Abstract

Index nonuniformity in optical glass must be characterized at a resolution exceeding the ratio of the wavelength to the total optical path in the system, if diffraction-limited performance is to be maintained. The physical relationship between index inhomogeneity and local mass density can also be used to infer the mass distribution of precision glass rotators for gyroscopes from knowledge of the index profile. The index distribution in bulk glass is measured by scanning the sample through a closely separated pair of laser beams which are then interfered. Changes in phase between the interfering beams measure the local gradient of the refractive index integrated along the beam path.

© 1991 Optical Society of America