Optical system and wide-temperature transmission-type telescope based on same

Abstract

The invention relates to the technical field of optical imaging, and discloses an optical system and a wide-temperature transmission-type telescope based on the optical system, and an objective lens group sequentially comprises an objective lens first lens, an objective lens second lens, an objective lens third lens and an objective lens fourth lens from a light incident direction to a light emergent direction, the third objective lens and the fourth objective lens are combined to form an objective balsaming lens; the eyepiece group sequentially comprises a first eyepiece lens and a second eyepiece lens from a light incident direction to a light emergent direction; the objective lens group and the eyepiece group satisfy the following conditions: fw / fm =-11--12, fw-fm < = 115 mm, and phi0 = 60 mm, where fw is the focal length of the objective lens group, fm is the focal length of the eyepiece group, and phi0 is the entrance diameter of the optical system. According to the technical scheme provided by the invention, the athermalization optical system design of the high-performance telescope can be realized in inter-satellite laser communication, so that the stability of the focal length and the image quality in a wide temperature range is kept.

Description

Technical Field

[0001] This application relates to the field of optical imaging technology, and more particularly to an optical system and a wide-temperature transmission telescope based thereon. Background Technology

[0002] Inter-satellite laser communication, a crucial technology in the aerospace field, is widely used in satellite networking and deep space exploration. The performance of its core optical component, the telescope, directly impacts the pointing accuracy and signal transmission efficiency of the communication link. Traditional transmission telescopes suffer from optical system defocusing and image blurring when exposed to temperature changes, limiting their applications. Therefore, employing a calorimetric design to maintain focal length and image quality stability is critical. Calorimetric optical design utilizes materials with different thermal properties for compensation, offering advantages in high reliability and lightweight design, but also presents multiple challenges, including material selection, chromatic aberration correction, and cost control.

[0003] Therefore, how to achieve the design of a thermal optical system for high-performance telescopes in inter-satellite laser communication, so as to maintain the stability of focal length and image quality over a wide temperature range, is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] This application provides an optical system and a wide-temperature transmission telescope based thereon, which achieves the technical effect of a thermalized optical system design for high-performance telescopes in inter-satellite laser communication, thereby maintaining the stability of focal length and image quality over a wide temperature range.

[0005] To achieve the above objectives, the main technical solutions adopted in this application include: In a first aspect, embodiments of this application provide an optical system, which includes a protective glass, an aperture element, an objective lens group, a central mirror, and an eyepiece group; wherein... The objective lens group, from the light incident direction to the light exit direction, includes, in sequence: a first objective lens, a second objective lens, a third objective lens, and a fourth objective lens. The first objective lens is a meniscus lens with positive optical power and its concave surface facing the light exit direction. The second and third objective lenses are biconvex lenses with positive optical power. The fourth objective lens is a biconcave lens with negative optical power. The third and fourth objective lenses are combined to form a cemented objective lens. The eyepiece group includes, in sequence from the light incident direction to the light exit direction: a first eyepiece lens and a second eyepiece lens. The first eyepiece lens is a meniscus lens with negative optical power and its concave surface facing the light exit direction. The second eyepiece lens is a biconcave lens with negative optical power. The objective lens group and the eyepiece group satisfy the following conditions: f w / f m =-11~-12, fw -|f m |≤115mm, Φ0=60mm Among them, f w f is the focal length of the objective lens group. m Φ is the focal length of the eyepiece group, and Φ0 is the entrance diameter of the optical system.

[0006] This embodiment provides an optical system that effectively optimizes focal length and image quality. The focal length ratio f of the optical system is... w / f m =-11~-12 and focal length difference f w -|f m The ≤115mm aperture ensures a high magnification and excellent imaging quality, while the 60mm entrance pupil diameter (Φ0) enhances light throughput. Over a wide temperature range, this design effectively controls optical errors, preventing degradation in focal length and image quality due to temperature changes, thus maintaining the stability and reliability of signal reception. This compact and lightweight optical system meets the high-performance requirements of laser communication.

