首页>
外国专利>
Laser doppler vibrometer employing active frequency feedback
Laser doppler vibrometer employing active frequency feedback
展开▼
机译:采用有源频率反馈的激光多普勒振动计
展开▼
页面导航
摘要
著录项
相似文献
摘要
A laser Doppler vibrometer for vibration measurement that employs active feedback to cancel the effect of large vibration excursions at low frequencies, obviating the need to unwrap phase data. The Doppler shift of a reflective vibrating test object is sensed interferometrically and compensated by means of a voltage-controlled oscillator driving an acousto-optic modulator. For frequencies within the servo bandwidth, the feedback signal provides a direct measurement of vibration velocity. For frequencies outside the servo bandwidth, feedback biases the interferometer at a point of maximal sensitivity, thus enabling phase-sensitive measurement of the high-frequency excursions. Using two measurements, one with a low bandwidth and one with a high bandwidth, more than five decades of frequency may be spanned. This approach is of particular interest for the frequently occurring situation where vibration amplitudes at low frequency exceed an optical wavelength, but knowledge of the vibration spectrum at high frequency is also important.
展开▼