OSA Incubator Meeting
Controlled Light Propagation through Complex Media
5-7 March 2014
OSA Headquarters • Washington, DC, USA
Thomas Bifano, Boston University, United States; Sylvain Gigan, Institut Langevin, France; Jerome Mertz, Boston University, United States; Allard Mosk, University of Twente, Netherlands
Recent breakthroughs have allowed, for the first time, exploitation of the interaction between light and strongly scattering or turbid media to focus or shape the light. The excitement generated by a series of firsts – enhanced beam focusing through nearly opaque media, imaging around corners using wall-induced scatter, and compressing short laser pulses diffusively – has led to serious efforts to solve longstanding optical challenges. Those include imaging deep within dense neural tissue and controlling beam propagation through turbulent horizontal paths.
The techniques, components, challenges and opportunities associated with this emerging field will form the core of this meeting. The basic science involves coherent combination of light modes that are generated by propagation of light through a scattering medium, to achieve some optical objective. Accordingly, the field’s main avenues of research involve understanding those modes and how they interact, and controlling modes within a medium, or after propagation through a medium, using a modulator in the beam path. Some important technical challenges discussed at this Incubator Meeting included:
Can the efficiency of optimization that links the mode controller (e.g. the spatial light modulator) to the sensor (e.g. a photo sensor at desired focus) be improved? Can optimization algorithms be linked deterministically to the physical state of the scatterer?
Can the system be made “one-sided” so that the sensor and the modulator are both on the same side of the scattering medium, even when the control objective (e.g. the focus point) is on the other side of the medium?
What kinds of systems will allow imaging or beam control inside of the medium (most systems to date use the medium only as an intermediate element).
Can imaging and acoustics be linked to improve the capacity of such systems to image or focus deep within tissue?
Technology issues also abound. The field, to date, has benefitted from experiments conducted on mostly rigid and relatively thin media. There are severe limitations to the technique when these limits are relaxed. Faster spatial light modulators and more efficient optimization techniques are needed to make the leap from technology demonstrations to systems of practical utility.
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