Abstract: An direction determining instrument provides an image reversing device positioned for siting a fixed indicator indicia and a mirror image reversed compass rose supported for rotation about its center. The compass rose is enabled by a magnetic device such as a magnet, for seeking magnetic north. The image reversing device, compass rose, and fixed indicator indicia are arranged and positioned so that the fixed indicator indicia and the rotatable mirror imaged compass rose are visible in the image reversing device as a non-reversed compass rose superimposed on the indicator indicia such that rotation of the compass rose appears to move in the direction of rotation of the instrument.

Abstract: An apparatus is provided for analyzing the polarization state a light beam. A rotatable disk provides, on a surface of the disk, a visual indicator and a centrally positioned polarizer. The indicator and polarizer rotate with the disk as a single unit. A drive motor is engaged with the rotatable disk for providing motive force in rotating the disk about its central rotational axis. A signal processing circuit includes an optical detector positioned on one side of the polarizer for receiving the light beam after the light beam passes through the polarizer. The optical detector produces a detector electrical signal of an amplitude generally dependent on the instantaneous rotational position of the rotatable disk, as such position is determinant of the light attenuating power of the polarizer on the light beam. The signal drives the visual indicator to produce a visual image as the disk rotates.