A low-distortion ultra-wide-angle eyepiece

Abstract

The present invention discloses a low-distortion ultra-wide-angle eyepiece, comprising: an aperture, a first lens group, a second lens group, and a third lens group, coaxially arranged along the optical axis from the eye side to the image side; the first lens group has positive or negative refractive power; the second lens group has positive refractive power; and the third lens group has negative refractive power. The low-distortion ultra-wide-angle eyepiece satisfies the following conditions: 0.01 <|f*NA / D0| < 0.5; 0.01 <|f / f1| < 0.5; 0.50 <|f / f2| < 0.9; 0.01 <|f / f3| < 0.7; 0.01 <|f2 / f1| < 0.5; and 0.02 <|f2 / f3| < 0.7. The eyepiece of the present invention still has low distortion performance at ultra-wide angles.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to a low-distortion ultra-wide-angle eyepiece. Background Art

[0002] In recent years, with the rapid development of the optical industry, the use of eyepiece optical systems (such as microscopes, telescopes, cameras, augmented reality devices, and head-mounted devices) for observation has increased in military, industrial, medical, educational, and consumer fields. Users use eyepieces to magnify the observed image to obtain intuitive and visual images, videos, text, and other information. To obtain as much information as possible from the image, with the highest clarity and without distortion, users often require eyepieces with ultra-wide angles, low distortion, high resolution, and minimal field curvature.

[0003] Chinese Patent Documents 1 (CN 112764221 A), 2 (CN 112630978 A), 3 (CN112630976 A), and 4 (CN 112630975 A) disclose eyepiece optical systems and head-mounted display devices with large fields of view. Specifically, they provide optical systems that combine positive, negative, and positive lens groups. However, the eyepiece optical systems and head-mounted display devices disclosed in these references focus on head-mounted display applications and cannot meet the requirements of some applications with higher field of view and distortion performance requirements (such as microscopy observation). Summary of the Invention

[0004] In view of the above-mentioned defects of the prior art, the present invention provides a low-distortion ultra-wide-angle eyepiece.

[0005] The present invention adopts the following technical solutions:

[0006] A low-distortion ultra-wide-angle eyepiece, comprising: an aperture, a first lens group, a second lens group, and a third lens group, which are coaxially arranged in sequence along the optical axis from the eye side to the image side; the first lens group has positive or negative refractive power; the second lens group has positive refractive power; and the third lens group has negative refractive power; the low-distortion ultra-wide-angle eyepiece satisfies the following conditional formula:

[0007] 0.01<|f*NA / D0|<0.5;

[0008] 0.01<|f / f1|<0.5;

[0009] 0.50<|f / f2|<0.9;

[0010] 0.01<|f / f3|<0.7;

[0011] 0.01<|f2 / f1|<0.5;

[0012] 0.02<|f2 / f3|<0.7;

[0013] Where, f is the focal length of the eyepiece; NA is the image-side numerical aperture of the eyepiece; D0 is the distance from the aperture to the optical axis of the lens surface closest to the eye; f1 is the focal length of the first lens group; f2 is the focal length of the second lens group; and f3 is the focal length of the third lens group.

[0014] Preferably, the first lens group includes a first lens with negative refractive power and a second lens with positive refractive power, and the surface of the first lens facing the image side is cemented to the surface of the second lens facing the eye side; the second lens group includes a third lens with positive refractive power and a fourth lens with positive refractive power; the third lens group includes a fifth lens with positive refractive power and a sixth lens with negative refractive power, and the surface of the fifth lens facing the image side is cemented to the surface of the sixth lens facing the eye side.

[0015] Preferably, the first lens group, the second lens group and the third lens group satisfy the following conditional formula:

[0016] 0.01<|f11 / f1|<0.50;

[0017] 0.02<|f12 / f1|<0.60;

[0018] 1.00<|f21 / f2|<5.00;

[0019] 1.00<|f22 / f2|<5.00;

[0020] 0.01<|f31 / f3|<0.90;

[0021] 0.01<|f32 / f3|<0.50;

[0022] Among them, f11 is the focal length of the first lens; f12 is the focal length of the second lens; f21 is the focal length of the third lens; f22 is the focal length of the fourth lens; f31 is the focal length of the fifth lens; and f32 is the focal length of the sixth lens.

[0023] Preferably, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens satisfy the following conditional formula:

[0024] N11≥1.85;

[0025] N12≥1.55;

[0026] N21≥1.85;

[0027] N22≤1.65;

[0028] N31≤1.75;

[0029] N32≥1.85;

[0030] Among them, N11 is the refractive index of the first lens; N12 is the refractive index of the second lens; N21 is the refractive index of the third lens; N22 is the refractive index of the fourth lens; N31 is the refractive index of the fifth lens; N32 is the refractive index of the sixth lens.

[0031] Preferably, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens satisfy the following conditional formula:

[0032] V11≥17.5;

[0033] V12≤70.5;

[0034] V21≥17.5;

[0035] V22≤65.5;

[0036] V31≥55.5;

[0037] V32≥17.5;

[0038] Among them, V11 is the Abbe number of the first lens; V12 is the Abbe number of the second lens; V21 is the Abbe number of the third lens; V22 is the Abbe number of the fourth lens; V31 is the Abbe number of the fifth lens; V32 is the Abbe number of the sixth lens.

