Patent ID: 7212280

Claim:
A method for measuring the diameter of an optical fiber and for detecting defects in the fiber, the method comprising: directing a beam of a laser at the fiber, radially, to produce an interference pattern; providing a first sensor receiving said interference pattern in an angle span, with respect to an axis of said laser, through an optical system; providing a first processing board connected to said first sensor for analyzing said interference pattern received by said first sensor; calibrating said first sensor so that each of several points of said first sensor corresponds to a determined value for said angle with respect to said axis of said laser axis; using said processing board for calculating the values for A, B, D and φ so that a theoretical curve of the interference pattern, represented by: M = A B + θ × [ 1 + sin 2 ⁢ { N ⁡ ( D , θ ) × π + φ } ] _ N ⁡ ( D , θ ) = D λ × [ sin ⁢ θ 2 + ( n 2 + 1 - 2 ⁢ n × cos ⁢ θ 2 ) 1 ⁢ / ⁢ 2 ] + 1 4 wherein: M is a signal amplitude, A is a calibration parameter for the signal amplitude, B is a calibration parameter for the angle, φ is a calibration parameter for the phase, N is a number of fringes, θ is a measurement angle with respect to said axis of said laser, D is a fiber diameter, and λ is a laser wavelength, corresponds to said interference pattern received by said first sensor, in order to obtain an absolute measurement of said fiber diameter D.