[0007] In one embodiment, from the light incident direction to the light exit direction... The convex surface radius of curvature of the first objective lens is [100mm, 110mm], and the concave surface radius of curvature of the first objective lens is [300mm, 400mm]. The radius of curvature of the first convex surface of the objective lens is [70mm, 90mm], and the radius of curvature of the second convex surface of the objective lens is [-500mm, -600mm]. The convex surface curvature radius of the cemented objective lens is [55mm, 65mm]; the cemented surface curvature radius of the cemented objective lens is [-200mm, -500mm]; the convex surface curvature radius of the cemented objective lens is [60mm, 90mm].

[0008] In one embodiment, from the light incident direction to the light exit direction... The convex surface radius of curvature of the first eyepiece lens is [40mm, 50mm], and the concave surface radius of curvature of the first eyepiece lens is [10mm, 20mm]. The radius of curvature of the first concave surface of the second lens of the eyepiece is [-30mm, 40mm]; The radius of curvature of the second concave surface of the second lens of the eyepiece is [25mm, 35mm].

[0009] In one embodiment, the center thickness of the first objective lens is [4mm, 6mm], the center thickness of the second objective lens is [8mm, 9.5mm], the air gap between the first and second objective lenses is [0.5mm, 1mm], the center thickness of the third objective lens is [9mm, 10.5mm], the center thickness of the fourth objective lens is [4.5mm, 5.5mm], and the air gap between the cemented objective lens and the central mirror is [31mm, 32mm].

[0010] In one embodiment, the air gap between the central reflector and the first eyepiece lens is [43.7mm, 44.3mm], the center thickness of the first eyepiece lens is [4mm, 5mm], the center thickness of the second eyepiece lens is [2.3mm, 2.7mm], and the air gap between the first eyepiece lens and the second eyepiece lens is [4.5mm, 7mm].

[0011] In one embodiment, the first objective lens is made of radiation-resistant glass, the second objective lens is made of heavy crown glass, the third objective lens is made of heavy phosphorus crown glass, and the fourth objective lens is made of heavy flint glass.

[0012] In one embodiment, the first eyepiece lens and the second eyepiece lens are made of heavy flint glass.

[0013] In one embodiment, the protective glass is made of radiation-resistant glass, and the central reflector is made of fused silica or microcrystalline glass.

[0014] Secondly, embodiments of this application provide a wide-temperature transmission telescope for an inter-satellite laser communication terminal, including the optical system described above.

[0015] In one embodiment, the performance parameters of the wide-temperature transmission telescope include: Field of view: ≥±3mrad; Aperture diameter: ≥60mm; Magnification: 11x~12x; Applicable temperature: -5℃ to 40℃; RMS wavefront error: RMS≤1 / 30λ@1550nm over the entire operating temperature range; Size restrictions: Height × Width ≤ 96mm × 95mm.

[0016] This embodiment provides a wide-temperature transmission telescope for inter-satellite laser communication terminals. It achieves a high-performance, athermalized optical system design within the inter-satellite laser communication terminal, maintaining stability of focal length and image quality over a wide temperature range. Its field of view is ≥±3mrad, ensuring effective capture of a large field of view, thereby improving fault tolerance and communication reliability. A ≥60mm aperture enhances light collection capabilities, maintaining a high signal-to-noise ratio even in low-light environments, ensuring stable data transmission. An 11x to 12x magnification provides necessary detail magnification for target alignment, avoiding the problem of a narrow field of view. The applicable temperature range from -5℃ to 40℃ allows the telescope to operate normally under various environmental conditions, maintaining performance stability. Simultaneously, a wavefront error standard of RMS≤1 / 30λ@1550nm across the entire operating temperature range ensures extremely high imaging quality, effectively reducing signal distortion and improving the transmission quality of laser signals. Finally, its compact size of ≤96mm×95mm (height × width) facilitates integration, enhances portability, and reduces launch costs and operational complexity. These design parameters together provide a solid technical foundation for interplanetary laser communication. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 A schematic diagram of an optical system provided in an embodiment of this application; Figure 2 This is a graph showing the relationship between RMS wavefront error and field of view at different temperatures in Example 1. Figure 3 This is a dot plot of Example 1 at different temperatures and different viewing angles; Figure 4 This is the axial color difference diagram of Example 1 at 20°C.

