US 11,906,350 B2
Calibration apparatus and calibrating a laser doppler vibrometer
Michael Gaitan, North Potomac, MD (US); Jon Clement Geist, Olney, MD (US); Benjamin James Reschovsky, Cabin John, MD (US); and Akobuije Douglas Eziani Chijioke, Silver Spring, MD (US)
Assigned to GOVERNMENT OF THE UNITED STATES OF AMERICA, AS REPRESENTED BY THE SECRETARY OF COMMERCE, Gaithersburg, MD (US)
Filed by Government of the United States of America, as represented by the Secretary of Commerce, Gaithersburg, MD (US)
Filed on Jun. 2, 2021, as Appl. No. 17/336,964.
Claims priority of provisional application 63/035,127, filed on Jun. 5, 2020.
Prior Publication US 2021/0381883 A1, Dec. 9, 2021
Int. Cl. G01H 9/00 (2006.01)
CPC G01H 9/002 (2013.01) 9 Claims
OG exemplary drawing
 
1. A calibration apparatus for calibrating a laser Doppler vibrometer, the calibration apparatus comprising:
a bidirectional frequency shifter stage in optical communication with the laser Doppler vibrometer and that:
receives, from the laser Doppler vibrometer, primary laser light comprising a primary frequency that propagates in a forward propagation direction to the bidirectional frequency shifter stage from the laser Doppler vibrometer;
produces, from the primary laser light, frequency shifted light comprising a shifted frequency, such that the shifted frequency differs from the primary frequency;
communicates, in a forward propagation direction, the frequency shifted light from the bidirectional frequency shifter stage to a reflector;
receives, from the reflector, the frequency shifted light reflected by the reflector and that propagates from the reflector to the bidirectional frequency shifter stage in a reverse propagation direction;
produces secondary light comprising a secondary shifted frequency from the frequency shifted light reflected by the reflector, such that secondary shifted frequency differs from the shifted frequency and from the primary frequency; and
communicates the secondary light to the laser Doppler vibrometer in the reverse propagation direction, such that the laser Doppler vibrometer receives the secondary light from the bidirectional frequency shifter stage and produces a synthetic velocity shift from the secondary light; and
the reflector in optical communication with the bidirectional frequency shifter stage and that:
receives frequency shifted light that propagates from the bidirectional frequency shifter stage to the reflector in the forward propagation direction; and
reflects the frequency shifted light back to the bidirectional frequency shifter stage in the reverse propagation direction;
an analyzer in electron communication with the laser Doppler vibrometer and that receives the synthetic velocity shift from the laser Doppler vibrometer,
wherein the analyzer determines a calibration of the laser Doppler vibrometer from the synthetic velocity shift.