Adaptive optics in an optical trapping system for enhanced lateral trap stiffness at depth

Caroline Müllenbroich, Niall McAlinden, Amanda Wright

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

In optical trapping systems the trap stiffness, or spring constant, deteriorates dramatically with trap depth due to optical aberrations and system misalignment. This can severely hamper studies that employ optical tweezers to make accurate quantitative measurements. Here, a deformable membrane mirror is used, in conjunction with a random search algorithm, to correct for these aberrations by optimizing on a merit factor that is directly proportional to the trap stiffness. Previous studies have sought to address this issue but none have used a merit factor that is directly proportional to the trap stiffness. We demonstrate that the lateral trap stiffness, measured with and without aberration correction at increasing depths, improves throughout the trapping range of a conventional trap and allows us to extend the maximum depth at which we can trap from 136 to 166 μm. At a depth of 131 μm, trap stiffness improved by factors of 4.37 and 3.31 for the x- and y-axes respectively. The aberration correction resulted in deformable membrane mirror shapes where a single shape could be applied throughout a wide range of trap depths, showing significant improvement, and had the added benefit of making the lateral trapping forces more uniform in x and y.
LanguageEnglish
Article number075305
Number of pages8
JournalJournal of Optics
Volume15
Issue number7
DOIs
Publication statusPublished - 2 Jul 2013

Fingerprint

Adaptive optics
adaptive optics
stiffness
Aberrations
trapping
Stiffness
traps
aberration
Mirrors
Membranes
Optical tweezers
Optical systems
mirrors
membranes
misalignment

Keywords

  • optical trapping
  • adaptive optics
  • trap stiffness
  • optical tweezers

Cite this

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Adaptive optics in an optical trapping system for enhanced lateral trap stiffness at depth. / Müllenbroich, Caroline; McAlinden, Niall; Wright, Amanda.

In: Journal of Optics, Vol. 15, No. 7, 075305, 02.07.2013.

Research output: Contribution to journalArticle

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AU - Müllenbroich, Caroline

AU - McAlinden, Niall

AU - Wright, Amanda

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AB - In optical trapping systems the trap stiffness, or spring constant, deteriorates dramatically with trap depth due to optical aberrations and system misalignment. This can severely hamper studies that employ optical tweezers to make accurate quantitative measurements. Here, a deformable membrane mirror is used, in conjunction with a random search algorithm, to correct for these aberrations by optimizing on a merit factor that is directly proportional to the trap stiffness. Previous studies have sought to address this issue but none have used a merit factor that is directly proportional to the trap stiffness. We demonstrate that the lateral trap stiffness, measured with and without aberration correction at increasing depths, improves throughout the trapping range of a conventional trap and allows us to extend the maximum depth at which we can trap from 136 to 166 μm. At a depth of 131 μm, trap stiffness improved by factors of 4.37 and 3.31 for the x- and y-axes respectively. The aberration correction resulted in deformable membrane mirror shapes where a single shape could be applied throughout a wide range of trap depths, showing significant improvement, and had the added benefit of making the lateral trapping forces more uniform in x and y.

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