Light-in-flight recording by holography

Abstract

A flat object surface and a hologram plate are both illuminated at an oblique angle by laser light of short pulse duration or short coherence length. Only those parts of the object surface are holographically recorded that correspond to a small-pathlength difference between object beam and reference beam. The holographic plate therefore corresponds to an infinite set of gated viewing systems triggered by the traversing reference beam. Scanning along the processed plate produces a continuous-motion picture of the light in flight. This new technique probably represents the ultimate in high-speed photographic recording, as no mechanical or electrical inertia is involved.

Non-invasive imaging through opaque scattering layers

“…For semi-transparent media it is possible to perform imaging using gated techniques to separate the small amount of ballistic light that did not change direction from the scattered background. [2][3][4][5] Yet the achievable resolution rapidly degrades when the scattering becomes stronger 6 and this method breaks down when all ballistic light is blocked. Alternatively diffuse wave tomography techniques can locate absorptive objects deep inside a scattering medium 7 but do not permit to resolve details.…”

Diffuse Mirrors: 3D Reconstruction from Diffuse Indirect Illumination Using Inexpensive Time-of-Flight Sensors

“…Light-in-Flight Imaging [1] refers to a novel imaging modality in which short pulses of light are observed "in flight" as they traverse a scene and before the light distribution achieves a global equilibrium. Specifically, a transient image is a rapid sequence of images representing the impulse response of a scene.…”

“…Most recently, researchers have started probing the temporal response of macroscopic scenes to non-stationary illumination, effectively resolving light contributions by the total length of the optical path [1,11]. Experimental evidence suggests that such unmixing of light contributions will benefit many challenges in computer vision, including the use of diffuse reflectors to image objects via the time profile of reflections from ultra-short laser pulses, so-called transient images [20,7].…”

Femto-photography

“…Liquid nonlinear shutters actuated with powerful laser pulses have been used to capture single analog frames imaging light pulses at picosecond time resolution [Duguay and Mattick 1971]. Other sensors that use a coherent phase relation between the illumination and the detected light, such as optical coherence tomography (OCT) [Huang et al 1991], coherent LiDAR [Xia and Zhang 2009], light-in-flight holography [Abramson 1978], or white light interferometry [Wyant 2002], achieve femtosecond resolutions; however, they require light to maintain coherence (i.e., wave interference effects) during light transport, and are therefore unsuitable for indirect illumination, in which diffuse reflections remove coherence from the light. Simple streak sensors capture incoherent light at picosecond to nanosecond speeds, but are limited to a line or low resolution (20 × 20) square field of view [Campillo and Shapiro 1987;Itatani et al 2002;Shiraga et al 1995;Gelbart et al 2002;Kodama et al 1999;Qu et al 2006].…”