Recently, intensive research has been conducted to accelerate the development of photoacoustic (PA) imaging modality for biomedical applications. The use of acoustic lenses to collect ultrasound signals is of great interest. This Letter presents the design and fabrication of a liquid acoustic diverging lens, which can enlarge the acceptance angle of an ultrasound transducer. This lens possesses an inherent advantage of low acoustic impedance and the convenience to be attached to or detached from a commercial flat transducer. Phantom experiments have been carried out to demonstrate the improvement of using such a liquid lens over using a bare transducer for PA tomography.