Optical waveguide preform measurement during manufacture

Claim 1

An apparatus for measuring diameter and runout of an optical waveguide preform during manufacture of the preform, wherein successive layers of preform material are deposited on a rotating bait rod to form an outwardly growing preform surface, comprising: at least one distance gauge comprising, a sensing unit electrically connected to a control unit, for measuring distance between said sensing unit and the preform surface, said sensing unit spaced apart from the preform and having a light source, directed at the preform surface and operating within a wavelength range, and a light detector, to receive source light reflected from the preform surface, and said at least one distance gauge providing an electrical signal proportional to the distance between said sensing unit and the preform surface; a housing surrounding and supporting said sensing unit, said housing having an opening, facing the preform surface, to allow passage of the source light from said sensing unit to the preform surface and entrance of light reflected from the preform surface to said sensing unit; a light filter covering the opening of said housing and sealed to said housing, said light filter constructed to transmit a range of light wavelengths substantially coincident with the operating wavelength range of the light source of said sensing unit; an electronic circuit for dividing the electric signal from said distance gauge into an alternating signal portion and a constant signal portion; and, means for translating said alternating signal into a preform runout measurement and said constant signal into a preform diameter measurement.

Claim 2

An apparatus for measuring diameter and runout of an optical waveguide preform during manufacture of the preform, wherein successive layers of preform material are deposited on a rotating bait rod to form an outwardly growing preform surface, comprising: at least one distance gauge comprising, a sensing unit electrically connected to a control unit, for measuring distance between said sensing unit and the preform surface, said sensing unit spaced apart from the preform and having a light source, directed at the preform surface and operating within a wavelength range, and a light detector, to receive source light reflected from the preform surface, and said at least one distance gauge providing an electrical signal proportional to the distance between said sensing unit and the preform surface; a housing surrounding and supporting said sensing unit, said housing having an opening, facing the preform surface, to allow passage of the source light from said sensing unit to the preform surface and entrance of light reflected from the preform surface to said sensing unit; a light filter covering the opening of said housing and sealed to said housing, said light filter constructed to transmit a range of light wavelengths substantially coincident with the operating wavelength range of the light source of said sensing unit; an electronic circuit for dividing the electric signal from said distance gauge into an alternating signal portion and a constant signal portion; and, means for translating said alternating signal into a preform runout measurement and said constant signal into a preform diameter measurement.

Claim 14

A method of measuring diameter and runout of an optical waveguide preform during manufacture of the preform, wherein successive layers of preform material are deposited on a rotating bait rod to form an outwardly growing preform surface, comprising the steps of: providing at least one distance gauge comprising, a sensing unit electrically connected to a control unit, said sensing unit spaced apart from the preform, wherein said distance gauge produces an electric signal proportional to the distance between said sensing unit and the preform surface; dividing said electric signal into an alternating signal portion and a constant signal portion; and recording and translating said alternating signal portion into a measurement of preform runout and said constant signal portion into a measurement of preform diameter.

Claim 15

A method of measuring diameter and runout of an optical waveguide preform during manufacture of the preform, wherein successive layers of preform material are deposited on a rotating bait rod to form an outwardly growing preform surface, comprising the steps of: providing at least one distance gauge comprising, a sensing unit electrically connected to a control unit, said sensing unit spaced apart from the preform, wherein said distance gauge produces an electric signal proportional to the distance between said sensing unit and the preform surface; dividing said electric signal into an alternating signal portion and a constant signal portion; and recording and translating said alternating signal portion into a measurement of preform runout and said constant signal portion into a measurement of preform diameter.

Claim 19

A method for measuring diameter, ellipticity and runout of an optical waveguide preform during manufacture of the preform, wherein successive layers of preform material are deposited on a rotating bait rod to form an outwardly growing preform surface, comprising the steps of: providing two distance gauges each comprising, a sensing unit electrically connected to a control unit, wherein each said distance gauge produces an electric signal proportional to the respective distances between each said sensing unit and the preform surface; positioning said two sensing units spaced apart from the preform surface and at respective fixed distances relative to a reference line, said two sensing units located to face diametrically opposite surfaces of the preform; translating said respective electric signals into a measurement of the respective distances of each said sensing unit from the preform surface; translating said respective distance measurements into a preform thickness measurement; recording successive thickness measurements, made over a time period equal to or greater than the time required for the preform to make one revolution, the time interval between measurements being less than the time required for the preform to make one revolution; dividing each said respective electric signal into an alternating signal portion and a constant signal portion; and recording and translating each said alternating signal portion into a measurement of preform runout and each said constant signal portion into a measurement of preform diameter.

Claim 20

A method for measuring diameter, ellipticity and runout of an optical waveguide preform during manufacture of the preform, wherein successive layers of preform material are deposited on a rotating bait rod to form an outwardly growing preform surface, comprising the steps of: providing two distance gauges each comprising, a sensing unit electrically connected to a control unit, wherein each said distance gauge produces an electric signal proportional to the respective distances between each said sensing unit and the preform surface; positioning said two sensing units spaced apart from the preform surface and at respective fixed distances relative to a reference line, said two sensing units located to face diametrically opposite surfaces of the preform; translating said respective electric signals into a measurement of the respective distances of each said sensing unit from the preform surface; translating said respective distance measurements into a preform thickness measurement; recording successive thickness measurements, made over a time period equal to or greater than the time required for the preform to make one revolution, the time interval between measurements being less than the time required for the preform to make one revolution; dividing each said respective electric signal into an alternating signal portion and a constant signal portion; and recording and translating each said alternating signal portion into a measurement of preform runout and each said constant signal portion into a measurement of preform diameter.

Claim 25

A method for mapping the shape of an optical waveguide preform during manufacture of the preform comprising the steps of: providing a rotating bait rod, wherein successive layers of preform material are deposited on the rotating bait rod to form an outwardly growing preform surface; providing two distance gauges each comprising, a sensing unit electrically connected to a control unit, wherein each said distance gauge produces an electric signal proportional to the respective distances between each said sensing unit and the preform surface; positioning said two sensing units spaced apart from the preform surface and at respective fixed distances relative to a reference line, said two sensing units essentially centered on the preform and located to face diametrically opposite surfaces of the preform; translating said respective electric signals into a measurement of the respective distances of each said sensing unit from the preform surface; translating said respective distance measurements into a preform thickness measurement; recording successive thickness measurements, made over a time period equal to or greater than the time required for the preform to make one revolution, wherein the time interval between said successive measurements is less than or equal to the time required for the preform to make 0.25 revolutions; and, moving said two sensing units in unison parallel to the axis of rotation of the preform.

Claim 26

A method for mapping the shape of an optical waveguide preform during manufacture of the preform comprising the steps of: providing a rotating bait rod, wherein successive layers of preform material are deposited on the rotating bait rod to form an outwardly growing preform surface; providing two distance gauges each comprising, a sensing unit electrically connected to a control unit, wherein each said distance gauge produces an electric signal proportional to the respective distances between each said sensing unit and the preform surface; positioning said two sensing units spaced apart from the preform surface and at respective fixed distances relative to a reference line, said two sensing units essentially centered on the preform and located to face diametrically opposite surfaces of the preform; translating said respective electric signals into a measurement of the respective distances of each said sensing unit from the preform surface; translating said respective distance measurements into a preform thickness measurement; recording successive thickness measurements, made over a time period equal to or greater than the time required for the preform to make one revolution, wherein the time interval between said successive measurements is less than or equal to the time required for the preform to make 0.25 revolutions; and, moving said two sensing units in unison parallel to the axis of rotation of the preform.