CN220207992U - Eyepiece with long exit pupil - Google Patents

Abstract

The embodiment of the utility model provides a long-exit pupil ocular, which relates to the optical lens technology, and comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged from an observation side to a display side along an optical axis; the first, second, fourth, and fifth lenses each have positive optical power, and the third lens has negative optical power. The embodiment of the utility model provides a long-exit pupil eyepiece, which is used for realizing the eyepiece with long exit pupil distance, low distortion and large magnification.

Description

Eyepiece with long exit pupil

Technical Field

The utility model relates to the technology of optical lenses, in particular to a long-exit pupil eyepiece.

Background

With the development of OLED (Organic Light Emitting Diode) and LCOS (Liquid Crystal on Silicon) technologies, the micro display has smaller and smaller pixels, more and more pixels and smaller volume, and is convenient to be installed in the handheld observation device. When the micro display is used for a handheld observation device, an eyepiece is needed to enlarge the micro display for the eyes to watch. Because the micro-displays such as OLED, LCOS and the like have the advantages of high pixel, full color, high resolution and the like, the corresponding requirement can be matched with the eyepiece for use, and the eyepiece can reach higher resolution, small distortion and large magnification; moreover, the handheld observation device is required to be: the large exit pupil diameter and long exit pupil distance are convenient for field and night use.

The existing ocular generally has defects of different types or different degrees such as small exit pupil distance (generally not more than 22 mm), large distortion, small magnification (generally not more than 10 times) and the like, so that the development of ocular with long exit pupil distance, low distortion and large magnification is urgent.

Disclosure of Invention

The embodiment of the utility model provides a long-exit pupil eyepiece, which is used for realizing the eyepiece with long exit pupil distance, low distortion and large magnification.

The embodiment of the utility model provides a long-exit pupil eyepiece, which comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged from an observation side to a display side along an optical axis;

the first, second, fourth, and fifth lenses each have positive optical power, and the third lens has negative optical power.

Optionally, the combined optical power of the first lens and the second lens is Φ12, and the optical power of the long exit pupil eyepiece is Φ, which satisfies the following conditions:

0.787≤Φ/Φ12≤1.307。

optionally, a minimum value of refractive index in both the first lens and the fourth lens is greater than or equal to 1.456.

Optionally, the lens further comprises a diaphragm, and the diaphragm is located on one side of the first lens away from the second lens.

Optionally, an on-axis distance from the diaphragm to the observation side surface of the first lens is an exit pupil distance, denoted as EL, and an effective focal length of the long exit pupil eyepiece is f, which satisfies:

2.013≤EL/f≤2.475；

wherein the viewing side surface is a surface of the lens facing the viewing side.

Optionally, the abbe number of the third lens is Vd3, and the abbe number of the fourth lens is Vd4, which satisfies the following conditions:

|Vd3-Vd4|≥23.551。

optionally, the optical power of the third lens is Φ3, and the optical power of the long exit pupil eyepiece is Φ, which satisfies the following conditions:

-2.004≤Φ3/Φ≤-1.215。

optionally, the optical power of the first lens is Φ1, and the optical power of the long exit pupil eyepiece is Φ, which satisfies the following conditions:

0.274≤Φ1/Φ≤0.411。

optionally, the center thickness of the first lens is CT1, the center thickness of the fourth lens is CT4, and the on-axis distance from the viewing side surface of the first lens to the display side surface of the fifth lens is CT, which satisfies the following conditions:

0.244≤(CT1+CT4)/CT≤0.421；

the display side surface is a surface of the lens facing the display side, and the center thickness is an on-axis distance from a viewing side surface of the lens to the display side surface.

Optionally, half of the maximum field angle of the long exit pupil eyepiece is noted as HFOV, satisfying:

14°≥HFOV≥13°。

in the first embodiment of the utility model, the optical powers of the first lens, the second lens, the third lens, the fourth lens and the fifth lens are positive, negative, positive and positive respectively. Thereby providing an eyepiece with long exit pupil distance, low distortion and large magnification.

