Photoacoustic imaging is a method combines the advantages of optical imaging (high contrast) and ultrasonic imaging (high spatial resolution). This results in various new applications in the field of biology, medicine, industry and material science.
Principle
To generate photoacoustic signals short laser pulses (in the range of nanoseconds) are used. The electromagnetic energy (laser) is absorbed in the sample. Due to the thermoelastic expansion in the region of absorption – the so called photoacoustic effect – a broadband ultrasonic signal is launched. The photoacoustic signal is recorded at different positions at the surface of the sample by a special transducer. Taking such a set of data it is possible to calculate either slices of the objects or the whole volume using reconstruction algorithms such as Time Reversal, Back Projection, or other methods. In Fig. 1 a scheme of the principle of photoacoustic tomography can be seen.
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| Fig 1. PhotoAcoustic Effect |
