KR100577977B1 - Photographing lens system - Google Patents

Abstract

The present invention provides a iris 2 for controlling an amount of light incident from a subject, and a first diffraction grating having a diffraction grating shape having a symmetrical lattice shape on one side of which is rotated symmetrically to an optical axis. A second lens 8 and a rear surface of the second lens 8 including a lens 6 and a rear surface of the first lens 6 and one side thereof having an aspherical surface having positive refractive power, Provided is a lens for image recording, wherein one side thereof comprises a third lens 10 comprising an aspherical surface having positive or negative refractive power.

According to the present invention, there is an effect that a high resolution, easy aberration correction, and a compact low cost image recording lens can be provided.

Image recording lens, diffraction, refraction, lens

Description

Image recording lens {Photographing lens system}

1 is a block diagram showing a lens for recording images of Example 1 according to the present invention;

2 is a graph showing the results of measuring astigmatism and phase distortion of Example 1 according to the present invention;

3 is a block diagram showing a lens for recording images of Example 2 according to the present invention;

4 is a graph showing the results of measuring astigmatism and phase distortion of Example 2 according to the present invention;

5 is a block diagram showing a lens for recording images of Example 3 according to the present invention;

6 is a graph showing the results of measuring astigmatism and phase distortion of Example 3 according to the present invention;

7 is a block diagram showing a lens for recording images of Example 4 according to the present invention;

8 is a graph showing the results of measuring astigmatism and phase distortion of Example 4 according to the present invention;

9 is a block diagram showing an image recording lens of Example 5 according to the present invention;

10 is a graph showing the results of measuring astigmatism and phase distortion of Example 5 according to the present invention.

<Description of Symbols for Main Parts of Drawings>

2: Lens for image recording 4: Aperture aperture

6: first lens 8: second lens

10: third lens 12: flat plate

14: upper surface

The present invention relates to an image recording lens, and more particularly, an image recording in which a lens having a diffraction optical surface shaped like a diffraction grating, a lens having positive refractive power and a lens having positive or negative refractive power are sequentially provided. It relates to a lens for use.

Recently, with the development of digital technology, the improvement of image compression and restoration technology, and the improvement of the performance of peripheral device technology of multimedia products, the production cost reduction of camera lens used in digital still camera, portable information terminal camera, PC camera, surveillance camera, etc. And the situation is continuously researched to implement the thinning.

In addition, the demand for increased production efficiency is due to the rapid spread of CCD cameras using charge coupled devices (CCDs) as video input means for portable computer terminals as well as multimedia computer video conferencing systems. Doing.

In particular, as the number of micro lenses used for mobile phone cameras and digital still cameras, which are portable information terminals, increases, the need for a lens having a wide angle of view, high resolution, high resolution, low volume, low weight, and low cost This is urgently needed.

As an example, cameras for mobile phones start with resolutions of about QVGA (Quarter Video Graphics Array), and in recent years, the need for high resolution lenses for high resolution CCDs or Complementary Metal-Oxide Semiconductor (CMOS) sensors of 2 mega or more is emerging. There is a need for a super-precision lens having a wide angle of more than 1 degree and allowing distortion within 1.5%. In addition, the mobile camera has to be very small in size and length due to its characteristics, and should also be light in weight.

In order to meet the needs of the times, US Patent No. 6,476,982 discloses the construction of a compact lens using two glass lenses and two plastic lenses, but this is satisfactory in terms of resolution and precision. The use of two glass lenses used for chromatic aberration correction increases the volume and weight, and thus there is a problem that it is not suitable as a lens used in a camera for a mobile phone that must be compact and light.

Therefore, the inventors of the present invention can correct the chromatic aberration generated in the conventional lens when using a diffractive optical lens that corrects the chromatic aberration using the diffraction phenomenon of light during the study to overcome the above problems. With this in mind, the present invention has been completed.

The present invention has been made to solve the above problems, and comprises a lens for image recording with a lens having a diffraction grating shaped diffraction optical surface, a lens having a positive refractive power and a lens having a positive or negative refractive power Therefore, there is a technical problem in providing a lens for image recording having a wide view angle, high resolution, high resolution, easy chromatic aberration correction, and a compact and low cost.

