KR19990053707A - Telephoto Lens Using Kenoform Element - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a telephoto lens using a kinoform element, comprising a lens using a kinoform element from an object side, including a front lens group having a positive refractive power as a whole, and a rear lens group having a negative refractive power. By constructing a telephoto lens using a general lens using a kinofoam element instead of a lens having a low dispersion material, the price is significantly lower than that of a lens having a low dispersion material, and the resolution is improved. There are no restrictions on the use of low-dispersion materials, and the range of applications is broad.

Description

Telephoto Lens Using Kenoform Element

The present invention relates to a telephoto lens using a kinoform element. More specifically, a large-diameter telephoto lens or an infrared ray is used by using a lens using a kinoform element, which is a type of HOG (Holograpic Optical Element) on one surface. The present invention relates to a telephoto lens optical system using a kinoform element capable of producing the same effect as a spherical lens of an optical system.

In general, a telephoto lens is a lens designed with a telephoto lens whose length from the film surface to the front of the lens is shorter than a focal length. However, since most of the long focal length lenses used for photographing are designed with a telephoto lens type. Other designs, such as long focal length or mirror lenses, may be referred to as long focal length lenses.

1 is an example of the telephoto lens.

In FIG. 1, two lenses having a low dispersion material are used, but the number of lenses having a low dispersion material may be varied to configure a telephoto lens.

The telephoto lens shown in FIG. 1 has a focal length of 300 mm and a lens brightness of F4.0. The number of lenses constituting the telephoto lens is 7, and the total length is 243 mm.

In addition, the two hatched lenses of the telephoto lens have a refractive index of 1.497 and a dispersion of 81.6.

The telephoto lens having the above configuration has a long focal length by the two hatched lenses, and thus may serve as a telephoto lens.

However, the two hatched lenses should use a low dispersion material having a large outer diameter. The reason why the two hatched lenses are used as a low dispersion material is that the low dispersion material lens has an excellent effect of removing chromatic aberration.

Since chromatic aberration is related to resolution, the use of low dispersion materials is an important factor in performance.

In addition, in the case of a high-quality telephoto lens, a low dispersion material should be used because the lens outer diameter is large, but a lens having a low dispersion material has a high cost, resulting in a high cost burden.

Accordingly, the present invention is to solve the conventional problems, and to provide a telephoto lens using a kinofoam element that can use a lens having a common material using a kinoform element instead of a lens having a low dispersion lens.

1 is a configuration diagram of a conventional telephoto lens optical system,

2 is a configuration diagram of a telephoto lens using a kinoform element according to an embodiment of the present invention,

3 (a) and 3 (b) are state diagrams of a lens using a kinoform element for explaining the HOE technology applied to the embodiment of the present invention.

4 (a) and 4 (b) are state diagrams of a center portion and an edge portion of a lens using a kinoform element used for a telephoto lens using a kinoform element according to an embodiment of the present invention.

5 is a spherical aberration diagram of a telephoto lens using a kinoform element according to an embodiment of the present invention,

6 is an astigmatism diagram of a telephoto lens using a kinoform element according to an embodiment of the present invention,

7 is a distortion aberration diagram of a telephoto lens using a kinoform element according to an embodiment of the present invention.

The present invention as a means for solving the above technical problem

An all-group lens including a lens using a kinofoam element from the object side and having positive refractive power as a whole;

It includes a rear lens group having negative refractive power, and satisfies the following equation.

In the above equation, vd1: Abbe's number for the first lens from the object side

f: total lens focal length

Φ1 : Power against all forces

f1: Focal length for all forces.

By the above-described configuration, a person having ordinary skill in the art to which the present invention pertains will be described in detail with reference to the accompanying drawings.

2 is a configuration diagram of a telephoto lens using a kinoform element according to an embodiment of the present invention.

As shown in FIG. 2, the telephoto lens using the kinoform element according to the embodiment of the present invention includes a lens using the kinoform element from the object side, and has an overall group having positive refractive power. A lens 1;

The rear lens group 2 includes a first lens group 21 having a negative refractive power as a whole, and a second group of lenses 2 composed of a second lens group 22 having a positive refractive power.

The front lens group 1 includes a first lens 11 having a positive refractive power, a second lens 12 having a positive refractive power, and a second lens 12 having a positive refractive power applied to an image side from an object side. And a third lens 13 bonded to 12 and having negative refractive power.

