Optical multichannel transducer array for wind tunnel applications

The optical multichannel transducer array (OMTA) is a fiber optic-based sensor designed to measure pressure profiles with high time and spatial resolution for wind tunnel applications. The OMTA is an in- tegration of various state-of-the-art technologies and consists of two in- terchangeable sensor array heads (10 channels, 32 channels) and the associated fiber optics, a filter spectrometer with a 64-element detector array, diode lasers and their controllers, and a LabView-based software control system. The sensor head arrays are produced by anisotropic etching of masked silicon wafers to produce multiple independent ele- ments. These arrays, having 10 and 32 individual, 0.81-mm 2 elements and 1.1-mm center-to-center spacing, are designed for flush mounting in a hypersonic wind tunnel model. Laboratory calibration using dc and low-frequency pressure ramps showed that the measurable displace- ment resolution was approximately 0.01 m, which corresponds in this configuration to 0.1 psi. The frequency response is approximately 50 kHz for 32 channels. The entire system is mounted on one laboratory rack for installation near a wind tunnel facility.