[0039] Preferably, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens satisfy the following conditional formula:

[0040] 0.50 <T1 / T2<0.95;

[0041] 0.50 <T1 / T3<0.98;

[0042] 0.10 <T11 / T1<0.60;

[0043] 0.30 <T12 / T1<1.10;

[0044] 0.10 <T21 / T2<0.80;

[0045] 0.30 <T22 / T2<0.80;

[0046] 0.10 <T31 / T3<0.90;

[0047] 0.10 <T32 / T3<0.50;

[0048] Wherein, T1 is the length of the first lens group on the optical axis; T2 is the length of the second lens group on the optical axis; T3 is the length of the third lens group on the optical axis; T11 is the thickness of the first lens on the optical axis; T12 is the thickness of the second lens on the optical axis; T21 is the thickness of the third lens on the optical axis; T22 is the thickness of the fourth lens on the optical axis; T31 is the thickness of the fifth lens on the optical axis; T32 is the thickness of the sixth lens on the optical axis.

[0049] Preferably, the low-distortion ultra-wide-angle eyepiece further includes: an eyepiece main body and a first spacer; the surface of the first lens facing the eye side is placed in the eyepiece main body; the surface of the second lens facing the image side is placed in the first spacer; the surface of the third lens facing the eye side contacts the first spacer; the second lens and the third lens are spaced apart on the optical axis.

[0050] Preferably, the low-distortion ultra-wide-angle eyepiece further includes: a second spacer; the surface of the third lens facing the image side is placed in the second spacer; the surface of the fourth lens facing the eye side contacts the second spacer; and the third lens and the fourth lens are spaced apart on the optical axis.

[0051] Preferably, the low-distortion ultra-wide-angle eyepiece further includes: a third spacer; the surface of the fourth lens facing the image side is placed in the third spacer; the surface of the fifth lens facing the eye side contacts the third spacer; and the fourth lens and the fifth lens are spaced apart on the optical axis.

[0052] Preferably, the low-distortion ultra-wide-angle eyepiece further includes: a pressure ring; the pressure ring is placed on the surface of the sixth lens facing the image side.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] (1) The eyepiece of the present invention includes a first lens group, a second lens group, and a third lens group, wherein the first lens group has positive / negative refractive power, the second lens group has positive refractive power, and the third lens group has negative refractive power; by limiting the focal length of the eyepiece, the image-side numerical aperture of the eyepiece, the distance from the aperture to the optical axis of the lens surface closest to the eye, the focal length of the first lens group, the focal length of the second lens group, and the focal length of the third lens group, the eyepiece of the present invention has a larger magnification, high optical performance, a larger numerical aperture, and better resolution;

[0055] (2) The first lens group of the present invention includes a first lens with negative refractive power and a second lens with positive refractive power, and the first lens is glued to the second lens; the second lens group includes a third lens with positive refractive power and a fourth lens with positive refractive power; the third lens group includes a fifth lens with positive refractive power and a sixth lens with negative refractive power, and the fifth lens is glued to the sixth lens; by limiting the focal distance, refractive index, Abbe number and thickness, the field curvature, distortion and aberration sensitivity of the eyepiece of the present invention are further improved, thereby ensuring the optical performance of the eyepiece, so that the eyepiece still has low distortion performance at ultra-wide angles.

[0056] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 1 is a lens composition diagram of the eyepiece optical system according to the first embodiment of the present invention;

[0058] Figure 2 This is a spherical aberration diagram of the eyepiece optical system according to the first embodiment of the present invention;

[0059] Figure 3 A field curvature diagram of the eyepiece optical system according to embodiment 1 of the present invention;

[0060] Figure 4 This is a distortion diagram of the eyepiece optical system according to the first embodiment of the present invention;

[0061] Figure 5 This is a diagram of the MTF (Modulation Transfer Function) of the eyepiece optical system according to the first embodiment of the present invention;

[0062] Figure 6 2 is a lens composition diagram of the eyepiece optical system according to the second embodiment of the present invention;

[0063] Figure 7 This is a spherical aberration diagram of the eyepiece optical system according to the second embodiment of the present invention;

[0064] Figure 8 A field curvature diagram of the eyepiece optical system according to the second embodiment of the present invention;

[0065] Figure 9 This is a distortion diagram of the eyepiece optical system of Example 2 of the present invention;

[0066] Figure 10 This is an MTF (Modulation Transfer Function) diagram of the eyepiece optical system according to the second embodiment of the present invention;

[0067] Figure 11 1 is a lens composition diagram of the eyepiece optical system according to the third embodiment of the present invention;

[0068] Figure 12 This is a spherical aberration diagram of the eyepiece optical system according to the third embodiment of the present invention;

[0069] Figure 13 This is a field curvature diagram of the eyepiece optical system according to the third embodiment of the present invention;

[0070] Figure 14 This is a distortion diagram of the eyepiece optical system of Example 3 of the present invention;

[0071] Figure 15 This is an MTF (Modulation Transfer Function) diagram of the eyepiece optical system of Example 3 of the present invention. DETAILED DESCRIPTION

[0072] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention.