The first lens group 21 of the rear lens group 2 includes a fourth lens 211 having negative refractive power and a fifth lens 212 having positive refractive power, and the rear lens 22. The second lens group 22 may include a sixth lens 221 having negative refractive power, a seventh lens 222 having positive refractive power, and a filter 223 for filtering light passing through the seventh lens 222. It is made to include.

3 (a) and 3 (b) are state diagrams of a lens using a kinoform element for explaining the HOE technique applied to the embodiment of the present invention.

That is, the lenses shown in (a) and (b) of FIG. 3 are Fresnel lenses to which HOE is applied, (a) is a side view of the Fresnel lens, and (b) is the Fresnel lens. Front view of the lens.

As shown in (a) and (b) of FIG. 3, (a) is provided with a plurality of tooth-shaped grooves symmetrically centered on one side of the lens, and (b) A plurality of concentric grooves are formed around the center. Light is diffracted by the grooves of the plurality of concentric circles formed as described above, and a kinoform element such as the grooves of the plurality of concentric circles is applied to the eye side of the first lens shown in FIG. 2.

4 (a) and 4 (b) are state diagrams of a center portion and an edge portion of a lens using a kinoform element used in a telephoto lens using a kinoform element according to an embodiment of the present invention.

That is, FIG. 4 is a state diagram showing the width of the kinoform element applied to the eye side of the first lens from the object side shown in FIG.

As shown in FIGS. 4A and 4B, the width of the kinoform element becomes narrower from the center portion of the lens toward the edge.

5 is a spherical aberration diagram of a telephoto lens using a kinoform element according to an embodiment of the present invention,

6 is an astigmatism diagram of a telephoto lens using a kinoform element according to an embodiment of the present invention,

7 is a distortion aberration diagram of a telephoto lens using a kinoform element according to an embodiment of the present invention.

A telephoto lens using a kinoform element according to an embodiment of the present invention will be described with reference to the attached FIGS. 1 to 7.

The light reflected by the subject is incident on the first lens 11 having the positive refractive power of the entire group 1.

Light incident on the first lens 11 is refracted at the object side, and the refracted light is diffracted at the eye side. The first lens 11 has a positive refractive power, and a kinoform element is applied to the eye side.

The first lens 11 to which the eye side is applied the kinoform errorment has the same effect as the low dispersion material and has a long focal length. The light diffracted at the eye side of the first lens 11 passes through the second lens 12 of the entire group 1 having positive refractive power, is bonded to the second lens 12, and has negative refractive power. The branches pass through the third lens 13 of the entire group 1.

The light passing through the third lens 13 is incident on the first lens group 21 of the rear group 2 to provide positive refractive power with the fourth lens 211 having negative refractive power of the first lens group 21. The branch passes through the fifth lens 212 and has negative refractive power as a whole.

The light passing through the first lens group 21 is incident to the second lens group 22 having the overall positive refractive power of the rear group 2 through the aperture, and has a negative refractive power of the second lens group 22. The six lenses 221 pass through the seventh lens 222 and the filter 223 having positive refractive power.

The shape of the kinoform element formed on the eye side surface of the first lens 11 of the front group 1 is determined according to the coefficient obtained by the following equation.

The coefficients for the kenoform element are:

V (y) = C ₁ y ² + C ₂ y ⁴ + C ₃ y ⁶ + ...

y = mh _x Y × h where we normalize to h = 1

In Equations 1 and 2, V (y) Is the characteristic equation of the kinoform element,

C ₁ , C ₂ , C ₃ Is the kinoform element coefficient,

mh _x Y Is a scale, which is 37.5.

Solving equation 4 in equation 3 above to solve,

A ₁ = C ₁ × mh _x Y ² , A ₂ = C ₂ × mh _x Y ² , A ₃ = C ₃ × mh _x Y ² , ...

The value comes out, the above A ₁ , A ₂ , A ₃ ... can be obtained by the following equation (5).

Z = distance from the lens vertex to the optical axis

y = distance in the direction perpendicular to the optical axis

C = inverse of the lens radius of curvature

K = Conic constant

A ₄ , A ₆ , A ₈ , A ₈ , Aspherical coefficient

By Equation 5 above

A ₁ = 0.066566250, A ₂ = 0.000016412 A ₃ = 0.000000002.

Therefore, the kinoform element coefficient

C ₁ = -4.7336 × 10 ^-5 , C ₂ = 1.153 × 10 ^-8 , C ₃ = -1.6248 × 10 ^-12 to be.

