KR102461801B1 - Lens optical system - Google Patents

Abstract

A lens optical system of the present invention includes a first group, a second group, a third group, a fourth group, and a fifth group including at least one lens and sequentially arranged from an object side to a sensor side between an object and a sensor on which an image of the object is formed. The first group includes a first lens having negative refractive power and a sensor-side surface concave in a paraxial direction. The second group includes a second lens having positive refractive power and at least one of an object-side surface and a sensor-side surface convex in the paraxial direction and a third lens having positive refractive power and at least one of an object-side surface and a sensor-side surface convex in the paraxial direction. The third group includes a fourth lens having positive refractive power, a fifth lens having negative refractive power, and a sixth lens having negative refractive power and having a diffractive optical element formed on at least one of an object-side surface and a sensor-side surface, wherein the fourth lens and the fifth lens are bonded to each other. The fourth group includes a seventh lens having positive refractive power and at least one of an object-side surface and a sensor-side surface convex in the paraxial direction. The fifth group includes an eighth lens having negative refractive power and formed in a meniscus shape in the paraxial direction. An aperture is located between the first group and the second group. When f1 is the focal length of the first lens and f is the focal length of the lens optical system, the following conditional expression for f1 and f is satisfied. The conditional expression is represented by |f1|/f > 2. The lens optical system of the present invention can achieve excellent optical performance not only in the visible ray band but also in the near-infrared ray band.

Description

Lens optical system

The present invention relates to a lens optical system, and more particularly, to a lens optical system that can be used not only in the visible light band but also in the near-infrared band.

A lens optical system mounted on a camera module for imaging has a form in which a plurality of lenses are arranged along an optical axis. Although it varies depending on the purpose and size of the camera module, the lens optical system mounted on recent camera modules has three or more lenses arranged to achieve various optical performance improvements, such as improving distortion caused by aberrations or having a wider angle of view. have.

Most cameras are designed to be used in a specific wavelength band. Specifically, in the case of a lens optical system mounted on a camera module that captures light in a visible ray band, it is designed to achieve the best optical performance in a wavelength band of about 400 nm to 800 nm. And, in the case of a lens optical system mounted on a thermal imaging camera module using near-infrared light, it is designed to achieve the best optical performance in a wavelength band of approximately 800 nm to 1100 nm.

In the case of recent optical devices such as night vision goggles, when the external illuminance is sufficiently high, the image is captured by receiving light in the visible ray band, and when the external illuminance is low, light in the near-infrared band is received and imaged. In the case of such an optical device, a lens optical system for a visible ray band and a lens optical system for an infrared band are respectively mounted, and in many cases, one lens optical system is selected and used according to a mode of use.

However, in the case of an optical device in which a plurality of lens optical systems according to the wavelength band are mounted and one of them is selected and used, the unit cost is high and miniaturization is difficult because there are a plurality of lens optical systems. There was a problem that durability may be reduced.

Republic of Korea Patent Registration No. 10-0576874 (2006.04.27)

The problem to be solved by the present invention is to solve the above problems, and an object of the present invention is to provide a lens optical system capable of achieving excellent optical performance not only in the visible light band but also in the near infrared band.

Another object to be solved by the present invention is to provide a lens optical system that is easy to design change so that appropriate optical performance is achieved even if it is linked with an image intensifier having a cover glass having a different thickness.

The lens optical system of the present invention is sequentially arranged from the object side to the sensor side between an object and a sensor on which an image of the object is formed, and a first group, a second group, a third group, and a fourth group including at least one lens and a fifth group, wherein the first group has a negative refractive power, a sensor side surface includes a first lens concave at paraxial, the second group has a positive refractive power, an object side surface and a sensor At least one of the side surfaces comprises a paraxially convex second lens and a positive refractive power, at least one of the object side and the sensor side includes a paraxially convex third lens, wherein the third group includes a fourth having positive refractive power a lens, a fifth lens having a negative refractive power, and a sixth lens having a negative refractive power and a diffractive optical element formed on at least one of an object side surface and a sensor side surface - the fourth lens and the fifth lens are bonded to each other , wherein the fourth group has a positive refractive power, at least one of the object-side surface and the sensor-side surface comprises a seventh lens that is paraxially convex, the fifth group has a negative refractive power, and has a meniscus shape at paraxial Including an eighth lens formed by , an iris is positioned between the first group and the second group, f1 is the focal length of the first lens, and f is the focal length of the lens optical system, below f1 and The conditional expression for f is satisfied.

<conditional expression>

|f1|/f > 2

In an embodiment of the present invention, the object-side surface of the first lens may be paraxially convex.

In one embodiment of the present invention, at least one of the second lens and the third lens may be convex on both the object side surface and the sensor side surface.

In an embodiment of the present invention, the fourth lens, the fifth lens, and the sixth lens may be sequentially arranged from the object side to the sensor side in order.

In one embodiment of the present invention, the diffractive optical element may be formed on the object side surface of the sixth lens.

In one embodiment of the present invention, the seventh lens may be convex on both the object side surface and the sensor side surface.

In one embodiment of the present invention, the sixth lens, the fifth lens, and the fourth lens may be sequentially arranged from the object side to the sensor side in order.

In one embodiment of the present invention, the diffractive optical element may be formed on the sensor side of the sixth lens.

In one embodiment of the present invention, the seventh lens may be formed in a meniscus shape at the paraxial axis.

In one embodiment of the present invention, the sixth lens may be formed in a meniscus shape at the paraxial axis.

In one embodiment of the present invention, at least one of the object-side surface and the sensor-side surface of the eighth lens may have at least one inflection point within the effective diameter.

In one embodiment of the present invention, the first lens may be a plastic lens, and the second group may include at least one glass lens.

In one embodiment of the present invention, the fourth lens and the fifth lens may be a glass lens, and the sixth lens may be a plastic lens.

In one embodiment of the present invention, when V2 is the Abbe number of the second lens, V3 is the Abbe number of the third lens, and V7 is the Abbe number of the seventh lens, V2 below, The conditional expressions for V3 and V7 may be satisfied.

<conditional expression>

45 < (V2+V3+V7)/3 < 55

In one embodiment of the present invention, FSL is the distance on the optical axis between the diaphragm and the object-side surface of the first lens, and TTL is the distance on the optical axis from the object-side surface of the first lens to the sensor. , the following conditional expressions for FSL and TTL may be satisfied.

<conditional expression>

0.1 < FSL/TTL < 0.2

In one embodiment of the present invention, when L1R is the maximum outer diameter at the effective diameter of the object side of the first lens and ImageR is the maximum outer diameter in the effective area of the sensor, the conditional expressions for L1R and ImageR below can be satisfied

<conditional expression>

1.1 < L1R/ImageR < 1.4

In one embodiment of the present invention, the fringe at the auxiliary wavelength of 1100 nm of the diffractive optical element is determined by the following conditional formula, and R is the maximum outer diameter in the effective diameter of the diffractive optical element, the fringe below and a conditional expression for R may be satisfied.

fringe = (1/1100) X (R2 R ² + R4 R ⁴ + R6 R ⁶ + R8 R ⁸ )

(The R2 is the radius of curvature of the second pattern of the diffractive optical element, R4 is the radius of curvature of the fourth pattern of the diffractive optical element, and R6 is the radius of curvature of the sixth pattern of the diffractive optical element, and the R8 is the radius of curvature of the 8th-order pattern of the diffractive optical element)

<conditional expression>

|fringe|/R < 8

In one embodiment of the present invention, in the lens optical system, the change amount of the focal length in a wavelength band of 400 nm to 1000 nm may be less than 1.0%.

