Transmission optical system, sensor system, and lidar device

Abstract

An optical system according to an embodiment of the present invention includes first to fourth lenses sequentially arranged from an object to a light source along an optical axis. The first lens has a positive power and the object side surface of the first lens has a convex shape on the optical axis. The second lens has a meniscus shape that is convex toward the object on the optical axis. The third lens has a negative power. The fourth lens has a positive power. The center-to-center distance between the second and third lenses is greater than that between any other pair of adjacent lenses. The light source side surface of the third lens has a concave shape on the optical axis and may have the smallest absolute value of the radius of curvature of any of the object side surfaces and the light source side surfaces of the first to fourth lenses.

Description

Transmission optics, 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 an optical system for LiDAR (Light detection and ranging) and a device having the same. The present invention relates to a mobile device having a transmitting 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 optical system and a sensor system having the same. The present invention provides a transmission 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 sequentially arranged along an optical axis from an object to a light source, wherein the first lens has a convex shape on the object-side surface on the optical axis and has positive power, the second lens has a meniscus shape convex toward the object on the optical axis, the third lens has negative power, and the fourth lens has positive power, and the center distance between the second and third lenses is the largest among the center distances between adjacent two lenses, the light-source-side surface of the third lens has a concave shape on the optical axis, and may be the smallest among the absolute values ​​of the radii of curvature of the object-side surfaces and the light-source-side surfaces of the first to fourth lenses.

[0007] According to an embodiment of the invention, the effective diameter of the third lens may be the minimum among the effective diameters of the first to fourth lenses. The object-side surface of the third lens may have a convex shape on the optical axis. The fourth lens may have a convex shape on both sides on the optical axis.

[0008] According to an embodiment of the invention, the center distance between the first lens and the second lens may be the minimum among the center distances between adjacent lenses, and may be less than 1 mm. The optical system may include a diffuser arranged on the object side of the first lens; and a light source arranged on the light source side of the fourth lens. The first to fourth lenses may be made of glass, and the fourth lens may have an aspherical shape. The angle of view of the optical system is FOV, and the optical axis distance from the object side surface of the first lens to the surface of the light source is TTL, and satisfies the mathematical formula: FOV < (TTL / n), where n may be the number of lenses.

[0009] According to an embodiment of the invention, the optical axis distance from the object-side surface of the first lens to the surface of the light source is TTL, the refractive index of the first lens is Nd1, and the mathematical expression: 50 < TTL / Nd1 < 100 can be satisfied. The maximum effective diameter among the object-side surface and the light source-side surface of the first to fourth lenses is CA_Max, the total focal length is F, and the mathematical expression: 0 < CA_Max / F < 1 can be satisfied. The effective diameter of the first lens can be the maximum among the effective diameters of the first to fourth lenses.

[0010] According to an embodiment of the invention, a transmission optical system includes a diffuser adjacent to an object; a light source irradiating laser light; and first to fourth lenses sequentially arranged along an optical axis between the diffuser and the light source, wherein the first lens has a meniscus shape convex toward the object, the third lens has negative power, the fourth lens has a biconvex shape on the optical axis, each of the first and second lenses has an effective diameter larger than an effective diameter of each of the third and fourth lenses, a center thickness of the first lens is CT1, a center thickness of the second lens is CT2, a center spacing between the first and second lenses is CG1, and a center spacing between the second and third lenses is CG2, and a mathematical equation: 1 < CG2 / (CT1 + CG1 + CT2) < 3 can be satisfied.

[0011] According to an embodiment of the invention, the central thickness of the third lens is CT3, the central thickness of the fourth lens is CT4, and the mathematical expression: 1 < CG2 / (CT3+CT4) < 4 can be satisfied. The maximum among the central thicknesses of each of the first to fourth lenses is CT_Max, and the maximum among the central intervals between the first to fourth lenses is CG_Max, and the mathematical expression: 0.2 < CT_Max / CG_Max < 0.7 can be satisfied.

[0012] According to an embodiment of the invention, the first to fourth lenses are made of glass, the first to third lenses have a spherical shape, and the fourth lens may have a positive power and an aspherical shape. The focal length of the optical system is F, and the optical axis distance from the light source side of the fourth lens to the surface of the light source is BFL, and the mathematical formula: 3 < F / BFL < 10 may be satisfied.

[0013] According to an embodiment of the invention, half of the diagonal length of the light source is RsH, and can satisfy the mathematical formula: 1.5 < BFL / LsH < 2.5. The angle of view of the optical system is FOV, and the optical axis distance from the object-side surface of the first lens to the surface of the light source is TTL, and satisfies the mathematical formula: 200 < (FOV*TTL) / n < 500, where n may be the number of lenses.

[0014] A lidar device according to an embodiment of the invention comprises a transmitting optical system having a light source, and first to fourth lenses aligned with a first optical axis from an object toward the light source; and a receiving optical system having an image sensor, and fifth to ninth lenses aligned with a second optical axis from an object toward the image sensor, wherein at least one lens of the first to fourth lenses adjacent to the light source is an aspherical lens, and at least two of the fifth to ninth lenses are aspherical lenses, the receiving optical system includes an optical filter disposed between spherical lenses, the number of aspherical lenses in the transmitting optical system is smaller than the number of spherical lenses, the angle of view of the transmitting optical system is 15 degrees or less, the distance from the object-side surface of the first lens in the transmitting optical system to the light source is greater than 60 mm and less than 200 mm, and the focal length in the transmitting optical system may be greater than 50 mm and less than 300 mm.

[0015] According to an embodiment of the invention, the light source may generate light in the range of 890 nm to 960 nm, and the optical filter may be a bandpass filter that transmits light in the range of 890 nm to 960 nm. The first to fourth lenses and the fifth to ninth lenses may all be made of glass.

[0016] According to an embodiment, it can have improved optical characteristics. The lidar transmission optical system of the invention can maximize the extraction efficiency of light emitted from the transmission optical system.

[0017] The lidar transmission optical system of the invention can have good optical properties in a low to high temperature range. Specifically, a plurality of lenses included in the transmission 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 glass mold lens and the glass lens. That is, the transmission optical system can effectively perform refractive power distribution in a low to high temperature range, and can prevent or minimize changes in optical properties in a low to high temperature range. Therefore, the optical system and sensor system according to the embodiment can maintain improved optical properties in various temperature ranges.

[0018] The lidar transmission optical system of the invention 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 have good optical performance in the periphery of the field of view.

[0019] The transmission optical system and sensor system according to the embodiment can satisfy a set angle of view and implement excellent optical characteristics through a combination of a glass mold lens and a glass lens. Therefore, the optical system can provide a sensor system for a vehicle. 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.

[0020] Fig. 1 is a side cross-sectional view of a transmission optical system of a lidar according to a first embodiment.

[0021] Fig. 2 is a table showing the lens characteristics of the transmission optical system of Fig. 1.

[0022] Fig. 3 is a table showing the aspherical coefficient of the lens in the transmission optical system of Fig. 1.

[0023] Fig. 4 is a graph showing data of diffraction MTF (Modulation Transfer Function) in the transmission optical system of Fig. 1.

[0024] Fig. 5 is a side cross-sectional view of a transmission optical system of a lidar according to a second embodiment.

[0025] Fig. 6 is a table showing the lens characteristics of the transmission optical system of Fig. 5.

[0026] Fig. 7 is a table showing the aspherical coefficient of the lens in the transmission optical system of Fig. 5.

[0027] Fig. 8 is a graph showing data of diffraction MTF in the transmission optical system of Fig. 5.

[0028] Figure 9 is data on the distortion characteristics of the transmission optical system of Figures 1 and 5.

[0029] Fig. 10 is a block diagram showing a sensor system having the transmission optical system of Figs. 1 and 6.

[0030] Fig. 11 is a side cross-sectional view showing the receiving optical system of the sensor system of Fig. 10.

[0031] FIG. 12 is a drawing showing an example of measuring an object in a vehicle having a sensor system of the invention.

[0032] Fig. 13 is a drawing showing an example of surrounding surveillance in a vehicle having a sensor system of the invention.

[0033] 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.

[0034] 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.

[0035] 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, the "sensor-side surface" may mean a surface of a lens facing the imaging surface (image sensor) based on the optical axis, and the "light source-side surface" may mean a surface of a lens facing the light source 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 concaveity 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 is almost 0. Hereinafter, the optical axis may include the center of each lens or a very narrow region near the optical axis.

[0036]

[0037] FIG. 1 and FIG. 5 are side cross-sectional views of the transmission optical system of the lidar according to the first and second embodiments.

[0038] Referring to FIGS. 1 and 5, a transmission optical system (100A) and a sensor system having the same can be mounted inside or outside a vehicle to monitor a driver or sense external objects or lanes. The transmission optical system (100A) includes a plurality of lenses, and the material of each of the plurality of lenses can be selected from glass or plastic. The linear expansion coefficient of the lens is lower for glass than for plastic, and a glass lens can suppress changes in the focal imaging position due to temperature changes. However, when the glass lenses are configured as spherical lenses, there is a limit to reducing the number of lenses, and there is a limit to reducing the size and weight.

[0039] The transmission optical system (100A) of the 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 of the object-side surface and the light source-side surface of the lens on the optical axis is a spherical surface. The aspherical lens is a lens in which at least one of the object-side surface and the light source-side surface of the lens on the optical axis is an aspherical surface. The object-side surface is the output-side surface of each lens or the surface close to the object, and the light source-side surface is the incident-side surface of each lens or the surface close to the light source.

[0040] The above-described transmission optical system (100A) may include a spherical glass lens and an aspherical glass lens. Furthermore, if at least one of the lenses includes an aspherical lens, the optical system (100A) may have a reduced overall length (TTL), and the aspherical lens may provide excellent correction for various aberrations, such as spherical aberration and chromatic aberration. Furthermore, the aspherical lens may minimize distortion at the periphery of the effective area.

[0041] The optical system (100A) may include n lenses, where the nth lens may be the last lens adjacent to the light source (126), and the (n-1)th lens may be the lens closest to the last lens. The n is an integer less than or equal to 5, and may be, for example, in the range of 3 to 5. The ratio of the spherical lens to the aspherical lens in the n lenses may be 3:1 or 2:2.

[0042] In the above transmission optical system (100A), the first lens (121, 131) closest to the object may be formed of a glass lens. The first lens (121, 131) has a small amount of expansion and contraction change due to external temperature changes, and its surface is not easily scratched, thereby preventing surface damage. Accordingly, in the optical system (100A), the lenses close to the object may be spherical lenses, and the lens(es) close to the light source may be aspherical lenses to control the path of the emitted light.

[0043] Within the optical system (100A), at least one lens close to the light source (126) may be an aspherical lens. For example, the nth lens may be an aspherical lens, and the nth aspherical lens may refract light from the exit side of the light source (126) into various paths. The aspherical lens may be a glass mold made of injection-molded glass. As another example, at least two lenses closest to the light source (126) may be aspherical lenses.

[0044] The lenses within the optical system (100A) may be made of glass. Since the rate of contraction and expansion due to temperature changes in the lenses made of glass is smaller than that of lenses made of plastic, the phenomenon of the central axis of the lenses tilting within the lens barrel can be suppressed.

[0045] The number of aspherical lenses in the optical system (100A) may be smaller than the number of spherical lenses. The lenses in the optical system may be made of glass, the spherical lenses may be made of glass, and the aspherical lenses may be made of glass mold material.

