CN115390218A

CN115390218A - Optical projection lens and corresponding AR projection device

Info

Publication number: CN115390218A
Application number: CN202110566633.9A
Authority: CN
Inventors: 刘冰玉; 杜佳玮; 陈军
Original assignee: Ningbo Sunny Opotech Co Ltd
Current assignee: Ningbo Sunny Opotech Co Ltd
Priority date: 2021-05-24
Filing date: 2021-05-24
Publication date: 2022-11-25

Abstract

The invention relates to an optical projection lens, which comprises the following components in sequence from a projection side to a chip side: a first lens, a second lens, a third lens, and a fourth lens; the first lens has positive focal power, the second lens has negative focal power, the third lens has positive focal power, and the fourth lens has negative focal power; wherein a focal length f of the optical projection lens, a focal length f1 of the first lens, a focal length f2 of the second lens, a focal length f3 of the third lens, and a focal length f4 of the fourth lens satisfy the following relations: 0.8-woven fabric f3/f <1.3; | f1+ f2+ f3+ f4|/f >0.15;0.5< (f 1+ f2+ f 3)/f <1.5. The invention also provides corresponding AR equipment. The optical projection lens can improve projection brightness and projection uniformity.

Description

Optical projection lens and corresponding AR projection device

Technical Field

The invention relates to the technical field of optics, in particular to an optical projection lens and corresponding AR projection equipment.

Background

Augmented Reality (AR) technology can fuse virtual information (objects, pictures, videos, sounds and the like) in a real environment, enrich the real world and construct a more comprehensive and better world. With the development of AR technology, the related fields are continuously expanded, and the AR has wide application prospects in various fields such as entertainment, education, medical treatment and the like. AR projection devices (otherwise known as AR display devices, AR devices) typically include an optical system and a display system. The optical system may include an image source device that generates an image and projects the image through an optical projection lens into display optics that reflect the image into the eye.

The optical projection lens plays an important role in information conversion and transmission, and needs to convert a near image or text content generated by an image source device (usually a chip) into far-distance optical information, and then reflect the information to human eyes through an optical reflection or waveguide element.

The optical projection lens used on AR equipment at present has great difference in design process and final structure due to difference of image source devices, and the common image source devices of the AR equipment mainly comprise a reflective passive light-emitting DLP chip and an LCOS chip; and self-luminous micro leds and OLED chips. The former needs to add an illumination device besides an optical projection lens in the information transmission process due to non-self-luminescence, has a more complicated structure and larger size, is not suitable for mass production, and is difficult to be applied to a miniaturized AR device. Compared with the micro led and the OLED, the overall size of the AR device (e.g., AR light machine) can be greatly reduced due to the advantage of self-luminescence; and because the secondary breakage between illumination and chips does not exist, the integral light effect of the AR light machine is higher, and the image quality contrast is better. And, because the AR device based on the self-light emitting chip has few types of elements and many linear arrangements, it has better mass productivity.

However, in the prior art, the AR device based on the self-light emitting chip still needs to be improved in terms of projection brightness, projection uniformity and the like. Therefore, there is a need for an optical projection lens and corresponding AR device solution with better projection brightness and projection uniformity that is compatible with self-light emitting chips.

Disclosure of Invention

The present invention is directed to overcoming the deficiencies of the prior art and providing an optical projection lens and corresponding AR device solution with better projection brightness and projection uniformity for adaptation to a self-luminous chip.

In order to solve the above technical problem, the present invention provides an optical projection lens, which includes: sequentially arranged from the projection side to the chip side: a first lens, a second lens, a third lens, and a fourth lens; the first lens has positive focal power, the second lens has negative focal power, the third lens has positive focal power, and the fourth lens has negative focal power; wherein a focal length f of the optical projection lens, a focal length f1 of the first lens, a focal length f2 of the second lens, a focal length f3 of the third lens, and a focal length f4 of the fourth lens satisfy the following relations: 0.8< -f3/f <1.3; f1+ f2+ f3+ f 4/f >0.15;0.5< (f 1+ f2+ f 3)/f <1.5.

Wherein a thickness CT1 of the first lens element on the optical axis, a distance AT3 between the third lens element and the fourth lens element on the optical axis, and a focal length f of the optical projection lens satisfy the following relations: 0.25< (CT 2+ AT 3)/f <0.45.

The surface of the projection side of the third lens is a convex surface, and the surface of the chip side of the third lens is a concave surface.