Drawings

FIG. 1 is a schematic diagram of a long exit pupil eyepiece according to a first embodiment of the utility model;

FIG. 2 is a diagram of a fan of light rays from a long exit pupil eyepiece according to a first embodiment of the utility model;

FIG. 3 is a graph showing curvature of field of a long exit pupil eyepiece according to a first embodiment of the utility model;

FIG. 4 is a graph showing distortion of a long exit pupil eyepiece according to a first embodiment of the utility model;

FIG. 5 is a schematic diagram of a long exit pupil eyepiece according to a second embodiment of the utility model;

FIG. 6 is a diagram of a ray fan of a long exit pupil eyepiece according to a second embodiment of the utility model;

FIG. 7 is a graph showing curvature of field of a long exit pupil eyepiece according to a second embodiment of the utility model;

FIG. 8 is a graph showing distortion of a long exit pupil eyepiece in a second embodiment of the utility model;

FIG. 9 is a schematic diagram of a structure of a long exit pupil eyepiece according to a third embodiment of the utility model;

FIG. 10 is a ray fan diagram of a long exit pupil eyepiece in a third embodiment of the utility model;

FIG. 11 is a graph of curvature of field of a long exit pupil eyepiece in a third embodiment of the utility model;

fig. 12 is a graph showing distortion of a long exit pupil eyepiece in a third embodiment of the utility model.

Detailed Description

The utility model is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the utility model and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present utility model are shown in the drawings.

Example 1

Fig. 1 is a schematic structural diagram of a long-exit pupil eyepiece according to a first embodiment of the present utility model, and referring to fig. 1, the long-exit pupil eyepiece includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a fifth lens 5 sequentially arranged from a viewing side to a display side along an optical axis. The observation side is a side on which an observer observes using a long exit pupil eyepiece. The display side is the side on which the observed object is located, and the observed object may include a micro display, for example. The first lens 1, the second lens 2, the fourth lens 4, and the fifth lens 5 each have positive optical power, and the third lens 3 has negative optical power.

In the first embodiment of the present utility model, the optical powers of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4 and the fifth lens 5 are positive, negative, positive and positive, respectively. Thereby providing an eyepiece with long exit pupil distance, low distortion and large magnification.

The second lens 2, the third lens 3, and the fifth lens 5 may be plastic aspherical lenses, and the first lens 1 and the fourth lens 4 may be glass spherical or glass aspherical lenses, for example. By adopting a glass-plastic mixed structure, the eyepiece design which can give consideration to long exit pupil distance, low distortion and large magnification is realized through the collocation of lens materials and the reasonable distribution of the focal power of each lens, the exit pupil distance is not less than 45mm, the absolute value of distortion is less than or equal to 3%, and the magnification is 12.5 times.

Optionally, referring to fig. 1, the combined optical power of the first lens 1 and the second lens 2 is Φ12, and the optical power of the long exit pupil eyepiece is Φ, which satisfies: phi/phi 12 is more than or equal to 0.787 and less than or equal to 1.307. The minimum value of the refractive index in both the first lens and the fourth lens is greater than or equal to 1.456. The refractive index of the first lens 1 is denoted as Nd1, and the refractive index of the fourth lens 4 is denoted as Nd4, and MIN (Nd 1, nd 4) > 1.456. Therefore, the height of the long-exit pupil ocular lens into which the light enters is controlled, the light is collected, the off-axis aberration is limited, and meanwhile, the requirement of a target surface can be met. And the focal power of the long exit pupil ocular can be reasonably distributed, so that the resolution is improved and the larger exit pupil distance is satisfied.

Optionally, referring to fig. 1, the long exit pupil eyepiece further comprises a stop STO, which is located at a side of the first lens 1 remote from the second lens 2.

