Optical system, sensor system and lidar device

Abstract

An optical system disclosed in an embodiment of the invention comprises first to fourth lenses aligned along the optical axis from an object toward a sensing unit, wherein the power of the first lens is negative, the first to fourth lenses each include at least one spherical lens adjacent to the object and at least one aspherical lens adjacent to the sensing unit, and a distance between the first lens and the second lens may be such that a center distance is greater than an edge distance, and the third lens may include a convex object-side surface and a convex sensor-side surface on the optical axis.

Description

Optical systems, sensor systems and lidar devices

[0001] The present invention relates to an optical system and a sensor system having the same. The present invention relates to a receiving optical system for LIDAR (Light detection and ranging) and a device having the same. The present invention relates to a mobile object having a receiving optical system and system for LIDAR.

[0002] ADAS (Advanced Driving Assistance System) is an advanced driver assistance system that assists the driver in driving. It consists of sensing the situation ahead, judging the situation based on the sensed results, and controlling the vehicle's behavior based on the situation judgment. For example, ADAS sensor devices detect a vehicle ahead and recognize lanes. After the target lane, target speed, and forward target are determined, the vehicle's ESC (Electrical Stability Control), EMS (Engine Management System), and MDPS (Motor Driven Power Steering) are controlled. Representative examples of ADAS can be implemented as automatic parking systems, low-speed city driving assistance systems, and blind spot warning systems.

[0003] With the recent surge in interest in autonomous vehicles, demand for LiDAR (Light Detection And Ranging) sensors, a key component of autonomous vehicles, is growing. Currently, LiDAR is used only in high-end, expensive vehicles, but its adoption in general-purpose vehicles is expected to increase as manufacturing costs decline.

[0004] Ultra-small and ultra-light lidar technology can be used not only as a sensor for unmanned mobile devices, but also in satellites and aerospace for observing the Earth's topography and environment, unmanned vehicles, transporters, cranes, and robots used in factories and shipyards, and it is expected to appear in the form of complex or cooperative operation between mobile devices through an integrated approach in the land, aviation, and marine industries. Therefore, the development of an optical system for ultra-small and ultra-light lidar to implement ultra-small and ultra-light lidar is urgent.

[0005] The present invention provides an optical system having improved optical characteristics and a sensor system having the same. The present invention provides a wide-angle receiving optical system and a sensor system having the same. The present invention provides a receiving optical system, a sensor system, and a lidar device having improved thermal compensation characteristics.

[0006] An optical system according to an embodiment of the invention includes first to fourth lenses aligned along an optical axis from an object toward a sensing unit, wherein the power of the first lens is negative, the first to fourth lenses include at least one spherical lens adjacent to the object and at least one aspherical lens adjacent to the sensing unit, and a distance between the first lens and the second lens is such that a center distance is greater than an edge distance, and the third lens may include a convex object-side surface and a convex sensor-side surface on the optical axis.

[0007] According to an embodiment of the invention, the object-side surface of the first lens is convex on the optical axis, and the effective diameter of the object-side surface of the first lens may be the largest among the effective diameters of the object-side surfaces and the sensor-side surfaces of the first to fourth lenses. The first lens may include a sensor-side surface that is concave on the optical axis, and the second lens may include an object-side surface that is concave on the optical axis. The fourth lens may have a biconvex shape on the optical axis, and the object-side surface of the fourth lens may have a critical point between the optical axis and an end of the effective area. The first aperture may be disposed on the periphery of an area between the second lens and the third lens. A center distance between the second and third lenses may be smaller than an edge distance. The second aperture may be disposed on the periphery of the object-side surface of the first lens.

[0008] According to an embodiment of the invention, the first to fourth lenses may be made of glass, the object-side surface and the sensor-side surface of each of the first and third lenses may be spherical, the object-side surface and the sensor-side surface of the third lens may be aspherical, and the object-side surface and the sensor-side surface of the fourth lens may be aspherical.

[0009] According to an embodiment of the invention, the power of the second to fourth lenses may have a positive value. The focal length of the second lens may be the largest among the absolute values ​​of the focal lengths of the first to fourth lenses.

[0010] An optical system according to an embodiment of the invention includes a first lens having a convex object-side surface and a concave sensor-side surface on an optical axis; a second lens disposed on a sensor-side of the first lens; a third lens disposed on a sensor-side of the second lens; and a fourth lens disposed on a sensor-side of the third lens, wherein among the first to fourth lenses, a lens having a maximum effective diameter is made of glass, a lens having an aspherical object-side surface and a sensor-side surface among the first to fourth lenses is made of glass, and the second lens has a minimum effective diameter among the first to fourth lenses and may have a meniscus shape convex on the optical axis toward the image sensor.

[0011] According to an embodiment of the invention, the composite focal length of the first and second lenses may have a positive value, and the composite focal length of the third and fourth lenses may have a negative value.

[0012] According to an embodiment of the invention, the central thickness of the first lens may be the smallest among the central thicknesses of the first to fourth lenses. The first lens may have negative refractive power, and the second to fourth lenses may have positive refractive power. The first to fourth lenses may be alternately arranged as spherical lenses and aspherical lenses.

[0013] According to an embodiment of the invention, the center distance between the first lens and the second lens is CG1, the center thickness of the first lens is CT1, and is thinner than the center thickness of each of the second and third lenses, and the mathematical formula: 1 < CG1 / CT1 < 4 can be satisfied.

[0014] According to an embodiment of the invention, the radii of curvature of the object-side surface and the sensor-side surface of the first lens are L1R1 and L2R1, and the effective diameters of the object-side surface and the sensor-side surface of the first lens are CA11 and CA12, and the mathematical formula: 5 < (CA11*L1R1) / (CA12*L1R2) < 15 can be satisfied.

[0015] According to an embodiment of the invention, a first aperture is provided on a periphery between the second lens and the third lens; and a second aperture is provided on a periphery of an object-side surface of the first lens, wherein a hole diameter of the first aperture is CA_ST1, a hole diameter of the second aperture is CA_ST2, and a mathematical formula: 1 < CA_ST2 / CA_ST1 < 5 can be satisfied.

[0016] According to an embodiment of the invention, a camera module includes: a sensing unit; first to fourth lenses aligned with an optical axis from an object toward the sensing unit; and an optical filter disposed between the sensing unit and the fourth lens, wherein the power of the first lens is negative, the power of the fourth lens is positive, a diagonal field of view of the optical system is 100 degrees or more, and a lens adjacent to the sensing unit among the first to fourth lenses has an aspheric surface on an object-side surface and a sensor-side surface, the first to fourth lenses are made of glass, and an optical axis distance from the center of the sensor-side surface of the fourth lens to the surface of the image sensor is BFL, and half of the diagonal length of the sensing unit is ImgH, and mathematical equations: 4 < TTL / ImgH < 11 and 0 < BFL / ImgH < 3 can be satisfied.

[0017] In an embodiment, improved optical properties can be achieved. Specifically, in an optical system according to an embodiment, the bandpass filter can be positioned near an aperture stop to minimize the incident angle of light entering the filter. Accordingly, the transmittance range of the bandpass filter can be broadly utilized depending on the incident angle of light on the bandpass filter.

[0018] The optical system of the invention's lidar can maximize the effect of receiving light emitted from the transmitting optical system.

[0019] The optical system of the lidar of the invention can have good optical characteristics in a temperature range from low to high temperature. Specifically, a plurality of lenses included in the optical system can have set materials, refractive powers, and refractive indices. Accordingly, when the refractive index of each lens changes due to temperature changes, and the focal length of each lens changes as a result, mutual compensation can be made by the aspherical lens and the spherical lens made of glass. In other words, the optical system can effectively distribute refractive power in a temperature range from low to high temperature, and can prevent or minimize changes in optical characteristics in a temperature range from low to high temperature. Therefore, the optical system and sensor system according to the embodiment can maintain improved optical characteristics in a variety of temperature ranges.

[0020] The optical system of the inventive lidar may have lenses with set thicknesses, refractive powers, and spacings from adjacent lenses. Accordingly, the optical system and sensor system according to the embodiment may have improved MTF characteristics, aberration control characteristics, resolution characteristics, etc. within a set field of view range, and may exhibit good optical performance in the periphery of the field of view.

[0021] The optical system and sensor system according to the embodiment can achieve excellent optical characteristics while satisfying a set angle of view through a combination of spherical and aspherical lenses made of glass. This allows the optical system to provide a slimmer vehicle sensor system. Accordingly, the optical system and sensor system can be used in various applications and devices, and can maintain excellent optical characteristics even in harsh temperature environments, such as when exposed to the exterior of a vehicle or in the high temperatures of a vehicle interior during the summer.

[0022] Fig. 1 is a side cross-sectional view of an optical system according to an embodiment.

[0023] Figure 2 is a table showing the lens characteristics of the optical system of Figure 1.

[0024] Fig. 3 is a table showing the aspherical coefficients of lenses in the optical system of Fig. 1.

[0025] Fig. 4 is a graph showing data of the diffraction MTF (Modulation Transfer Function) of the optical system of Fig. 1.

[0026] Fig. 5 is a graph showing data on the aberration characteristics of the optical system of Fig. 1.

[0027] Fig. 6 is a block diagram showing a sensor system having the optical system of Fig. 1.

[0028] FIG. 7 is a drawing showing an example of measuring an object in a vehicle having a sensor system of the invention.

[0029] Fig. 8 is a drawing showing an example of surrounding surveillance in a vehicle having a sensor system of the invention.

[0030] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. The technical idea of ​​the present invention is not limited to some of the embodiments described, but can be implemented in various different forms, and one or more of the components between the embodiments can be selectively combined or substituted within the scope of the technical idea of ​​the present invention. In addition, terms (including technical and scientific terms) used in the embodiments of the present invention can be interpreted as having a meaning that can be generally understood by a person having ordinary skill in the technical field to which the present invention belongs, unless explicitly and specifically defined and described, and terms that are commonly used, such as terms defined in a dictionary, can be interpreted in consideration of the contextual meaning of the related technology.

[0031] The terminology used in the embodiments of the present invention is for the purpose of describing the embodiments and is not intended to limit the present invention. In this specification, the singular may also include the plural unless specifically stated in the phrase, and when it is described as “A and (or at least one (or more) of B, C)”, it may include one or more of all combinations that can be combined with A, B, and C. In addition, when describing components of the embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the components from other components, and are not limited by the nature, order, or sequence of the components. In addition, when it is described that a component is “connected,” “coupled,” or “connected” to another component, it may include not only cases where the component is directly connected, coupled, or connected to the other component, but also cases where the component is “connected,” “coupled,” or “connected” due to another component between the component and the other component. Additionally, when it is described as being formed or arranged "above or below" each component, "above" or "below" includes not only cases where the two components are in direct contact with each other, but also cases where one or more other components are formed or arranged between the two components. Furthermore, when it is expressed as "above" or "below", it can include the meaning of a downward direction as well as an upward direction based on one component.

