Snapshot Three-Dimensional Absorption Imaging of Microscopic Specimens

Snapshot projection optical tomography (SPOT) uses a microlens array (MLA) to simultaneously capture the projection images of a three-dimensional (3D) specimen corresponding to different viewing directions. Compared to other light-field imaging techniques using an MLA, SPOT is dual telecentric and can block high-angle stray rays without sacrificing the light collection efficiency. Using SPOT, we recently demonstrated snapshot 3D fluorescence imaging. Here we demonstrate snapshot 3D absorption imaging of microscopic specimens. For the illumination, we focus the incoherent light from a light-emitting diode onto a pinhole, which is placed at a conjugate plane to the sample plane. SPOT allows us to capture the ray bundles passing through the specimen along different directions. The images recorded by an array of lenslets can be related to the projections of 3D absorption coefficient along the viewing directions of lenslets. Using a tomographic reconstruction algorithm, we obtain the 3D map of absorption coefficient. We apply the developed system to different types of samples, which demonstrates the optical sectioning capability. The transverse and axial resolutions measured with gold nanoparticles are 1.3 and 2.3 mu m, respectively.

Automated summary

SPOT utilizes a microlens array to capture projection images of 3D specimens, demonstrating snapshot 3D fluorescence and absorption imaging. By using specific illumination and lenslet combinations, a 3D map of absorption coefficient can be obtained with good transverse and axial resolutions.