[0073] In the description of the present invention, it should be understood that the terms "first," "second," etc. are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being described. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0074] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "placed in," and "contacting" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections, or mutual communication; direct connections or indirect connections through an intermediate medium; and internal communication between two elements or interaction between two elements. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0075] First use Figure 1 The structure of the microscope eyepiece of this embodiment will be described. The microscope eyepiece EY comprises, in order from the eye side, a first lens group 81 with positive or negative refractive power, a second lens group 82 with positive refractive power, and a third lens group 83 with negative refractive power. This combination provides the eyepiece with strong positive refractive power, thereby ensuring that the microscope eyepiece EY offers a greater magnification and high optical performance.

[0076] In order for the eyepiece optical system to have a larger numerical aperture and better resolution, the following conditions must be met:

[0077] 0.01<|f*NA / D0|<0.5;

[0078] 0.01<|f / f1|<0.5;

[0079] 0.50<|f / f2|<0.9;

[0080] 0.01<|f / f3|<0.7;

[0081] 0.01<|f2 / f1|<0.5;

[0082] 0.02<|f2 / f3|<0.7;

[0083] Among them, f is the focal length of the eyepiece; NA is the image-side numerical aperture of the eyepiece; D0 is the distance from the aperture 700 to the optical axis of the lens surface closest to the eye; f1 is the focal length of the first lens group 81; f2 is the focal length of the second lens group 82; f3 is the focal length of the third lens group 83.

[0084] In the above-mentioned eyepiece optical system, the first lens group 81 is composed of a first lens 811 having a negative refractive power and a second lens 812 having a positive refractive power. The second lens group 82 is composed of a third lens 821 having a positive refractive power and a fourth lens 822 having a positive refractive power. The third lens group 83 is composed of a first lens 731 having a positive refractive power and a second lens 732 having a negative refractive power.

[0085] The first lens group 81, the second lens group 82, and the third lens group 83 need to meet the following conditions to better control distortion and field curvature:

[0086] 0.01<|f11 / f1|<0.50;

[0087] 0.02<|f12 / f1|<0.60;

[0088] 1.00<|f21 / f2|<5.00;

[0089] 1.00<|f22 / f2|<5.00;

[0090] 0.01<|f31 / f3|<0.90;

[0091] 0.01<|f32 / f3|<0.50;

[0092] Among them, f11 is the focal length of the first lens 811, f12 is the focal length of the second lens 812, f21 is the focal length of the third lens 821, f22 is the focal length of the fourth lens 822, f31 is the focal length of the fifth lens 831, and f32 is the focal length of the sixth lens 832.

[0093] In order to reduce the on-axis coma and on-axis convergence aberration of the eyepiece optical system, the refractive indices of the first lens group 81, the second lens group 82, and the third lens group 83 are set as follows to further correct the field curvature of the eyepiece optical system.

[0094] The first lens 811, the second lens 812, the third lens 821, the fourth lens 822, the fifth lens 831, and the sixth lens 832 are made of materials that meet the following conditions:

[0095] N11≥1.85;

[0096] N12≥1.55;

[0097] N21≥1.85;

[0098] N22≤1.65;

[0099] N31≤1.75;

[0100] N32≥1.85;

[0101] Wherein, N11 is the refractive index of the first lens 811, N12 is the refractive index of the second lens 812, N21 is the refractive index of the third lens 821, N22 is the refractive index of the fourth lens 822, N31 is the refractive index of the fifth lens 831, and N32 is the refractive index of the sixth lens 832.

[0102] The first lens 811, the second lens 812, the third lens 821, the fourth lens 822, the fifth lens 831, and the sixth lens 832 are made of materials that meet the following conditions:

[0103] V11≥17.5;

[0104] V12≤70.5;

[0105] V21≥17.5;

[0106] V22≤65.5;

[0107] V31≥55.5;

[0108] V32≥17.5;

[0109] Among them, V11 is the Abbe number of the first lens 811, V12 is the Abbe number of the second lens 812, V21 is the Abbe number of the third lens 821, V22 is the Abbe number of the fourth lens 822, V31 is the Abbe number of the fifth lens 831, and V32 is the Abbe number of the sixth lens 832.

[0110] In addition, in order to reduce on-axis spherical aberration and off-axis coma, the thicknesses of the first lens group 81, the second lens group 82, and the third lens group 83 are set as follows:

[0111] 0.50 <T1 / T2<0.95;

[0112] 0.50 <T1 / T3<0.98;

[0113] 0.10 <T11 / T1<0.60;

[0114] 0.30 <T12 / T1<1.10;

[0115] 0.10 <T21 / T2<0.80;

[0116] 0.30 <T22 / T2<0.80;

[0117] 0.10 <T31 / T3<0.90;

[0118] 0.10 <T32 / T3<0.50;

[0119] Wherein, T1 is the length of the first lens group 81 on the optical axis, T2 is the length of the second lens group 82 on the optical axis, T3 is the length of the third lens group 83 on the optical axis, T11 is the thickness of the first lens 811 on the optical axis, T12 is the thickness of the second lens 812 on the optical axis, T21 is the thickness of the third lens 821 on the optical axis, T22 is the thickness of the fourth lens 822 on the optical axis, T31 is the thickness of the fifth lens 831 on the optical axis, and T32 is the thickness of the sixth lens 832 on the optical axis.

[0120] In order to further elaborate the technical content of the invention, three embodiments are listed below to describe the eyepiece optical system in detail.

