CN111694147A

CN111694147A - Eyepiece lens and eyepiece optical system

Info

Publication number: CN111694147A
Application number: CN202010590942.5A
Authority: CN
Inventors: 王景; 宋强; 马国斌; 汪涛
Original assignee: Shenzhen Lochn Optics Technology Co ltd
Current assignee: Long Optoelectronics Co ltd
Priority date: 2020-06-24
Filing date: 2020-06-24
Publication date: 2020-09-22
Anticipated expiration: 2040-06-24
Also published as: CN111694147B

Abstract

The embodiment of the invention relates to the technical field of optics, in particular to an eyepiece lens and an eyepiece optical system. The eyepiece lens comprises a first lens, a second lens, a third lens and a fourth lens which are arranged in sequence from an image side to an object side in a coaxial mode, wherein the third lens has negative focal power, the other lenses have positive focal power, and the other lenses are concave-convex lenses except the first lens and the second lens.

Description

Eyepiece lens and eyepiece optical system

Technical Field

The embodiment of the invention relates to the technical field of optics, in particular to an eyepiece lens and an eyepiece optical system.

Background

The Augmented Reality (AR) technology is a relatively new technology content that integrates real world information and virtual world information content, and a head-mounted display for Augmented Reality adopts a near-to-eye display technology, so that people can view a virtual image being shown while viewing the surrounding environment, and the virtual image is superimposed on the real world perceived by a user, so that more realistic experience can be created, and the user has a stronger sense of immersion. In recent years, as head-mounted display devices are widely applied to the fields of military affairs, aerospace and the like, the imaging quality of the head-mounted display devices is required to be higher, and the quality of the imaging quality mainly depends on an eyepiece optical system.

In order to improve the optical performance and the imaging quality of an eyepiece optical system, in the prior art, a multi-lens combination is often adopted, and although the eyepiece optical system adopting the multi-lens combination has better optical performance and imaging quality, the eyepiece optical system has larger size, poor portability, complex structure and heavier product, which affects the user experience.

Disclosure of Invention

In view of the foregoing defects in the prior art, an embodiment of the present invention provides an eyepiece lens and an eyepiece optical system, which can be applied to AR display, and the projection lens has a small size and a light weight.

The purpose of the embodiment of the invention is realized by the following technical scheme:

in order to solve the above technical problem, in a first aspect, an embodiment of the present invention provides an eyepiece lens including a first lens, a second lens, a third lens, and a fourth lens, which are coaxially disposed in order from an image side to an object side;

the first lens is a biconvex lens and has positive focal power;

the second lens is a biconvex lens and has positive focal power;

the third lens is a concave-convex lens with negative focal power, the concave surface of the third lens is close to the image side, and the convex surface of the third lens is close to the object side;

the fourth lens is a convex-concave lens with positive focal power, the convex surface of the fourth lens is close to the third lens, and the concave surface of the fourth lens is close to the object side.

In some embodiments, the first lens relative aperture is greater than 1: 3.5, the second lens relative aperture is greater than 1: 1.5, the third lens relative aperture is greater than 1:1, and the fourth lens relative aperture is greater than 1: 1.

In some embodiments, the first lens, the second lens, the third lens and the fourth lens are aspheric lenses.

In some embodiments, the radii of the first lens, the second lens, the third lens, and the fourth lens are each less than or equal to 10 mm.

In some embodiments, the material of the first lens, the second lens, the third lens, and the fourth lens is optical glass or optical resin.

In some embodiments, the effective focal length of the eyepiece lens is 14.3 mm.

In some embodiments, the exit pupil distance of the eyepiece lens is greater than or equal to 20mm and the exit pupil diameter of the eyepiece lens is greater than or equal to 4 mm.

In some embodiments, the diagonal full field angle of the eyepiece lens is greater than or equal to 40 °.

In order to solve the above technical problem, in a second aspect, an embodiment of the present invention provides an eyepiece optical system, including: the eyepiece lens of any one of claims 1-8 and a display chip, wherein the display chip is disposed in an object-side direction of the eyepiece lens and is coaxial with the eyepiece lens, and the display chip size is less than or equal to 0.39 inches.

In some embodiments, the display chip size is 0.39 inches.

Compared with the prior art, the invention has the beneficial effects that: in contrast to the prior art, an embodiment of the present invention provides an eyepiece lens and an eyepiece optical system, where the eyepiece lens includes a first lens, a second lens, a third lens, and a fourth lens that are coaxially disposed in order from an image side to an object side, where the third lens has a negative refractive power, and the other lenses have positive refractive powers, and the other lenses are meniscus lenses, except the first lens and the second lens.

