A solar adaptive telescope

Abstract

The application discloses a solar adaptive telescope, which comprises a primary mirror, a secondary mirror, a front mirror group, a wavefront corrector, a rear mirror group, a beam splitter, an observation system, a wavefront sensor and a wavefront controller. The wavefront corrector is placed in the pupil conjugate position of the folded light path of the telescope, so that the high integration of the solar telescope and the adaptive optical system is realized. Compared with the method of transforming the secondary mirror or the third mirror and the fourth mirror into a high-precision deformable secondary mirror, the original telescope main structure is not changed, and only the folded light path of the original telescope needs to be reasonably adjusted, so that the redesign and structural transformation of the support and thermal control system caused by the use of the complex deformable secondary mirror are avoided. The application has the advantages of wide application range, strong flexibility, simplified optical system structure, reduced number of optical elements and the like, and can effectively reduce the system inherent aberration and stray light and improve the solar energy utilization efficiency.

Description

Technical Field

[0001] This invention belongs to the field of adaptive optics technology, specifically relating to a solar adaptive telescope. Background Technology

[0002] When ground-based large-aperture solar telescopes perform high-resolution imaging of the solar atmosphere (including the photosphere, chromosphere, and corona), the theoretical diffraction-limited resolution is consistently and severely constrained by atmospheric turbulence. Atmospheric turbulence causes dynamic phase distortion of the incident wavefront, resulting in a degradation of the actual imaging resolution, which is far below the telescope's theoretical diffraction-limited resolution.

[0003] To overcome the limitations of atmospheric seeing, adaptive optics (AO) systems have been introduced as a crucial calibration link between telescopes and scientific terminals. The core components of an AO system include a wavefront sensor, a wavefront controller, and a wavefront corrector. The wavefront sensor measures the distortion of the light wavefront, and the wavefront controller sends commands based on the sensor's feedback to adjust the mirror shape of the wavefront corrector to compensate for the distortion. In an AO system, to ensure that the deformable mirror can most effectively and accurately correct wavefront aberrations, the optical plane containing its mirror must be positionally conjugate to the pupil plane containing the wavefront to be corrected. This positional conjugation ensures that a small area on the deformable mirror surface corresponds to a specific, localized wavefront region on the pupil plane. Thus, the actuator's correction of this region can most directly and effectively compensate for the wavefront error in that localized area.

[0004] To achieve a high degree of integration between adaptive optics systems and solar telescopes, and to realize high-resolution imaging of the sun with a large field of view, current adaptive optics solar telescopes often employ a technical solution where the secondary mirrors, third or fourth mirrors, etc., of the solar telescope are designed as deformable secondary mirrors. A wavefront controller uses feedback from the wavefront detector to precisely control and adjust the actuators of the deformable secondary mirrors, changing the mirror shape in real time to compensate for and correct wavefront aberrations in front of the focal point. Essentially, in adaptive solar telescopes based on deformable secondary mirrors, the deformable secondary mirror serves both as part of the telescope's optical structure and as a wavefront corrector within the adaptive optics system, thus achieving a high degree of integration between the two.

[0005] Adaptive optics systems theoretically enable near-diffraction-limited imaging by using wavefront sensors to detect distortion in real time and deformable mirrors to dynamically compensate for aberrations. However, existing solar adaptive optics systems face two major structural challenges:

[0006] Optical path complexity drawbacks: In solar telescopes, deformable mirrors are typically located behind the telescope's imaging focal point. Wavefront distortion information measured by wavefront sensors is used by a wavefront controller to accurately control the deformable mirror for effective compensation. However, traditional discrete AO correction systems (including tilt mirrors, deformable mirrors, and relay lens groups) are limited by their structure. The system has a large number of refractive and reflective interfaces, which significantly reduces the overall transmittance and increases the risk of additional assembly misalignment aberrations (such as astigmatism) and chromatic aberration. In addition, under strong solar radiation, multi-mirror thermal deformation will exacerbate the difficulty of the telescope's system thermal management.

