Optical system, sensor system, and lidar device

Abstract

An optical system according to embodiments of the present invention comprises: a first lens to a fifth lens arranged along an optical axis from an object toward a sensing unit; and an optical filter disposed in any one of regions between the second to fifth lenses. The first lens has a meniscus shape, convex toward the object, on the optical axis. The object-side surface of the third lens has a concave shape on the optical axis. The radius of curvature of the object-side surface of the first lens on the optical axis is L1R1. The radius of curvature of a sensor-side surface of the first lens on the optical axis is L1R2. The mathematical expression 1<L1R1 / L1R2<5 can be satisfied.

Description

Optical systems, sensor systems and lidar devices

[0001] The present invention relates to an optical system and a sensor system for transmitting or receiving. The present invention relates to a receiving optical system and a sensor system having the same. The present invention relates to a transmitting optical system and a sensor system having the same. The present invention relates to a receiving optical system for LIDAR (Light Detection and Ranging) and a device having the same. The present invention relates to a mobile device having a receiving optical system and system for LIDAR.

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

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

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

[0005] The present invention provides an optical system having improved optical characteristics and a sensor system having the same. The present invention provides a wide-angle optical system and a sensor system having the same. The present invention provides a receiving optical system, a sensor system, and a lidar device having improved thermal compensation characteristics. The present invention provides a transmitting 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 fifth lenses aligned along an optical axis from an object toward a sensing unit; and an optical filter disposed in any one of regions between the second to fifth lenses, wherein on the optical axis, the first lens has a convex meniscus shape toward the object, and an object-side surface of the third lens has a concave shape on the optical axis, and a radius of curvature of the object-side surface of the first lens on the optical axis is L1R1, and a radius of curvature of the sensor-side surface of the first lens on the optical axis is L1R2, and a mathematical equation: 1 < L1R1 / L1R2 < 5 can be satisfied.

[0007] According to an embodiment of the invention, the object-side surface of the second lens on the optical axis may have a convex shape. The sensor-side surface of the fourth lens on the optical axis may have a convex shape. The sensor-side surface of the fifth lens on the optical axis may have a convex shape. Among the absolute values ​​of the radii of curvature of the object-side surfaces and the sensor-side surfaces of the first to fifth lenses, the radius of curvature of the sensor-side surface of the fifth lens may be the largest.

[0008] According to an embodiment of the invention, the optical filter may be positioned between two lenses among the first to fifth lenses, the central thickness of which is thicker than that of the other lenses. The optical filter may be positioned between the third lens and the fourth lens.

[0009] According to an embodiment of the invention, the optical axis distance from the optical filter to the surface of the sensing unit is DF2, and the optical axis distance from the sensor-side surface of the fifth lens to the surface of the sensing unit is BFL, and can satisfy the mathematical expression: BFL < DF2. An aperture is disposed around the object-side surface of the optical filter or the sensor-side surface of the third lens, and the optical axis distance from the aperture to the surface of the sensing unit is SD, and can satisfy the mathematical expression: 1 < SD / DF2 < 1.2. The optical axis distance from the center of the object-side surface of the first lens to the optical filter is DF1, and can satisfy the mathematical expression: DF2 < DF1.

[0010] According to an embodiment of the invention, the first to fifth lenses may be made of glass. The object-side surface and the sensor-side surface of the second and fifth lenses may be aspherical.

[0011] According to an embodiment of the invention, the optical filter is a band pass filter that passes a range of 890 nm to 960 nm, and the center spacing between the object-side lens and the sensor-side lens of the optical filter may be the largest among the center spacings between the first to fifth lenses.

[0012] According to an embodiment of the invention, the first and second lenses may have negative refractive power, and the third to fifth lenses may have positive refractive power. The center spacing between the third and fourth lenses may be CG3, the thickness of the optical filter may be OFt, and the mathematical expression: 2 < CG3 / OFt < 15 may be satisfied.

[0013] In an embodiment, improved optical properties can be achieved. Specifically, in an optical system according to an embodiment, the bandpass filter can be positioned near the stop to minimize the incident angle of light entering the filter. Accordingly, the transmittance range of the bandpass filter can be broadly utilized depending on the incident angle of light on the bandpass filter.

[0014] The receiving optical system of the inventive lidar can maximize the effect of receiving light emitted from the transmitting optical system. According to an embodiment, it can have improved optical characteristics. The inventive lidar device can maximize the extraction efficiency of light emitted from the transmitting / receiving optical system.

[0015] The receiving optical system of the inventive lidar can have good optical characteristics in a low to high temperature range. Specifically, a plurality of lenses included in the receiving 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. In other words, the optical system can effectively distribute refractive power in a low to high temperature range, and can prevent or minimize changes in optical characteristics in a low to high temperature range. Therefore, the optical system and sensor system according to the embodiment can maintain improved optical characteristics in various temperature ranges.

[0016] The optical system of the inventive lidar may have lenses with set thicknesses, refractive powers, and spacings from adjacent lenses. Accordingly, the optical system and sensor system according to the embodiment may have improved MTF characteristics, aberration control characteristics, resolution characteristics, etc. within a set field of view range, and may exhibit good optical performance in the periphery of the field of view.

[0017] The optical system and sensor system according to the embodiment can achieve excellent optical characteristics while satisfying a set angle of view through a combination of a glass mold lens and a glass lens. This allows the optical system to provide a slimmer vehicle sensor system. Accordingly, the optical system and sensor system can be used in various applications and devices, and can maintain excellent optical characteristics even in harsh temperature environments, such as when exposed to the exterior of a vehicle or in the high temperatures of a vehicle interior during the summer.

[0018] Fig. 1 is a side cross-sectional view of a receiving optical system of a lidar according to an embodiment.

[0019] Figure 2 is a table showing the lens characteristics of the optical system of Figure 1.

[0020] Fig. 3 is a table showing the aspherical coefficients of lenses in the optical system of Fig. 1.

[0021] Figure 4 is data on the distortion characteristics of the optical system of Figure 1.

[0022] Figure 5 is a graph showing data of diffraction MTF (Modulation Transfer Function) according to low temperature, room temperature, and high temperature in the optical system of Figure 1.

[0023] Fig. 6 is a graph showing data on the aberration characteristics of the optical system of Fig. 1 at low temperatures.

[0024] Fig. 7 is a graph showing data on the aberration characteristics of the optical system of Fig. 1 at room temperature.

[0025] Fig. 8 is a graph showing data on the aberration characteristics of the optical system of Fig. 1 at high temperatures.

[0026] Fig. 9 is a graph comparing the transmittance curves when the incident angle of the main beam is 0 degrees, 20 degrees, and 40 degrees, as measured by automatic optical inspection (AOI) equipment for the filter of the optical system of Fig. 1.

[0027] Fig. 10 is a block diagram showing a sensor system having the optical system of Fig. 1.

[0028] Fig. 11 is a side cross-sectional view of a transmission optical system of a lidar according to an embodiment.

[0029] Fig. 12 is a drawing showing the first lens and diffuser of the optical system of Fig. 11.

[0030] Fig. 13 is a drawing comparing a comparative example and an embodiment with respect to the refractive characteristics of light by a lens array of a diffuser of the transmission optical system of Fig. 11.

[0031] Fig. 14 is a table showing the lens characteristics of the optical system of Fig. 11.

[0032] Fig. 15 is a table showing the aspherical coefficients of lenses in the optical system of Fig. 11.

[0033] Figure 16 is a graph showing data of diffraction MTF (Modulation Transfer Function) according to low temperature, room temperature, and high temperature in the optical system of Figure 11.

[0034] Fig. 17 is a graph showing data on the aberration characteristics of the optical system of Fig. 11 at low temperatures.

[0035] Fig. 18 is a graph showing data on the aberration characteristics of the optical system of Fig. 11 at room temperature.

[0036] Fig. 19 is a graph showing data on the aberration characteristics of the optical system of Fig. 11 at high temperatures.

[0037] Figure 20 is data on the distortion characteristics of the optical system of Figure 11.

[0038]

[0039] Figure 21 is a graph showing the pixel-by-pixel matching results according to the light source height and divergence angle in the transmission optical system of Figure 11.

[0040] Fig. 22 is a graph showing the pixel-by-pixel matching results according to the image height and angle of view in the receiving optical system of Fig. 1.

[0041] FIG. 23 is a drawing showing an example of measuring an object in a vehicle having a sensor system of the invention.

[0042] Fig. 24 is a drawing showing an example of surrounding surveillance in a vehicle having a sensor system of the invention.

[0043] 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.

[0044] 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.

[0045] In the description of the invention, the "object-side surface" may mean a surface of a lens facing the object side based on the optical axis (OA), and the "sensor-side surface" may mean a surface of a lens facing the imaging surface (surface of the sensing unit) based on the optical axis. The convexity of one surface of the lens may mean a convex shape in the optical axis or the paraxial region, and the concaveness of one surface of the lens may mean a concave shape in the optical axis or the paraxial region. The radius of curvature, center thickness, and optical axis spacing between lenses described in the table for lens data may mean values ​​(unit: mm) in the optical axis. The vertical direction may mean a direction perpendicular to the optical axis, and the end of a lens or lens surface may mean the end of an effective area of ​​a lens through which incident light passes. The size of the effective diameter of the lens surface may have a measurement error of up to ±0.4 mm depending on the measurement method, etc. The above-mentioned near-axis region refers to a very narrow region near the optical axis, and is a region where the distance a light ray falls from the optical axis (OA) is almost 0. Hereinafter, the optical axis may include the center of each lens or a very narrow region near the optical axis.

[0046]

[0047] Fig. 1 is a side cross-sectional view showing the receiving optical system of the invention.

[0048] Referring to Fig. 1, an optical system (100) 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 material of each of the lenses can be selected from glass or plastic, and the linear expansion coefficient of the lenses is lower in glass than in plastic. Therefore, lenses made of glass are employed to suppress changes in the focal imaging position due to temperature changes. However, when configuring an optical system with spherical glass lenses, there is a limit to reducing the number of lenses, and there is a limit to reducing the size and weight.

[0049] The optical system (100) of the embodiment of the invention is a receiving optical system, and may include a spherical lens and an aspherical lens. Here, the spherical lens is a lens in which at least one or both of the object-side surface and the sensor-side surface of the lens is spherical. The aspherical lens is a lens in which at least one or both of the object-side surface and the sensor-side surface of the lens is aspherical. The optical system (100) may include a spherical glass lens and an aspherical glass lens. In addition, by employing an aspherical lens, the overall length (TTL) of the optical system (100) may be reduced, and various aberrations such as spherical aberration and chromatic aberration may be well corrected due to the aspherical lens. In addition, the aspherical lens may minimize the distortion portion at the periphery of the sensing unit (151). The optical system (100) may include n lenses, the n-th lens may be the last lens adjacent to the sensing unit (151), and the (n-1)-th lens may be the lens closest to the last lens. The above n is an integer greater than or equal to 4, and may be, for example, in the range of 4 to 7 or in the range of 4 to 6. The ratio of the spherical lens to the aspherical lens in the n lenses may be any one of 3:1, 4:1, 3:2, 2:3, 3:3, 5:2, or 4:2.

[0050] In the optical system (100), the first lens (101) closest to the object may be made of glass. The glass material exhibits little change in expansion and contraction due to external temperature changes, and its surface is not easily scratched, thereby preventing surface damage. Accordingly, in the optical system (100), the first lens (101) on the object side may be a spherical lens, and the nth lens may be arranged as an aspherical lens. Since the nth lens in the optical system (100) is arranged as an aspherical lens, various aberrations of the light incident on the sensing unit (151) may be corrected.

[0051] Since at least two lenses closest to the object in the optical system (100) are arranged with glass material, the rate of contraction and expansion according to temperature change is smaller than that of plastic material, and thus, deterioration of optical characteristics according to temperature change within the lens barrel can be prevented. In addition, in the optical system (100), the lens (105) closest to the sensing unit (151) is arranged with glass mold material, and thus, the rate of contraction and expansion according to temperature change of the lens (105) is smaller than that of plastic material, and thus, deterioration of optical characteristics according to temperature change within the lens barrel can be prevented.

[0052] Each of the above lenses (101-105) may have an object-side surface and a sensor-side surface. The object-side surface and the sensor-side surface are opposite lens surfaces of the lenses. The optical system (100) may include an object-side spherical lens and a sensor-side spherical lens, and an object-side aspherical lens and a sensor-side aspherical lens. The number of aspherical lenses in the optical system may be smaller than the number of spherical lenses. Since the aspherical lens is arranged adjacent to the sensing unit (151), the aspherical lens can correct various aberrations of the optical system (100). The spherical lens and the aspherical lens may be made of glass. Among the lenses of the optical system (100), a lens having a maximum refractive index may be a spherical lens, and a lens having a maximum Abbe number may be an aspherical lens. Since the first lens (101) has a high refractive index and is positioned adjacent to the object, the first lens (101) can have a thin center thickness (CT1) and can provide an effective diameter on the sensor side to be smaller than the effective diameter on the object side.

[0053]

[0054] The first lens (101) has a lens surface having a maximum effective diameter within the optical system (100). A lens having a minimum effective diameter within the optical system (100) may be positioned between the aperture (ST) and the first lens (101). In addition, the effective diameters of the aspherical lenses may be smaller than the effective diameters of the spherical lenses. Here, the effective diameter of the lens is an average value of the effective diameters of the object-side surface and the sensor-side surface of each lens. By adjusting the effective diameters of each lens, the optical system (100) may be miniaturized. Each of the lenses (101-105) 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 an effective diameter in which the incident light is refracted to implement optical characteristics. The ineffective area may be arranged around the periphery of the effective area. The above-mentioned ineffective area may be an area where effective light is not incident on the plurality of lenses. In other words, the above-mentioned ineffective area may be an area unrelated to the above-mentioned optical characteristics. In addition, the end of the above-mentioned ineffective area may be an area fixed to a lens barrel (not shown) that accommodates the lens.

[0055]

[0056] Among the lenses of the optical system (100), the lens having the maximum center thickness may be a spherical lens. Among the lenses of the optical system (100), the lens having the maximum edge thickness may be a spherical lens. The average of the center thicknesses of the aspherical lenses may be smaller than the average of the center thicknesses of the spherical lenses arranged between the aspherical lenses. The aspherical lenses having thin thicknesses can reduce the TTL (Total Top Length) and refract the incident light into various paths. Here, the TTL is the distance from the center of the object-side surface of the first lens (101) to the image surface of the sensing unit (151) along the optical axis (OA). In the optical system (100), the TTL may be more than 10 times, for example, more than 10 times and less than 30 times, than the ImgH. The above ImgH is the distance from the center of the effective area of ​​the sensing unit (151) to the diagonal end or half of the maximum diagonal length of the effective area of ​​the sensing unit (151). The effective diameter of each lens within the optical system (100) may be greater than the diagonal length of the sensing unit (151).

[0057] The effective focal length of the optical system (100) can be shortened to 10 mm or less to realize a wide angle. The effective focal length (EFL) of the optical system (100) can be 10 mm or less, for example, in the range of 1 mm to 10 mm or 1 mm to 6 mm. Since the effective focal length is 10 mm or less and the field of view (FOV) is provided in excess of 100 degrees, the optical system (100) can be provided as a standard receiving optical system in a vehicle sensor system. For example, the receiving optical system and the sensor system according to the embodiment can be applied to a sensing device for an ADAS (Advanced Driving Assistance System) installed inside or outside a vehicle.

[0058] The optical system (100) above may have a condition of TTL / (2*ImgH) greater than 5, for example, a range of greater than 5 and less than 10. Accordingly, the central thickness of each lens along the optical axis (OA) can be increased and the size of the sensing unit (151) can be reduced, thereby providing a vehicle lens optical system. In addition, temperature compensation 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 -45°C to +120°C. That is, the lens must be configured so that the focus of the lens is maintained within the set range even when the lens expands or contracts due to temperature changes. The number of lenses having positive (+) refractive power or power in the optical system (100) may be equal to or greater than the number of lenses having negative (-) refractive power or power. The number of lenses having positive (+) refractive power or power may be 50% or more of the total number of lenses. Since this optical system (100) is a mixture of spherical lenses and aspherical lenses made of glass, various aberrations can be corrected, thereby preventing deterioration of optical performance.

[0059]

[0060] An optical system according to an embodiment of the invention will be described.

[0061] FIG. 1 is a side cross-sectional view of a receiving optical system of a lidar according to an embodiment, FIG. 2 is a table showing lens characteristics of the optical system of FIG. 1, FIG. 3 is a table showing aspherical coefficients of lenses in the receiving optical system of FIG. 1, FIG. 4 is data on distortion characteristics of the receiving optical system of FIG. 1, FIG. 5 is a graph showing data of diffraction MTF (Modulation Transfer Function) according to low temperature, room temperature, and high temperature in the receiving optical system of FIG. 1, FIG. 6 is a graph showing data on aberration characteristics of the optical system of FIG. 1 at low temperature, FIG. 7 is a graph showing data on aberration characteristics of the optical system of FIG. 1 at room temperature, and FIG. 8 is a graph showing data on aberration characteristics of the optical system of FIG. 1 at high temperature.

[0062] Referring to FIGS. 1 to 3, the optical system (100) may include first lenses (101) to fifth lenses (105) aligned with an optical axis (OA) from an object toward a sensor side. The first to fifth lenses (101-105) may be defined as a lens unit. The optical system (100) may include an optical filter (155), and the optical filter (155) may be arranged between the lenses. The optical filter (155) may be arranged between aspherical lenses. The optical filter (155) may be arranged between spherical lenses. The optical filter (155) may be arranged at a position closer to the spherical lens than to the aspherical lens. Light corresponding to information about an object passes through the first lens (101) to the third lens (103), the optical filter (155), and the fourth and fifth lenses (104, 105) and can be incident on the sensing unit (151).

[0063] The first lens (101) may have positive (+) or negative (-) refractive power on the optical axis (OA), and preferably, negative (-) refractive power. The first lens (101) may include a plastic material or a glass material, and may be, for example, a glass material. The first lens (101) made of a glass material can reduce changes in the center position and radius of curvature due to temperature changes in the surrounding environment, and can protect the incident side surface of the optical system (100). The first lens (101) is made of a glass material that is not injection molded.

[0064] On the optical axis (OA), the object-side first surface (S1) of the first lens (101) may have a convex shape, and the sensor-side second surface (S2) may have a concave shape. That is, the first lens (101) may have a convex meniscus shape toward the object. The first surface (S1) and the second surface (S2) may have spherical surfaces. The first lens (101) may have a convex meniscus shape toward the object. Alternatively, the first surface (S1) may have a concave shape, and the second surface (S2) may have a convex shape, on the optical axis (OA). Alternatively, the first lens (101) may have concave shapes on both sides.

[0065] Since the first surface (S1) of the first lens (101) is convex and the second surface (S2) is concave, the incident light can be refracted in a direction close to the optical axis (OA), the edge gap between the first and second lenses (101, 102) can be reduced, and the effective diameter of the second lens (102) can be reduced. The increase in the effective diameter of the second lens (102) can be suppressed by the shape of the lens surface of the first lens (101).

[0066] When the refractive index of the first lens (101) is Nd1, the condition of 1.7 < Nd1 or 1.75 < Nd1 < 2.1 can be satisfied. Since the refractive index (Nd1) of the first lens (101) is higher than that of other aspherical lenses, the radius of curvature of the first surface (S1) of the first lens (101) can be increased, and lens manufacturing can be easy. When the refractive index (Nd1) of the first lens (101) is lower than the condition, the lens surface must be formed to be sharply concave or convex in order to increase the refractive power of the second lens (102). In this case, lens manufacturing is not easy, the lens defect rate increases, and this may cause a decrease in yield.