[0032] In the description of the invention, the "object-side surface" may mean a surface of a lens facing the object side based on the optical axis (OA), and the "sensor-side surface" may mean a surface of a lens facing the imaging surface (surface of the sensing unit) based on the optical axis. The convexity of one surface of the lens may mean a convex shape in the optical axis or the paraxial region, and the concaveness of one surface of the lens may mean a concave shape in the optical axis or the paraxial region. The radius of curvature, center thickness, and optical axis spacing between lenses described in the table for lens data may mean values ​​(unit: mm) in the optical axis. The vertical direction may mean a direction perpendicular to the optical axis, and the end of a lens or lens surface may mean the end of an effective area of ​​a lens through which incident light passes. The size of the effective diameter of the lens surface may have a measurement error of up to ±0.4 mm depending on the measurement method, etc. The above-mentioned near-axis region refers to a very narrow region near the optical axis, and is a region where the distance a light ray falls from the optical axis (OA) is almost 0. Hereinafter, the optical axis may include the center of each lens or a very narrow region near the optical axis.

[0033]

[0034] Fig. 1 is a side cross-sectional view of an optical system according to an embodiment, Fig. 2 is a table showing lens characteristics of the optical system of Fig. 1, and Fig. 3 is a table showing aspherical coefficients of lenses in the optical system of Fig. 1.

[0035] Referring to FIGS. 1 to 3, an optical system (100) and a sensor system having the same may be mounted inside or outside a moving vehicle to monitor a driver or sense external objects or lanes. Each of the lenses in the optical system (100) may be made of glass. The coefficient of linear expansion of glass lenses is smaller than that of plastic materials. Therefore, the lenses of the optical system (100) may be made of glass to suppress changes in the focal imaging position due to temperature changes. However, when the optical system is configured with spherical glass lenses, there is a limit to reducing the number of lenses, and there is a limit to size reduction and weight reduction. The optical system (100) of an embodiment of the invention may include a spherical lens and an aspherical lens. Here, the spherical lens is a lens in which at least one or both of the object-side surface and the sensor-side surface of the lens is spherical. The aspherical lens is a lens in which at least one or both of the object-side surface and the sensor-side surface of the lens is aspherical. The optical system (100) may include a spherical glass lens and an aspherical glass lens. In addition, since it includes an aspherical lens, the optical system (100) may have a reduced total track length (TTL), and may be capable of providing good correction for various aberrations such as spherical aberration and chromatic aberration due to the aspherical lens. In addition, the aspherical lens may minimize distortion in the peripheral portion of the sensing unit (151). The aspherical lens may be injection-molded from a glass material. Alternatively, the aspherical lens may be formed from a plastic material.

[0036]

[0037] The optical system (100) may include n lenses, the nth lens being the last lens adjacent to the sensing unit (151), and the (n-1)th lens being the lens closest to the last lens. The n is an integer greater than or equal to 4, for example, in the range of 3 to 6 or 3 to 5. The ratio of spherical lenses to aspherical lenses in the n lenses may be 1:1 or 3:1. Preferably, the number of spherical lenses may be equal to or greater than the number of aspherical lenses. Accordingly, an increase in the price of the optical system (100) may be suppressed.

[0038] In the optical system (100), the first lens (101) closest to the object may be made of glass. The glass material exhibits little change in expansion and contraction due to external temperature changes, and its surface is not easily scratched, thereby preventing surface damage. Accordingly, in the optical system (100), the first lens (101) on the object side may be a spherical lens, and the nth lens may be arranged as an aspherical lens. Since the nth lens in the optical system (100) is arranged as an aspherical lens, various aberrations of the light incident on the sensing unit (151) may be corrected.

[0039] The first lens closest to the object in the optical system (100) may be arranged with a glass material, and the lenses adjacent to the outside have a smaller rate of contraction and expansion according to temperature change than those made of plastic, thereby preventing a deterioration of optical characteristics according to temperature change within the lens barrel. The optical system (100) may have the last lens (104) closest to the sensing unit (151) arranged with a glass mold material or an aspherical surface, and the last lens (104) has a smaller rate of contraction and expansion according to temperature change than those made of plastic, thereby preventing a deterioration of optical characteristics according to temperature change within the lens barrel.

[0040]

[0041] Each lens of the optical system (100) may have an object-side surface and a sensor-side surface. The lenses may include lenses whose object-side surface and sensor-side surface are spherical, and lenses whose object-side surface and sensor-side surface are aspherical. The object-side aspherical lens may be arranged between spherical lenses. The sensor-side spherical lens may be arranged between aspherical lenses. Here, the object-side is an area located on the object side relative to any lens, and the sensor-side is an area located on the sensor side relative to any lens. Since the optical system (100) arranges the aspherical lens adjacent to the sensing unit (151), various aberrations can be corrected. The spherical lens and the aspherical lens may be made of glass.

[0042]

[0043] Within the optical system (100), a lens surface having a maximum effective diameter may be arranged on the first lens (101) closest to the object. The first lens (101) may be made of glass and may be a spherical lens. Within the optical system (100), a lens having a minimum effective diameter may be arranged between an aperture (ST) and the first lens (101). The lens having the minimum effective diameter may be an aspherical lens. In addition, the average effective diameter of the aspherical lenses may be smaller than the average effective diameter of the spherical lenses. Here, the effective diameter of the lens is an average value of the effective diameter of the object-side surface of each lens and the effective diameter of the sensor-side surface. By adjusting the effective diameters of each lens, the optical system (100) may be miniaturized.

[0044] Each of the above lenses may include an effective area and an ineffective area. The effective area may be an area through which light incident on each of the lenses passes. That is, the effective area may be defined as an effective area or effective diameter through which the incident light is refracted to implement optical characteristics. The ineffective area may be arranged around the periphery of the effective area. The ineffective area may be an area through which effective light is not incident from the plurality of lenses. That is, the ineffective area may be an area unrelated to the optical characteristics. In addition, an end of the ineffective area may be an area fixed to a lens barrel (not shown) that accommodates the lens.

[0045] Among the lenses of the optical system (100), the lens having the maximum center thickness may be a spherical lens, and the lens having the maximum edge thickness may be a spherical lens. The average of the center thicknesses of the spherical lenses may be greater than the average of the center thicknesses of the aspherical lenses. The aspherical lenses having thin thicknesses may reduce the TTL (Total Top Length), and may refract the incident light into various paths. In the optical system (100), the TTL may be more than 4 times the ImgH (Image Height), for example, more than 4 times and less than 12 times. The TTL (Total Track Length) is the distance from the center of the object-side surface (S1) of the first lens (101) to the upper surface of the sensing unit (151) on the optical axis (OA). The above ImgH is the distance from the center of the effective area of ​​the sensing unit (151) to the diagonal end, or half the diagonal length of the effective area of ​​the sensing unit (151). In addition, the effective diameter of at least one of the lenses may be smaller than the diagonal length of the sensing unit (151). In the optical system (100), the effective focal length (EFL) is less than 20 mm and the field of view (FOV) is 75 degrees or more or 100 degrees or more, so that it can be provided as a standard optical system in a vehicle sensor system. For example, the optical system and sensor system according to the embodiment can be applied to a sensing device for an ADAS (Advanced Driving Assistance System) installed inside or outside a vehicle.

[0046] The optical system (100) above can satisfy the condition of 2 < TTL / (2*ImgH) < 6. Accordingly, the central thickness of each lens along the optical axis (OA) can be increased and the size of the sensing unit (151) can be reduced, thereby providing a vehicle lens optical system. In addition, temperature compensation can be possible in a temperature range that serves as a temperature reliability evaluation standard for automotive electrical components for use in vehicle cameras, that is, from -45°C to +120°C. The lens must be configured so that the focus of the lens remains within the set range even when the lens expands or contracts due to temperature changes. The optical system (100) can be configured with lenses made of a glass material that can perform the aforementioned temperature compensation and has an effective focal length (EFL) of less than 20 mm, for example, in a range of 1 mm to 15 mm or a range of 1 mm to 10 mm.

[0047] Within the optical system (100), the number of lenses having positive (+) refractive power may be equal to or greater than the number of lenses having negative (-) refractive power. The number of lenses having positive (+) refractive power may be 50% or more, for example, 55% or more, of the total number of lenses. Since this optical system (100) is a mixture of spherical lenses and aspherical lenses made of glass, various aberrations can be corrected, thereby preventing deterioration of optical performance.

[0048]

[0049] The optical system (100) may include an optical filter (155), and the optical filter (155) may be arranged between the last lens (104) and the sensor unit (151). The optical filter (155) may transmit light, for example, a laser wavelength, emitted from the transmission optical system and reflected from the subject, and block other wavelengths. The transmitted laser wavelength may be in the range of 890 nm to 960 nm or 940 nm ± 10 nm. As another example, the laser wavelength may be in the range of 1550 nm ± 10 nm. The optical filter (155) may be a bandpass filter. As another example, the optical filter (155) may be arranged between two different lenses. The optical filter (155) may perform an operation of transmitting light of a specific wavelength (for example, a wavelength range of approximately 800 to 1000 nm) or light belonging to a specific band, and blocking light outside the specific wavelength. The optical filter (155) can actively perform a filtering operation. To this end, the optical filter (155) may include an active device that, in response to an external control signal, allows only light having a specific center wavelength to pass through and blocks light having other wavelengths. The control signal provided to the optical filter (155) may include information about the center wavelength of the light to pass through the active device, wherein the center wavelength may correspond to the center wavelength of the light emitted from the transmission optical system. Consequently, the control signal provided to the optical filter (155) is a control signal that matches the center wavelength of the light emitted from the transmission optical system with the center wavelength of the light to pass through the active device of the optical filter (155). Due to the active device included in the optical filter (155), the optical filter (155) can selectively allow only desired light to pass through and block other noise light, including natural light. Therefore, the signal-to-noise ratio (S / N) of the lidar system can be increased. As an example of the above active device, the optical filter may include a tunable bandpass filter.The above-mentioned tunable bandpass filter may operate in a liquid crystal or acousto-optic manner. The optical filter (155) is a TOF optical system that utilizes a specific wavelength or a designated wavelength band, and can suppress the generation of stray light by blocking light outside the designated wavelength band from entering the sensor unit.

[0050]

[0051] The optical system (100) and the camera module may have an F number of 1.5 or less. The F number may be in the range of 0.6 to 1.5 or in the range of 0.9 to 1.3. In configuring such a bright optical system, the camera module may include at least five lenses, and may be miniaturized and achieve good optical performance by using at least one aspherical lens. By adjusting the refractive index of the lenses within the optical system (100), it is possible to prevent degradation of optical performance for temperature changes from -45 to 120 degrees and to optimize thermal compensation. In addition, by adjusting the Abbe number, it is possible to minimize the deviation of the spot size of incident light, i.e., to minimize the spot diagram size.