The surface of the projection side of the first lens is a convex surface, and the surface of the chip side of the first lens is a concave surface; the surface of the projection side of the second lens is a convex surface, and the surface of the chip side of the second lens is a concave surface; and the surfaces of the two sides of the fourth lens are both concave surfaces.

Wherein, the distance ST between the diaphragm and the first lens on the optical axis satisfies the following relation: ST is more than or equal to 1mm.

Wherein the curvature radius R21 of the projection side of the second lens and the curvature radius R22 of the chip side of the second lens satisfy the following relation: 1.5 sP R21/R22<2.5.

Wherein a curvature radius R31 of the projection side of the third lens and a curvature radius R42 of the chip side of the fourth lens satisfy the following relational expression: 0.15 sP R31/R42<1.5.

Wherein, the thickness CT1 of the first lens element on the optical axis and the thickness CT3 of the third lens element on the optical axis satisfy the following relations: CT1/CT3<1.1.

Wherein optical surfaces of the first lens, the second lens, the third lens and the fourth lens are aspheric.

Any two adjacent lenses of the first lens, the second lens, the third lens and the fourth lens have a non-zero distance on an optical axis.

According to another aspect of the present application, there is also provided an AR projection apparatus, including: an optical projection lens as described in any of the preceding paragraphs; a self-light emitting chip for projecting a light information image to the optical projection lens; and a waveguide device including a coupling-in region disposed at a front end of the first lens, the front end being an output end of the optical projection lens.

Wherein the waveguide device is a waveguide sheet having the coupling-in region and the coupling-out region.

Wherein the waveguide plate has a first surface on which a microstructure constituting the coupling-in region is fabricated and a second surface disposed between the first surface and the first lens.

Wherein, the diaphragm of the optical projection lens is arranged on the first surface.

The optical projection lens further comprises a lens barrel, and the first lens, the second lens, the third lens and the fourth lens are mounted on the lens barrel and are assembled into a lens group through the lens barrel; the second surface is a plane and is supported against the end surface of the lens barrel.

Compared with the prior art, the application has at least one of the following technical effects:

1. the optical projection lens can improve projection brightness and projection uniformity.

2. In some embodiments of the present application, the third lens provides a primary optical power and is configured with the first lens having a positive optical power and the second and fourth lenses having a weaker optical power, which can receive the beam angle of the light emitted from the image source device to a greater degree and reduce the light-emitting angle of the image source device corresponding to the central light of the lens to increase the light flux of the light passing through the projection system.

3. In some embodiments of the present application, the second lens may act as a beam expander throughout the optical system to ensure that the incoming beam fills the coupling-in area of the entire waveguide sheet without vignetting.

4. In some embodiments of the present application, the thickness of the second lens and the interval of the fourth lens of the optical projection lens can be used to adjust and improve the temperature drift performance of the optical system, and the lenses with positive and negative focal powers can be guaranteed to compensate each other in the temperature change process within this range, thereby playing a role in keeping good image quality in high and low temperature environments.

5. In some embodiments of the present application, the diaphragm may be disposed at the coupling-in region of the waveguide sheet. The design can reduce the influence of vignetting of the coupling-in area of the waveguide plate on the image information to the maximum extent, thereby improving the contrast, brightness and uniformity of the picture.

Drawings

Fig. 1, 2, 3, 4 and 5 sequentially show an optical projection lens structure, a distortion curve, a relative illuminance curve, an astigmatism curve and a chromatic aberration curve of embodiment 1 of the present application;

fig. 6, 7, 8, 9 and 10 sequentially show an optical projection lens structure, a distortion curve, a relative illuminance curve, an astigmatism curve and a chromatic aberration curve of embodiment 2 of the present application;

fig. 11, 12, 13, 14 and 15 show an optical projection lens structure, a distortion curve, a relative illuminance curve, an astigmatism curve and a chromatic aberration curve in this application in this order of embodiment 3;

fig. 16, 17, 18, 19 and 20 sequentially show an optical projection lens structure, a distortion curve, a relative illuminance curve, an astigmatism curve and a chromatic aberration curve of embodiment 4 of the present application;

fig. 21, 22, 23, 24 and 25 sequentially show an optical projection lens structure, a distortion curve, a relative illuminance curve, an astigmatism curve and a chromatic aberration curve of embodiment 5 of the present application;

fig. 26, 27, 28, 29 and 30 sequentially show an optical projection lens structure, a distortion curve, a relative illuminance curve, an astigmatism curve and a chromatic aberration curve of embodiment 6 of the present application;

fig. 31 shows a schematic view from above of a waveguide plate of an AR device according to an embodiment of the present application.

