A series of measurements verify that the accuracy, reproducibility, and quality of fiber infrared spectra strongly rely on fiber thickness and morphology, the aperture size and direction, and instrument parameters, despite the use of high resolution in microscopy by using the Continu mu m microscope. The effect of fiber cross section and testing parameters on the characteristics of the FTIR microscope spectra is discussed systematically. Meanwhile, the reproducibility of the spectra has also been tested using the transmission and mapping methods. The experimental results show that the size selection of the aperture, fiber flattening, and proper contact between attenuated total reflection crystal and fiber are vitally important for high quality and accuracy of FTIR microscope spectra. Through reasonable parameter setting and sample preparation, in fact, the IR spectra of single fibers can be obtained quickly and reproducibly. (c) 2005 Wiley Periodicals, Inc.