Accurate calibration of optical tweezers close to a glass surface using interference rings in backscattered light - Institut d'Optique Graduate School Access content directly
Journal Articles Journal of the European Optical Society : Rapid publications Year : 2023

Accurate calibration of optical tweezers close to a glass surface using interference rings in backscattered light

Abstract

Mechanical forces play an important role in the behaviour of cells, from differentiation to migration and the development of diseases. Optical tweezers provide a quantitative tool to study these forces and must be combined with other tools, such as phase contrast and fluorescence microscopy. Detecting the retro-reflected trap beam is a convenient way to monitor the force applied by optical tweezers, while freeing top access to the sample. Accurate in situ calibration is required especially for single cells close to a surface where viscosity varies rapidly with height. Here, we take advantage of the well contrasted interference rings in the back focal plane of the objective to find the height of a trapped bead above a cover slip. We thus map the viscous drag dependence close to the surface and find agreement between four different measurement techniques for the trap stiffness down to 2 lm above the surface. Combining this detection scheme with phase contrast microscopy, we show that the phase ring in the back focal plane of the objective must be deported in a conjugate plane on the imaging path. This simplifies implementation of optical tweezers in combination with other techniques for biomechanical studies.
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Dates and versions

hal-04107235 , version 1 (02-06-2023)

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Flavie Gillant, Julien Moreau, Maximilian U Richly, Antigoni Alexandrou, Karen Perronet, et al.. Accurate calibration of optical tweezers close to a glass surface using interference rings in backscattered light. Journal of the European Optical Society : Rapid publications, 2023, 19, ⟨10.1051/jeos/2023026⟩. ⟨hal-04107235⟩
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