Optics

A terrestrial laser scanning technique that allows the structure of vegetation to be 3D-mapped to the millimeter is more accurate in determining the biomass of trees and carbon stocks in forests than current methods, according to a paper in Methods in Ecology and Evolution

The study authors believe it could be used in monitoring carbon stocks for climate policy. Both above-ground biomass and carbon stocks are important details for UN-REDD, the United Nations initiative on Reducing Emissions from Deforestation and forest Degradation that is striving to keep the destruction of forests in check and thereby preserve the uptake of carbon by trees.

A new optical technique by which audio information can be extracted from high-speed video recordings, by using an image-matching process based on vibration from sound waves.

The technique is based on the fact that sound waves are mechanical waves that cause air to vibrate when traveling, the paper notes. That vibration through air can cause vibration of objects located in its traveling path, especially if the objects are lightweight, thin, and flexible, such as a piece of paper. The vibrations, although usually with small amplitudes, can be detected and analyzed algorithmically, and audio reconstructed based on those calculations.


On a quest to design an alternative to the complex approaches currently used to produce electrons within microwave electron guns, a team of researchers have demonstrated a plug-and-play solution capable of operating in a high-electric-field environment with a high-quality electron beam.

Unfamiliar with microwave electron guns? They provide a higher current and much higher quality electron beams than conventional DC guns for X-ray sources . Beams of this sort are also used in free-electron lasers, synchrotrons, linear colliders and wakefield accelerator schemes. But the electron emission mechanisms involved -- laser irradiation of materials (photocathodes) and heating of materials (thermionic cathodes) -- tend to be complex, bulky or extremely expensive.


Laser-powered weapons have been a staple of science-fiction movies for so long we think we know what they would look like, but we really don't.

Researchers at the Laser Centre of the Institute of Physical Chemistry of the Polish Academy of Sciences and the Faculty of Physics, University of Warsaw decided to find out, and make a real film of it. They fired an ultrashort laser pulse through the air and captured it on video and when they slowed it down they found that it looks lot like a regular bullet, and a lot like a "Star Wars" light saber - combined. 


A long-distance optical tractor beam can move tiny particles - one fifth of a millimeter in diameter - a distance of up to 20 centimeters, which is almost 100 times further than previous experiments.


The hollow laser beam is bright around the edges and dark in its center and it can be used to attract or repel objects.

Get ready to control the weather or capture an X-Wing fighter in space - if it's really close, that is.



Dr. Vladlen Shvedov (L) and Dr. Cyril Hnatovsky adjust the hollow laser beam in their lab at the Australian National University. Credit: Stuart Hay, ANU


In Lewis Carroll's Through the Looking-Glass, and What Alice Found There, the 1871 sequel to Alice's Adventures in Wonderland, the title character finds a mirror that behaves in a surprising and unexpected way.
 
Now bizarre mirrors have become a reality.

In an Optica report, scientists have demonstrated, for the first time, a new class of mirror that works like no other
- it forgoes a familiar shiny metallic surface and instead reflects infrared light by using an unusual magnetic property of a non-metallic metamaterial.  


Look into the light - unless you want to keep your memories.

UC Davis psychologists have used light to erase specific memories in mice and proved a basic hypothesis fpr how different parts of the brain work together to retrieve episodic memories. Optogenetics, created by Karl Diesseroth at Stanford University, is an effort at manipulating and studying nerve cells using light. The techniques of optogenetics are becoming popular for brain function studies.


Optical sensors are used all around the world to monitor the condition of difficult-to-access places like the underbellies of bridges, the exterior walls of tunnels, the feet of dams, long pipelines and railways in remote areas.


Electrical engineering researchers have developed a unique nanoscale device that demonstrates mechanical transportation of light.

The nanoscale device that can capture, measure and transport fundamental particles of light - photons. The tiny device is just 0.7 micrometers by 50 micrometer (about .00007 by .005 centimeters) and works almost like a seesaw. On each side of the "seesaw benches," researchers etched an array of holes, called photonic crystal cavities. These cavities capture photons that streamed from a nearby source. 


Using twisted light to send data at almost unimaginable speeds is not new but researchers have developed a similar technique using radio waves - high speeds without the hassles that go with optical systems.