A large-area plate radiator with in situ temperature homogenization for thermographic imager calibration.

Large-area plate radiators with a high emissivity and uniform temperature distribution are needed as reference sources for calibrating infrared imagers and camera systems. However, achieving very uniform temperature distribution over a large area is technically challenging, especially at high temperatures. We present a large-area plate radiator with an improved uniformity in its surface temperature distribution for the calibration of infrared thermographic imagers.

Nonuniformity correction of imaging systems with a spatially nonhomogeneous radiation source.

We present a novel method of nonuniformity correction of imaging systems in a wide optical spectral range by applying a radiation source with an unknown and spatially nonhomogeneous radiance or radiance temperature distribution. The benefit of this method is that it can be applied with radiation sources of arbitrary spatial radiance or radiance temperature distribution and only requires the sufficient temporal stability of this distribution during the measurement process. The method is based on the recording of several (at least three) images of a radiation source and a purposeful row- and line-shift of these sequent images in relation to the first primary image.

Optical methods for power measurement of terahertz radiation.

Precision power measurements of terahertz (THz) radiation are required to establish metrological applications in the THz spectral range. However, traceability to the International System of Units (SI) has been missing in the THz region in the past. The Physikalisch-Technische Bundesanstalt (PTB), as the national metrology institute of Germany, determines the spectral responsivity of detectors for THz radiation by using two complementary optical methods: source- and detector-based radiometry.