KR20230037397A - Optical system and camera module including the same - Google Patents

Abstract

An optical system disclosed in an embodiment of the present invention includes first to fourth lenses disposed along an optical axis in a direction from an object side to a sensor side, wherein the second lens has negative refractive power on the optical axis, the third lens has positive refractive power on the optical axis, and the second and third lenses may satisfy the following equation. The equation is as follows: 5 < L2_CT / d23_CT < 5.6 (wherein L2_CT means the thickness of the second lens on the optical axis, and d23_CT is a distance between the second and third lenses on the optical axis). Embodiments are intended to provide the optical system and the camera module with improved optical characteristics.

Description

Optical system and camera module including the same {OPTICAL SYSTEM AND CAMERA MODULE INCLUDING THE SAME}

The embodiment relates to an optical system having improved optical performance and a camera module including the same.

ADAS (Advanced Driving Assistance System) is an advanced driver assistance system for assisting the driver in driving. It senses the situation ahead, determines the situation based on the sensed result, and controls the vehicle behavior based on the situation judgment consists of For example, an ADAS sensor device detects a vehicle ahead and recognizes a lane. Then, when the target lane, target speed, and forward target are determined, the vehicle's Electrical Stability Control (ESC), EMS (Engine Management System), and MDPS (Motor Driven Power Steering) are controlled. Typically, ADAS can be implemented as an automatic parking system, a low-speed city driving assistance system, a blind spot warning system, and the like.

Sensor devices for detecting the situation ahead in ADAS include a GPS sensor, laser scanner, front radar, Lidar, and the like, and the most representative is a camera for photographing the front, rear, and side of the vehicle.

Such a camera may be placed outside or inside a vehicle to detect surrounding conditions of the vehicle. In addition, the camera may be disposed inside the vehicle to detect situations of the driver and passengers. For example, the camera may photograph the driver at a location adjacent to the driver, and detect the driver's health condition, drowsiness, or drinking. In addition, the camera can photograph the passenger at a location adjacent to the passenger, detect whether the passenger is sleeping, health status, etc., and provide information about the passenger to the driver.

In particular, the most important element to obtain an image from a camera is an imaging lens that forms an image. Recently, interest in high performance, such as high image quality and high resolution, is increasing, and in order to realize this, research on an optical system including a plurality of lenses is being conducted. However, there is a problem in that the characteristics of the optical system change when the camera is exposed to harsh environments outside or inside the vehicle, such as high temperature, low temperature, moisture, and high humidity. In this case, the camera has a problem in that it is difficult to uniformly derive excellent optical characteristics and aberration characteristics. Therefore, a new optical system and camera capable of solving the above problems are required.

Embodiments are intended to provide an optical system and a camera module with improved optical characteristics.

In addition, embodiments are intended to provide an optical system and a camera module having excellent optical performance in a low-temperature to high-temperature environment.

In addition, embodiments are intended to provide an optical system and a camera module capable of preventing or minimizing changes in optical characteristics in various temperature ranges.

An optical system according to an embodiment includes first to fourth lenses disposed along an optical axis in a direction from an object side to a sensor side, the second lens has a negative refractive power along the optical axis, and the third lens extends along the optical axis. With positive refractive power, the second and third lenses may satisfy the following equation.

5 < L2_CT / d23_CT < 5.6

(L2_CT means the thickness of the second lens on the optical axis, and d23_CT is the distance between the second and third lenses on the optical axis.)

Also, the second lens may have a concave shape on both sides of the optical axis.

Also, an object-side surface of the first lens may have a convex shape in the optical axis.

In addition, the second and third lenses may satisfy the following equation.

11.3 < L3_CT / d23_CT < 12.5

(L3_CT means the thickness of the third lens on the optical axis, and d23_CT is the distance between the second and third lenses on the optical axis.)

Also, the fourth lens may satisfy the following equation.

0.1 < L4_CT / L4_ET < 1

(L4_CT denotes the thickness of the fourth lens along the optical axis. In addition, L4_ET is the thickness in the optical axis direction at the end of the effective area of the fourth lens, which is It is the distance between the ends of the effective area of the sensor-side surface of the fourth lens in the optical axis direction.)

Also, among the first to fourth lenses, the third lens may have the highest refractive index.

Also, among the first to fourth lenses, the second lens may have the smallest refractive index.

Also, materials of the first lens and the second lens may be different from each other.

Also, the first lens may be made of a glass material and the second lens may be made of a plastic material.

In addition, the optical system according to the embodiment includes first to fourth lenses disposed along an optical axis in a direction from an object side to a sensor side, the second lens has a negative refractive power along the optical axis, and the third lens The first to fourth lenses may have positive refractive power on the optical axis and satisfy the following equation.

dnt_1/dt < 0, dnt_2/dt < 0, dnt_3/dt < 0, dnt_4/dt < 0.

(dnt_1/dt, dnt_2/dt, dnt_3/dt, and dnt_4/dt are changes in the refractive index of each of the first to fourth lenses for light in the 940 nm wavelength band according to the amount of temperature change.)

Also, materials of the first lens and the second lens may be different from each other.

Also, materials of the fourth lens and the second lens may be different from each other.

In addition, the first lens, the third lens, and the fourth lens may include a glass material, and the second lens may include a plastic material.

Also, the second and third lenses may satisfy the following equation.

5 < L2_CT / d23_CT < 5.6

(L2_CT means the thickness of the second lens on the optical axis, and d23_CT is the distance between the second and third lenses on the optical axis.)

In addition, the camera module according to the embodiment may include the optical system and the image sensor, and may satisfy the following equation.

1 < TTL < 10

(TTL is the distance on the optical axis from the object-side surface of the first lens to the image surface of the sensor.)

An optical system and a camera module according to an embodiment may have improved optical characteristics. In detail, in the optical system according to the embodiment, a plurality of lenses may have a set thickness, spacing, refractive power, and the like. Accordingly, the optical system and the camera module according to the embodiment may have improved MTF characteristics, aberration control characteristics, resolution characteristics, etc. in a set field of view range, and may have good optical performance not only at the center of the field of view but also at the periphery.

In addition, the optical system and the camera module according to the embodiment may have good optical performance in a temperature range from low temperature (about -40°C) to high temperature (about 85°C). In detail, the plurality of lenses included in the optical system may have a set material, refractive power, and refractive index. Accordingly, even when the focal length of each lens changes due to a change in refractive index due to a change in temperature, the first to fourth lenses can compensate each other. That is, the optical system can effectively distribute the refractive power in a low to high temperature range, and prevent or minimize a change in optical properties in a low temperature (about -40°C) to high temperature (about 85°C) temperature range. can do. Therefore, the optical system and the camera module according to the embodiment may maintain improved optical characteristics in various temperature ranges.

In addition, the optical system and the camera module according to the embodiment may satisfy the minimum angle of view set by the lens and implement excellent optical characteristics. Due to this, the optical system can be provided with a slimmer and more compact structure. Accordingly, the optical system and the camera module can be provided for various applications and devices, and can have excellent optical properties even in harsh temperature environments, for example, exposed to the outside of a vehicle or inside a high-temperature vehicle in summer.

1 is a plan view of a vehicle to which a camera module or an optical system according to an embodiment is applied.
2 and 3 are views illustrating the interior of a vehicle to which a camera module or optical system according to an embodiment is applied.
4 is a configuration diagram of an optical system according to an embodiment.
5 is a graph showing data on diffraction MTF at room temperature (25° C.) of an optical system according to an embodiment.
6 is a graph showing data on diffraction MTF at a low temperature (-40° C.) of an optical system according to an embodiment.
7 is a graph showing data on diffraction MTF at a high temperature (85° C.) of an optical system according to an embodiment.
8 is a graph showing data on an aberration diagram at room temperature (25° C.) of an optical system according to an embodiment.
9 is a graph showing data on the aberration diagram of an optical system according to an embodiment at a low temperature (-40° C.).
10 is a graph showing data on the aberration diagram of an optical system according to an embodiment at a high temperature (85° C.).
11 to 13 are graphs showing the diffraction MTF according to the distance between the second and third lenses of the optical system according to the embodiment at room temperature (25° C.).
14 is data on distortion characteristics of an optical system according to an embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the technical idea of the present invention is not limited to some of the described embodiments, but may be implemented in a variety of different forms, and if it is within the scope of the technical idea of the present invention, one or more of the components among the embodiments can be selectively selected. can be used by combining and substituting. In addition, terms (including technical and scientific terms) used in the embodiments of the present invention, unless explicitly specifically defined and described, can be generally understood by those of ordinary skill in the art to which the present invention belongs. It can be interpreted as meaning, and commonly used terms, such as terms defined in a dictionary, can be interpreted in consideration of contextual meanings of related technologies.

Also, terms used in the embodiments of the present invention are for describing the embodiments and are not intended to limit the present invention. In this specification, the singular form may also include the plural form unless otherwise specified in the phrase, and when described as "at least one (or more than one) of A and (and) B and C", A, B, and C are combined. may include one or more of all possible combinations. Also, terms such as first, second, A, B, (a), and (b) may be used to describe components of an embodiment of the present invention. These terms are only used to distinguish the component from other components, and the term is not limited to the nature, order, or order of the corresponding component. And, when a component is described as being 'connected', 'coupled' or 'connected' to another component, the component is not only directly connected to, combined with, or connected to the other component, but also with the component. It may also include the case of being 'connected', 'combined', or 'connected' due to another component between the other components. In addition, when it is described as being formed or disposed on the "top (above) or bottom (bottom)" of each component, the top (top) or bottom (bottom) is not only a case where two components are in direct contact with each other, but also one A case in which another component above is formed or disposed between two components is also included. In addition, when expressed as "up (up) or down (down)", it may include the meaning of not only the upward direction but also the downward direction based on one component.

