LEOI-50 is designed for teaching nonlinear optical experiments at universities and colleges. It can help students understand the theory of a diode-pumped solid-state (DPSS) laser with frequency doubling technique. A solid-state laser with Nd: YVO4 as the gain material, which is pumped by a semiconductor laser at 808 nm, emits infrared light at 1.064 μm. By incorporating a KTP crystal into the laser cavity to generate frequency-doubled green light, it is possible to observe frequency doubling phenomenon, and measure frequency doubling efficiency, phase matching angle and other basic parameters.