According to an aspect of the present invention, there is provided an aperture stop for controlling an amount of light incident from a subject, a first lens including a diffraction grating having a diffraction grating shape that is provided at a rear of the aperture and at least one surface is rotationally symmetric to an optical axis, the first lens A second lens provided at the rear of the lens and having at least one surface having positive dioptric power is an aspherical surface and a third lens provided at the rear of the second lens having at least one surface having a negative or positive refractive power aspheric surface It provides a lens for image recording, characterized in that consisting of a lens.

At least one side of the third lens is further provided with a coated flat plate for absorbing or reflecting light of a specific wavelength.

In this case, the first lens satisfies the following conditional expression (1), and in the case of the image recording lens, the total length of the image recording lens along the optical axis must satisfy the following conditional expression (2).

0.75 <F ₁ / F _E <2.65 ..... (1)

TTL / F _E <1.78 ..... (2)

here,

F ₁ is the focal length of the first lens,

F _E is the focal length of the entire image recording lens,

TTL means the entire length of the image recording lens along the optical axis.

Meanwhile, an image recording lens according to the present invention includes at least three or more lenses therein, and is provided with at least three or more lenses to record an image by expressing light flowing from a subject on an upper surface thereof. In the present invention, the whole is referred to as an image recording lens, and the entire lens group provided to constitute the image recording lens is referred to as a lens system.

On the other hand, conditional expression (1) limits the intrinsic ability of the first lens, and if F ₁ / F _E is out of the range of the conditional expression (1), excessive chromatic aberration, spherical aberration and coma aberration may occur. .

In addition, the conditional expression (2) limits the length of the entire image recording lens along the optical axis of the image recording lens, and when the TTL / F _E is out of the range of the conditional expression (2), The long length prevents the compact lens for compact image recording.

The first lens according to the present invention may be any lens as long as the lens corrects chromatic aberration by using light diffraction, but preferably at least one diffraction grating has a diffraction grating shape that is rotationally symmetric to the optical axis. It is preferable to use a diffractive optical lens having

Here, the diffractive optical lens means that the diffraction phenomenon and the refraction phenomenon are designed to be generated at the same time. The color aberration generated by the diffraction phenomenon and the refraction phenomenon is corrected by the diffraction and refraction of the lens, thereby significantly reducing chromatic aberration. Can be.

The second lens according to the present invention may be any lens as long as at least one surface having positive refractive power is aspheric, and any lens having positive refractive power known in the art may be used. You may.

The third lens according to the present invention may be any lens as long as at least one surface including negative or positive refractive power is aspheric, but generally includes negative or positive refractive power used in the art. Any lens can be used.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing an image recording lens of Example 1 according to the present invention, Figure 2 is a graph showing the results of measuring astigmatism and image distortion of Example 1 according to the present invention, Figure 3 is a present invention 4 is a block diagram showing a result of measuring astigmatism and image distortion of Example 2 according to the present invention, and FIG. 5 is an image of Example 3 according to the present invention. 6 is a graph showing a result of measuring astigmatism and image distortion of Example 3 according to the present invention, and FIG. 7 is a view showing the lens for image recording according to Example 4 of the present invention. 8 is a graph showing the results of measuring astigmatism and image distortion of Example 4 according to the present invention, FIG. 9 is a block diagram showing an image recording lens of Example 5 according to the present invention, and FIG. Astigmatism of Example 5 According to the Invention The results of measuring the phase distortion will be described with an illustrated graph.

As shown in Figs. 1 to 10, an image recording lens 2 according to the present invention is provided with an aperture 4 for controlling the amount of light incident from a subject and at the rear of the aperture 4 at least. A first lens 6 including a diffraction grating having a diffraction grating shape in which one surface is rotationally symmetric with respect to the optical axis, and a second at least one surface having a positive refractive power, which is provided behind the first lens 6 and is aspherical; At least one surface having a negative or positive refractive power is provided as a third lens 10 provided behind the lens 8 and the second lens 8.

In addition, the image recording lens 2 is further provided with one flat plate 12 behind the third lens 10.

