| 摘要 |
A narrow laser beam (16) scans a clad optical fiber preform (10) with a narrow, parallel scanning beam of coherent light and the deflection angle ( theta ) thereof measured as the beam exits the preform. The deflection angles ( theta ) of the scanning beam (16) are measured and compared to theoretical or empirically developed deflection angle scans of preforms having known parameters to determine the parameters of the preform. The deflection angle ( theta ) is plotted versus the incident beam position (d) and that plot is integrated to provide a curve (47) that is compared to theoretically developed plots having known parameters to determine parameters of the fiber preform such as refractive index gradient power, gamma , and the refractive index ratio, DELTA .
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