1. A coaxial four-lens reflex tele optical system, comprising:

the primary mirror, the secondary mirror, the third mirror and the fourth mirror are coaxially arranged;

the primary mirror is symmetrically arranged relative to the three mirrors, the secondary mirror and the four mirrors are positioned on the same side of the primary mirror, and the four mirrors are positioned between the secondary mirror and the three mirrors; the primary mirror and the third mirror are high-order aspheric mirrors, and the secondary mirror and the fourth mirror are spherical mirrors;

a first central hole is formed in the center of the third mirror, and a second central hole is formed in the center of the fourth mirror;

the light rays are reflected by the primary mirror and the secondary mirror in sequence to obtain first reflected light, the first reflected light is incident to the three mirrors after passing through the second central hole, the light rays are reflected by the three mirrors to obtain second reflected light, and the second reflected light is reflected by the four mirrors, passes through the first central hole and then is converged and imaged to the focal plane.

2. The coaxial four-lens reflex tele optical system of claim 1, wherein the primary mirror is integrally formed with the three-lens.

3. The coaxial four-reflection long-focus optical system as claimed in claim 1, wherein the image space of the four mirrors is provided with a first plane folding mirror and a second plane folding mirror, and the light emitted from the first central hole is reflected by the first plane folding mirror and the second plane folding mirror in sequence and focused to form an image on a focal plane.

4. The coaxial four-lens reflex tele optical system according to claim 1, wherein an aperture stop of the optical system is provided on the primary mirror.

5. The coaxial four-lens reflex tele optical system of claim 1, wherein the vertex radius of curvature of the primary mirror ranges from-146.47 mm to-161.89 mm; the vertex curvature radius of the secondary mirror ranges from-1099.82 mm to-1215.59 mm; the vertex curvature radius of the three mirrors ranges from-39.77 mm to-43.96 mm; the vertex curvature radius of the four mirrors ranges from-31.89 mm to-35.25 mm.

6. A coaxial four-reflection tele optical system of claim 1, wherein the primary and tertiary mirrors are concave mirrors.

7. A telescopic objective optical bench comprising the coaxial four-lens reflex optical system according to any one of claims 1 to 6.

8. The telescopic objective optical bench of claim 7 further comprising a quadri-radial support on which the secondary mirror and the quadri-mirror are disposed.

9. The telescopic objective optical bench of claim 7 wherein the primary mirror and the three mirrors are co-substrate machined.

10. An optical device comprising the telescopic objective optical machine of any one of claims 7 to 9.

Background

The reflective far objective is a widely used optical lens, and has numerous application scenes in the fields of astronomy, military industry, national defense and aerospace optical remote sensing. The spherical Newton's reflection telescope developed in Newton in 1618 was the beginning of a reflective telescopic objective. In recent decades, the use of photoelectric imaging devices has put higher demands on the optical performance of telescopic objectives. The coaxial two-mirror system using a quadric surface is a relatively common telephoto reflective optical system. By adding the reflector and the aspheric surface item, the effective view field can be enlarged, the imaging quality can be improved,

in order to improve the imaging quality of the system, enlarge the field of view and inhibit stray light, a quadric surface aspheric reflector and two reflecting optical structures are often selected and used. More advanced telescopic objective designs also include off-axis three-mirror astigmatic optical systems, and even four-mirror optical systems. The optical fiber can provide a larger imaging view field and better optical performance, and is mainly used in the field of aerospace optical remote sensing application with high index requirements.

The mainstream scheme of the tele optical system is an on-axis two-mirror optical system and an off-axis three-mirror astigmatism-eliminating optical system. The coaxial two-mirror system is more commonly used, the number of reflectors is less, the system transmittance is high, the coaxial structure is simple, reliable and easy to manufacture, the machining loss of the reflectors is small, and the optical machining difficulty is low. The off-axis three-reflection astigmatism optical system is a high-performance optical imaging system with a large field of view and a large relative aperture, the off-axis optical system is not blocked, and three aspheric surfaces provide more aberration correction variables. The coaxial four-reflection optical system is also a good choice of a large-view-field system, the system has a plurality of variables, and the design freedom is high.

