The single frequency operation of a cw Ti:sapphire laser has been realized with an astimagition compensated ring cavity of four mirrors. A wideband optical diode was placed inside the cavity to force the tarvelling wave to travel unidirectionally. An intracavity complexed birefrigent filter and an etalon were used to tune wavelength, reduce linewidth and select the single longitudinal mode. Laser frequency was locked to a confocal reference cavity through electronic servo loop. Less than 430 kHz of frequency fluctuation when output was 183 mW and less than 610 kHz of frequency fluctuation when output was 423 mW within one minute were demonstrated at the wavelength of 790 nm.