dorsal/arxiv
View SchemaOrientation of optically trapped nonspherical birefringent particles
| Authors | Wolfgang Singer, Timo A. Nieminen, Ursula J. Gibson, Norman R. Heckenberg, Halina Rubinsztein-Dunlop |
|---|---|
| Categories | |
| ArXiv ID | physics/0602156 |
| URL | https://arxiv.org/abs/physics/0602156 |
| DOI | 10.1103/PhysRevE.73.021911 |
| Journal | Physical Review E 73(2), 021911 (2006) |
Abstract
While the alignment and rotation of microparticles in optical traps have received increased attention recently, one of the earliest examples has been almost totally neglected the alignment of particles relative to the beam axis, as opposed to about the beam axis. However, since the alignment torques determine how particles align in a trap, they are directly relevant to practical applications. Lysozyme crystals are an ideal model system to study factors determining the orientation of nonspherical birefringent particles in a trap. Both their size and their aspect ratio can be controlled by the growth parameters, and their regular shape makes computational modeling feasible. We show that both external shape and internal birefringence anisotropy contribute to the alignment torque. Three-dimensionally trapped elongated objects either align with their long axis parallel or perpendicular to the beam axis depending on their size. The shape-dependent torque can exceed the torque due to birefringence, and can align negative uniaxial particles with their optic axis parallel to the electric field, allowing an application of optical torque about the beam axis.
{
"annotation_id": "0cef6696-302d-496d-8349-e6b7ec1ce41d",
"date_created": "2026-03-02T18:01:07.273000Z",
"date_modified": "2026-03-02T18:01:07.273000Z",
"file_hash": "e0e4ec652251fc48cd9cfdf992c56648e718c67346922836d741aae56de5c135",
"private": false,
"record": {
"abstract": "While the alignment and rotation of microparticles in optical traps have\nreceived increased attention recently, one of the earliest examples has been\nalmost totally neglected the alignment of particles relative to the beam axis,\nas opposed to about the beam axis. However, since the alignment torques\ndetermine how particles align in a trap, they are directly relevant to\npractical applications. Lysozyme crystals are an ideal model system to study\nfactors determining the orientation of nonspherical birefringent particles in a\ntrap. Both their size and their aspect ratio can be controlled by the growth\nparameters, and their regular shape makes computational modeling feasible. We\nshow that both external shape and internal birefringence anisotropy contribute\nto the alignment torque. Three-dimensionally trapped elongated objects either\nalign with their long axis parallel or perpendicular to the beam axis depending\non their size. The shape-dependent torque can exceed the torque due to\nbirefringence, and can align negative uniaxial particles with their optic axis\nparallel to the electric field, allowing an application of optical torque about\nthe beam axis.",
"arxiv_id": "physics/0602156",
"authors": [
"Wolfgang Singer",
"Timo A. Nieminen",
"Ursula J. Gibson",
"Norman R. Heckenberg",
"Halina Rubinsztein-Dunlop"
],
"categories": [
"physics.optics"
],
"doi": "10.1103/PhysRevE.73.021911",
"journal_ref": "Physical Review E 73(2), 021911 (2006)",
"title": "Orientation of optically trapped nonspherical birefringent particles",
"url": "https://arxiv.org/abs/physics/0602156"
},
"schema_id": "dorsal/arxiv",
"source": {
"execution_id": "7b3d01d2-5f20-4e78-8fa8-bc37f9e67842",
"id": "arXiv Dataset IDs",
"type": "Model",
"variant": "snapshot-2026-03-01",
"version": "0.1.0"
},
"user_id": 1000002
}