Multi-beam heterodyne laser Doppler vibrometer
First Claim
1. A multi-beam heterodyne vibrometer for analyzing vibration of an object, the vibrometer comprising:
- an optical system for;
generating a plurality of object beams and a plurality of reference beams, one of the plurality of beams having a frequency that is shifted from a frequency of the other plurality of beams;
transmitting the object beams to the object, a portion of each of the object beams being reflected off of the object as a modulated object beam; and
collecting the modulated object beams; and
a combining element for combining each of the modulated object beams with a respective one of the reference beams into a plurality of beam pairs.
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Abstract
A multi-beam laser Doppler vibrometer simultaneously measures velocity, displacement, and vibration history of multiple locations on an object. A beam of coherent light is split into an object beam and a reference beam. The object beam is divided into a plurality of object beams to simultaneously illuminate multiple locations on the object under inspection. The reference beam is frequency shifted and split into a corresponding plurality of frequency-shifted reference beams. A portion of each object beam is reflected by the object as a modulated object beam. The plurality of modulated object beams are collected and respectively mixed with the plurality of frequency-shifted reference beams to provide a plurality of beam pairs. Each beam pair may be focused onto a photodetector or an optical fiber connected to a photodetector.
27 Citations
25 Claims
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1. A multi-beam heterodyne vibrometer for analyzing vibration of an object, the vibrometer comprising:
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an optical system for; generating a plurality of object beams and a plurality of reference beams, one of the plurality of beams having a frequency that is shifted from a frequency of the other plurality of beams; transmitting the object beams to the object, a portion of each of the object beams being reflected off of the object as a modulated object beam; and collecting the modulated object beams; and a combining element for combining each of the modulated object beams with a respective one of the reference beams into a plurality of beam pairs. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for analyzing vibration of an object, the method comprising:
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transmitting a plurality of object beams to the object, a portion of the object beams being reflected by the object as modulated object beams; collecting the modulated object beams; and combining the modulated object beams with a reference beam; wherein one of the combined beams has a frequency that is shifted from a frequency of the other of the combined beams. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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22. A multi-beam heterodyne vibrometer for analyzing vibration of an object, the vibrometer comprising:
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a laser configured to provide an output beam; a first beam splitter configured to split the output beam into an object beam and a reference beam; a frequency shifter configured to shift a frequency of either the object beam or the reference beam; a second beam splitter configured to split the reference beam into a plurality of reference beams; a third beam splitter configured to split the object beam into a plurality of object beams for transmission to the object, a portion of the object beams being reflected by the object as a modulated object beam; a collecting lens disposed to collect the plurality of modulated object beams; and a combining element for combining the modulated object beams with one of the reference beams into a plurality of beam pairs. - View Dependent Claims (23, 24, 25)
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Specification