[0046]

[0047] Within the optical system (100A), the lens with the largest effective diameter is positioned closest to the aperture (ST) or the object, and may be made of glass and be a spherical lens. Within the optical system (100A), the lens with the smallest effective diameter is positioned closest to the aspherical lens, and may be a glass lens. The lens with the smallest effective diameter may be positioned between the spherical lens and the aspherical lens. The effective diameter of the aspherical lens may be smaller than the average effective diameter of the spherical lenses. Here, the effective diameter of each lens is the average value of the effective diameter of the object-side surface of each lens and the effective diameter of the light source-side surface.

[0048] Each of the lenses (121-124) 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.

[0049] The maximum central thickness of the above lenses may be greater than the maximum edge thickness of the lenses. The maximum central thickness of the above lenses may be less than the maximum value of the central spacing between two adjacent lenses.

[0050] Within the optical system (100A), the TTL (Total top length) may be more than 5 times, for example, more than 5 times and less than 15 times, than the LsH. The TTL (Total track length) is the distance from the center of the object-side surface of the first lens (121, 131) to the surface of the light source (126) on the optical axis (OA1). The LsH is the distance from the center of the light source (126) to the diagonal end or half of the maximum diagonal length of the light source (126). In addition, the effective diameter of each lens within the optical system (100A) may be greater than the diagonal length of the light source (126).

[0051] Within the optical system (100A), the effective focal length (EFL) is provided to be greater than 50 mm and the field of view (FOV) is provided to be less than 30 degrees, so that it can be provided as a standard transmission optical system in a vehicle sensor system. For example, the transmission optical system and sensor system according to the embodiment can be applied to a sensing device for an Advanced Driving Assistance System (ADAS) installed inside or outside a vehicle. The optical system (100A) can be applied to a lidar transmission system.

[0052]

[0053] The above optical system (100A) may have a condition of TTL / (2*LsH) of more than 2.5 times and less than 10 times. Accordingly, the central thickness of each lens along the optical axis (OA1) can be increased and the size of the light source (126) can be reduced, thereby providing a vehicle lens optical system. In addition, temperature compensation must be applied in the temperature range that serves as the temperature reliability evaluation standard for automotive electrical components for use in vehicle cameras, that is, from -40°C to 120°C. That is, 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 total effective focal length (F) may be more than 50 mm, for example, in the range of 50 mm < F < 200 mm, and may be configured with lenses made of glass capable of the aforementioned temperature compensation. The transmitting optical system (100A) may provide an effective focal length greater than the effective focal length of the receiving optical system to implement a narrow angle.

[0054]

[0055] The light source (126) generates a laser beam, and the wavelength of the laser beam may be in the range of 800 nm to 1000 nm, for example, in the range of 890 nm to 960 nm or 940 nm ± 10 nm. As another example, the wavelength of the laser beam may be 1550 nm ± 10 nm. The light source (126) may be implemented as a semiconductor diode laser based on a compound semiconductor, for example, InGaAs / GaAs, and may emit high power laser light. The light source (126) may include a single emitter and / or multiple emitters. The light source (126) generates laser light in the form of a line light source or a point light source.

[0056] In the optical system (100A), the number of lenses having positive (+) refractive power may be two or more, and the number of lenses having negative (-) refractive power may be two or less. The powers of the first lens (121, 131) and the last lens may both have positive values. In the optical system (100A), a lens having a minimum radius of curvature among the object-side surface and the light source-side surface of the lenses may have negative power. In the optical system (100A), a lens having a minimum central thickness among the lenses may have negative power. In the optical system (100A), a lens having a minimum effective diameter among the lenses may have negative power. In the optical system (100A), a central distance between a lens having negative power and another lens may be greater than a central thickness of the lens having the negative power.

[0057] The lens having the negative power may be arranged on the object side rather than the aspherical lens. The lens having the negative power may be a spherical lens. Since the optical system (100A) is a mixture of a spherical lens and an aspherical lens made of glass, optical performance degradation can be prevented. In addition, the average central thickness of the lenses within the optical system (100A) is provided to be 5 mm or more, so that the lenses can be provided with strong heat resistance. The effective diameter of the first lens (121, 131) closest to the object side within the optical system (100A) may be larger than the effective diameter of the last lens closest to the light source (126). Accordingly, the brightness of the receiving optical system can be controlled. By controlling the effective diameter size and central thickness of each lens, the optical system (100A) can control the irradiated light to improve resolution, prevent degradation of optical characteristics due to temperature changes, and control chromatic aberration characteristics. By adjusting the effective diameter and thickness of the above lenses, the assemblability of the optical system (100A) can be improved.

[0058]

[0059] <First embodiment>

[0060] Referring to FIGS. 1 to 3, the optical system (100A) may include a first lens (121), a second lens (122), a third lens (123), and a fourth lens (124) that are sequentially aligned from an object toward a light source along an optical axis (OA1). The first to fourth lenses (121, 122, 123, 124) may be defined as a lens unit. The optical system (100A) may include a diffuser (Diffuser, 120) and may be defined as a transmission optical system or a transmission lens assembly. Laser light generated from the light source (126) may be emitted by the fourth lens (124), the third lens (123), the second lens (122), and the first lens (121) and irradiated to a subject through the diffuser (120).

[0061] The above aperture (ST) may be arranged between the object-side surface of the first lens (121) and the diffuser (120). The aperture (ST) may be arranged closer to the object-side surface of the first lens (121) than the diffuser (120), so as to control the amount of light emitted through the first lens (121). The diffuser (120) is arranged on the object-side surface of the aperture (ST), and may refract light traveling through the aperture (ST) into parallel light toward the subject. The diffuser (120) may have a microlens array on the object-side surface or the light source-side surface, and the path of the traveling light is controlled using the microlens array.

[0062]

[0063] The power of the first lens (121) may be positive (+) or negative (-) on the optical axis (OA1). The power of the first lens (121) has a positive (+) value. The first lens (121) may include a plastic material or a glass material, and may be, for example, a glass material. The first lens (121) made of a glass material can reduce changes in the center position and the radius of curvature due to temperature changes according to the surrounding environment, and can protect the output side surface of the optical system (100A). The object-side first surface (S1) of the first lens (121) with respect to the optical axis may be convex, and the light source-side second surface (S2) may be concave. The first surface (S1) and the second surface (S2) may have spherical surfaces. The first lens (121) may have a meniscus shape that is convex toward the object side. In contrast, the first surface (S1) may have a concave shape and the second surface (S2) may have a convex shape on the optical axis (OA1). Since the first surface (S1) is convex and the second surface (S2) is concave, the emitted light can be refracted in a direction close to the optical axis (OA1), the gap between the first and second lenses (121, 122) can be reduced, and the effective diameter of the first lens (121) can be reduced. By the shape of the lens surface of the first lens (121), the effective diameter of the light source-side surface of the second lens (122) can be designed to be smaller than the effective diameter of the object-side surface.

[0064] When the refractive index of the first lens (121) is Nd1, the condition of 1.70 < Nd1 or 1.70 < Nd1 < 2.0 can be satisfied. Since the refractive index (Nd1) of the first lens (121) exceeds 1.70, the radius of curvature of the second surface (S2) of the first lens (121) can be larger than the radius of curvature of the lens surfaces of the aspherical lens, and lens manufacturing can be easy. When the refractive index (Nd1) of the first lens (121) is smaller than the condition, the lens surfaces must be formed to be sharply concave or convex in order to increase the refractive power of the first and second lenses (121, 122). In this case, lens manufacturing is not easy, the lens defect rate increases, and this may cause a decrease in yield.

[0065]

[0066] Since the first lens (121) is arranged on the light source side of the aperture (ST) and diffuser (120), the center thickness (CT1) of the first lens (121) can be provided to be thinner than the center thickness (CT2) of the second lens (122). Since the first lens (121) is arranged on the light source side of the aperture (ST) and diffuser (120), it can have the largest effective diameter among the lenses. Since the first lens (121) is arranged on the light source side of the aperture (ST) and diffuser (120), it can have a radius of curvature that is larger than the average radius of curvature of the second lens (122). Since the first lens (121) has a positive refractive power (F1 > 0), the first lens (121) can refract the emitted light in the direction of the optical axis, and can suppress an increase in the distance from the light source side or rear side lens of the first lens (121).

[0067]

[0068] The second lens (122) may be arranged between the first lens (121) and the third lens (123). The power of the second lens (122) may be positive (+) or negative (-) on the optical axis (OA1). The power of the second lens (122) has a positive value. The second lens (122) may include a plastic or glass material, and may be provided as a spherical lens made of glass, for example. The object-side third surface (S3) of the second lens (122) on the optical axis (OA1) may be convex, and the light source-side fourth surface (S4) may be concave. The third and fourth surfaces (S3, S4) may be spherical. Alternatively, the third surface (S3) may be convex, and the fourth surface (S4) may be convex. Alternatively, the second lens (122) may have a concave shape on both sides. When the refractive index of the second lens (122) is Nd2, the condition of 1.70 < Nd2 or 1.70 < Nd2 < 2.10 can be satisfied. The refractive index (Nd2) of the second lens (122) can be higher than the refractive index of the last lens or the aspherical lens. In addition, the radius of curvature of the third surface (S3) of the second lens (122) can be larger than the radius of curvature of the object-side surface of the last lens or the aspherical lens, so that lens manufacturing can be easy.

[0069] Since the third surface (S3) of the second lens (122) is convex and has a radius of curvature smaller than that of the second surface (S2), the center spacing between the first and second lenses (121, 122) can be less than 1 mm or smaller than the thickness of the diffuser (120). Since the fourth surface (S4) of the second lens (122) is concave and has a radius of curvature larger than that of the third surface (S3), the center spacing (CG2) between the second lens (122) and the third lens (123) can be spaced apart by 10 mm or more, and an increase in the effective diameter of the third lens (123) can be suppressed.

[0070]

[0071] The power of the third lens (123) can be positive (+) or negative (-) on the optical axis (OA1). The power of the third lens (123) can have a negative (-) value. The third lens (123) can include a plastic or glass material, and can be, for example, glass. The fifth surface (S5) on the object side of the third lens (123) on the optical axis can be convex, and the sixth surface (S6) on the light source side can be concave. The third lens (123) can have a meniscus shape that is convex toward the object on the optical axis (OA1). At least one or both of the fifth surface (S5) and the sixth surface (S6) can be spherical. Alternatively, the third lens (123) can have a meniscus shape that is convex on both sides or convex toward the light source. Alternatively, the third lens (123) may have a concave shape on both sides of the optical axis.

[0072]

[0073] The power of the fourth lens (124) may have a positive (+) or negative (-) refractive power on the optical axis (OA1). The power of the fourth lens (124) may have a positive value. The fourth lens (124) may include a plastic or glass material, and may be provided as a glass material. The fourth lens (124) may be an injection-molded glass mold. The seventh surface (S7) on the object side of the fourth lens (124) on the optical axis may be convex, and the eighth surface (S8) on the light source side may be convex. The fourth lens (124) may have a convex shape on both sides on the optical axis (OA1). Alternatively, the fourth lens (124) may have a meniscus shape that is convex toward the light source. Alternatively, the fourth lens (124) may have a concave shape on both sides on the optical axis (OA1). At least one or both of the seventh surface (S7) and the eighth surface (S8) may be aspherical. The aspherical coefficients of the seventh and eighth surfaces (S7, S8) may be provided as L4S7 and L4S8 of FIG. 3. The seventh surface (S7) may be provided without a critical point from the optical axis (OA1) to the end of the effective area. The eighth surface (S8) may be provided without a critical point from the optical axis (OA1) to the end of the effective area. As another example, at least one of the seventh surface (S7) and the eighth surface (S8) may have a critical point. Here, the critical point may mean a point where the sign of the gradient value with respect to the optical axis (OA1) and the direction perpendicular to the optical axis (OA1) changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the gradient value is 0. Additionally, the critical point may be a point where the slope value of the tangent passing through the lens surface increases and decreases, or a point where it decreases and then increases.