[0067] The second lens (102) may be disposed between the first lens (101) and the third lens (103). The second lens (102) may have positive (+) or negative (-) refractive power on the optical axis (OA), for example, negative (-) refractive power. The second lens (102) may include a plastic or glass material, and may be provided as a glass material, for example. The second lens (102) may be injection molded. The object-side third surface (S3) of the second lens (102) on the optical axis (OA) may have a convex shape, and the sensor-side fourth surface (S4) may have a concave shape. That is, the second lens (102) may have a convex meniscus shape toward the object. The third and fourth surfaces (S3, S4) may be aspherical, and as shown in FIG. 4, are defined as L2S3 and L2S4, and may have a conic constant (K) and aspherical coefficients from the 4th to the 14th order (A to F). The third surface (S3) may have a critical point from the optical axis (OA) to the end or edge of the effective area. Since the third surface (S3) has a convex shape on the optical axis (OA) and has a critical point, the edge of the third surface (S3) may protrude further toward the object than the center of the third surface (S3). The fourth surface (S3) may be provided without a critical point from the optical axis (OA) to the edge. Alternatively, the third surface (S3) may be convex and the fourth surface (S4) may be concave on the optical axis (OA). In contrast, the second lens (102) may have a biconvex shape. The critical point may be a point where the sign of the slope value with respect to the optical axis (OA) and the direction perpendicular to the optical axis (OA) changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the slope value is 0. In addition, the critical point may be a point where the slope value of the tangent line passing through the lens surface increases and then decreases, or a point where the slope value decreases and then increases.

[0068] When the refractive index of the second lens (102) is Nd2, the condition of 1.8 > Nd2 or 1.55 < Nd2 < 1.8 can be satisfied. The refractive index (Nd2) of the second lens (102) is lower than the refractive indices of the first and third lenses (101, 103), and the difference in the radius of curvature of the third and fourth surfaces (S3, S4) can be provided as 30 mm or more. Accordingly, the second lens (102) can refract light incident through the first lens (101) to the entire area of ​​the third lens (103). Since the third surface (S3) of the second lens (102) has a critical point, the incident light can be refracted to the entire area of ​​the fourth surface (S4). In addition, since the sensor-side fourth surface (S4) of the second lens (102) is concave and has a small radius of curvature, an increase in the gap between the second and third lenses (102, 103) can be prevented.

[0069] The third lens (103) may have positive (+) or negative (-) refractive power on the optical axis (OA), and may be, for example, positive (+) refractive power. The third lens (103) may include a plastic or glass material, and may be, for example, a glass material. The third lens (103) is a glass material that is not injection molded. The object-side fifth surface (S5) of the third lens (103) on the optical axis (OA) may have a concave shape, and the sensor-side sixth surface (S6) may have a convex shape. That is, the third lens (103) may have a convex meniscus shape toward the sensing unit (151) or the image sensor on the optical axis (OA). At least one or both of the fifth surface (S5) and the sixth surface (S6) of the third lens (103) may be spherical. At least one or both of the fifth surface (S5) and the sixth surface (S6) may be provided without a critical point from the optical axis (OA) to the end of the effective area. Alternatively, the third lens (103) may have a meniscus shape that is convex toward the object. Alternatively, the third lens (103) may have a concave or convex shape on both sides on the optical axis. When the refractive index of the third lens (103) is Nd3, the condition of Nd2 < Nd3 may be satisfied. When the Abbe number of the third lens (103) is Vd3, the condition of Vd3 < Vd2 may be satisfied. Here, Vd2 is the Abbe number of the second lens (102).

[0070]

[0071] The optical system (100) may include an aperture stop (ST). The aperture (ST) may adjust the amount of light incident on the optical system (100). The aperture (ST) may be arranged on the periphery between two adjacent lenses. The aperture (ST) may be arranged on the periphery of the sensor-side surface (S6) of the third lens (103). The aperture (ST) may be arranged on the periphery between the third lens (103) and the fourth lens (104). The aperture (ST) may be arranged on the periphery between the sensor-side sixth surface (S6) of the third lens (103) and the object-side seventh surface (S7) of the fourth lens (104). The aperture (ST) may be arranged on the periphery of the object-side surface or the sensor-side surface of the optical filter (155). The above aperture (ST) may be arranged on the periphery between the third lens (133) and the optical filter (155). The aperture (ST) may be arranged on the periphery of the object-side surface (FS1) of the optical filter (155). The lens surface on which the aperture (ST) is arranged, i.e., the sixth surface (S6), may more efficiently control and guide the amount of light of the optical system (100). As in the embodiment, the aperture (ST) may be arranged on the sensor-side surface of the third lens (103). Alternatively, the aperture (ST) may be arranged on the periphery of the object-side surface or the sensor-side surface of the second lens (102). Alternatively, at least one lens selected from the plurality of lenses, for example, the object-side surface or the sensor-side surface of the third lens (103), may function as an aperture.

[0072] The focal length of the third lens (103) is F3, and the condition: F3 > 0 is satisfied. Since the third lens (103) arranged on the object side of the aperture (ST) has positive refractive power, the third lens (103) can refract incident light in the direction of the optical axis, and can suppress an increase in the effective diameter of the sensor-side or rear-side lenses of the third lens (103). Accordingly, a decrease in the yield by weight of the optical system can be prevented by the third lens (103), and production efficiency can be improved. Here, the focal lengths of the fourth and fifth lenses (104, 105) arranged on the sensor side of the aperture (ST) can have positive values, and the optical system (100) can reduce the TTL within the field of view range.

[0073] Since the sensor-side sixth surface (S6) of the third lens (103) has a convex shape and a smaller radius of curvature than the radius of curvature of the fifth surface (S5), the center distance between the third lens (103) and the aperture (ST) may be smaller than the center distance between the aperture (ST) and the fourth lens (104). The effective diameter of the optical filter (155) may be larger than the effective diameter of the third lens (103). The optical filter (155) transmits a laser beam reflected by a subject after being emitted from the transmission optical system of the lidar device, and blocks beams of other wavelengths. The optical filter (155) may be positioned closer to the third lens (103) than to the fourth lens (104) in order to improve light blocking and transmission efficiency.

[0074] The fourth lens (104) may have positive (+) or negative (-) refractive power on the optical axis (OA), for example, positive (+) refractive power. The fourth lens (104) may include a plastic or glass material, and may be provided as a glass material. The fourth lens (104) may not be injection molded. The object-side seventh surface (S7) of the fourth lens (104) on the optical axis (OA) may have a convex shape, and the sensor-side eighth surface (S8) may have a convex shape. The fourth lens (104) may have a convex shape on both sides. At least one or both of the seventh surface (S7) and the eighth surface (S8) may be spherical. The seventh and eighth surfaces (S7, S8) of the fourth lens (104) may be provided without a critical point from the optical axis (OA) to the end of the effective area. Alternatively, the fourth lens (104) may have a convex meniscus shape toward the object. Alternatively, the fourth lens (104) may have a convex meniscus shape toward the image sensor. Alternatively, the fourth lens (104) may have a concave shape on both sides along the optical axis (OA).

[0075]

[0076] The fifth lens (105) may have positive (+) or negative (-) refractive power on the optical axis (OA), for example, positive (+) refractive power. The fifth lens (105) may include a plastic or glass material, and may be provided as a glass material. The fifth lens (105) may be injection molded. On the optical axis (OA), the ninth surface (S9) on the object side of the fifth lens (105) may have a convex shape, and the tenth surface (S10) on the sensor side may have a convex shape. The fifth lens (105) may have a convex shape on both sides on the optical axis (OA). Alternatively, the fifth lens (105) may have a convex meniscus shape toward the object or the image sensor. Alternatively, on the optical axis (OA), the fifth lens (105) may have a concave shape on both sides. At least one or both of the ninth surface (S9) and the tenth surface (S10) may be aspherical. The aspherical coefficients of the ninth and tenth surfaces (S9, S10) may be provided as L5S9 and L5S10 of FIG. 3. The ninth surface (S9) of the fifth lens (105) may be provided without a critical point from the optical axis to the end of the effective area. The tenth surface (S10) may have at least one critical point from the optical axis to the end or edge of the effective area, and the critical point may be arranged closer to the edge than the center of the tenth surface (S10). The fifth lens (105) has an aspherical surface and may guide light incident through the fourth lens (104), which is a spherical lens, to the sensing unit (151).

[0077] When the refractive index of the fifth lens (105) is Nd5, the condition of Nd5 < Nd3 can be satisfied. When the Abbe number of the fifth lens (105) is Vd5, the condition of Vd3 < Vd5 can be satisfied. When the refractive index of the fourth lens (104) is Nd4, the condition: 0.8 < Nd4 / Nd5 < 1.2 can be satisfied. The fifth lens (105) may be an aspherical lens closest to the sensing unit (151). By means of the lens surface having an aspherical surface, aberrations such as spherical aberration and chromatic aberration can be improved, and the influence on the resolution can be controlled. By means of the aspherical surface of the lens surface adjacent to the sensing unit (151), optical performance can be improved, and for example, aberration characteristics can be improved and resolution deterioration can be prevented. At least one or both of the object-side surface and the sensor-side surface of the second and fifth lenses (102, 105) may have a free surface, i.e., a non-rotationally symmetrical surface.

[0078]

[0079] The optical system (100) or sensor system may include a sensing unit (151). The sensing unit (151) may detect light that has sequentially passed through the lenses. The sensing unit (151) may detect light and convert it into an electrical signal. The sensing unit (151) may obtain various information about the subject. The sensing unit (151) may detect time delay or phase difference information from the incident light, and based on this, may obtain distance information to the subject, position information of the subject, depth image of the subject, etc. To this end, the sensing unit (151) may include an image sensor or a photon detector, and may include, for example, a sensor such as a synchronization photo detector (SPD), a single photon avalanche diode (SPAD), or an avalanche photo-diode (APD). As another example, the sensing unit (151) may include an element capable of detecting incident light, such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), as an image sensor. As another example, the sensing unit may include a TDC (Time to digital converter). Here, the effective length of the sensing unit (151) is the maximum length in the diagonal direction orthogonal to the optical axis (OA), and here, the number of lenses having an effective diameter larger than the effective length of the sensing unit (151) is 4 to 6, and there may be no number of lenses having an effective diameter smaller than the effective length of the sensing unit (151).

[0080] The first and third lenses (101, 103) may be made of the same material or have the same refractive index. The first and second lenses (101, 102) may have positive power, and the third to fifth lenses (103-105) may have positive power. When the lenses having negative refractive power or power are the first lens group and the lenses having positive refractive power or power are the second lens group, the aperture (ST) and the optical filter (155) may be arranged within the second lens group. The aperture (ST) and the optical filter (155) may be arranged between the spherical lens surfaces of the second lens group.

[0081] The fifth lens (105) may have a lower refractive index than the refractive indices of the first to third lenses (101, 102, 103) and may have an Abbe number higher than the Abbe numbers of the first and third lenses (101, 103). The Abbe number of the fifth lens (105) may be lower than the Abbe number of the second lens (102). The effective diameter of the fifth lens (105) may be smaller than the effective diameter of the fourth lens (104). The effective diameter of the first lens (101) may be the largest among the lenses. The effective diameters of the second to fourth lenses (102, 103, 104) may be larger as the lens is closer to the sensing unit (151). The effective diameter of the first lens (101) may be larger than the effective diameter of the fifth lens (105) closest to the sensing unit (151). Accordingly, the brightness of the optical system (100) can be controlled. By controlling the effective diameter of each of the lenses (101-105), the optical system (100) can control the incident light to compensate for the deterioration of the resolution and optical characteristics due to temperature changes, improve the chromatic aberration control characteristics, and improve the vignetting characteristics of the optical system (100).

[0082]

[0083] At least two lenses may be arranged between the optical filter (155) and the sensing unit (151). The fourth and fifth lenses (104, 105) may be arranged between the optical filter (155) and the sensing unit (151). A spherical lens and an aspherical lens may be arranged between the optical filter (155) and the sensing unit (151). The optical filter (155) may be arranged between the sensor-side sixth surface (S6) of the third lens (103) and the object-side seventh surface (S7) of the fourth lens (104). The optical filter (155) may be a band pass filter that passes a laser beam in the range of 890 nm to 960 nm or 940 nm ± 10 nm. As another example, the optical filter (155) may transmit a range of 1550 nm ± 10 nm and block other wavelengths. The optical filter (155) above can pass 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. The optical filter (155) above can be a bandpass filter.

[0084] The cover glass (153) is placed between the last lens and the sensing unit (151), and protects the upper portion of the sensing unit (151) and can prevent the reliability of the sensing unit (151) from being deteriorated. The cover glass (153) can be placed between the fifth lens (105) and the sensing unit (151). The cover glass (153) can be removed. The cover glass (153) can be a protective glass.

[0085] The optical filter (155) can perform an operation of passing light of a specific wavelength and blocking the remaining light. The optical filter (155) can actively perform the filtering operation. To this end, the optical filter (155) can include an active device that, in response to an external control signal, passes only light having a specific center wavelength and blocks light of other wavelengths. The control signal provided to the optical filter (155) can include information about the center wavelength of the light to pass through the active device, wherein the center wavelength can correspond to the center wavelength of the light emitted from the transmission optical system. Consequently, the control signal provided to the optical filter (155) is a control signal that matches the center wavelength of the light emitted from the transmission optical system and the center wavelength of the light to pass through the active device of the optical filter (155). Due to the active device included in the optical filter (155), the optical filter (155) can selectively pass only desired light and block other noise light including natural light. Therefore, the signal-to-noise ratio (S / N) of the lidar system can be increased. As an example of the active device, the optical filter may include a tunable band-pass filter. The tunable band-pass filter may operate in a liquid crystal or acousto-optic manner.

[0086]

[0087] The third lens (103) is disposed on the object side of the optical filter (155), has a refractive index greater than that of the second lens (102), and may have a center thickness (CT3) greater than that of the first lens (101). The fourth lens (104) is disposed on the sensor side of the optical filter (155), has a refractive index less than that of the fourth lens (104), and may have a center thickness (CT4) greater than that of the first lens (101). A center distance (CG3) between the third lens (103) and the fourth lens (104) may be greater than the thickness of the optical filter (155). The center distance (CG3) between the third lens (103) and the fourth lens (104) may be the largest among the center distances between adjacent two lenses within the optical system (100). The optical filter (155) may be placed between two lenses among the first to fifth lenses (101-105) whose central thickness is thicker than that of the other lenses.

[0088]

[0089] When the radius of curvature is described as an absolute value, the lens surface having the minimum radius of curvature with respect to the optical axis (OA) within the optical system (100) may be the fourth surface (S4) of the second lens (102) or the ninth surface (S9) of the fifth lens (105), for example, the fourth surface (S4). Accordingly, the center distance between the first lens (101) and the second lens (102) may be increased, and the center distance between the fourth lens (104) and the fifth lens (105) may be decreased. The lens surface having the maximum radius of curvature within the optical system (100) may be the tenth surface (S10) of the fifth lens (105) among the spherical surfaces. When the radius of curvature of the lenses is adjusted, lens ghosting can be reduced by preventing random reflection between adjacent lens surfaces, and interference (MPI: Multi-path interference) due to lens ghosting can also be prevented. The tenth surface (S10) of the fifth lens (105) has a radius of curvature of 200 mm or more, and may be 20 times or more the radius of curvature of the ninth surface (S9).

[0090] In the optical system (100) of the embodiment, the sum of the refractive indices of the lenses may be greater than 5, for example, 8.0 or more, and preferably, in the range of 8.0 to 12.0, and the average of the refractive indices may be in the range of 1.70 to 1.80. The sum of the Abbe numbers of each of the lenses may be 180 or less, for example, in the range of 120 to 180, and the average of the Abbe numbers may be 47 or less, for example, in the range of 23 to 47. By controlling the glass material and refractive indices of the lenses in the optical system (100), it is possible to prevent degradation of optical performance for temperature changes from -45 to 120 degrees and to optimize thermal compensation. In addition, by controlling the Abbe numbers of the lenses, it is possible to minimize the deviation of the spot size of incident light, i.e., to minimize the spot diagram size.

[0091] The sum of the central thicknesses of all lenses within the optical system (100) may be 18 mm or more, for example, in the range of 18 mm to 30 mm, and the average of the central thicknesses may be 6 mm or less, for example, in the range of 4 mm to 6 mm. The sum of the central spacings between the lenses on the optical axis (OA) may be 10 mm or more, for example, in the range of 10 mm to 20 mm, and may be less than the sum of the central thicknesses of the lenses. In addition, the average value of the effective diameter of each lens surface of the optical system (100) may be provided as 20 mm or less, for example, in the range of 9 mm to 20 mm. By controlling the thickness of each lens within the optical system (100), it is possible to prevent degradation of optical performance for temperature changes from -45 to 120 degrees and to optimize thermal compensation.

[0092] In the receiving optical system according to an embodiment of the invention, the angle of view may be greater than 100 degrees, for example, in the range of 118 degrees or more to 138 degrees, preferably, in the range of 128 degrees ± 10 degrees. The angle of view may be a horizontal angle of view. The F number of the optical system or the camera module may be 1.2 or less, for example, in the range of 0.7 to 1.2 or in the range of 0.7 to 0.9. Therefore, the optical system (100) may provide a bright optical system. In addition, the relative illumination (RI) may be 85% or more, for example, 88% or more. The size (RMS) of the spot received in the receiving optical system for Lidar may be 15 μm or less, for example, 12 μm or less. That is, the condition: spot size < pixel size may be satisfied. The diagonal length of the sensing unit (151) may be greater than 2 mm and less than 20 mm, for example, 6.34 mm ± 0.5 mm, and may be greater than the sensor height in the vertical direction. The invention can provide a vehicle lidar device that suppresses changes in the focal imaging position due to temperature changes by stacking glass lenses and corrects various aberrations by providing an aspherical lens.

[0093]

[0094] Since the embodiment is a receiving optical system applied to a lidar device, the first lens (101) 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 more effectively prevent scratches caused by foreign substances or when placed inside a vehicle, a glass lens may be used as the first lens (101), and the object-side surface of the first lens (101) may have a convex shape to prevent 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 may be used for an advanced driver assistance system (ADAS). The optical system (100) according to the embodiment may further include a reflective member (not shown) for changing the path of light. The reflective member may be placed on the incident side of the first lens (101) and may be implemented as a prism that reflects the incident light toward the lenses. Hereinafter, the optical system according to the embodiment will be described in detail.

[0095]

[0096] As shown in FIGS. 1 and 2, the center thickness of the first to fifth lenses (101 to 105) is represented by CT1 to CT5, the edge thickness at the end of the effective area of ​​each lens is represented by ET1 to ET5, and the center gap between two adjacent lenses is represented by CG1 to CG4. The first to fifth lenses (101 to 105) can satisfy the following conditions.

[0097] Condition 1: CT1 < CT3 Condition 2: CT2 < CT5 < CT4

[0098] Condition 3: (CT4-CT5) < (CT3-CT2) Condition 4: ET1 < ET3 < ET2

[0099] Condition 5: ET5 < ET4 < ET3 < CT5

[0100] At least one or both of the center thicknesses (CT3, CT4) of the third and fourth lenses (103, 104) are the largest among the lenses, and the center thickness (CT1) of the first lens (101) is the smallest among the lenses. The maximum center thickness may be more than 1.5 times and less than or equal to 3 times the minimum center thickness, and the difference between the maximum center thickness and the minimum center thickness may be more than 2 mm and less than or equal to 4 mm. That is, even if the first lens made of a spherical material provides a thin center thickness, the optical performance may not be degraded, and the thickness of the sensor system may be provided slimly. By adjusting the thickness of these glass lenses, thermal compensation can be performed for temperatures that change from low to high temperatures.

[0101]

[0102] Regarding the center spacings (CG1-CG4) between adjacent lenses, the center spacing (CG3) between the third lens (103) and the fourth lens (104) is the largest among the center spacings and is larger than the center spacing (CG1) between the first and second lenses (101, 102). The center spacing (CG4) between the fourth and fifth lenses (104, 105) may be the smallest among the center spacings. Here, the difference between the maximum center spacing and the minimum center spacing may be 2 mm or more, for example, in the range of 2 mm to 4 mm. In addition, since the maximum center spacing between the lenses is provided to be smaller than the maximum center thickness of each lens, the optical system (100) can control the optical path between the spherical lens and the aspherical lens.

