Optics

We all understand light has a wide electromagnetic spectrum and we only see a small band of that. In physics terms, that is between 400 - 700 nanometers and they show up as colors,from violet to red.

We can't see in the ultraviolet radiation spectrum because it is a shorter wavelength than what we can detect - violet - which is why it's in the name, and we can't see infrared because its wavelength is longer than red, which is why the name is infrared. 


Lasers are ubiquitous but there are still wavelengths for which only large and expensive ones exist, or none at all. Remote sensing and medical applications call for compact laser systems, for example with wavelengths from the near infrared to the Terahertz region and now researchers at the Technische Universitaet Muenchen and the University of Texas Austin have developed a 400 nanometer thick nonlinear mirror that reflects frequency-doubled output using input light intensity as small as that of a laser pointer.


The high power needed to cut or weld using a laser beam creates its own problem: the beam’s energy deforms the mirrors that focus it. When that happens, the beam expands and loses intensity.

A new type of mirror is being presented at the Optatec trade fair in Frankfurt next week - it can deform itself to correct deformation the laser beams it controls.

Lasers are used in manufacturing to cut materials or weld components together. Laser light is focused to a point using various lenses and mirrors obviously, the smaller the focal point and the higher the energy, the more accurately operators can work with the laser.

If you have ever seen set pieces from a science-fiction show, you have probably been amazed at how cheap and silly the whole things looks. That was the initial concern with high-definition television too. Standard definition hid a lot of cosmetic defects in people and things that are quite obvious in the real world.

Lighting can do the same thing in the real world, of course. Everyone has had a table in their place that looked fine, only to open the windows and have natural light reveal a layer of dust. 


An array of tiny, metallic, U-shaped structures deposited onto a dielectric material creates a new artificial surface that can bend and focus electromagnetic waves the same way an antenna does.


The complexity of biology can befuddle even the most sophisticated light microscopes because biological samples bend light in unpredictable ways, returning difficult-to-interpret information to the microscope and distorting the resulting image.

New imaging technology developed at the Howard Hughes Medical Institute's Janelia Farm Research Campus rapidly corrects for these distortions and sharpens high-resolution images over large volumes of tissue. 


Exposure to short wavelength, blue, light during the biological day directly and immediately improves alertness and performance.

In order to determine which wavelengths of light were most effective in warding off fatigue, the researchers teamed with George Brainard, PhD, a professor of neurology at Thomas Jefferson University, who developed the specialized light equipment used in the study. Researchers compared the effects of blue light with exposure to an equal amount of green light on alertness and performance in 16 study participants for 6.5 hours over a day. Participants then rated how sleepy they felt, had their reaction times measured and wore electrodes to assess changes in brain activity patterns during the light exposure.  


A project to develop fast-blinking LED systems for underwater optical communications has led to discovering that an artificial metamaterial can increase the light intensity and "blink speed" of a fluorescent light-emitting dye molecule.

The nanopatterned layers of silver and silicon in the new material sped up the molecule's blink rate to 76 times faster than normal, while producing an 80-fold increase in its brightness.


Experiments with ultrashort laser pulses support the idea that quantum interactions between molecules help plants, algae, and some bacteria efficiently gather light to fuel their growth - but that's about it. Key details of nature's vital light-harvesting mechanisms remain obscure, and the exact role that quantum physics may play in understanding them is more subtle than was once thought.


Raman scattering mode is an optical phenomenon, discovered in 1928 by the physicist Chandrasekhara Venkata Raman, that involves the inelastic scattering of photons - the physical phenomenon by which a medium can modify the frequency of the light impinging on it. 

The difference corresponds to an exchange of energy (wavelength) between the light beam and the medium. In this way, scattered light does not have the same wavelength as incidental light. The technique has become widely used since the advent of the laser in the industry and for research .