[0121] Example 1

[0122] like Figure 1As shown, the low-distortion ultra-wide-angle eyepiece EY01 of the first embodiment includes an aperture 700 (located on the eye side), an image plane 701 (located on the image side), a first lens group 81, a second lens group 82, and a third lens group 83. The first lens group 81 includes a first lens 811 with negative refractive power and a second lens 812 with positive refractive power. The surface of the first lens 811 facing the eye is a first surface 8111, and the surface facing the image side is a second surface 8112. The surface of the second lens 812 facing the eye is 8121, and the surface facing the image side is a second surface 8122.

[0123] The second lens group 82 includes a third lens 821 with positive refractive power and a fourth lens 822 with positive refractive power. The surface of the third lens 821 facing the eye is a first surface 8211, and the surface facing the image side is a second surface 8212. The surface of the fourth lens 822 facing the eye is a first surface 8221, and the surface facing the image side is a second surface 8222.

[0124] The third lens group 83 includes a fifth lens element 831 with positive refractive power and a sixth lens element 832 with positive refractive power. The surface of the fifth lens element 831 facing the eye is a first surface 8311, and the surface facing the image side is a second surface 8312. The surface of the sixth lens element 832 facing the eye is a first surface 8321, and the surface facing the image side is a second surface 8322.

[0125] The surface 8112 of the first lens 811 facing the image side is glued to the surface 8121 of the second lens 812 facing the eye side, and the first lens 811 facing the eye side is placed in the eyepiece main seat 601 with the surface 8111 of the first lens 811 facing the eye side as the receiving surface.

[0126] The first spacer 602 is placed with the image-facing surface 8122 of the second lens 812. The eye-facing surface 8211 of the third lens 821 serves as a contact surface with the first spacer 602. The length of the first spacer 602 is controlled to ensure the spacing between the second lens 812 and the third lens 821 on the optical axis.

[0127] The image-facing surface 8212 of the third lens 821 is placed in the second spacer 603. The eye-facing surface 8221 of the fourth lens 822 serves as a contact surface with the second spacer 603. The length of the second spacer 603 is controlled to ensure the spacing between the third lens 821 and the fourth lens 822 on the optical axis.

[0128] The image-facing surface 8222 of the fourth lens 822 is placed in the third spacer 604. The eye-facing surface 8311 of the fifth lens 831 serves as a contact surface with the third spacer 604. The length of the third spacer 604 is controlled to ensure the spacing between the fourth lens 822 and the fifth lens 831 on the optical axis.

[0129] The surface 8311 of the fifth lens 831 facing the image side is glued to the surface 8321 of the sixth lens 832 facing the eye side, and the pressure ring 605 is placed with the surface 6322 of the sixth lens 632 facing the image side as the receiving surface.

[0130] Specifically, in the eyepiece optical system of the first embodiment, the field number is 27 mm.

[0131] The first lens 811 has a focal length f11 of −49.87, a refractive index N11 of 1.95, an Abbe number V11 of 17.9, and a thickness T11 of 5.08.

[0132] The second lens 812 has a focal length f12 of 59.14, a refractive index N12 of 1.61, an Abbe number V12 of 58.9, and a thickness T12 of 7.85.

[0133] The third lens 821 has a focal length f21 of 89.03, a refractive index N21 of 1.95, an Abbe number V21 of 17.9, and a thickness T21 of 5.51.

[0134] The fourth lens 822 has a focal length f22 of 54.38, a refractive index N22 of 1.73, an Abbe number V22 of 54.7, and a thickness T22 of 8.73.

[0135] The fifth lens 831 has a focal length f31 of 42.74, a refractive index N31 of 1.50, an Abbe number V31 of 81.6, and a thickness T31 of 11.57.

[0136] The sixth lens 832 has a focal length f32 of −36.61, a refractive index N32 of 1.95, an Abbe number V32 of 17.9, and a thickness T32 of 3.00.

[0137] Other optical parameters of the eyepiece optical system are shown in Table 1.

[0138] Table 1

[0139] Radius of curvature Thickness / spacing Refractive index Abbe number focal length aperture unlimited 22.93 First lens First side -30.04 5.08 1.95 17.9 -49.87 Side 2 -87.59 0.01 Second lens First side -87.59 7.85 1.61 58.9 59.14 Side 2 -26.46 0.20 The third lens First side -104.97 5.51 1.95 17.9 89.03 Side 2 -48.27 0.20 Fourth lens First side 103.54 8.73 1.73 54.7 54.38 Side 2 -62.40 0.20 Fifth lens First side 37.34 11.57 1.50 81.6 42.74 Side 2 -44.49 0.01 Sixth lens First side -44.49 3.00 1.95 17.9 -36.61 Side 2 171.38 16.47 Image plane unlimited 0.02

[0140] As can be seen from the above, in the eyepiece EY01 of this embodiment, f is the focal length of the eyepiece optical system, i.e., f is 25.01; NA is the image-side numerical aperture of the eyepiece optical system, i.e., NA is 0.04; and D0 is the distance from the stop 700 to the optical axis of the lens surface of the eyepiece optical system closest to the eye, i.e., D0 is 22.93. Therefore, |f*NA / D0| is 0.044. This ensures that the eyepiece has a large numerical aperture, high resolution, and a large field of view.

