RESUMEN
A high power and high quality picosecond laser is crucial in MEMS fabrication regarding micromachines. Optimal seed beam coupling is an important precondition to enhance laser efficiency. However, empirical coupling limits its development. In this paper, the physical parameters related to coupling are determined. The relationships among them are established under optical mode matching constraints to satisfy optimal seed beam coupling. According to a theoretical analysis, the focal length cut-off and the optimal coupling position of the coupling lens are acquired. A maximum transmittance of 87.2% is acquired with a 6 W input seed power in the validation experiment. In further power amplification experiments, a diffraction-limited beam quality is achieved, with M2X = 1.111, M2Y = 1.017, an optical efficiency of 60.5% and a slope efficiency of 66%, benefiting from the previous theoretical guidance.
RESUMEN
For measuring and region-identifying the deep displacement of slopes, a rod-fiber coupling structure based on optical time-domain reflection technology was designed. Accuracy of measurement and region identification in the deep displacement of slopes were studied by calibration experiment and model experiment. A rod-fiber coupling structure was able to calculate the variation and accurately identify the region of deep displacement of a slope compared with the measured downslide displacement of the slope model. The maximum measurement error of the deep displacement of the slope was 10.1%, the identification error of the displacement region was less than 4.4%, and the accuracy of the displacement-region identification of the rod-fiber coupling structure was 3.1 cm. Thus, the rod-fiber coupling structure based on optical time-domain reflection technology can be used for measuring and for region identification in the deep displacement of the slopes, and can provide a new method for the identification of the sliding surfaces of slopes.