Design of an optical trap and calibration of its trap stiffness using the power spectrum method
Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
Optical tweezers are used to trap small particles using the radiation pressure. The aim of this experiment was to design an optical tweezers system and calibrate the stiffness of optical tweezers using the power spectrum method. The experimental setup included a trapping system using He-Ne laser, an oil immersion objective (numerical aperture (NA) =1.3) and optics for beam-expansion, a microscope system for observing the micro-sized particles and a data recording and processing system. In this experiment, the free beads were trapped successfully using the optical optical trap and the stiffness of the trap was calibrated by the power spectrum method. The corner frequency was fc= (17 ± 2) Hz in the x direction and fc= (15 ± 2) Hz in the y direction. The stiffnesses of the trap were κx = (2.3 ± 0.2 pN /μm） in the x direction and κy = (2.0 ± 0.2）pN /μm in the y direction. The errors come from the the radius of the bead and the temperature of the fluid. By ignoring the noise through the power spectrum, a reliable optical trap was achieved.
Place, publisher, year, edition, pages
Atom and Molecular Physics and Optics
IdentifiersURN: urn:nbn:se:umu:diva-122048OAI: oai:DiVA.org:umu-122048DiVA: diva2:936825
Subject / course
Fysik C - Examensarbete