[0141] The focal length of the first lens group 81 is the combined focal length of the first lens 811 and the second lens 812, that is, f1 is 1928.04; the focal length of the second lens group 82 is the combined focal length of the third lens 821 to the fourth lens 822, that is, f2 is 34.03; the focal length of the third lens group 83 is the combined focal length of the fifth lens 831 to the sixth lens 832, that is, f3 is -1110.43. The focal length f of the entire optical system is 25.01. Then |f / f1| is 0.01, |f / f2| is 0.73, |f / f3| is 0.02, |f2 / f1| is 0.02, |f2 / f3| is 0.03, |f11 / f1| is 0.03, |f12 / f1| is 0.03, |f21 / f2| is 2.62, |f22 / f2| is 1.60, |f31 / f3| is 0.04, |f32 / f3| is 0.03.

[0142] In this embodiment 1, the thickness T1 of the first lens group 81 is 13.14, the thickness T2 of the second lens group 82 is 14.64, and the thickness T3 of the third lens group 83 is 14.58; T1 / T2 is 0.90, T1 / T3 is 0.90, T11 / T1 is 0.39, T12 / T1 is 0.60, T21 / T2 is 0.38, T22 / T2 is 0.60, T31 / T3 is 0.79, and T32 / T3 is 0.21.

[0143] like Figures 2 to 5 As shown, various aberration diagrams and MTF performance diagrams of the eyepiece optical system of Example 1 are shown. The various aberrations presented therein represent the resolution capability. When the aberrations are relatively small, better quality images can be observed.

[0144] Specifically, Figure 2 This is a spherical aberration diagram of the eyepiece optical system according to the first embodiment of the present invention, as shown in FIG. Figure 2 As shown in the figure, the horizontal axis is the spherical aberration, in mm, and the vertical axis is the image height, in mm. The solid line represents the d-line, the dashed line represents the C-line, the single-dash line represents the F-line, and the double-dash line represents the g-line. The spherical aberration of this eyepiece optical system is controlled within ±0.01 mm, resulting in optimal center resolution.

[0145] Figure 3 This is a field curvature diagram of the eyepiece optical system according to the first embodiment of the present invention, as shown in FIG. Figure 3 As shown in the figure, the abscissa represents the object plane movement (in mm), and the ordinate represents the image height (in mm). The solid line represents the sagittal direction relative to each wavelength, and the dashed line represents the meridian direction relative to each wavelength. The distribution of field curvature indicates that the field curvature of this eyepiece optical system is controlled within ±1.0 mm, resulting in optimal center resolution.

[0146] Figure 4This is a distortion diagram of the eyepiece optical system of Example 1 of the present invention, as shown in FIG. Figure 4 As shown, the horizontal axis is the distortion amount, unit is %, and the vertical axis is the image height, unit is mm. From the distribution of distortion, it can be seen that the distortion of the eyepiece optical system is controlled within ±0.5%, making the center resolution of the eyepiece optical system optimal.

[0147] Figure 5 This is a diagram of the MTF (Modulation Transfer Function) of the eyepiece optical system according to the first embodiment of the present invention. Figure 5 As shown in the figure, the horizontal axis is the spatial frequency (in cycles / mm), and the vertical axis is the modulation (MTF). The solid line represents the modulation (MTF) of the central image plane of the eyepiece optical system, and the dotted line represents the diffraction limit.

[0148] Example 2

[0149] like Figure 6 As shown, the structure of the eyepiece EY02 in the second embodiment is similar to that in the first embodiment, and also includes a first lens group 81, a second lens group 82, and a third lens group 83. The first lens group 81 includes: a first lens 811 and a second lens 812, the second lens group 82 includes: a third lens 821 and a fourth lens 822, and the third lens group 83 includes: a fifth lens 831 and a sixth lens 832. The distance between the sixth lens and the image plane is different, and the optical parameters of the lenses are slightly different from those in the first embodiment.

[0150] Specifically, in the eyepiece optical system of the second embodiment, the field number is 27 mm.

[0151] The first lens 811 has a focal length f11 of -37.70, a refractive index N11 of 1.95, an Abbe number V11 of 17.9, and a thickness T11 of 3.00.

[0152] The second lens 812 has a focal length f12 of 38.37, a refractive index N12 of 1.65, an Abbe number V12 of 58.4, and a thickness T12 of 11.64.

[0153] The third lens 821 has a focal length f21 of 64.35, a refractive index N21 of 1.95, an Abbe number V21 of 17.9, and a thickness T21 of 7.67.

[0154] The fourth lens 822 has a focal length f22 of 61.97, a refractive index N22 of 1.73, an Abbe number V22 of 54.7, and a thickness T22 of 9.39.

[0155] The fifth lens 831 has a focal length f31 of 40.62, a refractive index N31 of 1.50, an Abbe number V31 of 81.6, and a thickness T31 of 12.55.

[0156] The sixth lens 832 has a focal length f32 of −20.59, a refractive index N32 of 1.95, an Abbe number V32 of 17.9, and a thickness T32 of 3.00.

[0157] Other optical parameters of the eyepiece optical system are shown in Table 2.