The lens optical system of the present invention has the advantage that excellent optical performance can be achieved not only in the visible light band but also in the near infrared band.

In addition, the lens optical system of the present invention has the advantage that it is easy to change the design so that appropriate optical performance is achieved even if it is linked with image intensifiers having cover glasses of different thicknesses.

1 is a view showing a lens optical system according to an embodiment of the present invention.
2 is a view showing a lens optical system according to another embodiment of the present invention.
3 is a view showing a lens optical system according to another embodiment of the present invention.

Hereinafter, the embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings, but the same or similar components are assigned the same reference numerals regardless of reference numerals, and redundant description thereof will be omitted. In addition, in describing the embodiments disclosed in the present specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in this specification, the detailed description thereof will be omitted.

Terms including ordinal numbers such as first, second, etc. may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

The singular expression includes the plural expression unless the context clearly dictates otherwise.

In the present application, each of the steps described may be performed regardless of the listed order, except for a case where they must be performed in the listed order due to a special causal relationship.

In the present application, terms such as “comprises” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It is to be understood that this does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, a lens optical system according to a first embodiment of the present invention will be described with reference to FIG. 1 .

1 is a lens configuration diagram of a lens optical system according to an embodiment of the present invention.

Referring to FIG. 1, the lens optical system of the present invention provides a first group (G1), a second group (G2), a third group (G3), A fourth group (G4) and a fifth group (G5) are located. The first to fifth groups G1 to G5 are sequentially arranged from the object side to the sensor IS side.

Each lens has two sides facing each other. In one lens, the surface facing the object corresponds to the incident surface, which is the surface through which light enters the lens. In addition, in one lens, a surface facing the sensor IS corresponds to an emitting surface that is a surface through which light exits from the lens. In this specification, the object side and the incident surface of the n-th lens are denoted by Sn1, and the sensor side and the exit plane are denoted by Sn2. Accordingly, the object-side and incident surface of the first lens L1 is indicated by S11, and the sensor-side and exit surface is indicated by S12. In addition, the object-side and incident surface of the second lens L2 is indicated by S21, and the sensor-side and emitting surface is indicated by S22. In this way, the object-side and incident surface of the eighth lens L8 is indicated by S81, and the sensor-side and output surface is indicated by S82.

The lens optical system includes a stop S. The diaphragm S may block a portion of light to control the amount of light irradiated into the lens optical system. The diaphragm S is positioned between the first group G1 and the second group G2.

The sensor IS may be an image sensor IS that receives light passing through a lens and converts it into an electrical signal. The sensor IS is positioned at the rear of the fifth group G5 so that the light passing through the lenses of the first to fifth groups G5 forms an image on the object side surface of the sensor IS.

The lens optical system of the present invention may be located in front of an image intensitifer (not shown). That is, the lens optical system of the present invention is located closer to the object side than the image intensifier. The image intensifier corresponds to an image amplifier or an optical amplifier, and includes a vacuum container provided with a photofront, an electron multiplier that is accommodated in the vacuum container and multiplies the electrons emitted from the photoelectric conversion film, and the electron multiplier. It may be a device having a fluorescent surface into which electrons multiplied by the ray are incident and the electrons multiplied by the electron multiplication means are converted into light.

The image intensifier may further include a cover glass (CG). The cover glass CG may have both surfaces formed with a flat surface. The cover glass CG may be positioned on the side of the object of the image intensifier. Therefore, in the lens optical system of the present invention, the lens located closest to the sensor may be positioned to face the cover glass CG.

Each group of the lens optical system of the present invention and the lens included in the group have the following characteristics.

The first group G1 includes a first lens L1 .

The first lens L1 has negative (-, negative) refractive power. The first lens L1 is formed of a plastic material, and it is preferable that the plastic forming the first lens L1 has a refractive index greater than 1.65 and less than 1.85. And it is preferable that the Abbe number (V1) of the first lens (L1) is greater than 40 and less than 60.

The object-side surface S11 of the first lens L1 is paraxially convex. Here, the paraxial means a portion close to the optical axis, and means a portion close to the optical axis in the effective diameter of the lens. The object-side surface S11 of the first lens L1 has a positive radius of curvature with respect to the paraxial axis. The object-side surface S11 of the first lens L1 may be formed without an inflection point within the effective diameter. The object-side surface S11 of the first lens L1 may be formed as an aspherical surface.

The sensor side surface S12 of the first lens L1 is paraxially concave. The radius of curvature based on the paraxial axis of the sensor side surface S12 of the first lens L1 has a positive value. The sensor side surface S12 of the first lens L1 is concave even within the effective diameter. The sensor side surface S12 of the first lens L1 may be formed without an inflection point within the effective diameter. The sensor side surface S12 of the first lens L1 may be formed as an aspherical surface.

The second group G2 includes a second lens L2 and a third lens L3. The second lens L2 and the third lens L3 are sequentially arranged from the object side to the sensor side direction.

The second lens L2 has positive (+, positive) refractive power. The second lens L2 is formed of a glass material, and the refractive index of the glass forming the second lens L2 is preferably greater than 1.65 and less than 1.80. And it is preferable that the Abbe number (V2) of the second lens (L2) is greater than 45 and less than 55.

The object-side surface S21 of the second lens L2 is paraxially convex. The object-side surface S21 of the second lens L2 has a positive radius of curvature with respect to the paraxial axis. The object-side surface S21 of the second lens L2 is convex even within the effective diameter. The object-side surface S21 of the second lens L2 may be formed without an inflection point within the effective diameter. The object-side surface S21 of the second lens L2 may be formed as a spherical surface.

The sensor side surface S22 of the second lens L2 is paraxially convex. A radius of curvature based on the paraxial axis of the sensor side surface S22 of the second lens L2 has a negative value. The sensor side surface S22 of the second lens L2 is convex even within the effective diameter. The sensor side surface S22 of the second lens L2 may be formed without an inflection point within the effective diameter. The sensor side surface S22 of the second lens L2 may be formed in a spherical shape.

The third lens L3 has positive (+, positive) refractive power. The third lens L3 is formed of a glass material, and the glass forming the third lens L3 preferably has a refractive index greater than 1.60 and less than 1.70. The refractive index of the third lens L3 may be smaller than that of the second lens L2 . And it is preferable that the Abbe number (V3) of the third lens (L3) is greater than 50 and less than 62.

The object-side surface S31 of the third lens L3 is paraxially convex. The object-side surface S31 of the third lens L3 has a positive radius of curvature with respect to the paraxial axis. The object-side surface S31 of the third lens L3 is convex even within the effective diameter. The object-side surface S31 of the third lens L3 may be formed without an inflection point within the effective diameter. The object-side surface S31 of the third lens L3 may be formed as a spherical surface.

The sensor side surface S32 of the third lens L3 is paraxially convex. A radius of curvature with respect to the paraxial axis of the sensor side surface S32 of the third lens L3 has a negative value. The sensor side surface S32 of the third lens L3 is convex even within the effective diameter. The sensor side surface S32 of the third lens L3 may be formed without an inflection point within the effective diameter. The sensor side surface S32 of the third lens L3 may be formed in a spherical shape.

