KR101171517B1 - Subminiature Optical System - Google Patents

Abstract

An ultra-compact optical system according to an embodiment of the present invention comprises a first lens having a positive refractive power, in order from the object side, the object side surface and the image side surface is convex and aspherical; A second lens having negative refractive power and having a meniscus shape in which an image side surface is concave; A third lens having positive refractive power and having an image-side surface convex; A fourth lens having a positive refractive power and having a meniscus shape in which an image side surface is convex, wherein at least one of the object side surface and the image side surface is an aspherical surface; And a fifth lens having negative refractive power and formed of an aspherical surface having a concave side and an inflection point on the image side.

Description

Subminiature Optical System

The present invention relates to an ultra-compact optical system, and more particularly, to a five-lens lens mounted on a mobile communication terminal, a PDA, or the like, applied to a surveillance camera and a digital camera, and achieving high resolution lens performance that minimizes chromatic aberration.

In general, cameras are installed in mobile communication terminals, computers, laptops, and vehicles to display or record video information of surroundings. It is required to have high image quality while being lightweight.

Therefore, since the optical system also requires high performance in terms of resolution, image quality, and the like, the configuration of the lens constituting the optical system is complicated. In the case of such a configuration or optical complexity, the size of the optical system itself is increased to reduce the size and thickness There is a problem.

In addition, as the demand for high resolution increases, the pixel size of the image sensor becomes smaller and smaller, and a high resolution lens needs to be developed to cope with such a small pixel size.

Along with the demand for high resolution lenses, the economic aspects of mass production have to be satisfied. Therefore, development of high resolution lenses using plastic lenses is required.

However, in the case of plastic lenses, it is difficult to secure reliability, and the type is limited compared to glass materials, and thus, it is true that the selection of materials is difficult.

Therefore, while achieving high resolution by removing chromatic aberration, it is possible to pursue miniaturization and thinning, and it is urgent to study an optical system that prevents a decrease in yield by reducing sensitivity according to the environment.

An object of the present invention is to provide an ultra-compact optical system having a five-lens configuration that can be miniaturized and thinned, and maintains good optical performance such as aberration and MTF characteristics.

An ultra-compact optical system according to an embodiment of the present invention comprises a first lens having a positive refractive power, in order from the object side, the object side surface and the image side surface is convex and aspherical; A second lens having negative refractive power and having a meniscus shape in which an image side surface is concave; A third lens having positive refractive power and having an image-side surface convex; A fourth lens having a positive refractive power and having a meniscus shape in which an image side surface is convex, wherein at least one of the object side surface and the image side surface is an aspherical surface; And a fifth lens having negative refractive power, the image-side surface being concave and having an inflection point with an inflection point, and satisfying the following Conditional Expressions 1 to 8.

[Condition 1] 1.1 <tt / f <1.5

[Condition 2] 0.5 <f1 / f <1.2

[Condition 3] 25 <Vg1-Vg2 <50

[Condition 4] | Vg3-Vg4 | <15

[Condition 5] | Vg1-Vg3 | <15
[Condition 6] | A3 | > 1.5 * 10 ^-5
[Condition 7] | A4 | > 1.5 * 10 ^-5
[Condition 8] | A5 | > 1.5 * 10 ^-5

Where tt is the distance from the object-side surface of the first lens to the imaging surface

f: focal length of optical system

f1: focal length of the first lens

Vg1: Abbe number of the first lens

Vg2: Abbe number of the second lens

Vg3: Abbe number of the third lens

Vg4: Abbe number of the fourth lens
A3: coefficient of thermal expansion of the third lens
A4: coefficient of linear thermal expansion of the fourth lens
A5: coefficient of thermal expansion of the fifth lens

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The ultra-compact optical system according to an embodiment of the present invention may be characterized by satisfying the following Conditional Expressions 9 and 10.

[Condition 9] | A1 | > 1.5 * 10 ^-5

[Condition 10] | A2 | > 1.5 * 10 ^-5

Here, A1: coefficient of linear thermal expansion of the first lens

        A2: coefficient of thermal expansion of the second lens

The micro-optical system according to an embodiment of the present invention may further include an aperture provided between the first lens and the second lens to adjust the amount of light.

The object-side surface of the fifth lens of the micro-optical system according to an embodiment of the present invention may be formed of an aspherical surface having no inflection point.

The second lens of the micro-optical system according to an embodiment of the present invention may be characterized in that at least one of the object-side surface and the image-side surface is aspheric.

The object-side surface of the fifth lens of the ultra-compact optical system according to an embodiment of the present invention may be characterized in that the concave shape.

According to the microscopic optical system according to the present invention, by maintaining the spherical aberration, astigmatism, and distortion aberrations well, an image having excellent quality of high resolution and high definition can be obtained.