Also, the convex surface of the lens may mean that the lens surface in the optical axis area has a convex shape, and the concave surface of the lens may mean that the lens surface in the optical axis area has a concave shape. Also, the “object-side surface” may refer to a surface of a lens facing the object side based on an optical axis, and the “sensor-side surface” may refer to a surface of a lens facing the image sensor based on an optical axis. In addition, the vertical direction may mean a direction perpendicular to the optical axis, and the end of the lens or lens surface may mean the most end of an effective area of the lens through which incident light passes. In addition, the center thickness of the lens may refer to a length between the object side and the sensor side of the lens in the optical axis direction.

1 is a plan view of a vehicle to which a camera module or optical system according to an embodiment is applied, and FIGS. 2 and 3 are views showing the interior of a vehicle to which a camera module or optical system according to an embodiment is applied.

Referring to FIG. 1 , a vehicle 2000 according to an embodiment may include a first information generator 2100, a second information generator 2200, and a control unit 2300.

The first information generator 2100 may generate first detection information by detecting a front of the vehicle 2000 . For example, the first information generator 2100 includes a first camera module 2110 disposed outside or inside the vehicle 2000, and the first camera module 2110 includes the vehicle 2000. ) can generate an anterior image. In addition, the first camera module 2110 may generate an image of the surroundings of the vehicle 2000 by capturing not only the front of the vehicle 2000 but also the surroundings of the vehicle 2000 in one or more directions. Here, the front image and the surrounding image may be digital images, and may include color images, black and white images, and infrared images. Also, the front image and the surrounding image may include a still image and a moving image. The first camera module 2110 may provide the first sensing information formed by sensing a front image and a surrounding image to the controller 2300 .

Also, the first information generator 2100 may include at least one radar 2130. The radar 2130 may detect the front of the vehicle 2000 and form the first detection information. The radar 2130 may generate the first detection information by detecting the location and speed of other vehicles located in front of the vehicle 2000, presence and location of pedestrians, and the like, and provide the information to the control unit 2300. .

The second information generation unit 2200 detects the side and/or rear side of the vehicle 2000 based on the first detection information generated by the first information generation unit 2100 and generates second detection information. can create The second information generator 2200 may include at least one radar and/or camera.

The second information generation unit 2200 may sense or capture the positions and speeds of other vehicles located at the side and rear of the vehicle 2000 . The second information generators 2210, 2220, 2230, 2240, 2250, and 2260 may be disposed in at least one of front corners, side mirrors, rear corners, and rear center regions of the vehicle 2000. The second information generator 2200 may provide the second detection information to the controller 2300 .

The control unit 2300 uses at least one of the first detection information generated by the first information generation unit 2100 and the second detection information generated by the second information generation unit 2200, , the vehicle 2000 can be controlled. For example, the control unit 2300 may control the vehicle 2000 to maintain a constant distance from another vehicle located in front. In addition, the control unit 2300 controls operation of the vehicle 2000 or outputs a warning signal in a specific situation, such as when the driver of the vehicle 2000 changes a driving lane or moves backward, so that the vehicle 2000 Driving stability can be improved.

Also, referring to FIGS. 2 and 3 , the first information generator 2100 may further include at least one second camera module 2120 disposed inside the vehicle 2000 . The second camera module 2120 may be disposed adjacent to the driver and passenger. For example, the second camera module 2120 may be disposed at a location separated from the driver and passenger by a first distance to generate an internal image of the vehicle 2000 . In this case, the first distance may be about 400 mm or more.

The first information generating unit 2100 may generate an internal image of the vehicle 2000 using the second camera module 2120 . Here, the interior image of the vehicle 2000 may be a digital image, and may include a color image, a black and white image, and an infrared image. Also, the internal image may include a still image and a moving image. The first information generation unit 2100 may provide the control unit 2300 with an interior image of the vehicle 2000 captured through the second camera module 2120 .

The control unit 2300 may provide information to the occupants of the vehicle 2000 based on the information provided from the first information generating unit 2100 . For example, based on the information through the second camera module 2120, the driver's state of health, drowsiness, drinking, etc. may be detected, and information such as guidance and warning corresponding thereto may be provided to the driver. can In addition, based on the information provided by the second camera module 2120, it is possible to detect the passenger's health condition, sleep state, etc., and provide the driver and/or the passenger with this information.

The vehicle 2000 uses at least one camera module of the above-described first camera module 2110 and the second camera module 2120 to capture the front, rear, each side, or corner area of the vehicle 2000. The acquired information may be used, and the vehicle 2000 and objects may be protected from autonomous driving or surrounding safety by providing or processing the information to the user. In addition, it may be provided inside the vehicle 2000 to provide various information to the driver and/or passengers. That is, functions such as a lane keeping assistance system (LKAS), a lane departure warning system (LDWS), and a driver monitoring system (DMS) may be provided through the camera module.

At this time, at least one camera module of the first camera module 2110 and the second camera module 2120 has an optical system (which will be described later) to have stable and improved optical characteristics and reliability in various environments, for example, various temperature ranges. 1000) may be included.

Hereinafter, the optical system 1000 according to the embodiment will be described in detail.

The optical system 1000 according to the embodiment may include a plurality of lenses 100 and an image sensor 300 . The optical system 1000 according to the embodiment may include two or more lenses. For example, the optical system 1000 may include 4 lenses. The optical system 1000 may include a first lens 110, a second lens 120, a third lens 130, and a fourth lens 140 sequentially arranged from the object side to the sensor side, An image sensor 300 disposed next to the fourth lens 140 may be included. The first to fourth lenses 110 , 120 , 130 , and 140 may be sequentially disposed along the optical axis OA of the optical system 1000 .

Light corresponding to object information passes through the first lens 110, the second lens 120, the third lens 130, and the fourth lens 140 and is incident on the image sensor 300. It can be.

Each of the plurality of lenses 100 may include an effective area and an ineffective area. The effective area may be an area through which light incident to each of the first to ninth lenses 110 , 120 , 130 , 140 , 150 , 160 , 170 , 180 , and 190 passes. That is, the effective area may be an area in which the incident light is refracted to implement optical characteristics.

The non-effective area may be arranged around the effective area. The ineffective area may be an area in which light is not incident from the plurality of lenses 100 . That is, the non-effective area may be an area unrelated to the optical characteristics. Also, the non-effective area may be an area fixed to a barrel (not shown) accommodating the lens.

The image sensor 300 may detect light. In detail, the image sensor 300 may detect light sequentially passing through the plurality of lenses 100 , and in detail the first to third lenses 110 , 120 , and 130 . The image sensor 300 may include a device capable of sensing incident light, such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS).

The image sensor 300 may detect light of a set wavelength. In detail, the image sensor 300 may detect at least one of visible light and infrared (IR) light. For example, the image sensor 300 may detect near infrared ray light of about 1500 nm or less. The image sensor may detect light in a wavelength band of about 880 nm to about 1000 nm.

The optical system 1000 according to the embodiment may include a filter 500 . The filter 500 may be disposed between the plurality of lenses 100 and the image sensor 300 . The filter 500 may be disposed between the image sensor 300 and a last lens closest to the image sensor 300 among the plurality of lenses 100 . For example, when the optical system 1000 includes four lenses, the filter 500 may be disposed between the fourth lens 140 and the image sensor 300 .

The filter 500 may pass light of a set wavelength band and filter light of a different wavelength band. The filter 500 may pass light of a wavelength band corresponding to light received by the image sensor 300 and may block light of a wavelength band not corresponding to the light received. In detail, the filter 500 can pass light in the infrared wavelength band and block light in the ultraviolet and visible ray bands. For example, the filter 500 may include at least one of an IR pass filter and an IR cut-off filter.

In addition, the optical system 1000 according to the embodiment may further include a cover glass (not shown).

The cover glass may be disposed between the plurality of lenses 100 and the image sensor 300 . The cover glass may be disposed between the filter 500 and the image sensor 300 . The cover glass may be disposed adjacent to the image sensor 300 .

The cover glass may include a material through which light passing through the filter 500 may pass, and may have a shape corresponding to that of the image sensor 300 . The cover glass may be provided in a size equal to or greater than that of the image sensor 300 to protect an upper portion of the image sensor 300 .

In addition, the optical system 1000 according to the embodiment may include a stop (not shown). The diaphragm may control the amount of light incident to the optical system 1000 .

The diaphragm may be disposed at a set position. For example, the diaphragm may be positioned in front of the first lens 110 or behind the first lens 110 . Also, the diaphragm may be disposed between two lenses selected from among the plurality of lenses 100 . For example, the diaphragm may be positioned between the first lens 110 and the second lens 120 .

In addition, at least one lens of the first to fourth lenses 110, 120, 130, and 140 may serve as a diaphragm. In detail, an object-side surface or a sensor-side surface of one lens selected from among the first to fourth lenses 110, 120, 130, and 140 may serve as a diaphragm for adjusting the amount of light. For example, the object-side surface (first surface S1) of the first lens 110 may serve as a diaphragm.

Hereinafter, the plurality of lenses 100 according to the embodiment will be described in more detail.

The first lens 110 may have positive (+) refractive power along the optical axis OA. The first lens 110 may include a glass material.

The first lens 110 may include a first surface S1 defined as an object side surface and a second surface S2 defined as a sensor side surface. The first surface S1 may have a convex shape along the optical axis OA, and the second surface S2 may have a concave shape along the optical axis OA. That is, the first lens 110 may have a meniscus shape convex from the optical axis OA toward the object side. Alternatively, the first surface S1 may have a convex shape along the optical axis OA, and the second surface S2 may have a convex shape along the optical axis OA. That is, the first lens 110 may have a convex shape on both sides of the optical axis OA.

At least one of the first surface S1 and the second surface S2 may be a sphere. For example, both the first surface S1 and the second surface S2 may be spheres.

The second lens 120 may have negative (-) refractive power on the optical axis OA. The second lens 120 may include a glass or plastic material.

The second lens 120 may include a third surface S3 defined as an object side surface and a fourth surface S4 defined as a sensor side surface. The third surface S3 may have a concave shape in the optical axis OA, and the fourth surface S4 may have a concave shape in the optical axis OA. That is, the second lens 120 may have a concave shape on both sides of the optical axis OA.

At least one of the third and fourth surfaces S3 and S4 may be an aspheric surface. For example, both the third surface S3 and the fourth surface S4 may be aspheric surfaces (Asphere).

