OPTICAL STRAIN SENSOR BASED ON POLYMERIC DIFFRACTION GRATINGS

摘要

We look at an innovative method for the strain, stress measurement on surface. Our project is a simple imaging technique illuminating a polymer (PDMS) grid, attached on specimen, with a large spectra light source, and recording, with a ccd camera, the grid image obtained by diffracting light. Image acquired under stress is subtracted from one without stress giving a colour map of the surface correlated to the stress intensity. This technique arises from asserted optical techniques. Moreover, taking in account the technological progress (polymer, ccd, LEDs), we make the hardware setup very simple because it doesn't need coherent light source and the detector may be a commercial colour ccd.