A 3D imaging system includes: a light source; a modulator connected with the light source and configured to modulate output of the light source with a frequency sweep signal; an optical module connected to the light source; a light sensing device connected with the optical module and configured to sense optical output of the optical module and convert the optical output into a plurality of electrical signals; and a signal processing module connected with the light sensing device and configured to extract 3D information of the object from the electrical signals.