公开(公告)号：CA1214556A

公开(公告)日：1986-11-25

申请号：CA466723

申请日：1984-10-31

Applicant: CSELT CENTRO STUDI LAB TELECOM

Inventor： COPPA GIANNI ,  DI VITA PIETRO ,  ROSSI UMBERTO

IPC: G01J1/02 ,  G01J1/42 ,  G01J9/00 ,  G01M11/00 ,  G01R29/08 ,  G02B6/10 ,  H04B17/00

Abstract: The value of a transverse moment of any order of the electromagnetic field associated with an optical beam (and in particular the spot size of such a beam) is determined by two successive measurements of the optical power of the beam: one measurement is a direct measurement, whilst the other is effected after spatially modulating the transverse distribution of the electromagnetic field by a factor proportional to the n-th power of the transverse coordinate of the beam, n being the moment order. The moment can be obtained from the ratio between the two measurements. The invention also includes apparatus for carrying out the method.

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.

公开(公告)号：CA1065174A

公开(公告)日：1979-10-30

申请号：CA277054

申请日：1977-04-18

Applicant: CSELT CENTRO STUDI LAB TELECOM

Inventor： DI VITA PIETRO

IPC: G02B6/14 ,  G02B6/32 ,  G02B5/14

Abstract: In an optical equalizer for an optical multimode telecommunications waveguide, the number of optical elements and the number of surfaces at which partial reflection can occur are reduced by using a single refractive body whose refractive index varies according to the distance from its axis so as thus to provide the required equalizing function, i.e. the interchange of axial and maximum transmission angle rays.