Diffraction-Assisted Light Field Microscopy for Microtomography and Digital Volume Correlation with Improved Spatial Resolution

Light field microscopy (LFM) is capable of ultrafast tomographic reconstruction using a light field image acquired in a single snapshot. However, the axial resolution of LFM is inferior to its lateral resolution and is non-uniform in the axial direction. A diffraction-assisted light field microscopy (DLFM) method is proposed in this work to achieve resolution enhancement over the conventional LFM. DLFM makes use of a transmission diffraction grating inserted between the specimen and microscope objective. Light field images of different diffraction orders are formed on the sensor plane and encode both the spatial and angular information of light rays emanating from the specimen. A wave optics model is developed to derive the point spread functions (PSFs) of DLFM, which are then used to deconvolute the light field images for tomographic reconstruction. Validation tests are performed on both experimental and simulated data and the results show that DLFM effectively improves the axial resolution without compromising the lateral resolution. Furthermore, we show that tomographic reconstruction using DLFM can be combined with digital volume correlation (DVC) to achieve three-dimensional, full-field displacement measurement.