The optical system for detecting wake profiles based on laser backscattering by bubbles at 180 degrees is reported, in which the monostatic optical geometry is adopted and the power density estimation is used to process bubble scattering signal. The profiles of wakes produced by a two-blade propeller with a diameter of 46 mm at 6000 and 8000 rpm are measured using this system. It is shown that the wake region can be identified, the wake with different shapes can be distinguished, and the fine structure within wakes can be detected. Also, the repeatability of the results is tested experimentally. Results show the feasibility of this system in wake profile detection.