The choice of a laser for airborne depth sounding

A conventional electro-optically Q-switched laser resonator and a polarisation coupled crossed-Porro resonator are compared for use in a frequency doubled neodymium doped yttrium aluminium garnet (Nd:YAG) laser. Laser rod diameters of 3, 4 and 5 mm are evaluated in each resonator to determine the relative merits of each rod/resonator combination in producing the required 532 nm frequency doubled output. The effect of repetition rate over the range 15 Hz to 250 Hz on the performance of each resonator and rod is examined. A lifetest is used to determine the likely problem areas in both resonators. Recommendations are made concerning the size of rod and type of resonator configuration best able to meet the requirements of a laser suitable for airborne depth sounding.