Ultrafast 3D imaging in soft X-ray region

Lensless Fourier transform holography (FTH) is known as an imaging method suitable for high resolution X-ray microscopy with coherent X-rays. In FTH, there had been a limit on the spatial resolution, mainly because of the contradiction between the requirement on the numerical aperture and the realistic resolving power of high spatial frequency fringes that appeared in the hologram. Multiplexing, i.e., the use of multiple object and reference signals, can be one promising solution, because it extends the effective field of view. Recently, a research group led by Professor J. Stöh, a director of Stanford Synchrotron Radiation Laboratory (SSRL), has developed the technique further so that the measurement can be done by a single shot. Using patterned masks to provide multiple X-ray sources, the team demonstrated the ability to record images simultaneously at different parts of the sample. 3D imaging of ultrafast processes could become a reality if the method is combined with so-called pump-probe experiments. For more information, see the paper, "Extended field of view soft x-ray Fourier transform holography: toward imaging ultrafast evolution in a single shot", W. F. Schlotter et al., Optics Letters, 32, 3110-3112 (2007).