An external occulting stabilised coronagraph

Abstract

The present application relates to the field of astronomical, space science and solar observation coronagraph instrument, especially relates to a kind of external mask type image stabilization coronagraph, it includes in turn: external mask, heat rejection mirror, objective lens group, field stop, field lens, Lyot diaphragm, image converter group and linear polarizer, it further includes: image stabilization device, the image stabilization device includes: image stabilization lens group, guide mirror and image stabilization lens adjusting mechanism, wherein, the image stabilization lens group is located between objective lens group and field stop;The guide mirror is set to the incident light path direction parallel to external mask outside external mask, for collecting solar azimuth and solar elevation angle optical signal, obtains solar pointing deviation signal;The image stabilization lens adjusting mechanism is based on solar pointing deviation signal, adjusts the pose of image stabilization lens group, to compensate solar pointing deviation.The present application combines high-precision imaging and image stabilization technology organically, significantly improves the observation performance of coronagraph, provides reliable technical support for the research of solar activity and coronal structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coronagraphic instruments for astronomy, space science and solar observation, and in particular to an external occulting stabilized coronagraph. BACKGROUND

[0002] A coronagraph is a specialized astronomical instrument used for observing the solar corona, which is of great significance for studying solar activity and its impact on the Earth's space environment. Traditional coronagraphs mainly block the strong light of the sun through internal optical elements to observe the relatively dim corona structure. However, these traditional coronagraphs often face many challenges in practical applications, including poor imaging stability, insufficient resolution, and image jitter caused by environmental disturbances.

[0003] On the one hand, due to factors such as vibration of the mounting platform, atmospheric disturbance, and movement of the instrument itself, the coronal image is prone to jitter and blurring, which seriously affects the observation quality and the accuracy of the data.

[0004] In order to solve these problems, researchers have been exploring new technical means to enhance the imaging stability and resolution of coronagraphs. SUMMARY

[0005] The purpose of the present application is to overcome the above-mentioned defects of the prior art, and to provide an external occulting stabilized coronagraph.

[0006] To solve the above technical problems, the technical solution of the present application provides an external occulting stabilized coronagraph, which comprises, in sequence: an external occulting body, a heat rejection mirror, an objective lens group, a field stop, a field lens, a Lyot stop, an image converter lens group, and a linear polarizer, and further comprises a stabilization device, which comprises a stabilization lens group, a guide mirror, and a stabilization lens adjustment mechanism, wherein,

[0007] The stabilization lens group is located between the objective lens group and the field stop;

[0008] The guide mirror is arranged outside the external occulting body and parallel to the incident light path direction of the external occulting body, and is used to collect solar azimuth and solar elevation angle optical signals to obtain a solar pointing deviation signal;

[0009] The stabilization lens adjustment mechanism adjusts the pose of the stabilization lens group based on the solar pointing deviation signal to compensate for the solar pointing deviation.

[0010] Preferably, the guide mirror comprises a four-quadrant detector, wherein when a solar pointing deviation occurs, the four-quadrant detector generates an electrical signal deviation, and after processing, a solar pointing deviation signal is obtained.

[0011] Preferably, the guide mirror further comprises a filter for selecting a specific wavelength and an optical assembly for focusing.

[0012] Preferably, the image-stabilizing mirror set comprises an image-stabilizing main mirror and an image-stabilizing backup mirror; both the image-stabilizing main mirror and the image-stabilizing backup mirror are plane mirrors, and the outgoing light of the objective lens set is reflected by the image-stabilizing main mirror and the image-stabilizing backup mirror in sequence and then is directed to the field diaphragm.

[0013] Preferably, the image-stabilizing mirror adjusting mechanism comprises a piezoelectric ceramic, wherein the piezoelectric ceramic adjusts the pose of the image-stabilizing main mirror or / and the image-stabilizing backup mirror based on the sun pointing deviation signal, so as to adjust the relative angle between the image-stabilizing main mirror and the image-stabilizing backup mirror, compensate for the sun pointing deviation, and thus complete image stabilization; the pose comprises a position and a facing angle.

[0014] Preferably, the outer shield is used to shield the light of the sun's disk; and the objective lens set is used to reflect the direct light of the sun so that the direct light of the sun enters the objective lens set at a predetermined light angle.

[0015] Compared with the prior art, the advantages of the present application are that the present application provides an outer-shielded image-stabilized coronagraph, which effectively eliminates image jitter caused by environmental interference by introducing image stabilization technology, and can maintain high precision and high stability of the image. The system uses an outer shield design to effectively shield the light of the sun's disk, thereby improving the clarity of coronal observation. In addition, the image-stabilizing device can monitor and correct the position and angle changes of the imaging device in real time, ensuring that clear and stable images are obtained at all times during long-term observation.

