This PDF file contains the front matter associated with SPIE Proceedings Volume 13505, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Large width and low distortion were the two developing trends of space remote technique. An isometric scanning system was introduced. The scanning field of view was in front of the sub-satellite point. The width of the camera was about 2006km when the orbit altitude of satellite was 705km. The distortion of the camera image was 29.3%.

Spectrograph is one of the most important tools in astronomical observation and can be used in research areas ranging from cosmology to exoplanet research. Conventional astronomical spectrograph using a diffraction grating is huge, posing great challenges to their thermal and mechanical stability, and they are also very expensive. This inevitably determines the need for new original innovations in future optical and near-infrared spectrograph technologies. The application of photonics in astronomical spectrograph in recent years has shown a great potential for miniaturizing the spectrograph which is mounted on the large telescopes. The new dispersion element named waveguide spectral lens (WSL)is proposed by Westlake University that different from the independent optical element in the conventional spectrograph, and it can realize the dual functions of both wavelength separation and focus. This kind of chip technology makes the structure more compact, and improves the design to expand the devices working in the communication band to the visible and near-infrared band, enabling the spectrograph based on this new technology to achieve astronomical observation in the visible band in the future. In order to fully understand the performance of this new dispersion element and its application potential in astronomy, we established two chip test platforms in the optical laboratory of Shanghai Astronomical Observatory, and analyzed the dispersion capability of the device by using the wavelength calibration method. In order to expand the range of the spectra, the two-dimensional cross-dispersion spectrum was realized by adding a cylindrical lens and a blazed grating in the laboratory. The solar spectrum is also observed using these two chips. The experimental results show that this new optical waveguide chip can be applied to the visible light band, and can be used as the dispersion element of astronomical spectrograph for astronomical applications. At present, the optical and mechanical design of the prototype of the spectrograph has been completed. In the future, the laboratory installation of the prototype will be completed to realize the on-sky observation as soon as possible.

In recent years, the Resident Space Objects in Low Earth Orbit (LEO) have been dramatically increased due to space activities which may cause the risk of collision by its large populations. Thus, Space Traffic Management (STM) is a significant solution to space technology development as it guarantees safety. Radar sensor systems have emerged as pivotal tools for space objects monitoring. LeoLabs is a commercial provider of space object detection and monitoring services, operating via their global distributed radar network. Their space radar network system, which consists of Phased-array radars, serves as a measurement tool for space services related to STM in LEO, including tracking and mapping space objects, issuing real-time conjunction alerts, and supporting spacecraft launches. This system presents various noteworthy aspects at both individual radar sites and the network cooperation scale. Hence, this article is going to introduce the LeoLabs radar information from our literature review which includes overall system architecture, briefly radar sites information, system performance, etc.

Solar activity is the source of variations in the solar-terrestrial space environment and disturbs the Earth's magnetic field in various forms. The corona is the most active region of the sun, and its impact on the earth and human beings is also the most intense. The temperature of the corona is 2~3 orders of magnitude higher than the temperature of the photosphere in its inner layer, and the reason how it heats has constantly been a mystery in the field of solar physics. Direct imaging observations of the corona are of great significance for the study of coronal mass ejection (CME) and coronal heating mechanisms. Measurement of the abundance of elemental helium, which is the largest contributor to the density of the coronal plasma next only to hydrogen, could further study the corona and understand the origin and acceleration mechanism of the solar wind sufficiently, however, implementing high-precision measurement of helium abundance on the global scale currently is a severe technical challenge. In this paper, the helium abundance of the sun served as the research object, comparing the international mainstream coronagraph models and basic optical architecture, designed an extreme ultraviolet external occulter (EO) coronagraph, which has a field of view of 1.4~4R☉, with a working wave of 30.4nm for observing helium abundance, aperture of 40mm, focal length of 420mm, and spatial resolution of 7.37arcsec.In this paper, the diffraction of stray light caused by the external occulter of the coronagraph system is studied. Aiming at the external occulter of a single disk and a triple disk, The uniform boundary wave theory is used to study the theory, and the simulation experiments are carried out. it is obtained that the external occulter of a triple disk can effectively reduce the diffraction intensity by 2 ~ 3 orders of magnitude compared with the external occulter of a single disk. On the basis that the external occulter is a triple disk, a method to suppress the diffracted stray light is proposed in this paper, by which the diffraction stray light is blocked by the feasible design of the position and size of the inner occulter (IO). The diffraction stray light formed by the aperture opening of the heat rejection mirror is also suppressed, to suppress the diffracted light of the coronagraph system effectively, which lays an excellent foundation for the prototype production of coronagraph and the experimental measurement of stray light in the immediate future.

