A dual-beam Fourier transform infrared spectrometer (FT-IR) is described. Sensitivity improvement, photometric accuracy, and instrument stability are evaluated by comparing dual-beam spectra with conventional single-beam spectra. Dual-beam FT-IR data acquisitions require an order of magnitude less measurement time than single-beam acquisitions for spectra of comparable signal-to-noise ratios. Application of dual-beam FT-IR for analysis of a highly transmitting sample is discussed. Single fiber analysis without masking and without an infrared microscope is described.
Donald L. Beduhn and Robert L. White, "Advantages of Dual-Beam Interferometry in Fourier Transform Infrared Spectrometry," Appl. Spectrosc. 40, 628-632 (1986)