Photoacoustic (or optoacoustic) imaging is a high-resolution hybrid imaging technique utilizing the sensitivity and contrast of optical imaging with the depth of ultrasound.
As the name suggests, the physical principle at the basis of the method is a photoacoustic effect. In order to observe the effect, a modulated or pulsed laser is used. Laser light is absorbed causing thermoelastic expansion and an acoustic wave follows which is detected by an ultrasound transducer.
The technique is mostly used for in-vivo high resolution real-time non-invasive bioimaging. It can be applied for either microscopy or tomography. The high resolution and contrast is achieved due to the less prominent scattering and absorption of ultrasonic waves in comparison with visible and near infrared light. Therefore, in order to obtain high contrast images with photoacoustic imaging, the wavelength of the laser should be chosen according to the absorption curve of the sample under investigation.
At HÜBNER Photonics, the compact Cobolt Tor Series of pulsed lasers with a repetition rate of up to 7 kHz and pulse energies up to 160 uJ/pulse, is very suitable for photoacoustic microscopy applications.