Coastal Zone Imager(CZI) was designed for coastal water body and islands. To analyze the potential application of Chinese
ocean color satellite in coastal zone area and evaluate the image quality, we used subjective and objective evaluation
method and took a comparison between Chinese ocean color satellite and Gaofen series satellite. Subjective evaluation
showed that Chinese ocean color satellite images had a better performance than Gaofen series satellite images in water
bodies. Based on statistical information ,objective evaluation showed that each band gray distribution of Chinese ocean
color satellite images was more dispersed and had a higher separability feature. Applying evaluation showed that Chinese
ocean color satellite also performed better in terms of texture property and classification accuracy. Overall Chinese ocean
color satellite had a high image quality and potential applications in coastal areas.
Sun light reflected from sea surface forms a high intensity solar ray. Sun-glint is created by Fresnel reflection which contaminates ocean color products. It covers up the real physical characteristics of water bodies and interferes with the inversion of ocean remote sensing data precision. In this paper, sun glint regional characteristics are simulated and analyzed in consideration of the different satellite attitude angles and time phases based on Cox–Munk model. The numerical simulation shows that through the satellites adjust attitude dynamically, the contamination area decreases by 11.8%.Onorbit test data are used to evaluate the method precision and it will contributes to the estimation of sun glint regional characteristics and strategy of on-orbit use.
Satellite telemetry is the vital indicators to estimate the performance of the satellite. The telemetry data, the threshold
range and the variation tendency collected during the whole operational life of the satellite, can guide and evaluate the
subsequent design of the satellite in the future. The rotational parts on the satellite (e.g. solar arrays, antennas and
oscillating mirrors) affect collecting the solar energy and the other functions of the satellite. Visualization telemetries
(pictures, video) are captured to interpret the status of the satellite qualitatively in real time as an important supplement
for troubleshooting. The mature technology of commercial off-the-shelf (COTS) products have obvious advantages in
terms of the design of construction, electronics, interfaces and image processing. Also considering the weight, power
consumption, and cost, it can be directly used in our application or can be adopted for secondary development. In this
paper, characteristic simulations of solar arrays radiation in orbit are presented, and a suitable camera module of certain
commercial smartphone is adopted after the precise calculation and the product selection process. Considering the
advantages of the COTS devices, which can solve both the fundamental and complicated satellite problems, this
technique proposed is innovative to the project implementation in the future.
Based on the maximum detection range, the detection capability of space-based camera for space debris is analyzed in the paper. We perform grid generation method on the debris target and analyze the shadowing effects among the grids, building the geometry modeling of cone target sequentially. The calculation model of optical infrared characteristics is established, taking into consideration the target self-radiation and radiation reflection characteristics of the material on surface. The radiation energy of the target is only depended on the reflection of earth’s radiation and its self-radiation in the simulation proposed in the paper. Based on the maximum detection range formula, the numerical simulation presented shows that when the space-based target radiation intensity is 21.54W/sr and optical system aperture is 0.5m, the maximum detection range is 17279km. The simulation results theoretically contribute to the estimation of camera parameters and analysis on the detection capability.
The freeform optics is extensively applied in the fields of aerospace, aviation, lighting, medical treatment, et al.. For the linearly push-broom space-borne imager, integration time of different field of view can be affected by the optical system design of the imager, orbits of the satellite, maneuver of the attitudes, rotation of the Earth, light delay due to the refraction and transmission of the atmosphere, terrain error and so on. The dynamically imaging quality should be affected by the accuracy and adjusting mode of the integration time. In this paper, a new method which is especially appropriate to imaging model simulating and integration time calculating for the wide-field-of-view remote sensor is proposed. Then, the integration time of specified viewing direction for the imager with a single projection center and a super-wide field of view based on freeform mirror, which is mounted on a sun-synchronous orbit satellite, is calculated. And influence on imaging quality of adjusting integration time of different grouping modes for the focal plane assembly is analyzed. The results indicate that with the constraint condition of satellite roll angle and the modulation transfer function (MTF) influence factor no more than 20°and 2% respectively, integration time of all CCDs for the whole focal plane assembly divided into two groups with each adopting the uniform integration time, can fulfill the requirements of the imaging quality for the imager.
Proc. SPIE. 9621, 2015 International Conference on Optical Instruments and Technology: Advanced Lasers and Applications
KEYWORDS: Signal to noise ratio, Telescopes, LIDAR, Solid state lasers, Space telescopes, Atmospheric sensing, Pulsed laser operation, Atmospheric modeling, Atmospheric optics, Laser systems engineering
Many studies have indicated that the optimum measurement approach for winds from space is a pulsed coherent wind lidar, which is an active remote sensing tool with the characteristics that high spatial and temporal resolutions, real-time detection, high mobility, facilitated control and so on. Because of the significant eye safety, efficiency, size, and lifetime advantage, 2μm wavelength solid-state laser lidar systems have attracted much attention in spacebased wind lidar plans. In this paper, the theory of coherent detection is presented and a 2μm wavelength solid-state laser lidar system is introduced, then the ideal aperture is calculated from signal-to-noise(SNR) view at orbit 400km. However, considering real application, even if the lidar hardware is perfectly aligned, the directional jitter of laser beam, the attitude change of the lidar in the long round trip time of the light from the atmosphere and other factors can bring misalignment angle. So the influence of misalignment angle is considered and calculated, and the optimum telescope diameter(0.45m) is obtained as the misalignment angle is 4 μrad. By the analysis of the optimum aperture required for spacebased coherent wind lidar system, we try to present the design guidance for the telescope.