The solar power satellite (SPS) concept is an elegant solution to the challenge of providing large-scale energy for humanity a large platform, positioned in space in a high Earth orbit, continuously collects and converts solar energy into electricity. SPS-ALPHA is composed of a large number of small modules, which enables the modularity and lower cost of machining/space transport. Until now two options of SPS-ALPHA have been proposed, the Mark-I version (sigmoid-curve-based shape) and the Mark-II version (conical shape). The current study aims to find the optimal design parameters of the reflecting modules for these two versions where high optical efficiency and a stable irradiance distribution are both achieved for an effective photovoltaic layout design. To meet this target, the ant colony optimization algorithm, combined with dynamic source-target mapping, was adopted to find the optimal aiming vectors of the reflectors. The optical transmission characteristics under different incident degrees were investigated using a two-step Monte Carlo ray tracing method. The received heat flux distribution and error analysis of the two structural versions are compared as well. This article can provide basic data and a reference for engineering constructions of SPS-ALPHA for the next step.A Nomarski polarizing prism has been used in conjunction with a focused laser differential interferometer to measure the phase velocity of a density disturbance at sampling frequencies ≥10MHz. Use of this prism enables the simultaneous measurement of density disturbances at two closely spaced points that can be arbitrarily oriented about the instrument's optical axis. The orientation is prescribed by rotating the prism about this axis. Since all four beams (one beam pair at each measurement point) propagate parallel to one another within the test volume, any bias imparted by density fluctuations away from the measurement plane on the disturbance phase velocity is minimized. A laboratory measurement of a spark-generated shock wave and a wind tunnel measurement of a second-mode instability wave on a cone model in a Mach 6 flow are presented to demonstrate the performance of the instrument. High-speed schlieren imaging is used in both cases to verify the results obtained with the instrument.During quality-assurance procedures in the mass production of small-sized curved optical lenses, fine defects are usually detected via manual observation, which is not recommended owing to the associated drawbacks of high error rate, low efficiency, and nonamenability to quantitative analysis. To address this concern, this paper presents a comprehensive defect-detection system based on transmitted fringe deflectometry, dark-field illumination, and light transmission. Experimental results obtained in this study reveal that the proposed method demonstrates efficient and accurate detection of several microdefects occurring in small-sized optical lenses, thereby providing valuable insights into the optimization of parameters concerning the mass production of optical lenses. The proposed system can be applied to the actual mass production of small-sized curved optical lenses.The directional polarimetric camera (DPC) is a polarization sensor with ultra-wide-angle and low-distortion imaging characteristics. Geometric calibration is usually the first essential step before remote sensing satellites are launched.  https://www.selleckchem.com/products/bi-3802.html  In this paper, a geometric calibration method based on a two-dimensional turntable and a rotation matrix with high precision, simple operation, and wide application range is proposed for the directional polarimetric camera. Instead of precisely adjusting the position of the sensor on the turntable, the method effectively eliminates the errors caused by the mechanical axis of the turntable and the optical axis of the sensor not being adjusted to the same direction through the rotation transformation of the coordinate system. The geometric calibration experiments of the directional polarimetric camera were carried out with the method of Chen et al. [Optik121, 486 (2010)10.1016/j.ijleo.2008.08.004OTIKAJ0030-4026] and the proposed method. The experimental results showed the calibration residual of the proposed method was less than 0.1 pixel while Chen's method was 0.3 pixel. The mean reprojection error and root mean square error of the proposed method were reduced to 0.06352 pixel and 0.06961 pixel, respectively. The geometric calibration parameters obtained by the proposed method were used for geometric correction of the in-orbit images of the DPC, and the results also prove the effectiveness and superiority of the proposed method.We demonstrate visible and near-IR image projection via non-absorbing, multi-level broadband diffractive-optical elements (BDOEs) in one or more planes. By appropriate design of the BDOE topography, we experimentally demonstrate (1) different images in different spectral bands, (2) different images in different image planes, (3) image magnification by changing the distance between the illumination source and the BDOE, (4) completely flat BDOE via an index-contrast top coating, and (5) reflective BDOEs. All of these are accomplished with broadband illumination. Furthermore, the BDOEs are highly efficient and versatile and can be inexpensively mass manufactured using imprint-based replication techniques.The accurate registration and realignment of complex signal volumes is critical for cross-range aperture gain in 3D LiDAR aperture synthesis. For targets at long range, only a limited number of diffraction-limited pixels will be projected on the target, resulting in low cross-range support. In addition, the signal-to-noise ratio (SNR) is typically low. This research describes an enhanced cross-correlation registration algorithm for 3D inverse synthetic aperture LiDAR data volumes that improves performance for low cross-range support, low SNRs, and relatively large aperture shifts. The registration performance is improved through statistical removal of the cross-correlation noise pedestal and compensation for the reduced signal overlap caused by larger shifts. The registration performance is characterized as a function of SNR, signal shift (target rotation rate), and target pixel support. The algorithm's improvements allow for registration convergence at 1-5 dB lower SNR than the baseline cross-correlation algorithm.