Coaxial catoptric optical telescope system

Abstract

The application discloses a coaxial reflection type optical telescopic system, and belongs to the technical field of applied optics. The optical telescopic system comprises a primary mirror, a secondary mirror, a tertiary mirror, a central mirror and an imaging assembly which are arranged along the light path direction. The primary mirror and the tertiary mirror are coaxially arranged in an integrated manner, and the primary mirror, the secondary mirror and the tertiary mirror are coaxially arranged. The central mirror has a central hole, and the position of the central hole is located between the secondary mirror and the tertiary mirror. The position of the central hole satisfies that the light reflected by the secondary mirror passes through the central hole and is incident on the tertiary mirror, and the light reflected by the tertiary mirror is incident on the central mirror. The light reflected by the central mirror is incident on the imaging assembly. The optical telescopic system has the advantages of wide response band, high resolution and compact structure.

Description

Technical Field

[0001] This application relates to the field of applied optics technology, and in particular to a coaxial reflective optical telescope system. Background Technology

[0002] The demand for optical systems in the field of airborne optoelectronic detection is increasing, with wide spectral density and high resolution being two prominent requirements. Wide spectral density requires optical systems to cover the detection and identification of visible light, laser, mid-infrared, and long-infrared bands within the limited envelope of the airborne environment; high resolution requires optical systems to have a sufficiently long focal length to meet spatial resolution requirements, while also requiring optical systems to increase aperture to meet detection range requirements.

[0003] Airborne telescope common aperture optical systems have a critical impact on system layout, response band, and performance indicators. Common optical telescope systems can be divided into reflective, catadioptric, and transmissive types. Among them, catadioptric and transmissive types have great difficulty in chromatic aberration correction, requiring many lenses to correct chromatic aberration in visible light and mid-to-long-wave infrared light, which does not meet the compact envelope requirements of airborne platforms. Summary of the Invention

[0004] To meet the requirements of wide band, high resolution, long focal length, and compact space for airborne optical systems, this application provides a coaxial reflective optical telescope system with a coaxial three-mirror optical structure, which has the advantages of wide response band, high resolution, and compact structure.

[0005] This application provides a coaxial reflective optical telescope system, including a primary mirror, a secondary mirror, a third mirror, a central reflecting mirror, and an imaging assembly arranged along the optical path; wherein...

[0006] The primary mirror and the three mirrors are coaxially integrated, and the primary mirror, the secondary mirror, and the three mirrors are coaxially integrated.

[0007] The central reflector has a central hole located between the secondary and tertiary mirrors. The position of the central hole is such that light reflected from the secondary mirror passes through the central hole and enters the tertiary mirror, and after being reflected by the tertiary mirror, it enters the central reflector. The light reflected by the central reflector then enters the imaging assembly.

[0008] Optionally, the primary mirror and the third mirror are parabolic surfaces with their concave surfaces facing the secondary mirror;

[0009] The distance d1 between the vertices of the parabolic surfaces of the primary mirror and the three mirrors satisfies: |d1|≤3mm.

[0010] Optionally, the primary mirror and the three mirrors are integrated lenses, and the materials include aluminum alloy or silicon single crystal;

[0011] The secondary mirror is a high-order aspherical mirror with its convex surface facing the primary mirror, and is made of aluminum alloy or silicon single crystal material.

[0012] Optionally, the radius of curvature R1 of the primary mirror satisfies: -310mm≤R1≤-290mm;

[0013] The curvature radius R2 of the secondary mirror satisfies: -100mm≤R2≤-80mm;

[0014] The curvature radius R3 of the three mirrors satisfies: -120mm≤R3≤-100mm;

[0015] The distance L1 between the primary mirror and the secondary mirror satisfies: -130mm≤L1≤-120mm;

[0016] The combined focal length f1 of the primary mirror and the secondary mirror satisfies: 320mm≤f1≤380mm;

[0017] The aperture D1 of the primary mirror satisfies: 210mm≤D1≤230mm;

[0018] The aperture D2 of the secondary mirror satisfies: 40mm≤D2≤50mm;

[0019] The aperture D3 of the three mirrors satisfies: 45mm≤D3≤50mm.

[0020] Optionally, the surface of the central reflector near the primary mirror is coated with a reflective film;

[0021] The central hole consists of an elliptical cylindrical opening on one side surface near the primary mirror and a funnel-shaped cylindrical opening on the other side surface; wherein,

[0022] The major axis a1 and minor axis b1 of the elliptical cylinder opening satisfy: 10mm≤a1≤15mm, 7mm≤b1≤11mm, and the cylinder height c1 satisfies: 0mm≤c1≤0.5mm.

