阅读说明：本技术 一种目镜光学系统 (Eyepiece optical system ) 是由 廖明燕 林清泉 于 2020-12-30 设计创作，主要内容包括：本发明涉及镜头技术领域。本发明公开了一种目镜光学系统,从目侧至显示侧沿一光轴依次包括第一透镜至第四透镜,第一透镜和第三透镜为具正屈光率的凸凸透镜,第二透镜为具正屈光率的凹凸透镜,第四透镜为具负屈光率的凹凹透镜,第一透镜和第二透镜的目侧面和显示侧面均为非球面；第三透镜与第四透镜相互胶合,第三透镜与第四透镜均为玻璃透镜。本发明具有视场角大,岀瞳距离大,分辨率高,成像质量好,镜片数少,小型化,量产良率好的优点。(The invention relates to the technical field of lenses. The invention discloses an eyepiece optical system, which sequentially comprises a first lens, a second lens, a third lens, a fourth lens and a third lens from an eye side to a display side along an optical axis, wherein the first lens and the third lens are convex lenses with positive refractive indexes, the second lens is a concave-convex lens with positive refractive indexes, the fourth lens is a concave-concave lens with negative refractive indexes, and the eye side surfaces and the display side surfaces of the first lens and the second lens are aspheric surfaces; the third lens and the fourth lens are mutually glued, and both the third lens and the fourth lens are glass lenses. The invention has the advantages of large field angle, large exit pupil distance, high resolution, good imaging quality, few lenses, miniaturization and good yield of mass production.)

1. An eyepiece optical system for imaging an imaging light from a display screen through the eyepiece optical system into an eye of an observer, the direction toward the eye being a target side and the direction toward the display screen being a display side, the eyepiece optical system comprising: the eyepiece optical system comprises a first lens, a second lens and a third lens in sequence from an object side to a display side along an optical axis; the first lens to the fourth lens respectively comprise an eye side surface facing to the eye side and allowing the imaging light to pass through and a display side surface facing to the display side and allowing the imaging light to pass through;

the first lens element has positive refractive index, the eye side surface of the first lens element is convex, and the display side surface of the first lens element is convex;

the second lens element has positive refractive index, the eye side surface of the second lens element is concave, and the display side surface of the second lens element is convex;

the third lens element with positive refractive index has a convex eye side surface and a convex display side surface;

the fourth lens element with negative refractive index has a concave eye side surface and a concave display side surface;

the eye side surface and the display side surface of the first lens and the second lens are both aspheric surfaces; the third lens and the fourth lens are mutually glued, and both the third lens and the fourth lens are glass lenses;

the eyepiece optical system has only the first lens to the fourth lens with the refractive index.

2. The eyepiece optical system of claim 1, wherein: the first lens and the second lens are both made of plastic materials.

3. The eyepiece optical system of claim 1, further comprising: nd4-nd3 is less than or equal to 0.07, wherein nd3 is the refractive index of the third lens, and nd4 is the refractive index of the fourth lens.

4. The eyepiece optical system of claim 3, further comprising: nd4 is more than or equal to 1.88 and less than or equal to nd3 and less than or equal to 2.00.

5. The eyepiece optical system of claim 1, further comprising: vd3-vd4 is more than or equal to 20, wherein vd3 is the abbe number of the third lens, and vd4 is the abbe number of the fourth lens.

6. The eyepiece optical system of claim 1, further comprising: 1.54 is less than or equal to nd1, wherein nd1 is the refractive index of the first lens.

7. The eyepiece optical system of claim 1, further comprising: and nd2 is not less than 1.64, wherein nd2 is the refractive index of the second lens.

8. The eyepiece optical system of claim 1, further comprising: the TTL is less than or equal to 35.1mm, wherein the TTL is the distance between the eye side surface of the first lens and the optical axis of the display picture.

Technical Field

The invention belongs to the technical field of lenses, and particularly relates to an eyepiece optical system of a handheld camera.

Background

With the continuous progress of scientific technology and the continuous development of society, in recent years, optical imaging lenses are also rapidly developed, and the optical imaging lenses are widely applied to various fields such as smart phones, tablet computers, video conferences, vehicle-mounted monitoring, unmanned aerial vehicle aerial photography, machine vision, security monitoring, cameras and the like, so that the requirements on the optical imaging lenses are higher and higher.

