source: © 2012 Optical Society of America
Optoacoustic (photoacoustic) mesoscopic and microscopic imaging is often implemented by linearly scanning a spherically focused ultrasound transducer. In this case, the resolution and sensitivity along the scan direction are limited by diffraction and therefore degrade rapidly for imaging depths away from the focal point. Partial restoration of the lost resolution can be achieved by using data-processing techniques, such as the virtual detector delay-and-sum method. However, these techniques are based on an approximate description of the detector properties, which limits the improvement in image quality they achieve. Herein we propose a reconstruction method based on an exact model of the optoacoustic generation and propagation that incorporates the spatial response of the sensor. The proposed method shows superior imaging performance over previously considered techniques.
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Fig. 1. (a) Geometry for the simulated scan. (b) Result of the scan for absorber 1. The color scale is linear, and the image is normalized to its maximum. (c) VD processing at the signal level: the signal of interest is on-axis (blue/solid), and is to be corrected with the aid of signals acquired at other sensor positions (one of them is shown in red/dotted). The off-axis signal is first time-shifted (black/dashed) and then (d) added to the signal of interest. (blue/solid), resulting in the VD-processed signal (black/dashed).