[0019] Explanation of reference numerals in the attached figures Protective glass L1, aperture element L2, first objective lens L3, second objective lens L4, third objective lens L5, fourth objective lens L6, central reflecting mirror L7, first eyepiece lens L8, second eyepiece lens L9, the two sides of the first objective lens L3 are S31 and S32, the two sides of the second objective lens L4 are S41 and S42, the two sides of the third objective lens L5 are S1 and S2, the two sides of the fourth objective lens L6 are S2 and S3, the two sides of the first eyepiece lens L8 are S81 and S82, and the two sides of the second eyepiece lens L9 are S91 and S92. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] Inter-satellite laser communication, a crucial technology in modern aerospace, is widely used in satellite networking and deep space exploration missions. Its high transmission rate, strong anti-interference capabilities, good security, and abundant spectrum resources make it a key solution for long-distance, high-capacity data transmission. In this context, the telescope, as the core optical component of the inter-satellite laser communication terminal, is critical to the pointing accuracy, signal transmission efficiency, and equipment compatibility of the communication link. This requires the telescope to not only possess excellent optical performance but also meet the stringent requirements of low cost, wide environmental adaptability, and precise pointing within a narrow field of view in aerospace scenarios.

[0022] Currently, the telescopes commonly used in inter-satellite laser communication terminals include three types: coaxial transmission telescopes, reflection telescopes, and catadioptric telescopes. Among them, traditional transmission telescopes, due to their unobstructed central design, are closest to meeting the requirements for laser signal transmission and collimation. However, in practical applications, this type of telescope is significantly affected by surrounding environmental factors, especially temperature changes. When the ambient temperature fluctuates, the surface shape, spacing, thickness, and refractive index of the optical system all change, causing the optical system to defocus and the image to become blurred, thus limiting its effective application in the space environment.

[0023] To address this issue, anechoic design is an effective approach. Anechoic design aims to maintain focal length and image quality stability in optical systems over a wide temperature range. Currently, there are two main methods: mechanical compensation and optical anechoic design. Mechanical compensation methods are further divided into electronically active and mechanically passive methods. While electronically active methods can be precisely controlled using sensors and motors, their complex structure and high cost hinder miniaturization. Mechanically passive methods, on the other hand, utilize components with different coefficients of thermal expansion for compensation; although their structure is relatively simple, their reliability is often lower and their weight is greater.

[0024] In contrast, anechoic optical design achieves compensation by combining optical materials with different thermal properties, offering advantages such as no moving parts, high reliability, simple structure, and light weight. However, this approach also faces many challenges. For example, the influence of the space environment on optical systems, such as irradiance and heat from the solar spectrum, increases the difficulty of selecting lens optical materials. Furthermore, factors such as chromatic aberration correction, cost control, and size limitations must be considered during the design process, all of which contribute to the increased complexity of the design.

[0025] In summary, how to achieve the design of a thermal optical system for high-performance telescopes in inter-satellite laser communication, so as to maintain the stability of focal length and image quality over a wide temperature range, is a technical problem that urgently needs to be solved.

[0026] To address the aforementioned technical problems, this embodiment provides an optical system. Figure 1 A schematic diagram of an optical system provided in an embodiment of this application is shown below. Figure 1 As shown, the optical system includes a protective glass L1, an aperture element L2, an objective lens group, a central reflecting mirror L7, and an eyepiece group; wherein, The objective lens group, from the light incident direction to the light exit direction, includes: objective lens L3, objective lens L4, objective lens L5, and objective lens L6. Objective lens L3 is a meniscus lens with positive optical power and its concave surface facing the light exit direction. Objective lens L4 and objective lens L5 are biconvex lenses with positive optical power. Objective lens L6 is a biconcave lens with negative optical power. Objective lens L5 and objective lens L6 are combined to form a cemented objective lens. The eyepiece group includes, from the light incident direction to the light exit direction, the following components in sequence: eyepiece first lens L8 and eyepiece second lens L9. The eyepiece first lens L8 is a meniscus lens with negative optical power and its concave surface facing the light exit direction. The eyepiece second lens L9 is a biconcave lens with negative optical power. The objective lens group and the eyepiece group satisfy the following conditions: f w / f m =-11~-12, fw -|f m |≤115mm, Φ0=60mm Among them, f w f is the focal length of the objective lens group. m Φ is the focal length of the eyepiece group, and Φ0 is the entrance diameter of the optical system.