[0023] The small diameter of the flared cylindrical opening is the same as that of the elliptical cylindrical opening, while the large diameter is elliptical. Its major axis a2 and minor axis b2 satisfy: 33mm≤a2≤36mm, 28mm≤b2≤33mm. The cylindrical height c2 satisfies: 3mm≤c2≤5mm.

[0024] Optionally, the distance L2 between the central reflector (4) and the secondary mirror (2) satisfies: 55mm≤L2≤65mm;

[0025] The distance L3 between the central reflector and the three mirrors satisfies: 55mm ≤ L3 ≤ 65mm.

[0026] Optionally, the exit pupil of the coaxial reflective optical telescope is located in the light-emitting direction of the central reflector, and the distance P1 between it and the central reflector satisfies: 30mm≤P1≤50mm.

[0027] The coaxial reflective optical telescope system operates in the wavelength range of 0.4μm to 14μm, with a magnification β satisfying: 6≤β≤7, and a full field of view ω satisfying: 0°≤ω≤2°.

[0028] The F# range of the coaxial reflective optical telescope system is 1.4 to 6.

[0029] The optical telescope system of this application adopts a coaxial three-mirror optical structure, which has the advantages of wide response band, high resolution and compact structure, and can meet the requirements of airborne optical systems such as wide band, high resolution, long focal length and compact space.

[0030] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0031] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0032] Figure 1 This is a schematic diagram of the optical path composition of an optical telescope system according to an embodiment of this application. Detailed Implementation

[0033] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0034] Reflective optical telescope systems do not introduce chromatic aberration and can be divided into coaxial reflective and off-axis reflective systems. Off-axis reflective systems have a large structural size and are difficult to assemble and adjust. Therefore, coaxial reflective telescope systems have promising applications in airborne broadband and high-resolution optical systems.

[0035] To meet the requirements of wide bandwidth, high resolution, long focal length, and compact space for airborne optical systems, this application provides a coaxial reflective optical telescope system, such as... Figure 1 As shown, it includes a primary mirror 1, a secondary mirror 2, a third mirror 3, a central reflecting mirror 4, and an imaging assembly 6 arranged along the optical path; wherein,

[0036] The primary mirror 1 and the three mirrors 3 are coaxially integrated, and the primary mirror 1, the secondary mirror 2, and the three mirrors 3 are coaxially integrated.

[0037] The central reflector 4 has a central hole, which is located between the secondary mirror and the third mirror. The position of the central hole is such that light reflected from the secondary mirror 2 passes through the central hole and enters the third mirror 3, and after being reflected by the third mirror 3, it enters the central reflector 4. The light reflected by the central reflector 4 then enters the imaging component 6.

[0038] In some specific examples, the imaging component 6 may include visible light, near-infrared, mid-wave infrared, and long-wave infrared imaging sensors, which may be in the form of common-path, common-focal-plane imaging, or split-path, non-comfocal-plane imaging.

[0039] The optical telescope system of this application adopts a coaxial three-mirror optical structure, which has the advantages of wide response band, high resolution and compact structure, and can meet the requirements of airborne optical systems such as wide band, high resolution, long focal length and compact space.

[0040] In some embodiments, the primary mirror 1 and the third mirror 3 are parabolic surfaces with their concave surfaces facing the secondary mirror 2;

[0041] The distance d1 between the vertices of the parabolic surfaces of the primary mirror 1 and the three mirrors 3 satisfies: |d1|≤3mm. In some specific examples, for instance, the distance d1 between the vertices of the parabolic surfaces of the primary mirror and the three mirrors is 1.5mm.

[0042] In the embodiments of this application, controlling the distance between the vertices of the parabolic surfaces of the secondary and tertiary mirrors can adjust the difference in elevation between the inner circle of the primary mirror and the outer circle of the tertiary mirror to a positive number, which facilitates processing.

[0043] In some embodiments, the primary mirror and the three mirrors 3 are integrated lenses made of aluminum alloy or silicon single crystal; the secondary mirror 2 is a high-order aspherical mirror with its convex surface facing the primary mirror 1, made of aluminum alloy or silicon single crystal. In some specific applications, the primary mirror and the three mirrors are integrated lenses made of silicon, and the secondary mirror is a high-order aspherical mirror with its convex surface facing the primary mirror, also made of silicon.

[0044] In the embodiments of this application, the primary mirror, the integrated three-mirror lens, and the secondary mirror lens are all made of single-crystal silicon material, taking into account both machinability and surface accuracy. The primary mirror and the integrated three-mirror lens have parabolic surfaces to correct spherical aberration of the telescope system, while the secondary mirror has a high-order aspherical surface, mainly used to correct coma and astigmatism of the telescope system.