[0074] The effective diameter of the fourth lens (124) may be larger than that of the third lens (123). The effective diameter of the third lens (123) may be the smallest among the lenses. The powers of the first and second lenses (121, 122) and the fourth lens (124) may have positive values, and the power of the third lens (123) may have negative values. At least one of the object-side surface and the light source-side surface of the fourth lens (124) may have a free-form surface, that is, a non-rotationally symmetrical surface. The fourth lens (124) may be an aspherical lens closest to the light source (126). By means of the lens surface having the aspherical surface, aberrations such as spherical aberration and chromatic aberration can be improved.

[0075]

[0076] The center thicknesses of the first to fourth lenses (121 to 124) are represented by CT1 to CT4, the edge thicknesses at the ends of the effective areas of each lens are represented by ET1 to ET4, and the center gap between two adjacent lenses can be defined as CG1 to CG3. The first to fourth lenses (121 to 124) can satisfy at least one of the following conditions.

[0077] Condition 1: CT3 < CT1 < CT2 Condition 2: CT2 < CT4

[0078] Condition 3: (CT2-CT1) < (CT4-CT3) Condition 4: ET1 < ET3 < CT2

[0079] Condition 5: 0 < CG1 < 1mm Condition 6: CG3 < CG2

[0080] Condition 7: CT4 < CG2 Condition 8: CT1 < CG3

[0081] Condition 9: CT1+CT2 < CG2

[0082] The center thickness (CT4) of the fourth lens (124) is the largest among the lenses, and the center thickness (CT3) of the third lens (123) is the smallest among the lenses. The maximum center thickness may be 10 mm or more thicker than the minimum center thickness. That is, by providing a thick center thickness for the two lenses adjacent to the object, heat resistance and assembling properties can be improved, and by arranging a thick aspherical lens, optical performance degradation on the light source (126) can be prevented, and the size (light source height) of the sensor system can be adjusted.

[0083]

[0084] Since the aperture (ST) and the diffuser (120) are arranged on the object side of the first lens (121), the center thickness (CT1) of the first lens (121) is thinner than the center thickness (CT2) of the second lens (122), and the radius of curvature is provided to be larger than the radius of curvature of the second lens (122), so that light incident through the second lens (122) can be refracted toward the diffuser (120). Among the first to fourth lenses (121-124), the maximum distance between adjacent lenses is CG_Max, and among the first to fourth lenses (121-124), the minimum distance between adjacent lenses is CG_Min, and the mathematical expression: 50 < CG_Max / CG_Min can be satisfied.

[0085] Since the center distance (CG2) between the second lens (122) and the third lens (123) is the largest among the center distances between adjacent lenses, the effective diameters of the first and second lenses (121, 122) may be larger than the effective diameter of the third lens (123). The effective diameter of the third lens (123) is the smallest among the lenses, and the radius of curvature of the sixth surface (S6) of the third lens (123) is the smallest among the lens surfaces, so that light incident through the fourth lens (124) can be refracted to the second lens (122) without loss. The effective diameter of each of the first to fourth lenses (121-124) may be larger than the diagonal length of the light source (126). The fourth lens (124) has an aspherical surface and can guide the incident light to a spherical lens. By adjusting the radius of curvature and effective diameter of each of the above lenses, the Chief Ray Angle (CRA) can be minimized from the optical axis to the end of the effective area, i.e., in the entire field, thereby maximizing the transmission efficiency. Here, when the CRA is large, the asymmetry of the divergence angle (Divergence Angel) with respect to the center of the light source (126) of the transmission optical system (100A) increases, which may reduce the transmission efficiency.

[0086]

[0087] The optical axis distance between the first lens (121) and the diffuser (120) is CG0 and may be less than 5 mm. Since the diffuser (120) is spaced apart from the convex first surface (S1) of the first lens (121) by the distance, an increase in the effective length of the diffuser (120) can be suppressed.

[0088] The above diffuser (120) can refract the light emitted through the first lens (121) and emit it as parallel light. Since the light emitted through the first lens (121) is provided as parallel light, the radius of curvature of the object-side surface of the fifth lens (101) of the receiving optical system of FIG. 11 can be provided to be large. Accordingly, the amount of light incident through the fifth lens (101) can be increased. The diagonal length of the diffuser (120) may be larger than the maximum diameter of the light source (126) and larger than the maximum diameters of the third and fourth lenses (123, 124). The emission-side surface of the diffuser (120) is the object-side surface, and the incident-side surface is the light source-side surface.

[0089]

[0090] The transmitting optical system (100A) having the first to fourth lenses (121-124) can spread the horizontal field of view (HFOV) of the receiving optical system (100) to 120 degrees or more since the object-side diffuser (120) is arranged in a one-dimensional shape. In the optical system (100A), the sum of the refractive indices of the lenses of the lens unit (100A) is 6 or more, for example, in the range of 6 to 10. The sum of the Abbe numbers of each of the lenses is 160 or less, for example, in the range of 100 to 160. By adjusting the refractive indices of the lenses in the transmitting optical system (100A), it is possible to prevent a decrease in transmission efficiency for a temperature change of -45 to 120 degrees and to optimize thermal compensation. In addition, by adjusting the Abbe numbers of the lenses, it is possible to minimize a deviation in transmission efficiency according to a wavelength.

[0091]

[0092] The sum of the central thicknesses of all lenses may be 20 mm or more, for example, in the range of 20 mm to 80 mm, and the average of the central thicknesses may be 5 mm or more, for example, in the range of 5 mm to 25 mm. The sum of the central spacings between the lenses on the optical axis (OA1) may be 20 mm or more, for example, in the range of 20 mm to 80 mm, and the maximum central spacing between the lenses may be greater than the maximum central thickness of the lenses. In addition, the maximum of the effective diameters of each lens surface of the transmission optical system (100A) may be greater than the maximum central spacing. The transmission optical system (100A) may adjust the thickness of the lenses to prevent degradation of optical performance for temperature changes from -45 degrees to 120 degrees and to optimize thermal compensation.

[0093] In the transmission optical system according to the first embodiment of the invention, the angle of view may be less than 30 degrees, for example, more than 1 degree and less than 30 degrees, or more than 5 degrees and less than 15 degrees. The F number of the optical system may be 5 or more, for example, in the range of 5 to 20 or in the range of 7 to 17. The diagonal length of the light source (126) may be 10 mm or more, and may be greater than the height of the image sensor in the vertical direction. The invention can provide a vehicle lidar device that suppresses a change in a focus imaging position due to temperature change by stacking glass lenses and corrects various aberrations by providing an aspherical lens.

[0094]

[0095] FIG. 2 is an example of lens data of the transmission optical system of FIG. 1. As shown in FIG. 2, the radius of curvature of the optical axis (OA1) of the first to fourth lenses (121, 122, 123, and 124), the center thickness (CT) of the lenses, the center spacing (CG) between the lenses, the refractive index at the d-line, the Abbe number, and the size of the effective diameter can be set. As shown in FIG. 3, among the lenses of the embodiment, the lens surface of the fourth lens (124) may include an aspherical surface having a radius of curvature (R), a conic constant (K), and a 14th-order aspherical coefficient (A to E). For example, the object-side surface and the light source-side surface of the fourth lens (124) may be lens surfaces having a 14th-order aspherical coefficient. As described above, an aspherical surface with a 14th aspherical coefficient (a non-zero value) can significantly change the aspherical shape of the periphery, and thus can provide good optical performance correction in the periphery of the field of view (FOV).

[0096] When comparing the focal lengths in absolute values, the focal length of the first lens (121) is the largest among the lenses and can be 150 or more. Accordingly, the optical system can have improved MTF characteristics, aberration control characteristics, etc. in the set angle of view range, and can have good optical performance.

[0097]

[0098] FIG. 4 is a graph showing the diffraction MTF (Modulation Transfer Function) in the transmitting optical system of FIG. 1, and is a graph showing the modulation according to the spatial frequency at room temperature. The optical system has chromatic aberration, which can be corrected using the last aspherical lens. In addition, since the amount of change in the characteristics of the glass lenses due to temperature change is small, it is effective to correct the chromatic aberration between the lenses even when the temperature changes. In addition, F, BFL, F#, FOV, TTL, and RsH can satisfy the following conditions. Here, F is the effective focal length of the receiving optical system, BFL is the optical axis distance from the last lens, that is, the fourth lens (104), to the surface of the light source (126), F# is the F number of the optical system, TTL is the optical axis distance from the first lens (121) to the surface of the light source (126), FOV is the angle of view of the receiving optical system, and RsH is half the diagonal length of the light source.

[0099] Condition 1: FOV < F# Condition 2: BFL < F

[0100] Condition 3: F#*FOV < TTL Condition 4: EPD < RsH

[0101] Condition 5: RsH < BFL

[0102]

[0103] <Second embodiment>

[0104] A second embodiment will be described with reference to FIGS. 5 to 8, and in the configuration and description of the second embodiment, the same configuration and description as in the first embodiment will be omitted.

[0105] Referring to FIGS. 5 to 7, the optical system (100A) may include a first lens (131), a second lens (132), a third lens (133), and a fourth lens (134). An aperture (ST) may be disposed between the object-side surface of the first lens (131) and a diffuser (120). The aperture (ST) may be disposed closer to the object-side surface of the first lens (131) than to the diffuser (120), thereby controlling the amount of light emitted through the first lens (131).

[0106] The first to fourth lenses (131-134) may be made of glass. The first to third lenses (131, 132, 133) are spherical lenses. The first, second, and fourth lenses (131, 132, 134) may have positive power values, and the third lens (133) may have negative power values. The first surface (S1) of the first lens (131) may be convex, and the second surface (S2) may be concave. The first surface (S1) and the second surface (S2) may have spherical surfaces. The refractive index (Nd1) of the first lens (131) may satisfy the condition of 1.70 < Nd1 or 1.70 < Nd1 < 2.0. The center thickness (CT1) of the first lens (131) may be provided to be thinner than the center thickness (CT2) of the second lens (132). The first lens (131) may have the largest effective diameter among the lenses. The first lens (131) may have a radius of curvature greater than the average radius of curvature of the second lens (132). Since the first lens (131) has positive refractive power (F1 > 0), the first lens (131) may refract the emitted light in the direction of the optical axis, and may suppress an increase in the distance from the light source side or the rear side lens of the first lens (131).

[0107]

[0108] The object-side third surface (S3) of the second lens (132) may be convex, and the light source-side fourth surface (S4) may be concave. The third and fourth surfaces (S3, S4) may be spherical. When the refractive index of the second lens (132) is Nd2, the condition of 1.70 < Nd2 or 1.70 < Nd2 < 2.10 may be satisfied. The refractive index (Nd2) of the second lens (132) may be higher than the refractive index of the last lens or the aspherical lens. In addition, the radius of curvature of the third surface (S3) of the second lens (132) may be larger than the radius of curvature of the object-side surface of the last lens or the aspherical lens, so that lens manufacturing may be easy. Since the third surface (S3) of the second lens (132) is convex and has a radius of curvature smaller than that of the second surface (S2), the center spacing between the first and second lenses (131, 132) can be less than 1 mm or smaller than the thickness of the diffuser (120). Since the fourth surface (S4) of the second lens (132) is concave and has a radius of curvature larger than that of the third surface (S3), the center spacing (CG2) between the second lens (132) and the third lens (133) can be spaced apart by 10 mm or more, and an increase in the effective diameter of the third lens (133) can be suppressed.

