Search

The space-agile optical composite detection (SOCD) system with a pointing mirror possesses flexible and fast response ability. Like other space telescopes, if the stray light is not properly eliminated, it may result in a false response or noise that floods the real light signal due to the low illuminance and large dynamic range of the target. The paper shows the optical structure layout, the decomposition of the optical processing index and roughness control index, the stray light suppression requirements, and the detailed stray light analysis process. The pointing mirror and ultra-long afocal optical path increase the difficulty of stray light suppression in the SOCD system. This paper presents the design method of a special-shaped aperture diaphragm and entrance baffle, black baffle surface testing, simulating, selection, and stray light suppression analysis process. The special-shaped entrance baffle has a significant effect on the suppression of stray light and reduced dependence on the platform posture of the SOCD system.

In low-Earth orbit, the already existing population of small and medium debris (between 1 cm and several dozens of cm) is a concrete threat to operational satellites. A space-based laser space debris removal (SLDR) system that can remove hazardous debris around selected space assets appears to be a flexible and effective project. To achieve high-precision tracking and emitting, the optical system of the SLDR mission includes a target-detection telescope and emitting telescope, adopting a common light path structure. The optical design results, system performance, tolerance budget, and detailed stray light control design are presented in this paper. The large-aperture off-axis two-mirror beam-narrowing system characteristics are also discussed in terms of stray light control. This paper will present the lateral-displacement (LD) setting, two-stage fore baffle design, black baffle surface selection, and opening direction of the telescope door. The results showed that the stray light elimination reaches a 10 − 9 order, meeting design requirements.

The surface figure precision, weight, and dynamic performance of spaceborne primary mirrors depend on mirror structure parameters, which are usually optimized to improve the overall performance. To realize rapid multi-objective design optimization of a primary mirror with multiple apertures, a fully parameterized primary mirror structure is established. A surrogate model based on a hybrid of improved particle swarm optimization (IPSO), adaptive genetic algorithm (IAGA), and optimized back propagation neural network (IPSO-IAGA-BPNN) is developed to replace optomechanical simulation with its high computational cost. In this model, a self-adaptive inertia weight and a modified genetic operator are introduced into the particle swarm optimization (PSO) and adaptive genetic algorithm (AGA), respectively. The connection parameters of BPNN are optimized by the IPSO-IAGA algorithm for global searching capability. Further, the proposed IPSO-IAGA-BPNN, based on a rapid multi-objective optimization framework for a fully parameterized primary mirror structure, is established. Moreover, in addition to the proposed IPSO-IAGA-BPNN model, the Kriging, RSM, BPNN, GA-BPNN, PSO-BPNN, and PSO-GA-BPNN models are also analyzed as contrast models. The comparison results indicate that the predicted value obtained by IPSO-IAGA-BPNN is superior to the six other surrogate models since its mean absolute percentage error is less than 3% and its R 2 is more than 0.99. Finally, we present a Pareto-optimal primary mirror design and implement it through three optimization methods. The verification results show that the proposed method predicts mirror structural performance more accurately than existing surrogate-based methods, and promotes significantly superior computational efficiency compared to the conventional integration-based method.

In this paper, a series of chromium carbon nitride (CrCN) composite films with various carbon content were deposited by changing the power of carbon target using RF-reactive magnetron sputtering system in the argon and nitrogen mixture gases. The microstructure, mechanical and frictional properties of CrCN films were investigated by X-ray diffraction (XRD), Raman spectrometer, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), nanoindentation and friction tester. According to the experimental results, the deposited binary CrN film exhibited a single face-centered cubic (fcc) structure, whereas the addition of carbon into the CrN matrix induced the formation of other phases of carbon and CNx. Both the solid solution strengthening and the increase of compressive residual stress improved the hardness from ~17 GPa at 0 at.% carbon to ~19 GPa at 6.3 at.% carbon. With the increase of C content, the friction curve of the CrCN film stabilized gradually and the average friction coefficient decreased gradually from 0.62 at 0 at.% carbon to 0.40 at 23.7 at.% carbon. The formation of lubricating amorphous carbon and CNx phase in the films mainly attributed to the improvement of friction property.