The conventional way used in Ultrasound Imaging is based on field generation and echo detection using piezoelectric crystals. BioScan took a non-conventional approach and based its design on acoustical generation and detection by using light propagating through optical fibers.
The ultrasonic emitter is excited by laser pulses. The interaction of optical energy with the materials causes a thermoelastic expansion as result of an energy absorption process. The absorption process is rapid and undergoes attenuation. As a result of absorption of the radiation energy, temperature gradients are established within the solid, which in turn produce a rapidly changing strain field (thermoelastic effect) that radiates energy as elastic (ultrasonic) waves. The spatial and temporal properties of the emitted field depend on several parameters. The result is an ultrasonic pulse source with stable and repeatable performance.
The reflected echoes from the tissues are sensed by a fiber carrying continuous laser energy. Light propagated back and forth through the fiber, is phase modulated by the external ultrasonic echoes, through several mechanisms like diffraction index change, length variation or polarization shift. By subtracting the reflected and the transmitted light we detect the phase modulation that is directly related to the echo signal reflected from the tissue. The result is sampled and analyzed for the calculation of tissue characteristics.
Based on this effect, BioScan has developed its unique and proprietary technology that combines the power of laser with the diagnostic properties of ultrasound.