The prior art has the following technical defects: the coaxial double-reflection system has the advantages that the folding times of the optical path are few, the focal length ratio of the system is limited, the length of a lens barrel is long, the optical rear intercept is short, and an outer lens hood is needed to inhibit stray light; the off-axis three-reflector stigmation system has the advantages that the axial size can be further reduced, but the transverse size is larger, the processing and detection of the reflector are difficult, the assembly and adjustment process is complex, and the stray light inhibition design is difficult; the coaxial three-mirror system object image is positioned at the same side of the main mirror, and a folding mirror is required to be added to lead out an image surface, so that secondary blocking is easily caused; the coaxial four-lens reflex system has too many aspheric elements and long adjustment process.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to overcome the technical defects of limited focal length ratio of the system, long length of the lens barrel, complex installation and adjustment process, difficult design of stray light inhibition and the like in the prior art.

In order to solve the above technical problem, the present invention provides a coaxial four-lens reflex tele optical system, comprising:

the primary mirror, the secondary mirror, the third mirror and the fourth mirror are coaxially arranged;

the primary mirror is symmetrically arranged relative to the three mirrors, the secondary mirror and the four mirrors are positioned on the same side of the primary mirror, and the four mirrors are positioned between the secondary mirror and the three mirrors; the primary mirror and the third mirror are high-order aspheric mirrors, and the secondary mirror and the fourth mirror are spherical mirrors;

a first central hole is formed in the center of the third mirror, and a second central hole is formed in the center of the fourth mirror;

the light rays are reflected by the primary mirror and the secondary mirror in sequence to obtain first reflected light, the first reflected light is incident to the three mirrors after passing through the second central hole, the light rays are reflected by the three mirrors to obtain second reflected light, and the second reflected light is reflected by the four mirrors, passes through the first central hole and then is converged and imaged to the focal plane.

Preferably, the main mirror and the three mirrors are integrally formed.

Preferably, the image space of the four mirrors is provided with a first plane folding mirror and a second plane folding mirror, and the light emitted from the first central hole is reflected by the first plane folding mirror and the second plane folding mirror in sequence and is converged to form an image on the focal plane.

Preferably, the aperture stop of the optical system is disposed on the primary mirror.

Preferably, the vertex curvature radius of the primary mirror ranges from-146.47 mm to-161.89 mm; the vertex curvature radius of the secondary mirror ranges from-1099.82 mm to-1215.59 mm; the vertex curvature radius of the three mirrors ranges from-39.77 mm to-43.96 mm; the vertex curvature radius of the four mirrors ranges from-31.89 mm to-35.25 mm.

Preferably, the primary mirror and the tertiary mirror are concave mirrors.

The invention discloses a telescope objective optical machine which comprises the coaxial four-reflection long-focus optical system.

Preferably, the optical system further comprises a quadri-spoke support, and the secondary mirror and the quadri-mirror are arranged on the quadri-spoke support.

Preferably, the main mirror and the three mirrors are processed in a common substrate.

The invention discloses an optical device which comprises the telescope objective optical machine.

Compared with the prior art, the technical scheme of the invention has the following advantages:

1. according to the coaxial four-reflection long-focus optical system with the two spherical surfaces, the primary mirror, the secondary mirror, the third mirror and the fourth mirror are coaxially arranged, so that the folding times of an optical path are increased, the interval between the lenses is compressed, and the axial total length of the optical system is controlled.

2. The secondary mirror and the fourth mirror are spherical surfaces, so that the element processing and detecting cost is reduced, and the element alignment and positioning requirements in assembly and adjustment are reduced; the optical system is designed with a middle image surface, and the stray light of the system can be effectively inhibited by arranging the solid field diaphragm at the middle image surface.

