초록 ▼

A contactless system for imaging an acoustic source within a workpiece directs a preferably annular optical probe beam pattern onto the vibrating workpiece surface, with the vibrationally modulated beam then detected by an array of preferably non-steady-state photo-emf detectors arranged in a simila

A contactless system for imaging an acoustic source within a workpiece directs a preferably annular optical probe beam pattern onto the vibrating workpiece surface, with the vibrationally modulated beam then detected by an array of preferably non-steady-state photo-emf detectors arranged in a similar pattern. The probe beam is scanned over the vibrating surface, either mechanically or through an electronically simulated phased array scheme. Time gating is used to suppress unwanted side-lobes when the individual detector outputs are summed over an appreciable waveband. A self-calibration scheme is also preferably used that provides a quantitative as well as qualitative output. A calibration modulation is imposed on at least one of the probe and reference beams, with the calibration modulation later removed at a post-detector stage and used to normalize the acoustic modulation output. Variations of the self-calibration scheme include reference-beam and time-delay interferometers based upon a calibrating phase modulation, and a photon flux measurement approach based upon a calibrating amplitude modulation.

대표청구항 ▼

[ We claim:] [1.] A contactless sensing system for locating an acoustic source within a medium that has a surface which vibrates in response to acoustic signals from the source, comprising:an array of discrete optical detectors,a probe beam director for directing an optical probe beam onto said vibr

[ We claim:] [1.] A contactless sensing system for locating an acoustic source within a medium that has a surface which vibrates in response to acoustic signals from the source, comprising:an array of discrete optical detectors,a probe beam director for directing an optical probe beam onto said vibrating surface in a pattern that corresponds to said detector array, and for directing at least a portion of the probe beam reflected from said surface onto said detector array,a reference beam director for directing a reference beam onto said detector array at an angle to said probe beam to produce fringe patterns on said detectors which correspond to the vibrations along said surface pattern, anda readout system that obtains output signals from said discrete detectors to produce an array output signal indicative of at least a two-dimensional location for said acoustic source relative to said surface.