Alternatively, referring to fig. 1, the on-axis distance of the stop STO to the observation side surface of the first lens 1 is the exit pupil distance, denoted EL. The effective focal length of the long exit pupil eyepiece is f, which satisfies the following conditions: EL/f is more than or equal to 2.013 and less than or equal to 2.475. Wherein the viewing side surface is the surface of the lens facing the viewing side. The magnification of the long exit pupil eyepiece is the distance between the human eye's clear vision (250 mm distance between the human eye's clear vision) divided by the effective focal length of the long exit pupil eyepiece. The smaller the effective focal length of the long exit pupil eyepiece, the greater the magnification of the long exit pupil eyepiece. The smaller the effective focal length of the long exit pupil ocular lens is, the larger the field angle which is required to be achieved by the same target surface is, so that larger off-axis aberration is brought, the larger the effective focal length of the long exit pupil ocular lens is, the larger the chromatic aberration is, and the image quality cannot meet the design requirement. In the embodiment, EL/f is limited to be less than or equal to 2.013 and less than or equal to 2.475, and the requirements of large exit pupil distance and large magnification can be well met at the same time.

Optionally, referring to fig. 1, the abbe number of the third lens is Vd3, and the abbe number of the fourth lens is Vd4, satisfying: vd3-Vd4 is not less than 23.551. Thereby facilitating a reduction in chromatic aberration of the long exit pupil eyepiece, thereby ensuring higher imaging quality.

Optionally, referring to fig. 1, the third lens 3 has optical power Φ3, and the long exit pupil eyepiece has optical power Φ, which satisfies the following: -2.004. Ltoreq.Φ3/Φ.ltoreq.1.215. The focal power of the first lens 1 is phi 1, the focal power of the long-pupil eyepiece is phi, and the following conditions are satisfied: phi 1/phi 0.274-0.411. In this embodiment, the distortion of the long exit pupil eyepiece is balanced by defining the power of the first lens 1 and/or the power of the third lens 3. Wherein the distortion of the long exit pupil eyepiece is the sum of the distortions of all lenses.

Alternatively, referring to fig. 1, the center thickness of the first lens 1 is CT1, and the center thickness of the fourth lens 4 is CT4. The on-axis distance from the observation side surface of the first lens 1 to the display side surface of the fifth lens 5 is CT. The method meets the following conditions: the ratio of (CT1+CT4)/CT is more than or equal to 0.244 and less than or equal to 0.421. The display side surface is a surface of the lens facing the display side, and the center thickness is an on-axis distance from the observation side surface of the lens to the display side surface. In the embodiment, the ratio of (CT1+CT4)/CT is limited to 0.244 and less than or equal to 0.421, so that the total length of the long-exit pupil eyepiece is reduced, and the long-exit pupil eyepiece is ensured to have a smaller size.

Alternatively, referring to FIG. 1, half of the maximum field angle of the long exit pupil eyepiece is noted as HFOV, satisfying: the HFOV is more than or equal to 14 degrees and more than or equal to 13 degrees. The larger the exit pupil distance, the larger the off-axis aberration generated, the larger the field angle, and the higher the height of light entering the long exit pupil eyepiece, and the larger the off-axis aberration. In the embodiment, the limit of 14 degrees is more than or equal to 13 degrees of HFOV, the height of light entering the system can be controlled, the off-axis aberration is limited, and the requirement of a target surface can be met.

Illustratively, referring to fig. 1, the long exit pupil eyepiece further comprises a plate glass 6, the plate glass 6 being located on the side of the fifth lens 5 remote from the fourth lens 4. The plate glass 6 may be a cover glass or a filter having a filtering function.

