Effect of quality of opto-mechanical components on fringes of diffraction Lloyd mirror interferometer

Abstract

Diffraction Lloyd mirror interferometer (DLMI) is a relatively new interferometer where interference fringes are generated by superposition of two diffracted beams instead of two geometrical beams of light. The interferometer is suitable for performing basic investigations on diffraction and interference of light. In this work, a number of set-up parameters determining the performance of DLMI including characteristics of knife-edge, quality of mirror, quality of lenses, and effect of algorithm, are experimentally studied and reported for the first time. The effect of these parameters on interference fringes of DLMI is evaluated in terms of change in average intensity, signal to noise ratio (SNR) and contrast of the fringes. By optimizing above parameters, a DLMI set-up is realized and used for characterization of silicon optics fabricated using the single point diamond turning process. The validation results by a commercial optical profiler confirms the effectiveness of DLMI system. This study would provide useful reference for setting up the DLMI system for different applications such as optical profilometry, optical metrology, and to study the diffraction of light etc.