Figure 8
(a) Optical Setup for remote photoacoustic sensing in transmission-mode using speckle analysis. The detection unit consists of a high speed camera (1), lens (2), aperture (3), bandpass-filter (4) and microscope objective (5). The speckle pattern is generated by cw-laser beam (6) which is focused on the phantom surface (9) using a lens (7). The sample is excited with a short laser pulse aiming at the phantom centre (8) which triggers the high speed camera. (b) Optical Setup for remote photoacoustic sensing in reflection-mode. Excitation and sensing take place on the same object side. (c) The resolution of the imaging system was measured at 2.76 μm (Group 7, Element 4) using a USAF 1951 Test Target. (d) Example of a speckle image captured with the imaging setup (128 × 16 pixel). The scales are added using the resolution, pixel size and the optical magnification \(M=10\).