[0103] In terms of the effective diameter, the lens having the maximum effective diameter may be the first lens (101). The lens surface having the maximum effective diameter is the first surface (S1). The lens having the minimum effective diameter may be the second lens (102). The lens surface having the minimum effective diameter may be either the fourth surface (S4) of the second lens (102) or the tenth surface (S10) of the fifth lens (105), and may be 0.6 times or less than the first surface (S1). The effective diameter of each of the first to fifth lenses (101-105) may be greater than the diagonal length of the effective area of ​​the sensing unit (151).

[0104]

[0105] FIG. 2 is an example of lens data of the optical system of the embodiment of FIG. 1. As shown in FIG. 2, the radius of curvature of the optical axis (OA) of the first to fifth lenses (101, 102, 103, 104, and 105), the center thickness (CT) of the lenses, the center spacing (CG) between the lenses, the refractive index at the d-line, the Abbe number, the effective diameter, and the focal length can be set. As shown in FIG. 3, the lens surfaces of the second and fifth lenses (102, and 105) of the embodiment may include an aspherical surface having a 14th-order aspherical surface coefficient. For example, the object-side surface (L2S1) and the sensor-side surface (L2S2) of the second lens (102) and the object-side surface (L5S9) and the sensor-side surface (L5S10) of the fifth lens (105) 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).

[0106]

[0107] The focal lengths (F1, F2) of the first and second lenses (101, 102) may have negative refractive power, and the focal lengths (F3, F4, F5) of the third, fourth, and fifth lenses (103, 104, 105) may have positive refractive power. The second lens (102) and the third lens (103), which are arranged adjacently, may satisfy the following conditions.

[0108] Condition 1: Refractive index of lens with negative refractive power < refractive index of lens with positive refractive power

[0109] Here, among the lenses, the second lens (102) has a negative refractive power and the third lens (103) has a positive refractive power, so that according to the condition 1, the refractive index of the third lens (103) is greater than the refractive index of the second lens (102), so that the dispersion value of light can be adjusted. The optical system generates chromatic aberration, and the chromatic aberration is corrected using the second and fifth lenses (102, 105).

[0110] Since the first to fifth lenses (101-105) of the invention are made of glass, the difference in characteristics between the lenses due to temperature changes can be eliminated. That is, the lenses repeatedly contract and expand as the temperature changes from low to high. Since the amount of change in lens characteristics due to temperature changes is the same for lenses of the same material, it is effective to correct chromatic aberration between lenses of the same material even when the temperature changes. For example, as shown in Table 1, it can be seen that there is almost no change in optical characteristics when the temperature of the lens barrel or optical system changes from -45 degrees (low temperature), 22 degrees (room temperature), and 90 degrees (high temperature). Table 1 compares changes in optical characteristics such as EFL, BFL, F number (F#), TTL, and field of view (FOV) at room temperature, low temperature, and high temperature in an optical system according to an embodiment, and it can be seen that the change rate of optical characteristics at low temperature is 5% or less, for example, 3% or less or 2% or less, based on room temperature, and the change rate of optical characteristics at high temperature is 5% or less, for example, 3% or less or 2% or less, based on room temperature.

[0111] Low temperature Room temperature High temperature Low temperature / Room temperature (%) High temperature / Room temperature (%) EFL (mm) 3.3509 3.3508 3.3511100.00% 100.01% BFL (mm) 6.16396.16736.182399.94% 100.24% F# 0.80090.80090.8009 100.00% 100.00% TTL (mm) 46.852846.900046.947899.90% 100.10% FOV (˚) 128.9782128.9710128.9398100.01% 99.98%

[0112] In Table 1, EFL is the effective focal length of the optical system, BFL is the optical axis distance from the last lens, i.e., the fifth lens (105), to the surface of the sensing unit (151), i.e., the image sensor, F# is the F number of the optical system, TTL is the optical axis distance from the center of the object-side surface of the first lens (101) to the surface of the sensing unit (151), i.e., the upper surface of the image sensor, and FOV is the angle of view of the optical system. As shown in Table 1, it can be seen that the change in optical characteristics according to the temperature change from low temperature to high temperature, for example, the change rate of the effective focal length (EFL), TTL, BFL, F number, and angle of view (FOV), is 10% or less, i.e., 5% or less, for example, in the range of 0% to 5%. This can prevent the deterioration of the reliability of the optical characteristics by designing to enable temperature compensation for the aspherical lens even when at least one or two or more aspherical lenses are used. The optical system of the embodiment disclosed above can effectively control aberration characteristics such as chromatic aberration and distortion aberration, and can have good optical performance even in the center and periphery of the field of view (FOV).

[0113]

[0114] When comparing the focal lengths in absolute values, the focal length of the third lens (103) is the largest among the lenses and may be 20 mm or more, for example, in the range of 20 mm to 45 mm. In addition, the focal lengths of the first and second lenses (101, 102) may be 30 mm or less, for example, in the range of 5 mm to 30 mm. The focal lengths of the fourth and fifth lenses (104, 105) may be 30 mm or less, for example, in the range of 5 mm to 30 mm. Accordingly, the optical system may have improved MTF characteristics, aberration control characteristics, resolution characteristics, etc. in the set field of view range, and may have good optical performance in the periphery of the field of view.

[0115]

[0116] In addition, the optical system (100) according to the embodiment may have good optical performance according to temperature change in a temperature range from low temperature (-45 degrees) to high temperature (120 degrees) and may have set distortion characteristics. For example, the optical system (100) may be based on any one of the following mapping functions of a wide-angle lens. In detail, the distance (mm) from the surface center (0 Field) of the image sensor, which is the sensing unit (151), to 1 field is defined as ImgH, that is, ImgH is half of the maximum diagonal length (mm) of the effective area of ​​the image sensor. When the half-field angle (HFOV) is θ and the total focal length (mm) of the optical system (100) is defined as F, the mapping function of the wide-angle or fisheye optical system may be defined as follows. Equidistance mapping can be defined as ImgH = F*θ, and Equal Area (Equisolid angle) mapping can be defined as ImgH = 2*F*sin(θ / 2). Also, Orthographic mapping can be defined as ImgH = F*sinθ, and Stereographic mapping can be defined as ImgH = 2*F*tan(θ / 2). Here, * indicates multiplication.

[0117] Looking at the transmission optical system (110) of FIGS. 11 and 13, the diffuser (119) of the transmission optical system (110) has a micro lens array, and the optical path of light passing through the micro lens array causes a change in the Field of Illumination (FOI) in the on-axis direction separate from the direction in which the light travels. In the comparative example, it can be seen that the FOI changes in the off-axis direction after passing through the one-dimensional micro lens array. Here, looking at the optical path after passing through the diffuser (119), the comparative example has an optical path of F*θ, and the embodiment has an optical path of F*sinθ. That is, if the optical path on the spherical coordinate is projected onto a plane and induced to be imaged on the SPAD, it can be seen that the condition: y=F*sinθ is satisfied.

[0118]

[0119] As shown in FIG. 4, the optical system (100) may have distortion characteristics that are set compared to the design criteria (comparative example) as it goes from the 0 degree field of view to the maximum half field of view (HFOV). For example, it can be seen that the embodiment of the optical system (100) has an increasing resolution as it goes from the 0 degree field of view to the maximum value of the half field of view (HFOV) and the maximum value of the sensor height (i.e., ImgH) when imaged on the SPAD of the receiver. It may have a distortion characteristic that satisfies compared to other examples of mapping such as Stereographic, equidistance, rectilinear, and Equisolid. In detail, the embodiment may satisfy the distortion characteristics compared to the other example 1 above.

[0120] In addition, the optical system (100) can have a distortion characteristic set compared to other examples as it goes from a 0 degree angle of view to a maximum value of the half field of view (HFOV), thereby providing an optical system that satisfies the orthographic projection type. Here, the ratio for the distortion characteristic is for the value of ImgH at a specific half field of view position, and can mean something calculated by the formula: ((Other example - embodiment) / embodiment * 100). Accordingly, the optical system according to the embodiment can prevent the optical characteristics from changing according to temperature change in a temperature range from a low temperature (-45 degrees) to a high temperature (120 degrees) based on the Equal Area mapping method, and can have improved optical performance in various temperature ranges.

[0121] Fig. 5 is a graph showing the diffraction MTF (Modulation Transfer Function) at low, room, and high temperatures in the optical system of Fig. 1, and is a graph showing the luminance ratio (modulation) according to the spatial frequency. As shown in Fig. 5, in an embodiment of the invention, the deviation of the MTF at low or high temperature with respect to room temperature may be less than 10%, that is, 7% or less. Here, each MTF curve was measured from 0.000 mm to 3.024 mm in units of 0.302 mm.

[0122] FIGS. 6 to 8 are graphs showing aberration characteristics at low temperatures, room temperatures, and high temperatures in the optical system of FIG. 1. In the aberration graphs of FIGS. 6 to 8, spherical aberration (longitudinal spherical aberration), astigmatic field curves, and distortion are measured from left to right, and the X-axis can represent the focal length (mm) and the degree of distortion (%), and the Y-axis can represent the image height (height). In addition, the graph for spherical aberration is a graph for light in the wavelength bands of about 930 nm, about 940 nm, and about 950 nm, and the graphs for astigmatic aberration and distortion aberration are graphs for light in the wavelength band of about 940 nm. In the aberration diagrams of FIGS. 6 to 8, the closer each curve at low temperatures, room temperatures, and high temperatures is to the Y-axis, the better the aberration correction function can be interpreted. That is, the optical system (100) according to the embodiment can have improved resolution and good optical performance at the center and periphery of the field of view (FOV). Here, the low temperature is -20 degrees or lower, for example, in the range of -20 to -50 degrees, the room temperature is in the range of 22 degrees ± 5 degrees or in the range of 18 degrees to 27 degrees, and the high temperature can be 85 degrees or higher, for example, in the range of 85 degrees to 120 degrees. Accordingly, it can be seen from the graphs of FIGS. 6 to 8 that the decrease in luminance ratio (modulation) from low temperature to high temperature is less than 10%, for example, 5% or lower, or is almost unchanged.

[0123]

[0124] According to an embodiment of the invention, a receiving optical system can prevent degradation of optical performance from low to high temperatures by considering the characteristics of a vehicle optical system. For example, after designing a lens at room temperature, the value of the dn / dt, which is a temperature-dependent refractive index change coefficient, is assembled by 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 ±6.5㎛ or less. To this end, the first, third, and fourth lenses (101, 103, and 104) are made of a spherical glass material, and the second and fifth lenses (102, 105) are made of an aspherical glass material. The existing filter is arranged between the sensing unit and the last lens. In an embodiment of the invention, the optical filter (155) can be arranged close to the aperture (ST), that is, between the aperture (ST) and the fourth lens (104). Accordingly, the incident angle of light incident on the optical filter (155) can be minimized. That is, the incident angle of the main beam incident on the optical filter (155) can be less than 25 degrees at most.

[0125] It is possible to overcome the material limitation that the filter transmittance region is T-shifted depending on the incident angle incident on the optical filter (155). For example, when the existing filter is arranged between the sensing unit and the last lens, the incident angle of the main beam incident on the filter is about 45 degrees, but the optical filter (155) of the invention is arranged around the aperture (ST), so that the incident angle of the main beam can be less than 25 degrees. When considering the transmittance curve when the main beam is at an incident angle of 0 degrees on the optical filter (155) and the transmittance curves when the main beam is at an incident angle of 20 degrees and 40 degrees, there is an effect that the filter region can be utilized more widely from an incident angle of 0 degrees to an angle of less than 25 degrees at most.

[0126] Fig. 9 is a graph showing a curve of transmittance (%) when the incident angle of the main beam incident on the filter of the invention is 0 degrees, 20 degrees, and 40 degrees. The incident angle of the main beam on the incident surface of the optical filter (155) is inspected using AOI (Automated optical inspection) equipment, and it can be seen that the incident angle in different directions (±Y direction, ±X direction) from the main beam (chief ray) incident on the filter from 0 field to 1.05 field is less than 25 degrees, for example, from 0 degree to a maximum of 24.8 degrees. Accordingly, the problem of the incident angle of the main beam shifting at low and high temperatures compared to room temperature can be minimized.

[0127] The optical system (100) according to the embodiment disclosed above can satisfy at least one or two or more of the mathematical equations described below. Accordingly, the optical system (100) according to the embodiment can have improved optical characteristics. For example, when the optical system (100) satisfies at least one mathematical equation, the optical system (100) can effectively control aberration characteristics such as chromatic aberration and distortion aberration, and can have good optical performance even in the center and periphery of the field of view (FOV). In addition, the optical system (100) can have improved resolution. In addition, the thickness of the lens on the optical axis (OA) described in the mathematical equations and the spacing between adjacent lenses on the optical axis (OA) may refer to the embodiment disclosed above.

[0128] [Mathematical Formula 1] 0 < CT1 / CT2 < 2

[0129] CT1 is the central thickness of the first lens (101), and CT2 is the central thickness of the second lens (102). By setting the central thickness (CT1) of the first lens (101) and the central thickness (CT2) of the second lens (102) in mathematical expression 1, it is possible to prevent a decrease in the rigidity of the first lens (101) and control factors affecting aberration. Preferably, mathematical expression 1 can satisfy 0 < CT1 / CT2 < 1.

[0130] [Mathematical Formula 2] 4 < CA11 / CT1 < 12

[0131] CA11 is the effective diameter of the object-side surface (S1) of the first lens (101). In mathematical expression 2, the center thickness (CT1) of the first lens (101) and the effective diameter (CA11) of the object-side surface (S1) of the first lens (101) can be set, and when these are satisfied, the strength and optical characteristics of the glass lens can be prevented from being deteriorated. The amount of incident light can be increased by the effective diameter of the object-side surface (S1) of the first lens (101). If it is lower than the range of mathematical expression 1, the lens may be damaged or the incident efficiency may be reduced, and if it is larger than the range, the TTL may increase and the weight of the optical system may become heavier. Preferably, mathematical expression 2 can satisfy 6 < CA11 / CT1 < 10.

[0132] [Mathematical Formula 3] 0 < CT5 / CT4 < 3

[0133] CT4 is the central thickness of the fourth lens (104), and CT5 is the central thickness of the fifth lens (105). In mathematical expression 3, the central thickness (CT5) of the fifth lens (105) and the central thickness (CT4) of the fourth lens (104) can be set, thereby optimizing thermal compensation according to temperature changes from low to high temperatures and preventing degradation of optical performance. Preferably, mathematical expression 3 can satisfy 0.5 < CT5 / CT4 < 1.2.

[0134] [Equation 3-1] 0 < CT5 / CT3 < 2

[0135] CT3 is the center thickness of the third lens (103). By setting the center thicknesses (CT3, CT5) of the third and fifth lenses (103, 105) in Mathematical Expression 3-1, light refracted from the object-side lenses can be guided to the sensing unit (151). Preferably, Mathematical Expression 3-1 can satisfy 0.5 < CT5 / CT3 < 1. Accordingly, the fifth lens (105) closest to the sensing unit (151) can thicken the center thickness (CT5) and refract light refracted through the object-side lenses to the entire area of ​​the sensing unit (151) without significantly increasing the effective diameter.

[0136] [Mathematical Formula 4] 0 < CT5 / (CT1+CT2) < 3

[0137] In mathematical expression 4, the central thickness (CT5) of the fifth lens (105) can be set to be greater than the sum of the central thicknesses (CT1, CT2) of the first and second lenses (101, 102). The fifth lens (105) can refract light refracted from the object-side lenses to the entire area of ​​the sensing unit (151). Preferably, mathematical expression 4 can satisfy 0.5 < CT5 / (CT1+CT2) < 1. Accordingly, the central thickness (CT5) of the fifth lens (105) closest to the sensing unit (151) can be thickened, and the effective diameter may not increase significantly.

[0138] [Mathematical Formula 5] 1 < CG3 / CT1 < 3

[0139] CG3 is the center spacing between the third and fourth lenses (103, 104). In mathematical expression 5, the center spacing (CG3) between the third and fourth lenses (103, 104) can be set to be greater than the center thickness (CT1) of the first lens (101). Accordingly, the minimum spacing between the convex sensor-side surface of the third lens (103) and the convex object-side surface of the fourth lens (104) can be provided to be greater than the thickness of the optical filter (155). Preferably, 1.2 < CC3 / CT1 < 2.2 can be satisfied.

[0140]

[0141] [Equation 6] 1 < CG1 / CG4 < 5

[0142] CG1 is the center spacing between the first and second lenses (101, 102), and CG4 is the center spacing between the fourth and fifth lenses (104, 105). In Equation 6, by setting the center spacing (CG1) between the first and second lenses (101, 102) to be greater than the center spacing (CG4) of the fourth and fifth lenses (104, 105), the center spacings between adjacent spherical lenses (101, 104) and aspherical lenses (102, 105) can be set. Preferably, 2 < CG1 / CG4 < 4 can be satisfied.

[0143] [Equation 6-1] 0 < CG4 / CG2 < 1

[0144] In mathematical expression 6-1, the center spacing (CG2) between the second and third lenses (102, 103) is set to be larger than the center spacing (CG4) between the fourth and fifth lenses (104, 105), so that the center spacing between the two object-side lenses (102, 103) of the aperture (ST) is set to be larger than the center spacing between the two sensor-side lenses (104, 105) of the aperture (ST), thereby controlling the light paths on the incident and exit sides of the aperture (ST). Preferably, 0.1 < CG4 / CG2 < 0.5 can be satisfied.

[0145]

[0146] [Equation 7] 2 < CG3 / OFt < 15

[0147] OFt is the thickness of the optical filter (155). In mathematical expression 7, by making the center spacing (CG3) between the third and fourth lenses (103, 104) larger than the thickness of the optical filter (155), a space in which the optical filter (155) can be installed can be secured in the area between the third and fourth lenses (103, 104). Preferably, 5 < CG3 / OFt < 12 can be satisfied.

[0148] [Equation 8] 0 < CG3 / (CT1+CG1+CT2) < 1

[0149] In mathematical expression 8, the center distance (CG3) between the third and fourth lenses (103, 104) can be set to be smaller than the optical axis distance between the object-side surface of the first lens (101) and the sensor-side surface of the second lens (102). Accordingly, the object-side surface of the first lens (101) can be set to the maximum effective diameter, and the second lens (102) can be set to the minimum effective diameter. Preferably, 0.2 < CG3 / (CT1+CG1+CT2) < 0.8 can be satisfied.

[0150] [Equation 9] 1 < TTL / DF2 < 4

[0151] DF2 is the optical axis distance from the upper surface of the sensing unit (151) to the optical filter (151). In mathematical expression 8, the total optical axis length (TTL) and the optical axis distance between the optical filter (151) and the sensing unit (151) can be set. Accordingly, the position of the optical filter (151) can be positioned closer to the object than the last lens. Preferably, 1.5 < TTL / DF2 < 3 can be satisfied.

[0152]

[0153] [Equation 10] 1.70 < Nd1

[0154] Nd1 is the refractive index at the d-line of the first lens (101). In mathematical expression 10, by setting the refractive index of the first lens (101) high, the factor affecting the reduction of the third-order aberration (Seidel aberration) of the optical system can be adjusted, and the aberration that may occur as the TTL becomes somewhat longer can be reduced. Mathematical expression 10 can preferably satisfy 1.75 < Nd1 < 2.1. If it is designed to be lower than the lower limit of mathematical expression 10, the performance of reducing the aberration can be obtained, and the refractive power of the first lens may be weakened so that light cannot be collected efficiently, which may lower the performance of the optical system. If it is designed to be higher than the upper limit of mathematical expression 10, there is a disadvantage in that it is difficult to obtain materials. Additionally, when the refractive index of the first lens (101) is designed to be lower than the lower limit of mathematical expression 10, the radius of curvature of the first and second lenses can be increased to increase the refractive power of the first and second lenses.