In addition, the sensitivity of the lens can be reduced to prevent a decrease in yield, and the incident angle of light incident on the image sensor can be reduced, thereby providing an optical system corresponding to a small pixel size.

1 is a lens configuration diagram showing a lens arrangement of an ultra-compact optical system according to a first embodiment of the present invention.
FIG. 2 is a graph illustrating aberration diagrams of the microscopic optical systems shown in FIGS. 1 and 1, showing longitudinal spherical aberration, astigmatism, and distortion.
3 and 4 are graphs showing the MTF characteristics of the microscopic optical systems shown in FIGS. 1 and 1 and analysis graphs showing the distribution of lateral colors.
5 is a lens configuration diagram showing the lens arrangement of the ultra-compact optical system according to the second embodiment of the present invention.
FIG. 6 is a graph illustrating aberration diagrams of the ultra-compact optical system shown in FIGS. 5 and 3, illustrating longitudinal spherical aberration, astigmatism, and distortion.
7 and 8 are graphs showing the MTF characteristics of the microscopic optical systems shown in FIGS. 5 and 3 and an analysis graph showing the distribution of lateral colors.
9 is a lens configuration diagram showing the lens arrangement of the ultra-compact optical system according to the third embodiment of the present invention.
FIG. 10 is a graph illustrating aberration diagrams of the microscopic optical systems illustrated in FIGS. 9 and 5, illustrating longitudinal spherical aberration, astigmatism, and distortion.
11 and 12 are graphs showing the MTF characteristics of the microscopic optical systems shown in FIGS. 9 and 5 and an analysis graph showing the distribution of lateral colors.
FIG. 13 is a lens configuration diagram showing a lens arrangement of an ultra-compact optical system according to a fourth embodiment of the present invention. FIG.
FIG. 14 is a graph illustrating the aberration diagram of the ultra-compact optical system shown in FIGS. 13 and 7, showing longitudinal spherical aberration, astigmatism, and distortion.
15 and 16 are graphs showing the MTF characteristics of the microscopic optical systems shown in FIGS. 13 and 7 and analysis graphs showing the distribution of lateral colors.
FIG. 17 is a lens configuration diagram showing a lens arrangement of the ultra-compact optical system according to the fifth embodiment of the present invention. FIG.
FIG. 18 is a graph illustrating aberrations of the ultra-compact optical system shown in FIGS. 17 and 9, showing longitudinal spherical aberration, astigmatism, and distortion.
19 and 20 are graphs showing the MTF characteristics of the microscopic optical systems shown in FIGS. 17 and 9 and analysis graphs showing the distribution of lateral colors.

Hereinafter, with reference to the drawings will be described in detail a specific embodiment of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventive concept. Other embodiments falling within the scope of the inventive concept may readily be suggested, but are also considered to be within the scope of the present invention.

The same reference numerals are used to designate the same components in the same reference numerals in the drawings of the embodiments.

1 is a lens configuration diagram showing a lens arrangement of the microscopic optical system 100 according to the first embodiment of the present invention.

In the following lens configuration, the thickness, size, and shape of the lens have been somewhat exaggerated for explanation, and in particular, the shape of the spherical or aspherical surface shown in the lens configuration is merely an example and is not limited thereto.

In general, the camera module has at least one lens, a predetermined space formed therein, a housing accommodating the lens, an image sensor corresponding to an imaging surface by the lens, and a fixed installation at the other end of the housing, wherein the image is fixed on one surface of the camera module. The sensor may be mounted to a circuit board for processing an image sensed by the image sensor.

The present invention relates to a micro-optical system 100 used in the miniature camera module of the camera module.

As shown in FIG. 1, the microscopic optical system 100 according to the first exemplary embodiment of the present invention includes the first lens L1, the second lens L2, the third lens L3, and the first lens in order from the object side. Four lenses L4 and fifth lens L5 may be included. Here, IP illustrated in FIG. 1 represents an image plane.

The first lens L1 has a positive refractive power, the object-side surface 1 and the image side 2 may be convex and aspherical, and the second lens L2 has a negative refractive power, and the image side surface ( 5) may be concave meniscus shape.

In addition, the third lens L3 has a positive refractive power, and the image side surface 7 is convex.

In addition, the fourth lens L4 may have positive refractive power, have a meniscus shape in which the image side surface 9 is convex, and at least one of the object side surface 8 and the image side surface 9 may be aspheric. .

Here, the fifth lens L5 may be formed of an aspherical surface having an image side surface 11 concave and having an inflection point.

This lens configuration can be advantageous for miniaturization and thinning by appropriately distributing five lenses L1, L2, L3, L4 and L5 having positive, negative, positive, positive and negative refractive powers from the object side in turn.