Here, at least one surface of the flat plate 12 is formed with a coating layer (not shown) for absorbing or reflecting light having a wavelength of 620 nm or more, and the coating layer may be used as long as it is commonly used in the art. Do.

Meanwhile, the first lens 6 according to the present invention satisfies the following conditional expression (1), and in the case of the image recording lens, the total length of the image recording lens along the optical axis must satisfy the following conditional expression (2). do.

0.75 <F ₁ / F _E <2.65 ..... (1)

TTL / F _E <1.78 ..... (2)

here,

F ₁ is a focal length of the first lens,

F _E is a focal length of the entire image recording lens,

The TTL means the entire length of the image recording lens along the optical axis.

At this time, the TTL is calculated after excluding the planar plate 12.

The conditional expression (1) limits the intrinsic ability of the first lens 6, i.e., the total length of the lens for image recording if the first lens 6 is weakened to the extent exceeding the lower limit of F ₁ / F _E. If is longer and becomes strong enough to exceed the upper limit of F ₁ / F _E , excessive chromatic aberration, spherical aberration and coma aberration may occur in the first lens 6.

In addition, the conditional expression (2) limits the total length of the image recording lens along the optical axis of the image recording lens, and the image recording lens when the TTL / F _E is out of the range of the conditional expression (2) The total length of the lens becomes long, which makes it impossible to construct a compact image recording lens.

The first lens 6 according to the present invention may be any lens as long as the lens corrects chromatic aberration by using the diffraction phenomenon of light. However, at least one surface of the first lens 6 has a diffraction grating shape having rotational symmetry on the optical axis. A diffractive optical lens having a diffractive optical surface, particularly preferably the S2 plane located on the rear surface of the first lens 6 with respect to the direction in which light is incident is a diffraction optical surface in the form of a diffraction grating which is rotationally symmetric to the optical axis. It is preferable that the other side facing is aspherical.

Here, the diffractive optical lens means that the diffraction phenomenon and the refraction phenomenon are designed to be generated at the same time. The color aberration generated by the diffraction phenomenon and the refraction phenomenon is corrected by the diffraction or refraction of the lens, thereby significantly reducing chromatic aberration. Can be.

In general, the diffractive optical surface has a negative Abbe's number, and a general refractive surface with a positive dispersion coefficient has a shorter focal length and a diffractive optical surface having a negative dispersion coefficient. On the contrary, the shorter the wavelength, the longer the focal length. Therefore, if the lens system is constructed using the diffractive optical lens element having both of these properties, it is possible to construct a lens for image recording, which has not only chromatic aberration correction but also high resolution, excellent wide angle, small size and light weight. The first lens 4 according to the present invention includes both the above-described diffraction and refraction.

In particular, a lens system consisting only of a general refractive lens is a combination of a lens element having a relatively large dispersion coefficient and a positive refractive power, and a lens element having a relatively small dispersion coefficient and a negative refractive power. Or by a combination of a lens element having a relatively small dispersion coefficient and a positive refractive power and a lens element having a relatively large dispersion coefficient and a negative refractive power. Therefore, to correct chromatic aberration, lens elements having different dispersion coefficients should be used, which limits the number of lens elements used and thus prevents the use of relatively small plastic lenses.

The second lens 8 according to the present invention may be any lens as long as at least one surface including positive refractive power is aspheric, and generally includes a lens having positive refractive power known in the art. It is good to use.

The third lens 10 according to the present invention may be any lens as long as at least one surface including positive or negative refractive power is aspherical, but preferably any positive or negative commonly used in the art. It is better to use a lens that includes refractive power.

Here, the distance between the second lens 8 and the third lens 10 is configured to be closer to the optical axis and farther from the optical axis (FIGS. 1, 3, 5, 7 and 9). .

On the other hand, the aspherical surfaces of the first lens 6, the second lens 8, and the third lens 10 constituting the image recording lens according to the present invention are shaped by the following equation 1 with respect to the distance r from the optical axis. Can be expressed.

here,

Z is a sag value of an aspherical surface parallel to the optical axis,

C is the curvature (curvature) at the aspherical vertex,

K is the conic coefficients of the aspherical surface,

A, B, C, D, E, F, G, H and J are aspherical surfaces corresponding to 4th, 6th, 8th, 10th, 12th, 14th, 16th, 18th, and 20th, respectively. Means coefficients.