[0052] In an optical system according to an embodiment of the invention, the angle of view may be 100 degrees or more, for example, in a range of 100 degrees or more to 150 degrees, preferably, in a range of 115 degrees to 135 degrees. The diagonal length of the sensing unit (151) may be 6 mm or more, for example, in a range of 6 mm to 12 mm or in a range of 7 mm to 11 mm, and may be greater than the sensor height in the vertical direction. The invention can provide a vehicle lidar device that suppresses a change in a focal imaging position due to temperature change by stacking glass lenses and corrects various aberrations by providing an aspherical lens.

[0053]

[0054] The embodiment includes an optical system applied to a lidar device, wherein the first lens (101) may be provided as a glass material. This is because glass has the advantage of being scratch-resistant and insensitive to external temperatures compared to plastic materials. In order to more effectively prevent scratches caused by foreign substances or when placed inside a vehicle, a glass lens may be used as the first lens (101), and the object-side surface of the first lens (101) may have a convex shape to prevent the accumulation of foreign substances. The lidar device can detect the distance, direction, speed, temperature, material distribution, and concentration characteristics to an object when the vehicle is running. Such a lidar device can be used for an advanced driver assistance system (ADAS).

[0055] The optical system (100) according to the embodiment may further include a reflective member (not shown) for changing the path of light. The reflective member may be implemented as a prism that reflects incident light toward the lenses. Hereinafter, the optical system according to the embodiment will be described in detail. The lenses arranged between the aperture (ST1) and the object may be defined as a first lens group, and the lenses arranged between the aperture (ST1) and the sensor unit (151) may be defined as a second lens group. The power of the first lens group may have a negative value, and the power of the second lens group may have a positive value. The power is the reciprocal of the refractive power.

[0056] The aperture (ST1) arranged between the above lenses can be defined as a first aperture, and is arranged around the object-side surface (S1) of the first lens (101), and the aperture that controls the amount of light incident on the object-side surface (S1) of the first lens (101) can be defined as a second aperture (not shown).

[0057] The optical system (100) may include first lenses (101) to fourth lenses (104) aligned from the object side toward the sensor side along the optical axis (OA). The first to fourth lenses (101-104) may be defined as a lens unit. The lens unit and the sensor unit (151) may be defined as a camera module, a sensor system, or a lens assembly. Light corresponding to object information may pass through the first lenses (101) to fourth lenses (104) and the optical filter (155) and be incident on the sensing unit (151). The aperture (ST1) may be arranged around the periphery of the sensor-side surface of the second lens (102) or the periphery of the object-side surface (S5) of the third lens (103). The position of the above aperture (ST1) may be arranged closer to the sensor side surface (S4) of the second lens (102) than to the object side surface (S5) of the third lens (103).

[0058] Each of the first to fourth lenses (101-104) may have a positive (+) or negative (-) refractive power on the optical axis (OA). At least one or all of the first to fourth lenses (101-104) may include a plastic material or a glass material, and may be, for example, a glass material.

[0059] The first lens (101) may have a negative (-) refractive power. The first lens (101) may be made of glass. The first lens (101) made of glass can reduce changes in the center position and radius of curvature due to temperature changes in the surrounding environment, and can protect the incident side surface of the optical system (100). The first lens (101) is made of a non-injection-molded glass material. The object-side first surface (S1) of the first lens (101) on the optical axis (OA) may be convex, and the sensor-side second surface (S2) may be concave. The first surface (S1) and the second surface (S2) may have a spherical surface. The first lens (101) may have a meniscus shape that is convex toward the object side. Alternatively, the first surface (S1) on the optical axis (OA) may have a concave shape, and the second surface (S2) may have a convex shape. Alternatively, the first lens (101) may have a concave shape on both sides.

[0060] Since the first surface (S1) of the first lens (101) has a convex shape and the second surface (S2) has a concave shape, the incident light can be refracted in a direction close to the optical axis (OA), and an increase in the effective diameter of the second lens (102) can be suppressed. When the refractive index of the first lens (101) is Nd1, the condition of 1.7 < Nd1 or 1.75 < Nd1 < 2.1 can be satisfied.

[0061] The second lens (102) may be arranged between the first lens (101) and the third lens (103). The second lens (102) may have positive (+) refractive power. The second lens (102) may be an aspherical lens made of glass. On the optical axis (OA), the object-side third surface (S3) of the second lens (102) may be concave, and the sensor-side fourth surface (S4) may be convex. The third and fourth surfaces (S3, S4) may be aspherical, and, as shown in FIG. 4, exhibit conic constants (K) of L2S1 and L2S2 and aspherical coefficients from the 4th to the 22nd order (AJ). The third and fourth surfaces (S3, S4) may be provided without critical points from the optical axis (OA) to the ends of the effective areas. Alternatively, the third surface (S3) may be convex and the fourth surface (S4) may be concave. Alternatively, the second lens (102) may be convex on both sides or concave on both sides.

[0062] The center spacing (CG1) on the first and second lenses (101, 102) can be increased by the shapes of the first and second lenses (101, 102). The aspherical second lens (102) can be placed between the spherical first and third lenses (101, 103), and the effective diameter of the third lens (103) can be increased compared to the effective diameter of the second lens (102). The center spacing (CG10) between the first and second lenses (101, 102) can be greater than the edge spacing, and can gradually become smaller from the center toward the edge.

[0063] The third lens (103) may have positive (+) refractive power on the optical axis. The third lens (103) may include a glass material. The third lens (103) may be a spherical lens made of glass. On the optical axis, the fifth surface (S5) on the object side of the third lens (103) may be convex, and the sixth surface (S6) on the sensor side may be convex. The third lens (103) may have a shape in which both sides are convex on the optical axis (OA). Alternatively, the third lens (103) may have a meniscus shape that is convex on the object side or the sensor side. Alternatively, the third lens (103) may have a shape in which both sides are concave on the optical axis. At least one or both of the fifth surface (S5) and the sixth surface (S6) may be spherical. At least one or both of the fifth side (S5) and the sixth side (S6) can be provided without a critical point from the optical axis (OA) to the end of the effective area.

[0064] When the refractive indices of the third and fourth lenses (103, 104) are Nd3 and Nd4, the condition of Nd4 < Nd3 can be satisfied. When the Abbe numbers of the second and third lenses (102, 103) are Vd2 and Vd3, the condition of Vd2 < Vd3 can be satisfied.

[0065] The above aperture (ST1) can control the amount of light incident on the optical system (100). The lens surface on which the aperture (ST1) is arranged can more efficiently control and guide the amount of light of the optical system (100). As in the embodiment, the aperture (ST1) can be arranged on the periphery of the sensor-side surface of the second lens (102) or the object-side surface of the third lens (103). Alternatively, at least one lens selected from the plurality of lenses, for example, the sensor-side surface of the second lens (102), can function as an aperture.

[0066] Since the third lens (103) located on the sensor side of the aperture (ST1) has positive refractive power, the third lens (103) can refract incident light in the direction of the optical axis and suppress the effective diameter of the fourth lens (104) from increasing. Since the power of the third and fourth lenses (103, 104) located on the sensor side of the aperture (ST1) can have a positive value, the optical system can reduce TTL within the field of view range.

[0067]

[0068] The fourth lens (104) may have positive (+) refractive power. The fourth lens (104) may include a glass material. The fourth lens (104) may be an aspherical lens. On the optical axis, the seventh surface (S7) on the object side of the fourth lens (104) may be convex, and the eighth surface (S8) on the sensor side may have a convex shape. The fourth lens (104) may have a convex shape on both sides. Alternatively, the fourth lens (104) may have a meniscus shape that is convex on the object side or the sensor side. Alternatively, the fourth lens (104) may have a concave shape on both sides. The above seventh surface (S7) and the above eighth surface (S8) may be aspherical, and as shown in FIG. 4, they represent the conic constant (K) of L2S1 and L2S2 and the aspherical coefficients from the 4th to the 22nd order (AJ).

[0069] The seventh surface (S7) of the fourth lens (104) may have at least one critical point from the optical axis (OA) to the end of the effective area. The position of the critical point may be arranged at 60% or more, for example, in the range of 60% to 90%, of the effective radius with respect to the optical axis (OA). For example, the position of the critical point may be arranged at 3 mm or more, for example, in the range of 3 mm to 4.5 mm with respect to the optical axis. The eighth surface (S8) may be provided without a critical point from the optical axis (OA) to the end of the effective area. Here, the critical point may be a point where the sign of the gradient value with respect to the optical axis (OA) and the direction perpendicular to the optical axis (OA) changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the gradient value is 0. In addition, the critical point may be a point where the gradient value of a tangent passing through the lens surface increases and then decreases, or a point where the gradient value decreases and then increases. Here, the eighth surface (S8) may have an absolute value of a radius of curvature on the optical axis (OA) that is greater than the radius of curvature of the seventh surface (S7), thereby refracting light toward the center and periphery of the sensor unit (151). Alternatively, the eighth surface (S8) may have at least one critical point from the optical axis (OA) to the end of the effective area.

[0070] The fourth lens (104) may be an aspherical lens closest to the sensing unit (151). The fourth lens (104) can improve aberrations such as spherical aberration and chromatic aberration by having an aspherical surface on the lens surface, and can control the influence on the resolution. The aspherical surface of the lens surface adjacent to the sensing unit (151) can improve optical performance, and for example, can improve aberration characteristics and prevent resolution degradation.

[0071] The effective diameter of the optical filter (155) located on the sensor side of the fourth lens (104) may be smaller than the effective diameter of the eighth surface (S8) of the fourth lens (104). The optical filter (155) transmits a laser beam reflected by a subject after being emitted from the transmission optical system of the lidar device, and blocks beams of other wavelengths. The optical filter (155) may transmit light, for example, a laser wavelength, reflected from a subject after being emitted from the transmission optical system, and block other wavelengths. The transmitted laser wavelength may be in the range of 890 nm to 960 nm or 940 nm ± 10 nm. As another example, the laser wavelength may be in the range of 1550 nm ± 10 nm.

[0072] By controlling the effective diameter of each of the above lenses (101-104), the optical system (100) can control the incident light to compensate for the deterioration of the resolution and optical characteristics due to temperature changes, improve the chromatic aberration control characteristics, and improve the vignetting characteristics of the optical system (100). As another example, at least one of the object-side surface and the sensor-side surface of the second and fourth lenses (102, 104) can have a free-form surface, i.e., a non-rotationally symmetrical surface.

