According to the ’332 patent, existing techniques for measuring high speed surface deformations or vibrations use a single laser beam which is scanned across the surface. The movement of the surface can be measured using interferometry to detect the Doppler shift of the light (e.g., in laser Doppler vibrometry or LDV) or changes in the speckle pattern of the reflected light (e.g., in electronic speckle pattern interferometry or ESPI). While these techniques work well for steady-state or well-characterized vibrations, the time in scanning the single beam across the surface being measured can make it difficult to measure transient or non-steady-state vibrations. The ’332 patent discloses a system that uses multiple laser beams to irradiate the surface and a flood reference beam to generate multiple interference signals simultaneously across the two-dimensional surface.
According to MetroLaser’s website, the company’s VibroMet™ multi-beam laser Doppler vibrometers are being used for noise and vibration measurements world-wide in a variety of industrial, military, and space applications (e.g., automobile, aircraft, and even landmine detection).
According to the USPTO database, MetroLaser has 10 U.S. patents, and the ’332 patent is its first in 2011.