A method includes receiving a first optical signal at a first communication terminal from a second communication terminal through a free space optical link. The received optical signal contains a modulated unique frequency tone. The method also includes mixing the modulated unique frequency tone with a reference signal to provide a mixed output signal and determining a signal strength of the modulated unique frequency tone based on the mixed output signal. The reference signal includes a same frequency as the modulated unique frequency tone. The method adjusts an optical head of the first communication terminal to establish acquisition and optical beam pointing with the second communication terminal based on the signal strength of the modulated unique frequency tone received from the second communication terminal.