Drawings

One or more embodiments are illustrated by the accompanying figures in the drawings that correspond thereto and are not to be construed as limiting the embodiments, wherein elements/modules and steps having the same reference numerals are represented by like elements/modules and steps, unless otherwise specified, and the drawings are not to scale.

Fig. 1 is a schematic structural diagram of an eyepiece optical system according to an embodiment of the present invention;

FIG. 2 is an MTF plot for the eyepiece optical system shown in FIG. 1;

FIG. 3 is a through focus MTF plot for the eyepiece optical system shown in FIG. 1;

FIG. 4 is a graph of curvature of field versus distortion for the eyepiece optics shown in FIG. 1;

FIG. 5 is an axial aberration diagram of the eyepiece optical system shown in FIG. 1;

FIG. 6 is a dot-column diagram of the eyepiece optical system shown in FIG. 1;

fig. 7 is a schematic structural view of an eyepiece optical system provided by another embodiment of the present invention;

FIG. 8 is an MTF plot for the eyepiece optical system shown in FIG. 7;

FIG. 9 is a through focus MTF plot for the eyepiece optical system shown in FIG. 7;

FIG. 10 is a graph of curvature of field versus distortion for the eyepiece optical system shown in FIG. 7;

fig. 11 is an axial aberration diagram of the eyepiece optical system shown in fig. 7;

fig. 12 is a dot-column diagram of the eyepiece optical system shown in fig. 7.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

Further, the terms "first," "second," "third," and the like, as used herein, do not limit the data and the execution order, but merely distinguish the same items or similar items having substantially the same functions and actions.

In order to facilitate the connection structure definition, the invention takes the light path advancing/light axis emergent direction as the reference to carry out the position definition of the component.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Specifically, the embodiments of the present invention will be further explained below with reference to the drawings.

The first embodiment is as follows:

referring to fig. 1, a schematic structural diagram of an eyepiece optical system according to an embodiment of the present invention is shown, where an eyepiece lens of the eyepiece optical system includes: a first lens E1, a second lens E2, a third lens E3, and a fourth lens E4.

The first lens element E1 is a biconvex lens with positive optical power, and has a convex surface S1 close to the image side and a convex surface S2 close to the object side.

The second lens E2 is a biconvex lens having a positive power with a convex surface S3 close to the image side and the first lens E1 and a convex surface S4 close to the object side.

The third lens E3 is a meniscus lens having a negative power, and has a concave surface S5 close to the image side and a convex surface S6 close to the object side of the second lens E2.

The fourth lens E4 is a convex-concave lens with positive optical power, and has a convex surface S7 close to the image side and a concave surface S8 close to the object side of the third lens E3.

In some embodiments, the relative aperture of the first lens E1 is greater than 1: 3.5, the relative aperture of the second lens E2 is greater than 1: 1.5, the relative aperture of the third lens E3 is greater than 1:1, and the relative aperture of the fourth lens E4 is greater than 1:1, so as to ensure the light transmission amount of the eyepiece optical system.

For example, in the embodiment of the present invention, the relative aperture of the first lens E1 is 1: 3.02, the relative aperture of the second lens E2 is 1: 1.13, the relative aperture of the third lens E3 is 1: 0.52, and the relative aperture of the fourth lens E4 is 1: 0.64.

In some embodiments, each lens of the eyepiece lens can be a separate lens or a double cemented lens.

In the embodiment of the invention, the materials of the first lens E1, the second lens E2, the third lens E3 and the fourth lens E4 are all optical resin, so that the light weight and the portability are strong.

In other embodiments, the material of each lens of the eyepiece lens can be optical glass.

Wherein, the surface parameters of each lens of the eyepiece lens can be set to appropriate values. In the embodiment of the present invention, the surface parameters of each lens of the eyepiece lens are shown in table 1 below.

TABLE 1 surface parameters of lenses in eyepiece lenses

The first lens E1, the second lens E2, the third lens E3 and the fourth lens E4 are all aspheric lenses.

The aspherical cone coefficient value and the aspherical coefficient of each order of each lens may be set to appropriate values. The aspheric conic coefficient values and the aspheric coefficients of each order of the lenses according to the embodiments of the present invention are shown in table 2 below, where K is the aspheric conic coefficient, and a1, a2, a3, a4, and a5 correspond to aspheric coefficients of 2, 4, 6, 8, and 10 orders, respectively.

In other embodiments, the first lens E1, the second lens E2, the third lens E3, and the fourth lens E4 may be spherical mirrors.

