Demonstration of synergic Fresnel and Fraunhofer diffraction for application to micrograting fabrication

Diffraction is a manifestation of light at edge due to its wavelike nature. The well-known diffraction phenomena are Fresnel and Fraunhofer, they find variety of applications individually. But the synergy of two phenomena is not studied and understood, which is important to understand the compound optical instruments. This research studies and demonstrates the synergic patterns of Fresnel and Fraunhofer diffractions. The combined diffraction resulted in the patterns similar to Hermite-Gaussian Beam intensity distribution in both simulated and experimental results. Further, the combined phenomena is implemented in speckle lithography to fabricate wide area micro grating patterns which are better than simple speckle diffraction grating patterns. This work may contribute to the deeper understanding of complex diffraction in optical instruments and also shows the way for robust fabrication of micro gratings.