The third group G3 includes a fourth lens L4 , a fifth lens L5 , and a sixth lens L6 . In the third group G3 , the arrangement order of the fourth lens L4 , the fifth lens L5 , and the sixth lens L6 may be changed. In this embodiment described with reference to FIG. 1 , the fourth lens L4 , the fifth lens L5 , and the sixth lens L6 are sequentially arranged from the object side to the sensor side direction.

The fourth lens L4 has positive (+, positive) refractive power. The fourth lens L4 is formed of a glass material, and the refractive index of the glass forming the fourth lens L4 is preferably greater than 1.75 and less than 1.85. And it is preferable that the Abbe number (V4) of the fourth lens (L4) is greater than 25 and less than 58.

The object-side surface S41 of the fourth lens L4 is paraxially convex. The object-side surface S41 of the fourth lens L4 has a positive radius of curvature with respect to the paraxial axis. The object side surface S41 of the fourth lens L4 is convex even within the effective diameter. The object side surface S41 of the fourth lens L4 may be formed without an inflection point within the effective diameter. The object-side surface S41 of the fourth lens L4 may be formed as a spherical surface.

The sensor side surface S42 of the fourth lens L4 is paraxially convex. A radius of curvature based on the paraxial axis of the sensor side surface S42 of the fourth lens L4 has a negative value. The sensor side surface S42 of the fourth lens L4 is convex even within the effective diameter. The sensor side surface S42 of the fourth lens L4 may be formed without an inflection point within the effective diameter. The sensor side surface S42 of the fourth lens L4 may be formed in a spherical shape.

The fifth lens L5 has negative (-, negative) refractive power. The fifth lens L5 is formed of a glass material, and the refractive index of the glass forming the fifth lens L5 is preferably greater than 1.75 and less than 1.85. And it is preferable that the Abbe number (V5) of the fifth lens (L5) is greater than 25 and less than 58.

The object-side surface S51 of the fifth lens L5 is paraxially concave. The object-side surface S51 of the fifth lens L5 has a negative radius of curvature with respect to the paraxial axis. The object side surface S51 of the fifth lens L5 is concave even within the effective diameter. The object side surface S51 of the fifth lens L5 may be formed without an inflection point within the effective diameter. The object-side surface S51 of the fifth lens L5 may be formed as a spherical surface.

The sensor side surface S52 of the fifth lens L5 is paraxially concave. A radius of curvature based on the paraxial axis of the sensor side surface S52 of the fifth lens L5 has a positive value. The sensor side surface S52 of the fifth lens L5 is concave even within the effective diameter. The sensor side surface S52 of the fifth lens L5 may be formed without an inflection point within the effective diameter. The sensor side surface S52 of the fifth lens L5 may be formed in a spherical shape.

The fourth lens L4 and the fifth lens L5 may be doublet lenses bonded to each other. That is, the sensor-side surface S42 of the fourth lens L4 and the object-side surface S51 of the fifth lens L5 are bonded to each other. Therefore, the separation distance between the fourth lens L4 and the fifth lens L5 may be expressed as 0. In addition, the sensor-side surface S42 of the fourth lens L4 and the object-side surface S51 of the fifth lens L5 may have surface shapes corresponding to each other.

The sixth lens L6 has negative (-, negative) refractive power. The sixth lens L6 is formed of a plastic material, and the plastic forming the sixth lens L6 preferably has a refractive index greater than 1.50 and less than 1.55. And it is preferable that the Abbe number (V6) of the sixth lens (L6) is greater than 50 and less than 58.

The object-side surface S61 of the sixth lens L6 is paraxially concave. The object-side surface S61 of the sixth lens L6 has a negative radius of curvature with respect to the paraxial axis. The object side surface S61 of the sixth lens L6 is concave even within the effective diameter. The object side surface S61 of the sixth lens L6 may be formed without an inflection point within the effective diameter. The object-side surface S61 of the sixth lens L6 may be formed as an aspherical surface.

The sensor side surface S62 of the sixth lens L6 may be paraxially concave. However, the sensor side surface S62 of the sixth lens L6 may have a substantially convex shape in the entire effective mirror. If the sensor side S62 of the sixth lens L6 is concave in paraxial but substantially convex in the entire effective diameter, it means that there is at least one inflection point on the sensor side S62 of the sixth lens L6. can

Accordingly, the sixth lens L6 may be formed in a meniscus shape. A radius of curvature based on the paraxial axis of the sensor side surface S62 of the sixth lens L6 has a positive value. The sensor side surface S62 of the sixth lens L6 may be formed as an aspherical surface.

Diffractive optical elements (DOE) may be formed on any one of the object-side surface S61 and the sensor-side surface S62 of the sixth lens L6. The diffractive optical element refers to an element using diffraction by periodic structures rather than refraction or reflection to control light in an optical system.

In the first embodiment, a diffractive optical element is formed on the object-side surface S61 of the sixth lens L6.

The fringe at the auxiliary wavelength of 1100 nm of the diffractive optical element is determined by the following conditional expression.

fringe = (1/1100) X (R2 R ² + R4 R ⁴ + R6 R ⁶ + R8 R ⁸ )

Here, R is the maximum outer diameter in the effective diameter of the diffractive optical element, R2 is the radius of curvature of the secondary pattern of the diffractive optical element, R4 is the radius of curvature of the fourth pattern of the diffractive optical element, R6 is the radius of curvature of the diffractive optical element It is the radius of curvature of the 6th-order pattern, and R8 is the radius of curvature of the 8th-order pattern of the diffractive optical element.

In this case, the diffractive optical element may satisfy the following conditional expressions for the fringe and R.

<conditional expression>

|fringe|/R < 8

Here, |fringe|/R means the number of fringes per unit length. If the number of fringes per unit length in the diffractive optical element is 8 or more, there is a problem that processing of the diffractive optical element is difficult and a large loss occurs. Therefore, it is preferable that the number of fringes per unit length is less than 8 in order to ensure ease of processing and reduction of loss while achieving appropriate diffraction.

The fourth group G4 includes a seventh lens L7.

The seventh lens L7 has positive (+, positive) refractive power. The seventh lens L7 is formed of a glass material, and the glass forming the seventh lens L7 preferably has a refractive index greater than 1.80 and less than 1.85. And it is preferable that the Abbe number (V7) of the seventh lens (L7) is greater than 40 and less than 48.

The object-side surface S71 of the seventh lens L7 is paraxially convex. The object-side surface S71 of the seventh lens L7 has a positive radius of curvature with respect to the paraxial axis. The object-side surface S71 of the seventh lens L7 is convex even within the effective diameter. The object side surface S71 of the seventh lens L7 may be formed without an inflection point within the effective diameter. The object-side surface S71 of the seventh lens L7 may be formed as a spherical surface.

The sensor side surface S72 of the seventh lens L7 is paraxially convex. The radius of curvature based on the paraxial axis of the sensor side surface S72 of the seventh lens L7 has a negative value. The sensor side surface S72 of the seventh lens L7 is convex even within the effective diameter. The sensor side surface S72 of the seventh lens L7 may be formed without an inflection point within the effective diameter. The sensor side surface S72 of the seventh lens L7 may be formed in a spherical shape.

The fifth group G5 includes an eighth lens L8.

The eighth lens L8 has positive (+, positive) refractive power. The eighth lens L8 is formed of a plastic material, and the plastic forming the eighth lens L8 preferably has a refractive index greater than 1.50 and less than 1.55. And it is preferable that the Abbe number (V8) of the eighth lens (L8) is greater than 52 and less than 58.

