NEW ACCESSORY FOR CHARACTERIZING OPTICAL FIBERS WITH AN FT-IR SPECTROMETER

An accessory has been designed for FT-IR spectroscopy that can be used to measure the optical properties of fiber-optic cables or serve as a n interface for remote sensing probes that use fiber optics. This acce ssory utilizes compound parabolic concentrators (CPCs) to focus the en ergy from the spectrometer into the optical fiber and to also refocus the energy returning to the spectrometer onto the detector. The design was optimized for the high acceptance angle of chalcogenide mid-IR fi bers. However, the use of nonimaging concentrators yields an all-refle cting system that can be used to characterize fibers with different sp ectral transmission ranges. This accessory has been used to investigat e the spectral response, cladding effects, and impurities in various o ptical fibers.