[0109]

[0110] On the optical axis, the object-side fifth surface (S5) of the third lens (133) may be convex, and the light source-side sixth surface (S6) may be concave. At least one or both of the fifth surface (S5) and the sixth surface (S6) may be spherical. On the optical axis, the object-side seventh surface (S7) of the fourth lens (134) may be convex, and the light source-side eighth surface (S8) may be convex. The fourth lens (134) may have a shape in which both sides are convex on the optical axis (OA1). At least one or both of the seventh surface (S7) and the eighth surface (S8) may be aspherical. The aspherical coefficients of the seventh and eighth surfaces (S7, S8) may be provided as L4S7 and L4S8 of FIG. 7. The seventh surface (S7) may be provided without a critical point from the optical axis (OA1) to the end of the effective area. The eighth surface (S8) may be provided without a critical point from the optical axis (OA1) to the end of the effective area. As another example, at least one of the seventh surface (S7) and the eighth surface (S8) may have a critical point. The effective diameter of the fourth lens (134) may be larger than the effective diameter of the third lens (133). The effective diameter of the third lens (133) may be the smallest among the lenses. The fourth lens (134) may be an aspherical lens closest to the light source (136). By means of the lens surface having an aspherical surface, aberrations such as spherical aberration and chromatic aberration can be improved.

[0111]

[0112] The first to fourth lenses (131 to 134) may satisfy at least one of the following conditions.

[0113] Condition 1: CT3 < CT1 < CT2 Condition 2: CT4 < CT2

[0114] Condition 3: (CT4-CT3) < (CT2-CT1) Condition 4: ET1 < ET3 < CT2

[0115] Condition 5: 0 < CG1 < 1mm Condition 6: CG3 < CG2

[0116] Condition 7: CT4 < CG2 Condition 8: CT1 < CG3

[0117] Condition 9: CT1+CT2 < CG2

[0118] The center thickness (CT2) of the second lens (132) is the largest among the lenses, and the center thickness (CT3, CT4) of the third or fourth lens (133, 134) is the smallest among the lenses. The maximum center thickness can be 5 mm or more thicker than the minimum center thickness. That is, by providing a thick center thickness for the two lenses adjacent to the object, heat resistance and assembling ability can be improved, and by arranging a thick aspherical lens, optical performance degradation on the light source (136) can be prevented, and the size (light source height) of the sensor system can be adjusted.

[0119]

[0120] Since the aperture (ST) and the diffuser (120) are arranged on the object side of the first lens (131), the center thickness (CT1) of the first lens (131) is thinner than the center thickness (CT2) of the second lens (132), and the radius of curvature is provided to be larger than the radius of curvature of the second lens (132), so that light incident through the second lens (132) can be refracted toward the diffuser (120). Among the first to fourth lenses (131-134), the maximum distance between adjacent lenses is CG_Max, and among the first to fourth lenses (131-134), the minimum distance between adjacent lenses is CG_Min, and the mathematical expression: 50 < CG_Max / CG_Min can be satisfied.

[0121] Since the center distance (CG2) between the second lens (132) and the third lens (133) is the largest among the center distances between adjacent lenses, the effective diameters of the first and second lenses (131, 132) can be larger than the effective diameter of the third lens (133). The effective diameter of the third lens (133) is the smallest among the lenses, and the radius of curvature of the sixth surface (S6) of the third lens (133) is the smallest among the lens surfaces, so that light incident through the fourth lens (134) can be refracted to the second lens (132) without loss.

[0122] The effective diameter of each of the first to fourth lenses (131-134) may be greater than the diagonal length of the light source (126). The fourth lens (134) has an aspherical surface and can guide the incident light to a spherical lens. By adjusting the radius of curvature and the effective diameter of each lens, the Chief Ray Angle (CRA) can be minimized from the optical axis to the end of the effective area, i.e., throughout the entire field, thereby maximizing the transmission efficiency.

[0123]

[0124] The optical axis distance between the first lens (131) and the diffuser (120) is CG0 and may be less than 1 mm. Since the diffuser (120) is spaced apart from the convex first surface (S1) of the first lens (131) by the distance, an increase in the effective length of the diffuser (120) can be suppressed. Since the light emitted through the first lens (131) is provided as parallel light, the radius of curvature of the object-side surface of the fifth lens (101) of the receiving optical system of FIG. 11 can be provided to be large. Accordingly, the amount of light incident through the fifth lens (101) can be increased. The diagonal length of the diffuser (120) may be greater than the maximum diameter of the light source (126) and the effective diameters of the third and fourth lenses (133, 134).

[0125] The transmitting optical system (100A) having the first to fourth lenses (131-134) can spread the horizontal field of view (HFOV) of the receiving optical system (100) to 120 degrees or more since the object-side diffuser (120) is arranged in a one-dimensional shape. In the optical system (100A) of the embodiment, the sum of the refractive indices of the lenses of the lens unit (100A) is 6 or more, for example, in the range of 6 to 10. The sum of the Abbe numbers of each of the lenses is 160 or less, for example, in the range of 100 to 160. By adjusting the refractive indices of the lenses in the transmitting optical system (100A), it is possible to prevent a decrease in transmission efficiency for a temperature change of -45 to 120 degrees and to optimize thermal compensation. In addition, by adjusting the Abbe numbers of the lenses, it is possible to minimize a deviation in transmission efficiency according to a wavelength.

[0126] The sum of the central thicknesses of all lenses may be 20 mm or more, for example, in the range of 20 mm to 80 mm, and the average of the central thicknesses may be 5 mm or more, for example, in the range of 5 mm to 25 mm. The sum of the central spacings between the lenses on the optical axis (OA1) may be 20 mm or more, for example, in the range of 20 mm to 80 mm, and may be greater than the sum of the central thicknesses of the lenses. In addition, the maximum central spacing between the lenses may be greater than the maximum central thickness of the lenses. In addition, the maximum of the effective diameters of each lens surface of the transmission optical system (100A) may be greater than the maximum central spacing. The transmission optical system (100A) may adjust the thickness of the lenses to prevent degradation of optical performance for temperature changes from -45 degrees to 120 degrees and to optimize thermal compensation.

[0127]

[0128] In the transmission optical system according to the second embodiment of the invention, the angle of view may be less than 30 degrees, for example, more than 1 degree and less than 30 degrees, or more than 5 degrees and less than 15 degrees. The F number of the optical system may be 5 or less, for example, in the range of 0.5 to 5 or in the range of 1 to 3. The diagonal length of the light source (126) may be 10 mm or more, and may be greater than the height of the image sensor in the vertical direction. The invention may provide a vehicle lidar device that suppresses a change in a focus imaging position due to temperature change by stacking glass lenses and corrects various aberrations by providing an aspherical lens.

[0129] As shown in Fig. 7, among the lenses of the embodiment, the lens surface of the fourth lens (134) may include an aspherical surface having a radius of curvature (R), a conic constant (K), and a 14th-order aspherical coefficient (A to E). For example, the object-side surface and the light source-side surface of the fourth lens (134) may be lens surfaces having a 14th-order aspherical coefficient. As described above, an aspherical surface having a 14th-order aspherical coefficient (a value other than “0”) 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).

[0130]

[0131] When comparing the focal lengths in absolute values, the focal length of the first lens (131) is the largest among the lenses and can be 120 or more. Accordingly, it can have improved MTF characteristics, aberration control characteristics, etc. in the field of view range set in the optical system, and can have good optical performance. Fig. 8 is a graph showing the diffraction MTF in the transmission optical system of Fig. 1, and is a graph showing the modulation of the luminance according to the spatial frequency at room temperature.

[0132] Additionally, F, BFL, F#, FOV, TTL and RsH can satisfy the following conditions.

[0133] Condition 1: F# < FOV Condition 2: BFL < F

[0134] Condition 3: F#*FOV < EPD < TTL Condition 4: RsH < EPD

[0135] Condition 5: RsH < BFL

[0136]

[0137] The first and second embodiments are optical systems applied to a lidar device, and the first lens (121, 131) may be provided with a glass material. This is because glass has the advantage of being scratch-resistant and insensitive to external temperature compared to plastic materials. In order to be placed inside a vehicle or to more effectively prevent scratches caused by foreign substances, a glass lens may be used as the first lens (121, 131), and the object-side surface of the first lens (121, 131) may have a convex shape to prevent external foreign substances from accumulating. 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). Fig. 9 is a table showing the distortion characteristics of the receiving optical system according to the first and second embodiments, and it can be seen that the change in the distortion characteristics from the center (0.OF) of the light source to the edge (1.0F) is not large.

[0138] The optical system (100A) according to the first and second embodiments 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 the emitted light toward the lenses. Hereinafter, the optical system according to the embodiment will be described in detail. The transmission optical system according to the first and second embodiments can prevent the degradation of optical performance from low to high temperatures by considering the characteristics of the vehicle optical system. For example, after designing the lens at room temperature, the value of the dn / dt, which is a temperature-dependent refractive index change coefficient, is assembled by considering 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 to third lenses are made of a spherical glass material, and the fourth lens is made of an aspherical glass material.

[0139]

[0140] The optical system (100A) 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 (100A) according to the embodiment can have improved optical characteristics. For example, when the optical system (100A) satisfies at least one mathematical equation, the optical system (100A) can effectively control aberration characteristics such as chromatic aberration and distortion aberration, and can have good optical performance even in the center and periphery of the field of view (FOV). In addition, the optical system (100A) can have improved resolution. In addition, the thickness of the lens on the optical axis (OA1) described in the mathematical equations and the spacing between adjacent lenses on the optical axis (OA1) may refer to the embodiment disclosed above.

[0141] [Mathematical Formula 1] 0 < CT1 / CT2 < 1

[0142] CT1 is the central thickness of the first lens, and CT2 is the central thickness of the second lens. In mathematical expression 1, by setting the central thickness (CT1) of the first lens (121, 131) and the central thickness (CT2) of the second lens (122, 132), the rigidity of the first lens (121, 131) can be prevented from decreasing, and factors affecting aberration can be controlled. In addition, by providing the first and second lenses as glass lenses with the above thickness, heat resistance can be improved. Preferably, mathematical expression 1 can satisfy 0.3 < CT1 / CT2 < 0.8.

[0143] [Equation 2] 0.5 < CT4 / CT3 < 7

[0144] CT3 and CT4 are the central thicknesses of the third and fourth lenses. By setting the central thicknesses of the third and fourth lenses in mathematical expression 2, it is possible to prevent the rigidity and optical characteristics of the glass lens from decreasing, and to control factors affecting aberration. Preferably, mathematical expression 2 can satisfy 1 < CT4 / CT3 < 5. Preferably, the first embodiment can satisfy 2 < CT4 / CT3 < 5, and the second embodiment can satisfy 1 < CT4 / CT3 < 2.

[0145] [Mathematical Formula 3] 1 < CT2 / CT3 < 7

[0146] In mathematical expression 3, the central thickness of the second and third lenses can be set, so that thermal compensation can be optimized according to temperature changes from low to high temperatures, and deterioration of optical performance can be prevented. Preferably, mathematical expression 3 can satisfy 1 < CT2 / CT3 < 5. Preferably, the first embodiment can satisfy 2 < CT2 / CT3 < 5, and the second embodiment can satisfy 1 < CT2 / CT3 < 3.

[0147] [Equation 4] 1 < CG2 / CT2 < 4

[0148] CG2 is the center distance between the second and third lenses. In mathematical expression 4, by setting the center distance between the second and third lenses to the above range, light refracted through the spherical third lens (123, 133) can be transmitted to the effective area of ​​the second lens (122, 132) by the center distance (CG2) between the second and third lenses. When mathematical expression 4 is satisfied, the difference in effective diameters between the second and third lenses may be the largest among the differences in effective diameters between adjacent two lenses. When mathematical expression 4 is satisfied, the difference in the radius of curvature between the object-side surface and the light source-side surface of the third lens may be the largest among the differences between the radii of curvature of the object-side surface and the light source-side surface of each lens. mathematical expression 4 may satisfy 1 < CG2 / CT2 < 3.