Detailed Description

For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of exemplary embodiments of the present application and does not limit the scope of the present application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.

It should be noted that the expressions first, second, etc. in this specification are used only to distinguish one feature from another feature, and do not indicate any limitation on the features. Thus, a first body discussed below may also be referred to as a second body without departing from the teachings of the present application.

In the drawings, the thickness, size, and shape of an object have been slightly exaggerated for convenience of explanation. The figures are purely diagrammatic and not drawn to scale.

It will be further understood that the terms "comprises," "comprising," "includes," "including," "has," "including," and/or "including," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Moreover, when a statement such as "at least one of" appears after a list of listed features, the entirety of the listed features is modified rather than modifying individual elements in the list. Furthermore, when describing embodiments of the present application, the use of "may" mean "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to examples or illustrations.

As used herein, the terms "substantially," "about," and the like are used as terms of table approximation and not as terms of table degree, and are intended to account for inherent deviations in measured or calculated values that will be recognized by those of ordinary skill in the art.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

It should be noted that, in the present application, the embodiments and features of the embodiments may be combined with each other without conflict.

The application provides an optical projection lens designed based on a self-luminous chip, and the optical projection lens comprises a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged from an optical information projection end to an image source device end. The lens with diopter is four non-adhesive aspheric lenses, so-called non-adhesive lens, that is, a space is formed between any two adjacent first lens, second lens, third lens and fourth lens of the optical projection lens, and the design can effectively avoid the problem caused by adhering the lenses. Specifically, when the lenses are bonded, a bonding surface is formed between adjacent lenses, and the surface shape of the bonding surface is often difficult to determine (for example, the bonding surface may be deformed by heating), so that additional errors are introduced; the cemented lens may also suffer from debonding problems due to heat; moreover, the difficulty of lens coating is increased by adopting the gluing technology to assemble the lens group. In the present application, any two adjacent lenses of the first lens, the second lens, the third lens and the fourth lens of the optical projection lens have a distance therebetween, that is, the non-cemented lens is used to assemble the lens assembly, so that the above-mentioned problems can be effectively avoided.

In a series of embodiments of the present application, a first lens having positive optical power (i.e., having positive refractive power) in the optical projection lens has a convex surface on a side thereof close to the optical information projection end (which may be simply referred to as a projection side) and a concave surface on a side thereof close to the image source device (in the present embodiment, the image source device is generally implemented by a self-luminous image chip, and thus the side close to the image source device may be simply referred to as a chip side). In the present application, the optical power characterizes the refractive power of the optical system with respect to the incident parallel light beam, and has a unit of diopter (diopter). The first lens has the function of adjusting the light direction in the system and is suitable for projecting light to the coupling-in area of the waveguide piece. Wherein the coupling-in region of the waveguide plate is adapted to be arranged at the exit end of the first lens. The third lens provides a primary power and is configured with a first lens having a positive power, and second and fourth lenses having a weaker power. The design can be used for receiving the beam angle of light emitted by an image source device (such as a self-luminous image chip) to a greater extent, and reducing the light-emitting angle of the image source device corresponding to the light in the center of the lens so as to increase the light flux of the light passing through the projection system.

Further, in some embodiments of the present application, the optical projection lens has a second lens with positive optical power, a convex surface on a projection side thereof, and a concave surface on a chip side thereof. The second lens may act as a beam expander throughout the optical system to ensure that the incoming beam fills the coupling-in region of the entire waveguide sheet without vignetting. The thickness of the second lens and the interval of the fourth lens of the optical projection lens can be used for adjusting and improving the temperature drift performance of the optical system, and the lenses with positive and negative focal powers of the lens can be mutually compensated in the temperature change process within the range, so that the effect of keeping good image quality under high and low temperature environments is achieved.