The third lens 130 may have positive (+) refractive power along the optical axis OA. The third lens 130 may include a glass or plastic material.

The third lens 130 may include a fifth surface S5 defined as an object side surface and a sixth surface S6 defined as a sensor side surface. The fifth surface S5 may have a convex shape along the optical axis OA, and the sixth surface S6 may have a concave shape along the optical axis OA. That is, the third lens 130 may have a meniscus shape convex from the optical axis OA toward the object side. Alternatively, the fifth surface S5 may have a convex shape along the optical axis OA, and the sixth surface S6 may have a convex shape along the optical axis OA. That is, the third lens 130 may have a convex shape on both sides of the optical axis OA. Alternatively, the fifth surface S5 may have a concave shape along the optical axis OA, and the sixth surface S6 may have a convex shape along the optical axis OA. That is, the third lens 130 may have a convex meniscus shape toward the image sensor 300 from the optical axis OA. Alternatively, the fifth surface S5 may have a concave shape in the optical axis OA, and the sixth surface S6 may have a concave shape in the optical axis OA. That is, the third lens 130 may have a concave shape on both sides of the optical axis OA.

At least one of the fifth surface S5 and the sixth surface S6 may be an aspherical surface (Asphere). For example, both the fifth surface S5 and the sixth surface S6 may be aspheric surfaces (Asphere).

The fourth lens 140 may have negative (-) refractive power along the optical axis OA. The fourth lens 140 may include a glass material.

The fourth lens 140 may include a seventh surface S7 defined as an object side surface and an eighth surface S8 defined as a sensor side surface. The seventh surface S7 may have a convex shape along the optical axis OA, and the eighth surface S8 may have a concave shape along the optical axis OA. That is, the fourth lens 140 may have a meniscus shape convex from the optical axis OA toward the object side. Alternatively, the seventh surface S7 may have a convex shape along the optical axis OA, and the eighth surface S8 may have a convex shape along the optical axis OA. That is, the fourth lens 140 may have a convex shape on both sides of the optical axis OA. Alternatively, the seventh surface S7 may have a concave shape along the optical axis OA, and the eighth surface S8 may have a convex shape along the optical axis OA. That is, the fourth lens 140 may have a convex meniscus shape toward the image sensor 300 from the optical axis OA. Alternatively, the seventh surface S7 may have a concave shape in the optical axis OA, and the eighth surface S8 may have a concave shape in the optical axis OA. That is, the fourth lens 140 may have a concave shape on both sides of the optical axis OA.

At least one of the seventh surface S7 and the eighth surface S8 may be a sphere. For example, both the seventh surface S7 and the eighth surface S8 may be spheres.

The optical system 1000 according to the embodiment may satisfy at least one equation among equations described below. Accordingly, the optical system 1000 according to the embodiment can prevent or minimize a change in optical characteristics depending on temperature, and thus can have good optical performance at various temperatures. In addition, the optical system 1000 according to the embodiment may have improved distortion and aberration characteristics at various temperatures as it satisfies at least one of equations to be described later.

Equations will be described below. Here, the values of the items described in the equations mean values at room temperature (25 ° C.).

[Equation 1]

1.6 < nt_1 < 1.8

In Equation 1, nt_1 is a refractive index of the first lens 110 for light in a wavelength band of about 940 nm.

When the optical system 1000 according to the embodiment satisfies Equation 1, the optical system 1000 may control a light beam incident to the optical system 1000 through the first lens 110 .

[Equation 2]

1.4 < nt_2 < 1.7

In Equation 2, nt_2 is the refractive index of the second lens 120 for light in a wavelength band of about 940 nm.

[Equation 3]

nt_2 < nt_3

nt_4 < nt_3

nt_2 < nt_4

In Equation 3, nt_2 is the refractive index of the second lens 120 for light in a wavelength band of about 940 nm, nt_3 is the refractive index of the third lens 130 for light in the wavelength band of about 940 nm, and nt_4 is the first 4 is the refractive index of the lens 140 for light in a wavelength band of about 940 nm.

When the optical system 1000 according to the embodiment satisfies Equation 3, the optical system 1000 interrelates the refractive index of the lens that changes according to the temperature in the temperature range from low temperature (about -40 ℃) to high temperature (about 85 ℃). can compensate

[Equation 4]

dnt_1/dt < 0

dnt_2/dt < 0

dnt_3/dt < 0

dnt_4/dt < 0

In Equation 4, dt denotes a temperature change amount (° C.), and dnt_1 is a refractive index change of the first lens 110 for light in a wavelength band of about 940 nm. That is, dnt_1/dt means a change in the refractive index of the first lens 110 for light in the 940 nm wavelength band according to the amount of temperature change. Also, dnt_2 is a change in the refractive index of the second lens 120 for light in a wavelength band of about 940 nm. That is, dnt_2/dt means a change in the refractive index of the second lens 120 for light in the 940 nm wavelength band according to the amount of temperature change. Also, dnt_3 is a change in the refractive index of the third lens 130 for light in a wavelength band of about 940 nm. That is, dnt_3/dt means a change in the refractive index of the third lens 130 for light in the 940 nm wavelength band according to the amount of temperature change.

When the optical system according to the embodiment satisfies Equation 4, the optical system 1000 may mutually compensate for the refractive index of the lens that changes according to the temperature in the temperature range of low temperature (about -40 ° C) to high temperature (about 85 ° C). there is. Accordingly, the optical system 1000 may have good optical performance within a set temperature range.

[Equation 5]

5 < L2_CT / d23_CT < 5.6

In Equation 5, L2_CT means the thickness (mm) of the second lens 120 on the optical axis OA. Also, d23_CT means the distance (mm) between the second lens 120 and the third lens 130 on the optical axis OA. In detail, d23_CT is the distance from the optical axis OA of the sensor side surface (fourth surface S4) of the second lens 120 and the object side surface (fifth surface S5) of the third lens 130. (mm).

When the optical system 1000 according to the embodiment satisfies Equation 5, the optical system 1000 can prevent deterioration of the resolution characteristic of the peripheral portion of the field of view (FOV) and can have good optical performance.

[Equation 6]

11.3 < L3_CT / d23_CT < 12.5

In Equation 6, L3_CT means the thickness (mm) of the third lens 130 on the optical axis OA. Also, d23_CT means the distance (mm) between the second lens 120 and the third lens 130 on the optical axis OA. In detail, d23_CT is the distance from the optical axis OA of the sensor side surface (fourth surface S4) of the second lens 120 and the object side surface (fifth surface S5) of the third lens 130. (mm).

When the optical system 1000 according to the embodiment satisfies Equation 6, the optical system 1000 can prevent deterioration of the resolution characteristic of the peripheral portion of the field of view (FOV) and can have good optical performance.

[Equation 7]

1 < L3_CT / d34_CT < 2

In Equation 7, L3_CT means the thickness (mm) of the third lens 130 on the optical axis OA. Also, d34_CT means the distance (mm) between the third lens 130 and the fourth lens 140 on the optical axis OA. In detail, d34_CT is the sensor-side surface (sixth surface S6) of the third lens 130 and the object-side surface (seventh surface S7) of the fourth lens 140 on the optical axis OA. Means distance (mm).

When the optical system 1000 according to the embodiment satisfies Equation 7, the optical system 1000 has good optical performance at the periphery of the angle of view (FOV) in a temperature range from low temperature (about -40 ° C) to high temperature (about 85 ° C). can have

[Equation 8]

0.1 < L4_CT / d34_CT < 1

In Equation 8, L4_CT means the thickness (mm) of the fourth lens 140 on the optical axis OA. Also, d34_CT means the distance (mm) between the third lens 130 and the fourth lens 140 on the optical axis OA. In detail, d34_CT is the sensor-side surface (sixth surface S6) of the third lens 130 and the object-side surface (seventh surface S7) of the fourth lens 140 on the optical axis OA. Means distance (mm).

When the optical system 1000 according to the embodiment satisfies Equation 8, the optical system 1000 has good optical performance in the periphery of the angle of view (FOV) in a temperature range from low temperature (about -40 ° C) to high temperature (about 85 ° C). can have

[Equation 9]

0 < d23_CT / d34_CT < 0.5

In Equation 9, d23_CT means the distance (mm) between the second lens 120 and the third lens 130 on the optical axis OA. In detail, d23_CT is the distance from the optical axis OA of the sensor side surface (fourth surface S4) of the second lens 120 and the object side surface (fifth surface S5) of the third lens 130. (mm).

Also, d34_CT means the distance (mm) between the third lens 130 and the fourth lens 140 on the optical axis OA. In detail, d34_CT is the sensor-side surface (sixth surface S6) of the third lens 130 and the object-side surface (seventh surface S7) of the fourth lens 140 on the optical axis OA. Means distance (mm).

When the optical system 1000 according to the embodiment satisfies Equation 9, the optical system 1000 may have good optical performance in a temperature range from low temperature (about -40°C) to high temperature (about 85°C).

[Equation 10]

0.1 < L4_CT / L4_ET < 1

In Equation 10, L4_CT means the thickness (mm) in the optical axis (OA) of the fourth lens 140, and L4_ET is the thickness (mm) in the optical axis (OA) direction at the end of the effective area of the fourth lens 140 ( mm) means. In detail, L4_ET is the end of the effective area of the object side surface (seventh surface S7) of the fourth lens 140 and the effective area of the sensor side surface (eighth surface S8) of the fourth lens 140. It means the distance in the direction of the optical axis (OA) between the ends.

When the optical system 1000 according to the embodiment satisfies Equation 10, the optical system 1000 may control the MTF characteristics of the peripheral portion of the field of view (FOV).

[Equation 11]

-1 < L1R1 / L2R1 < 0

In Equation 11, L1R1 means the radius of curvature (mm) of the object side surface (first surface S1) of the first lens 110, and L2R1 is the object side surface of the second lens 120 (the first surface S1). It means the radius of curvature (mm) of the third surface (S3).

When the optical system 1000 according to the embodiment satisfies Equation 11, the optical system 1000 can control light incident on the optical system 1000 and improve optical performance.

