Simultaneous Multichannel Waveform Recovery of Illumination Signals Using Compressed Sensing

A critical element of any time-of-flight (ToF) 3D imaging system is the illumination. Most commercial solutions are restricted to short range indoor operation and use simple illumination setups of single or few LEDs, grouped together. Recent developments toward medium and long range ToF imaging, ready for outdoor operation, bring the need for powerful illumination setups, constituted by many emitters, which might be grouped in distributed modules. Provided that the depth accuracy of ToF cameras strongly depends on the quality of the illumination waveform, assuring that a complex illumination system is providing a homogeneous in-phase wavefront is of capital importance to minimize systematic inaccuracies. In this letter, we present a novel framework for multichannel simultaneous testing of illumination waveforms, which is able to recover the waveform of the incident light on each pixel of a ToF camera, exploiting the sparsity of typical continuous wave illumination signals in frequency domain.