Available at: https://digitalcommons.calpoly.edu/theses/2947
Date of Award
12-2024
Degree Name
MS in Electrical Engineering
Department/Program
Electrical Engineering
College
College of Engineering
Advisor
Xiaomin Jin
Advisor Department
Electrical Engineering
Advisor College
College of Engineering
Abstract
Current research has shown that photophoretic optical trapping (POT) is a promising method for creating true three-dimensional holograms. A landmark study by Smalley et. al. at BYU was able to generate a full hologram within a 2 cm edge cube with remarkable success. However, a key drawback to this method is its poor ability to hold trapped particles within the focal point of the laser for an extended period of time. An investigation from our group presented at SPIE Photonics West 2023 sought to improve these results by varying the focal length of the trapping and the wavelength of the laser, called the one-lens control. To further extend trapping times, we take advantage of optical power lost due to scattering by reflecting it back toward the trapping site. We investigate the potential of retro-reflectors as an effective low-cost solution due to their corner- cube micro-structures which prevent interference between reflected and incident light. The reflected light is then re-focused back toward the trapping site using a Keplerian lens configuration. The resulting trapping times with retro-reflectors are measured and compared against two different control setups without reflectors, as well as a mirror setup to quantify the effects of destructive interference. Both the average and median trapping times for the retro-reflector setup showed significant improvement when compared to all three other test setups. While maximum trapping times with the retro-reflectors were comparable to those of the two-lens control setup, the new setup has higher average trapping times and shows great promise for future research. In addition we showed that at high optical laser powers the retro-reflectors showed higher average trapping times compared to the basic setup.