This study reports an application of a fiber-optic LED-based illumination system to solve an inverse problem in optical measurements of characteristics of a single-mode fiber. The illumination system has the advantages of low temporal coherence, high intensity, collimation, and thermal stability of the emission spectrum. The inverse analysis is investigated to predict the values of the diameter and refractive index of a single-mode fiber and applies to the far field scattering pattern in the vicinity of a polychromatic rainbow. As the inversion possibility depends considerably on the properties of the incident radiation, a detailed discussion is provided on both the specification of the illumination system as well as preliminary characteristics of the produced radiation. The illumination system uses a direct coupling between a thermally-stabilized LED junction and a plastic optical fiber, which transmits light to an optical collimator. A numerical study of fiber-to-LED coupling efficiency helps to understand the influence of lateral and longitudinal misalignments on the output power.

Date Published: 26 June 2017
PDF: 10 pages
Proc. SPIE 10330, Modeling Aspects in Optical Metrology VI, 1033019 (26 June 2017); doi: 10.1117/12.2269795

Published in SPIE Proceedings Vol. 10330:
Modeling Aspects in Optical Metrology VI
Bernd Bodermann; Karsten Frenner; Richard M. Silver, Editor(s)