We conducted research into the visible light detection of conical space targets and proposed a method to determine the caliber of a space-based detection system. We constructed a three-dimensional conical space target radiation transfer model and analyzed the effect of the phase angle between the solar incident direction, the detector’s bore sight direction, and the conical target inclination on the radiation intensity of the space target received by the detector. Finally, we obtained the threshold caliber which can meet the detection requirements of the system with the system signal-to-noise ratio as the evaluation standard, and we took the SBV sensor as an example to verify that the caliber determination method in this paper is effective.

In this study, we developed a numerical model of the coupled modulation transfer function (coupled-MTF) based on the discrete sampling system from the perspective of optical system imaging quality evaluation for coupled two-dimensional discrete sampling characteristics of the hexagonally aligned fiber-optic imaging bundles and CCD image elements. The results show that when the spatial frequency of the input target signal deviates from the Nyquist frequency by 1%, an increase in the number of fibers leads to a faster convergence of the oscillation of the coupled-MTF, and the coupled-MTF converges to a stable value when the number of fibers reaches 1000 × 1000. The deviation of the spatial frequency of the input target signal from the Nyquist frequency is within 1%, and the oscillatory convergence of the coupled-MTF accelerates with increasing deviation. The coupled-MTF oscillates with the deviation period of the wave peak of the input target signal from the initial position of the fiber center, and the theoretical oscillation spatial period is twice the fiber diameter. This study produces important guidelines for the selection of the number of fibers, input spatial frequency, and initial position deviation of the hexagonally arranged fiber imaging bundles.

We report a method for determining the field of view (FOV) of a dawn–dusk sun-synchronous orbit satellite based on an improved observation mode. The target trajectory distribution model in geosynchronous orbit (GEO) is established, the natural rendezvous mode is improved, and the observation mode of the satellite is determined. A scheme for determining the thresholds of cross-orbit field of view (COFOV) and the along-orbit field of view (AOFOV) was developed. The result shows that the coverage of the satellite can reach more than 95% when the improved observation mode is used to observe the GEO target. When the revisit period of the satellite is one day, the threshold of the COFOV is 15°, and the threshold of the AOFOV is 12°.

The concentric optical camera based on the optical fiber relay image can meet the needs of the miniaturization, lightweight, and large field of view detection of the space target detection system. However, due to the inevitable thermal stretching and torque processes involved in the production of fiber optic panels (FOPs), defects of unknown shape, size, and location are formed, increasing the difficulty of space target information acquisition and causing center-of-mass localization errors. To efficiently and accurately detect and locate defects in FOPs, we propose an improved defect detection and localization method for FOPs based on discrete wavelet and multi-objective morphological optimization by using the gray value of the image sensor. We compare this method with the Canny edge detection method and the FCM clustering method and find that the method has higher detection accuracy and stronger robustness in an environment with a large number of dark filament interferences, and the detection results are not affected by the various image sizes of the FOPs. The method also maintains a high degree of consistency in detection metrics, with the F_Score detection accuracy of 85%. This research provides a reliable solution for FOP defect detection and localization, lays the foundation for image quality improvement of concentric optical cameras based on fiber-optic relay imaging, and contributes to space target detection and localization.

The monocentric camera based on fiber relay imaging offers benefits of light weight, compact size envelope, vast field of view, and high resolution, which can fully fulfill the index requirements of space-based surveillance systems. However, the fiber optic plate's (FOP) defects will result in the loss of imaging data, and the FOP's discrete structural features will exacerbate the imaging's non-uniformity. A global defect detection approach based on manual threshold segmentation of saturated frames is suggested to detect FOP defect features. The suggested method's efficacy and accuracy are confirmed when compared to the classical Otsu algorithm. Additionally, through tests, the relative imaging response coefficients of each pixel are identified, the response non-uniformity of the pixels is corrected, and the whole image non-uniformity drops from 10.01% to 0.78%. The study in this paper expedites the use of fiber relay imaging-based monocentric cameras in the field of space-based surveillance, and the technique described in this paper is also appropriate for large-array optical fiber coupled relay image transmission systems.

We propose a method for obtaining the centroid locating accuracy (CLA) of a monocentric imager with a fiber optic plate (FOP) as a relay image transmission element in order to reduce the loss of CLA due to the addition of FOP. We constructed a two-stage image transmission coupling model of spherical focal surface (FOP) image sensor. By analyzing the influences of FOP parameters, including the fill factor and the fiber diameter, and FOP in-plane displacements, including rotation and translation on CLA, the loss of the lowest CLA that the monocentric imager can withstand caused by the addition of the FOP was reduced by 20%.