EFFECTS OF ELECTROMAGNETIC DISTURBANCE ON LIGHT INTENSITY SIGNAL OF LASER BEAM SYSTEM

In performing the experiments, the interference source has the form of a hollow PVC tube wrapped with a current-carrying coil, while the detector has the form of a PIN (Positive-Intrinsic- Negative) photodiode. The experimental results show that the electromagnetic disturbance (EMD) signal effect is dependent on the number of turns, the direction of the electromagnetic field, and the frequency and amplitude of the interference voltage. Specifically, it is shown that when the electromagnetic field acts in the opposite direction to that of the laser beam, the intensity and optical power of the detected signal decrease with an increasing interference frequency or amplitude. By contrast, when the electromagnetic field acts in the same direction as that of the laser beam, the intensity and optical power increase with an increasing interference frequency or amplitude. In addition, it is shown that the effect of EMD on the intensity of the laser beam increases with an increasing laser beam dispersion (i.e., an increasing distance from the laser source).