Further, in some embodiments of the present application, the optical projection lens has a third lens with positive optical power, a surface on a projection side thereof is convex, and a surface on a chip side thereof is concave. The third lens is matched with the first lens with positive diopter and the second lens with negative diopter to play a role of beam expansion and is matched with the fourth lens with negative diopter, so that more effective light rays are provided for a large-size coupling-in area of the waveguide sheet, and the luminous flux and projection brightness of projection light information at the emergent end are increased. Fig. 31 shows a schematic view from above of a waveguide plate of an AR device according to an embodiment of the present application. Referring to fig. 31, the waveguide plate generally includes an incoupling region 110 and an outcoupling region 120, and light rays projected by the optical projection lens are coupled into the incoupling region 110 of the waveguide plate, are laterally transmitted in the waveguide plate by one diffraction or multiple reflections, and then enter the outcoupling region 120, and are received by human eyes after being outcoupled by the outcoupling region 120. Generally, the area of the out-coupling region 120 is larger than that of the in-coupling region 110 in a top view. The incoupling region 110 is typically a region of a particular optical function formed after microstructural processing of the surface of the waveguide sheet. The light projected by the optical projection lens can be transmitted to the coupling-out region through the waveguide sheet and received by human eyes only when entering the coupling-in region 110.

Further, in some embodiments of the present application, the optical projection lens has a fourth lens with negative refractive power, both surfaces of the fourth lens are concave surfaces, and the fourth lens is matched with the third lens with positive refractive power, so that aberrations (including other aberrations except chromatic aberration, such as spherical aberration and coma aberration) except chromatic aberration can be better balanced under a certain curvature radius ratio, thereby improving the optical performance of the optical projection lens. Meanwhile, the fourth lens is matched with the third lens, the application range of the optical projection lens can be expanded, and the optical performance requirements of image source devices with different sizes are met.

Further, in some embodiments of the present application, the stop of the optical system of the AR device may be placed outside the optical projection lens. Specifically, the first lens, the second lens, the third lens and the fourth lens of the optical projection lens may be mounted in a lens barrel, and the stop of the optical system of the optical projection lens may be disposed outside the lens barrel. In particular, the diaphragm may be arranged in the coupling-in region of the waveguide plate. The design can reduce the influence of vignetting of the coupling-in area of the waveguide plate on the image information to the maximum extent, thereby improving the contrast, brightness and uniformity of the picture. In this embodiment, the AR device may include a waveguide sheet, an optical projection lens, and a self-light emitting chip. The light rays which form image information and are output by the self-luminous chip are projected to the coupling-in area of the waveguide sheet through the optical projection lens, then are transversely transmitted to the coupling-out area of the waveguide sheet through the waveguide sheet based on a diffraction or multi-reflection mechanism, and finally are received by human eyes. In this embodiment, two surfaces of the waveguide sheet may be a flat surface and a functional surface with a microstructure (the functional surface is sometimes referred to as a first surface, and the flat surface serving as a protective cover is referred to as a second surface). The plane can be supported against the end face of the lens barrel of the optical projection lens, and the functional surface is positioned on the surface deviating from the lens barrel. I.e. the second surface is located between the first surface and the first lens. In this embodiment, the diaphragm may be fabricated on a functional surface of the waveguide sheet, that is, the diaphragm is fabricated on a surface of the waveguide sheet that is away from the lens barrel. In this embodiment, the coupling-in region of the first surface is formed by a specific microstructure fabricated on the surface of the waveguide plate, and the region outside the microstructure cannot couple in the projected light, so that the boundary of the coupling-in region formed by the microstructure can be regarded as the light-passing hole of the diaphragm. In this embodiment, since the optical projection lens itself does not need to be additionally provided with the diaphragm, for example, the end surface of the lens barrel of the optical projection lens may not be provided with the diaphragm, more light rays may be coupled into the waveguide sheet, thereby improving the brightness of the projected image.

Further, in some embodiments of the present application, to achieve the above beneficial effects, a plurality of parameters of the optical elements of the optical projection lens satisfy the following relationship: assuming that a focal length of the optical projection lens is f, wherein the focal length of the first lens element is f1, the focal length of the second lens element is f2, the focal length of the third lens element is f3, the focal length of the fourth lens element is f4, a thickness of the first lens element along the optical axis is CT1, a thickness of the second lens element along the optical axis is CT2, an axial distance between the stop and the first lens element along the optical axis is ST, and an axial distance between the third lens element and the fourth lens element along the optical axis is AT3, the following conditions are satisfied: 0.8< -f3/f <1.3, | f1+ f2+ f3+ f4|/f >0.15, ST ≥ 1mm, 0.5< (f 1+ f2+ f 3)/f <1.5. More preferably, in some preferred embodiments, the following conditions may be further satisfied: 0.25< (CT 2+ AT 3)/f <0.45.

