Abstract: A monochromatic light beam scans a silica reference and a translucent body, both submerged in index matching fluid and the deflection angle of the beam is measured as it exits the reference, the translucent body and the fluid. This deflection angle of the light beam exiting the reference is compared with the undeflected beam passing through only the fluid. The difference, if any, is used to offset the measurements of the deflection angles of the light beam exiting the translucent body to correct them so that the profile is referenced to the index of silica.

Abstract: A method for automatically determining the refractive index profile of a lightguide preform.

Abstract: Nondestructive analysis of a porous, inhomogeneous, generally cylindrical object, such as a soot boule (12), comprised of n known components, where n is an integer, is achieved by scanning the boule with a beam (18) comprised of photons, each having a distinct energy within one n-1 energy groups. The intensity of the photons within each of the n-1 energy groups leaving the boule is detected by a detector (22) and is measured by a pulse height/scaler analyzer (30) at each of a plurality of separate heights t.sub.i of the beam (18) as measured from the center of the boule. A computer (31) determines each of n-1 attenuation coefficients .mu..sub.1 (r), .mu..sub.2 (r), . . . .mu..sub.n (r), representing the attenuation of the intensity of the photons in each of the n-1 energy groups, respectively, at each height t.sub.i of the beam in accordance with the output data furnished by the scaler/analyzer. From the n-1 attenuation coefficients, the computer (31) determines the density .rho.