A catadioptric magnifier optical system

Abstract

The present invention discloses a catadioptric magnifier optical system. This structural form adopts a combination of refraction and reflection to achieve optical magnification. It includes a first lens, a primary reflector, an intermediate lens group, a secondary reflector and a rear group in sequence along the optical path. The magnifier optical system has two intermediate image planes both located inside the system. The system can achieve a magnification ratio of 3 to 8 times and is widely applicable in the visible light to infrared band. The entire optical system of the present invention has the advantages of compact structure, good processability, and large magnification. Compared with the purely refractive optical magnification structural form, the present invention adopts a catadioptric structural form for optical design. There are two lenses in the middle of the optical system that pass light twice in the optical path, which improves the utilization rate of optical elements, thereby effectively reducing the number of lenses and simplifying the optical system. The secondary mirror adopts an aspheric surface type, which better corrects the aberration of the off-axis field of view. The design result has excellent imaging quality.

Description

Technical Field

[0001] The invention relates to a magnifier, in particular to a catadioptric magnifier optical system. Background Art

[0002] Whether in the military or civilian fields, when there is a need to observe distant targets, observation and aiming equipment can be equipped with a magnifying lens, using optical magnification to achieve longer-range observation and aiming. The magnifying lens is a telescope in its optical principle. Common telescope structures include refractive, reflective, and catadioptric types. Traditional telescopes are afocal optical systems that receive and emit parallel light and are designed for the human eye. However, today's common telescope designs are designed for detection devices, and the optical system is a focal system. The optical principle of the magnifying lens described in the present invention is the same as that of an afocal telescope.

[0003] Patents CN212083799U, "A magnifier adapted for wide-angle high-magnification zoom lenses," and CN203732794U, "A magnifier for wide-angle high-magnification zoom lenses," use a purely refractive structural design to design magnifiers adapted for wide-angle zoom lenses. Similarly, patent CN215769174U, "A magnifier for a telecentric optical system," also uses a purely refractive design to design a magnification-adjustable magnification magnifier. Patent CN206788457U, "Night vision device," describes a night vision optical system that cascades multiple magnifiers, which also uses a purely refractive structural design. Patent CN113655605A, "A magnifier, optical system, and imaging device," designs a purely refractive magnifier. In summary, the magnifiers covered by domestic patents are all designed with a purely refractive structural design.

[0004] Refracting telescopes are relatively simple in structure and easy to assemble and adjust. However, at higher magnifications, their axial dimensions are generally longer (for example, patent CN113655605A has a total length of up to 280mm) and they often have larger lenses (for example, patent CN212083799U). Common reflecting telescopes, mostly used in astronomical telescopes, are focal systems. They are large in size and suffer from significant central obscuration. Therefore, using a purely refractive magnification multiplier requires many lenses and is heavy at higher magnifications. Reflecting telescopes, however, are rarely used due to their large size and significant central obscuration. Summary of the Invention

[0005] In view of the defects of common magnifier optical systems, the present invention adopts a catadioptric optical system to design the magnifier. While obtaining a larger magnification, the axial size of the optical system is compressed, the center of gravity position of the magnifier is optimized, and the comfort of use is improved; the center obstruction of the optical system is reduced, the energy collection effect of the system is ensured, and good imaging quality is achieved.

[0006] A catadioptric magnifier optical system comprises, in sequence along the optical path, a first lens, a primary reflector, an intermediate lens group, a secondary reflector, and a rear lens group; the catadioptric magnifier optical system has two intermediate image planes, both of which are located inside the system; the catadioptric magnifier optical system can be used in the visible light and infrared bands.

[0007] Furthermore, the first lens is the first optical element of the system, and can be mainly used as a protective window of the system and as a mounting support plate for the intermediate lens group and the secondary reflector.

[0008] Furthermore, the primary reflector is the first optical element with optical power, and its surface is spherical, used for converging light, and its radius value satisfies: 70<r<120.

[0009] Furthermore, the intermediate lens group has positive optical power and passes light twice in the optical path, thereby improving the utilization rate of optical elements, thereby reducing the number of elements and simplifying the optical system.

[0010] Furthermore, the secondary reflector is aspherical, which optimizes and improves the imaging quality of the system's edge field of view. At the same time, its surface asphericity is low and it is easy to manufacture. Its normalized radius value satisfies: 15<r<35.

[0011] Furthermore, the rear group has positive optical power and is mainly used to correct some residual aberrations and form the second intermediate image of the system at infinity for use by the subsequent optical system.

[0012] Furthermore, the obstruction ratio of the optical system of the magnifier is defined as the effective aperture φ of the secondary mirror. 次 The effective aperture of the primary mirror φ 主 The ratio of φ 次 / φ 主 ≤0.35.

