Provided herein are measurement systems including a micrometer assembly for receiving a length of tubing, the micrometer assembly including a plurality of non-contact optical micrometers disposed around the length of tubing for measuring an outer diameter (OD) at a first plurality of positions along a circumference of the length of tubing. The measurement system may further include a displacement gauge assembly for receiving the length of tubing from the optical micrometer assembly, the displacement gauge assembly including a plurality of non-contact gauges disposed around the length of tubing for measuring a wall thickness at a second plurality of positions along the circumference of the length of tubing. A controller receives the OD measurements and thickness measurements, and determines an inner diameter and a concentricity of the length of glass tubing based on an index of refraction of the length of glass tubing, the OD measurements, and the thickness measurements.

Provided herein are measurement systems including a micrometer assembly for receiving a length of tubing, the micrometer assembly including a plurality of non-contact optical micrometers disposed around the length of tubing for measuring an outer diameter (OD) at a first plurality of positions along a circumference of the length of tubing. The measurement system may further include a displacement gauge assembly for receiving the length of tubing from the optical micrometer assembly, the displacement gauge assembly including a plurality of non-contact gauges disposed around the length of tubing for measuring a wall thickness at a second plurality of positions along the circumference of the length of tubing. A controller receives the OD measurements and thickness measurements, and determines an inner diameter and a concentricity of the length of glass tubing based on an index of refraction of the length of glass tubing, the OD measurements, and the thickness measurements.

Methods for producing glass articles from glass tube includes securing a glass tube in a holder of a converter; rotating the glass tube; and passing the glass tube through processing stations, which include at least a heating station and a forming station, to form one or more features at a working end of the glass tube. An active time is an amount of time the glass tube is engaged with a heating element or a forming tool while in a processing station, and an exposure index for the processing station is the rotational speed of the glass tube multiplied by a number of heating elements or forming tools in the processing station multiplied by the active time. An absolute difference between the exposure index and a nearest integer is less than or equal to 0.30, which reduces temperature and dimensional inhomogeneity around a circumference of the glass tube.

Methods for producing glass articles from glass tube includes securing a glass tube in a holder of a converter; rotating the glass tube; and passing the glass tube through processing stations, which include at least a heating station and a forming station, to form one or more features at a working end of the glass tube. An active time is an amount of time the glass tube is engaged with a heating element or a forming tool while in a processing station, and an exposure index for the processing station is the rotational speed of the glass tube multiplied by a number of heating elements or forming tools in the processing station multiplied by the active time. An absolute difference between the exposure index and a nearest integer is less than or equal to 0.30, which reduces temperature and dimensional inhomogeneity around a circumference of the glass tube.

A process for preparing a glass container that includes: providing a glass tube with a first portion, a second portion, and a longitudinal axis (L.sub.tube); holding the first portion in a first clamping chuck and the second portion in a second clamping chuck; rotating the glass tube around the longitudinal axis (L.sub.tube); heating, via a heater, the glass tube above a glass transition temperature; separating the first and second portions from one another by pulling apart along the longitudinal axis (L.sub.tube) while the heated glass tube is still rotating by moving the first and the second chucks away from each other; and moving the heater, while moving the first and second chucks away from each other, so that the heater follows a mass that remains at a circular end region of the first and/or second portion.

A process for preparing a glass container that includes: providing a glass tube with a first portion, a second portion, and a longitudinal axis (L.sub.tube); holding the first portion in a first clamping chuck and the second portion in a second clamping chuck; rotating the glass tube around the longitudinal axis (L.sub.tube); heating, via a heater, the glass tube above a glass transition temperature; separating the first and second portions from one another by pulling apart along the longitudinal axis (L.sub.tube) while the heated glass tube is still rotating by moving the first and the second chucks away from each other; and moving the heater, while moving the first and second chucks away from each other, so that the heater follows a mass that remains at a circular end region of the first and/or second portion.

A method for forming a hollow cylinder, in a single step, into a quartz glass tube with a large outer diameter and high dimensional stability is provided. To produce the tube, the cylinder, while rotating, is softened in portions in a heating zone which is moved at a relative feed rate Va and the softened portion is radially expanded by a centrifugal force and/or internal overpressure applied in the hollow cylinder bore so as to form a deformation zone. The radial expansion of the softened portion is carried out at a location-dependent radial expansion rate Vr, the profile of which along the deformation zone has a maximum value Vr,max which is smaller than 20 cm/min. The temperature in a rear heating portion of the heating zone, assigned to the end of the deformation zone, is lower than in a front heating portion assigned to the beginning of the deformation zone.

A method for forming a hollow cylinder, in a single step, into a quartz glass tube with a large outer diameter and high dimensional stability is provided. To produce the tube, the cylinder, while rotating, is softened in portions in a heating zone which is moved at a relative feed rate Va and the softened portion is radially expanded by a centrifugal force and/or internal overpressure applied in the hollow cylinder bore so as to form a deformation zone. The radial expansion of the softened portion is carried out at a location-dependent radial expansion rate Vr, the profile of which along the deformation zone has a maximum value Vr,max which is smaller than 20 cm/min. The temperature in a rear heating portion of the heating zone, assigned to the end of the deformation zone, is lower than in a front heating portion assigned to the beginning of the deformation zone.

Provided herein are measurement systems including a micrometer assembly for receiving a length of tubing, the micrometer assembly including a plurality of non-contact optical micrometers disposed around the length of tubing for measuring an outer diameter (OD) at a first plurality of positions along a circumference of the length of tubing. The measurement system may further include a displacement gauge assembly for receiving the length of tubing from the optical micrometer assembly, the displacement gauge assembly including a plurality of non-contact gauges disposed around the length of tubing for measuring a wall thickness at a second plurality of positions along the circumference of the length of tubing. A controller receives the OD measurements and thickness measurements, and determines an inner diameter and a concentricity of the length of glass tubing based on an index of refraction of the length of glass tubing, the OD measurements, and the thickness measurements.

Provided herein are measurement systems including a micrometer assembly for receiving a length of tubing, the micrometer assembly including a plurality of non-contact optical micrometers disposed around the length of tubing for measuring an outer diameter (OD) at a first plurality of positions along a circumference of the length of tubing. The measurement system may further include a displacement gauge assembly for receiving the length of tubing from the optical micrometer assembly, the displacement gauge assembly including a plurality of non-contact gauges disposed around the length of tubing for measuring a wall thickness at a second plurality of positions along the circumference of the length of tubing. A controller receives the OD measurements and thickness measurements, and determines an inner diameter and a concentricity of the length of glass tubing based on an index of refraction of the length of glass tubing, the OD measurements, and the thickness measurements.