A large-target super-starlight train cabin monitoring optical system

Abstract

The present invention provides a large-target-area super-starlight train cabin monitoring optical system, which includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a filter, a protective glass, and an image plane, arranged in sequence from the object side to the image side. The first lens is a meniscus lens with a negative optical focal length; the second lens is a meniscus lens with a positive optical focal length; the third lens is a meniscus lens with a negative optical focal length; the fourth lens is a biconvex lens with a positive optical focal length; the fifth lens is a biconvex lens with a positive optical focal length; the sixth lens is a biconcave lens with a negative optical focal length; the seventh lens is a biconvex lens with a positive optical focal length; and the eighth lens is a concave-convex lens with a positive optical focal length. The large-target-area super-starlight train cabin monitoring optical system provided by the present invention takes into account the characteristics of long focal length, large aperture, large target area, high definition, purple fringing optimization, and thermal drift stability.

Description

Technical Field

[0001] The present invention relates to the field of imaging technology, and in particular to a large-target-area super-starlight train cabin monitoring optical system. Background Art

[0002] In recent years, with the continuous advancement of technology and the increasing emphasis on driving safety, various driver-assistance systems have emerged, such as ADAS (Advanced Driver Assistance Systems), DMS (Driver Monitoring Systems), and OMS (Occupant Monitoring Systems). Among these, market demand for OMS systems (Occupant Monitoring Systems) supporting intelligent driving is increasing. OMS systems primarily track the status of passengers in the cabin to ensure their safety. However, they are primarily used in automobiles, with limited application in trains and subways. Therefore, a large-area super-starlight train cabin monitoring optical system has been developed specifically for these applications.

[0003] Existing optical systems for OMS monitoring often suffer from issues such as short focal length, small aperture, small target surface, poor stability to high and low temperature thermal drift, and severe edge purple fringing. To address these issues, the present invention proposes a large-target-area super-starlight train cabin monitoring optical system that combines the advantages of long focal length, large aperture, large target surface, high definition, optimized purple fringing, and thermal drift stability. Summary of the Invention

[0004] The purpose of the present invention is to provide a large-target-area super-starlight train cabin monitoring optical system to solve the technical problems of traditional OMS monitoring optical systems, such as short focal length, small aperture, small target surface, poor high and low temperature thermal drift stability, and severe edge purple fringing.

[0005] To achieve the above-mentioned object, the technical solution adopted by the present invention is to provide a large-target-area super-starlight train cabin monitoring optical system, the large-target-area super-starlight train cabin monitoring optical system comprising:

[0006] The large-target-area super starlight train cabin monitoring optical system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a filter, a protective glass and an image plane arranged in sequence from the object side to the image side, wherein the first lens is a meniscus lens with a negative optical focal length; the second lens is a meniscus lens with a positive optical focal length; the third lens is a meniscus lens with a negative optical focal length; the fourth lens is a biconvex lens with a positive optical focal length; the fifth lens is a biconvex lens with a positive optical focal length; the sixth lens is a biconcave lens with a negative optical focal length; the seventh lens is a biconvex lens with a positive optical focal length; and the eighth lens is a concave-convex lens with a positive optical focal length.

[0007] In one embodiment, the ratios of the focal lengths of the first to eighth lenses to the focal lengths of the optical system lenses satisfy the following set relationships: 1.7 < |f1 / f| < 2.1, 15.3 < |f2 / f| < 15.7, 4.8 < |f3 / f| < 5.2, 2.5 < |f4 / f| < 3.0, 1.7 < |f5 / f| < 2.2, 1.5 < |f6 / f| < 1.8, 2.6 < |f7 / f| < 2.9, 11.1 < |f8 / f| < 11.6; wherein f1 represents the effective focal length of the first meniscus lens, f2 represents the effective focal length of the second meniscus lens, f3 represents the effective focal length of the third meniscus lens, f4 represents the effective focal length of the fourth biconvex lens, f5 represents the effective focal length of the fifth biconvex lens, f6 represents the effective focal length of the sixth biconcave lens, f7 represents the effective focal length of the seventh biconvex lens, f8 represents the effective focal length of the eighth concave-convex lens, and f represents the effective focal length of the optical system lens.

[0008] In one embodiment, the refractive indexes of the third lens, the fifth lens, and the eighth lens are all greater than 1.45 and less than 1.62, and the Abbe coefficients are all greater than 50 and less than 65; the refractive indexes of the first lens and the fourth lens are all greater than 1.5 and less than 1.65, and the Abbe coefficients are all greater than 65 and less than 75.

[0009] In one embodiment, the maximum holographic image height of the large-target super-starlight train cabin monitoring optical system is: IH≥9.06.