[0016] The present application significantly improves the observation performance of the coronagraph by organically combining high-precision imaging and image stabilization technology, and provides reliable technical support for the study of solar activity and coronal structure. It is not only suitable for ground-based observation platforms, but also can be popularized to space probes, and opens up a new application space for the frontier research of solar physics. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic diagram of the outer-shielded image-stabilized coronagraph;

[0018] Figure 2 is a schematic diagram of the outer-shielded image-stabilized coronagraph;

[0019] Figure 3 is a partial enlarged view of the outer-shielded image-stabilized coronagraph;

[0020] Fig. 4(a) is a 540 nm point column diagram;

[0021] Fig. 4(b) is a 590 nm point column diagram;

[0022] Fig. 4(c) is a 640 nm point column diagram. DETAILED DESCRIPTION

[0023] The technical solutions provided by the present application are further illustrated below in combination with embodiments.

[0024] The embodiment provides an outer-shielded image-stabilized coronagraph, and the core function of the system is to realize high-precision observation of the solar corona through an outer-shielded device and an image-stabilized technology. The image-stabilized device is used for reducing or eliminating image jitter caused by instrument vibration or external interference, thereby improving the stability and clarity of coronal imaging. This technology can be widely applied to ground-based coronal observation stations, space probes and other scientific equipment that needs high-precision solar observation, and provides high-quality data support for the research of solar physics.

[0025] The outer-shielded image-stabilized coronagraph provided by the embodiment mainly comprises a guide mirror, an outer shield, a heat-rejecting mirror, an objective lens, a main image-stabilized mirror, a backup image-stabilized mirror, a piezoelectric ceramic, a field-of-view diaphragm, a field lens, a Lyot diaphragm, an image inverter and a linear polarizer, as shown in Figure 1 、 Figure 2 and Figure 3 .

[0026] The guide mirror is composed of a filter, an optical assembly and a four-quadrant detector. The filter can select a specific wavelength, the optical assembly can be used for focusing, and the four-quadrant detector can detect the deviation of the pointing direction of the sun. The addition of the image-stabilized design ensures the clarity and stability of the image, and effectively solves the problems of inaccurate pointing and non-jittering platform in the traditional coronagraph.

[0027] The guide mirror is designed to use a four-quadrant detector silicon photodiode to collect light signals in the azimuth and elevation directions of the sun. When the pointing direction of the sun is accurate, the four-quadrant silicon photodiode signal has consistent intensity. When there is a deviation, the silicon photodiode will generate an electrical signal deviation. After signal processing, the signal deviation is used to drive the pointing accuracy adjustment, and the piezoelectric ceramic is controlled. The piezoelectric ceramic adjusts the main image-stabilized mirror and the backup image-stabilized mirror, and adjusts the position and angle of the lens to ensure the clarity and stability of the image during observation.

[0028] The image-stabilized technology of the system not only significantly improves the image clarity and resolution of coronal observation, enhances the observation accuracy, but also makes it adapt to complex conditions in the ground and space environment, provides wide applicability and reliability, and realizes high-precision imaging.

[0029] The light path of the system is as follows: the coronal light first passes through the outer eclipse body to effectively shield the solar surface light, the heat rejection mirror returns the direct sunlight from the surface of the sun, the objective lens set collects the coronal light to form an image surface, and a field stop is arranged at the primary image surface. The pointing signal deviation is adjusted by the guide mirror to adjust the position and angle of the image stabilization main mirror and the image stabilization backup mirror in real time to eliminate the preliminary shaking and vibration. The field stop is used to preliminarily suppress the stray light in the field of view, and then the Lyot stop is used to further suppress the multi-stage stray light such as structural scattering, aperture diffraction and lens reflection. The image is formed by the erecting image forming through the relay lens set, the linear polarizer selects the light of a specific polarization state to eliminate the interference of the polarization stray light, and finally the light reaches the imaging image surface to form a stable, erect and clear image.

[0030] The components of the system will be described in detail as follows:

[0031] 1. The outer eclipse body and the heat rejection mirror: the outer eclipse body shields the light from the solar surface to avoid the light from the solar surface entering the optical system; the heat rejection mirror reflects the direct sunlight from the sun to allow only specific light angles to enter the objective lens.

[0032] 2. The guide mirror: the field of view of the guide mirror is the solar angle, and the signal deviation of the four-quadrant detector is used to drive the piezoelectric ceramic to adjust the image stabilization main mirror and the image stabilization backup mirror to complete the image stabilization.

[0033] 3. The piezoelectric ceramic: the position and angle of the image stabilization main mirror and the image stabilization backup mirror can be adjusted.

[0034] 4. The objective lens: the objective lens set is used to preliminarily collect the light from the sun to form a primary image surface for setting the field stop.

[0035] 5. The image stabilization main mirror and the image stabilization backup mirror: both are plane mirrors and realize image stabilization through fine adjustment mechanism. The image stabilization main mirror and the image stabilization backup mirror cooperate with each other to quickly compensate for the pointing error of the sun caused by external vibration, platform instability or environmental disturbance to ensure the stability and clarity of the image during observation. Through the design of double mirror image stabilization, the anti-interference ability of the system is effectively improved.