The first lens L1 most disposed on the object side can convex both surfaces 1 and 2 to have positive refractive power, thereby adjusting the refractive power of the entire optical system on the object side of the optical system.

The second lens L2 is formed of a material having a relatively large dispersion value (that is, having a small Abbe number), and concave to form the image side surface 5 to have a negative refractive power, and to be disposed behind the third lens L2. The fifth to fifth lenses L3 to L5 are configured to compensate for color dispersion.

In addition, at least one of the object-side surface 4 and the image-side surface 5 of the second lens L2 may be aspherical.

In addition, since the second lens L2 is a lens having a large dispersion value, chromatic aberration may be improved and high resolution may be pursued, as can be seen in the analysis graph of the embodiment to be described later.

Here, an aperture AS is provided between the first lens L1 and the second lens L2, and the aperture AS is disposed between the first lens L1 and the second lens L2. The arrangement may be advantageous in making the optical system slimmer and thinner than the arrangement in the object-side surface 1 side of the first lens L1.

The third lens L3 may have the positive refractive power having the convex shape of the image surface 7 to allow light passing through the second lens L2 disposed in front thereof to be incident at a small incident angle.

The fourth lens L4 may have a meniscus shape in which the image side surface 9 is convex, and at least one of the object side surface 8 and the image side surface 9 may be aspheric.

The fifth lens L5 is a lens disposed at the uppermost side, and the image side 11 is formed as an aspherical surface having a concave and inflection point, thereby reducing the incident angle of light incident on the image surface IP, thereby reducing the pixel size of the image sensor. In addition, it is possible to obtain an image of excellent quality with reduced aberration.

Here, the object-side surface 10 of the fifth lens L5 may be formed of an aspherical surface without an inflection point, and may be formed in a concave shape.

In addition, the image-side surface 11 of the fifth lens L5 is concave, so that the back focus can be shortened without protruding largely in the direction of the image surface IP. It can be an advantageous configuration.

In addition, by bringing the focal length of the fifth lens L5 to a shorter length, the telecentric characteristic is secured together with the image surface 9 of the fourth lens L4 having a small curvature radius and sensitivity even at a wide angle of view. Can slow down.

Here, an optical filter (OF) such as an infrared filter or a cover glass may be installed between the fifth lens (L5) and the image surface (IP), the optical filter (OF) in principle does not affect the optical performance Seen to be.

In addition, the upper surface IP corresponds to an imaging surface of an imaging device such as a charge coupled device (CCD) and a complementary metal oxide semicondictor (COMS).

On the other hand, the micro-optical system 100 according to the present invention is preferably implemented in a range that satisfies the following conditional expression with the features as described above.

First, the micro-optical system 100 according to an embodiment of the present invention is preferably implemented within a range satisfying the following Conditional Expressions 1 to 5.

[Condition 1] 1.1 <tt / f <1.5

In the above Conditional Expression 1, tt represents a distance from the object-side surface 1 of the first lens L1 to the image surface IP, and f represents a focal length of the optical system.

Conditional Expression 1 is a conditional expression that satisfies a high resolution and reduces the length of the entire optical system. If the conditional expression 1 is out of the lower limit of Conditional Expression 1, coma and astigmatism are greatly increased, and it is difficult to obtain a clear image. The optimal upper surface position is greatly deviated, making it impossible to realize high resolution in the entire screen.

If the distance from the upper limit of Conditional Expression 1 is exceeded, the distance from the object-side surface 1 of the first lens L1 to the image surface IP becomes long, making it impossible to realize miniaturization, thinning, and a slim optical system.

On the other hand, the micro-optical system 100 according to the present invention is preferably implemented in a range that satisfies the following Conditional Expression 2 together with or independently of the Conditional Expression 1 above.

[Condition 2] 0.5 <f1 / f <1.2

In Conditional Expression 2, f1 represents a focal length of the first lens L1, and f represents a focal length of the optical system.

Conditional Expression 2 defines a condition related to the refractive power of the first lens L1. The conditional expression 2 maintains the size of the entire optical system while suppressing the generation of spherical aberration and coma flare, thereby ensuring excellent image quality and protecting the environment. Conditional expression for preventing the decrease in yield by slowing the sensitivity.

When the deviation from the lower limit of the conditional expression 2 occurs, the spherical aberration and the coma aberration are greatly generated, resulting in deterioration of image quality.

And, if the deviation from the upper limit of the conditional expression 2, the refractive power of the first lens (L1) is weakened so that the position where the light rays starting from the object-side surface 1 of the first lens (L1) meets the optical axis Therefore, it is impossible to implement a slim optical system, the sensitivity of the environment is also increased, and chromatic aberration increases, making it difficult to correct chromatic aberration.