The object-side surface S81 of the eighth lens L8 is paraxially convex. The object-side surface S81 of the eighth lens L8 has a positive radius of curvature with respect to the paraxial axis. The object-side surface S81 of the eighth lens L8 includes at least one inflection point within the effective diameter. Therefore, the object-side surface S81 of the eighth lens L8 may have a concave portion near the non-paraxial axis within the effective diameter. The object-side surface S81 of the eighth lens L8 is formed as an aspherical surface.

The sensor side surface S82 of the eighth lens L8 is paraxially concave. The sensor side surface S82 of the eighth lens L8 has a positive radius of curvature with respect to the paraxial axis. The sensor side surface S82 of the eighth lens L8 includes at least one inflection point within the effective diameter. Accordingly, the sensor side surface S82 of the eighth lens L8 may have a convex portion near the non-paraxial axis within the effective diameter. The sensor side surface S82 of the eighth lens L8 is formed as an aspherical surface.

A cover glass CG of the intensifier may be positioned at the rear end of the eighth lens L8. The thickness of the cover glass CG may be variously determined. However, the optical design of the lens optical system may be changed according to the thickness of the cover glass CG.

An image sensor is coupled to the rear surface (opposite surface of the object side) of the cover glass CG. The rear surface of the cover glass CG and the image sensor may be directly contacted and coupled, so that the distance therebetween may be displayed as substantially zero.

The lens optical system of the present invention satisfies the following Conditional Expressions 1 to 4.

<Condition 1>

|f1|/f > 2

Here, f1 is the focal length of the first lens L1, and f is the focal length of the lens optical system of the present invention. Since the absolute value of the focal length of the first lens L1 is greater than twice the focal length of the lens optical system, distortion correction of the entire lens optical system is facilitated. If the absolute value of the focal length of the first lens L1 is less than twice the focal length of the lens optical system, the negative power of the first lens L1 increases, and distortion correction due to this in the entire lens optical system is increased. The problem is that it gets difficult.

<Condition 2>

45 < (V2+V3+V7)/3 < 55

Here, V2 is the Abbe number of the second lens L2, V3 is the Abbe number of the third lens L3, and V7 is the Abbe number of the seventh lens L7. According to Conditional Expression 2, a high dispersion lens is disposed at positions corresponding to the second lens, the third lens, and the seventh lens, thereby suppressing color dispersion.

<Condition 3>

0.1 < FSL/TTL < 0.2

Here, FSL is the distance on the optical axis between the object-side surface of the first lens L1 and the stopper S, and TTL is the distance on the optical axis from the object-side surface of the first lens L1 to the sensor. The position of the diaphragm in the entire lens optical system is determined by Conditional Expression 3. In the present invention, the diaphragm is positioned between the first lens L1 and the second lens L2.

<Condition 4>

1.1 < L1R/ImageR < 1.4

Here, L1R is the maximum outer diameter at the effective diameter of the object side surface of the first lens L1, and ImageR is the maximum outer diameter in the effective area of the sensor. There is an advantage in that the overall size of the lens optical system can be reduced by satisfying the condition (4).

In the lens optical system of the present invention, it is preferable that the amount of change of the focal length in the wavelength band of 400 nm to 1000 nm is less than 5%. Specifically, the lens optical system shown in FIG. 1 has a focal length of 19.228 mm in the reference wavelength band of 656 nm. However, the focal length may be 19.251 mm in the 1000 nm band, while the focal length may be 19.248 mm in the 400 nm band. In the lens optical system shown in FIG. 1 , the case with the longest focal length is 0.12% greater than the case with the shortest focal length.

As described above, the lens optical system of the present invention has the advantage that it can be commonly used not only in the visible band but also in the near-infrared band because the change in the focal length is adjusted to 5% or less in the near-infrared band as well as in the visible light band.

The table below describes the optical characteristics of the lens optical system according to the first embodiment of the present invention shown in FIG. 1 .

Component r d N f V first group (G1) first lens (L1) S11* 226.26 1.800 1.667 -47.34 55.12 S12* 27.46 4.400 Aperture (S) ∞ 2.700 2nd group (G2) second lens (L2) S21 29.47 5.000 1.659 36.47 50.87 S22 -117.20 1.000 third lens (L3) S31 25.09 5.000 1.65 34.93 55.90 S32 -212.00 0.300 3rd group (G3) 4th lens (L4) S41 16.41 4.300 1.773 18.28 49.61 S42 -85.85 0 5th lens (L5) S51 -85.85 3.300 1.805 -10.63 25.48 S52 9.55 1.500 6th lens (L6) S61* -539.87 2.550 1.53 -238.81 55.75 S62* 115.68 0.800 4th group (G4) 7th lens (L7) S71 70.62 3.550 1.803 22.80 46.59 S72 -24.00 0.300 5th group (G5) 8th lens (L8) S81* 8.80 1.500 1.531 -60.23 55.75 S82* 6.48 1.800 cover glass ∞ 5.600 1.486 ∞ 70.44 ∞ 0 Focal length(F) 19.23 Total Track Length (TTL) 45.40 Image height 16.00 Chief Ray Angle (CRA) 12.21 F No. 1.20 DFOV 45.84

In the table above, * indicated on the lens surface indicates that the lens surface is an aspherical surface. In the table above, r is the radius of curvature of the corresponding lens surface, d is the thickness on the optical axis of the lens when the corresponding lens surface is the object side surface, and when the corresponding lens surface is the sensor side, the output of the corresponding lens It is the distance between the next component (lens, diaphragm (S) or filter) in a plane. For example, d in S32 means a distance between the sensor-side surface S32 of the third lens L3 and a lens positioned at the rear side of the third lens L3. N is the refractive index of the corresponding lens, f is the focal length of the corresponding lens, V is the Abbe number of the corresponding lens (Abbe number). Here, the distance units of r, d and f are mm. Focal Length (F) is the focal length of the entire lens optical system, Image height is half the diagonal length of the sensor IS, and TTL is the total track distance of the lens optical system ( Specifically as the total track length), it is the distance on the optical axis from the object side surface S11 of the first lens L1 to the sensor IS, CRA is the maximum value of the chief ray angle of the lens optical system, and DFOV is It is the angle of view of the lens optics. Here, the units of F and TTL are mm, and the angles of CRA and HFOV are degrees.

The aspherical surface of the lens surface of the lens optical system according to the first embodiment of the present invention shown in FIG. 1 satisfies the aspherical surface equation of the following equation.

<Equation>

Here, z denotes a distance from the vertex of the lens in the direction of the optical axis, and y denotes a distance in a direction perpendicular to the optical axis. And R represents the radius of curvature at the vertex of the lens, and K represents a conic constant. In addition, A 2 to A 12 each represent an aspheric coefficient.

The table below is a table relating to the aspheric coefficient of the aspherical surface of the lens optical system according to the first embodiment of the present invention shown in FIG. 1 .

