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Abstract Heterodyne lidar echoes in atmospheric detection are greatly affected by the shapes of aerosols. With the aid of T-matrix and vector Monte Carlo simulation, we investigated the properties of lidar echoes backscattered by randomly oriented polydisperse aerosols, including the soot, sea salt and mineral aerosols. The degree of polarization (DoP) and backscattered photon numbers in different range bins are calculated when the launched laser pulses are linearly polarized light and circularly polarized light at 1.55 μm. There are reductions of DoP along the 10 km detection path, which vary with aspect ratios (AR) and aerosol types. The ARs are chosen within 0.5–2.0 for cylinders and 0.3–1.0 for spheroids. The lidar echoes in soot aerosols have the largest DoP which is higher than 0.8. Moreover, the shape fading factor and polarization fading factor are defined and calculated based on the effective backscattered photon numbers, which shows that the mineral aerosols in nuc.mode (MINM) is less affected by aerosol shapes and laser polarization states, and that the LPL is suitable for the heterodyne detection of nonspherical atmospheric aerosols. The results provide echo characteristic deviations from the spherical particle scattering, which can be used in the practical modeling of atmospheric echoes and designs of heterodyne lidars. [ABSTRACT FROM AUTHOR]

We briefly introduce the upside-down taper lens drawn from the end of single-mode circular core triangular-index fiber and analyse it. Based on paraxial approximation, we formulate ABCD transformation matrix of such fiber end. The said prescription involves modelling of refractive index profile in tapered region, ray trace equation and also the ray refraction formula at a spherical surface. The analysis can be employed for design of micro-optic image systems and also for study of coupling optics involving such tapered lensing device. Employing the prescribed ABCD matrix of transmission, we formulate analytical expression for coupling efficiency and employ them to predict the concerned coupling optics. In this context, Gaussian field distributions for both the source and the fiber are assumed. In our present study, we use two practical wavelengths namely 1.3 μm and 1.5 μm. This simple but accurate method will prove beneficial to the designers and packagers working with the field of launch optics. [ABSTRACT FROM AUTHOR]

Abstract: The master-slave surveillance system uses stationary-dynamic camera assemblies to achieve wide-area surveillance and selective focus-of-interest. In such a system, a stationary fish-eye camera monitors a panoramic field of environment from a distance, while a dynamic PTZ (Pan–Tilt–Zoom) dome camera is commanded to acquire high-resolution images from a focused direction and provide multi-scale zoomed-in information. In order to achieve the precise interaction, pre-processing spatial calibration between these two cameras is required. This paper introduces a novel vision based calibration approach to automatically calculate a transformation matrix model between the fish-eye coordinate system and the PTZ dome coordinate system by matching feature points in the scene. The experiment has demonstrated the effectiveness of using this method with high accuracy in short calibration time. [Copyright &y& Elsevier]

Abstract: One of the most popular mathematical tools in fields of robotics, mechanisms and computer graphics is the 4×4 homogeneous transformation matrix. Our group''s previous application of the homogeneous transformation matrix to flat and spherical optical boundaries has been extended to hyperboloid surfaces for: (1) skew ray tracing to determine the paths of reflected/refracted skew rays; (2) sensitivity analysis for direct mathematical expression of differential changes of incident points and reflected/refracted vectors with respect to changes in incident light sources and boundary geometric parameters; (3) a sensitivity analysis-based merit function derived directly from mathematical expression of catadioptric imaging system components. The presented methodology is highly suited to digital implementation and offers direct and rapid analytical statement of ray path, chief ray, marginal rays and merit functions of optical systems. [Copyright &y& Elsevier]