[0013] The beneficial effects of the present invention are:

[0014] The magnification ratio of the optical system of the magnifier of the present invention can reach 3 to 8 times. The overall structure is light and compact, which can meet the needs of optical magnification of optical systems in military and civilian fields. At the same time, the overall center of gravity is positioned backward during use, which has good comfort of use and can be widely used in products for video recording, observation and other purposes. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the optical system diagram of the 3x micro-light catadioptric magnifier;

[0016] Figure 2 This is the optical path diagram of the 0° field of view of the 3x low-light catadioptric magnifier optical system;

[0017] Figure 3 This is the optical path diagram of the 0.7 field of view of the 3x micro-light catadioptric magnifier optical system;

[0018] Figure 4 This is the full-field optical path diagram of the 3x low-light catadioptric magnifier optical system;

[0019] Figure 5 This is a spot diagram of the 3x micro-light catadioptric optical system;

[0020] Figure 6 This is the optical system diagram of the 5x low-light catadioptric magnifier;

[0021] Figure 7 This is the optical path diagram of the 0° field of view of the 5x micro-light catadioptric optical system;

[0022] Figure 8 This is the optical path diagram of the 0.7 field of view of the 5x low-light catadioptric optical system;

[0023] Figure 9 This is the full-field optical path diagram of the 5x low-light catadioptric optical system;

[0024] Figure 10 This is a spot diagram of the optical system of a 5x micro-light catadioptric extender;

[0025] Figure 11 This is the optical system diagram of the 8x low-light catadioptric magnifier;

[0026] Figure 12 This is a point diagram of the optical system of an 8x micro-light catadioptric extender. DETAILED DESCRIPTION

[0027] In order to make the purpose, content, and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below with reference to the accompanying drawings and examples.

[0028] The design concept of the catadioptric magnifier optical system of the present invention is slightly different from that of the traditional magnifier. First, while ensuring the magnification and imaging quality, the central obstruction is minimized as much as possible and the energy of the optical system is increased to obtain better observation effects.

[0029] Example 1

[0030] like Figure 1The optical system of Example 1 is shown. Following the optical path from object to eye, the system comprises: first lens L1, primary reflector M1, second lens L2, third lens L3, secondary reflector M2, fourth lens L4, and first cemented lens L5 (cemented with the fifth and sixth lenses). The effective aperture of the primary mirror is 40 mm, the effective aperture of the secondary mirror is 14 mm, and the obscuration ratio is 0.35.

[0031] Table 1 shows the optical system parameters of Example 1.

[0032] Table 1 Parameters of the 3x micro-light catadioptric magnifier optical system

[0033]

[0034] Example 2

[0035] like Figure 6 The optical system of Example 2 is shown. Following the optical path from object to eye, the system comprises: first lens L1, primary reflector M1, first cemented lens L2 (cemented with second and third lenses), fourth lens L3, secondary reflector M2, fifth lens L4, and second cemented lens L5 (cemented with sixth and seventh lenses). The effective aperture of the primary mirror is 64, the effective aperture of the secondary mirror is 16.1, and the obscuration ratio is 0.25.

[0036] Table 2 shows the optical system parameters of Example 2.

[0037] Table 2 Optical system parameters of the 5x micro-light catadioptric magnifier

[0038]

[0039] Example 3

[0040] like Figure 11 The optical system of Example 3 is shown. Following the optical path from the object side to the eye side, the system comprises: first lens L1, primary reflector M1, first cemented lens L2 (cemented with the second, third, and fourth lenses), fifth lens L3, secondary reflector M2, sixth lens L4, and second cemented lens L5 (cemented with the seventh and eighth lenses). The effective aperture of the primary mirror is 100, the effective aperture of the secondary mirror is 22.1, and the obscuration ratio is 0.22.

[0041] Table 3 shows the optical system parameters of Example 3.

[0042] Table 3 Parameters of the optical system of the 8x micro-light catadioptric magnifier

[0043]

[0044]

[0045] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A catadioptric magnifier optical system, characterized by: The optical path includes, in order, a first lens, a primary reflector, an intermediate lens group, a secondary reflector, and a rear lens group. The light beam passes through the first lens to the primary reflector, is reflected by the primary reflector, passes through the intermediate lens group to the secondary reflector, is reflected by the secondary reflector again, passes through the intermediate lens group, and finally passes through the rear lens group to form an image. The optical system of the magnifier has two intermediate image planes, both located inside the system. The first lens is a parallel flat plate; The primary reflector is a spherical surface, and its radius r1 satisfies: 70mm<r1<120mm; The intermediate lens group has positive optical power and passes light twice in the optical path; The secondary reflector is an aspheric surface, and its normalized radius value r2 satisfies: 15mm<r2<35mm; The rear group has positive optical power; The obscuration ratio of the magnifier optical system is defined as the effective aperture φ of the secondary reflector. 次 The effective aperture of the primary reflector φ 主 The ratio of φ 次 / φ 主 ≤0.35; The magnification of the magnifying mirror optical system is 3 to 8 times.

2. The catadioptric magnifier optical system according to claim 1, wherein: The magnifier optical system is used in the visible light and infrared bands.

3. The catadioptric magnifier optical system according to any one of claims 1 to 2, characterized in that: The first lens serves as a protective window of the system and as a mounting support plate for the intermediate lens group and the secondary reflector.

4. The catadioptric magnifier optical system according to any one of claims 1 to 2, characterized in that: The primary reflector is used to converge light.

5. The catadioptric magnifier optical system according to any one of claims 1 to 2, characterized in that: The secondary reflector is used to improve the imaging quality of the system's peripheral field of view.

6. The catadioptric magnifier optical system according to any one of claims 1 to 2, characterized in that: The rear group is used to correct some of the remaining aberrations and to form the second intermediate image of the system at infinity for use by the subsequent optical system.

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