Conventional contacting transducers are highly sensitive and readily available for ultrasonic and photoacoustic imaging. On the other hand, optical detection can be advantageous when a small sensor footprint, large bandwidth and no contact are essential. However, most optical methods utilizing interferometry or Doppler vibrometry rely on the reflection of light from the object. We present a non-contact detection method for photoacoustic and ultrasound imaging--termed Gas-Coupled Laser Acoustic Detection (GCLAD)--that does not involve surface reflectivity. GCLAD measures the displacement along a line in the air parallel to the object. Information about point displacements along the line is lost with this method, but resolution is increased over techniques that utilize finite point-detectors when used as an integrating line detector. In this proceeding, we present a formula for quantifying surface displacement remotely with GCLAD. We will validate this result by comparison with a commercial vibrometer. Finally, we will present two-dimensional imaging results using GCLAD as a line detector for photoacoustic and laser-ultrasound imaging.
Jami L. Johnson, Kasper van Wijk, James N. Caron, and Miriam Timmerman, "Photoacoustic and ultrasound imaging with a gas-coupled laser acoustic line detector," Proc. SPIE 9708, Photons Plus Ultrasound: Imaging and Sensing 2016, 970814 (Presented at SPIE BiOS: February 15, 2016; Published: 15 March 2016); https://doi.org/10.1117/12.2211800.
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