Table 1 design value of long exit pupil eyepiece in example one

Table 1 shows a design value of the long exit pupil eyepiece in the first embodiment, and the specific numerical value of the design value can be adjusted according to the product requirement, which is not a limitation of the embodiment of the utility model. The long exit pupil eyepieces shown in table 1 may be those shown in fig. 1. A lens generally comprises two surfaces, each of which is a refractive surface. The surface numbers in table 1 are numbered according to the surfaces of the respective lenses. Wherein, the surface number "1" indicates the front surface (i.e. the viewing side surface) of the first lens 1, the surface number "2" indicates the rear surface (i.e. the display side surface) of the first lens 1, and so on, and will not be described herein. Note that "O" in the column of "face number" indicates the plane in which the stop STO lies. The radius of curvature represents the degree of curvature of the lens surface, a positive value of the radius of curvature representing the center of curvature on the side of the surface closer to the image side (i.e., the display side), and a negative value of the radius of curvature representing the center of curvature on the side of the surface farther from the image side. The "INF" in the column of "radius of curvature" represents infinity. The values in the column "thickness" represent the axial distance from the current surface to the next surface. The column "refractive index" indicates the refractive index of the medium from the current surface to the next surface, representing the ability of the material from the current surface to the next surface to deflect light. The space in the column of "refractive index" is the refractive index of air, and the refractive index of air is 1. The Abbe number represents the dispersive properties of the material from the current surface to the next surface for light, and the space represents the current position as air. The numerical value in the column "half-caliber" represents half the caliber of the current surface.

Optionally, the surface of the aspherical lens satisfies the formula:

wherein Z is the axial sagittal height of the surface in the Z direction, r is the height of the aspheric surface, i.e. when Z is the position of the aspheric surface with the height r along the optical axis direction, the distance sagittal height from the vertex of the aspheric surface; c is the curvature of the fitting sphere, c is the inverse of the curvature radius in value, c=1/R, R represents the paraxial curvature radius of the mirror; k is a conic coefficient, A, B, C is an aspherical coefficient, specifically A, B, C is a coefficient of 4 th, 6 th and 8 th order terms of the aspherical polynomial, respectively.

Table 2 a design value for aspherical coefficients of lenses in a long exit pupil eyepiece in example one

Face number	k	A	B	C
					3	-1.544	1.940470E-05	-1.003652E-08	-1.121417E-09
4	5.436	-2.106836E-06	-4.299734E-07	-4.995528E-10
					5	36.792	4.905275E-05	-8.147737E-08	-5.542115E-10
6	-3.836	6.533962E-06	-9.047393E-08	-4.375267E-10
					7	0.0	2.617979E-06	-5.281330E-09	4.233918E-10
8	0.0	5.027490E-07	4.795919E-08	1.330427E-10
					9	-0.071	-2.212759E-04	-3.327230E-07	-1.631495E-08
10	-200.003	5.802619E-05	3.078793E-08	-3.574747E-09

Table 2 is a design value of the aspherical coefficient of the lens in the eyepiece with a long exit pupil in the first embodiment, and the specific value of the design value can be adjusted according to the product requirement, which is not a limitation of the embodiment of the utility model. The long exit pupil eyepiece shown in table 2 may be that shown in fig. 1. The column of "face number" in table 2 corresponds to the meaning of "face number" in table 1. "E" in the various embodiments of the present utility model represents an index based on 10.

Fig. 2 is a light fan diagram of a long exit pupil eyepiece according to a first embodiment of the present utility model, and the light fan diagram is one of the most commonly used evaluation methods in modern optical design. The abscissa is the beam caliber and the ordinate is the vertical aberration. The most ideal curve is a straight line which coincides with the abscissa, which means that all the light rays are converged at the same point on the image plane, and the corresponding interval on the ordinate of the curve is the maximum dispersion range of the light beam on the ideal plane. The light fan graph can reflect monochromatic aberration with different wavelengths and can also show the magnitude of vertical axis chromatic aberration. As can be seen from fig. 2, the long exit pupil eyepiece is better near the abscissa of each wavelength in each view field, which means that the vertical axis aberration of each wavelength of the system is better corrected, meanwhile, each wavelength is not obviously dispersed, which means that the chromatic aberration of the system is better corrected, thereby ensuring that the long exit pupil eyepiece can realize the high-resolution imaging requirement.