[0027] Specifically, the protective glass L1, as a front-end component of the optical system, primarily functions to filter out spectra outside the operating wavelength range and suppress interference from strong sunlight on the normal operation of the optical system, thereby ensuring the sensitivity and reliability of the terminal under strong background light. Furthermore, it also provides protection, especially against radiation in the space environment, slowing down the aging of the optical lens coating. Preferably, the protective glass L1 is made of radiation-resistant glass, specifically fused silica.

[0028] The aperture stop element L2 is an aperture stop, whose main function is to limit the aperture size of the optical system and control the amount of light entering the optical system.

[0029] The objective lens group is responsible for focusing the incident light rays to form a clear image, and its structure is as follows: Objective lens L3: This is a meniscus lens with positive focal length, its concave surface facing the light exit direction. It is primarily used to converge the light beam and also provides protection. Preferably, objective lens L3 is made of radiation-resistant glass, specifically fused silica or CDGM grade radiation-resistant glass.

[0030] Objective lens L4 and objective lens L5 are biconvex lenses with positive focal length, responsible for further focusing light and improving the optical characteristics of imaging. Preferably, objective lens L4 is made of heavy crown glass, and objective lens L5 is made of heavy phosphor crown glass.

[0031] The fourth objective lens L6 is a negative-power biconcave lens, which, together with the third objective lens L5, forms a cemented objective lens, aiming to achieve better optical performance and optical path compensation. Preferably, the fourth objective lens L6 is made of heavy flint glass.

[0032] The central reflecting mirror L7 is a plane mirror, positioned between the objective lens group and the eyepiece group, primarily used to deflect the light path by 90°. This design not only effectively reduces the height of the optical system but also optimizes the optical path, ensuring that light can pass smoothly through the entire optical system, thereby improving overall optical performance. Preferably, the central reflecting mirror L7 is made of fused silica or microcrystalline glass. This material maintains good optical properties under drastic temperature changes, avoiding deformation caused by temperature fluctuations and thus not affecting the quality of the light path.

[0033] The eyepiece group is used to magnify the image output by the objective lens group, and its structure is as follows: Eyepiece first lens L8: This is a negative focal power meniscus lens with its concave surface facing the light exit direction. It functions similarly to the objective first lens L3, helping to expand the field of view. Preferably, the eyepiece first lens L8 is made of heavy flint glass.

[0034] The second eyepiece lens L9 is a negative focal power biconcave lens that further improves image quality. Preferably, the second eyepiece lens L9 is made of heavy flint glass.

[0035] Focal length ratio (f) w / f m The focal length difference (f) ranges from -11 to -12, providing good imaging magnification and field of view. w -|f m |≤115mm) indicates that the focal length difference between the objective lens group and the eyepiece lens group must be less than or equal to 115 mm. This helps maintain the compactness and compatibility of the optical system, ensuring optimal optical performance in space-constrained situations. The entrance pupil diameter is 60 mm. At this diameter, the receiving power, signal-to-noise ratio (SNR), and diffraction-limited angle of the terminal system can be guaranteed, while also meeting the requirements of engineering parameters such as size.

[0036] This embodiment provides an optical system that effectively optimizes focal length and image quality. The focal length ratio f of the optical system is... w / f m =-11~-12 and focal length difference f w -|f m The ≤115mm aperture ensures a high magnification and excellent imaging quality, while the 60mm entrance pupil diameter (Φ0) enhances light throughput. Over a wide temperature range, this design effectively controls optical errors, preventing degradation in focal length and image quality due to temperature changes, thus maintaining the stability and reliability of signal reception. This compact and lightweight optical system meets the high-performance requirements of laser communication.

[0037] In one embodiment, from the light incident direction to the light exit direction... The convex surface radius of curvature of the first objective lens L3 is [100mm, 110mm], and the concave surface radius of curvature of the first objective lens L3 is [300mm, 400mm]. The radius of curvature of the first convex surface of the objective lens L4 is [70mm, 90mm], and the radius of curvature of the second convex surface of the objective lens L4 is [-500mm, -600mm]. The convex surface curvature radius of the cemented objective lens is [55mm, 65mm]; the cemented surface curvature radius of the cemented objective lens is [-200mm, -500mm]; the convex surface curvature radius of the cemented objective lens is [60mm, 90mm].

