The apparatus of a linearly polarized light source that ro tates at arbitrary high frequencies was constructed using an Acoustooptic Tunable Filter employing a TeOz crystal. The characteristics of optical devices, such as birefringence of optical fiber, transmisslvity of half mirror, angle of rotation of optical isolator, and film thickness and refractive index of optical thin-film, were measured using this ap paratus. The advantages of this apparatus are Its simple construction, ability to produce high rotating frequencies, and ability to use various laser beams.