By substituting the kinoform element coefficient obtained above into the kinoform element characteristic equation, a special power of the first lens 11 can be obtained.

As described above, when the kinoform element is used on the eye side of the first lens 1, Equation 1 may be satisfied.

Equations 1 and 2 are equations representing the power range of the first lens.

The value of the first embodiment according to the embodiment of the present invention, which satisfies Equation 1 and Equation 2, is shown in Table 1 below.

In Table 1, r is a radius of curvature, d is a thickness of a lens and a distance between lenses, nd is a d-line refractive index, and vd is an Abbe's number.

Cotton number Radius of curvature (r) Thickness and distance (d) Refractive Index (nd) Abe number (vd) One 149.550 8.5 1.51633 64.10 2 ∞ (K.E applied) 15.0 1.0 3 149.550 12.00 1.72825 28.41 4 -148.130 0.03 1.0 5 -148.130 6.5 1.48749 70.41 6 -457.271 47.131 1.0 7 ∞ 2.0 1.0 8 692.331 4.0 1.72825 28.41 9 42.321 7.118 1.0 10 41.151 5.5 1.62193 37.04 11 63.872 29.0 1.0 iris ∞ 8.0 1.0 13 13390.745 2.5 1.62193 37.04 14 52.605 13.163 1.0 15 90.979 5.0 1.54814 45.75 16 -129.420 6.5 1.0 17 ∞ 4.0 1.51633 64.10 18 ∞ 46.689 1.0 19 ∞ 37.0152 1.0

In Table 1, surfaces 7 and 12 are mechanical surfaces that allow a corresponding amount of light to pass through.

The value of the second embodiment according to the embodiment of the present invention satisfying Equations 1 and 2 is shown in Table 2 below.

In Table 1, r is a radius of curvature, d is a thickness of a lens and a distance between lenses, nd is a d-line refractive index, and vd is an Abbe's number.

Cotton number Radius of curvature (r) Thickness and distance (d) Refractive Index (nd) Abe number (vd) One 135.233 8.5 1.51633 64.10 2 ∞ (K.E applied) 15.0 1.0 3 147.527 12.00 1.48749 70.41 4 -144.896 0.03 1.0 5 -144.694 6.5 1.72825 28.41 6 -470.454 31.51 1.0 7 ∞ 2.0 1.0 8 437.189 4.0 1.48749 70.41 9 44.126 7.12 1.0 10 45.451 5.5 1.62193 37.04 11 76.153 29.0 1.0 iris ∞ 8.0 1.0 13 -247.778 2.5 1.62193 37.04 14 68.695 16.527 1.0 15 200.782 5.0 1.54814 45.75 16 -86.302 6.495 1.0 17 ∞ 4.0 1.51633 64.10 18 ∞ 46.689 1.0 19 ∞ 55.999 1.0

In the above, the seventh and twelve sides are mechanical surfaces that allow a corresponding amount of light to pass through.

In the present invention, the telephoto lens is constructed by using a general lens using a kinofoam element instead of a lens having a low dispersion material, thereby significantly lowering the cost and improving the resolution than a lens having a low dispersion material. There are no restrictions on the use of low-dispersion materials, and the range of applications is broad.

Claims (5)

An all-group lens including a lens using a kinofoam element from the object side and having positive refractive power as a whole; A telephoto lens using a kinoform element comprising a rear lens group having negative refractive power. The method of claim 1, wherein the front lens group is A telephoto lens using a kinoform element characterized by satisfying the following equation. In the above equation, vd1: Abbe's number for the first lens from the object side f: total lens focal length Φ1 : Power against all forces f1: Focal length for all forces. The method of claim 1, wherein the front lens group is From the object side, a telephoto lens using a kinoform element, characterized in that it comprises a first lens 11 having positive refractive power, a second lens 12 having positive refractive power, and a third lens having negative refractive power. . The method of claim 3, wherein the front lens group A telephoto lens using a kinoform element, characterized in that the kinoform element is applied to the eye side of the first lens 11 which is the first lens from the object side. The method of claim 1, wherein the rear lens group is The first lens group 21 including the fourth lens 211 having negative refractive power on the object side and the fifth lens 212 having positive refractive power on the object side and the sixth lens 221 having negative refractive power on the eye side. And a second lens group including a seventh lens group 222 having positive refractive power.