The adaptive telescope based on a deformable secondary mirror can effectively simplify the system structure, enhance the telescope’s utilization of light energy, reduce background radiation, and improve the telescope’s observation ability for dim and infrared targets. This paper presents our latest research on adaptive telescopes utilizing piezoelectric deformable secondary mirrors (PDSM). We have developed a 241-unit PDSM with small actuator spacing and installed it on the 1.8-meter adaptive telescope at the Lijiang Observatory in Yunnan, China. This system has successfully captured high-resolution visible near-diffraction limit images of astronomical targets. The imaging Strehl ratio of the system in the visible light band (approximately 640nm) reaches about 0.5, and the tracking accuracy is approximately 0.02 arcseconds. These results suggest that adaptive telescopes utilizing piezoelectric-driven deformable secondary mirrors outperform traditional ’telescope + adaptive optics’ system architecture, enabling significant improvements in high-resolution visible imaging.

The comprehensive and high-performance adaptive optics test bench (CHAO) is an indoor adaptive optics system developed by the High-Resolution Solar Atmospheric Optical Detection Team at the Institute of Optics and Electronics, Chinese Academy of Sciences. It possesses the capability to test and validate cutting-edge technologies in the field of adaptive optics. In current stage, CHAO includes a conventional adaptive optics system and a ground-layer adaptive optics system. These two AO systems each consist of a 177-subaperture single-direction Shack-Hartmann wavefront sensor (SH-WFS) and a 55-subaperture multi-direction SH-WFS, sharing a 177-element deformable mirror. The real-time controller of CHAO employs a multi-core CPU architecture, enabling both two AO systems to operate stably at frequencies above 4000 Hz. Additionally, RESAO is equipped with both point target source and extended target source, along with a turbulence phase screen to simulate dynamic turbulence disturbances. This paper will provide a detailed introduction to the design, functionality, and current results obtained based on the CHAO.

Waveplates are widely used in solar physics for polarization measurements in solar telescopes. Accurate calibration of the fast-axis azimuth and retardance of waveplates is crucial for improving the precision of these measurements. In this paper, we suggest that the spatial polarization characteristics of the analyzer in waveplate calibration system, using the intensity method, can introduce errors in calibrating the fast-axis and retardance. Therefore, we propose a correction method that introduces an analyzer model during the waveplate calibration process to address these errors. Numerical simulations demonstrated that the impact of these characteristics of the analyzer on the waveplate calibration depends on the form of these characteristics and the parameters of the waveplate itself, leading to calibration errors over 0.1° in fast-axis orientation and 1° in retardance in some cases. We conducted simulations using a calibration system as an example. The simulations indicate that, in certain cases, the correction method can reduce these errors significantly: from-0.27°to-0.08° for fast-axis orientation and from -3.8° to -0.01° for retardance. This method effectively reduces calibration errors of waveplate parameters induced by the spatial polarization characteristics of the analyzer in intensity-based methods.

To better understand the characteristics of atmospheric precipitable water vapor (PWV) in high-altitude regions, we have installed a microwave radiometer at the Ali site in Tibet for PWV measurements. The calibrated microwave radiometer is operating normally. Currently, it is the summer season at this site, and the PWV distribution ranges from 6 to 14 millimeters. In addition to measuring in the zenith direction, the microwave radiometer can also perform rotational scanning to obtain numerical results of PWV distribution throughout all the sky above the site. Besides the measurement of Precipitable Water Vapor, we have also published profile measurements of relative and absolute humidity. With the continuous measurement and accumulation of data on PWV, it will provide important support for the upcoming primordial gravitational wave measurement experiments.

To ensure the photometric accuracy of the transit telescope on Earth 2.0 and reduce the defocusing caused by thermal deformation, it is necessary to improve the radial temperature gradient of its lens. In this study, a thermal theoretical analysis of the lens to determine the heat transfer paths is conducted firstly, thereby the causes of significant radial temperature differences in the optical lens are clarified. Based on this analysis, a surrogate model was trained using thermal simulation calculations, enabling effective sensitivity analysis of all thermal factors affecting lens temperature uniformity, which identified the key factors and directions for thermal design optimization. For these key factors, a novel and systematic solution to improve the radial temperature uniformity of the optical lens was proposed for the first time. The main measures include increasing the thermal resistance between the lens and the telescope tube, reducing the temperature difference between the telescope tube and the lens, employing new lens coating techniques, and adjusting the temperature of the hood. With these thermal control technologies, simulation results show that the radial temperature difference of the first lens, when exposed to the harsh thermal environment of cold space, was reduced from 10K (before) to within 2K(after), greatly enhancing the radial temperature uniformity of the transit telescope lens. The method is derived from a general structural approach, making it applicable to other optical projects.

This paper presents a part of an initial study on a collaborative control strategy for multiple active mirrors in a large telescope. The study examines the structural dynamics from individual substructures to the overall telescope, providing a detailed mathematical formulation for assembling subunits within a comprehensive model. Additionally, a hierarchical control system is envisioned, integrating various sensor and actuator sources to correct the mirror shape across different temporal and spatial bandwidths.