Combination of the two styles of the multiple-wavelength range-gated active imaging principle for four-dimensional imaging.

Having previously reported the foundations of the multiple-wavelength range-gated active imaging (WRAI) principle in juxtaposed style and in superimposed style, its use in combination of both styles was studied. The juxtaposed style consists of restoring the 3D scene directly. Each emitted light pulse with a different wavelength corresponds to a visualized zone with a different distance in the scene. In superimposed style, each wavelength is superimposed in the scene at a specific moment in time. By combining these two styles and independently of the video frequency, it is possible to deduce the trajectory and direction of the object in 3D space as well as its speed between two consecutive positions from a single recorded image. Furthermore, with the help of range gating, the object visibility through scattering environments is improved. In order to separate both styles in the image, the wavelengths were separated into warm colors for depth and cold colors for time. The experimental tests confirmed the ability to record a moving object in a 4D space represented by a single image, thus validating the combined WRAI principle.