[0155] [Mathematical Formula 10-1] GMn_Aver < GLn_Aver

[0156] GLn_Aver is the average of the refractive index values ​​at the d-line of the spherical glass lenses, and GMn_Aver is the average of the refractive index values ​​at the d-line of the aspherical glass lenses, which are glass molds. The spherical lens is a lens made of a non-injection-molded glass material, and the aspherical lens is a lens made of an injection-molded glass material. Spherical lenses with a high refractive index can be positioned on the object side of the aspherical lens to increase chromatic dispersion.

[0157]

[0158] [Equation 11] 0 < Nd1 / Nd3 < 1.5

[0159] Nd3 is the refractive index at the d-line of the third lens (103). In mathematical expression 11, the difference in the refractive index of the first lens (101) and the refractive index of the third lens (103) can be reduced, thereby preventing the reduction in color dispersion caused by lenses made of glass. Preferably, in mathematical expression 11, Nd1 and Nd3 can be the same.

[0160] [Equation 12] 0 < Nd3 / Nd4 < 1.5

[0161] Nd4 is the refractive index of the fourth lens (104) at the d-line. In mathematical expression 12, by setting the refractive index of the third lens (103) higher than the refractive index of the fourth lens (104), the chromatic dispersion caused by spherical material lenses and the chromatic dispersion caused by aspherical lenses can be controlled. Preferably, mathematical expression 12 can satisfy 0.5 < Nd3 / Nd4 < 1.2.

[0162] [Equation 13] (Vd4*Nd4) < (Vd2*Nd2)

[0163] Nd2 is the refractive index at the d-line of the second lens (102), and Vd2 and Vd4 are the Abbe numbers of the second and fourth lenses. In mathematical expression 13, by setting the product of the refractive index and Abbe number of the second lens (102) to be greater than the product of the refractive index and Abbe number of the fourth lens (104), the color dispersion by the spherical material lens and the color dispersion by the aspherical lens can be controlled.

[0164] [Mathematical Formula 13-1] (Vd3*Nd3) < (Vd5*Nd5)

[0165] Nd3 and Nd5 are the refractive indices at the d-line of the third and fifth lenses (103 and 105), and Vd3 and Vd5 are the Abbe numbers of the third and fifth lenses. In mathematical expression 13-1, by setting the product of the refractive index and Abbe number of the fifth lens (105) to be greater than the product of the refractive index and Abbe number of the third lens (103), the color dispersion by the spherical material lens and the color dispersion by the aspherical lens can be controlled.

[0166] [Equation 14] BFL < DF2

[0167] BFL is the optical axis distance from the surface of the sensing unit (151) to the center of the sensor-side surface of the last lens, i.e., the fifth lens (105). By satisfying mathematical expression 14, the optical filter (155) can be positioned adjacent to the aperture (ST) or positioned on a lens closer to the object side than the last lens. In addition, mathematical expression 14 can satisfy 3 < DF2 / BFL < 7.

[0168] [Equation 14-1] 1 < SD / DF2 < 1.2

[0169] SD is the distance in the direction of the optical axis from the aperture (ST) to the surface of the sensing unit (151). When mathematical expression 14-1 is satisfied, the optical filter (155) may be placed adjacent to the aperture (ST) or on the sensor side of the aperture (ST).

[0170] [Equation 14-2] BFL < CG3 < DF2

[0171] [Equation 15] CT5 < DF2 < TTL / 2

[0172] In mathematical expression 15, the optical axis distance (DF2) between the optical filter (155) and the sensing unit (151) can be set to be greater than the center thickness of the fifth lens (105) and less than half the TTL value. Accordingly, the incident angle of the main beam incident on the optical filter (155) can be reduced to less than 25 degrees, and the problem of the incident angle shifting at low and high temperatures compared to room temperature can be minimized. Preferably, DF2 satisfies 18 mm < DF2 < 25 mm.

[0173] [Equation 16] DF2 < DF1

[0174] DF1 is the optical axis distance from the center of the object-side surface of the first lens (101) to the object-side surface of the optical filter (155). When mathematical expression 16 is satisfied, the optical filter (155) may be placed between the lenses, between the third and fourth lenses (103, 104), or at a position adjacent to the aperture (ST). Accordingly, the incident angle of the main beam incident on the optical filter (155) can be reduced to less than 25 degrees, and the problem of the incident angle shifting at low and high temperatures compared to room temperature can be minimized. Preferably, 18 mm < DF2 < DF1 < 25 mm can be satisfied.

[0175] [Mathematical Formula 17] 0.1 < OFt < CG3

[0176] If mathematical expression 17 is satisfied, the optical filter (155) SMS can be placed between the third and fourth lenses.

[0177] [Mathematical Formula 18] 1 < CA11 / CA21 < 5

[0178] CA11 refers to the effective diameter of the first surface (S1) of the first lens (101), and CA21 refers to the effective diameter of the third surface (S3) of the second lens (102). When mathematical expression 18 is satisfied, the optical system (100) can control the incident light and set the factors affecting aberration, and preferably, 1 < CA11 / CA21 < 2.5 can be satisfied.

[0179] [Equation 18-1] 1 < CA11 / CA12 < 2

[0180] CA12 denotes the effective diameter of the second surface (S2) of the first lens (101). When mathematical expression 18-1 is satisfied, the amount of incident light can be increased, and an increase in the effective diameter of the second lens can be suppressed. Preferably, 1.2 < CA11 / CA12 < 1.8 can be satisfied.

[0181]

[0182] [Equation 19] 0 < CA22 / CA31 < 1.5

[0183] CA22 refers to the effective diameter of the fourth surface (S4) of the second lens (102), and CA31 refers to the effective diameter of the fifth surface (S5) of the third lens (103). When mathematical expression 19 is satisfied, the optical system (100) can control the incident light path and set the sensor-side surface of the second lens (102) to a concave shape. Preferably, mathematical expression 19 can satisfy 0.5 < CA22 / CA31 < 1.

[0184] [Equation 20] 0.5 < CA42 / CA51 < 2

[0185] CA42 refers to the effective diameter of the eighth surface (S8) of the fourth lens (104), and CA51 refers to the effective diameter of the ninth surface (S9) of the fifth lens (105). When mathematical expression 20 is satisfied, the optical system (100) can set a light path that is incident on the sensing unit (151) through the fourth lens (104) and the fifth lens (105). Mathematical expression 20 can preferably satisfy 1 < CA42 / CA51 < 1.5.

[0186] [Mathematical Formula 21] 1 < CA11 / CA52 < 5

[0187] CA52 refers to the effective diameter of the tenth surface (S10) of the fifth lens (105). When the optical system (100) satisfies mathematical expression 21, the incident amount of the first lens (101) can be increased and the path of light toward the sensing unit (151) through the fifth lens (105) can be set. Mathematical expression 21 can preferably satisfy 1 < CA11 / CA52 < 2.5.

[0188] [Equation 22] 0 < CG2 / (CT2+CT3) < 1

[0189] CG2 is the center spacing between the second and third lenses, and CT2 and CT3 are the center thicknesses of the second and third lenses. When mathematical expression 22 is satisfied, the concave radius of curvature of the sensor-side surface of the second lens (102) can be set, and the optical path between the second and third lenses (102, 103) can be set. Preferably, 0.2 < CG2 / (CT2+CT3) < 0.6 can be satisfied.

[0190] [Equation 23] 0 < CG4 / (CT4+CT5) < 1

[0191] When mathematical expression 23 is satisfied, the optical path can be set according to the center spacing between the fourth and fifth lenses (104, 105). Preferably, 0 < CG4 / (CT4+CT5) < 0.5 can be satisfied.

[0192] [Equation 24] 2 < CG_max / CG4 < 5

[0193] CG_max refers to the maximum center spacing between lenses within the optical system. When mathematical expression 24 is satisfied, the maximum center spacing between lenses is positioned closer to the object than the center spacing between the fourth lens (104) and the fifth lens (105), thereby suppressing an increase in the size of the fourth lens (104). Preferably, 3 < CG_max / CG4 < 4 can be satisfied.

[0194] [Equation 25] 1 < CT5 / BFL < 2

[0195] When mathematical expression 25 is satisfied, the incident light can be transmitted to the entire area of ​​the sensing unit (151) by the fifth lens (105). Preferably, 1 < CT5 / BFL < 1.5 can be satisfied.

[0196] [Equation 26] 0 < CG3 / CT5 < 1

[0197] When mathematical expression 26 is satisfied, the effective diameter of the fifth lens (105) can be adjusted. Preferably, 0.5 < CG3 / CT5 < 1 can be satisfied.

[0198] [Equation 27] 0 < CG4 / CT5 < 1

[0199] When mathematical expression 27 is satisfied, the effective diameter of the fifth lens (105) can be adjusted and the aberration characteristics in the central and peripheral parts of the sensing unit (151) can be improved. Preferably, 0 < CG4 / CT5 < 0.5 can be satisfied.

[0200] [Equation 28] 20 < |L5R2| / CT5 < 70

[0201] L5R2 is the radius of curvature of the sensor-side surface of the fifth lens. When mathematical expression 28 is satisfied, the refractive power of the fifth lens (105) can be controlled and optical performance can be improved. Preferably, 30 < | L5R2 | / CT5 < 60 can be satisfied.

[0202] [Equation 29] 10 < |L5R2| / L5R1 < 40

[0203] L5R1 is the radius of curvature of the object-side surface of the fifth lens. When mathematical expression 29 is satisfied, the refractive power of the fifth lens (105) can be controlled and optical performance can be improved. Preferably, 20 < |L5R2| / L5R1 < 30 can be satisfied.

[0204] [Equation 30] 1 < L1R1 / L1R2 < 5

[0205] L1R1 is the radius of curvature of the object-side surface of the first lens, and L1R2 is the radius of curvature of the sensor-side surface of the first lens. When mathematical expression 30 is satisfied, the refractive power of the first lens (101) can be controlled and the optical performance can be improved. Preferably, 2 < L1R1 / L1R2 < 5 can be satisfied.

[0206] [Equation 31] 5 < L2R1 / L2R2 < 20

[0207] L2R1 is the radius of curvature of the object-side surface of the second lens, and L2R2 is the radius of curvature of the sensor-side surface of the second lens. When mathematical expression 31 is satisfied, the refractive power of the second lens (102) can be controlled and the optical performance can be improved, and the effective diameters of the sensor-side lenses of the second lens (102) can be adjusted. Preferably, 5 < L2R1 / L2R2 < 15 can be satisfied.

[0208]

[0209] [Equation 32] 1 < CT_Max / CG_Max < 2

[0210] In Equation 32, the maximum central thickness (CT_Max) among the lenses and the maximum gap (CT_Max) between adjacent lenses can be set. When Equation 32 is satisfied, the optical system can have good optical performance at the focal length of the set angle of view and can reduce the TTL. Preferably, 1 < CT_Max / CG_Max < 1.5 can be satisfied.

[0211] [Equation 33] 1 < ΣCT / ΣCG < 3

[0212] 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, 1.2 < ΣCT / ΣCG < 2.2 can be satisfied.

[0213] [Equation 34] 5 < ΣNd < 15

[0214] ΣNd represents the sum of the refractive indices at the d-line of each of the plurality of lenses. When mathematical expression 34 is satisfied, TTL can be controlled in an optical system (100) in which aspherical lenses and spherical lenses are mixed, and improved resolution can be achieved. In addition, when the number of spherical lenses is greater than the number of aspherical lenses, the sum of TTL and refractive indices can be set. Mathematical expression 34 can preferably satisfy 7 < ΣNd < 9.

[0215] [Equation 35] 10 < ΣVd / ΣNd < 50

[0216] ΣVd means the sum of the Abbe numbers of each of the plurality of lenses. When mathematical expression 35 is satisfied, the optical system (100) can have improved aberration characteristics and resolution. By setting the sum of the Abbe numbers and the sum of the refractive indices of the lenses in mathematical expression 35, the optical characteristics can be controlled, and preferably, 13 < ΣVd / ΣNd < 23 can be satisfied.

[0217] [Equation 36] 50 < ΣCT*n < 159

[0218] ΣCT is the sum of the central thicknesses of multiple lenses, and n is the number of lenses in the optical system. If mathematical expression 36 is satisfied, TTL can be controlled. Preferably, 100 < ΣCT*n < 135 can be satisfied.

[0219] [Equation 37] 1 < CA11 / CA_Min < 4

[0220] CA_Min represents the minimum effective diameter among the object-side and sensor-side faces of the lenses. When mathematical expression 37 is satisfied, the optical system can control incident light, maintain optical performance, and provide a slimmer module. Mathematical expression 38 can preferably satisfy 1 < CA11 / CA_Min < 3. Here, CA11 may be the maximum effective diameter, and the tenth surface (S10) of the fifth lens (105) may have the minimum effective diameter.

[0221] [Mathematical Formula 38] CA3 < D_OF / CA4 < 4

[0222] CA3 is the average of the effective diameters of the object-side and sensor-side surfaces of the third lens, D_OF is the effective diameter of the optical filter, and CA4 is the average of the effective diameters of the object-side and sensor-side surfaces of the fourth lens. When mathematical expression 38 is satisfied, the incident light can be transmitted through the third lens, the optical filter, and the fourth lens.

[0223] [Equation 39] 0.5 < CA_Max / DF2 < 1.5

[0224] When mathematical expression 39 is satisfied, the position of the optical filter (155) can be set based on the maximum effective diameter. Preferably, 0.6 < CA_max / DF2 < 1.3 can be satisfied.

[0225] [Equation 40] 0.3 < CA_Min / DF2 < 1

[0226] Mathematical expression 30 sets the minimum effective diameter of the lens surface and the position of the optical filter, which can reduce TTL. Preferably, 0.3 < CA_Min / DF2 < 0.8 can be satisfied.

[0227] [Mathematical Formula 41] 1 < CA_max / (2*ImgH) < 5

[0228] Mathematical expression 42 can be set by the maximum effective diameter (CA_Max) and the diagonal length of the sensing unit (2*ImgH), and if this is satisfied, the optical system can maintain good optical performance and a slim and compact sensor device can be set. Mathematical expression 41 can preferably satisfy 2 < CA_max / (2*ImgH) < 4.3.

[0229]

[0230] [Equation 42] 1 < TD / CA_Max < 4

[0231] TD is the optical axis distance from the center of the object-side surface of the first lens to the center of the sensor-side surface of the last lens. When mathematical expression 43 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. Mathematical expression 42 preferably satisfies 1.5 < TD / CA_Max < 2.2.

[0232] [Equation 42-1] SD < TD

[0233] The above SD is the optical axis distance from the position of the aperture to the surface of the sensing unit. Preferably, the condition of 2 < TD / SD < 2.5 can be satisfied.

[0234]

[0235] [Equation 43] 0 < F / L5R2 < 0.5

[0236] F is the effective focal length of the optical system, and L5S2 is the radius of curvature of the sensor-side surface of the fifth lens. When mathematical expression 43 is satisfied, the effect on optical system reduction, such as TTL, can be controlled by setting the effective focal length and the radius of curvature of the sensor-side surface of the last aspherical lens. Mathematical expression 43 can preferably satisfy 0 < F / L5R2 < 0.2.

[0237] [Equation 44] 0 < F / L1R1 < 0.5

[0238] In mathematical expression 44, the effective focal length of the optical system and the radius of curvature of the object-side surface of the first lens can be set to control the influence on the incident light and TTL. Mathematical expression 44 can preferably satisfy 0 < F / L1R1 < 0.25.

[0239] [Equation 45] 0 < EPD / |L5R2| < 0.5

[0240] EPD refers to the size of the entrance pupil of the optical system (100). When the optical system (100) according to the embodiment satisfies mathematical expression 45, the optical system (100) can control incident light. Preferably, the condition of 0 < EPD / |L5R2| < 0.2 can be satisfied.

[0241] [Equation 46] 0 < EPD / L1R1 < 0.5

[0242] In mathematical expression 46, the size of the entrance pupil of the optical system (100) and the radius of curvature of the object-side surface of the first lens can be set, and when these are satisfied, the optical system (100) can control the incident light. Preferably, the condition of 0 < EPD / L1R1 < 0.2 can be satisfied.

[0243] [Equation 47] 0 < |F1 / F2| < 5

[0244] F1 is the focal length of the first lens, and F2 is the focal length of the second lens. When mathematical expression 47 is satisfied, the refractive power of the first and second lenses can be controlled to improve the resolution, and can affect TTL and EFL. Preferably, the condition 1 < |F1 / F2| < 2 or |F2| < |F1| can be satisfied.

[0245] [Equation 48] 0 < |F1| / F < 10

[0246] In mathematical expression 48, the focal length of the first lens and the effective focal length of the optical system can be set, and the resolution can be improved by controlling the refractive power of the first lens. Preferably, 0 < |F1| / F < 5 can be satisfied.

[0247] [Equation 49] 0 < |F1 / F5| < 10

[0248] In mathematical expression 49, the focal lengths of the first and fifth lenses can be set, and the refractive power of the first and fifth lenses can be controlled to improve the resolution. Preferably, 1 < |F1 / F5| < 2 can be satisfied.

[0249] [Equation 49-1] |F1|< F4

[0250] [Equation 49-2] F4 < F3

[0251] [Equation 49-3] F5 < F4

[0252] In mathematical expressions 49-1 to 49-3, F1, F2, F3, F4, and F5 represent the focal lengths of the first to fifth lenses, and by adjusting the focal length of the spherical lens to the focal length of the last aspherical lens, light can be guided to the effective area of ​​the aspherical lens. The balance of the focal lengths of each of the lenses can suppress the difference in focus position due to temperature change. Accordingly, the optical characteristics of the imaging lenses can be suppressed from deteriorating due to temperature change.

[0253] Here, the aperture (ST) is arranged on the sensor-side surface of the third lens (103). The focal length of the lens arranged on the sensor-side surface closer to the aperture (ST) and closest to the aperture (ST) is greater than 0. In the embodiment of the present invention, the focal length F3 of the third lens (103) should be designed to be greater than 0. In this case, the third lens (103) gathers light, so that the effective diameters of the fourth and fifth lenses, which are lenses arranged closer to the sensor than the third lens (103), can be prevented from increasing, and the TTL can be prevented from becoming longer, thereby enabling miniaturization of the optical system. In this case, a wide-angle optical system can be provided in a field of view (FOV) exceeding 100 degrees, for example, in a range of 110 degrees to 130 degrees.

[0254]

[0255] [Equation 50] 0 < | F1 / F4| < 2

[0256] F1 is the refractive power of the first lens, and F4 is the refractive power of the fourth lens. In other words, the refractive powers of the first and fourth lenses are opposite to each other, so they can improve aberrations and effectively guide light with an aspherical lens. When the condition of F1 * F4 < 0, the improvement effect of chromatic aberration in the two lenses is not significant.

[0257] [Mathematical Formula 51] 20mm < TTL < 60mm

[0258] TTL (Total track length) refers to the distance (mm) from the center of the first surface (S1) of the first lens (101) to the upper surface of the sensing unit (151) on the optical axis (OA). By setting TTL in mathematical expression 51, an optical system for a vehicle can be provided. Mathematical expression 51 can preferably satisfy 30 mm < TTL < 55 mm.

[0259] [Mathematical Formula 52] 2mm < ImgH < 20mm

[0260] Mathematical expression 52 can set the diagonal size of the sensing unit (151) and provide an optical system having a vehicle sensor size. Mathematical expression 52 can preferably satisfy 2 mm < ImgH < 5 mm.

[0261] [Mathematical Formula 53] 3mm < BFL < 7mm

[0262] By setting the BFL (Back focal length) in Equation 53, the installation space of the cover glass (153) can be secured, the assembling of components can be improved through the gap between the sensing unit (151) and the last lens, and the joining reliability can be improved. Equation 53 can preferably satisfy 3.5 mm < BFL < 5.5 mm. If the BFL is less than the range of Equation 53, some of the light traveling to the sensing unit may not be transmitted to the sensing unit, which may cause a decrease in resolution. If the BFL exceeds the range of Equation 53, stray light may be introduced, which may deteriorate the aberration characteristics of the optical system.

