Thursday , October 6 2022

new device & # 39; trapping and optical filtering to manipulate, move tiny objects


When focusing beam & # 39; light on your hand, do not feel much, except for a little bit & # 39; Heat generated by the beam. When fire that same light into a world that is measured on the nano or micro scale, the light becomes a powerful tool to manipulate that you & # 39; use to move objects around – well caught in the light.

Researchers from the Light Group Structured from the School of Physics at the Witwatersrand University in & # 39; Johannesburg, Africa & # 39; South, found a way to use the full beam & # 39; laser light , to control and manipulate small objects like single cells in & # 39; body human factor, tiny particles in & # 39; of & # 39; small volume chemical, or working on future devices on the chip.

While specific technique, called trapping ottografiku holographic and tweezing, is not new, the researchers & # 39; wits found a way to use optimally the full force of light – including vector light not previously available for this application. This forms the first holographic trap vector.

"Traps previously holographic were limited to particular classes of & # 39; lighting (skalariku light), so it is very exciting that we can show a holistic way to cover all classes of & # 39; light, including replicate the all appliances & # 39; trapping previous ", Professor Andrew Forbes, collaboration and Distinwt Professor in the School of Physics which manages the wits Structured Light Laboratory.

"What we have done is that we have demonstrated the first system & # 39; trapping and optical tweezing with the system holographic. The device allows particles & # 39; as mikrometriku, such as biological cells, caught and just being manipulated by light . "

The final instrument can & # 39; picks up multiple particles in & # 39; sigh and move them just a vector states & # 39; light. The experiments for this study made by Nkosi Bhebhe as part of studies & # 39; doctorate. The work is published online in the journal Nature, Scientific Reports.

F & # 39; & # 39 conventional systems, optical trapping and tweezing, the light is focused properly in & # 39; small volume containing small particles, such as biological cells. On this small scale (typically micro- or nanometers) forces that light can & # 39; exercise significant, so that the particles can be trapped by the light and then controlled. As the light is conducted, the particles will move with it. This idea won out American scientist Arthur Ashkin the 2018 Nobel Prize in Physics. Originally the light was controlled by & # 39; mechanical way by stages and mirrors, but the idea was further improved by moving around the holographic light, ie the use of & # 39; hologram generated by computer to control light without moving parts and b & # 39; so controlling particles. Until now only special classes & # 39; laser beams, called scalar beams, can be used in & # 39; so holographic traps.

In their paper entitled holographic optical vector Trampa the wits researchers have shown how to create and control any design & # 39; olografikament light, and then used it to form a new device & # 39; trapping and optical tweezing.

"B & # 39; in particular, the device can & # 39; works with both & # 39; traditional laser beams (skalarji beams) as well as more complex vector beams. Vector traces are very topical and found many applications, but no vettorali holographic trap was possible until now ".

The researchers & # 39; wits show trap their new by controlling b & # 39; holographic way the rays of the scale of the vector in the same device, to advance the state & # 39; art and introduce a new device to the community. The group expects the new device is useful in & # 39; experiments controlled in micro and nano world, including studies & # 39; single cells in biology and medicine, chemical reactions & # 39; small volume, fundamental physics and future devices on the chip.

Having previously shown that it is possible to create hundreds & # 39; custom of lighting one hologram patterns, research brings & # 39; out their previous work on holographic light control with application & # 39; optical trapping and tweezing.

How does holographic optical trap

F & # 39; conventional optical trap, the light is focused properly so it can & # 39; exert forces on the matter. The question, ie a particle, caught in the light. When the light driven by & # 39; mirrors or mechanical steps, so the particle moves with it. This is called optical trapping (catching particle) and optical tweezing, moving the particle as if with tweezers, but in & # 39; in this case tweezers made of light. To control becomes less mechanical, researchers have used holograms to control light. With one spatial modulators of light can & # 39; encoding structured light patterns and shift those trends within the trap, so many particles can be trapped and moved simultaneously. This has opened up many new exciting areas, but the final holographic optical traps (HOTs) were limited to scales beams & # 39; light, a small fraction of & # 39; what was possible. The other class of & # 39; optical beams, vector states, were not possible for the holographic control. With new vector HOT, all lighting states can now be used. Time will time what it means for the community in general.


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