Method of computer digital image processing was utilized to measure non-circularity of single mode fiber. The two end
faces were polished, the faces come into plane, and which are perpendicular to fiber axis. Laser beam was thrown on one
end of the fiber, and an inerratic spot was formed from light beam put out at another end of the fiber. The spot was shot
by a digital camera with 5.1x106 pixels. The image was processed with a computer. The process includes full color
picture being translated into gray one, contrast enhancement, median filtering, and picking-up contour line. The every
different three points on the contour line were taken out to determine one circular radius, average of many radiuses was
calculated, The maximum radius and the minimum radius are picked out to calculate the fiber no-circularity in according
to definition. Visual C++ and Matlab were used to programme. The results of experiment show that measurement
precision is independent of the sampling number, but dependence of gray value, and average standard deviation is about
0.03%.
The characteristics of pulse laser transmitting in atmosphere were analyzed. An experiment setup was introduced to
measure the impacts of fog produced by ultrasonic-nebulizer on time delay characters of the laser pulse transmission in
atmosphere. The experimental results show that the width of laser pulse becomes wider while the laser pulse transmits in
fog. The value of width broadened increases with the enhancement of fog thickness. The value of width broadened is
substantially proportional to the extinction coefficient. The R-square of curve fitting is 0.9777. This relation may be used
to estimate the atmosphere extinction.
A lidar system was constructed to operate in the initiative state as well as passive state, with atmosphere component
inspecting and elements of weather. The lidar system consists of laser transmit system, receiving telescope system,
subsequence optics system, signals detecting and processing system. Tuned output laser from the system made up of
SL-III-10-YAG laser and ND6000 tunable dye laser is employed as probing light beam. Its wavelength takes 270-900
nm. Optical axis of laser transmit system is in parallel with one of receiving telescope system. The telescope is made into
Cassegrainian type, and efficient aperture is 400mm. Dispersion spot of the focus point is about 0.5mm. A spatial
resolution of 3.0m was provided in the lidar system.
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