Methods Photoacoustic Imaging
Photoacoustic Imaging
Photoacoustic imaging is a new upcoming 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.


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.


In the field of photoacoustic imaging RECENDT traces an unique approach concerning special detectors – so called integrating detectors. An integrating detector is at least in one dimension bigger than the sample. The most practicable type of integrating detectors is a line detector which can be realized in different ways (piezo line, free-beam interferometer, …). RECENT uses a promising approach. Fiber-based line detectors are developed. This type of detector shows easy handling and avoids complex adjustment. Compared to piezo electrical detectors fiber-based detectors are less sensitive against electrical disturbance from the environment and show a much better frequency response for the whole frequency range – from a few Hertz up to the Megahertz-regime.


The aim of the detector development is a more sensitive broadband ultrasonic detector. Such a detector will be deployable for novel biological, medical or industrial applications. This way RECENDT provides a novel technique and enhanced detectors for imaging objects achieving high contrast and simultaneously high spatial resolution.