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    2.
    发明专利
    未知

    公开(公告)号：IT1180071B

    公开(公告)日：1987-09-23

    申请号：IT6758084

    申请日：1984-06-05

    Applicant: CSELT CENTRO STUDI LAB TELECOM

    Inventor： COPPA GIANNI ,  DI VITA PIETRO

    IPC: G01M11/00 ,  G01M11/02 ,  G01M11/08 ,  H01P

    Abstract: The process is based on the fact that the introduction of perturbations in an optical fibre can generate greater losses on higher order modes. Therefore, a spectral scanning of the fibre output power is effected under a certain number of different perturbation conditions and the values obtained are combined so as to determine the fraction of power guided in the fundamental mode. The cut-off wavelength is that where this fraction exceeds a certain value. The equipment implementing the process is also provided.

    3.
    发明专利
    未知

    公开(公告)号：IT1171039B

    公开(公告)日：1987-06-10

    申请号：IT6817183

    申请日：1983-11-10

    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 ,  G01R

    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, 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 includes also the apparatus for carrying out the method.

    METHOD AND DEVICE FOR MIXING-DEMIXING OPTICAL BEAMS FOR TRANSMISSION ON OPTICAL FIBRES
    6.
    发明专利
    METHOD AND DEVICE FOR MIXING-DEMIXING OPTICAL BEAMS FOR TRANSMISSION ON OPTICAL FIBRES 未知

    公开(公告)号：CA1109307A

    公开(公告)日：1981-09-22

    申请号：CA321113

    申请日：1979-02-08

    Applicant: CSELT CENTRO STUDI LAB TELECOM

    Inventor： DI VITA PIETRO

    IPC: G02B6/293 ,  G02B6/28 ,  G02B6/34 ,  G02B6/42 ,  G02B27/10 ,  G02B27/12

    Abstract: In the transmission of signals on multimode optical fibres, wherein light beams of different wavelengths are collected into a single composite beam to be transmitted, each of the monochromatic light beams is collected into the composite beam by means of a mixing device constructed to minimize optical losses. The mixing device is a transparent body having two components of the same refractive index for the wavelength of the particular monochromatic beam and different refractive indices for the wavelengths of the composite beam, the respective angles of incidence of the beams upon the separation surface of the components of the transparent body being such that the monochromatic beam is transmitted without deflection along a straight line path and the composite beam is totally reflected along said path. Conversely, a composite beam is split into its monochromatic components by one or more such bodies according to the number of components to be separated.

    7.
    发明专利
    未知

    公开(公告)号：IT1199897B

    公开(公告)日：1989-01-05

    申请号：IT6766585

    申请日：1985-07-22

    Applicant: CSELT CENTRO STUDI LAB TELECOM ,  LAB TELECOMUNICAZIONI S P A

    Inventor： CALZAVARA MASSIMO ,  COPPA GIANNI ,  DI VITA PIETRO

    IPC: G02B6/24 ,  G01M11/00 ,  G02B

    Abstract: An optical beam is injected into a single-mode (FO) fibre of a given length and outgoes from an end face of the fibre, is reflected by a reflecting optical system into said fibre; the optical power of the reflected beam guided backward by the fibre is measured. Said end face of the fibre is placed in the optical centre of the reflecting system to obtain the maximum reflected power, and is then deviated from said position detecting the occurring reductions of the reflected optical power.A device and variants to implement the method are also described.

    METHOD OF AND APPARATUS FOR THE MEASUREMENT OF THE REFRACTIVE-INDEX PROFILE IN MONOMODE OPTICAL FIBRES
    8.
    发明专利
    METHOD OF AND APPARATUS FOR THE MEASUREMENT OF THE REFRACTIVE-INDEX PROFILE IN MONOMODE OPTICAL FIBRES 未知

    公开(公告)号：CA1235923A

    公开(公告)日：1988-05-03

    申请号：CA497701

    申请日：1985-12-16

    Applicant: CSELT CENTRO STUDI LAB TELECOM

    Inventor： COPPA GIANNI ,  DI VITA PIETRO

    IPC: G01M11/02 ,  G01M11/00 ,  G01N21/41 ,  G02B6/00 ,  G01N21/84

    Abstract: The present invention provides a method which is of the guided near field type so as to exploit fibre propagation characteristics, and requires no complex processing of a measured value. In this method, an image of the fibre output end is radially scanned, and for each value of a distance r from the image axis, two image-intensity measurements are effected, the first after optically filtering the beam emerging from the fibre so as to modulate the beam according to a factor p4 (with p = a ? sin .THETA., .THETA. being the angular beam coordinate, and a the distance of the generic filter point from the fibre output end), the second meansurement being effected by directly collecting the beam leaving the fibre end, the refractive index value at that point being derived from the ratio between the first and the second measurement.

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