HIGH PRECISION MEASUREMENT OF REFRACTIVE INDEX PROFILE OF CYLINDRICAL GLASS BODIES

摘要

According to some embodiments a method of measuring the refractive index profile of a consolidated glass body having a cylindrical surface comprises the steps of: (a) forming an image of a slit behind the glass body, (b) optionally pre-scanning the cylindrical surface of the test glass body or a reference glass body and analyzing the data within a fixed window to determine the likely location of the zero-order, un-diffracted beam while ignoring other diffracted beams; (c) optionally adjusting the optical power to improve the intensity of the data within the fixed window in order to improve the analysis; (d) predicting the trajectory of the zero-order beam through the preform based on the sampling location xi (incidence position) of the light impinging on the cylindrical surface and the location at which the zero-order beam impinges on the detector; (e) measuring the cylindrical surface of a glass body while using the estimated location of the zero-order beam and adjusted optical power to set the center of a floating window and the beam power at each measurement point; (e) determining deflection angles of the exiting zero-order beam within the floating window at each sampling location; (e) calculating the refractive index profile of glass body by utilizing a transformation function which determines refractive index at each location based upon the measured deflection angle function of the beam.

主权项

1. A method of measuring the refractive index profile of a consolidated glass body with a cylindrical surface, the method comprising the steps of:
a. scanning the cylindrical surface of the consolidated glass body using an optical beam that emanates from an aperture, such that an image of the aperture is formed downstream from the consolidated glass body, between the consolidated glass body and at least one optical detector, and sampling the cylindrical surface with the optical beam at multiple sampling locations xi; b. detecting locations where zero-order optical beams corresponding to the sampling locations xi impinge on at least one optical detector after passing through the consolidated glass body; c. determining deflection angles of the zero-order beams corresponding to the multiple sampling locations xi; d. calculating the refractive index profile of the consolidated glass body based on the deflection angles of the zero-order optical beams corresponding to the multiple sampling locations.