ABSTRACT We reported pump uniformity study of a side-pumped DPSS laser, which produced CW output of 30 W with aproper uniform pumping. An JR camera was employed to study the pump energy distribution as well as thethermal effect inside the laser crystal. Theoretically simulated energy distributions were compared with theexperimentally measured JR images. Jt is found that the JR imaging technology is an effective method to studypump uniformity of side-pumped DPSS lasers, and uniform pumping is very essential to achieve a good beam quality and a wider stable operating range for high-power DPSS lasers.Key words: Diode-Pumped, Solid-State Lasers, Infrared Imaging 1. INTRODUCTION In the recent years, diode-pumped solid-state (DPSS) lasers have been the fastest growing segment in the worldwide lasermarket [1, 2], as well as the one ofthe most active research topics in the areas oflasers [35]. Although DPSS lasers havemany obvious advantages over the traditional lamp-pumped solid-state lasers, especially in the aspect of overcoming thethermally induced problems, thermal effect is still one of the major problems for the application and commercialization of