TABLE 2 aspherical Cone coefficient values and aspherical coefficients of respective orders for respective lenses in eyepiece lens

Flour mark

K

a1

a2

a3

a4

a5

S1

-14.03

0

-3.285210E-05

-1.730702E-06

1.973515E-08

0

S2

-26.62

0

-4.182380E-04

8.290133E-07

2.127755E-08

0

S3

-0.30

0

-6.132080E-05

2.432163E-08

-2.299657E-08

0

S4

15.14

0

2.032052E-04

-4.858835E-06

2.182754E-08

0

S5

-2.38

0

6.327115E-04

-6.182617E-06

3.368128E-08

0

S6

-3.97

0

6.839881E-04

-7.362250E-06

4.242462E-08

0

S7

-4.41

0

5.450853E-04

-1.960775E-06

-2.712114E-07

0

S8

16.76

0

1.555421E-03

-3.511109E-05

2.129971E-07

0

Based on the above structure, the optical performance parameters of the eyepiece lens are shown in the following table 3

TABLE 3 optical Performance parameters of eyepiece lenses

Angle of view	Effective focal length	Distance of exit pupil	Diameter of exit pupil	Eye movement range-eye box
					40°	14.3mm	22mm	≥4mm	8×8mm²

As can be seen from Table 3, the effective focal length of the eyepiece lens is 14.3mm, the exit pupil distance is 22mm, that is, the effective focal length and the exit pupil distance of the eyepiece lens are small, the distance between human eyes and an image source can be effectively shortened, so that the size of equipment using the eyepiece lens can be reduced, the miniaturization design is realized, the diagonal full field angle of the eyepiece lens is 40 degrees, the exit pupil diameter is greater than or equal to 4mm, and the eye movement range is 8 × 8mm²The observation range of human eyes can be reached, so that the resolving power of the human eyes can be fully exerted.

In some other embodiments, the eyepiece optical system further comprises a display chip P1, the display chip P1 is disposed in the object-side direction of the eyepiece lens and is coaxial with the eyepiece lens, and the display chip P1 used can be less than or equal to 0.39 inches for providing an image source of the eyepiece optical system.

The display chip P1 can be Lcos, Micro-LED or DLP. When the display chip P1 uses a chip that is not self-luminous, such as Lcos or DLP, the eyepiece lens has a visible light band, so the eyepiece optical system needs to be added with an illumination portion, and the illumination portion can use an LED or laser light source.

In this embodiment, the display chip P1 is an OLED with a size of 0.39 inch and a resolution of 1920 × 1080P, and the chip pixel size is 4.5 μm, and the ultimate resolution is 111 Ip/mm. The use of the 0.39 inch display chip can eliminate the granulation phenomenon, obtain a larger diagonal full-field angle and smaller distortion, thereby fully exerting the optical performance of the eyepiece optical system.

The imaging quality of the eyepiece optical system is examined below.

Fig. 2 is an MTF (modulation transfer function) graph of the eyepiece optical system shown in fig. 1, wherein the MTF can comprehensively reflect the imaging quality of the optical system, and the smoother the curve shape and the higher the relative X-axis height prove that the imaging quality of the system is better. As can be seen from FIG. 2, the MTF curve is smoother, and the MTF of the eyepiece optical system at a spatial frequency of 100lp/mm is > 0.2, which is much higher than the limit resolution of 0.5 times. For the eyepiece optical system, the limit resolution of which the resolution is greater than 0.5 times can be regarded as that the eyepiece optical system has a good imaging effect, that is, the aberration of the eyepiece optical system in the embodiment is well corrected, and the imaging quality is good.

FIG. 3 is a defocusing MTF graph of the eyepiece optical system shown in FIG. 1, and it can be seen from FIG. 3 that the MTF of the eyepiece optical system at a spatial frequency of 55lp/mm is greater than or equal to 0.2 and supports a focal depth of + -0.3 mm, that is, the eyepiece optical system in this embodiment has a good imaging effect.

Fig. 4 is a graph of field curvature and distortion of the eyepiece optical system shown in fig. 1, where the left side is the field curvature curve and the right side is the distortion curve. The field curvature is an aberration of a curved image formed by an object plane, and is characterized by tangential field curvature and sagittal field curvature, and the axial ray imaging quality of the optical system is seriously influenced by the two kinds of overlarge field curvature. As can be seen from fig. 4, the curvature of field is within ± 0.08mm, that is, the curvature of field of the eyepiece optical system is corrected to a small range. Meanwhile, when the distortion of the system is less than 4%, the distortion is hard to be perceived by human eyes, and as can be seen from fig. 4, the maximum distortion of the eyepiece optical system is less than 3%, that is, the eyepiece optical system in the embodiment has small curvature of field and distortion, and a good imaging effect.

