Optical tweezers can trap micron-sized objects such as cells, bacteria, and microspheres, and has become an important instrument for measuring forces associated with various physical and biological phenomena. In this thesis work, I constructed an optical tweezers instrument to trap 2µm diameter beads using a HeNe-laser operating with a wavelength of 632.8nm. Trapped beads were imaged using a charge-coupled device (CCD) camera. Since quantitative use of optical tweezers relies on the precise calibration of the trapping stiffness, I used a position sensitive detector (PSD) to measure the Brownian motion of trapped beads. The lateral stiffness of the optical tweezers was evaluated by fitting a Lorentzian to the power spectrum of the Brownian motion of the trapped 2µm beads, which were found to be 6.4(2)pN/µm in the x-direction and 6.0(1)pN/µm in the y-direction. Thus, I realized an optical tweezers setup that could trap and measure the position of micron-sided particles and I developed algorithms to calibrate the stiffness of the trap.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:umu-200963 |
| Date | January 2022 |
| Creators | Yang, Haoxiang |
| Publisher | Umeå universitet, Institutionen för fysik |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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