<title>Characterization of narrowband infrared interference filters</title>

Abstract

A Fourier-transform infrared (VF-IR) spectrophotometer system is used to measure the transmittance of infrared band-pass filters as a function of wavelength, temperature, and beam geometry. Measurements are performed using an ff4 beam geometry at normal incidence, or a nearly collimated geometry with variable angle of incidence. Blocking filters are used to expand the dynamic range of the out-of-band measurement to transmittances as low as 1116with 4 cm1 resolution.