3. The optical system has the advantages of compact structure, convenient processing, simplified installation and adjustment, long rear working distance, high image quality, low distortion and low stray light.

Drawings

FIG. 1 is a schematic diagram of a coaxial four-lens reflex tele optical system of the present invention having two spherical surfaces;

FIG. 2 is a light envelope of an optical system;

FIG. 3 is a graph of the optical transfer function of the system;

FIG. 4 is a graph of system field curvature and distortion;

FIG. 5 is a first schematic structural diagram of the optical-mechanical device, in which the quadriradians support, the quadrilaterals, and the secondary mirror are partially cut away;

FIG. 6 is a second schematic structural diagram of the optical-mechanical device, in which the first plane folding mirror and the second plane folding mirror are partially cut away;

FIG. 7 is a cross-sectional view of the imaging optical path of the optical engine.

The specification reference numbers indicate: 1. a primary mirror; 2. a secondary mirror; 3. three mirrors; 4. four mirrors; 5. a focal plane; 6. a main three-in-one mirror; 7. a four-spoke support; 8. a first mounting seat; 9. a first planar fold mirror; 10. a second mounting seat; 11. a second planar fold mirror.

Detailed Description

The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention.

Referring to fig. 1-4, the invention discloses a coaxial four-reflection long-focus optical system, which is of a concave-convex-concave-convex structure and comprises a primary mirror 1, a secondary mirror 2, a three-mirror 3 and a four-mirror 4 which are coaxially arranged. The primary mirror 1 is symmetrically arranged relative to the tertiary mirror 3, the secondary mirror 2 and the fourth mirror 4 are positioned on the same side of the primary mirror 1, and the fourth mirror 4 is positioned between the secondary mirror 2 and the tertiary mirror 3. The primary mirror 1 and the third mirror 3 are high-order aspheric mirrors, and the secondary mirror 2 and the fourth mirror 4 are spherical mirrors. The center of the three mirrors 3 is provided with a first center hole, and the center of the four mirrors 4 is provided with a second center hole.

The light rays are reflected by the primary mirror 1 and the secondary mirror 2 in sequence to obtain first reflected light, the first reflected light is incident to the third mirror 3 after passing through the second central hole, the light rays are reflected by the third mirror 3 to obtain second reflected light, and the second reflected light is reflected by the fourth mirror 4, passes through the first central hole and then is converged and imaged to the focal plane 5.

As shown in fig. 2, a diagram of the light envelope of the optical system is shown. The primary mirror 1 and the three mirrors 3 are concave surfaces, the axial positions of the inner edge of the primary mirror 1 and the outer edge of the three mirrors 3 are close to each other in optical design and do not have radial overlapping, the primary mirror 1 and the three mirrors 3 are combined into one optical element for processing in optical machine design, and the optical element containing the primary mirror 1 and the three mirrors 3 is processed into a primary three-in-one mirror 6.

The working principle of the invention is as follows: in the invention, a coaxial four-reflection long-focus optical system adopts a coaxial four-reflection layout, and the axial length of the optical system is compressed by folding a light path; the integrated design of the primary mirror 1 and the three mirrors 3 avoids the alignment and adjustment process of the primary three-in-one mirror 6, and reduces the difficulty of adjustment; by the spherical surface shape design of the secondary mirror 2 and the four mirrors 4, the processing difficulty of the optical element is reduced, and the element alignment and positioning requirements in assembly and adjustment are reduced; through the optimized design of the surface shapes and high-order terms of the main mirror 1 and the three mirrors 3, astigmatism and field curvature are effectively corrected, and distortion is controlled; the optical system is designed based on a secondary imaging principle, stray light inhibition capacity is improved, and imaging contrast of the optical system is improved.

In the invention, the main mirror 1 and the three mirrors 3 are integrally formed, and specifically, the main mirror 1 and the three mirrors 3 are processed on the same substrate. Therefore, the structure is compact, and the installation is convenient.

