In order to solve the problem that ground-based optical telescope cannot detect space targets in the daytime, an infrared detection method is proposed in this paper. Firstly, from the perspective of spectral characteristics of space targets and skylight, the short-wave infrared band (SWIR) of 0.9~1.7μm is optimized, which reduces the brightness of the skylight, and avoids the cooling of the optical system. Secondly, the signal-to-noise ratio (SNR) of the target is improved by the time-domain multi-frame accumulation algorithm and the goal of daytime 'extended range' detection of optical telescope is achieved. Experiments on a 0.3-meter telescope show that the space targets, which SNR less than 1 are detected by adopting this method in the daytime, when the zenith angle of sun is 40°, exposure time is 40ms, and the number of the cumulative frames is 360, the limit detection ability is 10.8mV. The results of the experiments well verify the theoretical analysis, which provides a reference for the system design of the next generation of ground-based optical telescope.
The 1.2-m primary mirror supporting systems are composed of axial support system with whiffletree structure and lateral support system with 6 tangent links. With the simulation based on the finite element analysis (FEA), the 18 points positions of the axial support are determined and the bottom chamber structure of the primary mirror is improved. In order to reduce the mirror surface deformation, the assembly stress on the primary mirror is reduced by optimizing the lateral support structure. The analysis results demonstrated that the root-mean-square (RMS) of the surface deformation is 10.9nm when the primary mirror points vertically. Meanwhile the RMS of the surface deformation is 10.3nm when the primary mirror points horizontally.
Removing space debris by high-energy pulsed laser may be the most effective way to mitigate the threat posed by the increasing space debris. Laser ablation of a thin surface layer causes recoil impulse, which will lower the orbit perigee of space debris and accelerate the atmospheric capture. When the laser beam vertically irradiates a flat debris, it requires a certain laser fluence to reach the optimal impulse coupling, and the recoil impulse is parallel to the laser beam. However, the incident laser fluence varies in different parts of a non-flat surface. We have taken the shape effect into account to propose a numerical method of calculating the recoil impulse. Taking cylinder debris as the target, we have compared the recoil impulse in different laser fluences through simulation experiments, which implies that a higher laser fluence than the optimal one is needed to obtain a larger recoil impulse for irregularly shaped space debris.
The echo received from diffuse reflection laser ranging (DRLR) system for space debris and satellite without corner reflector is too weak to detect available echo-photon robustly. A new method based on image saliency feature for echophoton detection was proposed, which used the concept of image saliency in computer vision field to describe echophoton distribution feature. The O-C residue distribution information was used to generate O-C residue image, and then saliency feature recognition, Piecewise Hough detection and polynomial fitting were adopt orderly to obtain available echo signal. The actual experiment results show the effectiveness and robustness of the algorithm.
KEYWORDS: Missiles, Optical testing, 3D acquisition, 3D image processing, 3D metrology, Detection and tracking algorithms, Defense technologies, Rockets, Target detection, Binary data
Measuring the three-dimension (3D) orientation parameters of the axis symmetry objects, such as missile and rocket,
plays an important role of optimization design and malfunction analysis of the targets in shooting range experimentations.
If the target is clear-cut, there are already many ways to extract the axis precisely, and get the three-dimension orientation
parameters by triangulation method. But in practical experimentations, we sometimes face the problem that the target is
illuminated by intense sunlight, which with the background of sky will cause the imprecision of axis extraction and the
increasing of measurement error. To solve the problem, this paper presents an accurate method to extract the target’s axis.
The method build a point set, and try to put all the target’s points into it by using the priori-knowledge, such as the
symmetry target’s characteristic under unilateral illumination condition, then calculate the regional minimum inertia axis
of the set’s points and get the target’s axis. Experimental results show that this method is efficient and robust to noise,
which can meet the requirement of unilaterally illuminated target 3D pose interpretation in shooting range.
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