dorsal/arxiv
View SchemaCalculation and optical measurement of laser trapping forces on non-spherical particles
| Authors | T. A. Nieminen, H. Rubinsztein-Dunlop, N. R. Heckenberg |
|---|---|
| Categories | |
| ArXiv ID | physics/0308110 |
| URL | https://arxiv.org/abs/physics/0308110 |
| DOI | 10.1016/S0022-4073(01)00034-6 |
| Journal | Journal of Quantitative Spectroscopy and Radiative Transfer 70, 627-637 (2001) |
Abstract
Optical trapping, where microscopic particles are trapped and manipulated by light is a powerful and widespread technique, with the single-beam gradient trap (also known as optical tweezers) in use for a large number of biological and other applications. The forces and torques acting on a trapped particle result from the transfer of momentum and angular momentum from the trapping beam to the particle. Despite the apparent simplicity of a laser trap, with a single particle in a single beam, exact calculation of the optical forces and torques acting on particles is difficult. Calculations can be performed using approximate methods, but are only applicable within their ranges of validity, such as for particles much larger than, or much smaller than, the trapping wavelength, and for spherical isotropic particles. This leaves unfortunate gaps, since wavelength-scale particles are of great practical interest because they are readily and strongly trapped and are used to probe interesting microscopic and macroscopic phenomena, and non-spherical or anisotropic particles, biological, crystalline, or other, due to their frequent occurance in nature, and the possibility of rotating such objects or controlling or sensing their orientation. The systematic application of electromagnetic scattering theory can provide a general theory of laser trapping, and render results missing from existing theory. We present here calculations of force and torque on a trapped particle obtained from this theory and discuss the possible applications, including the optical measurement of the force and torque.
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"abstract": "Optical trapping, where microscopic particles are trapped and manipulated by\nlight is a powerful and widespread technique, with the single-beam gradient\ntrap (also known as optical tweezers) in use for a large number of biological\nand other applications.\n The forces and torques acting on a trapped particle result from the transfer\nof momentum and angular momentum from the trapping beam to the particle.\n Despite the apparent simplicity of a laser trap, with a single particle in a\nsingle beam, exact calculation of the optical forces and torques acting on\nparticles is difficult. Calculations can be performed using approximate\nmethods, but are only applicable within their ranges of validity, such as for\nparticles much larger than, or much smaller than, the trapping wavelength, and\nfor spherical isotropic particles.\n This leaves unfortunate gaps, since wavelength-scale particles are of great\npractical interest because they are readily and strongly trapped and are used\nto probe interesting microscopic and macroscopic phenomena, and non-spherical\nor anisotropic particles, biological, crystalline, or other, due to their\nfrequent occurance in nature, and the possibility of rotating such objects or\ncontrolling or sensing their orientation.\n The systematic application of electromagnetic scattering theory can provide a\ngeneral theory of laser trapping, and render results missing from existing\ntheory. We present here calculations of force and torque on a trapped particle\nobtained from this theory and discuss the possible applications, including the\noptical measurement of the force and torque.",
"arxiv_id": "physics/0308110",
"authors": [
"T. A. Nieminen",
"H. Rubinsztein-Dunlop",
"N. R. Heckenberg"
],
"categories": [
"physics.optics"
],
"doi": "10.1016/S0022-4073(01)00034-6",
"journal_ref": "Journal of Quantitative Spectroscopy and Radiative Transfer 70,\n 627-637 (2001)",
"title": "Calculation and optical measurement of laser trapping forces on non-spherical particles",
"url": "https://arxiv.org/abs/physics/0308110"
},
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