Further, in some embodiments, it is assumed that the curvature radius of the surface on the exit side of the second lens is R21, the curvature radius of the chip-side surface is R22, the curvature radius of the surface on the exit side of the third lens is R31, and the curvature radius of the surface on the chip side of the fourth lens is R42. It satisfies the following conditions: 1.5-sR21/R22 <2.5, 0.15-sR31/R42 <1.5. Further, in some preferred embodiments, the following conditions may be further satisfied: CT1/CT3<1.1.

In the following, specific embodiments are provided and will be described in detail with reference to the drawings.

Wherein, the aspheric curve equation of each lens is expressed as follows:

wherein:

x: the distance between the point on the aspheric surface and the optical axis is Y, and the distance is relative to the tangent plane of the intersection point on the aspheric surface optical axis;

y: the perpendicular distance between a point on the aspheric curve and the optical axis;

r: a radius of curvature;

k: the cone coefficient;

ai: the ith order aspheric coefficients.

< example 1>

In the optical projection lens of embodiment 1, the focal length of the optical projection lens is f, the aperture value (f-number) of the optical projection lens is Fno, and the maximum viewing angle of the optical projection lens is FOV, which are as follows: f =5.78mm; fno =1.66; and FOV =30 degrees.

Example 1 the conditional expressions of the optical projection lens have specific numerical values as follows:

f3/f＝0.89

|f1+f2+f3+f4|/f＝0.66

(f1+f2+f3)/f＝0.59

(CT2+AT3)/f＝0.36

R21/R22＝1.75

R31/R42＝1.02

CT1/CT3＝1.03

ST＝1mm

more specific optical parameters of each optical element of the optical projection lens and the corresponding AR apparatus (which includes the waveguide and the aperture) of embodiment 1 can be referred to the following table 1 and table 2. In the table, the surface 1 of the diaphragm and the aperture represents the surface of the waveguide sheet on which the diaphragm is provided, and the surface 2 represents the surface of the waveguide sheet serving as a protective Cover (Cover Glass, abbreviated as CG). In the AR apparatus, the image source device generally has an image source device protective Cover (here, cover Glass, abbreviated as CG) and a self-luminous chip. In the table, the surfaces 11 and 12 represent two surfaces of the protective cover (i.e., the glass cover plate) of the image source device, respectively, and the surface 13 represents the light-emitting surface of the self-light-emitting chip. In the other tables below, the meaning of each surface is consistent with that in table 1, and is not repeated. In addition, the practical meaning of the column of thickness in table 1 is the distance on the optical axis from the current surface to the next surface. For example, the thickness corresponding to surface 1 refers to the distance between surface 1 and surface 2 on the optical axis. Wherein the optical axis refers to the optical axis of the optical projection lens. In the other tables below, the actual meaning of the column of thickness is consistent with that in table 1, and will not be described again.

TABLE 1

TABLE 2

Table 1 shows the detailed structural data of embodiment 1 of fig. 1, wherein the units of the radius of curvature, the thickness and the focal length are mm, and the surfaces 1-13 sequentially represent the surfaces from the object side to the image side. Table 2 shows the aspheric data of example 1, where K represents the cone coefficients in the aspheric curve equation and A4-A16 represent the aspheric coefficients of order 4-16 for each surface. Further, fig. 1, 2, 3, 4 and 5 sequentially show the optical projection lens structure, a distortion curve, a relative illuminance curve, an astigmatism curve and a chromatic aberration curve of embodiment 1 of the present application. In fig. 1, E1 denotes a waveguide sheet, E2 denotes a first lens, E3 denotes a second lens, E4 denotes a third lens, E5 denotes a fourth lens, E6 denotes a protective cover for an image source device, and E7 denotes a light emitting surface of a self-light emitting chip. Further, STO represents surface 1, and S2-13 represent surfaces 2-13 in Table 1, respectively. Hereinafter, fig. 6, 7, 8, 9 and 10 sequentially show the optical projection lens structure, distortion curve, relative illuminance curve, astigmatism curve and chromatic aberration curve of embodiment 2 of the present application. The meaning of the reference numerals in fig. 6 can refer to fig. 1 corresponding to embodiment 1, and is not repeated. Further, fig. 11, 12, 13, 14 and 15 sequentially show the optical projection lens structure, distortion curve, relative illuminance curve, astigmatism curve and chromatic aberration curve of embodiment 3 of the present application; fig. 16, 17, 18, 19 and 20 sequentially show an optical projection lens structure, a distortion curve, a relative illuminance curve, an astigmatism curve and a chromatic aberration curve of embodiment 4 of the present application; fig. 21, 22, 23, 24 and 25 sequentially show an optical projection lens structure, a distortion curve, a relative illuminance curve, an astigmatism curve and a chromatic aberration curve of embodiment 5 of the present application; fig. 26, 27, 28, 29 and 30 sequentially show the optical projection lens structure, distortion curve, relative illuminance curve, astigmatism curve and chromatic aberration curve of embodiment 6 of the present application. The meanings of the reference numerals in the above structure diagrams of the optical projection lenses can refer to the description of fig. 1 in the foregoing, and are not repeated.

