Method for testing specimens

Claim 1

A method for non-destructive testing of fiber optical waveguides as to their tensile properties, said method comprising the steps of providing a specimen selected from a fiber optical waveguide and a preform from which a fiber optical waveguide is drawn; creating a spatial frequency spectrum of the specimen; filtering the spectrum to remove selected relatively stronger-appearing diffraction maximums of the spatial frequency spectrum by projecting the spectrum of the specimens onto a spatial frequency filter; and evaluating the component of the spectrum passing through the filter.

Claim 2

A method for non-destructive testing of fiber optical waveguides as to their tensile properties, said method comprising the steps of providing a specimen selected from a fiber optical waveguide and a preform from which a fiber optical waveguide is drawn; creating a spatial frequency spectrum of the specimen; filtering the spectrum to remove selected relatively stronger-appearing diffraction maximums of the spatial frequency spectrum by projecting the spectrum of the specimens onto a spatial frequency filter; and evaluating the component of the spectrum passing through the filter.

Claim 14

A device for non-destructive testing of a fiber optical waveguide as to its tensile properties by a method of drawing a fiber optical waveguide from a preform, creating a spatial frequency spectrum of a portion of the waveguide, filtering the spectrum by projecting it onto a spatial frequency filter and evaluating a component of the spectrum passing through said filter, said device comprising means for producing a beam of coherent light and projecting it onto a fiber optical waveguide being drawn from a preform; a transformation lens being disposed on a beam axis of said beam of light in a position to receive the light passing through said waveguide, said transformation lens having a focal plane; a spatial frequency filter being disposed in said focal plane and means for evaluating components of said frequency spectrum passing through said filter.

Claim 15

A device for non-destructive testing of a fiber optical waveguide as to its tensile properties by a method of drawing a fiber optical waveguide from a preform, creating a spatial frequency spectrum of a portion of the waveguide, filtering the spectrum by projecting it onto a spatial frequency filter and evaluating a component of the spectrum passing through said filter, said device comprising means for producing a beam of coherent light and projecting it onto a fiber optical waveguide being drawn from a preform; a transformation lens being disposed on a beam axis of said beam of light in a position to receive the light passing through said waveguide, said transformation lens having a focal plane; a spatial frequency filter being disposed in said focal plane and means for evaluating components of said frequency spectrum passing through said filter.

Claim 16

A method for non-destructive testing of a fiber optical waveguide as to its tensile properties, said method comprising the steps of drawing an optical fiber waveguide from a preform, creating a spatial frequency spectrum of the waveguide; filtering the spectrum by providing a filter with a spatial frequency spectrum which consists of a simple structure that will partially block out selected relatively strong appearing diffraction maximums of the spectrum and by projecting the spectrum of the waveguide onto said spatial frequency filter and then evaluating the components of the spectrum passing through the filter.

Claim 17

A method for non-destructive testing of a fiber optical waveguide as to its tensile properties, said method comprising the steps of drawing an optical fiber waveguide from a preform, creating a spatial frequency spectrum of the waveguide; filtering the spectrum by providing a filter with a spatial frequency spectrum which consists of a simple structure that will partially block out selected relatively strong appearing diffraction maximums of the spectrum and by projecting the spectrum of the waveguide onto said spatial frequency filter and then evaluating the components of the spectrum passing through the filter.