On the other hand, the micro-optical system 100 according to the present invention is preferably implemented in a range that satisfies the following conditional expressions 3 to 5 together with or independently of at least one of the conditional expressions 1 and 2.

[Condition 3] 25 <Vg1-Vg2 <50

[Condition 4] | Vg3-Vg4 | <15

[Condition 5] | Vg1-Vg3 | <15

In the above Conditional Expressions 3 to 5, Vg1 to Vg4 represent Abbe numbers of the first to fourth lenses L1 to L4.

Conditional Expressions 3 to 5 define conditions related to materials of the first lens L1 to the fourth lens L2. When the conditional value is out of the range of the conditional expression 3, the Abbe number of the second lens L2 is relatively high. In a case where a large value (small dispersion value) is formed, color dispersion correction may be difficult.

When the deviation from the upper limit of the conditional expression 3 occurs, the aberration degree, that is, the spherical aberration, the astigmatism, and the distortion, increases, and the MTF characteristic may deteriorate.

In addition, the same problem occurs when the condition is out of the range of the conditional expressions 4 and 5.

On the other hand, the micro-optical system 100 according to the present invention is preferably implemented in a range that satisfies the following conditional expressions 6 to 8 together or independently with at least one of the conditional expressions 1 to 5.

[Condition 6] | A3 | > 1.5 * 10 ^-5

[Condition 7] | A4 | > 1.5 * 10 ^-5

[Condition 8] | A5 | > 1.5 * 10 ^-5

In the above Conditional Expressions 6 to 8, A3 to A5 represent linear thermal expansion coefficients of the third lens L3 to the fifth lens L5.

 Conditional Expressions 6 to 8 define conditions of the degree of expansion according to the temperature of the third lens L3 to the fifth lens L5, and when the condition is out of the conditional expression, the ultra-compact optical system 100 according to the present invention is applied to the environment. Sensitivity is increased, resulting in a decrease in yield.

That is, Conditional Expressions 6 to 8 are the minimum ranges for preventing the degradation of the yield by slowing the sensitivity due to environmental changes.

On the other hand, the micro-optical system 100 according to the present invention is preferably implemented in a range that satisfies the following conditions 9 and 10 together with or independently of at least one of the conditions 1 to 8.

[Condition 9] | A1 | > 1.5 * 10 ^-5

[Condition 10] | A2 | > 1.5 * 10 ^-5

In the above Conditional Expressions 9 and 10, A1 and A2 represent linear thermal expansion coefficients of the first lens L1 and the second lens L2.

The conditional expressions 9 and 10 also define the condition of the degree of expansion according to the temperature of the first lens (L1) and the second lens (L2) similar to the conditional expressions 6 to 8, when the conditional expression is out of the conditional expression according to the present invention The optical system increases the sensitivity according to the environment, resulting in a decrease in yield.

Meanwhile, hereinafter, the first embodiment shown in FIG. 1, the second embodiment shown in FIG. 5, the third embodiment shown in FIG. 9, the fourth embodiment shown in FIG. 13, and the agent shown in FIG. 17 will be described. By applying specific numerical values with respect to the five embodiments will be described in more detail with respect to the micro-optical system according to each embodiment.

First, the following Examples 1 to 5 have a positive refractive power, the first lens L1 having a positive refractive power, an image-side surface 2 and a convex shape and an aspherical surface, and a negative refractive power and an image side surface. The second lens L2 having a concave meniscus shape (5), the third lens L3 having positive refractive power and the convex image surface 7, and the meniscus shape having the positive refractive power and convex image surface 9. And at least one of the object-side surface 8 and the image-side surface 9 is a fourth lens L4 composed of an aspherical surface and a fifth lens composed of an aspherical surface having a negative refractive power and the image-side surface 11 concave. L5), and an aperture AS is provided between the first lens L1 and the second lens L2.

In addition, an optical filter OF corresponding to an infrared filter, a cover glass, or the like is provided between the fifth lens L5 and the image surface IP, and the image surface IP is formed on an imaging surface of an image sensor such as a CCD or a CMOS. Corresponding.

The aspherical surface used in each of the following examples is obtained from well-known Equation 1, and is used in the Conic constant (K) and the aspherical surface coefficients (A, B, C, D, E, F), and The number following is the power of ten. For example, E + 01 represents 101 and E-02 represents 10-2.