[0073] The center thickness (CT3) of the third lens (103) may be greater than the center thicknesses (CT1, CT2) of the first and second lenses (101, 102). The center thickness (CT4) of the fourth lens (104) may be greater than the center thickness of the first lens (101) and less than the center thickness (CT3) of the third lens (103). The center spacing (CG1) between the first and second lenses (101, 102) may be greater than the center thickness (CT3) of the third lens (103). The center spacing (CG2) between the second and third lenses (102, 103) and the center spacing (CG3) between the third and fourth lenses (103, 104) may be greater than the center thickness (CT1) of the first lens (101). The center spacing (CG3) between the third and fourth lenses (103, 104) may be smaller than the center thickness (CT3) of the third lens (103) and the center thickness (CT4) of the fourth lens (104). The center spacing (CG2) between the second and third lenses (102, 103) may be smaller than the edge spacing.

[0074] When the radius of curvature of each lens surface on the optical axis is described as an absolute value, the lens surface having the minimum radius of curvature may be the second surface (S2) of the first lens (101). The lens surface having the maximum radius of curvature (absolute value) may be the sixth surface (S6) of the third lens (103). Accordingly, the amount of incident light of the first lens (101) can be increased, the center distance (CG1) between the first and second lenses (101, 102) can be adjusted, and the position of the aperture (ST1) can be set. The lens having the largest difference in the radius of curvature between the object-side surface and the sensor-side surface of each lens is the first lens (101), and the difference in effective diameter between the first and second lenses (101, 102) may be the largest among the differences in effective diameters of adjacent lenses.

[0075] Since the object-side first surface (S1) of the first lens (101) is provided with a radius of curvature of 10 mm or more and more than four times the radius of curvature of the second surface (S2), distortion of reflected light can be reduced and the depth of field can be further increased, thereby improving image quality under low-light conditions.

[0076] The optical system (100) or sensor system may include a sensing unit (151). The sensing unit (151) may detect light that sequentially passes through the lenses. The sensing unit (151) may detect light and convert it into an electrical signal. The sensing unit (151) may obtain various information about the subject. The sensing unit (151) may detect time delay or phase difference information from the incident light, and based on this, may obtain distance information to the subject, position information of the subject, depth image of the subject, etc. To this end, the sensing unit (151) may include a device that may detect incident light, such as an image sensor, for example, a Charge Coupled Device (CCD) or a Complementary Metal Oxide Semiconductor (CMOS). As another example, the sensing unit may include a Time to Digital Converter (TDC). Here, the effective length of the sensing unit (151) is the maximum length in the diagonal direction orthogonal to the optical axis (OA), and here, the number of lenses having an effective diameter larger than the effective length of the sensing unit (151) may be 3, and the number of lenses having an effective diameter smaller than the effective length of the sensing unit (151) may be 1.

[0077] A cover glass (not shown) is placed between the optical filter (155) and the sensing unit (151), and protects the upper portion of the sensing unit (151) and can prevent a decrease in the reliability of the sensing unit (151). The cover glass (not shown) can be removed.

[0078] Fig. 2 is an example of lens data of the optical system of the embodiment of Fig. 1. As shown in Fig. 2, the radius of curvature of the optical axis (OA) of the first to fourth lenses (101-104), the center thickness (CT) of the lenses, the center gap (CG) between the lenses, the refractive index at the d-line, the Abbe number, and the size of the effective diameter can be set.

[0079] As shown in Fig. 3, among the lenses of the optical system of Fig. 1, the lens surfaces (S3, S4, S7, S8) of the second and fourth lenses (102, 104) may include aspherical surfaces having a radius of curvature (R), a conic constant (K), and an aspherical coefficient (AJ) of the 4th to 22nd order. As described above, an aspherical surface having a 22nd aspherical coefficient (a non-zero value) can significantly change the aspherical shape of the periphery, and thus can effectively correct the optical performance of the periphery of the field of view (FOV).

[0080] The effective focal length of the optical system (100) is F, and the focal lengths of the first to fourth lenses (101-104) can be defined as F1-F4. The focal length (F1) of the first lens (101) has negative refractive power, and the focal lengths (F2, F3, F4) of the second, third, and fourth lenses (102, 103, 104) can have positive refractive power. The focal length of the second lens (102) can be the largest among the absolute values ​​of the focal lengths of the lenses. The focal length of the second lens (102) can be greater than the sum of the absolute values ​​of the focal lengths of the lenses.

[0081] The composite focal length of the first and second lenses (101, 102) is F12, and the composite focal length of the third and fourth lenses (103, 104) is F34. These focal lengths can satisfy the following conditions.

[0082] Condition 1: F < │F1│ < F3 Condition 2: F < F3 < F2

[0083] Condition 3: F < F4 < F2 Condition 4: F < F34 < │F12│ < F4

[0084]

[0085] Since the aspherical lens in the optical system (100) is arranged on the sensor side of the spherical lens, the chromatic aberration occurring in the spherical lens can be corrected by the aspherical lens. In addition, by satisfying that the signs of the focal lengths between the first lens (102) and the second lens (102) arranged in series are opposite to each other and the refractive index difference is 0.3 or less, the chromatic aberration occurring in the spherical lens can be compensated for by the aspherical lens. In addition, by satisfying that the difference in the focal lengths between the third lens (103) and the fourth lens (104) arranged in series is 10 or less and the refractive index difference is 0.3 or less, the chromatic aberration occurring in the spherical lens can be compensated for by the aspherical lens. The focal length of the second lens (102) is the largest among the lenses and may be 100 mm or more, for example, in the range of 100 mm to 300 mm. Accordingly, the optical system can have improved MTF characteristics, aberration control characteristics, resolution characteristics, etc. in the set angle of view range, and can have good optical performance in the periphery of the angle of view.

[0086] The optical axis distance between the last lens, i.e., the fourth lens (104), and the surface of the image sensor, which is the sensor unit (151), is BFL. BFL can satisfy the following conditions, and * indicates multiplication.

[0087] Condition 1: CT1 < BFL < CT*4 Condition 2: ImgH < BFL < ImgH*2

[0088] Condition 3: CG1 < BFL < CT2*2

[0089] TTL is the optical axis distance from the object side of the first lens (101) to the surface of the sensor unit (151), and FOV is the angle of view of the optical system. TTL and FOV can satisfy the following conditions.

[0090] Condition 1: BFL*ImgH < TTL Condition 2: F3 < TTL

[0091] Condition 3: TTL*3 < FOV < TTL*5 Condition 4: FOV < F2

[0092]

[0093] Fig. 4 is a graph showing the diffraction MTF in the optical system of Fig. 1, and is a graph showing the modulation of the luminance according to the spatial frequency. That is, Fig. 4 shows the diffraction MTF at room temperature, and is a graph measuring the luminance ratio according to the position of the defocusing position. Fig. 5 is a graph showing the aberration characteristics in the optical system of Fig. 1. In the aberration graph of Fig. 5, it is a graph measuring spherical aberration (longitudinal spherical aberration), astigmatic field curves, and distortion from left to right. In Fig. 5, the X-axis can represent the focal length (mm) and the degree of distortion (%), and the Y-axis can represent the height of the image. In addition, the graph for spherical aberration is a graph for light in the wavelength bands of about 930 nm, about 940 nm, and about 950 nm, and the graph for astigmatism and distortion is a graph for light in the wavelength band of about 940 nm. In the aberration diagram of Fig. 5, it can be interpreted that the closer each curve at room temperature is to the Y-axis, the better the aberration correction function. That is, the optical system (100) according to the embodiment can have improved resolution and good optical performance in the center and periphery of the field of view (FOV).

[0094] Table 1 is a comparative table measuring changes in optical characteristics such as EFL, BFL, F number (F#), TTL, and FOV according to temperature changes (room temperature, low temperature, high temperature) in an optical system and a camera module according to an embodiment, and it can be seen that the change rate of the optical characteristics at low temperature is 5% or less, for example, 3% or less, based on room temperature, and it can be seen that the change rate of the optical characteristics at high temperature is 5% or less, for example, 3% or less, based on room temperature. Here, the low temperature is -20 degrees or less, for example, in the range of -20 to -40 degrees, the room temperature is in the range of 22 degrees ± 5 degrees or in the range of 18 degrees to 27 degrees, and the high temperature can be 85 degrees or more, for example, in the range of 85 degrees to 105 degrees.

[0095] Room temperature, low temperature, high temperature, low temperature / room temperature, high temperature / room temperature EFL (mm) 3.896 3.896 3.896 99.99% 100.01% BFL (mm) 2.910 2.911 2.909 100.02% 99.98% F# 1.100 1.099 1.101 99.94% 100.06% TTL (mm) 30.000 29.974 30.026 99.91% 100.09% FOV (degrees) 126.825 126.846 126.804 100.02% 99.98%

[0096] The optical system (100) above generates chromatic aberration and can correct the chromatic aberration using spaced aspherical lenses. As the temperature changes from low to high, the lenses repeatedly contract and expand. Since the amount of change in lens characteristics according to temperature change is the same for lenses of the same material, it is effective to correct the chromatic aberration between lenses of the same material even when the temperature changes. In addition, even if the optical system (100) uses one or more aspherical lenses, temperature compensation for the aspherical lenses is possible and a decrease in the reliability of the optical characteristics can be prevented. The optical system of the embodiment disclosed above can effectively control aberration characteristics such as chromatic aberration and distortion aberration, and can have good optical performance at the center and periphery of the field of view (FOV).

[0097] An optical system according to an embodiment of the invention can prevent a deterioration in optical performance from low to high temperatures by taking into account the characteristics of an optical system for a vehicle. For example, after designing a lens at room temperature, the value of the dn / dt, which is a temperature-dependent refractive index change coefficient, is assembled by taking into account the power combination of each lens, and the value of the temperature coefficient (dn / dt) according to the refractive index of the lens and the defocus for the thickness variable according to low, room, and high temperatures can be set to 5㎛ or less. To this end, the first and third lenses are made of a spherical glass material, and the second and fourth lenses are made of an aspherical glass material.

[0098] The optical system (100) according to the embodiment disclosed above can satisfy at least one or two or more of the mathematical equations described below. Accordingly, the optical system (100) according to the embodiment can have improved optical characteristics. For example, when the optical system (100) satisfies at least one mathematical equation, the optical system (100) can effectively control aberration characteristics such as chromatic aberration and distortion aberration, and can have good optical performance at the center and periphery of the field of view (FOV). In addition, the optical system (100) can have improved resolution. The center thickness of the first to fourth lenses (101-104) is represented by CT1-CT4, the edge thickness at the end of the effective area of ​​each lens is represented by ET1-ET4, and the center gap between two adjacent lenses can be represented by CG1-CG3.

[0099] [Mathematical Formula 1] 0 < CT1 / CT2 < 1

[0100] In mathematical expression 1, by setting the central thickness (CT1) of the first lens (101) and the central thickness (CT2) of the second lens (102), it is possible to prevent a decrease in the rigidity of the first lens (101) and control factors affecting aberration. Preferably, mathematical expression 1 can satisfy 0.2 < CT1 / CT2 < 0.8.

