Measuring thermal focal length with a curvature sensor

Thermal focal length of an LD side-pumped Nd:YAG laser rod is measured and discussed. The edge-cooled solid-state laser rod pumped uniformly likes a lens. When the parallel beam goes through the rod, its wavefront will be changed and equal to the focal length. With the wavefront curvature sensor, the wavefront of the beam can be measured exactly. Any equipment should not move and change during the measurement, so that few errors may appear. In this way, the thermal focal length of the pumped laser rod can be measured easily. The experimental result shows that the thermal focal length of high power solidstate laser rod is short, and the theoretical and practical result is close．