Multi-beam heterodyne laser Doppler vibrometer

A method for analyzing vibration of an object, the method comprising:

• 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.

A multi-beam heterodyne vibrometer for analyzing vibration of an object, the vibrometer comprising:

• 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.