[Equation 12]

1 < L1R1 / L2R2 < 2

In Equation 12, L1R1 means the radius of curvature (mm) of the object side surface (first surface S1) of the first lens 110, and L2R2 is the sensor side surface of the second lens 120 (the first surface S1). It means the radius of curvature (mm) of the fourth surface (S4).

When the optical system 1000 according to the embodiment satisfies Equation 12, the optical system 1000 can control light incident on the optical system 1000 and control MTF characteristics.

[Equation 13]

20 < L1R2 / L1R1 < 10000

In Equation 13, L1R1 means the radius of curvature (mm) of the object side surface (first surface S1) of the first lens 110, and L1R2 is the sensor side surface of the first lens 110 (the first surface S1). It means the radius of curvature (mm) of the second surface (S2).

When the optical system 1000 according to the embodiment satisfies Equation 13, the optical system 1000 can control the light rays incident on the optical system 1000, and on the sensor side of the first lens 110 When forming the coating layer, the coating layer may be easily formed.

[Equation 14]

-3 < f1 / f2 < -1

In Equation 14, f1 means the focal length (mm) of the first lens 110, and f2 means the focal length (mm) of the second lens 120.

When the optical system 1000 according to the embodiment satisfies Equation 14, the optical system 1000 can control the refractive power of the first lens 110 and the second lens 120, and at a low temperature (about -40 ° C). ) to high temperature (about 85° C.).

[Equation 15]

-3 < f2 / f3 < -1

In Equation 15, f2 means the focal length (mm) of the second lens 120, and f3 means the focal length (mm) of the third lens 130.

When the optical system 1000 according to the embodiment satisfies Equation 15, the optical system 1000 can control the refractive power of the second lens 120 and the third lens 130, and at a low temperature (about -40 ° C). ) to high temperatures (about 85° C.) to have good optical performance.

[Equation 16]

1 < CA_L3S2 / CA_L4S1 < 2

In Equation 16, CA_L3S2 means the clear aperture (CA) size (mm) of the sensor side surface (the sixth surface S6) of the third lens 130, and CA_L4S1 is the fourth lens 140 It means the size (mm) of the effective diameter CA of the object-side surface (the seventh surface S7) of .

When the optical system 1000 according to the embodiment satisfies Equation 16, the optical system 1000 may control aberration characteristics.

[Equation 17]

1.5 < CA_max / CA_min < 3

In Equation 17, CA_max means the effective diameter CA size (mm) of the lens surface having the largest effective diameter CA size among the object side and the sensor side of the plurality of lenses 100. Also, CA_min means the effective diameter (CA) size (mm) of the lens surface having the smallest effective diameter (CA) size among the object-side and sensor-side surfaces of the plurality of lenses 100 .

When the optical system 1000 according to the embodiment satisfies Equation 17, the optical system 1000 may be provided with a slim and compact structure while maintaining optical performance.

[Equation 18]

1 < CA_max / CA_Aver < 2

In Equation 18, CA_max means the effective diameter CA size (mm) of the lens surface having the largest effective diameter CA size among the object side and the sensor side of the plurality of lenses 100. Also, CA_Aver means the average of effective aperture (CA) sizes (mm) of the object-side and sensor-side surfaces of the plurality of lenses 100 .

When the optical system 1000 according to the embodiment satisfies Equation 18, the optical system 1000 may be provided with a slim and compact structure and may have an appropriate size for realizing optical performance.

[Equation 19]

0.1 < CA_min / CA_Aver < 1

In Equation 19, CA_min means the effective diameter CA size (mm) of the lens surface having the smallest effective diameter CA size among the object side and the sensor side of the plurality of lenses 100. Also, CA_Aver means the average of effective aperture (CA) sizes (mm) of the object-side and sensor-side surfaces of the plurality of lenses 100 .

When the optical system 1000 according to the embodiment satisfies Equation 19, the optical system 1000 may be provided with a slim and compact structure and may have an appropriate size for realizing optical performance.

[Equation 20]

0.5 < CA_max / (2*ImgH) < 1

In Equation 20, CA_max means the effective diameter CA size (mm) of the lens surface having the largest effective diameter CA size among the object side and the sensor side of the plurality of lenses 100.

In addition, ImgH is the vertical direction of the optical axis OA from the 0 field area at the center of the top surface of the image sensor 300 overlapping with the optical axis OA to the 1.0 field area of the image sensor 300. Means distance (mm). That is, the ImgH means 1/2 of the maximum diagonal length (mm) of the effective area of the image sensor 300 .

When the optical system 1000 according to the embodiment satisfies Equation 20, the optical system 1000 may be provided with a slim and compact structure.

[Equation 21]

1 ≤ |v1 - v2| ≤ 10

In Equation 21, v1 is the Abbe's number of the first lens 110, and v2 is the Abbe's number of the second lens 120.

[Equation 22]

20 ≤|v2 - v3| ≤ 50

In Equation 22, v2 is the Abbe number of the second lens 120, and v3 is the Abbe number of the third lens 130.

When the optical system 1000 according to the embodiment satisfies Equation 22, the optical system 1000 may have improved chromatic aberration control characteristics.

[Equation 23]

20 ≤ |v3 - v4| ≤ 50

In Equation 23, v3 is the Abbe's number of the third lens 130, and v4 is the Abbe's number of the fourth lens 140.

When the optical system 1000 according to the embodiment satisfies Equation 23, the optical system 1000 may have improved chromatic aberration control characteristics.

[Equation 24]

1 < TTL < 10

In Equation 24, Total track length (TTL) is the distance on the optical axis OA from the apex of the object side surface (first surface S1) of the first lens 110 to the top surface of the image sensor 300. (mm).

[Equation 25]

2 < ImgH

In Equation 25, ImgH is the ratio of the optical axis OA from the 0 field area at the center of the top surface of the image sensor 300 overlapping the optical axis OA to the 1.0 field area of the image sensor 300. It means vertical distance (mm). That is, the ImgH means 1/2 of the maximum diagonal length (mm) of the effective area of the image sensor 300 .

[Equation 26]

0.6 < BFL

In Equation 26, BFL (Back focal length) means the distance (mm) on the optical axis OA from the apex of the sensor-side surface of the lens closest to the image sensor 300 to the upper surface of the image sensor 300 .

When the optical system 1000 according to the embodiment satisfies Equation 26, the optical system 1000 has at least one of the filter 500 and the cover glass between the plurality of lenses 100 and the image sensor 300. It is possible to secure a space in which one component is placed, so that it can have improved assemblability. Accordingly, the optical system 1000 can transmit light of a set wavelength band and have improved reliability.

[Equation 27]

30 < FOV < 150

In Equation 27, field of view (FOV) means the angle of view (degrees, °) of the optical system 1000.

[Equation 28]

0.5 < TTL / ImgH < 5

In Equation 28, Total track length (TTL) is the distance on the optical axis OA from the apex of the object-side surface (first surface S1) of the first lens 110 to the top surface of the image sensor 300. (mm).

In addition, ImgH is the vertical direction of the optical axis OA from the 0 field area at the center of the top surface of the image sensor 300 overlapping with the optical axis OA to the 1.0 field area of the image sensor 300. Means distance (mm). That is, the ImgH means 1/2 of the maximum diagonal length (mm) of the effective area of the image sensor 300 .

When the optical system 1000 according to the embodiment satisfies Equation 28, the optical system 1000 secures a BFL (Back focal length) for application of the relatively large image sensor 300 and can have a smaller TTL and may have a high-definition implementation and a slim structure.

[Equation 29]

0.1 < BFL / ImgH < 0.5

In Equation 29, Back focal length (BFL) means the distance (mm) on the optical axis OA from the apex of the sensor-side surface of the lens closest to the image sensor 300 to the upper surface of the image sensor 300 .

In addition, ImgH is the vertical direction of the optical axis OA from the 0 field area at the center of the top surface of the image sensor 300 overlapping with the optical axis OA to the 1.0 field area of the image sensor 300. Means distance (mm). That is, the ImgH means 1/2 of the maximum diagonal length (mm) of the effective area of the image sensor 300 .

When the optical system 1000 according to the embodiment satisfies Equation 29, the optical system 1000 can secure a BFL (Back focal length) for applying the relatively large image sensor 300, and the last lens Since the distance between the image sensor 300 and the image sensor 300 can be minimized, good optical characteristics can be obtained at the center and the periphery of the field of view (FOV).

[Equation 30]

4 < TTL / BFL < 10

In Equation 30, Total track length (TTL) is the distance on the optical axis OA from the apex of the object-side surface (first surface S1) of the first lens 110 to the top surface of the image sensor 300. (mm).

In addition, a back focal length (BFL) means a distance (mm) on an optical axis OA from the apex of the sensor-side surface of the lens closest to the image sensor 300 to the top surface of the image sensor 300.

When the optical system 1000 according to the embodiment satisfies Equation 30, the optical system 1000 secures the BFL and can be provided slim and compact.

[Equation 31]

0.1 < F / TTL < 1

In Equation 31, F means the total focal length (mm) of the optical system 1000, and TTL (Total track length) is the apex of the object side surface (first surface S1) of the first lens 110. It means the distance (mm) on the optical axis OA from to the upper surface of the image sensor 300.

When the optical system 1000 according to the embodiment satisfies Equation 31, the optical system 1000 can be provided slim and compact.

[Equation 32]

3 < F / BFL < 8

In Equation 32, F means the total focal length (mm) of the optical system 1000, and BFL (Back focal length) is the image sensor 300 from the apex of the sensor side of the lens closest to the image sensor 300. ) means the distance (mm) from the optical axis OA to the top surface of

When the optical system 1000 according to the embodiment satisfies Equation 32, the optical system 1000 has a set angle of view and can be provided slim and compact. In addition, the optical system 1000 can minimize the distance between the last lens and the image sensor 300, so that it can have good optical characteristics in the periphery of the field of view (FOV).

