Date of Award
Bachelor of Science
Physics and Astronomy
tweezers, optics, particle, light, laser
We constructed an optical tweezers apparatus, used it to trap transparent micron-sized particles, and moved those particles within a sample by moving the sample relative to the focal point of the trapping beam. The optical trap was based on the fact that focused coherent light creates forces on dielectric objects that point towards the focal point. The magnitude and the span of the force are dependent on the size of the focal point of the beam - generally around 1µm - and the intensity of light. We used an 808 nm 200 mW laser and a piezoelectric stage to trap 1µm plastic beads and move them in 3D. Using a LabView program, we were able to move the stage at precise speeds and thus determine the forces within the focal point of the beam for different powers of the laser. We measured forces as large as 0.5 pN for a laser beam power of 80 mW.
Aprelev, Pavel, "Design and Construction of an Optical Tweezers" (2013). Honors Theses and Student Projects. 631.