A miniaturized probe for combined two-photon microscopy and femtosecond laser microsurgery

This thesis presents the design, fabrication, and characterization of a miniaturized two-photon fluorescence microscope system. The system is designed to act as a first step towards the design of a two-photon endoscope system capable of in vivo diagnostic imaging and delivery of high energy femtosecond laser pulses for microsurgery. Optical modeling software (TracePro®) was used to design a compact (10 × 15 × 40 mm³) microscope system where field of view (FOV), resolution, and collection efficiency were identified as the key areas of performance. The resulting design utilizes two-axis gimbaled micromechanical system (MEMS) scanning mirror for laser scanning and aircore photonic crystal fiber for the delivery of femtosecond laser pulses. The system employs a miniaturized relay lens pair to limit aberrations due to pre-objective scanning and a separate, large numerical aperture fiber to enhance collection efficiency. The maximum FOV, lateral and axial resolution were measured to be 310 [Greek small letter mu]m and 1.64 [Greek small letter mu]m and 16.4 [Greek small letter mu]m, respectively. The two-photon imaging capabilities of this miniaturized probe were demonstrated using fluorescent beads and pollen grains.