The recently introduced remote photoacoustic imaging technique allows measurement of photoacoustic signals on nonplanar surfaces without the need for a water bath or coupling agent. Hereby, photoacoustically generated ultrasonic displacements are detected without physical contact to the sample by utilizing laser interferometric techniques. In this work we adapted different algorithms to allow reconstruction on non-planar surfaces and evaluate them on experimental and simulated data. Experimental data were obtained using a remote photoacoustic setup based on two-wave mixing in a photorefractive crystal. Ultrasonic displacements were acquired on flat and non-flat surfaces. Three-dimensional reconstruction of simulated and real measurement data is shown with synthetic aperture focusing technique, Fourier domain synthetic aperture focusing technique, and spectral-domain time reversal algorithms. For the synthetic aperture focusing technique and the time reversal algorithm the surface morphology is taken into account. It is demonstrated that artifacts can occur if the surface is not considered. For the experimental data the shape of the surface is obtained from optical coherence tomography or by a priori knowledge.
- image reconstruction
- photoacoustic imaging
- spectral domain time reversal