[0038] In one embodiment, from the light incident direction to the light exit direction... The convex surface radius of curvature of the first eyepiece lens L8 is [40mm, 50mm], and the concave surface radius of curvature of the first eyepiece lens L8 is [10mm, 20mm]. The radius of curvature of the first concave surface of the second eyepiece lens L9 is [-30mm, 40mm]; The radius of curvature of the second concave surface of the eyepiece second lens L9 is [25mm, 35mm].

[0039] In one embodiment, the center thickness of the first objective lens L3 is [4mm, 6mm], the center thickness of the second objective lens L4 is [8mm, 9.5mm], the air gap between the first objective lens L3 and the second objective lens L4 is [0.5mm, 1mm], the center thickness of the third objective lens L3 is [9mm, 10.5mm], the center thickness of the fourth objective lens L4 is [4.5mm, 5.5mm], and the air gap between the cemented objective lens and the central reflecting mirror L7 is [31mm, 32mm].

[0040] In one embodiment, the air gap between the central reflecting mirror L7 and the first eyepiece lens L8 is [43.7mm, 44.3mm], the center thickness of the first eyepiece lens L8 is [4mm, 5mm], the center thickness of the second eyepiece lens L9 is [2.3mm, 2.7mm], and the air gap between the first eyepiece lens L8 and the second eyepiece lens L9 is [4.5mm, 7mm].

[0041] This embodiment also provides a wide-temperature transmission telescope for an inter-satellite laser communication terminal, including the optical system described above. The performance parameters of the wide-temperature transmission telescope include: Field of view: ≥±3mrad; Aperture diameter: ≥60mm; Magnification: 11x~12x; Applicable temperature: -5℃ to 40℃; RMS wavefront error: RMS≤1 / 30λ@1550nm over the entire operating temperature range; Size restrictions: Height × Width ≤ 96mm × 95mm.

[0042] Specifically, the field of view (FOP) represents the observation range that a telescope can acquire. A FOP of ±3 mrad means that the telescope can effectively receive light signals within a certain range. This FOP is suitable for inter-satellite communication, allowing the antenna to have a certain degree of flexibility in conducting inter-satellite laser communication to cope with the relative motion and positional changes between satellites.

[0043] The aperture size refers to the diameter of a telescope, which directly affects the light-gathering capability and resolution of the optical system. A 60mm aperture size can effectively capture weak light signals, thereby enhancing communication reliability.

[0044] The magnification determines the image size of the target object. In interplanetary laser communication, an appropriate magnification can help the operator better align with the target satellite and ensure that the optical system can stably establish a connection with the target.

[0045] A wide temperature range means the telescope can operate stably under various environmental conditions, adapting to different space environments or ground conditions. This ensures that the telescope maintains its optical performance and mechanical integrity during operation, thus guaranteeing long-term reliability and stability.

[0046] RMS wavefront error is an important indicator for evaluating the imaging quality of a telescope. RMS≤1 / 30λ@1550nm means that the wavefront error of the telescope will not exceed 1 / 30 of the wavelength 1550mm. This means that the focusing ability and transmission efficiency of the beam can be significantly improved across the entire temperature range, with almost no aberrations, ensuring the consistency and high quality of the laser signal during transmission and reducing the bit error rate.

[0047] The telescope's compact size allows for easy integration into various space-constrained applications, such as satellites, and helps reduce the overall weight of the equipment, making launch and operation more economical and efficient.