However, the eyepiece lens used for the handheld camera in the current market has many defects, such as small field angle and incapability of being suitable for large field of view; the exit pupil distance is small, usually less than 20mm, and is not suitable for people with glasses; the number of lenses is large, the volume is large, the product performance is poor, and the like, so that the requirements of consumers which are increasing increasingly cannot be met, and the improvement is urgently needed.

Disclosure of Invention

The present invention is directed to an eyepiece optical system for solving the above-mentioned problems.

In order to achieve the purpose, the invention adopts the technical scheme that: an eyepiece optical system is used for enabling imaging light to enter eyes of an observer from a display picture through the eyepiece optical system for imaging, the direction facing the eyes is an eye side, the direction facing the display picture is a display side, and the eyepiece optical system sequentially comprises a first lens to a fourth lens from the eye side to the display side along an optical axis; the first lens to the fourth lens respectively comprise an eye side surface facing to the eye side and allowing the imaging light to pass through and a display side surface facing to the display side and allowing the imaging light to pass through;

the first lens element has positive refractive index, the eye side surface of the first lens element is convex, and the display side surface of the first lens element is convex;

the second lens element has positive refractive index, the eye side surface of the second lens element is concave, and the display side surface of the second lens element is convex;

the third lens element with positive refractive index has a convex eye side surface and a convex display side surface;

the fourth lens element with negative refractive index has a concave eye side surface and a concave display side surface;

the eye side surface and the display side surface of the first lens and the second lens are both aspheric surfaces; the third lens and the fourth lens are mutually glued, and both the third lens and the fourth lens are glass lenses;

the eyepiece optical system has only the first lens to the fourth lens with the refractive index.

Further, the first lens and the second lens are both made of plastic materials.

Further, the eyepiece optical system further satisfies: nd4-nd3 is less than or equal to 0.07, wherein nd3 is the refractive index of the third lens, and nd4 is the refractive index of the fourth lens.

Furthermore, the eyepiece optical system further satisfies: nd4 is more than or equal to 1.88 and less than or equal to nd3 and less than or equal to 2.00.

Further, the eyepiece optical system further satisfies: vd3-vd4 is more than or equal to 20, wherein vd3 is the abbe number of the third lens, and vd4 is the abbe number of the fourth lens.

Further, the eyepiece optical system further satisfies: 1.54 is less than or equal to nd1, wherein nd1 is the refractive index of the first lens.

Further, the eyepiece optical system further satisfies: and nd2 is not less than 1.64, wherein nd2 is the refractive index of the second lens.

Further, the eyepiece optical system further satisfies: the TTL is less than or equal to 35.1mm, wherein the TTL is the distance between the eye side surface of the first lens and the optical axis of the display picture.

The invention has the beneficial technical effects that:

the invention adopts four lenses, and by correspondingly designing each lens, the field angle is large, and the horizontal field angle is larger than 44 degrees; the exit pupil distance is large and can reach 25 mm; the image quality is good, and the imaging quality is excellent; the number of lenses is small, the miniaturization is realized, and the product performance is realized; the sensitivity of the lens is good, and the yield of mass production is good.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic structural diagram according to a first embodiment of the present invention;

FIG. 2 is a graph of MTF at 0.4861-0.6563 μm according to the first embodiment of the present invention;

FIG. 3 is a graph of field curvature and distortion curves of a first embodiment of the present invention;

FIG. 4 is a schematic structural diagram according to a second embodiment of the present invention;

FIG. 5 is a graph of MTF at 0.4861-0.6563 μm according to example two of the present invention;

FIG. 6 is a graph showing curvature of field and distortion in a second embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a third embodiment of the present invention;

FIG. 8 is a graph of MTF at 0.4861-0.6563 μm in case III of the present invention;

FIG. 9 is a graph of field curvature and distortion curves for a third embodiment of the present invention;

FIG. 10 is a schematic structural diagram of a fourth embodiment of the present invention;

FIG. 11 is a graph of MTF at 0.4861-0.6563 μm according to example four of the present invention;

fig. 12 is a graph showing curvature of field and distortion in a fourth embodiment of the present invention.

Detailed Description

To further illustrate the various embodiments, the invention provides the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the embodiments. Those skilled in the art will appreciate still other possible embodiments and advantages of the present invention with reference to these figures. Elements in the figures are not drawn to scale and like reference numerals are generally used to indicate like elements.

The invention will now be further described with reference to the accompanying drawings and detailed description.