[0007] The Challenges of Modifying Secondary Mirrors: To achieve high-resolution imaging of the sun with a wide field of view, some solutions involve modifying the telescope's secondary mirrors or third and fourth mirrors into deformable secondary mirrors. This allows for wavefront compensation of incident sunlight in front of the imaging focal point. However, this modification requires redesigning and fabricating the mirror surface to be modified, deploying a sufficient number of deformable mirror actuators to ensure the accuracy of wavefront aberration correction, and precisely controlling the actuators for real-time correction. The high precision and fast response characteristics place extremely high demands on the design, fabrication, and construction of deformable secondary mirrors. Correspondingly, the telescope's support structure and thermal control system must meet the requirements of maintaining the deformation accuracy of the deformable secondary mirror under complex thermal environments. This places stringent demands on the durability of relevant materials and the stability of the mechanical structure and thermal control system under different environments. The amount of telescope modification work increases significantly, making it difficult to implement and costly. Summary of the Invention

[0008] To overcome the problems of high complexity, low energy utilization, and high cost and difficulty in modifying deformable secondary mirrors in traditional solar adaptive telescopes, this invention proposes a solar adaptive telescope. This solar telescope is highly integrated with an adaptive optics system, simplifying the telescope's structural design and reducing the number of components without increasing the overall complexity of the telescope. This avoids the problem of increased energy loss due to a large number of reflection and refraction interfaces. Compared to modifying the secondary mirrors or third and fourth mirrors of the telescope into deformable secondary mirrors, the modification of constructing the pupil conjugate position in the folding optical path is less difficult, less costly, and more flexible. It is compatible with various reflecting and catadioptric solar telescopes and has broad application prospects.

[0009] The technical solution adopted in this invention is: a solar adaptive telescope, comprising: a primary mirror, a secondary mirror, a front reflecting mirror assembly, a wavefront corrector, a rear reflecting mirror assembly, a beam splitter, an observation system, a wavefront sensor, and a wavefront controller. The primary mirror receives incident sunlight from various directions and focuses the incident beam onto the secondary mirror. The secondary mirror reflects the light converged by the primary mirror to the front reflecting mirror assembly. The front reflecting mirror assembly performs initial transmission and direction adjustment of the incident light and constructs a pupil plane conjugate position, placing the wavefront corrector on the conjugate plane of the telescope's entrance pupil. This allows for real-time correction and compensation of the wavefront at the entrance pupil by accurately controlling the shape of the mirror. The rear reflecting mirror group then transmits the wavefront-corrected light to the beam splitter. At the beam splitter, the beam is split into two paths: one path is transmitted to the observation system for final scientific observation, and the other path is transmitted to the wavefront sensor. The wavefront sensor measures the wavefront aberration of the pupil surface in real time. The wavefront controller generates a correction signal to drive the wavefront corrector to control the shape change of the mirror, thus achieving "closed-loop" adaptive optics control and synchronously and dynamically compensating for tilt aberration and higher-order aberrations.

[0010] The expected beneficial effects of this invention are as follows:

[0011] Using this invention, the structure of the telescope can be simplified without increasing the overall complexity of the telescope, effectively reducing the number of optical components in the telescope system, avoiding the problem of increased energy loss due to a large number of reflection and refraction interfaces, and improving the energy utilization efficiency of incident sunlight.

[0012] Using this invention, a solar telescope can be constructed without altering its structure (such as the telescope's secondary mirror) or adding additional upgrades or modifications. Compared to modifying the secondary mirror or third / fourth mirror into a deformable secondary mirror, the modification requirement of constructing the pupil conjugate position in the optical path is less difficult, less costly, and more flexible. It is also compatible with a variety of reflecting and catadioptric solar telescopes, making it widely applicable. Attached Figure Description

[0013] Figure 1 This is a block diagram illustrating the principle of a solar adaptive telescope system according to the present invention.

[0014] Figure 2 This is an example of an adaptive optics integrated design for a Gregorian-style ground-based solar telescope based on the present invention. Detailed Implementation

[0015] 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.

[0016] Figure 1 This is a block diagram illustrating the principle of a solar adaptive telescope system according to the present invention. The following is in conjunction with... Figure 1 The present invention is described. In the description, an adaptive optics integrated design of a certain Gregorian-style ground-based solar telescope is used as an example for illustration.