[0263] [Mathematical Formula 54] 1mm < F < 10mm

[0264] Mathematical expression 54 can set the overall focal length (F) to suit the vehicle optical system. Mathematical expression 54 can satisfy 1 mm < F < 5.5 mm.

[0265] [Mathematical Formula 55] 100 degrees < FOV

[0266] In mathematical expression 55, FOV (Field of view) refers to the angle of view (Degree) of the optical system (100), and a vehicle optical system having an angle of view (F0V) exceeding 100 degrees can be provided. Preferably, the FOV can satisfy 110 ≤ FOV ≤ 130.

[0267] In mathematical expression 55, the range of the vehicle optical system can be set by the angle of view. The horizontal sensor length is based on 6.04 mm ± 0.5 mm. In addition, when mathematical expression 55 is satisfied, when the temperature changes from room temperature to high temperature, the change rate of the effective focal length and the change rate of the angle of view can be set to 5% or less, for example, 0 to 5%. In addition, even if two or more aspherical lenses are used in combination with spherical lenses in the optical system (100), the deterioration of optical characteristics can be prevented through temperature compensation and aberration correction by the aspherical lens made of glass.

[0268]

[0269] [Mathematical Formula 56] 1 < TTL / CA_max < 7

[0270] Mathematical expression 56 establishes a relationship between the total optical axis length of the optical system and the maximum effective diameter, thereby providing an improved vehicle optical system. Mathematical expression 56 preferably satisfies 1 < TTL / CA_max < 3.

[0271] [Equation 57] 10 < TTL / ImgH < 30

[0272] Mathematical expression 57 can set the total optical axis length (TTL) of the optical system and the diagonal length (ImgH) from the center of the sensing unit (151). When the optical system (100) according to the embodiment satisfies Mathematical expression 57, the optical system (100) can have TTL for application to the vehicle sensing unit (151), thereby providing improved image quality. Mathematical expression 57 can preferably satisfy 10 < TTL / ImgH < 20.

[0273] [Equation 58] 1 < BFL / ImgH < 2

[0274] Mathematical expression 58 can set the optical axis distance between the sensing unit (151) and the fifth lens (105) and the length in the diagonal direction from the center of the sensing unit (151). When the optical system (100) according to the embodiment satisfies Mathematical expression 58, the optical system (100) can secure a BFL for applying the size of the vehicle sensing unit (151), can set the gap between the fifth lens (105) and the sensing unit (151), and can have good optical characteristics in the center and periphery of the field of view (FOV). Mathematical expression 58 can preferably satisfy 1.2 < BFL / ImgH < 1.8.

[0275] [Equation 58-1] ImgH < BFL < DF2

[0276] BFL may be greater than a value (ImgH) that is half the diagonal length of the sensing unit (151) and less than the optical axis distance from the optical filter (155) to the surface of the sensing unit (151).

[0277] [Equation 59] 4 < TTL / BFL < 15

[0278] Mathematical expression 59 can set the total optical axis length (TTL) of the optical system and the optical axis spacing (BFL) between the sensing unit (151) and the last lens. When the optical system (100) according to the embodiment satisfies Mathematical expression 59, the optical system (100) can secure BFL. Mathematical expression 59 can preferably satisfy 8 < TTL / BFL < 12.

[0279] [Equation 60] 0 < F / TTL < 0.5

[0280] Mathematical expression 60 can set the total focal length (F) and the total optical axis length (TTL) of the optical system (100). Accordingly, an optical system for a driver assistance system can be provided. Mathematical expression 60 can preferably satisfy 0 < TTL / F < 0.1. When the optical system (100) according to the embodiment satisfies Mathematical expression 60, the optical system (100) 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 becomes long, which may cause a problem of the imaging lens system becoming large.

[0281] [Equation 61] 0 < F / BFL < 1

[0282] Mathematical expression 61 can set the total focal length (F) of the optical system (100) and the optical axis distance (BFL) between the sensing unit (151) and the last lens. When the optical system (100) according to the embodiment satisfies Mathematical expression 61, the optical system (100) can have a set angle of view and an appropriate focal length, and an optical system for a vehicle can be provided. In addition, the optical system (100) can minimize the distance between the last lens and the sensing unit (151), and thus can have good optical characteristics in the periphery of the field of view (FOV). Mathematical expression 61 can preferably satisfy 0.5 < F / BFL < 1.

[0283] [Equation 62] 0.5 < F / ImgH < 1.5

[0284] Mathematical expression 62 can set the total focal length (F) of the optical system (100) and the diagonal length (ImgH) from the center of the sensing unit (151). This optical system (100) can have improved aberration characteristics in the size of the vehicle sensing unit (151). Mathematical expression 62 can preferably satisfy 1 < F / ImgH < 1.4.

[0285]

[0286] [Equation 63] 0.5 < F / EPD < 1.5

[0287] Mathematical expression 63 can set the overall focal length (F) and entrance pupil size of the optical system (100). Accordingly, the overall brightness of the optical system can be controlled. Mathematical expression 63 preferably satisfies 0.5 < F / EPD < 1.

[0288] [Mathematical Formula 64] 0 < EPD / ImgH / FOV < 0.2

[0289] Mathematical expression 64 can set the relationship between the entrance pupil size (EPD), the length of half the maximum diagonal length of the sensing unit (ImgH), and the field of view. Accordingly, the overall size and brightness of the optical system can be controlled. Mathematical expression 64 can preferably satisfy 0 < EPD / ImgH / FOV < 0.1.

[0290] [Equation 65] 100 < FOV / F# < 200

[0291] Mathematical expression 65 can establish the relationship between the angle of view and the F number (F#) of the optical system. Mathematical expression 65 can preferably satisfy 120 < FOV / F# < 170. Here, F# is provided to be 1.2 or less, thereby providing a bright image.

[0292] [Equation 66] 40 < (CT_Max+CG_Max)*n < 140

[0293] [Mathematical Formula 67] 800 < (FOV*TTL) / n

[0294] Preferably, mathematical expression 67 can satisfy the condition of 1000 < (FOV*TTL) / n < 1200 depending on the angle of view and the number of lenses (n).

[0295] [Mathematical Formula 68] FOV < (TTL*n)

[0296] [Equation 69] 5 < (TD / CA_Max)*n < 30

[0297] Preferably, 8 < (TD / CA_Max)*n < 12 can be satisfied.

[0298] [Mathematical Formula 70] 0 < (CA52 / CA22) / (CA11 / CA21) < 1.5

[0299] 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, effective diameter (CA52) of the sensor-side surface of the fifth lens, effective diameter (CA11) of the object-side surface of the first lens, and effective diameters (CA21, CA22) of the object-side and sensor-side surfaces of the second lens can be set. Accordingly, the chromatic aberration, resolution, size, etc. of an optical system having 6 or fewer lenses can be controlled.

[0300]

[0301] [Equation 71]

[0302]

[0303] In mathematical expression 71, Z may represent Sag, which is the distance in the direction of the optical axis from an arbitrary 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 an arbitrary 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 constants from the 4th to the 14th order.

[0304] The optical system (100) according to the embodiment can satisfy at least one or two or more mathematical equations from mathematical equations 1 to 70. In this case, the optical system (100) can have improved optical characteristics. Specifically, when the optical system (100) satisfies at least one of mathematical equations 1 to 35 and / or at least one of mathematical equations 36 to 70, the optical system (100) can have improved resolution and improve aberration and distortion characteristics. In addition, the optical system (100) can secure a BFL (Back focal length) for applying a vehicle sensing unit (151), can compensate for optical characteristic degradation due to temperature change, and can minimize the gap between the last lens and the sensing unit (151), thereby having good optical performance at the center and periphery of the field of view (FOV).

[0305]

[0306] Table 2 shows the items of the mathematical formulas described above in the optical system (100) of the embodiment, including the TTL, BFL, F, ImgH, effective diameter, sum of the center thicknesses of each lens, sum of the center spacings between adjacent lenses, TTL, sum of Abbe numbers, sum of refractive indices, TD which is the optical axis distance from the first surface (S1) to the tenth surface (S10), focal lengths (F1, F2, F3, F4, F5), angle of view (degrees), edge thickness (ET), F number, etc. of each of the first to fifth lenses.

[0307] Item ValueItem ValueF(EFL)3.351ET13.674F1-17.776ET26.654F2-11.933ET35.145F331.811ET43.505F419.897ET53.061F513.659FOV12 8.971ΣNd8.752EPD4.184ΣVd150.790BFL4.436ΣCT25.384TD40.727ΣCG14.843ImgH3.024TTL45.163SD18.307F-number0.801

[0308]

[0309] Table 3 shows the result values ​​for the mathematical expressions 1 to 35 described above in the optical system (100) of the embodiment. Referring to Table 3, it can be seen that the optical system (100) satisfies at least one, two or more, or three or more of the mathematical expressions 1 to 35. In detail, it can be seen that the optical system (100) according to the embodiment satisfies all of the mathematical expressions 1 to 35. Accordingly, the optical system (100) can have good optical performance and excellent optical characteristics in the center and periphery of the field of view (FOV).

[0310] Equation value 10 < CT1 / CT2 < 20.55624 < CA11 / CT1 < 128.74030 < CT5 / CT4 < 30.96540 < CT5 / (CT1+CT2) < 30.85551 < CG3 / CT1 < 31.88561 < CG1 / CG4 < 53.13572 < CG3 / OFt < 159.41980.5 < CG3 / (CT1+CG1+CT2) < 1.50.41291 < TTL / DF2 < 42.126101.60 < Nd11.816110 < Nd1 / Nd3 <1.51.000120 < Nd3 / Nd4 <1.51.08813(Vd2*Nd2) < (Vd1*Nd1) Satisfied 14 BFL < DF2 Satisfied 15 CT5 < DF2 < TTL / 2 Satisfied 16 DF2 < DF1 Satisfied 17 0.1 < Opt < CG3 Satisfied 181 < CA11 / CA21 < 51.700190 < CA22 / CA31 < 1.50.923200.5 < CA42 / CA51 < 21.200211 < CA11 / CA52 < 52.069220 < CG2 / (CT2+CT3) < 10.401230 < CG4 / (CT4+CT5) < 10.116242 < CG_max / CG4 < 53.339251 < CT5 / BFL < 21.349260 < CG3 / CT5 < 10.787270 < CG4 / CT5 < 10.2362820 < |L5R2| / CT5 < 7041.7812910 < |L5R2| / L5R1 < 4026.821301 < L1R1 / L1R2 < 53.188315 < L2R2 / L2R1 <2010.677321 < CT_Max / CG_Max < 21.316331 < ∑CT / ∑CG < 31.710345 < ∑Nd <158.7523510 < ∑Vd / ∑Nd <5017.229

[0311]

[0312] Table 4 shows the result values ​​for the mathematical expressions 36 to 70 described above in the optical system (100) of the embodiment. Referring to Table 4, it can be seen that the optical system (100) satisfies at least one, two or more, or three or more of the mathematical expressions 36 to 70. In detail, it can be seen that the optical system (100) according to the embodiment satisfies all of the mathematical expressions 1 to 70. Accordingly, the optical system (100) can have good optical performance and excellent optical characteristics in the center and periphery of the field of view (FOV).

[0313] 수학식값3650 < ∑CT*n < 159126.918371 < CA11 / CA_min < 42.10138CA3 < D_OF < CA4만족390.5 < CA_max / DF2 < 1.51.029400.3 < CA_min / DF2 < 10.490411 < CA_max / (2*ImgH) < 53.613421 < TD / CA_Max < 41.864430 < F / |L5R2| < 0.50.013440 < F / L1R1 < 0.50.112450 < EPD / |L5R2|< 0.50.017460 < EPD / L1R1 < 0.50.139470 < |F1 / F2| < 51.490481 < |F1| / F < 105.305490 < |F1 / F5| < 101.301500 < | F1 / F4| <20.8935120 < TTL < 6045.163522 < ImgH < 203.024533 < BFL < 74.436541 < F < 103.35155100 < FOV < 150128.971561 < TTL / CA_max < 72.0675710 < TTL / ImgH < 3014.935581 < BFL / ImgH < 21.467594 < TTL / BFL < 1510.181600 < F / TTL < 0.50.074610 < F / BFL < 10.755620.5 < F / ImgH < 1.51.108630.5 < F / EPD < 1.50.801640 < EPD / Imgh / FOV < 0.20.01165100 < FOV / F# <200161.0336640 < (CT_Max+CG_Max)*n < 14054.56067800 < (FOV*TTL) / n1164.94168FOV < (TTL*n)만족695 < (TD / CA_max) *n < 309.320700 < (CA52 / CA22) / (CA11 / CA21) < 1.50.597

[0314]

[0315] FIG. 10 is a block diagram of a sensor system having a transmitting / receiving optical system according to an embodiment of the invention.

[0316] 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).

[0317] The above 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 the light source included in the transmission optical system (30) to drive it. The light source generates a laser beam in the form of a line light source or a point light source. The light source driving unit (20) can adjust or vary the driving current supplied to the light source according to driving environment information. The driving environment information may include topographic information of the driving section, traffic congestion information, weather, etc.

[0318] The wavelength of the laser beam generated from the light source may be 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 laser light source may be implemented as an InGaAs / GaAs-based semiconductor diode laser and may emit a high-power laser beam. The light source may include a single emitter and / or multiple emitters. The transmitting optical system (30) transmits the laser beam generated from the light source to an object (40) through a lens unit and a diffuser, and the light reflected from the object (40) is received by the receiving optical system (50). The receiving optical system (50) may be composed of a plurality of optical sensors, and the optical sensor converts the received light into an electrical signal using a photodiode. That is, the sensing unit is arranged in a matrix type to convert light received from an object scanned in each of the horizontal and vertical directions into current.

[0319] The signal processing unit (60) converts the output of the receiving optical system (50) into 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. The control unit (10) can receive the vehicle's 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's speed, the road condition of the road on which the vehicle is driving, and the driving environment information, and can provide sensor data including the distance to the object and the shape information of the object to the free-roaming device.

[0320]

[0321] FIG. 11 is a side cross-sectional view of a transmission optical system of a lidar according to an embodiment, FIG. 12 is a drawing showing a first lens and a diffuser of the optical system of FIG. 11, FIG. 13 is an example of an optical path through a lens array of a diffuser of a comparative example and an embodiment, and FIG. 14 is a table showing lens characteristics of the optical system of FIG. 11.

[0322] Referring to Fig. 11, an optical system (110) 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 material of each of the lenses can be selected from glass or plastic, and since the coefficient of linear expansion of each lens is smaller for glass than for plastic, lenses made of glass can be employed to suppress changes in the focal imaging position due to temperature changes. However, when configuring an optical system with spherical glass lenses, there is a limit to reducing the number of lenses, and there is a limit to reducing the size and weight.

[0323] The optical system (110) is a transmission optical system and 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 lens. The optical system (110) may include a spherical glass lens and an aspherical glass lens. In addition, by employing an aspherical lens, the overall length (TTL) of the optical system (110) can be reduced, and the aspherical lens can provide good correction for various aberrations such as spherical aberration and chromatic aberration. In addition, the aspherical lenses can minimize distortion in the peripheral area.

[0324] The optical system (110) may include n lenses, where the nth lens may be the last lens adjacent to the image sensor (151), 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 either 3:1 or 2:2.

[0325] The optical system (110) may be configured such that the first lens (111) closest to the water is made of glass. The glass material exhibits little expansion and contraction changes due to external temperature changes, and the surface is not easily scratched, thereby preventing surface damage. Accordingly, the lenses closest to the object in the optical system (110) may be spherical lenses, and the lenses closest to the light source (116) may be aspherical lenses. That is, the last lens closest to the light source (116) in the optical system (110) may be an aspherical lens. The nth lens in the optical system (110) may be an aspherical lens. The last lens may emit light from the light source (116) through 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 (116) may be aspherical lenses.

[0326] The lenses within the optical system (110) 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 the lenses made of plastic, the lenses made of glass may be placed in an area adjacent to the outside within the lens barrel.

[0327]

[0328] Each of the above lenses may have an object-side surface and a light source-side surface. The lenses may include lenses having an object-side spherical surface and a light source-side spherical surface, and lenses having an object-side aspherical surface and a light source-side aspherical surface. The number of aspherical lenses in the optical system (110) may be smaller than the number of spherical lenses. The optical system (110) may provide variously refracted light by arranging the aspherical lenses adjacent to the light source (116). The spherical lenses may be made of glass, and the aspherical lenses may be made of glass mold. Among the lenses of the optical system (110), the lens having the highest refractive index may be a spherical lens, and the lens having the highest Abbe number may be a spherical lens. Accordingly, since the lens having the highest refractive index is arranged on the object side, it is easy to change the radius of curvature of the lenses after the second lens, and the central thickness may be increased.

[0329]

[0330] Within the optical system (110), a lens having a maximum effective diameter is positioned closest to an aspherical lens, may be made of glass, and may be a spherical lens. Within the optical system (110), a lens having a minimum effective diameter may be arranged between spherical lenses. Here, the effective diameter of the lens is an average value of the effective diameter of the object-side surface of each lens and the effective diameter of the light source-side surface. Each of the lenses (111-114) 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 an effective diameter through which the incident light is refracted to implement optical characteristics. The ineffective area may be arranged around 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. Additionally, the end of the non-effective area may be an area fixed to a lens barrel (not shown) that accommodates the lens.

[0331]

[0332] Among the lenses of the optical system (110), the lens having the maximum center thickness may be a spherical lens, and the lens having the maximum edge thickness may be an aspherical lens. The lens (113) having the maximum thickness and the lens (113) having the maximum effective diameter may be the same lens. The center thickness of the aspherical lens may be greater than the average of the center thicknesses of the spherical lenses. Such an aspherical lens may be arranged adjacent to the light source (116) to refract laser light to the entire area of ​​the object-side lenses.

[0333] Within the optical system (110), 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 (111) to the surface of the light source (116) on the optical axis (OA). The LsH is the distance from the center of the light source (116) to the diagonal end or half of the maximum diagonal length of the light source (116). In addition, the effective diameter of each lens within the optical system (110) may be greater than the diagonal length of the light source (116). Within the optical system (110), the effective focal length (EFL) may be more than 5 mm and the field of view (FOV) may be less than 70 degrees or 29±10 degrees, so that the optical system 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 may be applied to a sensing device for an Advanced Driving Assistance System (ADAS) installed inside or outside a vehicle. The angle of view may be defined as the divergence angle in the transmission optical system.

[0334] Since the mathematical equation: 5 < TTL / LsH < 15 is satisfied in the optical system (110), the central thickness of each lens along the optical axis (OA) can be increased and the size of the light source (116) can be reduced. Accordingly, a vehicle lens optical system can be provided. In addition, in order to be used in a vehicle camera, temperature compensation must be applied in the temperature range that serves as the temperature reliability evaluation standard for automotive electrical components, that is, from -40°C to 120°C. That is, the lens must be configured so that the focus of the lens is maintained within the set range even when the lens expands or contracts due to temperature changes. The total effective focal length (EFL) can be greater than 5 mm, for example, in the range of 8 mm to 20 mm, and can be configured with lenses made of glass capable of the aforementioned temperature compensation. The optical system (110) can implement a narrow angle by making the effective focal length longer than the receiving optical system.

[0335]

[0336] In the optical system (110), 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. Since the optical system (110) is a mixture of spherical lenses and aspherical lenses made of glass, optical performance degradation can be prevented. The effective diameter of the lens closest to the object in the optical system (110) may be smaller than the effective diameter of the lens closest to the light source (116). Accordingly, the brightness of the optical system can be controlled. By controlling the effective diameter size of each lens, the optical system (110) can control the emitted light to compensate for the deterioration of optical characteristics due to resolution and temperature changes, and can improve chromatic aberration control characteristics. By controlling the effective diameters of the lenses, there is an effect of enabling miniaturization of the optical system (110).

