Related Experiment Video
Updated: Aug 16, 2026

Measurement of X-ray Beam Coherence along Multiple Directions Using 2-D Checkerboard Phase Grating
Published on: October 11, 2016
Observation of two-wave coupling during the formation of POLICRYPS diffraction gratings
Roberto Caputo1, Luciano De Sio, Alessandro Veltri
1Liquid Crystals Laboratory, National Institute for the Physics of Matter, Center of Excellence CEMIF.CAL, Department of Physics, University of Calabria, 87036 Arcavacata di Rende, CS, Italy.
Abstract:
We report on the experimental observation of two-wave mixing that occurs inside a sample between the beams used for the fabrication of polymer-liquid-crystal-polymer slices (POLICRYPS) diffraction gratings. The effect depends on the phase shift between the curing interference pattern and the grating being cured. This shift can be mechanically induced by accidental vibrations of the experimental setup; thus a high setup stability is needed. We devised a mechanism that enables us to control setup vibrations in situ and used it to monitor the experiment. When the mechanically induced shift was significantly small, wave mixing was observed only if the initial intensities of the two curing beams were different from each other.
Related Concept Videos
Interference and Diffraction
X-ray Crystallography
Diffraction
Diffraction is the change in the direction of travel experienced by an electromagnetic wave when it encounters a physical barrier whose dimensions are comparable to those of the wavelength of the light. X-rays are electromagnetic radiation with wavelengths about as long as the distance between neighboring...
The de Broglie Wavelength
Determination of Crystal Structures