In addition, the definitions of the data in the tables of the following embodiments are the same as those in table 1 and table 2 of embodiment 1, and are not repeated herein.

< example 2>

In the optical projection lens of embodiment 2, the focal length of the optical projection lens is f, the aperture value (f-number) of the optical projection lens is Fno, and the maximum viewing angle of the optical projection lens is FOV, which are as follows: f =5.84mm; fno =1.66; and FOV =30 degrees.

Example 2 the specific values of the conditional expressions of the optical projection lens are as follows:

f3/f＝1.23

|f1+f2+f3+f4|/f＝17.68

(f1+f2+f3)/f＝1.05

(CT2+AT3)/f＝0.28

R21/R22＝1.95

R31/R42＝0.36

CT1/CT3＝1.0

ST＝1mm

more specific optical parameters of the optical elements of the optical projection lens and the corresponding AR apparatus (which includes the waveguide and the aperture) of embodiment 2 can be referred to the following table 3 and table 4.

TABLE 3

TABLE 4

< example 3>

In the optical projection lens of embodiment 3, the focal length of the optical projection lens is f, the aperture value (f-number) of the optical projection lens is Fno, and the maximum viewing angle of the optical projection lens is FOV, which are as follows: f =6.0mm; fno =1.66; and FOV =30 degrees.

Example 3 the conditional expressions of the optical projection lens have the following specific numerical values:

f3/f＝0.87

|f1+f2+f3+f4|/f＝0.54

(f1+f2+f3)/f＝0.80

(CT2+AT3)/f＝0.37

R21/R22＝1.84

R31/R42＝0.3

CT1/CT3＝0.99

ST＝1mm

more specific optical parameters of the optical elements of the optical projection lens and the corresponding AR device (which includes a waveguide sheet and an aperture) of embodiment 3 can be referred to the following table 5 and table 6.

TABLE 5

TABLE 6

< example 4>

In the optical projection lens of embodiment 4, the focal length of the optical projection lens is f, the aperture value (f-number) of the optical projection lens is Fno, and the maximum viewing angle of the optical projection lens is FOV, which are as follows: f =6.00mm; fno =1.66; and FOV =30 degrees.

Example 4 the conditional expressions of the optical projection lens have specific numerical values as follows:

f3/f＝0.82

|f1+f2+f3+f4|/f＝0.28

(f1+f2+f3)/f＝0.79

(CT2+AT3)/f＝0.4

R21/R22＝1.81

R31/R42＝0.28

CT1/CT3＝0.92

ST＝1mm

more specific optical parameters of the optical elements of the optical projection lens and the corresponding AR device (which includes a waveguide sheet and an aperture) of embodiment 4 can be referred to the following table 7 and table 8.

TABLE 7

TABLE 8

< example 5>

In the optical projection lens of embodiment 5, the focal length of the optical projection lens is f, the aperture value (f-number) of the optical projection lens is Fno, and the maximum viewing angle of the optical projection lens is FOV, which are as follows: f =6.08mm; fno =1.8; and FOV =30 degrees.

Example 5 the conditional expressions of the optical projection lens have specific numerical values as follows:

f3/f＝0.89

|f1+f2+f3+f4|/f＝0.98

(f1+f2+f3)/f＝0.92

(CT2+AT3)/f＝0.33

R21/R22＝2.22

R31/R42＝0.19

CT1/CT3＝1.04

ST＝1mm

more specific optical parameters of the optical elements of the optical projection lens and the corresponding AR device (which includes a waveguide sheet and an aperture) of embodiment 5 can be referred to the following table 9 and table 10.

