Interferometric chromatic dispersion measurements of long, gradient-index red lenses in the visible and the near infrared

A new procedure is presented for testing long, radial-gradient-index rod le nses in a phase-stepping Twyman-Green interferometer. In addition, a method for converting the measured optical phase data to the rod's index of refra ction profile is reviewed. This procedure was used to measure refractive-in dex profile dispersions over the wavelength range of 441 to 1064 nm. These measurements provide the first data for refractive-index profiles of rod le nses in the infrared and show the existence of positive dispersion, negativ e dispersion, and near-infrared dispersion reversal in some samples. The di spersion results suggest the need for modifications to the current glass mo del. (C) 1999 Optical Society of America. OCIS codes: 120.3180, 120.3940, 1 20.3930, 110.2760, 260.2030, 160.2750.