Lasers

Researchers at the Risø National Laboratory for Sustainable Energy at the Technical University of Denmark, have demonstrated for the first time the use of a wind turbine equipped with a laser for improved performance^†.

We've previously reported on the use of light patterning techniques to manipulate the movement of particles in solution (Microscopic particle manipulation for screening operations), but now the method has been improved upon and we can see it in action.

Lasers which can control the movement of particles are still confined to the microscopic world, but if you have an over-reactive imagination, you might wonder just what the limits are on the size of bodies which these devices can control and whether science fiction's tractor beams are becoming a reality. Today's technology may not be capable of producing force fields that lock on to starships and guide them in to land, but the size of particles which can be manipulated by light are getting larger.

While I was leafing through the news stories of the past week, looking for something big in the world of optics, I received a press release about something really big: the world's largest laser is now complete. Read on for the full press release from Lawrence Livermore National Laboratory.

Counterfeit and smuggled goods are said to be one of the fuels that drive organised crime, so it is essential that products can be identified to determine if they are genuine and where they came from. Some manufacturers go to extreme lengths to incorporate hard to replicate anti-counterfeit labels or devices into their products, but it's a game of catch up and it isn't long before the criminals find a way of defeating those measures. So how about using no anti-counterfeit measures at all? This is the approach being promoted by Russell Cowburn at Imperial College in London, who is researching a method called Laser Surface Authentication (LSA), which relies on unique, microscopic identifiers already inherent in products or their packaging.

A novel approach to harvesting the energy of the sun is described in a recent paper in the Journal of Applied Physics, which reports on one of the key components in the system: a solar powered laser¹.
 
 

The advances in optically controlled micromanipulation are continuing at a rapid pace. A recent paper published in Applied Physics Letters describes an optically-driven rotor^†, which could be the precursor to nanopumps, miniature mechanical pumps that could drive suspended particles around circuits in microfluidic applications.

It has been likened to an optically driven snowblower for microscopic particles and could see practical use for the sorting of micrometre sized particles. Researchers from the University of Saint Andrews in the UK have reported on their work using Airy beams for particle clearing, in an advance online publication for Nature Photonics^†.

Precious stones are an enduring fascination for mankind and for centuries they've been traded and given as gifts, either as polished stones or embedded in jewelery. In so doing, they have traversed the planet, sometimes ending far from the source from which they were mined. Apparently a gem's origin is not only a matter of curiosity but can in fact have a significant bearing on its value. Scientists from New Mexico State University in the US have proposed a way of extracting information about a gem's origin from its chemical composition by using laser-induced breakdown spectroscopy (LIBS)¹.

Optical fibres can be used in a variety of ways to perform remote sensing operations. Take the case of the Fibre Fabry-Pérot (FFP) interferometer, for example. Working on the principle of light interference produced by two parallel reflecting surfaces either side of a small cavity, they can be constructed in different ways, either with an external cavity, or with the cavity located within the body of the fibre itself. They can be used to measure pressure, temperature or strain, all by detecting changes in the optical path length of the cavity due to environmental influences. They can even be used as chemical sensors because the optical path length in the cavity is related to the refractive index of the medium inside. Researchers at the Missouri University of Science and Technology have come up with a way in which to do just that, in such a way that produces a highly robust device suitable for chemical sensing¹.