TABLE 9

Watch 10

< example 6>

The optical projection lens of embodiment 6 has a focal length f, an aperture value (f-number) Fno, and a maximum viewing angle FOV as follows: f =5.9mm; fno =1.56; and FOV =30 degrees.

Example 6 the conditional expressions of the optical projection lens have specific numerical values as follows:

f3/f＝0.84

|f1+f2+f3+f4|/f＝0.18

(f1+f2+f3)/f＝0.76

(CT2+AT3)/f＝0.41

R21/R22＝1.79

R31/R42＝0.35

CT1/CT3＝1.0

ST＝1mm

more specific optical parameters of the optical elements of the optical projection lens and the corresponding AR device (which includes a waveguide sheet and an aperture) of embodiment 6 can be referred to the following table 11 and table 12.

TABLE 11

TABLE 12

Given the above specific examples of the optical design of 6 specific optical lens lenses and corresponding AR devices, table 13 below further shows the values of these 6 examples under the respective conditions.

Watch 13

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or substituted with equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered by the scope of the claims of the present invention.

Claims

1. An optical projection lens, comprising, arranged in order from a projection side to a chip side: a first lens, a second lens, a third lens, and a fourth lens; the first lens has positive focal power, the second lens has negative focal power, the third lens has positive focal power, and the fourth lens has negative focal power;

wherein a focal length f of the optical projection lens, a focal length f1 of the first lens, a focal length f2 of the second lens, a focal length f3 of the third lens, and a focal length f4 of the fourth lens satisfy the following relations:

0.8<f3/f<1.3

|f1+f2+f3+f4|/f>0.15

0.5<(f1+f2+f3)/f<1.5。

2. the optical projection lens as claimed in claim 1, wherein the thickness CT1 of the first lens element on the optical axis, the distance AT3 between the third lens element and the fourth lens element on the optical axis, and the focal length f of the optical projection lens satisfy the following relations:

0.25<(CT2+AT3)/f<0.45。

3. the optical projection lens as claimed in claim 2, wherein the surface of the third lens on the projection side is convex and the surface on the chip side is concave.

4. The optical projection lens as claimed in claim 3, wherein the surface of the first lens on the projection side is convex, and the surface of the first lens on the chip side is concave;

the surface of the projection side of the second lens is a convex surface, and the surface of the chip side of the second lens is a concave surface; and

and the surfaces of both sides of the fourth lens are concave surfaces.

5. The optical projection lens of claim 4, wherein the separation distance ST between the stop and the first lens on the optical axis satisfies the following relation:

ST≥1mm。

6. an optical projection lens as claimed in claim 1, characterized in that the radius of curvature R21 of the projection side of the second lens and the radius of curvature R22 of the chip side thereof satisfy the following relation:

1.5<R21/R22<2.5。

7. an optical projection lens as claimed in claim 6, characterized in that the radius of curvature R31 on the projection side of the third lens and the radius of curvature R42 on the chip side of the fourth lens satisfy the following relation:

0.15<R31/R42<1.5。

8. the optical projection lens as claimed in claim 1, wherein the thickness CT1 of the first lens element on the optical axis and the thickness CT3 of the third lens element on the optical axis satisfy the following relation:

CT1/CT3<1.1。

9. the optical projection lens of claim 1 wherein the optical surfaces of the first lens, the second lens, the third lens and the fourth lens are aspheric.

10. The optical projection lens as claimed in claim 1, wherein any two adjacent lenses of the first lens, the second lens, the third lens and the fourth lens have a distance different from zero on an optical axis.

11. An AR projection device, comprising:

the optical projection lens of any one of claims 1-10;

a self-light emitting chip for projecting a light information image to the optical projection lens; and

a waveguide device including a coupling-in region disposed at a front end of the first lens, the front end being an output end of the optical projection lens.

12. The AR projection apparatus of claim 11, wherein the waveguide device is a waveguide sheet having the in-coupling region and the out-coupling region.

13. The AR projection device of claim 12, wherein the waveguide sheet has a first surface fabricated with microstructures constituting the coupling-in region and a second surface disposed between the first surface and the first lens.

14. The AR projection device of claim 13, wherein a stop of the optical projection lens is disposed on the first surface.

15. The AR projection device of claim 13, wherein the optical projection lens further comprises a barrel, the first, second, third, and fourth lenses being mounted to the barrel and grouped into a lens group by the barrel; the second surface is a plane and is supported against the end face of the lens barrel.