[0101] [Mathematical Formula 2] 1 < CT4 / CT1 < 3

[0102] In mathematical expression 2, the central thickness (CT1) of the first lens (101) and the central thickness (CT4) of the fourth lens (104) can be set, and the strength of the glass lens can be prevented from decreasing, thermal compensation can be optimized according to temperature changes from low to high temperatures, and the deterioration of optical performance can be prevented. Preferably, mathematical expression 2 can satisfy 1.2 < CT4 / CT1 < 2.2.

[0103] [Equation 3] 0.5 < CT2 / CT3 < 1.5

[0104] In mathematical expression 3, the central thicknesses (CT2, CT3) of the second and third lenses (102, 103) can be set, thereby controlling factors affecting aberration. Preferably, mathematical expression 3 can satisfy 0.7 < CT2 / CT3 < 1.2.

[0105] [Mathematical Formula 4] 1 < CG1 / CT1 < 4

[0106] In mathematical expression 4, the effective diameter of the second lens (102) can be adjusted by setting the center distance (CG1) between the first and second lenses (101, 102). Preferably, mathematical expression 4 can satisfy 2 < CG1 / CT1 < 3.

[0107] [Equation 5] 0 < CG1 / (CT1+CT2) < 1.5

[0108] In mathematical expression 5, the center distance (CG1) between the first and second lenses (101, 102) and the center thickness (CT1, CT2) of the first and second lenses (101, 102) can be set, so that the effective diameter of the second lens (102) can be adjusted according to the shape of the first and second lenses (101, 102). Preferably, mathematical expression 5: 0.5 < CG1 / (CT1+CT2) < 1 can be satisfied.

[0109] [Equation 6] 1 < CG1 / CG2 < 4

[0110] In mathematical expression 6, the center spacing between the spherical lens and the aspherical lens can be adjusted by setting the center spacing (CG1) between the first and second lenses and the center spacing (CG2) between the second and third lenses. Preferably, mathematical expression 6 can satisfy 1.5 < CG1 / CG2 < 2.5.

[0111] [Equation 7] 0.5 < CG2 / CG3 < 1.5

[0112] In mathematical expression 7, the center spacing between the spherical lens and the aspherical lens can be adjusted by setting the center spacing (CG2) between the second and third lenses and the center spacing (CG3) between the third and fourth lenses. Preferably, mathematical expression 7 can satisfy 0.5 < CG2 / CG3 < 1.

[0113] [Equation 8] 0 < CG2 / CT2 < 1.5

[0114] In mathematical expression 8, the center spacing (CG2) of the second and third lenses and the center thickness (CT2) of the second lens can be set. Accordingly, the second lens (102) has a convex meniscus shape toward the sensor, and the third lens (103) provides a concave shape on both sides, so that the path of light passing through the second and third lenses can be controlled.

[0115] [Equation 9] SD1 < TTL

[0116] In mathematical expression 9, SD1 is the distance in the direction of the optical axis from the aperture (ST1) to the sensor side of the fourth lens (104), which is the last lens. The aperture (ST1) is arranged within the lens section so as to control the amount of light in the area between the lenses.

[0117] [Equation 10] 1.70 < Nd1

[0118] Nd1 is the refractive index at the d-line of the first lens (101). In mathematical expression 10, by setting the refractive index of the first lens (101) high, the factor affecting the reduction of the third-order aberration (Seidel aberration) of the optical system can be adjusted, and the aberration that may occur as the TTL becomes somewhat longer can be reduced. Mathematical expression 10 can preferably satisfy 1.75 < Nd1 < 2.1. If it is designed to be lower than the lower limit of mathematical expression 10, the performance of reducing the aberration can be obtained, and the refractive power of the first lens may be weakened so that light cannot be collected efficiently, which may lower the performance of the optical system. If it is designed to be higher than the upper limit of mathematical expression 10, there is a disadvantage in that it is difficult to obtain materials. Additionally, when the refractive index of the first lens (101) is designed to be lower than the lower limit of mathematical expression 10, the radius of curvature of the first and second lenses can be increased to increase the refractive power of the first and second lenses.

[0119] [Equation 11] 0.5 < Nd1 / Nd3 < 1.5

[0120] Nd1 and Nd3 are the refractive indices of the first and third lenses at the d-line. In Equation 11, by reducing the difference in refractive indices between the first and third lenses, the reduction in color dispersion caused by lenses made of glass can be prevented. Preferably, in Equation 11, Nd1 and Nd3 can be the same.

[0121] [Equation 12] 0.5 < Nd1 / Nd4 < 1.5

[0122] Nd1 and Nd4 are the refractive indices of the first and fourth lenses at the d-line. In Equation 12, by setting the refractive index of the fourth lens to be lower than the refractive index of the first lens, the chromatic dispersion caused by the spherical material lenses and the chromatic dispersion caused by the aspherical lenses can be controlled. Preferably, Equation 12 can satisfy 1 < Nd1 / Nd4 < 1.2.

[0123] [Mathematical Formula 13] (Vd2*Nd2) < (Vd4*Nd4)

[0124] Vd2 and Vd4 are the Abbe numbers of the second and fourth lenses, and Nd2 is the refractive index of the second lens at the d-line. In mathematical expression 13, by setting the product of the refractive index and the Abbe number of the second lens (102) to be lower than the product of the refractive index and the Abbe number of the fourth lens (104), the color dispersion by the spherical material lens and the color dispersion by the aspherical lens can be controlled.

[0125]

[0126] [Equation 14] 1 < TD / SD1 < 2.5

[0127] In Equation 14, TD is the optical axis distance from the center of the object-side surface of the first lens to the center of the sensor-side surface of the fourth lens, which is the last lens. Since the optical system satisfies Equation 14, the position of the aperture (ST1) can be set. Preferably, 1.5 < TD / SD1 < 2 can be satisfied.

[0128] [Equation 15] 1 < CA42 / CT4 < 5

[0129] In Equation 15, CA42 is the effective diameter of the sensor-side surface of the fourth lens. In Equation 15, the effective diameter and the central thickness of the sensor-side surface of the fourth lens can be set. Accordingly, the fourth lens can control the emitted light path. Preferably, 2.5 < CA42 / CT4 < 3.5 can be satisfied.

[0130] [Equation 16] 4 < CA11 / CT1 < 10

[0131] In Equation 16, CA11 is the effective diameter of the object-side surface of the first lens. In Equation 16, the effective diameter and the central thickness of the object-side surface of the first lens can be set. Accordingly, the first lens can control the amount of incident light. Preferably, 6 < CA11 / CT1 < 9 can be satisfied.

[0132] [Mathematical Formula 17] 1 < CA11 / (CG1+CG2) < 3

[0133] Mathematical expression 17 can set the center spacing (CG1, CG2) between the first, second, and third lenses according to the effective diameter of the object-side surface of the first lens. Preferably, 1.5 < CA11 / (CG1+CG2) < 2.5 can be satisfied.

[0134] [Mathematical Formula 18] 1 < CA11 / CA21 < 3

[0135] CA11 refers to the effective diameter of the object-side first surface (S1) of the first lens (101), and CA21 refers to the effective diameter of the object-side third surface (S3) of the second lens (102). When mathematical expression 18 is satisfied, the optical system (100) can control the incident light and set the factors affecting aberration, and preferably, 1.5 < CA11 / CA21 < 2.5 can be satisfied.

[0136] [Equation 19] 0 < CA22 / CA31 < 2

[0137] CA22 denotes the effective diameter of the sensor-side fourth surface (S4) of the second lens, and CA31 denotes the effective diameter of the object-side fifth surface (S5) of the third lens. When mathematical expression 19 is satisfied, the optical system (100) can control the incident light path and set the sensor-side surface of the second lens to a convex shape. Preferably, mathematical expression 19 can satisfy 0.5 < CA22 / CA31 < 1.

[0138] [Mathematical Formula 20] 1 < CA11 / CA12 < 3

[0139] CA12 refers to the effective diameter of the sensor-side second surface (S2) of the first lens. When mathematical expression 20 is satisfied, the optical system (100) can set a light path refracted through the first lens (101). Mathematical expression 20 can preferably satisfy 1.5 < CA11 / CA12 < 2.3.

[0140] [Mathematical Formula 21] 1 < CA11 / CA42 < 3

[0141] CA11 is the effective diameter of the first surface (S1) of the first lens, and CA42 means the effective diameter of the eighth surface (S8) of the fourth lens. When the optical system (100) satisfies mathematical expression 21, the incident amount of the first lens, which is a spherical lens, can be increased, and the path of light toward the sensing unit can be set through the last lens, which is an aspherical lens. Mathematical expression 21 can preferably satisfy 1 < CA11 / CA42 < 1.5.

[0142] [Mathematical Formula 22] 5 < (CA11*L1R1) / (CA12*L1R2) < 15

[0143] L1R1 is the radius of curvature of the first surface of the first lens, and L1R2 is the radius of curvature of the second surface of the first lens. In mathematical expression 22, the effective diameter (CA11) and the radius of curvature (L1R1) of the object-side surface of the first lens, and the effective diameter (CA12) and the radius of curvature (L1R2) of the sensor-side surface of the first lens can be set. Accordingly, the first lens (101) can control the light path incident on the effective area of ​​the second lens (102) having the minimum effective diameter within the lens unit. Preferably, 6 < (CA11*L1R1) / (CA12*L1R2) < 10 can be satisfied.

[0144] [Mathematical Formula 23] 5 < (CA1-CA2) / (CA4-CA3) < 30

[0145] CA1, CA2, CA3, and CA4 are the average effective diameters of the object-side and sensor-side surfaces of the first to fourth lenses, respectively. In mathematical expression 22, the effective diameter between two adjacent lenses can be set. Accordingly, the first to fourth lenses (101-104) can control the light path that proceeds to the effective area of ​​each lens. Preferably, 15 < (CA1-CA2) / (CA4-CA3) < 25 can be satisfied.

[0146]

[0147] [Mathematical Formula 24] 1 < (CA1-CA2) / (CT2-CT1) < 4

[0148] Mathematical expression 24 sets the difference in the center thickness of the first and second lenses and the difference in the effective diameter of the first and second lenses, thereby allowing the optical path to be adjusted according to the sizes of the lenses. Preferably, 1.5 < (CA1-CA2) / (CT2-CT1) < 2.5 can be satisfied.

[0149] [Equation 25] 0 < CT4 / BFL < 1.5

[0150] In mathematical expression 25, when the central thickness (CT4) of the fourth lens and the optical axis distance (BFL) between the fourth lens (104) and the sensing unit (151) are satisfied, the incident light can be transmitted to the entire area of ​​the sensing unit (151) by the fourth lens. Preferably, 0.2 < CT5 / BFL < 1 can be satisfied.

