Two holdovers from my trip to Baltimore for SPIE DSS 2012 have appeared on Optics.org:
Since shining a laser pointer in the general direction of an aircraft pilot seems to be the jape that won’t go away, optical filters that can limit the dazzle are in demand, and the military are just as interested in them as commercial airlines – probably more. Filters usually work by blocking the particular laser wavelengths used in your average pointer, but a better approach might be to block incident light based on its power instead. KiloLambda showed off a wide-band filter that uses a layer of carefully manufactured nanostructures and exploits their non-linear optics to block laser light when it passes a designated power threshold. Below that, the filter stays clear at all wavelengths; above it, transmission is either limited to a certain value or blocked completely.
Nanstructures are also the key to a scintillator material made by the applied research arm of Georgia Tech, a cerium-doped gadolinium halide material cast in a glass that scintillates when hit by incoming gamma-rays. If the nanoparticles used can be held below a certain size, and about 20 nanometers or so seems to do it, then the scattering of the scintillated light which can bedevil any kind of accurate reading is drastically reduced. Plus a glass or glass-ceramic material is much easier to handle than a fragile scintillation crystal. Plenty of room for improvement in the resolution, though.
And away from DSS: further work on retinal implants, a topic that has now entered the watch-lists of TV news producers everywhere. The principle of restoring sight to someone suffering from a condition like age-related macular degeneration hinges on the fact that it’s the photoreceptors in the retina that have died, not the neurons behind them. Implants to take over the job of the receptors and fire the neurons when light hits the retina are well past the status of pipe dreams, but there are a wealth of problems – not least among them, how to power the array of photoreceptors while it goes about its business. A group from Stanford University, applying scrupulous logic, think the answer may be to build an implant which draws its power from the same incoming infra-red light which brings the visual data, and their lab trials suggest that they’re on the right lines. Not quite a solar-powered retinal implant, but not too far off. Not a bionic eye either, although Steve Austin is the gift that keeps on giving for headline writers on a deadline.