FIG. 3 is a graph showing the curvature of field of a long exit pupil eyepiece according to a first embodiment of the utility model, and referring to FIG. 3, the horizontal coordinate represents the magnitude of the curvature of field in mm; the vertical coordinates represent the normalized image height without units; where T represents meridian and S represents sagittal. As can be seen from fig. 3, the long exit pupil eyepiece provided in this embodiment is effectively controlled in curvature of field, i.e., the difference between the image quality of the center and the image quality of the periphery is small at the time of imaging.

Fig. 4 is a graph of distortion of a long exit pupil eyepiece in accordance with an embodiment of the utility model, and referring to fig. 4, the horizontal coordinate represents the magnitude of distortion in percent (%); the vertical coordinates represent the normalized image height with no units. As can be seen from fig. 3, the distortion of the long exit pupil eyepiece provided in the present embodiment is well corrected, and the imaging distortion is small.

Example two

The same points as in the first embodiment will not be described again here.

Table 3 design value of long exit pupil eyepiece in example two

Table 3 shows a design value of the long pupil eyepiece in the second embodiment, the specific value of which can be adjusted according to the product requirement, and the design value is not limited to the embodiment of the utility model. The long exit pupil eyepiece shown in table 3 may be that shown in fig. 5.

Optionally, the surface of the aspherical lens satisfies the formula:

wherein Z is the axial sagittal height of the surface in the Z direction, r is the height of the aspheric surface, i.e. when Z is the position of the aspheric surface with the height r along the optical axis direction, the distance sagittal height from the vertex of the aspheric surface; c is the curvature of the fitting sphere, c is the inverse of the curvature radius in value, c=1/R, R represents the paraxial curvature radius of the mirror; k is a conic coefficient, A, B, C, D is an aspherical coefficient, specifically A, B, C, D is a coefficient of 4 th, 6 th, 8 th and 10 th order terms of the aspherical polynomial, respectively.

Table 4 a design value for aspherical coefficients of lenses in the long exit pupil eyepiece in example two

Table 4 is a design value of the aspherical coefficient of the lens in the eyepiece with a long exit pupil in the second embodiment, and the specific value of the design value can be adjusted according to the product requirement, which is not a limitation of the embodiment of the utility model. The long exit pupil eyepiece shown in table 4 may be as shown in fig. 5.

Example III

The same points as in the first and second embodiments are not described here again.

Table 5 design value of long exit pupil eyepiece in example three

Face number	Surface type	Radius of curvature (mm)	Thickness (mm)	Refractive index	Abbe number	Semi-caliber (mm)
							0	Plane surface	INF	45.000			3.000
1	Spherical surface	34.659	4.350	1.697	55.534	13.000
							2	Spherical surface	226.216	0.143			13.000
3	Aspherical surface	12.151	6.060	1.658	89.262	12.994
							4	Aspherical surface	18.556	0.375			12.511
5	Aspherical surface	27.610	3.037	1.835	35.227	12.347
							6	Aspherical surface	6.536	2.093			10.970
7	Spherical surface	17.163	5.936	1.699	79.899	10.998
							8	Spherical surface	261.387	0.200			10.433
9	Aspherical surface	7.171	4.663	1.582	89.994	9.153
							10	Aspherical surface	29.003	6.132			8.789
11	Plane surface	INF	1.700	1.517	64.167	5.690
							12	Plane surface	INF	0.100			5.156

Table 5 shows a design value of the long pupil eyepiece in the third embodiment, the specific value of which can be adjusted according to the product requirement, and is not a limitation of the embodiment of the present utility model. The long exit pupil eyepiece shown in table 5 may be as shown in fig. 9.