[0149] [Equation 5] 1 < CG2 / (CT3+CT4) < 4

[0150] In mathematical expression 5, the difference in effective diameter between the first and second lenses can be reduced by setting the center distance (CG2) between the second and third lenses to be greater than the sum of the center thicknesses (CT3, CT4) of the third and fourth lenses. In addition, the effective diameter of the second lens (122, 132) can be adjusted by the effective diameter and radius of curvature of the third lens and the center distance (CG2) between the second and third lenses. Mathematical expression 5 can satisfy 1 < CG2 / (CT3+CT4) < 3.

[0151] [Equation 6] 500 < CG2 / CG1 < 200

[0152] CG1 is the center spacing between the first and second lenses. In mathematical expression 6, the center spacing between the first and second lenses (CG1) and the center spacing between the second and third lenses (CG2) can be set to set the center spacing between the spherical lenses. Preferably, mathematical expression 6 can satisfy 100 < CG1 / CG2 < 190. Accordingly, the center spacing between the second and third lenses can be increased, and the center spacing between the first and second lenses can be decreased.

[0153] [Equation 7] 1 < CG2 / CG3 < 4

[0154] In mathematical expression 7, the center spacing (CG2) between the second and third lenses is set to be greater than the center spacing (CG3) between the third and fourth lenses, so that the center spacing between the spherical lens and the aspherical lens can be reduced compared to the center spacing between the object-side spherical lenses. Preferably, mathematical expression 7 can satisfy 1.2 < CG2 / CG3 < 2.6.

[0155] [Equation 8] 1 < CG2 / (CT1+CG1+CT2) < 3

[0156] In mathematical expression 8, the center distance (CG2) between the second and third lenses can be set to be greater than the optical axis distance between the object-side surface of the first lens (121, 131) and the light source-side surface of the second lens (122, 132). Accordingly, the effective diameter of the object-side surface of the first lens (121, 131) can be set to be greater than the effective diameter of the object-side surface of the second lens (122, 132), and the first and second lenses can have a convex meniscus shape toward the object. Preferably, mathematical expression 8 can satisfy 1 < CG2 / (CT1+CG1+CT2) < 2.

[0157] [Equation 9] TTL < SD

[0158] SD is the optical axis distance from the aperture (ST) to the surface of the light source (126), and TTL is the optical axis distance from the object-side surface of the first lens to the surface of the light source. Preferably, the aperture (ST) can be arranged around the perimeter of the object-side surface of the first lens (121, 131) or the perimeter of the light-source-side surface of the diffuser (120). When the optical system satisfies mathematical expression 9, the aperture (ST) can be positioned at the farthest position from the light source (126), that is, closer to the object than the first lens (121, 131), thereby controlling the amount of light emitted.

[0159] [Equation 10] 1.70 < Nd1

[0160] Nd1 is the refractive index at the d-line of the first lens (121, 131). In Equation 10, by setting the refractive index of the first lens (121, 131) 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. Equation 10 can preferably satisfy 1.75 < Nd1 < 2.0. If it is designed to be lower than the lower limit of Equation 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 Equation 10, there is a disadvantage in that it is difficult to obtain materials. Additionally, when the refractive index of the first lens (121) is designed to be lower than the lower limit of mathematical expression 4, the radius of curvature of the first and second lenses may be increased to increase the refractive power of the first and second lenses.

[0161] [Equation 10-1] 1.7 < Aver(Nd1:Nd4) < 1.8

[0162] Aver(Nd1:Nd4) is the average of the refractive index values ​​at the d-line of the first to fourth lenses. When mathematical expression 10-1 is satisfied, the optical system (100A) can suppress the influence of TTL.

[0163] [Equation 11] 0.5 < Nd1 / Nd3 < 1.5

[0164] Nd1 and Nd3 are the refractive indices of the first and third lenses at the d-line. In Equation 11, the difference in the refractive indices of the first lens (121 and 131) and the third lens (123 and 133) can be reduced, thereby preventing the reduction in color dispersion caused by the lenses made of glass. Preferably, the refractive indices of the first, second, and third lenses can be the same.

[0165] [Equation 12] 0.5 < Nd1 / Nd4 < 1.5

[0166] 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 first lens (121, 131) higher than the refractive index of the fourth lens (124, 134), the color dispersion by the spherical material lens and the color dispersion by the aspherical lenses can be controlled. Preferably, Equation 12 can satisfy 0.8 < Nd1 / Nd4 < 1.3.

[0167] [Mathematical Formula 13] (Vd2*Nd2) < (Vd4*Nd4)

[0168] Nd2, Nd4 are the refractive indices of the 2nd and 4th lenses at the d-line, and Vd2, Vd4 are the Abbe numbers of the 2nd and 4th lenses. In mathematical expression 13, by setting the product of the refractive index and the Abbe number of the 2nd lens (121, 131) to be smaller than the product of the refractive index and the Abbe number of the 4th lens (124, 134), the color dispersion by the spherical material lenses and the color dispersion by the aspherical lenses can be controlled.

[0169]

[0170] [Equation 14] TD < SD

[0171] TD is the optical axis distance from the object-side surface of the first lens (121) to the light source-side surface of the fourth lens (124). When the optical system satisfies mathematical expression 14, the aperture (ST) may be located on the object side relative to the first lens (121).

[0172] [Equation 14-1] TD < TTL < SD

[0173] If this mathematical expression 14-1 is satisfied, the position of the aperture (ST) can be set to be located on the object side relative to the first lens (121).

[0174] [Equation 15] 1 < CA42 < CT4 < 5

[0175] CA42 is the effective diameter of the fourth lens (124, 134) on the light source side, and CT4 is the central thickness of the fourth lens. If mathematical expression 15 is satisfied, the ratio of the effective diameter of the last lens to the central thickness can be set. Preferably, 1.2 < CA42 < CT4 < 4 can be satisfied.

[0176] [Equation 16] SA42 < CG2 < CA11

[0177] SA42 is the effective radius of the fourth lens, and CA11 is the effective diameter of the object-side surface of the first lens. If Equation 16 is satisfied, the center spacing between the second and third lenses can be increased, and the effective radius of the fourth lens can be set not to increase.

[0178] [Mathematical Formula 17] 1 < CA11 < (CG1+CG2) < 3

[0179] In mathematical expression 17, the effective diameter (CA11) of the object-side surface of the first lens, the center distance (CG1) between the first and second lenses, and the center distance (CG2) between the second and third lenses can be set, and if these are satisfied, the number of lenses of the spherical lenses can be reduced. Preferably, 1 < CA11 < (CG1+CG2) < 2.5 can be satisfied.

[0180] [Equation 18] 0.5 < CA11 / CA21 < 1.5

[0181] CA11 refers to the effective diameter of the first surface (S1) of the first lens (121, 131), and CA21 refers to the effective diameter of the third surface (S3) of the second lens (122, 132). When mathematical expression 18 is satisfied, the optical system (100A) can control the emitted light and set factors affecting aberration, and preferably, CA11 > CA21 can be satisfied.

[0182] [Mathematical Formula 19] 1< CA22 / CA31 < 3

[0183] CA22 denotes the effective diameter of the fourth surface (S4) of the second lens (122, 132), and CA31 denotes the effective diameter of the fifth surface (S5) of the third lens (123, 133). When mathematical expression 19 is satisfied, the optical system (100A) can control the light path to be emitted, and can set the second lens (122, 132) to have a convex shape toward the object. Preferably, mathematical expression 19 can satisfy 1.5 < CA22 / CA31 < 2.2.

[0184] [Equation 20] 0.5 < CA11 / DP_CA < 1.5

[0185] DP_CA denotes the effective diameter of the diffuser. When mathematical expression 20 is satisfied, the optical system (100A) can set a light path that is emitted to the diffuser (120) through the first lens (121). Mathematical expression 20 can preferably satisfy 1 ≤ CA11 / DP_CA < 1.3.

[0186] [Equation 21] 10 < CA11 / CG0

[0187] CA11 denotes the effective diameter of the first surface (S1) of the first lens (121, 131), and CG0 is the optical axis distance between the first lens (121, 131) and the aperture (ST) or diffuser (120). When the optical system (100A) satisfies mathematical expression 21, the effective diameter and radius of curvature of the first lens (121) can be adjusted. In mathematical expression 21, the first embodiment satisfies 15 < CA11 / CG0 < 35, and the second embodiment can satisfy 50 < CA11 / CG0 < 100. Here, CGO can satisfy 0 ≤ CG0 < 3.5 mm.

[0188] [Equation 22] 0 < CT1 / CG0

[0189] When the optical system satisfies mathematical expression 22, the optical axis distance (CG0) between the first lens (121, 131) and the aperture (ST) or diffuser (120) and the center thickness (CT1) of the first lens (121, 131) can be set, and the distortion aberration can be adjusted. Preferably, the first embodiment satisfies 3 < CT1 / CG0 < 5, and the second embodiment satisfies 5 < CT1 / CG0 < 15.

[0190]

[0191] [Equation 23] 1 < DP_CA / CA_Min < 4

[0192] CA_Min represents the smallest effective diameter among the lens surfaces of the lenses. If the optical system satisfies Equation 23, the entire optical axis length can be controlled. Preferably, 2 < ST_CA / CA_Max < 3 can be satisfied.

[0193] [Equation 24] 5 < CG_Max / CG0

[0194] CG_Max refers to the maximum center spacing between lenses in the optical system, for example, the center spacing between the second and third lenses. When the optical system satisfies mathematical expression 24, the maximum center spacing between the lenses can set the relationship between the optical axis spacing between the first lens (121, 131) and the aperture (ST) or diffuser (120), thereby adjusting the overall optical axis length and suppressing an increase in the effective diameter of the first lens (121, 131). Preferably, the first embodiment satisfies 5 < CG_Max / CG0 < 15, and the second embodiment satisfies 20 < CG_Max / CG0 < 70.

[0195] [Equation 25] 0 < CT4 / BFL < 1.5

[0196] BFL is the optical axis distance from the center of the light source side surface of the last lens to the light source (126). That is, BFL is the optical axis distance from the center of the eighth surface (S8) of the fourth lens (124) to the light source (126). When mathematical expression 25 is satisfied, the emitted light can be transmitted to the entire area of ​​the third lens (103) by the fourth lens (124). Preferably, 0.3 < CT4 / BFL < 1 can be satisfied.

[0197] [Equation 26] 0.5 < CG3 / CT4 < 3

[0198] CG3 represents the center spacing between the third and fourth lenses. When mathematical expression 26 is satisfied, the center spacing between the third and fourth lenses can be made narrower than the center spacing between the second and third lenses, and the effective diameter of the fourth lens (124, 134) can be adjusted. Preferably, the first embodiment satisfies 1 < CG3 / CT4 < 1.5, and the first embodiment can satisfy 1.5 < CG3 / CT4 < 2.5.

[0199] [Equation 27] 10 < DP_CA / CG0

[0200] When the transmitting optical system satisfies mathematical expression 27, the position of the diffuser (120) can be set, and due to the diffuser (120), the transmitting optical system and the receiving optical system can be optically matched even if they provide different aspect ratios. Preferably, the first embodiment satisfies 20 < DP_CA / CG0 < 50, and the second embodiment satisfies 50 < DP_CA / CG0 < 100.

[0201] [Equation 28] 2 < │L4R2│ / CT4 < 50

[0202] L4R2 is the radius of curvature of the light source-side surface of the fourth lens. When mathematical expression 28 is satisfied, the refractive power of the fourth lens (124, 134) can be controlled and the optical performance can be improved. Preferably, the first embodiment satisfies 2 < │L4R2│ / CT4 < 5, and the second embodiment satisfies 25 < │L4R2│ / CT4 < 50.

