PHOTOACOUSTIC EFFECT

Alexander Graham Bell, 1880 — Light Becomes Sound
Wavelength (nm) 520 nm
Pulse Rate (Hz) 5 Hz
Pulse Energy 1.0 mJ
Click wavelength in spectrum to select
The photoacoustic effect: pulsed light absorbed by a sample causes rapid heating, thermal expansion, and a pressure wave detectable as sound. Each material has a unique absorption spectrum — this is the basis of photoacoustic spectroscopy, used in medical imaging, gas detection, and archaeology.