Category Archives: Publications

Scattering in the Cloud

Clouds in the sky get their white colour from the scattering of light. This is a well-understood phenomenon, yet notoriously difficult to compute. Deep-tissue microscopy relies on controlling light scattering within biological tissue, so we take a particular interest in this issue. By mapping Maxwell’s equations onto the structure of a neural network, we were able to scale up light wave scattering calculations on the cloud, more specifically, the Google Colab cloud.

We integrated this into the open source MacroMax EM solver, ideal for computing coherent scattering in highly-heterogeneous materials such as biological tissue. It is straighforward to install and use with Python. Well within 10 minutes, light wave scattering can now be computed throughout a complex 3D structure with all 3 sides >100μm!

Read more about how this works in our recently published paper doi: 10.34133/icomputing.0098.

Wavefront Shaping for Biomedical Imaging book available!

wavefront shaping bookTogether with K. Dholakia I authored a book chapter “Shaped Beams for Light Sheet Imaging and Optical Manipulation” in the book “Wavefront Shaping for Biomedical Imaging” (online ISBN: 9781316403938), published by Cambridge University Press: doi:10.1017/9781316403938. For those interested in wavefront shaping and its applications, the book contains many interesting contributions (TOC).

Automated detection of neutropenia

Our work on automated detection of neutropenia is published in the American Journal for Hematology! The blood flow in the capillaries is imaged through the nail-fold skin. Machine learning techniques are applied to detect the location of the capillaries in the image, and spatio-temporal correlations are analysed per capillary. Read more here: doi:10.1002/ajh.25516, and check out the Supporting Info!

Finally a fast algorithm to calculate the light field!

complex scatteringBiological samples, often the subject of optical microscopy, tend to be rather heterogeneous. This affects the propagation of the electromagnetic field of light. While the Maxwell’s laws underlying the propagation of electromagnetic waves in such tissue are well-understood; accurate numerical calculation does not scale well. Even the sub-millimeter-sized sample areas in microscopy pose significant challenges. Recently this changed. Osnabrugge et al. proposed a modification to the efficient Born series that is guaranteed to converge for Helmholtz problems. We have now extended this to solve Maxwell’s equations. The algorithm works for both isotropic and anisotropic dielectric materials, including those with chiral and magnetic properties. Our paper is available on doi:10.1364/OE.27.011946 (open access). The algorithm is made available as a Python library: pip install macromax, documentation and the MacroMax source code with examples can be found on GitHub.

Deeper Raman spectroscopy

Our latest paper “Enhanced deep detection of Raman scattered light by wavefront shaping” is published: doi: 10.1364/OE.26.033565 (open access). Raman spectroscopy tends to expose the sample to high levels of radiation. This is aggravated when probing deeper areas of — scattering — biological tissue. Here, we show how wavefront shaping can be used to increase the depth at which Raman spectroscopy can be performed in scattering materials, without increasing the exposure at the surface of the sample.