Multimode optical fiber-graded index (GRIN) lens couples are modeled with the use of an algorithm which quantitatively traces light paths through the optical elements. The effects of the variation of optical fiber core size, GRIN lens length (pitch), fiber-optic/GRIN lens separation, and wavelength are quantitatively demonstrated, Chromatic effects specific to Selfoc™ GRIN lens couples are evaluated for the near-UV to near-infrared spectral region. In general, GRIN lens couples are found to be superior to equivalent ball lens couples for spectroscopic applications. A simple example application of the multimode fiber-optic/GRIN lens couple in remote chemical spectroscopy is presented.
David A. Landis and Carl J. Seliskar, "Fiber-Optic/GRIN Lens Couples for Use in Chemical Spectroscopy," Appl. Spectrosc. 49, 547-555 (1995)