Abstract
Optical tweezers are powerful tools based on focused laser beams. They are able to trap, manipulate, and investigate a wide range of microscopic and nanoscopic particles in different media, such as liquids, air, and vacuum. Key applications of this contactless technique have been developed in many fields. Despite this progress, optical trapping applications to planetary exploration are still to be developed. Here we describe how optical tweezers can be used to trap and characterize extraterrestrial particulate matter. In particular, we exploit light scattering theory in the T-matrix formalism to calculate radiation pressure and optical trapping properties of a variety of complex particles of astrophysical interest. Our results open perspectives in the investigation of extraterrestrial particles on our planet, in controlled laboratory experiments, aiming for space tweezers applications: optical tweezers used to trap and characterize dust particles in space or on planetary bodies surface.
Highlights
[2,3,4] that led him to the Nobel prize in Physics 2018, key applications of this contactless manipulation technique have been developed in a wide range of fields: from biology, soft matter, and ultra-sensitive spectroscopy to atomic physics, nanoscience, photonics, spectroscopy, and aerosols science [5]
We focus on the systematic characterization of optical trapping forces in optical tweezers, i.e., a single Gaussian beam focused by a high-numerical aperture (NA) objective
After a review on the role of interstellar, interplanetary, and planetary dust in the universe, we presented a computational study the solar radiation force and optical trapping properties for different cosmic dust particles
Summary
[2,3,4] that led him to the Nobel prize in Physics 2018, key applications of this contactless manipulation technique have been developed in a wide range of fields: from biology, soft matter, and ultra-sensitive spectroscopy to atomic physics, nanoscience, photonics, spectroscopy, and aerosols science [5]. In the limiting cases of particles much smaller or much larger than the laser wavelength, optical forces in optical tweezers can be divided in two components [5]: a gradient force, proportional to the intensity gradient of the laser spot, responsible for trapping, and a scattering force, proportional to the light intensity that tends to push particles away from the laser focus destabilizing single-beam trapping of particles with large extinction Such detrimental effects can be suppressed through the use of two counter-propagating beams to null the opposite scattering forces [13]. These dual-beam traps are based on the use of low numerical aperture (NA) lenses and allow the trapping of particles with reduced incident power in a focal region that is wider than for standard optical tweezers [10]. We consider and compare results of calculations for optical trapping of dust particles in standard optical tweezers in water (typical laboratory conditions) with those calculated for OT in air or in space
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