[0203]

[0204] [Equation 29] 1 < │L4R2│ / L4R1 < 20

[0205] L4R1 is the radius of curvature of the object-side surface of the fourth lens. When mathematical expression 29 is satisfied, the refractive power of the fourth lens (124, 134) can be controlled and the optical performance can be improved. Preferably, the first embodiment satisfies 1 < L4R2 / L4R1 < 3, and the second embodiment satisfies 5 < L4R2 / L4R1 < 15.

[0206] [Mathematical Formula 30] 0 < L1R1 / L1R2 < 1

[0207] L1R1 is the radius of curvature of the object-side surface of the first lens, and L1R2 is the radius of curvature of the light source-side surface of the first lens. When mathematical expression 30 is satisfied, the refractive power of the first lens (121, 131) can be controlled to improve optical performance, and the gap between the first and second lenses can be reduced. Preferably, 0 < L1R1 / L1R2 < 0.5 can be satisfied. When mathematical expression 30 is satisfied, the gap between the first lens (121, 131) and the aperture (ST) or diffuser (120) can be set. In addition, the conditions: L1R1 > 0 and L1R2 > 0 can be satisfied.

[0208] [Equation 31] 0.2 < L2R1 / L2R2 < 1.5

[0209] L2R1 is the radius of curvature of the object-side surface of the second lens, and L2R2 is the radius of curvature of the light source-side surface of the second lens. When mathematical expression 31 is satisfied, the refractive power of the second lens (122, 132) can be controlled to improve optical performance, and the incidence efficiency through the light source-side surface of the second lens (122, 132) can be improved. Preferably, 0.3 < L2R1 / L2R2 < 0.8 is satisfied, and L2R1 > 0 and L2R2 > 0 can be satisfied.

[0210] [Equation 31-1] 10 < L3R1 / L3R2 < 30

[0211] L3R1 is the radius of curvature of the object-side surface of the third lens, and L3R2 is the radius of curvature of the light source-side surface of the third lens. When mathematical expression 31-1 is satisfied, the refractive power of the third lens (123, 133) can be controlled and the optical performance can be improved, and light can be refracted into the effective area of ​​the second lens (122, 132) through the object-side surface of the third lens (123, 133). The radius of curvature can satisfy L3R1 > 0 and L3R2 > 0.

[0212] [Equation 32] 0 < CT_Max / CG_Max < 1

[0213] In Equation 32, the maximum central thickness (CT_Max) among the lenses and the maximum gap (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 TTL. Preferably, 0.2 < CT_Max / CG_Max < 0.7 can be satisfied.

[0214]

[0215] [Equation 33] 0.5 < ΣCT / ΣCG < 1.5

[0216] 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. Preferably, 0.5 < ΣCT / ΣCG < 1 can be satisfied.

[0217] [Equation 34] 5 < ΣNd < 15

[0218] 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 (100A) in which aspherical lenses and spherical lenses are mixed. 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 < 10.

[0219] [Equation 35] 10 < ΣVd / ΣNd < 50

[0220] ΣVd means the sum of the Abbe numbers of each of the plurality of lenses. When mathematical expression 35 is satisfied, the optical system (100A) 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, 17 < ΣVd / ΣNd < 23 can be satisfied.

[0221] [Equation 36] 1 < (ΣCT*n) / F < 3

[0222] F is the focal length of the optical system, and n is the number of lenses in the optical system. If mathematical expression 36 is satisfied, TTL can be controlled. Preferably, 1 < (ΣCT*n) / F < 2 can be satisfied.

[0223] [Equation 37] 3 < ΣCT / ΣET < 15

[0224] ΣET is the sum of the edge thicknesses of the lenses. When Equation 37 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. Equation 37 preferably satisfies 4 < ΣCT / ΣET < 10.

[0225] [Equation 38] 1 < CA11 / CA_Min < 5

[0226] CA_Min represents the minimum effective diameter among the object-side and light-source-side surfaces of the lenses. When mathematical expression 38 is satisfied, the optical system can control incident light and provide a module with improved optical performance. Mathematical expression 38 can preferably satisfy 2 < CA11 / CA_Min < 3. Here, CA32 may be the minimum effective diameter among the lens surfaces.

[0227] [Equation 38-1] 1 < CA_Max / CA_Min < 5

[0228] CA_Max represents the maximum effective diameter between the object-side and light-source-side surfaces of the lenses. If Equation 39 is satisfied, the optical system can have improved optical performance. Equation 39 preferably satisfies 2 < CA_Max / CA_Min < 3.

[0229] [Equation 39] 0 < CG2 / CA12 < 1

[0230] When mathematical expression 39 is satisfied, the incident light of the spherical lenses can be controlled. Mathematical expression 39 preferably satisfies 0.3 < CG2 / CA12 < 0.9.

[0231] [Equation 40] 0.5 < CG2 / CA31 < 2

[0232] If Equation 40 is satisfied, the optical system can maintain the optical performance of the final spherical lens. Equation 40 preferably satisfies 1 < CG2 / CA31 < 2.

[0233] [Equation 41] 0 < CA_Max / F < 1

[0234] F is the effective focal length of the optical system. If Equation 41 is satisfied, the optical system can provide a narrow angle of view. Equation 41 preferably satisfies 0.2 < CA_Max / F < 0.8.

[0235] [Equation 42] 1 < CA_Max / (2*LsH) < 6

[0236] LsH is half the diagonal length of the light source. Mathematical expression 42 can set the maximum effective diameter (CA_Max) and the diagonal length of the light source, and if this is satisfied, the optical system can maintain good optical performance. Mathematical expression 42 can preferably satisfy 2 < CA_Max / (2*LsH) < 4.

[0237] [Equation 42-1] 1 < TD / CA_Max < 4

[0238] TD is the optical axis distance from the center of the object-side surface of the first lens to the center of the light-source-side surface of the last lens. When Equation 42-1 is satisfied, the total optical axis distance and maximum effective diameter of the lenses can be set, thereby setting the size for good optical performance. Equation 42-1 can preferably satisfy 2 < TD / CA_Max < 3.

[0239] [Equation 43] 0 < F / |L4R2| < 3

[0240] F is the effective focal length of the optical system, and L4S2 is the radius of curvature of the light source side surface of the fourth lens. If mathematical expression 43 is satisfied, TTL can be adjusted by setting the effective focal length and the radius of curvature of the light source side surface of the aspherical lens. In mathematical expression 43, the first embodiment satisfies 1 < F / |L4R2| < 3, and the second embodiment can satisfy 0 < F / |L4R2| < 1.

[0241] [Equation 44] 0 < F / L1R1 < 2

[0242] 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 output light and TTL. Mathematical expression 44 can preferably satisfy 1 ≤ F / L1R1 < 1.5.

[0243] [Equation 45] 0 < EPD / |L4R2| < 0.5

[0244] EPD refers to the size of the entrance pupil of the optical system (100A). Here, the entrance pupil can be defined as the exit pupil in the case of a transmission optical system. When the transmission optical system (100A) according to the embodiment satisfies mathematical expression 45, the optical system (100A) can control the exit light. Preferably, the condition of 0 < EPD / |L4R2| < 0.3 can be satisfied. Preferably, L4R1 > 0, L4R2 < 0 can be satisfied.

[0245] [Equation 46] 0 < EPD / L1R1 < 1

[0246] In mathematical expression 46, the size of the entrance pupil of the optical system (100A) 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 (100A) can control the emitted light. Preferably, the condition of 0 < EPD / L1R1 < 0.8 can be satisfied.

[0247]

[0248] [Mathematical Formula 47] 0.5 < F2 / F < 2

[0249] F2 is the focal length of the second lens. If Equation 47 is satisfied, a lens optical system with a small angle of view can be provided. In addition, F2 > 0 can be satisfied. Preferably, 1 < F2 / F < 2 can be satisfied.

[0250] [Equation 48] 0.8 < F1 / F < 2

[0251] F1 is the focal length of the first lens. In Equation 48, the focal length of the first lens and the effective focal length of the optical system can be set, and the refractive power of the first lens can be controlled. Furthermore, if Equation 48 is satisfied, a lens optical system with a small angle of view and a small F-number can be provided. Furthermore, F1 > 0 can be satisfied.

[0252] [Equation 49] 0 < F4 / F < 1

[0253] In mathematical expression 49, the refractive power of the fourth lens can be controlled by setting the focal length (F4) of the fourth lens. When mathematical expression 49 is satisfied, a lens optical system can be provided in which the last lens adjacent to the light source has positive power and a small F number. Preferably, 0 < F4 / F < 0.5 can be satisfied.

[0254] [Mathematical Formula 49-1] |F3| < F4 (provided that F3 < 0)

[0255] Balancing the focal lengths of each lens can suppress differences in focus position due to temperature changes. This, in turn, prevents the optical properties of the lenses from deteriorating due to temperature changes. Furthermore, the overall focal length of the transmitting optical system can be greater than the overall focal length of the receiving optical system.

[0256] [Mathematical Formula 50] Po2 * Po3 < 0

[0257] Po2 is the power value of the second lens, and Po3 is the power value of the third lens. That is, the powers of the second and third lenses have opposite signs, which can improve aberrations and effectively guide light through the spherical lens. When the condition of Po2 * Po3 > 0, the improvement effect of chromatic aberration in the two lenses is not significant.

[0258] [Mathematical Formula 51] 60mm < TTL < 200mm

[0259] In mathematical expression 51, a vehicle optical system can be provided by setting the TTL to be less than 200 mm. Mathematical expression 51 can satisfy 100 mm < TTL < 200 mm. In addition, the number of lenses in the transmitting optical system may be smaller than the number of lenses in the receiving optical system. In addition, the number of aspherical lenses in the transmitting optical system may be smaller than the number of aspherical lenses in the receiving optical system.

[0260] [Mathematical Formula 52] 5mm < LsH < 16mm

[0261] LsH is half the diagonal length of the light source. Mathematical expression 52 can set the diagonal length of the light source (126) and provide an optical system having a vehicle sensor size. Mathematical expression 52 can preferably satisfy 7 mm < LsH < 13 mm.

[0262] [Mathematical Formula 53] 10mm < BFL < 30mm

[0263] In mathematical expression 53, the BFL (Back focal length) is set to be greater than 10 mm, thereby improving the assemblability of components and improving joint reliability through the gap between the light source (126) and the last lens. Preferably, mathematical expression 53 satisfies 15 mm < BFL < 25 mm. If the BFL is less than the range of mathematical expression 53, some of the light emitted from the light source may not be emitted, which may cause a decrease in resolution. If the BFL exceeds the range of mathematical expression 53, stray light may be emitted, which may deteriorate the aberration characteristics of the optical system.

[0264] [Mathematical Formula 54] 50mm < F < 300mm

[0265] Mathematical expression 54 can set the overall focal length (F) to suit the vehicle transmitting optical system. Mathematical expression 54 can satisfy 100 mm < F < 200 mm, and can be greater than the overall focal length of the receiving optical system.

[0266] [Mathematical Formula 55] 1 degree < FOV < 30 degrees

[0267] In mathematical expression 55, FOV (Field of view) means the angle of view (Degree) of the optical system (100A), and a vehicle optical system having an angle of view (F0V) of less than 30 degrees can be provided. Preferably, 5 ≤ FOV ≤ 15 can be satisfied. The angle of view of the transmitting optical system can be provided narrower than the angle of view of the receiving optical system. That is, even if the angle of view of the receiving optical system is implemented wide by the diffuser (120), the sensitivity of the detection unit can be prevented from being lowered. In addition, the condition: 1 ≤ RsH / F0V < 1.5 can be satisfied.