Z: Distance from the vertex of the lens to the optical axis direction

Y: Distance in the direction perpendicular to the optical axis

c: inverse of the radius of curvature r at the vertex of the lens

K: Conic constant

A, B, C, D, E, F: Aspheric coefficient

[First Embodiment]

Table 1 below shows a numerical example of the ultra-compact optical system according to the first embodiment of the present invention, Figure 1 is a lens configuration showing the lens arrangement of the ultra-compact optical system according to the first embodiment of the present invention, Figure 2 1 and Table 1 are diagrams showing the aberration diagrams of the optical system shown in FIG. 1, and are analytical graphs showing the spherical aberration, astigmatism, and distortion aberration, and FIGS. It is a graph showing MTF characteristics and an analysis graph showing the distribution of lateral colors.

In the case of the first embodiment, the distance tt from the object-side surface of the first lens L1 to the image surface IP is 5.95 mm, the focal length f of the entire optical system is 4.72 mm, and the first lens L1. The focal length f1 is 3.0 mm, and the Abbe number Vg2 of the second lens L2 is 25.59, and the Abbe number of the first lens L1, the third lens L3, and the fourth lens L4 ( Vg1, Vg3, Vg4) is 56.27.

Cotton number
Bending Radius (mm) Thickness or
Distance (t)
Refractive index (Nd)
Abbe (Vgn)
Remarks One ∞ 0.050000 1.5346 56.27 First lens 2 2.14883 0.802919 3 -5.59961 0.100000 iris 4 4.78007 0.333304 1.6142 25.59 Second lens 5 1.55362 0.666641 6 -80.21577 0.705100 1.5346 56.27 Third lens 7 -4.13869 0.330701 8 -1.80440 0.660624 1.5346 56.27 Fourth lens 9 -0.97424 0.081081 10 -64.81954 0.808286 1.5311 55.87 Fifth lens 11 1.31793 0.261344 12 ∞ 0.300000 BSC7_HOYA Optical filter 13 ∞ 0.898006 14 ∞ 0.002000 Top

The aspherical coefficients of the first embodiment according to Equation 1 are shown in Table 2 below.

if
number
K
A
B
C
D
E 2 -2.544048 0.282637E-01 0.379984E-02 -.159926E-01 0.144370E-01 -.680986E-02 3 -6.242273 0.627687E-01 -.736614E-01 0.611350E-01 -.500827E-01 0.161823E-01 4 15.802308 -.484340E-01 0.206748E-01 -.435237E-01 0.152281E-01 -.546892E-02 5 -5.201058 0.523298E-01 0.108090E-01 -.125565E-01 0.963247E-03 0.262775E-02 6 0.000000 -.362828E-01 -.224459E-01 0.399117E-01 -.166800E-01 0.290067E-02 7 -1.807298 -.250410E-01 -.745210E-01 0.823338E-01 -.343495E-01 0.523488E-02 8 -3.530849 -.227660E-01 -.614062E-01 0.957610E-01 -.469476E-01 0.758467E-02 9 -3.251006 -.657952E-01 0.369796E-01 0.151892E-02 -.587111E-02 0.112461E-02 10 0.000000 -.303366E-01 0.517853E-02 -.213475E-02 0.409276E-03 -.274509E-04 11 -8.626509 -.407000E-01 0.959994E-02 -.207809E-02 0.219020E-03 -.100145E-04

[Second Embodiment]

Table 3 below shows a numerical example of the ultra-compact optical system according to the second embodiment of the present invention, Figure 5 is a lens configuration showing the lens arrangement of the ultra-compact optical system according to the second embodiment of the present invention, Figure 6 5 is a graph illustrating the first aberration diagram of the optical system shown in FIG. 5 and Table 3, which is an analysis graph showing longitudinal spherical aberration, astigmatism, and distortion, and FIGS. It is a graph showing MTF characteristics and an analysis graph showing the distribution of lateral colors.

In the case of the second embodiment, the distance tt from the object-side surface of the first lens L1 to the image surface IP is 5.32 mm, the focal length f of the entire optical system is 4.05 mm, and the first lens L1 Has a focal length f1 of 2.9828 mm, an Abbe number Vg2 of the second lens L2 of 25.59, and an Abbe number of the first lens L1, the third lens L3, and the fourth lens L4 ( Vg1, Vg3, Vg4) is 56.27.