The term "a lens element having positive refractive index (or negative refractive index)" means that the paraxial refractive index of the lens element calculated by Gaussian optics theory is positive (or negative). The determination of the surface shape of the lens can be performed by the judgment method of a person skilled in the art, i.e., by the sign of the curvature radius (abbreviated as R value). The R value may be commonly used in optical design software, such as Zemax or CodeV. The R value is also commonly found in lens data sheets (lens data sheets) of optical design software. Regarding the eye side, when the R value is positive, the eye side is judged to be a convex side; when the R value is negative, the eye side surface is judged to be a concave surface. On the contrary, regarding the display side surface, when the R value is positive, the display side surface is judged to be a concave surface; when the R value is negative, the display side is judged to be convex.

The invention discloses an eyepiece optical system, which is used for enabling imaging light to enter eyes of an observer from a display picture through the eyepiece optical system for imaging, wherein the direction facing the eyes is an eye side, the direction facing the display picture is a display side, and the eyepiece optical system sequentially comprises a first lens to a fourth lens from the eye side to the display side along an optical axis; the first lens to the fourth lens respectively comprise an eye side surface facing to the eye side and allowing the imaging light to pass through and a display side surface facing to the display side and allowing the imaging light to pass through.

The first lens element has a positive refractive index, a convex eye side surface and a convex display side surface.

The second lens element has positive refractive index, and has a concave eye side surface and a convex display side surface.

The third lens element has a positive refractive index, a convex object-side surface, and a convex display-side surface.

The fourth lens element with negative refractive index has a concave eye side surface and a concave display side surface.

The eye side surface and the display side surface of the first lens and the second lens are both aspheric surfaces; the third lens and the fourth lens are mutually glued, and both the third lens and the fourth lens are glass lenses.

The first lens is used for reducing the primary amount of aberration (particularly spherical aberration), reducing the high-level amount of the aberration, correcting partial aberration, lightening the burden of a rear group, achieving the effect of using a plurality of spherical lenses by using one aspheric lens, and being simpler in structure and easier to realize the shortening of the total length of a system; the second lens is used for reducing the primary amount of aberration (particularly spherical aberration) and also can reduce the high-grade amount of aberration, corrects the off-axis aberration of the system together with the first lens, achieves the effect of using a plurality of spherical lenses by using one aspheric lens, is simpler in structure and is easier to realize the shortening of the total length of the system; the third lens further corrects aberration and effectively reduces primary aberration; the fourth lens is used by being glued with the third lens to correct the chromatic aberration of the system.

The eyepiece optical system has only the first lens to the fourth lens with the refractive index. The invention adopts four lenses, and by correspondingly designing each lens, the field angle is large, and the horizontal field angle is larger than 44 degrees; the exit pupil distance is large and can reach 25 mm; the image quality is good, and the imaging quality is excellent; the number of lenses is small, the miniaturization is realized, and the product performance is realized; the sensitivity of the lens is good, and the yield of mass production is good.

Preferably, the first lens and the second lens are made of plastic materials, so that the weight is further reduced, the cost is reduced, and the product performance is improved.

Preferably, the eyepiece optical system further satisfies: nd4-nd3 is less than or equal to 0.07, nd3 is the refractive index of the third lens, nd4 is the refractive index of the fourth lens, and the chromatic aberration of the system is further optimized.

More preferably, the eyepiece optical system further satisfies: nd3 is more than or equal to 1.88 and less than or equal to nd4 and less than or equal to 2.00, so that MTF and distortion are further optimized, and imaging quality is improved.

Preferably, the eyepiece optical system further satisfies: and vd3-vd4 is more than or equal to 20, wherein vd3 is the abbe number of the third lens, and vd4 is the abbe number of the fourth lens, so that the chromatic aberration of the system is further optimized.

Preferably, the eyepiece optical system further satisfies: nd1 is not less than 1.54, wherein nd1 is the refractive index of the first lens, so that MTF and distortion are further optimized, and imaging quality is improved.

Preferably, the eyepiece optical system further satisfies: nd2 is not less than 1.64, wherein nd2 is the refractive index of the second lens, so that MTF and distortion are further optimized, and imaging quality is improved.

Preferably, the eyepiece optical system further satisfies: the TTL is less than or equal to 35.1mm, wherein the TTL is the distance between the eye side surface of the first lens and the optical axis of the display picture, the total length of the system is further shortened, and the miniaturization is realized.