[0268] In mathematical expression 55, the range of the vehicle transmission optical system can be set by the angle of view. If mathematical expression 55 is satisfied, the rate of change in the effective focal length and the rate of change in the angle of view can be set low when the temperature changes from room temperature to high temperature. In addition, even if an aspherical lens is used in combination with a spherical lens within the optical system (100A), the deterioration of optical characteristics can be prevented through temperature compensation and aberration correction by the aspherical lens made of glass.

[0269]

[0270] [Mathematical Formula 56] 1 < TTL / CA_Max < 4

[0271] In mathematical expression 56, CA_Max refers to the largest effective diameter (mm) among the object-side and light-source-side surfaces of the plurality of lenses. Mathematical expression 56 sets the relationship between the total optical axis length of the optical system and the maximum effective diameter, thereby allowing the size of the vehicle optical system to be adjusted. Mathematical expression 56 preferably satisfies 1.3 < TTL / CA_Max < 2.3.

[0272] [Mathematical Formula 57] 5 < TTL / LsH < 20

[0273] Mathematical expression 57 can set the total optical axis length (TTL) of the optical system and the diagonal length (LsH) from the optical axis of the light source (126). When the optical system (100A) according to the embodiment satisfies Mathematical expression 57, the optical system (100A) can have a TTL for application to the vehicle light source (126). Mathematical expression 57 can preferably satisfy 8 < TTL / LsH < 15.

[0274] [Equation 58] 0 < BFL / LsH < 3

[0275] Mathematical expression 58 can set the optical axis distance between the light source (126) and the last lens and the diagonal length from the optical axis of the light source (126). When the optical system (100A) according to the embodiment satisfies Mathematical expression 58, the optical system (100A) can secure a BFL for applying the size of the vehicle light source (126), can set the distance between the last lens and the light source (126), and can have good optical characteristics in a narrow field of view (FOV). Mathematical expression 58 can preferably satisfy 1.5 < BFL / LsH < 2.5.

[0276] [Equation 59] 1 < TTL / BFL < 15

[0277] Mathematical expression 59 can set the total optical axis length (TTL) of the optical system and the optical axis spacing (BFL) between the light source (126) and the last lens. When the optical system (100A) according to the embodiment satisfies Mathematical expression 59, the optical system (100A) can secure BFL. Mathematical expression 59 can preferably satisfy 3 < TTL / BFL < 10.

[0278] [Equation 60] 0.5 < TTL / F < 2

[0279] Mathematical expression 60 can set the overall focal length (F) and overall optical axis length (TTL) of the optical system (100A). Accordingly, an optical system for a driver assistance system can be provided. Mathematical expression 60 can preferably satisfy 1 ≤ TTL / F < 1.5. When the optical system (100A) according to the embodiment satisfies Mathematical expression 60, the optical system (100A) can have an appropriate focal length 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 may become longer, which may cause a problem of the optical system becoming larger.

[0280]

[0281] [Equation 61] 3 < F / BFL < 10

[0282] Mathematical expression 61 can set the total focal length (F) of the optical system (100A) and the optical axis distance (BFL) between the light source (126) and the last lens. When the optical system (100A) according to the embodiment satisfies Mathematical expression 61, the optical system (100A) 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 (100A) can minimize the distance between the last lens and the light source (126), and thus can have good optical characteristics in the angle of view (FOV). Mathematical expression 61 can preferably satisfy 5 < F / BFL < 10.

[0283] [Equation 62] 5 < F / LsH < 20

[0284] Mathematical expression 62 can set the overall focal length (F) of the optical system (100A) and the diagonal length (LsH) from the optical axis of the light source (126). This optical system (100A) can have improved aberration characteristics in the size of the vehicle light source (126). Mathematical expression 62 can preferably satisfy 8 < F / LsH < 15.

[0285] [Equation 63] 1 < F / EPD < 18

[0286] Mathematical expression 63 can set the overall focal length (F) and entrance pupil size of the optical system (100A). Accordingly, the overall brightness of the optical system can be controlled. In other words, an optical system with a small F number can be provided. In Mathematical expression 63, the first embodiment satisfies 5 < F / EPD < 15, and the second embodiment satisfies 1 < F / EPD < 3.

[0287] [Mathematical Formula 64] 0 < EPD / LsH / FOV < 1

[0288] Mathematical expression 64 can set the relationship between the entrance pupil size (EPD), the length of half the diagonal length of the light source (LsH), and the field of view. Accordingly, the overall size and brightness of the optical system can be controlled. Mathematical expression 64 preferably satisfies 0.05 < EPD / LsH / FOV < 0.9.

[0289] [Equation 65] 0 < FOV / F# < 7

[0290] Mathematical expression 65 can establish the relationship between the angle of view and the F number (F#) of the optical system. In Mathematical expression 65, the first embodiment satisfies 0 < FOV / F# < 1, and the second embodiment satisfies 2 < FOV / F# < 7.

[0291] [Equation 66] 5 < (CT_Max+CG_Max) / n < 20

[0292] [Mathematical Formula 67] 200 < (FOV*TTL) / n < 500

[0293] Preferably, mathematical expression 67 can satisfy the condition of 250 < (FOV*TTL) / n < 400 depending on the angle of view and the number of lenses (n).

[0294] [Mathematical Formula 68] FOV < (TTL / n)

[0295] [Equation 69] 1 < (TD / CA_Max)*n < 10

[0296] Preferably, 3 < (TD / CA_Max)*n < 8 can be satisfied.

[0297] [Equation 70] 50 < TTL / Nd1 < 100

[0298] In mathematical expressions 66 to 70, n represents the total number of lenses, and depending on the total number of lenses, the relationship between the maximum center thickness (CT_Max), maximum center spacing (CG_Max), FOV, TTL, optical axis distance (TD) of the lenses, and refractive index (Nd1) of the first lens can be set. Accordingly, the chromatic aberration, resolution, size, etc. of an optical system having 5 or fewer lenses can be controlled.

[0299]

[0300] [Equation 71]

[0301]

[0302] In mathematical expression 71, 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.

[0303]

[0304] The optical system (100A) according to the embodiment can satisfy at least one or two or more mathematical expressions from mathematical expressions 1 to 70. In this case, the optical system (100A) can have improved optical characteristics. Specifically, when the optical system (100A) satisfies at least one of mathematical expressions 1 to 35 and / or at least one of mathematical expressions 36 to 70, the optical system (100A) can have improved resolution and improve aberration and distortion characteristics. In addition, the optical system (100A) can secure a back focal length (BFL) for applying a vehicle light source (126), can compensate for optical characteristic degradation due to temperature change, and can minimize the distance between the last lens and the light source (126), thereby having good optical performance within the field of view (FOV).

[0305] Table 1 shows the items of the mathematical formulas described above in the optical system (100A) of the embodiment, including the TTL (mm), BFL (mm), effective focal length (F), LsH, effective diameter (CA), sum of the center thicknesses of each lens, sum of the center spacings between adjacent lenses, TTL (mm), sum of Abbe numbers, sum of refractive indices, TD (mm), which is the optical axis distance from the first surface (S1) to the eighth surface (S8), angle of view (FOV), edge thickness (ET), F number, etc. of the optical system (100A).

[0306] Item Example 1 Example 2 Item Example 1 Example 2 F148.701155.651ET16.2806.279ΣNd7.0307.298ET26.28014.359ΣVd142.371159.022ET311.47917.902ΣCT60.24451.899ET46.2806.287ΣCG60.7287 3.244FOV9.0169.015ΣET7.58011.207EPD12.46186.473TTL143.700146.701BFL22.72 821.558F-number11.9341.800TD126.972128.143SD146.70040.1700LsH11.74011.731

[0307]

[0308] Table 2 shows the results for the mathematical expressions 1 to 35 described above in the optical system (100A) of the embodiment. Referring to Table 4, it can be seen that the optical system (100A) satisfies at least one, two or more, or three or more of the mathematical expressions 1 to 35. Accordingly, the optical system (100A) can have good optical performance within the field of view (FOV) and excellent optical characteristics.

[0309] Mathematical FormulaExample 1Example 210 < CT1 / CT2 < 10.5470.60820.5 < CT4 / CT3 < 74.5611.03631 < CT2 / CT3 < 74.4261.77641 < CG2 / CT2 < 41.7602.66951 < CG2 / (CT3+CT4) < 41.4012.327650 < CG2 / CG1 < 200126.062167.57971 < CG2 / CG3 < 41.6732.21881 < CG2 / (CT1+CG1+CT2) < 31.1271.6439TTL < SDSatisfiedSatisfied101.70 < Nd11.7981.821110.5 < Nd1 / Nd3 <1.50.9861.073120.5 < Nd1 / Nd4 <1.51.1171.00013(Vd2*Nd2) < (Vd4*Nd4)SatisfiedSatisfied14TD < SDSatisfiedSatisfied151 < CA42 / CT4 < 51.6973.38716SA42 < CG2 < CA11SatisfiedSatisfied171 < CA11 / (CG1+CG2) < 32.0611.640180.5 < CA11 / CA21 < 1.51.0621.049191 < CA22 / CA31 < 31.8091.841200.5 < CA11 / DP_CA < 1.51.0161.0082110 < CA11 / CG026.62383.597220 < CT1 / CG03.92011.460231 < DP_CA / CA_Min < 42.5452.635245 < CG_Max / CG012.60650.274250 < CT4 / BFL < 1.50.9740.510260.5 < CG3 / CT4 < 31.0212.0622710 < DP_CA / CG026.19282.925282 < |L4R2| / CT4 < 503.63338.781291 < |L4R2| / L4R1 < 201.7179.513300 < L1R1 / L1R2 < 10.2120.133310.2 < L2R1 / L2R2 < 1.50.5890.677320 < CT_Max / CG_Max < 10.5850.375330.5 < ∑CT / ∑CG < 1.50.9920.709345 < ∑Nd <157.0307.2983510 < ∑Vd / ∑Nd <5020.25121.788.

[0310]

[0311] Table 3 shows the results for mathematical expressions 36 to 70 described above in the optical system (100A) of the embodiment. Referring to Table 5, it can be seen that the optical system (100A) satisfies at least one, two or more, or three or more of mathematical expressions 36 to 70. Accordingly, the optical system (100A) can have good optical performance within the field of view (FOV) and excellent optical characteristics.

[0312] Mathematical Formula Example 1 Example 2 361 < (∑CT*n) / F < 31.6211.334373 < ΣCT / ΣET < 157.9484.631381 < CA11 / CA_Min < 52.5872.657390 < CG2 / CA12 < 10.4820.609400.5 < CG2 / CA31 < 21.0621.311410 < CA_Max / F < 10.5370.537421 < CA_Max / (2*LsH) < 63.4023.563430 < F / |L4R2| < 31.8490.365440 < F / L1R1 < 21.2981.090450 < EPD / |L4R2|< 0.50.1550.203460 < EPD / L1R1 < 10.1090.605470.5 < F2 / F < 21.1521.403480.8 < F1 / F < 21.2421.310490 < F4 / F < 10.3490.32850Po2 * Po3 < 0SatisfiedSatisfied5160 < TTL < 200143.700146.701525 < LsH < 1611.74011.7315310 < BFL < 3022.72821.5585450 < F < 300148.701155.651551 < FOV < 309.0169.015561 < TTL / CA_Max < 41.7991.755575 < TTL / LsH < 2012.24012.506580 < BFL / LsH < 31.9361.838591 < TTL / BFL < 156.3236.805600.5 < F / TTL < 21.0351.061613 < F / BFL < 106.5437.220625 < F / LsH < 2012.66613.269633 < F / EPD < 1811.9341.800640 < EPD / LsH / FOV < 10.1180.818650 < FOV / F# <70.7565.008665 < (CT_Max+CG_Max) / n < 2014.99017.27867200 < (FOV*TTL) / n < 500323.912330.63168FOV < (TTL / n)SatisfiedSatisfied691 < (TD / CA_Max) *n < 106.3596.1317050 < TTL / Nd1 < 10079.91880.547.