Cotton number
Bending Radius (mm) Thickness or
Distance (t)
Refractive index (Nd)
Abbe (Vgn)
Remarks One ∞  0.050000 1.5346 56.27 First lens 2 2.12462 0.612015 3 -5.84935 0.118054 iris 4  4.66219 0.320000 SP-1516
Second lens 5 1.61852 0.482843 6 -100.00000 0.648314 1.5346 56.27 Third lens 7 -6.63972 0.224977 8 -2.93989 0.758569 1.5346 56.27 Fourth lens 9 -0.87836 0.100000 10 150.00000 0.536952 1.5311 55.87 Fifth lens 11  1.05493 0.271732 12 ∞  0.300000 BSC7_HOYA Optical filter 13 ∞  0.950102 14 ∞ -0.000102 Top

The aspherical coefficients of the second embodiment according to Equation 1 are shown in Table 4 below.

if
number
K
A
B
C
D
E 2 -2.794328 0.244478E-01 -.517991E-02 -.227463E-01 0.118364E-01 -.179869E-01 3 13.100677 0.486429E-01 -.830145E-01 0.514118E-01 -.594536E-01 0.210621E-01 4 14.780412 -.477783E-01 0.422114E-02 -.529322E-01 0.187898E-01 0.402237E-02 5 -5.008763 0.552079E-01 0.107659E-01 -.154335E-01 0.396226E-03 0.565827E-02 6  0.000000 -.469629E-01 -.178547E-01 0.452474E-01 -.148773E-01 0.230356E-02 7  5.289501 -.357861E-01 -.784772E-01 0.821315E-01 -.343372E-01 0.546464E-02 8 -3.873847 -.203837E-01 -.637047E-01 0.945438E-01 -.469152E-01 0.775738E-02 9 -3.597572 -.813446E-01 0.409031E-01 0.268742E-02 -.570961E-02 0.111487E-02 10  0.000000 -.371323E-01 0.121846E-02 -.215088E-02 0.490625E-03 0.351645E-05 11 -7.481393 -.462052E-01 0.813597E-02 -.212780E-02 0.237834E-03 -.123884E-04

Third Embodiment

Table 5 below shows a numerical example of the ultra-compact optical system according to the third embodiment of the present invention, Figure 9 is a lens configuration showing the lens arrangement of the ultra-compact optical system according to the third embodiment of the present invention, Figure 10 9 is a graph illustrating an aberration diagram of the optical system illustrated in FIGS. 9 and 5, and is an analysis graph illustrating longitudinal spherical aberration, astigmatism, and distortion, and FIGS. 11 and 12 are diagrams illustrating the optical systems illustrated in FIGS. It is a graph showing MTF characteristics and an analysis graph showing the distribution of lateral colors.

In the third embodiment, the distance tt from the object-side surface of the first lens L1 to the image surface IP is 7.07 mm, the focal length f of the entire optical system is 5.78 mm, and the first lens L1 The focal length f1 is 3.52 mm, the Abbe number Vg2 of the second lens L2 is 25.59, and the Abbe number of the first lens L1, the third lens L3, and the fourth lens L4 ( Vg1, Vg3, Vg4) is 56.27.

Cotton number
Bending Radius (mm) Thickness or
Distance (t)
Refractive index (Nd)
Abbe (Vgn)
Remarks One ∞  0.050000 1.5346 56.27 First lens 2  2.37044 0.866465 3  -8.05780 0.100000 iris 4 5.59632  0.400000 1.6142 25.59 Second lens 5  1.79761  0.846992 6 56.27569 0.962362 1.5346 56.27 Third lens 7 -7.08355 0.344008 8 -2.64077 0.833246 1.5346 56.27 Fourth lens 9 -1.23871 0.100000 10 -184.13931 0.923000 1.5346 56.27 Fifth lens 11   1.59138 0.400000 12 ∞  0.300000 BSC7_HOYA Optical filter 13 ∞  1.069170 14 ∞ 0.000754 Top

The aspherical coefficients of the third embodiment according to Equation 1 are shown in Table 6 below.

Face number
K
A
B
C
D
E 2 -1.864155 0.183356E-01 0.163794E-02 -.275178E-02 0.244502E-02 -.968426E-03 3 -28.263606 0.347091E-01 -.266778E-01 0.164285E-01 -.921245E-02 0.181526E-02 4 14.639252 -.309134E-01 0.101933E-01 -.116674E-01 0.221741E-02 -.695570E-03 5 -4.944833 0.343567E-01 0.488233E-02 -.374608E-02 0.134377E-02 -.577625E-04 6 0.000000 -.193177E-01 -.669626E-02 0.783901E-02 -.282449E-02 0.407995E-03 7 -7.654944 -.142719E-01 -.282541E-01 0.191868E-01 -.531207E-02 0.492656E-03 8 -5.846012 -.914486E-02 -.223004E-01 0.221858E-01 -.708789E-02 0.744131E-03 9 -3.617903 -.314381E-01 0.143139E-01 0.153413E-03 -.905702E-03 0.114600E-03 10  0.000000 -.215028E-01 0.286183E-02 -.638488E-03 0.214244E-04 0.420439E-05 11 -8.523607 -.231145E-01 0.367534E-02 -.562573E-03 0.400526E-04 -.114855E-05

[Fourth Embodiment]

Table 7 below shows a numerical example of the ultra-compact optical system according to the fourth embodiment of the present invention, Figure 13 is a lens configuration showing the lens arrangement of the ultra-compact optical system according to the fourth embodiment of the present invention, Figure 14 FIG. 13 is a graph illustrating the aberration diagrams of the optical systems shown in FIGS. 13 and 7, illustrating analysis of spherical aberration, astigmatism, and distortion, and FIGS. 15 and 16 illustrate an optical system shown in FIGS. It is a graph showing MTF characteristics and an analysis graph showing the distribution of lateral colors.

