This study concerns the determination of the diameter of an optical fiber by analysis of a 2D measured diffraction pattern relative to this linear object, falling within the scope of the Fraunhofer approximation. In this approach, when considering a small line-shaped aperture, with a radius α, or a diffractive object placed at the y-axis, an amplitude of the in-line Fraunhofer hologram can be achieved by a mathematical expression, for a given wavelength of the illuminating light λ and a distance z between the particle and the recording plane. The interferometric signal depends on an Airy curve expressed by a Sinc function whose determination of the zeros makes it possible to deduce an argument giving the radius of the fiber. The measurement is carried out for an object-CCD distance equal to z = 60 mm, with a wavelength of illumination λ = 635nm. The zeros of the Airy function appearing in the analytic expression of the interferometric signal allows us to achieve the value of the measured diameter. Knowing that the fiber radius is α = 62.5 μm, the measured value is acquired with an error of 1.7%.
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