[0158] Table 2

[0159] Radius of curvature Thickness / spacing Refractive index Abbe number focal length aperture unlimited 28.83 First lens First side -53.80 3.00 1.95 17.9 -37.70 Side 2 113.01 0.01 Second lens First side 113.01 11.64 1.65 58.4 38.37 Side 2 -30.95 0.20 The third lens First side 204.08 7.67 1.95 17.9 64.35 Side 2 -86.75 0.20 Fourth lens First side 74.24 9.39 1.73 54.7 61.97 Side 2 -110.52 0.20 Fifth lens First side 28.67 12.55 1.50 81.6 40.62 Side 2 -58.86 0.01 Sixth lens First side -58.86 3.00 1.95 17.9 -20.59 Side 2 30.42 9.79 Image plane unlimited -0.03

[0160] As can be seen from the above, in the eyepiece EY02 of this embodiment, f is the focal length of the eyepiece optical system, i.e., f is 25.00; NA is the image-side numerical aperture of the eyepiece optical system, i.e., NA is 0.04; and D0 is the distance from the stop 700 to the optical axis of the lens surface of the eyepiece optical system closest to the eye, i.e., D0 is 28.83. Therefore, |f*NA / D0| is 0.035. This ensures a large numerical aperture, high resolution, and a wide field of view.

[0161] The focal length of the first lens group 81 is the combined focal length of the first lens 811 and the second lens 812, that is, f1 is 238.16; the focal length of the second lens group 82 is the combined focal length of the third lens 821 to the fourth lens 822, that is, f2 is 32.50; the focal length of the third lens group 83 is the combined focal length of the fifth lens 831 to the sixth lens 832, that is, f3 is -63.75, and the focal length f of the entire optical system is 25.00. Then |f / f1| is 0.10, |f / f2| is 0.77, |f / f3| is 0.39, |f2 / f1| is 0.39, |f2 / f3| is 0.50, |f11 / f1| is 0.16, |f12 / f1| is 0.16, |f21 / f2| is 1.98, |f22 / f2| is 1.91, |f31 / f3| is 0.64, |f32 / f3| is 0.32.

[0162] In this second embodiment, the thickness T1 of the first lens group 81 is 14.85, the thickness T2 of the second lens group 82 is 17.47, and the thickness T3 of the third lens group 83 is 15.56; T1 / T2 is 0.85, T1 / T3 is 0.95, T11 / T1 is 0.20, T12 / T1 is 0.78, T21 / T2 is 0.44, T22 / T2 is 0.54, T31 / T3 is 0.81, and T32 / T3 is 0.19.

[0163] like Figures 7 to 10 The diagrams of various aberrations and MTF performance of the eyepiece optical system of the second embodiment show the various aberrations presented, which demonstrate the resolution capability. When the aberrations are relatively small, better quality images can be observed.

[0164] Specifically, Figure 7 This is a spherical aberration diagram of the eyepiece optical system according to the second embodiment of the present invention, as shown in FIG. Figure 7 As shown in the figure, the horizontal axis is the spherical aberration, in mm, and the vertical axis is the image height, in mm. The solid line represents the d-line, the dashed line represents the C-line, the single-dash line represents the F-line, and the double-dash line represents the g-line. The spherical aberration of this eyepiece optical system is controlled within ±0.01 mm, resulting in optimal center resolution.

[0165] Figure 8 This is a field curvature diagram of the eyepiece optical system of the second embodiment of the present invention, as shown in FIG. Figure 8 As shown, the abscissa represents the object plane movement (in mm), and the ordinate represents the image height (in mm). The solid line represents the sagittal direction relative to each wavelength, and the dashed line represents the meridian direction relative to each wavelength. The distribution of field curvature indicates that the field curvature of this eyepiece optical system is controlled within ±1.0 mm, resulting in optimal center resolution.

[0166] Figure 9 This is a distortion diagram of the eyepiece optical system of the second embodiment of the present invention, as shown in FIG. Figure 9 As shown, the horizontal axis is the distortion amount, unit is %, and the vertical axis is the image height, unit is mm. From the distribution of distortion, it can be seen that the distortion of the eyepiece optical system is controlled within ±0.5%, making the center resolution of the eyepiece optical system optimal.

[0167] Figure 10 This is the MTF (Modulation Transfer Function) diagram of the eyepiece optical system of Example 2 of the present invention, as shown in FIG. Figure 10 As shown in the figure, the horizontal axis is the spatial frequency (in cycles / mm), and the vertical axis is the modulation (MTF). The solid line represents the modulation (MTF) of the central image plane of the eyepiece optical system, and the dotted line represents the diffraction limit.

[0168] Example 3

[0169] like Figure 11 As shown, the structure of the eyepiece EY03 in Example 3 is similar to that of Example 1, including a first lens group 81 comprising a first lens 811 and a second lens 812, a second lens group 82 comprising a third lens 821 and a fourth lens 822, and a third lens group 83 comprising a fifth lens 831 and a sixth lens 832. Example 3 has a larger NA of 0.05, and the optical parameters of the lenses are slightly different from those of Example 1.

[0170] Specifically, in the eyepiece optical system of the third embodiment, the field number is 27 mm.

[0171] The first lens 811 has a focal length f11 of -22.89, a refractive index N11 of 1.92, an Abbe number V11 of 17.9, and a thickness T11 of 20.9.

[0172] The second lens 812 has a focal length f12 of 31.34, a refractive index N12 of 1.73, an Abbe number V12 of 58.4, and a thickness T12 of 54.7.

