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New observations of auroras based on the wide-field aurora imager (WAI) onboard Fengyun-3D (FY-3D) satellite are exhibited in this paper. Validity of the WAI data is analyzed by comparing auroral boundaries derived from WAI observations with results obtained from data collected by the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) aboard the Defense Meteorological Satellite Program (DMSP F18). Dynamic variations of the aurora with the solar wind, interplanetary magnetic field (IMF) parameters, and the SYM-H index are also investigated. The comparison of auroral boundaries indicates that the WAI data are morphologically valid and suitable to the study of auroral dynamics. Effective responses to solar wind parameters indicate that the WAI data can be useful to monitor and predict the Earth’s space weather. Since the configuration of aurora is a good indicator of the solar wind–magnetosphere–ionosphere (SW-M-I) coupling system, and can reflect the disturbance of the space environment, the WAI will provide important data to help us to study the physical processes in space.

The radiation intensity of observed auroras in the far-ultraviolet (FUV) band varies dramatically with location for aerospace applications, requiring a photon counting imaging apparatus with a wide dynamic range. However, combining high spatial resolution imaging with high event rates is technically challenging. We developed an FUV photon counting imaging system for aurora observation. Our system mainly consists of a microchannel plate (MCP) stack readout using a wedge strip anode (WSA) with charge induction and high-speed electronics, such as a charge sensitive amplifier (CSA) and pulse shaper. Moreover, we constructed an anode readout model and a time response model for readout circuits to investigate the counting error in high counting rate applications. This system supports global rates of 500 kilo counts, 0.610 dark counts s&minus, 1 cm&minus, 2 at an ambient temperature of 300 K and 111 &micro, m spatial resolution at 400 kilo counts s&minus, 1 (kcps). We demonstrate an obvious photon count loss at incident intensities close to the counting capacity of the system. To preserve image quality, the response time should be improved and some noise performance may be sacrificed. Finally, we also describe the correlation between counting rate and imaging resolution, which further guides the design of space observation instruments.

The newly launched Fengyun-3D (FY-3D) satellite carried a wide-field auroral imager (WAI) that was developed by Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences (CIOMP), which will provide a large field of view (FOV), high spatial resolution, and broadband ultraviolet images of the aurora and the ionosphere by imaging the N2 LBH bands of emissions. The WAI consists of two identical cameras, each with an FOV of 68° in the along-track direction and 10° in the cross-track direction. The two cameras are tilted relative to each other to cover a fan-shaped field of size 130° × 10°. Each camera consists of an unobstructed four-mirror anastigmatic optical system, a BaF2 filter, and a photon-counting imaging detector. The spatial resolution of WAI is ~10 km at the nadir point at a reference height of 110 km above the Earth’s surface. The sensitivity is >0.01 counts s−1 Rayleigh−1 pixel−1 (140–180 nm) for both cameras, which is sufficient for mapping the boundaries and the fine structures of the auroral oval during storms/substorms. Based on the tests and calibrations that were conducted prior to launch, the data processing algorithm includes photon signal decoding, geometric distortion correction, photometric correction, flat-field correction, line-of-sight projection and correction, and normalization between the two cameras. Preliminarily processed images are compared with DMSP SSUSI images. The agreement between the images that were captured by two instruments demonstrates that the WAI and the data processing algorithm operate normally and can provide high-quality scientific data for future studies on auroral dynamics., Satellite imaging: Mapping Earth’s auroras for space weather A compact camera system on board China’s recently launched Fengyun-3D satellite can reveal subtle features of the Earth’s auroras for improved space weather forecasting. Auroras such as the northern lights arise when solar wind charged particles precipitate along the Earth’s magnetic field and collide with atmospheric gases. Xiao-Xin Zhang, Bo Chen and their colleagues have developed a high-resolution imager that can help researchers predict geomagnetic substorms and storms from the dynamic configurations of auroras. The imager uses two cameras to simultaneously scan auroral regions from a low Earth orbit, delivering an expanded field of view relative to previous instruments. In-orbit testing shows that the device’s mirror-based optics and data processing system can identify boundaries and structures of auroras with 10 kilometer-scale resolution.

As one of the payloads for the Advanced Space-based Solar Observatory (ASO-S) mission, the Lyman-alpha (Lyα) Solar Telescope (LST) is aimed at imaging the Sun and the inner corona up to 2.5R⊙(mean solar radius) in both the Lyα(121.6 nm) and visible wavebands with high temporo-spatial resolution, mainly targeting solar flares, coronal mass ejections (CMEs) and filaments/prominences. LST observations allow us to trace solar eruptive phenomena from the disk center to the inner corona, to study the relationships between eruptive prominences/filaments, solar flares and CMEs, to explore the dynamical processes and evolution of solar eruptions, to diagnose solar winds, and to derive physical parameters of the solar atmosphere. LST is actually an instrument suite, which consists of a Solar Disk Imager (SDI), a Solar Corona Imager (SCI), aWhite-light Solar Telescope (WST) and two Guide Telescopes (GTs). This is the first paper in a series of LST-related papers. In this paper, we introduce the scientific objectives, present an overview of the LST payload and describe the planned observations. The detailed design and data along with potential diagnostics are described in the second (Paper II) and third (Paper III) papers, respectively, appearing in this issue.