In addition, the diffraction grating shape of the diffraction grating, which is rotationally symmetrical, on the optical axis of the image recording lens according to the present invention includes a spherical or aspherical shape, so that refraction and diffraction occur simultaneously. The phase profile is corrected for the distance r from the optical axis by correcting the chromatic aberration of.

here,

₀은 기준파장이고,remind

₀ is the reference wavelength,

C ₁ , C ₂ , C _3, and the like are second, fourth, sixth, and respective phase coefficients.

The values of the variables included in Equations 1 and 2 are set according to the image recording lens in which the lens is used. That is, when the image recording lens is set, the performance of the lens for using the image recording lens is also determined. Therefore, according to the set value, the values of the variables included in Equations 1 and 2 are determined.

Hereinafter, the present invention will be described in detail through examples. However, the following examples are only for illustrating the present invention in detail and are not intended to limit the scope of the present invention by these examples.

<Example 1>

As shown in FIG. 1, the aperture 4, the first lens 6, the second lens 8, the third lens 10, the flat plate 12, and the upper surface 14 are sequentially installed. A lens for image recording was constructed.

Here, the configuration conditions of the aperture 4, the first lens 6, the second lens 8 and the third lens 10, for example, the focal length, the length of the entire lens system, the number of Fs. , Radius of curvature, distance, and the like are shown in Tables 1 to 3, and the results are shown in FIG.

Meanwhile, a in FIG. 2 represents an astigmatic field curve, and b in FIG. 2 represents distortion. In this case, the solid line and the dotted line in FIG. 2 indicate the sagittal and tangential directions, respectively.

F _E F ₁ / F _E TTL / F _E FNO TTL ANG value 3.9067 1.0904 1.2901 2.5800 5.0402 62.0000

Here, F _E is the total focal length, F ₁ is the focal length of the first lens, TTL is the length of the image recording lens for the optical axis (calculated after focusing except the flat plate), FNO is F / Number, and ANG means Field Angle.

Surface number Bending Radius (R) (mm) Distance (D) (mm) Nd Vd ss infinity 0.094506 S1 1.76357 0.660548 1.52996 56.35 S2 5.29982 1.194181 S3 -0.96494 0.640000 1.52996 56.35 S4 -1.14855 0.100000 S5 1.58500 0.720000 1.52996 56.35 S6 1.50260 0.790764 S7 infinity 0.550000 1.51680 64.2 S8 infinity 0.450000

Where R is the radius of curvature, D is the distance between the lens and the lens, Nd is the d-line index, Vd is the dispersion coefficient.

Aspheric Data and Phase Coefficient S1 K A B C D E -5.902425 0.139638E + 00 -0.682554E-01 0.383472E-01 -0.645628E-02 S2 C1 C2 C3 C4 C5 C6 -1.2221E-02 5.9592E-03 -1.4875E-03 -5.1247E-03 2.7529E-03 2.0438E-04 S3 K A B C D E -5.556835 -0.465556E + 00 0.299101E + 00 -0.140565E + 00 0.998126E-01 -0.464441E-01 S4 K A B C D E -2.707275 -0.213176E + 00 0.538981E-01 0.411830E-01 -0.1056925E-01 0.439062E-03 S5 K A B C D E -2.068034 -0.213567E + 00 0.136253E + 00 -0.471556E-01 0.842375E-02 -0.633850E-03 S6 K A B C D E -1.303693 -0.212599E + 00 0.941569E-01 -0.264779E-01 0.399415E-02 -0.263959E-03

<Example 2>

As shown in FIG. 3, the aperture 4, the first lens 6, the second lens 8, the third lens 10, the flat plate 12, and the upper surface 14 are sequentially installed. A lens for image recording was constructed.

