NASA - National Aeronautics and Space Administration

THOR stands for THickness from Offbeam Returns. This Lidar system is designed to estimate the thickness of clouds by measuring the size of the reflected halo resulting from a laser entering a cloud. A refractive telescope with approximately 7.5-inch (19.05-centimeter) aperture is used to gather the returned light and collect it into a custom designed fiber optic bundle. The fiber optic bundle routes specific sections of the light focused by the telescope into ten Hamamatsu detectors.