[0151]

[0152] [Equation 26] 0 < CG3 / CT4 < 2

[0153] In mathematical expression 26, the central thickness of the fourth lens and the central spacing between the third and fourth lenses can be set. Preferably, mathematical expression 26: 0.5 < CG3 / CT4 < 1 can be satisfied.

[0154] [Mathematical Formula 27] 1 < CA_ST2 / CA_ST1 < 5

[0155] CA_ST1 is the effective diameter of the aperture (ST1) arranged on the periphery between the second and third lenses, i.e., the effective diameter of the hole, and CA_ST2 is the effective diameter of the object-side aperture (ST2) arranged on the periphery of the object-side surface of the first lens (101), i.e., the effective diameter of the hole. When mathematical expression 26 is satisfied, the effective diameters of the two apertures (ST1, ST2) can be set in an optical system having five or fewer lenses.

[0156] [Equation 28] 1 < |L4R2| / CT4 < 10

[0157] L4R2 is the radius of curvature of the sensor-side surface of the fourth lens. When mathematical expression 28 is satisfied, the refractive power of the fourth lens (104) can be controlled and optical performance can be improved. Preferably, 1 < |L4R2| / CT4 < 5 can be satisfied.

[0158] [Equation 29] 0 < |L4R2| / L4R1 < 2

[0159] When mathematical expression 29 is satisfied, the refractive power of the fourth lens (104) can be controlled and optical performance can be improved. Preferably, 0 < |L4R2| / L4R1 < 1 can be satisfied.

[0160] [Mathematical Formula 30] 1 < L1R1 / L1R2 < 10

[0161] In mathematical expression 30, the radius of curvature of the object-side surface and the sensor-side surface of the first lens can be set. When mathematical expression 30 is satisfied, the refractive power of the first lens (101) can be controlled and the optical performance can be improved. Preferably, 2 < L1R1 / L1R2 < 8 can be satisfied.

[0162] [Equation 31] 0.2 < |L2R1 / L2R2| < 1.5

[0163] L2R1 is the radius of curvature of the object-side surface of the second lens, and L2R2 is the radius of curvature of the sensor-side surface of the second lens. When mathematical expression 31 is satisfied, the refractive power of the second lens (102) can be controlled to improve optical performance, and the effective diameters of the third, fourth lenses (103, 104) can be adjusted. Preferably, mathematical expression 31 can satisfy 0.5 < |L2R1 / L2R2| < 1.

[0164] [Equation 32] 0 < CT_Max / CG_Max < 1.5

[0165] In Equation 32, the maximum center thickness (CT_Max) among the lenses and the maximum center spacing (CG_Max) between adjacent lenses can be set. When Equation 32 is satisfied, the optical system can have good optical performance at the focal length of the set angle of view and can reduce the TTL. Preferably, Equation 32: 0.4 < CT_Max / CG_Max < 1 can be satisfied.

[0166] [Equation 33] 0.5 < ΣCT / ΣCG < 1.7

[0167] ΣCT is the sum of the central thicknesses of the lenses, and ΣCG is the sum of the spacings between adjacent lenses. When mathematical expression 33 is satisfied, the optical system can have good optical performance at the focal length at the set angle of view, and can reduce the TTL. Here, 1 < ΣCT / ΣCG < 1.5 can be satisfied.

[0168] [Equation 34] 5 < ΣNd < 15

[0169] ΣNd represents the sum of the refractive indices at the d-line of each of the plurality of lenses. When mathematical expression 34 is satisfied, TTL can be controlled in an optical system (100) in which aspherical lenses and spherical lenses are mixed, and improved resolution can be achieved. In addition, when the number of spherical lenses is greater than the number of aspherical lenses, the sum of TTL and refractive indices can be set. Mathematical expression 34 can preferably satisfy 5 < ΣNd < 9.

[0170] [Equation 35] 10 < ΣVd / ΣNd < 40

[0171] ΣVd means the sum of the Abbe numbers of each of the plurality of lenses. When mathematical expression 35 is satisfied, the optical system (100) can have improved aberration characteristics and resolution. By setting the sum of the Abbe numbers and the sum of the refractive indices of the lenses in mathematical expression 35, the optical characteristics can be controlled, and preferably, 12 < ΣVd / ΣNd < 25 can be satisfied.

[0172] [Equation 36] 5 < (ΣCT*n) / F < 20

[0173] n is the number of lenses in the optical system, and F is the effective focal length of the optical system. If mathematical expression 36 is satisfied, TTL can be controlled. Preferably, 10 < (ΣCT*n) / F < 17 can be satisfied.

[0174] [Equation 37] 2 < ΣCT / ΣET < 12

[0175] ΣET represents the sum of the edge thicknesses of the effective areas of multiple lenses. In Equation 37, the sum of the center thicknesses of multiple lenses can be set to be greater than the sum of the edge thicknesses. Preferably, 3 < ΣCT / ΣET < 6 can be satisfied.

[0176] [Equation 38] 1 < CA11 / CA_Min < 5

[0177] CA_Min represents the minimum effective diameter between the object-side and sensor-side surfaces of the lenses. When Equation 37 is satisfied, the optical system can control incident light, maintain optical performance, and provide a slimmer module. Equation 38 preferably satisfies 1 < CA11 / CA_Min < 3.

[0178] [Equation 39] 0 < CG2 / CA12 < 1

[0179] In mathematical expression 39, the center spacing between the second and third lenses and the effective diameter of the sensor-side surface of the first lens can be set. Preferably, 0 < CG2 / CA12 < 0.5 can be satisfied.

[0180] [Equation 40] 0.5 < CG2 / CA31 < 2

[0181] CA31 represents the effective diameter of the object-side surface of the third lens. When mathematical expression 40 is satisfied, the effective diameter of the object-side surface of the third lens can be set according to the center spacing between the second and third lenses. Preferably, 0 < CG2 / CA31 < 0.5 can be satisfied.

[0182]

[0183] [Equation 41] 1 < CA_Max / F < 5

[0184] CA_Max represents the maximum effective diameter between the object-side and sensor-side faces of the lenses. Preferably, 3 < CA_Max / F < 4.5 can be satisfied.

[0185] [Equation 42] 1 < CA_Max / (2*ImgH) < 6

[0186] In mathematical expression 42, the maximum effective diameter (CA_Max) of the lens surface can be set to the diagonal length (2*ImgH) of the sensing unit (151), and if this is satisfied, the optical system can maintain good optical performance and a slim and compact sensor device can be set. Mathematical expression 41 can preferably satisfy 1 < CA_Max / (2*ImgH) < 3.

[0187] [Equation 43] 0 < F / │L4R2│ < 1

[0188] F is the effective focal length of the optical system, and L4S2 is the radius of curvature of the sensor-side surface of the fourth lens. When mathematical expression 43 is satisfied, the effect on optical system reduction, such as TTL, can be controlled by setting the effective focal length and the radius of curvature of the sensor-side surface of the last aspherical lens. Mathematical expression 43 can preferably satisfy 0 < F / │L4R2│ < 0.5.

[0189] [Equation 44] 0 < F / L1R1 < 1

[0190] In mathematical expression 44, the effective focal length of the optical system and the radius of curvature of the object-side surface of the first lens can be set to control the influence on the incident light and TTL. Mathematical expression 44 can preferably satisfy 0 < F / L1R1 < 0.4.

[0191] [Equation 45] 0 < EPD / │L4R2│ < 1

[0192] EPD refers to the size of the entrance pupil diameter of the optical system (100). When the optical system (100) according to the embodiment satisfies mathematical expression 45, the optical system (100) can control incident light. Preferably, the condition of 0 < EPD / L4R2 < 0.5 can be satisfied.

[0193] [Equation 46] 0 < EPD / L1R1 < 1

[0194] In mathematical expression 46, the size of the entrance pupil of the optical system (100) and the radius of curvature of the object-side surface of the first lens can be set, and when these are satisfied, the optical system (100) can control the incident light. Preferably, the condition of 0 < EPD / L1R1 < 0.3 can be satisfied.

[0195]

[0196] [Equation 47] 10 < F2 / F < 100

[0197] F2 is the focal length of the second lens. When mathematical expression 48 is satisfied, the power of the second lens can be set positively for an optical system having an angle of view of 110 degrees or more. Preferably, 30 < F2 / F < 70 can be satisfied.

[0198] [Mathematical Formula 48] 1 <|F1│ / F <5

[0199] F1 is the focal length of the first lens, and F is the overall focal length. If Equation 47 is satisfied, the power of the first lens can be set negative for an optical system with an angle of view of 110 degrees or more.

[0200] [Equation 49] 1 < F4 / F < 6

[0201] In mathematical expression 49, the total effective focal length and the focal length of the fourth lens can be set, and the resolution can be improved by controlling the refractive power of the fourth lens. Preferably, 1 < F4 / F < 6 can be satisfied. In mathematical expressions 47 to 49, when F1, F2, F3, F4 and the total effective overall distance are set, light can be guided to the effective area of ​​the aspherical lens by adjusting the focal length of the spherical lens to the last aspherical lens. The balance of the focal lengths of each lens can suppress the difference in focus position due to temperature change. Accordingly, the optical characteristics of the imaging lenses can be suppressed from deteriorating due to temperature change.

[0202]

[0203] [Mathematical Formula 50] Po1*Po2 < 0

[0204] Po1 and Po2 are the power values ​​of the first and second lenses. The first and second lenses can have powers of opposite signs. The first and third lenses can have powers of opposite signs, which can improve aberrations and effectively guide light with aspherical lenses.

[0205] [Mathematical Formula 51] 10mm < TTL < 60mm

[0206] TTL (Total track length) refers to the distance from the center of the first surface (S1) of the first lens (101) to the upper surface of the sensing unit (151) on the optical axis (OA). If mathematical expression 51 is satisfied, it can be applied to a vehicle optical system having TTL. Mathematical expression 51 can preferably satisfy 20 mm < TTL < 40 mm.

[0207] [Mathematical Formula 52] 2mm < ImgH < 6mm

[0208] Mathematical expression 52 can set half of the diagonal size of the sensing unit (151) and provide an optical system having a vehicle sensor size. Mathematical expression 52 can preferably satisfy 3 mm < ImgH < 5 mm.

[0209] [Mathematical Formula 53] 3mm < BFL < 8mm

[0210] In mathematical expression 53, the BFL (Back focal length) is set to exceed 3 mm, thereby securing an installation space for an optical filter, improving the assemblability of components through the gap between the sensing unit (151) and the last lens, and improving the joint reliability. Mathematical expression 53 can preferably satisfy 4 mm < BFL < 7.5 mm. When the BFL is less than the range of mathematical expression 53, some of the light traveling to the sensing unit may not be transmitted to the sensing unit, which may cause a decrease in resolution. When the BFL exceeds the range of mathematical expression 53, stray light may be introduced, which may deteriorate the aberration characteristics of the optical system.