In this paper, the combination of nonlinear gradient iteration and crossing method is presented in order to analyze high precision remote sensing images of solar magnetic field in extreme ultraviolet (EUV) wavelengths which are usually affected by solar magnetic evolution, satellite attitude changes and random satellite jitter, and to reduce structural complexity the complicated correlation tracker is normally adopted. Using crossing method which better approached the inefficiency by computing full-scale solar magnetic field images, nine point areas are uniformly selected in full-scale solar magnetic field images which solves the problem of low-computing efficiency. Meanwhile, nonlinear gradient iteration algorithm through numerical simulation experiments is adopted to analyze displacement of solar magnetic field images in EUV wavelengths, which reduces the errors due to the solar intensity changing and tiny deformation of solar magnetic field compared to traditional algorithms. The results clearly indicate that the precision of mean error field and square deviation field for deformed displacement are both less than 5% of pixel by solar magnetic field images of Solar Dynamics Observatory (SDO).

A novel curved focal plane extreme ultraviolet (EUV) detector array designed for a moon-based EUV camera is demonstrated. The curved focal plane detector array operating in a pulse-counting mode consists of a curved microchannel plate (MCP) stack and an induced charge wedge-strip anode (WSA). The curved MCP is fabricated by firstly thermally slumping of the MCPs, and then followed by optical polishing and core glass etching. By using this technology, curved MCPs with a length-to-diameter (L/D) ratio of 80:1 and a radius of curvature of 150 mm have been successfully achieved. The performance of the curved MCP detector is fully characterized in terms of the background noise, pulse height distribution, gain, image linearity and spatial resolution. It is measured that a spatial resolution of 7.13 lp/mm can be achieved with a background noise of less than 0.3 counts/cm2⋅s. The characterization results indicate that the curved focal plane detector can fulfill the requirements of the moon-based EUV camera.

The extreme-ultraviolet camera mounted on the Lander of China Chang-E lunar exploration project launched in 2013 is the first instrument used to imaging from the lunar surface to the whole plasmasphere around the earth. Taking into account both the lunar environment conditions and the weight and volume constraints, a single spherical mirror and a spherical microchannel plate detector make up the compact optical system. An optimized opto-mechanical design was presented using Finite Element Analysis Model, and the detail design for the important assemblies of the 2-axis platform, the primary mirror, the aperture door mechanism and MCP detector were all specially addressed for their environmental adaptability and reliability. Tests of mechanical characteristics have demonstrated that the position and pointing accuracy and its stability meets the operation requirements of 2'. Vibration results have shown that the EUVC has adequate stiffness and strength safety margin to survive in launch and the moon environments. The imaging performance with the resolution of 0.08 degrees is measured after vibration, in agreement with the predicted performance. (C)2014 Optical Society of America

In this paper, a general reaction time test instrument is designed for measuring general reaction time, through timing the moment of signal sent out to tester taking off. The instrument is controlled by a micro controller unite (MCU). Pressure sensors are set in a footboard. The signal of the sensors which is amplified by amplifying circuit is collected by AnalogDigital convertor (ADC) on MCU. Though this method, the instrument monitors the action of the tester. The instrument can also time jump period of the tester and measure the peak of jump force. Via enabling different group of lights, the instrument can measure both general simple reaction time and general choice reaction time. The test result can be sent to PC through USB port. PC software saves and analyzes the data. A time-force curve which perceivably shows the jump process is graphed by the software. 2013 IEEE.

For advancing the image quantity of multi-spectral and panchromatic images fusion, this paper presents an algorithm of multi-spectral image fusion based on the characteristic of imaging system. This algorithm firstly executes multi-resolution decomposition to multi-spectral and panchromatic images adopting with Nonsubsample contourlet transform, then establishes the panchromatic image injection model by analysising the imaging system characteristic of multi-spectral image in detail, and injects the detail information of panchromatic image to every spectrum of multi-spectral image by this model. At last, the decomposition coefficient is reconstructed by inverse nonsubsample contourlet transform so that the final fusion image is obtained. The experiment shows that the algorithm of this paper can not only fuses the detail information of panchromatic image adequately, but also retains the spectral characteristic of multi-spectral image better, reduces the spectrum distortion problem effectively.

In order to solve the problem of precise temperature control, the thermoelectric cooler (TEC) principle widely used is analyzed for the design of the whole control process and selection of control parameters, and then accurate simulation model of the TEC is established in Proteus simulation software. Moreover, combined with the traditional circuit simulation model, the temperature control loop is designed, and the response characteristics of the system are tested using an input signal similar to the unit-step function to achieve the precise temperature control. Simulation results show that the proposed control circuits can precisely convert error signal to output voltage sent to TEC model, and TEC model behaves approximately like a two-pole system. The first pole starts at 20mHz and a second pole at 1Hz.

Software rating ascertainment is very important in development of space camera software system. It can guide the software measurement and management, and help designer improve system reliability finally. Fault Tree Analysis is a common method to analyze the danger reason and fix on bottom events. The most significant step is calculating the occurrence probabilistic of top event, namely the occurrence probabilistic of dangerous event. Because software failure cause is anfractuous and available data are hard to get, a modeling method for bottom event is proposed based on Vague set to calculate the occurrence probabilistic of top event. Experimental results show that the new approach of Vague set can guide the Software rating ascertainment which is ascertained using qualitative analysis. The results also show that the new method makes software rating ascertainment have the quantificational evidence.