With the development of aerospace technologies and the widespread adoption of communication and navigation systems, accurate and timely space weather forecasting has become increasingly urgent to mitigate the influence of catastrophic space weather events on human activities. Since the 1970s, space weather has been actively studied and applied. Many observational instruments have been developed to monitor solar activity and space environment variations. In particular, a series of space payloads have been developed for the extremely sensitive wavebands of X-ray, extreme ultraviolet (EUV), and far ultraviolet (FUV) to monitor changes in the Sun and the terrestrial space environment. Since the 1980s, several key technological breakthroughs have been achieved at Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences (CIOMP), including optical elements, single-photon-counting imaging detectors, and radiometry for X-ray, EUV, and FUV regions. A number of optical elements and detectors have been fabricated, and calibrations are applied to space payloads.

EUV multilayer mirrors have been fabricated with working wavelengths including 9.4, 17.1, 19.5, 21.1, and 30.4 nm, with reflectance of 28%, 45%, 35%, 38%, and 38%, respectively [Fig. 1(a)]. Broadband, aperiodic FUV LaF₃/MgF₂ multilayer mirrors have also been prepared, with a working wavelength range of 140?180 nm and an in-band average reflectance of 45%. These mirrors also exhibit good out-of-band reflectance suppression [Fig. 1(b)]. For observing weak EUV and FUV targets, a single-photon-counting imaging detector with a spherical photosensitive surface and excellent adaptability to space environments has been developed. This includes key technological advancements such as the fabrication of spherical microchannel plates, the carving of micro-strip anodes, and the processing of weak optoelectronic pulse signals. The detector has an equivalent pixel size of 45 μm, a counting rate of 3.5×10⁵ s^-1, an effective aperture of Ф75 mm, and approximately 1600×1600 equivalent pixels. Test and calibration devices for optical element measurements in X-ray, EUV, and FUV regions have been established. These devices are equipped with a hollow cathode source, a laser-produced plasma source, and an X-ray tube. The device’s working wavelength range is from 0.1 nm to 200 nm, with a spectral resolution of 0.1 nm, a test repeatability of 1%, and a wavelength precision of 0.2 nm. These have been used to measure the reflectance and transmittance of optical elements and grating efficiencies. To obtain high-resolution solar images, a high-precision pointing and imaging stabilization technology has been developed. A solar guide telescope (GT) has been developed at CIOMP, achieving a pointing accuracy of 0.1″ and a data update speed of 1 kHz. The GT is used in payloads onboard FengYun meteorological satellites and the Kua Fu advanced space-based solar observatory satellite (ASO-S). Based on the breakthroughs in the above key technologies, four payloads have been developed at CIOMP and are employed in space weather forecasting, warning, and scientific research. An innovative X-ray and EUV double-wavelength solar imager is developed, which combines an EUV multilayer of normal-incidence optics in the central part of an X-ray grazing-incidence imaging optics for the FY-3E satellite. This imager covers the 0.6?8.0 nm X-ray waveband and 19.5 nm EUV dual wavelengths. The instrument serves the function of two separate instruments. The imager is also equipped with a sensor for the same wavelengths which measures solar irradiance and regularly calibrates the X-ray and EUV solar images. Figure 9 shows solar images with absolute brightness. A Lyman α solar telescope (LST) has been developed for solar flare and coronal mass ejection (CME) observations, including a solar corona imager (SCI), a solar disk imager (SDI), and a white light solar telescope (WST). SCI utilizes a special design combining off-axis reflective optics and an FUV beam splitter to achieve inner corona imaging in dual wavebands of 121.6 and 700 nm. On-orbit test results indicate SCI achieves an angular resolution of 4.8″, which is about one-eighth that of METIS/Solar Orbiter. The SDI’s field of view (FOV) is 38.5′, allowing for full solar disk observation. The solar observation area of the SDI is approximately four times larger than that of EUI/Solar Orbiter. LST is the first to achieve imaging observation of all regions, from the full solar disk to the inner corona, at Lyman-α, monitoring the real-time process of fine corona and prominence. These observations have been used for space weather forecasting and scientific research. The AEUV camera onboard Chang’e-3, as part of the mission’s payload, is the first EUV instrument to be used for observing Earth’s plasmasphere from lunar orbit. These Earth plasma images are released by the Lunar Exploration and Space Program Center of China National Space Administration in January 2014. Figure 16 shows the panorama image of Earth’s plasmasphere captured from the lunar surface. The wide-field auroral imager onboard FY-3D has been developed to monitor aurora in the 140?180 nm waveband and can image the entire polar region (5000 km×5000 km) in two minutes. Compared with DMSP/SSUSI and TIMED/GUVI, it has a higher temporal resolution, offering an advantage for forecasting and scientific research.

A series of core space optical technologies in the X-ray, EUV, and FUV wavebands have been mastered, including the manufacture, testing, and calibration of instruments. A research system has been established at CIOMP. Several payloads in these wavebands have been developed and launched into lunar orbit, polar orbit, and sun-synchronous orbit. These payloads play an important role in space weather forecasting and scientific research.