Gravity operated, rotatable lens curtain for thermal imager

Abstract

A device for in-situ calibration of a thermal imager on a UAS is disclosed. A rotatable lens curtain is provided with an aperture for the lens of a thermal imager to observe a field of view. The lens curtain comprises a balancing weight and blocking portion having a thermally uniform interior surface that functions as a calibration surface. The lens curtain is disposed with respect to the lens such that when the UAS is in a substantially level flight path, the lens is exposed to the field of view through the aperture. The lens curtain is provided such that when the UAS is rotated about an axis, the lens curtain maintains its absolute position relative to the Earth by virtue of the balance weight and the lens rotates within the lens curtain such that the blocking position obscures the lens from the field of view and the lens is exposed to the thermally uniform interior surface such that a calibration operation can be performed by the thermal imager.

Dependencies are inferred from the claim text.