| 摘要 |
An active infra-red surveillance illuminator uses a statistically mono-directional micro-diffractive material overlaid on a bank of light emitting diodes (LEDs) to refract light from the LEDs onto a target image. This delivers energy distribution profiles out to a distance to match the aspect ratios of current wide-angle target and wide-angle camera surveillance systems. The distribution of refracted light is elliptical. This distribution can vary by using different diffractive material in conjunction with various numbers, brightness and angles of the LEDs in an LED bank. The effective range of the illuminators is greatly extended with this type of illumination. By limiting infrared (IR) radiation down to a 10 degree vertical window it renders the IR illumination much more effective for surveillance imaging by providing much more effective power on wide, ground-level scenes, and particularly enables multi-lane license plate capture. |
