A rocket borne instrument module for detecting atomic oxygen concentrations by the resonance fluorescence technique is reported. The module contained a source lamp emitting OI 1304 ¿ photons and a detector for the scattered photons. The module was constructed so that it could be coupled to a fast flow reactor for calibration purposes. During the flight the module was radially deployed from the payload on an oscillating boom with a maximum extension of 90 cm from the skin. Analysis of the initial flight data indicates that the shock formed by the motion of the rocket had a substantial effect on the data and the maximum concentration of the layer as 93 km was about 1.1¿1011 cm-3.