The single-mode fiber coupling efficiency with graded-index rod lenses can achieve higher coupling efficiency, compared with the direct alignment coupling of the single-mode fiber. The assembly error of direct alignment has a far greater impact on the coupling efficiency of the fiber than the GRIN lenses coupling to fiber. The analysis of the influence of the coupling error on the optical fiber coupling efficiency provides important theoretical support and guidance for processing and assembly. Axial error, radial error and angular tilt will all have different effects on fiber coupling efficiency. However, the fiber coupling system is not only limited to the coupling of the fiber and GRIN lenses, but also can be coupled with one or more lenses to analyze the advantages and disadvantages of multiple coupling methods.
Solar Array Drive Assembly(SADA) is a core component of high-power and long-life satellites, and the shafting is an important part of SADA. Its vibration characteristics analysis is very important in structural design and dynamic analysis. The paper theoretically derived and calculated the natural frequency of the shaft system under the action of bearing preload and span, and established a corresponding finite element simulation model in ANSYS. It is concluded that the natural frequency of the shafting increases with the increase of the bearing preload and the span, and the influence of the bearing span is more significant.
In this paper, we mainly studied how to calculate the energy values of stars received by ground optical systems. Then according to the characteristics of the radiation spectrum of stars and the radiation spectrum of sky background light, we analyzed and selected the observation spectrum of the image-forming system. We also studied the influence of optical system design parameters, such as field of view, focal length and aperture, on detection capability. At the same time, we analyzed and calculate the limitation of the detector's dark current, readout noise and other noise factors on the ability of receiving stars. The significance of these studies is that we provide an effective theoretical basis for designing and improving ground-based photoelectric detection system for star observation during the daytime. In addition, we used digital image processing technology to process the existing observation images and improve the quality of the image. We provide several algorithms for extracting small targets in strong background. We use threshold segmentation, morphological filtering and other methods to improve the signal-to-noise ratio of the image and then improve the detection ability of the system again. According to the simulation, the target extraction accuracy can reach 1/10 pixels when the target imaging size is 4 pixels and the signal-to-noise ratio is less than 5. Improving the detection ability of photoelectric detection system, detecting more available stars and obtaining their relative position information are the important basis for star map matching and the estimation of targets’ position and gesture.
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