third lens and the fourth lens are f1, f2, f3 and f4 respectively, wherein f1, f2, f3 and f4 satisfy the following ratios: 1.5 < f1 / f < 2.0, 10.0 < f2 / f < 11.0, 0.5 < f3 / f < 1.0, -1.0 < f4 / f < -0.5.

[0027] In this embodiment, the first lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; the second lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; the third lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; the fourth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; wherein N d is the refractive index, and V d is the Abbe number.

[0028] In this embodiment, the air gap between the first lens and the second lens is 0.5-1.0 mm; the air gap between the second lens and the third lens is 0.0-0.5 mm; the air gap between the third lens and the fourth lens is 0.0-0.5 mm.

[0029] In this embodiment, the aspherical surface curve equation expressions of the first lens, the second lens, the third lens and the fourth lens are as follows:

[0030]

[0031] wherein Z is the sagittal height of the aspherical surface at a height of h along the optical axis; c is the paraxial curvature of the aspherical surface; k is the conic constant; α1, α2, α3, α4, α5, α6, α7 and α8 are high-order coefficients. Further, the aspherical surface coefficients of each aspherical lens of the optical system are as follows:

[0032]

[0033] In the embodiment, the total track length TTL of the optical system and the focal length f of the optical system satisfy: TTL / f≤1.3.

[0034] In the embodiment, the F number of the optical system is ≤2.0.

[0035] In the embodiment, the image height H of the optical system and the focal length f of the optical system satisfy: H / f≤0.6.

[0036] In the embodiment, the diaphragm is located on the object side of the first lens.

[0037] In the embodiment, the rear side of the fourth lens is provided with an equivalent glass flat plate L5.

[0038] The technical indexes achieved by the optical system in the embodiment are as follows:

[0039] (1) focal length: 5.0≤EFFL≤6.0mm;

[0040] (2) aperture F≤2.0;

[0041] (3) field of view angle: 2w≥60°;

[0042] (4) working waveband: 940nm short-wave infrared waveband.

[0043] To achieve the design parameters, the specific design of the optical system in the embodiment is shown in the following table:

[0044]

[0045] In the embodiment, the imaging method of the 3M infrared DMS optical lens is as follows: when imaging, light rays enter the diaphragm STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the equivalent glass flat plate L5 from left to right, and then image on the imaging surface IMA.

[0046] In the embodiment, the optical system is designed to meet the 3M imaging performance requirements by reasonably distributing the optical power, surface type, central thickness of each lens and the axial distance between each lens, and adopts the structure form of combining plastic aspherical lenses and glass aspherical lenses to reduce the total length of the lens and the radial size of each lens, so as to realize the miniaturization of the lens group and the cost reduction.

[0047] The advantages of the present application are as follows:

[0048] 1. The lens has an imaging angle of more than 60 degrees for an object, and has the advantages of 3M imaging clarity, large light aperture, low tolerance sensitivity and good high-low temperature stability, and can more comprehensively monitor the driver;

[0049] 2. By reasonably collocating each optical lens, the system structure is compact and reasonable, has a small volume, is easy to assemble, has low tolerance sensitivity, and is more suitable for large-scale high-yield production;

[0050] 3. One glass lens is collocated with three plastic lenses, which reduces the cost while adapting to the environment;

[0051] 4. The focusing surface displacement can be compensated well at high and low temperatures, and the system has complex environment adaptability;

[0052] 5. Each axial chromatic aberration, sagittal chromatic aberration and high-order chromatic aberration is corrected, so that the imaging system can have high imaging quality at a large angle.

[0053] If the present application discloses or involves mutually fixed connecting parts or structural parts, except otherwise stated, the fixed connection can be understood as: detachable fixed connection (for example, using bolt or screw connection), and can also be understood as: non-detachable fixed connection (for example, riveting, welding), of course, the mutually fixed connection can also be replaced by an integral structure (for example, using casting process integral forming manufacturing) (obviously, except for integral forming process).

[0054] In addition, the terms used to represent the position relationship or shape in any of the technical solutions disclosed above include the approximate, similar or close state or shape, unless otherwise stated.

[0055] Any component provided by the present application can be assembled from multiple individual components, or can be a single component manufactured by integral forming process.

[0056] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application and not to limit it; although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: the specific embodiments of the present application can be modified or some technical features can be replaced by equivalent; without departing from the spirit of the technical solutions of the present application, they should be covered in the technical solution range of the present application claimed.

Claims

1. A 3M infrared DMS optical lens characterized by: The optical system of the lens is composed of a diaphragm, a first lens, a second lens, a third lens and a fourth lens arranged in sequence from left to right along the light path of the incident light, the first lens is a meniscus convex positive lens, the second lens is a meniscus convex positive lens, the third lens is a double convex positive lens, and the fourth lens is a double concave negative lens, the first lens is a glass aspheric lens, and the second lens, the third lens and the fourth lens are plastic aspheric lenses; The object side of the first lens is a convex surface, and the image side is a concave surface; the object side of the second lens is a convex surface, and the image side is a concave surface; the object side of the third lens is a convex surface, and the image side is a convex surface; and the object side of the fourth lens is a concave surface, and the image side is a concave surface; The focal length of the optical system is f, and the focal lengths of the first lens, the second lens, the third lens and the fourth lens are f1, f2, f3 and f4 respectively, wherein f1, f2, f3 and f4 satisfy the following ratios: 1.5 < f1 / f < 2.0, 10.0 < f2 / f < 11.0, 0.5 < f3 / f < 1.0 and -1.0 < f4 / f < -0.5; The total optical length TTL of the optical system and the focal length f of the optical system satisfy: TTL / f ≤ 1.3; The F number of the optical system is ≤2.0; the image height H of the optical system and the focal length f of the optical system satisfy: H / f ≤ 0.6; The number of lenses with optical power in the lens is four.

2. A 3M infrared DMS optical lens according to claim 1, characterized in that: The first lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; the second lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≤ 50.0; the third lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; and the fourth lens satisfies the relationship: 1.5 ≤ N d ≤ 1.8, V d ≥ 50.0; wherein N d is the refractive index, and V d is the Abbe number.

3. A 3M infrared DMS optical lens according to claim 1, characterized in that: The air gap between the first lens and the second lens is 0.5-1.0 mm; the air gap between the second lens and the third lens is 0.0-0.5 mm; and the air gap between the third lens and the fourth lens is 0.0-0.5 mm.

4. A 3M infrared DMS optical lens according to claim 1, characterized in that: The aspheric curve equation expression of the first lens, the second lens, the third lens and the fourth lens is: Wherein, z is the sagittal height of the aspheric surface at a height of h along the optical axis direction from the vertex of the aspheric surface; c is the paraxial curvature of the aspheric surface, r=1 / c; k is the conic constant; α1, α2, α3, α4, α5, α6, α7 and α8 are high-order coefficients.

5. A 3M infrared DMS optical lens according to claim 1, characterized in that: The diaphragm is located on the object side of the first lens; and an equivalent glass flat plate is arranged on the rear side of the fourth lens.

6. An imaging method for a 3M infrared DMS optical lens characterized by: The 3M infrared DMS optical lens is adopted, and when imaging, the light rays enter the diaphragm, the first lens, the second lens, the third lens, the fourth lens and the equivalent glass flat plate from left to right, and then image on the imaging surface.

Images