The process of development and calibration for the first Moon-based ex- treme ultraviolet （EUV） camera to observe Earth＇s plasmasphere is introduced and the design, test and calibration results are presented. The E...The process of development and calibration for the first Moon-based ex- treme ultraviolet （EUV） camera to observe Earth＇s plasmasphere is introduced and the design, test and calibration results are presented. The EUV camera is composed of a multilayer film mirror, a thin film filter, a photon-counting imaging detector, a mech- anism that can adjust the direction in two dimensions, a protective cover, an electronic unit and a thermal control unit. The center wavelength of the EUV camera is 30.2 nm with a bandwidth of 4.6nm. The field of view is 14.7° with an angular resolution of 0.08°, and the sensitivity of the camera is 0.11 count s-1 Rayleigh-1. The geomet- ric calibration, the absolute photometric calibration and the relative photometric cal- ibration are carried out under different temperatures before launch to obtain a matrix that can correct geometric distortion and a matrix for relative photometric correction, which are used for in-orbit correction of the images to ensure their accuracy.展开更多
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 provid...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,flatfield 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.展开更多
文摘The process of development and calibration for the first Moon-based ex- treme ultraviolet （EUV） camera to observe Earth＇s plasmasphere is introduced and the design, test and calibration results are presented. The EUV camera is composed of a multilayer film mirror, a thin film filter, a photon-counting imaging detector, a mech- anism that can adjust the direction in two dimensions, a protective cover, an electronic unit and a thermal control unit. The center wavelength of the EUV camera is 30.2 nm with a bandwidth of 4.6nm. The field of view is 14.7° with an angular resolution of 0.08°, and the sensitivity of the camera is 0.11 count s-1 Rayleigh-1. The geomet- ric calibration, the absolute photometric calibration and the relative photometric cal- ibration are carried out under different temperatures before launch to obtain a matrix that can correct geometric distortion and a matrix for relative photometric correction, which are used for in-orbit correction of the images to ensure their accuracy.
基金supported in part by the National Science Foundation of China(Grant Nos.41774152 and 41674155)supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA17010201)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2017258).
文摘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,flatfield 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.
