First, moving objects with light can only be done in a very small scale. Now scientists are moving in the meter scale.
Transferring Objects With Light
More than 40 years scientists use radiation pressure of light to manipulate small objects in space, but until now the movement of these objects is limited to a very small scale, usually only a few hundred micrometers, and mostly done on the fluid-fluid . In the new study, scientists demonstrated a technique that produces very large optical manipulation in air using an optical trap that can move objects across distances measuring 100 micrometers in a meter scale with an accuracy of about 10 micrometers.
The researchers Vladlen Shvedov from the Australian National University in Canberra and the National University Tavrida in Simferopol, Ukraine and his fellow researchers published their research in the last edition of Physical Review Letters recently.
As described by scientists, move objects with light can be done using fotoresis effects on air and other gases. When a particle is heated unevenly by the light, some gas molecules rebound from the surface of the particles with different speeds that generate power on particles that are pressed in the direction of illumination or higher light to the lower illumination.
In the new study, scientists modify the light catcher system which is used to combine the optical vortex beams with a section similar to cake donuts create a pipeline of optical bright circular spot of light intensity serves as a barrier “wall pipes” that capture the light-absorbing particles in the dark center of the beam. Axial component of the light suppress thermal power vortex particles along the pipeline, and a movable mirror can control the direction of the beam to shoot particles at targets located at a distance of up to one meter.
The researchers demonstrated the long-distance optical manipulation using two types of particles: the group of carbon nano particles with diameter of 100 nanometers to 100 micrometers and carbon-coated hollow glass microspheres with a diameter of 50 to 100 micrometers. In both cases, the carbon surface makes these objects excellent light absorber which has a very low reflectivity. Experiments showed that the velocity fotoresis particles (which are in the order of several millimeters per second) varies depending on the internal structure of the particles and the variations associated with mass.
“Three things are quite different from the new science are combined in a single experiment,” says co-researcher Andrei Rode of the Australian National University, as quoted by PhysOrg. “Those things are is the use of thermal energy fotoresis to move the particles in the air as opposed to the light pressure force or energy of radiation in the optical tweezers in the liquid, the use of optical vortex beams with a donut shape similar to the cross section for forming an optical vortex pipeline , and the use of light-absorbing particles with low thermal conductivity such as carbon nano particle groups and cash-cash-coated glass micro-carbon. “
As demonstrated by the researchers, the technique may allow the light-absorbing particles to be manipulated with high accuracy tingakt even at large distances. The researchers were able to move the particles into a target located at a distance of 0.5 meters with an accuracy of 10 micrometers which they demonstrated with the use of particles with diameter between 60 to 100 micrometers.
“The farther the distance, the greater the laser power is needed so that the higher the danger of overheating or even burning particles,” Rode said. “So the distance is highly dependent on particle properties. With these particles we use, there should be no great challenge to move up to a distance of 10 meters.”
Manipulate particles with optical cross such distances can be for some applications such as touch-free transport containers that contain substances that are very pure or dangerous, including viruses, living cells and gases. As demonstrated by the scientists, the technique allows researchers to move containers in the opposite direction, speed it up a few centimeters per second, or hold it in place that did not move at any location in the pipeline. Because the technique can be applied to various materials, the technique can also be used to study particles in the air as aerosol-aerosol and also to map the plasma-dust plasma and dust in interstellar between other applications.