Fig. 5 is an axial aberration diagram of the eyepiece optical system shown in fig. 1, and as can be seen from fig. 5, the axial aberration of the eyepiece optical system is small.

Fig. 6 is a point diagram of the eyepiece optical system shown in fig. 1, where the point diagram reflects the imaging geometry of the optical system, and in image quality evaluation, the density of the available point diagram more intuitively reflects and measures the quality of the imaging quality of the system, and the smaller the RMS radius of the point diagram, the smaller the aberration is, the better the imaging quality of the system is. As shown in the figure, the RMS radius is controlled within 4.5 μm, namely the size of each visual field spot of the eyepiece system is smaller than one pixel, so that the visual effect is achieved, the spot of each visual field is small, the aberration correction is good, and the imaging quality of the eyepiece optical system is good.

According to the data, the eyepiece optical system is simple in structure, small in size, good in aberration correction and excellent in imaging quality.

Example two:

fig. 7 is a schematic structural diagram of an eyepiece optical system according to another embodiment of the present invention, wherein an eyepiece lens of the eyepiece optical system includes: a first lens E5, a second lens E6, a third lens E7, and a fourth lens E8.

The first lens element E5 is a biconvex lens with positive optical power, and has a convex surface S9 close to the image side and a convex surface S10 close to the object side.

The second lens E6 is a biconvex lens having a positive power with a convex surface S11 close to the image side and the first lens E5 and a convex surface S12 close to the object side.

The third lens E7 is a meniscus lens having a negative power, and has a concave surface S13 close to the image side and a convex surface S14 close to the object side of the second lens E7.

The fourth lens E8 is a convex-concave lens with positive optical power, and has a convex surface S15 close to the image side and a concave surface S16 close to the object side of the third lens E3.

In the embodiment of the invention, the relative aperture of the first lens E1 is 1: 3.0, the relative aperture of the second lens E2 is 1: 1.13, the relative aperture of the third lens E3 is 1: 0.52, and the relative aperture of the fourth lens E4 is 1: 0.63.

In the embodiment of the invention, the materials of the first lens E5, the second lens E6, the third lens E7 and the fourth lens E8 are all optical resin, so that the light weight and the portability are strong.

In the embodiment of the present invention, the surface parameters of each lens of the eyepiece lens are shown in table 4 below.

TABLE 4 surface parameters of the lenses in the eyepiece lenses

The first lens element E1, the second lens element E2, the third lens element E3 and the fourth lens element E4 are aspheric lens elements, the aspheric conic coefficient values and aspheric coefficients of each order are shown in table 5 below, K is an aspheric conic coefficient, and a1, a2, a3, a4 and a5 correspond to aspheric coefficients of 2, 4, 6, 8 and 10 orders, respectively.

TABLE 5 aspherical Cone coefficient values and aspherical coefficients of respective orders for respective lenses in eyepiece lens

Flour mark

K

a1

a2

a3

a4

a5

S9

-14.22

0

-3.299607E-05

-1.726575E-06

1.978966E-08

0

S10

-25.27

0

-4.179282E-04

8.242829E-07

2.120817E-08

0

S11

-0.31

0

-6.029895E-05

2.154466E-08

-2.301311E-08

0

S12

14.78

0

2.034771E-04

-4.854566E-06

2.197225E-08

0

S13

-2.38

0

6.327752E-04

-6.183659E-06

3.357352E-08

0

S14

-3.99

0

6.845644E-04

-7.361062E-06

4.241132E-08

0

S15

-4.42

0

5.457052E-04

-1.953133E-06

-2.708517E-07

0

S16

16.79

0

1.555382E-03

-3.513574E-05

2.122163E-07

0

Based on the above structure, the optical performance parameters of the eyepiece lens are shown in table 6 below

TABLE 6 optical Performance parameters of eyepiece systems

As can be seen from Table 6, the effective focal length of the eyepiece lens is 14.3mm, the exit pupil distance is 22mm, that is, the effective focal length and the exit pupil distance of the eyepiece lens are small, the distance between an eye and an image source can be effectively shortened, so that the size of equipment using the eyepiece system can be reduced, the miniaturization design is realized, the diagonal full field angle of the eyepiece lens is 40 degrees, the exit pupil diameter is greater than or equal to 4mm, and the eye movement range is 8 × 8mm²The observation range of human eyes can be reached, thereby fully exerting the resolving power of human eyes.

In this embodiment, the eyepiece optical system further includes a display chip P2, and the display chip P2 is disposed in the object-side direction of the eyepiece lens and is coaxial with the eyepiece lens, and is configured to provide an image source of the eyepiece optical system.

