Improvements in a system for determining atmospheric data relating to the movements of an airborne vehicle

A plurality of lasers each regulated to operate at a particular temperature, are supported by a manifold to direct coherent light into space. The regulation may be provided by producing pulses of a trickle current of a particular magnitude through the laser, measuring the voltage required to produce the trickle current and adjusting the characteristics of a thermoelectric member in accordance with the magnitude of such voltage to adjust the rate at which the thermoelectric member transfers heat from the laser. The lasers produce substantially parallel and thin beams of light in pairs. The light beams in each pair provide an optimum angle for the interception by such paired beams, of particles having individual trajectories in space. These particles scatter the light to a receiving lens system disposed within the manifold. The received light then passes through masks which restrict the collected light to a spatial pattern corresponding to the pattern of the light beams from the lasers. The received light beams passing through the masks are detected to produce signals indicative of the light in such beams. The manifold temperature may be regulated to maintain the optical characteristics of the lasers and the receiving system at a constant and optimum value. The regulation may be provided by disposing heat sleeves on the manifold periphery, preferably in both axial and annular directions, and disposing in each heat sleeve a porous wick and a material convertible between liquid and gaseous forms. At positions above the regulated temperature, the liquid vaporizes and travels through the wick toward cooler spots where it vaporizes.