In the case of the fourth embodiment, the distance tt from the object-side surface of the first lens L1 to the image surface IP is 5.91 mm, the focal length f of the entire optical system is 4.81 mm, and the first lens L1. Has a focal length f1 of 3.3578 mm, an Abbe number Vg1 of the first lens L1 is 62.76, an Abbe number Vg2 of the second lens L2 is 27.57, and a third lens L3 and a third lens. The Abbe's numbers Vg3 and Vg4 of the four lenses L4 are 56.27.

Cotton number
Bending Radius (mm) Thickness or
Distance (t)
Refractive index (Nd)
Abbe (Vgn)
Remarks One ∞ 0.050000 1.577692 62.7610 First lens 2  2.06471 0.850376 3 -27.22956   0.178803 iris 4 14.44646 0.453600 1.755201 27.5795 Second lens 5  3.07512 0.527372 6 -15.28726 0.520731 1.5346 56.27 Third lens 7 -4.73902 0.172421 8  -1.74473  0.633516 1.5346 56.27 Fourth lens 9 -1.03667 0.081081 10 -150.00000  0.817866 1.5311 55.87 Fifth lens 11 1.70568 0.179957 12 ∞ 0.300000 BSC7_HOYA Optical filter 13 ∞ 1.198762 14 ∞  0.002000 Top

The aspherical coefficients of the fourth embodiment according to Equation 1 are shown in Table 8 below.

Face number
K
A
B
C
D
E 2 -2.141521 0.308997E-01 0.400028E-02 -.136621E-01 0.157808E-01 -.556268E-02 3 389.518486 0.321983E-01 -.629017E-01 0.853962E-01 -.346162E-01 -.547512E-02 6  0.000000 -.369572E-01 -.295225E-01 0.371262E-01 -.173881E-01 -.712044E-03 7 -2.579403 -.205492E-01 -.751897E-01 0.830285E-01 -.337708E-01 0.543811E-02 8 -2.701442 -.138787E-01 -.587531E-01 0.949170E-01 -.469866E-01 0.775848E-02 9 -3.029522 -.578712E-01 0.377262E-01 0.225320E-02 -.571775E-02 0.116901E-02 10 0.000000 -.256045E-01 0.522594E-02 -.188905E-02 0.445608E-03 -.314017E-04 11 -12.238157 -.407028E-01 0.861606E-02 -.195271E-02 0.212113E-03 -.108034E-04

[Fifth Embodiment]

Table 9 below shows a numerical example of the ultra-compact optical system according to the fifth embodiment of the present invention, Figure 17 is a lens configuration showing the lens arrangement of the ultra-compact optical system according to the fifth embodiment of the present invention, Figure 18 FIG. 17 is a graph illustrating the aberration diagrams of the optical systems shown in FIGS. 17 and 9, illustrating analysis of spherical aberration, astigmatism, and distortion, and FIGS. 19 and 20 illustrate the optical systems shown in FIGS. It is a graph showing MTF characteristics and an analysis graph showing the distribution of lateral colors.

In the case of the fifth embodiment, the distance tt from the object-side surface of the first lens L1 to the image surface IP is 5.92 mm, the focal length f of the entire optical system is 4.80 mm, and the first lens L1 Has a focal length f1 of 2.85 mm, an Abbe number Vg1 of the first lens L1 is 59.66, an Abbe number Vg2 of the second lens L2 is 27.57, and a third lens L3 and a third lens. The Abbe's numbers Vg3 and Vg4 of the four lenses L4 are 56.27.