[0337]

[0338] The optical system (110) may include a first lens (111), a second lens (112), a third lens (113), and a fourth lens (114) aligned along an optical axis (OA) from an object toward a light source. The first to fourth lenses (111, 112, 113, 114) may be defined as a lens unit. The light source (116) generates a laser beam, and the wavelength of the laser beam may be 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 (116) may be implemented as an InGaAs / GaAs-based semiconductor diode laser and may emit high-power laser light. The light source (116) may include a single emitter and / or multiple emitters. The above light source (116) generates laser light in the form of a line light source or a point light source.

[0339]

[0340] When the radius of curvature is described as an absolute value, the lens surface having the minimum radius of curvature with respect to the optical axis (OA) within the optical system (110) may be the light source-side surface (S8) of the fourth lens (114) among the spherical surfaces. Accordingly, the center distance (CG2) between the second lens (112) and the third lens (113) may be set to be greater than the center distance (CG1) between the first lens (111) and the second lens (112). The lens surface having the maximum radius of curvature within the optical system (110) may be the light source-side surface of the third lens (113). By adjusting the radius of curvature of each lens, the CRA (Chief ray angle) may be minimized to 0.5 degrees or less from the optical axis to the end of the effective area, that is, throughout the entire field, thereby maximizing transmission efficiency. Here, as the CRA increases, the asymmetry of the divergence angle with respect to the center of the light source (116) of the optical system (110) increases, which may reduce the transmission efficiency.

[0341] The optical system (110) may include an aperture (ST: Stop). The aperture (ST) may control the amount of light emitted from the optical system (110). The aperture (ST) may be arranged on the periphery of the object-side surface of the first lens (111). The aperture (ST) may be spaced apart from the object-side surface of the first lens (111) by a predetermined distance (CG0). The optical axis distance (CG0) between the first lens (111) and the aperture (ST) may be 1.2 mm or more. Since the aperture (ST) is spaced apart from the object-side surface of the first lens (111) by the distance, an increase in the effective length of the diffuser (119) may be suppressed.

[0342]

[0343] As shown in FIGS. 11 and 12, a diffuser (119) may be placed between an object and the aperture (ST). The diffuser (119) may include a lens array, for example, a micro lens array, on at least one of an incident side surface and an exit side surface. The micro lens array may be placed on the exit side surface of the diffuser (119). Each of the micro lenses (119A) may have a long length in a first direction (vertical direction) and may be spaced apart from each other in a plurality in a second direction (horizontal direction). Each of the lenses may have a cylindrical cross-section and may have a convex hemispherical shape. The diffuser (119) may have a square shape in plan view.

[0344] The above diffuser (119) can refract the light emitted through the first lens (111) and emit it as parallel light. Since the light emitted through the first lens (111) is provided as parallel light, the radius of curvature of the object-side surface of the fifth lens (101) of the receiving optical system (100) of Fig. 1 can be increased to resemble a flat surface. Accordingly, the amount of light incident through the fifth lens (101) can be increased.

[0345]

[0346] The optical system (110) having the first to fourth lenses (111-114) can spread the horizontal field of view (HFOV) of the receiving optical system (100) to 120 degrees or more because the object-side diffusers (119) are arranged in a one-dimensional shape. That is, since the diffusers (119) are arranged as a cylindrical lens array having a long length in the first direction (vertical direction), only the horizontal field of view (HFOV) can be increased without a significant change in the vertical field of view (VFOV). The aspect ratio of the optical system (110) and the receiving optical system (100) by the diffusers (119) is the ratio of the width to the height of the image sensor, and can be expressed as H:V=1:7. This has the effect of enabling optical matching by means of a diffuser (119) even if the aspect ratios of the optical system and the receiving optical system are different compared to the aspect ratio of the existing receiving optical system, which is H:V=3.43:1. Accordingly, the size of the transmitting / receiving optical system can be reduced.

[0347] In the transmission optical system (110) of the embodiment, the sum of the refractive indices of the lenses of the lens unit (110) may be 6 or more, for example, in the range of 6 to 10, and the average of the refractive indices may be in the range of 1.70 to 1.80. The sum of the Abbe numbers of each of the lenses may be 180 or less, for example, in the range of 120 to 180, and the average of the Abbe numbers may be 50 or less, for example, in the range of 35 to 50. By adjusting the refractive indices of the lenses within the optical system (110), 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.

[0348] In the transmission optical system, the sum of the central thicknesses of all lenses may be 13 mm or more, for example, in the range of 13 mm to 23 mm, and the average of the central thicknesses may be 3.9 mm or more, for example, in the range of 3.9 mm to 5.9 mm. The sum of the central spacings between the lenses on the optical axis (OA) may be 25 mm or less, for example, in the range of 8 mm to 20 mm, and may be less than the sum of the central thicknesses of the lenses. The optical system (110) 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.

[0349] In an optical system according to an embodiment of the invention, the angle of view may be less than 70 degrees, for example, in the range of 20 to 60 degrees. The F number of the optical system or camera module may be 1.8 or less, for example, in the range of 1.2 to 1.8 or in the range of 1.2 to 1.7. Accordingly, the optical system (110) may provide a bright optical system. In addition, the relative illumination (RI) may be 90% or more, for example, 93% or more. The diagonal length of the light source (116) may be 8.33 mm ± 0.5 mm 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.

[0350]

[0351] Since Fig. 11 is a transmission optical system applied to a lidar device, the first lens (111) may be provided with a glass material. This is because glass has the advantage of being scratch-resistant and insensitive to external temperatures compared to plastic materials. In order to more effectively prevent scratches caused by foreign substances or when placed inside a vehicle, a glass lens may be used as the first lens (111), and the object-side surface of the first lens (111) 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 may be used for an advanced driver assistance system (ADAS). The optical system (110) according to an embodiment may further include a reflective member (not shown) for changing the path of light. The reflective member may be placed on the object side of the diffuser (119) and may be implemented as a prism. Hereinafter, the optical system according to an embodiment will be described in detail.

[0352] Referring to FIGS. 11 and 14, the optical system (110) may include a first lens (111) to a fourth lens (114) sequentially aligned along the optical axis (OA). Laser light generated from the light source (116) may be emitted by the fourth lens (114), the third lens (113), the second lens (112), and the first lens (111) and irradiated onto a subject through a diffuser (119).

[0353] The above aperture (ST) may be arranged closer to the diffuser (119) than the object-side surface of the first lens (111). The aperture (ST) may be spaced apart from the vertex of the first surface (S1) of the first lens (111) by a predetermined distance (CG0). Since the first lens (111) adjacent to the light source side of the aperture (ST) has positive refractive power (F1 > 0), the first lens (111) 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 the rear side lens of the first lens (111).

[0354] The above diffuser (119) is arranged on the object side of the aperture (ST) and can refract light passing through the aperture (ST) toward the subject as parallel light. As shown in FIGS. 12 and 13, the diffuser (119) of the embodiment uses a micro lens array to control the path of passing light. At this time, a change in the Field of Illumination (FOI) occurs in the on-axis direction separate from the direction in which the light travels. In the comparative example of FIG. 13, it can be seen that the FOI changes in the off-axis direction after passing through the micro lens array. Here, when looking at the light path after passing through the diffuser (119), the comparative example has an optical path of F*θ, and the embodiment has an optical path of f*sinθ.

[0355]

[0356] The power of the first lens (111) can be positive (+) or negative (-) on the optical axis (OA), for example, positive (+). The first lens (111) can include a plastic material or a glass material, for example, can be a glass material. The first lens (111) made of a glass material can reduce changes in the center position and radius of curvature due to temperature changes in the surrounding environment, and can protect the output side surface of the optical system (110).

[0357] On the optical axis (OA), the first surface (S1) on the object side of the first lens (111) may have a convex shape, and the second surface (S2) on the light source side may have a convex shape. The first surface (S1) and the second surface (S2) may have spherical surfaces. The first lens (111) may have a convex shape on both sides. Alternatively, the first lens (111) may have a meniscus shape that is convex toward the object side. Alternatively, the first surface (S1) on the optical axis (OA) may have a concave shape, and the second surface (S2) may have a convex shape. Since the first surface (S1) is convex, the first lens (111) can refract the emitted light in a direction close to the optical axis (OA), reduce the gap between the first and second lenses (111, 112), and reduce the effective diameter of the first lens (111). The effective diameter of the light source-side surface of the second lens (112) can be designed to be smaller than the effective diameter of the object-side surface due to the shape of the lens surface of the first lens (111). The first surface (S1) and the second surface (S2) of the first lens (111) can be provided from the optical axis (OA) to the end of the effective area, i.e., the edge, without a critical point. When the refractive index of the first lens (111) is Nd1, the condition of Nd1 > 1.70 or 2.0 > Nd1 > 1.70 can be satisfied. Since the refractive index (Nd1) of the first lens (111) is higher than that of an aspherical lens, the radius of curvature of the first surface (S1) of the first lens (111) can be larger than that of an aspherical lens, and lens manufacturing can be facilitated. If the refractive index (Nd1) of the first lens (111) is lower than the above condition, the lens surface must be formed sharply concave or convex in order to increase the refractive power of the first and second lenses (111, 112). In this case, lens manufacturing is not easy, the lens defect rate increases, and this may cause a decrease in yield.Since the first lens (111) is arranged on the light source side of the aperture (ST) and diffuser (119), the center thickness (CT1) of the first lens (111) can be provided to be thinner than the center thicknesses of the third and fourth lenses (113, 114). In addition, the effective diameter of the first lens (111) can be smaller than the effective diameters of the third and fourth lenses (113, 114). Since the first lens (111) is arranged on the light source side of the aperture (ST) and diffuser (119), the radius of curvature of the first lens (111) can have a radius of curvature that is larger than the average of the absolute values ​​of the radii of curvature of the second lens (112). The radius of curvature of each lens is the average of the absolute values ​​of the radii of curvature of the object-side surface and the light source-side surface of each lens.

[0358]

[0359] The second lens (112) may be arranged between the first lens (111) and the third lens (113). The power of the second lens (112) may be positive (+) or negative (-) on the optical axis (OA), for example, negative (-). The second lens (112) 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 (112) on the optical axis (OA) may have a concave shape, and the light source-side fourth surface (S4) may have a concave shape. The third and fourth surfaces (S3, S4) may be spherical. The third and fourth surfaces (S3, S4) may be provided without a critical point to the end of the central effective area of ​​each lens surface. In contrast, the third surface (S3) may have a convex shape, and the fourth surface (S4) may have a concave shape. In contrast, the second lens (112) may have a convex shape on both sides.

[0360] When the refractive index of the second lens (112) is Nd2, the condition of Nd2 < 1.7 or 1.4 < Nd2 < 1.7 can be satisfied. The refractive index (Nd2) of the second lens (112) can be lower than the refractive index of the aspherical lens. Since the fourth surface (S4) on the light source side of the second lens (112) is concave and the radius of curvature is 20 mm or less, the center spacing between the second lens (112) and the third lens (113) can be spaced apart. In addition, when the radius of curvature of the third surface (S3) of the second lens (112) is L2R1 and the radius of curvature of the fourth surface (S4) is L2R2, the condition: L2R2 < │L2R1│ can be satisfied. When this condition is satisfied, the light emitted by the third and fourth surfaces (S3, S4) can be efficiently refracted, so that the effective diameter of the first lens (111) does not increase, and the TTL can be reduced.

[0361]

[0362] The power of the third lens (113) may be positive (+) or negative (-) on the optical axis (OA), and may be positive (+), for example. The third lens (113) may include a plastic or glass material, and may be, for example, glass. On the optical axis (OA), the fifth surface (S5) on the object side of the third lens (113) may have a convex shape, and the sixth surface (S6) on the light source side may have a concave shape. The third lens (113) may have a convex shape on both sides on the optical axis (OA). At least one or both of the fifth surface (S5) and the sixth surface (S6) may be spherical. At least one or both of the fifth surface (S5) and the sixth surface (S6) may be provided without a critical point from the optical axis (OA) to the end of the effective area. Alternatively, the third lens (113) may have a meniscus shape that is convex toward the object. Alternatively, the third lens (113) may have a meniscus shape that is concave on both sides or convex toward the light source.

[0363] When the refractive index of the third lens (113) is Nd3, the condition of Nd3 > 1.7 or 2.0 > Nd3 > 1.70 can be satisfied. The first to third lenses (111, 112, 113) may all be aspherical. The first and third lenses (111, 113) may have the same refractive index. When the Abbe number of the third lens (113) is Vd3, the condition of Vd3 < Vd4 can be satisfied. In addition, the condition of Nd4 < Nd3 can be satisfied. Nd4 is the refractive index of the fourth lens (114). Vd4 is the Abbe number of the fourth lens (114).

[0364]

[0365] The power of the fourth lens (114) may have a positive (+) or negative (-) refractive power on the optical axis (OA), for example, positive. The fourth lens (114) may include a plastic or glass material, and may be provided as a glass material. The fourth lens (114) may be an injection-molded glass mold. The object-side seventh surface (S7) of the fourth lens (114) on the optical axis (OA) may have a convex shape, and the light source-side eighth surface (S8) may have a concave shape. The fourth lens (114) may have a convex meniscus shape toward the object. 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 S7 and S8 of L4 of FIG. 15. At least one of the object-side surface and the light source-side surface of the fourth lens (114) may have a free-form surface, i.e., a non-rotationally symmetrical surface. Alternatively, the fourth lens (114) may have a meniscus shape that is convex toward the light source (116) on the optical axis (OA).

[0366] The seventh and eighth surfaces (S7, S8) of the fourth lens (114) may be provided without a critical point from the optical axis (OA) 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 be a point where the sign of the gradient value with respect to the optical axis (OA) and the direction perpendicular to the optical axis (OA) changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the gradient value is 0. In addition, the critical point may be a point where the gradient value of a tangent passing through the lens surface increases and then decreases, or a point where the gradient value decreases and then increases.

[0367]

[0368] The effective diameter of the fourth lens (114) may be smaller than that of the third lens (113). The effective diameter of the third lens (113) may be the largest among the lenses. The second lens (112) may have a lower refractive index than that of the first, third, and fourth lenses (111, 113, and 114), and may have an Abbe number higher than that of the first, third, and fourth lenses (111, 113, and 114).

[0369] The power of the first lens (111) and the third and fourth lenses (113, 114) may have positive values, and the power of the second lens (112) may have negative values. The fourth lens (114) may be an aspherical lens closest to the light source (116). By means of the lens surface having an aspherical surface, aberrations such as spherical aberration and chromatic aberration can be improved.

[0370] The center thicknesses of the first to fourth lenses (111 to 114) 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 is represented by CG1 to CG3.

[0371] The first to fourth lenses (111 to 114) can satisfy the following conditions.

[0372] Condition 1: CT2 < CT1 < CT3 Condition 2: CT1 < CT4 ≤ CT3

[0373] Condition 3: (CT3-CT4) < (CT1-CT2) Condition 4: ET3 < ET1 < ET2

[0374] Condition 5: ET1 < ET2 < ET4 Condition 6: ET4 < ET2 < CT4

[0375] Condition 7: CG1 < CT1 < CG2

[0376]

[0377] The central thickness (CT3) of the third lens (113) is the largest among the lenses, and the central thickness (CT2) of the second lens (112) is the smallest among the lenses. The maximum central thickness may be 2 mm or more thicker than the minimum central thickness. In other words, by adjusting the thickness of the spherical lens and the aspherical lens, it is possible to prevent a deterioration in optical performance, and to provide a slim sensor system in terms of size or light source height.

[0378]

[0379] When explaining the center spacing between adjacent lenses, the center spacing (CG2) between the second lens (112) and the third lens (113) is the maximum, and the center spacing (CG3) between the third and fourth lenses (113, 114) is the minimum. Here, the difference between the maximum center spacing and the minimum center spacing may be 5 mm or more, for example, in the range of 5 mm to 7 mm. In addition, a transmission optical system can be provided in which the maximum center spacing between the lenses is provided to be smaller than the maximum center thickness of each lens, and the center spacing between the aspherical lens and the spherical lens is not increased. In addition, since the maximum center spacing between the lenses is provided to be larger than the minimum center thickness of each lens, the optical path can be controlled.

[0380] The effective diameter of the first and second lenses (111, 112) can be provided to be smaller than the effective diameter of the third lens (113) due to the shape of the light source-side surface of the second lens (112) and the gap between the second and third lenses (112, 113). The effective diameter of the third lens (113) can be the largest among the lenses.

[0381] The lens having the maximum effective diameter may be the third lens (113). The lens surface having the maximum effective diameter may be the sixth surface (S6) of the third lens (113). The lens having the minimum effective diameter may be the first lens (111) adjacent to the aperture (ST). The lens surface having the minimum effective diameter may be any one of the third and fourth surfaces (S3 and S4) of the second lens (112), and the eighth surface (S8) of the fourth lens (114). The effective diameter of each of the first to fourth lenses (111-114) may be greater than the diagonal length of the light source (116). The fourth lens (114) has an aspherical surface and may guide incident light to a spherical lens.

[0382]

[0383] Fig. 14 is an example of lens data of the optical system of Fig. 11. As in Fig. 4, the radius of curvature at the optical axis (OA), the center thickness (CT) of the lenses, the center spacing (CG) between the lenses, the refractive index at the d-line, the Abbe number, the effective diameter, and the focal length of the first to fourth lenses (111, 112, 113, and 114) can be set. When the focal lengths are compared in absolute values, the focal length of the fourth lens (114) is the largest among the lenses and may be 100 mm or more, and the focal length of the second lens (112) is the smallest among the lenses and may be 20 mm or less. Based on the absolute value, the focal length of the fourth lens (114) may be 5 times or more the focal length of the fourth lens (114). The absolute value of the radius of curvature of the second surface (S2) of the first lens (111) has the largest radius of curvature among the lens surfaces and may be 100 mm or more. Accordingly, the optical system may have improved MTF characteristics, aberration control characteristics, etc. in the set angle of view range, and may have good optical performance.

[0384] As shown in Fig. 15, among the lenses of the embodiment, the lens surface of the fourth lens (114) may include an aspherical surface having a conic constant (K) and a 14th-order aspherical coefficient (A to F). For example, the object-side surface and the light source-side surface of the fourth lens (114) 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).

[0385] Fig. 16 is a graph showing the diffraction MTF (Modulation Transfer Function) at low, room, and high temperatures in the optical system of Fig. 11, and is a graph showing the modulation ratio according to the spatial frequency. As in Fig. 6, in the embodiment of the invention, the deviation of the MTF at low or high temperature with respect to room temperature may be less than 10%, that is, 7% or less. Here, each MTF curve was measured from 0.000 mm to 3.940 mm in units of 0.394 mm.

[0386]

[0387] FIGS. 17 to 19 are graphs showing aberration characteristics at low, room, and high temperatures in the optical system of FIG. 11. In the aberration graphs of FIGS. 17 to 19, spherical aberration (longitudinal spherical aberration), astigmatic field curves, and distortion are measured from left to right. In FIGS. 17 to 19, the X-axis may represent a focal length (mm) and a degree of distortion (%), and the Y-axis may represent a light source height (height). In addition, the graph for spherical aberration is a graph for light in wavelength bands of about 930 nm, about 940 nm, and about 950 nm, and the graphs for astigmatism and distortion are graphs for light in wavelength bands of about 940 nm. In the aberration diagrams of Figs. 17 to 19, the closer the curves at low temperature, room temperature, and high temperature are to the Y-axis, the better the aberration correction function can be interpreted. Here, the low temperature is -20 degrees or lower, for example, in the range of -20 to -50 degrees, the room temperature is in the range of 22 degrees ± 5 degrees or in the range of 18 degrees to 27 degrees, and the high temperature can be 85 degrees or higher, for example, in the range of 85 degrees to 120 degrees. Accordingly, it can be seen that the decrease in the luminance ratio (modulation) from the low temperature to the high temperature in Figs. 17 to 19 is less than 10%, for example, 5% or lower, or is almost unchanged.

