Based on the Ring-Cavity optical parametric oscilaltor (OPO) technology, the Phocus ESSENTIAL represents the ideal light source for photoacoustic imaging applications that require high pulse energies and NIR wavelengths for deep penetration of biological tissue. High damage thresholds combined with minimal maintenance and turn-key operation reduce system down-time and allow ease of operation. The system provides an ultra-compact, light-sealed, transportable cart designed for deployment into pre-clinical environments. A customizable, safety-interlocked fiber bundle delivers light from the system to the instrumentation and prevents system operation without fiber attachement. Motorized harmonics and fiber bundle delivery provide a completely, hands-free system tunable laser system.