发明名称 |
Contactless acoustic sensing system with detector array scanning and self-calibrating |
摘要 |
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.
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申请公布号 |
US6075603(A) |
申请公布日期 |
2000.06.13 |
申请号 |
US19970848929 |
申请日期 |
1997.05.01 |
申请人 |
HUGHES ELECTRONICS CORPORATION |
发明人 |
O'MEARA, THOMAS R.;PEPPER, DAVID M. |
分类号 |
G01D5/26;G01H9/00;(IPC1-7):G01B9/02 |
主分类号 |
G01D5/26 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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