Cheap, full-colour images from lens-free microscope

Editorial

Rebecca Pool

Tuesday, June 13, 2017 - 11:00
Spectral light fusion microscopy: intensity projection of lung tissue [Wong et al/University of Waterloo]
 
Canada-based researchers have developed a new form of light-field imaging - spectral light fusion microscopy - to capture full-colour, light-field images of tissue and fluid samples for pathology applications.
 
The several-hundred-dollar lens-free microscope uses artificial intelligence and modelling to capture interferometric data and reconstruct 3D images at a large scale.
 
With their latest microscope, Professor Alexander Wong, co-director of the Vision and Image Processing Lab at the University of Waterloo, and colleagues, can construct nanometre-resolution images with a ultra-wide field-of-view, more than 100 times greater than that of 40X optical microscopy systems.
 
Professor Alexander Wong (right) and colleagues have pioneered spectral light-field fusion microscsopy for cheap pathology applications.
 
"This technology has the potential to make pathology labs more affordable in communities that currently don't have access to conventional equipment," highlights Wong.
 
While large 3D images are typically produced by stitching together multiple images from conventional microscopes, this process demands equipment that can cost hundreds of thousands of dollars.
 
Given this, wide-field on-chip microscopy, which uses holography principles to capture interferometric information without lenses, is gaining widespread interest.
 
Wong and colleagues have now introduced the idea of laser light-field fusion for lens-free on-chip phase contrast microscopy, to produce nanometre-scale images.
 
Initial instrument with interferometric light-field encodings; scale bar: 1mm [Kazemzadah et al, Scientific Reports 6,  38981 (2016)]
 
They have developed compact pulsed lighting and detection apparatus to first capture interferometric laser light-field encoding, at different wavelengths.
 
They then use a Bayesian-based fusion method to combine and reconstruct high-resolution, marker-free phase contrast images of particles at the nanoscale.
 
The researchers have detected 300 nm particles across a 30 mm² field-of-view, without specialised sample preparation or the use of synthetic aperture- or lateral shift-based techniques.
 
And using this instrument they have acquired intensity projections of lung cells, a bee's head and more.
 
Spectral Light-field fusion imaging achieves 4D label-free tomographic imaging of biological specimens in a low-cost, compact form factor.
 
As Wong points out, acquiring the interferometric light-field encoding takes less than ~3 ms - equivalent to >300 frames per second - enabling studies of highly time-resolved dynamic systems or transient phenomena.
 
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