An Enhanced Common Path Interference Measurement Method for Optical Refractive Indices

This study presents an enhanced common path interference system designed to measure the refractive index of crystal optical components. The proposed system is based on the classic Michelson interferometer and comprises a frequency stabilized helium-neon (He-Ne) laser, a beam splitter, a fixed mirror, an adjustable mirror, and a light detection system. The waveplate of interest was clamped to a rotatory motor and positioned between the beam splitter and the fixed mirror. The refractive index of the waveplate was then derived from the change in rotational angle of the waveplate as it moved from one position of minimum interference to the next. The measurement system proposed in this study is simple in construction, straightforward in operation, and robust to the effects of experimental noise. Furthermore, the system is a non-contact measurement system, and hence does not damage the optical component of interest. The experimental results are found to be in good agreement with the theoretical results. Therefore, the proposed system provides a viable means for the rapid experimental evaluation of the optical characteristics of quartz components.