[Equation 33]

1 < F / ImgH < 3

In Equation 33, F means the total focal length (mm) of the optical system 1000, and ImgH is the image sensor in the field center 0 field area of the image sensor 300 overlapping the optical axis OA. It means the distance (mm) in the vertical direction of the optical axis (OA) to the 1.0 field area of (300). That is, the ImgH means 1/2 of the maximum diagonal length (mm) of the effective area of the image sensor 300 .

When the optical system 1000 according to the embodiment satisfies Equation 33, the optical system 1000 may have an appropriate focal length compared to the size of the image sensor 300, have improved aberration characteristics, and implement high quality and high resolution.

[Equation 34]

In Equation 34, Z is Sag and may mean a distance in the optical axis direction from an arbitrary position on the aspheric surface to the apex of the aspherical surface.

Also, Y may mean a distance in a direction perpendicular to the optical axis from an arbitrary position on the aspherical surface to the optical axis.

Also, c may mean the curvature of the lens, and K may mean the conic constant.

Also, A, B, C, D, ?? may mean an aspheric constant.

The refractive index of the plurality of lenses 100 according to the embodiment may change according to a temperature change within a set temperature range.

Low temperature (-40℃) Normal temperature (25℃) High temperature (85℃) 1st lens +0.00031 1.66672 -0.00038 2nd lens +0.0065 1.531131 -0.0054 3rd lens +0.00036 1.755199 -0.00037 4th lens +0.00051 1.6935 -0.00047

In detail, Table 1 shows the first to fourth lenses (110, 120, 130, 140) data for each refractive index difference. For example, in Table 1, the values for the low temperature (−40° C.) and high temperature (85° C.) items are the difference values for the refractive index values at room temperature (25° C.).

Referring to Table 1, it can be seen that the first to fourth lenses 110, 120, 130, and 140 have a higher refractive index at a low temperature (-40 ° C) than at a room temperature (25 ° C), and at a high temperature (85 ° C) It can be seen that it has a smaller refractive index than room temperature (25 ℃). In particular, the change in refractive index (dnt_1/dt, dnt_2/dt, dnt_3/dt, dnt_4/dt) according to the temperature change of each of the first to fourth lenses 110, 120, 130, and 140 is as shown in Equation 4. It can be seen that it has a negative (-) value.

In this case, the first lens 110 may have a higher refractive index than the second lens 120 . In detail, the first lens 110 may have a higher refractive index than the second lens 120 in order to compensate for the refractive index of the second lens 120 whose refractive index changes with a temperature change is relatively large.

Also, among the first to fourth lenses 110, 120, 130, and 140, the third lens 130 may have the largest refractive index and the second lens 120 may have the smallest refractive index. The plurality of lenses 100 may have higher refractive indices in the order of the third lens 130 , the fourth lens 140 , the first lens 110 , and the second lens 120 . Also, the third lens 130 may have the largest diopter value among the first to fourth lenses 110 , 120 , 130 , and 140 . Here, the diopter value may mean an absolute value of the diopter of each of the first to fourth lenses 110, 120, 130, and 140.

Accordingly, the third lens 130 can effectively distribute the power of the optical system 1000 of the optical system 1000 in a temperature range from low temperature (-40°C) to high temperature (85°C). Therefore, the optical system 1000 according to the embodiment can minimize or prevent changes in optical characteristics in a low to high temperature environment, and can have good optical performance in the center and periphery of the FOV in various temperature ranges. there is.

That is, in the optical system 1000 according to the embodiment, at least one of the first lens 110, the third lens 130, and the fourth lens 140 is made of a material different from that of the second lens 120. , and may satisfy at least one of Equations 1 to 33 above. Accordingly, the optical system 1000 can minimize or prevent a change in optical characteristics at a low to high temperature.

In addition, as the optical system 1000 according to the embodiment satisfies at least one of Equations 1 to 33, the optical system 1000 prevents or minimizes changes in distortion and aberration characteristics in various temperature ranges. It can have excellent resolution in the periphery as well as the center of the field of view (FOV) and have good optical performance.

The optical system 1000 according to the embodiment will be described in more detail with reference to FIGS. 4 to 13 .

4 is a configuration diagram of an optical system according to an embodiment, and FIGS. 5 to 7 are diffraction MTF data at room temperature (25 ° C), low temperature (-40 ° C) and high temperature (85 ° C) of the optical system according to the embodiment. am. 8 to 10 are data on aberration diagrams at room temperature (25 ° C), low temperature (-40 ° C), and high temperature (85 ° C) of the optical system according to the embodiment, and FIGS. 11 to 13 are room temperature (25 ° C) ℃) is data on the diffraction MTF according to the distance between the second and third lenses of the optical system according to the embodiment. 14 is data on distortion characteristics of an optical system according to an embodiment.

Referring to FIG. 4 , an optical system 1000 according to an embodiment includes a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, and an image sensor 300. can do. The first to fourth lenses 110 , 120 , 130 , and 140 may be sequentially disposed along the optical axis OA of the optical system 1000 .

Also, in the optical system 1000, the object-side surface (first surface S1) of the first lens 110 may serve as a diaphragm.

In addition, a filter 500 may be disposed between the plurality of lenses 100 and the image sensor 300 . In detail, the filter 500 may be disposed between the fourth lens 140 and the image sensor 300 .

lens noodle Bending radius (mm) Thickness or Spacing (mm) refractive index Abe number Size of effective diameter (mm) 1st lens page 1
(Stop) 3.723 0.800 1.667 48.297 2.274 side 2 150.000 0.355 2.476 2nd lens 3rd side -4.635 0.800 1.531 55.754 2.556 page 4 2.780 0.150 3.323 3rd lens page 5 2.612 1.800 1.755 27.512 3.957 page 6 -3.550 1.170 4.011 4th lens page 7 -2.188 0.800 1.694 53.201 3.533 page 8 -15.000 0.150 4.623 filter Infinity 0.400 4.963 Infinity 0.770 5.218 image sensor Infinity -0.021 6.000

Table 2 shows the radius of curvature and thickness of the lens in the optical axis (OA) of the first to fourth lenses (110, 120, 130, 140) according to the embodiment at room temperature (25 ° C) , the distance between the lenses, the refractive index at a wavelength of about 940 nm, the Abbe's Number, and the size of the clear aperture (CA).

In the optical system 1000 according to the embodiment, the first lens 110 may have positive (+) refractive power on the optical axis OA. The first lens 110 may be made of a glass material. The first surface S1 of the first lens 110 may have a convex shape along the optical axis OA, and the second surface S2 may have a concave shape along the optical axis OA. The first lens 110 may have a meniscus shape convex from the optical axis OA toward the object side. The first surface S1 and the second surface S2 may be spheres.

The second lens 120 may have negative (-) refractive power on the optical axis OA. The second lens 120 may be provided with a material different from that of the first lens 110 . For example, the second lens 120 may be made of a plastic material. The third surface S3 of the second lens 120 may have a concave shape in the optical axis OA, and the fourth surface S4 may have a concave shape in the optical axis OA. The second lens 120 may have a concave shape on both sides of the optical axis OA. The third surface S3 and the fourth surface S4 may be aspheric surfaces. The third surface S3 and the fourth surface S4 may have aspherical surface coefficients as shown in Table 3 below.

The third lens 130 may have positive (+) refractive power along the optical axis OA. The third lens 130 may be provided with a material different from that of the second lens 120 . For example, the third lens 130 may be made of a glass material. The fifth surface S5 of the third lens 130 may have a convex shape along the optical axis OA, and the sixth surface S6 may have a convex shape. The third lens 130 may have a convex shape on both sides of the optical axis OA. The fifth surface S5 and the sixth surface S6 may be aspheric surfaces. The fifth surface S5 and the sixth surface S6 may have aspherical surface coefficients as shown in Table 3 below.

The fourth lens 140 may have negative (-) refractive power along the optical axis OA. The fourth lens 140 may be provided with a material corresponding to that of the first lens 110 or a material different from that of the second lens 120 . For example, the fourth lens 140 may be made of a glass material. The seventh surface S7 of the fourth lens 140 may have a concave shape along the optical axis OA, and the eighth surface S8 may have a convex shape along the optical axis OA. The fourth lens 140 may have a convex meniscus shape toward the image sensor 300 from the optical axis OA. The seventh surface S7 and the eighth surface S8 may be spheres.

In the optical system 1000 according to the embodiment, the value of the aspherical surface coefficient of each lens surface is shown in Table 3 below.

2nd lens 3rd lens 3rd side page 4 page 5 page 6 Y -4.63E+00 2.78E+00 2.61E+00 -3.55E+00 K 8.49E+00 -2.01E+01 -1.17E+01 -2.45E+00 A -8.95E-03 -1.15E-02 9.15E-03 -3.23E-03 B 2.02E-02 7.01E-03 -9.67E-04 4.04E-04 C -1.11E-02 -2.40E-03 1.83E-04 3.86E-05 D 3.43E-03 3.56E-04 0 0 E 0 0 0 0 F 0 0 0 0 G 0 0 0 0 H 0 0 0 0 J 0 0 0 0

In addition, the first lens 110 of the optical system 1000 according to the embodiment may have a thickness set according to the height as shown in Table 4 below at room temperature (25° C.).

Vertical height from optical axis (mm) Optical axis direction thickness of the first lens 110 (mm) 0 0.800 0.1 0.799 0.2 0.795 0.3 0.788 0.4 0.779 0.5 0.767 0.6 0.753 0.7 0.735 0.8 0.715 0.9 0.692 One 0.667 1.1 0.638 1.137 0.606

In Table 4, the point at which the height in the vertical direction is 0 from the optical axis OA means the optical axis OA. In addition, in Table 4, the point at which the height in the vertical direction is 1.137 is the effective radius of the first surface S1 having a small effective mirror among the first and second surfaces S1 and S2 of the first lens 110 ( 1/2 of the size of the effective diameter in Table 1) means the value.

Referring to Table 4, the thickness of the first lens 110 in the direction of the optical axis OA may decrease from the optical axis OA to the end of the effective area of the first surface S1. In the height range in the vertical direction described above, the thickness of the first lens 110 in the direction of the optical axis OA may have a maximum value along the optical axis OA and may have a minimum value at an end of the effective area of the first surface S1. . In this case, the maximum value of the thickness of the first lens 110 in the direction of the optical axis (OA) may be about 1.1 times to about 2 times the minimum value. For example, in the embodiment, the thickness of the first lens 110 in the optical axis direction may be approximately 1.32 times the minimum value of the maximum value.