[0045] In some embodiments, the surface of the central reflector 4 near the main mirror 1 is coated with a reflective film;

[0046] The central hole consists of an elliptical cylindrical opening on one side surface near the primary mirror 1 and a funnel-shaped cylindrical opening on the other side surface; wherein,

[0047] The major axis a1 and minor axis b1 of the elliptical cylinder opening satisfy: 10mm≤a1≤15mm, 7mm≤b1≤11mm, and the cylinder height c1 satisfies: 0mm≤c1≤0.5mm.

[0048] The small diameter of the flared cylindrical opening is the same as that of the elliptical opening, while the large diameter is elliptical. Its major axis a2 and minor axis b2 satisfy: 33mm≤a2≤36mm, 28mm≤b2≤33mm. The cylindrical height c2 satisfies: 3mm≤c2≤5mm.

[0049] In some application examples, the surface of the central reflector near the primary mirror is coated with a reflective film and has an elliptical opening. The major axis of the ellipse is a1 = 14 mm, the minor axis is b1 = 10 mm, and the height is c1 = 0.5 mm. The back of the central reflector has a flared opening. The small diameter of the flared opening matches the elliptical opening on the front surface, while the large diameter is elliptical with a major axis a2 = 35 mm, a minor axis b2 = 30 mm, and a height c2 = 5 mm. Specifically, the size and shape of the opening of the central reflector are determined based on the direction of light, while ensuring that it does not block light and maintains the accuracy of the reflector surface, and the opening size is minimized to improve the working efficiency of the telescope system.

[0050] In some embodiments, the radius of curvature R1 of the primary mirror 1 satisfies: -310mm≤R1≤-290mm;

[0051] The radius of curvature R2 of the secondary mirror 2 satisfies: -100mm≤R2≤-80mm;

[0052] The radius of curvature R3 of the three mirrors 3 satisfies: -120mm≤R3≤-100mm;

[0053] The distance L1 between the primary mirror 1 and the secondary mirror 2 satisfies: -130mm≤L1≤-120mm;

[0054] The combined focal length f1 of the primary mirror 1 and the secondary mirror 2 satisfies: 320mm≤f1≤380mm;

[0055] The aperture D1 of the primary mirror 1 satisfies: 210mm≤D1≤230mm;

[0056] The aperture D2 of the secondary mirror 2 satisfies: 40mm≤D2≤50mm;

[0057] The aperture D3 of the three mirrors 3 satisfies: 45mm≤D3≤50mm.

[0058] In some application examples of this application, the radius of curvature of the primary mirror is R1 = -295 mm, the radius of curvature of the secondary mirror is R2 = -83.6 mm, the radius of curvature of the tertiary mirror is R3 = -116.3 mm, the aspheric coefficients of the secondary mirror are A = 4.1099e-6, B = -2.4653e-9, and C = 3.3757e-14, and the surface equation of the aspheric surface is:

[0059]

[0060] The distance between the primary mirror and the secondary mirror is L1 = -122mm, and the combined focal length of the primary and secondary mirrors is f1 = 378mm; the distance between the central mirror and the secondary mirror is L2 = 61.5mm, and the distance between the central mirror and the third mirror is L3 = 62mm.

[0061] In some embodiments, the distance L2 between the central reflector 4 and the secondary reflector 2 satisfies: 55mm ≤ L2 ≤ 65mm; the distance L3 between the central reflector and the third reflector 3 satisfies: 55mm ≤ L3 ≤ 65mm.

[0062] In some application examples, the primary mirror has an aperture of D1 = 220 mm, the secondary mirror has an aperture of D2 = 50 mm, and the tertiary mirror has an aperture of D3 = 48 mm. The aperture of the tertiary mirror is no larger than that of the secondary mirror, which helps to reduce the influence of stray light on the optical system.

[0063] In some embodiments, the exit pupil of the coaxial reflective optical telescope is located in the light-emitting direction of the central reflector, and the distance P1 between the exit pupil and the central reflector satisfies: 30mm≤P1≤50mm;

[0064] The coaxial reflective optical telescope system operates in the wavelength range of 0.4μm to 14μm, with a magnification β satisfying 6 ≤ β ≤ 7 and a full field of view ω satisfying 0° ≤ ω ≤ 2°. For example, in some specific examples, the optical telescope system operates in the wavelength ranges of 0.4μm to 1.1μm, 3.7μm to 5μm, and 7.7μm to 11.5μm, with a magnification β = 6.5 and a full field of view ω = 1.5°. Specifically, the optical telescope system exhibits no chromatic aberration in any wavelength band, significantly reducing the design complexity of the imaging components.

[0065] The F# range of the coaxial reflective optical telescope system is 1.4 to 6.

