Modeling of the visual artifact in range-gated active imaging, especially in burst mode.

An active imaging system in burst mode allows the duty cycle of laser pulses to be close to 50%. In this configuration, a visual artifact resulting from a remote zone in the scene can appear in the image of the desired visualized zone. Therefore, the elements of this remote zone will create confusion in the image with erroneous estimated distances. These misinterpretations can be very disturbing when determining the distance of a target in the scene. In order to demonstrate the occurrence of visual artifacts with an active imaging system in burst mode, the different translated signals in the time domain as well as the atmospheric attenuation and the attenuation due to the inverse square distance were included in the modeling of this mode. A graphic method, which does not take into account the different attenuations, was also proposed to give an idea of the visual artifact phenomenon. The validity of the modeling was demonstrated by comparing the results of the outdoor tests carried out with an active imaging system in burst mode. Consequently, the simulation programs can use this modeling to evaluate the visual artifact in a scene.