  We report a light-field based method that allows the optical encryption of
three-dimensional (3D) volumetric information at the microscopic scale in a
single 2D light-field image. The system consists of a microlens array and an
array of random phase/amplitude masks. The method utilizes a wave optics model
to account for the dominant diffraction effect at this new scale, and the
system point-spread function (PSF) serves as the key for encryption and
decryption. We successfully developed and demonstrated a deconvolution
algorithm to retrieve spatially multiplexed discrete and continuous volumetric
data from 2D light-field images. Showing that the method is practical for data
transmission and storage, we obtained a faithful reconstruction of the 3D
volumetric information from a digital copy of the encrypted light-field image.
The method represents a new level of optical encryption, paving the way for
broad industrial and biomedical applications in processing and securing 3D data
at the microscopic scale.
