Fig. 1.

A photograph (left) and a schematic diagram (right) of the field-portable lensfree tomographic microscope (weighing ~110 grams) are shown. 24 LEDs are butt-coupled to individual optical fibres, which are mounted along an arc to provide multi-angle illumination within a range of ±50°. LEDs are sequentially turned on by a micro-controller to record projection holograms of the objects. At each angle, multiple sub-pixel shifted holograms are recorded to synthesize projection holograms with enhanced numerical aperture and resolution. These holograms are digitally processed to first obtain projection images, and then to compute tomograms with <7 μm axial resolution over a large sample volume of ~20 mm³ on a chip.