[0173] The third lens 821 has a focal length f21 of 63.33, a refractive index N21 of 1.95, an Abbe number V21 of 17.9, and a thickness T21 of 17.9.

[0174] The fourth lens 822 has a focal length f22 of 61.88, a refractive index N22 of 1.73, an Abbe number V22 of 54.7, and a thickness T22 of 54.7.

[0175] The fifth lens 831 has a focal length f31 of 41.27, a refractive index N31 of 1.50, an Abbe number V31 of 81.6, and a thickness T31 of 81.6.

[0176] The sixth lens 832 has a focal length f32 of −19.43, a refractive index N32 of 1.95, an Abbe number V32 of 17.9, and a thickness T32 of 17.9.

[0177] Other optical parameters of the eyepiece optical system are shown in Table 3.

[0178] Table 3

[0179] Radius of curvature Thickness / spacing Refractive index Abbe number focal length aperture unlimited 26.77 First lens First side -28.56 3.20 1.92 20.9 -22.89 Side 2 89.28 0.01 Second lens First side 89.28 13.49 1.73 54.7 31.34 Side 2 -28.91 0.20 The third lens First side 599.57 8.67 1.95 17.9 63.33 Side 2 -67.05 0.20 Fourth lens First side 76.11 10.70 1.73 54.7 61.88 Side 2 -105.33 0.20 Fifth lens First side 28.31 13.71 1.50 81.6 41.27 Side 2 -63.09 0.01 Sixth lens First side -63.09 4.27 1.95 17.9 -19.43 Side 2 27.30 11.11 Image plane unlimited 0.02

[0180] As can be seen from the above, in the eyepiece optical system EY03 of this embodiment, f is the focal length of the eyepiece optical system, i.e., f is 25.02; NA is the image-side numerical aperture of the eyepiece optical system, i.e., NA is 0.05; and D0 is the distance from the aperture 700 to the optical axis of the lens surface of the eyepiece optical system closest to the eye, i.e., D0 is 26.77. Therefore, |f*NA / D0| is 0.047. This ensures that the system has a large numerical aperture, high resolution, and a large field of view.

[0181] The focal length of the first lens group 81 is the combined focal length of the first lens 811 and the second lens 812, that is, f1 is -699.63; the focal length of the second lens group 82 is the combined focal length of the third lens 821 to the fourth lens 822, that is, f2 is 32.15; the focal length of the third lens group 83 is the combined focal length of the fifth lens 831 to the sixth lens 832, that is, f3 is -58.57, and the focal length f of the entire optical system is 25.02. Then |f / f1| is 0.04, |f / f2| is 0.78, |f / f3| is 0.43, |f2 / f1| is 0.05, |f2 / f3| is 0.55, |f11 / f1| is 0.03, |f12 / f1| is 0.05, |f21 / f2| is 1.97, |f22 / f2| is 1.93, |f31 / f3| is 0.71, and |f32 / f3| is 0.33.

[0182] In this third embodiment, the thickness T1 of the first lens group 81 is 16.90, the thickness T2 of the second lens group 82 is 19.78, and the thickness T3 of the third lens group 83 is 17.99; T1 / T2 is 0.85, T1 / T3 is 0.94, T11 / T1 is 0.19, T12 / T1 is 0.80, T21 / T2 is 0.44, T22 / T2 is 0.54, T31 / T3 is 0.76, and T32 / T3 is 0.24.

[0183] Figures 12 to 15 The diagrams of various aberrations and MTF performance of the eyepiece optical system of Example 3 are shown. The various aberrations presented therein demonstrate the resolution capability. When the aberrations are relatively small, better quality images can be observed.

[0184] Specifically, Figure 12 This is a spherical aberration diagram of the eyepiece optical system of embodiment 3 of the present invention, as shown in FIG. Figure 12 As shown in the figure, the horizontal axis is the spherical aberration, in mm, and the vertical axis is the image height, in mm. The solid line represents the d-line, the dashed line represents the C-line, the single-dash line represents the F-line, and the double-dash line represents the g-line. The spherical aberration of this eyepiece optical system is controlled within ±0.01 mm, resulting in optimal center resolution.

[0185] Figure 13 This is a field curvature diagram of the eyepiece optical system of embodiment 3 of the present invention, as shown in FIG. Figure 13 As shown, the abscissa represents the object plane movement (in mm), and the ordinate represents the image height (in mm). The solid line represents the sagittal direction relative to each wavelength, and the dashed line represents the meridian direction relative to each wavelength. The distribution of field curvature indicates that the field curvature of this eyepiece optical system is controlled within ±1.0 mm, resulting in optimal center resolution.

[0186] Figure 14This is a distortion diagram of the eyepiece optical system of Example 3 of the present invention, as shown in FIG. Figure 14 As shown, the horizontal axis is the distortion amount, unit is %, and the vertical axis is the image height, unit is mm. From the distribution of distortion, it can be seen that the distortion of the eyepiece optical system is controlled within ±0.5%, making the center resolution of the eyepiece optical system optimal.

