Uniform sized PMMA-beads were deposited as a monolayer on silicon substrates using dip-coating techniques. High-resolution grazing incidence X-ray small angle scattering experiments were performed using a micrometer sized beam (mu-GISAXS) to determine the structure of a highly ordered monolayer with two-dimensional hexagonal arrays. A clear and strong interference pattern coming from the reflection and refraction effects of particles on flat surfaces with small uncorrelated roughnesses is shown. The quantitative analysis and simulations of the X-ray scattering pattern have been performed, and a detailed explanation of the analysis is reported. The results were directly compared and verified with atomic force microscopy (AFM) measurements and their resulting FFT spectra.