[0048] This embodiment provides a wide-temperature transmission telescope for inter-satellite laser communication terminals. It achieves a high-performance, athermalized optical system design within the inter-satellite laser communication terminal, maintaining stability of focal length and image quality over a wide temperature range. Its field of view is ≥±3mrad, ensuring effective capture of a large field of view, thereby improving fault tolerance and communication reliability. A ≥60mm aperture enhances light collection capabilities, maintaining a high signal-to-noise ratio even in low-light environments, ensuring stable data transmission. An 11x to 12x magnification provides necessary detail magnification for target alignment, avoiding the problem of a narrow field of view. The applicable temperature range from -5℃ to 40℃ allows the telescope to operate normally under various environmental conditions, maintaining performance stability. Simultaneously, a wavefront error standard of RMS≤1 / 30λ@1550nm across the entire operating temperature range ensures extremely high imaging quality, effectively reducing signal distortion and improving the transmission quality of laser signals. Finally, its compact size of ≤96mm×95mm (height × width) facilitates integration, enhances portability, and reduces launch costs and operational complexity. These design parameters together provide a solid technical foundation for interplanetary laser communication.

[0049] Example 1 See also Figure 1 In this embodiment, the protective glass L1 is made of fused silica, with a cutoff wavelength of 2.5 mm except for the operating wavelength of 1550 nm ± 20 nm. The first objective lens L2 is also made of fused silica to further reduce the influence of electromagnetic and particle radiation from the space environment on the system; its thickness is 5.48 mm, equivalent to approximately 6 mm of aluminum. In this embodiment, the central reflecting mirror L7 is a plane mirror with a high-reflectivity coating, also made of fused silica, with a thickness of 6 mm. The central reflecting mirror L7 is located between the objective lens group and the eyepiece group, used to deflect the optical path, thereby reducing the telescope's size in the height direction and achieving a miniaturized design.

[0050] The second objective lens L3 is made of heavy crown glass, while the cemented objective lens consists of the third objective lens L5 and the fourth objective lens L6. The third objective lens L5 uses heavy phosphor crown glass, while the fourth objective lens L6 uses heavy flint glass. The first eyepiece lens L8 and the second eyepiece lens L9 also use heavy flint glass. The system structure is constructed of aluminum alloy. Notably, the fourth objective lens L6 has a refractive index of 1.95 and a dispersion coefficient of 17.9, which helps to shorten the air gap between the objective lens group and the eyepiece group—that is, the sum of the air gaps between the objective lens group and the central mirror L7, and between the central mirror L7 and the eyepiece group.

[0051] To achieve the design of a focusless telescope, the objective lens group and eyepiece group must satisfy the following conditions: f w / f m=-11.4, f w -|f m |=113.4mm, Φ0=60mm.

[0052] The table below shows the parameters of the optical system in the wide-temperature transmission telescope used for inter-satellite laser communication terminals in Example 1: Therefore, based on the various parameters, the dimensions of the telescope can be determined to be 94.56 mm in height and 88.4 mm in width. This allows for a further reduction in the height dimension of the optical system, while the width dimension connects to the rear optical path of the communication terminal.

[0053] Based on the parameters in Example 1, the optical system was simulated and tested, and the test results are as follows: Figures 2 to 4 As shown: like Figure 2 The graph shows the relationship between RMS wavefront error and field of view at different temperatures in Example 1. RMS wavefront error is a core quantitative indicator for evaluating the imaging quality of an optical system, and its value directly reflects whether the optical system meets the preset performance requirements. When the RMS wavefront error is lower than the diffraction limit λ / 25@1550nm, the imaging of the optical system is close to the ideal diffraction-limited state, which can achieve effective acquisition by the communication terminal. If the error exceeds the allowable threshold, it will affect the acquisition performance of the optical system. Within the full temperature operating range of this telescope, the RMS wavefront error is ≤1 / 30λ@1550nm. Therefore, it can be considered that the telescope can operate normally within the temperature range of -5℃ to 40℃.

[0054] like Figure 3 The diagram shows a dot plot of Example 1 at different temperatures and field angles. The diameter of the circle enclosed by the 80% energy level is smaller than the diameter of the diffraction-limited Airy disk, indicating that the optical system's imaging is close to ideal. The energy enclosed by the Airy disk diameter in the diagram shows that the telescope can operate normally within its operating temperature range.

[0055] like Figure 4 The image shows the axial chromatic aberration at 20°C for Example 1, with the wavelength range selected from 1530 nm to 1570 nm. Near a normalized aperture of 0.7, chromatic aberration is observed at 1530 nm and 1570 nm, indicating that chromatic aberration has no significant impact on the performance of the optical system.

[0056] It should also be noted that 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 limitation, 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 said element.