[0010] In one embodiment, the aperture value of the large-target-area super starlight train cabin monitoring optical system is: F.NO≤1.0.

[0011] In one embodiment, the optical back focal length BFL and the effective focal length f of the large-target-area super starlight train cabin monitoring optical system satisfy the conditional formula: 1.2>BFL / f>1.0.

[0012] In one embodiment, the large-target-area super-starlight train cabin monitoring optical system satisfies the following conditional formula: 0.6<(h / 2) / (f×tan(FOV / 2))<0.75;

[0013] Wherein: f represents the effective focal length of the optical system, FOV represents the maximum field of view of the optical system, and h represents the maximum image circle of the optical system.

[0014] In one embodiment, the first lens has a convex surface facing the object side, and a concave surface facing the image side; the second lens has a concave surface facing the object side, and a convex surface facing the image side; the third lens has a concave surface facing the object side, and a convex surface facing the image side; the fourth lens has a small convex surface facing the object side, and a large convex surface facing the image side; the fifth lens has a large convex surface facing the object side, and a small convex surface facing the image side; the sixth lens has a small concave surface facing the object side, and a large concave surface facing the image side; the seventh lens has a large convex surface facing the object side, and a small convex surface facing the image side; the eighth lens has a convex surface facing the object side, and a concave surface facing the image side.

[0015] One or more of the above technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0016] The embodiment of the present invention provides a large-scale super-starlight train cabin monitoring optical system. By rationally using lenses of specific shapes and structures and limiting the optical focal length of each lens, excellent image quality is designed, reaching 8M high-definition pixel level, with a full image height of 9.05mm, which can match the 1 / 1.8 large-scale OS08A10 chip, meeting the market demand for matching high-definition large-scale chip. The focal length is 5.1mm, which can receive information of more distant objects and ensure long-distance shooting. The aperture reaches F1.0, which can realize color image acquisition in the dark and dim environment of the train cabin at night, greatly improving the nighttime management of the train. In order to improve the monitoring capability, the design adopts low-dispersion lens materials, optimizes the purple edge effect of the object edge, better restores the real scene, and makes the entire optical system have a thermal compensation effect. The operating temperature is -40℃ to 95℃, which well guarantees the product's resolution requirement under complex temperature scenes. Because the first lens of the existing optical system is generally made of plastic, it cannot withstand harsh high temperature and high humidity environments, and other lenses use GM (glass aspheric surface) to increase the cost. The first lens of this patent is glass, and the other lenses are a combination of glass and plastic, which achieves a balance between reliability and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 Schematic diagram of a lens according to an embodiment of the present invention;

[0019] Figure 2This is a 100lp / mm MTF analysis diagram at 20°C of an embodiment of the present invention;

[0020] Figure 3 This is a defocus curve of 100 lp / mm at 20°C according to an embodiment of the present invention;

[0021] Figure 4 This is a defocus curve of 100 lp / mm at 85°C according to an embodiment of the present invention;

[0022] Figure 5 This is a 100lp / mm defocus curve at -40°C according to an embodiment of the present invention;

[0023] Figure 6 A field curvature diagram according to an embodiment of the present invention;

[0024] Figure 7 : is an F-THETA distortion diagram of an embodiment of the present invention;

[0025] Figure 8 FIG. 4 is an imaging point diagram according to an embodiment of the present invention.

[0026] The reference numerals are as follows:

[0027] E1, first lens; E2, second lens; E3, third lens; E4, fourth lens; E5, fifth lens; E6, sixth lens; E7, seventh lens; E8, eighth lens; STO, aperture; IR, filter; CG, protective glass; IMA, image plane; S1, first mirror; S2, second mirror; S3, third mirror; S4, fourth mirror; S5, fifth mirror; S6, sixth mirror; S8, eighth mirror; S9, ninth mirror; S10, tenth mirror; S11, eleventh mirror; S12, twelfth mirror; S13, thirteenth mirror; S14, fourteenth mirror; S15, fifteenth mirror; S16, sixteenth mirror; S17, seventeenth mirror. DETAILED DESCRIPTION

[0028] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0029] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0031] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0032] The following describes an embodiment of an optical system according to an embodiment of the present invention. It should be noted that the data listed in Tables 1 and 2 below are preferred data for the present invention and are not intended to limit the present invention. Any person skilled in the art, after referring to the present invention, may make appropriate changes to the parameters or settings, and such changes will still fall within the scope of the present invention.

