Light polarization effect in measurement of thin wire diameter by laser diffraction and its explanation with boundary diffraction wave

The polarization effect in the measurement of thin wire diameter by laser diffraction has been studied experimentally and theoretically in this paper. The experimental values of a diameter vary sinusoidally with the vibration direction of incident polarized light. The difference between measured diameter values with S and P component of incident light is nearly proportional to the imaginary part of the complex index which represents the optical property of metal wire. Taken into account the phase change of boundary diffraction wave originating from the edges of metal wire, the physical cause of this polarization effect, and its experimental results have been clearly explained.