[0057] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0058] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

[0059] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An optical system, characterized in that, The optical system includes a protective glass, an aperture element, an objective lens group, a central mirror, and an eyepiece group; wherein... The objective lens group, from the light incident direction to the light exit direction, includes, in sequence: a first objective lens, a second objective lens, a third objective lens, and a fourth objective lens. The first objective lens is a meniscus lens with positive optical power and its concave surface facing the light exit direction. The second and third objective lenses are biconvex lenses with positive optical power. The fourth objective lens is a biconcave lens with negative optical power. The third and fourth objective lenses are combined to form a cemented objective lens. The eyepiece group includes, in sequence from the light incident direction to the light exit direction: a first eyepiece lens and a second eyepiece lens. The first eyepiece lens is a meniscus lens with negative optical power and its concave surface facing the light exit direction. The second eyepiece lens is a biconcave lens with negative optical power. The objective lens group and the eyepiece group satisfy the following conditions: f w / f m =-11~-12,f w -|f m |≤115mm,Φ0=60mm Among them, f w f is the focal length of the objective lens group. m Φ is the focal length of the eyepiece group, and Φ0 is the entrance diameter of the optical system.

2. The optical system according to claim 1, characterized in that, From the direction of light incidence to the direction of light emission The convex surface radius of curvature of the first objective lens is [100mm, 110mm], and the concave surface radius of curvature of the first objective lens is [300mm, 400mm]. The radius of curvature of the first convex surface of the objective lens is [70mm, 90mm], and the radius of curvature of the second convex surface of the objective lens is [-500mm, -600mm]. The convex surface curvature radius of the cemented objective lens is [55mm, 65mm]; the cemented surface curvature radius of the cemented objective lens is [-200mm, -500mm]; the convex surface curvature radius of the cemented objective lens is [60mm, 90mm].

3. The optical system according to claim 1, characterized in that, From the direction of light incidence to the direction of light emission The convex surface radius of curvature of the first eyepiece lens is [40mm, 50mm], and the concave surface radius of curvature of the first eyepiece lens is [10mm, 20mm]. The radius of curvature of the first concave surface of the second lens of the eyepiece is [-30mm, 40mm]; The radius of curvature of the second concave surface of the eyepiece second lens is [25mm, 35mm].

4. The optical system according to claim 1, characterized in that, The center thickness of the first objective lens is [4mm, 6mm], the center thickness of the second objective lens is [8mm, 9.5mm], the air gap between the first and second objective lenses is [0.5mm, 1mm], the center thickness of the third objective lens is [9mm, 10.5mm], the center thickness of the fourth objective lens is [4.5mm, 5.5mm], and the air gap between the cemented objective lens and the central reflecting mirror is [31mm, 32mm].

5. The optical system according to claim 1, characterized in that, The air gap between the central reflector and the first eyepiece lens is [43.7mm, 44.3mm], the center thickness of the first eyepiece lens is [4mm, 5mm], the center thickness of the second eyepiece lens is [2.3mm, 2.7mm], and the air gap between the first eyepiece lens and the second eyepiece lens is [4.5mm, 7mm].

6. The optical system according to claim 1, characterized in that, The first objective lens is made of radiation-resistant glass, the second objective lens is made of heavy crown glass, the third objective lens is made of heavy phosphorus crown glass, and the fourth objective lens is made of heavy flint glass.

7. The optical system according to claim 1, characterized in that, The first and second lenses of the eyepiece are made of heavy flint glass.

8. The optical system according to claim 1, characterized in that, The protective glass is made of radiation-resistant glass, and the central reflector is made of fused silica or microcrystalline glass.

9. A wide-temperature transmission telescope for inter-satellite laser communication terminals, characterized in that, Includes the optical system as described in any one of claims 1 to 8.

10. The wide-temperature transmission telescope for inter-satellite laser communication terminals according to claim 9, characterized in that, The performance parameters of the wide-temperature transmission telescope include: Field of view: ≥±3mrad; Aperture diameter: ≥60mm; Magnification: 11x~12x; Applicable temperature: -5℃ to 40℃; RMS wavefront error: RMS≤1 / 30λ@1550nm over the entire operating temperature range; Size restrictions: Height × Width ≤ 96mm × 95mm.

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