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Biotechnology - Physics - Radiology and Medical Imaging

Giga-Pixel Lensfree Holographic Microscopy and Tomography Using Color Image Sensors
Published: Wednesday, September 12, 2012
Author: Serhan O. Isikman et al.

by Serhan O. Isikman, Alon Greenbaum, Wei Luo, Ahmet F. Coskun, Aydogan Ozcan

We report Giga-pixel lensfree holographic microscopy and tomography using color sensor-arrays such as CMOS imagers that exhibit Bayer color filter patterns. Without physically removing these color filters coated on the sensor chip, we synthesize pixel super-resolved lensfree holograms, which are then reconstructed to achieve ~350 nm lateral resolution, corresponding to a numerical aperture of ~0.8, across a field-of-view of ~20.5 mm2. This constitutes a digital image with ~0.7 Billion effective pixels in both amplitude and phase channels (i.e., ~1.4 Giga-pixels total). Furthermore, by changing the illumination angle (e.g., ±50°) and scanning a partially-coherent light source across two orthogonal axes, super-resolved images of the same specimen from different viewing angles are created, which are then digitally combined to synthesize tomographic images of the object. Using this dual-axis lensfree tomographic imager running on a color sensor-chip, we achieve a 3D spatial resolution of ~0.35 µm×0.35 µm×~2 µm, in x, y and z, respectively, creating an effective voxel size of ~0.03 µm3 across a sample volume of ~5 mm3, which is equivalent to >150 Billion voxels. We demonstrate the proof-of-concept of this lensfree optical tomographic microscopy platform on a color CMOS image sensor by creating tomograms of micro-particles as well as a wild-type C. elegans nematode.