Photoacoustics is a non-invasive sensing technique that differentiates between materials with different optical absorption and mechanical properties. The photoacoustic (PA) effect is the process of light being absorbed by a material, creating a temperature change that produces a pressure transient. The operational and detection characteristics of two different PA imaging techniques were investigated based on pulsed and continuous wave (CW) optical illumination. A new phantom material, polyvinyl chloride-plastisol (PVCP), was characterized using the optoacoustic method and diffuse reflectance measurements, and phantoms with known optical properties were prepared. A thermal lesion was generated in chicken tissue and also imaged. The pulsed PA method can detect low absorption targets and thermal lesions in chicken tissue. The CW or frequency domain PA method uses a chirp modulated laser as the source of excitation. This system was characterized relating the detected PA signals to the incident fluence rate and known optical properties of PVCP samples.