Range-Gated Laser Stroboscopic Imaging for Night Remote Surveillance

For night remote surveillance, we present a method, the range-gated laser stroboscopic imaging(RGLSI), which uses a new kind of time delay integration mode to integrate target signals so that night remote surveillance can be realized by a low-energy illuminated laser. The time delay integration in this method has no influence on the video frame rate. Compared with the traditional range-gated laser imaging, RGLSI can reduce scintillation and target speckle effects and significantly improve the image signal-to-noise ratio analyzed. Even under low light level and low visibility conditions, the RGLSI system can effectively work. In a preliminary experiment, we have detected and recognized a railway bridge one kilometer away under a visibility of six kilometers, when the effective illuminated energy is 29.5 mu J.

Effects of atmosphere visibility on performances of non-line-of-sight ultraviolet communication systems

Dependence of performances of non-line-of-sight (NLOS) solar-blind ultraviolet (UV) communication systems on atmosphere visibility is investigated numerically by correlating the propagation of UV radiation with the visibility. A simplified solar-blind UV atmospheric propagation model is introduced, and the NLOS UV communication system model is constituted based on the single scattering assumption. Using the model, numerical simulation is conducted for two typical geometry configurations and different modulation formats. The results indicate that the performance of the NLOS UV communication system is insensitive to variation of visibility in quite a large range, and deteriorates significantly only in very low-visibility weather, and is also dependent on the geometry configuration of the system. The results also show that the pulse position modulation (PPM) is preferable due to its high-power efficiency to improve the system performance. (c) 2007 Elsevier GmbH. All rights reserved.

Enhanced visibility of graphene: Effect of one-dimensional photonic crystal

We investigate theoretically the light reflectance of a graphene layer prepared on the top of one-dimensional Si/SiO2 photonic crystal (1DPC). It is shown that the visibility of the graphene layers is enhanced greatly when 1DPC is added, and the visibility can be tuned by changing the incident angle and light wavelengths. This phenomenon is caused by the absorption of the graphene layer and the enhanced reflectance of the 1DPC. (C) 2007 American Institute of Physics.

The research of range-gated laser night vision system on cars - art. no. 68351V

The characteristic of several night imaging and display technologies on cars are introduced. Compared with the current night vision technologies on cars, Range-gated technology can eliminate backscattered light and increase the SNR of system. The theory of range-gated image technology is described. The plan of range-gated system on cars is designed; the divergence angle of laser can be designed to change automatically, this allows overfilling of the camera field of view to effectively attenuate the laser when necessary. Safety range of the driver is calculated according to the theory analysis. Observation distance of the designed system is about 500m which is satisfied with the need of safety driver range.