Spatio‐Spectral‐Temporal Imaging of Fast Transient Phenomena Using a Random Array of Pinholes

Abstract

Fast transient phenomena such as light–matter interactions, rapid electrical discharge, light scattering in tissues, and biochemical reactions that generate light signatures can be studied using high‐speed cameras. Herein, a lensless, single camera shot, spatio‐spectral‐temporal imaging technique based on chaotic waves is proposed and demonstrated. A random pinhole array is used as a chaotic wave generator to map every color point source in the object space to a unique random distribution. The spatio‐spectral signatures are recorded for two cases using a monochrome high‐speed camera, and an extensive library of spatio‐spectral signatures is synthesized by computational interpolation and extrapolation using the scaling factors of the Fresnel propagators. A spark generated by an abrupt electrical discharge is converted into a chaotic wave using the same pinhole array, and the hologram is recorded using the monochrome high‐speed camera in time. The recorded hologram of the spark is decomposed into spatio‐spectral 4D events in time with a temporal resolution of 40 μs using the semisynthetic spatio‐spectral signatures.