Rotating mirror drum radiometer imaging system

Abstract

A rotating mirror drum radiometer imaging apparatus. The apparatus generally comprises a two-sided mirror, a drum for securely supporting the two-sided mirror therein at an angle of preferably about 45 degrees relative to a longitudinal axis of symmetry extending through the drum, support walls for supporting the drum for rotational movement, and a motor and drive wheel for rotationally driving the drum. In one embodiment the drum includes first and second cut-outs in a side surface thereof. The cut-outs are further spaced preferably about 180 degrees from each other about the longitudinal axis of symmetry and enable a transmitted signal to be alternately received therethrough by first and second sides of the two-sided mirror as the drum and mirror are concurrently rotated by the motor and drive wheel. A first antenna is disposed adjacent a first end of the drum and a second antenna is disposed adjacent a second end of the drum. The first and second antennas, either dish antennas or an imaging array, alternately receive the signal as the signal is alternately reflected from the first and second sides of the mirror as the mirror is driven rotationally. Thus, both sides of the mirror are used to thereby effectively double the number of image scans obtainable for any given rotation rate of the mirror. The apparatus is particularly effective for high altitude imaging applications where the speed of an airborne platform may be quite high, thus necessitating a correspondingly high mirror rotation rate. The increased rotation rate of the mirror provided by the apparatus further allows higher refresh rates compared to heretofore designed scanning antenna systems.