Lens-Less Imaging Technique Improved To Include More Depth In 3D
11 June 2014
UK company Phase Focus has come up with a technique that can visualize objects in 3D with increased depth without using a focusing lens after applying algorithms to diffraction patterns formed when an object is illuminated by coherent light.
The breakthrough in this imaging technique, called ptychography, is that researchers managed to image continuous specimens with a lateral resolution of 1 micrometer (0.001 millimeter or about 0.000039 inch). The axial resolution reached 2 microns in samples with thickness of up to 150 micrometers.
Phase Focus' Timothy Godden said that this small sectional depth was achieved by illuminating objects with focused 635 nanometer laser beams. According to Godden, although applying a lens-less approach to a microscope seems counter-intuitive, the benefits in terms of achievable 3D resolution outweigh the degradation due to aberrations that are present in conventional microscopy.
By breaking down the reconstruction process into steps structuring the illumination carefully, researchers were able to overcome the common problem in ptychography that samples with strongly scattering features - or larger ones with varying diffraction properties - can be more challenging for 3D algorithms.
Another challenge for developing superior ptychography tools is that specimens over 100 micrometers thick currently can't be imaged effectively, and still maintain the 2 micrometer axial resolution. As of now, Phase Focus claims its technology can image samples that are even one millimeter thick, but with compromised axial resolution. Still, the technology allows cells to be imaged without straining or labeling, which is a valuable simplification in key areas of cell biology.