/a></li>
		<li><a href="#heading3">Running the reconstruction</a></li>
	</ul>
</div>

<a name="heading2"></a>
<h2>Selecting a focus function</h2>

<p>The reconstruction of images in photoacoustic tomography is reliant on specifying the speed of sound within the propagation medium. However, for in vivo imaging, this value is not normally accurately known. To overcome this, an optimisation of the selected sound speed is performed to maximize the sharpness of prominent features visible within the reconstructed