[0017] like Figure 1 As shown, the solar adaptive telescope includes a primary mirror 1, a secondary mirror 2, a front mirror assembly 3, a wavefront corrector 4, a rear mirror assembly 5, a beam splitter 6, an observation system 7, a wavefront sensor 8, and a wavefront controller 9. The primary mirror 1 receives incident sunlight from various directions and focuses the incident beam onto the secondary mirror 2. The secondary mirror 2 reflects the light converged by the primary mirror to the front mirror assembly 3. The front mirror assembly 3 performs initial transmission and direction adjustment of the incident light and constructs the conjugate position of the pupil plane. The wavefront corrector 4 is placed on the conjugate plane of the telescope's entrance pupil, thereby... Accurate control of the mirror shape enables real-time correction and compensation of the wavefront at the entrance pupil. The rear reflecting mirror group 5 further transmits the wavefront-corrected light to the beam splitter 6. At the beam splitter 6, the beam is split into two paths. One path is transmitted to the observation system 7 for final scientific observation, and the other path is transmitted to the wavefront sensor 8. The wavefront sensor 8 measures the wavefront aberration of the pupil surface in real time. The wavefront controller 9 generates a correction signal to drive the wavefront corrector 4 to control the shape change of the mirror, realizing "closed-loop" adaptive optics control and synchronously and dynamically compensating for tilt aberration and higher-order aberrations.

[0018] The solar telescope has a reflective or catadioptric structure. When it is a reflective telescope, the primary mirror 1 and the secondary mirror 2 form a Gregorian or Cassegrain structure. The optical surface shape and support structure of the secondary mirror 2 or other third or fourth mirrors that are equivalent to the secondary mirror do not need to be modified. When it is a catadioptric telescope, one or more refractive lenses for correction are usually arranged in front of the primary mirror 1. The pupil conjugate position is generated in the refracting optical path behind the primary mirror 1, the secondary mirror 2 and the front reflecting mirror group 3. The wavefront corrector 4 is deployed to achieve adaptive optics integration.

[0019] Both the front reflector group 3 and the rear reflector group 5 consist of at least one planar or curved reflector, used to construct the conjugate position of the pupil plane and the optical path deflection. The specific number and parameters are determined by the specific application design.

[0020] The wavefront corrector 4 includes two independent devices, a tilt corrector and a higher-order wavefront corrector, or a single corrector that can simultaneously compensate for tilt aberrations and higher-order aberrations.

[0021] The wavefront corrector 4 is implemented by a discrete wavefront corrector and a tilting mirror; the tilting mirror is located in the downstream optical path of the wavefront corrector and is used to correct the new optical path deviation caused by the introduction of the wavefront corrector.

[0022] The observation system 7 is the scientific observation terminal of the telescope, which can be connected to different solar spectral lines or image observation optical paths according to actual observation needs.

[0023] The wavefront sensor 8 is selected from at least one of the following types: Shaker-Hartmann wavefront sensor, curvature wavefront sensor, shear interference wavefront sensor, pyramidal wavefront sensor, etc.

[0024] The real-time control algorithms used by the wavefront controller 9 include, but are not limited to, proportional-integral (PI) control algorithms, linear quadratic Gaussian (LQG) control algorithms, predictive control algorithms, and other adaptive optics real-time control algorithms.

[0025] like Figure 2 As shown, the basic optical path of an adaptive integrated design for a certain Gregorian ground-based solar telescope includes: primary mirror 1, secondary mirror 2, reflector M3, reflector M4, wavefront corrector M5, tilt mirror M6, reflector M7, reflector M8, beam splitter M9, observation system M10, wavefront sensor M11, and wavefront controller M12.

[0026] In the adaptive integration design of this Gregorian-style ground-based solar telescope, mirrors M3 and M4 correspond to... Figure 1 The front reflecting mirror assembly, with wavefront corrector M5 corresponding to tilt mirror M6. Figure 1 Wavefront corrector 4, corresponding to mirrors M7 and M8 Figure 1 The rear mirror group 5; at the telescope's observation system M10, the deployment of the multi-channel imaging system and the multi-channel, high-dispersion spectrometer was simplified, aiming to highlight the integrated design of adaptive optics and the solar telescope. The adaptive integration modification of this Gregorian solar telescope, considering actual telescope modification conditions, in... Figure 2 The wavefront corrector M5 shown replaces the original telescope's reflector, ensuring that the wavefront corrector's mirror surface is conjugate to the telescope's entrance pupil. The tilting mirror M6 is used to correct the modified optical path, keeping the telescope's focal plane in its original position.

