Light-in-flight recording by holography

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.