Long eye relief lightweight eyepiece optical system

Abstract

The application discloses a long-out-pupil lightweight eyepiece optical system, which comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens arranged in sequence along an optical axis from an eye to a micro display screen; the first lens is a glass positive lens; the second lens, the third lens and the fifth lens are all plastic aspheric lenses; and the fourth lens is a glass negative lens. The optical system comprises five lenses in total, has a simple structure and is easy to make a structure lens barrel; the lens collocation is reasonable, the eyepiece exit pupil distance is greater than 60 mm, the comfort of observation is significantly improved, the optical system has good environmental adaptability, and the disadvantages of high weight and high cost of traditional observation eyepieces are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to an optical system, in particular to a long exit pupil lightweight eyepiece optical system. BACKGROUND

[0002] With the continuous development of individual equipment, head-mounted glasses, scopes and the like are also expanding in the direction of informatization, intelligentization, lightweight, long distance, large field of view and the like. In particular, in special environmental conditions such as a battlefield, soldiers need to wear gas masks or goggles to observe and guard the target scene. In addition, heavy gun impact is large, and a sufficient safety distance (more than 40 mm) needs to be left between the eyepiece and the human eye to prevent the impact from injuring the eye when shooting.

[0003] Generally, the exit pupil distance of conventional military observation eyepieces is required to be more than 25 mm, and the exit pupil distance of light-type scopes is required to be more than 30 mm; however, the actual requirement for the exit pupil distance is greatly increased in the use of equipment such as goggles and gas masks on the battlefield. However, in the prior art, the exit pupil distance or aberration of the designed eyepiece is mostly difficult to meet the current new situation requirements. The existing 10x exit pupil distance 40mm eyepiece can only be matched with a 0.5 eyepiece, and after wearing a gas mask, the shooting is very limited, and the weight is relatively heavy, which is very unfavorable for head-wearing or portability. SUMMARY

[0004] In order to solve the above technical problems, the present application provides a long exit pupil lightweight eyepiece optical system.

[0005] In order to solve the above technical problems, the present application adopts the technical scheme of: a long exit pupil lightweight eyepiece optical system, comprising a first lens, a second lens, a third lens, a fourth lens and a fifth lens arranged in order along the optical axis from the eye to the micro display screen.

[0006] The first lens is a glass positive lens, the second lens, the third lens and the fifth lens are all plastic aspherical lenses, and the fourth lens is a glass negative lens.

[0007] Further, the first lens is a flat convex glass positive lens, the second lens is a double convex plastic positive lens, the third lens is a convex-concave meniscus plastic positive lens, the fourth lens is a convex-concave meniscus glass positive lens, and the fifth lens is a double convex plastic positive lens.

[0008] Further, the ratio of the focal length of the first lens to the focal length of the entire lens satisfies the following relationship:

[0009] 3 < |f1 / f| < 5

[0010] Wherein, f is the focal length of the entire lens, and f1 is the focal length of the first lens.

[0011] Further, the second lens, the third lens and the fifth lens have a density of not greater than 1.25 g / cm 3 Plastic material.

[0012] Further, the plastic material is any one of PMMA, E48R, K26R, F52R, APL5014DP, PAL5514ML and ep5000.

[0013] Further, the long-eyepupil lightweight eyepiece optical system has an overall focal length of 20-25 mm, an eyepupil diameter of 5-7 mm and an eyepupil distance of 50-65 mm.

[0014] The application discloses a long-eyepupil lightweight eyepiece optical system. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The application discloses a long-eyepupil lightweight eyepiece optical system.

[0016] Figure 2 The application discloses a long-eyepupil lightweight eyepiece optical system.

[0017] Figure 3 The application discloses a long-eyepupil lightweight eyepiece optical system.

[0018] In the figure, 1 represents an eyepupil, 2 represents a first lens, 3 represents a second lens, 4 represents a third lens, 5 represents a fourth lens, 6 represents a fifth lens and 7 represents a micro display screen. DETAILED DESCRIPTION

[0019] The application will be further described in detail below in combination with the drawings and specific embodiments.

[0020] In order to solve the problem that the existing long-eyepupil eyepiece cannot meet the requirements of military eyepieces under the new situation in terms of eyepupil distance, weight and effect, the application provides a long-eyepupil lightweight eyepiece optical system. Figure 1 As shown in the figure, the optical system comprises a first lens 2, a second lens 3, a third lens 4, a fourth lens 5 and a fifth lens 6 which are sequentially arranged along an optical axis from an eye to a micro display screen 7 (i.e. Figure 1 from the eyepupil 1 in the figure).

[0021] The first lens 2 is a glass positive lens, the second lens 3, the third lens 4 and the fifth lens 6 are plastic aspheric lenses, and the fourth lens 5 is a glass negative lens.

[0022] Specifically, the first lens 2 is a flat-convex glass positive lens, the second lens 3 is a double-convex plastic positive lens, the third lens 4 is a convex-concave meniscus plastic positive lens, the fourth lens 5 is a convex-concave meniscus glass positive lens, and the fifth lens 6 is a double-convex plastic positive lens; thus, in combination with the micro display screen 7, a long-pupil lightweight eyepiece optical system of the application is formed, which has an overall focal length of 20-25 mm, an exit pupil diameter of 5-7 mm, and an exit pupil distance of up to 50-65 mm.

[0023] Preferably, the ratio of the focal length of the first lens 2 to the focal length of the entire lens satisfies the following relationship:

[0024] 3 < |f1 / f| < 5

[0025] wherein f is the focal length of the entire lens, and f1 is the focal length of the first lens.

