We report on extra cavity frequency doubling lasers for 266 nm with a compact, tunable extended cavity diode laser (ECDL) at 1 064 nm. The ECDL injected into a tapered amplifier yields a power of 290 mW. In a first frequency-doubling stage, about 47-mW green light at 532 nm is generated. Subsequent second-harmonic generation (SHG) employing a BBO crystal leads to about 30 μW of ultraviolet (UV) light at 266 nm. The tunable characteristic of this UV light source is discussed. The tuning span of quasi-phase matching of doubling cavity for 532 nm with PPKTP crystal is achieved with –3.5 nm by changing the temperature of PPKTP and is achieved with –1.186 nm by adjusting angle of PPKTP.