Table 6 a design value of aspherical coefficient of lens in eyepiece of long exit pupil in third embodiment

Face number	k	A	B	C	D
						S3	-1.342	-1.741383E-05	-6.461944E-07	3.984798E-09	-8.925143E-12
S4	0.123	-8.587915E-05	-3.905193E-07	2.242871E-10	1.450613E-12
						S5	1.867	-2.094412E-06	-4.873846E-07	-1.331575E-10	1.796565E-12
S6	-1.967	-8.553366E-06	-6.307354E-08	-3.414732E-10	-6.481626E-12
						S9	-0.816	-3.542149E-04	-4.080220E-07	-1.838160E-08	8.974954E-11
S10	-38.378	-2.241291E-04	1.662516E-06	-1.118015E-08	4.520991E-11

Table 6 is a design value of the aspherical coefficient of the lens in the eyepiece with a long exit pupil in the third embodiment, and the specific value of the design value can be adjusted according to the product requirement, which is not a limitation of the embodiment of the utility model. The long exit pupil eyepiece shown in table 6 may be that shown in fig. 9.

Note that the above is only a preferred embodiment of the present utility model and the technical principle applied. It will be understood by those skilled in the art that the present utility model is not limited to the particular embodiments described herein, and that various obvious changes, rearrangements, combinations, and substitutions can be made by those skilled in the art without departing from the scope of the utility model. Therefore, while the utility model has been described in connection with the above embodiments, the utility model is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the utility model, which is set forth in the following claims.

Claims (9)

1. A long exit pupil eyepiece comprising a first lens, a second lens, a third lens, a fourth lens and a fifth lens arranged in this order from an observation side to a display side along an optical axis;

the first lens, the second lens, the fourth lens and the fifth lens all have positive optical power, and the third lens has negative optical power;

the combined focal power of the first lens and the second lens is phi 12, and the focal power of the long-exit pupil eyepiece is phi, so that the following conditions are satisfied:

0.787≤Φ/Φ12≤1.307。

2. the long exit pupil eyepiece of claim 1, wherein a minimum value of refractive index in both the first lens and the fourth lens is greater than or equal to 1.456.

3. The long exit pupil eyepiece of claim 1, further comprising a stop located on a side of the first lens remote from the second lens.

4. A long exit pupil eyepiece according to claim 3, characterized in that the distance on axis of the stop to the viewing side surface of the first lens is the exit pupil distance, denoted EL, and the effective focal length of the long exit pupil eyepiece is f, satisfying:

2.013≤EL/f≤2.475；

wherein the viewing side surface is a surface of the lens facing the viewing side.

5. The long exit pupil eyepiece of claim 1, wherein the abbe number of the third lens is Vd3 and the abbe number of the fourth lens is Vd4, satisfying:

|Vd3-Vd4|≥23.551。

6. the long exit pupil eyepiece of claim 1, wherein the third lens has an optical power of Φ3, and the long exit pupil eyepiece has an optical power of Φ that satisfies:

-2.004≤Φ3/Φ≤-1.215。

7. the long exit pupil eyepiece of claim 1, wherein the first lens has an optical power Φ1, and the long exit pupil eyepiece has an optical power Φ that satisfies:

0.274≤Φ1/Φ≤0.411。

8. the long exit pupil eyepiece of claim 1, wherein the first lens has a center thickness of CT1, the fourth lens has a center thickness of CT4, and an on-axis distance from a viewing side surface of the first lens to a display side surface of the fifth lens is CT, satisfying:

0.244≤(CT1+CT4)/CT≤0.421；

the display side surface is a surface of the lens facing the display side, and the center thickness is an on-axis distance from a viewing side surface of the lens to the display side surface.

9. The long exit pupil eyepiece of claim 1, wherein half of the maximum field angle of the long exit pupil eyepiece is denoted HFOV, satisfying:

14°≥HFOV≥13°。