Abstract: A device for measuring the speed of the wind at medium altitude by the Doppler effect within the visible frequency range comprises a laser which emits pulses of light, a telescope which receives a scattered light and an interferometer used to measure the spectral shift of the scattered light in relation to the emitted pulse of light. The interferometer is a Fabry-Perot interferometer in which a part of one of the two mirrors of the interferometer is covered with an excess thickness of silica to form two separate filters. The spacing of the two mirrors and the excess thickness of silica are determined in such a manner that the pass bands of each one of the two filters thus constructed are centered on the flanks of the spectral distribution of the backscattered light.

Abstract: A vehicle for the exploration of the atmosphere comprising an infra-red and olar montgolfier (hot-air balloon) capable of being piloted reversibly. The vehicle comprises a gas-tight envelope in which the upper part of the envelope is either transparent to or slightly absorbent of infra-red radiation, the outer face of the upper part of the envelope is slightly emissive in the infra-red region of radiation and the inner face of the upper part absorbs infra-red radiation so that ascending forces which act on the montgolfier are only obtained as a result of the heating of the gas contained in the envelope which is produced by the absorption of infra-red radiation.