In this embodiment, the display chip P2 is an OLED with dimensions of 0.39 inch, resolution of 1920 × 1080P, and is flexible, and the chip pixel size is 4.5 μm, and the limit resolution is 111 Ip/mm. The use of a 0.39 inch display chip eliminates the phenomenon of graining, provides a larger diagonal full field of view and less distortion, and the flexible display chip can be bent at a certain angle, thereby having the capability of correcting the curvature of field of the system and fully exerting the optical performance of the eyepiece optical system.

The performance of the eyepiece system is examined below.

Fig. 8 is an MTF graph of the eyepiece optical system shown in fig. 7, and it can be seen from fig. 8 that the MTF curve is relatively smooth, and the MTF of the eyepiece optical system at a spatial frequency of 100lp/mm is greater than 0.2 and much higher than 0.5 times of the limit resolution, that is, the aberration of the eyepiece optical system in this embodiment is well corrected, and the imaging quality is excellent.

FIG. 9 is a defocusing MTF graph of the eyepiece optical system shown in FIG. 7, and it can be seen from FIG. 9 that the MTF of the eyepiece optical system at a spatial frequency of 55lp/mm is greater than or equal to 0.2 and supports a focal depth of + -0.3 mm, that is, the eyepiece optical system in this embodiment has a good imaging effect.

Fig. 10 is a graph of curvature of field and distortion of the eyepiece optical system shown in fig. 7, and it can be seen from fig. 10 that the curvature of field is within ± 0.01mm, so that it can be seen that the curvature of field of the eyepiece optical system is corrected to an extremely small range when the bendable display chip P2 is used. Meanwhile, fig. 10 also shows that the maximum distortion of the eyepiece system is less than 3%, that is, the eyepiece optical system in the embodiment has small curvature of field and distortion, and the imaging effect is good.

Fig. 11 is an axial aberration diagram of the eyepiece optical system shown in fig. 7, and as can be seen from fig. 11, the axial aberration of the eyepiece optical system is small.

Fig. 12 is a point diagram of the eyepiece system shown in fig. 7, and as shown in fig. 12, the RMS radius is controlled within 4.5 μm, that is, the size of each field spot of the eyepiece system is smaller than one pixel, so that it is visible, the spot of each field is small, the aberration correction is good, and the imaging quality of the eyepiece optical system is good.

An embodiment of the present invention provides an eyepiece lens and an eyepiece optical system, where the eyepiece lens includes a first lens, a second lens, a third lens, and a fourth lens that are coaxially disposed in order from an image side to an object side, where the third lens has a negative refractive power, and the other lenses have positive refractive powers, and the other lenses are meniscus lenses except the first lens and the second lens.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; within the idea of the invention, also technical features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An eyepiece lens includes a first lens, a second lens, a third lens, and a fourth lens arranged in order from an image side to an object side on a common optical axis;

the first lens is a biconvex lens and has positive focal power;

the second lens is a biconvex lens and has positive focal power;

2. An eyepiece lens as recited in claim 1, wherein the first lens relative aperture is greater than 1: 3.5, the relative aperture of the second lens is larger than 1: 1.5, the relative aperture of the third lens is larger than 1:1, and the relative aperture of the fourth lens is larger than 1: 1.

3. an eyepiece lens as recited in claim 2 wherein said first lens, said second lens, said third lens, and said fourth lens are aspheric lenses.

4. An eyepiece lens as recited in claim 3 wherein the radii of the first lens, the second lens, the third lens, and the fourth lens are each less than or equal to 10 mm.

5. An eyepiece lens as recited in any of claims 1-4 wherein the material of said first lens, said second lens, said third lens, said fourth lens is optical glass or optical resin.

6. An eyepiece lens as recited in any of claims 1-4, wherein the effective focal length of the eyepiece lens is 14.3 mm.

7. An eyepiece lens as recited in any one of claims 1 to 4 wherein the exit pupil distance of the eyepiece lens is greater than or equal to 20mm and the exit pupil diameter of the eyepiece lens is greater than or equal to 4 mm.

8. An eyepiece lens as recited in any of claims 1-4, wherein the full diagonal field angle of the eyepiece lens is greater than or equal to 40 °.

9. An eyepiece optical system comprising the eyepiece lens of any one of claims 1 to 8 and a display chip, wherein the display chip is disposed in an object-side direction of the eyepiece lens and is coaxial with the eyepiece lens, and wherein the display chip size is less than or equal to 0.39 inches.

10. The eyepiece optical system of claim 9, wherein the display chip size is 0.39 inches.