[0036] 6. The field lens: adjusts the light path to realize a more compact design and reduce the length of the optical system.

[0037] 7. The field stop: used to suppress the light outside the field of view from entering the optical system to avoid the generation of field stray light.

[0038] 8. The Lyot stop: arranged at the exit pupil of the field lens, which can realize multi-stage stray light suppression design to further eliminate the stray light caused by structural scattering, aperture diffraction and lens reflection.

[0039] 9. Turnaround mirror group: The design of the turnaround mirror group can improve the imaging quality of the optical system and realize image rotation, and the image on the detector surface is an upright image.

[0040] 10. Linear polarizer: By controlling the polarization state of light, the influence of polarized stray light is reduced, and the clarity of the observed image is improved.

[0041] Figures 4(a)-4(c) The spot RMS radius of different wavelengths is shown.

[0042] Figure 4(a) shows the 540nm point column diagram, and the specific data is shown in Table 1:

[0043] Table 1:

[0044]

[0045] Figure 4(b) shows the 590nm point column diagram, and the specific data is shown in Table 2:

[0046] Table 2:

[0047]

[0048] Figure 4(c) shows the 640nm point column diagram, and the specific data is shown in Table 3:

[0049] Table 3:

[0050]

[0051] From Figures 4(a)-4(c) It can be seen that the external mask type image stabilization coronagraph provided in the embodiment achieves good results.

[0052] As can be seen from the above technical solution, the external mask type image stabilization coronagraph provided by the present application can effectively realize the acquisition of clear and stable images during long-time observation, and provides a new solution for precise observation of solar activity, and has the following advantages:

[0053] 1. Image stability: By introducing the image stabilization device, the image distortion problem caused by atmospheric disturbance and instrument micro-jitter and other factors is effectively eliminated, the stability of the image during observation is ensured, and the clarity is improved.

[0054] 2. Low stray light effect: The system design includes external mask, heat rejection mirror, field diaphragm, Lyot diaphragm and linear polarizer and other measures to suppress stray light, which effectively suppresses the stray light reaching the image surface to interfere with the signal.

[0055] 3. High-precision imaging: High-performance anti-reflection coating and precision-processed optical components are adopted, and the surface roughness of the optical elements is controlled to be below 2nm in RMS, which significantly reduces the stray light caused by scattering and reflection of light, thereby improving the overall system stray light suppression level.

[0056] 4. Wide application: The optical system design of the present application enables the coronagraph to output high-precision imaging under platform jitter and atmospheric disturbance, which is suitable for various astronomical observation and research needs, thereby expanding the application range of the coronagraph.

[0057] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the examples, those skilled in the art should understand that modifications or equivalent replacements of the technical solutions of the present application do not deviate from the spirit and scope of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. An externally occulting stabilized coronagraph comprising, in order: The outer mask, heat-rejection mirror, objective lens group, field stop, field lens, Lyot stop, relay lens group and linear polarizer further comprise a stabilizing device, which comprises a stabilizing lens group, a guide mirror and a stabilizing lens adjusting mechanism, wherein The stabilizing lens group is located between the objective lens group and the field stop; The guide mirror is arranged outside the outer mask and parallel to the incident light path direction of the outer mask, and is used to collect solar azimuth and solar elevation angle optical signals to obtain a solar pointing deviation signal; The stabilizing lens adjusting mechanism adjusts the pose of the stabilizing lens group based on the solar pointing deviation signal to compensate for the solar pointing deviation; The stabilizing lens group comprises a stabilizing main mirror and a stabilizing backup mirror; both the stabilizing main mirror and the stabilizing backup mirror are plane mirrors, and the outgoing light of the objective lens group is reflected by the stabilizing main mirror and the stabilizing backup mirror in sequence and then is directed to the field stop.

2. The externally occulting stabilized coronagraph of claim 1, wherein, The guide mirror comprises a four-quadrant detector, wherein when the solar pointing deviation occurs, the four-quadrant detector generates an electrical signal deviation, and after processing, the solar pointing deviation signal is obtained.

3. The externally occulting stabilized coronagraph of claim 1, wherein, The guide mirror further comprises a filter for selecting a specific wavelength and an optical assembly for focusing.

4. The externally occulting stabilized coronagraph of claim 1, wherein, The stabilizing lens adjusting mechanism comprises a piezoelectric ceramic, wherein the piezoelectric ceramic adjusts the pose of the stabilizing main mirror or / and the stabilizing backup mirror based on the solar pointing deviation signal, thereby adjusting the relative angle between the stabilizing main mirror and the stabilizing backup mirror, compensating for the solar pointing deviation, thereby completing the stabilization; the pose comprises a position and a facing angle.

5. The externally occulting stabilized coronagraph of claim 1, wherein, The outer mask is used to shield the light of the solar disk; and the objective lens group is used to reflect the direct light of the sun so that the direct light of the sun enters the objective lens group at a predetermined light angle.

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