Here, the configuration conditions of the aperture 4, the first lens 6, the second lens 8 and the third lens 10, for example, the focal length, the length of the entire lens system, the number of Fs. , Radius of curvature, distance, and the like are shown in Tables 4 to 6, and the results are shown in FIG.

Meanwhile, a in FIG. 4 represents astigmatism curves, and b in FIG. 4 represents image distortion. At this time, the solid line and the dotted line in Fig. 4 represent the sphere and the tangential direction, respectively.

F _E F ₁ / F _E TTL / F _E FNO TTL ANG value 4.2941 1.1791 1.3790 2.5800 5.9217 62.0000

Here, F _E is the total focal length, F ₁ is the focal length of the first lens, TTL is the length of the image recording lens with respect to the optical axis (length calculated after focusing except the flat plate), FNO is F / Number, and ANG means angle of view.

Surface number Bending Radius (R) (mm) Distance (D) (mm) Nd Vd ss infinity 0.094506 S1 2.22490 1.156739 1.52996 56.35 S2 7.50758 1.158891 S3 -1.15188 0.800000 1.52996 56.35 S4 -1.15400 0.100000 S5 2.27221 0.880000 1.52996 56.35 S6 1.72465 0.663317 S7 infinity 0.550000 1.51680 64.2 S8 infinity 0.700000

Where R is the radius of curvature, D is the distance between the lens, Nd is the d-line index, and Vd is the dispersion coefficient.

Aspheric Data and Phase Coefficient S1 K A B C D E -2.132443 0.269753E-01 -0.119287E-02 0.243376E-02 -0.405456E-03 S2 C1 C2 C3 C4 C5 C6 -1.0481E-02 -6.6143E-04 9.9680E-03 -1.6828E-02 1.1344E-02 -2.8049E-03 S3 K A B C D E -0.290500 0.163910E-01 -0.195760E + 00 0.271659E + 00 -0.120620E + 00 0.255151E-01 S4 K A B C D E -0.881332 -0.124555E + 00 0.104645E + 00 -0.677734E-01 0.328980E-01 -0.530439E-02 S5 K A B C D E -1.681317 -0.214439E + 00 0.152951E + 00 -0.585973E-01 0.114877E-01 -0.939313E-03 S6 K A B C D E -1.359059 -1.95596E + 00 0.886561E-01 -0.242869E-01 0.347771E-02 -0.211057E-03

<Example 3>

As shown in FIG. 5, the aperture 4, the first lens 6, the second lens 8, the third lens 10, the flat plate 12, and the upper surface 14 are sequentially installed. A lens for image recording was constructed.

Here, the configuration conditions of the aperture 4, the first lens 6, the second lens 8 and the third lens 10, for example, the focal length, the length of the entire lens system, the number of Fs. , Radius of curvature, distance, and the like are shown in Tables 7 to 9, and the results are shown in FIG.

On the other hand, a of FIG. 6 shows astigmatism curves, and b of FIG. 6 shows image distortion. At this time, the solid line and the dotted line in Fig. 6 represent the sphere and the tangential direction, respectively.

F _E F ₁ / F _E TTL / F _E FNO TTL ANG value 4.4792 1.1534 1.3614 2.6000 6.0981 60.0000

Here, F _E is the total focal length, F ₁ is the focal length of the first lens, TTL is the length of the image recording lens with respect to the optical axis (length calculated after focusing except the flat plate), FNO is F / Number, and the ANG means an angle of view.

Surface number Bending Radius (R) (mm) Distance (D) (mm) Nd Vd ss infinity 0.094506 S1 2.29334 1.219159 1.52996 56.35 S2 8.16030 1.308960 S3 -1.10667 0.800000 1.52996 56.35 S4 -1.09606 0.100000 S5 2.26231 0.880000 1.52996 56.35 S6 1.56613 0.625377 S7 infinity 0.550000 1.51680 64.2 S8 infinity 0.700000

Where R is the radius of curvature, D is the distance between the lens, Nd is the d-line index, and Vd is the dispersion coefficient.

