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Calibration of the spectral radiant power responsivity of windowed pyroelectric radiometers from 785 nm to 14 μm

2008; SPIE; Linguagem: Inglês

10.1117/12.799665

1996-756X

Jinan Zeng, Leonard M. Hanssen,

Optical and Acousto-Optic Technologies

As part of the optical detector characterization program at the Optical Technology Division at NIST, we have established a capability for the calibration of spectral radiant power responsivity in the infrared from 785 nm to 14 μm. We have used our facilities to characterize two commercial pyroelectric radiometers with KRS5 windows. The calibration methodology consists of the determination of the responsivity at single wavelength tie points together with relative spectral responsivity measurements. Responsivity tie points at 785, 1064, 1320, 1600, 2000 and 10600 nm are obtained against the NIST ACR-L1 absolute cryogenic radiometer as well as a domed pyroelectric transfer standard, using an OPO tunable laser and a stabilized CO 2 laser as sources. The spatial variation of the responsivity of the test radiometers has also been measured. This enables us to minimize the uncertainties due to interference fringes from the KRS5 window. The relative spectral responsivity curves for the two radiometers are obtained indirectly through measurement of the detector absorptance with an FTIR-based integrating sphere reflectometer. In order to obtain the actual absorptance at the detector from the reflectance measurements, an individual KRS5 window and a bare detector were also measured. The results are compared and the uncertainty budgets will be discussed.