[0033]

[0034]

[0035] Table 1 Aspheric coefficients are shown in Table 2:

[0036]

[0037]

[0038]

[0039] Table 2

[0040] The aspheric coefficients satisfy the following equation:

[0041]

[0042] Among them, z is the aspheric surface sag, c is the aspheric surface paraxial curvature, y is the lens aperture, k is the cone coefficient, a4 is the 4th aspheric surface coefficient, a6 is the 6th aspheric surface coefficient, a8 is the 8th aspheric surface coefficient, a10 is the 10th aspheric surface coefficient, and a12 is the 12th aspheric surface coefficient.

[0043] Specifically, the R value (Radius) and thickness (Thickness) of each lens surface in this embodiment are shown in Table 1, and the aspheric surface parameters are shown in Table 2.

[0044] Table 1 shows the optical system's effective focal length of 5.1mm, total optical system length of 29.5mm, aperture F.NO. of 1.0, full image height of 9.06mm, and field of view (2w) of 108 degrees. Numbers 1-17 in Table 1 represent mirror surfaces S1-S17, respectively; 18 represents the filter, and 19 represents the protective glass.

[0045] In the embodiment of the present invention, the first lens is a meniscus lens with negative optical power; the second lens is a meniscus lens with positive optical power; the third lens is a meniscus lens with negative optical power; the fourth lens is a biconvex lens with positive optical power; the fifth lens is a biconvex lens with positive optical power; the sixth lens is a biconcave lens with negative optical power; the seventh lens is a biconvex lens with positive optical power; and the eighth lens is a concave-convex lens with positive optical power.

[0046] The ratio of the focal lengths of the first to eighth lenses to the focal length of the lens satisfies the following relationship:

[0047] 1.7<|f1 / f|<2.1, 15.3<|f2 / f|<15.7, 4.8<|f3 / f|<5.2, 2.5<|f4 / f|<3.0, 1.7<|f5 / f|<2.2, 1.5<|f6 / f|<1.8, 2.6<|f7 / f|<2.9, 11.1<|f8 / f|<11.6; wherein f1 represents the effective focal length of the first meniscus lens, f2 represents the effective focal length of the second meniscus lens, f3 represents the effective focal length of the third meniscus lens, f4 represents the effective focal length of the fourth biconvex lens, f5 represents the effective focal length of the fifth biconvex lens, f6 represents the effective focal length of the sixth biconcave lens, f7 represents the effective focal length of the seventh biconvex lens, f8 represents the effective focal length of the eighth concave-convex lens, and f represents the effective focal length of the optical system.

[0048] The refractive indexes of the third lens, the fifth lens, and the eighth lens described in this embodiment of the present invention are all greater than 1.45 and less than 1.62, and the Abbe coefficients are all greater than 50 and less than 65; the refractive indexes of the first lens and the fourth lens are all greater than 1.5 and less than 1.65, and the Abbe coefficients are all greater than 65 and less than 75.

[0049] In the optical system described in the embodiment of the present invention, the maximum total image height of the optical system is: IH≥9.06.

[0050] In the optical system described in the embodiment of the present invention, the aperture value of the optical system is: F.NO≤1.0.

[0051] In the optical system of the embodiment of the present invention, the optical back focal length BFL and the effective focal length f of the optical system satisfy the conditional formula: 1.2>BFL / f>1.0.

[0052] In the optical system described in the embodiment of the present invention, the optical system satisfies the following condition: 0.6<(h / 2) / (f×tan(FOV / 2))<0.75.

[0053] Wherein: f represents the effective focal length of the optical system, FOV represents the maximum field of view of the optical system, and h represents the maximum image circle of the optical system.

[0054] The first lens described in the embodiment of the present invention has a convex surface facing the object side and a concave surface facing the image side; the second lens has a concave surface facing the object side and a convex surface facing the image side; the third lens has a concave surface facing the object side and a convex surface facing the image side; the fourth lens has a small convex surface facing the object side and a large convex surface facing the image side; the fifth lens has a large convex surface facing the object side and a small convex surface facing the image side; the sixth lens has a small concave surface facing the object side and a large concave surface facing the image side; the seventh lens has a large convex surface facing the object side and a small convex surface facing the image side; and the eighth lens has a convex surface facing the object side and a concave surface facing the image side.

[0055] In an embodiment of the present invention, Figure 2 The modulation transfer function (MTF) curve for the visible light band represents the comprehensive resolution capability of the optical system. The horizontal axis represents the spatial frequency (cycles / mm), and the vertical axis represents the value of the modulation transfer function (MTF). The MTF value is used to evaluate the imaging quality of the lens, and the value range is 0-1. It is particularly pointed out that the optical transfer function is a relatively accurate, intuitive and common way to evaluate the imaging quality of an optical system. The higher and smoother the curve is, the better the imaging quality of the system is and the stronger the ability to restore the real image is. Figure 2It can be seen that when the spatial frequency of the visible light band is 100lp / mm, the MTF of the imaging area near the center is greater than 0.7, and the imaging quality is good. Figure 3 From the defocus curve, we can see that the MTF concentration of this lens is good, which makes focusing easy. Figure 4 and Figure 5 It can be seen that the defocus curves at both high and low temperatures meet high resolution, the focus change of the defocus curve is small, and the thermal drift effect is stable;

[0056] Figure 6 Represented as a field curvature diagram, Figure 6 It can be seen that the field curvature value is controlled between -0.03mm and 0.03mm. The smaller the field curvature value, the better the imaging quality of the lens. Figure 7 It is expressed as F-THETA distortion diagram. The smaller the F-THETA distortion, the smaller the compression of the image edge. Figure 8 Represented as an imaging point diagram.