The image space of the four mirrors 4 is provided with a first plane folding mirror 9 and a second plane folding mirror 11, and light rays emitted from the first central hole are reflected by the first plane folding mirror 9 and the second plane folding mirror 11 in sequence and are converged to form an image to the focal plane 5. The first plane folding mirror 9 and the second plane folding mirror 11 are beneficial to further folding and compressing the light path envelope, thereby reducing the volume of the whole optical system.

An aperture stop of the optical system is provided on the primary mirror 1.

In the invention, the range of the curvature radius of the vertex of the primary mirror 1 is-146.47 mm to-161.89 mm; the vertex curvature radius of the secondary mirror 2 ranges from-1099.82 mm to-1215.59 mm; the vertex curvature radius of the three mirrors 3 ranges from-39.77 mm to-43.96 mm; the vertex radius of curvature of the four mirrors 4 ranges from-31.89 mm to-35.25 mm.

Table 1 shows the design parameters of the optical system components according to one embodiment.

TABLE 1

Table 2 shows the optical system parameters.

TABLE 2

Parameter item	Numerical value
		Range of wave bands	450nm-700nm
Focal length	1000mm
		Bore diameter	100mm
f number	10
		Diagonal field of view	1.40°
Optical transmittance	80.75％
		Distortion of optical system	≤0.35％
Coefficient of line blocking	0.45
		Maximum three-dimensional size	100mm×100mm×155mm

As can be seen from Table 2, the effective aperture of the optical system is 100mm, the focal length is 1000mm, the F number is 10, the full field angle is 1.4 degrees, and the length of the optical system is 152.36 mm.

Fig. 3 is a graph of the optical transfer function, and it can be seen that the optical transfer function of the optical system of the present embodiment is better than 0.242 at 100l p/mm for all fields of view and all wavelengths.

The field curvature and distortion diagram of the system are shown in fig. 4, and it can be seen that the maximum distortion of the optical system of the present embodiment is less than 0.35%.

Referring to fig. 5-7, the invention discloses a telescope objective optical machine, comprising the coaxial four-lens reflex tele optical system.

The invention also comprises a quadri-spoke support 7, and the secondary mirror 2 and the four-mirror 4 are arranged on the quadri-spoke support 7. The optical machine further comprises a first mounting seat 8 and a second mounting seat 10, wherein the first plane folding mirror 9 is arranged on the first mounting seat 8, and the second plane folding mirror 11 is arranged on the second mounting seat 10. The maximum three-dimensional size of the optical machine after the design is less than 100mm multiplied by 100 mm. On the basis of the technology of ultra-precision mirror surface machining based on metal aluminum reflectors and single-point diamonds, proper weight reduction optimization design is carried out, and the weight of the designed optical machine is smaller than 400 g.

The optical machine design fully utilizes the optical design characteristics of the coaxial four-reflection long-focus optical system, and has the characteristics of small size, light weight and good optical performance. The method is suitable for a cubic satellite 1U remote sensing optical imaging system, a portable high-performance civil telescope and a remote monitoring optical imaging system.

The invention discloses an optical device which comprises the telescope objective optical machine.

The invention has the following advantages:

1. according to the coaxial four-reflection long-focus optical system with the two spherical surfaces, the primary mirror, the secondary mirror, the third mirror and the fourth mirror are coaxially arranged, so that light path folding is increased, the spacing of the lenses is effectively compressed, and the axial total length of the optical system is controlled.

2. The main mirror and the three mirrors are processed on the same substrate, so that the difficulty of optical-mechanical processing and system installation and adjustment is reduced, and the single-point diamond turning integrated processing is facilitated.

3. The secondary mirror and the fourth mirror are spherical surfaces, so that the element processing and detecting cost is reduced, and the assembly and adjustment requirements are lowered; the optical system is designed with an intermediate image surface, and stray light of the system can be effectively inhibited at the intermediate image surface.

4. The optical system has the advantages of compact structure, convenient processing, simplified installation and adjustment, long rear working distance, high image quality, low distortion and low stray light.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.