Aspheric Data and Phase Coefficient S1 K A B C D E -9.270039 0.945460E-01 -0.511351E-01 0.258513E-01 -0.573770E-02 S2 C1 C2 C3 C4 C5 C6 -9.4726E-03 2.0376E-03 5.5567E-04 -2.4209E-03 1.0010E-03 S3 K A B C D E -3.721404 -0.227660E + 00 0.751258E-01 0.630975E-02 -0.622023E-02 0.928457E-03 S4 K A B C D E -1.640050 -0.547232E-01 0.234735E-02 0.681018E-02 0.130424E-02 -0.417422E-03 S5 K A B C D E -7.834327 -2.40161E-01 0.191893E-01 -0.601543E-02 0.899197E-03 -0.565410E-04 S6 K A B C D E -6.050980 -0.487147E-01 0.199259E-01 -0.459951E-02 0.520503E-03 -0.261821E-04

<Example 4>

As shown in FIG. 7, the aperture 4, the first lens 6, the second lens 8, the third lens 10, the flat plate 12, and the upper surface 14 are sequentially installed. A lens for image recording was constructed.

Here, the configuration conditions of the aperture 4, the first lens 6, the second lens 8 and the third lens 10, for example, the focal length, the length of the entire lens system, the number of Fs. , Radius of curvature, distance, and the like are shown in Tables 10 to 12, and the results are shown in FIG.

On the other hand, a of FIG. 8 shows astigmatism curves, and b of FIG. 8 shows image distortion. At this time, the solid line and the dotted line in Fig. 8 represent the sphere and the tangential direction, respectively.

F _E F ₁ / F _E TTL / F _E FNO TTL ANG value 3.9128 1.0852 1.2905 2.5800 5.0496 62.0000

Here, F _E is the total focal length, F ₁ is the focal length of the first lens, TTL is the length of the image recording lens with respect to the optical axis (length calculated after focusing except the flat plate), FNO is F / Number, and ANG means Field Angle.

Surface number Bending Radius (R) (mm) Distance (D) (mm) Nd Vd ss infinity 0.094506 S1 1.79239 0.754710 1.52996 56.35 S2 5.76663 1.213343 S3 -0.95972 0.640000 1.52996 56.35 S4 -1.23898 0.100000 S5 1.33594 0.720000 1.52996 56.35 S6 1.33776 1.527077 S7 infinity 0.550000 1.51680 64.2 S8 infinity 0.450000

Where R is the radius of curvature, D is the distance between the lens, Nd is the d-line index, and Vd is the dispersion coefficient.

Aspheric Data and Phase Coefficient S1 K A B C D E -6.302528 0.138590E + 00 -0.726570E-01 0.413681E-01 -0.769415E-02 S2 C1 C2 C3 C4 C5 C6 -1.0731E-02 3.7660E-03 1.4780E-03 -8.8075E-03 4.8781E-03 -1.9189E-04 S3 K A B C D E -6.074066 -0.494328E + 00 0.417973E + 00 -0.338616E + 00 0.227492E + 00 -0.752325E-01 S4 K A B C D E -2.443321 -0.197984E + 00 0.1717787E-01 0.112378E-01 -0.149957E-02 -0.216053E-03 S5 K A B C D E -3.983813 -0.106457E + 00 0.693957E-01 -0.218769E-01 0.356041E-02 -0.245545E-03 S6 K A B C D E -1.205704 -0.190826E + 00 0.752042-01 -0.178980E-01 0.234869E-02 -0.139932E-03

Example 5

As shown in FIG. 9, the aperture 4, the first lens 6, the second lens 8, the third lens 10, the flat plate 12, and the upper surface 14 are sequentially installed. A lens for image recording was constructed.

Here, the configuration conditions of the aperture 4, the first lens 6, the second lens 8 and the third lens 10, for example, the focal length, the length of the entire lens system, the number of Fs. , Radius of curvature, distance, and the like are shown in Tables 13 to 15, and the results are shown in FIG.

Meanwhile, a in FIG. 10 represents astigmatism curves, and b in FIG. 10 represents image distortion. At this time, the solid line and the dotted line in Fig. 10 represent the sphere and the tangential direction, respectively.

