The acoustic lens will collect the waves generated from an optical absorber in the object plane and focus them onto an ultrasound detector placed in the image plane as shown in Figure 1. The object plane here corresponds to a coronal plane in the tissue unlike sagittal or transverse planes imaged by a conventional ultrasound imaging system. Image plane is defined by time delay measured with respect to time t=0 when the laser illuminates the tissue.

Figure 1:Acoustic Lens based Photoacoustic image formation

The advantages of the acoustic lens focusing over electronic focusing:

• Its faster
• It uses zero electrical power
• It is inexpensive to design and implement
• There are no errors in the reconstructed image due to spatial and temporal sampling of the signal.