K A2 A4 A6 A8 A10 A12 S11 -7.85 -4.49 x 10 ^-5 5.69 x 10 ^-7 -1.79 x 10 ^-9 -3.78 x 10 ^-11 4.76 x 10 ^-13 -1.58 x 10 ^-15 S12 -3.82 -9.17 x 10 ^-6 7.64 x 10 ^-7 -7.26 x 10 ^-9 6.88 x 10 ^-11 -6.19 x 10 ^-13 3.09 x 10 ^-15 S61 -10 -2.77 x 10 ^-4 1.06 x 10 ^-5 -2.17 x 10 ^-7 -4.57 x 10 ^-9 3.13 x 10 ^-10 -4.28 x 10 ^-12 S62 -10 -6.31 x 10 ^-4 3.09 x 10 ^-5 -9.37 x 10 ^-7 1.65 x 10 ^-8 -1.20 x 10 ^-10 -1.16 x 10 ^-14 S81 -7.37 -1.32 x 10 ^-3 -3.24 x 10 ^-6 7.01 x 10 ^-7 -1.89 x 10 ^-8 2.18 x 10 ^-10 -1.30 x 10 ^-12 S82 -3.54 -1.47 x 10 ^-3 1.71 x 10 ^-5 -1.07 x 10 ^-7 -1.60 x 10 ^-9 2.45 x 10 ^-11 -1.23 x 10 ^-13

1 and the above two tables, each lens of the lens optical system according to the first embodiment of the present invention satisfies the above-described characteristics. is calculated as the value of

conditional expression target value Target value of the first embodiment conditional expression 1 |f1|/f > 2 |f1|/f 2.46 condition 2 45 < (V2+V3+V7)/3 < 55 (V2+V3+V7)/3 54.17 conditional expression 3 0.1 < FSL/TTL < 0.2 FSL/TTL 0.16 condition 4 1.1 < L1R/ImageR < 1.4 L1R/ImageR 1.25

As shown in the above table, it can be seen that the lens optical system of the first embodiment of the present invention satisfies all of Conditions 1 to 4.

Hereinafter, a lens optical system according to a second embodiment of the present invention will be described with reference to FIG. 2 .

2 is a lens configuration diagram of a lens optical system according to an embodiment of the present invention. While the second embodiment will be described with reference to FIG. 2 , different points from the first embodiment will be mainly described.

The third group G3 includes a fourth lens L4 , a fifth lens L5 , and a sixth lens L6 . In the third group G3 , the arrangement order of the fourth lens L4 , the fifth lens L5 , and the sixth lens L6 may be changed. In this embodiment described with reference to FIG. 2 , the sixth lens L6 , the fifth lens L5 , and the fourth lens L4 are sequentially arranged from the object side to the sensor side direction.

Among the lenses of the third group G3, the sixth lens L6 located closest to the object has negative (-, negative) refractive power. The sixth lens L6 is formed of a plastic material, and the plastic forming the sixth lens L6 preferably has a refractive index greater than 1.50 and less than 1.55. And it is preferable that the Abbe number (V6) of the sixth lens (L6) is greater than 50 and less than 58.

The object-side surface S61 of the sixth lens L6 is paraxially convex. The object-side surface S61 of the sixth lens L6 has a positive radius of curvature with respect to the paraxial axis. The object side surface S61 of the sixth lens L6 is convex even within the effective diameter. The object side surface S61 of the sixth lens L6 may be formed without an inflection point within the effective diameter. The object-side surface S61 of the sixth lens L6 may be formed as an aspherical surface.

The sensor side surface S62 of the sixth lens L6 is paraxially concave. Accordingly, the sixth lens L6 may be formed in a meniscus shape. The radius of curvature with respect to the paraxial axis of the sensor side surface S62 of the sixth lens L6 has a negative value. The sensor side surface S62 of the sixth lens L6 is concave even within the effective diameter. The sensor side surface S62 of the sixth lens L6 may be formed without an inflection point within the effective diameter. The sensor side surface S62 of the sixth lens L6 may be formed as an aspherical surface.

Diffractive optical elements (DOE) may be formed on any one of the object-side surface S61 and the sensor-side surface S62 of the sixth lens L6. The diffractive optical element refers to an element using diffraction by periodic structures rather than refraction or reflection to control light in an optical system.

In the second embodiment, a diffractive optical element is formed on the sensor side surface S62 of the sixth lens L6.

In the second embodiment, the sensor side surface S72 of the seventh lens L7 may be paraxially concave. The sensor side surface S72 of the seventh lens L7 may be formed in a concave shape throughout the effective mirror. Therefore, the seventh lens L7 may be formed in a meniscus shape.

The radius of curvature based on the paraxial axis of the sensor side surface S72 of the seventh lens L7 has a positive value. The sensor side surface S72 of the seventh lens L7 may be formed in a spherical shape.

The fringe at the auxiliary wavelength of 1100 nm of the diffractive optical element is determined by the following conditional expression.

fringe = (1/1100) X (R2 R ² + R4 R ⁴ + R6 R ⁶ + R8 R ⁸ )

Here, R is the maximum outer diameter in the effective diameter of the diffractive optical element, R2 is the radius of curvature of the secondary pattern of the diffractive optical element, R4 is the radius of curvature of the fourth pattern of the diffractive optical element, R6 is the radius of curvature of the diffractive optical element It is the radius of curvature of the 6th-order pattern, and R8 is the radius of curvature of the 8th-order pattern of the diffractive optical element.

In this case, the diffractive optical element may satisfy the following conditional expressions for the fringe and R.

<conditional expression>

|fringe|/R < 8

Here, |fringe|/R means the number of fringes per unit length. If the number of fringes per unit length in the diffractive optical element is 8 or more, there is a problem that processing of the diffractive optical element is difficult and a large loss occurs. Therefore, it is preferable that the number of fringes per unit length is less than 8 in order to ensure ease of processing and reduction of loss while achieving appropriate diffraction.

In the second embodiment, the fifth lens L5 is positioned on the sensor side of the sixth lens L6. The fifth lens L5 has negative (-, negative) refractive power. The fifth lens L5 is formed of a glass material, and the refractive index of the glass forming the fifth lens L5 is preferably greater than 1.75 and less than 1.85. And it is preferable that the Abbe number (V5) of the fifth lens (L5) is greater than 25 and less than 58.

The object-side surface S51 of the fifth lens L5 is paraxially concave. The object-side surface S51 of the fifth lens L5 has a negative radius of curvature with respect to the paraxial axis. The object side surface S51 of the fifth lens L5 is concave even within the effective diameter. The object side surface S51 of the fifth lens L5 may be formed without an inflection point within the effective diameter. The object-side surface S51 of the fifth lens L5 may be formed as a spherical surface.

The sensor side surface S52 of the fifth lens L5 is paraxially concave. A radius of curvature based on the paraxial axis of the sensor side surface S52 of the fifth lens L5 has a positive value. The sensor side surface S52 of the fifth lens L5 is concave even within the effective diameter. The sensor side surface S52 of the fifth lens L5 may be formed without an inflection point within the effective diameter. The sensor side surface S52 of the fifth lens L5 may be formed in a spherical shape.

In the second embodiment, the fourth lens L4 is positioned on the sensor side of the fifth lens L5. The fourth lens L4 has positive (+, positive) refractive power. The fourth lens L4 is formed of a glass material, and the refractive index of the glass forming the fourth lens L4 is preferably greater than 1.75 and less than 1.85. And it is preferable that the Abbe number (V4) of the fourth lens (L4) is greater than 25 and less than 58.

The object-side surface S41 of the fourth lens L4 is paraxially convex. The object-side surface S41 of the fourth lens L4 has a positive radius of curvature with respect to the paraxial axis. The object side surface S41 of the fourth lens L4 is convex even within the effective diameter. The object side surface S41 of the fourth lens L4 may be formed without an inflection point within the effective diameter. The object-side surface S41 of the fourth lens L4 may be formed as a spherical surface.

