Optical Micro-manipulation Technology And Its Applications

Optical micro-manipulation is a new type of technology for micro-control, micro-fabrication and micro-measurement, which combines the capabilities of optical tweezers, femtosecond laser scissors and micro-spectrometer. Since it was invented in 1970's, optical micro-manipulation technology has been used in various research fields such as biomedicine, material chemistry and nano-technology. In this dissertation, experimental and theoretical studies on optical micro-manipulation techniques are presented.(1). A set of multi-purpose optical micro-manipulation apparatus was established. Optical trapping and moving of yeast cells, blood red cells, chloroplasts, PMMA particles and SiO₂ particles were realized and demonstrated. The maximal transverse trapping forces of particles were measured by the viscous drag force calibration method. By using computer-controlled beam steering mirror, time-divided scanning optical trapping was realized. Nine yeast cells were trapped simultaneously. The mechanism of optically driven rotation of micro-particles by orbital angular momentum and spin angular momentum of light as well as specially shaped particles was analyzed. Optical rotation of a calcium carbonate particle was demonstrated by transferring the spin angular momentum of a circularly polarized laser beam to the particle. The maximal rotation speed of the calcium carbonate particle reached 12rps.(2). Femtosecond laser scissor incorporated with optical tweezers was implemented, in which the optical tweezers traps the target particle and the femtosecond laser scissor makes micro-fabrication on the particle. Simulated micro-surgery on a PMMA particle was demonstrated with the femtosecond laser scissor. The femtosecond laser assisted transfection of propidium iodide (PI) fluorescein into living cells was realized. The femtosecond laser induced production of F-state in a biological material, BR film, was found. Micro-patterns with two-photon absorption of femtosecond laser were recorded in an organic photochromic material, fulgide film. (3). A dark-field microscopic technique by using an axicon was invented, which has the advantages of high light transmittance and ease of switchover between dark-field and bright-field illumination. Combined with the micro-spectrometer, the system can take absorbance, scattering and fluorescence spectra of micron-sized samples while simultaneously viewing the sample.(4). A method for producing 2D and 3D optical lattice with multi-beam interference by using pyramid lens and top-chopped pyramid lens was proposed. The structures of 2D and 3D optical lattice formed by interference of multiple z-axis symmetrically distributed plane waves were numerically simulated and analyzed. Femtosecond lasers were used to generate the 2D and 3D optical lattice by illuminating the pyramid lens and top-chopped pyramid lens. Plastic polarizer sheets were used to record the patterns of the optical lattice, and fraunhofer diffraction tests with the recorded structures were performed. The experimental results were consistent with the numerical simulations very well.