That is, in the optical system 1000 according to the embodiment, the first lens 110 may have the aforementioned optical axis OA direction thickness. Accordingly, the optical system 1000 can effectively control light incident at a set angle of view.

In addition, the second lens 120 of the optical system 1000 according to the embodiment may have a thickness set according to a height as shown in Table 5 below at room temperature (25° C.).

Vertical height from optical axis (mm) Optical axis direction thickness of the second lens 120 (mm) 0 0.800 0.1 0.803 0.2 0.811 0.3 0.825 0.4 0.844 0.5 0.867 0.6 0.894 0.7 0.925 0.8 0.960 0.9 0.998 One 1.039 1.1 1.084 1.2 1.133 1.278 1.186

In Table 5, the point at which the height in the vertical direction is 0 from the optical axis OA means the optical axis OA. In addition, in Table 5, the point where the height in the vertical direction is 1.278 is the effective radius of the third surface S3 having a smaller effective mirror among the third and fourth surfaces S3 and S4 of the second lens 120 ( 1/2 of the size of the effective diameter in Table 1) means the value.

Referring to Table 5, the thickness of the second lens 120 in the direction of the optical axis OA may increase from the optical axis OA to the end of the effective area of the third surface S3. In the height range in the vertical direction described above, the thickness of the second lens 120 in the direction of the optical axis OA may have a minimum value along the optical axis OA and a maximum value at an end of the effective area of the third surface S3. . In this case, the maximum value of the thickness of the second lens 120 in the direction of the optical axis (OA) may be about 1.1 times to about 2 times the minimum value. For example, in the embodiment, the thickness of the second lens 120 in the optical axis direction may be about 1.48 times the minimum value of the maximum value.

That is, in the optical system 1000 according to the embodiment, the second lens 120 may have the aforementioned optical axis OA direction thickness. Accordingly, the optical system 1000 has a set distance between the first lens 110 and the third lens 130 and can control the path of incident light to the set path.

In addition, the third lens 130 of the optical system 1000 according to the embodiment may have a thickness set according to a height as shown in Table 6 below at room temperature (25° C.).

Vertical height from optical axis (mm) Optical axis direction thickness of the third lens 130 (mm) 0 1.800 0.1 1.797 0.2 1.787 0.3 1.771 0.4 1.748 0.5 1.720 0.6 1.687 0.7 1.649 0.8 1.605 0.9 1.557 One 1.505 1.1 1.448 1.2 1.386 1.3 1.320 1.4 1.250 1.5 1.175 1.6 1.096 1.7 1.012 1.8 0.922 1.9 0.828 1.979 0.728

In Table 6, the point at which the height in the vertical direction is 0 from the optical axis OA means the optical axis OA. In addition, in Table 6, the point at which the height in the vertical direction is 1.979 is the effective radius of the fifth surface S5 having a smaller effective mirror among the fifth and sixth surfaces S5 and S6 of the third lens 130 ( 1/2 of the size of the effective diameter in Table 1) means the value.

Referring to Table 6, the thickness of the third lens 130 in the direction of the optical axis OA may decrease from the optical axis OA to the end of the effective area of the fifth surface S5. In the height range in the vertical direction described above, the thickness of the third lens 130 in the direction of the optical axis OA may have a minimum value at the end of the effective area of the fifth surface S5 and a maximum value along the optical axis OA. . In this case, the maximum value of the thickness of the third lens 130 in the direction of the optical axis (OA) may be about 2 times to about 3.5 times the minimum value. For example, in the embodiment, the thickness of the third lens 130 in the optical axis direction may be approximately 2.47 times the minimum value of the maximum value.

That is, in the optical system 1000 according to the embodiment, the third lens 130 may have the aforementioned thickness in the optical axis OA direction. Accordingly, the optical system 1000 may have good optical performance at a set angle of view.

In addition, the fourth lens 140 of the optical system 1000 according to the embodiment may have a thickness set according to the height as shown in Table 7 below at room temperature (25° C.).

Vertical height from optical axis (mm) Optical axis direction thickness of the fourth lens 140 (mm) 0 0.800 0.1 0.802 0.2 0.808 0.3 0.818 0.4 0.832 0.5 0.850 0.6 0.872 0.7 0.899 0.8 0.930 0.9 0.967 One 1.008 1.1 1.056 1.2 1.110 1.3 1.172 1.4 1.241 1.5 1.320 1.6 1.410 1.7 1.514 1.767 1.636

In Table 7, the point at which the height in the vertical direction is 0 from the optical axis OA means the optical axis OA. In addition, in Table 7, the point at which the height in the vertical direction is 1.767 is the effective radius of the seventh surface S7 having a smaller effective mirror among the seventh and eighth surfaces S7 and S8 of the fourth lens 140 ( 1/2 of the size of the effective diameter in Table 1) means the value.

Referring to Table 7, the thickness of the fourth lens 140 in the direction of the optical axis OA may decrease from the optical axis OA to the end of the effective area of the seventh surface S7. In the height range in the vertical direction described above, the thickness of the fourth lens 140 in the direction of the optical axis OA may have a minimum value along the optical axis OA and a maximum value at the end of the effective area of the seventh surface S7. . At this time, the maximum value of the thickness of the fourth lens 140 in the direction of the optical axis (OA) may be about 1.5 times to about 3 times the minimum value. For example, in the embodiment, the thickness of the fourth lens 140 in the optical axis direction may be about 2.04 times the minimum value of the maximum value.

That is, in the optical system 1000 according to the embodiment, the fourth lens 140 may have the aforementioned optical axis OA direction thickness. Accordingly, the optical system 1000 can prevent deterioration of MTF characteristics in the periphery of the field of view (FOV).

In addition, the first lens 110 and the second lens 120 of the optical system 1000 according to the embodiment may be spaced apart by a first distance defined as an optical axis OA direction distance at room temperature (25° C.). . In this case, the first interval according to the height from the optical axis may be as shown in Table 8 below.

Vertical height of the optical axis from the optical axis on the sensor side of the first lens (mm) Spacing in the optical axis direction of the air gap (d12) (mm)
(first interval) Vertical height of the optical axis from the optical axis on the object side of the second lens (mm) 0 0.355 0 0.1 0.354 0.1 0.2 0.351 0.2 0.3 0.345 0.3 0.4 0.337 0.4 0.5 0.326 0.5 0.6 0.313 0.6 0.7 0.297 0.7 0.8 0.278 0.8 0.9 0.257 0.9 One 0.232 One 1.1 0.204 1.1 1.2 0.172 1.2 1.238 (L1) 0.126 1.238
(L1)

In Table 8, the point at which the height in the vertical direction is 0 from the optical axis OA means the optical axis OA. In addition, in Table 8, the point at which the height in the vertical direction is 1.238 is the sensor-side surface (second surface S2) of the first lens 110 and the object-side surface (third surface) of the second lens 120 facing each other. (S3)) means the value of the effective radius (half of the size of the effective diameter in Table 1) of the second surface S2 having a small size of the effective diameter.

Referring to Table 8, the first distance may decrease from the optical axis OA to a first point L1 located on the second surface S2. The first point L1 may be an end of the effective diameter of the second surface S2.

The first interval may have a maximum value at the optical axis OA and may have a minimum value at the first point L1. The maximum value of the first interval may be about 1.5 times to about 4 times the minimum value. For example, in an embodiment, the maximum value of the first interval may be about 2.8 times the minimum value.

In the optical system 1000 according to the embodiment, the first lens 110 and the second lens 120 may have a first distance satisfying the range according to positions. Accordingly, the optical system 1000 can effectively control the path of light incident on the optical system 1000 .

In addition, the second lens 120 and the third lens 130 of the optical system 1000 according to the embodiment may be spaced apart from each other by a second distance defined as an optical axis OA direction distance at room temperature (25° C.). . In this case, the second interval according to the height from the optical axis may be as shown in Table 9 below.

Vertical height of the optical axis from the optical axis on the sensor side of the second lens (mm) Spacing in the optical axis direction of the air gap (d23) (mm)
(second interval) Vertical height of the optical axis from the optical axis on the object side of the third lens (mm) 0 0.150 0 0.1 0.150 0.1 0.2 0.151 0.2 0.3 0.151 0.3 0.4 0.153 0.4 0.5 0.156 0.5 0.6 0.159 0.6 0.7 0.164 0.7 0.8 0.170 0.8 0.9 0.177 0.9 One 0.186 One 1.1 0.197 1.1 1.2 0.209 1.2 1.3 0.224 1.3 1.4 0.890 1.4 1.5 0.908 1.5 1.6 0.928 1.6 1.661 (L2) 0.949 1.661
(L2)

In Table 9, the point at which the height in the vertical direction is 0 from the optical axis OA means the optical axis OA. In addition, in Table 9, the point at which the height in the vertical direction is 1.661 is the sensor-side surface (fourth surface S4) of the second lens 120 and the object-side surface (fifth surface) of the third lens 130 facing each other. (S5)) means the value of the effective radius (1/2 of the size of the effective diameter in Table 1) of the fourth surface S4 having a smaller effective diameter.

Referring to Table 9, the second interval may increase from the optical axis OA toward a second point L2 located on the fourth surface S4. The second point L2 may be an end of the effective diameter of the fourth surface S4.

The second interval may have a maximum value at the second point L2 and a minimum value at the optical axis OA. The maximum value of the second interval may be about 3 times to about 10 times the minimum value. For example, in an embodiment, the maximum value of the second interval may be about 6.33 times the minimum value.

In the optical system 1000 according to the embodiment, the second lens 120 and the third lens 130 may have a second distance satisfying the range according to positions. Accordingly, the optical system 1000 can prevent deterioration of MTF characteristics in a temperature range of low to high temperatures.