[0313]

[0314] FIG. 10 is a block diagram of a sensor system having a transmitting optical system according to an embodiment of the invention. Referring to FIG. 10, the sensor device includes a control unit (10), a light source driving unit (20), a transmitting optical system (30), a receiving 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 transmitting optical system (30). The light source generates laser light 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.

[0315] The wavelength of the laser light generated from the light source may be in the range of 800 nm to 1000 nm, for example, in the range of 890 nm to 960 nm or in the range of 940 nm ± 10 nm. The laser light source may be implemented as a semiconductor diode laser based on a compound semiconductor, for example, an InGaAs / GaAs, and may emit high power laser light. The light source may include a single emitter and / or multiple emitters.

[0316] The above-described transmitting optical system (30) transmits laser light generated from a light source to an object (40), and the light reflected from the object (40) is received by the receiving optical system (50). The receiving 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 image sensors are 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.

[0317] The signal processing unit (60) converts the output of the receiving 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.

[0318] 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.

[0319]

[0320] FIG. 11 is a drawing showing a receiving optical system according to an embodiment of the invention.

[0321] Referring to FIG. 11, the receiving optical system (100) may include fifth to ninth lenses (101, 102, 103, 104, 105) sequentially arranged from the object side to the image sensor (151). The fifth to ninth lenses (101, 102, 103, 104, 105) may have shapes and different numbers of lenses that are asymmetrical with respect to the object side compared to the first to fourth lenses (121, 122, 123, 124) of the transmitting optical system (100A) of FIG. 1.

[0322] The first to third lenses (121, 122, 123) and the fifth, seventh, and eighth lenses (101, 103, 104) are made of glass and are spherical lenses that are not injection-molded. In addition, the fourth lens (124) and the sixth and ninth lenses (102, 105) are made of glass and are aspherical lenses that are injection-molded. The aperture (ST) arranged between the seventh and eighth lenses (103, 104) may be arranged on the object side of the optical filter (115). The aperture of the transmitting optical system (100A) may be defined as a second aperture, and the aperture of the receiving optical system (100) may be defined as a first aperture.

[0323] The fifth lens (101) may have a positive (+) or negative (-) refractive power on the optical axis (OA). The fifth lens (101) may have a negative (-) refractive power. The fifth 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 receiving optical system (100).

[0324] The object-side surface of the fifth lens (101) may be convex with respect to the optical axis, and the sensor-side surface may be concave. The object-side surface and the sensor-side surface of the fifth lens (101) may have spherical surfaces. The fifth lens (101) may have a meniscus shape that is convex toward the object side. The object-side surface of the fifth lens (101) may have the largest radius of curvature among the first to ninth lenses. The sixth lens (102) may be arranged between the fifth lens (101) and the seventh lens (103). The sixth lens (102) may have positive (+) or negative (-) refractive power in the optical axis (OA). The sixth lens (102) may have negative (-) refractive power. The sixth lens (102) may include a plastic or glass material, and may be provided as an aspherical surface of a glass material, for example. The object-side surface of the sixth lens (102) based on the optical axis (OA) is concave, and the sensor-side surface may be concave.

[0325]

[0326] The seventh lens (103) may have positive (+) or negative (-) refractive power in the optical axis (OA). The seventh lens (103) may have positive (+) refractive power. The seventh lens (103) may include a plastic or glass material, and may be, for example, glass. The object-side surface of the seventh lens (103) with respect to the optical axis may be convex, and the sensor-side surface may be convex. The seventh lens (103) may have a shape in which both sides are convex in the optical axis (OA). At least one or both of the object-side surface and the light source-side surface of the seventh lens (103) may be spherical. An aperture (ST) may be arranged around the periphery of the sensor-side surface of the eighth lens (103). The seventh lens (103) adjacent to the object side of the aperture (ST) may have positive refractive power, thereby suppressing an increase in the effective diameter of the eighth lens (104). The eighth lens (104) may have positive (+) or negative (-) refractive power in the optical axis (OA). The eighth lens (104) may have positive (+) refractive power. The eighth lens (104) may include a plastic or glass material, and may be provided as a glass material. The eighth lens (104) may be a spherical lens. The object-side surface of the eighth lens (104) with respect to the optical axis may be convex, and the sensor-side surface may be convex.

[0327] The ninth lens (105) may have positive (+) or negative (-) refractive power in the optical axis (OA). The ninth lens (105) may have positive (+) refractive power. The ninth lens (105) may include a plastic or glass material, and may be provided as an aspherical surface made of glass. The ninth lens (105) may be injection molded. The object-side surface of the ninth lens (105) with respect to the optical axis may be convex, and the sensor-side surface may be convex. The ninth lens (105) may be the lens closest to the image sensor (151). The ninth lens (105) may have a refractive index lower than the refractive indices of the fifth and seventh lenses (101, 103).

[0328]

[0329] At least two lenses may be arranged between the optical filter (155) and the image sensor (151). For example, the eighth and ninth lenses (104, 105) may be arranged between the optical filter (155) and the image sensor (151). An aspherical lens and a spherical lens may be mixed between the optical filter (155) and the image sensor (151). The optical filter (155) may be arranged between the spherical seventh lens (103) and the spherical eighth lens (108). The optical filter (155) may be arranged between the sensor-side surface of the seventh lens (103) and the object-side surface of the eighth lens (104). The optical filter (155) may be a band pass filter that passes a laser beam in the range of 800 nm to 1000 nm, for example, in the range of 890 nm to 960 nm or 940 nm ± 10 nm. The above optical filter (155) can pass light having a wavelength corresponding to a laser beam transmitted from a transmission optical system of a lidar device and block light corresponding to the remaining ambient light.

[0330] The cover glass (153) is disposed between the ninth lens (105) and the image sensor (151), and protects the upper portion of the image sensor (151) and can prevent the reliability of the image sensor (151) from being deteriorated. The cover glass (153) can be removed. The cover glass (153) may be a protective glass. The image sensor (151) can detect light that has sequentially passed through the lenses. The image sensor (151) may include an element capable of detecting incident light, such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). The light-emitting area of ​​the light source (126) may be different from the light-receiving area of ​​the image sensor (151). The ninth lens (105) may be an aspherical lens that is closest to the image sensor (151). Two or more aspherical lenses can be placed within the receiving optical system (100).

[0331]

[0332] FIG. 12 is a drawing showing an example of measuring an object in a vehicle having the sensor system of the invention, and FIG. 13 is a drawing showing an example of surrounding surveillance in a vehicle having the sensor system of the invention.

[0333] Referring to FIGS. 12 and 13, a vehicle (202) having a sensor system includes a transmitting optical system that projects laser light (201) generated by a light source toward a target scene, and a receiving 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 (106) 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 and receiving 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.

[0334] The receiving 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.

[0335] 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 the side-view "surround view" field of view and range (206), but with a longer range requirement. Typically, a vehicle's sensor functions 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 present 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, unmanned aerial vehicles, boats, ships, and the like.

[0336]

[0337] 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. 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, 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. Includes first to fourth lenses arranged sequentially along the optical axis from the object toward the light source, The above first lens has a convex shape on the object-side surface on the optical axis and has positive power. The above second lens has a convex meniscus shape toward the object on the optical axis, The above third lens has negative power, The above fourth lens has positive power, The center spacing between the second and third lenses is the maximum among the center spacings between adjacent two lenses. An optical system in which the light source-side surface of the third lens has a concave shape on the optical axis, and the absolute value of the curvature radii of the object-side surfaces and the light source-side surfaces of the first to fourth lenses is the minimum.

2. In paragraph 1, An optical system in which the effective diameter of the third lens is the smallest among the effective diameters of the first to fourth lenses.

3. In paragraph 1, An optical system in which the object-side surface of the third lens has a convex shape on the optical axis.

4. In any one of paragraphs 1 to 3, The above fourth lens is an optical system having a convex shape on both sides on the optical axis.

5. In any one of paragraphs 1 to 3, An optical system wherein the center spacing between the first lens and the second lens is the smallest among the center spacings between adjacent lenses and is less than 1 mm.

6. In any one of paragraphs 1 to 3, An optical system including a diffuser arranged on the object side of the first lens; and a light source arranged on the light source side of the fourth lens.

7. In any one of paragraphs 1 to 3, The above first to fourth lenses are made of glass, The above fourth lens is an optical system having an aspherical shape.

8. In any one of paragraphs 1 to 3, The angle of view is FOV, The optical axis distance from the object side of the first lens to the surface of the light source is TTL, Mathematical Formula: FOV < (TTL / n) An optical system where n is the number of lenses.

9. In any one of paragraphs 1 to 3, The optical axis distance from the object side of the first lens to the surface of the light source is TTL, The refractive index of the above first lens is Nd1, Mathematical formula: Optical system satisfying 50 < TTL / Nd1 < 100.

10. In any one of paragraphs 1 to 3, The maximum effective diameter among the object-side surface and the light source-side surface of the first to fourth lenses is CA_Max, The overall focal length is F, Mathematical Formula: 0 < CA_Max / F < 1 An optical system that satisfies .

11. In clause 10, An optical system in which the effective diameter of the first lens is the largest among the effective diameters of the first to fourth lenses.

12. Diffuser adjacent to the object; A light source that irradiates laser light; and It includes first to fourth lenses sequentially arranged along the optical axis between the diffuser and the light source, The above first lens has a convex meniscus shape toward the object, The above third lens has negative power, The above fourth lens has a biconvex shape on the optical axis, Each of the first and second lenses has an effective diameter larger than that of each of the third and fourth lenses, The central thickness of the above first lens is CT1, The central thickness of the above second lens is CT2, The center spacing between the first and second lenses is CG1. The center spacing between the second and third lenses is CG2. Mathematical formula: 1 < CG2 / (CT1+CG1+CT2) < 3 A transmission optical system satisfying .

13. In paragraph 12, The central thickness of the above third lens is CT3, The central thickness of the above fourth lens is CT4, Mathematical formula: A transmission optical system satisfying 1 < CG2 / (CT3+CT4) < 4.

14. In clause 12 or 13, The maximum central thickness of each of the first to fourth lenses is CT_Max, The maximum of the center spacings between the first to fourth lenses is CG_Max, Mathematical formula: 0.2 < CT_Max / CG_Max < 0.7, The above first to fourth lenses are made of glass, The first to third lenses have a spherical shape, The above fourth lens is a transmitting optical system having positive power and an aspherical shape.

15. A transmitting optical system having a light source and first to fourth lenses aligned with a first optical axis from the object toward the light source; and A receiving optical system comprising the image sensor and fifth to ninth lenses aligned along a second optical axis from the object toward the image sensor, At least one lens adjacent to the light source among the first to fourth lenses is an aspherical lens, At least two of the fifth to ninth lenses are aspherical lenses, The above receiving optical system includes an optical filter arranged between spherical lenses, The number of aspherical lenses in the above transmission optical system is smaller than the number of spherical lenses. The angle of view of the above transmission optical system is less than 15 degrees, In the above transmitting optical system, the distance from the object side of the first lens to the light source is greater than 60 mm and less than 200 mm, In the above transmitting optical system, the focal length is greater than 50 mm and less than 300 mm, A lidar device wherein the first to fourth lenses and the fifth to ninth lenses are all made of glass.

Images