ABSTRACT
During 2019, an infrared camera, the compact thermal imager (CTI), recorded 15 million images of the Earth from the International Space Station. CTI is based on strained-layer superlattice (SLS) detector technology. The camera covered the spectral range from 3 to 11 µm in two spectral channels, 3.3-5.4 and 7.8-10.7 µm. Individual image frames were 26×21km2 projected on the ground, with 82 m pixel resolution. A frame time of 2.54 s created continuous image swaths with a 13% along-track image overlap. Upper limits determined on the ground and in flight for the electronic offset, read noise, and dark current demonstrated the stability of the SLS detector and camera over many months. Temperature calibration was established using a combination of preflight and in-flight measurements. A narrowband approximation of temperature as a function of photon counts produced an analytic relationship covering a temperature range of 0°-400°C. Examples of CTI images illustrate temperature retrievals over sea ice, urban and agricultural areas, desert, and wildfires.
ABSTRACT
Two frequency scanning ultrasonic spectrographs utilizing time-delay signal processing techniques have been developed. These permit measurement of time delays (and hence velocity changes) in a sample in the order of 10(-8) s. The present instruments allow such measurements to be made continuously over a frequency range of 1-10 MHz. These instruments have been used to monitor changes in velocity as a function of frequency during coagulation in purified human fibrinogen solution and human plasma. It was found that velocity dispersion occurred at discrete frequencies during the coagulation process. The frequency dependent data is reproducible, although this depends to some extent upon the samples used. The instruments which were calibrated using a fixed length of coaxial cable, exhibit a high degree of reproducibility.