The sensor side surface S42 of the fourth lens L4 is paraxially convex. A radius of curvature based on the paraxial axis of the sensor side surface S42 of the fourth lens L4 has a negative value. The sensor side surface S42 of the fourth lens L4 is convex even within the effective diameter. The sensor side surface S42 of the fourth lens L4 may be formed without an inflection point within the effective diameter. The sensor side surface S42 of the fourth lens L4 may be formed in a spherical shape.

The fourth lens L4 and the fifth lens L5 may be doublet lenses bonded to each other. That is, the object-side surface S41 of the fourth lens L4 and the sensor-side surface S52 of the fifth lens L5 are bonded to each other. Therefore, the separation distance between the fourth lens L4 and the fifth lens L5 may be expressed as 0. In addition, the object-side surface S41 of the fourth lens L4 and the sensor-side surface S52 of the fifth lens L5 may have surface shapes corresponding to each other.

In the lens optical system of the present invention, it is preferable that the amount of change of the focal length in the wavelength band of 400 nm to 1000 nm is less than 5%. Specifically, the lens optical system shown in FIG. 1 has a focal length of 17.049 mm in the reference wavelength band of 656 nm. However, the focal length may be 17.026 mm in the 1000 nm band, while the focal length may be 17.079 mm in the 400 nm band. In the lens optical system shown in FIG. 1 , the case with the longest focal length is 0.31% greater than the case with the shortest focal length.

As described above, the lens optical system of the present invention has the advantage that it can be commonly used not only in the visible band but also in the near-infrared band because the change in the focal length is adjusted to 5% or less in the near-infrared band as well as in the visible light band.

The table below describes the optical characteristics of the lens optical system according to the second embodiment of the present invention shown in FIG. 2 .

Component r d N f V first group (G1) first lens (L1) S11* 667.08 1.800 1.80 -43.88 40.89 S12* 33.31 4.748 Aperture (S) ∞ 1.901 2nd group (G2) second lens (L2) S21 35.75 2.599 1.77 36.78 49.61 S22 -130.31 1.800 third lens (L3) S31 22.87 3.099 1.62 30.52 60.37 S32 -101.51 2.301 3rd group (G3) 6th lens (L6) S61* 11.5927 3.01 1.53 -80.00 55.75 S62* -8.0832 2.598 5th lens (L5) S51 -24.496 1.001 1.76 -11.02 26.61 S52 12.79 0 4th lens (L4) S41 12.79 4.451 1.80 10.67 46.59 S42 -21.63 0.300 4th group (G4) 7th lens (L7) S71 16.23 4.301 1.80 42.02 46.59 S72 27.695 2.600 5th group (G5) 8th lens (L8) S81* 15.63 1.501 1.53 -46.46 55.75 S82* 9.23 2.000 cover glass ∞ 2.000 1.49 ∞ 70.44 ∞ 0 Focal length(F) 17.05 Total Track Length (TTL) 42.00 Image height 16.00 Chief Ray Angle (CRA) 11.84 F No. 1.20 DFOV 51.55

Among the lens surfaces of the lens optical system according to the second embodiment of the present invention shown in FIG. 2, an aspherical surface satisfies the aspherical surface equation of the following equation.

<Equation>

Here, z denotes a distance from the vertex of the lens in the direction of the optical axis, and y denotes a distance in a direction perpendicular to the optical axis. And R represents the radius of curvature at the vertex of the lens, and K represents a conic constant. In addition, A 2 to A 12 each represent an aspherical coefficient.

The table below is a table related to the aspheric coefficient of the aspherical surface of the lens optical system according to the third embodiment of the present invention shown in FIG. 3 .

K A2 A4 A6 A8 A10 A12 S11 10 -2.27 x 10 ^-5 5.36 x 10 ^-7 -2.66 x 10 ^-9 -2.83 x 10 ^-11 5.11 x 10 ^-13 -2.10 x 10 ^-15 S12 2.37 -1.48 x 10 ^-5 7.55 x 10 ^-7 -6.38 x 10 ^-9 9.88 x 10 ^-12 4.58 x 10 ^-13 -2.60 x 10 ^-15 S61 -0.67 -6.74 x 10 ^-5 4.27 x 10 ^-7 -1.31 x 10 ^-8 2.96 x 10 ^-10 -5.15 x 10 ^-12 3.32 x 10 ^-14 S62 -0.48 -1.47 x 10 ^-4 6.14 x 10 ^-7 -1.62 x 10 ^-8 -1.11 x 10 ^-10 6.91 x 10 ^-12 -9.86 x 10 ^-14 S81 -0.03 -1.36 x 10 ^-3 -4.82 x 10 ^-6 4.58 x 10 ^-7 -1.23 x 10 ^-8 1.83 x 10 ^-10 -1.13 x 10 ^-12 S82 0.00 -1.32 x 10 ^-3 -3.59 x 10 ^-6 3.26 x 10 ^-7 -9.58 x 10 ^-9 1.41 x 10 ^-10 -8.11 x 10 ^-13

2 and the two tables above, each lens of the lens optical system according to the second embodiment of the present invention satisfies the above-described characteristics. is calculated as the value of

conditional expression target value Target value of the second embodiment conditional expression 1 |f1|/f > 2 |f1|/f 2.57 condition 2 45 < (V2+V3+V7)/3 < 55 (V2+V3+V7)/3 52.19 conditional expression 3 0.1 < FSL/TTL < 0.2 FSL/TTL 0.16 condition 4 1.1 < L1R/ImageR < 1.4 L1R/ImageR 1.18

As shown in the table above, it can be seen that the lens optical system of the second embodiment of the present invention satisfies all of Conditions 1 to 4.

Hereinafter, a lens optical system according to a third embodiment of the present invention will be described with reference to FIG. 3 .

3 is a lens configuration diagram of a lens optical system according to an embodiment of the present invention. While the third embodiment will be described with reference to FIG. 3 , different points from the first embodiment will be mainly described.

The third group G3 includes a fourth lens L4 , a fifth lens L5 , and a sixth lens L6 . In the third group G3 , the arrangement order of the fourth lens L4 , the fifth lens L5 , and the sixth lens L6 may be changed. In this embodiment described with reference to FIG. 2 , the sixth lens L6 , the fourth lens L4 , and the fifth lens L5 are sequentially arranged from the object side to the sensor side direction.

Among the lenses of the third group G3, the sixth lens L6 located closest to the object has negative (-, negative) refractive power. The sixth lens L6 is formed of a plastic material, and the plastic forming the sixth lens L6 preferably has a refractive index greater than 1.50 and less than 1.55. And it is preferable that the Abbe number (V6) of the sixth lens (L6) is greater than 50 and less than 58.

The object-side surface S61 of the sixth lens L6 is paraxially convex. The object-side surface S61 of the sixth lens L6 has a positive radius of curvature with respect to the paraxial axis. The object side surface S61 of the sixth lens L6 is convex even within the effective diameter. The object side surface S61 of the sixth lens L6 may be formed without an inflection point within the effective diameter. The object-side surface S61 of the sixth lens L6 may be formed as an aspherical surface.

The sensor side surface S62 of the sixth lens L6 is paraxially concave. Accordingly, the sixth lens L6 may be formed in a meniscus shape. The radius of curvature with respect to the paraxial axis of the sensor side surface S62 of the sixth lens L6 has a negative value. The sensor side surface S62 of the sixth lens L6 is concave even within the effective diameter. The sensor side surface S62 of the sixth lens L6 may be formed without an inflection point within the effective diameter. The sensor side surface S62 of the sixth lens L6 may be formed as an aspherical surface.

