PHYSICS: Speeding Up Holography

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Science  23 Nov 2007:
Vol. 318, Issue 5854, pp. 1218c
DOI: 10.1126/science.318.5854.1218c

The ability to produce ultrashort electron bunches and x-ray and optical pulses has allowed researchers to glimpse fleeting structural and electronic rearrangements occurring on femtosecond or shorter time scales. However, these pump-probe measurements often tend to provide a somewhat limited series of one- or two-dimensional (2D) snapshots of the processes at play. Two groups now show how holographic imaging—a technique in which the interference of two light beams encodes 3D information on a 2D detection surface—can be extended to the ultrafast regime, thereby raising the possibility of obtaining more detailed, fully dynamical 3D movies of processes taking place on these rapid time scales. Kubota et al. demonstrate the use of optical holography to track light images formed from femtosecond red light pulses as they are launched into an optical medium; the result is a spatially and temporally continuous movie of the images propagating, converging into a focal point, and then diverging again. Schlotter et al. extend ultrafast holography to shorter wavelengths in the x-ray regime. Using patterned masks to provide multiple x-ray sources, they demonstrate the ability to record images simultaneously at different parts of the sample. They note that combining this multi-spatial sampling with gated pump-probe illumination could extend the technique to 3D imaging of ultrafast processes. — ISO

Opt. Express 15, 14348 (2007); Opt. Lett. 92, 3110 (2007).

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