The eyepiece optical system of the present invention will be described in detail with specific embodiments, and the following embodiments all use a reverse design (light direction reverse tracking) method to describe in detail the performance of the eyepiece optical system of the present invention, that is, the exit pupil of human eye is used as a diaphragm, the display screen is used as an imaging surface, and light is emitted from the exit pupil of human eye, passes through the eyepiece optical system, and is focused and imaged on the display screen.

Example one

As shown in fig. 1, an eyepiece optical system for imaging an imaging light beam entering an eye of an observer from a display screen 6 through the eyepiece optical system and an eye exit pupil 5 of the observer, the direction toward the eye being an eye side a1, the direction toward the display screen 6 being a display side a2, the eyepiece optical system comprising, in order along an optical axis I, a eye exit pupil 5 (as a diaphragm), a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a display screen 6 (as an imaging surface), from the eye side a1 to the display side a 2; the first lens element 1 to the fourth lens element 4 each include an eye side surface facing the eye side a1 and passing the image light and a display side surface facing the display side a2 and passing the image light.

The first lens element 1 has a positive refractive index, the eye side surface 11 of the first lens element 1 is a convex surface, and the display side surface 12 of the first lens element 1 is a convex surface.

The second lens element 2 has a positive refractive index, the object side surface 21 of the second lens element 2 is a concave surface, and the display side surface 22 of the second lens element 2 is a convex surface.

The third lens element 3 has a positive refractive index, the eye side surface 31 of the third lens element 3 is a convex surface, and the display side surface 32 of the third lens element 3 is a convex surface.

The fourth lens element 4 has a negative refractive index, the eye-side surface 41 of the fourth lens element 4 is concave, and the display-side surface 42 of the fourth lens element 4 is concave.

Both the eye side surfaces 11, 21 and the display side surfaces 12, 22 of the first lens 1 and the second lens 2 are aspherical surfaces.

The third lens 3 and the fourth lens 4 are mutually glued, and the third lens 3 and the fourth lens 4 are both glass spherical lenses.

In this embodiment, the first lens 1 and the second lens 2 are preferably made of plastic materials, but not limited thereto, and in some embodiments, other optical materials such as glass may be used.

The detailed optical data of this embodiment are shown in Table 1-1.

Table 1-1 detailed optical data for example one

In this embodiment, the eye side surfaces 11, 21 and the display side surfaces 12, 22 are defined according to the following aspheric curve formula:

wherein:

r is the distance from a point on the optical surface to the optical axis.

z is the rise of this point in the direction of the optical axis.

c is the curvature of the surface.

K is the conic constant of the surface.

A₄、A₆、A₈、A₁₀、A₁₂、A₁₄Respectively as follows: aspheric coefficients of fourth order, sixth order, eighth order, tenth order, twelfth order, and fourteen order.

For details of parameters of each aspheric surface, please refer to the following table:

please refer to table 5 for the values of the conditional expressions related to this embodiment.

The MTF transfer function curve chart of the specific embodiment is shown in detail in FIG. 2, and it can be seen that the resolution is high, the central MTF value of 30lp/mm spatial frequency is greater than 0.8, the edge MTF value is greater than 0.3, and the image quality is good; as shown in fig. 3 (a) and (B), it can be seen that the field curvature and distortion are small, and the imaging quality is good.

In this embodiment, the focal length f of the eyepiece optical system is 19.53 mm; horizontal field angle FOV is 45.0 °; exit pupil distance 25.0 mm; the distance TTL between the eye-side surface 11 of the first lens 1 and the display screen 6 on the optical axis I is 35.00 mm.

Example two

As shown in fig. 4, the lens elements of this embodiment have the same surface roughness and refractive index as those of the first embodiment, and only the optical parameters such as the curvature radius of the surface of each lens element and the lens thickness are different.

The detailed optical data of this embodiment is shown in Table 2-1.

TABLE 2-1 detailed optical data for example two

For the detailed data of the parameters of each aspheric surface of this embodiment, refer to the following table:

surface of

K

A4

A6

A8

A10

A12

11

20.849

-1.25E-05

4.95E-08

-4.06E-11

-2.48E-13

0.00E+00

12

-0.741

2.24E-05

1.58E-07

-1.04E-10

-4.52E-13

0.00E+00

21

4.462

8.54E-06

1.06E-07

1.68E-10

-3.39E-13

1.68E-15

22

-2.201

-6.90E-06

-5.90E-08

1.64E-10

1.21E-12

-1.36E-15

Please refer to table 5 for the values of the conditional expressions related to this embodiment.