[0027] This modification scheme achieves adaptive optics integration modification of the solar telescope by constructing a pupil conjugate position in the refractive optical path of the solar telescope and placing a wavefront corrector. This modification scheme does not require adjustment or redesign of the subsequent optical path and other structures of the telescope, and the modification difficulty is small. Moreover, compared with the traditional adaptive optics process of splitting the optical path at the rear of the telescope focal plane to run the adaptive optics system, the modification scheme described in this invention simplifies the structural design of the telescope, effectively reduces the introduction of refraction and reflection interfaces in the overall telescope, and improves the energy utilization rate of incident sunlight.

[0028] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0029] It should be pointed out that, Figure 2 Only one possible implementation has been given. Based on the implementation method proposed in this invention, there are infinitely many possible implementations. As long as they satisfy the basic characteristics of this invention, they are all covered within the protection scope of this invention. The above description is only one specific embodiment of this invention, and the specific protection scope of this invention should be determined by the scope of the claims.

Claims

1. A solar adaptive telescope, characterized by, It comprises: The main mirror (1), the secondary mirror (2), the front mirror group (3), the wavefront corrector (4), the rear mirror group (5), the beam splitter (6), the observation system (7), the wavefront sensor (8) and the wavefront controller (9), wherein the main mirror (1) receives incident sunlight from all directions and focuses the incident light beam to the secondary mirror (2), the secondary mirror (2) reflects the light rays converged by the main mirror to the front mirror group (3), the front mirror group (3) performs preliminary transmission and direction adjustment on the incident light and constructs the pupil conjugate position, the wavefront corrector (4) is placed on the conjugate plane of the telescope entrance pupil, so that the wavefront at the entrance pupil is compensated in real time by accurately controlling the mirror shape of the wavefront corrector (4), the rear mirror group (5) further transmits the light rays after wavefront correction to the beam splitter (6), at the beam splitter (6), the light beam is divided into two paths, one path is transmitted to the observation system (7) for final scientific observation, and the other path is transmitted to the wavefront sensor (8), the wavefront sensor (8) measures the wavefront aberration of the pupil in real time, generates a correction signal through the wavefront controller (9) to drive the wavefront corrector (4) to control the shape change of its mirror, and realizes "closed loop" adaptive optical control, synchronous dynamic compensation of tilt aberration and high-order aberration; The structure of the solar adaptive telescope is a reflective or catadioptric structure; when it is a reflective structure, the main mirror (1) and the secondary mirror (2) form a Gregorian structure; when it is a catadioptric structure, one or more refractive lenses are arranged in front of the main mirror (1) for correction, the pupil conjugate position is generated in the folded light path after the main mirror (1), the secondary mirror (2) and the front mirror group (3), and the wavefront corrector (4) is deployed to realize adaptive optical integration; The front mirror group (3) and the rear mirror group (5) are each composed of at least one plane or curved mirror, which is used to construct the pupil conjugate position and the folded light path; The wavefront corrector (4) comprises two independent devices of a tilt corrector and a high-order wavefront corrector, or a single correction device that can simultaneously compensate tilt aberration and high-order aberration; The wavefront corrector (4) is realized by a separate wavefront corrector and a tilt mirror, which is located in the downstream light path of the wavefront corrector and is used to correct the newly introduced light path deviation caused by the wavefront corrector.

2. The solar adaptive telescope of claim 1, wherein, The observation system (7) is the scientific observation terminal of the telescope, which accesses different solar spectral lines or image observation light paths according to actual observation requirements.

3. The solar adaptive telescope of claim 1, wherein, The wavefront sensor (8) is selected from at least one of the following types: Shack-Hartmann wavefront sensor, curvature wavefront sensor, shear interferometer wavefront sensor and pyramid wavefront sensor.

4. The solar adaptive telescope of claim 1, wherein, The real-time control algorithm adopted by the wavefront controller (9) includes proportional-integral control algorithm, linear quadratic Gaussian control algorithm and predictive control algorithm.

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