[0187] Figure 15 This is the MTF (Modulation Transfer Function) diagram of the eyepiece optical system of Example 3 of the present invention, as shown in FIG. Figure 15 As shown in the figure, the horizontal axis is the spatial frequency (in cycles / mm), and the vertical axis is the modulation (MTF). The solid line represents the modulation (MTF) of the central image plane of the eyepiece optical system, and the dotted line represents the diffraction limit.

[0188] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A low-distortion ultra-wide-angle eyepiece, characterized in that: include: An aperture, a first lens group, a second lens group, and a third lens group are coaxially arranged in sequence along the optical axis from the eye side to the image side; The first lens group has positive or negative refractive power; the second lens group has positive refractive power; the third lens group has negative refractive power; and the low-distortion ultra-wide-angle eyepiece satisfies the following conditional formula: 0.01<|f*NA / D0|<0.5; 0.01<|f / f1|<0.5; 0.50<|f / f2|<0.9; 0.01<|f / f3|<0.7; 0.01<|f2 / f1|<0.5; 0.02<|f2 / f3|<0.7; Where f is the focal length of the eyepiece; NA is the image-side numerical aperture of the eyepiece; D0 is the distance from the aperture to the optical axis of the lens surface closest to the eye; f1 is the focal length of the first lens group; f2 is the focal length of the second lens group; f3 is the focal length of the third lens group; The first lens group includes a first lens having negative refractive power and a second lens having positive refractive power, wherein a surface of the first lens facing the image side is cemented to a surface of the second lens facing the eye side; the second lens group includes a third lens having positive refractive power and a fourth lens having positive refractive power; the third lens group includes a fifth lens having positive refractive power and a sixth lens having negative refractive power, wherein a surface of the fifth lens facing the image side is cemented to a surface of the sixth lens facing the eye side; The first lens group, the second lens group and the third lens group satisfy the following conditional formula: 0.01<|f11 / f1|<0.50; 0.02<|f12 / f1|<0.60; 1.00<|f21 / f2|<5.00; 1.00<|f22 / f2|<5.00; 0.01<|f31 / f3|<0.90; 0.01<|f32 / f3|<0.50; Among them, f11 is the focal length of the first lens; f12 is the focal length of the second lens; f21 is the focal length of the third lens; f22 is the focal length of the fourth lens; f31 is the focal length of the fifth lens; and f32 is the focal length of the sixth lens.

2. The low-distortion ultra-wide-angle eyepiece according to claim 1, characterized in that: The first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens satisfy the following conditional formula: N11≥1.85； N12≥1.55； N21≥1.85； N22≤1.65； N31≤1.75； N32≥1.85； Among them, N11 is the refractive index of the first lens; N12 is the refractive index of the second lens; N21 is the refractive index of the third lens; N22 is the refractive index of the fourth lens; N31 is the refractive index of the fifth lens; N32 is the refractive index of the sixth lens.

3. The low-distortion ultra-wide-angle eyepiece according to claim 1, wherein: The first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens satisfy the following conditional formula: V11≥17.5； V12≤70.5； V21≥17.5； V22≤65.5； V31≥55.5； V32≥17.5； Among them, V11 is the Abbe number of the first lens; V12 is the Abbe number of the second lens; V21 is the Abbe number of the third lens; V22 is the Abbe number of the fourth lens; V31 is the Abbe number of the fifth lens; V32 is the Abbe number of the sixth lens.

4. The low-distortion ultra-wide-angle eyepiece according to claim 1, wherein: The first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens satisfy the following conditional formula: 0.50 <T1 / T2<0.95; 0.50 <T1 / T3<0.98; 0.10 <T11 / T1<0.60; 0.30 <T12 / T1<1.10; 0.10 <T21 / T2<0.80; 0.30 <T22 / T2<0.80; 0.10 <T31 / T3<0.90; 0.10 <T32 / T3<0.50; Wherein, T1 is the length of the first lens group on the optical axis; T2 is the length of the second lens group on the optical axis; T3 is the length of the third lens group on the optical axis; T11 is the thickness of the first lens on the optical axis; T12 is the thickness of the second lens on the optical axis; T21 is the thickness of the third lens on the optical axis; T22 is the thickness of the fourth lens on the optical axis; T31 is the thickness of the fifth lens on the optical axis; T32 is the thickness of the sixth lens on the optical axis.

5. The low-distortion ultra-wide-angle eyepiece according to claim 1, wherein: Also includes: An eyepiece main body and a first spacer; the surface of the first lens facing the eye is placed in the eyepiece main body; The surface of the second lens facing the image side is placed in a first spacer; the surface of the third lens facing the eye side contacts the first spacer; and the second lens and the third lens are spaced apart on the optical axis.

6. The low-distortion ultra-wide-angle eyepiece according to claim 1, wherein: Also includes: a second spacer; the surface of the third lens facing the image side is placed in the second spacer; the surface of the fourth lens facing the eye side contacts the second spacer; the third lens and the fourth lens are spaced apart on the optical axis.

7. The low-distortion ultra-wide-angle eyepiece according to claim 1, wherein: Also includes: a third spacer; the surface of the fourth lens facing the image side is placed in the third spacer; the surface of the fifth lens facing the eye side contacts the third spacer; the fourth lens and the fifth lens are spaced apart on the optical axis.

8. The low-distortion ultra-wide-angle eyepiece according to claim 1, wherein: Also includes: A pressure ring is placed on the surface of the sixth lens facing the image side.

Images