[0388]

[0389] Optical systems experience chromatic aberration, which is corrected using spaced aspherical lenses. As temperatures change from low to high, the lenses contract and expand repeatedly. Since lenses made of the same material exhibit the same degree of change in lens characteristics with temperature, it is effective to compensate for chromatic aberration between lenses made of the same material, even when temperatures change. For example, as shown in Table 1, when the temperature of the lens barrel or receiving optical system changes from -45°C (low temperature), 22°C (room temperature), and 90°C (high temperature), there is little change in optical characteristics.

[0390] Table 5 compares changes in optical characteristics such as EFL, BFL, F number (F#), TTL, and field of view (FOV) at room temperature, low temperature, and high temperature in a transmission optical system according to an embodiment, and it can be seen that the change rate of optical characteristics at low temperature is 5% or less, for example, 3% or less or 2% or less, based on room temperature, and the change rate of optical characteristics at high temperature is 5% or less, for example, 3% or less or 2% or less, based on room temperature.

[0391] Low temperature Room temperature High temperature Low temperature / Room temperature (%) High temperature / Room temperature (%) EFL15.27915.29015.30399.93%100.09% BFL6.1166.1256.13599.85%100.16% FNO1.5761.5761.576100.00%99.98% TTL37.62737.66337.70199.90%100.10% FOV28.76228.74228.722100.07%99.93%

[0392] Therefore, as shown in Table 5, it can be seen that the change in optical characteristics according to the temperature change from low temperature to high temperature, for example, the change rate of effective focal length (EFL), TTL, BFL, F number, and field of view (FOV), is 10% or less, that is, 5% or less, for example, in the range of 0 to 5%. This means that even if at least one aspherical lens is used, the design enables temperature compensation for the aspherical lens, thereby preventing a decrease in the reliability of the optical characteristics. The transmission optical system of the embodiment disclosed above can effectively control aberration characteristics such as chromatic aberration and distortion aberration, and can have good optical performance at the center and periphery of the field of view (FOV). Here, EFL is the effective focal length of the receiving optical system, BFL is the optical axis distance from the last lens, i.e., the fourth lens (104) to the surface of the light source (116), Fno is the F number of the transmitting optical system, TTL is the optical axis distance from the first lens (111) to the surface of the light source (116), and FOV is the angle of view or divergence angle of the receiving optical system.

[0393]

[0394] Referring to FIG. 20, the optical system (110) may have distortion characteristics set in comparison with the design standard (comparative example) as it goes from the 0 degree angle of view to the maximum half angle of view (Half FOV). For example, it can be seen that the embodiment of the optical system (110) further increases as the light source height increases as it goes from the 0 degree angle of view to the maximum half angle of view, and may have distortion characteristics that are satisfactory compared to other examples of mapping such as Stereographic, equidistance, rectilinear, and Equisolid. In detail, the embodiment may satisfy the distortion characteristics in comparison with the Comparative Example 1. Here, the half angle of view is half of the angle of view, and may be set to an angle of up to about 16 degrees with respect to the optical axis of 0 degrees.

[0395] In addition, the receiving optical system (110) may have a distortion characteristic set compared to other examples as it goes from a 0 degree field of view to a maximum half-angle of view, thereby providing an optical system that satisfies the orthographic projection type. Here, the ratio for the distortion characteristic may mean the value of the light source height at a specific half-angle position, calculated as ((Other example - embodiment) / embodiment * 100). Accordingly, the optical system according to the embodiment may prevent the optical characteristics from changing according to temperature change in a temperature range from a low temperature (-40 degrees) to a high temperature (120 degrees) based on the Equal Area mapping method, and may have improved optical performance in various temperature ranges.

[0396] According to an embodiment of the invention, a transmission optical system can prevent degradation of optical performance from low to high temperatures by considering the characteristics of a vehicle optical system. For example, after designing a lens at room temperature, the value of the dn / dt, which is a temperature-dependent refractive index change coefficient, is assembled by 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 2.5 μm or less. For this purpose, the first to third lenses (111, 112, and 113) are made of a spherical glass material, and the fourth lens (114) is made of an aspherical glass material.

[0397]

[0398] The transmission optical system (110) 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 (110) according to the embodiment can have improved optical characteristics. For example, when the optical system (110) satisfies at least one mathematical equation, the optical system (110) can effectively control aberration characteristics such as chromatic aberration and distortion aberration. In addition, the optical system (110) can have improved resolution. In addition, the thickness of the lens on the optical axis (OA) described in the mathematical equations and the spacing between adjacent lenses on the optical axis (OA) can refer to the embodiment disclosed above.

[0399] [Mathematical Formula 1] 1 < CT1 / CT2 < 3

[0400] CT1 is the central thickness of the first lens (111), and CT2 is the central thickness of the second lens. By setting the central thickness (CT1) of the first lens (111) and the central thickness (CT2) of the second lens (112) in mathematical expression 1, it is possible to prevent a decrease in the rigidity of the first lens (111) and control factors affecting aberration. Preferably, mathematical expression 1 can satisfy 1.5 < CT1 / CT2 < 2.2.

[0401] [Equation 2] 0.5 < CT4 / CT3 < 1.5

[0402] CT3 and CT4 are the central thicknesses of the third and fourth lenses (113 and 114). By setting the central thicknesses of the third and fourth lenses (113 and 114) in Equation 2, it is possible to prevent the rigidity and optical characteristics of the glass lens from deteriorating, and to control factors affecting aberration. Preferably, CT4 ≤ CT3 can be satisfied.

[0403] [Mathematical Formula 3] 1 < CT3 / CT2 < 4

[0404] In mathematical expression 3, the central thicknesses of the second and third (112, 113) can be set, thereby optimizing thermal compensation according to temperature changes from low to high temperatures and preventing degradation of optical performance. Preferably, mathematical expression 3 can satisfy 2.5 < CT3 / CT2 < 3.5.

[0405] [Equation 4] 1 < CG2 / CT2 < 4

[0406] CG2 is the center spacing between the second and third lenses (112, 113). In mathematical expression 4, by setting the center spacing between the second and third lenses (112, 113) to the above range, light refracted through the aspherical fourth lens (114) can be guided along the spacing between the second and third lenses (112, 113). Preferably, mathematical expression 4 can satisfy 2 < CG2 / CT2 < 3.

[0407] [Equation 5] 0.5 < CT3 / (CT1+CT2) < 1.5

[0408] In mathematical expression 5, the central thickness between the first, second, and third lenses (111, 112, and 113) can be set. Preferably, mathematical expression 5 can satisfy 0.8 < CT3 / (CT1+CT2) < 1.2.

[0409]

[0410] [Equation 6] 2 < CG2 / CG1 < 5

[0411] CG1 is the center spacing between the first and second lenses (111, 112). In Equation 6, the center spacing (CG1) between the first and second lenses (111, 112) is set to be smaller than the center spacing (CG2) between the second and third lenses (112, 113), thereby preventing an increase in the effective diameter of the first lens (111). In addition, the center spacing between the spherical lenses can be set by Equation 6. Preferably, 3 < CG1 / CG2 < 4.6 can be satisfied.

[0412] [Equation 7] 5 < CG2 / CG3 < 20

[0413] In mathematical expression 7, the center spacing (CG2) between the second and third lenses (112, 113) is set to be greater than the center spacing (CG3) between the third and fourth lenses (113, 114), so that the center spacing between the spherical lens and the aspherical lens can be reduced compared to the center spacing between the spherical lenses. Preferably, 5 < CG2 / CG3 < 10 can be satisfied.

[0414] [Equation 8] 0.5 < CT3 / (CT1+CG1+CT2) < 1.5

[0415] In mathematical expression 8, the central thickness (CT3) of the third lens (113) can be set to be smaller than the optical axis distance between the object-side surface of the first lens (111) and the light source-side surface of the second lens (112). Preferably, mathematical expression 8 can satisfy 0.6 < CT3 / (CT1+CG1+CT2) < 1.

[0416]

[0417] [Equation 9] 0.5 < SD / TTL < 1.5

[0418] SD is the optical axis distance from the aperture (ST) to the surface of the light source (116), and TTL is the optical axis distance from the object-side surface of the first lens to the surface of the light source. Preferably, 0.8 < SD / TTL < 1.2 can be satisfied. When the optical system satisfies mathematical expression 9, the aperture (ST) can be positioned at the farthest position from the light source (116), that is, closer to the object than the first lens (111), thereby controlling the amount of light emitted.

[0419] [Equation 10] 1.70 < Nd1

[0420] Nd1 is the refractive index at the d-line of the first lens (111). In Equation 10, by setting the refractive index of the first lens (111) 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 aberration can be obtained, and the refractive power of the first lens may be weakened so that light cannot be collected efficiently, which may deteriorate 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 becomes difficult to obtain materials. In addition, if the refractive index of the first lens (111) is designed to be lower than the lower limit of Equation 4, the radius of curvature of the first and second lenses may be increased in order to increase the refractive power of the first and second lenses.

[0421] [Equation 11] 0.5 < Nd1 / Nd3 < 1.5

[0422] Nd1 and Nd3 are the refractive indices of the first and third lenses (111 and 113) at the d-line. In Equation 11, the difference in the refractive index of the first lens (111) and the refractive index of the third lens (113) can be reduced, thereby preventing the reduction in color dispersion caused by lenses made of glass. Preferably, the refractive indices of the first, second, and third lenses can be the same.

[0423] [Equation 12] 1 < Nd1 / Nd4 < 1.5

[0424] Nd1 and Nd4 are the refractive indices of the first and fourth lenses (111 and 114) at the d-line. In Equation 12, by setting the refractive index of the first lens (111) higher than the refractive index of the fourth lens (114), the color dispersion by the lenses made of spherical materials and the color dispersion by the aspherical lenses can be controlled. Preferably, Equation 12 can satisfy 1 < Nd1 / Nd4 < 1.2.

[0425] [Equation 13] (Vd3*Nd3) < (Vd4*Nd4)

[0426] Nd3 and Nd4 are the refractive indices of the 3rd and 4th lenses (113 and 114) at the d-line, and Vd3 and Vd4 are the Abbe numbers of the 1st and 4th lenses. In mathematical expression 13, by setting the product of the refractive index and Abbe number of the 1st lens (111) to be smaller than the product of the refractive index and Abbe number of the 4th lens (114), the color dispersion by the spherical material lenses and the color dispersion by the aspherical lenses can be controlled.

[0427]

[0428] [Equation 14] TD < SD

[0429] SD is the optical axis distance from the aperture (ST) to the surface of the light source (116), and TD is the optical axis distance from the object-side surface of the first lens (111) to the light source-side surface of the fourth lens (114). When the optical system satisfies mathematical expression 14, the aperture (ST) may be located on the object side relative to the first lens (111).

[0430] [Equation 14-1] TTL < SD

[0431] 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 (111).

[0432] [Equation 15] 1 < CA42 < CT4 < 3

[0433] CA42 is the effective diameter of the light source side of the fourth lens (1140), and CT4 is the central thickness of the fourth lens. If mathematical expression 15 is satisfied, the effective diameter of the last lens can be set not to be large compared to the central thickness. Preferably, 1.2 < CA42 < CT4 < 2 can be satisfied.

[0434] [Mathematical Formula 16] 1 < CA3 / CA2 < 3

[0435] CA2 and CA3 are the effective diameters of the second and third lenses. CA2 and CA3 are the average of the effective diameters of the object-side and sensor-side surfaces of the second and third lenses. If mathematical expression 16 is satisfied, a lens with a maximum effective diameter and a lens with a minimum effective diameter can be set. Preferably, 1.3 < CA3 / CA2 < 2.3 can be satisfied.

[0436] [Mathematical Formula 17] 0.5 < CA1 < CA2 < 1.5

[0437] CA1 is the effective diameter of the first lens. That is, CA1 is the average of the effective diameters of the object-side surface and the light source-side surface of the first lens. In mathematical expression 17, the effective diameters of the two output-side lenses or the output-side spherical lenses can be set. Preferably, 0.8 < CA1 < CA2 < 1.2 can be satisfied.

[0438] [Mathematical Formula 18] 1 < CA3 / CA4 < 2

[0439] CA3 and CA4 denote the effective diameters of the third and fourth lenses (113 and 114). In mathematical expression 18, the effective diameters of the two lenses on the light source side or the spherical lens and aspherical lens arranged adjacently can be set. When mathematical expression 18 is satisfied, the emission efficiency of the light emitted from the light source (116) can be improved, and preferably, 1.2 < CA3 / CA4 < 1.6 can be satisfied.

[0440] [Mathematical Formula 19] 1 < CA32 / CA21 < 3

[0441] CA32 refers to the effective diameter of the sixth surface (S6) of the third lens (113), and CA21 refers to the effective diameter of the third surface (S3) of the second lens (112). When mathematical expression 19 is satisfied, the optical system (110) can control the light path emitted from the light source (116), and can set the light source-side surface of the second lens (112) to a concave shape. Preferably, mathematical expression 19 can satisfy 1.5 < CA32 / CA21 < 2.

[0442]

[0443] [Equation 20] 0.5 < CA11 / ST_CA < 1.5

[0444] CA11 denotes the effective diameter of the first surface (S1) of the first lens (111), and ST_CA denotes the effective diameter of the hole of the aperture (ST). When mathematical expression 20 is satisfied, the optical system (110) can set a light path that is emitted toward the aperture (ST) through the first lens (111). Mathematical expression 20 can preferably satisfy 1 < CA11 / ST_CA < 1.3.

[0445]

[0446] [Equation 21] 2 < CA11 / CG0 < 8

[0447] CG0 is the optical axis distance between the first lens (111) and the aperture (ST) or diffuser (119). When the optical system (110) satisfies mathematical expression 21, the effective diameter and radius of curvature of the first lens (111) can be adjusted. Mathematical expression 21 can preferably satisfy 4 < CA11 / CG0 < 7.5.

[0448] [Equation 22] 0 < CG0 / CT1 < 1

[0449] When the optical system satisfies mathematical expression 22, the optical axis distance between the first lens (111) and the aperture (ST) or diffuser (119) and the central thickness of the first lens (111) can be set, and distortion aberration can be controlled. Preferably, 0 < CG0 / CT1 < 0.5 can be satisfied.

[0450] [Equation 23] 0 < ST_CA / CA_Max < 1

[0451] CA_Max represents the largest 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, 0.3 < ST_CA / CA_Max < 0.8 can be satisfied.

[0452] [Equation 24] 1 < CG_Max / CG0 < 4

[0453] CG_Max refers to the maximum center spacing between lenses in the optical system. When the optical system satisfies mathematical expression 24, the maximum center spacing between lenses can set the relationship between the optical axis spacing between the first lens (111) and the aperture (ST) or diffuser (119), thereby controlling the overall optical axis length and suppressing an increase in the effective diameter of the first lens (111). Preferably, mathematical expression 24 can satisfy 3.4 < CG_Max / CG0 < 4 or 3.4 < CG2 / CG0 < 4.

[0454] [Equation 25] 0.5 < CT4 / BFL < 1.5

[0455] BFL is the optical axis distance from the center of the light source side surface of the fourth lens (114) to the light source (116). That is, BFL is the optical axis distance from the center of the eighth surface (S8) of the fourth lens (114) to the light source (116). 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 (114). Preferably, 0.8 < CT4 / BFL < 1.3 can be satisfied.

[0456] [Equation 26] 2 < BFL / CG0 < 6

[0457] Mathematical expression 26 can set the distance (CG0) between the first lens and the aperture, and the distance (BFL) between the fourth lens (114) and the light source. When mathematical expression 26 is satisfied, the distance between the object-side configuration and the light-source-side configuration of the lens unit can be adjusted. Preferably, 3 < BFL / CG0 < 5 can be satisfied.

[0458] [Equation 27] 2 < ST_CA / CG0 < 8

[0459] When the optical system satisfies mathematical expression 27, the position of the diffuser (119) can be set, and due to the diffuser (119), the transmitting optical system and the receiving optical system can be optically matched even if they provide different aspect ratios. Preferably, 5 < ST_CA / CG0 < 7 can be satisfied.

[0460]

[0461] [Equation 28] 1 < L4R2 / CT4 < 5

[0462] 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 (114) can be controlled and optical performance can be improved. Preferably, 1 < L4R2 / CT4 < 2 can be satisfied.

[0463] [Equation 29] 0.5 < L4R2 / L4R1 < 1.5

[0464] 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 (114) can be controlled and optical performance can be improved. Preferably, 0.5 < L4R2 / L4R1 < 1 can be satisfied.

[0465] [Equation 30] 0 < L1R1 / |L1R2| < 1

[0466] 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 (111) can be controlled and the optical performance can be improved. Preferably, 0 < L1R1 / |L1R2| < 0.5 is satisfied, and in this case, the distance between the first lens (111) and the aperture (ST) or diffuser (119) can be set.

[0467] [Equation 31] L1R2 < 0

[0468] The light source side of the first lens (111) may have a shape that is blocked toward the light source and may have a radius of curvature of 100 mm or more. Accordingly, the amount of change in light incident on the first lens (111) may be reduced. L1R1 may be > 0.

[0469] [Equation 32] 1 < |L2R1 / L2R2| < 3

[0470] 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 (112) can be controlled to improve optical performance, and the incidence efficiency through the light source-side surface of the second lens (112) can be improved. Preferably, 1 < |L2R1 / L2R2| < 2 is satisfied, and L2R1 < 0 and L2R2 > 0 can be satisfied.

[0471] [Equation 33] |L3R2| < L3R1

[0472] 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 33 is satisfied, the refractive power of the third lens (113) can be controlled and the optical performance can be improved, and the effective diameters of the first and second lenses can be reduced by the radius of curvature of the third lens (113) and the gap between the second and third lenses. Preferably, L3R1 > 0 and L3R2 < 0 can be satisfied.

[0473]

[0474] [Equation 34] 0 < CT_Max / CG_Max < 2

[0475] In Equation 34, the maximum central thickness (CT_Max) among the lenses and the maximum gap (CT_Max) between adjacent lenses can be set. When Equation 34 is satisfied, the optical system can have good optical performance at the focal length of the set angle of view and can reduce the TTL. Preferably, 1 < CT_Max / CG_Max < 1.5 can be satisfied.

[0476] [Equation 35] 1 < ΣCT / ΣCG < 4

[0477] 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 35 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, 2 < ΣCT / ΣCG < 3 can be satisfied.

[0478]

[0479] [Equation 36] 5 < ΣNd < 10

[0480] ΣNd represents the sum of the refractive indices at the d-line of each of the plurality of lenses. If mathematical expression 34 is satisfied, TTL can be controlled in an optical system (110) in which aspherical lenses and spherical lenses are mixed. In addition, if the number of spherical lenses is greater than the number of aspherical lenses, the sum of TTL and refractive indices can be set.

[0481] [Equation 37] 10 < ΣVd / ΣNd < 50

[0482] ΣVd means the sum of the Abbe numbers of each of the plurality of lenses. When mathematical expression 37 is satisfied, the optical system (110) 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 37, the optical characteristics can be controlled, and preferably, 15 < ΣVd / ΣNd < 27 can be satisfied.

[0483] [Equation 38] 50 < ΣCT*n < 100

[0484] ΣCT is the sum of the central thicknesses of multiple lenses, and n is the number of lenses in the optical system. If mathematical expression 38 is satisfied, TTL can be controlled. Preferably, 70 < ΣCT*n < 95 can be satisfied. Here, n is 4.

[0485] [Equation 39] CT2 < ET2

[0486] ET2 is the edge thickness of the second lens. When mathematical expression 39 is satisfied, light incident on the second lens can be refracted in the direction of the optical axis, thereby suppressing an increase in the effective diameter of the first lens.

[0487] [Mathematical Formula 40] 8mm < CA11 < 15mm

[0488] CA11 is the effective diameter of the object-side first surface (S1) of the first lens. If mathematical expression 40 is satisfied, the optical system can increase the output light. Mathematical expression 38 preferably satisfies 8 mm < CA11 < 13 mm.