F _E F ₁ / F _E TTL / F _E FNO TTL ANG value 4.4764 1.1035 1.3373 2.6000 5.9862 60.0000

Here, F _E is the total focal length, F ₁ is the focal length of the first lens, TTL is the length of the image recording lens with respect to the optical axis (length calculated after focusing except the flat plate), FNO is F / Number, and ANG means angle of view.

Surface number Bending Radius (R) (mm) Distance (D) (mm) Nd Vd ss infinity 0.094506 S1 2.11153 1.146678 1.52996 56.35 S2 6.59641 1.211993 S3 -1.07815 0.800000 1.52996 56.35 S4 -1.10420 0.100000 S5 2.56296 0.880000 1.52996 56.35 S6 1.84512 0.675965 S7 infinity 0.550000 1.51680 64.2 S8 infinity 0.700000

Where R is the radius of curvature, D is the distance between the lens, Nd is the d-line index, and Vd is the dispersion coefficient.

Aspheric Data and Phase Coefficient S1 K A B C D E -1.106879 0.172257E-01 0.100312E-02 0.100953E-02 0.196428E-03 S2 C1 C2 C3 C4 C5 C6 -1.0271E-02 2.0273E-03 1.7379E-03 -4.4033E-03 1.7861E-03 S3 K A B C D E -2.790546 -0.185395E + 00 0.103461E-01 0.451310E-0 -0.121076E-01 -0.128443E-03 S4 K A B C D E -0.738341 0.348715E-01 -0.185813E-01 0.142327E-01 0.166975E-02 -0.533795E-03 S5 K A B C D E -3.338606 -0.499580E-01 0.236067E-01 -0.573931E-02 0.645713E-03 -0.258150E-04 S6 K A B C D E -6.985293 -0.445029E-01 0.130877E-01 -0.224157E-02 0.110001E-03 0.357711E-05

As described above, the numerical values shown in the examples of the first to fifth embodiments satisfy the conditional expressions (1) and (2) and the equations (1) and (2), and as shown in the aberration curves in the respective embodiments, respectively. The aberration is also corrected well.

As described above, those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. Therefore, the exemplary embodiments described above are to be understood as illustrative in all respects and not as restrictive. The scope of the present invention should be construed that all changes or modifications derived from the meaning and scope of the appended claims and their equivalents, rather than the detailed description, are included in the scope of the present invention.

As described above, the present invention has the effect of providing a high-resolution, easy-to-chromatic aberration correction lens and a compact, low cost image recording lens.

Claims (6)

A first lens 6 including an aperture 4 for adjusting an amount of light incident from a subject, and a diffraction grating having a diffraction grating like a mirror symmetry having at least one surface rotationally symmetric to an optical axis. ), A second lens 8 provided at the rear of the first lens 6 and having at least one surface having positive refractive power is an aspherical surface and provided at the rear of the second lens 8 and having a negative or positive refraction. At least one surface having a ridge includes a third lens 10 which is an aspherical surface, wherein the first lens 6 satisfies the following conditional expression (1), and the whole of the image recording lens 2 with respect to the optical axis. A video recording lens, characterized in that the length satisfies the following conditional expression (2). Conditional Expression (1): 0.75 <F ₁ / F _E <2.65 Conditional Expression (2): TTL / F _E <1.78 here, F ₁ is the focal length of the first lens, F _E is the focal length of the entire image recording lens, The TTL is the length of the entire image recording lens along the optical axis. The method of claim 1, And one flat plate (12) at the rear of the third lens (10), wherein the thickness of the flat plate (12) is excluded when measuring the TTL. The method of claim 2, One side of the flat plate (12) is an image recording lens, characterized in that provided with a coating layer for absorbing or reflecting light having a wavelength of 620nm or more. The method of claim 1, And said first lens (6) has a concave diffraction optical surface in the shape of a diffraction grating whose one side is rotationally symmetric to the optical axis. The method according to any one of claims 1 to 4, The first lens (6) has a diffraction grating-shaped diffraction optical surface of which one side is rotationally symmetrical on the optical axis, and the other side opposite thereto is an aspherical surface. The method according to any one of claims 1 to 4, And the distance between the second lens (8) and the third lens (10) is closer to the optical axis and further away from the optical axis.

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