Diffractive optical elements (DOE) may be formed on any one of the object-side surface S61 and the sensor-side surface S62 of the sixth lens L6. The diffractive optical element refers to an element using diffraction by periodic structures rather than refraction or reflection to control light in an optical system.

In the second embodiment, a diffractive optical element is formed on the sensor side surface S62 of the sixth lens L6.

The fringe at the auxiliary wavelength of 1100 nm of the diffractive optical element is determined by the following conditional expression.

fringe = (1/1100) X (R2 R ² + R4 R ⁴ + R6 R ⁶ + R8 R ⁸ )

Here, R is the maximum outer diameter in the effective diameter of the diffractive optical element, R2 is the radius of curvature of the secondary pattern of the diffractive optical element, R4 is the radius of curvature of the fourth pattern of the diffractive optical element, R6 is the radius of curvature of the diffractive optical element It is the radius of curvature of the 6th-order pattern, and R8 is the radius of curvature of the 8th-order pattern of the diffractive optical element.

In this case, the diffractive optical element may satisfy the following conditional expressions for the fringe and R.

<conditional expression>

|fringe|/R < 8

Here, |fringe|/R means the number of fringes per unit length. If the number of fringes per unit length in the diffractive optical element is 8 or more, there is a problem that processing of the diffractive optical element is difficult and a large loss occurs. Therefore, it is preferable that the number of fringes per unit length is less than 8 in order to ensure ease of processing and reduction of loss while achieving appropriate diffraction.

In the second embodiment, the fourth lens L4 is positioned on the sensor side of the sixth lens L6. The fourth lens L4 has positive (+, positive) refractive power. The fourth lens L4 is formed of a glass material, and the refractive index of the glass forming the fourth lens L4 is preferably greater than 1.75 and less than 1.85. And it is preferable that the Abbe number (V4) of the fourth lens (L4) is greater than 25 and less than 58.

The object-side surface S41 of the fourth lens L4 is paraxially convex. The object-side surface S41 of the fourth lens L4 has a positive radius of curvature with respect to the paraxial axis. The object side surface S41 of the fourth lens L4 is convex even within the effective diameter. The object side surface S41 of the fourth lens L4 may be formed without an inflection point within the effective diameter. The object-side surface S41 of the fourth lens L4 may be formed as a spherical surface.

The sensor side surface S42 of the fourth lens L4 is paraxially convex. A radius of curvature based on the paraxial axis of the sensor side surface S42 of the fourth lens L4 has a negative value. The sensor side surface S42 of the fourth lens L4 is convex even within the effective diameter. The sensor side surface S42 of the fourth lens L4 may be formed without an inflection point within the effective diameter. The sensor side surface S42 of the fourth lens L4 may be formed in a spherical shape.

In the second embodiment, the fifth lens L5 is positioned on the sensor side of the fourth lens L4. The fifth lens L5 has negative (-, negative) refractive power. The fifth lens L5 is formed of a glass material, and the refractive index of the glass forming the fifth lens L5 is preferably greater than 1.75 and less than 1.85. And it is preferable that the Abbe number (V5) of the fifth lens (L5) is greater than 25 and less than 58.

The object-side surface S51 of the fifth lens L5 is paraxially concave. The object-side surface S51 of the fifth lens L5 has a negative radius of curvature with respect to the paraxial axis. The object side surface S51 of the fifth lens L5 is concave even within the effective diameter. The object side surface S51 of the fifth lens L5 may be formed without an inflection point within the effective diameter. The object-side surface S51 of the fifth lens L5 may be formed as a spherical surface.

The sensor side surface S52 of the fifth lens L5 is paraxially concave. A radius of curvature based on the paraxial axis of the sensor side surface S52 of the fifth lens L5 has a positive value. The sensor side surface S52 of the fifth lens L5 is concave even within the effective diameter. The sensor side surface S52 of the fifth lens L5 may be formed without an inflection point within the effective diameter. The sensor side surface S52 of the fifth lens L5 may be formed in a spherical shape.

The fourth lens L4 and the fifth lens L5 may be doublet lenses bonded to each other. That is, the sensor-side surface S42 of the fourth lens L4 and the object-side surface S51 of the fifth lens L5 are bonded to each other. Therefore, the separation distance between the fourth lens L4 and the fifth lens L5 may be expressed as 0. In addition, the sensor-side surface S42 of the fourth lens L4 and the object-side surface S51 of the fifth lens L5 may have surface shapes corresponding to each other.

In the lens optical system of the present invention, it is preferable that the amount of change of the focal length in the wavelength band of 400 nm to 1000 nm is less than 5%. Specifically, the lens optical system shown in FIG. 1 has a focal length of 17.049 mm in the reference wavelength band of 656 nm. However, the focal length may be 17.029 mm in the 1000 m band, while the focal length may be 17.065 mm in the 400 nm band. In the lens optical system shown in FIG. 1 , the case with the longest focal length is 0.21% greater than the case with the shortest focal length.

As described above, the lens optical system of the present invention has an advantage that it can be commonly used not only in the visible light band but also in the near-infrared band because the change in focal length is adjusted to 5% or less in the near-infrared band as well as in the visible light band.

The table below describes the optical characteristics of the lens optical system according to the third embodiment of the present invention shown in FIG. 3 .

Component r d N f V first group (G1) first lens (L1) S11* 303.18 1.800 1.81 -37.60 40.40 S12* 27.30 5.427 Aperture (S) ∞ 1.901 2nd group (G2) second lens (L2) S21 54.50 3.509 1.77 27.46 49.62 S22 -33.43 0.300 third lens (L3) S31 20.91 3.646 1.67 28.23 52.46 S32 -170.91 1.659 3rd group (G3) 6th lens (L6) S61* 26.40 2.873 1.53 -26.28 55.75 S62* 8.54 1.193 4th lens (L4) S41 16.49 3.831 1.76 9.97 46.50 S42 -13.81 0.000 5th lens (L5) S51 -13.81 1.200 1.80 -8.23 25.44 S52 12.74 2.095 4th group (G4) 7th lens (L7) S71 21.76 5.000 1.80 15.58 40.58 S72 -27.41 1.847 5th group (G5) 8th lens (L8) S81* 27.19 1.800 1.53 -32.07 55.75 S82* 10.20 2.000 cover glass ∞ 2.000 1.49 ∞ 70.44 ∞ 0 Focal length(F) 17.05 Total Track Length (TTL) 42.00 Image height 16.00 Chief Ray Angle (CRA) 7.84 F No. 1.20 DFOV 52.59

The aspherical surface of the lens surface of the lens optical system according to the third embodiment of the present invention shown in FIG. 3 satisfies the aspherical surface equation of the following equation.

<Equation>

Here, z denotes a distance from the vertex of the lens in the direction of the optical axis, and y denotes a distance in a direction perpendicular to the optical axis. And R represents the radius of curvature at the vertex of the lens, and K represents a conic constant. In addition, A 2 to A 12 each represent an aspheric coefficient.

The table below is a table related to the aspheric coefficient of the aspherical surface of the lens optical system according to the third embodiment of the present invention shown in FIG. 3 .