Cotton number
Bending Radius (mm) Thickness or
Distance (t)
Refractive index (Nd)
Abbe (Vgn)
Remarks One ∞  0.050000 1.546734 59.6642 First lens 2  2.07875 0.721481 3 -5.62421 0.101375 iris 4  5.63219 0.320000 1.6142 25.59 Second lens 5 1.66430 0.705566 6 -80.21577 0.619776 1.5346 56.27 Third lens 7 -6.08118 0.249085 8  -1.89682 0.721170 1.5346 56.27 Fourth lens 9  -1.06935 0.081081 10 -150.00000  0.916051 1.5311 55.87 Fifth lens 11  1.54412 0.239309 12 ∞ 0.300000 BSC7_HOYA Optical filter 13 ∞ 0.950395 14 ∞ -0.000410 Top

The aspherical coefficients of the fifth embodiment according to Equation 1 are shown in Table 10 below.

if
number
K
A
B
C
D
E 2 -2.517309 0.268111E-01 -.636776E-03 -.179310E-01 0.146119E-01 -.832468E-02 3 -4.070214 0.596714E-01 -.832561E-01 0.632942E-01 -.422103E-01 0.101855E-01 5 -5.068986 0.565392E-01 0.159805E-01 -.496674E-02 0.635267E-02 -.137141E-02 6 0.000000 -.451226E-01 -.267750E-01 0.376621E-01 -.163030E-01 0.422067E-02 7 -0.821332 -.257023E-01 -.765114E-01 0.819021E-01 -.343519E-01 0.503663E-02 8 -3.653166 -.133759E-01 -.609021E-01 0.938436E-01 -.476625E-01 0.751272E-02 9 -3.266806 -.588047E-01 0.360235E-01 0.154566E-02 -.590242E-02 0.110358E-02 10  0.000000 -.271228E-01 0.503267E-02 -.204038E-02 0.416927E-03 -.361568E-04 11 -9.339746 -.373698E-01 0.864250E-02 -.193433E-02 0.213865E-03 -.103066E-04

The above embodiments can be confirmed that the test values within the range satisfying the conditional formulas 1 to 10, shown in Figures 2 to 4, 6 to 8, 10 to 12, 14 to 16 and 18 to 20. As described above, by maintaining good spherical aberration, astigmatism and distortion aberration, an image having excellent quality of high resolution and high definition can be obtained.

In addition, the optical system according to the present invention can improve the distribution of MTF characteristics and lateral color.

In addition, the sensitivity of the lens can be reduced to prevent a decrease in yield, and the incident angle of light incident on the image sensor can be reduced, thereby providing an optical system corresponding to a small pixel size.

L1 to L5: first to fifth lenses
1, 2 and 4 to 11: surface number of first to fifth lenses
3: face number of iris
OF: optical filter
12, 13: face number of the optical filter
IP: Top

Claims (7)

In order from the object side,
A first lens having a positive refractive power, the object-side surface and the image-side surface being convex and aspherical;
A second lens having negative refractive power and having a meniscus shape in which an image side surface is concave;
A third lens having positive refractive power and having an image-side surface convex;
A fourth lens having a positive refractive power and having a meniscus shape in which an image side surface is convex, wherein at least one of the object side surface and the image side surface is an aspherical surface; And
And a fifth lens having a negative refractive power, and having an aspherical surface having a concave and inflection point at an image side thereof, and including the following conditional expressions 1 to 8.
[Condition 1] 1.1 <tt / f <1.5
[Condition 2] 0.5 <f1 / f <1.2
[Condition 3] 25 <Vg1-Vg2 <50
[Condition 4] | Vg3-Vg4 | <15
[Condition 5] | Vg1-Vg3 | <15
[Condition 6] | A3 | > 1.5 * 10 ^-5
[Condition 7] | A4 | > 1.5 * 10 ^-5
[Condition 8] | A5 | > 1.5 * 10 ^-5
Tt: distance from the object-side surface of the first lens to the image surface IP
f: focal length of optical system
f1: focal length of the first lens
Vg1: Abbe number of the first lens
Vg2: Abbe number of the second lens
Vg3: Abbe number of the third lens
Vg4: Abbe number of the fourth lens
A3: coefficient of thermal expansion of the third lens
A4: coefficient of linear thermal expansion of the fourth lens
A5: coefficient of thermal expansion of the fifth lens
delete The method of claim 1,
The ultra-compact optical system which satisfies the following conditional expressions 9 and 10.
[Condition 9] | A1 | > 1.5 * 10 ^-5
[Condition 10] | A2 | > 1.5 * 10 ^-5
Here, A1: coefficient of linear thermal expansion of the first lens
A2: coefficient of thermal expansion of the second lens
The method according to claim 1 or 3,
The micro-optical system further comprises a stop provided between the first lens and the second lens to adjust the amount of light.
The method according to claim 1 or 3,
Miniature optical system, characterized in that the object-side surface of the fifth lens is composed of an aspherical surface having no inflection point.
The method according to claim 1 or 3,
The second lens is an ultra-compact optical system, characterized in that at least one of the object-side surface and the image side surface is aspheric surface.
The method according to claim 1 or 3,
The microscopic optical system according to claim 5, wherein the object-side surface of the fifth lens is concave.

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