In addition, the third lens 130 and the fourth lens 140 of the optical system 1000 according to the embodiment may be spaced apart by a third distance defined as an optical axis OA direction distance at room temperature (25° C.). . In this case, the second interval according to the height from the optical axis may be as shown in Table 10 below.

Vertical height of the optical axis from the optical axis on the sensor side of the third lens (mm) Spacing in the optical axis direction of the air gap (d34) (mm)
(third interval) Vertical height of the optical axis from the optical axis on the object side of the fourth lens (mm) 0 1.170 0 0.1 1.169 0.1 0.2 1.166 0.2 0.3 1.162 0.3 0.4 1.155 0.4 0.5 1.147 0.5 0.6 1.136 0.6 0.7 1.123 0.7 0.8 1.108 0.8 0.9 1.089 0.9 One 1.067 One 1.1 1.042 1.1 1.2 1.012 1.2 1.3 0.976 1.3 1.4 0.934 1.4 1.5 0.884 1.5 1.6 0.824 1.6 1.7 0.751 1.7 1.767 (L3) 0.662 1.767
(L3)

In Table 10, the point at which the height in the vertical direction is 0 from the optical axis OA means the optical axis OA. In addition, in Table 10, the point at which the height in the vertical direction is 1.767 is the sensor-side surface (sixth surface S6) of the third lens 130 and the object-side surface (seventh surface) of the fourth lens 140 facing each other. (S7)) means the value of the effective radius (1/2 of the size of the effective diameter in Table 1) of the seventh surface S7 having a smaller effective diameter.

Referring to Table 10, the third distance may decrease from the optical axis OA toward a third point L3 located on the seventh surface S7. The third point L3 may be an end of the effective diameter of the seventh surface S7.

The third interval may have a maximum value at the optical axis OA and may have a minimum value at the third point L3. The maximum value of the third interval may be about 1.1 times to about 2.5 times the minimum value. For example, in an embodiment, the maximum value of the third interval may be about 1.77 times the minimum value.

In the optical system 1000 according to the embodiment, the third lens 130 and the fourth lens 140 may have a third distance satisfying the range according to positions. Accordingly, the optical system 1000 may have good optical performance in various temperature ranges by mutually compensating the refractive index that changes according to the temperature in the low to high temperature range.

Example Diopter of the first lens (Diop_L1) (room temperature (about 25°C)) 0.1715 Diopter of the second lens (Diop_L2) (room temperature (about 25°C)) -0.3113 Diopter of the 3rd lens (Diop_L3) (Room temperature (about 25℃)) 0.4259 Diopter of the 4th lens (Diop_L3) (room temperature (about 25°C)) -0.2590 L1_ET 0.6243 mm L2_ET 1.2455 mm L3_ET 0.7379 mm L4_ET 1.5208mm CA_Max 4.623 mm CA_Min 2.274 mm CA_Aver 3.344 mm f1 (room temperature (approx. 25°C)) 5.8305 mm f2 (room temperature (approx. 25°C)) -3.2127 mm f3 (room temperature (approx. 25°C)) 2.3479 mm f4 (room temperature (approx. 25°C)) -3.8615 mm TTL (room temperature (about 25℃)) 7.1737 mm EFL (room temperature (25℃)) 5.0033 mm EFL (low temperature (-40℃)) 4.9970 mm EFL (high temperature (85℃)) 5.0104 mm F# (room temperature (25℃)) 2.2 F# (low temperature (-40℃)) 2.2 F# (high temperature (85℃)) 2.2 ImgH (room temperature (25℃)) 2.9650 mm ImgH (low temperature (-40℃)) 2.9565mm ImgH (high temperature (85℃)) 2.9630mm BFL (room temperature (25℃)) 1.2990 mm BFL (low temperature (-40℃)) 1.2945 mm BFL (high temperature (85℃)) 1.304mm Field of view (FOV) (room temperature (25℃)) 61.3032 degrees Field of View (FOV) (low temperature (-40℃)) 61.3354 degrees Field of view (FOV) (high temperature (85℃)) 61.3126 degrees

math formula Example Equation 1 1.6 < nt_1 < 1.8 Satisfaction
(nt_1= 1.667) Equation 2 1.4 < nt_2 < 1.7 Satisfaction
(nt_2= 1.531) Equation 3 nt_2 < nt_3nt_4 < nt_3
nt_2 < nt_4 Satisfaction
(nt_2= 1.531, nt_3= 1.755, nt_4= 1.694) Equation 4 dnt_1/dt < 0 dnt_2/dt < 0
dnt_3/dt < 0
dnt_4/dt < 0 Satisfaction Equation 5 5 < L2_CT / d23_CT < 5.6 5.333 Equation 6 11.3 < L3_CT / d23_CT < 12.5 12.000 Equation 7 1 < L3_CT / d34_CT < 2 1.539 Equation 8 0.1 < L4_CT / d34_CT < 1 0.684 Equation 9 0 < d23_CT / d34_CT < 0.5 0.128 Equation 10 0.1 < L4_CT / L4_ET < 1 0.526 Equation 11 -1 < L1R1 / L2R1 < 0 -0.803 Equation 12 1 < L1R1 / L2R2 < 2 1.339 Equation 13 20 < L1R2 / L1R1 < 10000 40.288 Equation 14 -3 < F1 / F2 < -1 -1.815 Equation 15 -3 < f2 / f3 < -1 -1.368 Equation 16 1 < CA_L3S2 / CA_L4S1 < 2 1.135 Equation 17 1.5 < CA_max / CA_min < 3 2.033 Equation 18 1 < CA_max / CA_Aver < 2 1.382 Equation 19 0.1 < CA_min / CA_Aver < 1 0.680 Equation 20 0.5 < CA_max / (2*ImgH) < 1 0.770 Equation 21 1 ≤ |v1 - v2| ≤ 10 Satisfaction
(v1= 48.297, v2= 55.754) Equation 22 20 ≤ |v2 - v3| ≤ 50 Satisfied (v2= 55.754, v3=27.512) Equation 23 20 ≤ |v3 - v4| ≤ 50 Satisfied (v3= 27.512, v4=53.201) Equation 24 1 < TTL < 10 Satisfactory (TTL= 7.174mm) Equation 25 2 < ImgH Satisfaction
(ImgH= 2.9650mm) Equation 26 0.6 < BFL Satisfactory (BFL= 1.299 mm) Equation 27 30 < FOV < 150 Satisfaction (61.130 degrees) Equation 28 0.5 < TTL / ImgH < 5 2.391 Equation 29 0.1 < BFL / ImgH < 0.5 0.433 Equation 30 4 < TTL / BFL < 10 5.522 Equation 31 0.1 < F / TTL < 1 0.697 Equation 32 3 < F / BFL < 8 3.852 Equation 33 1 < F / ImgH < 3 1.668

Table 11 relates to the items of the above-described equations in the optical system 1000 according to the embodiment, and the diopter values of the first to fourth lenses 110, 120, 130, and 140 at room temperature (about 25° C.) , focal length, edge thickness (ET, edge thickness), total track length (TTL) for each temperature of the optical system 1000, back focal length (BFL), F value, ImgH, effective focal length (EFL) value, etc. . Here, the edge thickness ET of the lens means the thickness in the optical axis OA direction at the end of the effective area of the lens. In detail, the edge thickness of the lens means the distance from the end of the effective area on the object side of the lens to the end of the effective area on the sensor side in the direction of the optical axis (OA).

Also, Table 12 is for the resultant values of Equations 1 to 33 in the optical system 1000 according to the embodiment.

Referring to Table 12, it can be seen that the optical system 1000 according to the embodiment satisfies at least one of Equations 1 to 33. In detail, it can be seen that the optical system 1000 according to the embodiment satisfies all of Equations 1 to 33.

Accordingly, the optical system 1000 according to the embodiment may have optical characteristics as shown in FIGS. 5 to 10 in a temperature range from low temperature (−40° C.) to high temperature (85° C.).

In detail, FIGS. 5 to 7 are data on the diffraction MTF of the optical system 1000 according to the embodiment. In detail, FIG. 5 is data for diffraction MTF in a room temperature (25° C.) environment, FIG. 6 is a low temperature (-40° C.) environment, and FIG. 7 is a diffraction MTF data in a high temperature (85° C.) environment. Referring to FIGS. 5 to 7 , it can be seen that the optical system 1000 has excellent MTF characteristics without variation in low temperature, room temperature, and high temperature environments.

8 to 10 are data on aberration diagrams of the optical system 1000 according to the embodiment. In detail, FIG. 8 is data for an aberration diagram in a room temperature (25° C.) environment, FIG. 9 is a low temperature (-40° C.) environment, and FIG. 10 is a high temperature (85° C.) environment. It is a graph in which spherical aberration, astigmatic field curves, and distortion are measured from left to right in the aberration diagrams of FIGS. 8 to 10 .

In addition, in the aberration diagrams of FIGS. 8 to 10, the X axis may indicate a focal length (mm) or distortion (%), and the Y axis may indicate the height of an image. In addition, graphs for spherical aberration, astigmatism, and distortion aberration are graphs for light in a 940 nm wavelength band.

In the aberration diagrams of FIGS. 8 to 10, it can be interpreted that the aberration correction function is better as each curve approaches the Y-axis. Referring to FIGS. It can be seen that the measured values are adjacent to the Y-axis.

Temperature (℃) MTF deviation
(@Nq/2) Center Low temperature (-40℃) 71.9 room temperature (25℃) 78.7 high temperature (85℃) 67.3

That is, referring to FIGS. 5 to 10 and Table 13, the optical system 1000 according to the embodiment changes MTF characteristics and aberration characteristics even when the temperature is changed in the range of low temperature (-40 ° C) to high temperature (85 ° C). It can be seen that there is little or no significant In detail, it can be seen that the change in MTF properties at low temperature (−40° C.) and high temperature (85° C.) is less than 15% of that at room temperature (25° C.).

Accordingly, the optical system 1000 according to the embodiment may maintain excellent optical characteristics in various temperature ranges. In detail, the optical system 1000 includes a material for which the plurality of lenses 100 are set, and as the second lens 120 and the third lens 130 are spaced apart from each other on the optical axis OA at set intervals, various temperatures It may have improved diffraction MTF control characteristics in the range.