The detailed MTF transfer function graph of the embodiment can be seen in FIG. 5 that the resolution is high, the central MTF value of the 30lp/mm spatial frequency is greater than 0.7, the edge MTF value is greater than 0.3, and the image quality is good; as for the field curvature and distortion diagram, (a) and (B) in fig. 6, it can be seen that the field curvature and distortion are small and the imaging quality is good.

In this embodiment, the focal length f of the eyepiece optical system is 19.68 mm; horizontal field angle FOV is 44.8 °; exit pupil distance 25.0 mm; the distance TTL between the eye-side surface 11 of the first lens 1 and the display screen 6 on the optical axis I is 34.96 mm.

EXAMPLE III

As shown in fig. 7, the lens elements of this embodiment have the same surface roughness and refractive index as those of the first embodiment, and only the optical parameters such as the curvature radius of the surface of each lens element and the lens thickness are different.

The detailed optical data of this embodiment is shown in Table 3-1.

TABLE 3-1 detailed optical data for EXAMPLE III

For the detailed data of the parameters of each aspheric surface of this embodiment, refer to the following table:

surface of

K

A4

A6

A8

A10

A12

11

15.922

-1.44E-05

4.64E-08

-6.75E-12

-1.40E-13

0.00E+00

12

-0.754

2.40E-05

1.63E-07

-1.35E-10

-6.19E-13

0.00E+00

21

4.106

5.67E-06

1.11E-07

1.59E-10

-3.78E-13

1.30E-15

22

-1.243

-1.02E-05

-5.25E-08

1.60E-10

1.22E-12

-8.05E-16

Please refer to table 5 for the values of the conditional expressions related to this embodiment.

The MTF transfer function curve chart of the specific embodiment is shown in detail in FIG. 8, and it can be seen that the resolution is high, the central MTF value of 30lp/mm spatial frequency is greater than 0.8, the edge MTF value is greater than 0.25, and the image quality is good; as for the field curvature and distortion diagram, (a) and (B) of fig. 9, it can be seen that the field curvature and distortion are small and the imaging quality is good.

In this embodiment, the focal length f of the eyepiece optical system is 19.62 mm; horizontal field angle FOV 44.7 °; exit pupil distance 25.0 mm; the distance TTL between the eye-side surface 11 of the first lens 1 and the display screen 6 on the optical axis I is 35.02 mm.

Example four

As shown in fig. 10, the lens elements of this embodiment have the same surface roughness and refractive index as those of the first embodiment, and only the optical parameters such as the curvature radius of the surface of each lens element and the lens thickness are different.

The detailed optical data of this embodiment is shown in Table 4-1.

TABLE 4-1 detailed optical data for example four

For the detailed data of the parameters of each aspheric surface of this embodiment, refer to the following table:

surface of

K

A4

A6

A8

A10

A12

11

15.720

-1.59E-05

3.62E-08

-3.40E-11

-6.06E-14

0.00E+00

12

-0.727

2.37E-05

1.63E-07

-1.62E-10

-6.35E-13

0.00E+00

21

4.230

6.41E-06

1.05E-07

1.59E-10

-3.31E-13

1.46E-15

22

-1.322

-1.02E-05

-5.76E-08

1.52E-10

1.23E-12

-6.33E-16

Please refer to table 5 for the values of the conditional expressions related to this embodiment.

The MTF transfer function curve chart of the specific embodiment is shown in detail in FIG. 11, and it can be seen that the resolution is high, the central MTF value of 30lp/mm spatial frequency is greater than 0.8, the edge MTF value is greater than 0.25, and the image quality is good; as shown in fig. 12 (a) and (B), it can be seen that the field curvature and distortion are small and the imaging quality is good.

In this embodiment, the focal length f of the eyepiece optical system is 19.70 mm; horizontal field angle FOV 44.7 °; exit pupil distance 25.0 mm; the distance TTL between the eye-side surface 11 of the first lens 1 and the display screen 6 on the optical axis I is 35.02 mm.

TABLE 5 values of relevant important parameters for four embodiments of the invention

	First embodiment	Second embodiment	Third embodiment	Fourth embodiment
					nd4-nd3	0.07	0.07	0.07	0.07
vd3-vd4	21.30	22.20	22.80	22.80

While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.