[0066] In some examples, the exit pupil of the optical telescope system is located in the light-emitting direction of the central reflector, at a distance P1 = 35 mm from the central reflector. By controlling the position of the exit pupil of the telescope system, the size of the central reflector and its opening can be effectively controlled, thereby reducing system occlusion and improving the system's detection and recognition capabilities.

[0067] In some embodiments, the F-number is 4 for the visible light and laser bands, 5 for the mid-wave band, and 3 for the long-wave band. The F-number of an optical telescope system is determined by the relative aperture of the imaging components.

[0068] The optical telescope system of this application adopts a coaxial three-mirror system with a central mirror with an aperture, realizing wide-band, high-resolution, common-aperture telescope function. It has the advantages of compact space, high magnification, wide operating band, and easy assembly and adjustment, meeting the usage requirements of airborne photoelectric detection systems.

[0069] It should be noted that, in the embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0070] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0071] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims. All of these forms are within the protection scope of this application.

Claims

1. A coaxial reflective optical telescope system, characterized in that, It includes a primary mirror (1), a secondary mirror (2), a third mirror (3), a central reflecting mirror (4), and an imaging assembly (6) arranged along the optical path; among which, The primary mirror (1) and the three mirrors (3) are coaxially integrated, and the primary mirror (1), the secondary mirror (2), and the three mirrors (3) are coaxially integrated. The central reflector (4) has a central hole located between the secondary mirror and the third mirror. The position of the central hole is such that light reflected from the secondary mirror (2) passes through the central hole and enters the third mirror (3), and after being reflected by the third mirror (3), it enters the central reflector (4). The light reflected by the central reflector (4) enters the imaging component (6). The surface of the central reflector (4) near the main mirror (1) is coated with a reflective film; The central hole is an elliptical cylindrical opening on one side surface near the main mirror (1) and a trumpet-shaped cylindrical opening on the other side surface; wherein, The opening of the elliptical cylinder corresponds to the major axis of the ellipse. and short axis Satisfy: 10mm≤ ≤15mm, 7mm≤ ≤11mm, cylinder height Satisfy: 0mm≤ ≤0.5mm; The small diameter of the flared cylindrical opening is the same as that of the elliptical cylindrical opening, while the large diameter is elliptical, with its major axis... and short axis Satisfies: 33mm≤ ≤36mm, 28mm≤ ≤33mm, cylinder height Satisfy: 3mm≤ ≤5mm.

2. The coaxial reflective optical telescope system as described in claim 1, characterized in that, The primary mirror (1) and the three mirrors (3) are parabolic surfaces with their concave surfaces facing the secondary mirror (2); The distance d1 between the vertices of the parabolic surfaces of the primary mirror (1) and the three mirrors (3) satisfies: .

3. The coaxial reflective optical telescope system as described in claim 2, characterized in that, The primary mirror and the three mirrors (3) are integrated lenses, and the materials include aluminum alloy or silicon single crystal; The secondary mirror (2) is a high-order aspherical mirror with its convex surface facing the primary mirror (1), and is made of aluminum alloy or silicon single crystal material.

4. The coaxial reflective optical telescope system as described in claim 3, characterized in that, The radius of curvature of the primary mirror (1) Satisfies: -310mm≤ ≤-290mm; The radius of curvature of the secondary mirror (2) Satisfies: -100mm≤ ≤-80mm; The radius of curvature of the three mirrors (3) Satisfies: -120mm≤ ≤-100mm; The distance between the primary mirror (1) and the secondary mirror (2) Satisfies: -130mm≤ ≤-120mm; The combined focal length of the primary mirror (1) and the secondary mirror (2) Satisfies: 320mm≤ ≤380mm; The aperture of the primary mirror (1) Satisfies: 210mm≤ ≤230mm; The aperture of the secondary mirror (2) Satisfies: 40mm≤D2≤50mm; The aperture of the three mirrors (3) Satisfies: 45mm≤ ≤50mm.

5. The coaxial reflective optical telescope system as described in claim 1, characterized in that, The distance between the central reflector (4) and the secondary mirror (2) Satisfies: 55mm≤ ≤65mm; The distance of the central reflecting mirror from the three mirrors (3) Satisfies: 55mm≤ ≤65mm.

6. The coaxial reflective optical telescope system as described in claim 1, characterized in that, The exit pupil of the coaxial reflective optical telescope is located in the light-emitting direction of the central reflector, and its distance from the central reflector is... Satisfy: 30mm≤ ≤50mm; The coaxial reflective optical telescope system operates in the wavelength range of 0.4μm to 14μm, with a magnification β satisfying: 6≤β≤7, and a full field of view ω satisfying: 0°≤ω≤2°. The F# range of the coaxial reflective optical telescope system is 1.4 to 6.

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