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As a field of active research, laser optical trapping allows the movement and position of particles of different sizes and shapes to be controlled. The ability to move small particles in a precise and controlled manner is important for basic and applied science. For example, the ability to control the motion of isolated atoms can be used to achieve quantum computing, and research also contributes to the study of biological specimens and pollutants.
Scientists at Tel Aviv University have now operated for 2,300 years. An old water displacement technology to develop a new laser beam that traps and displaces particles in specific directions.
"We have created a light beam that looks like an Archimedean screw," says Dr. Alon Bahabad of the Physical Optics Laboratory at the TAU School of Electrical Engineering. "Instead of traveling in a straight line like regular laser beams, our beam consists of two helical strands, similar to the shape of the DNA, and we can use this beam to move very small particles. whose size varies between tens of nanometers to about 10 microns, are transported. "
The study, published in the journal Optica was conducted by the students of Dr. Bahabad Barak Hadad, Sahar Froim and Yaniv Eliezer in collaboration with Dr. Yael Roichman at the TAU School of Chemistry and students Harel Bagar and Tamir Admon
From Water to Light
Archimedes, a Greek scientist who lived in the 3rd century BC, is credited with inventing one of the first effective water pumps: a wide-threaded screw, bent around an axis enclosed by a cylinder or a tube.
"A major challenge in laser optical trapping is how to move particles to a light source," Dr. Bahabad sa ys. "It's a problem because particles tend to move with light flow, or are pushed downstream, so to speak, our goal was to generate upstream movement of the particles trapped for create a tractor beam. We did exactly that by referring to an old idea. "
Archimedes demonstrated that the rotation of a mechanical screw moves the water along the axis of the screw, against the gravitational pull." We designed a Stylish tractor beam based on this simple idea, "says Dr. Bahabad." In our case, the movement of trapped particles depends on the rotation of the beam: if you rotate it on one side, the particles are pushed towards downstream, rotate it in the other direction, and they are fired upstream. "
Standing Wave
Dr. Bahabad and his team combined different beams bright to create an interference pattern called a standing wave.These interference patterns are characterized by the alternation of bright and dark areas.The particles contained in the beams were trapped by the movements of Air near the particles due to heat deposited by the beam
"When the particle is in a shiny area of the beam, it becomes hot and repelled by the air molecules toward the darker regions," says Dr. Bahabad. "When we rotate the beam, the dark areas move and carry the trapped particles with them, allowing a dispenser with a screw to move the snacks to work
" We think our discovery may find applications in biology, materials science. , spectroscopy or any other area requiring monitoring of different materials or biological samples. "
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Material Provided by American Friends of Tel Aviv University . Note: Content may vary for style and length.
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