K A2 A4 A6 A8 A10 A12 S11 -10 -6.69 x 10 ^-6 4.64 x 10 ^-8 -9.70 x 10 ^-10 5.86 x 10 ^-12 0 0 S12 5.19 x 10 ^-2 3.55 x 10 ^-5 1.55 x 10 ^-7 -2.25 x 10 ^-9 1.45 x 10 ^-11 0 0 S61 2.91 x 10 ^-19 -1.80 x 10 ^-4 2.39 x 10 ^-6 -2.22 x 10 ^-8 9.66 x 10 ^-11 0 0 S62 -5.54 x 10 ^-21 -3.62 x 10 ^-4 2.43 x 10 ^-6 -3.66 x 10 ^-8 -1.42 x 10 ^-10 0 0 S81 10 -1.24 x 10 ^-3 6.67 x 10 ^-6 2.48 x 10 ^-7 -1.05 x 10 ^-8 1.58 x 10 ^-10 -9.01x 10 ^-13 S82 3.33 x 10 ^-1 -1.31 x 10 ^-3 5.69 x 10 ^-6 1.51 x 10 ^-7 -8.74 x 10 ^-9 1.41 x 10 ^-10 -8.10 x 10 ^-13

3 and the above two tables, each lens of the lens optical system according to the third embodiment of the present invention satisfies the above-described characteristics. is calculated as the value of

conditional expression target value Target value of the third embodiment conditional expression 1 |f1|/f > 2 |f1|/f 2.21 condition 2 45 < (V2+V3+V7)/3 < 55 (V2+V3+V7)/3 47.56 conditional expression 3 0.1 < FSL/TTL < 0.2 FSL/TTL 0.17 condition 4 1.1 < L1R/ImageR < 1.4 L1R/ImageR 1.20

As shown in the above table, it can be seen that the lens optical system of the third embodiment of the present invention satisfies all of Conditions 1 to 4.

The technical features disclosed in each embodiment of the present invention are not limited only to the embodiment, and unless they are incompatible with each other, the technical features disclosed in each embodiment may be combined and applied to different embodiments.

Accordingly, in each embodiment, each technical feature will be mainly described, but unless the technical features are incompatible with each other, they may be merged and applied.

The present invention is not limited to the above-described embodiments and the accompanying drawings, and various modifications and variations will be possible from the point of view of those of ordinary skill in the art to which the present invention pertains. Accordingly, the scope of the present invention should be defined not only by the claims of the present specification, but also by those claims and their equivalents.

G1: first group
G2: 2nd group
G3: 3rd group
L1: first lens
L2: second lens
L3: third lens
L4: fourth lens
L5: 5th lens
L6: sixth lens
L7: 7th lens
L8: 8th lens
S: aperture
S11: the object side of the first lens
S12: sensor side of the first lens
S21: object side of the second lens
S22: sensor side of the second lens
S31: object side of the third lens
S32: sensor side of the third lens
S41: Object side of the fourth lens
S42: sensor side of the fourth lens
S51: the object side of the fifth lens
S52: sensor side of the fifth lens
S61: Object side of the sixth lens
S62: sensor side of the sixth lens
S71: object side of the 7th lens
S72: Sensor side of the 7th lens
S81: Object side of the 8th lens
S82: Sensor side of the 8th lens

Claims (18)

A first group, a second group, a third group, a fourth group, and a fifth group are sequentially arranged from the object side to the sensor side between the object and the sensor on which the image of the object is formed, and include at least one lens. As a lens optical system to
The first group has a negative refractive power, and the sensor side includes a first lens concave in paraxial,
the second group has a positive refractive power, at least one of the object-side and sensor-side surfaces has a paraxially convex second lens and a positive refractive power, and at least one of the object-side and sensor-side surface has a paraxially convex third lens including,
The third group includes a fourth lens having a positive refractive power, a fifth lens having a negative refractive power, and a sixth lens having a negative refractive power and a diffractive optical element formed on at least one of an object side surface and a sensor side surface - the the fourth lens and the fifth lens are bonded to each other;
the fourth group has a positive refractive power, and at least one of the object-side surface and the sensor-side surface includes a paraxially convex seventh lens,
The fifth group includes an eighth lens having a negative refractive power and formed in a meniscus shape at paraxial,
An iris is located between the first group and the second group,
When f1 is the focal length of the first lens and f is the focal length of the lens optical system, the following conditional expressions for f1 and f are satisfied.
<conditional expression>
|f1|/f > 2 The method of claim 1,
An object-side surface of the first lens is paraxially convex lens optical system. The method of claim 1,
At least one of the second lens and the third lens is a lens optical system in which both an object-side surface and a sensor-side surface are convex. The method of claim 1,
A lens optical system sequentially arranged in the order of the fourth lens, the fifth lens, and the sixth lens from the object side to the sensor side. 5. The method of claim 4,
The diffractive optical element is a lens optical system formed on the object side surface of the sixth lens. 6. The method of claim 5,
The seventh lens is a lens optical system in which both the object side surface and the sensor side surface are convex. The method of claim 1,
A lens optical system sequentially arranged in the order of the sixth lens, the fifth lens, and the fourth lens from the object side to the sensor side. 5. The method of claim 4,
The diffractive optical element is a lens optical system formed on the sensor side surface of the sixth lens. 9. The method of claim 8,
The seventh lens is a lens optical system formed in a meniscus shape in paraxial. The method of claim 1,
The sixth lens is a lens optical system formed in a meniscus shape in the paraxial axis. The method of claim 1,
At least one of the object-side surface and the sensor-side surface of the eighth lens has at least one inflection point within the effective lens optical system. The method of claim 1,
The first lens is a plastic lens,
wherein the second group includes at least one glass lens. The method of claim 1,
The fourth lens and the fifth lens are glass lenses,
The sixth lens is a plastic lens lens optical system. The method of claim 1,
When V2 is the Abbe number of the second lens, V3 is the Abbe number of the third lens, and V7 is the Abbe number of the seventh lens, the following conditional expressions for V2, V3 and V7 are satisfied. lens optics.
<conditional expression>
45 < (V2+V3+V7)/3 < 55 The method of claim 1,
When FSL is the distance on the optical axis between the object-side surface of the first lens and the diaphragm, and TTL is the distance on the optical axis from the object-side surface of the first lens to the sensor, the following conditional expressions for FSL and TTL are Satisfying lens optics.
<conditional expression>
0.1 < FSL/TTL < 0.2 The method of claim 1,
When L1R is the maximum outer diameter at the effective diameter on the object side surface of the first lens and ImageR is the maximum outer diameter in the effective area of the sensor, the following conditional expressions for L1R and ImageR are satisfied.
<conditional expression>
1.1 < L1R/ImageR < 1.4 The method of claim 1,
A fringe at an auxiliary wavelength of 1100 nm of the diffractive optical element is determined by the following conditional expression, and when R is the maximum outer diameter in the effective diameter of the diffractive optical element, a lens satisfying the following conditional expression for the fringe and R optics.
fringe = (1/1100) X (R2 R ² + R4 R ⁴ + R6 R ⁶ + R8 R ⁸ )
(The R2 is the radius of curvature of the second pattern of the diffractive optical element, R4 is the radius of curvature of the fourth pattern of the diffractive optical element, and R6 is the radius of curvature of the sixth pattern of the diffractive optical element, the R8 is the radius of curvature of the 8th-order pattern of the diffractive optical element)
<conditional expression>
|fringe|/R < 8 The method of claim 1,
In the lens optical system, the change amount of the focal length in a wavelength band of 400 nm to 1000 nm is less than 1.0%.

Images