[0211] [Mathematical Formula 54] 1mm < F < 20mm

[0212] Mathematical expression 54 can set the overall effective focal length (F) to suit the vehicle optical system. Mathematical expression 54 can satisfy 1 mm < F < 6 mm.

[0213] [Mathematical Formula 55] 70 degrees < FOV < 150 degrees

[0214] In mathematical expression 55, FOV (Field of view) refers to the angle of view (Degree) of the optical system (100), and a vehicle optical system having an angle of view (F0V) exceeding 70 degrees or 100 degrees or more can be provided. Preferably, mathematical expression 55: 100 ≤ FOV ≤ 140 can be satisfied.

[0215] In mathematical expression 55, the range of the vehicle optical system can be set by the angle of view. The horizontal sensor length is based on 12.8 mm ± 0.6 mm. In addition, when mathematical expression 55 is satisfied, when the temperature changes from room temperature to high temperature, the change rate of the effective focal length and the change rate of the angle of view can be set to 5% or less, for example, 0 to 5%. In addition, even if two or more aspherical lenses are used in combination with spherical lenses in the optical system (100), the deterioration of optical characteristics can be prevented through temperature compensation and aberration correction by the aspherical lens made of glass.

[0216]

[0217] [Mathematical Formula 56] 1 < TTL / CA_Max < 4

[0218] Mathematical expression 56 can provide an improved vehicle optical system by setting the total optical axis length of the optical system and the maximum effective diameter among the object-side and sensor-side surfaces of the lens. Mathematical expression 56 can preferably satisfy 1 < TTL / CA_Max < 3.

[0219] [Mathematical Formula 57] 4 < TTL / ImgH < 11

[0220] Mathematical expression 57 can set the total optical axis length (TTL) of the optical system and the diagonal length (ImgH) from the optical axis of the sensing unit (151). When the optical system (100) according to the embodiment satisfies Mathematical expression 57, the optical system (100) can have TTL for application to the vehicle sensing unit (151), thereby providing improved image quality. Mathematical expression 57 can preferably satisfy 5 < TTL / ImgH < 10.

[0221] [Equation 58] 0 < BFL / ImgH < 3

[0222] Mathematical expression 58 can set the optical axis distance between the sensing unit (151) and the last lens and the length in the diagonal direction from the optical axis of the sensing unit (151). When the optical system (100) according to the embodiment satisfies Mathematical expression 58, the optical system (100) can secure a BFL for applying the size of the vehicle sensing unit (151), can set the distance between the last lens and the sensing unit (151), and can have good optical characteristics in the center and periphery of the field of view (FOV). Mathematical expression 58 can preferably satisfy 1 < BFL / ImgH < 2.

[0223] [Equation 59] 1 < TTL / BFL < 10

[0224] Mathematical expression 59 can set the total optical axis length (TTL) of the optical system and the optical axis spacing (BFL) between the sensing unit (151) and the last lens. When the optical system (100) according to the embodiment satisfies Mathematical expression 59, the optical system (100) can secure BFL. Mathematical expression 59 can preferably satisfy 2 < TTL / BFL < 7.

[0225] [Equation 60] 0 < F / TTL < 0.5

[0226] Mathematical expression 60 can set the effective focal length (F) and the total optical axis length (TTL) of the optical system (100). Accordingly, an optical system for a driver assistance system can be provided. Mathematical expression 60 can satisfy 0 < TTL / F < 0.2. When the optical system (100) according to the embodiment satisfies Mathematical expression 60, the optical system (100) can have an appropriate focal length and a wide angle of view in the set TTL range, and provides an optical system that can form an image while maintaining an appropriate focal length even when the temperature changes from low to high. When it is less than the lower limit of Mathematical expression 60, it is necessary to increase the refractive power of the lenses, making it difficult to correct spherical aberration or distortion aberration, and when it is more than the upper limit of Mathematical expression 60, the effective diameter or TTL of the lenses becomes long, which may cause a problem of the imaging lens system becoming large.

[0227] [Equation 61] 0 < F / BFL < 1

[0228] Mathematical expression 61 can set the effective focal length (F) of the optical system (100) and the optical axis distance (BFL) between the sensing unit (151) and the last lens. When the optical system (100) according to the embodiment satisfies Mathematical expression 61, the optical system (100) can have a set angle of view and an appropriate focal length, and an optical system for a vehicle can be provided. In addition, the optical system (100) can minimize the distance between the last lens and the sensing unit (151), and thus can have good optical characteristics in the periphery of the field of view (FOV). Mathematical expression 61 can preferably satisfy 0.4 < F / BFL < 1.

[0229]

[0230] [Equation 62] 0 < F / ImgH < 2

[0231] Mathematical expression 62 can set the total focal length (F) of the optical system (100) and the diagonal length (ImgH) from the optical axis of the sensing unit (151). This optical system (100) can have improved aberration characteristics in the size of the vehicle sensing unit (151). Mathematical expression 62 can preferably satisfy 0.5 < F / ImgH < 1.

[0232] [Equation 63] 0 < F / EPD < 3

[0233] Mathematical expression 63 can set the overall focal length (F) and entrance pupil size of the optical system (100). Accordingly, the optical system has a small F number, allowing for control of overall brightness. Mathematical expression 63 preferably satisfies 1 < F / EPD < 1.2.

[0234] [Mathematical Formula 64] 0 < EPD / ImgH / FOV < 0.5

[0235] Mathematical expression 64 can set the relationship between the entrance pupil size (EPD), the length of half the diagonal length of the image sensor (ImgH), and the diagonal field of view. Accordingly, the overall size and brightness of the optical system can be controlled. Mathematical expression 64 can preferably satisfy 0 < EPD / ImgH / FOV < 0.05.

[0236] [Equation 65] 50 < FOV / F# < 150

[0237] Mathematical expression 65 can establish the relationship between the diagonal field of view of an optical system and the F number. Mathematical expression 65 preferably satisfies 100 < FOV / F# < 130. Here, F# is provided to be 1.5 or less, thereby providing a bright image.

[0238] [Equation 66] 1 < (CT_Max+CG_Max) / n < 5

[0239] Mathematical expression 66 can set the maximum of the central thicknesses of each lens, the maximum of the central spacing between adjacent lenses, and the number of lenses (n), and can satisfy the condition of 1 < (CT_Max+CG_Max) / n < 4.

[0240] [Mathematical Formula 67] 300 < (FOV * TTL) / n

[0241] If the field of view (FOV) and total length to length (TTL) of the optical system in mathematical expression 67 are satisfied, the optical axis length of the optical system having an angle of view of 110 degrees or more can be set. Accordingly, the chromatic aberration, resolution, size, etc. of the optical system having 5 or fewer lenses can be controlled.

[0242]

[0243] [Equation 68]

[0244]

[0245] In mathematical expression 68, Z may represent Sag, which is the distance in the direction of the optical axis from any position on the aspherical surface to the vertex of the aspherical surface. Y may represent the distance in the direction perpendicular to the optical axis from any position on the aspherical surface to the optical axis. c may represent the curvature of the lens, and K may represent the conic constant. In addition, A, B, C, D, E, and F may represent aspheric coefficients.

[0246]

[0247] The optical system (100) according to the embodiment can satisfy at least one or two or more mathematical equations from mathematical equations 1 to 67. In this case, the optical system (100) can have improved optical characteristics. Specifically, when the optical system (100) satisfies at least one of mathematical equations 1 to 34 and / or at least one of mathematical equations 35 to 67, the optical system (100) can have improved resolution and improve aberration and distortion characteristics. In addition, the optical system (100) can secure a BFL (Back focal length) for applying a vehicle sensing unit (151), can compensate for optical characteristic degradation due to temperature change, and can minimize the gap between the last lens and the sensing unit (151), thereby having good optical performance at the center and periphery of the field of view (FOV).

[0248] Table 2 shows the items of the mathematical formulas described above in the optical system (100) of the embodiment, including the TTL (mm), BFL (mm), effective focal length (F), ImgH (mm), effective diameter (mm), the sum of the center thicknesses of each lens, the sum of the center spacings between adjacent lenses, the sum of Abbe numbers, the sum of refractive indices, the optical axis distance TD (mm) from the first surface (S1) to the eighth surface (S8), the focal lengths (F1, F2, F3, F4) of each of the first to fourth lenses, the composite focal length, FOV, edge thickness (ET), F number, etc. of the optical system (100).

[0249] Item ValueItem ValueF(EFL)3.896F12-11.207F1-8.238F348.097F2199.044FOV126.800F311.624EPD3.542F413.253BFL6.335ΣNd7.007TD2 3.665ΣVd109.023ImgH4.400ΣCT13.440SD12.665ΣCG10.225ET13.413TTL30.000ET23.776F#3.896ET32.496ΣET3.046ET42.500

[0250] Table 3 shows the result values ​​for the mathematical expressions 1 to 34 described above in the optical system (100) of the embodiment. Referring to Table 3, it can be seen that the optical system (100) satisfies at least one, two or more, or three or more of the mathematical expressions 1 to 34. Accordingly, the optical system (100) can have good optical performance and excellent optical characteristics in the center and periphery of the field of view (FOV).

[0251] Mathematical formula value 10 < CT1 / CT2 < 10.51921 < CT4 / CT1 < 31.79130.5 < CT2 / CT3 < 1.50.96341 < CG1 / CT1 < 42.52350 < CG1 / (CT1+CT2) < 1.50.86261 < CG1 / CG2 < 41.98270.5 < CG2 / CG3 < 1.50.96780 < CG2 / CT2 < 1.50.6619SD1 < TTL satisfaction 101.70 < Nd1 1.778110.5 < Nd1 / Nd3 < 1.51.000120.5 < Nd1 / Nd4 <1.51.06813(Vd2*Nd2) < (Vd4*Nd4)Satisfied141 < TD / SD1 < 2.51.869151 < CA42 / CT4 < 52.933164 < CA11 / CT1 < 107.300171 < CA11 / (CG1+CG2) < 31.923181 < CA11 / CA21 < 31.915190 < CA22 / CA31 < 20.876201 < CA11 / CA12 < 31.704211 < CA11 / CA42 < 31.389225 < (CA11*L1R1) / (CA12*L1R2) < 158.382235 < (CA1-CA2) / (CA4-CA3) < 3018.749241 < (CA1-CA2) / (CT2-CT1) < 41.828250 < CT4 / BFL < 1.50.566260 < CG3 / CT4 < 20.735271 < CA_ST2 / CA_ST1 < 52.356281 < |L4R2| / CT4 < 103.807290 < |L4R2| / L4R1 < 20.614301 < L1R1 / L1R2 < 104.919310.2 < |L2R1 / L2R2| < 1.50.846320 < CT_Max / CG_Max < 1.50.793330.5 < ∑CT / ∑CG < 1.71.314345 < ∑Nd <157.007

[0252] Table 4 shows the result values ​​for the mathematical expressions 35 to 67 described above in the optical system (100) of the embodiment. Referring to Table 4, it can be seen that the optical system (100) satisfies at least one, two or more, or three or more of the mathematical expressions 35 to 67. Accordingly, the optical system (100) can have good optical performance and excellent optical characteristics in the center and periphery of the field of view (FOV).

