Concepts of holography, long associated to the world of 3D projections, entertainment and science fiction, are routinely applied in medical imaging, in fraud and security issues, in data storage, etc. Now holography is moving into microscopy, nanoscopy and bio-imaging applications. ICFO researchers Lisa Saemisch, Unai Ortiz-Orruño and Matz Liebel implemented holographic microscopy schemes to take advantage of the interferometric sensitivity and 3D-capacity, for ultrafast 3D particle tracking, particles sizing and particle identification.
Merging ultrafast spectroscopy, wide-field nanoscopy, and digital holography they realized an ultrafast holographic transient microscope, enabling parallel 3D-tracking of fs-ps dynamics of many particles in wide field imaging (Figure 1).
By imaging in the Fourier plane (k-space) the scattering signal of all particles was projected onto all camera pixels, thus dramatically boosting the achievable dynamic range for quantitative sizing (Figure 2).
Finally, directly visualizing the phase response of individual nanoparticles they devised a simple widefield method for distinguishing metallic and dielectric particles purely based on their spectral phase behavior.
These results pave the way to single-shot 3D microscopy of 2D and 3D materials on arbitrary time scales from femtosecond carrier dynamics in advanced materials to millisecond dynamics in complex tissues and cells.