公开(公告)号：IT8567966D0

公开(公告)日：1985-11-15

申请号：IT6796685

申请日：1985-11-15

Applicant: CSELT CENTRO STUDI LAB TELECOM

Inventor： CAPONI RENATO ,  COPPA GIANNI ,  DI VITA PIETRO

IPC: G01M11/02 ,  G01M11/00 ,  G02B6/00 ,  G02B

Abstract: The method of measuring mode field radius in single-mode optical fibres comprises the modulation of an optical beam by means of a spatial filter with radial-distribution of transmittivity of Gaussian type. Modulated beam intensity is measured in correspondence with the beam axis for different widths of the Gaussian curve, and the mode field radius is derived from both such intensity values and a parameter dependant on the Gaussian width. The apparatus which implements the method is also provided.

公开(公告)号：CA1193880A

公开(公告)日：1985-09-24

申请号：CA429684

申请日：1983-06-03

Applicant: CSELT CENTRO STUDI LAB TELECOM

Inventor： COPPA GIANNI ,  DI VITA PIETRO ,  POTENZA MARCELLO ,  ROSSI UMBERTO

IPC: G01M11/02 ,  G01N21/41 ,  G02B6/00

Abstract: The apparatus comprises an opaque screen, which is placed between a light source and a fibre or preform whose refractive index profile is to be determined. The screen has an oblique slit which forms a beam illuminating a plane section of the fibre or preform, and an optical system forms a nearfield image of the beam incident on the fibre or preform and a far-field image of the refracted beam, in two perpendicular directions on a photosensitive screen. The image formed on the screen is scanned by the scanning system of a television camera of which the photosensitive screen forms part, and the deflection function and hence the refractive index profile are obtained from the coordinates of the points of maximum brightness by using a computing system.