[0489]

[0490] [Equation 41] 1 < Fno < 2

[0491] F# is the F number of the optical system. If mathematical expression 41 is satisfied, a bright image can be provided.

[0492] [Equation 42] 2 < CA_Max / (2*LsH) < 6

[0493] Mathematical expression 42 can be set by the maximum effective diameter (CA_Max) and the diagonal length of the light source. If this is satisfied, the optical system can maintain good optical performance and a slim and compact sensor device can be set. Mathematical expression 42 preferably satisfies 2 < CA_max / (2*LsH) < 3.

[0494] [Equation 43] 0 < F / L4R2 < 3

[0495] 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 Equation 43 is satisfied, the effect on optical system reduction, such as TTL, can be controlled by setting the effective focal length and the radius of curvature of the light source-side surface of the last aspherical lens. Equation 43 can preferably satisfy 1 < F / L4R2 < 3.

[0496] [Equation 44] 0 < F / L1R1 < 2

[0497] 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 0.5 < F / L1R1 < 1.

[0498] [Equation 45] 0 < EPD / L4R2 < 2

[0499] EPD refers to the size of the entrance pupil of the optical system (110). When the optical system (110) according to the embodiment satisfies mathematical expression 45, the optical system (110) can control the emitted light. Preferably, the condition of 0.5 < EPD / L4R2 < 1.5 can be satisfied.

[0500] [Equation 46] 0 < EPD / L1R1 < 1

[0501] In mathematical expression 46, the size of the entrance pupil of the optical system (110) 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 (110) can control the emitted light. Preferably, the condition of 0.3 < EPD / L1R1 < 0.8 can be satisfied.

[0502]

[0503] [Mathematical Formula 47] 1 < |F1 / F2| < 3

[0504] F1 is the focal length of the first lens, and F2 is the focal length of the second lens. When mathematical expression 47 is satisfied, the refractive power of the first and second lenses can be controlled, and the TTL and effective focal length (EFL) can be influenced. Preferably, 1 < |F1 / F2| < 2 can be satisfied. The first and second lenses (111, 112) have powers of opposite signs, so that aberrations can be corrected.

[0505] [Equation 48] 2 < F1 / F < 10

[0506] In mathematical expression 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.

[0507] [Equation 49] 2 < F4 / F1 < 10

[0508] In mathematical expression 49, the focal lengths of the first and fourth lenses can be set, and the refractive powers of the first and fourth lenses can be controlled. Preferably, 3 < F4 / F1 < 9 can be satisfied.

[0509] [Equation 50] F2 < 0

[0510] F2 is the focal length of the second lens, which has a negative value. The second lens can improve chromatic aberration caused by the third and fourth lenses.

[0511]

[0512] [Mathematical Formula 51] 20 mm < TTL < 60 mm

[0513] TTL (Total track length) means the distance from the center of the first surface (S1) of the first lens (111) to the upper surface of the light source (116) on the optical axis (OA). By setting the TTL in the above range in mathematical expression 51, a vehicle optical system can be provided. Mathematical expression 51 can preferably satisfy 25 mm < TTL < 55 mm. In addition, the TTL of the transmitting optical system may be smaller than the TTL of the receiving optical system. 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.

[0514] [Mathematical Formula 52] 2 mm < LsH < 10 mm

[0515] LsH is half the diagonal length of the light source. Mathematical expression 52 can set the diagonal length of the light source (116) and provide an optical system having a vehicle sensor size. Mathematical expression 52 can preferably satisfy 2 mm < LsH < 5 mm.

[0516] [Mathematical Formula 53] 1.5 mm < BFL < 9 mm

[0517] In mathematical expression 53, the BFL (Back focal length) is set to be greater than 1.5 mm and less than 9 mm, thereby improving the assemblability of components and improving the joint reliability through the gap between the light source (116) and the last lens. Mathematical expression 53 can preferably satisfy 5 mm < BFL < 7 mm. When 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. When the BFL exceeds the range of mathematical expression 53, stray light may be emitted, which may deteriorate the aberration characteristics of the optical system.

[0518] [Mathematical Formula 54] 5 mm < F < 30 mm

[0519] Mathematical expression 54 can set the overall focal length (F) to suit the vehicle transmitting optical system. Mathematical expression 54 can satisfy 10 mm < F < 20 mm, and can be greater than the overall focal length of the receiving optical system.

[0520]

[0521] [Mathematical Formula 55] FOV < 70 degrees

[0522] In mathematical expression 55, FOV (Field of view) means the angle of view (Degree) of the optical system (110), and a vehicle optical system having an angle of view (F0V) of less than 70 degrees can be provided. The FOV can preferably satisfy 20 ≤ FOV ≤ 50. The angle of view of the 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 (119), the sensitivity of the sensing unit can be prevented from decreasing. In mathematical expression 55, the range of the vehicle optical system can be set by the angle of view. When mathematical expression 55 is satisfied, when the temperature changes from room temperature to high temperature, the change rate of the effective focal length and the change rate of the angle of view can be set to 5% or less, for example, 0 to 5%. In addition, even if an aspherical lens is used in combination with a spherical lens within the optical system (110), the deterioration of optical characteristics can be prevented through temperature compensation and aberration correction by the aspherical lens made of glass.

[0523]

[0524] [Equation 56] 1 < TTL / CA_Max < 7

[0525] Mathematical expression 56 establishes a relationship between the total optical axis length of the optical system and the maximum effective diameter, thereby providing an improved vehicle optical system. Mathematical expression 56 preferably satisfies 1 < TTL / CA_Max < 3.

[0526] [Mathematical Formula 57] 5 < TTL / LsH < 15

[0527] Mathematical expression 57 can set the total optical axis length (TTL) of the optical system and the diagonal length from the center of the light source (116). When the optical system (110) according to the embodiment satisfies Mathematical expression 57, the optical system (110) can have TTL for application to the vehicle light source (116), thereby providing improved image quality. Mathematical expression 57 can preferably satisfy 6 < TTL / LsH < 11.

[0528] [Equation 58] 0 < BFL / LsH < 3

[0529] Mathematical expression 58 can set the optical axis distance between the light source (116) and the fourth lens (114) and the length in the diagonal direction from the optical axis of the light source (116). When the optical system (110) according to the embodiment satisfies Mathematical expression 58, the optical system (110) can secure BFL for applying the size of the vehicle light source (116), can set the distance between the fourth lens (114) and the light source (116), and can have good optical characteristics in the field of view (FOV). Mathematical expression 58 can preferably satisfy 1 < BFL / LsH < 2.

[0530]

[0531] [Equation 59] 1 < TTL / BFL < 15

[0532] 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 (116) and the last lens. When the optical system (110) according to the embodiment satisfies Mathematical expression 59, the optical system (110) can secure BFL. Mathematical expression 59 can preferably satisfy 3 < TTL / BFL < 10.

[0533] [Equation 60] 1 < TTL / F < 10

[0534] Mathematical expression 60 can set the total focal length (F) and the total optical axis length (TTL) of the optical system (110). Accordingly, an optical system for a driver assistance system can be provided. Mathematical expression 60 can preferably satisfy 1 < TTL / F < 5. When the optical system (110) according to the embodiment satisfies Mathematical expression 60, the optical system (110) 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 becomes long, which may cause a problem of the imaging lens system becoming large.

[0535] [Equation 61] 1 < F / BFL < 4

[0536] Mathematical expression 61 can set the total focal length (F) of the optical system (110) and the optical axis distance between the light source (116) and the last lens. When the optical system (110) according to the embodiment satisfies Mathematical expression 61, the optical system (110) 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 (110) can minimize the distance between the last lens and the light source (116), and thus can have good optical characteristics in the angle of view (FOV). Mathematical expression 61 can preferably satisfy 2 < F / BFL < 3.

[0537] [Equation 62] 1 < F / LsH < 5

[0538] Mathematical expression 62 can set the total focal length (F) of the optical system (110) and the diagonal length from the optical axis of the light source (116). This optical system (110) can have improved aberration characteristics in the size of the vehicle light source (116). Mathematical expression 62 can preferably satisfy 3 < F / LsH < 4.5.

[0539] [Equation 63] 1 < F / EPD < 3

[0540] Mathematical expression 63 can set the overall focal length (F) and entrance pupil size of the optical system (110). Accordingly, the overall brightness of the optical system can be controlled. Mathematical expression 63 preferably satisfies 1.2 < F / EPD < 2.

[0541] [Equation 64] 0 < EPD / LsH / FOV < 0.2

[0542] Mathematical expression 64 can set the relationship between the entrance pupil size (EPD), the length of half the diagonal length of the light source, and the field of view. Accordingly, the overall size and brightness of the optical system can be controlled. Mathematical expression 64 can preferably satisfy 0 < EPD / LsH / FOV < 0.1.

[0543] [Equation 65] 10 < FOV / F# < 30

[0544] Mathematical expression 65 can establish the relationship between the angle of view and the F number (F#) of an optical system. Mathematical expression 65 can preferably satisfy 15 < FOV / F# < 25.

[0545] [Equation 66] 20 < (CT_Max+CG_Max)*n < 80

[0546] [Mathematical Formula 67] 200 < (FOV*TTL) / n < 500

[0547] Preferably, mathematical expression 67 can satisfy the condition of 200 < (FOV*TTL) / n < 300 depending on the angle of view and the number of lenses (n). Here, n is 4.

[0548] [Mathematical Formula 68] FOV < TTL

[0549] [Equation 69] 1 < (TD / CA_Max)*n < 20

[0550] Preferably, 1 < (TD / CA_Max)*n < 10 can be satisfied.

[0551]

[0552] The transmission optical system (110) according to the embodiment can satisfy at least one or two or more mathematical equations from mathematical equations 1 to 69. In this case, the optical system (110) can have improved optical characteristics. Specifically, when the optical system (110) satisfies at least one of mathematical equations 1 to 35 and / or at least one of mathematical equations 36 to 69, the optical system (110) can have improved resolution and improve aberration and distortion characteristics. In addition, the optical system (110) can secure a BFL (Back focal length) for applying a vehicle light source (116), can compensate for optical characteristic degradation due to temperature change, and can minimize the distance between the last lens and the light source (116), thereby having good optical performance within the field of view (FOV).

[0553]

[0554] Table 6 shows the items of the mathematical formulas described above in the optical system (110) of the embodiment, including the TTL (Total track length) (mm), BFL (Back focal length), 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), focal lengths (F1, F2, F3, F4), angle of view (FOV), edge thickness (ET), F number, etc. of each of the first to fourth lenses.

[0555] Item ValueItem ValueF15.290ET13.500F121.487ET24.803F2-12.756ET33.398F315.471ET45.581F4135.479FOV29.59ΣNd6.894E PD9.700ΣVd164.860BFL6.637ΣCT20.800TD37.664ΣCG8.227LsH3.940ΣET17.282SD37.264TTL35.664F-number1.576

[0556] Table 7 shows the result values ​​for the mathematical expressions 1 to 35 described above in the transmission optical system (110) of the embodiment. Referring to Table 7, it can be seen that the optical system (110) satisfies at least one, two or more, or three or more of the mathematical expressions 1 to 35. In detail, it can be seen that the optical system (110) according to the embodiment satisfies all of the mathematical expressions 1 to 35. Accordingly, the optical system (110) can have good optical performance within the field of view (FOV) and can have excellent optical characteristics.

[0557] Equation value 11 < CT1 / CT2 < 31.73120.5 < CT4 / CT3 < 1.50.99631 < CT3 / CT2 < 42.80041 < CG2 / CT2 < 42.40250.5 < CT3 / (CT1+CT2) < 1.51.02562 < CG2 / CG1 < 54.22575 < CG2 / CG3 < 207.50780.5 < CT3 / (CT1+CG1+CT2) < 10.84890.5 < SD / TTL < 1.50.957101.70 < Nd11.847110.5 < Nd1 / Nd3 <1.51.000121 < Nd1 / Nd4 <1.51.09713(Vd3*Nd3) < (Vd4*Nd4)Satisfied14TD < SDSatisfied151 < CA42 / CT4 < 31.519161 < CA3 / CA2 < 31.657170.5 < CA1 / CA2 < 1.50.985181 < CA3 / CA4 < 21.356191 < CA32 / CA21 < 31.757200.5 < CA11 / ST_CA < 1.51.097213 < CA11 / CG0 < 86.652220 < CG0 / CT1 < 10.370230 < ST_CA / CA_Max < 10.530241 < CG_Max / CG0 < 43.753250.5 < CT4 / BFL < 1.51.050262 < BFL / CG0 < 64.148272 < ST_CA / CG0 < 86.063281 < L4R2 / CT4 < 51.290290.5 < L4R2 / L4R1 < 1.50.836300 < L1R1 / |L1R2| < 10.14531L1R2 < 0Satisfied321 < |L2R1 / L2R2| < 31.53133|L3R2| < L3R1Satisfied340 < CT_Max / CG_Max < 21.166351 < ² / ∑?CG < 42.528

[0558] Table 8 shows the result values ​​for the mathematical expressions 36 to 69 described above in the optical system (110) of the embodiment. Referring to Table 8, it can be seen that the optical system (110) satisfies at least one, two or more, or three or more of the mathematical expressions 36 to 69. In detail, it can be seen that the optical system (110) according to the embodiment satisfies all of the mathematical expressions 1 to 69. Accordingly, the optical system (110) can have good optical performance within the field of view (FOV) and can have excellent optical characteristics.

[0559] Mathematical expression value 365 < ?lt;106.8943710 < ² / ∑?Nd <5023.9153850 < ?lt; 10083.20039CT2 < ET2 Satisfaction 408 < CA11 < 1510.643411 < F# < 21.580421 < CA_Max / (2*LsH) < 62.322430 < F / L4R2 < 31.701440 < F / L1R1 < 20.771450 < EPD / L4R2< 21.079460 < EPD / L1R1 < 10.489471 < |F1 / F2| < 31.685481 < F1 / F < 101.405492 < F4 / F1 < 106.30550F2 < 0 Satisfaction 5120 < TTL <6035.664522 < LsH <103.940531.5 < BFL < 96.637545 < F < 3015.29055FOV < 7029.590561 < TTL / CA_Max < 71.949575 < TTL / LsH < 159.052580 < BFL / LsH < 31.685591 < TTL / BFL < 155.374601 < TTL / F < 102.332611 < F / BFL < 42.304621 < F / LsH < 53.881631 < F / EPD < 31.576640 < EPD / LsH / FOV < 0.20.0836510 < FOV / F# <3018.7786620 < (CT_Max+CG_Max)*n < 8052.02267200 < (FOV*TTL) / n < 500263.82368FOV < TTL satisfaction 691 < (TD / CA_Max) *n < 208.233

[0560] The pixel-by-pixel matching results according to the transmitting and receiving optical systems of the invention are as shown in FIGS. 22 and 23. FIG. 22 is a graph showing the pixel-by-pixel matching results according to the light source height and divergence angle of the transmitting optical system, and it can be seen that as the divergence angle increases as the light source height increases from the center (0.0) to the end, i.e., 3.8 mm, the pixel-by-pixel matching increases. FIG. 23 is a graph showing the pixel-by-pixel matching results according to the image height and field of view in the receiving optical system according to an embodiment of the invention, and it can be seen that as the field of view increases as the sensor height increases from the center (0.0) to the end, i.e., 3.2 mm, the pixel-by-pixel matching increases. Therefore, the matching efficiency of the transmitting and receiving optical systems in linear lidar can be provided at 95% or more.

[0561]

[0562] Fig. 24 is a drawing showing an example of measuring an object in a vehicle having the sensor system of the invention, and Fig. 25 is a drawing showing an example of surrounding surveillance in a vehicle having the sensor system of the invention.

[0563] Referring to FIGS. 24 and 25, a vehicle (202) having a sensor system includes a transmitting optical system that projects a laser beam (201) generated by a light source toward a target scene, and 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 (210) from the reflected light, and an element that can scan or provide a specific pattern of light, which may be a static pattern, within a desired range and field of view (FOV). The transmitting 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 FOV of the lidar system.

[0564] 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.

[0565] 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 long range requirement. Typically, the sensor functions of a vehicle may be enabled by a combination of LIDAR, radar, cameras, and ultrasonic sensors. The combination of these sensor data to generate information about the surrounding environment is often referred to as "sensor fusion." The LIDAR may include a linear scan type.

[0566] While the present invention describes a LIDAR system in the context of an automobile, where LIDAR is widely used for autonomous, self-driving, or driver-assisted vehicles, it should be understood that the embodiments can be applied to any vehicle. Other types of vehicles include robots, tractors, trucks, airplanes, drones, boats, and ships.

[0567]

[0568] 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. exemplified in each embodiment can be combined or modified in other embodiments by those skilled in the art to which the embodiments pertain. Therefore, the contents related to such combinations and modifications should be construed as falling within the scope of the present invention.

[0569] In addition, although the above description focuses on examples, these are merely examples and do not limit the present invention. Those skilled in the art to which the present invention pertains will appreciate that various modifications and applications not exemplified above are possible without departing from the essential characteristics of the present invention. For example, each component specifically shown in the examples can be modified and implemented. In addition, differences related to such modifications and applications should be interpreted as being included within the scope of the present invention defined in the appended claims.

Claims

1. First to fifth lenses aligned along the optical axis from the object toward the sensing unit; and An optical filter disposed in any one of the regions between the second lens to the fifth lens, On the optical axis, the first lens has a convex meniscus shape toward the object, The object-side surface of the third lens on the optical axis has a concave shape, The radius of curvature of the object-side surface of the first lens on the optical axis is L1R1. The radius of curvature of the sensor-side surface of the first lens on the optical axis is L1R2. Mathematical Formula: 1 < L1R1 / L1R2 < 5 An optical system that satisfies .

2. In paragraph 1, An optical system, wherein the object-side surface of the second lens on the optical axis has a convex shape.

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

4. In paragraph 1, An optical system in which the sensor-side surface of the fifth lens on the optical axis has a convex shape.

5. In any one of paragraphs 1 to 4, An optical system, wherein among the absolute values ​​of the radii of curvature of the object-side and sensor-side surfaces of the first to fifth lenses, the radius of curvature of the sensor-side surface of the fifth lens is the largest.

6. In any one of paragraphs 1 to 4, An optical system wherein the optical filter is positioned between two lenses among the first to fifth lenses, the central thickness of which is thicker than that of the other lenses.

7. In any one of paragraphs 1 to 4, An optical system wherein the optical filter is positioned between the third lens and the fourth lens.

8. In any one of paragraphs 1 to 4, The optical axis distance from the optical filter to the surface of the sensing unit is DF2, The optical axis distance from the sensor side of the fifth lens to the surface of the sensing unit is BFL. Mathematical Formula: BFL < DF2 An optical system that satisfies .

9. In paragraph 7, It includes an aperture arranged around the object-side surface of the optical filter or the sensor-side surface of the third lens, The optical axis distance from the above aperture to the surface of the sensing part is SD, Mathematical Formula: 1 < SD / DF2 < 1.2 An optical system that satisfies .

10. In paragraph 7, The optical axis distance from the center of the object-side surface of the first lens to the optical filter is DF1. Mathematical Formula: DF2 < DF1 An optical system that satisfies .

11. In any of paragraphs 1 to 4, An optical system wherein the first to fifth lenses are made of glass.

12. In any of paragraphs 1 to 4, An optical system in which the object-side surface and the sensor-side surface of the second and fifth lenses are aspherical.

13. In any one of paragraphs 1 to 4, The above optical filter is a band pass filter that passes the range of 890 nm to 960 nm, An optical system in which the center spacing between the object-side lens and the sensor-side lens of the optical filter is the largest among the center spacings between the first to fifth lenses.

14. In any one of paragraphs 1 to 4, The above first and second lenses have negative refractive power, An optical system wherein the third to fifth lenses have positive refractive power.

15. In any one of paragraphs 1 to 4, The center spacing between the above 3rd and 4th lenses is CG3. The thickness of the above optical filter is OFt, Mathematical Formula: 2 < CG3 / OFt < 15 An optical system that satisfies .

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