Dual field horizon scanner

Abstract

Pitch and roll attitude information of an orbiting body is provided by sensing the discontinuity of optical radiation in a scan field of view between the reference body and outer space using a scanner which simultaneously scans two concentric conical paths through the field of view about the same axis of rotation of the orbiting body. The scanner comprises a scanning mirror split into two halves which are tilted through an angle with respect to each other and are also displaced in phase with respect to each other about the axis of rotation. The scanner may also be a prism having angled faces on opposite sides of the optical axis of the scanner which are also displaced in phase. Either scanner results in having a detector view two instantaneous fields of view simultaneously. An infrared detector receiving the radiation from these two fields of view produces signals which can be used to determine pitch and roll attidue as well as altitude on each scan which identifies four points around the horizon. This is all accomplished using but a single conical scanner.

Dependencies are inferred from the claim text.