Claims

1. A large-target-area super-starlight train cabin monitoring optical system, characterized by: The large-target-area super starlight train cabin monitoring optical system comprises eight lenses, a filter, a protective glass and an image plane arranged in sequence from the object side to the image side, wherein the eight lenses are the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens in sequence from the object side to the image side; the first lens is a meniscus lens with a negative optical focal length; the second lens is a meniscus lens with a positive optical focal length; the third lens is a meniscus lens with a negative optical focal length; the fourth lens is a biconvex lens with a positive optical focal length; the fifth lens is a biconvex lens with a positive optical focal length; the sixth lens is a biconcave lens with a negative optical focal length; the seventh lens is a biconvex lens with a positive optical focal length; and the eighth lens is a concave-convex lens with a positive optical focal length. The focal length ratios of the first to eighth lenses to the focal lengths of the optical system lenses satisfy the following set relationships: 1.7 < |f1 / f| < 2.1, 15.3 < |f2 / f| < 15.7, 4.8 < |f3 / f| < 5.2, 2.5 < |f4 / f| < 3.0, 1.7 < |f5 / f| < 2.2, 1.5 < |f6 / f| < 1.8, 2.6 < |f7 / f| < 2.9, 11.1 < |f8 / f| < 11. 6; wherein f1 represents the effective focal length of the first meniscus lens, f2 represents the effective focal length of the second meniscus lens, f3 represents the effective focal length of the third meniscus lens, f4 represents the effective focal length of the fourth biconvex lens, f5 represents the effective focal length of the fifth biconvex lens, f6 represents the effective focal length of the sixth biconcave lens, f7 represents the effective focal length of the seventh biconvex lens, f8 represents the effective focal length of the eighth concave-convex lens, and f represents the effective focal length of the lens of the optical system.

2. The large-target-area super-starlight train cabin monitoring optical system according to claim 1, characterized in that: The refractive indexes of the third lens, the fifth lens, and the eighth lens are all greater than 1.45 and less than 1.62, and the Abbe coefficients are all greater than 50 and less than 65; the refractive indexes of the first lens and the fourth lens are all greater than 1.5 and less than 1.65, and the Abbe coefficients are all greater than 65 and less than 75.

3. The large-target-area super-starlight train cabin monitoring optical system according to any one of claims 1-2, characterized in that: The maximum holographic image height of the large-target super-starlight train cabin monitoring optical system is: IH≥9.06mm.

4. The large-target-area super-starlight train cabin monitoring optical system according to any one of claims 1-2, characterized in that: The aperture value of the large-target super-starlight train cabin monitoring optical system is: FNO≤1.

0.

5. The large-target-area super-starlight train cabin monitoring optical system according to any one of claims 1-2, characterized in that: The optical back focal length BFL and the effective focal length f of the large-target-area super starlight train cabin monitoring optical system satisfy the conditional formula: 1.2>BFL / f>1.

0.

6. The large-target-area super-starlight train cabin monitoring optical system according to any one of claims 1-2, characterized in that: The large-target-area super-starlight train cabin monitoring optical system satisfies the following conditional formula: 0.6<(h / 2) / (f×tan(FOV / 2))<0.75; Wherein: f represents the effective focal length of the optical system, FOV represents the maximum field of view of the optical system, and h represents the maximum image circle of the optical system.

7. The large-target-area super-starlight train cabin monitoring optical system according to any one of claims 1-2, characterized in that: The first lens has a convex surface facing the object side, and a concave surface facing the image side; the second lens has a concave surface facing the object side, and a convex surface facing the image side; the third lens has a concave surface facing the object side, and a convex surface facing the image side; the fourth lens has a convex surface facing the object side, and a convex surface facing the image side; the fifth lens has a convex surface facing the object side, and a convex surface facing the image side; the sixth lens has a concave surface facing the object side, and a concave surface facing the image side; the seventh lens has a convex surface facing the object side, and a convex surface facing the image side; the eighth lens has a convex surface facing the object side, and a concave surface facing the image side.

Images