Two-dimensional detection of optoacoustic stress transients

For enhanced optoacoustic imaging in biomedical applications more than one-dimensional detection is required. Tomographic images comparable to ultrasound B-scans can be generated with linear arrays. This work presents a detection scheme for such an array based on piezoelectric films. Each single detector consists of a ring shaped active area with a diameter of less than one millimeter, which leads to a high lateral resolution. Because of the small dimensions of the systems it is suitable for applications with limited accessibility like ophthalmic or endoscopic use. The sensitivity of a single detector is close to 0.5 mV/bar. First measurements on layered tissue phantoms made of gelatine and absorbing films show the potential of such an array for depth profiling as well as for two-dimensional imaging of simple structures.