[0253] Equation value 3510 < ∑Vd / ∑Nd <4015.560365 < (∑CT*n) / F < 2013.799372 < ΣCT / ΣET < 124.412381 < CA11 / CA_Min < 51.915390 < CG2 / CA12 < 10.297400.5 < CG2 / CA31 < 20.255411 < CA_Max / F < 53.747421 < CA_Max / (2*ImgH) < 61.657430 < F / |L4R2| < 10.286440 < F / L1R1 < 10.163450 < EPD / |L4R2|< 10.260460 < EPD / L1R1 < 10.1484710 < F2 / F < 10051.089481 < |F1| / F < 52.115491 < F4 / F < 63.40250Po1 * Po2 < 0Satisfied5110 < TTL < 6030.000522 < ImgH < 64.405533 < BFL < 86.335541 < F < 203.8965570 < FOV < 150126.800561 < TTL / CA_Max < 42.055574 < TTL / ImgH < 116.811580 < BFL / ImgH < 31.438591 < TTL / BFL < 104.736600 < F / TTL < 0.50.130610 < F / BFL < 10.615620 < F / ImgH < 20.884630 < F / EPD < 31.100640 < EPD / ImgH / FOV < 0.50.0066550 < FOV / F# < 150115.282661 < (CT_Max+CG_Max) / n < 52.26267300 < (FOV*TTL) / n951.000

[0254] FIG. 6 is a block diagram of a sensor device having an optical system according to an embodiment of the invention.

[0255] Referring to FIG. 6, the sensor device includes a control unit (10), a light source driving unit (20), a transmission optical system (30), the optical system (50) disclosed above, and a signal processing unit (60). The control unit (10) controls the transmission and reception of signals, and can be linked to devices related to communication services such as autonomous driving modules, artificial intelligence modules, drones, robots, augmented reality devices, virtual phenomenon devices, and 5G and 6G based on the transmitted / received signals. The light source driving unit (20) supplies power to and drives a light source included in the transmission optical system (30). The light source generates a laser beam in the form of a line light source or a point light source. The light source driving unit (20) can adjust or vary the driving current supplied to the light source according to driving environment information. The driving environment information may include topographic information of the driving section, traffic congestion information, weather, etc.

[0256] The wavelength of the laser beam generated from the light source may be in the range of 890 nm to 960 nm or in the range of 940 nm ± 10 nm. As another example, the wavelength of the laser beam may be 1550 nm ± 10 nm. The laser light source may be implemented as an InGaAs / GaAs-based semiconductor diode laser and may emit a high-power laser beam. The light source may include a single emitter and / or multiple emitters.

[0257] The above-mentioned transmitting optical system (30) transmits a laser beam generated from a light source to an object (40) through a lens unit and a diffuser, and the light reflected from the object (40) is received by the optical system (50). The optical system (50) may be composed of a plurality of optical sensors, and the optical sensors convert the received light into an electrical signal using a photodiode. That is, the sensing unit is arranged in a matrix type to convert the light received from an object scanned in each of the horizontal and vertical directions into an electric current.

[0258] The signal processing unit (60) converts the output of the optical system (50) into a voltage, amplifies it, and then converts the amplified signal into a digital signal using an analog-to-digital converter. The signal processing unit (60) analyzes the digital data using a TOF (Time of Flight) algorithm or a phase-shift algorithm to detect the distance to the object (40) and the shape of the object.

[0259] The control unit (10) can receive vehicle speed information and road condition information through a control unit (ECU) or a network. The control unit (10) can receive driving environment information through a network. The driving environment information can include terrain information of the driving section, traffic congestion information, weather, etc. The control unit (10) can adjust the gain based on one or more of the vehicle speed, the road surface condition of the road on which the vehicle is driving, and the driving environment information, and can provide sensor data including the distance to an object and shape information of the object to the free driving device.

[0260] FIG. 7 is a drawing showing an example of measuring an object in a vehicle having the sensor system of the invention, and FIG. 8 is a drawing showing an example of surrounding surveillance in a vehicle having the sensor system of the invention.

[0261] Referring to FIGS. 7 and 8, a vehicle (202) having a sensor system includes a transmitting optical system that projects a laser beam (201) generated by a light source toward a target scene, and an optical system that receives light (203) reflected from the target or subject (210). The sensor system also includes a lidar system, which typically includes a controller that calculates distance information to the subject (210) from the reflected light, and an element that can scan or provide a specific pattern of light, which may be a static pattern, within a desired range and field of view (FOV). The transmitting optical system is used to convert the received signal light into measurements representing a point-by-point three-dimensional map of the surrounding environment within the range and field of view of the lidar system.

[0262] The optics and signal processing for the LIDAR calculate range information based on measurements of the time of flight of the light pulses emitted from the light source. Furthermore, the scene is illuminated at a target plane associated with a specific range, and known information about the light beam profile based on the specific design of the source and projector system is used to determine positional information about the reflecting surfaces, thereby generating a complete x, y, z, or 3D picture of the scene. In other words, the point-by-point 3D map of the surrounding environment represents a collection of measurement data representing positional information from all surfaces reflecting the light from the source to the receiver within the LIDAR system's field of view. In this way, a 3D representation of the object in the LIDAR system's field of view is obtained.

[0263] Also shown is a schematic diagram illustrating the two-dimensional field of view and range requirements of a typical surround-view LIDAR system (200) for a vehicle (202). For example, adaptive cruise control may require a field of view and range (204) with a narrower field of view compared to a side-view "surround view" field of view and range (206), but with a longer range requirement. Typically, the sensor functions of a vehicle may be enabled by a combination of LIDAR, radar, cameras, and ultrasonic sensors. The combination of these sensor data to generate information about the surrounding environment is often referred to as "sensor fusion." While the invention describes a LIDAR system in the context of a vehicle, where LIDAR is widely used for autonomous, self-driving, or driver-assisted vehicles, it should be understood that the embodiments may be applied to any vehicle. Other types of vehicles may include robots, tractors, trucks, airplanes, drones, boats, ships, and the like.

[0264] The features, structures, effects, etc. described in the embodiments above are included in at least one embodiment of the present invention, and are not necessarily limited to just one embodiment. Furthermore, the features, structures, effects, etc. illustrated in each embodiment can be combined or modified and implemented in other embodiments by a person having ordinary skill in the art to which the embodiments pertain. Therefore, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention. In addition, although the embodiments have been described above, these are merely examples and do not limit the present invention. Those having ordinary skill in the art to which the present invention pertains will appreciate that various modifications and applications not illustrated above are possible without departing from the essential characteristics of the embodiments. For example, each component specifically shown in the embodiments can be modified and implemented. In addition, the differences related to such modifications and applications should be interpreted as being included in the scope of the present invention defined in the appended claims.

Claims

1. Including first to fourth lenses aligned along the optical axis toward the sensing unit from the object, The power of the above first lens is negative, The first to fourth lenses include at least one spherical lens adjacent to the object and at least one aspherical lens adjacent to the sensing unit, The distance between the first lens and the second lens is such that the center distance is greater than the edge distance, An optical system in which the third lens includes a convex object-side surface and a convex sensor-side surface on the optical axis.

2. In paragraph 1, The object-side surface of the first lens is convex on the optical axis, An optical system in which the effective diameter of the object-side surface of the first lens is the largest among the effective diameters of the object-side surfaces and the sensor-side surfaces of the first to fourth lenses.

3. In paragraph 1, The first lens includes a concave sensor side surface on the optical axis, An optical system wherein the second lens includes an object-side surface that is concave on the optical axis.

4. In paragraph 1, The above fourth lens has a biconvex shape on the optical axis, An optical system in which the object-side surface of the fourth lens has a critical point between the optical axis and the end of the effective area.

5. In any one of paragraphs 1 to 4, An optical system comprising a first aperture arranged around an area between the second lens and the third lens.

6. In paragraph 5, An optical system wherein the spacing between the second and third lenses is such that the center spacing is smaller than the edge spacing.

7. In any one of paragraphs 1 to 4, An optical system comprising a second aperture arranged around the object-side surface of the first lens.

8. In any one of paragraphs 1 to 4, The first to fourth lenses are made of glass, The object-side surface and the sensor-side surface of each of the first and third lenses are spherical, The object-side surface and the sensor-side surface of the second lens are aspherical, An optical system in which the object-side surface and the sensor-side surface of the fourth lens are aspherical.

9. In paragraph 8, The focal length of the second lens is the largest among the absolute values ​​of the focal lengths of the first to fourth lenses, The power of the second to fourth lenses is positive, the optical system.

10. A first lens having a convex object-side surface and a concave sensor-side surface on the optical axis; A second lens arranged on the sensor side of the first lens; a third lens arranged on the sensor side of the second lens; and Includes a fourth lens arranged on the sensor side of the third lens, Among the first to fourth lenses, the lens having the largest effective diameter is made of glass. Among the first to fourth lenses, the lenses having aspherical surfaces on the object side and the sensor side are made of glass. An optical system wherein the second lens has a minimum effective diameter among the first to fourth lenses and has a convex meniscus shape toward the image sensor on the optical axis.

11. In paragraph 10, The composite focal length of the first and second lenses has a positive value, An optical system in which the composite focal lengths of the third and fourth lenses have negative values.

12. In paragraph 10, The central thickness of the first lens is the smallest among the central thicknesses of the first to fourth lenses, The above first lens has negative refractive power, An optical system wherein the second to fourth lenses have positive refractive power.

13. In any one of paragraphs 10 to 12, The center spacing between the first lens and the second lens is CG1, The central thickness of the first lens is CT1, and is thinner than the central thickness of each of the second and third lenses. Mathematical formula: 1 < CG1 / CT1 < 4 An optical system that satisfies .

14. Sensing unit; First to fourth lenses aligned along the optical axis toward the sensing unit from the object; and An optical filter disposed between the sensing unit and the fourth lens, The power of the above first lens is negative, The power of the above fourth lens is positive, The diagonal angle of view of the optical system is more than 100 degrees, Among the first to fourth lenses, the lens adjacent to the sensing unit has an aspherical surface on the object side and the sensor side, The first to fourth lenses are made of glass, The optical axis distance from the center of the sensor-side surface of the fourth lens to the surface of the image sensor is BFL, Half of the diagonal length of the above sensing part is ImgH, Mathematical formula: 4 < TTL / ImgH < 11 0 < BFL / ImgH < 3 Camera module that satisfies .

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