Patent ID: 6366348
Filing Date: 2002-04-02
Classification: G01M

Abstract:
An optical fiber distortion measuring apparatus comprising:a first measuring device for measuring the difference in level between back scatter light from an undistorted optical fiber and back scatter light from a distorted optical fiber; a second measuring device for directing a light signal having a first light frequency into the undistorted optical fiber and for obtaining an initial time change waveform indicating the intensity of back scatter light generated at each position in the undistorted optical fiber; a third measuring device for directing a light signal having a first light frequency into the distorted optical fiber and for obtaining a first time change waveform indicating the light intensity of the back scatter light generated at each position in the distorted optical fiber; a comparing device for comparing the first time change waveform and the initial time change waveform and for detecting a detection point at which the light intensities differ from one another; a fourth measuring device for directing a light signal having a second light frequency into the distorted optical fiber and obtaining a second time change waveform; a correction device for correcting a first light intensity, which is a light intensity at the detection point in the first time change waveform, on the basis of the difference in level, and for correcting a second light intensity, which is a light intensity at the detection point in the second time change waveform, on the basis of the difference in level; a curve calculating device for calculating, with respect to a spectrum waveform showing the relationship between the light frequency of the incident light and the intensity of the back scatter light generated at the detection points, a curve resulting from a parallel movement of a curve approximating the spectrum waveform relating to the undistorted optical fiber, which curve satisfies the relationships between the first light frequency and first light intensity after correction, and satisfies the relationship between the second light frequency and second light intensity after correction; a peak frequency calculating device for calculating the light frequency exhibiting a maximal light intensity in the curve obtained by the curve calculating device; and a distortion amount calculating device for calculating an amount of distortion of the optical fiber at the detection point based on the light frequency obtained by the peak frequency calculating device.