[0026] The first lens 2 and the fourth lens 5 are made of glass, which improves the environmental adaptability of the eyepiece; the second lens 3, the third lens 4 and the fifth lens 6 are made of plastic, and the plastic material can be PMMA, E48R, K26R, F52R, APL5014DP, PAL5514ML, ep5000, etc., which have good optical properties and a density generally not greater than 1.25 g / cm 3 , which is significantly smaller than that of glass, thereby significantly reducing the weight of the eyepiece optical system and the batch molding cost of the plastic lens is much lower than that of the glass lens.

[0027]

EMBODIMENT

[0028] The long-pupil lightweight eyepiece optical system disclosed in the embodiment has an overall focal length of 25 mm, a magnification of 10x, an exit pupil diameter of 5 mm, an exit pupil distance of up to 63 mm, an optical total length of 41.2 mm, and a weight of only 44 g; the first lens f1 has a value of 82.4 mm; the long-pupil lightweight eyepiece optical system of the embodiment comprises five lenses and has ten surfaces, which are sequentially numbered 2 to 11 in order of the first lens to the fifth lens, and the diaphragm is numbered 1; the corresponding curvature radii, lens center thicknesses, lens center distances and lens refractive indices satisfy the conditions shown in the following table:

[0029]

[0030] In the table, the surfaces with the surface numbers of 4, 6 and 10 are aspherical surfaces, and the aspherical lens satisfies the following formula:

[0031]

[0032] Where c = 1 / R, R is the radius of curvature of the aspherical surface, r is the number from 0 to the maximum effective aperture of the lens, k is the quadratic surface parameter, A is the 4th order coefficient, B is the 6th order coefficient, C is the 8th order coefficient, and so on.

[0033] The specific parameters for aspherical surface types are shown in the table below:

[0034] Surface No. k A B C 4 -1.665 0 0 0 6 -0.0759 0 0 0 10 0 2.53e-007 -8.03e-008 -2.67e-010

[0035] Both sides of all plastic lenses can be set to aspherical, and can be appropriately adjusted according to the system parameters, the material of the plastic lens, and the difficulty of processing.

[0036] Furthermore, Figure 2 The MTF resolution curve of the lightweight eyepiece optics system with long exit pupil in this embodiment is shown, where the horizontal axis represents the spatial frequency of line pairs / mm, and the vertical axis represents the MTF value. From Figure 2 As can be seen, this optical system exhibits good contrast at a spatial frequency of 30 lp / mm in the central region, meeting the requirements for human eye observation.

[0037] The optical distortion diagram of the lightweight eyepiece optical system with long exit pupil in this embodiment is as follows: Figure 3 As shown, from Figure 3 As can be seen, its maximum distortion rate is only 2.3%.

[0038] Therefore, the lightweight eyepiece optical system with long exit pupil disclosed in this invention has the following technical advantages compared with the prior art:

[0039] (1) The first lens is made of glass, which improves the environmental adaptability of the eyepiece.

[0040] (2) The second, third and fifth lenses are made of plastic lenses, which significantly reduces the weight of the eyepiece and the cost of mass molding is much lower than that of glass lenses.

[0041] (3) The eyepiece exit pupil distance of the present invention is greater than 60mm, which significantly improves the comfort of observation.

[0042] (4) The eyepiece of the present invention can support a micro display screen up to 0.6 inches, and the maximum distortion is only 2.3%, which significantly improves the fatigue of human eyes during long-term observation.

[0043] (5) The eyepiece optical back distance of the present invention is greater than 6mm, which can meet the adjustment of more than -6 diopters.

[0044] (6) The entire optical system uses only 5 lenses, and the structure is simple and easy to make the lens barrel.

[0045] The above embodiments are not a limitation of the present application, and the present application is not limited to the above examples. Changes, modifications, additions or replacements made by those skilled in the art within the technical scheme of the present application shall also fall within the protection scope of the present application.

Claims

1. A lightweight eyepiece optical system for extended eye relief, characterized by: The lens group of the long-pupil lightweight eyepiece optical system is composed of a first lens (2), a second lens (3), a third lens (4), a fourth lens (5) and a fifth lens (6) arranged in sequence along the optical axis from the eye to the micro display screen (7); The first lens (2) is a flat-convex glass positive lens, the second lens (3) is a double-convex plastic positive lens, the third lens (4) is a convex-concave meniscus plastic positive lens, the fourth lens (5) is a convex-concave meniscus glass positive lens, and the fifth lens (6) is a double-convex plastic positive lens; The ratio of the focal length of the first lens (2) to the focal length of the entire lens satisfies the following relationship: 3 < |f1 / f| < 5 Where f is the focal length of the entire lens, and f1 is the focal length of the first lens; In the order of the first lens (2) to the fifth lens (6), the ten surfaces of the lenses are numbered 2 to 11 in sequence, and the diaphragm is numbered 1; The curvature radii of the surfaces numbered 1-11 are infinite, infinite, -51.1, 36.26, -162.24, 22, 218.4, 79.23, 16.7, 18, and -54.62, respectively, in units of mm; The lens center distances of the surfaces numbered 1-11 are 63, 5.5, 0.3, 8.1, 0.3, 9.8, 0.3, 2.1, 1.02, 7.6, and 6.2, respectively, in units of mm; The refractive indices of the first lens (2) to the fifth lens (6) are 1.62, 1.49, 1.49, 1.94, and 1.49, respectively.

2. The long eye relief lightweight eyepiece optical system of claim 1, wherein: The second lens (3), the third lens (4), the fifth lens (6) adopt plastic material with density not greater than 1.25 g / cm 3 plastic material.

3. The long eye relief lightweight eyepiece optical system of any of claims 1-2, wherein: The long-pupil lightweight eyepiece optical system has an overall focal length of 20-25 mm, an exit pupil diameter of 5-7 mm, and an exit pupil distance of 50-65 mm.

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