Abstract: A laser and laser mount system for a vehicle measurement system wherein the laser is powered by a direct current source, such as a battery, and the laser is mounted on the same axis as its rotational pivot axis which provides for up to 360.degree. of rotation of the laser about such axis.

Abstract: A selectible beam/plane projecting laser is particularly useful for vehicle frame and body alignment. A lens contained in a holder mechanism mounted on a laser projector housing flips into and out of the laser beam path and when in the path, changes the beam to a plane. When used for vehicle frame and body alignment, the plane of the laser generated light allows the operator to spot targets any place in the plane of light and makes easier determination of alignment conditions.

Abstract: An optical tracking system for aircraft and the like which measures positional variations of a portion of a laser transmitter pulse train or beam returned from a tracked object to derive error signals for energizing the tracking servo mechanism. In particular, the system detects such beam position change by measuring variations in energy received by a quadrant-segmented photo sensor relative to the sensor axis of symmetry. Compensation for scintillation (variation with time of the spatial intensity distribution) of the return beam due to change in the index of refraction of the atmosphere is achieved, in accordance with the invention, by focusing the return beam to a small diameter and passing it through a diffusing medium such as opal glass or a fiber optic bundle. The energy in the output beam from this medium is homogeneous and substantially invariant with time so that tracking error due to scintillation is eliminated.