A new cavity has been designed to allow the amplification of both stimulated and spontaneous emission. Mercury-vapor in the new cavity produces peak wavelengths at 404, 436, 546, and 577 nm which are very close to the blood absorption peaks. The excitation techniques include both direct current and optical pumping of the mercury-vapor medium, to increase the power density of the output light, therefore, making it suitable for most medical applications. OptoDermTM is a new skin lesion treatment system, based on the mercury-vapor- unilaser. The output is gated quasi-pulsed, with high power pulses of 3 millisecond duration, in addition to a low level continuous wave beam as the aiming beam. The power supply is designed to match the plasma region, and is capable of pumping the cavity at high currents to produce the high power output pulses. The proper choice of the plasma region and the power supply, resulted in a very small, lightweight, and affordable system ideal for clinical and laboratory environments.