Researchers at the Institute of Photonics technology at Jinan University in Guangzhou have adapted fibre-optic sensors for medical ultrasound imaging to develop a fibre laser photoacoustic imaging technique that manipulates how sound affects laser pulses. The sensors are compact laser built within the core of a single-mode 8 µm optical fibre. The fibre deforms when the fibre lasers are impacted by ultrasound waves parallel to the length, which modulates the emitted frequency of light. By detecting the frequency shift, the team can use self-heterodyning to reconstruct the acoustic waveform. This technique measures the effect of the mixing of two frequencies and is superior to the more common method of interferometry as the signal output is more stable.
“Sensor technology adapted for medical ultrasound imaging“
Team leader Long Jin said: “This method can also be used to structurally image other tissues and functionally image oxygen distribution by using other excitation wavelengths, which takes advantage of the characteristic absorption spectra of different target tissues. Current commercial endoscopic products are typically millimetres in dimension, which can cause pain, and they don’t work well within hollow organs with limited space.”