We have measured the out-of-band transmittance (attenuation) for several narrow-band filters using two Fourier-transform infrared spectrometers in the wavelength range of 2–25 μm. Band-rejection filters are used to eliminate the power transmitted in the main band of the filter under investigation. Neutral-density filters are used for the reference measurement to reduce the effect of nonlinearity. Results from different optical arrangements are compared and discussed. This study demonstrates the feasibility of using Fourier-transform infrared instruments to measure a spectral transmittance of 10−6.
© 1995 Optical Society of America
Original Manuscript: November 3, 1994
Published: May 1, 1995
Z. M. Zhang, L. M. Hanssen, and R. U. Datla, "High-optical-density out-of-band spectral transmittance measurements of bandpass filters," Opt. Lett. 20, 1077-1079 (1995)