For example, FIGS. 11 to 13 are data on the diffraction MTF according to the distance between the second and third lenses 120 and 130 in a room temperature environment (25° C.).

First, in FIG. 11, FIG. 11(b) is for the diffraction MTF when the second lens 120 and the third lens 130 are spaced apart from the optical axis OA by 0.15 mm as shown in Table 2, 11(a) shows the diffraction MTF when the second lens 120 and the third lens 130 are spaced apart by 0.145 mm from the optical axis OA, and FIG. 11(c) shows the second lens ( 120) and the third lens 130 are about 0.155 mm apart from the optical axis OA.

Referring to FIGS. 11(a), 11(b), and 11(c), the distance d23_CT between the second lens 120 and the third lens 130 on the optical axis OA is about 0.145 mm. to about 0.155 mm, it can be seen that the resolution characteristics of the periphery of the field of view (FOV) are maintained and good optical performance is obtained. That is, when each of the second lens 120 and the third lens 130 has a thickness as shown in Table 2, it can be seen that they have good optical characteristics within the range of the distance d23_CT described above.

Subsequently, in FIG. 12, FIG. 12(a) is for the diffraction MTF when the second lens 120 and the third lens 130 are separated by 0.13 mm from the optical axis OA, and FIG. 12(b) shows This is for the diffraction MTF when the second lens 120 and the third lens 130 are separated by 0.14 mm from the optical axis OA. In FIG. 13, FIG. 13(a) is for the diffraction MTF when the second lens 120 and the third lens 130 are separated by 0.16 mm from the optical axis OA, and FIG. 13(b) shows This is for the diffraction MTF when the second lens 120 and the third lens 130 are separated by 0.17 mm from the optical axis OA.

12 and 13, the distance d23_CT between the second lens 120 and the third lens 130 on the optical axis OA is out of the aforementioned range (about 0.145 mm to about 0.155 mm). Able to know. In this case, it can be seen that the resolution characteristic of the periphery of the angle of view (FOV) deteriorates as the distance d23_CT is out of the above-described range.

That is, in the optical system 1000 according to the embodiment, the second lens 120 and the third lens 130 may have a set distance along the optical axis OA. In detail, the distance between the second and third lenses 120 and 130 along the optical axis OA is the thickness of each of the second lens 120 and the third lens 130 along the optical axis OA. You can have a set ratio. Accordingly, the optical system 1000 may have improved diffraction MTF control characteristics in various temperature ranges, and may have good resolution characteristics not only in the center of the field of view (FOV) but also in the periphery.

In addition, referring to FIG. 14, the optical system 1000 according to the embodiment has good optical performance according to temperature change in the temperature range of low temperature (-40 degrees) to high temperature (85 degrees) and has set distortion characteristics. can

For example, the optical system 1000 may be based on any one of the following mapping functions of a wide-angle lens and a fisheye lens. In detail, the distance (mm) from the 0 field area to the 1 field area at the center of the image sensor 300. In detail, 1/2 of the maximum diagonal length (mm) of the effective area of the image sensor 300 is called ImgH. When the angle of view (FOV) is θ and the total focal length (mm) of the optical system 1000 is defined as F, the mapping function of the wide-angle or fisheye optical system can be defined as follows.

First, 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). In addition, orthographic mapping can be defined as ImgH = f * sin θ, and stereographic mapping can be defined as ImgH = 2 * F * tan(θ/2). In addition, Rectilinear mapping can be defined as ImgH = f * tanθ.

Referring to FIG. 14 , the optical system 1000 according to the embodiment may have set distortion characteristics compared to that of the Rectilinear mapping method (Comparative Example 3). For example, the optical system 1000 may satisfy a distortion characteristic of less than about 5% compared to Comparative Example 3 as it goes from a 0 degree field of view to a maximum half field of view (HFOV). In detail, Example may satisfy distortion characteristics within about 3% compared to Comparative Example 3. More specifically, Example may satisfy distortion characteristics within about 1.5% compared to Comparative Example 1.

In addition, the optical system 1000 according to the embodiment compares stereographic mapping (Comparative Example 1), equidistance mapping (Comparative Example 2), Equal Area mapping (Comparative Example 4), and Orthographic mapping (Comparative Example 5) to set distortion characteristics. can have For example, the optical system 1000 is about 20% as compared to Comparative Example 1, Comparative Example 2, Comparative Example 4, and Comparative Example 5 from 0 degree angle of view to the maximum half angle of view (HFOV, 1/2 of FOV). It is possible to satisfy distortion characteristics within In detail, Example may satisfy distortion characteristics of up to about 10% compared to Comparative Example 1, and may satisfy distortion characteristics of up to about 12% compared to Comparative Example 2. In addition, the embodiment may satisfy distortion characteristics of up to about 13% compared to Comparative Example 4, and may satisfy distortion characteristics of up to about 15% compared to Comparative Example 5.

Here, the ratio for the distortion characteristic may mean a value calculated as ((Comparative Example-Example)/Example * 100) for the value of ImgH at a specific half-angle position.

Accordingly, the optical system 1000 according to the embodiment may be based on the Rectilinear mapping method (Comparative Example 3). Accordingly, the optical system 1000 can prevent optical characteristics from changing due to temperature changes in the temperature range from low temperature (-40 degrees) to high temperature (85 degrees) based on the Rectilinear mapping method (Comparative Example 3), , can have improved optical performance, for example, improved distortion aberration characteristics, in various temperature ranges.

) 내지 고온(약 85

)의 온도 범위에서 광학 특성이 변화하는 것을 방지 또는 최소화할 수 있다. 따라서, 실시예에 따른 광학계(1000) 및 이를 포함하는 카메라 모듈은 다양한 온도 범위에서 양호한 광학 특성을 가질 수 있다.That is, the plurality of lenses 100 included in the optical system 1000 according to the embodiment may have a set material, refractive power, and refractive index. Accordingly, even when the focal length of each lens changes due to a change in refractive index due to a change in temperature, the first to fourth lenses 110, 120, 130, and 140 can compensate each other. That is, the optical system 1000 can effectively distribute the refractive power in a temperature range from low to high, and at a low temperature (about -40

) to high temperature (about 85

), it is possible to prevent or minimize the change in optical properties in the temperature range. Therefore, the optical system 1000 and the camera module including the optical system 1000 according to the embodiment may have good optical characteristics in various temperature ranges.

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 only one embodiment. Furthermore, the features, structures, and effects illustrated in each embodiment can be combined or modified with respect to other embodiments by those skilled in the art in the field to which the embodiments belong. Therefore, contents related to these combinations and variations should be construed as being included in the scope of the present invention. In addition, although the above has been described with a focus on the embodiments, these are only examples and do not limit the present invention, and those skilled in the art to which the present invention belongs can exemplify the above to the extent that does not deviate from the essential characteristics of the present embodiment. It will be seen that various variations and applications that have not been made are possible. For example, each component specifically shown in the embodiment can be modified and implemented. And differences related to these modifications and applications should be construed as being included in the scope of the present invention as defined in the appended claims.

Optics: 1000
1st lens: 110 2nd lens: 120
3rd lens: 130 4th lens: 140
Image Sensor: 300 Filter: 500

Claims (15)

Including first to fourth lenses disposed along the optical axis in a direction from the object side to the sensor side,
the second lens has a negative refractive power on the optical axis;
The third lens has a positive refractive power on the optical axis,
The second and third lenses satisfy the following equation.
5 < L2_CT / d23_CT < 5.6
(L2_CT means the thickness of the second lens on the optical axis, and d23_CT is the distance between the second and third lenses on the optical axis.) According to claim 1,
The second lens has a concave shape on both sides of the optical axis. According to claim 1,
The object-side surface of the first lens has a convex shape in the optical axis. According to claim 1,
The second and third lenses satisfy the following equation.
11.3 < L3_CT / d23_CT < 12.5
(L3_CT means the thickness of the third lens on the optical axis, and d23_CT is the distance between the second and third lenses on the optical axis.) According to claim 1,
The fourth lens is an optical system that satisfies the following equation.
0.1 < L4_CT / L4_ET < 1
(L4_CT denotes the thickness of the fourth lens along the optical axis. In addition, L4_ET is the thickness in the optical axis direction at the end of the effective area of the fourth lens, which is It is the distance between the ends of the effective area of the sensor-side surface of the fourth lens in the optical axis direction.) According to claim 1,
Among the first to fourth lenses, the third lens has the largest refractive index. According to claim 6,
Among the first to fourth lenses, the second lens has the smallest refractive index. According to claim 1,
The first lens and the second lens are made of different optical systems. According to claim 8,
The optical system of claim 1 , wherein the first lens is made of a glass material and the second lens is made of a plastic material. Including first to fourth lenses disposed along the optical axis in a direction from the object side to the sensor side,
the second lens has a negative refractive power on the optical axis;
The third lens has a positive refractive power on the optical axis,
The first to fourth lenses satisfy the following equation.
dnt_1/dt <0;
dnt_2/dt <0;
dnt_3/dt <0;
dnt_4/dt < 0
(dnt_1/dt, dnt_2/dt, dnt_3/dt, and dnt_4/dt are changes in the refractive index of each of the first to fourth lenses for light in the 940 nm wavelength band according to the amount of temperature change.) According to claim 10,
The first lens and the second lens are made of different optical systems. According to claim 11,
The fourth lens and the second lens are made of different optical systems. According to claim 12,
The first lens, the third lens, and the fourth lens include a glass material, and the second lens includes a plastic material. According to claim 10,
The second and third lenses satisfy the following equation.
5 < L2_CT / d23_CT < 5.6
(L2_CT means the thickness of the second lens on the optical axis, and d23_CT is the distance between the second and third lenses on the optical axis.) Including an optical system and an image sensor,
The optical system includes an optical system according to any one of claims 1 to 14,
A camera module that satisfies the following equation.
1 < TTL < 10
(TTL is the distance on the optical axis from the object side surface of the first lens to the image sensor image sensor.)

Images