Abstract: Optical transceiver apparatus for detecting angular misalignment between a pylon and fuselage of a helicopter, includes an optical transmitter secured to one of the pylon and fuselage and which transmits three spaced optical beams; an optical receiver which receives the optical beams from each optical transmitter, the optical receiver being mounted on another one of the pylon and fuselage, the optical receiver including a two linear detectors which detects angular twist between the pylon and fuselage from a null position in response to two of the optical beams, substantially irrespective of the distance between the pylon and fuselage, and a radially variable detector which detects elevation and azimuth changes of the pylon with respect to the fuselage from a null position in response to the third of the optical beams, substantially irrespective of the distance between the pylon and fuselage.

Abstract: An alignment device for aligning the boresight axis of armament with the line-of-sight axis of an optical sight including a novel collimating apparatus for field use. The collimating apparatus includes a collimator and a collimated light beam generator. The collimator includes an objective lens having its optical axis parallel to one of the axes to be aligned, a translucent screen for rear projection and a projection lens between the objective lens and the screen. A remote collimated light beam generator includes a battery energized incandescent light bulb, a projection reticle, and an objective lens for collimating the light source, the optical axis of the lens being parallel to the second of the axes to be aligned. The angular displacement between the axes is indicated by the position of a light spot on the screen.